I X D USTRIAL A S D E-VGINEERING CHEMISTRY
October, 1926
FUTURE TRENDS IN INDUSTRIAL ENGINEERING CHEMISTRY Papers presented before the Division of Industrial and Engineering Chemistry a t the i 2 n d Meeting of the Am6 Philadelphia, Pa., September 6 to 11, 1926
Future Trends in Automotive Fuels’ By A. C. Fieldner a n d R. L. Brown PA. PITTSBURGH EXPERIMENT STATION. BEREAUOF MIXES, PITTSBURGH,
RON one hundred thousand to more than twenty million registered motor vehicles in the short span of twenty years is the almost incredible record of increase in the number of automobiles and trucks in the L-nited States. The automotive industry stands at the head of manufacturing, the value of the products being $3,163,000,000 for the year 1923.2 This is slightly more than the value of the products of the steel works and rolling mills, which came second with a value of $3,154,000,000. The development of the internal combustion c’ng’ine as a simple and reliable power-generating apparatus, the wealth of cheap petroleum, and the resourcefulness of the chemist in transforming etroleum into suitable motor fuel have made possible this tremendous development in automotive transportation. With one motor car for every six people in the United States, the continued supply of motor fuel for future needs is naturally of universalinterest, and chemists in particular are concerned with the problem of more efficient utilization of present sources of motor fuel, as well as the conversion of other fuel materials into a form suitable for automotive purposes. I n the broadest sense automotive fuels may be solid, liquid, or gaseous. All of these forms have been used to some degree, but the liquid form, and in particular volatile liquids, is the almost universal form of fuel used a t the present time. Petroleum gasoline comprises all but 1 or 2 per cent of the motor fuel consumed in the United Statw, and the United States has 80 per cent of the world’s automobiles.
F
Vnited Kingdom, and a considerable increase in the use of motor cars may be expected in Europe and other foreign countries. Whether such growing use of motors will absorb the new discoveries of petroleum in foreign countries is problematical; nevertheless, increased foreign competition for motor fuel must be recognized as an important factor in future automotive fuel supplies. The Report of the Committee of Eleven to the American Petroleum Institute3 estimates the total number of automotive engines in the United States in 1930 a t approxi50 per cent increase in five years. mately 31 million-a I n 1950 the estimated number is 45 million-another 50 per cent increase, but in a period of twenty years. The saturation ratio for passenger cars is assumed as one car for four persons. This figure will be reached in 1938; after this date any further increase will be due to increase in population. F u t u r e Fuel R e q u i r e m e n t
Froin the estimated number of automotive engines, the committee has calculated the yearly requirements for every fifth year up to 1975, based on both a maximum and minimum demand-the minimum demand assumes more efficient engines which consume only one half. of that now required per unit of work done. Following are some of these calculated gasoline demand figures : 4
....
N u m b e r of Automobiles a n d T h e i r Probable Increase
-4recent report of the Department of Commerce estimates 24,589,249 motor cars and trucks in operation throughout the world on January 1, 1926. Of these 19,954.347 are in the United States; the United Kingdom is second with 815,957 cars; France is third with 735,000; Canada, fourth with 715,962; and Germany, fifth with 323,000. The ratios of persons per motor car for the more highly motorized countries are as follows: Country United States Hawaii Canada N e w Zealand Australia
Persons per car 6 11 13 14 20
Country Denmark France United Kingdom Argentine
Persons per car 51 53 55 55
Owing probably to the unfavorable econoinic conditions, Germany is farther down the list than would be expected, with 193 persons per car. With the return of more prosperous conditions Germany should eventually have as many cars in proportion t o population as either France or the 1 2
1926
Published with approval of the Director, U. S Bureau of Mines. The American Year Book, 1925 The Macmillan Co , New York,
-MILLION GALLONS-Year Maximum Minimum 1925 9,165Q 1930 13,249 6,625 1940 16,928 5,464 1950 19,133 9,567 1975 22,981 11,490 Gasoline produced in 1925 was 10,886 million gallons.
Q
Domestic Reserves for Motor Fuel
To meet this demand the known domestic petroleum reserves of the United States are estimated by the Committee of Eleven as f o l l o ~ s : ~ Billion
(42barrels gallons) Oil from existing wells and proven acreage, available by existing methods of recovery J Oil remaining in this proven acreage after recovery b y present pumping methods has stopped. Much of this may be re26 covered by other more expensive methods Undiscovered new fields and deeper sands (no estimate made) . .. From 394 billion tons of oil-shale deposits 108 From 3127 billion tons of bituminous coal deposits 525 70 From 986 billion tons of lignite deposits ~
-_
TOTAL734
Only 4.2 per cent of this tot’al estimated reserve of liquid and potential liquid fuel is petroleum. “American Petroleum: Graw-Hill Book Company. 4 I b i d . , p. 202. 5 L O C . clt., p. 7 .
