Petroleum Supplements 1. C. KEMP, JR. 135 E m f 42nd Sf., New York, N. Y.
H. V. ATWELL The Texas Co., Beacon,
Various known methods o f making high quality synthetic fuels are being constantly improved and will be available
N. Y.
for commercial use when they can be justified economically. Recovering oil from shale still involves problems o f lowering mining costs, improving the design of retorts, and finding better refining processes. The direct hydrogenation of coal needs better primary stage catalysts, cheaper sources of hydrogen, and methods for more selective conversion. Problems of materials of construction and materials han-
dling are involved in perfecting the gasification of raw powdered coal under pressure for the Fischer-Tropsch process. New techniques for converting synthesis gas to oil with iron catalysts promise much cheaper operation and higher quality products than realized previously. Some liquid fuel may be obtained b y hydrogenating tar from powdered coal carbonization processes now being developed. Oil recoverable from bituminous sands presents refining problems similar to those associated with shale oil.
OR a great many years the petroleum industry has been well aware of the fact that its raw materials will eventually be exhausted. On several occasions the threat of declining petroleum reserves has seemed quite serious, but fortunately each of these periods of alarm has been followed by the discovery of new oil fields which has deferred the probable date of exhaustion. Today, the proved reserves of petroleum and natural gas in the United States are higher than ever and we can be reasonably confident that these reserves will also be augmented by the discovery of new fields and by the upward revision of the estimates of reserves in old fields. To estimate accurately the extent of these reserves and to predict their life is a major problem for which a solution is not likely to be found. However, the latest and most careful study of this problem by a committee of the National Petroleum Council (14) has lead to the conclusion that available petroleum supplies in the United States will continue to increase and will probably be adequate for the foreseeable future. This conclusion takes into consideration the fact that the consumption of petroleum products is increasing steadily, with no indication of a reversal in this trend. Although the prospects for the immediate future are encouraging, it must be recognized that actual reserves of petroleum are finite and will eventually be exhausted. The rate of production must pass through a maximum which some experts feel will occur within the next 10 years (S). Even if the day of declining production is much farther away, there can be no doubt that the cost of production will show a general trend upward. The major factors in this cost trend will be the exploitation of relatively deep producing formations and offshore drilling. This inevitable rise in the cost of recovering petroleum will eventually make it economical to produce liquid fuels by synthetic means. While rising prices will make fuel synthesis profitable, they will also tend to encourage more efficient use of all liquid fuels and cause some replacement of liquid fuels by coal. These changes will not come suddenly and there is no reason why they should be influenced by other than normal economic and technological considerations. Improved Gasoline Economy. Both the petroleum and automotive industries have contributed greatly to the more efficient use of motor gasoline, which is the principal product with which this paper is concerned. However, this has not yet greatly affected the extravagance of the average motorist who desires an automobile weighing nearly 2 tons, powered by an engine of a t least 100 hp., and frequently for the transportation of only one passenger. The American needs only a short visit to European countries to realize how much motor fuel might be saved if
American motorists would be satisfied with the light, economical cars which are the rule rather than the exception there. Duiing the postwar years certain foreign trade circumstances have lead to the marketing of many of these light cars in the United States and their advantages are being discovered by experience. Unless bome miracle can reverse the rising trend of fuel costs and taxes, it seems reasonable t o expect that the extensive use of light and economical cars will eventually become a reality in this country, with a substantial effect on the consumption of motor fuel. Substitution of Coal for Fuel Oil. Another shift in the pattern of consumption which will probably result from rising petroleum prices is the substitution of coal for heavy fuel oil. The relatively great extent of the coal reserves of this countrv would suggest that the mining and use of coal tvould be greatly stimulated by a rather slight rise in the price of competitive fuels. However, it must be recognized that the cost of producing coal from new mines, even with complete mechanization and large scale operations, will