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PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their application in industry

VOL. 32 OCTOBER 1988

Contents

Reactions of Complexes of Platinum Metals with Bio-Molecules

Water Soluble Rhodium Catalysts

The Destruction of Polychlorinated Biphenyls

Chemical Conversion of Carbon Dioxide

The Electrodeposition of Platinum and Platinum Alloys

Ruthenium in Cancer Chemotherapy

Lean-Burn Oxygen Sensor Material

Control of Corrosion in Molten Carbonate Fuel Cells

Flammable Gas Detection

International Congress on Catalysis

Geology and Geochemistry of the Platinum Metals

Abstracts

New Patents

Index to Volume 32

NO. 4

Communications should be addressed to The Editor, Platinum Metals Review

Johnson Matthey Public Limited Company, Hatton Garden, London ECl N 8EE

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Reactions of Complexes of Platinum Metals with Bio-Molecules By Professor A. G. Sykes Department of Chemistry, The University, Newcastle upon Tyne, England

There is a growing recognition of the opportunities that may exist for inorganic biochemistry to contribute to the solution of practical problems that occur in many quite different areas, ranging from mineral extraction to medicine. While most traditional applications of the platinum metals depend upon their ability to remain largely unchanged in highly reactive environments, compounds of these metals can be quite reactive and do react with biological materials. This paper reviews the present position and indicates potential applications.

The reactions of co-ordination complexes of the platinum metals and gold with bio- molecules are relevant to a number of areas. The most important of these currently relates to the medicinal applications of platinum and gold (I), with much potential still to be explored. There are other applications, however, including the laboratory use of platinum metals as heavy-atom markers in the determination of biological macromolecule crystal structures, the use of osmium tetroxide as a specific oxidant and biological stain, and the use of attached ruthenium complexes as spectroscopic labels and probes for studying the electron-transfer reactions of bio-molecules. At the other extreme there is the potential use of micro- organisms in mining processes, and for the selective extraction/recovery of metals from aqueous solutions (pH>2) with cells or cell extracts. The formation of ruthenium as a fusion product in nuclear reactors-the isotopes lo3 Ru and '06 Ru have half lives of 40 days and I year, respectively-and its release into the atmosphere at the time of the Chernobyl mishap, is also relevant.

The use of the Pt(I1) complex cis-platin, cis-[Pt(NH,),CI,l, in chemotherapy was approved as recently as 1979, and this is now the leading anti-cancer drug in the U.S.A. (2 ) . It is used in combination therapy with either adriamycin or bleomycin and binblastine, and

finds applications in the treatment of testicular, ovarian and lung cancers. Cis-platin was the first successful anti-cancer drug, but it does display unpleasant side effects, notably kidney toxicity, nausea and vomiting, as well as neurotoxicity. Second generation drugs, carboplatin [a], which is now approved for use in the U. K., iproplatin [bl and spiroplatin [cl , are less toxic and have better anti-tumour activity. (3). There are additional advantages, thus spiroplatin has higher water solubility, of o.5M, which allows easier administration of the drug. It has been demonstrated that this form of drug is active against three animal tumours with a 30-fold greater activity than cis-platin. The use of carboplatin and iproplatin in synergistic combination with radiotherapy is being investigated. Third generation drugs which contain combinations of malonate and cyclobutanedicarboxylate with amine and diamine ligands, so giving a broad spectrum of activity, are currently under investigation (3, 4). Features of all these drugs are the use of neutral Pt(I1) or Pt(1V) complexes which contain two cis amine groups (primary or secondary, but not tertiary) and two other good cis leaving groups. Thus trans complexes, or cis complexes with poor leaving groups, that is the inert CN-, ONO-, NCS- or I- , are inactive.

Early experiments demonstrated that cis- and trans-platin bind more strongly to RNA than to

Platinum Melals Rev., 1988, 32, (4), 170-178 170

DNA, and least strongly to proteins. However, when their ability to suppress synthesis was measured at low concentrations only the synthesis of DNA was suppressed. It is believed that cis-platin type complexes are effective because they bind to the N-7 positions of two adjacent guanines of the DNA, and that this hinders replication (5-7). A normal cell is able to op- pose this attachment by means of its repair mechanisms, while a tumour cell has a deficien- cy in repair proteins which could otherwise recognise the damaged segment and cause a repair. Analogous trans complexes attach more readily to guanine in the initial stages but decrease in concentration over 24 hour periods due to their removal by repair proteins.

A complex such as cis-platin is believed to remain in the neutral dichloro form in the plasma where the concentration of U- is high (-103mM). After W o n across the cell membrane, in the presence of only ,~IM U- in the cytoplasm, the complex yields the various aquated products (8). Since H,O is a good leaving group the platinum can then attach itself to the DNA.

Rhodium complexes, for example [Rh,(O,CR),l, have been reported to possess some activity as anticaocer agents (9). More generally, when added to cell growth media, complexes mm-[RhX,L,l (where L is a N- heterocyclic such as pyridine) are known to interfere with cell division and cause f3atmnt.a- tion in growth (10). A series of Pd(II) analogue complexes have been tested, but show little promise. It is known that Pd(I1) is more labile than Pt(I1) and this can lead to unavoidable toxicity. The Pd(II) may not even reach the DNA. Recent reports indicate that the four-cmrdinate

Au(1) bis-diphosphine complexes such as [Au(dppe),lU may have a future as anti- cancer agents (11). Titanocene dichloride, [Ti(Cp) , U, 1 , where Cp = cyclopentadienyl, represents an interesting example of an organometallic anti-tumour reagent (12).

Another type of interaction of simple transition-metal complexes with DNA is the intercalation which m r s with planar heterocyclic chromophores. The heterocyclic ligands can insert and stack between base pairs of the DNA helix. Such effects have recently been reviewed by Barton (8). The stereoselective interaction of tris(phenanthr0line) complexes such as [Rubhen) 1 ,+ has for example been noted, the A-[Ru(phen) 1 ,+ complex in- tercalating more favourably than the A isomer, which is inhibited by steric repulsions between H-atoms of the phenanthroline and 0-atoms of the DNA phosphate (13). There are also spectroscopic applications, and the tris (4,7 - diphenylphenanthroline ) ruthenium (11) complex can be used as a sensitive stain for helix conformation in chromosome studies using fluorescence techniques. Electron- transfer reactions of intercalated metal complexes, for example the Fe(I1)-EDTA derivative complex which has the aromatic methidium intercalator attached by a short hydrocarbon chain, can with oxygen give rise to single strand DNA scissions (14). The Fe(I1) activates the oxygen to yield 0,- or OH' radicals (or Fe-0, complexes), which at high local concentrations can bring about cleavage of the sugar phosphate backbone.

The binding of platinum complexes to cytochrome c has recently been studied. A metalloprotein has many advantages in such

Platinum Me& Rm., 1988, 32, (4) 171

investigations because structural features have number of reagents, possibly with some pertur- been extensively explored, and the presence of bation of conformation, is however of low reac- the metal helps in demonstrating whether at- tivity with [Pt(terpy)ClI+ . This is particularly tachment of a second metal has any disruptive interesting since, in separate studies with amino effects on the protein structure. Kostili has acids or small peptides as entering ligands, the shown that [PtCI I - and [ Pt(z-Fpy) , C1 , I , complex is completely selective towards cys- where 2-Fpy is 2-fluoropyridine, cross-link teine. From a recent crystallographic study on horse cytochrome c by co-ordinating to the iso-1-cytochrome c, it has been confirmed that S-atom of the thioether side chain of a the Cysroz is buried and in a hydrophobic methionine, [dl, in this case Met65 (15). region. The binding is illustrated in [el. With Recently it has been demonstrated that in- [Pt(terpy)ClP however, selective covalent cubation of horse cytochrome c with the Rh(I1) labelling of histidine residues, tfl, His33 (major dimer [Rh,(O,CCH,),l for 2 days at pH 7 (but binding) and His26 (minor binding) is observ- not pH 5) gives the diprotein complex ed, with no labelling of Met65 (16). The dif- [Rh,(O,CCH,),l(cyt c ) ~ , [gl (19). Attachment ference in behaviour can be attributed to the steric demands of the terpyridine ligand, which prevent it binding to the thioether

A % O G - G f l

*o’ I group. Interestingly, in the case of the complex [Pt(NH,) H, 01 + preliminary results

I >.. .J H N V N - Rh‘- R6’- N-NH

indicate that binding occurs 55 per cent to the methionine and 45 per cent to histidine His33 (17). yo [gl

is at a histidine residue, and model complexes

Im = imidazole, with the Im co-ordinated in the axial position. Since no reaction is observed with tuna cytochrome c, which does not have the His33 residue, it has been concluded that attachment is at this residue on horse cytochrome c. Enhanced stability of the dimer

[el adduct to hydrolysis, as compared to

steric bulk of the protein with the possibility of some H-bonding in addition.

I CH2 I Gold(1) drugs are extensively used in the

HF=F treatment of rheumatoid arthritis although C again the mechanism is not well understood H (20). The most commonly used drugs are

Myochrisin (gold sodium thiomalate) and The reaction of cytochrome c from Candtda Solganal (gold thioglucose), which are ad-

krusei and baker’s yeast with [Pt(terpy)Cl] + ministered by weekly or monthly intramuscular has also been studied (IS), when modification injections. The structures of these compounds of surface His33 and His39 residues (which are are not known precisely. The newer drug in hydrophilic regions) is observed, but His26 Auranofin, the gold triethyl phosphine (in a hydrophobic pocket) is largely shielded. thioglucose complex, can be administered oral- The cysteine residue, HS-CH,-R (pK,- 8.3), ly (11). It seems likely that the role of the drug Cys102 in baker’s yeast, which is reactive to a is anti-inflamatory and/or anti-enzymatic, and

t L CH3 [Rh,(O,CCH,),(Im),I can be prepared, where 0, I \ H3N- CH-COO-

I s- Pt -s

I :.s\ (CH2)2

H3C ‘ L I ‘0

QF L = C I - or

CH3

Met [ dl

t [Rh,(O,CCH,),(Im),l, is attributed to the H3N -CH -COO-

:Nb ,NH

His Ifl

Platinum Metals Rev., 1988, 32, (4) 172

A c O

The Structure of Auranofin

that the body's immune responses are effected in some way. There is some evidence that gold accumulates in the red blood cells. The uptake of Et,PAu+ into such cells has been investigated (21). With concentrations of Et , PAu + (up to 9mM) in excess of that achieved in therapeutic applications (25-5opM), interactions with intracellular glutathione, and a second site identified as the cysteine p-93 of hemoglobin, takes place. Excess Et PAu' also reacts at weaker binding sites (nitrogen or thioether ligands). Comparisons have been made with the binding of gold at weak and strong binding sites identified on serum albumin (22). A facile interprotein gold transfer from gold modified hemoglobin to the -SH containing component of serum albumin has been noted in this work. The application of I'P NMR spectroscopy has been important in these studies.

The use of heavy-atom markers was a major breakthrough in the X-ray structure determination of large bio-molecules. In this process the crystalline material is derivatised for phase determination by a method of isomorphous replacement (23). Procedures involve soaking the crystal in mother liquor containing the heavy-atom marker, or reacting the two together prior to crystallisation. In order to obtain the necessary information, the native diffraction intensities and those obtained from crystals derivatised in at least two unique sites have to be determined.

The reactivities of individual amino acids has been summarised by Petsko and different classes of heavy-atoms defined according to their affinities (23). The most extensively used reagent is [PtCl,12- which is capable of binding to methionine, histidine and cysteine

residues, none of which are present in large numbers in metalloproteins, and in some cases provide unique sites. Some care is required because mother liquors high in [CI-I or [SO, 2-1 concentrations could impede efficient binding of [PtCI,lz-, which is first converted to aqua and hydroxo forms of neutral or I + charge before attaching to the residues indicated (25). Other complexes which will react in the same way are [Pt(N02),12-, [Pt(NH,),CI,l or IPt(en)CI,l, where en = ethylenediamine, whereas the inertness of [Pt(CN),12- ensures its retention as a 2- anion which will interact, if at all, with positively charged residues (lysines, arginines and at pH<7 histidines) by electrostatic associa- tion. A wide range of mercury compounds including for example ethylmercury phosphate, are known to bind to cysteine or histidine residues (26), and can, because of their structure, readily penetrate into proteins to react with buried side chains. Lanthanides (often samarium because of its large anomalous scat- tering signal) and uranium compounds will bind at carboxylate residues, although buffers other than phosphate (which will bind to such metals) should be used. The complex ion K, [HgI, 1, which in aqueous solution generates trigonal [HgI,] -, can bind electrostatically to cations or, because of its flat structure, penetrate into proteins (23).

The strong oxidant osmium tetroxide, which is more stable than RuO, , is used as a reagent to give syn dihydroxy addition from the less hindered side of a double bond (27). The reagent adds rather slowly but quantitatively to give the intermediate as illustrated [il.

I I - c = c - + OSOL - c - c - I I I I Iil

HO OH I I

I I - - C - C - -

The latter is subsequently decomposed with sodium sulphite in, for example, ethanol. The same reaction can be carried out more economically with hydrogen peroxide using


osmium tetroxide as a catalyst. The procedure finds commercial use in small scale prepara- tions of scarce materials. Osmium tetroxide is highly toxic however, and particularly hazar- dous to the eyes because of its ready reaction with organic matter to give a black oxide, a pro- perty which is utilised in its application as a f=- ative and stain in electron microscopy. This is probably due to its ability to react with unsaturated fatty acid side chains of lipids (24). Binding of [OsO, 1 * - to cis diols has been used in the X-ray analysis of t-RNA where binding is most likely to the 3'-ribose, [ii] (28).

+ K ~ O S O L - L: >OSQ ; 1:: Iiil

A procedure for detecting genetic changes in new strains of viruses has recently been reported using hydroxylamine and osmium tetroxide (29).

Attachment of pentaammineruthenium(II1) to the N-3 position of the imidazole side chain of a histidine residue, [hl in proteins was reported

,CH2CHCO$ I

HN-C NH; / 1 \\

HC4,CH N

NH3 [hl

by Matthews and coworkers in 1978 (30). Earlier in the 1970s it had been shown that imidazole and histidine complexes readily form in aqueous solution, and are extremely stable at neutral and acidic pHs. The first studies were with the ribonuclease A protein which has four histidine residues. Three derivatives each containing a single (NH,), Ru-histidine complex were synthesised and purified. It was found that sensitivity of the charge-transfer spectrum of one of these derivatives to temperature and urea-induced unfolding could be used to explore conformational changes in the vicinity of the complex (31). It has also been shown that fluorescent energy transfer between trypto- phans and a (NH,),Ru attached to a histidine

on a-lytic protease and lysozyme can be used to determine inter-residue distances (I 5.5 and 11.8& respectively) (32). At about the same time the preparation and characterisation of a (NH,) , Ru(II1) to histidine-33 derivative of horse cytochrome c was reported (33). This type of attachment to electron transport metalloproteins has now been carried out in a number of cases in order to explore fued distance (crystallographically defined for the unmodified protein) electron transfer from the attached ruthenium (as Ru(II)), to the active site in its oxidised form, heme Fe(II1) in the case of cytochrome c (34). A feature of all these studies is the special affinity of (NH , ) Ru for histidine in preference to other amino acid residues.

Relevant to these studies is the earlier Taube work, and the observation that both Ru(I1) and Ru(II1) are inert to substitution. Modification is carried out using a -50-fold excess of [Ru(NH , ) H, 01 2+ [iiil ,

IRu(NH,),H,OI2+ + His-Protein - (NH,),RuHis-Protein Iiiil

after which the reaction is terminated by chromatographic filtration to remove excess of the ruthenium reagent. The fully oxidised form Ru(III)Fe(III) is obtained by oxidation with [Fe(CN), 1 3- after which further purification (by FPLC) and characterisation is carried out. In order to study the intramolecular electron- transfer process, rapid pulse-radiolysis or flash- photolysis in situ reduction has to be achieved to generate the Ru(II)Fe(III) combination; about 10 per cent reduction is appropriate. The intramolecular electron-transfer process [ivl,

Ru(ll)Fe( Ill) - Ru( III)Fe( II) [ivl

can then be monitored spectrophotometrically . In the cytochrome c case protein concentrations are sufficiently dilute so that there is no contribution from the intermolecular (bimolecular) path [vl.

Ru(II)Fe(lll) + Ru(lll)Fe(lll) - Ru(lll)Fe(lll) + Ru(lll)Fe(ll) Ivl

The reduction potentials for the couples

Platinum Metals Rev. , 1988, 32, (4) 174

[Ru(NH,),(His)12+/’+ (0.08V) and cytochrome c (II)/(III) (0.26V) ensure that there is a positive driving force for [ivl. An interesting variation on this experiment is to attach other ligands to the ruthenium which have much more strongly oxidising couples, for example, [R~(NH,),(isn)(H,0)1~+’~+ (o.emV) or [Ru(NH,),(py)(H,O)I ,+’I+ (o.33mV), so that a variation on intramolecular electron transfer [vil can be monitored. This type of study is at present under investigation.

Ru(lll)Fe(ll) - Ru(ll)Fe(lll) [vil

With hind-sight, cytochrome c(1I) with its high overall positive charge (estimated as + 8 at pH - 7) was not in fact a good choice in the first instance for modification with a positively charged complex. The time for modification (24-72h) is substantially longer than that required for acidic negatively charged proteins. Thus with the single copper protein plastocyanin the procedure for [iii] requires only 20

minutes in the case of the acidic plastocyanin (charge 9 - ) from the green algal source Scenedesmus obliquus, but requires approximately 4 hours for the basic plastocyanin (charge I + ) from the blue-green algal source Anabaena variabilis (35).

Modification of proteins by the attachment of (NH,),Ru is not trivial, and extensive characterisation of the products is required for each new protein studied to ensure that attachment is indeed at a histidine residue, and (if more than one histidine) which histidine is involved (3 s). Techniques used include Induc- tively Coupled Plasma (ICP) atomic emission spectroscopy to determine the metal content, NMR to demonstrate that the histidine C,H proton resonance is no longer present due to the line broadening effect of paramagnetic Ru(III), and testing with diethyl pyrocarbonate (DEPC) for modification of a histidine (with attendant U.V. spectrophotometric changes) which can no longer occur when ruthenium is present. There is no evidence to suggest that ruthenium attachment is at all disruptive.

Three different types of electron-transport protein have been modified and will be referred

N lHis87)

Fig. 1 Structural model showing selected parts and the relative orientations (with edge to edge separation) of the donor and acceptor sites in ruthenium-modified A. variabilis plastocyanin (Ref. 35)

to. Plastocyanin (35) and azurin (36) each have a single copper active site, and utilise Cu(II)/Cu(I) redox states. High-potential iron- sulphur protein (HIPIP) has a cuboidal Fe, s, cluster which can be either Fe,S,’+”+ (37), while both the cytochromes c and cs5, contain a heme Fe and have Fe(III)/Fe(II) stable states (38, 39). It should be noted that not all proteins have histidine residues, and that not all histidines are modified by ruthenium. For example in the case of cytochrome c, His33 is readily modified but His26 is not.

Some care is required in defining the distance (d) for intramolecular electron transfer from the Ru(I1). For the copper proteins the Cu-S (cysteine) is likely to be the lead-in group, and since there is delocalisation between copper and sulphur the relevant distance is to the S-atom, Figure I (35). Similarly there is delocalisation at the imidazole ring of the histidine to which the ruthenium is attached, and the nearest point of the imidazole to the active site is considered relevant. A computer graphics representation for P. srutzeri cytochrome c5,, is illustrated in Figure 2 (39). The direct polypeptide link between His47 and the heme is circuitous in the extreme, and cannot be relevant. Electron transfer to the axially co- ordinated Met61 has been assumed, but transfer to the heme ring, which is strongly electron delocalised, is also possible. For HIPIP, Figure 3, the distance to the nearest point of the Fe,S, cube, one of the ~.c,-sulphido


\ His16 Fig. 2 Structural model showing selected parts and relative orientations of the donor and acceptor heme and His47 (with R u ( N H ~ ) ~ attached) sites in P. stutreri cytochrome csJl. The buried pro- pionate attached to the heme at position 7 is also indicated (Ref. 39)

ligands, is considered relevant (37). Of all the studies to date HIPIP is the only protein in which the modified histidine is linked directly by a short polypeptide chain to the active site (Cys43 is co-ordinated to the Fe,S,). The through bond distance (saturated bonds!) is 13A, whereas the through space distance is only 7.9A. No benefits seem to accrue from this type of attachment.

Distances (d) for electron transfer coinciden- tally fall into two groups which are close to 12A and 8A, respectively, and values for the thermodynamic driving force (AEO) lie in a fairly narrow range 180-3mmV, see the Table. At

the outset the distance separating the Ru(I1) from the metal active site, and the driving force were expected to be the prime rate determining factors. The results obtained clearly indicate that this is not so and that biological electron transfer is far from simple. It is concluded that protein structure and the nature of the intervening polypeptide material must be important. Of current interest is just how influential any intervening aromatic residues might be. Further results from this work are awaited.

Sperm-whale myoglobin, an oxygen binding protein, has also been used by the Gray group to explore factors affecting electron transfer

I p 1 0

\ I

v

Fig. 3 Structural model showing selected parts and relative orientations of the Fe,S, active site of high-potential iron- sulphur protein, which is co- ordinated by Cys43, and His42 which is ruthenium modified (Ref. 37)

Met49


A Comparison of Rate Constants for Intramolecular Electron Transfer from Ru(I1) in Ruthenium-Modified Metalloproteins I

Protein

Cytochrome c (horse) Azurin (P.a.) Plastocyanin ( S o . ) Plastocyanin (A. v. Cytochrome c, 5 , (P.s. HlPlP (C.V.)

Site of Modification

His33 His83 His59 His59 His47 His42

d (A)

11.8 11.8

10-12 11.9

7.9 7.9

AE O

(mV)

1 8 0 240 300 2 6 0 200 270

k (S-

30, 53a 1.9

<0.26 <0.08 1 3 1 8b

Reference

38 36 3 5 3 5 3 9 3 7

a Values obtained by flash photolysis and pulse radiolysis. respectively

Values 1 and 13s-’ have been obtained by the Gray group for two HlPlPs modified at His42

reactivity. This protein has four surface histidines His12, His48, His81 and His116 (all at different distances 14.6-22.d from the heme Fe) each of which can be ruthenium- modified. Four different singly-modified Ru(NH,), derivatives have been prepared, and in this case a rate constant (k) against distance (d) relationship In k versus d appears to hold. Unlike the studies with electron transport proteins reorganisation energy requirements at the active site are more significant. This is because metMb has an axial H,O ligand whereas deoxyMb is five co-ordinate with no H,O. The myoglobin intramolecular reactions are somewhat slower therefore on this account.

The successful attachment of ruthenium to proteins and various applications that have resulted poses the question: if ruthenium, why not other metals? As far as electron transfer studies are concerned it is of crucial importance that the ruthenium stays attached (it is substitution-inert t,>>I min) in both the Ru(I1) and Ru(II1) oxidation states, and that the reduction potentials are of the required magnitude. Another metal which may behave in this way is osmium, but here very little is known of the (11) state solution chemistry. As far as the other platinum metals are concerned Rh(II1) and Ir(II1) are too inert to be readily attached, and the (11) states are comparatively rare. In the case of palladium and platinum the stable oxidation states (11) and (Iv) are separated by two electrons.

Methods for the selective extraction of gold and platinum ions from an aqueous solution at pH>2 with cells or cell extracts of a micro- organism (green or blue-green algae) (40) and fungi (41), and subsequent elution with S- donor ligands are being actively explored. This is the subject of a recent U.S. patent (40). Fungi have also be used to remove precious metals from dilute aqueous solutions (41).

Finally, mention should perhaps be made here of the application of bacterial leaching processes in the extraction of certain metals from their ores which in the case of uranium and copper is already being exploited commercially (@,

43). 7liobacillus fernoxidam is for example able to oxidise iron pyrites (FeS) to soluble Fe” and SO:- with very beneficial results (43). The use of other closely related micro- organisms, which are active in hot spring regions, in order to make available the metallic gold present in pyrites deposits is currently receiving attention (4).

This short review illustrates the wide range of potential applications of platinum metal compounds centering around their reactivity with a variety of different bio-molecules. Relevant areas stretch from laboratory applications to medicine via the further development of procedures for mining and recovery. Many of the applications make use of specific chemical properties identified in the already well studied and extensive inorganic solution chemistry of these elements.


Additional abbreviations used in the text, without explanation: dppe = bis(diphenylphosphho)ethylene, EDTA = ethylenediamine tetraacetic acid, terpy = terpyridine, py = pyridine, isn = isonicotinamide, Mb = myoglobin.

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31 C. R. Matthew, P. M. Erickson and C. L. Froebe, Bwchim.Bwphys.Acta, 1980, 624, 499

32 J. Recchia, C. R. Matthews, M. -J. Rhee and W. D. Horrocks, Jr., Biochim. Biophys.Acta, 1982,

33 K. M. Yocum, J. B. Shelton, J. R. Shelton, W. A. Schroeder, G. Worosila, S. S. Isied, E. Bor- dignon and H. B. Gray, Pmc.Natl.Acad. Sci.U.S.A., 1982, 79, 7052

702, 105

34 A. G. Sykes, Chem.Br., 1988, 24, 551 35 M. P. Jackman, J. McGinnis, R. Powls, G. A.

Salmon and A. G. Sykes, J.Am. Chem.Soc., 1988, 1x0, 5880

36 H. B. Gray, Chem.Soc.Rev., 1986, IS, I7 37 M. P. Jackman, M.-C. Lim, G. A. Salmon and A.

G. Sykes, J.Chem.Soc., Dalton Trans., 1988, in press

38 S. L. Mayo, W. R. Ellis, R. J. Gutchley and H. B. Gray, Science, 1986,233,948; R. Bechtold, M. B. Gardineer, A. Kazmi, B. van Hemelryck and S . S . Isied, J.Phys.Chem., 1986, 90, 3800

39 P. Osvath, G. A. Salmon and A. G. Sykes, J.Am.Chem.Soc., 1988, 1x0, in press

40 Ceskoslovenska Akademie Ved, U.S. Patent

41 Engelhard Minerals & Chemicals Corp., U.S.

42 Continental Oil Company, U.S. Patent

43 W. J. Ingledew, Bwchim.Bwphys.Acta, 1982, 683, 89; C. L. Brierley, Sci.Amer., 1982,42, 247

eq D. P. Kelley, P. R. Norris and C. L. Brierley, “Microbiological methods for Extraction and Recovery of Metals in Microbial Technology: Current State, Future Prospects”, Soc. Gen. Microbiol. Symp. 29

3,725491; I973

Patent 4,293,333; 1981

329379520; 1976


Water S oluble Rho &urn Catalysts A HYDROFORMYLATION SYSTEM FOR THE MANUFACTURE OF ALDEHYDES FOR THE FINE CHEMICALS MARKET

By M. J. H. Russell Johnson Matthey, Materials Technology Division, Royston

The rhodium catalysed hydroformylation reaction is one of the most widely used industrial applications of homogenous catalysis to employ platinum group metals. Potential limitations in the application of this technology to molecules which are heat sensitive or have high boiling points are the stability of the catalyst and the ability to separate the catalyst from the products. A means of circumventing these limitations is described. This involves locating the catalyst in an aqueous liquid phase, and it enables viable reaction rates to be achieved at moderate temperatures and pressures.

Hydroformylation is the reaction of an alkene, hydrogen and carbon monoxide to generate an aldehyde, as shown in Figure I. While the reaction is energetically favourable it only proceeds in the presence of a catalyst. A number of different metal complexes have been investigated as potential catalysts, but the only ones with sufficient activity to be useful in- dustrially are those of cobalt and rhodium. The relative activities of these metals are given in Table I.

The hydroformylation reaction was first reported by Roelen in 1938 during a study of Fischer Tropsch catalysts (I). Later it was realised that the active catalyst was a hydridocarbonylcobalt species, and in the period 1945 to 1951 a number of processes employing homogeneous cobalt catalysts were developed for the production of detergent and plasticiser alcohols.

It was demonstrated during the 1950s that rhodium compounds such as rhodium oxide were highly active as hydroformylation catalysts, although the ratio of normal:iso aldehydes was lower than those obtained with commercial cobalt systems. However in the 1960s Wilkinson’s group at Imperial College, London, and Pruett’s group at Union Carbide found, independently, that rhodium com-

pounds containing organophosphines could convert alkenes to aldehydes at mild temperatures and pressures, and with high selectivity to linear aldehydes (2,3). An exten- tion of this work resulted in the commercial ex- ploitation of the rhodium Low Pressure 0x0 (LPO) process by Union Carbide, Davy McKee and Johnson Manhey. The principal industrial application of this process is the hydroformylation of propylene to butyraldeyde. This

R d

1 R V C H O (normal)

+

(is01 RTHo -

ALDEHYDE Hydrogenation/ v l d o l condensation

ALCOHOL DIMER Fig. 1 Hydroformylation is the reaction of an akene with hydrogen and carbon monoxide to yield an aldehyde, the rhodium catalysed reaction being highly selective to linear aldehydes

Platinum Metals Rev., 1988, 32, (4), 179-186 179

[4

Table I

Relative Activities of Metals for the Hydroformylation Reaction

Metal

Rhodium

Cobalt - - _ _ _ _ _ - _ _ _ _ _ _

Ruthenium, Platinum

Manganese

Iron

Chromium, Molybdenum, Tungsten, Nickel

~

Activity

103-1 0 4

1 - _ _ _ _ - .

1 0 - 2

1 0 - 4

10-6

0

primary product can be converted to the plasticiser alcohol 2-ethylhexanol, via aldol con- densationhydrogenation, or to butanol. Since the LPO process was introduced commercially in the 1970s it has been immensely successful. It has been used for the production of over one million tomes of butyraldehyde, and is licensed to 12 companies in 9 countries, Table 11.

In addition to the development being timely with respect to feedstock costs, the commercial success of the process can be attributed to a number of technical features: [ I 1 The high activity of rhodium complexes. 121 The presence of a large excess of

triphenylphosphine contributes to the high selectivity to aldehydes, in particular the desired product n-butyraldehyde, and it also suppresses hydrogenation.

L3l In addition, the presence of triphenylphosphine renders the catalyst ther- mally stable and confers longevity on the catalyst, while the low volatility of the catalyst means that the product can be stripped from the reactor with a minimal rhodium loss, of less than Ippm. An efficient reactant purification system eliminates catalyst poisons and extends the catalyst lifetime.

hrerall the process provides a graphic example of how a relatively expensive platinum group metal catalyst can successfully compete

with a significantly cheaper cobalt catalyst. On a commercial scale, the rhodium and

cobalt catalyst systems are to some extent com- plementary in that rhodium catalysts are only suitable for the hydroformylation of low molecular weight alkenes, whereas the cobalt systems can be applied to the hydroformylation of high molecular weight feedstocks and are particularly attractive where alcohols are the desired products, Table 111.

Limitations to the rhodium process result from the availability of methods of separating the catalyst from the product. In the production of butyraldehyde the product is distilled out of the reactor at low temperatures which do not cause catalyst degradation. For higher molecular weight products higher temperatures are required, and at temperatures greater than 12ooC severe catalyst degradation can occur, Table IV. Thus if rhodium catalysts are to be used commercially for the production of compounds of interest to the detergent and aroma industry, an alternative strategy is required.

An approach which has attracted a great deal of attention from research workers in- vestigating hydroformylation and related reactions is the use of chemically anchored catalysts. After some preliminary work in this

Table II

Low Pressure 0 x 0 Plants

Company

Union Carbide Tenneco Neste 0x0 Huels CNTIC TSK Kyowa Yuka Chisso Lucky Polimex Nan Ya Plastics Oxochimie (planned)

Location

Texas, U.S.A. Texas, U.S.A. Sweden West Germany China (2) Japan Japan Japan South Korea Poland Taiwan France


Table 111

Commercial Hydroformylation Processes

Catalyst Temperature, OC Pressure, bars Products Normal : branched aldehyde ratio n-product yield, per cent Aldehyde yield, per cent Alkanes, per cent Other by-products, per cent Catalyst costs

Cobalt

[HColCO),I 110-180 200-300 Aldehydes

2-4 67 90

1 9

* Aldehyde and Alcohol

area Johnson Matthey decided against this approach, for a variety of reasons, including: [a] The difficulty of producing a catalyst with

reproducible activity and selectivity, which implied that catalyst costs would be extremely high.

[bl Many of the heterogenised catalysts were more air sensitive than their homogeneous analogues.

[c] Metal was slowly lost from the catalyst, and in many cases the metal could not be recovered in a cost effective manner.

[d] Neighbouring group effects such as chelation, arising from a high surface concentration of organophosphines, caused slower rates of reaction.

We were attracted to the idea of utilising a water soluble catalyst system, with a view to locating the catalyst in the aqueous phase and the feedstock and product in the organic phase. We concentrated on rhodium catalyst systems, with a few less successful diversions into ruthenium and platinum systems. The standard which we wished to match in terms of rate and selectivity was the triphenylphosphine- modified rhodium homogeneous system, and we chose dodec-I-ene as a convenient model substrate.

Our first task was to devise a water-soluble phosphine ligand which located the rhodium in the aqueous phase, yet was similar to

Modified Cobalt

[HCo(CO),(PBu,)I 160-200

50- 1 0 0 Alcohols

7 67

15 5

Similar

a0

Rhodium Low Pressure

[HRh(COI(PPh,l,l 1 0 0 <20

Aldehydes >10

90 9a 0.9 1 .o

triphenylphosphine. The sulphonated triphenylphosphine-rhodium systems which had been investigated by RhBne Poulenc and by Wilkinson gave rise to extremely slow rates of reaction at moderate pressures, and we selected carboxylated triphenylphosphines as ligands. We observed measurable rates at 8ooC and about 6 atmospheres hydrogen-carbon monoxide with a ten-fold molar excess of carboxylated phosphine over rhodium.

At the conception of the project we had ap- preciated that we would need to use some “special” effect to enhance the rate in the two liquids system relative to the homogeneous system. For the system containing two liquid phases, mass transfer control is likely to

Table IV

Catalyst Solution Degradation

Phosphido bridged rhodium species

Alkyl diphenylphosphine complexes

Triphenylphosphine oxide

Benzene, benzaldehyde

Heavy organics


Tabla V

Hydroformylation of Dodec-1-ene SurfactantlPhase Transfer Agent Variation 1

Surfactantlphase I transfer agent

1 8-cr0wn-6'~'

PhCH,N+Bu,"CI-

Bu,"N+CI-

Bu,"N+OH-

C,,H,, +PBu",Br-

Aliquat 336 (C,,H,, ),N+MeBr-

Benzethonium chloride'b1

Tween 61

Span 40

Sodium dodecyl sulphate

Brij 35

CTAB C,,H,,N+Me,Br-

Cl,H,,N+Me3Br-

Ciz H z s (OCHz CHz ),,OH

selectivity n:i

3

7

6

6

6

2

5

4

5

4

14

115

70

60

otal aldehyde: per cent

88

76

73

90

64

78

82

72

80

80

87

76

78

70

Colour of organic phase

yellow

yellow

yellow

yellow

deep purple

deep purple

yellow

yellow

yellow

yellow

colourless

colourless

colourless

pale yellow

Colour of aqueous phase

yellow

brown

brown

brown

colourless

colourless

colourless

colourless

colourless

brown

brown

yellow

clear orange

yellow

la' In p H l O KHCOI + KOH buffei All runs a s BOOC, 5.1-5.5 atrns 1:l H,:CO, organic:aqueous= 1:2, organic=dodec-1-ene 11Ogl unless otherwise stated, aqueous=pHlO NaHCO, buffer

Ibl Benzethonium chloride =

dominate, which contrasts with the homogeneous hydroformylation system where kinetic control is operative.