Supply and Demand,” 1926, p. 198.
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From these data it is evident that if the gasoline type of liquid fuel is to continue as the principal source of automotive power after petroleum supplies become inadequate, then the chemist must solve the problem of cheap and efficient transformation from solid to liquid form, the possibility of which has already been indicated by recent researches. Just when such augmentation of motor fuel from sources other than petroleum shall be required is unknown. Production thus far has more than kept pace with the growing demand, and recent improvements in cracking have made it possible to crack any type of crude oil to gasoline, coke, and gas. I n 1925 the gasoline yield of all crude oil run to stills was 35 per cent, and the Committee of Eleven believes that ultimately 65 per cent of the crude oil production will be recovered as gasoline. Using this figure, Mackenzie6 finds that: The reserves of over 5 billion barrels in this country from prese n t wells and present productive area will supply the estimated gasoline requirements of the country, using the maximum figures t o the year 1936 and the minimum figures to the year 1943. This, of course, does not mean that in 1943, at the latest, our petroleum reserves will be exhausted, since it is impossible to believe that we will not continue to find and develop new fields in this country.
Present Trends in Automotive Fuels
Present trends in the automotive and petroleum industry, in our opinion, are in harmony with the above estimate that petroleum will continue to furnish the great bulk of automotive fuel during the next decade. These trends are: (1) Increased production of crude oil by intensive prospecting and the use of more scientific methods, deeper drilling, and greater recovery by use of compressed air or gas, and by water flooding of oil sands. ( 2 ) Marked improvement of refinery practice, resulting in greater gasoline recovery and reduction of losses. (3) Development of cracking methods whereby any form of crude oil can be cracked down completely into gasoline, coke, and gas, with a possible ultimate yield of 75 per cent of gasoline. (4) Chemical modification of gasoline by improved methods of cracking and by blending or adding specific antiknock agents to permit its use with much greater efficiency in high-compression engines. ( 5 ) More efficient carburetor, engine, and motor car design.
IMPROVEMENTS IN PRODUCTIOX-Oil is now produced in California from depths in excess of 4000 feet, and there are a number of deep wells in Oklahoma, Texas, and Colorado. A well in the Athens Field of California is producing oil from a sand a t a depth of 7300 feet.’ A very definite start has been made toward recovering some of the 60 to 80 per cent of oil that remains in the sand after ordinary pumping secures no more oil. Water-flooding the sands in the Bradford Field of Pennsylvania has produced good returns, as has the application of compressed air or gas to certain limited areas. Natural-gas gasoline recovered by compression, oil absorption, and charcoal absorption processes is a n important factor in gasoline production, as it comprises 10 per cent of the total production and supplies the low-boiling constituents for blending with less volatile naphthas. IMPROVEMENTS IN REFINING-A similar recovery of volatile gasoline constituents from still vapors is typical of the trend towards the reduction of losses in refineries. The application of modern chemical engineering to refinery practice is one of the outstanding trends in the petroleum industry. Batch stills are being succeeded by continuous tube stills, with improved fractionating and bubble towers which increase the efficiency of the distillation and cracking
* Trns JOURNAL, 7
17, 1113 (1926) Hill, Bur. Mines, Circ. 6003, 4 (1926).
.
Val. 18, No. 10
process; installation of modern furnace designs and heat exchangers has increased fuel economy and the substitution of continuous washing processes and dilute acid, fuller’s earth, acid clays, plumbite solution, or other treatment for the drastic concentrated sulfuric acid wash has resulted in lowering refining costs and in saving valuable fuel and antiknock constituents. The Gray process for continuous purification in the vapor phase with fuller’s earth has given promising results in several large-scale installatiom.8 In this treatment the gum-forming constituents only, such as the diolefins, are removed and the losses are only 0.5 to 0.76 per cent as compared with 4 to 5 per cent in acid treatment. These are some of the more important current developments which show the attention that is being given to increasing the quantity and quality of gasoline in the refining process, but the most far-reaching of all is the great change taking place in cracking processes and their application, DEVELOPMENTS IN CRACKINQ--EglOff lo States: Not since its foundation in the year 1859 has the oil industry been so deeply affected as by the process of cracking heavy oils into gasoline. For the potential gasoline of the future lies in the cracking in one operation of heavy oils into just two productsgasoline and coke. Instead of gasoline representing 33 per cent of the total production of oil, as is the case a t present, in ten years or so 75 per cent will be the economic necessity, and this percentage of the gasoline will be derived from the cracking of heavy crude oils.