be relatively high because of the large capital charges involved and the fact that the output per man-shift is subject to human factors which may impose limits other than those associated with mechanization. Since transportation costs are always a considerable factor in the price of coal a t points of largescale use, recent developments in pipeline transportation of coal in water suspension may prove to be very important in making coal more competitive with fuel oil. Synthetic Fuels. Fortunately, the problems associated with the increased production of coal a t the lowest possible price nced not be solved bv the petroleum industry, but they will certainly have an important bearing on the relative demand for liquid and solid fuels and hence on the urgency of a synthetic liquid furl industry. The liquid fuels which are expected to gradually replace those now recovered from petroleum are commonly designated synthetic fuels, although synthesis in the chemical sense may be involved only t o a limited degree in their production. However, the term “synthetic fuels” is generally understood and no longer conveys the impression of substitute materials of inferior quality. Synthetic fuels will be produced to the Same high standaids which apply to petroleum products. The problem of establishing a synthetic fuel industry to supplement declining supplies of petroleum resolves itself into questions of when, where, and by whom, with the question of how being a relatively minor matter. Technically speaking, methods for making replacement fuels are well developed and some such processes have been used commercially for many years in foreign countries where petroleum has been relatively scarce and costly. These processes can be improved in many
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respects, but the fact remains that they could be used in this country today, if necessary. Which of the available processes is most economical and when a n y of them can be established profitably is a subject of considerable disagreement. The nature and extent of the natural resources which the nation can draw upon for the synthesis of petroleum replacements is shown by Table I, compiled by Ayres and Scarlott (g). Petroteum, even by the most optimistic estimates, is a minor resource compared to coal. Oil from coal is obviously the ultimate goal but economic studies indicate that oil from shale may be most profitable initially (16).
IA’
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shale exploitation. The assoriated problem of stream pollution is potentially serious, although present indications are that objectionable pollution can be avoided. The rugged country in which shale deposits occur is advantageous in providing apparently adequate dumping grounds for spent shale. If it were necessary to build mountains of spent shale as in Scotland and Europe, the scale of operations contemplated in this country would involve a very serious spent shale handling cost. In respect t o this as well as mining and retorting procedures, the American shale oil industry will be considerably different from that of Europe. Coal Conversion by Gas Syntheses
Table I.
Estimated Ultimate Reserves of Energy from All Fossil-Fuel Deposits o f the United States Energy, Hp.-Hr. X 1014 Min.
Max. Coal Petroleum (liquid) Natural gas Oil shale Peat Total
Oil from Shale Oil shale is a sedimentary rock containing organic matter called kerogen which can be decomposed a t temperatures of about 900” F. to yield crude oil of rather poor quality. The oil shale deposits of Colorado and Utah include a bed of shale known as the mahogany ledge, which will yield roughly 30 gallons of oil per ton. The extent of this particular bed is sufficient t o yield a total of a t least 100 billion barrels of oil. The leaner deposits in the Colorado-Utah area would increase the potential shale oil reserve to about 400 billion barrels. However, this increment attributed t o the leaner formations would be more costly to recover than the oil from the richer beds which will undoubtedly be exploited first. Excellent work by the U. S. Bureau of Mines a t Rifle, Colo., has demonstrated the possibility of mining oil shale at a cost of about 55 cents per ton. Work is continuing to perfect still cheaper methods of drilling, blasting, and handling shale in the mine. Perhaps the greatest remaining problem in this phase of the shale oil operation is one of human relations, which may be more difficult to solve. Specifically, assurance is needed that shale mining on a commercial basis can be sustained at rates and costs per man-shift, which have been demonstrated at Rifle. Considerable progress has been made by the Bureau of Mines in cooperation with the Union Oil Co. in developing retorts for oil shale, but additional problems may be encountered in perfecting the most economical retort for handling extremely large quantities involved in commercial operation. Whatever the retorting method, it seems inevitable that the quality of the crude shale oil will be