Vol. 12, No. 1, 2001

(continued, page 3)

Burt DavisUK Center for Applied Energy Research

Part II of a two part series.

In the 1970s, direct liquefaction of coal toproduce transportation fuels wasconsidered a certainty. The United Stateshad two major demonstration plants(200-600 tons coal/day) and two some-what smaller ones operating. Other largedemonstration plants were operating inseveral countries. Kentucky, with its largeproduction of coal, was to be the SaudiArabia of the Western nations. In 1980,petroleum was projected to cost morethan $100/barrel by the year 2000. Thus,the projected cost of petroleum wasgreater than even the most pessimisticestimate for the cost of production ofsynthetic fuels. With time the projectedprice of petroleum substitute declined buthas always been above the actual cost, at

least until the mid 1980s.During the past 15

years, the cost of

crude has varied but it has remained inthe $10-30/barrel range. The cost ofpetroleum had remained nearly constantfor so long that when it reached $10/barrel, and even lower, nearly all expertscould explain why crude would remainaround this price for several years.Within a year the price had exceeded $30/barrel and U.S. government officials werescrambling to find a “solution” to thiscrisis that resulted in gas pump pricesbecoming high enough to shock custom-ers into action.

Oil shale retorting was a commercialcertainty in the 1970s. Even Eastern U.S.shale, which required fluid-bed pyrolysis,was considered likely with U.S. andforeign companies scrambling to developlarge-track leases for the Kentuckyresources. The CAER progressed from a1 inch to a 2 inch to a larger 6 inch fluid-bed pilot plant. At the time of completionof the 6 inch plant, Exxon announcedthat they were abandoning the commer-cial development of oil shale. Federal andState support for this effort vanished.Today there are few options that areconsidered to be less likely than oil shale.Tar sands have made some in-roads anda commercial operation continues in

Canada; however, the economicviability of this depends on the

person that is talking.

Biomass conversion has beenpracticed at a small scale formany years. In 1980, onestudy projected that biomasswould provide almost 10%or the total energyconsumed in the U.S. bythe year 2000; anothermore optimistic studyexpected that 19% ofthe total energyconsumed in 2000would come frombiomass. At that time,the limitations of

ENERGY - Perception Versus Reality

EffectiveUtilization ofCoal-derivedPhenolicChemicalsChunshan Song and Harold H. SchobertThe Pennsylvania State University

INTRODUCTION

This article provides an overview forpotential utilization of coal-derivedphenolic compounds. Phenolic com-pounds are abundant in coal-derivedliquids. Coal-derived phenolic com-pounds include phenol, cresol, catechol,methylcatechol, naphthol, and theirderivatives. Liquids from coal liquefac-tion, pyrolysis, gasification, and carbon-ization are potential sources of phenolicchemicals, although certain processingand separation is needed. There areopportunities for coal-based phenolicchemicals, because industrial applicationsand potential new applications exist.Currently the petrochemical industryproduces phenol in multi-step processes.Selective methylation of phenol canproduce a precursor for aromaticengineering plastics. Catalytic oxidationof phenol has been commercializedrecently for catechol production. Thereare potential new uses of phenol thatcould replace large-volume multi-step

extensive development of biomassresources were considered to be its highland and water requirements and thecompetition with food production.However, the limitation was and contin-ues to be economic - the cost of produc-tion is greater than the value of the

(continued, page 2)

2

Energy - Perception Versus Reality, (cont.)

(continued, page 3)

energy produced - and the net energybalance. The latter point, net energybalance, is illustrated in Figure 12. Bothoptions are based on production ofpremium fuel by agriculture. In oneinstance corn is converted to fuel gradeethanol, and the net energy balance isnegative (-4.0%). A positive net energybalance results in this case only ifbiomass residue and coal are utilized inthe production of the premium fuel.Nevertheless, the U.S. has continued toproduce and utilize ethanol in itspremium transportation fuels, andthereby contributes to its energy short-age.