Cracking stills are becoming the central feature of the refinery, and it is estimated that by the end of 1926 the available cracking units in the United States should be able to supply about 45 per cent” of the total 1925 production of motor fuel. CHArCGES Is CHEMICAL COMPOSITION O F GAsOLIh-E-The new cracking processes not only permit cracking any type of crude oil, but also provide a motor fuel with antiknock properties, due to the high degree of unsaturation of the cracked product. It is now recognized that olefins have no gumming effect and are desirable constituents because of their antiknock effect. Consequently, cracking processes are being modified to favor maximum yields of olefins. This objective favors greater use of vapor-phase methods instead of liquid-phase, because of the higher yield of antiknock constituents by the vapor-phase product. Some of the new antiknock gasolines on the market contain as high as 40 per cent olefins. Color and specific gravity as criteria for quality of gasoline are now superseded by “antiknock” value and volatility. The antiknock values of the hydrocarbons are usually rated in the order of aromatic (benzene, toluene), unsaturated straight-chain (olefins), cyclic (naphthenes), and saturated paraffins. (Ricardo places cyclic ahead of straight-chain unsaturated compounds in antiknock properties.) Therefore, the antiknock value of the gasoline depends on the composition as well as the amount of unsaturates. These are in turn determined by the composition of the crude oil and the cracking conditions. The hea1-y asphaltic-base oils yield a gasoline of higher antiknock value than the paraffin-base oils. According to Egloff ,lo Smackover heavy oil is being cracked into over 50 per cent gasoline of particularly high antiknock value suitable for high-compression motors. Certain California heavy oils also yield high antiknock gasolines. Recognition of the value of the unsaturated constituents of gasoline has radically changed the methods of refining 11
Miller, “Petroleum Development and Technology in 1926,” A m
Inst Maning Me;. Eng., 1916, p 388 9 Liddell, Chem Met Eng , 31, 975 (1924) 10 “Petroleum Development and Technology,” A m Insl Minrna M e t . Eng , 1916, p 346. 1 1 Parmelee, I b r d , p 332
October, 1926
I S D l - S T R I . 4 L d S B EXGINEERISG C H E M I S T R Y
the cracked product, so as to avoid polymerizing and removing the olefins. I n fact, straight-run saturated gasolines, which were formerly a t a premium, are now subject t o discount unless blended with benzene or cracked antiknock gasoline, or treated with a n antiknock compound such as tetraethyl lead, and with the general use of motors of higher compression all motor fuel sold in a felv years will be of antiknock grade. Trend in Engine and Motor Car Design
At the present prices of gasoline the public is not primarily interested in gasoline economy, but in greater apparent power, freedom from detonation, and a smooth running engine. These characteristics, according to Horning, l2 “may be had in an engine using high compression, high turbulence and antiknock fuel and one of the least appreciated by-products will be economy.” The present average compression ratio of all models sold in the United States is 4.1 to 1. The best antiknock cracked gasolines are suitable for a compression ratio of 5.5 to 1 or more.I3 -4s antiknock fuels become more generally available, manufacturers of motor cars will increase compression ratios from year to year, to a figure probably not exceeding 6 to 1 . 1 2 These higher compression ratios should result in eventually doubling the mileage pw gallon of gasoline. Motor-car manufacturers are aiding also in decreasing the fuel required per car mile by more efficient carburetor design and other changes in engine design such as the Ricardo type of cylinder head, which reduces detonating tendencies; and of course the small, light car such as is used in Europe must eventually come when the fuel shortage greatly increases the price of motor fuel. Probable Trend when Petroleum Supply Becomes Inadequate
The probable trend in automotive fuels when the petroleum supply becomes inadequate is difficult to predict. The internal combustion engine using liquid fuels that can be carbureted seems so firmly intrenched that the production of similar substitutes and augmenting materials from coal, lignite, oil shale, and vegetable matter appears t o be the most likely solution of the problem, a t least for passenger automobiles. Certainly during the transition period these substitute sources must provide a fuel which can be blended with gasoline from petroleum to make a fuel that is generally suitable for the type of automotive engines then in use. These engines are likely to be high-compression engines which, require a maximum of anti-detonating properties in the fuel. Fortunately, most of the substitute materials answer this antiknock requirement, and antiknock compounds are now available which may be added to the fuels deficient in this property. The light oils from high-temperature carbonization of coal consisting of benzene, toluene, and xylenes have a high antiknock value, as do the light oils from low-temperature carbonization, which consist of 60 to 70 per cent unsaturated and cyclic hydrocarbon^.^^ The gasoline from cracking shale oil contains approximately 50 per cent of antiknock hydrocarbons, as shown by Morrell and Egl0ff.15 and the alcohols give their most efficient performance a t high compressions. The principal positive requirements of this future passenger automotive fuel will be: (1) volatility substantially 1’Am. Insl Mining Mef Eng , 1936,p. 468. I* Clayden, I b r d , p. 464. 14 Brown and Cooper, Cool A g e , 19, 90.5(1926). 16 TITIS JOURNAL, 18, 801 (1926).