relatively poor because of the presence of comparatively large amounts of sulfur, oxygen, and nitrogen compounds. Hydrogenation appears to be the only completely satisfactory method of refining such oil and this is an inherently expensive process. The problem of improving the technology and economics of this step is a real challenge. There is a reasonable degree of confidence but no absolute certainty among th’e experts regarding solution of certain other problems of the potential shale oil industry. Perhaps first and foremost is whether the very favorable rock structure encountered in the experimental mine a t Rifle will prevail through a large percentage of the shale bed which must eventually be exploited. The low cost of mining demonstrated at Rifle can be realized only to the extent that it is possible to operate in large rooms with unsupported roofs. Another problem peculiar t o the location of larger shale deposits is the relative scarcity of water. This may or may not prove t o be a limitation on the rate of oil July 1953
T o solve the problem of converting coal to oil naturally the two different processes which have been used commercially in Germany are considered. The so-called Fischer-Tropsch process involves the conversion of coal to a mixture of carbon monoxide and hydrogen which can be further reacted over cobalt or iron catalysts to make a nonaromatic oil of wide boiling range. The so-called Bergius process involves the direct hydrogenation of coal under pressure. This is usually accomplished in several stages-the first stage making a gas oil from a suspension of coal in liquid oil and the subsequent stages operating on the primary gas oil in the vapor phase to make highly aromatic gasoline. Complete details of these German processes have been obtained by numerous investigators both before and after World War I1 (13). The American version of the Fischer-Tropsch process, as a result of very extensive research since the war, will be substantially different from, and much superior to, the German process ( l a ) . This general method of procedure is designated in this country as gas synthesis or sometimes “hycosynthesis” which indicates the use of hydrogen-carbon monoxide mixtures as charge gas for the synthesis step. The cost of synthesis gas is a major item in the production of liquid fuels by hycosynthesis. It is generally believed that the synthesis step itself should be conducted at a pressure of a few hundred pounds and that it will be most economical to generate the synthesis gas a t a slightly higher pressure instead of generating a t atmospheric pressure and compressing. Since coal gasification is, unavoidably, a high temperature reaction, its conduct at high pressure requires internal heating, and for this purpose relatively pure oxygen rather than air must be used in order to avoid excessive dilution of the synthesis gas with nitrogen. Along this line, American investigators have departed further from German commercial practice by using powdered raw coal instead of lump coal or coke and by operating a t such high temperatures that the ash can be handled in the molten state. Although pilot plant work by various organizations has shown great promise for this method of making synthesis gas (8, 9, 10, 1 6 , 1 7 ) , there are certainly a number of problems t o be solved, particularly to perfect the process for prolonged operation on a large scale. I n common with the similar production of synthesis gas from natural gas, this process involves the characteristics of partial combustion with pure oxygen under high pressure. I n this connection there are many possibilities for fundamental research which will contribute greatly to the success of commercial processing. The synthesis step itseIf has been greatly improved in this country b y the development of cheap iron catalysts capable of making high yields of high antiknock gasoline (6). The application of the fluidized catalyst technique to hycosynthesis has been particularly effective to this end. However, catalyst costs which now seem sufficiently low must eventually be scrutinized and undoubtedly means will be found t o increase catalyst activity and selectivity and to prolong catalyst life. There is also a possibility of discovering catalysts which will give economical conversion at lower pressure than now seems desirable, thus saving compression costs.
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On the basis of research conducted mainly in Germany, it is well known t h a t the Fischer-Tropsch synthesis using iron catalyst can be made to yield very large quantities of oxygenated compounds. Even the small quantities of such chemicals which are produced incidental to gasoline synthesis can be regarded as valuable by-products having some influence on the economic attractiveness of the process. However, if the objective is t o make synthetic fuels it seems desirable to keep chemical byproducts a t a minimum, which is quite easy with hycosynthesis in contrast t o the situation with direct coal hydrogenation.
