ture (cross-linked montmorillonltss and graft nodular molecular sieves, etc.) were also pmpared. lt was found that each of these new molecular sieves had charac- teristic catalytic properties. Rare earth he- teropolyacids (salts) and organic rare earth compounds, each having a well- defined structure, were also found to pos- sess specific catalytic activities.

(ii) Significant advances were obtained in research on the modification and func- tionalization of various molecular sieves by removing aluminium atoms; supplying sili- con atoms or adding heteroatoms; which led to significant improvements in the cata- lytic properties of the molecular sieves. For example, the formation process for USY zeolltes, the structure of USY and hydrkte transfer processes over USY were all examined systematically; some new visw- points on secondary pore structure, frame- work and non-framework aluminium atoms and the mechanism of hydride transfer etc., were suggested. Moreover, informatbn was obtained from the studies of the modification of the molecular sieves by the introduction of heteroatoms into the framework (for instance isosubstitutbn with Zn, 8, Fe, Ti, Cr and Sn, etc.), the substitution process and its effect on the catalytic properties of the modified materi- Sk.

(iii) A number of new results and new concepts were obtained in the following areas; the role of the cations located at different sites of zeolite structure; the rela- tionship between dlffusbn and reaction; the crystallization mechanism in molecular sieve synthesis; the carbonization mech- anism of hydrocarbons over the surfaces and in the channels of mobcular &eves; the relationship between defect structures and the catalytic activities of the rare earth complex oxides; as well as the structure of

N3

the acttve components in rare earth cata- lysts during potymerizatbn. In additbn, detailed investigatbns ahout new reac- tions, such as the aromatizatbn d hydro- carbons, the oxidattve coupling of me- thaneandtheshapesebcttveconversbn of methanol to light alkenes were carried out.

(iv) Some new methods were de- veloped and applied to the investigation of the physico-chemical properties of the catalysts: the use of positron annihilation spectroscopy, Ftaman spectroscopy, etc., to measure a monolayer dispersion threshold value of an oxide supported on the zeotites; the development of a physi- sorption method to determine the pore in- tegrky of zsolltes; the appkcatbn of solid- state NMR spectromstry, atom bombard- ment mass spsctrometry, far-IR and IR spectroscopytostudyaspectssuchasthe distribution of framework and non-frarne- work aluminium atoms and their proper- ties, as well as the sites and surface struc- ture of ths cations in the zeolites.

(v) Several valuable catalysts were de- veloped, for instance molecular sieve cata- tysts for the synthesis of paradiethylben- zene and para-chbrotoluene, rare earth complex oxide catalysts for environmental protection uses (such as for the puriflca- tion and promotbn of combustion of auto mobile exhaust gases, and materials for hydrodewaxing of diil fuel).

In addition, domestic natural zeolites were also investigated and characterized.

Citation Classic - Catalysis by Metals

It is always a pleasure to see that a publication on catalysis has become a Ci- Won Classic, even more so when such a puhlicatbn is one on which one cut one’s teethandyetmoresowhentheauthorisa

applied catalysis - Volume 76 No. l-1 September 1961

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personal friend. Hence, the fact that Geoff Bonds book “Catalysis by Metals” has been featured as a Citation Classic in Cur- rent Contents, (Physical, Chemical and Earth Sciences and also Science and En- gineering, Vol. 31, No. 22, June 3,1991) for having been cited more than 1496 times is

particularly pleasing. In his commentary, Geoff sketches the problems invohred in writing such a book and the historical situ- ation in which it was written: “If I had tried five years earlier, there would not have been enough to say; fhre years later, there would have been too much’.

He then goes on to point out the need in such a book to write “plain but interesting English” (something which I have always admired in both his oral and written pres- entations) and ends, haying had a dig at those of us who use word processors, by exhorting the reader who has not yet writ- ten a book to try it - once.

JULIAN ROSS

Recent Patents and Publications

Role of Alkali Cations in Copper

Faujasites In a recent puMicedion in the Journal of

Physical Chemistry [96 (1991) 32621, J.-S. Yu and L. Kevan report the catalytic oxida- tion of propene over Cu” exchanged X and Y zeolites in the presence of other cations (M$+, Ca2’, Li+, Na+, K+, H+). Approxi- mately the same level of copper was ex- changed into X or Y zeolite and the role of the cation was studied. Dramatic diieren- ces in activity were recorded, with the al- kaline earth cations being the most active, white H+ and K+ were inactive. Y zeolites were slightly more effectiie than the X-type materials for the selective oxidation of propene to acrolein. The authors suggest

that acrdetn format&n is catalyzed by Cu’. The formation of acrolein exhibits a char- acteristic induction period which the auth- ors suggest is due to Cu” migration in the zeotiie lattice.

Metaibsiiicates of ZSM-5 Tjpe K. Yamagishi, S. Namba and T. Yashi-

ma [Bull. Chem. Sot. Jpn., 64 (1991) 9491 have described the preparation of indo-, gatlo- and aluminosilicates of ZSM-6 by introduction of the appropriate metal chlorides at elevated temperatures into de- fects of ZSM-5 (Si/AI ratio = 870). They were able to introduce at least 0.24 mmol/g of indium and higher amounts of the other metal salts without much change in sur- face area, but with a considerable increase in the number of acid sited per gram. The amount of metal in the bulk phase was 1.7 to 2.5 times as much as the number of acid sites, The relative order of acidity was in- dosilicate<gallosilicate~aluminosilicate.

Acid-6ase Properties of Modified

Aluminas This is the title of a recent paper by P.

Berteau, MA. Kellens and 8. Delmon, pub- lished in J. Chem. Sot. Faraday Trans., 87(9) (1991) 1426. The authors report the acidity and basicity of various modified aluminas which have been investigated by fiie methods: FT-IR spectroscopy of probe molecules (pyridine and CD&)); C02TPD, dehydration of 4-methyl-pentan- 2-01; and ammonia TPD. For these modi- fied y-aluminas, the authors report the fol- lowing relative acidity/basicity:

Na+ s Mg2+ < purer-AC03 < PO,* 5 CT < so,” < F-

increasing acidity -. c increasing bastcii

applied catalysis - Volume 76 No. 1 -1 September 1991