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as a t present; ( 2 ) high antiknock properties; and (3) frecdom from gum or sediment-forming constituents. Sources of Petroleum Substitutes
Gasoline substitutes and augmenting materials fulfilling these requirements will come from one or more of the following processes: the fermentation of vegetable matter, the distillation of oil shale, the carbonization and also the hydrogenation of coal and lignite, and direct synthesis of alcohols and hydrocarbons from combustible gases. All these processes are likely to contribute some of the future motor-fuel requirement, and the solid mineral-fuel reserves of coal, lignite, and oil shale are necessarily the ultimate sources of raw material from which automotive fuels must be drawn. Alcohol f r o m Ferme)itntion Processes
The amount of alcohols that can be obtained from the fermentation industries is limited by the relatively small acreage not needed for supplying the world’s food, and it is by no means certain that such fermentation alcohol can be produced as cheaply as by synthetic processes beginning with coal as a raw material. According to Whitaker,lG The future of alcohol motor fuels is largely an economic problem. It involves the relations between cost of alcohol and the cost of gasoline The cost of alcohol is necessarily linked with the question of cost and available supply of raw materials. A s gasoline becomes scarce an economic balance is bound to be established between the prices of gasoline, the price of alcohol, and the prices and the resultant supply of raw materials. As this economic balance is approached, alcohol will doubtless be used in the making of motor fuels.
Ordinary 9.5 per cent ethyl alcohol is not miscible with gasoline in all proportions without addition of a third blending agent such as benzene. However, when anhydrous (99 to 100 per cent) it is miscible with gasoline in all proportions. Continuous distillation processes are now in use which yield anhydrous commercial alcohol suitable for motor-fuel blends that give excellent results in high-compression engines. Gasoline f r o m 011 Shale
The highly unsaturated gasoline obtained from cracking shale oil also promises to be a more valuable constituent of future motor fuels than has been thought in the past, now that unsaturation has become a virtue instead of a vice. The Committee of Eleven17 estimates the oil-shale deposits of the United States a t 394 billion tons, from which complete recovery would yield 135 billion barrels of shale oil on the basis of an average of 14.4 gallons per ton. While it does not seem economical to go as low as shale yielding 10 gallons, in competition with coal yielding 20 to 30 gallons per ton and a valuable smokeless fuel residue as well, yet the richer shales, those running 30 to 50 gallons and higher, will probably furnish a considerable portion of future motor fuels. Shale oil as a cracking stock is superior to the tar oils from the low-temperature distillation of coal, because it is free from phenols and tar acids. These compounds comprise from 30 to 45 per cent of low-temperature tar, and detract seriously from the motor-fuel yield on cracking the tar. Morrell and Egloffi5 obtained 50 per cent yields of Navy end-point gasoline from cracking shale oil a t 120 to 150 pounds pressure in laboratory-scale apparatus. Similar experirnentsl8 on cracking low-temperature tar yielded only 17 per cent motor fuel distilling below 230’ C. Oil, P a i n f , Drug R e p , , 108,P t . 2, 11 (October 5, 1925). L O C . C i l . , p. 121. 18 Morrell and Egloff, THISJOURNAL, 17, 473 (192.5). 16 1’
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INDUSTRIAL A N D ENGINEERING CHE-MISTRY
The time when and the extent to which shale will supply motor fuel is largely an economic question of competition with distillation and synthetic products from coal, which cannot be answered a t this time, because of the many advances in the technology of distillation and synthetic processes that will be made before the need for shale or coal gasoline arrives.