liquid Fuel from Natural Gas From the long range point of view, natural gas cannot be regarded as a raw material for synthetic liquid fuel since the proved reserves of natural gas and crude oil are of the same order of magnitude in terms of years supply. However, local circunistances a few years ago made it economically attractive for Carthage Hydrocol, Inc., t o erect a commercial plant for converting natural gas to gasoline a t Brownsville, Tex. I n this plant natural gas is burned noncatalytically with a limited quantity of high purity oxygen under high pressure to make synthesis gas, and this gas is converted to liquids by a fluidized iron catalyst. The operation of this plant has been plagued with many difficulties, chiefly mechanical, but these are gradually being overcome. The experience gained at Brownville will be extremely valuable in the design and operation of any additional plants which may be built to operate on natural gas and in connection with the ultimate use of coal instead of natural gas as a raw material for the same type of synthesis. The Brownsville plant includes two of the largest oxygen units ever built, each having a capacity of 1000 tons per day, and similar units would be needed for the gasification of coal. The performance of the fluidized catalyst for synthesis is generally independent of the raw material from which the synthesis gas is made. Valuable practical knowledge of the recovery of chemical by-products is being gained in the Stanolind plant associated with the Carthage Hydrocol plant and this information can be applied to the products from coal as well as from natural gas. -4possible problem in the transition from natural gas to coal as raw material for hycosynthesis may arise from the fact that natural gas yields readily a synthesis gas in which the volumetric ratio of hydrogen to carbon monoxide is nearly 2, while from coal it nil1 be somewhat cheaper to make gas containing a high proportion of carbon monoxide. I n the synthesis reaction this higher carbon monoxide content tends to give more carbon deposition and presumably faster catalyst deterioration, but i t is yet to be determined how serious these tendencies are on a commercial scale or how they can be counteracted most effectively. It is believed that the gas-fluidized catalyst can be used with this type of synthesis gas. An alternative which has been studied extensively by the U. S. Bureau of Mines is the submerged catalyst or liquid fluidized system. While avoiding the carbon deposition problem to a considerable degree by operating a t lower temperatures, this system does not achieve such high conversions per pass as the gas-fluidized catalyst. At the same time it makes a relatively high boiling primary product with a correspondingly lower yield of methane, which may be an advantage if synthetic Diesel fuel is desired. Other useful characteristics of the submerged catalyst system will probably be discovered as it is investigated further. The production of synthesis gas from coal will introduce the problem of desulfurizing the gas, which fortunately has been of no concern a t Brownsville. Although processes capable of accomplishing such desulfurizing are well known it seems likely that they will eventually be simplified and cheapened. A step in this direction has been announced by the Lurgi Co. of Germany ( 1 1, and it is understood t h a t this process will be used in a commercial synthesis plant in South Africa. The high temperature oxygen combustion process for gasifying powdered coal converts almost 1438
all of the sulfur to hydrogen sulfide, which greatly simplifies the gas purification problem. The problem might be avoided entirely if a sulfactive synthesis catalyst could be discovered. I n appraising the prospects for a synthetic fuel industry, some consideration must be given t o the tremendous growth of the domestic market for natural gas which has resulted from the postwar construction of natural gas transmission lines. A large part of the demand thus created for high B.t.u. gas must be met with similar gas from other sources when supplies of natural gas decline. It is important to keep in mind that the demand for natural gas substitutes will probably grow simultaneously with the demand for synthetic liquid fuels if the conclusion is corrcct that the reserves of natural gas and petroleum are of the same order of magnitude. I n this situation, gas from coal seems to be the logical replacement. Technically, it is even now possible to convert raw coal to carbon monoxide and hydrogen and t o convert this synthesis gas almost quantitatively to methane ( 1 ). However, such processes, like the other synthetic fuel processes, are not economically attractive today and it seems unlikely that technical improvements will make them attractive until the price of natural gas is considerably higher than it is now. Such improvements will certainly come, probably along the line of producing simultaneously high B.t.u. gas and liquid Eucls. with considerable flexibility in the ratios of production.