It has been estimated that in 1992, theproduction of chickens in the Southeast-ern U.S. produced 5 million tons of waste(J. A. Jones and A. C. Sheth, Proc.Renewable Adv. Energy system, 21st

Century, 1999, 78-90). In the past muchof this was used as fertilizer. Jones andSheth propose that this waste be gasifiedto produce energy. If this is done, whatimpact would it have on our energypicture? Assuming an optimistically highcarbon content of 40% and a 100%efficiency in gasification and conversionof the carbon to liquid fuels, the 5 milliontons of chicken waste could produce43,500 barrels/day transportation fuel.Since the U.S. consumes about 18 millionbarrels/day, this would provide 0.24% ofthe country’s consumption. A moreoptimistic approach has been proposed

by President Clinton. This wouldmandate that by 2010, 7.5% of U.S.electricity be produced using “renewableenergy resources.” The goal of this isobviously environmentally driven. Oneview of this action is that this is“...scarcely more realistic than mandat-ing ‘repeal’ of a law of physics...”(M.McCormack, C&E News, Sept. 13, 1999,p. 3) to the view that “All it would taketo stimulate the generation of 7.5% ofour electricity and more from renewablesources is a crude oil price that remainsabove $25 per barrel.”(D. L. Klass,President, Biomass Energy Research,C&E News, Nov. 15, 1999, p. 6).Unfortunately, many of these wellmeaning laws end up having a resultthat is contradictory to what wasintended. For example, as a result of theOPEC-created crisis in the 1970s,congress created a “synfuels bill” thatwas to provide a $25/ton tax write-off foreach ton of coal recovered from holdingponds and similar sources. However,with time the effort has changed so thattoday synfuels are generated by adding2-3% petroleum product to newly minedcoal, and then selling the synfuel for lessthan the real market value of newlymined coal. In short, it is difficult toprovide a subsidy that is not easilycircumvented.

U.S. refineries are being shed by themajor oil companies because the marginfor refining is far too low to satisfy Wall

Street’s expectations. Today, refineriesoperate at 95+% capacity. Unless someaction is taken that leads to increasedrefinery capacity or to importation offinished products rather than crude,the U.S. will continue to face higherprices based on real shortages ofrefined products. The nation’s lastenergy policy was formulated duringPresident Carter’s years and, intention-ally or otherwise, petroleum companieshave worked for 20 years to undo it.Petroleum companies are merging andshedding their refineries to becomedownstream marketers of high-profitproducts. At the present trend, the U.S.shall return soon to the 1880’s whenJohn D. Rockefellor’s Standard Oilwas the only petroleum company.

Based on historical reality, there is noreason to be upset about today’s pumpprice for transportation fuel. Thechange in supply is completely inad-equate to cause a price change at thepump of 50%, either as an increase or adecrease. However, both have occurredduring the past three years. Humannature dictates that one does notcomplain when the change is in one’sfavor, – but to complain loudly whenthe change goes against one. A histori-cal view allows us to conclude that theprice fluctuations during the past fiveyears have been perception based.

Will the future be based on perceptionor reality? One thing seems certain: theU.S. does not have an energy policy andthere is little reason to believe that onewill be developed during the short-term. Today, the U.S. Department ofEnergy (DOE) is responsible fordeveloping a policy; however, thelegislative and executive branches seemto be more concerned with eliminatingrather than working with that depart-ment. This has led to DOE lookingmore and more at short-term actions.Petroleum producers and refiners whoused to consider short-term to be amatter of years, now look no furtherthan the next quarter’s profit. Compa-nies, either because of perception orreality, feel compelled to meet theexpectations of Wall Street and to showever expanding profits. In this setting,companies cannot develop long-termplans, let alone help formulate long-term energy policies. During the past 30years, at least, the U.S. energy policyhas been one of benign neglect thatreacts only to sudden changes, andonly if viewed negatively by the public,with actions that provide the percep-tion of action.

Figure 12. Flows in energy units (Applied Catalysis).

(A)

(B)

(A) Conventional use of premium fuels forprocess and agriculture.