Motor Fuel from Coa119 The processes for obtaining motor fuel from coal may be grouped in four classes: (1) The high-temperature carbonization of coal, including the gas- and coke-manufacturing industry. ( 2 ) The low-temperature carbonization of coal. (3) The hydrogenation and liquefaction of coal by the Bergius process. (4). The complete gasification of coal and conversion of the resulting gases by pressure synthesis into methanol, Synthol, and other liquid combustibies.
Of these processes only the high-temperature carbonization is in commercial use, if we except the distillation of brown coal in Germany, which is done a t low temperature. A number of large-scale experimental units still in a developmental stage are operating intermittently both in this country and abroad. The principal object in most of these experiments is the production of a convenient form of smokeless solid fuel. Any considerable increase in the price of liquid fuel would make some of these low-temperature processes commercially successful. The partial liquefaction of coal by heating a t low temperature under high pressure of hydrogen by the Bergius method has been verified by a number of European laboratories, and large-scale experiments at Mannheiin by Bergius have shown that the process can be applied to a great variety of coals and lignites. The costs of the process are not available, but probably are too high to permit the process coming into use while petroleum is available in fair quantity. The synthesis of methanol from carbon monoxide and hydrogen has been in commercial operation in Germany for nearly two years. Fischer, Patart, Audibert, and others also have demonstrated by laboratory experimentation that the synthesis of motor fuels from the constituents of water gas is a future probability. These and similar synthetic processes have the advantage of being independent of the disposal of other products and can therefore be developed to furnish any desired quantity. The economic significance of the Bergius and the synthetic processes will become apparent as we show the yields and the possible total production from carbonizing coal wherein the motor fuel is a by-product. The total quantity of any by-product is necessarily determined by the market demand for the main product. M O T O R BENZOLFROM COKE AND GAS WORKS-~pprOXimately 3 to 4 gallons of crude light oil are obtained by hightemperature carbonization of one ton of coal. Sixty to 70 per cent of this light oil is suitable for motor fuel after proper refining, making the net yield per ton about 2.5 gallons. The total coal coked (including beehive ovens) in 1923,*O which was higher than in 1924, was 55,500,000 short tons, which if all coked with by-product recovery would yield 138,800,000 gallons of motor benzol or 1.3 per cent of the 10,886 million gallonsz1of gasoline produced in 1925. If the entire 1923 output of 545,500,000 tons of bituminous coal were put through by-product ovens the yield of motor benzol would be only 1,362,750,000 gallons, 18 20
21
Fieldner and Brown, Blast Furnace Steel Plant, 14, 138 (1926) Mineral Resources for 1925, U S. Geologtcal Survey. Hill, Bur M i n e s , Ctrc 6003,3 (March, 1926).
Vol. 18, No. 10
or 12.5 per cent of the gasoline produced in 1925. Obviously, coke-oven light oil can never supply more than small portions of future motor-fuel requirements, and can readily be absorbed as an antiknock constituent for blended fuels. ETHYLALCOHOLFROM COAL GAS-An interesting new by-product experiment has been in progress during the past year or two at a coke-oven plant a t Bethune mines in France.z2 The coke-oven gas is used as a raw material in a Claude plant for the manufacture of synthetic ammonia after separating the light oil, ethylene, and other constituents by compression and refrigeration. The ethylene is converted to ethyl alcohol via the ethyl sulfuric acid process. The yields of alcohol are probably between 1.5 and 2.0 gallons per ton of coal. The possible ultimate recovery by this process, should it eventually work out successfully, would increase the total motor fuel yield from coke-oven plants about 65 per cent. Ethylene from cracking stills and oil-shale plants can likewise be converted to alcohol.