Direct Hydrogenation of Coal Direct hydrogenation of coal, the major alternative t o conversion by gasification and synthesis, would still be essentially the same as the German Bergius process, although improved in some details as a result of extensive research and development by the U.S.Bureau of Ilines. I t s principal characteristics are operation a t temperatures of about 900' F. and pressures of 400 to '100 atmospheres, which require relatively expensive equipment and procedures. hfechanical problems are particularly severe in the first or liquid phase stage where heavy oil suspensions of abrasive solids must be handled under these extreme conditions. Maintenance costs will undoubtedly be high, but it is to be hoped that they can be kept below those experienced in Germany, where a normal figure was stated to be 5.2% per year on the total investment ( 1 1 ) . The liquefaction of raw coal by hydrogen is, unfortunately, a relatively slow reaction and the problem of finding a practical catalyst has been studied exhaustively. The processing of a suspension of solid material in a very heavy oil in the liquid phase is not the sort of situation in which catalysis can be expected to function very efficiently. The recovery of a catalyst from the asphalt-ash residue of such a process would be difficult. The basic problem here is to find a catalyst which will have much greater activity under very unfavorable conditions. Furthermore, the catalyst must be so cheap that it need not be recovered, or new and suitably cheap recovery processes must be developed. Although the investigators both in this country and abroad who have been concerned mainly with the production of liquid fuels have still not succeeded in attaining high rates of conversion in the primary hydrogenation step, a partial solution of the problem appears to have been achieved by the Carbide and Carbon Chemicals Corp. I n the course of their study of coal hydrogenation for the production of chemicals ( 7 ) , this 'company claims to have discovered operating conditions which reduce the residence time in the primary convertor from about 1 hour to something less than 5 minutes while accomplishing conversion of all of the carbonaceous components of the coal except the refractory fusain. Although this achievement may be applicable t o processing for liquid fuels, the Carbide and Carbon process is limited to a single stage of hydrogenation to make a wide range of aromatic chemicals with practically no gasoline. The plant of this character which is now operating a t Institute, W. Va., is expected to handle,
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ultimately, 600 tons of coal per day and it is believed that similar units of about 3000 tons daily capacity will be most economical for commercial operation. It seems probable t h a t plants of this character will be the most profitable method of meeting growing demands for aromatic chemicals from coal and t h a t adequate productive capacity can easily be provided by such plants witho u t reliance on by-products from the production of liquid fuels. From the chemical point of view, direct hydrogenation of coal is handicapped by the use of an expensive reagent, high pressure gaseous hydrogen. It is hoped that some reduction in the cost 'of hydrogen will result from development work now in progress on the production of synthesis gas from raw coal. It seems unavoidable t h a t much of this expensive hydrogen will be consumed in yielding relatively low value by-products such as water, hydrogen sulfide, and normally gaseous hydrocarbons. The latter are entirely paraffinic and therefore cannot be converted directly t o motor fuel by catalytic polymerization as is possible with the predominately olefinic CI and Ca hydrocarbons produced by the Fischer-Tropsch reaction. Even the production of liquid hydrocarbons from coal is not so clean-cut as might be desired since phenolic compounds and high boiling aromatic compounds are formed to a considerable extent and are not directly usable as liquid fuels. To what extent the by-product value of these compounds can be counted on t o lower the cost of the desired synthetic fuel is the subject of sharp disagreement among the experts. However, there can be little doubt that the credit for chemical by-products will become a progressively less favorable factor as the scale of coal hydrogenation operations is increased to meet even a small fraction of the nation's liquid fuel requirements.
Coal Carbonization N
2
The low temperature carbonization of coal is not generally considered a solution of the synthetic fuel problem. However, recent developments indicate that i t may play a considerable role in combination with electric power generation. Carbonization of powdered coal or lignite in the fluidized or entrained state shows promise of yielding a residual char which can be used with high efficiency for power generation, thereby taking the place of fuel oil or natural gas. At the same time the carbonization t a r can be hydrogenated t o liquid fuels by procedures which have been used commercially in other countries and which would be less costly than the hydrogenation of raw coal. Although the attractiveness of carbonization appears to be related to, and perhaps limited by, the possibility of using char for power generation, the alternative of using such char for the production of synthesis gas should not be overlooked. I n any event, the basic problem seems to be the perfection of the powdered coal carbonization technique. It is known that many laboratories are at work on this problem and new and improved processes are likely to result from this work.