At this time there was a burgeoning interest in the use of phase transfer agents in organic synthesis, and there were many reports that surfactant systems would induce micelle formation and promote liquid-liquid transport. Ac- cordingly we set out to investigate the effect of a range of these amphiphilic reagents on the two liquid phase hydroformylation reaction, see Figure 2 and Table V. For those reagents with a high affinity for organic solvents, high rates of reaction were obtained, as measured by conversion to aldehydes and by hydrogedcarbon

monoxide uptake. However, the reaction effec- tively took place in the organic phase, with high concentrations of rhodium observed in the organic. For quaternary ammonium salts (Quat.) of the type RN+Me,X- (R=C,,-C,, alkyl, X=halide, acetate etc), under basic conditions reasonable reaction rates were obtained, as shown in Table VI. These rates were about half that of the homogeneous rhodium system at 80--100~C and about 6 atmospheres hydrogen-carbon monoxide (4). In the more favourable cases rhodium loss to

the organic phase was lower than xppm. Dependent on the R group, rapid phase separation could be achieved. Alternatively, a fairly


Table VI

Effect of Surfactants

44

2

78

0.5

73

Surfactant

73

6

20

-

22

None

C,,H,,N+Me,Br-

None

C,,H,,N+Me,Br-

None

C,,H,,N +Me,Br-

Substrate

Hex-1 -ene

Hex-1 -ene

Dodec-1 -ene

Dodec-1 -ene

Hexadec-1 -ene

Hexadec-1 -ene

Time, hours

3

1

3

1

3

1 -

Conversion, per cent n:i

l 7 Efficiency, per cent

-

85

-

91

-

8 9

Conditions: [Rhlaq=300ppm, 4-Ph2PC.H.COOH, P R h = 1 O : l . C,,H,NMe,Br:Rh=ZO:l in pHlO buffer at 80°C, 5.5 atms 1 : l H,:CO

stable emulsion could be obtained. Using a particular reactor conformation it was possible to achieve extremely high selectivities to normal aldehydes, with normal:iso ratios in the region

Rhodium loss to the organic phase, and selectivity both to total aldehydes and normal aldehydes were highly dependent on the organic phase composition, the reactor system and the rate of stirring. The selectivity to total aldehydes was dependent on the organic phase composition, which can be explained in terms of the relative solubility of carbon monoxide. High selectivity to normal aldehydes was promoted when relatively poor mixing of the liquid phases occurred, and poor mixing also mini- mised rhodium loss.

The fact that the mixing of the two liquid phases plays such an important part in the course of the reaction can be interpreted in terms of the formation of metastable aggregates. The pH of the aqueous phase is basic under reaction conditions, and in these cir- cumstances the carboxylated phosphine is in an anionic form. It is possible to imagine an organised array containing catalyst, surfactant and substrate molecules (Figure 3). Under these highly organised conditions the approach of the polar alkene group will be favoured sterically for a I-alkene, and likewise the forma-

of 300.

tion of a linear alkyl and acyl will be favoured over the branched species for the two phase system relative to the homogeneous system. In this way it is possible to rationalise the extremely high normal:iso ratios that are obtained under poor mixing conditions, when the formation of highly organised assemblies is favoured.

Some work was carried out in elucidating the reaction mechanism. Through varying the hydrogen to carbon monoxide ratio it was found that at low partial pressures of carbon monoxide the normal:iso ratio is extremely high, with moderate selectivity to total aldehydes; increasing this partial pressure

I O r g a n i c substrate/product 1 A m p hiphi I i c reagent

Aqueous catalyst

Fig. 2 The effect of a range of amphiphilic (phase transfer or surfactant) reagents has been investigated as a means of enhancing reaction rates and reducing rhodium loss to the organic phase


Fig. 3 When quaternary ammonium salts are present at levels greater than the critical micelle concentration, aggregates are formed; (a) depicts a spherical assembly with the cationic surfactant molecules attracted to the negatively charged aqueous micro droplets, (n) represents schematically the greater steric interactions which occur when a branched alkyl or acyl is formed

results in a decrease in normal:iso, but an increase in selectivity to total aldehydes. This indicates that it is not the initial attack of hydride to alkene which determines the ratio of linear to branched aldehydes, but that there is a pathway

for the interconversion of iso-alkyl and normal- acyl compounds where the relative proportions of each are determinable by the partial pressure of carbon monoxide. The accepted hydroformylation pathway is given in Figure 4.

Tabla V I I

Comparison of Rhodium Water-Soluble Catalyst Syetems

Ligand

Rhodium, ppm

Ligand : Rhodium

Additive (A:Rh)

PH

Buffer

Total pressure, atmospheres

Temperature, OC

Efficiency, per cent

Selectivity, per cent

Normal:lso

PPh,C,H,CO,H

<300

10

Quat. (20: 1 )

10

bicarbonate

10

100

95

90

100 to 20

P(C,H,SO,I,(M+),

300-700

20-40

none

7-a

phosphate

>60

>125

<95

<go

12 (for 1-hexene)


H

H

I ,\\"

H-Rh I 'P

I P-Rh-P

I co

@ O k R

PR P-Rh-P

c o

co

I

PR

I t O F R

P-Rh-P

co I

\ H2

P-Rh-P I co

Fig. 4 The widely accepted mechanism for the hydroformylation of alkenes using rhodium catalysts is depicted. It involves the dissociation of a phosphine to give a sixteen electron species (l), followed by co-ordination of an alkene and the formation of linear and branched acyls. The mechanism permits the interconversion of branched alkyl (a) and linear acyl(f) species. Reductive elimination results in the formation of normal and iso aldehydes, and regenerates (1)


In this mechanism there is a route for the interconversion of branched alkyl (a) and linear acyl ( f ) species, which is consistent with the observations made above. Thus by modifying the microstructure of the liquid assembly, through the addition of surface active agents and the polarity of the organic solvent, it is possible to effect high selectivities to total aldehydes.

Other features which make this system attractive are that high normaliso ratios can be achieved at relatively low phosphine concentrations (less than 1/10 of that of the conventional triphenylphosphine-rhodium system). Minimal losses of phosphine, surfactant and rhodium occur, and the phosphine and surfactant are not degraded under the reaction conditions.

A related water soluble system has been developed by Rhdne Poulenc and Ruhr Chemie (5). This system utilises sulphonated triphenylphosphine as a water solubilising ligand and operates at higher temperatures and pressures than the truly homogeneous rhodium-phosphine. A comparison of the sulphonated and carboxylated phosphine systems is given in Table VII.

The trisulphonated triphenylphosphine- rhodium catalyst is operated commercially by Ruhr Chemie for the hydroformylation of propylene and the complexity of these reaction systems suggests that the design of an industrial plant for the hydroformylation of high molecular weight alkenes will not be trivial. However, the mild operating conditions which result from the use of the 4-diphenylphosphino- benzoate-rhodium catalyst, together with the high selectivities attained, mean that this system has considerable potential for the manufacture of aldehydes in the fine organic chemicals markets.

Acknowledgements I acknowledge and thank my colleagues at the

Johnson Matthey Technology Centre for their assistance, in particular Dr. B. A. Murrer.

References I 0. Roelen, German Patent 849,548; 1938 2 D. Evans, J. A. Osborn and G. Wdkinson,

3 R. L. Pruett and J. A. Smith, J. Org. Chem.,

4 M. J. H. Russell and B. A. Murrer, British

5 E. G . Kuntz, Chemtech, 1987, 17, (9), 570

J.Chem.Soc.A, 1968, (12), 3133

1969, 34, (2), 327

Patent 2,085,874B

The Destruction of Polychlorinated Biphenyls In an earlier issue of this journal attention

was drawn to the possibility of disposing of per- sistent aromatic pollutants, including polychlorodibenzo-p-dioxins (PCDDs) , by an oxidation process which utilised catalytic quantities of ruthenium tetroxide (I).

Since that time there has been a growing awareness of the potential danger to human health posed by polychlorinated biphenyls (PCBs), compounds with similar structures to the FCDDs. PCBs were widely used in the past as insulators in electrical transformers and capacitors. They are very stable, and therefore difficult to get rid of when they are no longer required. Burial in a landfill site cannot be regarded as a permanent solution as leaching in- to the drainge system may occur. Incineration, the usual alternative method of disposal, requires temperatures of around 12w°C and risks the possibility that even more toxic polychlorinated dibenzofurans could be formed if the process conditions are not controlled satisfactorily. Although various chemical

methods of detoxification have been reported the unreactivity of PCBs generally necessitates the use of extreme conditions. However, a simple, efficient method for the oxidative destruction of PCBs has now been reported by investigators at the University of East Anglia and at Queen Mary College, London (2).

Their procedure makes use of ruthenium tetroxide as an oxidising agent, and complete destruction can be achieved. The rate of destruction of individual polychlorinated biphenyl isomers varies, resistance to degradation depending on the degree of chlorination of the biphenyl. The method is said to be suitable for the detoxification of laboratory equipment, and to have possible application for the large scale treatment of commercial waste fluids.

References I D. C. Ayres, Platinum Metals Rev. , 1981, 25, (4),

2 C. S. Creaser, A. R. Fernandes and D. C. Ayres, I 6 0

Chem. & Ind., 1988, ( I S ) , 499

Platinum Metals Rev . , 1988, 32, (4) 186

Chemical Conversion of Carbon Dioxide Catalytic Activation of Carbon Dioxide, ACS Symposium Series 363 EDITED BY WILLIAM M. AYERS, American Chemical Society, Washington, 1988,212 pages, ISBN 0-8412-1447-6, U.S.$49.95 (N. America), U.S.$59.95 (Export)

Carbon dioxide build-up in the atmosphere, the resulting warming of the world’s climate and the widespread disruption that could result, have all been very much in the news recently. This monograph is thus very timely in as much as it discusses some of the recent practical and theoretical work on the chemical conversion of carbon dioxide, which turns out to be quite chemically reactive despite being so thermodynamically stable. Regret- tably it has not been possible to review here all the work reported. Six of the fourteen chapters in the book

deal explicitly with electrocatalytic reduction. Depending upon the catalyst and the conditions, a wide range of products have been obtained.

M. H. Miles and A. N. Fletcher sum- marise their review of carbon dioxide reduction on metal electrodes which shows the formation of methane on ruthenium and copper, methyl alcohol on ruthenium and molybdenum, carbon monoxide on ruthenium, palladium, platinum, cobalt, iron, gold and silver, and formate on cadmium, indium, tin or lead electrodes.

A contribution by a large group of researchers at the University of North Carolina (B. P. Sullivan, M. R. M. Bruce, T. R. O’Toole, C. M. Bolinger, E. Megehee, H. Thorp and T. J. Meyer) reviews the overall problems of designing suitable electrocatalysts and the energetics of the carbon dioxide conversion reaction. More detailed information is given of their own work on polypyridine complexes of the second and third row transition metals.

K. W. Frese and D. P. Summers, SRI International workers interested in photoelectrochemical conversion, used semiconductor electrodes which gave a

methanol product; later they used plated ruthenium electrodes giving methane.

The natural reluctance of carbonate and bicarbonate anions to adsorb on a negatively charged cathode was overcome by W. M. Ayers and M. Farley of Electron Transfer Technologies Inc., who employed a two cell electrochemical reactor separated by a palladium membrane acting as a bipolar electrode. Methanol and formic acid with lesser amounts of formaldehyde were the result.

Attempts by S. D. Worley and C. H. Dai of Auburn University to make higher molecular weight oxygenates over supported rhodium catalysts resulted in methane formation, while further addition of potassium apparently poisoned the catalyst completely.

More information on gas phase reduction over heterogeneous catalysts would have been welcome, particularly the commercially very important methanol synthesis which is now generally believed to be a case of carbon dioxide, rather than carbon monoxide, hydrogenation.

One purpose of a symposium is to review the current state of the science in a particular area, and point out areas where more work is required. This symposium and t h i s publication certainly achieve these objectives. Clearly we are s t i l l a long way removed from the level of sophistication and expertise of the natural plant world which seemingly has no difficulty in using carbon dioxide as a basic carbon containing raw material. This book should prove to be particular-

ly useful to people who are interested in photoelectrochemical carbon dioxide fixa- tion and the reverse, that is organically powered fuel cells. J.W.J.

Platinum Metah Rev., 1988, 32, (4), 187 187

The Electrodeposition of Platinum and Platinum Alloys By M. E. Baumgartner and Ch. J. Raub Forschungsinstitut fur Edelmetalle und Metallchemie, Schwabisch Gmund, West Germany

Work on the electrolytic deposition of platinum and some platinum alloys is reviewed, and the results of our recent work OR the deposition and the properties of the layers produced from some promising electrolytes are briefly discussed. In general, studies of plating solutions are restricted by the economic availability of the relevant platinum salts. On the other hand the hydrolysis of the platinum salts in solution, and the incorporation of decomposition products are also critical factors, especially for their influence on internal stress. Recent work has shown that i t is possible to deposit platinum-cobalt alloys which have excellent magnetic and mechanical properties, and these alloy deposits look very promising for data storage applications and for small permanent magnet layers.

Research on the electrodeposition of platinum has been rather neglected recently, and as a result there has been little discussion of it in the literature. The last review paper on the subject, by F. H. Reid, appeared in I970 (I), while a more general review of the electrodeposition of the platinurn group metals, by one of the present authors, appeared in the Gmelin Handbook (2 ) .

In the main, the published literature contains only general statements about the bath composition; often information is lacking on the preparation of the bath, its operation, and the properties of the deposits obtained. However, a

survey of hardness, ductility and the internal stresses in platinum layers deposited from various electrolytes is given in (3).

No literature has appeared on the production of platinum alloy films, especially the electrodeposition of alloys of platinum with the iron- group metals. The present paper reviews previous work, tries to find guidelines for future research and in addition discusses recent results obtained at the authors’ Institute on the electrodeposition of platinum and platinum-cobalt alloys, and their properties.

Electrolytes for the Deposition of Platinum

The first experiments on the electrolytic deposition of the platinum group metals were made over 150 years ago by Elkington, who obtained a patent in 1837 (4), and later by Bijttger (5). The electrolytes contained simple metal salts and were rather unstable, while the deposits could not be used for any application. A review in 1910 stated simply that “electrolytic platinum is hard” despite the fact that it listed no fewer than nine different processes (6). In general, present day electrolytes contain the platinum as stable but quite different, complexes. An advantage of these complexes is that they show a smaller degree of hydrolysis in the bath, as compared to simple salts, and therefore the electrolytes are much more stable.

These electrolytes may be divided into two groups: [a1 baths containing platinum in the divalent state and [bl those with it in the tetravalent state.. Within both groups a further differentiation can be made based on the typical salts used, which may not always be identical with the metal supplying compounds. In Tables I and I1 a survey of electrolytes producing worthwhile deposits is given. Tests to


produce deposits from aqueous cyanide solutions proved to be unsuccessful (7). A Mond Nickel Company patent describes the deposition of platinum from a complex amine compound which should generate good layers (8). Apparently deposition is possible if the cyanoamine platinum complexes contain at least one, if possible co-ordinated, CN- group bound to the metal (8). The electrolyte, however, did not find wide use.

Electrolytes with Divalent Platinum Compounds Electrolytes Based on Chlorides

Today this type of bath has no great significance, however it was one of the first to achieve technical importance. The basic salts are PtCl,.5H20, H,PtC1,.6H20 and (NH,),PtCl,, and in general the bath operates in the acidic range. The fundamentals of these solutions were developed between 1840 and 1900. According to Biittger (9, 500 grams of citric acid should be dissolved in 2 litres of water and carefully neutralised with sodium hydroxide. During continuous stirring, 75 grams of dry ammonium hexachloroplatinate is then added to the boiling solution which is finally diluted with water to 5 litres. Current efficiency is nearly 70 per cent and the operating temperature is about w°C.

Deposits produced using this bath are fine grained but irregular. The addition of citric

acid increases the electrolyte stability by complexing the platinum ion. Electrolytes with citrates, phosphates and ammonium compounds react in a weakly acidic, or sometimes even alkaline state, but their make-up is not always as simple as it may at first seem to be. Interest in chloride-based electrolytes recurred in 1931 with investigations by Grube and Reinhardt (9). Later Atkinson further developed these baths by studying their deposition mechanism (10). He suggested as optimum operating parameters: platinum as H2(PtC1,) 10-50 gA, hydrochloric acid 180-300 gA, 45- p°C, current density 2.5-3.5 A/dm2, current efficiency 15-20 per cent, and a soluble platinum anode. Under carefully controlled conditions, this solution apparently produces crack-free, ductile crystalline layers of up to 2opm in thickness. As with most transition metals in aqueous solutions, the pH must be kept within a narrow range in order to avoid hydrolysis, which in this bath starts between pH 2.0 to 2.2 (10). It has to be stated that even today these baths generally tend to be fairly unstable. Deposition begins at a high polarisation, causing high hydrogen co- deposition and a current efficiency which is mostly below 50 per cent. The lifetime of the solutions is not very long and in addition, they are rather corrosive, which requires most base metals to be given a proper protective intermediate layer of, for example, gold, silver or

Table I

Types of Electrolyte for the Electrodeposition of Platinum

Based on Platinum ( 1 1 ) Based on Platinum (IV)

Chloride bath Alkali hexahydroxyplatinates

Dinitrodiammineplatinum (platinum-p-salt)

DNS-plating baths (Dinitrosulphatoplatinites)

Phosphate bath


Fig. 1 Using an acidic phosphoric-eulphuric acid bath, at 4OoC, pH 1.5 and a current density of 1 Aldm’ a bright surface, free from cracks, may be produced

palladium. During operation C1- ion concentration increases in most cases, generating dis- coloured deposits. At higher hydrochloric acid concentrations and operating temperatures, and at too low current densities, the platinum anodes dissolve, so no additions of platinum salts will be necessary. At lower hydrochloric acid concentrations an insoluble yellow deposit of (NH,),PtCl, may form at the anode, acting as an insulating layer. Finally it should be explained why chloride electrolytes may be considered as of a “divalent” type. If the electrolysis begins with a (PtCl,) j - solution the Pt‘+ ion is cathodically reduced to Pt’+ and we have to consider the equilibrium:

z(PtC1,)Z- f (PtCl,)2- + Pt + za- At the high concentrations of hydrochloric acid used, equilibrium is strongly shifted to the left side of the above equation.

Dinitrodiammine-Based Solutions In order to maintain the concentration of

divalent platinum in solution and to avoid oxidation of Pt(I1) to Pt(IV), it is necessary to stabilise the Pt(I1) ion by complexing it with suitable amino compounds. The basis of this kind of solution is cis-dinitrodiammineplatinum Pt(NH 3 ) , (NO,) , , which is frequent- ly called Pt-p-salt ( I I). Its use for electroplating applications was discovered by Keitel and Zschiegner in 1931 and resulted in a strong

resurgence in platinum electroplating (12, 13 The most simple type consists of Pt-p-sai 8-16.5 gA, ammonium nitrate 100 gA, sodiun nitrite 10 gA, ammonia (28 per cent) 50 gA: 90-95OC, current density 0.3-2.0 A/dm2 , current efficiency 10 per cent, and an insoluble pure platinum anode. However the electrolyte reacts irregularly, due to changes in the nitrite concentration, which with increasing concentration influences the dissociation of the platinum complex. The initial current efficiency can be regained by boiling the bath with added NH,NO,. On reacting with NaNO, it forms NH,NO, which, as a free compound, dissociates into nitrogen and water.

During deposition nearly all nonmetallic con- stituents of the Pt-p-salt are removed from the bath in gaseous form, so the electrolyte has a longer lifetime than halide systems. The bath can be replenished by frequent additions of Pt- p-salt. However its levelling power is fairly poor. Deposits are of a similar quality to those obtained from phosphate baths. The advantage of these electrolytes is that they are relatively easy to prepare. However, the quality of the electrodeposited layer depends largely on the concentration of the metal salt in solution and its purity; the higher the platinum concentration, the better the deposits.

A further improvement was reached by periodically reversing the 5-6 A/dm2 current, 5 seconds cathodic being followed by z seconds anodic current (14). In this way a platinum deposition rate of Sprn per hour was obtained. It is assumed that this depolarisation of the cathode also reduces the porosity of the platinum layer, producing such a low porosity that a 5cm plate (Pt) over nickel withstood boiling hydrochloric acid (20 per cent) for five hours with no weight loss (IS). A different electrolyte of the Pt-p-salt type contains fluoroboric acid (16); its composition being: Pt-p-salt 20 gA, fluoroboric acid 50-100 gA, sodium fluoroborate 80-120 gA, 70-w°C, current density 2-5 A/dmz , current efficiency 14-18 per cent, insoluble platinum anode. Layers up to 7.5pm in thickness can be deposited. According to Hiinsel defect free


copper overplate

\ayer -D

copper substrate

Fig. 2 Replacing ammonium salts with sodium acetate and sodium carbonate results in improved current efficiency, and enables smooth, bright layers free from cracks and pores to be deposited; left 2.5pm platinum layer, right lOpm platinum

layers can be achieved only if the platinum is present in the solution in the divalent state (12). A different Pt-p-salt solution contains 20-100

gA sulphamic acid (17) or phosphoric acid, or a mixture of phosphoric and sulphuric acids (18, 19). For all these electrolytes insoluble platinum anodes are used; good electrolyte stirring and movement of the cathode are important. The layers produced from this electrolyte are crack free, shiny, bright and up to 2pm in thickness. Figure I shows the surface of a Ipm thick layer deposited from a phosphoric and sulphuric acid bath. The highest current efficiency is obtainable from an electrolyte in

52

f 48

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i? 28 Cathodic agitation lmlrnin Bath agitation :I 0 01 llrnin

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Fig. 3 Agitation of the electrolyte and the cathode results in an improvement in current efficiency at 7OoC, pH 10 and a current density of l Aldm’

which ammonium salts are replaced by sodium acetate and sodium carbonate, which also improves stability (I). Deposits from this bath are smooth, bright and free of pores and cracks at thicknesses up to Iopm, as shown in Figure 2.

The use of the sodium instead of the ammonium salts improves current efficiency and avoids the formation of a salt layer on the anode. The cathodic current efficiency of 35 to 40 per cent may be further improved by movement of the cathode or the electrolyte, as is shown in Figure 3.

Since the metal concentration in the electrolyte is fairly low, the diffusion controlled transport of the dischargeable ionic species through the Nernst diffusion layer soon becomes the dominating step in the discharge. Furthermore, this increases both the diffusion overvoltage and the hydrogen deposition, which gets even stronger at higher current densities. This mechanism explains the increase in current efficiency with higher relative movements of cathode and electrolyte. Addi- tional agitation, and a reduction of the thickness of the Nernst diffusion layer, is also provided by hydrogen evolution at the cathode.

Another method of improving the current efficiency of this bath is to increase the operating temperature. The influence of electrolyte temperature on the cathodic current efficiency is shown in Figure 4, a sudden increase in current efficiency near 6o°C reaches almost 60 per cent close to w0C. Below 5o°C


: 60, 1

./ I

u TEMPERATURE, *C

Vig. 4 Current efficiency can also be influenced by the temperature of the electrolyte. At pH 10, 1 A/dm’ and agitation of both the electrolyte and the cathode, a marked increase in current efficiency occurs at about 6OoC

the value is only about 10 per cent. If this electrolyte is newly made up, the pH adjusts itself to about 10. The dependence of cathodic current efficiency on pH is approximately linear, see Figure 5. This is further proof that the importance of hydrogen co-deposition increases with pH value. At the same time less metal is deposited-the current efficiency for metal deposition decreases with pH. A pro- nounced influence of metal deposition on current efficiency is shown by the platinum metal concentration, Figure 6. A decrease of metal concentration causes a reduction in current efficiency. On replenishing the electrolyte with new Pt-p-salt, intermediate products may be

60 u 1

V -

4 5 6 7 8 9 1 0 1 1

PH

Fig. 5 At 7OoC, 1 A/dmz and with electrolyte and cathode agitation, the reletion- ship between current efficiency and pH value is almost linear

formed and the nitrite concentration increases, reducing the concentration of the dischargeable platinum ionic complex.

The current density-potential curves of these electrolytes show very characteristic behaviour in the alkaline pH range, insofar as the current density increases up to a maximum limiting value of I . 5 A/dm2 at about 500 mV, and then within a further 50 mV it drops to a low value of 0.2 Aldrn’ before increasing again with potential due to hydrogen production. How far this kind of “cathodic passivation” is con- nected with the hydrogen co-discharge, and the adsorption of hydrogen, is not as yet clear. Another explanation might be a sudden change in pH value in the cathodic layer caused by hydrogen evolution. The critical current density can be increased by an increase in the concentration of the F’t-p-salt, as well as by the sodium acetate addition but not by changes in the sodium carbonate concentration. Tem- perature has a very decisive influence on the critical current density, while potentials remain nearly constant. “Passivation” is no longer observed at pH values below 7, since hydrogen evolution starts before platinum discharge begins. Figure 7 shows typical current density- potential curves for the electrolyte and for various pH values, at a temperature of 7oOC.

Electrolytes Based on Dinitrosulphatoplatinonoue Acid

These electrolytes are free of ammonia or amines, and are based on the complex H, Pt(N0,) , SO., . With them it is possible to coat directly with platinum a wide range of materials including copper, brass, silver, nickel, lead and titanium. However, metals such as iron, zinc or cadmium have to be pre- plated with a dense layer of nickel or silver (20).

The salts for making up the solutions are potassium salts of nitro-, chloro- and sulphatoplatinous acid, such as: K,Pt(NO,),Cl, K, Pt(N0,) ?Cl , and K, Pt(N0,) , SO, , respectively. If bright deposits are required the work has to be carried out at low current densities and the pH of the electrolyte must be kept below z by the addition of sulphuric acid.


Typical baths have the composition: dinitro- sulphatoplatinous acid (DNS) 10 gA, sulphuric acid up to pH 2, temperature 30 to 7ooC, current density 2.5 Aldm’, current efficiency 10-15 per cent, insoluble pure platinum anode. The advantages of the DNS electrolyte are claimed to be as follows: the deposits produced are smooth and bright, and do not have to be polished; layers up to 25pm thickness can be produced, however cracks form at greater thicknesses; electrolytes are stable, producing constant results and do not degrade on standing; it is possible to coat a wide range of base metals without using an intermediate layer.

Electrolytes with Tetravalent Platinum Complexes Alkaline Solutions

In general alkaline electrolytes contain the sodium or potassium salts of hexahydroxyplatinic acid Na,Pt(OH), or K,Pt(OH),, respectively (21). A typical bath is: sodium hex- ahydroxyplatinate 20 gA , sodium hydroxide 10

gA, 75OC, pH 13, current density 0.8 A/dm’, current efficiency 100 per cent, insoluble nickel or stainless steel anode. Deposits are dense and bright, if the electrolyte is freshly made up. In older solutions they become matte and spongy. An advantage of these kinds of electrolytes is their easy regeneration. If the pH of the electrolyte is decreased by the addition of acetic acid, hexahydroxyplatinic acid salts are

Fig. 6 Current efficiency is also influenced by the platinum concentration in the electrolyte, as demonstrated by a bath at 7OoC, pH 10 and 1 A/&’

~ ~ ~~ ~~ ~

Platinum Metals Rev., 1988, 32, (4)

CURRENT DENSITY, Aldm2 2 1.5 1 0.5

I

- 200

-400

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W

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precipitated and can then be filtered off and used for the preparation of a new bath. How- ever, a disadvantage is low stability, since during operation, or on standing, a yellow deposit forms by decomposition of the hydroxy salt according to the equation:

3 Na,Pt(OH), - Na,0.3Pt02.6H,0

The reaction is catalysed by impurities in the make-up salts. Another problem is the take up of carbon dioxide from the air, so the carbonate concentration increases and has to be reduced regularly by precipitation with Ba(0H) 2 . In this connection potassium salts show a better performance than sodium salts. It is claimed that an improvement in stability is obtained by adding sodium oxalate, sodium sulphate or sodium acetate (22, 23). Other researchers state, however, that these additions are detri-

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mental to the stability of the electrolyte since they were inclined to increase the tendency for precipitation of insoluble platinum compounds (12).

According to Davies and Powell, a typical bath composition is: sodium hexahydroxy- platinate 18.5 gA, sodium hydroxide 5.1 gA, sodium oxalate 5.1 gA, sodium sulphate 30.8 gA, 65-8ooC, current density 0.8 A/dm2 , current efficiency 80 per cent, insoluble pure platinum anodes (24). With this electrolyte dense, sparkling platinum deposits can be produced which are comparable to rhodium elec- trodeposits (25). However if the platinum concentration drops below 3 gA the current efficiency drops to only a few per cent. At higher platinum concentrations (12 gA) current densities of up to 2.5 A/dm2 may be achieved. Cur- rent efficiency versus temperature data display a maximum of about 80 per cent at 65 to 7ooC, which is not further improved, even at higher temperatures. Large temperature variations of the bath during deposition may generate scaling of the layers (25). Gold, silver, copper and their alloys may be used as base materials. However the electrolyte seems to be tolerant of impurities, especially against cyanides, which mask the platinum ions, so reducing current efficiency. Platinum must always be present in the tetravalent state of the hydroxy complex. The bath tolerates up to 300 gA potassium carbonate but only 60 to 80 gA sodium carbonate, before cathodic current efficiency drops (26). For deposition onto metals which react in strong alkaline solutions potassium hydroxide may be replaced by 40 gA of potassium sulphate (26).

Phosphate Based Electrolytes As early as 1855 Roseleur and Lanaux sug-

gested the use of phosphate based electrolytes for the deposition of platinum (27). The baths contain platinum as a chloro compound, such as Pt(1V) chloride, hexachloroplatinic acid or its alkali salts. To improve conductivity alkali phosphates and ammonium phosphates are used; the presence of the latter is supposed to enhance deposition. Pfanhauser suggests as the electrolyte: platinum(1V) chloride 7.5 gA,

diammonium hydrogen phosphate (NH,),HPO, 20 gA, disodium hydrogen phosphate Na,HPO, 100 gA, ammonium chloride 20-25 gA, 7o-9o0C, current density 0.3-1.0 A/dm2 , current efficiency 10 to 50 per cent, insoluble platinum anode (4). Layers up to a thickness of 0.5pm can be deposited. By increasing the platinum concentration up to 5-10

gA it is, however, possible to obtain deposits which, after dissolution of the substrate metal, remain as solid foils, tubes or other hollow structures. Using a similar electrolyte comparable results were reported by Grube and Beischer (7). A great disadvantage of this electrolyte is that it is difficult to prepare. Before a freshly prepared solution can be used, it has to be left until a deposit which forms is completely dissolved. If the solution is made up without ammonium phosphate, the deposits are rather porous and sometimes spongy. Apparently the ammonium phosphate improves the dissolution of an (NH,)+-containing platinum complex in the solution. Under certain conditions, this electrolyte also forms a layer of insoluble yellow salt which serves as an insulating “barrier” on the anode surface; this is most likely am- moniumhexachloroplatinate.

Platinum Alloy Deposits A general review of work on the electro-

deposition of platinum alloys up to 1963 has been given by Brenner (28). The earliest alloy deposition seems to have taken place in 1894 from alkaline cyanide solutions. A patent describes the deposition of platinum with cobalt, nickel, copper, zinc, cadmium and tin (29). A later literature survey of the subject covering the period from 1965 to I970 was given by Krohn and Bohn (30). However their remarks are very general and no information on electrolyte compositions is given. Bogenschiitz and George mention the compositions of certain electrolytes for the deposition of platinum with ruthenium, palladium, iridium and rhenium, as well as a solution for producing platinum-cobalt alloys. Regrettably information on deposition conditions and properties is not given (31).

Angus studied platinum-palladium and


a 1 0 0 7 cmulg

Fig. 8 The hysteresis loops of platinum-70 atomic per cent cobalt demonstrate the attractive magnetic properties of this material

I 0 10 20 30 4 0 50 6

COBALT CONTENT, atomic pcr Cent

Fig. 9 The hardness of electrodeposited platinum-cobalt depends largely upon the cobalt content. Here the base metal concentration in the electrolyte was 10 g/l, pH 5, and current density 2 Aldm’

platinum-ruthenium alloys, for depositing layers containing 20 to 80 per cent platinum (32). In these baths, current density is the dominant influence on alloy composition. Electrolytes for both alloys are quite different. In the platinum-palladium solution, with increasing current density, less palladium is co- deposited, while in the platinum-ruthenium alloy solution the ruthenium content of the layers increases from 10 to 50 per cent as the current density is raised from 0.5 to 2.0 Ndm’ .

Studies by HHnsel showed that electrodeposited alloys of platinum-7 per cent iridium and platinum-5 per cent rhenium have a much higher hardness than pure platinum layers, the increase being more than 200 per cent (33). He

used a chloride electrolyte with ammonium hexachloroplatinate and the respective iridate, and disodium hydrogen phosphates as a buffer (pH 8 .5 ) for the platinum-iridium alloy deposition. The best platinum-rhenium alloys were produced from a fluoroboric acid solution; however sulphamic acid caused high internal stresses in the layers.

An acidic platinum-iridium alloy bath (pH 1-2) is described by Tyrell (34). The bath is based on hexabromoplatinic acid and hexabromoiridic acid with I. 5 gfl iridium and 3.5 gA platinum. The iridium concentration in the solution and the temperature strongly influence the iridium content of the deposit. At 4 and 30 per cent iridium the layers tend to crack. However, layers with 10 per cent iridium can be produced up to a thickness of Iopm.

The deposition of platinum-cobalt alloys and the properties of the deposits have been studied recently in the authors’ Institute (35). The basic electrolyte composition was sodium acetate, sodium carbonate, platinum-p-salt, cobalt sulphate and triethanolamine. It was shown that it is possible to deposit platinum- cobalt alloys containing low to high cobalt concentrations (more than 50 atomic per cent), which combine high hardness and wear resistance with excellent magnetic properties. For example, the deposits show high coercive forces of up to 400 kA/m at a relatively small

Fig. 10 Platinum-cobalt alloys, containing 10-12 weight per cent cobalt, can be deposited as bright shiny layers which are crackfree at thicknesses up to about 6pm, and which show excellent adhesion to the substrate

Platinum Metals Rw., 1988, 32, (4) 196

anisotropy, making them very interesting materials for applications such as data storage devices or permanent magnets, see Figure 8.

The hardness of the layers depends strongly on their cobalt concentration, increasing cobalt resulting in an increase in hardness. In particular, an alloy with about so atomic per cent cobalt shows a major increase in hardness, as illustrated in Figure 9. As yet it is not clear how much the effect is

due to the deposition of platinum-cobalt in the ordered state. For comparison, metallurgically produced platinum-so atomic per cent cobalt alloys exhibited hardness values around 200 HV, while electroplated deposits of this composition have a hardness of 700 HV.

The composition of layers electrodeposited

from these electrolytes is strongly influenced by electrolyte temperature and pH value. If the electrolyte is operated in the neutral or alkaline range, no more than 10 to 12 weight per cent cobalt can be co-deposited with platinum. Depending on the pH value, the current efficiencies are between 15 and 30 per cent. All deposits are shiny bright, show excellent adhesion and are crack-free up to thicknesses of 6pm (Figure 10).