L 0 W-TEM P E R A TURE
CARBONIZATION-LOW-tempeI'at
Lire
carbonization is often cited as the process which will solve the problem of future motor-fuel supply. I n this process coal is heated to 450' to 700" C. instead of 1000° to 1300". The tar yields per ton are from 20 to 35 gallons, or two to three times that obtained by high-temperature carbonization. Also, the tar resembles petroleum in some respects. Low-temperature tar consists of one-third to one-half tar acids and higher phenols, and the remainder is hydrocarbons-saturated, unsaturated, and cyclic. It does not contain benzene, toluene, naphthalene, or anthracene, and very little phenol or cresol, all of which are found in high-temperature tar. From 1 to 2 gallons of light oil may be scrubbed from the gas, and another gallon or two distilled from the tar, the total yield being from 2 to 4 gallons. I n a sample of noncoking western bituminous coal, Brown and Cooper14 found the oil boiling between 20" and 200" C. t o consist of the following compounds: Compound Pentane Isopentane Amylenes Hexanes Hex enes
Per cent 2 8 30 10 17
Compound Per cent Heptanes 7 Heptenes 5.5 Cyclic olefins (of 7 carbon atoms) 3.5 Octanes and above 7.5 Octenes and above 9 5
The 65 per cent olefins in this oil gives it a high degree of antiknock properties and therefore i t is a valuable ma-
terial for blending with straight-run gasoline. This oil was relatively free from diolefins, which are recognized gum-forming constituents. Refining losses would bring the net yield of motor-fuel from gas-scrubbing and straight distillation of the tar to about the same figure per ton of coal as obtained in. hightemperature carbonization. However, Morrell and Egloff l 8 have shown that about one-fifth of the total tar can be converted into Navy end-point motor fuel by pressure cracking, and they predict an ultimate yield of 30 per cent as a result of research in this direction. There is also a possibility of Fischer's method23 of reducing the phenols to benzene giving a further material increase in the motor-fuel yield. It is therefore reasonable to assume a future yield of one-third motor fuel from low-temperature tar, which amounts to 7 to 12 gallons, or an average of 10 gallons per ton of coal carbonized. Assuming that 136 million tons of bituminous coal, approximately one-fourth of the 1923 output, are carbonized a t low temperature, the motor-fuel yield on the basis of 10 gallons per ton will be 1360 million gallons, or 12 per Vallete, C h i m e & indusfrie, 13, 718 (1925). "Conversion of Coal into Oils," translated b y Lessing. 1996, p 163 Ernest Benn, 1,td , London. 22
211
October, 1926
IAVDUSTRI.4LA-YD E+VGISEERIAIGCHEMISTRY
cent of the 1925 gasoline production. It is evident that the maximum probable development of low-temperature carbonization, while furnishing a material quantity of motor fuel, cannot satisfy the entire demand. We must turn to processes in which motor fuel is the principal product rather than a by-product. BERGIUSPROCESS OF LIQCEFYISG CoAL-Of these the Bergius process deserves serious consideration, since it converts from 30 t o 50 per cent of the coal into tar and oils, the yield varying with the type of coal and the condition9 of hydrogenation. An attractive feature of this process is that it is applicable to low-rank, noncoking coals and lignites, of which there are large deposits in the western states. I n this process pulverized coal mixed with oil or tar to form a thick paste is heated a t 400" to 450" C. in an atmosphere of hydrogen under a pressure of 150 to 200 atmospheres. About 5 per cent iron oxide is included to remove sulfur compounds. Under these conditions the coal is converted into a black tarry liquid, which on separation from the ash and undecomposed residue yields from 35 to 50 per cent of crude oil, or 93 t o 133 gallons per short ton of coal. Bergius reports a test on an Upper Silesian gas coal from which 140 gallons of crude oil per metric ton of dry coal were obtained. This crude oil on straight distillation and refining yielded 40 gallons of motor fuel, 50 gallons of Diesel engine oil, 35 gallons of fuel or creosoting oil, a pitch residue, and 10,000 to 12,000 cubic feet of gas. The motor-fuel fraction is said to consist of saturated aliphatic, aromatic, and hydroaromatic compounds. Olefins are said to be absent. The crude oil contains phenols, but presumably in much smaller quantity than in Iowtemperature tar. Ormandy and Craven24 examined the light-oil fraction distilling from 40" to 160' C. obtained in the hydrogenation of an English coal. The yield of gasoline was approximately 10 per cent of the weight of the coal (34 gallons per short ton). The washing loss was only 1 per cent, and the gasoline consisted of unsaturates 3.1, aromatics 7.6. naphthenes 51.7, and paraffins 37.6 per cent. This composition indicates excellent "antiknock" properties. The accompanying figure is a diagram of the Bergius process for the liquefaction of coal, and the table shows the yields from 1100 pounds of a bituminous gaq coal plus hydrogen and iron oxide.25 The practical difficulties to be solved in coinniercializing the Bergius procesj are the development or' autoclaves of suitable metal and design to withstand the high temperatures and pressures required over five years or more of continuous use and the development of a cheap method obtaining the hydrogen necessary from the distillation gases. However, the process has reached a sufficiently advanced stage of development that it could be carried on t o commercial s u c c m under the stimulus of a petroleum shortage. Assuming that 2 tons of coal yield 1 ton, or 6 barrels of crude oil, then 252 million tons of coal would be required to produce the 1925 production of 765,852,000 barrels of petroleuin. I n other words, our present annual bituminous coal mined per annum would need to be increased about 50 per cent. X o doubt our friends in the coal business would welcome the exhaustion of our petroleum resources. It would solve the present troubles of the coalmining industry. However, from the standpoint of gasoline substitutes in large quantity from coal, the Bergius process is not the only possible solution. SYNTHETICMOTOR FUEL-The investigations of Patartz6