R
Underground Coal Gasification The gasification of coal underground is attractive in principle since i t might be expected t o recover energy from coal which could not be mined economically because of its low quality or unfavorable location. However, underground gasification experiments in various parts of the world have indicated t h a t there is practically no prospect of recovering gas of high heating value, and therefore whatever gas is produced must be used for power generation at the mine. Such use must be on a very large scale to be economical and it is still not certain that underground combustion on such a scale could be adequately controlled for steady, long-term power plant operation. The difficulty of controlling underground gasification makes it impractical t o risk the injection of relatively pure oxygen in the hope of making synthesis gas. July 1953
Agricultural Products Agriculture has been advocated frequently as a producer of organic matter which could be converted in one way or another to liquid fuels. The production of ethyl alcohol from corn has been the most attractive of such proposals, but i t is so handicapped by the problem of gathering raw material from large areas of cultivated land t h a t it is not competitive with other methods of making alcohol. If agricultural materials must be used, it would seem much more attractive to convert all of their carbon and hydrogen content to synthesis gas for the production of hydrocarbons b y the Fischer-Tropsch reaction. Synthetic fuels from agricultural raw materials are attractive in principle since they represent current utilization of solar energy and thus might be available for many years after accumulated reserves of fossil fuels are exhausted. A somewhat analogous method of utilizing solar energy is the growth of algae in water. The possibilities of algae cultivation at present are still largely undetermined but current indications are intriguing. Ayres ( 4 ) points out t h a t i t has already been demonstrated t h a t algae cultivation will yield as much as 30,000 pounds of solid matter per acre per year and there are reasons to hope t h a t this figure can be increased t o 200,000 pounds per acre per year. This may be compared with 15,000 pounds per year for potatoes, which are among the most productive of all land crops. Another advantage of algae cultivation is the mobility of the medium, which might make the raw material collection problem somewhat more simple than is the case for agricultural crops. Experimental work in Germany has shown t h a t algae can be converted t o oleagenous material by bacterial action and there is always the possibility of converting algae like any other organic matter to synthesis gas and then t o oil. The cultivation of algae presents many problems on which great progress will certainly be made in coming years, However, at present the technique appears much more attractive for making feed for livestock than fuel for engines.
Bituminous Sands The bituminous sands of Canada comprise a very substantial reserve of oil estimated variously at 100 t o 500 billion barrels ( 5 ) . Heavy oil exists as such in these bituminous sands to the extent of 20 to 30 gallons per ton and can be recovered by water displacement or by retorting. Unfortunately, only a small percentage of these sands are suitably located for strip mining. Such sands are more attractive than oil shale in respect to ease of recovery of oil but they have the same drawbacks of remote location relative t o potential markets and low quality of the primary oil which can be recovered therefrom. Here again the techniques for recovering useful products are well known, although susceptible to improvement, but the exploitation of reserves is dependent on economic considerations. Currently, the exploitation is retarded by the rapidly growing discoveries of petroleum in the same general part of Canada. Similar bituminous sands occur in the United States but are of a negligible extent compared to the Canadian deposits and present a more difficult problem of oil separation.
Economic Considerations Differences of opinion exist as t o the probable cost of making oil from shale or coal. Even from shale, the cost of gasoline would apparently be about 20% more than for gasoline from petroleum and some estimates of the cost of gasoline from coal are more than three times as high. The reasons for the relatively high costs of synthetic fuel are well recognized and research and development work directed toward reducing these costs is in progress at many places. However, it is not to be expected that sensational discoveries will result in sharp reductions in synthesis costs but rather that gradual improvements in
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the technique of synthesis mill bring synthesis costs into line Kith the rising costs of producing fuel from petroleum. Then the synthetic fuel industry will begin to grow according to sound economic laws. The petroleum industry recognizes its responsibility for meeting all demands for the products which i t normally supplies. Petroleum technologists have followed closely all developnients in fuel synthesis abroad, and petroleum research laboratories in this country have conducted research which will be useful as a foundation for fuel synthesis in coming years. The research work of the U. S. Bureau of Mines along the same lines will also be extremely valuable in guiding the logical growth of a synthetic fuel industry. The technological background which is now being developed will eventually enable the synthetic fuel industry to stand on its own feet and to meet all demands for liquid fuels on a sound business basis. literature Cited (1) Blberts, L. W. et nl., Chem. Eng. Progr., 48, 486 (1952). (2) Ayres, E., and Scarlott. C. -4., “Energy Sources-The Wealth of the World,” p. 82ff, New York, McGraw-Hill Book Co., 1952. (3) Zbid., p. 1556. (4) Ibid., p. 241.
Blair, S. -M., Report on the Alberta Bituminous Sands, Dec. 12, 1950.
Bruner, F. H., IND.ENG.CHEY.,41, 2511 (1949). Chem. Eng. News, 30, 1954 (1952).
Eastman, DuBois, presented a t a meeting of the Am. Inst. RIining Met. Engrs., New York, Feb. 18-21, 1952. Elliott, RI. A , and Perry, Harry, IND.ENG.CHEM.,44, 1074-82 (1952).