Acknowledgements We wish to thank Impala Platinum Limited for

supporting our work on the electrodepsition of platinum and platinum alloys. Part of the work is based on a Diplom-Arbeit by M. Wiesner, made at Forschungsinstitut fiir Edelmetalle und Metallchemie in collaboration with Professor Dr. H. Ropwag of the Fachhochschule, Aalen, West Germany.

References

I F. H. Reid, Trans. Inst. Met. Finish, 1970, 48, 115; Metall. Rev., 1963, 8, 190

2 Ch. J. Raub, Electrodeposition of Platinum- Group Metals, Platinum Supplement A 1, “Gmelin Handbuch der Anorganischen Chemie”, Springer-Verlag, Berlin, Heidelberg, New York, 1987, p. I37

3 W. H. Safranek, “The Properties of Electro- deposited Metals and Alloys”, Elsevier, New

4 W. Pfanhauser, “Galvanotechnik”, Akademische

5 R. BSttger, 3. Franklin Inst., 1878, 348 6 W. G. McMillan and W. R. Cooper, “A Treatise

on Electro Metallurgy”, Charles Griffm and Co., London, 1910, p. 239

7 G. Grube and D. Beischer, Z. Elektmhem., 1933,

8 Mond Nickel Company Ltd., Gennan Patent

9 G. Grube and H. Reiiardt, Z. Elekmchem.,

10 R. H. Atkinson, Trans. Inst. Metal. Finish.,

I I “Gmelins Handbuch der Anorganischen Chemie”, Verlag Chemie, Weinheim, KAuflage, System Nr. 68, 1957, p. 229

York, 1974, P. 352

Verlagsgesellschaft, Leipzig, 1949, p. 870

39, 38

614,801; 1933

1931, 37, 307

19581591 37, 7/16

12 G. Hhsel, Metalloberjlache, 1967, 21, 238 13 W. Keitel and H. E. Zschiegner, Trans. Electro-

chem. Soc., 1931, 59, 273 14 A. B. Tripler, J. G. Beach and C. L. Faust, U.S.

Atomic Energy Commission Publ., (Bw-I097), I956

1,356,333; 1967

15 E. A. Parker, Plating, 1959, 46, 621 16 R. Lacroix and Ch. Beclier, French Patent

17 French Patent 1,231,410; 1960, U.S. Patent 2,984,603; 1961, U.S. Patent 2,984,604; 1961

18 W. Keitel and J. B. Kushner, Met. Ind. (N. Y.),

19 French Patent 1,299,226; 1960 20 N. Hopkin and L. F. Wilson, Platinum Metals

Rev., 1960, 4, (2j, 56 21 A. R. Powell and A. W. Scott, British Patent

363,569; 1931 22 S. Wernick, “Electrolytic Polishing and Bright

Plating of Metals”, A. Redman Ltd., 1951, P. 115

19393 37, 182

23 E. H. Leister, Met. Ind., 1954, 85, 469 24 E. C. Davies and A. R. Powell, J. Electro-

25 J. Fischer, “Galvanische Edelmetalliibeniige”,

26 French Patent 1,273,663; 1960 27 A. Roseleur and M. Lanaux, Dingler’s Polytech.

28 A. Brenner, “Electrodeposition of Alloys”, Vol. 11, Academic Press, New York, 1963, p. 542

29 W. A. Thomas and W. H. Burgum, British Patent

30 A. Krohn and C. W. Bohn, Plating, 1971,58,237 31 A. F. Bogenschiitz and U. George, “Galvanische

Legierungsabscheidung und Analytik”, G. Leuze Verlag, SaulgauIWttbg., 1982, p. 66

32 H. C. Angus, Tijdschr. Oppewlaktech. Metalen,

33 G. Hhsel, Metalloberfiche, 1967, 21, 238 34 C. J. Tyrell, Trans. Inst. Metal. Finish., 1967,45,

35 M. E. Bauqgirtner, Ch. J. Raub, P. Cavallotti

depositors Tech. SOC., 1937, 13, 7

G. Leuze Verlag, Saulgaumttbg., 1960

3., 1855, 13% 318

7853; 1894

1970, 14% 74

53

and G. Tumlli, Metalloberjlache, 1987, 41, 559


Ruthenium in Cancer Chemotherapy A SELECTIVE REVIEW OF THE TRIESTE SYMPOSIUM

By M. J. Clarke Department of Chemistry, Boston College, Chestnut Hill, Massachusetts

Since many “soft” metal ions bind to the same DNA co-ordination sites as the widely used anti-cancer drug, cisplatin, it seems likely that some of these should also yield effective chemotherapeutic agents. New results in this area were presented at a symposium held in Trieste, Italy, on 30th June-1st July 1988 which focused on the design and modes of action of non-platinum metal ions in cancer chemotherapy.

Ruthenium appears to be a likely candidate, even though its chemistry differs substantially from that of platinum. The most significant differences are its octahedral geometry and greater propensity to undergo redox reactions. The hypoxic environments of many tumours may favour the reduction of Ru(II1) compounds (which are relatively slow to bind to most biological substrates) to Ru(I1) species, which bind rapidly. Once co-ordinated to a DNA target, the metal may interfere with DNA metabolism by a variety of mechanisms. Migra- tion between sites can also occur in a manner which is controlled by redox potential and pH.

According to Dr. Jacqueline K. Barton of Columbia University, advantage can be taken of the two additional binding sites provided by octahedral geometries to design chiral compounds that are selective for the particular shapes of the various DNA conformers. Outer- sphere binding may occur electrostatically, hydrophobically or intercalatively. If open co- ordination sites are available on the metal ion, subsequent bond formation may ensue. Scis- sion of the DNA induced by the metal ion may occur by photochemical or redox routes and can be highly selective.

An interdisciplinary group in northern Italy headed by Professors G. Mestroni in Trieste and F. Quadrifoglio in Udine has been in-

vestigating the solution chemistry and DNA interactions of a family of compounds involving cis and trans isomers of X,(DMSO), Ru, where X=CI or Br, and DMSO is dimethyl sulphox- ide. While only mildly active, these compounds are fairly non-toxic and the trans isomer strongly inhibits metastases of Lewis lung carcinoma. In aqueous solution, the cis complex rapidly loses the 0-bound DMSO ligand, while the trans isomer quickly aquates on losing two cis- DMSO ligands. The trans isomer binds to DNA much more rapidly and to a higher degree than the cis isomer. DNA co-ordination by the cis species almost ceases in chloride concentrations approximating that of plasma, and the site of binding of both is suggested to be on the N7 of guanine with a possible involvement by the phosphate.

Dr. Bernard K. Keppler from the University of Heidelberg, Germany, reported very promising results on a number of compounds with the general formulae: trans-HB[RuB,CI,] and (HB) [ RuBCl 1, where B =nitrogen heterocy- cle. These compounds are effective against col- orectal tumours, which commonly occur and, once metastasised, are presently incurable. Keppler, in collaboration with M. E. Heim, also reported on the first stage of clinical trials of Budotitane, the titanium compound diethox- ybis( I-phenylbutane-I ,3-dionato)titanium(IV), which is also active against autochthonous col- orectal carcinomas. This compound is well tolerated at a level of 150 mglm’ , it exhibits liver toxicity but no myelosuppression or nephrotoxicity .

Dr. Petra Kopf-Maier of the Free University of Berlin presented results on three different types of metallocene complexes: a) neutral cis- diacido complexes, Cp, MX, , M = Ti(1V) or V(1V); b) cationic metallocenes, such as


ferrocinium, and c) decasubstituted neutral metallocenes, (C, R,),M, where R=phenyl or benzyl and M=Sn(II) or Ge(I1). Examples of each type were active in markedly inhibiting tumour growth and induced severe cytological and histological changes in the tumours treated, which suggested that the complexes interfere with nucleic acid metabolism. Reaction of the titanium complex resulted in [Cp,Ti]+ co- ordinated to purine nucleosides through both monodentate N7 and N7-06 chelation. The vanadocene moiety appears to bind in a labile outer-sphere fashion to phosphate groups. Doses of Cp, Tic1 are limited by liver toxicity.

Ruthenium and platinum compounds may be used to direct radiosensitising molecules to DNA, according to Professor Nicholas Farrell of the University of Vermont. This approach is particularly useful in radiotherapy applied to hypoxic or anoxic areas of tumours, where radiation is less effective. Studies on the radiation killing of cells indicate that metal complexes ligated with nitroimidazoles are more active than either the metal or ligand precursor molecules alone and so point a way to the design of new agents.

The ruthenium isotope, 97Ru, has excellent radiophysical properties for use in diagnostic

imaging agents. Its y-ray is easily collimated by existing radioscintigraphic cameras and its 3-day half-life provides adequate time for synthesis and quality control. Dr. Suresh Srivastava of Brookhaven National Laboratory presented the first clinical studies of a liver- imaging agent using a complex with diisopropyl carbamoylmethyl iminodiacetate, which proved very effective in imaging the livers of neonates suspected of liver dysfunction. Radiolabelling studies also showed that some Ru(II1) complexes can be bound to transfemn and carried to receptor sites on tumours. The metal ion is fixed inside the cell, possibly by a redox mechanism, while the transferrin is released.

The symposium discussions concerning the various approaches to ruthenium-containing anti-cancer drugs reflected the versatility of this element in synthesis, electron transfer, and even photochemistry. These properties, coupled with the affinity of ruthenium’s intermediate oxidation states for imine nitrogens, facilitate DNA targeting for both chemotherapeutic and radiosensitising agents. Finally, the existence of isotopes with desirable properties for diagnostic imaging indicates that exploration of the medical applications of ruthenium is likely to produce useful pharmaceuticals.

Lean-Burn Oxygen Sensor Material PLATINUM CATALYST IMPROVES RESPONSE TIME

Oxygen sensors are widely used as automobile engine control devices in order to obtain an optimised balance of exhaust emissions, fuel economy and vehicle drivability, and generally this is achieved by controlling the air to fuel ratio at the stoichiometric mix of 14.7:1. Now there is increasing interest in controlling the air to fuel ratio away from the stoichiometric point, in the lean-burn region, with the aim of increasing engine efficiency and decreasing nitrogen oxides emissions.

Lean-burn oxygen sensors are generally classified as either semiconducting or electrochemical pumping. The former are small, simple, low cost devices which are based upon the resistivity changes that take place in oxide semiconductors as the partial pressure of oxygen in the surrounding atmosphere varies.

A recent paper by C. Yu, Y. Shimizu and H.

Arai of Kyushu University, Fukuoka, Japan, reports on their investigation of several species of magnesium-doped SrTi03 in the exhaust gas resulting from air-propane combustion containing water vapour (“Mg-Doped SrTi03 as a Lean-Burn Oxygen Sensor”, Sens. Actuators, 1988, 14, (4), 309-318). At temperatures between 600 and 80o0C, the highest sensitivity to oxygen in the lean-burn region and the lowest sensitivity in the rich-burn region was shown by SrTi,,6Mg0.403-6, and therefore it was considered to be a suitable material for a lean-burn oxygen sensor. However the response time was about 1.5 seconds, which is too long for use in an automobile engine system. When I weight per cent platinum was added as a catalyst the response time was reduced significantly and in addition the sensitivity was increased in the lean-burn region.


Control of Corrosion in Molten Carbonate Fuel Cells THE APPLICATION OF PLATINUM GROUP METALS IN ANODE COMPONENTS

By M. Wyatt and J. M. Fisher Johnson Matthey Technology Centre

Molten carbonate fuel cells have the potential to succeed phosphoric acid fie1 cells as systems for large scale electrical power generation. Their introduction, h e v e r , will depend on the wide acceptance of first generation phosphoric acid technology and on solutions being found to a number of significant technical problems, including corrosion of fuel cell components by the molten carbonate electrolyte. Ruthenium, rhodium, palladium, platinum, silver and gold have all been shown to exhibit resistance to corrosion by molten carbonates under the conditions experienced at the anode of a molten carbonate fie1 cell. In addition, rhodium and ruthenium are not wetted significantly by the molten carbonate electrolyte.

Fuel cells offer a very attractive means of con- verting the chemical energy of a fuel and an oxidant to electrical energy, since the conversion efficiency is not subject to the limitation of the Carnot cycle. Phosphoric acid fuel cell technology is accepted as being nearest to commer- cialisation for large scale electric power generation. Dozens of prototype stationary phosphoric acid fuel cell units have been demonstrated at electric utilities and by users of co-generated heat and power in the United States of America and Japan. While these were generally successful they were considered to be too costly for commercial use. A large, 60 to 80,000 MW fuel cell market can be envisaged for the period 1996 to 2010, based on mature market prices (I). However, near term prices of L145o to L175okW for fuel cell power plants are well above the mature market price of f350 to &oc~ikW. A significant volume of production, say 2,000 to 3,000 MW, at lower prices will be required to support the introduction of phosphoric acid fuel cell units over the next 10

to 15 years (2).

For the future, molten carbonate fuel cells

are particularly attractive since the operating temperature is generally about 65oOC and the reaction kinetics are significantly faster than in lower temperature cells. In addition, the ohmic resistance of the usual 62 : 38 mol per cent lithium carbonate : potassium carbonate electrolyte is relatively low, while efficiencies of the order of 50 to 55 per cent have been reported (3).

A schematic diagram of a molten carbonate fuel cell is shown in Figure I. The electrolyte is supported in a matrix of lithium aluminate which is termed a “tile”. The separator plate and current collector are generally made from stainless steel. A practical fuel cell consists of repeated layers of electrolyte “tile”, cathode, bipolar plate and anode, see Figure 2.

The carbonate ion takes part in the electrode reactions, and the composition of the melt re- mains constant due to a continuous transfer of carbonate ions from the cathode to anode. Anode: H, + CO,-- - H,O + CO, + 2e-

Cathode: CO, + 1/2 0, + 2e- - C 0 , - - Overall cell reaction: H, + 1/2 0, - H,O

CO + CO,-- - 2C0, + 2e-


Hydrogen Air' carbon dioxide

Fig. 2 Depending upon the electrical output required, a practical molten carbonate E fuel cell would have to consist of a repeated series of the t six basic components shown 01

E

n

6

d - w

water * carbcn dioxide Air depleted ot oxygen and carbon dioxnde

Fig. 1 In a molten carbonate fuel cell the electrolyte is supported between the anode and cathode in a lithium aluminate matrix. The disposition of the reactant fluids and reaction products is shown

stainless steel

Cathode

Electrolyte trre, carbonates in ceramic matr ix

Anode

Current collector, stainless steel Separator plate,

7 stainless Steel

During early work on molten carbonate fuel cells platinum, palladium and palladium-silver alloys were used as anode materials (4) but they were rejected on the grounds of cost. At present, nickel or nickel-chromium is used for the anode in state-of-the-art cells, while the cathode is generally made of nickel oxide. How- ever, the cathodes in particular are subject to corrosion problems.

Corrosion Molten carbonate is a very aggressive

medium and the corrosion of fuel cell components poses significant problems. The resistance of any material to corrosion by

molten carbonate is dependent on a large number of factors (5), including moisture and impurities content, temperature, and the gas atmosphere above the melt. Another important factor affecting corrosion is the wettability of the materials by molten carbonate, and many materials are completely smothered by molten alkali carbonate. Since there are so many factors governing corrosion and wetting resistance it is not surprising that the literature in this field appears confusing. Differences in test procedures, purity of melts, gas atmospheres and temperatures, for example, can all give widely differing results.

The present work has shown that ruthenium, rhodium, palladium, platinum, silver and gold show promise as corrosion resistant materials for use at the anode in molten carbonate fuel cells. A series of static corrosion tests has been carried out on these metals using a specially designed rig which allowed the simultaneous testing of 6 samples. A schematic diagram of a single test chamber is shown in Figure 3, on the following page.

Preliminary tests demonstrated that gold did not dissolve in molten carbonate, so all subsequent corrosion tests were carried out in gold crucibles. A typical test involved placing a metal foil sample (z x I cm) and the carbonates (0.5 g) inside a small gold crucible which was then maintained inside the test chamber at a temperature of 65ooC, under a specified gas atmosphere.

A typical mixed carbonate electrolyte was prepared from lithium and potassium carbonates which were purified prior to use by

Platinum Metals Rev., 1988, 32, (4) 20 1

u 3

- n

Stainless steel

Metal sample Gold crucible and carbonate

Test duration, Initial weight, Weight change, Material hours grams per cent

Rhodium 93.6 0.604 0.33

Ruthenium 93.6 0.940 0.21

Fig. 3 Molten carbonates are extremely corrosive, with several factors governing the extent of the corrosion suffered by a particular material. For this reason a special rig has been constructed for .+ample testing

Weight change, grams

- 0.002

+ 0.002

passing carbon dioxide through the molten salt for 24 hours, to remove traces of oxide and hydroxide.

Ruthenium, rhodium, palladium, platinum, gold and silver were corrosion tested for 100

Platinum

Palladium

hours at 65oOC with purified carbonate (62 : 38 mol per cent lithium carbonate : potassium carbonate) under a 68 hydrogen, 17 carbon dioxide and 15 per cent water vapour atmosphere. These conditions simulated those at the anode side of a molten carbonate fuel cell. The samples appeared unmarked at the end of the test period and had suffered no significant weight change. Such changes are recorded in Table I, together with those for 321- and 304-type stainless steels which were tested under identical conditions.

The results for platinum and silver appeared surprising in view of the fact that corrosion under carbon dioxide has been reported previously (6). In the current work, however, hydrogen was also included in the gas atmosphere; and no trace of the previously reported lithium platinate was found by X-ray photo- electron spectroscopy (XPS).

The roo hour corrosion test was repeated for platinum and silver in an oxidising atmosphere of 50 per cent carbon dioxide, 50 per cent air. Under these conditions silver had visibly dissolved in the carbonate and some had plated out onto the bottom of the crucible. The corrosion of silver under oxidising conditions is consistent with data in the literature (7). The

+ 0.002 93.1 0.369 0.54

93.1 0.81 6 0.49 + 0.004

Gold 90.2 2.060 0.00 0.000

Silver

321 -type Stainless steel

304-type Stainless steel

93.6 1.760 0.08 +0.001

90.1 0.41 9 2.10 + 0.009 90.1 0.921 1.80 + 0.01 7

Platinum Merals Rev., 1988, 32, (4) 202

Table I

Corrosion Test Results (Li,CO, : K,CO, 62 : 38 mol%: under 68% H,, 17% CO,, 15% H,O at 65OOC)

Table II

Contact Angle Measurements (Li,CO, : K,CO, 62 : 38 mol%; under H,

at 65OOC and CO, at 6OOOC)

Silver

Gold

Material Gas atmosphere

Platinum

46 42

66 Wets

Ruthenium

321-type Stainless steel I 20 I Wets

304-type Stainless steel I Wets I Wets

platinum sample had changed colour, and when studied by X P S the surface layer was found to be Li,PtO, . These two metals are therefore considered to be unsuitable for use at the cathode side of the fuel cell.

Contact Angles The contact angles of the platinum group

metals with molten carbonate were measured using a hot stage microscope in order to assess their wettability, wetting being defined as a contact angle of 20° or less. The unit was mounted in a .wall of a glove box and this enabl- ed the test samples and the carbonate to be handled under carbon dioxide throughout the test procedure. Contact angles were measured on I x I cm foil squares, which were placed on the workstage together with a purified crystal of carbonate. The work chamber was evacuated to 10- mbar and then either hydrogen or carbon dioxide gas was admitted to a pressure of 300 mbar. The sample was heated and the contact angle was measured. The results are given in Table 11.

Rhodium, ruthenium and gold exhibited a high resistance to wetting under hydrogen and

all of the samples showed improved wetting resistance when compared to 321- and 304-type standard austenitic stainless steels.

Conclusions In current molten carbonate fuel cells nickel-

chromium is generally used for the anodes. However, the platinum group metals do offer good corrosion resistance and non-wetting properties under reducing conditions, and may therefore find application. In addition, noble metals alloyed with standard materials may enhance the properties of anode components.

Acknowledgement

of the European Communities. This work was funded in part by the Commission

References I J. M. Scigliano, “The Role of Fuel Cells in

Future Energy Scenarios”, Energy Production Processes, Symp. Institute Chemical Engineers, London, 12-14 April 1988

2 P. Hite, “The Effect of Improved Cathode Catalyst Technology in PAFC Cost”, Fuel Cell Technology and Applications International Seminar, The Netherlands, 1987

3 L. Paetsch, P. S. Patel, H. C. Maru and B. S. Baker, “Direct Fuel Cell Development”, Fuel Cell Seminar, Tucson, Arizona, 1986

4 G. H. J. Broers and J. A. A. Ketelaar, Ind. Eng. Chem., 1960, 52 , 303; L. G. Marianowski, J. Meek, E. B. Schultz and B. S. Baker, in Proc. 17th Ann. Power Sources Conf., PSC Publi- cations Committee, Red Bank, New Jersey, 1963, p. 72; J. T. Cobb and L. F. Albright, 3. Electro- chem. Soc., 1968, 1x5, 2

5 J. R. +lman and L. G. Marianowski, “Fuel cells” m “Molten Salt Technology”, Plenum Press, New York, 1982

6 G. J. Jam, A. Conte and E. Neuenschwander, Corrosion, 1963, 19, 292

7 I. Trachtenberg and D. F. Cole, “Fuel Cell Systems z”, ed. B. S. Baker, Av. Chem Series 90, Am. Chem. Soc., 1969

Flammable Gas Detection In the above named paper, which appeared in

Platinum Metals Rev., 1988, 32, (2), 50-60, a correction should be made on page 58, right hand column, line 3. Here the word “increase” should be “decrease”; the corrected sentence then being: “The adsorbed atoms form dipoles at the metal-insulator interface resulting in a decrease in the work function of the metal at the interface.”


Table II

Contact Angle Measurements (Li,CO, : K,CO, 62 : 38 mol%; under H,

at 65OOC and CO, at 600OC)

Platinum

Material I Gas atmosphere

H, CO,

22 4 2

Gold

321 -type Stainless steel

Palladium 140-42 I 38

66 Wets

20 Wets

Rhodium 168-70 138-40

Ruthenium 189-90 I Wets

Silver I 46 I 4 2

304-type Stainless steel I Wets I Wets

International Congress on Catalysis THE PLATINUM METALS FIND WIDE APPLICATION

The 9th International Congress on Catalysis (9th ICC) held in Calgary, Alberta, Canada during the week commencing 27 June 1988, was the latest in the series of congresses started at Philadelphia in 1956. Sadly, this meeting also marked the death of Prof. R. B. Anderson, who had contributed much to the understanding of catalysis as well as being co-chairman of the 9th ICC organising committee.

Almost 100 lectures and 170 posters were presented by authors from over 30 countries during the five day meeting, which was attend- ed by some 850 delegates. The theme of “Catalysis: Theory to Practice” attracted con- tributions from academic and industrial workers, especially from the chemical process industries. Environmental issues were not over- looked despite the surprisingly low number of papers addressing pollution control technology, and much was made of the need to minimise industrial pollution by the use of suitable processing techniques.

Many of the papers were concerned with the catalytic properties of the platinum group metals, and it is clear that the interaction between the noble metals and the catalyst support or promoters is attracting much attention. In particular, catalytic sites have been identified at the interface between noble metal particles and neighbouring oxide species, or associated with platinum group metal compounds such as sulphides, mixed oxides, silicides and borides. The use of EXAFS as a structural technique now appears to be almost routine. With such a wide ranging meeting, it would be difficult to include all the papers in this review, so the authors apologise for any omissions. The first four volumes of proceedings of the 9th Interna- tional Congress on Catalysis have been edited by M. J. Phillips and M. Ternan, and published by the Chemical Institute of Canada (1785 Alta Vista Drive, Suite 300, Ottawa, On- tario, KIG 3YS, Canada). Volume V, contain-

ing the plenary lectures and discussion, will be published shortly.

Synthesis Gas Conversion Platinum group metal catalysts are well

known for their ability to convert synthesis gas. Prof. A. T. Bell, of the University of California, gave a plenary lecture reviewing the current understanding of the Fischer-Tropsch reaction to form hydrocarbons. A number of techniques including infrared, reactive scavenging and radio-tracers showed that the rate determining step is dissociative adsorption of carbon monoxide, which is enhanced by co-adsorbed hydrogen. The carbon atoms are then hydrogenated giving a pool of reactive, adsorbed hydrocarbon intermediates. C. A. Mims, L. E. McCandlish and M. T. Melchior (Exxon Research and Engineering Company, U.S.A.) speculated that this may include C2 species. A single crystal study by F. M. Hoffman and J. L. Robbins (Exxon Corporate Laboratories, U.S.A.) suggests that co-adsorbed hydrogen promotes carbon monoxide dissociation by removing oxygen atoms from the surface, thus preventing recombination of carbon and oxygen atoms. G. A. Melson and E. B. Zucker- man, of the Virginia Commonwealth Uni- versity, compared bifunctional ruthenium/ zeolite catalysts with conventional ruthenium/ alumina catalysts. Impregnation of the zeolite ZSM-5 with triruthenium dodecacarbonyl deposited ruthenium only on the external surface of the support particles. Examination of the product distribution showed that the zeolite supported catalyst had greater selectivity to aromatic and low molecular weight hydrocarbons. L. Petrakis, M. Springel-Huet, T. Ito (CNRS, France) and T. R. Hughes, I. Y. Chan and J. Fraissard (Chevron Research Co., U. S.A.) studied platinum dispersion in zeolites using a 129 Xe NMR signal seen only from Pt-Xe interaction inside the cages.


The selectivity of rhodium-containing catalysts for conversion of syngas to oxygenates attracted much debate, especially concerning the distinction between promoters which increase the rate of carbon monoxide dissociation and those which influence chain length and oxygenate selectivities. Several groups had studied the structure of bimetallic catalysts containing a transition metal and a noble metal. J. W. Niemantsverdriet, S. P. A. Louwers, J. van Grondelle, A. M. van der b a n , F. W. H. Kampers and D. C. Koningsberger (Eindhoven University, Netherlands) suggest that their FeIr/silica catalysts for methanol synthesis contained ferric ions in addition to an iridium-iron alloy. M. Ichikawa, A. Fukusha and T. Kimura (Hokkaido University, Japan) achieved a similar structure when bimetallic Group VII/ iron/silica catalysts were prepared using mixed metal carbonyl clusters, for example Rh,Fe, instead of the chlorides and nitrates used by the Dutch group. The role of the rhodium precursor (chloride and nitrate) was also studied by B. J. Kip and E. G. F. Hermans (Eindhoven University) and R. F’rins (ETH Zurich, Switzerland), who concluded that differences in metal particle morphology were more important than residual anions on the support. A dual site mechanism was proposed by N. A. Bhore, C. Sudhakar, K. B. Bischoff, W. H. Manogue and G. A. M i l l s of Delaware University for oxygenate synthesis using rhodium/molybdenum/ alumina; rhodium activated the carbon monoxide which was then hydrogenated by hydrogen atoms migrating from pentavalent molybdenum sites which had dissociated the molecular hydrogen.

Synthesis gas processes using platinum group metals catalysts which have been commercial- ised are mainly homogeneous reactions. H. Bach, W. Gick, W. Konkol and E. Wiebus, of Ruhrchemie A.G., West Germany, described a recent development in the hydroformylation of alkenes to aldehydes; the new Ruhrchemie- R h h e Poulenc process uses a homogeneous rhodium catalyst rendered water soluble by its sulphonated phosphine ligands. Other papers on homogeneous processes included a kinetic

study on the direct formation of ethylene glycol from synthesis gas using ruthenium and rhodium complexes by T. Deguchi, M.

tom0 Chemical Co., Japan) and the production of formamides and amines using ruthenium melt catalysts by J. F. Knifton, D. C. Alex- ander and E. E. McEntire (Texaco Chemical Co., U.S.A.).

Tamurn, M. Ishino and S. Nakamura (Sumi-

Hydrotreating and Hydrogenation Prof. H. Knozinger of the University of

Miinchen, West Germany, reviewed current hydrodesulphurisation (HDS) catalysis technology, then indicated the growing interest in hydrodenitrogenation (HDN). Although commercial HDS catalysts are predominantly sulphided base metals (CoMo and NiMo), there is interest in platinum group metals especially for HDN. J. M. van der Eijk, H. A. Colijn and J. A. R. van Veen (Shell-KSLA, Netherlands) had compared Group VIII metals with sulphided catalysts for the HDN of quinoline and reported significant differences in behaviour; ruthenium and rhodium were very active but also promoted C-C hydrogenolysis; whereas platinum, palladium and iridium had lower HDN activity but better selectivity. The hydrogenation of biphenyl using a nickel- ruthenium mixed sulphide had been studied by M. Vrinat, M. Lacroix and M. Breysse (CNRS, France) and A. Bellaloui, L. Mosoni and M. Roubin (Univ. Claude Bernard, France); pure NiS, converted to inactive Ni,S, in the reactor, whereas mixed sulphides with more than 17 atomic per cent ruthenium retained an active pyrite structure. The high activity of the pyrite structure of RuS, was also noted by Y. J. Kuo and B. J. Tatarchuk of Auburn University, U.S.A., during thiophene HDS. Sulphidation temperature and HIS : H, ratio were believed to affect the surface structure with respect to S-S and M-S bond formation.

The roles of metal edge and face catalytic sites during liquid phase hydrogenation of a probe molecule, (+)-apopinene, using palladium/silica and platinum/silica catalysts were reported by G. V. Smith, D. Ostgard and


T. Nishizawa of Southern Illinois University, U.S.A., and F. Notheisz, A. G. Zsigmond and M. Bartok (Joszef Attila Univ., Hungary). In- cremental poisoning by CS * provided evidence that hydrogen dissociation and rapid *-ally1 isomerisation occurred on edge sites, whereas face sites accounted for addition and slow isomerisation. The role of adsorbate chemisorption strength and hydrogen surface coverage was used by J. Massardier, J. C. Bertolini and A. Renouprez (CNRS, France) to explain the difference in activity and selectivity between different palladium single crystal faces and palladium/silica for the hydrogenation of butadiene. A comparison between several Group VIII metal catalysts for deuterium exchange with hydrocarbons was given by R. Brown, C. Kemball and I. H. Sadler (Uni- versity of Edinburgh, U.K.).

A multi-step process using a promoted platinum/silica catalyst was described by M. Rusek (CIBA GEIGY, Switzerland) for the n- alkylation of anilines. This appeared to be a bifunctional catalyst, making use of the hydrogenation activity of the platinum and the acid- base properties of the support which were readily modified by the addition of alkaline earth ions. D. Richard, P. Fouilloux and P. Gallezot (CNRS, France) had studied the liquid phase hydrogenation of cinnamaldehyde using platinum/carbon catalysts. Charge transfer to the platinum particles, either from steps in the graphitic surface or from iron promoter atoms, improved the selectivity to cinnamyl alcohol. Iron also played an additional role by activating the C = O bond.

The effect of support and catalyst pretreatment on hydrogenolysis catalysts was discussed by several authors. G. C. Bond and R. R. Rajaram (Brunel University, U.K.) and R. Burch (University of Reading) had investigated ruthenium catalysts supported by titania, alumina and silica. Contamination of ruthenium/titania by chloride seemed to inhibit hydrogen spillover onto the support. Residual chloride was also examined by H. Miura, H. Hondou, K. Sugiyama, T. Matsuda and R. D. Gonzalez (Saitama University, Japan), who

supported the view of the previous authors concerning the partition of chloride between metal and support. They estimated that an ensemble of 4 to 5 ruthenium atoms was required for propane hydrogenolysis. Particle morphology was another factor influencing catalyst performance; according to E. J. Braunschweig, A. D. Logan, S. Chakraborti and A. K. Datye of the University of New Mexico, different oxidation and reduction procedures caused changes in the metal morphology of rhodium/silica catalysts.

Bimetallic Catalysts Bimetallic catalysts often exhibit activities

and selectivities for hydrogenation or hydrogenolysis of hydrocarbons that are dramatically different from those of their monometallic counterparts. A. J. den Hartog, M. Holder- busch, E. Rappel and V. Ponec (University of Leiden, Netherlands) have studied alloys of iridium with either copper or gold and argue that mixed iridium/copper ensembles are present. The effect of pretreatment on the surface composition of platinum-ruthenium/silica catalysts was discussed by M. Asomoza, G. del Angel, R. Gomez, E. Rejai and R. D. Gonzales of the University of Illinois; surface segregation of platinum was favoured by vacuum drying, although 'air drying reduced the subsequent reduction temperature. A. J. Hong, B. J. McHugh, L. Bonneviot, D. E. Resasco, R. S. Weber and G. L. Haller (Yale University) proposed that copper could form either 2-dimensional layers or 3-dimensional islands on the surface of ruthenium supported on different grades of silica. These differences in morphology had a profound effect on the performance of the catalyst.

The beneficial effect of the addition of a second metal, for example rhenium, tin or germanium, to platinum/alumina reforming catalyst is well established. Temperature programmed techniques and X P S were used by J. N. Beltramini (University of Queensland) and D. L. Trimm (University of New South Wales) to show that reduced germanium improves the activity of the catalyst, whereas unreduced germanium oxide promotes coking.


Similar effects with platinum-tin/alumina were reported by A. Sachdev and J. Swank of the University of Michigan; divalent tin was present and promoted hydrogen mobility.

Pollution Control and Poison Resistance

The poison resistance of platinum group metals can often be enhanced by the physical properties of the support. S. Nishiyama, T. Yoshida, Y. Nishikawa, S. Tsuruya and M. Masai (Kobe University, Japan) applied a thin coating of silica to platinudalumina catalysts and found no deactivation due to deposition of organo-nickel or organo-vanadium during hydrogenolysis of n-hexane. A metal-support interaction was discussed by M. Guenin, P. N. da Silva, J. Massardier and R. Frety (CNRS, France) as a means of weakening metal-sulphur bonds and so improving the thiotolerance of iridiudmagnesia and iridium/silica-alumina catalysts.

The reactions of carbon monoxide with oxygen and nitric oxide over noble metal catalysts are important for the catalytic control of automotive exhaust emissions. Addition of molyb- dena and ceria to rhodiudsilica catalysts for the reduction of nitric oxide by carbon monoxide was described by W. C. Hecker, M. D. Wardinsky, P. C. Clemmer and R. B. Brene- ham (Brigham Young University, U.S.A.), who found that ceria increased the rhodium dispersion, whereas molybdenum decreased it. The activities of the rhodium and rhodium- molybdenum catalysts were comparable, but the catalysts differed in terms of rate order with respect to carbon monoxide and nitric oxide. C. H. F. Peden, P. J. Berlowitz and D. W. Good- man (Sandia National Laboratories, U.S.A.) reported carbon monoxide oxidation kinetics on rhodium( I I I) single crystals. Under highly oxidising conditions, the near surface region became oxidised (possibly to Rh,O,) and the decomposition of carbonate-like intermediates became rate-limiting. Rhodium(111) was also used by G. B. Fisher, S. H. Oh, C. L. Di- Maggio and S. J. Schmeig (General Motors Research Laboratory, U.S.A.), and D. W.

Goodman and C. H. F. Peden (Sandia National Laboratories) to study the inhibition of carbon monoxide oxidation by nitric oxide. They suggest that the dissociation of nitric oxide at moderate temperatures leads to inhibition of oxygen adsorption by high coverages of nitrogen atoms. Another paper, by F. C. M. J. M. van Delft, K. Siera, R. J. Vreeberg and M. J. Koster van Groos (University of Leiden), and A. D. van Langeveld and B. E. Nieuwenhuys (Eindhoven Univeristy) examined the effect of the surface structure of platinum-rhodium alloys on the adsorption of nitric oxide dissociation, which appeared to be faster on rhodium- rich surfaces, especially those with higher index crystallographic planes.