(B) Premium fuel use restricted to farmingmachinery.

3

(continued, page 4)

The shock caused by the petroleumshortfall of the 1970s aroused the publicto the extent that the U.S. developed anenergy policy. Unfortunately, it wasproduced over a short period and wasbased on limited data that was extrapo-lated far beyond the region where it wasvalid. An examination of the literatureindicates that for about three years (1972-1975) the effort of scientists and engineerswas to “relearn” the work that had beendone during the previous crisis. Withvery limited data, the decision to buildlarge demonstration plants was madeand there was an “expensive crashprogram” to get the plants built andrunning. At the same time, funds weremade available to assist with commercialplants. The Reagan administrationrapidly shut-down this activity when itassumed office. In the relaxed atmo-sphere of the 1980s, any thoughts ofdeveloping a real energy policy for theU.S. were forgotten, and this attitude

chemical processes that are based onbenzene as the starting material. Newchemical research on coal and coal-derived liquids can pave the way for theirnon-fuel uses for making chemicals andmaterials.

PHENOLIC COMPOUNDSFROM PETROLEUM ANDCOAL

Phenol is one of the major industrialorganic chemicals, and ranked among thetop twenty in the U.S. (by the amountproduced). Table 1 shows the develop-ment of phenol production in the U.S.,Western Europe, and Japan from 1985to1995. It is currently produced mainlyfrom a multi-step process starting frombenzene, as described below. Benzene isseparated from BTX fraction extractedfrom catalytically reformed naphtha orpyrolysis gasoline. The purified benzeneis converted to cumene(isopropylbenzene) by catalyticisopropylation over an acidic catalyst.Subsequently, cumene is converted tocumene hydroperoxide, which produces

Energy - Perception Versus Reality, (cont.) Effective Utilization (cont.)

remains today. Any attention to an energypolicy is driven by environmentalconcerns and with making larger andlarger suburban recreational vehicles thatutilize more and more fuel for each milethat is traveled. Some countries doappear to be trying to formulate anenergy policy but, unfortunately, many ofthese appear to be based more onidealized environmental considerationsthan on workable energy efficiencyconsiderations. Hopefully, the U.S. willnot let the current jump in petroleumprices pass without beginning the processof developing a rational energy policy.

Dr. Davis has long worked in the energyarena. He has been at the CAER since1977 and currently serves as interimdirector. He may be contacted atdavis@caer.uky.edu.

4

Effective Utilization, (cont.)

phenol and acetone upon acid-catalyzedcleavage. Until 1990 about 97 % of the totalsynthetic phenol in the U.S., over90 % in Western Europe, and 100 % inJapan was manufactured by this process.The world capacity for phenol using thecumene process is currently about fivemillion tons per year. In 1990-1991 a newprocess based on toluene was introduced,and this route is now used for about 91 %of phenol production in Western Europe.Phenol is still the largest-volume chemicalderived from benzene, and its productioncurrently consumes about 20 % of the totalbenzene production. In addition tosynthesis, phenol is also produced insmaller quantities from tar and coke-ovenwater from coal coking and low tempera-ture carbonization of low-rank coals.Phenols, cresols and xylenols can berecovered by washing coal-derived liquidwith alkaline solutions and treating the acidsolution with CO

2.

By carefully designing the reactions, we canconvert coals into liquids that are rich inaromatic and phenolic compounds, whichare valuable chemical feedstocks. Phenolcan be directly separated from liquidsproduced from coals through pyrolysis,carbonization, hydropyrolysis or liquefac-tion. It has been shown that phenoliccompounds are dominant components inthe products from pyrolysis of low-rankcoals, as demonstrated by flash pyrolysis-GC-MS of several subbituminous coals.Analysis of products from coal liquefactionalso indicated this trend. Phenols can beextracted from coal-derived liquids bytraditional or non-traditional methods.

Table 1. Phenol production in the U.S.,Western Europe and Japan (in metric tons).