1013
and Audibert2' in France, and of Fischer28and the Badische Anilin und Soda Fabrik in Germany, together with the production of methanol from carbon monoxide and hydrogen on a commercial scale by the latter, present another route from coal to motor fuel. I n this process pure methanol is produced from two volumes of hydrogen to one of carbon monoxide when subjected to pressures of 150 to 250 atmospheres and temperatures of from 300" to 425" C. in a copper-lined reaction chamber, containing one or more of a number of catalysts which include zinc oxide or oxides of chromium, vanadium, manganese, tungsten, uranium, lead, and bismuth. The cost reported from both Frenchz6and
Diagram of Bergius Process for Liquefaction of Coal Yields from a Gas-Flame Coal hlot or fuel Fuel oil, for internal combustion engines Lubricating oil Fuel oil, for industrial use Distillation loss
Gas
200 60 RO
35
235
Water Ammonia Coke (with ash)
75
5 740
Loss
20
German29 sources Traries from 18 t o 27 cents per gallon. There are no by-products. Road tests in Germany reported by Fischer and Tropsch30 with a 4-cylinder truck and by Dumanois3*in France showed that the miles per gallon of methanol was approximately half that obtained with gasoline. The addition of 5 per cent water to the methanol was necessary to prevent backfiring, and after the addition of the water satisfactory service was obtained with a compression ratio of 6 t o 1.30 There was no detonation. One disadvantage of methanol is its lack of miscibility with straight-run gasoline. Nevertheless, some blend can probably be worked out with a third component, and in view of the similarity in the method of manufacture t o that of synthetic ammonia, methanol will doubtless receive serious consideration as a future motor fuel. Synthol. Of equal interest &om the laboratory standpoint is the product obtained by Fischer and TropschZ8 by a method similar to the methanol synthesis but using a different catalyst. Instead of pure methanol they ob27 Chimie & industrie 13, 186 (1925);translated in Fuel, I, 170 (1926). 28
Fischer and Tropsch, Brcnnsrof-Chem , 4, 193 (1923); I, 201, 217
(1924). 24
J . I n s f . Petroleum Tech., 12,77 (1926).
29
20
Bergius, Z. V n .deuf. I n & , 69, 1313, 1359 (1925). Chimic Er induslric. 18, 179 (1925).
* o Brcnnsfof-Chcm., 6, 233
20
Pounds 150
Elwortby. Can Chem. M c l . , 9, 139 (1925)
(1925).
** Compl. rend., 181, 26 (1925).
INDUSTRIAL AND ENGINEERING CHEMISTRY
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tained a mixture of alcohols, aldehydes, ketones, and acids with aliphatic hydrocarbons containing u p to eight or nine carbon atoms in the molecule. I n Fischer’s experiments water gas plus hydrogen was subjected to a pressure of from 75 to 150 atmospheres a t 400” to 435” C. in a steel reaction chamber containing a catalyst prepared from iron and a solution of sodium carbonate. By recirculation of the gases about one-third of the original water gas was converted into Synthol, having a distillation range similar to gasoline and a heating value of 8200 calories per kilogram. Satisfactory tests were made both alone and mixed with benzene in automotive engines. Synthol appears to be a better motor fuel than methanol, but the low yields, 27 per cent as compared to 85 to 90 per cent for methanol, must be greatly increased before it can be considered as an equal possibility for motor fuel. However, the Kaiser Wilhelm Institut a t Mulheim is continuing research in this field, and Fischer and Tropsch30832 have recently repeated the synthesis of higher homologs of methane from carbon monoxide and hydrogen a t atmospheric pressure and a temperature of 270” C. in the presence of finely divided metals of the eighth group, alone or mixed with metallic oxides such as those of zinc and chromium. I n one experiment a 14 per cent yield of liquid hydrocarbons similar t o gasoline was obtained by passing 1 cubic meter of water gas several times over an iron-cobalt contact mass. Oxygen appears in the reaction products almost wholly as carbon dioxide and water. Other research laboratories are now also working along these lines, so that further developments in synthesizing motor fuels may be expected in the future. At the present time the Bergius process seems the most promising for the conversion of coal to liquid fuel, because it is a more direct route than the others and does not involve expensive gas purification processes or the use of easily poisoned catalysts. Other F o r m s of Automotive Fuel
A discussion of future trends in automotive fuels would be incomplete without reference to fuels other than those suitable for the carburetor type of internal combustion engine. I n the early days of the automobile, steam and gasoline ran a close race. Even today steam-driven motor trucks for heavy duty may be seen in London and other cities of Great Britain. I n view of the 25 to 28 per cent thermal efficiency now being obtained in some of the latest steam-turbine power plants, it would appear that a steam or steam and mercury unit combined with powdered-coal combustion might be evolved for automotive purposes. The electric storage battery may also come back into the race, especially if the long-delayed discovery of a lightweight battery is made, and eventually we may have the ultimate solution in a coal-dust motor. It is reported that experimental work is being conducted by a German manufacturer on a Diesel engine using powdered-coal fuel, with some degree of success. It will be recalled that Diesel’s 52
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original idea was to use powdered coal. The oil injection engine which was successfully developed was a later idea.