Gumz, Wilhelm, Ibid.,44, 1071-4 (1952). Holroyd, R., “Report on Investigations by Fuels and Lubricants Teams a t the I. G. Farbenindustrie -4.G. Works, Ludwigshafen and Oppau,” U. S. Bur. Mines, I C 7375 (August 1946). Latta, J. E., and Walker, S. W., Chem. Eng. Progr., 44, 173 (1948).
Ministry of Fuel and Power (British),“Report on the Petroleum and Synthetic Oil Industry of Germany,” BIOS Over-all Rept. 1, London, Her Majesty’s Stationery Ofice (1947). Natl. Petroleum Council, “Petroleum Production Capacity,” Rept. of the Committee on Oil and Gas Availability (Jan. 29, 1952). Natl. Petroleum News, 44, No. 17, 24 (1952). Strimbeck, G. R . , presented a t the Am. Gas Assoc. Production and Chem. Conf., New York, May 26-28, 1952.
Ton Fredersdorff, C. G., and Pyrcorch, E: J.,presentedat theAm. Gas k 3 3 0 C . Production and Chem. Conf., New York, May 2628, 1952. RECEIVED for review October 15, 1952.
A C C E P T E D ?daFch
20, 1953.
C ATA LY S I S
Hydrocarbon Chemistry HUGH S. TAYLOR Princefon Universify, Princeton, N. J .
Every classical chemical reaction i s characterized b y a rearrangement of electrons around a given set of atomic nuclei, with rearrangement of the nuclei. From the standpoint of solid-state physics catalytic materials consist of metals and those compounds which by reason of defect lattice structures possess the properties of semiconduc-
tors-including hydrides, oxides, sulfides, selenides, and halides of the transition metals. Ion and radical mechanisms are involved. Both old and newer data indicate that future developments in hydrocarbon chemistry are intimately related to a more penetrating analysis of solid-state. behavior and its correlation with catalytic activity.
HE mantle of the prophet sits heavily on the shoulders of the physical scientist. ,411 that one can do in the present situation is to trace the historical development of the subject and perform a short extrapolation into the future. From the earliest days of surface catalysis, in the work of Davy, Dobereiner, Turner, and Henry more than 100 years ago, hydrocarbons have been studied, oxidation a t platinum surfaces being the objective of study in that period. Faraday established the preferential position which gases, including hydrocarbons, obtained at surfaces of platinum in competition with hydrogen for reaction with oxygen. In the latter half of the 19th century Butlerov indicated the activity of sulfuric acid in the polynierization of isobutylene to diisobutylene and Friedel and Crafts added aluminum chloride to the list of important catalysts for hydrocarbon reactions. At the end of the century Sabatier and Senderens in France and Ipatieff in Russia were broadening the scope of contact catalysis by defining the activity of nickel, cobalt, iron, copper, and oxides of metals in a wide variety of organic compounds in which hydrogenation of olefins and olefinic materials, dehydrogenation, polymerization of acetylene, and many other reactions provided the bases for an advance in the a r t and later the science of catalysis.
The technical development of high pressure reactions by the Badische Co., notably in the synthesis of ammonia, led to synthetic processes for the production of hydrocarbons and oxygenated compounds and to the hydrogenation of the most abundant hydrocarbon material, coal. These achievements were a compelling invitation to explore the role of the catalyst in the whole complex of petroleum hydrocarbons. This symposium highlights the main aspects of this development during the last 30 years. The topics include acid and Friedel-Craft catalysts, mechanism of hydrogenation of olefins, catalysis in synthetic liquid fuel processes, the thermal reactions of hydrocarbons, and the use of catalysts, including metals, oxides, metal-acidic oxide catalysts, sulfides, and even bromides. There is a consensus that, in hydrocarbon chemistry, catalysts are of two types: one operative through ionic mechanisms, the other involving radical fragments produced a t surfaces by the operation of chemisorptive processes. The broadening scope of materials that have found application in hydrocarbon catalyses should be emphasized. I n contrast to the 19th century with platinum, sulfuric acid, and aluminum chloride as the main constituents of catalysts, the last 40 years have witnessed a striking multiplication of the materials employed to produce desired objectives. The motive in the proliferation process has been, in the majority of cases, t o fit the catalyst more
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