YRTNUOC LONEHPECRUOS 5891 1991 5991

SU lonehpcitehtnyS 0621 3551 3781

dnaratmorFretawetsaw 42 72 72

latoT 4821 0851 0091

eporuEnretseW lonehpcitehtnyS 7511 0641 3941

dnaratmorFretawetsaw 41 82 41

latoT

napaJ lonehpcitehtnyS 552 865 177

dnaratmorFretawetsaw 2 2 a/N

latoT 752 075 177

TCUDORP DLROW SU NAPAJ NRETSEWEPORUE

9891 5991 5891 5991 6891 4991 5891 4991

)snotnoillim(latoT 07.4 32.5 70.1 97.1 52.0 05.0 50.1 52.1

)%(ntsiD

sniserlonehP 63 73 04 03 63 33 14 92

matcalorpaC 7 51 81 71 71 61

AlonehpsiB 02 23 22 53 92 93 22 72

dicacipidA 1 2 1 1 1 2

slonehplyklA 5 2 4 6 4 4 4 6

suoenallecsiM )1( 12 21 51 11 62 42 42 02

Table 2. Industrial Uses of Phenol in the World, US,Western Europe and Japan (in 1000 metric tons).

(1) e.g., aniline, chlorophenols, plasticizers, antioxidants. Sources: (a) Weissermel, K. andH.-J. Arpe, 1997; (b) C&EN, Facts & Figures, June 24, 1996.

form a mixture of cyclohexanol andcyclohexanone. Cyclohexnol in the mixtureis isolated and then dehydrogenated toproduce cyclohexanone. Cyclohexane isproduced from benzene hydrogenation. Asecond route to cyclohexanone is throughphenol hydrogenation. In 1990 about 63 %of the worldwide caprolactam productionwas based on cyclohexane oxidation andthe remainder came from the phenolhydrogenation route and other routes.

An earlier phenol route involves a two-stepprocess, ring hydrogenation tocyclohexanol over a nickel catalyst andthen dehydrogenation over a Zn or Cucatalyst to cyclohexanone. Some of thecatalysts developed for commercialoperation of cyclohexanol dehydrogenationto cyclohexanone are Cu/MgO and Cu/ZnO catalysts containing alkali promoter.However, recent research using some noblemetal-based catalysts has made it possibleto convert phenol to cyclohexanone in onestep. For example, some recent results bySrinivas Srimat in our laboratory showthat high selectivity to cyclohexanone canbe obtained in a single step under theconditions of phenol hydrogenation oversupported noble-metal catalysts modifiedin specific ways.

Cresols and xylenols can be obtainedfrom coal liquids or from methylation ofphenol. The demand for o-cresol and 2,6-xylenol has increased recently, so that thedemand can no longer be met solely frompetroleum and coal tar sources. o-Cresolis favored in methylation of phenol at

Sources: (a) Weissermel, K. and H.-J. Arpe, 1997; (b) C&EN, Facts & Figures,June 24, 1996.

(continued, page 5)

They can be separated directlyfrom the coal liquids by liquid-phase extraction, and can be usedas-is or converted into monomerssuch as bisphenol A and 2,6-dimethylphenol for makingaromatic polymers and engineer-ing plastics.

One could argue that the marketof phenol is relatively small and ifthere is one large commercial plantfor coal liquefaction, the phenolfrom such a plant could saturatethe current market. The pessimis-tic view may take this consider-ation as a stop sign for furtherprogress in phenol utilization.However, proactive measures canopen up new opportunities andnew applications. If phenol can beproduced in larger quantities,other applications of phenol maybecome attractive in addition to itscurrent uses, which may alsobecome competitive to some otherindustrial manufacturing pro-

cesses that currently do not use phenol.

INDUSTRIAL USES OFPHENOL

Table 2 shows the world-wide industrial uses ofphenol. The currentindustrial uses of phenolinclude the production ofphenolic resins (Bakelite,Novolacs), bisphenol A,caprolactam, alkylphenols,and adipic acid, as well assome other uses, as shownin Table 2. Bisphenol A,also known as 2,2-bis-(4-hydroxyphenyl)propeneproduced from condensa-tion of phenol and acetone,is widely used in themanufacture of syntheticresins and thermoplastics,such as polycarbonates(Figure 1).