Diesel Engine Automotive Power Diesel and semi-Diesel engines using heavy oils and coal tar will probably come into considerable use in the future for certain types of automotive equipment, such as rail cars, motor boats, tractors, and heavy motor trucks. Some progress has been made by Germany along this line and Faber33reports that heavy oils can be used with lower fuel costs than gasoline in motors where weight is not objectionable. Tar containing a considerable amount of phenol and boiling from 120” to 250” C. has been used successfully, provided a special kindling oil is mixed with it, and provided it is preheated with the exhaust gases. Benzene is used frequently as a starting fuel. On a 100-kilometer test trip with a &ton Benz truck there was a 50 to 70 per cent saving in fuel cost as compared with benzene. Sereral firms in Germany are building small heavy-oil engines of the vaporizer type for trucks, tractors, and automobiles, even including a unit for motor cycles. Although no similar Diesel units are yet on the market in this country, several manufacturers are working on the problem of developing comparatively light, high-speed Diesel oil engines. Successful development along this line might make it more economical to use low-temperature tar directly as a fuel than to crack it into gasoline and coke.
Gaseous Automotive Fuels Natural gas compressed in steel cylinders, manufactured gas from balloon-like containers, and producer gas from portable producers have all been used on demonstration cars, proving the technical possibility of these fuels for automotive purposes. The objections to transporting a fuel supply in heavy steel cylinders or bulky balloons are obvious and need not be discussed further. But the portable gas producer using charcoal or special low-temperature coke is worthy of some consideration for tractors, heavy trucks, busses, and rail cars. Several European manufacturers have built such equipment, and road tests with charcoal producers have shown fuel costs of one-sixth to oneeighth that of gasoline. The activated char from noncoking coals and lignite should be satisfactory fuel for these small producers. The disadvantages of the gas producer for automotive purposes are (1) loss of time in starting, (2) low overload capacity and inadaptability to varying power requirement, (3) weight and bulk, (4) more difficult to operate than gasoline motor, and ( 5 ) removal of dust and tar from the gas. In view of these disadvantages it is not expected to be a competitor of liquid-fuel engines for passenger or lighttruck automotive vehicles. Its use will be limited to constant-load, steady-speed, and continuous-operation service. 8 3 “Concerning the Technical and Economic Sittiation of the G e r m a n Supply of Fuel, Heating and Lubricating Oi19.” 1936, Leipzig
Russian Disputes Discovery of Chemical Elements Search for two missing chemical elements, recently reported to have been discovered in Germany, may have to be resumed for Russia claims that a careful check-up on the elements rhenium and masurium fails t o substantiate recent investigations. Walter Noddack of the University of Berlin, assisted by Ida Tacke and Otta Berg, reported in June, 1928, that he had found the characteristic x-ray spectra of missing elements, 75 and 43 of the periodic tables, in platinum ores from the Ural Mountains.
0. Zvjaginstsev, of the Platinum Institute of the Russian Academy of Sciences, has repeated Professor hToddack’sexperiments, using rare metals from the same source, but has failed to find element No. 75 and considers the presence of the still rarer element No. 43 “extremely unlikely.” The discovery of this element has also been claimed by Drs. Heyrovsky and Doleysek, both of Prague, who reported that they had found it associated with manganese.