Carbonyl Clusters and Unusual Compounds

A plenary lecture on catalysts derived from carbonyl clusters was given by Prof. L. Guczi of the Hungarian Academy of Sciences. A number of authors had used carbonyl clusters to prepare catalysts but there were contri- butions which specifically examined the behaviour of the cluster during preparation and use. In particular, cluster integrity, modes of decomposition and the role of the cluster- support interaction in inhibiting nucleation were discussed. S. D. Jackson and G. Owen (ICI, U.K.), and R. B. Moyes, M. S. Roberts, C. G. Scott, P. B. Wells and P. Worthington (University of Hull) described the conversion of hexameric osmium clusters to stable h e r s when supported on a cadmium sulphide support. H. H. Lamb, T. R. Krauss and B. C. Gates (University of Delaware) also had used osmium clusters but stressed the importance of anion formation on basic supports such as magnesia. EXAFS had been used by F. B. M. Van Zon, G. Visser and D. C. Koningsberger (Eindhoven University) to identify flat metal particles when a tetrairidium dodecacarbonyl cluster was supported on alumina. They suggested that the metal-support interaction involved long 0-Ir bonds, possibly as an Ir-(OH) interaction. Another study using EXAFS examined the genesis of platinum particles


formed by impregnation using chloroplatinic acid. F. Le Normand, D. Bazin, H. Dexpert and P. Lagarde (Univ. de Paris Sud, France) and J. P. Bournonville (IFP, France) obtained Pt-Pt, Pt-C1 and Pt-0 bond lengths using EXAFS every 15 minutes during slow isothermal decomposition/reduction of the catalyst precursor.

The Wacker process normally uses aqueous palladium dichloride to convert alkenes to aldehydes. The palladium is reduced to the metal but this is immediately reoxidised using a Cu(I)/Cu(II) couple which in turn is reoxidised by air. E. van der Heide, M. de Wind, A. W. Gerritsen and J. J. F. Scholten (Delft University, Netherlands) described a stable, heterogenised Wacker catalyst which operated in the same manner as the homogeneous catalyst system except that the Cu(I)/Cu(II) couple was replaced by a monolayer of vanadia applied to either alumina, titania or zirconia. Another example of a heterogenised, homogeneous catalyst used a monomeric palladium complex co- ordinated to the interlayer support of an aminated lithium hectorite. S. Shimazu, T. Ishada and T. Uematsu of Chiba University, Japan, claimed that the intercalated palladium catalysts showed higher activity and selectivity than the unsupported palladium complex for the liquid phase hydrogenation of isoprene. S. B. Ziemecki (DuPont, U.S.A.) used palladium to enhance the redox properties of phosphorus- vanadium-molybdenum heteropolyacids.

Two papers from the Polish Academy of Sciences concerned the catalytic properties of

palladium compounds. Work by W. Juszczyk, Z. Karpinski, J. Pielaszek, I. Ratajczykowa and Z. Stanasiuk on the reaction between neo- pentene and hydrogen suggested that high temperature reduction of palladium/silica led to the formation of palladium silicide, which was less active than pure palladium but more selective toward isomerisation. Palladium black catalysts prepared by borohydride reduction are known to contain boron; W. Palczewska, M. Cretti- Bujnowska, J. Pielaszek, J. Sobczak and J. Stachurski described the effects of segregation of boron to the surface under the influence of various pretreatments. Enrichment of the surface with palladium boride was found to increase the stereoselectivity during the hydrogenation of acetylenic groups.

Concluding Remarks This was a fascinating meeting. Platinum

group metals are used in a wide range of catalysts from platinum bimetallics for reforming petroleum products to carbon-supported systems for the synthesis of fine chemicals and drugs; and platinum metal technology is con- tributing significantly to the prevention of further deterioration of the environment. Already widely used, it is clear that in future years the platinum group metals can increase the role that they play in catalysis. The high interest in platinum group metal catalysts will, undoubtedly, lead to continuing study and further discussions at the Tenth International Congress on Catalysis to be held in Hungary in 1992. N.J.G., R.R.R.

Geology and Geochemistry of the Platinum Metals Platinum-Group Element Exploration, Developments in Economic Geology BY D. L. BUCHANAN, Elsevier, Amsterdam, 1988, 185 pages, U.S.$79/Dfl.150

The price of platinum over the past decade, supported by increasing demand for the metal for ihdustrial, investment and decorative purposes, has helped to stimulate worldwide interest in exploration for the platinum group elements; the publication of this book is therefore timely. It presents a set of guidelines for implementing an exploration programme and assessing the economic potential of an ore

body, and is supplemented by a bibliography of some 130 items. As well as providing mining geologists with a wealth of practical information, much of which is based upon the author’s experience of the rocks of the Bushveld Igneous Complex, the book contains information that will be of interest to users of the platinum metals who wish to know of the geological factors that govern their availability.


A BS TRA CTS of current literature on the platinum metals and their alloys

PROPERTIES High Temperature Oxidation of Pt-45Pd- 1 ORh G. W. GRAHAM, T. J. POTTER, W. H. WEBER and H. S. GANDHI, Oxid. Met., 1988, 29, (5/6), 487-497 Following earlier studies of oxidation-induced com- positional changes on the surface of Pt-Rh and Pd-Rh foils, the surfaces of Pt-45Pd-1oRh foils have now been examined after oxidation at 875-1075K, in 20%02-Ar at atmospheric pressure. A thin surface layer of mainly PdO formed at the lower temperatures, and pure PdRhO? at 1o75K.

The Effect of Cr and W Nucleation Layers on the Magnetic Properties of Copt Films J. K. HOWARD, J. Appl. Phys., 1988, 63, (8), 3263-3265 Alloy fdms of CoPt are of interest for use as recording media in high-density longitudinal recording technology. With the aim of improving magnetic properties, Co,Pt, fdms were deposited onto 1000A thick layers of Cr, O V alloy and W. Significantly higher coercivity values, of 2415 Oe, were observed on the W/Co,Pt, composite, compared to 1925 Oe for CrV/Co Pt , . Detection of Short- and Long-Range Order in Cu-Pt Alloys 1. BANHART, W. PFEILER and J. VOITlhIDER, Phys. Rev. B, 1988, 37, (II), 6027-6029

Short-range order (SRO) and long-range order (LRO) were studied in Cu-Pt alloys at various temperatures and compositions by means of the electrical resistivity measurements. Stable long-range- ordered equilibrium states can be achieved by thermal treatment. The effects of SRO and LRO can be separated for the non-equiatomic compositions by ex- amining the resistivity change on SRO and LRO.

Disordering and Recrystallisation of Pt- Ni-Cu Alloys

and YU. G. WOV, Fiz. Met. Metallwed., 1988, 65, (9, 967-969 The temperatures of recrystallisation and disordering of Pt,Ni,-,Cu, (x=o, 3, 5, 10, 15 and 25at.%) alloys were measured by differential and resistometric analysis at 3w-750°C. The results showed that regulating the annealing of these Pt alloys after plastic deformation does not eliminate its after effect, and heating of the disordered alloy is followed by recrystallisation. The position of temperature intervals in these processes and the effect of heat on the disordered alloy depended on the Cu concentration.

0. N. OGORODNIKOVA, V. S. LITVINOV, A. A. KURANOV

Concentration Changes of Pt and Si in a PtlPoly-Si Thin Layer System between 750 and 1000°C G. L. P. BERNING and C. w. Low, Appl. Surf. Sci.,

A Pt/polycrystalline Si/SiO,/Si( 100) multilayer system was prepared and annealed at 750°C in order to grow a PtSi layer on the polycrystalline Si layer. Upon subsequent annealing at 82ooC the unreacted polycrystalline Si diffused partly into the PtSi. When equilibrium was reached at 88ooC, the polycrystalline Si and PtSi layers were almost completely separated with the Si nearer to the surface. After annealing at iooooC for 10 min, the Pt and Si concentrations were constant throughout the top layer.

Interdiffusion in Platinum-Tin Oxide Multilayered Films

Len., 1988, 7, (6), 669-670

The interdiffusivity of polycrystalline Pt-SnO, multilayered fdms with an interplanar distance I of - 3 . 5 ~ 1 was investigated after the fdms were formed. X-ray diffraction patterns after annealing at different temperatures and for different times provided 9 x 10- 2z cm2 /s at 5moC for the interdiffusivity . Phase Equilibria in the RuO -Bi 0 -PdO System

Lett., 1988, 7, (61, 637-638 The phase equilibria in the title system were investigated because of possible reactions between the components during manufacture of thick fdm resistors. Phase diagrams for PdO-RuO,, PdO- Bi,O,, Ru0,-Bi,O, and the ternary system are presented. There was no ternary compound. The tie lines are between PdO-Bi,Ru,O,, and Bi,Ru,O,,- Bi,PdO,. The results show that there is no reaction between the conductive phase in thick fdm resistors (either RuO, or Bi ruthenate) and PdO during the fving of thick fdm circuits.

Critical Behaviour of Amorphous Gdo.7oPdo.soH0.20

1988, 31, (411 420-425

T. SUZUKI, T. YAMAZAKI and T. YOKOI, J. Mater. sci.,

M. HROVAT, S. BERNIK and D. KOLAR, 3. Mater. sci.,

D. J. GRIFFITHS, G. GOLD, 8. BOUCHER and R. TOURBOT, J. Phys. F, 1988, 18, (9, 993-1000 The magnetisation of amorphous Gdo.,Pdo.,H0.,, which was prepared by sputtering, was measured at 100 and 3ooK in fields of up to 5kOe. W e the Curie temperature, T,, was much lower than that observed for undiluted liquid-quenched amorphous Gd,70Pdo.,, the magnetic response in low fields was identical, indicating that the critical behaviour of the amorphous system does not change upon H addition.

Platinum Metals Rev. , 1988, 32, (4), 209-216 209

Decoupled Bulk and Surface Crystalliza- tion in PdssSi,5 Glassy Metallic Alloys: Description of Isothermal Crystallization by a Local Value of the Avrami Exponent A. CALKA and A. P. RADLI~SKI, 3. Muter. Res., 1988, 3, (11, 59-66 The isothermal devitrification of Pd,, Si,, amorphous alloys was studied by differential scanning calorimetry and XRD. The crystallisation of aged samples starts from the surface and proceeds several micrometers into the bulk, producing a layer of strongly textured Pd( I I I) followed by a mixture of Pd,Si, Masumoto MSI phase and untextured Pd. The crystallisation occurs via a different (bulk) mechanism, resulting in a mixture of Masumoto MSII phase and untextured Pd. The bulk mechanism is the only one observed in as-quenched samples. The observed variation of the Avrami coefficient, n, with the crystallised volume fraction, x, is explained by a change in nucleation rate during devitrification.

Evidence from Hydrogen Solubility

Hypostoichiometric Alloys of Pd, Mn

and Y. SAIL~IOTO, Scr. Metall., 1988, 22, (4), 511-515 Pd-Mn alloys were prepared and H solubilities at various temperatures for the quenched form of each alloy were measured. Ordering in the alloys, electrical resistance behaviour, H solubilities and electron diffraction patterns were obtained as the alloys were put through various cooling regimes. There are abrupt increases in the H solubility and electrical resistance as quenched samples of hypostoichiometric Pd ,Mn are heated. This is attributed to ordering of the alloy matrix. Low temperature H solubility comparisons of quenched and slowly cooled alloys show large differences, which support the fact that ordered forms exist. The electron diffraction patterns indicate that the order is of the Ag,Mg type, which is found in Pd , Mn after annealing in vacuo.

Physical Properties of Icosahedral and Glassy Pd-U-Si Alloys

Studies for Ordering in

A. ewLFT, R. FOLEY, T. B. FLANAGAN, K. BABA, Y. NIKI

P. G R h E R , H. BRE'ISCHER, G. INDLEKOFER, H. JEN- NY, R. LAPKA,.P. OELHAFEN, R. WIESENDANGER, T. ZINGG, €I.-]. GUNTHERODT and J.-B. SUCK, Muter. sci. Eng.9 198% 999 357-360 Various physical properties were measured on glassy, crystalline and quasicrystalline samples of the Pd-U- Si system. Large differences are observed between the static structure factors of the quasicrystalline and glassy samples; however, their dynamic properties are nearly identical but quite different from those of the fully crystallised samples. The general features of the valence electron structure of the quasicrystalline phase are very similar to those of the corresponding glassy alloy, and similar intensities at the Fermi energy are observed. The electrical resistivity, the Hall coefficient and the magnetic susceptibility have been measured to high temperatures.

On the Stability of the Ordered Pd8V Phase in a Proton-Irradiated Pd-l5at.%V Alloy

19% 14x3 (I) , 45-53 The maximum temperature at which the ordered Pd,V phase forms in a Pd-Isat.%V alloy irradiated by 400 keV protons was found between 350 and 420OC. Annealing studies after irradiation showed that Pd,V is most probably a thermodynamically stable equilibrium phase with a critical ordering temperature slightly below 400OC. Interstitial dislocation loops are prevalent in the microstructure of samples irradiated at 2o0°C, whereas more widely extended stacking fault ribbons are commonly observed at irradiation temperatures of 420OC. The diameters of the loops were smaller at 200OC than at 35Ooc. The segregation of undersized V atoms to these defects causes the preferential formation of Pd, V in regions between them.

J. CHENG and A. 1. ARDELL, J. Less-Common Met.,

CHEMICAL COMPOUNDS Rhodium and Iridium Oxometallates-A New Class of Solid Microporous Materials

SKARJUNE, K . 0. HODGSON, A. L. ROE and v. w. DAY, Solid State Ionics, 1988, 26, (z), 109-117 Organometallic Keggin ion complexes, [(Ph3P),Rh(CO)I, SiW,,O, and [(Ph,P),IrH, I , P- W,,O, have been characterised by solid state NMR and X-ray absorption spectroscopy. They constitute a new class of chemically microporous solids, and show how large molecular metal oxide clusters can form extensible lattices in which co-ordinatively unsaturated organometallic cations can be stabilised and studied. In some cases these cations are mobile and form bimetallic species. Reactions involving olefm isomerisation, hydroformylation, hydrogenation, dehydrogenation and C-H activation are described.

A. R. SIEDLE, R. A. NEWMARK, W. 8. GLEASON, R. P.

ELECTROCHEMISTRY Adsorption and Oxidation of Methanol and Formic Acid on Platinised Platinum Modifed with Tin Adatoms

E. KAZARINOv, Elektrokhimiya, 1988,24, (s), 686-690 The kinetics of adsorption and oxidation of methanol and formic acid on a platinised Pt electrode modified with Sn adatoms was studied in solutions of CH , OH, HCOOH and H,SO, at potentials of 0.2-0.4V by potentiodynamic impulse and radioactive indicator methods. Adsorption of methanol resulted in the formation of a COH product and also produced higher oxidised HC particles. In static conditions, the pro- portion of these adsorbed particles increases with an increase in the number of Sn adatoms on the electrode. The dependence of the rate of electro- oxidation of HCOOH on H, is confmed.

M. A. STITSYN, A. N . ZHUCHKOV, V. N. ANDREEV and V.


The Electrochemical Reactivity of Toluene at Porous Pt Electrodes

BALTRUSCHAT and J . HEITBAUM, 3. Electroanal. Chem. Interfacial Electrochem., 1988, 244, (I and z),

The electroreduction and electro-oxidation of toluene adsorbed on Pt electrodes were studied spec- trometrically. Part of the toluene starts to desorb at the potentials where H, adsorption begins. At potentials below 0. IV, hydrogenation to methylcyclohexane also occurs. Adsorbed intermediates which are in a higher oxidation state than toluene are also formed, and can only be oxidised in subsequent sweeps.

High Temperature Water Electrolysis: The Cathodic Process at the Cermet (Pt+ La,,,Sr,~,CrO,)/Zirconia Interface

26, (31, 240-250 Studies were made of the kinetics of the reduction of steam at the interface between a Pt containing cermet and an yttria stabilised zirconia electrolyte to find the effect of 3owt.%Pt embedded in the cermet. The presence of an outer porous Pt layer deposited onto the underlying cermet layer resulted in a great increase of the kinetic parameters of the overall reaction. However, the presence of metallic Pt embedded in the structure of the mixed oxide layer, restricted the section available for diffusion of reducible species.

The Effect of Palladium on Hydrogen Ab- sorption and Mobility in AISI 4130 Steels

Sci., 1988, 28, (9, 461-470 The effect of Pd in solid solution on the H absorption and mobility in AISI 4130 steels was studied by cathodic polarisation and H permeation techniques in IN NaOH. Pd additions resulted in a higher H permeation rate due to an increased diffusivity and a decreased H trapping effect. No significant differences were observed in the cathodic polarisation parameters as a result of these Pd additions, showing the effect of Pd is a bulk metallurgical effect. The work shows that Pd segregates to potential H traps and subsequently repels H from these sites.

Electrocatalytic Oxidation of Formic Acid on Pd+Pt Alloys of Different Bulk Com- position in Acidic Medium A. PAVESE, v. SOLIS and M. c. GIORDANO, 3. Elec- troanal. Chem. Interfacial Electrochem., 1988, 245, ( I and 2), 145-156 The electroadsorption and oxidation of formic acid on two Pd + Pt alloys of different bulk composition were studied and compared to values taken on pure metals. The HCOOH dehydrogenative adsorption is faster on Pd sites, but the strongly adsorbed intermediate is formed only at Pt sites, irrespective of the Pd atom neighbourhood. The synergetic effect observed with the alloys is time and potential dependent.

J. ZHU, TH. HARTUNG, D. TEGTMEYER, H.

273-286

G. B. BARB1 and C. M. M I , solid state IOnkS, 1988,

F. FONDEUR, T. A. MOZHL and B. E. WILDE, COrrOS.

Electrochemical Reduction of Nitrate and Nitrite in Concentrated Sodium Hydrox- ide at Platinum and Nickel Electrodes

Electrochem. SOC., 1988, 135, (9, 1154-1158 The electrochemical reduction of nitrite and nitrate in concentrated NaOH solution at Pt, Ni and platinised Ni electrodes was studied as a function of electrode material, temperature and solution composition. Electrolysis of NaNO, in 3M NaOH+o.qM Na,CO, at 8o°C on platinised Ni cathodes resulted in high current efficiency for the overall electrode reaction, a five-electron reduction to N,. NH, is formed in constant current electrolyses at high current densities. The presence of 0 in the cathode com- partment increased the rate of nitrate reduction under these conditions. Voltammetric studies showed that electrode reaction involves surface phenomena and is not mass transfer controlled. Maximising current efficiency for producing N, or NH, gas can have much significance for treating radioactive waste solutions.

Electrooxidation of Methanol on Platinum Bonded to the Solid Elec-

H.-L. LI, D. H. ROBERTSON and J. Q. CHAMBERS, 3.

trolyte, Nafion 2

A. ARAMATA, T. KODERA and M. MASUDA, 3. Appl. Electrochem., 1988, 18, (4), 577-582 The electro-oxidation of methanol was enhanced on binary electrodes PtSn-SPE, PtRu-SPE and PtIr-SPE (SPE is a solid polymer electrolyte, Nafion) in H,SO, solution, when compared with the activity of Pt-SPE, which is known to have a higher activity than a F't electrode. This dual enhancement of the oxidation rate for PtSn-SPE and PtRu-SPE catalysts is due to the modification of the oxidation state of Pt by Sn and Ru and to the presence of H,O and CH,OH, both modified by the SPE matrix. This modification appears to weaken their H bonds in solution. The PtIr-SPE catalyst had enhanced catalytic activity compared to F't or Ir. This is discussed in terms of Ir oxidised at relatively low positive potentials, assisting the redox process of Pt0/Pt2+ or Pt2+/Pt'+ in the SPE matrix.

Characteristics of Platinum Group Metal Anodes Prepared by Thermal Decom- position Method T. MURANAGA, Denki Kagaku, 1988, 56, ( z ) , 117-123 The Tim-IrO, anode showed low c1 and high 0, overvoltage characteristics. PdO can be used as the diluent of IrO, in the Tim-IrO, anode, as long as the IrO, content in the anode is kept over 15%. The Ti/Pt-IrO2(30) and Ti/R-Ir0,(20)-PdO(xo) anodes showed high current efficiency in a chlorate cell and a diaphragm cell compared to Ti/TiO,- Ru0,(3omol%) anode. The use of the anode made of thin layer TiO,/Pt-IrO, (30) layer improved durability to Na-amalgam cathode. A modified T i m - IrO,(3o) anode was effective for maintaining high current efficiency in ion-exchange membrane cells because of low c1 and optimum 0, overvoltage.


Effect of Phosphates on the Corrosion and Electrochemical Behaviour of Ruthenium-Titanium Oxides Anodes and Ruthenium Dioxide

N. YA. BUNE and v. v. GORODETSKII, Elektrokhimiya, 1988, 24, (6), 850-853 The effect of phosphates on the corrosion and electrochemical behaviour of Ru-Ti oxide electrodes and RuO, was studied in various pH and NaCl concentrations at 87OC, and at anodic current density of o.zA/cm2. The electrodes contained 30mol Oh RuO,, 7omol% TiO2(4.5g Ru/mz) and Ru02(z6g Ru/mz). The phosphate ions which adsorbed on Ru-Ti oxide anodes and on RuO, decreased the corrosion rate, and 0, was exposed on the anodes, without any substantial overloading of the c1 reaction. It is suggested that the addition of small amounts of phosphate may increase the stability of the anodes.

Spontaneous Oxidation of Water to Oxygen by the Mixed-Valence p-0x0 Ruthenium Dimer L (H O)RU"'-O-RU'~ (OWL, (L= 2,2'-bipyridyl-5,5 '-dicar- boxylic Acid)

M. GRATZEL, 3. Chem. soc., Chem. Commun., 1988,

The mixed-valence pox0 Ru dimer of the title converted spontaneously into L,(H,O)RU'"-O- Ru"'(H,O)L, with simultaneous oxidation of H,O to 0, at a very low thermodynamic driving force of the reaction, of <o. IeV per transferred electron. The unique feature of this complex is that the catalytically active state is accessible at very low overvoltage. This behaviour is unprecedented in homogeneous H, 0 oxidation catalysis. The finding could be useful in modelling the processes occurring on the surface of catalysts, such as colloidal RuO,, and represents great progress in the development of artificial analogues of the green plant H ,O splitting enzyme.

M. M. PECHERSKII, S. V. EVDOKIMOV, L. E. CHUVAEVA,

M. K. NAZEERUDDIN, F. P. ROTZINGER, P. COMTE and

( I D , 872-874

PHOTOCONVERSION The Photocatalytic Activity of a Platinized Titanium Dioxide Catalyst Supported over Silica K. DOMEN, Y. SAKATA, A. KUDO, K.-I. MARUYA and T. ONISHI, Bull. Chem. Soc. Jpn., 1988, 61, (2),

359-362 The effects of different loadings of platinised TiO, on the photocatalytic activity of H, evolution from aqueous methanol over Pt-TiO, /SiO, catalysts was studied. The optimum calcination temperature for catalytic activity was at 998K. For all the catalysts studied there was an optimum Pt loading for the amount of TiO, present which gave maximum H, evolution. The activity for H, evolution decreased with the decrease in the amount of supported TiO,/SiO, that is, with increase of dispersion.

The Structure of cis- and trans- Dichloroethenes Adsorbed on Pt( 1 1 1). Photochemical Reactions of cis- and trans-l,2-Dichloroethene Adsorbed on Pd( 1 1 1) and Pt( 1 1 1) v. H. GRASSIAN and G. c. PIMENTEL, 3. Chem. Phys., 1988, 88, (7), 4478-4483; 444-4491 The structures and photochemical behaviours of cis-I ,2- and trans- I ,z-dichloroethene (DCE) adsorbed on Pd( I I I ) and Pt( I I I ) surfaces were studied by EELS and TDS at 110-3ooK. For multilayer coverage on either metal surface, irradiation of physisorbed DCE at IIOK with broad band irradiation (A>2mnm) results in photoisomerisation, cis+trans. For monolayer coverage on Pt(r11) at IIOK, photolysis of chemisorbed DCE resulted in loss of the two C1 atoms to form a single HC product, chemisorbed acetylene. The study indicates that photochemistry of molecules chemisorbed on a metal surface is possible despite the proximity of the conducting surface.

Photoelectrochemical Characterization of Novel Rhodium Iodide Photocon- ductors M. w. PETERSON and B. A. PARKINSON, J. Electrochem. SOC., 1988, '35, (6), 1424-1431 The photoelectrochemical and physical properties of three Rh iodides, which form a new class of semiconducting and photoconductive materials, is reported. Crystalline and amorphous RhIl and especially the previously unreported RhI,,l-,,, (RhL ,) have been prepared and examined. The former are semiconductors with bandgaps in a range useful for photovoltaic and photoconductive devices. The structure of the latter material is predicted to be a chain of edge- sharing Rh iodide octahedra, where variations in preparation change the chain lengths and hence the electrical and photoelectrochemical properties. Large areas of thin fdm amorphous RhI, and RhL, are readily fabricated, which may make them attractive as photoconductors for, say, xerography.

Dehydrogenation of Saturated Hydro- carbons by Photocatalyeis Using Carbonyl (halogeno) phosphme - Rhodium Complexes K. NOMURA, H. KUMAGAI and Y. SAITO, Shokubai, 1988, 3% (z), 204-207 Remarkably high photocatalytic activities of the title Vaska-type Rh complexes RhX(CO)(PR,) , (X = halogen, PR, = ten-phosphine), were observed for alkane dehydrogenation, yielding alkene and H, . The wavelength and photointensity dependence studies showed that the trico-ordinate species RhX(PR,), , which were photogenerated under excitation conditions, are responsible for the catalysis cycle of alkane dehydrogenation with no photoassistance despite the thermodynamic difficulty. This catalyst design increases the concentration of catalytically-active species for C-H bond splitting.


APPARATUS AND TECHNIQUE

Quasi-Static and High Frequency C(V)- Response of Thin Platinum Metal-Oxide- Silicon Structures to Ammonia

Sens. Actuators, 1988, 14, (4), 369-386 Thin film Pt-gate MOS capacitors are of interest as possible NH, gas-sensitive devices. The effects of NH, exposure on the high frequency and quasi-static capacitance-voltage characteristic of Al and Pd Pt- MOS capacitors are discussed. There is a decrease in NH, sensitivity with decreasing Pt film thickness; this is related to the high impedance of the film and probably also to its microstructure.

Slow Quenches of High-Quality Single Crystals of Platinum and Palladium A. KHELLAF, R. M. EMRICK and J . J. WILLEMIN, Phys. Rev. B, 1988, 37, (12), 6717-6722 A new technique for growing and quenching high- purity, low-dislocation-density Pt and Pd single crystals is developed. This technique traps at least 87% of the vacancy concentration at 9% of the melting point without significantly increasing the dislocation density during the quench. It produces high quality single crystals with a controllable suwr-

T. FARE, A. SPETZ, M. ARMGARTH and I. LUh'DSTRdM,

Hydrogen Permeation through a Thin Film of Palladium: Influence of Surface Impurities R. LALAUZE, P . GILLARD and C. PIJOLAT, Sens. Ac- fuaton, 1988, 14, (3), 243-250 The influence of the surface state of a thin Pd film on H2 diffusion was investigated to improve the reliability of a Pd-MOS HI sensor. Surface states of the sample were analysed by a temperature programmed technique; C, S and 0 could affect H energetic adsorption sites and thus the gas permeation process through the membrane.

Ru(bipy) C1, Luminescence as Optical Step Signal for Detector Testing K. BRETTEL and E. SCHLODDER, Rev. Sci. Instrum., 1988 , 59, (4, 670-671 The use of picosecond-laser-flash-induced luminescence of the dye tris-(2,2'- bipyridyl)Ru(II)chloride as an optical step signal for testing the time response of fast optical detection systems is discussed. Following excitation at any wavelength between 250 and 550 nm, a single emission band between 570 and 700 nm is displayed which decays monoexponentially with a lifetime of - 600 ns in deoxygenated solution at room temperature.

- - ~ - HETEROGENEOUS CATALYSIS

saturation of vacancies for study by various t&h- niques, without significant background signals.

Effect of Heat Treatment on Physical Properties of Pt-Based Alloy Wires for High Temperature Strain Gauge Application B.-Z. FENG and D.-X. LI, Metall, 1988, 42, (7), 669-671

The effects of heat treatments on the resistivity, temperature coefficient of resistance, tensile strength, rate of elongation, elastic modulus, linear expansivi- ty, etc., on Pt-W and Pt-W-Re alloy wires used as sensors in high temperature strain gauges have been investigated. The optimum process for Pt-W involved solution heat treatment at 1 0 o o O C for I minute followed by water quenching and holding at 72oOC for 30 hours; for Pt-W-Re the optimum treatment was 1 0 o o O C for I minute, followed by water quenching, then stable treatment at 82oOC for 30 h.

Thin Palladium Films Prepared by Metal- Organic Plasma-Enhanced Chemical Vapour Deposition E. FEURER and H. SUHR, l?zin Solid Films, 1988, 157, (I) , 81 -86

A simple, low temperature method for the deposition of Pd films using allylcyclopentadienyl Pd complex is reported. In this organic plasma-enhanced CVD process bright metallic films can be produced at low temperatures producing films of pure Pd or composites with a wide range of electrical conductivity. The resistivity of these films approaches that of bulk Pd. If 0, is the carrier gas, the films are PdO.

The Role of Chlorine in the Regeneration by Hydrogen of Coked Reforming Catalysts A. PARMALIANA, F. FRUSTERI, A. MEZZAPICA and N. GIORDANO, J . Catal., 1988, 111, (z) , 235-242 The effect of surface c1 on the regeneration of several coked Ptly-Al, 0, honeycomb reforming catalysts has been investigated. Regeneration tests were performed at 40o0C, after the dehydrogenation of methylcyclohexane, in a continuous flow microreac- tor. A catalyst with -0.5% C1 shows complete regeneration during static and dynamic H I treatments, which is attributed to a maximum in the H I spillover from Pt to Al,O,, which restores the catalyst surface, freeing it of hydrocarbon residues.

Effect of Sulphur on the Dehydrocyclisa- tion of n-Hexane, n-Hexene and n- Heptane on Reforming Catalysts

Chem. Tech. (Leipzig,), 1988, 40, (5), 208-211

Studies of the effect of S pretreatment on the conversion of n-hexane, n-hexene and n-heptane over Pt/AI,O,, Pt-Re/Al,O, and Pt-Re-Cr/Al,O, catalysts were made at atmospheric pressure. The presulphidation stabilised the activity and selectivity of dehydrocyclisation and resulted in high yields of H, and liquid product. After repeated use Re containing catalysts without presulphidation became similar to sulphided ones, and after reactivation with CCl, in air high activity was obtained.

M. WILDE, R. STOLZ, R. FELDHAUS and K. ANDERS,


Dispersion and Catalysis of Platinum in Bimetal!Zeolite Catalysts

Catal., 1988, 39, (I-z), 255-265 The effects of modifier elements, such as Fe*+, both under oxidising and reducing conditions, on the formation of Pt particles in NaY zeolite, and the implica- tion of these interactions for the ultimate dispersion and catalytic activity of these Pt particles were studied. The unreduced transition metal ions interact chemically with the Pt metal panicles. The interaction appears to make use of the incompletely filled d orbitals of both Pt and anchoring ion. The modifier ions can block smaller cages during calcination, stabilise Ptz+ ions during and/or after calcination, and after reduction they can anchor Pt particles on the zeolite supports. The PtiFeNaY zeolite catalysts exhibited higher activities for benzene hydrogenation and n-hexane hydrogenolysis than PtMaY, but the activity for methylcyclopentane (MCP) hydrogenolysis was lower for PtiFeNaY. Catalysis of PtMaY was similar to that of Pt/SiO, , but the ring opening selectivity of MCP is different, due to geometric constraints.

The Effect of Electrochemical Oxygen Pum ing on the Steady-State and Oscifatory Behaviour of CO Oxidation on Polycrystalline Pt

1x1, ( I ) , 170-188

The effect of electrochemically pumping 0,- to or from a porous polycrystalline Pt catalyst film used for CO oxidation at atmospheric pressure and z50-600°C was studied. The Pt acted as a catalyst and as an electrode in the solid electrolyte cell CO, 0,, Pt/Zr0,(8 mol% Y,O,)/Pt, 0,. The pumping had a dramatic non-Faradaic effect; the steady-state reaction rate increases or decreases by a factor of 2,

but a 500% increase in reaction rate is observed under severely reducing conditions. Reaction rate oscilla- tions can be induced or stopped by adjusting the rate of O?- transfer and thus the electrode potential.

Isomerization of Ethylbenzene and m- Xylene on Zeolites Y. S. HSU, T. Y. LEE and H. C. HU, Ind. Eng. Chem. Res., 1988, 27, (6), 942-947 The simultaneous isomerisation of ethylbenzene and m-xylene on zeolite catalysts, including Pt/mordenite, Pt/USY, Pt/ZSM-5 and Pd/ZSM-5 has been studied. Pt/ZSM-5 was the best catalyst; Pd/ZSM-s was better than Pt/USY, although both are good enough for the reactions compared with Pt/mordenite. The transformation of m-xylene to o- or p-xylene may be limited by the mass-transfer rate of the diphenylmethane-type intermediate, and the formation of o-xylene from ethylbenzene may be restricted by the smaller protonated cyclopropane intermediate. The ratio p-xylene : o-xylene is increased with temperature, and is in the order:

H. 1. JIANG, M. S. TZOU and W. M. H. SACHTLER, Appl.

I . V. YENTEKAKIS and C. G. VAYENAS, J. catal . , 1988,

Pt/USY<Pd/ZSM-5 = Pt/ZSM-5.

Genesis and Characterization of Transi- tion Metal Clusters in Y Zeolites w. M. H. SACHTLER, M. s. TZOU and H. J. JIANC, Solid State lonics, 1988, 26, (2), 71-76 The size and location of Pt particles in Y zeolites largely depend on the calcination conditions following ion exchange. Calcination destroys NH, ligands and promotes migration of Pt ions from supercages to sodalite cages. Reduction then results in small Pt clusters in supercages, but large Pt particles form at the external surface if all the Pt ions are located in sodalite cages. When Pt ions are present in comparable quantities in both types of cages, those in the supercages are reduced at low temperature, and act as nucleation sites for Pt atoms leaving the sodalite cages at higher temperatures. By filling sodalite cages with auxiliary ions of other transition elements, the migration of Pt ions into such cages can be suppressed and higher Pt dispersion is obtained after reduction.

Liquid-Phase Hydrogenation of Buta- diene in the Presence of Palladium Based Catalysts

DIMITROV and v. M. FROLOV, Neftekhimiya, 1988, 28,

Studies of the mechanism of the liquid-phase hydrogenation of butadiene in the presence of o.oS-Iwt.%Pd/y-Al,O, catalysts showed a yield of butane at >go% selectivity. The Pd/y-Al,O, catalysts are characterised by maximum activity during hydrogenation, with less tendency to run a similar reaction of butene isomerisation.