For example, caprolactam isan important industrialorganic chemical, with aworldwide productioncapacity of 3.44 million tonsin 1989 (with 0.96, 0.60,and 0.51 million tons peryear in Western Europe, U.S., and Japan,respectively). It is used for the manufac-ture of Nylon 6. It is synthesized alsofrom a multi-step process with cyclohex-anone as the key intermediate. Mostcyclohexanone is made from cyclohexane,produced from cyclohexane oxidation to

5

300-360 °C under 40-70 bar over analumina catalyst; at higher tempera-tures and pressures, 2,6-xylenol isfavored. 2,6-Xylenol is the startingmaterial for polyphenylene oxide(Figure 2), a thermoplastic developedby General Electric, which has highheat and chemical resistance andexcellent electrical properties.

One option in the coal chemicalscommunity may be to wait and let

others take the first step (and also therisk). However, the result may be afurther shift in market away fromcoal-based chemicals. For example,while some researchers on coalchemicals still think the market forphenol is too small for coal-basedchemicals, several new processes havebeen developed in petrochemicals andchemical industries. As a result, anearlier cumene process using Lewisacidic AlCl

3 catalyst was replaced by

new processes using a solid acidcatalyst such as Al

2O

3-supported

phosphoric acid. A recent developmentin the 1990s is another new cumeneprocess commercialized by DowChemical Company, which useschemically modified mordenite as acatalyst for benzene isopropylation.Most recently, a new type of processbased on direct oxidation of benzenewith nitrogen oxide to produce phenolover molecular sieve catalyst was

developed and is being commercialized bySolutia Co.

Catechol is a useful industrial chemical, andcan be synthesized from hydroxylation ofphenol. Notari and coworkers have developeda new process for hydroxylation of phenol toproduce catechol over microporous crystallinetitanium silicates catalysts. Such a reaction canalso be promoted by other catalysts such as V-Zr-O complex oxide. On the other hand,catechol is present in relatively high concentra-

tions in liquids derived frompyrolysis of low-rank coals. Somecatechol derivatives are valuablechemicals. For example, veratrole(ortho-dimethoxybenzene) is animportant chemical for the produc-tion of alkaloids and pharmaceuti-cals. Veratrole can be synthesized inthe vapor phase using catechol anddimethyl carbonate over aluminaloaded with potassium nitrate.

POSSIBLE NEW USES OFPHENOL

New Oxygenates for Gasoline. One possible useis to make oxygenated compounds as analternative to current fuel additives such asmethyl-tert-butyl ether (MTBE). The use ofMTBE for reformulated gasoline is underincreasing pressure from environmentalists forits possible health and environmental effects.As an alternative, methylcyclohexyl ether(MCHE) may be a potential oxygenateadditive for liquid fuels. Phenol can behydrogenated to cyclohexanol and its conden-sation reaction with methanol can producemethylcyclohexyl ether (MCHE). Phenol canbe selectively hydrogenated into cyclohexanolover certain catalysts. Methanol is a larger-volume commodity chemical, and can also beobtained from coal gasification followed bysynthesis from syngas over Cu-Zn typecatalysts.

New Environmentally-Benign Manufacturing.

Potential new markets for phenol,including coal-derived phenols, can bedeveloped by exploring more environmen-tally benign syntheses that use phenol,which can replace existing routes thatinvolve more corrosive acids or toxicagents. Several examples are given below.

The phosgene-free synthesis of organiccarbonate is an important research areabecause phosgene currently used formaking some industrial organic chemicalsis toxic. Diphenyl carbonate is an essentialstarting material for phosgene-freesynthesis of an important engineeringplastic material, polycarbonate resin, asshown in Figure 1. Direct synthesis ofdiphenyl carbonate can be carried outusing phenol. For example, oxidativecarbonylation of phenol can be carriedout using carbon monoxide and air over aPd-Cu based catalyst to produce diphenylcarbonate.