Remarkable Activity Enhancement of Rh/A1203 Prepared from RhCl, for CO- H2 Reaction by the Pretreatment of High Temperature Evacuation

Jpn.2 1 9 8 8 , (41, 581-583 Studies of the catalytic activity of Rh/Al,O,, prepared from RhCI,, for the CO-H, reaction at 473 and 523K showed a remarkable enhancement by evacuation after the reduction of the catalyst. Evacua- tion at 773K after reduction with H, at 673K increased the activity of Rh/Al,O, to a maximum of 1200 mmol CO/g Rh h, comparable to that of RhiTiO, . Molecular Design of Heterogeneous Catalysts by Using Metal Cluster Complexes-Their Structures and Catalytic Properties M. ICHIKAWA and A. FUKUOKA, Shokubai, 1988, 30, (z), 168-171

Studies of bimetal cluster-derived catalysts prepared using SO,-supported Rh,Fe,, Rh,Fe, Ir,Fe, Pd, Fe, carbonyl clusters and NaY(NaX) zeolite- entrapped RhFe and Rh,-xIrx carbonyl clusters as the precursors showed very high activities and selectivities for C , -C, alcohol production in the CO+H, reaction, and higher alcohols in hydroformylation.

P. S. IVANOV, A. V. NOVIKOVA, 0. P. PARENAGO, KH.

(31, 320-323

H. FUJITSU, H. ISHIBASHI and I. MOCHIDA, Chem. Lett.

Platinum Metals Rev . , 1988, 32, (4) 214

Oxygen Transfer between Rhodium and an Oxygen-Ion Conducting Support

34, (61, 1048-1050 Highly dispersed Rh catalysts prepared on y-Al,O, and YSZ (yttria stabilised zirconia) supports were studied during automobile CO-NO exhaust conversion. The results showed that for CO oxidation, RNSZ and RhNSZ outperform Pt/AI,O, and Rh/Al, 0, , respectively, even under excess CO conditions. This is due to the YSZ support introducing an additional pathway for bringing 0, to the catalytic sites. The presence of H,O vapour increased the rate of the CO-NO reaction over both catalysts. The RhNSZ catalyst was found to be superior to the Rh/Al,O, catalyst under both wet and dry reaction conditions.

Effect of Particle Microstructure on Alkane Hydrogenolysis on Rh/Si02

210-219 Oxidation of Rh/SiO , , followed by low-temperature reduction in H , , produces hydrogenolysis activities for the catalyst which are up to l o J times higher than after high-temperature annealing in H, . The altera- tion in activity is larger for larger particle sizes and for C,H, than for C,H, or C,H,,. Freshly oxidised catalyst produces more CH, , while annealed catalyst produces larger alkanes. Activation in 0, begins at 25OC, and H,O is effective in partially activating the catalyst.

Lanthana-Promoted Rh/Si02. 11. Studies of CO Hydrogenation

I. S. METCALFE and S . SUNDARESAN, AIChE J., 1988,

S. GAO and L. D. SCHMIDT, 3. catal., 1988, 111, (I),

R. P. UNDERWOOD and A. T. BELL, 3. card . , 1988, 111, (21, 325-335 The influence of lanthana promotion on CO hydrogenation over Rh/SiO, was studied, and it was found that promoted catalysts exhibited higher turnover frequencies for the synthesis of CH,, C,-C, hydrocarbons, CH,OH and C, oxygenates than un- promoted Rh/SiO, . The turnover frequency for each product goes through a maximum with increasing lanthana addition. Selectivity for CH,OH, C, oxygenates and C,-C, hydrocarbons formation is also increased, while selectivity for CH, is decreased. Infrared observations show that lanthana promotion blocks the chemisorption of CO onto surface Rh sites, and also indicates acyl, formate and acetate groups on the catalyst surface.

Ethane Hydrogenolysis on a Ru( 1 , 1 ,lo) Surface c. EGAWA and Y. IWASAWA, Surf. Sci., 1988, 198, ( I lZ) , L329-L334 An investigation of the hydrogenolysis of ethane on a RU(I,I,IO) stepped surface has shown the steady state reaction rates to be one or two orders of magnitude higher than on supported catalysts. Active sites for the reaction are step sites composed of low co- ordination number surface atoms.

HOMOGENEOUS CATALYSIS Bulk Ruthenium as an HDN Catalyst A. S. HIRSCHON and R. M. LAINE, Energy & Fuels, 198% 2, (3, 292-295 A series of Group VI to Group VIII bulk metals was tested for HDN (the catalytic removal of N) activity by using a solution of tetrahydroquinoline in n- hexadecane. The results showed that bulk Ru is ex- ceptionally effective for C-N bond cleavage at temperatures as low as zoo°C and H pressures of 500 psig. Under similar conditions, Rh and Pt were less active, and Os, Ni, Mo and Re were inactive.

Hydrogenation of Dehydroamino Acid Derivatives in the Presence of Palladium(I1) Complexes with Methionine

SKAYA, v. K. LATOV and v. M. BELIKOV, Im. Akad. Nauk SSSR, Ser. Khim., 1988, (9, 1170-1172 Studies of the catalytic activity of Pd(I1) complexes with R- and S-methionine reduced by H, or NaBH, showed that the catalytic system formed during the interaction, complexes S- (or R)-MetHPdCI, , had high catalytic activity for the hydrogenation of industrial cinnamic acid, but the enantioselectivity of this reaction was only 3-3.4%. The hydrogenation of N-acetyldehydrophenylalanyl-S-tyrozine in presence of R- and S-MetHPdCI, yielded products with a diastereometric surplus of 18-24% R-S-isomer.

Formation Mechanism and Structure of Compounds Catalytically Active in Pro- pylene Dimerization and Formed in P ~ ( ~ C ~ ~ ) ~ - P R , - B F , O E ~ , Systems

I. N. LISICHKINA, A. I. VINOGRADOVA, M. B. SAPOROV-

V. S. TKACH, F. K. SCHMIDT, G. V. RATOVSKII, N. D. MALAKHOVA, N. A. MURASHEVA, M. L. CHERNYSHEV and 0. v. BURLAKOVA, React. Kinet. catal. Lett., 1988, 36, (zo), 257-262 Ultraviolet and I H NMR spectroscopic studies were performed of the interaction between the components of the catalytic system Pd(acac),-PR,-BF,OEt, during the dimerisation of propylene to linear hexenes with 59% selectivity. A formation mechanism for active [R,P-Pd-H]+BF,- compounds is suggested.

Rhodium(I1) Acetate Catalyzed Reactions of 2-Diazo- 1,3-Indandione and 2-Diazo- I-Indanone with Various Substrates M. J . ROSENFELD, B. K. RAVI SHANKAR and H.

Decomposition of 2-diazo-1,3-indandione (I) by Rh(I1) acetate (2) in cyclohexane and in benzene results in overall C-H insertion to give 2-substituted 1,3-indandiones. Anisole, (I) and (2) yield

benzenes substituted by single methyl or halogen groups yield the corresponding ortho- and para- substitution products. Spirocyclopropanes are obtained by Rh(I1)-catalysed additions of (I) to olefins; electron deficient olefins do not give adducts.

SHECHTER,J. h. Chem., 1988,53, (IZ) , 2699-2705

2-(4-methoxyphenyl)- I ,3-indandione (74%);


Oxygen Evolution by Means of Water Oxidation Catalyzed by Mononuclear Ruthenium-Ammine Complexes M . KANEKO, R. RAMARAJ and A. KIM, Bull. Chem. Soc. 3Pn., 1988, 61, (2), 417-421 Mononuclear Ru-ammine complexes, [Ru(NH j ) J Cl] ,+ and [Ru(NH I (H, O)] ’+, have been found to catalyse 0, evolution from H, 0 using (X(1V) as an oxidant, under homogeneous and heterogeneous conditions. The water oxidation process depends on the ionic strength of the medium. Higher acidic conditions gave higher 0, amounts. Heterogeneous catalysis using the Ru complex in Kaolin was as effective as homogeneous catalysis.

Competitive Cyclopropanation and Cross- Metathesis Reactions of Alkenes Catalys- ed by Diruthenium Tetrakis Carboxylates

R.-L. &QUEZ-SILVA and R. A. SANCHEZ-DELGADO, J. Chem. SOC., Chem. Commun., 1988, (12), 783-784 Observation of an efficient, competitive reaction pathway between carbene-transfer and alkene metathesis, promoted by a Ru-based system, is reported for the first time. The addition of ethyl diazoacetate to a mixture of styrene and norbornene containing a catalytic amount of Ru,(OAc), pfo- moted both the cyclopropanation and a selective cross-metathesis of the alkenes.

A. F. NOELS, A. DEMONCEAU, E. CARLIER, A. J. HUBERT,

FUEL CELLS Oxygen Reduction at Pt0.65Cro.3s, Pt,,, Cr,, and Roughened Platinum

Electrochem. Soc., 1988, 135, (6), 1431-1436 Oxygen reduced in o.5M H,SO, at the two named alloys and at the roughened surfaces produced by selective depletion of G has been investigated using conventional electrochemical techniques, and it is concluded that the increase in 0, reduction reaction current measured on roughened rotating disc electrode surfaces is due only to the increase in F’t surface area. Data presented demonstrate the benefit of increasing the surface area of these Pt electrodes.

Advances in Solid Polymer Electrolyte Fuel Cell Technology with Low Platinum Loading Electrodes

REDONDO, J. Power Sources, 1988, 22, (3 & 4), 359-375 The Gemini Space program showed the first major application of fuel cell systems. This paper presents methods to advance fuel cell technology by: (I) use of low Pt loading (0.35mglcm’) electrodes, (2) optimisation of anode/membrane/cathode interfaces by hot- pressing, (3) pressurisation of reactant gases (most important when air is used as cathodic reactant), and (4) adequate humidification of reactant gases.

M. T. PAFFETT, J. G. BEERY and S. GOTTESFELD, 3.

A. SRINIVASAN, E. A. TICIANELLI, C. R. DEROUIN and A.

Oxygen Electrodes for Rechargeable Alkaline Fuel Cells

(3 41, 399-408 Progress is reported on the investigation and development of electrocatalysts and supports to be used for the positive electrode of moderate temperature, single unit, rechargeable alkaline fuel cells. To date PbPdO,, CdPd, O,, Bi,PdO, , Pb~(Ir~-xPbx)07-y, Pb,(Ru,-,Pb,JO,-,, Na,Pt,O, and also Co tetramethoxyphenylporphyrin have been prepared and evaluated as electrocatalyst materials.

L. SWETTE and J . GINER, J. P m e r Sources, 1988, 22,

ELECTRICAL AND ELECTRONIC ENGINEERING Effects of Processing Conditions on the Characteristics of Platinum Silicide Schottky Barrier Diodes

HACKBARTH, s. B. BRoDSKY and M. R. POLCARI, Solid- State Electron., 1988, 31, ( s ) , 843-849 A study was performed of the effects of various processing conditions on the formation of PtSi Schottky barrier diodes. The interaction between PtSi and the contact metallurgy during subsequent annealing was also studied. The results show that oxide etching by wet etch is probably incomplete, leaving residues or suboxides on the surface of Si substrates which interfere with the subsequent PtSi formation.

Relations between Electrical Properties of RuOt Thick Film Resistors and Glass Viscosity 0. ABE, Y. TAKETA and M. HARAWME, Denki Kagaku, 1988, 56, ( I ) , 22-27 The relationship between the electrical and physical properties of thick fdm resistors was studied. The results showed that the electrical properties of the thick film resistors were affected by both the soften- ing point and the flow point of the glass. The resistance value varied inversely with the viscosity of the glass in the case of the resistor fired at the same temperature.

Application of Copper Conductor and Ruthenium Containing Oxide-Glass Resistor to High-Frequency Hybrid IC’s for a Portable Cellular Radio

KOBAYASHI, IEEE Trans. Components, Hybrids, Manuf. Technol., 1988, XI, (2), 211-217 The assessment of a Cu-conductor and a RuO , -glass resistor system and its performance in a high frequency circuit for a portable cellular radio is presented. The resistance of the Cu-compatible resistor increased after refiring at over 6oo°C and drastically increased as the firing temperature was raised. The results showed that the resistance change is caused by the diffusion of Ru to the Cu conductor.

D. MOY, S. BASAVAIAH, C. T. CHUANG, G. P . LI, E.

T. OGAWA, M. FUJII, T. ASAI, A. IKEGAMI and T.


NEW PATENTS

METALS AND ALLOYS Production of Platinum-Manganese- Antimony Thin Film

Production of a Heusler’s alloy thin fdm is achieved by arranging 3 targets of Pt, Mn and Sb to focus onto a quartz glass substrate, and performing magnetron sputtering. This is done simultaneously by ion bombardment to form an oriented Pt-Mn-Sb thin film.

Sulphurisation Resistant Silver Alloy Containing Platinum SEIKO EPSON K.K. Japanese Appl. 63114,830 A hard Ag alloy used for ornamental wares contains (by wt.) 80-93% Ag, 0.2-15% Pt, 1-5% Ge, and at least one of 0.2-15% Pd, 0.1-5% Ir, 0.2-15% In, 0.1-10% Zn and o.1-7% Sn. The Ag alloy has improved resistance to black discolouration on sulphurising by adding Pt , and improved hardness by precipitation of Ge due to age hardening.

MATSUSHITA ELEC. IND. K.K. Japanese Appl. 631452

CHEMICAL COMPOUNDS

Oxygen Evolving Anode for Use in Acidic Medium UNITED TECHNOLOGIES CORP. U. S. Patenr 4,707,229 An anode for electrolytic 0, generation in acidic medium has a ternary catalyst consisting of 5-25wt.% of a first platinum metal compound, 0.5-gowt.% of a valve metal compound, and the rest a second platinum group metal compound. The anode catalyst performs very well in harsh acidic environments and has good long life potential.

Electrodes for Electrochemical Cell DOW CHEMICAL CO. U.S. Patent 4,731,168 Porous electrodes for an electrochemical cell consist of particulate C bonded with a thermoplastic resin, and may contain a catalyst of Pt, Pd, Rh, and Ag. The electrodes are separated by a membrane or diaphragm, and are used in a cell for production of electric power by electrogenerative halogenation or oxidation of unsaturated hydrocarbons.

Electrode for Treatment of Waste Water KOBE STEEL K.K. Japanese Appl. 63/16,088 An electrode consists of Cu material covered with a Ti layer and then a Pt layer, both of controlled thickness, and both strongly bound. The electrode has improved conductivity and corrosion resistance, and is used for treatment of industrial waste water.

Conjugated Polymers Containing Palladium or Platinum NITTO KASEI K.K. Japanese Appl. 62/283,129 Conjugated polymers containing Sn and optionally other metals in the main chain are produced by reacting Pd or Pt compounds, such as ((C2H5),P),PdCl,, with Sn compounds, in the presence of Cu halides and basic solvents at O-ISO~C.

ELECTROCHEMISTRY Hydrogen Evolution Cathode JOHNSON MATTHEY P.L.C. European Appl. 256,673A A cathode suitable for H, evolution consists of a non- ferrous metal substrate, an electrocatalyst deposit containing Pt and Ru, and a depostit of Au and/or Ag at o . 1 - x i wt.% of the total of Pt and Ru metals. The cathode has enhanced poison resistance to Fe resulting from the presence of Au andlor Ag, and is especially used in a chloralkali cell.

Corrosion Resistant Electrolysis Electrodes

Insoluble Anode with Platinum Group Metal Coating TANAKA KIKINZOKU KOGYO

Japanese Appls. 63124,082-87 An insoluble anode consists of a Ti substrate, optionally coated with Mo, and coated by explosive spraying of a wire or plate material of Pt, or another platinum group metal, or an alloy of Pt with another platinum group metal. The coating can be formed quickly, and an anode with large surface area, low Cl, overvoltage, high 0, overvoltage, and high efficiency can be obtained, for use in the electrolysis industries.

Iridium Oxide Thin Film

An Ir oxide fdm is deposited on a cathode or anode surface by electrolysis of an alkaline aqueous solution containing an Ir compound, and having a pH of at least 8. The Ir oxide thin fdm can be electrolytically produced by a simple process.

HITACHI MAXELL Japanese APPl. 631339595

DAIKI ENG. K.K. European Appl. 261,920A Surface activated surface alloy electrodes have a substrate coated with up to I 50 p of an alloy containing 0.01-10 at.% ofone or more of Pt, Pd, Rh, Ir and Ru, 20-67 at.% of one or more of Ti, Zr, Nb and Ta, and Ni and/or Co. The electrodes have high corrosion resistance and activity, and are used for electrolysis of NaCl and H,SO, aqueous solutions.

Active Alloy Catalyst for Electrochemical Cells FUJI ELECTRIC W G . K.K. Japanese &’[. 63144,940 A catalyst for use in electrochemical cells consists of an alloy of Pt, a transition metal, preferably Fe, and a third component, preferably C. The alloy loaded Pt-Fe-C catalyst maintains high catalytic activity.


Anode for Electrochemical Peroxide Synthesis FAR E. UNIV. Russian Patent 1,333,717

An anode used in electrochemical synthesis of perox- ides is prepared more efficiently by coating the support with a catalyst containing (in wt.%) 20-41% Pt, 46-74% SnO,, and 4-13% Sb,O,. Using this method, Pt consumption is reduced two fold, selectivity of peroxide synthesis is increased by 30%, and energy consumption is reduced by up to 68%.

ELECTRODEPOSITION AND SURFACE COATINGS Tin-Palladium Catalyst for Electroless Deposition Processes MCGEAN-ROHCO INC. U. S. Patent 4,717,421

A solid Sn-Pd catalyst is prepared from a Pd halide, a Sn(I1) halide, an alkali metal halide, a Sn(I1) carboxylate and water. The method is used to manufacture a Sn-Pd catalyst used in electroless deposition processes. The product has superior activity to prior art catalysts and is non-toxic and easy to handle.

Palladium Chelate Plating Composition T. KOHAMA Japanese Appl. 621284,082

A non-electrolytic plating composition consists of a polymer compound of a Pd chelate and a solvent. The composition is applied to the surface of a base body, which is then non-electrolytically plated with metal. The body can be partially plated for better adhesion.

Palladium Activating Solution for Electroless Plating NEC CORP. Japanese Appls. 6314,072-73

A catalyst solution for electroless plating contains 0.1-1 gA PdCI,, HCI, SnCI,, a, a-dipyridyl and optionally NaCI. It is used for activating insulating materials such as plastics for preparation of electroless metal plating.

Electroless Paladium-Nickel Alloy Plating Liquid ISHIHARA YAKUHIN K.K. Japanese Appl. 63124,072

An electroless plating liquid contains 0.001 -0.5 molA of a Pd compound, 0.01-1 molA of a Ni compound, NH, and/or an amine compound, an organic compound including divalent S , and a hypophosphite and/or hydrogenated B compounds. The plating liquid has pH 5-11, and is used in the production of electronic components.

Palladium Activating Liquid for Electroless Plating SHINKO DENKI KOGYO Japanese Appl. 63145,378 An activating liquid contains more than I ppmA of a Pd ammonium complex in the form of [Pd(NH,),lz+ or IPd (NH,),I’+, and an alkali metal hydroxide. The liquid is used to activate a ceramic substance prior to electroless plating.

Amorphous Palladium Plating TONAN KINZOKU KOGYO Japanese Appl. 63/50,491

Amorphous Pd plating is effected from a Pd plating bath containing As, at 5 mA/cm’, at 50°C with a direct current, or at 25OC with a pulse current. An amorphous Pd plating layer having a smooth surface, good corrosion resistance and containing only a very small amount of absorbed H, can be produced rapidly.

APPARATUS AND TECHNIQUE Solid Electrolyte Gas Sensor ALLIED CORP. World Appl. 88/701A

An amperometric gas sensor consists of a Pt wire sensing electrode exposed to the ambient gas, and a reference electrode, both in electrical contact with a solid electrolyte matrix containing an alkali salt. The apparatus determines the concentration of gas consti- tuents in air, and uses a solid electrolyte operable over a wide range of environmental conditions.

Oxygen Sensor for Air:Fuel Ratio Control HONDA GIKEN KOGYO U.S. Patent 4,723,521

An 0 , sensor has a sensor body with two intercon- nected chambers and consists of ZrO, with R electrodes attached to each chamber wall. The sensor is located in the exhaust pipe, and the signals from it are fed to a microprocessor based management system, which determines and controls the air:fuel ratio at a predetermined value.

Dielectric Probe with Interdigitated Electrodes D.E. KRANBUEHL U. S. Patent 4,723,908

Two interdigitated chemically resistant electrodes of Pt, Pd, Au, Ti, W, Cr or a combination of these are used in a dielectric probe for sensing electrical properties. The probe is simple for contacting thin fims and coatings, and is used to monitor the dielectric properties of laminates and adhesives.

Ruthenium Alloy Probe for Liquid Helium Level Meter AISIN SEIKI K . K . Japanese Appl. 62/277,525 A superconductor wire of an amorphous alloy phase of Ru, Mo and P and/or B is used in the electrical resistance probe of a liquid He level meter for measuring the depth of liquid He in a vessel. The wire has excellent mechanical strength and gives decreased error due to temperature change.

Carbon Monoxide Detection Element SHIN COSMOS DENKI K. Japanese Appl. 63/3,247

A CO detection element consists of SnO, with at least one of Pt, Pd and Au in a total quantity of not more than o.o45wt.%. The element is steadily operated at not less than 25oOC. A purge circuit is unnecessary for this detecting element and cost can be reduced.


Working Electrode for Anion Analysis

A conductor of Pt, Pd, Rh, Ir, Ru, Au, Ag, a C material, or conductive glass is coated with a polydivinyl ferrocene thin film and used as a working electrode for potential scanning in aqueous electrolyte. The resulting current-potential curve is used to detect and analyse various anions in solution.

Hydrogen Gas Sensor Element

A H, gas sensor element is made by coating a spiral heat-sensitive resistor wire of Pt with y-Al,O,, impregnating with Pt, and treating with Si vapour at 200-400~C. The sensor element has good selective sensitivity for H, gas for long periods, and is used to detect H, in the air in fuel cell power generating plants and H, engines.

Oxide Semiconductor Type Oxygen Sensor

An 0, sensor device consists of an oxide semiconductor covering 2 electrodes at predetermined intervals, with a Pt or Pt/Rh catalyst around the electrodes. Positioning the catalyst in this way gives superior response while reducing the amount of catalyst used. The 0, sensor is used to detect 0, concentration in car exhaust gas by a change in resistance.

Dissolved Oxygen Sensor JGC CORP. Japanese Appl. 63158,148 An 0, sensor includes an inner tube having a Pt cathode plate with a curved lower surface, a Pb anode, and an outer tube with an 0, transmitting partitioning fdm. The measured current flow resulting from dissolved oxygen in the test liquid is stabilised even when heat pasteurisation is repeated, and a dissolved 0, sensor of high strength can be obtained.

Internal Structure for Tubes to Withstand Pressure Shocks W. SCHUBERT Gennan Appl. 3,622,445 The internal structure of pressure-shock insensitive tubes or vessels comprises a mattress-shaped lining with radial springs, and a sheet metal covering such as Pt, axially disposed on the inner surface. The ar- rangement can be replaced simply, and is used for industrial purposes and for nuclear reactor plants.

Determination of Specific Surface Area of Platinum MOSCOW LOMONOSOV UNIV. Russian Patent 1,332,195 The specific surface area of Pt dispersed on C substrates is determined by using the sample as one electrode in a three-electrode cell. An adsorbing substance is introduced, and the anode potential curve is noted and compared to that of a sample without adsorbed ions so that the number of adsorbed ions, and thus the specific surface, can be found.

AGENCY OF IND. SCI. TECH. Japanese Appl. 63115,152

FUJI ELECTRIC MFG. K.K. Japanese Appl. 63130,751

TOYOTA JIWSHA K.K. Japanese Appl. 63152,049

Specific Surface Measurements of Supported Metal M.P. ALEKSEEVA Russian Patent 1,334,076 The specific surface of Pt, Rh, Ir or Ru on an Al oxide surface can be determined by impregnating the sample with H, , and then measuring the amount of H, gas desorbed. The method is more accurate; the relative error being reduced 1.5-5 times.

JOINING Improved Bonding of Metal Layers to Synthetic Surfaces BAYER A.G. European Appl. 255,012A Improved bonding of Pd, Au, Ag, Ni, Co, Fe andlor Cu metal layers deposited without current on synthetic surfaces, is obtained by treating the surface with a non-etching activator composition containing a copolymer as binder. The composition is used as a printing paste in production of printed circuits.

Palladium-Silver Solder G. ROTZER U.S. Patent 4,718,593 Asolder consistingof 11-89wt .% Pd and 11-89wt.Yo Ag is used to bond a metal electrode to a rough cut and unmodified semiconductor surface. Using this method a permanent bond is achieved without the need for semiconductor surface pretreatment.

Palladium Alloy for Joining Ceramics GTE PRODUCTS CORP. U.S. Patent 4 ,719 ,081

An alloy for joining ceramics consists of 65-98% Pd, I-20% Ni, 0 .5 -20% Cr, o.5-10% Ti or Zr, and 0-10% Mo, (all wt.%). The alloy is preferably in the form of a foil, and is used for brazing ceramic components such as SIC. The Pd provides an oxidation resistant ductile bond, and the Ti and Zr allow wetting of the ceramic surfaces.

HETEROGENEOUS CATALYSIS Isomerisation Catalyst Containing Platinum andlor Palladium

Isomerisation of normal paraffin to isoparaffm uses a catalyst of o . ~ - ~ w t . % Pt andlor Pd deposited on a zeolite/combined ZrlAl, 0 mixture, at 220-280OC and a total pressure of 2-40 bars. The activity and selectivity of the catalyst are improved by the presence of Zr.

Ruthenium Promoted Hydrogenation/ Dehydrogenation Catalyst BEROL KEMI A.B. European Appl. 254,335A A catalyst consists of 4-40wt.Yo Ni andlor Co, 0. ~ - g w t . % Ru as promoter, and a halide compound, on a porous oxide support of at least 5owt.% activated Al,O, and/or SO, . The catalyst is used in hydrogenation and/or dehydrogenation reactions.

CIE RAFFINAGE DISTR. European Appl. 253,743A


Dehalogenation Catalyst CHIYODA CHEM. ENG. co. European Appl. 255,877A Dehalogenation of a halide involves catalytic hydrogenation of the halide at 200--1100~C, in the presence of a catalyst containing at least one platinum group metal and/or its silicide on a corrosion resistant ceramic or graphite support. The catalyst gives long life for dehalogenation of tetra- or trichlorosilane, but can also be used for other chlorides.

Combustion Catalyst for Hot Water Boiler U. VIANI European Appl. 256,322A A boiler with catalytic combustion of CH, for domestic H 2 0 heating has a container with layers of a combustion catalyst consisting of a platinum group metal supported on a granular solid. Use of low noble metal content catalysts ensures complete CH, combustion at low temperatures.

Platinum or Palladium Isomerisation Catalyst INST. FRANCAIS DE PETROLE European Appl. 256,945A An isomerisation catalyst preferably contains 0.05-1wt.% Pt or Pd, or o.r-~owt.% Ni supported on a mordenite in the acid form, and is subjected to an oxychlorination process to increase the metal dispersion and activity. The catalyst is used for hydroisomerisation of a fraction rich in 4-7C n- paraffms, to give a high octane gasoline component.

Decarbonylation Catalysts for Furan Preparation BASF A.G. European Appl. 261,603A Furan is prepared by gas phase decarbonylation of furfural at 250-4OOoc, in the presence of H, and a supported catalyst containing o . ~ - ~ o w t . % Pt andlor Rh, and o . ~ - ~ o w t . % of an alkali metal oxide, preferably Na, K andlor Cs. The catalysts give improved productivity and have a longer useful working life than prior art catalysts.

Zinc-Chromium-Palladium Catalyst for Pyrazine Preparation BRACCO IND. CHIM S.p.A. World Appl. 881189A A pyrazine compound is prepared by reacting a liamine with a diol in the presence of a new catalyst .ontaining Zn oxide, Zn chromate and o.g-swt.% PdSO,. The catalyst has an improved lifetime, and pyrazines are obtained in high yield with good selectivity. The products are used as essences, perfumes, flavours and intermediates.

Precious Metal Catalyst with Defined Metal Dispersion DOW CHEMICAL CO. U.S. Patent 4,713,363 A catalyst consists of 0 .45-1 .0 mmollg of Pt, Pd, Ir, Os, or Ru crystallites with a dispersion of 50-90%, on a metal oxide substrate with specified surface area and volume. The catalyst combines high metal loading with high dispersion, and can be used in hydrogenation processes or in the production of methyl methacrylate from 2-chloropropane.

Low Pressure Naphtha Reforming Catalyst EXXON RES. & ENG. co. U.S. Patent 4,719,005 A catalyst consisting of 0.1-1.2% Pt, 0.1-1.2% Re and 0.15-1.2% Ir (all wt.%) on an Al,O, support is used to improve octane quality of a naphtha by reforming at ultra-low pressure and ultra-low H, rate. The conditions used give acceptable catalyst activity, yield stability and an optimised yield of hydrocarbons.

Palladium Catalyst for Conversion of Propylene to Ally1 Acetate SUN REFINING & MARK. U.S. Paient 4,732,883 A supported Pd catalyst is contacted with a 3-6C olefin in acetic acid at 55-15oOC, 1 -10 atm, and in the absence of 0,, to prepare an activated Pd catalyst. This catalyst is especially useful in the one- step oxidation of propylene to ally1 acetate, giving high yield and selectivity under mild conditions.

Three-Way Automobile Exhaust Catalyst NISSAN MOTOR K.K. Japanese Appl. 621266 ,142

One or more of Pt, Pd and Rh is supported on a mixture of activated A12 0, supporting rare earth metal, and rare earth metal oxide, which is then made into a slurry with Al,O, sol, and coated onto a support. The catalyst produced is useful for simultaneous removal of HC, CO and NOx from automobile exhaust, and shows improved resistance to sintering of the catalytic metal.

Catalyst for Purification of o-Methy lacetophene TORAY IND. INC. Japanese Appl. 621277,338 A process of catalytic hydrogenation and distillation is used to purify crude o-methylacetophene, prepared from o-toluic acid and acetic acid or acetone. The hydrogenation catalyst is Pt, Pd, Rh, Ru and Ni, and is used at 1-20wt.% of the crude material. High purity o-methylacetophene is obtained.

Preparation of Dialkylaminophenols SUMITOMO CHEM. IND. K.K.Japanese Appl. 621292,747 Polymer Catalyst with Trapped Precious A Pt and/or Pd catalyst supported on activated charcoal is used in the preparation of an N,N-dialkyl- Metals

CATALYTICA ASSOC. world Appl. 8 8 / I , 2 0 0 A substituted aminonheno1 from a mono- A catalyst is prepared by intercalation of Pt, Pd, Rh, Ir, Ru or mixtures between the layers of a layered crystalline material containing P, and crosslinking the layers by reaction with a hydroxy metal complex.

alkylaminophenol, aliehyde(s) and H, . The product is prepared with high selectivity, and is an important intermediate of dyestuffs for heat-sensitive, pressure- sensitive paper and fluorescent dye.


Catalyst for Hydrocarbon Fuel Gas Production

A catalyst consists of platinum group metals, Fe andlor Co, and Mn oxides, on an AI,O, andlor SiO, support. An example catalyst has the composition 0.35% Ru, 0.9% Mn,O, and 5% Coon AI,O,. The catalyst is used to produce a high calorie 1-4c hydrocarbon fuel gas from a mixed gas containing H, and CO or CO, . Methanol Decomposition Catalyst

A methanol decomposition catalyst has a SiO, support with o.g-5wt.% of at least one of A, Pd and Rh, and at least one of Mo and La with an atomic ratio of 0 . 0 1 : 0 . 5 against Pt, Pd and Rh. The catalyst has high activity, improved selectivity, and shows high quality in the methanol decomposition reaction, leading to an improved methanol utilisation coefficient.

Combustion Catalyst for Natural Gas

A combustion catalyst having lo-IoogA of a platinum group element and a refractory metal oxide on a monolithic support, is used for catalytic combustion of natural gas containing methane and lower hydrocarbons, to obtain a clean gas practically free from toxic components. The clean combustion gas is useful as a primary energy source for turbines.

Palladium Catalyst for Nitrous Oxide Removal EBARA SOGO KENKYUSH Japanese Appl. 6317,826 N , 0 in a mixed gas is decomposed and removed by contact at 250-600°C with a supported catalyst containing one or more of the metals Pd, Ni, Fe, Co and Cu, or their oxides. The catalyst can be used to remove N,O in an effluent gas from a denitration apparatus (used for waste gas from a heavy oil combustion furnace).

Methanol Reforming Catalyst

KANSAI NETSUKAGAKU Japanese Appl. 621294,442

MITSUBISHI GAS CHEM. K.K. Japanese Appl. 6314,849

NIPPON SHOKUBAI KAGAKU Japanese Appl. 6314,852

MITSUBISHI HEAVY IND. K . K . Japanese App6. 6317,842-43

A CH,OH reforming catalyst consists of Rh and Pt or Pd loaded on a rutile-type TiO, support, or an AI,O, support coated with alkaline earth metal oxides. The catalyst is used to convert CH,OH into H, and CO, has higher activity at lower temperatures and an extended operating life.

Alcohol Combustion Engine Exhaust Purification Catalyst NIPPON SHOKUBAI KAGAKU Japanese Appl. 6317,845 A catalyst for purifying the exhaust of an alcohol combustion engine at lower temperatures consists of uniformly dispersed Pt particles (100-500I\) on a porous inorganic oxide. The catalyst may also contain Pd and Rh, and is used to decompose unreacted alcohol, CO, hydrocarbon or aldehyde in the exhaust.

Automobile Exhaust Catalyst with Controlled Metal Placement TOYOTA JIDOSHA K.K. Japanese Appl. 6317,847 A monolithic catalyst for automobile exhaust purification is prepared in such a way that the peripheral cells are clogged, and much more Pt and Rh are loaded onto the central part. Loading of the catalyst materials on the clogged parts can be prevented, so that the catalyst has higher activity, and reduced poisoning and degradation.

Aromatic Hydrocarbon Preparation SHOWA SHELL SEKIW Japanese Appl. 6318,342 An aromatic hydrocarbon is prepared by contacting a lower saturated hydrocarbon having 5 or less C atoms with a Zn silicate catalyst containing 0.25-1.5wt.% Pt, at 3oo-70o0C. The catalyst can be regenerated by burning in an 0, containing atmosphere and enables an aromatic hydrocarbon to be formed by using a cheap catalyst efficiently.

Ozone Decomposition Catalyst NIPPON SHOKUBAI KAGAKU Japanese Appl. 63112,347 A catalyst contains 0.2-5gfl of at least one element of Pt, Pd or Rh, 1-20 gA Ce oxide, and activated AIIO, supported on a refractory three-dimensional structure. The catalyst is used for decomposing 0 , gas to 0,, and has high activity at low temperature, and good durability.

Exhaust Catalyst with Improved Resistance to Lead Poisoning NIPPON MOLYBDENUM ~ ~ J a p a n e s e Appl. 63/20,028 A catalyst for cleaning automobile exhaust gas consists of a monolithic carrier or cordierite substrate, coated with alternate layers of activated AI,O, containing Pt, Rh andlor Pd, and activated AI,O,. The catalyst has improved lead poisoning resistance since poisons are trapped in the activated AI,O, layer.

Platinum Group Metal Catalyst for High Calorie Gas Preparation KANSAI NETSU KAGAKU Japanese Appl. 63123,742 A catalyst for preparing high calorie gas consists of a platinum group metal, 15-zswt.~/0 of Fe andlor Co, and MnO on a SiO, and/or AI,O, support. The catalyst has good heat resistance and long life, and enables high calorie gas containing 2-4C hydrocarbons to be obtained easily from low calorie gas such as coke oven gas.

Catalyst Coating for Improved Combustion Efficiency TANAKA KIKINZOKU KOGYO

Japanese Appls. 63/32,118--19 A platinum group metal or oxide catalyst is coated on the outer surface of movable parts and on the inner surface of fmed parts which contact the gases in the combustion chamber of an internal combustion engine. A coating with good activity and durability is obtained with good fuel gas combustion rate.

Platinum Metals Rev. , 1988, 32, (4) 22 1

Ethylene Preparation from Synthetic Gas

Ethylene is prepared from synthetic gas using a Rh- Ti-Fe-IrlSiO, catalyst on the upper plate of the reaction tube and an alcohol dehydrating catalyst on the lower plate, or using a mixture of the two. Reaction is carried out at roo-450°C, with H,:CO ratio of 10: I-I:IO. Using these catalysts ethylene can be synthesised selectively, in one step, and efficiently.

Filter for Diesel Exhaust Particulates TOYOTA JIDOSHA K.K. Japanese Appl. 63151,947 A honeycomb fdter is made of a 3-dimensional refractory structure, coated with an inorganic oxide, then plated with a conductive Cu or Ag layer, and plated with a Pt, Pd or Rh catalyst layer. The fdter has improved collection efficiency of exhaust particulates.

Combustion Exhaust Purification Catalyst TOYOTA JIDOSm K.K. Japanese Appl. 63154,940 A combustion exhaust purification catalyst consists of a supported Rh containing perovskite type double oxide, preferably Ba, -,Sr,RhO,, with a reversible phase transition point of 7oo-90o0C. The catalyst has improved durability as RhIAl , 0, solid solution formation is prevented, and higher activity at lower temperatures since Rh , 0, is deposited and Rh can be highly dispersed.

Efficient Particulate Capturing Catalytic Filters CATALER KOGYO K.K. Japanese Appls. 63165,926-27 Particulate capturing catalytic filters with high eff- ciency consists of a honeycomb body coated with Al,O, containing a rare earth metal oxide, carrying a platinum group metal at the gas inlet side, and having selected areas Cu plated, or upstream and downstream fdter units coated with Al,O,, carrying a platinum group metal and Cu, respectively.

Palladium Catalysts for Preparation of Dialkyl Oxalates

AGENCY OF IND. SCI. TECH. Japanese Appl. 63133,342

V.E.B. LEUNA-WERK ULBRICHT East German Patents 249,260-62

Dialkyl oxalates are prepared by reaction of CO with a nitrite ester at 323-473K and 0.1-1 MPa, in the presence of a catalyst containing 0.1-5wt.% Pd, and optionally Cu, on an Al,O, support which may be modified with other compounds. The catalysts have good stability and give high space-time yields.

HOMOGENEOUS CATALYSIS Palladium Catalyst for Aromatic Acid Preparation RHONE POULENC CHIMI. European Appl. 255,794A An aromatic acid is prepared by contacting an aromatic halide in an organic solvent with CO, H,O, a Pd-based catalyst, an organic base, and a Pd complexing agent, but without a transfer agent.

Phenol Oxidation Catalyst AIR LIQUIDE L. European Appl. 262,054A A salt or complex of Pd, Co or Cu is used as a catalyst for oxidation of phenols in industrial wastes, especially water containing chloro- or poly- chlorophenols. Oxidation is effected in an aqueous medium containing alkaline carbonate, at 80-200°C, and 0, pressure of 0.1-2 MPa, using up to 5% metal based on the wt. of phenol.

Polymer-Bound Catalysts with Improved Lifetime JOHNSON MAITHEY P.L.C. U.S. Patent 4,727,050 A multi-purpose catalyst consists of a platinum group metal carboxylate, especially Rh acetate, bound to the carboxylate groups of a polymer containing no other reactive groups. Such catalysts retain the activity of the unbound platinum group metal carboxylate, and have longer effective lifetimes. They are useful for various reactions such as cyclopropanation, hydroformylation and others.

Rhodium Based Catalyst for Alcohol Homologation UNION CARBIDE CORP. U.S. Patent 4,727,200 A catalyst system containing Rh, Ru, I, and a bis(diorganophospino)alkane is used for the reaction of an alcohol with synthesis gas to produce the next higher homologue alcohol. The reaction occurs at 50-z50°C, and ~oo-~oooo psig, and is used to produce ethanol and its precursors from methanol.

Chloropropionaldehyde Preparation Using Rhodium Catalyst

Preparation of 2-chloropropionaldehyde from vinyl chloride, CO and H, uses a catalyst of Rh compounds with at least one kind of styrene polymer containing phosphine groups. The product is obtained in high yield and selectivity, using mild conditions.

Ruthenium Catalyst System for Ethanol Preparation

Ethanol is prepared from formaldehyde, CO and H, by reaction in the presence of a catalyst system containing Co and Ru (at 0.01-0.1 compared to the molar number of formaldehyde) and a tertiary phosphine. The method uses no petroleum.

Selective Ethanol Preparation Using Ruthenium Catalysts

MITSUI TOATSU CHEM. INC.JapaneSe Appl. 621277,335

KAWASAKI STEEL K.K. Japanese Appl. 621298,543

AGENCY OF IND. SCI. TECH. Japanese Appls. 63148,236-37

Ethanol is prepared selectively from the reaction of CO and H, at high temperature and pressure in a liquid medium containing either Ru and halogen compounds, or an organic phosphine oxide solution containing Ru compounds, Co compounds, and alkali metal compounds and halides.


Palladium Catalysts for Acetylene Carbo-Alkoxylation W A N KIROV. CHEM. mcm.Russian Patent 1,315,457 New Pd catalysts are obtained by treatment of a carbonyl-chloride complex Pd dimer with glacial CH,COOH and triphenyl phosphine or triphenyl arsine. The proposed catalysts are used for acetylene carbo-alkoxylation, having higher selectivity than known catalysts, and have high selectivity for butyl acrylate production.

FUEL CELLS Secondary Fuel Cell with Novel Positive Electrodes RCA CORP. U. S. Patent 4,721,660 A secondary fuel cell has positive electrodes consisting of Ag-In alloys having 50-55wt.% Ag and 50-45wt.Oh In, and negative electrodes comprising a mixture of Pd and Ru. The fuel cell charges to higher voltage at lower pressure, has lower internal resistance, and is lighter than conventional electrically regenerable fuel cells.

Platinum Alloy Catalyst for a Fuel Cell FUJI ELECTRIC MFG. K.K. Japanese Appl. 63112,349 A platinum alloy catalyst for a fuel cell is produced by applying a Pt catalyst to a support, then a metal compound such as Fe hydroxide, and heat treating in reducing and inert atmospheres to form the alloy. The Pt can be perfectly alloyed and well dispersed, giving a catalyst with good durability, high activity, and strong resistance to catalyst poison.

Platinum-Ruthenium Anode Catalysts FUJI ELECTRIC MFG. K.K.

Japanese Appls. 63148,760-61 Preparation of anode catalysts for phosphoric acid fuel cells involves gradual reduction of an aqueous dispersion containing Pt, Ru and a catalyst substrate, after making alkaline, heating, and adding an anti- colloid agent. The dispersion of the Ru and its degree of contact with the catalyst substrate are good.

CHEMICAL TECHNOLOGY Production of Fine Precious Metal Particles TANAKA KIKINZOKU KOGYO

Japanese Appls. 621294,114-25 Fine particles of Pt, Pd, Rh, Ir, 0s or Ru (M) with a narrow particle size distribution are prepared by reducing an aqueous solution of H,MCI,. Using a reaction temperature of 30-1 5ooC and a reducing gas at partial pressure of 0.5-30 kglcm’ , spheroidal and well dispersed metal particles are obtained. However, with a temperature of 150-25o~C and pressure of 0.1-12 kglcm’, well dispersed and crystalline metal particles are obtained.

GLASS TECHNOLOGY Heat Resistant Platinum Alloy TANAKA KIKINZOKU KOGYO Japanese Appl. 63120,426 A platinum alloy containing Gd has excellent heat resistance, and is fused for crucibles for glass melting or high temperature sensors.

Glass Fibre Production Treatment Agent

A treatment agent used in glass fibre production contains a diorganopolysiloxane, an organohydro- dienepolysiloxane, and a catalytic amount of a Pt compound. The agent is useful for treating glass- sleeve, -cloth or -tape.

SHINETSU CHEM. IND. K.K. Japanese Appl. 63128,983

ELECTRICAL AND ELECTRONIC ENGINEERING Preparation of Flexible Printed Circuit Material BAYER A.G. Eumpean Appl. 259,754A Organic compounds of Pt, Pd, Rh, Au, andlor Ag are used as activators in the preparation of flexible circuits consisting of a conductive pattern deposited on a flexible substrate, such as a metal foil. Thin < I O ~ or very thin 0.3-5 p metal layers can be deposited by electroplating using this method.

Dielectric Composition for Multilayer Capacitors

Electrodes of 70wt.% Pd:30wt.% Ag alloy are used with a dielectric composition containing Nd titanate, Pb titanate, Ba titanate, Ba zirconate and Y oxide. The composition has a sintering temperature of 1280-1300~C, a dielectric constant of 75-85 at I MHz frequency, and is used for multilayer ceramic capacitors.

Gold-Palladium Wire Used in Forming Strong Contacts

A contact portion is formed on a metal pad by bonding to a ball on one end of a Au-Pd wire, consisting of 97_99wt.% Au and 1-3wt.% Pd. The method is especially used in forming contacts to MOS semiconductor devices.

Platinum Cap Member Used in Spark Plug Manufacture ALLIED CORP. U.S. Patent 4,725,254 Manufacture of the centre electrode for a spark plug involves passing current through a cup-shaped Pt cap member and an extruded cylindrical inconel body, until the inconel adjacent to the junction reaches melting point. A compressive force causes the Pt cap member to fuse uniformly to the tip of the extruded centre wire, which completes the electrode.

LCC-CICE CIE EURO coMPos .Eumpean Appl. 262,041A

AMERICAN TEL. & TELEG. CO. U.S. Patent 4,717,066

Platinum Metals Rev., 1?88, 32, (4) 223

Iridium Oxide Anode Colour Layer for Electrochromic Device CANON K.K. Japanese Appl. 621262,726 An Ir oxide layer for a solid electrochromic device is produced by reactive sputtering in the presence of H,, 0, and Ar using a decentered substrate and sample holder. An oxide film of non-uniform density with increased surface area and moisture content is formed, which improves the co1ouring:discolouring ratio, and the response speed of the electrochromic device.

Ferromagnetic Thin Film for Magnetic Head Core HITACHI K.K. Japanese Appl. 621279,609 A ferromagnetic thin film consists of an Fe-Mo alloy containing 0.9-5.8wt.Yo Mo, optionally 2wt.O/0 or less of at least one of Pt, Pd, Rh, Ir, Os, Ru, Ag and Au, and balance Fe. The thin film has a low magnetostriction constant, high saturation magnetic flux density, and high magnetic permeability, and is used as a magnetic head core material in magnetic disk devices and VTR’s.

Magnetic Recording Medium with Protective Film SEIKO EPSON K.K. Japanese Appl. 621289,912 A magnetic recording medium with superior mechanical reliability and durability consists of a Co alloy magnetic layer on a treated base, with a Pd-Ni or Pd protective film, and a Rh film. The Pd-Ni and Rh films have a total thickness of 100-1000d and protect the magnetic layer, which does not change even under high humidity.

Electrode Structure for Electric Cell ISHIKAWAJIM-HARIMA JUKO

Japanese Appl. 62/2go,8go An electrode structure for an electric cell is made so that the conventional troublesome brazing is replaced by a simplified setting. The structure includes a Pt electrode ring prepared in the underside flat face of a bolt head made of an insulator, with wiring con- nected to the electrode ring buried in the bolt stem.

Optical Recording Medium with Tellurium and Palladium MATSUSHITA ELEC. IND. K.K.

Japanese Appls. 63123,235 and 63123,242 An optical information recording medium has first and second layers sputtered onto a substrate from composite or alloy targets of Te and Pd. High reflec- tivity, high sensitivity, and high weather resistance are obtained. The recording carrier is for a disc type information recording medium, used for an optical recording regenerating system.

Permanent Magnet Alloy with Improved Resistance NIPPON GAKKI SEIZO K.K. Japanese Appl. 63145,349 A permanent magnet alloy contains Fe, a small amount of platinum group element(s), B, and Y andlor rare earth element(s). The alloy has improved resistance against oxidation and corrosion, and is used for high performance electrical apparatus.

Rerecordable Optical Recording Medium

An optical recording medium which is rerecordable has a substrate supporting a thin layer containing Pd, Sn, Pb and 0,. With this medium, erasing can be carried out using a low laser power, and ageing deterioration at high temperature is prevented.

Electrically Conductive Titanium Oxide Crystal

The surface of a Ti oxide crystal is divided into two areas, only one of which supports a catalyst including at least one of Pt, Pd, Rh and Ir. Each area is treated at 300-6woC in an oxidising or reducing gas atmosphere. A Ti oxide crystal having a specific area which is electrically conductive, and an area of low electrical conductivity, is obtained.

Durable Conductive Polymer Electronic Element

An electronic element has a first electrode of Pt,

VICTOR CO. OF JAPAN Japanese Appl. 63146,635

TOYOTA CENT. RES. & DEV.JapaneSe Appl. 63148,703

OMRON TATEISI ELTRN. K.K.JapaneSe Appl. 63161,284

SnO, and a second Pt thin fdm electrode, both with a surface covering of a conductive polymer layer of polyaniline. The element is used for a battery or

Magnetic Optical Material MATSUSHITA ELEC. IM). K.K.JaPaneseAPPl. 63111,659 A magnetic optical material has an orientated film of hisplayer, and has excellent durability because Heusler’s alloy with good magnetic optical effect. elution of the second electrode into the electrolyte is The material has at least Pt, Mn or Sb formed on a prevented by a sealing member. single crystal substrate with crystal structure of the NaCl or corundum tvpe. Palladium Activation for Metal Plating _ _ -

Ceramics Electroconductive Paste Containing SCHERING A.G. German Appl. 3,632,513

Metal plating ceramic materials involves pretreat- Palladium MITSUBISHI METAL K.K. Japanese APPl. 63113,303 ment with gaseous B halides in a glow discharge zone, An electroconductive paste consists of fme particles immersion in aqueous solution, activation in Pd- of magnetite coated with 30-70wt.% of a Ag-Pd alloy containing solutions, and chemical deposition of containing 2wt.Yo or more of Pd. The electroconduc- metal such as Cu or Ni. High grade, accurate printed tive paste has improved oxidation resistivity at high circuit boards for electronics can be produced on temperature, and is easy to manufacture. ceramics, with good adhesive strength.


Palladium Powder for the Microelectronics Industry FUNK E.J. & SONS INC. East German Patent 251,249 Pd powder with a specific surface area is prepared by precipitating from acid Pd chloride solution using 2-10 mol% of NH,OH and 0.5-5 mol% of a N,H, solution. The Pd powder is used to produce filter pressure paste and metallisation products.

TEMPERATURE MEASUREMENT Temperature Measuring Probe SCHWELM ANLAGEN German Appl. 3,639,408 A temperature measuring probe includes a Pt wire wound on a non-conductng carrier plate; both of which are embedded in an enamel layer. The probe is simple to produce, efficient, and reliable, and is used for chemical apparatus.

MEDICAL USES Lipophilic Platinum Complexes as Anti-Cancer Agents EFAMOL LTD. European Appl. 257,939A New complexes with anti-cancer effects consist of derivatives of platinum group metals, preferably Pt, with lipophilic residues, which aid transport of the metal across body cell membranes. The complexes are more lipophilic than cisplatin, and therefore show anti-cancer effects at lower dosages, resulting in less side effects.

New Riboflavin Diamine Platinum Anti-Cancer Agent Y. KIDANI European Appl. 261,044A A new riboflavin diamine Pt complex is prepared from the reaction of the riboflavin or its nucleotide with the dinitrato Pt (11) diamine complex. The complex is used for anti-cancer and anti-leukemia agents.

New Platinum Anti-Tumour Agents ASTA PHARM. A.G. European Appl. 262,498A New Pt indole-diamine complexes are useful as anti- tumour agents with a high binding affinity for oestrogen receptors. They are especially useful for treating mammary carcinomas; in an example a dose of 20 mgkg gave 77-89% inhibition of MXT carcinoma in mice after 6 weeks.

Iridium Oxide Coated Electrodes EIC LABORATORIES INC. U.S. Patent 4,717,581 Ir oxide coated electrodes for a neural stimulator are made by immersing a metal electrode in a solution containing a chloroiridate-alcohol complex, drying, and annealing. The Ir oxide layer permits charge densities of up to 10 mC/cmz for cathodic or anodic polarities without water electrolysis.

Generation of Iridium-191 for Use in Angiography CHILDREN'S MED. CENT. u. s. Patent 4,729,380 Apparatus for generating Ir-191 m includes a generator column having a resin loaded with a mixed solution of K,(OsO,.(OH),CI,) and K,(OsO,CI,). The Ir-191 m is used in first pass angiography to detect cardiac defects in patients. The angiography can be performed with minimal interfering background radiation, and minimal exposure to toxic 0s.

Deposition of Iodine-125 on a Substrate for Medical Use MIDI-PHYSICS INC. U. S. Patent 4,729,903 Substrates such as charcoal impregnated with Pt, graphite ribbon impregnated with Ag, and Ag wire are contacted with Xe-125 gas, which decays to deposit at least I microcurie of 1-125 gas as a solid on the surface. The substrate can then be used in bone densitometers and diagnostic devices such as portable units for taking X-rays or for use in radiation therapy.

Low Toxicity Platinum Anti-Tumour Agents BRISTOL MYERS CO. U.S. Patent 4,739,087 Dichloro Pt complexes are treated with the Ag (11) salt of a desired ligand, such as 2-sulphobenzoate or 3-ketoglutarate, to prepare new 1,2-diaminocyclohexane F't (11) compounds. The compounds are anti-tumour agents with improved solubility, stability, and activity against experimental murine malignancies, and have minimal toxicity.

Thermal Tip Catheter with Palladium Catalyst U.S. DEFT. HEALTH & HUMAN

U.S. Patent Appl. 071026,540 A thermal tip catheter consists of a catheter body with a catalytic thermal tip at its working end. A catalyst such as Pd sponge is located within the chamber formed between the metallic tip and the end of the inner tubing, with a thermocouple positioned here also to monitor the tip temperature. The catheter is used as a surgical device for antioplasty.

New Platinum Complexes for Use as Anti-Cancer Agents CHUGAI PHARMACEUTICAL K.K.

Japanese Appls. 621298,596 and 63/10,724-26 New complexes containing Pt and 1-(2-aminoethyl) pyrrolidine or 2-aminomethylpyrrolidine are used as anti-cancer agents. The products have higher anti- tumour activity than cisplatin and carboplatin, and combine with plasma protein more weakly than cis- platin. In animal tests they are effective against colon 26 carcinoma and some leukemias.

The New Patents abstracts have been prepared from material published by Derwent Publications Limited.


AUTHOR INDEX TO VOLUME 32 Page

Abdel-Hamid. S. M. 39 Abe, 0. 216 Abon, M. 91 Aboul-Gheit, A. K. 39 Adrian, H. 60 Aeppli, G. 60 Aizawa, M. 95 Akexandrowa, M. 36 Al Khowaiter, S. H. 38 Alexandrova, I. L. 40 Alnot, M. 31 Altman, E. 1. I49 Al-Ashab, S. T. 148 Amedelli, R. 153 Ammar, E. 38 Anders. K. 154. 213 Andoh,’ Y. Andreev, V. N. Andrews, J. W. Applehy, A. J. Aragane, J. Arai, H. Arai, Y. Arakawa, H. Aramata, A. Ardell, A. J. Armgarth, M. Asai, T. Asami, K. Asayama, K. Asriev, S. D. Assafi, M. Auffermann, G. Augustine, S. M. Ayala, N. P. Ayers, W. M. Ayres, D. C.

92 210 72 41

159 I99 40 40

21 1 210 213 216 35 32

I57 I55 I50 38

152 187 I86

Baba, K. 151, 210 Badwal, S. P. S. 153 Bagnoli, P. E. 41 Bagotzky, V. S. 129 Baidurskii, V. L. 40 Baiker, A. 40 Balch, A. L. 92 Baltruschat, H. 21 I Banhart, J. 209 Baranowski, B. 22 Barbi, G. B. 211 Bardina, I. A. 93 Barteau, M. A. 148 Barton, J. K. 34.100.153 Basavaiah, S. 216 Bashilov, V. V. 33 Basile, L. A. 100 Battaglin, C. 153 Baumann, S. M. 96 Baumgartner, M. E. 188 Beery, J. G. 216 Beletskaya, I. P. 157 Belikov, V. M. 215 Bell, A. T. 215 Beltramini, J. 38

Page Berlowitz, P. J. 149 Bernal, S. 40 Bernik, S. 209 Berning, G. L. P. 209 Bertolini, J. C. 91 Beyer, W. 91 Bianchi, M. 158 Birss, V. 1. 152 Blair, D. S. I49 Blake, A. J. I50 Bloembergen, P. 72 Bockris, J. O’M. 152 Boone, D. H. 94, 95 Borisov, A. V. 157 Borje, A. I50 Boshin, R. 36 Botana, F. J. 40 Bdttinger, J. 32

Bour, J. J. 150 Boucher, B. 209

Boyd, D. C. 35 Bradley, P. 94 Bragin, 0. V. 96 Bretscher, H. 210 Brettel, K. 213 Brodsky, S. B. 216 Bronger, W. I50 Brookes, C. 72 Brovko, V. Z. 98 Buchanan, D. L. 208 Bucur, R. V. 32 Budge, J. R. 98 Bumachin, N. A. 157 Bune, N. Ya. 212 Burkhanov, G. S. 36 Burlakova, 0. V. 215 Butochnikova, L. F. 38

Caga, I. T. Calka, A. Campbell, D. R. Cao, T. Cappadonia, M. Card, J. C. Carlier, E. Cassuto, A. Cenini, S. Cerclier, 0. Cerveny, L. Chadzhiev, S. N. Chakrabarti, D. J. Chambers, J. Q. Chan, M. K. Chen, S. Cheng, J. Chernova, G. P.

Chernysbev, M. L. Cheshokov, B. B. Chiba, T. Cho, B. K. Chou, P. Choudary, B. M.

100.

97 2 10 100 153 153 34

216 31

158 95 96 40 33

211 35

153 210 35. I59 215 157 95 96 39 I55

Page Christ, H. J. 37 Christopfel, W. C. 95 Chuang, C. T. 216 Chung, C. H. 33 Chuvaeva, L. E. 212 Ciacchi, F. T. 153 Clarke, M. J. 198 Cockman, R. W. 150 Cogen, J. M. 96 Colgan, E. G. 32 Comninellis, Ch. 152 Comrie, C. M. 149 Comte, P. 36, 212 Cook, R. I 0 0 Cooper, S. L. 60 Corti, C. W. 72 Cota-Araiza, L. 151 Cottington, I. E. 10, 18,

27, 60, 63, 118, 119, 129, 199, 208

Courbon, H. Craft, A. Crawford, E. J. Creaser, C. S. Crotti, C. Crovini, L. Cunningham, B.

Danowa, W. Davis, J. L. Davydov, A. A. Day, V. W. De Battisti, A. De Ruiter, R. De Visser, A. Degraff, V. A. Demas, J. N. Demonceau, A. Dene, J.

94 210 156 I86 158 72

100

36 148 154 210 153 94 91

152 I52 216 154

Derouin, C. R. 158, 216 Dhar, S. K. I49 Dimitrov, Kh. 2 I4 Dineff, P. 36 Diwell, A. F. 73 Dmitriev, R. V. 91 Doblhofer, K. 34 Dobos, K. 37 Dobrovolszky, M. A. 96 Doken, K. 157 Domen, K. 212 Donaldson, P. E. K. I18 Dong, S. I54 Dong, Z. 32 Dorr, G. 35 Dossenbach, 0. 36 Dossmann, Y. 92 Dovganyuk, V. F. 97 Doyle, M. L. I30 Drozdov, V. A. 154 Duczynski, E. W. 100 Duprez, D. 155 Diirr, H. 35 Dusan, J. 148

Page

D’Yachenko. S. A. 33 Dykh, Zh.L. 97

Ebsworth, E. A. V. 150 Edsinger, W. 31 Edwards, E. M. 63 Efimov, 0. A. 34 Efimov, 0. N. 92 Efimov, Yu. V. 93 Egawa, C. 215 Ehrhard, J. J. 31 Ehrhardt, J. J. 91 Ehrt, D. 100 Eiselt, 1. 34 Eisenberg, R. 94, 158 Elbaum, C. I49 Elfenthal, L. 32

Emel’yanov, V. I. 157 Emrick, R. M. 213 Eremenko, N. K. 33, 34,

97, 151 Ermolaev, V. N. 154 Esashika, K. 156 Evdokimov, S. V. 212 Ezaz-Nikpay, K. 96

Fal’kovskii, B. V. 157 Fare, T. 213 Fargues, D. 91 Farnetti, E. 157 Farrell, M. S. 94 Fasman, A. B. 154 Fedoseeva, T. A. 159 Feldhaus, R. 154, 213 Feng, B.-Z. 213 Fengyin, W. 36 Fernandes, A. R. 186 Fernandez, M. J. 157 Feurer, E. 213 Filippova, N. P. 32 Filonenko, G. V. 155 Fisher, G . B. I49

Flanagan, T. B. 151, 210 Fleming, R. H. 96

El-Morsi, A. K. 39

Fisher, J. M. 200

Flynn, J. R. 34 Foley, R. 2 10 Fondeur, F. 21 I Frank, A. J. 36 Franse, J. J. M. 91 Frese, K. W. 93, 152

Frings, P. H. 91 Frolov, V. M. 214 Froment, G . F. 96 Frumkin, A. N. 129 Frusteri, F. 213 Fujii, H. 92 Fujii, M. 216

Fujitsu, H. 214 Fujiwara, H. 92

Friedrich, F. 37

Fujikawa, K. 35

Platinum Metals Rev . , 1988, 32, (4), 226-229 226

Page Fujiwara, S. I56 Fukuda, I. I56 Fukuoka, A. 40, 154,

155. 214 Fung, A. S. I50 Furuya, F. R. 95

Gallhuber, E. 150 Gamboa, M. E. 151 Gandhi, H. S. 209 Gao, S. 97. 215 Garcia, R. 40 Gasser, D. 40 Gates, B. C. 98, 150 Gatts, C. E. 91 Genesca, J. 151 Georgiewa, M. 36 Getoff, N. 153 Giddings, S. 33 Gil Llambias, F. J. 97 Gillard, P. 213 Giner, J. 216 Giordano, M. C. 2 I I Giordano, N. 213 Girolami, G. S. 159 Gitlevich, A. E. 100 Gleason, W. B. 210 Goikhman, M. S. 36 Gold, G. 209 Gonzalez, R. D. 155 Goodenough,J.B. 93,151 Goodfellow, R. I50 Goodman, D. W. 149 Gorbatsevich, M. F. 38 Gordon, E. M. 158 Gorina, N. B. 36 Gorodetskii, V. 31 Gorodetskii, V. V. 212 Gorte, R. J. 149 Gottesfeld, S. 216 Gould, I. R. 153 Gozum, J. E. 159 Griitzel, M. 36. 212 Graham, G. W. 209 Grassian, V. H. 212 Grau, J. M. 96 Graziani, M. 157 Griffths, D. J. 209 Grimm, R. D. 36 Grishina, T. M. 93 Griitter, P. 210 Gryaznov, V. M. 91. 97,

151 Gum, W. 32 Guang, K. J. 100 Guczi, L. 155 Gudde, N. J. 204 Gulevich, Yu.V. 157 Gul’yanova, S. G . 91 Giintherodt, H.J. 2 10 Gu’ryanova, 0. S. 91 Guseva, M. I. 35 Gushchin, G. M. 148 Gut, G. 38

Hackbarth, E. 216

Page Hainfeld, J. F. 95 Haller, G. L. 92 Hallett, C. 73 Haltiwanger, R. C. 34 Hamada, T. I10 Hamnett, A. 93. 151 Hanafusa, K. 35 Hanaoka, T. 40 Haradome, M. 216 Harriman, A. 98, 151 Harris, I. R. 97,130,148 Harrison, B. 21, 73

Hashiguchi, Y. 156

Hashimoto, T. 92 Hatanaka, Y. 41 Hattori, T. 154, 156 Hayashi, R. 98 Haylock, J. W. 153 Heide, H. J. v.d. 100 Heitbaum, J. 21 1 Helkovskaya-Sergeeva,

E. G. 96 Hensler, G. 150 Herion, J. 91 Herrmann, J.-M. 94 Heumann, E. 100 Hikata, A. I49 Hill, S. P. I55 Hinden, J. I52 Hirschon, A. S. 215 Hishinuma, Y. 158 Hiyama, T. 41 Hodgson, K. 0. 210 Holloway, J. H. 150 Hong, Q. Z. 148

Hartung, Th. 21 1

Hashimoto, K. 35

Honji, A. 158 Horanyi, G. 93 Howard, J. K. 209 Hriljac, J. A. 40 Hrovat, M. 209 Hsu, Y. S. 214 Hu, H. C. 214 Hu, L. 97 Huang, H.-C. W. 100 Huber, G. 100 Hubert, A. J. 216 Hudgins, R. R. 97 Huizinga, S. 94 Hung, L. S. 148, 149 Hurst, J. K. 36

Ibers, J. A. 33 Ichikawa, M. 40, 97,

154, 155, 214 Igarashi, A. 40 Ikegami, A. 216 Imaizumi, S. 156 Imamura, S. 156 Imanaka, T. 157 Inanaga, J. 98

Inokuma, T. 41 Inoue, M. 156 Inoue, S. I56

Indlekofer, G. 210

Inui, T. Isaeva, V. 1. Ishibashi, H. Ishida, H. Ishida, R. Ishida, S. Ishii, Y. Ishikawa, H. Ishiyama, J.4. Isoe, s. Ito, 0. Ivanov, P. S. Ivko, A. A. Iwasaki, H. Iwasawa, Y. Izumitani, T.

Jablonski, E. L. Jacobsen, E. N. Janata, J. Jandova, J. Jelley, K. W. Jenkins, J. W. Jenny, H. Jensen, J. A. Jiang, H. J. Jin, Y. Johnson, C. E. Johnson, W. B. Jones, T. A. Josowicz, M. Jung, H.-J.

Page I56 97

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50. 203 92 37

Kadowaki, K. 60 Kagan, G. E. 91 Kainthla, R. C. 152 Kalyukova, E. N. 92 Kandasamy, K. 22 Kaneda, K. I57 Kanek, M. 35 Kaneko, M. 158, 216 Kaneko, T. 32, 33 Kang, W. P. 38 Kanomata, T. 33 Kanters, R. P. F. 150 Kaptanovskii, V. I. 153 Karpv , Yu.G. 209 Kasper, J. 157 Katsumura, S. 156 Kauffman, G. B. 141 Kawano, H. 99 Kawashima, A. 35 Kazakova, G. D. 31 Kazarinov, V. E. 129,210 Kelley, M. J. I50 Kemp, R. C. 100 Kennedy, B. J. 93, 151 Kenny, P. W. 95 Keramidas, V. G. 41 Keroglu, E. V. 31 Keryou, K. 39 Khan, S. U. M. 152 Khannanov, N. K. 94 Khazova, 0. A. 129 Khellaf, A. 213 Khlomov, V. S. 36

Page Khrustaleva, G. N. 100 Khutoretskaya, G. M. 154 Kiebwm, A. P. G. 39 Kim, C. H. 33 Kim, H. S. 33 Kimura, T. I54 Kira, A. 158, 216 Kita, H. 151 Kitaoka, Y. 32 Kleppa, 0. J. 150 Kleykamp, H. 92 Klimenko, E. B. 34 Knerel’man, E. I. 36 Knor, Z. 91 Kobayashi, T. 216 Kodera, T. 21 I Kohara, T. 32 Kohori, Y. 32 Koike, Y. 60 Kolar, D. 209 Komarov, V. S. 39 Komolova, L.Th. 31 Konishi, Y. 97 Kopylova, N. S. 93 Kornienko, L. P. 100 Kostin, N. A. 153 Kotz, E. R. 93 Kozlov, N. S. 38 Kozlova, M. D. 159 Krishnan, K. 41 Krstajic, N. V. 152 Ku, If. C. 60 Kubota, M. 35 Kubota, N. 37 Kudo, A. 212 Kuentzler, R. 92 Kukushkin, Yu. N. 98 Kumagai, H. 212 Kumagai, K. 60 Kumagai, N. 35 Kumar, C. V. I53 Kuranov, A. A. 209 Kurasov, S. S. 33 Kurenkov, N. V. 159 Kurita, K. 158 Kurusu, Y. 98 Kusuda, T. 91 Kut, 0. M. 38

Kuznetsov. V. A. 155 Kuzmin, V. A. 94

Lafer, L. I. Laine, R. M. 64, Lalauze, R. Lalevic, B. Lambrechts, M. Landolt, D. Langer, S. H. Lapidus, A. L. Lapka, R. Latov, V. K. Laughlin, D. E. W r , K. Lebedeva, 0. K. Ledig, L. Lee, D.-D.

97 156. 215

213 38 95 36 34

91. 96 210 215

33 I55 93

100 37

Plarinum Metals Rev., 1988, 32, (4) 227

Lee, K. N. Lee, T. Y. Leech, P. W. Leitner, K. Lenzner. J. Levin, E. S. Levin, P. P. Levy, M. Lewis, F. A. Li, D.-X. Li, G. P. Li, H. Li, H.-L. Li, Y.-E. Liang, D. Lin, Z.-Z. Lisichkina, I. N. Litvinov, V. S. Liu, H. Liu, J. Liu, J. C. h d i , G. Look, P. h h , W. h u w , c. w. Lundstrom, 1. Luo, R. J.