Aniline is an important industrial organicchemical. In 1993 the production ofaniline was 537, 508, and 184 thousandtons in the Western Europe, US, andJapan, respectively. Aniline is currentlysynthesized by a multi-step process:nitration of benzene, followed by hydro-genation of nitrobenzene. Direct synthesisof aniline from phenol and ammonia canbe carried out using MFI-type molecularsieve catalysts. For example, gallium-containing an MFI type catalyst has beenfound to be effective for the anilinesynthesis from phenol.

SUMMARY

Utilization of phenol will be an importantpart of non-fuel uses of coal and coal-derived liquids in the future. Currentroutes of industrial uses of phenol includethe production of phenolic resins,bisphenol A, caprolactam, alkylphenols,adipic acid, antioxidants, aniline,plasticizers, and chlorophenols. Thedemand for phenol has increasedsignificantly in the past two decades andthis trend is expected to continue. Thereare existing and new opportunities fordeveloping and using phenol and phenolderivatives in chemical process industries.

Drs. Song and Schobert lead an activeresearch group on clean fuels, chemicalsand catalysis research in the EnergyInstitute, and they are faculty members inthe Department of Energy & Geo-Environ-mental Engineering, The PennsylvaniaState University. Dr. Song may be reachedat: csong@psu.edu.

Effective Utilization, (cont.)

Figure 1. Synthesis of polycarbonate by phosgene-freeroute via trans-esterification of bisphenol A

with diphenyl carbonate.

Figure 2. Synthesis of polyphenyleneoxide via methylation of phenol,and condensation of 2,6-xylenol.

6

Energeia is published six times a year by the University of Kentucky's Center for Applied Energy Research (CAER). The publication features aspects of energy resourcedevelopment and environmentally related topics. Subscriptions are free and may be requested as follows: Marybeth McAlister, Editor of Energeia, CAER, 2540 ResearchPark Drive, University of Kentucky, Lexington, KY 40511-8410, (859) 257-0224, FAX: (859)-257-0220, e-mail: mcalister@caer.uky.edu. Current and recent past issuesof Energeia may be viewed on the CAER Web Page at www.caer.uky.edu. Copyright © 2001, University of Kentucky.

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trial chemistry, chemical engineering, plant operations, andresearch and development. He served as managing directorof the internationally recognized Sastech Research andDevelopment Division of Sasol for 10 years. Sasol, one of thebiggest coal producers in the world and leader in coalconversion, processing and utilization technologies, processesmore than 40 percent of South Africa’s liquid fuel require-ments.

Geertsema received a Ph.D. in chemical engineering from theUniversity of Karlsruhe in Germany in 1976 and an M.B.A.from the University of Potchefstroom in South Africa.

His recent professional awards include the 1994 IndustrialChemistry Medal from the South African Institute ofChemistry for promoting industrial chemistry and univer-sity-industry interactions and the 1993 Stokes Award fromthe International Pittsburgh Coal Conference for leadershipin commercialization of coal conversion technologies.

Geertsema will also hold an associate professor position inthe UK College of Engineering Department of Chemical andMaterials Engineering.

ANNOUNCING APPOINTMENT OF NEWCAER DIRECTORArie Geertsema was recentlyapproved by the University ofKentucky Board of Trustees asthe new director of the Center forApplied Energy Research.

“The university is gratified tohave such an internationallyrecognized fuel scientist andindustrialist as the new leader ofUK’s Center for Applied EnergyResearch and as a faculty memberof the College of Engineering,”

said Fitzgerald B. Bramwell, vice president for Research andGraduate Studies. “Dr. Geertsema’s expertise will position CAERand UK to respond aggressively to the research needs of achanging and dynamic industry for both the producers and usersof Kentucky coal.”

Geertsema, who most recently served as gas processing managerat the Commonwealth Science and Industrial Research Organiza-tion in Australia, has more than 30 years of experience in indus-