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37

Ma, D.-S. 37 Maclay, G. J. 37 Maeda, Y. 98 Maidan, R. 35 Maier, W. F. 96 Malakhova, N. D. 215 Mal’chevskii, I. A. 155 Malinin, A. B. I59 Mandler, D. 35, 94 Mann, K. R. 35 Manoharan, R. 93, 151 Mansilla, A. 97 Manzano, B. R. 157 Marchon, J.-C. 99 Mardaleishvili, R. E. 31 Mardashev, Yu. S. 31 Mari, C. M. 21 I Marin, G. B. 96 Markevich, S. V. 154 Markb, I. I58 MPrquez-Silva, R.-L. 2 16 Maruya, K.4 . 212 Maryshev, V. B. 38 Masuda, M. 21 1 Masuyama, Y. 98 Matsumura, M. 35 Matsuzaki, T. 40 Matteoli, U. 158 Matusek, K. I55 Mayer, J. W. 148, 149 McCabe, A. R. 1 1 McGiII, 1. R. 21 McKenna, M. J. 149 McMillan, M. 92 Mecea, V. 151 Medhanavyn, D. 156 Mednikov, E. G. 33 Medzhinskii, V. L. 38

Page Meissner, H. E. 41 Menchi, G. 158

Menovsky, A. A. 91 Mercea, P. 151 Metcalfe, I. S. 215 Meyer, 0. 32 Mezzapica, A. 213 Mibu, K. 91 Michailov, V. V. 100 Michailova, E. 93 Miki, S. 98 Mikuni, M. I53 Milchev, A. 93 Miller, L. L. 95 Mills, A. 33 Millward, G. R. 39, 98,

151 Minachev, Kh. M. 91 Ming, L. 36

Misono, M. 97. 98 Miyake, T. 156 Miyamoto, A. 156 Mochida, I. 214 Moiseev, I. I. 98 Mokwa, W. 37 Mori, K. 153 Mori, S. 99 Mori, T. 154. 156, 158 Mori, Y. 154 Morrison, S. R. 95 Morten, B. 159 Morton, J. R. I49 Moy, D. 216

Menoufy, M. F. 39

Min’kov, A. I. 34

Moya, S. A. 97 Mozhl, T. A. 21 I Miiller, P. I50 Miiller, V. 60 Munavalli, S. 36 Mungall, W. S. 158 Murahashi, T. 159

Murakami, Y. 154, 156

Murasheva, N. A. 215 Muresan, L. 151 Murray, M. 150 Muto, S. 110

Murakami, K. 95

Muranaga, T. 21 I

Nagle, J. K. 92 Naito, S. 39 Nakajima, H. 151 Nakamura, Y. 153 Nakato, Y. 152 Nambudripad, N. 149 Nannini, A. 41 Naoi, K. 34 Narita, K. 35 Nazeeruddin, M. K. 212 Nell, J. 33 Neta, P. 151 Neubert, W. 72 Newmark, R. A. 210 Nieuwenhuys, B. E. 32 Niki, Y. 210

Page Nikitin, V. V. 31 Nishida, 0. 40 Noels, A. F. 216 Nomura, K. 212 Nodus, D. 150 Novikova, A. V. 214 Noyori, R. 99, 157

Oda, Y. 32 Odaka, T. 159 Oelhafen, P. 210 Ogawa, T. 216 Ogorodnikova, 0. N. 209 Oh, S. H. I49 Ohgomori, Y. 99 Ohnishi. H. 35 Ohno, T. 98 Ohta, T. 99 Okada, K. 159 Okamoto, T. 92 Okuhara, T. 97, 98 Olmstead, M. M. 92 Onishi, T. 212 Onuki, Y. 60 Oota, A. 92 Orekhova, N. V. 151 Oro, L. A. 157 Osaka, T. 34 Oshima, R. I10 Otake, K. 98 011, H. R. 60 Owens, B. B. 27

PaPI, Z. 96 Paffett, M. T. 216 Paik, W.-K. 158 Palamarchuk, L. V. 155 Pampus, K. 32 Papapolymerou, G . A. 96 Parenago, 0. P. 214 Parera, J. M. 96 Park, H. L. 33 Parkinson, B. A. 212 Parmaliana, A. 213 Paszczynski, S. 95 Patel, 1. 33 Pavese, A. 211 Pavlovic, 0. Z. 152 Pecherskii, M. M. 212 Peden, C. H. F. 149 Perissi, R. 72 Pern, F.J. 36 Pestryakov, A. N. 154 Peterson, M. W. 212 Petri, 0. A. 93, 150 Petrov, E. S. 40 Petrovsky, P. V. 33 Pfeiler, W. 209 Philpott, J. E. 61 Piacenti, F. 158 Pichat, P. 94 Pickup, P. G. I52 Pieck, C. L. 96 Puolat, C. 213 Pimentel, G. C. 212 Piuotti, M. I58 Platiner, E. 152

Page Plavnik, G. M. 100 Polcari, M. R. 216 Pollina, D. M. 159 Popovskii, V. V. 154 Porta, F. 158 Poteat, T. L. 38 Potter, T. J. 209 Prakash Rao, A. 99 Preston, K. F. I49 Propchenko, A. V. 40 Prudenziati, M. 159 Puippe, J.-C. 36 Purdy, D. L. 27

Pyzhova, L. Ya. 92

Quint, R. M. 153

Radlinski, A. P. 210 Rajaram, R. R. 204 Rakowski Dubois, M. 34 Ramaraj, R. 158. 216 Ramasseul, R. 99 Ramirez, F. 40 Rao, L.-F. 155 Raphael, A. L. 100 Ratovskii, G. V. 215 Raub, Ch. J. 37, 188 Rausch, W. 100 Ravi Shankar, B. K. 215 Redondo, A. 216 Rehurkova, S. 96 Renker, B. 60 Resasco, D. E. 92 Rheingold, A. L. 98 Richoux, M. C. 151 Rizmayer, E. M. 93 Robertson, D. H. 211 Robson, G. G . I I8 Rodriguez-Izquierdo,

J. M. 40 Roe, A. L. 210 Rogl, P. 149 Rolewicz, R. I52 Ronsheim, P. 100 Rosenfeld, M. J. 215 Ross, G. S. 97 Rotzinger, F. P. 36, 212 Ruckenstein, E. 31 Russell, M. J. H.122, 179

Pyle, A. M. 34

Rytvin, E. I. 95

Saburi, M. Sacchi, M. Sachtler, W. M. H.

38, 97. Saito, Y. Sakakura, T. 99. Sakamoto, Y. 151. Sakata, Y. Sakellson, S. Sakurai, J. Samata, Y. Shnchez-Delgado,

R. A. Sands, T. Sansen, W.

99 159

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216 41 95


Page Santiago, J. J. 149 Saporovskaya, M. B. 215 Sasaki, K. 157 Sato, K. 156 Savel’ev, M. M. 96 Sayari, A. 149 Schlebos, P. P. J. 150 Schlodder, E. 213 Schmidt, F. K. 215 Schmidt, G. F. 41 Schmidt, L. D. 96, 215 Schmutzkr, R. I50 Schomburg, D. 150 Schreiner, S. 156 Schroder, G. 158 Schultze, J. W. 32 Schuster, J. C. I49 Schwank, J. 31 Scott, J. P. 98 Searles, R. A. I23 Sears, W. M. 95 Seeber, W. 100 Semionova, A. D. 93 Senda, Y. 156 Sen’kov, G. M. 38 Sermon, P. A. 39 Serov, Yu. M. 91 Sevastyanova, A. S. 159 Shafimvich, V. Ya Shafirovich, Ya. V. Sharf, V. Z. Sharp, P. R. Sharpless, K. B. Shastri, A. G. Shatinskii, V. F. Shechter, H. Shibai, H. Shimada, Y. Shimizu, Y. Shinjo, T. Shinohara, H. Shirakawa, K. Shirinskaya, L. P. Shriver, D. F. Shukla, R. S.

Siedle, A. R. Silipas, D. Silk, M. H. Silveston, P. L.

Shul, Y . 4 .

Sirotti, F. Skakunova, E. V. Skarjune, R. P. Smirnova, N. V. Smith, F. J. Smith, G. D. W. Smith, J. G. Sneddon, L. G. Sobolov, A. S. Socket, H. G . Sodeyama, T. Sohn, B.-K. Sokolov, V. I. Solis, V. Song, H. Souter. .I. W.

94 36 97 34

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Spogliarich, R. I57 Srinivasan, A. 216 Srinivasan, S. 158 Starosel’skaya, L. F. 40 Staunton, W. 95 Steer, C. J. 159 Steggerda, J. J. 150 Stepanov, A. P. 32 Stetsenko, A. I. 33 Stitsyn, M. A. 210 Stolyarov, I. P. 98 Stolz, R. 213 Stolz. T. I54 Streiff, R. 94, 95 Strelets, V. V. 92 Stucki, S. 93 Stul’, B. Ya. 157 Stunenegger, B. 36 Suck, J.-B. 210 sugi, Y. 40 Suhr, H. 213 Sulpice, A. 60 Suls, J. 95

Sunshine, S. A. 33

Spivey, J. J. 39

Summers, D. P. 93, 152 Sundaresan, S. 215

Sushumna, I. 31 Siiss-Fink, G. 41 Sutherland, R. R. 100 Sutton, M. A. 28 Suzuki, M. 157 Suzuki, 0. 156 Suzuki, T. 209 Svotola, J. 91 Swette, L. 216 Sykes. A. G. 170 Szab6, T. I50

Tabebayashi, K. 91 Tabuchi, T. 98 Takahashi, N. 156 Takamizawa, H. 159

Takegami, Y. 156 Taketa, Y. 41. 216 Takeuch, K. 40 Takezawa, T. 91 Tan, F. L. 100 Tanaka, K. 152 Tanaka, M. 99, 157 Tanaka, T. I52 Tang, R. 97 Taniguchi, S. I54 Tanimoto, M. 39 Taqui Khan, M. M. 99 Tashlykov, I. S. 35 Tatsumi, T. 40

Teitel’, E. I. 148 Terokhova, M. I. 40 Thomas, J. M. 39,98,15 1 Ticianelli. E. A. 158. 216

Takaya, H. 99

Tegtmeyer, D. 21 I

Page Timurzieva, M. A. 40 Tkach, V. S. 215 Toenshoff, D. A. 159 Tornroos, K. W. 150 Tokunaga, Y. 99, 157 Tomashov, N. D. 35,

100, 159

Tooley, P. A. I50 Topor, L. 150 Toratani, H. 41 Torp, B. 32 Tourbot, R. 209 Trimm, D. C. 38 Trusova, N. A. 95 Tneciak, A. M. 99 Tsakova, V. 93 Tsubomura, H. 35, 152 Tsurin, V. A. 32 Tsyrul’nikov, P. G. 154 Turro, N. J. 153 Tykochinskii, D. S. 95 Tzou, M. S. 2 14

Tominaga, H. 40

Uchida, Y. 99 Ueda, K. 152 Underwood, R. P. 215 Urbanovich, I. I. 39 ursu, I. 151

Valueva, I. T. 38 Van Bekkum, H. 39 Van Dam, H. E. 39 Van Deltl, F. C. J. M. 32 Van Der Euk, J. M. 94 Van Der Spiegel, J. 149 Van Houten, J. 153 Van Langeveld, A. D. 32 Van Trimpont, P. A. 96 Van Veen, J. A. R. 94

Vargaftik, M. N. 98 Vasina, T. V. 96 Vaska, L. I56 Vassiliev, Yu. B. 129 Vayenas, C. G . 214 Verderone, R. J. 96 Vettier, C. 91 Videlo, I. B. E. 100 Vijayaraghavan, R. 149 Villar, R. 60 Vinogradova, A. I. 215 Vladirnirov, B. G. 35 Vlasenko, V. M. 155 Voitekhova, E. A. 36 VoitlPnder, J. 209 Vorob’ev-Desyatovskii, N. V. 98

Voronova, L. I. 93 Voyer, J. 72 Vuillemin, J. J. 213

Wada, K. 157 Wagner, H. 91 Walsh, P. T. 50, 203 Wane. R. 32

Vannice, M. A. 39

Page Wang, Y. 155 Washburn, J. 41 Watanabe, A. 153, 157 Watanabe, Y. 99 Weber, R. S. 92 Weber, W. H. 209 Weeks, S. A. 93, 151 Wei, C. S. 149 Weitzer, F. I49 Wessel, I. 72 Whalen, M. V. 2 Wibberley, B. L. 26 Wiesendanger, R. 210 Wilde, B. E. 21 I Wilde, M. 154, 213 Willner, I. 35, 94 Winquist, F. 37 Winterbottom, J. M. 97,

Wolf, G. K. Worrell, W. L. Wyatt, M.

Xiao, F. Xu, J. F.

Yablonskaya, E. E. Yakersov, V. I. Yakovlev, K. I. Yamaguchi, M. Yamamoto, T. Yamanaka, A. Yamashita, Y. Yamazaki, T. Yang, F. Yang, L. Yano, H. Yastrebov, V. A. Yasui, H. Ye, D.-B. Yentekakis, 1. V. Yersin, H. Yokoi, T. Yonezawa, S.

Yoshida, M. Yoshida, S.4. Yoshida, Z.-I. Yu, c. Yu, J. Y. Yu, K. M. Yiicelen, F.

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Zabludovskii, V. A. 153 Zahraa, 0. 38 Zaidi, S. A. H. 155

Zetkin, A. S. 91 Zharkov, B. B. 38 Zhil’tzova, 0. A. 35 Zhu, J. 21 1 Zhuchkov, A. N. 210 Zimmer, G . 37 Zingg, T. 210

Zengerle, K. 35

ZiQkowski, J. J. 99 Zvkova. E. V. 36


SUBJECT INDEX TO VOLUME 32

a=abstract Page Acetalization, cyclohexanone, on platinum metals, a 156 Acetone, chemisorption, electroreduction. on Rh.

Rh-Ni catalysts, a 93 Acetoxylation, oxidative, propylene. by PdCl ,, a 157

93 alcohols on 0-Pd(II0 surfaces. reactions, a 148 CO, on Pd-Ru, Pd-Ni, HI effect on, a 91

on Pt-, Rh particleslA1,0,(0001), a I49 H 31. 130 nitrocompounds. on PtIPt, /Ti, /TiO, electrodes, a 93 0,. on Pt-Ag, a I54

98 C , , C, , formation from syngas, a 154, 155. 214 ethyl. electro-oxidation, on S-treated Pt black, a 34 from syngas. on Ru-Mo-Na,OlAl,O,, a I56 methyl, adsorption, oxidation, on platinised Pt+Sn

electrode, a, , 210 decomposition, on Pt, Rh wire, a 96 electro-oxidation. a 93, 151, 211 from syngas, a 40. 215 HI photoproduction from, a 212 oxidation on Pt-Ag, a I54 reduction to CH,, at Ru electrodes, a 93 synthesis. on Pdlzeolites, +Fe, La, a 155

methyl. ethyl, propyl, reactions on 0-Pd(III), surfaces, a 148

oxidation, on Ru/Ce(IV) oxide. a I56 secondary. oxidation to ketones, electrochemically, a 34 Unsaturated, from PhCH=CHCOMe. a I57

98 C,, , formation from decane, by RhCI(CO)(PR,),, a 157 formation, usmg Rh-phosphine two-phase catalysts 179 synthesis, from propylene, a 41

Aldoximes, for nitrile formation. a I57 Alkaloid. with 0~0,. for dihydroxylations, a 158 Alkanes, catalytic reactions, a 157, 212, 215 Alkenes, formation, a 155, 212

216 Alkylation, isobutene with ethene, on PdlY zeolites, a 40 Alkynes,. hydrqgenation. on PdlC, a 96

34 Ally1 Acetates, carbonyl allylation with Pd complexes, a 98 Allylation, active methylene compounds, + ally1 oxime

I56 98

Allykhloride, coupling with CO, a I56 Ammonia, detection, by Pt-MOS, a 37, 213

21 1 I I

Anisole, catalytic reactions, a 215 Arctic Ocean, cathodic protection of vessels I I9 Arenes, for biaryls formation, on RhCI(CO)(PMe,),, a 99

37

Batteries, implanted, book review 27 Benzaldehyde, hydmgenation, hydroslation, a 158 Benzene, carbonylation, photochemical. a 158

hydrogenations, a 39, 154, 214 10

Binryls, formation from arenes, on RhCI(CO)(PMe,),, a 99 Biochemistry, o portunities for platinum group metals 170 Blomedicnl EJneerlng, microbrazing Pt wire 118

nuclear implanted batteries 27 Book Reviews, batteries for biomedical devices 27

Catalytic Activation of CO,, ACS symposium 187 geology of Bushveld Complex 63 Platinum-Group Element Exploration 208

Boranes, transformations. a 40 Brazing, for Pt wires, in prostheses I I8 Bushveld Igneous Complex, book review 63

survey, in "Platinum 1988" I I8 Butadiene, hydrogenation, a 214 Butane, formation, on Pd/y-AI,O,, a 214

I54 38

159, 170. 198

Adsorption, 2-naphthoic acid, at platinised Pt, a

Alcohols, production on Pd(PPh,), +SmI,, a

Aldehydes, carbonyl allylation of, a

reactions, by Ru complexes, a

terminal. trtmerisation. by Rh complexes. a

carbonate, by Pd(0)-phosphine system, a carbonyl. aldehyde, by Pd complex, a

electroproduction from nitrate, at Pt, Ni, a oxidation. on Rh-Pt gauzes, characterisation

Arsine, detection, by Pd-MOS device, a

production in Pd reactor, from cyclohexane

oxidation, on PtlAI,O, + Ce, La oxides, a selectivity to, on cyclohexane dehydrogenation, a

Cancer, complexes for anti-tumour use

Page Capacitors, Pt-MOS, as NH, sensors, a 213 Carbon Oxides, catalytic activation, ACS symposium 187

CO, adsorption on Pd-Ru, Pd-Ni. HI effect on, a 91 automotive emission control 123 coupling with allylhalide. on Pd(0). a I56 desorption from Pt-, Rh/a-A1,0,(0001), a 149 detectors, a 37 Fischer-Tropsch reaction, a 97. 156 for Pd carbonyl phosphine complexes synthesis, a 34 hydrogenation reactions. a 40, 97, 154. I55 oxidation reactions. a 40, 149. 155, 214. 215 photoreduction to CH,. on Ru. 0 s colloids, a 35 production on carbonylation, by Pd complexes, a 157 reaction with aldoximes, for nitrile formation, a 157 reduction to CH,, at Ru electrodes, a 93 +HI. organic compound production, a 96

CO,, formation from HCOOHlNaCOOH, a 155 hydrogenationlreduction, on Pt complex, a 156 photochemical reduction to CO. a I52 reduction to CH,, at Ru electrodes, a 152

94 Carbonylation. reactions, a 157, 158 Carbonyls, reduction, by IrH,(PR,),, a I57

RhU, Rh,, cluster anion formation, a I57 Carboranes, transformation, a 40

204 conference, Liebfrauenberg, Sept. 1987 19 heterogeneous. a 38. 39. 40. 96. 97. 98. 154. 155. 156.

CO,/HCO;, photoreduction to formate, a

Catalysis, 9th Int. Congress review, Calgary

- 213, 214

39 homogeneous, a 40,41,98,99. 156. 157. 158.215.216 Homogeneous Catalyst Research Kit 122

of volatile organic compounds, a

metall6complexes. in electrodic processes. review, a 92 RuO,.xH,O, effect of Ce ions, a 33

Catalysts, automotive, emission control I23 for CO, activation, ACS symposium, review 187 history, Kuhlmann's work 84 Iridium, colloids, properties of, a 98

38 Iridium Complexes, a I57 Ir-Fe carbonyl clusterslSi0 , , for syngas reaction, a 2 14 Osmium Complexes, for dihydroxylations. a 158

IH RuOs (CO) 1 -(All clusters, a 98 Palladium. cluster, for propylene oxidation, a 98 Pslladium Alloys, Pd-Ag. Pd-Y, H diffusion

Pd-Zr. for CO oxidation, a 40 Palladium Complexes, for carbonylations, a 157

Pd carbonyl phosphines. synthesis, a 34 PdCl , , for propylene acetoxylation. a I57 PdCl ,(CP)(Py-X), for quadricyclane

isomerisation, a 98 PdCII(PhCN)l-SnCI,. for carbonyl allylation. a 98 PdCII(PPhJ), + SnCI,, for I-heptene reaction, a40 Pd(O), for manoalide formation, a 156 Pd(0) tetrakis(triphenylphosphine), for ketone

isomerisation. a I57 Pd(acac),-PRl-BF,OEt,, for dimerisations, a 215 Pd(dba),-phosphine system, for allylations, a 156 Pd(I1) thiocarkmide, for hydrosilylations. a 98 Pd(I1) + methionme. for hydrogenations. a 215 Pd(PPh,), promoted, for silylations. a 41 Pd(PPh,), + SmI, + propargylicacetate, for

alcohols, a 98 Pd acetate-MIC, for oxidation of C,H,, a 155 Pd collold/~-cycIodextrIn, for photoreduction, a 94 Pd mercapto-hydroxyl chelateslSiO,, activities, a 155

39 PdFeISlO,, bimetallic, for CO hydrogenation. a 154

40 Pd-Fe carbonyl clustersISi0, , for C , -C I alcohol

2 I4 PdlAI,O,, a I55

% PdlCdS, photocatalyst, stabilisation with EDTA. a 35 PdIchPrroPI, for HI, CO, formation, from

HCOOHlNaCOOH. a 155

effect on Pt dehydrogenation. a

membranes, ethylene hydrogenation, a 97

Pd powder, for benzene hydrogenation, a

methanol synthesis from syngas, a

synthesis, from syngas, a

PdIC, for alkynes. dienes, hydrogenation, a


Catalysts (confd.) Page 39

PdlY zeolites, for isobutene alkylation. a 40 Pdly-AIIO,, for butadiene hydrogenation. a 2 I4 Pdlzeolites, for isomerisation, a 214 Pdlzeolites, + La, Fe, for methanol synthesis. a 155 Platinum, for diesel generator exhaust 61

in lean bum engines I23 in phosphoric acid fuel cells, a 41 wlvcrvstalline films. for CO oxidation. a 214

Pdlsupport. for benzene hydrogenation, a

for oxygen sensor 199

h A u colloids, properties. a 39 wire. for HCHO, HCOOH. CH,OH, N,H,

decomposition. a 96

adsorption. a I54 Pt-Rh auzes, surface characterisation. a I I

98 [Pt,(j~dppm),l, for dimethyl formamide, a 156

Platinum Metals, borane. carborane reactions, a 40 for cyclohexanone reactions, at high pressure, a 156

Platinum Metalsflnorganic Support, for organic 96

PtFelSiO,, himetallic, for CO hydrogenation, a 154

Pt-CulAl,O,, formation, structure, a I54 Pt-RelAI,O,-CI. CI effects on, a 96 Pt-RelH mordenite, for n-heptane hydroconversion. a39

212 Ptl , Pt-Re/, Pt-Re-CrlAl,O,, for dehydrocyclisations,

S pretreatment. a 213 for methylcyclopentane conversion, a I54

PtlAI,O,, for 2,6dinitrotoluene hydrogenation. a 38

Platinum Alloys, Pt-Ag, for methanol oxidation, 0,

Platinum t!omplexes, for hydrosilylations, a

compound synthesis, from syngas, a

PtRelyAI,O,, a 38

Pt-TiO,lSiO,, for H, photoproduction, a

for cyclohexane decomposition 10 for cyclohexene hydrogenation, a 38

for reforming, effect of Ir additions, a for n-octane dehydrocyclisation, HI effect on, a 38

38 methanation activity, after reduction, a 154 removal of CO, NO, HC. from I.C.E. exhaust, a 96 sizes on thermal cycling in 0, and HI. a 31 sulphided, for C, hydrocarbon reforming, a 96

PtlAI,O, + Ce, La oxides, for butane oxidation. (1 154 PtlC, for glucose liquid phase hydrogenations, a 39 PtlFeNaY, for hydrogenation. hydrogenolysis, a 2 14 PtlH mordenite, for n-heptane hydrogenation, a 39 PtlH-ZSM pentasils, for n-hexane transformations, a 96 PtlNnY, Fe effect on. a 214 Pt/SiO,/Si, for cyclohexene dehydrogenation. a 96 PtlSiO,, D addition, exchange of propene, a 39

94 PtlY zeolites, production, characterisation. a 214 PtlYSZ, for CO oxidation. a 215 Ptly-Al,O,, coked, reforming, regeneration of. a 213

for benzene hydrogenation, coal formation, a 154 for cyclohexane dehydrogenation, coking effect, a 38

FWzeolites, for isomerisation. a 214 PtlzeoUtes + additions, for n-hexane isomerisation, a 39 Rh complexeslSi0, gel, synthesis, a 91 RhFelSiO,, bimetallic. for CO hydrogenation, a 154 Rhodium, electroreduction of acetone on. a 93

wire. for C,H, hydrogenolysis, a 91 wire. for N,H, decomposition. a 96

Rhodium Alloys, Rh-Ni. electroreduction on, a 93 Rh-F? auzes, surface characterisation I 1

Rhodium &omplexes, bis(thioether)-bridged Rh, svnthesis. reactions. a 34

R/TiO,, iliuminated. H, : D, exchange. a

-olefin reactions, a 99 RhCI(CO)(PMe,),, C-H bond activation, a RhCI(CO)(PMe,),. irradiated. for olefin

RhCI(CO)(PR,),. for decane carbonylation. a RhX(CO)(PR, ), . for photocatalytic

99

synthesis, a I51 157

dehydrogenkions. a 212 Rh(I1) acetate, for indandione reactions, a Rh-phosphine, two-phase. water soluble, for

Rh-tticyclohexylphosphine, for ethylene glycol

Rh,(CO). clusters. for nitriles, a

zeoliteJSiO,, for syngas reaction. a

215

hydroformylation I79

formation, a 99 I57

214 40

Rh-Fe, Rh-Ir cprbonyl clusterslNaYRJaX)

Rh-FelSIO,, for olefin hydroformylation. a

Catalysts (confd. J Page RhlAI,O,, for meta-cresol dealkylation. a I55

for syngas reaction, activity, a 214 RhlLaO(OH), support structures. a 40 RhlSiO,, for CO hydrogenation, a 215

for CO oxidation, a I55 for C, H, hydrogenation. hydro-formylation, a 97 improved activity, for alkane hydrogenolysis. a 215

RhfI’iO,, bonding in, a 92 Rhly-AI,O,, RhlYSZ, for CO-NO exhaust

conversion, a 215 Rh,, RhFe clusterslNaY zeolites, for alkene. alcohol

formation, from syngas, a I55 RuO1/y-AI~OI, for water gas shift, a 91 Ruthenium, characterisation. by thermal analysis, a 97

for C-N bond cleavage, a 215 Pb, Bi ruthenales, for olefin electro-oxidation. a 94 Ru( I , I , lo), for ethane hydrogenolysis, a 215

cyclopropanation, a 216 L,(HIO)Ru-O-Ru(OHI)L,. for H,O photo-

oxidation, a 36 Ru porphyrin. cholestJ-ene for epoxidation. a 99

212 RuCI(CO)(NO)(PPh,), , for carbonylations, a 158 Ru(bipy),* +/H,SO,ln-TiO,, for photolysis. a 153 Ru(bpy) + +RuO,lCdS, for photocatalysis. a 35 Ru(C0) , (CH COO) , (PBu ,),, hydrogenation, a I58 Ru(III)-EDTA-ascorbate-H,O,, for cyclohexane

oxidation, a 99 Ru(I1)-BINAP. for hydrogenations, a 99 IHRu.ICO),,I-. for Droovlene hvdro-

Ruthenium Complexes, for alkene metathesis,

Ru p-0x0 dimer, for water oxidation. a

forriylati’on; a ’ ’ * 41 98 IH, RUOS,(CO)~, I -{Al) cluster, a

[RuCI , (H ,O)A 1 . for olefin oxidation to ketones; a 99

[Ru(bpy),(CO),]’* + NADH, for CO, reduction to CO. a 152

[Ru(NH,),CII’+ + Ce(1V). for 0, evolution. a 158 [Ru(NH,),(H,O)I’+ + Ce(lV), for 0,

~~ evolution, a 158 Ruthenium Complexes, Ru,(CO)., Ru(CO),(PPh,),,

for nitro-benzene carbonylation, a 158 Ru(bpy),*+ + RuOllCdS, for H,O photocatalysis, a

35 Ru-Mo-NalOIAl,O,, for alcohol synthesis. a Ru-PtlY zeolite, for isoalkane synthesis, from

RulAI,O,, Fischer-Tropsch, a 91 for CO hydrogenation, oxidationlreduction

R u l C e O oxide, for waste water oxidation. a RulSiO,, for cyclohexane reactions, K additions, Rulsupport, charaterisation. by thermal analysis, a three-way, ceria promoted

syngas. a

effect, a

performance. a Catalytic RePflion Guide, Johnson Matthey Cathodic Protection, of oil rigs, ships. in the Arctic Cells, chlorate. diaphragm, anodes in, a

CO.O,.PtlZrO,~Y,O,~lPt.O,. solid electrolyte, 0

~~

I56

40 , 156

91 I56

a 98 91 73 96 83

I19 211

. . .. . pumping in, a 214

electrochemical. HIO splitting, model, a I52 for bromate production, using RuO,lTiO,Ti anode, a 152 photoelectrochemical, with a Ptln-Si electrode, a 152

Ceramics, SiN containing, syntheses 64 + glass. Pd-Ag wiring for, a I59

Cerium, additions to catalysts, a 33, 154, 158 Cermets, Pt+LaSrCrO,lzirconia. for steam reduction, a 21 I Chemhrption, acetone, on Rh. Rh-Ni catalysts, a 93

HI , O,, conductance effects on Pt films, a 31 Chlorate, cell, anodes in. a 21 I Chlorine, effects on Pt-Re/Al,O ,-CI, a 96

for regeneration, of coked Ptly-AI,O, catalysts. a 213 Chloroplatink Acid, radioisotopically labelled, a 159 Cholest-S-ene, stereospecific epoxidation. by air, on Ru

Cinnamk Acid, hydrogenation, by Pd(I1) complexes + Cluster Lobelling, by Ir4(CO)ii, a Clusters, Pd catalysts. for propylene oxidation, a Coal, formation. in spent catalysts. a

porphyrin. a 99

methionine. a 215 95 98

I54

Platinum Metals Rev., 1988, 32, (4) 23 1

Page

Pd. Pd-Ni contacts. review of wear resistance, a 95 Pd-Ag alloys, a 36, 37 Pd-Co alloys, shiny, electrodeposited, a 36 Pd-In alloys, on stainless steel, by diffusion. a 36 Pd-Ni alloys. by pulse and reverse current plating, a 36 Pt modified aluminide, corrosion resistance, a 94, 95

18 Pt on Re single crystals, a 31 Pt-polymer composite, on steel, corona discharge, a 94 Rh, deposition by ax . impulse currents, a 153

37 RuO,ITiO,, surface study. a I53 surface, a 36. 31. 94. 95

98 39

I53 Pd-C-Ag, self-lubricating composites, in motors, a 159

26 catalysis 19. 204 catalytic activation of CO,, review I87 Ruthenium in Cancer Chemotherapy I98 superconductivity, in platinum metals 60

216 35, 100

151 211 212 I I9

Coatings, acrylonitrile polymer, on Pt electrodes, electrochemical properties, a 34

on Ni superalloy, surface tests

effect of additives, on properties, a

Colloids, Ir, IrO,.xH,O catalysts, properties, a

Composites, electrodes + Pt, in 0, sensors, a Pt-Au catalysts, preparation, properties, a

Pt-polymer on steel, a 94 Conferences, Symp. on Temp. Measurement

Copper, in RuO, thick film resistors, a Corrosion, behaviour of Pd-Ti surfaces, a

catalytic, in Pd-Ru membranes. a in Pd+steel, on H absorption, a in Ru-Ti oxide anodes, a orevention. bv imoressed current svstems . , . protection, a 159 resistance, amorphous Ni-Nb-Pd-RhlNb, electrodes to

sea-water, a 35 electrodeposited Pd-Co alloys. a 36 Pt modified aluminide coatings 18. 94. 95

33 stability, of Pd surface alloyed steels, a I59

Cresol, meta, dealkylation, on Rhl-, Pd/AI,O,, a 155 Crucibles, Pt, Pt alloy, for laser glass production. a 41, 100

210 in Pt-Cu-Ni. after deformation, a 209

Crystals, Pd, Pt. high purity, high quality. growth, a 213 TI,Pt(CN),, structure, a 92

10 dehydrogenation, effect of coking and Pt content, a 38 hydrogenolysis, dehydrogenation, on RulSiO, , a 98 oxidation, by Ru(1II)-EDTA-ascorbate-H ,O , , a 99 production. a 38, 154

Cyclohexanone, hydrogenation, acetalization, a I56 Cyclohexene, dehydrogenation on SiO ,lPtlSi, a 96

hydrogenation, on Pt/AI,O,, kinetics, a 38

Decane, photocartmylation, by RhCI(CO)(PR,), , a 157 Decomposition, HCHO, HCOOH, CH,OH, H,H,, a 96 Dehydroamino Acid, hydrogenation, a 215 Dehydrocoupling, reactions, to synthesise polymers 64 Dehydrocycliation, hexane, hexene. heptane. n-octane, a

38, 213 Dehydrogenation, alkanes, to olefins. a I57

cyclohexanes. a 38, 98, 213 cyclohexene, on Si0,lPtlSi. a 96 hydrocarbons. photocatalytic, by Rh complexes, a 212

Desorption, CO, from Pt-, Rh particleslA1,0,(0001), a 149 Detector, fast response, oxygen I99

arsine. by Pd-MOS devices, a 37 biophysical, using [Ru(phi),lCI,, a 34 CH,, C,H,, n-C,H,,, by In,O, + PdCI,. a 37 CO, by SnO,/Pt, a 37 fast optical, Ru complex for time response test, a 213 flammable gases 50, 203 glucose. bv enzvme-wlvaniline filmlPt fibre. a 95

RuO,.xH,O. by Ce ions, a

Crystallisation, in PdSi amorphous alloys, a

Cyclohexane, decomposition, in Pd tube reactor

hydrocarbk Ibngcbairi. by Pt hot wire. a hydrocarbons, unsaturated, by R-MOS. a

NH,, by Pt-MOS. a 37

95 37

H,, a 31. 95, 213

organic impurities in water, by Pt monitor I29 0.. a 31. 37, 38 semiconductors, a 37 thick film voltammetric, RuO,, Bi,Ru,O,, a 95

91 Deuterium, diffusion, in Pd-Cu alloys, a

Deuterium (conrd.) Page 39. 94

l,Z-Dichlorwthene, structure. photochemistry. a 212 Dienes, hydrogenation, on PdlC, a 96 Diesel, generators, exhaust control 61 Diffusion, Au, in PdCuSi during irradiation. a 32

91 22, 32, 97, 130, 151

91 209 209 158 157 215

I56 158 38 95 40

100

isotopic exchange, with C,H.. CIH, , a

D,, in Pd-Cu alloys, a H,, in Pd, Pd alloys

to form PtSi on hydrogenated Si, a Pt, in SnO, multilayer films, a Si, polycrystalline, into PtSi, a

Dihydroxylation, between olefins and OsO,, a /?-Diketones, synthesis, from a, /?-epoxy ketones, a Dimerisation, propylene, to linear hexenes, a Dimethyl Formamide, formation, reversible, from CO, ,

Dimethyl Oxalate, hydrogenation, to methyl glycol, a Z,CDinitrotoluene, hydrogenation, liquid phase. a Diodes, Pd-Si tunnel MIS, for H, leak detection, a Dioxane, synthesis, from I -heptene, a

Electrical Conductivity, in PtPdlTiO,. Pt films, on H,. 0, chemisorption, a 31

Electrical Contacts, crossover systems, Pd-Ag, a 100 Pd. Pd-Ni, electrodeposited. wear resistance, a 95 Pd-C-Ag, self-lubricating composites, a I59

Pt, Rh. Pd, IrlGaAs, thin film, a 41 100 210 91

in Pt-U compounds, a 91 210

34. 35. 92, 93. 94. 150.

H,. Me,NH, on IPt,(dppm)J, a

DNA, cleavage, by Ru(DIP), Macro"', a

PdlZnlPd-p-type Gap, characteristics, a 100

PtSi-As doped Si, properties, a Electrical Resistance, in Pd-Mn, a Electrical Resistivity, in Pd-Fe alloys, a

Electrical Resistors, Pd-U-Si amorphous alloys, a Electrochemistry. a

151, 152. 210, Electrodemition. a 36. 37. 94. . . .95.

Pd-Ag' alloys, 'a Pt, on Pt, Ti, TiO,, for electrodes, a P t. Pt allow. review Rh, effectbf additives, a

Electrodes, anodes. in molten carbonate fuel cells platinised for corrosion protection on Arctic

Pt black, SO, treated. alcohol oxidation, a Pt+Ru/C, Pt+Ru. for methanol oxidation, a Pt-IrO,/, Pt-IrO,-PdOlTi. characteristics, a RuO,lTiO,lTi, for Na bromate formation, a Ru-Ti oxide, phosphate effect on, a

Au-Pd system, electrochemical properties, a cathodes, Pt, in phosphoric acid fuel cells, a

RuO,, H, evolution, a in phosphoric acid fuel cells, a Ni-Nb-Pd-Rh. amomhous. laser Drocessed.

vessels

21 I I53 37 93 .-

188 37

200

I I9 34

151 21 I 152 212 151 41 93

158

properties, a 35 PbPdO,, CdPd,O,. in alkaline fuel cells, a Pd,Mn, H solubility in, a

Dlatinised Pt. for 2-naohthoic acid adsomtion. a

216 I51 21 1 93

platinised Ni, for nitrate. nitrite, reduction, a

' Sn modihed, for ithylene glycol ox;dation, a 150 platinised Pt + Sn, for methanol, formic acid.

Pt, acrylonitrile coated, properties, a 34 electrochemistry of toluene on, a 21 I for nitrate, nitrite, reduction, a 211 in fuel cells, optimisation, a 216 in phosphoric acid fuel cells, a 159 in water monitoring sensor 129

93 thin films, pretreatment, a 92

37 153 153 216 35

electro-oxidation, a 151.211 158 34

cell, a I52

adsorption, oxidation. a 210

nucleation of Hg and Ag on. a

+ZrO, electrolyte, 0, detection, a Pt wire, in TMB electrolysis, whisker formation. a Pt + composite, in 0, sensors, a Pt-Cr, for 0, reduction, in fuel cells, a

Pt-SPE. hlr-SPE, PtRu-SPE. PtSn-SPE, for methanol

PtlC, power optimisation in SPE fuel cells, a

Ptln-Si. discontinuous, in photoelectrochemical solar

Pt-SPE. for H, oxidation, 0, reduction, a

PtlNBRlpolypyrrole, fast anion doping, a


Electrodes (conid. ) Puge PtlPt. -/Ti, -/TiO, structure. adsorption

characteristics, a 93 p-lnP(h)/n-Si. for H, evolution from model cell. a 152 Ru. CO. CH,OH reduction. a 93

electroplated. for CO, reduction to CH,. a 152 RuO,, thick film. voltammetric sensor. a 95 RuO,/Ru-Ti oxide. phosphate effect on. a 212 Ru(bpy)J + RuO,/CdS. water photochemical

Ti oxide, Pd ion implanted, a 32 Ti/IrO,-Ta,Ol, for 0, evolution. characterisation. a 152

Electrolysis, tetramethylbenzidine. by Pt electrode. a 153 water. high temperature, at Pt cermet/zirconia, a 2 I I

Electrolytes, for depositing Pt. Pt alloys. review I88 Pt cermet + YSZ zirconia, for steam reduction, a 21 I

Electron Transfer Reactions, interfacial. between Pt colloids and reducing radicals, a 151

Electroplating, Pt. Pt alloys, review I88 Emhrittlement, of steel. Ta, by H2. prevention 21. 31 Emission Control, automotive, a 96

73 CO-NO reaction, on Rh catalysts. a 215 CO,, in atmosphere, ACS symposium review 187 from lean bum and other engines 123 of diesel generators 61

Enzymes, co-ordination of platinum metals species to 186 H,O splittinp. modelling with Ru complexes. a 212

Epoxidation, stereospecific. cholest-5-ene derivatives, 99

Ethane, hydrogenolysis. on Ku(l,l,lO). a 215 Ethylbenzene, isomerisation. on Ptl. Pdlzeolites. a 2 I4

37 97

hydrogenation, hydroformylation. on Rh/SiO,. a 97 oxidation to vinyl acetate, on Pd acetate-Li/C. a 155

Ethylene Glycol, electro-oxidation. on Pt electrode. a 150 formation, a 99, 158

E.E.C., automotive emission control legislation 123 Pt-Rh thermocouple calibrations 72

Extraction, platinum group metals I70

Films, around Pt on thermal cycling in O2 and H,. a 31 Ir oxide. chargingldischarging kinetics, a I52 TiO, , Pd implanted, electrochemical studies, a 32

Fischer-Tropsrh, reactions. a 97. 156 Formaldehyde, decomposition, on Pt. Rh wire, a 96 Formate, Na. + HCOOH. for H,, CO, formation. a 155

photoproduction from CO,/HCO;. a 94 210

catalytic decomposition. a 96, I55 electro-oxidation. a 93, 211

Fuel Cells, a 41. 158. 159. 216 molten carbonate, corrosion in anodes 200

Fuels, liquid, on promoted Fischer-Tropsch catalysts. a 156

splitting. a 35

by three-way catalysts, ceria promoted

by air + Ru porphyrin. a

Ethylene, detection. by Pt-MOS. a hydrogenation, on Pd alloy membranes. a

Formic Acid, adsorption. oxidation, a

Gallium, triple point. use in Pt thermometer. a Gases, flammable. detection Gauzes, Rh-Pt, for HNO, manufacture Generators, diesel. exhaust control Geology, book review

of Bushveld Complex, book review Glass, amber, thermocouples for use in , a

laser, Pt crucibles for, a Glasses, amorphous, PdSi, Pd-H-Gd. Pd-U-Si. u

in RuO, resistors, a metallic, PdCuSi irradiation induced defects. + ceramics, Pd-Ag wiring for. a

Glucose, microsensor. a Glucose 1-Phosphate, liquid phase oxidation. a Glucuronic Acid 1-Phosphate, production, a

100 50 I I 61

208 63

I59 41. 100

209. 210 216

U 32 I59 95 39 39

Heavy-Atom Marker, use of PtCl , as I70 1-Heptane, hydrosilylation, on thiocarbamide. a 98 n-Heptane, reactions on Pt catalysts, a 39. 213 I-Heptene, hydrocarboxylation, to dioxane. a 40 n-Hexane, reactions. on Pt catalysts. a 39. 96. 213. 214 n-Hexene, dehydrocyclisation. on Pt catalysts. a 213 Hexenes, formation from propylene, by Pd complexes. a215 Hex-1-yne, formation by Ir complex. a 157 History, Frkdkric Kuhlmann, industrial pioneer 84

History (conrd.) Pirge spectroscopy 28 Viacheslav Vasil'evich Lebedinskii, Rh chemist 141

Homogeneous Catalyst Research, Kit. Johnson Matthey 122 Hydrazine, decomposition, on Pt. Rh wire. a 96 Hydrocarbons, automotive emission control 123

C,-C, formation, from CO hydrogenation. a 215 C,. reforming on sulphided Pt/Al,O,. a 96 detection, a 37 formation, from methylcyclopentane. a 38 higher. formed by Fischer-Tropsch reaction. a 156 longchain, sensor, by Pt hot wire, a 95 saturated, photocatalytic dehydrogenation. by Rh

complexes, a 212

Hydroconversion, n-heptane. a 39 Hydrocarboxylation, I-heptene. a 40

Hydroformylation, a 40. 41. 97, 99, 214 Rh-phosphine, two-phase. water soluble catalysts for 179

Hydrogen, absorption. in AISI 4130 steel + Pd. a 21 I in Pd-Si alloys, properties, review 83

adsorptionldesorption, on spongy Pt. a 31 detectors, a 37. 95 diffusion, through Pd alloy membranes 22. 32. 97 effect on CO adsorption, in Pd-Ni. Pd-Ru. u 91 effect on conductance, on chemisorption. a 31 effect on magnetic state, in Pd-Fe-H. a 32 effect on n-octane dehydrocyclisation, a 38 effect on selectivity, of RlH-ZSM pentasils. a 96 embrittlement of steel, prevention by Pd 21 embrittlement of Ta. prevention by PI'. a 31 evolution, on RuO, cathode, a 93 heat induced effects on PtlAl ,O j , o 31 in regenerating coked reforming catalysts. a 213 isotope exchange, on PtRely-Al,O,. a 38 oxidation, on Pt-SPE membrane electrode. a 35 permeation, in Ru-Pd membranes, a 151

213 photoproduction, a 35. 152, 153. 212 production, from HCOOH/NaCOOH. on Pdlcharcoal 155 solubility in Pd, Pd alloys. a 32. 148, 151. 210

Hydrogenation, 2,6dinitrotoluene, liquid phase, a 38 alkynes. dienes on Pdlactivated C. a 96 asymmetric, on Ru(l1)-BINAP dicarboxylate. a 99 benzaldehyde. by Ru(0) complexes, a I58 benzene. a 39. 154. 214 butadiene. liquid phase, by Pd/y-Al,O,. a 214

204 cinnamic acid, a 215 CO, by Fischer-Tropsch reaction, a 97, 156

97 for methanol, hydrocarbons synthesis. a 215 for methanol formation, on Pdlzeolite. a I55 for organic compound synthesis. a 96 to alkenes, alcohols, on Rh,, RhFe/NaY. a 155 to C , . C, alcohols, on bimetallic catalysts. a 154

CO,, to dimethyl formamide, by Pt,@-dppm),, a 156 cyclohexanone. high pressure, on platmum metals. a 156 cyclohexene, on Pt/Al,O,, kinetics, a 38 dehydroamino acid, by Pd(I1) complexes. a 215 dimethyl oxalate. to methyl glycolate, ethylene

I58 ethylene. a 97 PhCHKHCOMe. to unsaturated alcohol, a 157 stereoselective, I ,3 diketones. on Ru(II)-BINAP 99 toluene, on Pt electrodes, a 21 I

Hydrogenolysis, alkanes. on RhlSiO,, after treatment. u 215 cyclohexane. on Ru/SiO,. effect of K. a 98 ethane, on Ru(I.I.IO), a 215 methylcyclopentane. on PtINaY, a 2 I4 n-hexane, on Pt/FeNaY. a 214 on PtRely-Al ,O , . a 38

Hydrosilation, benzaldehyde. by Ru(0) complexes. a I58 Hydrosilylation, a 98. 157

Impressed Current Systems, for Arctic use I I9 Indandiones, decomposition. by Rh(I1) acetate, a 215 Indium, wetting, Pt, a I48 Inks, Ru based, in thick film resistors. a I59 Integrated Circuits, Cu-Ru0,-glass resistors in. a 216 Ion Beam Bombardment, effect on properties. a 32 Ion Irradiation, Au in Pd-Cu-Si. a 32

through thin Pd films. for Pd-MOS sensors, a

catalytic, 9th Congress on Catalysis

for hydrocarbon. oxygenates synthesis. a

glycol, by Ru complexes. a

propane. a 97


Page Iridium Alloys, a 33. 129

34 Ir oxometallates. Keggin ion, characterisation. a 210 IrR(CO)L,(mnt). characterisation, a 94 lr,(CO)t,, as label for measuring molecular length, a 95 Ilr(CO),F(COF)(PEt,),l+. synthesis, structure, a 150 IIr(NO)(CO)CI(PPh,),lBF,, photolysis. a 35

Iridium Oxide, a I52 Iron, additions to catalysts, a 155, 214 Isoalkanes, synthesis, on RuPtHY zeolites, a 40 Isobutene, alkylation with ethene. on Pd/Y zeolites. a 40 Isomerisation, u.P-epoxy ketones, to Pdiketones. a 157

ethylbenzene, m-xylene, on Pt/zeolites, a 214 n-hexane, on Pt/zeolite + additions. a 39 quadricyclane, on trans-CI,Pd(CP)(q.-X). a 98

ITS-90, International Temperature Scale 26

Johnson Matthev. Catalvtic Reaction Guide 83

Iridium Complexes, Ir dppm p-oxo. a

Homogeneo&'Catalyk Research Kit "Platinum 1988"

I22 I18 ~~

Joining 95. 118

Ketones, I .3diketones. stereoselective hydrogenation, on Ru(I1)-BINAP, a 99

u.P-epoxy. for isomerisation reactions, a I57 production from olefins, on [RUCI,(H,O),I+. a 99

Kuhlmann, Fddkric, history 84

Lasers, action in tluoroaluminate glass, a Lanthanum, oxide, addition to Pt/AI,O,. a I54

100 41

Lean Bum, engines, emission control in 123 Lebedimkii, V.V., history of a Rh chemist 141 Lithium Nlobnte, Ti diffused. in Pt box, for waveguides 10

Magnetism, Co-R films. effects of Cr. W. a 209 ErPd,Sn. low temperature, Massbauer study, a 91 in YbPdSb. YbPdBi compounds, a I49

33 Pd-Fe-H. H effect in, a 32

phosphate. glass, production in Pt alloy crucibles. a

MnRhAs. effect of pressure on. a

Pd-H-Gd, amorphous, a 209 Pd-U-Si amorphous alloys. a 210 U-Pt compouids. properties, a 91 Y(Fe,-,Ru,),. II 92

Manoalide, seco-manoslide. systhesis. a I56 Medical, implanted electrical devices. hook review 27

labelled chloroplatinic a ~ . for anticancer use. a 159 microbrazing for Pt wires, in prostheses I I8 Ru complexes in cancer chemotherapy. conference 198

IOG Membranes, Pd, Pd alloys 10. 22, 97 : 48, 151

Ru complex, lipid, for 0, production 36 Methanation, activity by Pt/AI,O,. a I54

37 production, a 35. 93. 152. 215

Methykarbamntes, formation from nitrobenzene, a 158 Methykyclohexane, dehydrogenation. on R/AI,O,. a 213

roduction from toluene. on Pt electrodes, a 211 Me& y lc y clopentane , reactions,,on Ptcata1ysts.a 38, 154, 214 Methylem, compounds, allylation. a I56 Monoacetate Propylene Glycols. synthesis. on propylene

157

Naphthok Acid, adyrption. on platinised Pt electrode. a 93 Nitrate, electrochemical reduction, a 21 I Nitric Acid, IMnUfaCNre I I NitrUes, formation. from CO. H,O. aldoximes. a 157 Nitrite, electrochemical reduction. a 21 I Nitrobenzene, reactivns. a 34. 158 Nitrogen, C-N cdralytic bond cleavage, a 215

21 I ion im lantation, effect on Pd, Pd alloys tribology, a 148

Nitrogen &i+ , automotive emission control I23 NO, reaction with CO, on Rh, Pt catalysts, a 149. 215

Norbomadiene, production, from quadricyclane, a 98 Nuclear Implants, in body, book review 27 Nuclear Waste, ""Ru. '06Ru recovery from I70

n-octnne, dehydrocyclisation. on Pt/AI,O ,. a 38 011, rigs, corrosion protection in the Arctic I I9 Olefins. dihydroxylation with OsO,. a 158

Ru(DIP), Macro"', for DNA cleavage. a

Methane, detection, by Inlo, + PdCI,. a

acetoxylation, by PdCl, . a

electroproducuon from nitrate, at Pt, Ni. a

Olefins (contd.) Page electro-oxidation. on Pb-, Bi ruthenates. a 94 formation from alkanes, by irradiated Rh complex. a 157 hydroformylation. on Rh catalysts. a 40. 99 oxidation to ketones, on [RuCI,(H,O),I+. u 99

33 96

for interfacial electron transfer, to Pt colloids, a 151 volatile, heterogeneous catalytic oxidation. review, a 39

Osmium Alloys, a 92 Osmium Complexes, a I50 Osmium Oxides, use in electron microscopy I70 Oxidation, alcohols, to ketones, on Pt electrode. a 34

butane, by Pt/AI,O, + La, Ce oxides, a I54 CH,OH, on Pt + Ru anodes, a 93 CO, catalytic, a 40, 149. 155. 214 cyclohexane. a 99 electro-, a 94. 150. 151. 211 ethylene, to vinyl acetate. on Pd acetate-LK, a 155 formic acid, a 93. 211 high temperature. Pt-Pd-Rh, Pt-Rh, Pd-Rh foils. a 209 H,, on Pt-SPE membrane electrode. a 35 Ir oxide films. kinetics of, a I52 liquid phase, of glucose I-phosphate, a 39 methanol, on Pt-Ag alloys. catalytic activity. a 154 NH ,, characterisation of Rh-Pt gauzes I I of polychlorinated biphenyls 186 olefins. to ketones, on IRuCI,(H,O),I+. a 99 propylene. to ally1 acetate, on Pd clusters. a 98 resistant Ir-Al, Ir-Hf alloys, for aerospace use 129 RhlSiO,. to improve activity, a 215 water, by Ru complexes, a 158, 212 wet, of waste organic compounds, a I56

I54 detectors, a 37. 38. 153 effect of alcohol conversions, on Pd(II1). a 148 effects on conductance, on chemisorption after

31 electrodes, in alkaline fuel cells, a 216 evolution, from H,O, by Ru complexes. a 158. 212, 216

152 for oxidising CO on Rh single crystals, a 149 photoproduction, from H,O. a 35. 36, 153 pumping. on porous Pt catalysts film. a 214 reduction, a 35. 216 sensors 199 size effect on Pt/AI,O,. on heating, a 31 transfer, between Rh catalyst and 0 ion support, a 215

21. 159. 211 91

FePd,, superlattice formation, a 91 37

YbPdSb, YbPdBi, low temperature properties. a 149 crystals, growth, a 213 electroplated, tribology. effect of N,'. a 148 H solubility and diffusivity in. a 32

100 in Pd-Sn-Si MIS device, for 0, detection. a 38 in Schottky diodes, a 41 ions, implantation in TiO, films. a 32

35 metallised poly(ethylene terephthalate), for gas

permeation. a I51 Pd(lll), photochemistry of dichloroethene on, a 212 Pd(lll)-Odosad surfaces, reactions of alcohols on, a 148 Pd-Au system, electrochemical properties. a I51 Pd-MOS detectors, a 37 Pd-Si tunnel MIS diode, for H, detection. a 95 Pd-W0.-W system, FEM study, a 91 PdlPd-Znlptype GaP contacts, characteristics, a 100 systems, phase formation, a 32 thin films. H, permeation through, a 213

synthesis, for electronics. a I59 Pnllsdium Alloys, H diffusion in Nbular membranes 22

Palladium + Platinum, formic acid oxidation. a 21 I Pdlndium-Cnrbon-SUva, composites. for motors. a 159 p.llndiumCobalt, electrodeposiud. properties. a 36 Pnlladium-Copper, D, diffusion in. a 91 PalladiumCopper-Hydrogen, effect of Ar ion. a 32

Oligwilazanes, synthesis 64 Optical Properties, RuO, thin films, a Organic Compounds. catalytic preparation. a

Organometnllics, polymers, syntheses 64

Oxygen, adsorption on Pt-Ag, state, a

chemisorption in Pt, PtPd/Ti02, a

on DSA type Ti/IrO,-Ta,Ol electrodes. u

Palladium, in steel compounds, ErPd,Sn. magnetism in. a

PdCI,, in h , O , gas sensor. a

in electrical crossover systems, a

implanted into Ti, corrosion resistance. a

Platinum Metuh Rev., 1988, 32, (4) 234

Palladium Alloys (conrd.) . Page Palladium-Copper-Silicon, amorphous. a 32, 149 Palladium-Europium, Palladium-Europium-Hydrogen,

H solubility, pressure-composition isotherms, a 148 Palladium-Gadolinium-Hydr~~n, amorphous, a 209 Palladium-Gold-Silver-Tin, N, effect, a 148 Palladium-Hydrogen, Ar ion bombardment, a 32 Palladium-Hydrogen-Iron, magnetic state, a 32 Palladium-Indium, diffusion coatings, properties, a 36 Palladium-Iron, annealing effects, on properties, a 148

FePd, superlattice formation on metal additions. a91 Palladium-Manganese, PdMn,, ordering in, H

solubility, a 151. 210 Palladium-Nickel, CO adsorption on, a 91

pulse and reverse current plating, a 36 Palladium-Rare Earths. ordering transformations I30 Palladium-Rhodium, foils, oxidation, a 209 Palladium-Ruthenium, CO adsorption on, a 91

membrane catalysts. corrosion, H permeability, a I 5 I Palladium-Silicon, electro-oxidation, a 93

H properties in 83 Palladium-Silicon-Uranium, properties, a 210 Palladium-Silver, electrodeposition. a 37

pulse plated, a 36 thick-film crossover properties. a 100 wiring for glass-ceramic materials, a I59

Palladium-Silver, Palladium-Yttrium, H diffusion membranes, a 97

Palladium-Steel, surface protection on alloying, a 159 Palladium-Titanium, corrosion behaviour, a 35, 100 Palladium-Vanadium, after irradiation, a 210

Palladium Complexes, a 33. 34. 92, 155, 213 Palladium Membrane Reactor 10 Palladium Oxide, in thick film resistors. a 209 Palladium Silicides, Pd,Si, growth, a I49

I49

Permeability, through Pdlpoly(ethy1ene

Phase Changes, in thin film Pd systems. a

polycrystalline reordering on epitaxial, a Pd,Si amorphous, crystallisation, a 210

terephthalate). a 151

Phase Diagrams, Ir-Cu, a 33 PdO-RuO,. PdO-Bi,Ol, RuO,-Bi,O,. a 209 Ru0,-Bi ,O, -PdO. a 209 Ru-Cu-Ni-S. a 33 Ru-Mo, at 900-2oOo0C, a 92 Ru-Si-N, Ru-Si. a 149

Phenol, oxidation. on RulCe(1V) oxide. a I56 Phenylacetylene, hydrosilylation. a 98

212 Phosphoric Acid, fuel cells. a 158, 159 Photocatalysis. a 35, 36. 94. 152, 153. 212 Plating, pulse, Pd. Pd alloys. a 36

pulse reverse current, Pd, Pd-Ni. a 36 10

catalysts, early industrial work by Kuhlmann. history 84 cermet, for steam reduction. a 21 I colloids, in electron transfer reactions, a 151 compounds, a 32. 33, 60. 91. 92. 148. 150 crystals, growth, a 213 dispersion strengthened 2. 159 electrochemical nucleation. of Hg and Ag on, a 93

37 in fuel cells, a 216 thin film, pretreatment of, a 92

electrolytic deposition of, review I88 for water pollution monitoring I29 hot water detector. for longchain hydrocarbons. a 95 implantation to prevent Ta embrittlement. a 31 in aluminide coatings, on Ni superalloy. surface tests 18 in composite electrodes. in 0, sensors, a 153 in MOS gas detectors. a 37 in SnO,/Pt. CO sensors. a 37 particles, size on thermal cycling in 0, and H,. a 31 powder polymer composites. coatings on steel, a 94 Pt particles/u-A1,OJ{0l), CO desorption from, a 149 Pt( I I I ) . photochemistry of dichlorwthene on. a 212 Pt-MOS. thin film capacitors, as NH, sensors, a 213 Pt-SnO,, interdiffusion. a 209 Pt-yttria. Pt-zirconia. in space resistojets 2 PtlC. in SPE fuel cells. a I58

H. in Pd-Ru membranes. a 151 32

Phosphates, effect on corrosion. Ru-Ti, RuO,, a

Platinum, box. for waveguide production

electrodes, adsorption. a 93 in cell, for 0, detection. a

Platinum (contd.) Page Ptlpoly-Si/SiO,lSi( 100). preparation, annealing, a 209 PtlSiC. support in phosphoric acid fuel cell, a 158 radioisotopes, for labelling chloroplatinic acid, a 159 resistance thermometer. using Ga triple point. a 100 spongy, H adsorptionldesorption tests, a 31 structure on fluoride supports, a 31 thin films. synthesis, for electronics, a I59 wettability by In, a I48

“Platinum 1988” I I8 Platinum Alloys, electrolytic depsition of, review 188

in phosphate laser glass production. a 41 Platinum-Palladium, for formic acid oxidation. a 21 I Platinum-Chromium, in fuel cells. a 216 Platinum-Cobalt, thin films, magnetic properties. a 209 Platinum-Copper, order in, a 209 Platinum-Copper-Nickel, disordering, a 209 Platinum-Iron, shape memory effects in I10 Platinum-Palladium-Rhodium, foils, oxidation, a 209 PIatinum-Rhenium(III), structure, a 31 Platinum-Rhodium, foils. oxidation, a 209

gauzes for HNO , manufacture, surface structure I I surface effects. a 31 thermocouples, European calibrations 72

Platinum-Silver, for methanol oxidation, a I54 Platinum-Tungsten, Platinum-Rhenium-Tungsten,

wires, in high temperature strain gauges. a 213 Platinum-Vanadium, reactions with Si. a 148

Pt,Ni, --x, photwmission of adsorbed Xe. a 91 Platinum Aluminide, on superalloys 18, 94. 95 Platinum Complexes, with biological molecules I70

Na,PdH,, synthesis, structure, a I50

production, from (C,H,)Pt(PPh,),, structure. a 150 63 95

100 formation at a-Si:H, a 91 in Schottky diodes, formation, a 216

209 123

automotive exhaust. a 96 204

CO-NO reaction, on Rh catalysts, a 215 CO, in the atmosphere, review of ACS symposium 187 destruction of polychlorinated biphenyls I86

73 of generator exhaust gas 61 waste water, by oxidation on RulCe(1V) oxide, a 156 water, monitoring, by Pt I29

Polychlorinated Biphenyls, destruction of I86

Polysaccharides, conversion to H , , a I55

Propane, hydrogenolysis, on Rh wire. a 97 94

Propargylic Acetates, alcohol production, a 98 39

Propylene, acetoxylation, byPdCl a 157 215

aldehydes, a 41 98

I I8

PdPtCI,@,-CO)(PPh,),. redox reactions. a 33

Platinum Metals, geology of Bushveld Platinum Metals Alloys, welding, a Platinum Silicides, contacts with Asdoped Si. a

layers. on polycrystalline Si, growth, a

catalytic, 9th Int. Congress on Catalysis

Pollution Control, automotive, in lean bum engines

exhaust emissions. by three-way catalysts

Polymers, organometallic. synthesis 64

Polysilazanes, synthesis 64

isotopic exchange, with D,, on PtlTiO,. a

Propene, D, addition, exhange, on PtlSi02. a

dimerisation. by Pd complexes, a hydroformylation, by [HRu (CO ,, )I -, for

oxidation, on Pd clusters, to ally1 acetate, a Prostheses, neurological, microbrazing for

Quadricyclane, isomerisation, by trans-CI,Pd(CP)(Py-X), a 98

Reduction, electro. acetone, on Rh, hh-Ni catalysts. a CO, CH,OH, to CH,, at Ru electrodes. a nitrate, nitrite, on Pt, Ni electrodes, a 0,. on Pt-SPE membrane, a toluene, on porous Pt electrodes. a

0,. at Pt-Cr electrodes, a photo, CO,/HCO,-, to formate, a

C, hydrocarbons. on sulphided PtlAl ,O ,, a methylcyclopentane on Ptl, Irl, Pt-Ir/AI,O,, a

Resistance Thermometer, Pt, using Ga triple point, a

Resistors, RuO,, thick films, a

93 93

21 I 35

211 216 94

154. 213 Ptly-AI,O,, regeneration of, a 213

96 38

100 2

41. 159. 216

Reforming, catalysts, S effect on. a

Resistojets, for propulsion in space


Resistors fconrd.) Pug' thick film, Ru-Bi-Pd oxides, a

carbonylation. of organic compounds. a catalytic preparation of organic compounds. a

209 I I 8 157 96

204

H in Pd-Si alloys 83 heterogeneous catalytic oxidation of organics. a 39 metallocomplexes, in electrocatalytic systems. a 92 Pt. Pt alloy electrolytic deposition I 88 Pt(l1) compounds with purine and pyrimidine bases. a 33 superconductivity conference 60 thermocouples in the glass industry, a I59 water gas shift reaction, a I56

Rhodium, coatings, deposition, properties. a I53 compounds. RhNa-Y. RhNa-X. paramagnetic. a 149

92 electrodeposition. effect of additives. a 37 electrodes, in molten carbonate fuel cells 200 history. of V. V . Lebedinskii 141 Rh particles/o-A1,0,(0l}, CO desorption from, u 149 Rh(l I I), Rh(100) single crystals, CO oxidation on. a149

Rhodium Alloys, Rhodium-Arsenic-Manganese, effect 33

Rhodium-Platinum, gauzes for HNO, manufacture I I Rhodium-Platinum, Rhodium-Palladium, foils.

Reviews, annual survey "Platinum 1988"

Congress on Catalysis. 9th Int.. Calgary electrical contact fretting, a 95

Rh,Ti. RhTi. bonding in, a

of pressure on magnetism, a

high temperature oxidation. a 209 Rhodium Complexes, a 34. 35, 210 Rhodium Iodides, characterisation, a 212 Ruthenium, compounds, a 92. 150. 159. 200 Ruthenium Alloys, Ruthenium-Copper-Nickel-Sulphur,

phase diagram, a 33 Ruthenium-Molybdenum, constitution, a 92 Ruthenium-Osmium-Vanadium, properties. a 92 Ruthenium-Palladium, membrane catalysts. u I5 I Ruthenium-Silicon, Ruthenium-Nitrogen-Silicon, a I49

Ruthenium Complexes, anti-cancer treatment I98 reaction with biological molecules I70 Ru(biby),CI,, luminescence. in optical detectors. a 2 I 3 Ru(bpy)>DIP1 . Ru(bpy)!phen' +. excitation

Ru(bpy) ,? +-viologen-oxidant, electron transfer. LI 94 I00

Ru(I1) o-diimine + Ag(l). luminescent exciplexes. u 152 [Ru(phi),lCI,. synthesis, spectroscopic properties. u 34 [ R u , .Os,(bpy),l(PF,),. emission properties, u IS0

Ruthenium Oxides, RuO,. cathode. for H: evolution. a 93 in resistors, a 41. 159. 216

209 33 95 33

153 153 I86

41 216

37. 38 2 12 I10 I19 91

100 I48

Silicon Nitride, ceramics 64 Silylation, vinyl halides. on promoted Pd(PPh,),, a 41 SMSI, in Pt/AI,O,. in methanation. a I54 Sodium Bromate, production by electrolysis.

using RuO,lTiO,/Ti anode. a I52 Solar Cells, photoelectrochemical. with a discontinuous

Pt/n-Si electrode. a I52 Solid Polymer Electrolytes, fuel cells. u I58 Solubility, Hi in Pd. Pd alloys. u 32. 148. 151. 210

I29

Spectroscopy, history 28 Spirocyclopropmes, production. a 215 Steel, AlSl 4130. effect of Pd addition. a 21 I

I19

spectra. a 153

Ru(DIP), Macro"'. for DNA cleavage. a

phase equilibria, for resistors, a thin films. optical properties, a

RuO?. Bi,Ru20,. thick film. sensors. a RuO,.xH,O. corrosion and catalytic activity. a RuO,/TiO,. coatings, surface study, a RuO,. in CCI,, for staining polymers. a

Ruthenium Tetroxide, oxidation of PCBs

Schottky Diodes, PdiSi0,in-Si. C-V characteristics. a Pt silicides in. production, n

Pd-MOS, Pt-MOS. for gas detection. a Rh iodides. photoelectrochemical properties. u

Semiconductors, In,O, + PdCI,. a 37

Shape Memory, effect in Pt-Fe alloys Ships, corrosion protection in the Arctic Silicnn, amorphous hydrogenated. PtSi formation. u

polycrystalline, As doped, contacts with PtSi. [ I

reactions with Pt-V. Pt-Ti. a

Space, I r oxidation resistant alloys for propulsion by resistojets 2

corrosion prevention in Arctic conditions

Steel (conrd.) Puge low alloy, Pd in surface, H embrittlement prevention 2 I

94 stainless. surface alloyed with Pd. a I59

Strain Gauges, high temperature. Pt alloy wires for. a 213 Structure, changes in Pd-Fe alloy. on annealing. a 148

I .2-dichloroethenes. on Pd( I I I ). Pt( I I I ), a 212 Ir dppm w-0x0 complexes, u 34 Pd-Mn. a 210 Pd-Rare Earth alloys. ordering transformations.

H behaviour I30 Pd-U-Si. amorphous, a 210 Pd-V. after irradiation. a 2 10 Pt-Cu alloys, a 209 Pt-Fe alloys. shape memory effects I10 Rh dppm pox0 complexes, a 34 Rh!CI,(CO),(ETM)!. Rh,CI!(p-CO)(ETM),, a 34 [Co, . ,Pt,. ,lTa,PtSe , b . a 33

97 154. 213

Superalloys, Pt aluminide coatings on 18. 94 Superconductivity 32. 60. 92 Supports, fluoride. Pt structure on. u 31 Surface Science II. 19. 32 Synthesis Gas 40. 96. 99. 154. 155. 156. 204. 214

Tantalum, H embrittlement. Ptt ions implantation. a 31 Temperature Measurement, a 26. 100 Tetramethylbenzidine, electrolysis. using Pt. a 153 Thermocouples, a 72. 159 Thick Films, a 37. 41. 95. 159. 209. 216 Thin Films, acrylonitrile on Pt electrodes. electrocatalytic

Pt-polymer composite coatings on. a

Sulphur, adsorbed, effect on Rh/SiO: activity. a pretreatment effects. on reforming catalysts, a

properties. a 34 M/GaAs. stable contacts. u 41 Pd. for Pd,Si growth on <I00>Si. u I49

H ! permeation through. i n Pd-MOS sensors. a 213 low temperature deposition. a 213 phase formation, a 32

precursors. a I59 Pt. electrodes. pretreatment. a 92

detectors, a 37 PtSi. on polycrystalline Si. growth, a 209

209 213

31

Pd. Pt, synthesis, by CVD, from organometallic

in MOS structures, for NH,. HC. ethylene

Pt-Co. effects of Cr, W on magnetic properties. u Pt-gate MOS. as NH, sensors. a Pt-Re(1lI) alloys. spectroscopic studies. ( I

Ptiglass. conductance changes on Hi. O1

Rhl,, RhI - ,. photoelectrochemical properties. ( I

Pt-SnO,, interdiffusion. a 209

chemisorption. a 31 212

RuO,. optical properties, a 33 Tin, adatoms to Pt electrode. for ethylene glycol.

Tin Chloride, effect on Pd complexes. a Tin Oxide, inferdiffusion in Pt films. a Titanium, implanted with Pd ions, corrosion

TiOi/Ti electrodes. Pd ion implanted. a

methanol, formic acid oxidation, a 150. 210 40

209

resistance, a 35. 100 32

21 I IS7 91

Toluene, electrochemistry, on porous Pt electrodes, a I-Triethylsilylhex-1-yne, formation by Ir complex. a Tungsten, Pd-W0,-W system, FEM study. LI

Vanadium Alloys, Vanadium-Ruthenium-Osmium,

Vinyl Acetate, formation from C,H, , u Vinyl Halides, for vinyl silane synthesis. a Vinyl Silane, synthesis. on promoted Pd(PPh,),. LI

Water, electrolysis, at Pt cermetizirconia. a

low temperature properties. a 91 I55 41 41

211 monitoring pollution in I29 oxidation. to O 1 . by Ru complexes. [ I 158. 212 photochemical splitting, a 35. 36. 152. 153 purification. on Ru/Ce(IV) oxide. u I56

Water Gas Shift Reaction, a 97. 156 10 9s 95

213

91 214

Waveguides, Ti-diffused LiNbO >. made in PI box Wear, of electrical contacts. a Welding, platinum metals alloys. a Wires, h-W, Pt-Re-W. for strain gauges. u

Xenon, adsorbed. photoemission. on Pt,Ni, JIII) . [ I

m-Xylene. isomerisation. on Pti. Pd/zeolites. u


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