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INDUSTRIAL AND ENGINEERING CHEMISTRY
VOL. 32, NO. 9
CONVERSION OF HEAVY RESIDUESISTO LIGHTERDISTIL-production of motor gasoline, are determined by the spread High-pressure hydrogenation provides a useful tool between crude and fuel oil value. In Europe, owing to limited for conversion of tars and pitches from cracking operations, oil supply, tariff restrictions on importation of natural pereduced fractions from asphaltic and high sulfur crudes, coal troleum, national defense policies, etc., conversion of heavy tar, and other materials having extremely low ratios of hyhydrocarbons into lighter, higher valued fractions can be more drogen to carbon into lighter and more easily processed hyreadily justified. The same considerations make the hydrodrocarbon mixtures. This conversion is effected without genation of coal and other solid carbonaceous materials more degradation of the starting material. Although no commeradvantageous. I n this field hydrogenation comes into comcial operations of this sort have been carried out in the United petition with methods for hydrocarbon synthesis from carbon States, the possibilities of this phase of the hydrogenation monoxide and hydrogen, which in turn may be prepared from process have been investigated in the laboratory. solid, liquid, or gaseous carbonaceous materials. The high-pressure hydrogenation of heavy residues, tar, and asphaltic materials is usually carried out in the liquid Literature Cited phase in the presence of strongly hydrogenating nonselective Brown, C. L., and Gohr, E. J., World Petroleum, 8 , No. 1 1 , 49-54 catalysts. Volumetric yields of gasoline and gas oil of 100 to (1937). 105 per cent are obtained in this operation. The operation Brown, C. L., and Tilton, J. A., Oil Gas J . , 36, No. 4 6 , 7 4 (1938). may be conducted so as to yield from 10 to 35 per cent of Byrne, P . J., Gohr, E. J., and Haslam, R. T., IND.Eruo. CHEM., 24, 1129 (1932). gasoline directly. It is advantageous to carry out the operaEdlund, K. R. (for Shell Development Co. and Shell Chemical tion to produce a maximum yield of material of the gas-oil Co.), Proc. 8th M i d y e a r Meeting A . P. I . , Sect. 3, 87 (1938). boiling range which may subsequently be cracked or hydroHaslam, R . T., and Russell, R. P., IKD.ENG. CHEM.,22, 1030 genated in the gas phase. If cracking is employed on the up(1930). Haslam, R. T., Russell, R. P., and Asbury, 1 % ' . C., World Petrograded material, the cracked tar resulting from the cracking leum Congr., London, 1953, Proc. 2, 302. operation may be returned to the hydrogenation plant. I n Howard, F. A., Oil Gas J . , 30, No. 46, 90 (1932). the liquid-phase hydrogenation process the asphalt content of Murphree, E. V., Gohr, E. J., and Brown, C. L., IND.Exa. CHEM., 31, 1083 (1939). the charge stock may be completely converted to single-ring Parks, G. S.,and Todd, S. S., I b i d . , 28, 418 (1936). aromatic, naphthenic, and paraffinic materials, and from 65 to Russell, R. P., in "Science of Petroleum", edited by Dunstan, 95 per cent of the sulfur may be eliminated. Some typical Nash, Brooks, and Tigard, Vol. 3, p. 2139, London, Oxford examples of the once-through liquid-phase operation are Univ. Press, 1938. Russell, R. P., Gohr, E. J., and Voorhies, A , , Jr., J . Znst. Petrogiven in Table X. leum Tech., 21, 347 (1935). The hydrogenation of heavy, low-hydrogen-content stocks Sweeney, W. J., andvoorhies, A., Jr., IND. ENQ.CHEM.,26, 195 requires relatively large amounts of hydrogen and therefore (1934). has a somewhat higher operating cost than other adaptations Vlugter, J. C., Waterman, H . I., and Westen, H. A. van, J . Inst. Petroleum Tech., 21, 661-76 (1936). of hydrogenation. The economics of this operation, as in the LATES.
ECONOMIC ASPECTS L. A. STENGEL Commercial Solvents Corp., Terre Haute, Ind.
HE classification of hydrogenation from the economic viewpoint naturally follows the main chemical subdivisions. We may, then, divide hydrogenation, not only from the chemical, but from a n economic aspect, into the following classes:
T
1. Reduction of the ethylenic linkage 2.
3. 4. 5. 6.
Reduction of a carbonyl group, or of carbon monoxide, t o an alcohol Reduction of a carboxyl derivative to an alcohol Hydrogenation of coal, petroleum, or tars Hydrogenation of nitrogen to ammonia Hydrogenolysis
From the above grouping of different classes of hydrogenation, one may wonder from what source the hydrogen is obtained for processing. Usually a company that has byproduct hydrogen from such sources as electrolysis of brine, special fermentations, electrolytic oxygen plants, etc., is interested in any hydrogenation process whereby any of their products or raw materials can be hydrogenated, using cheap or waste hydrogen. This condition probably accounts for a large number of hydrogenated chemical compounds on the market today that would otherwise not have been produced. Once a company has provided itself with a cheap source of hydrogen and facilities for making it available in the pure
R . NORRIS SHREVE Purdue University, Lafayette, Ind. state and under pressure, that company is in a position where manufacture of hydrogenated products is highly favored after thorough investigation by its research departments. Such companies even go in for custom hydrogenation and advertise that they will undertake this reaction on order for their customers. The charge for this work varies greatly, but one company advises that they undertake it a t a price ranging from 15 cents per pound for small quantities of fine chemicals, downward. Such charges vary with yields, specifications, processing difficulties, catalyst requirements, and volume of business. A company that is in a position where i t requires hydrogen to make products by hydrogenation must choose a source whereby its cost will not place them under any handicap in regard to competition. This choice has even resulted in building a new plant a t a location where cheap hydrogen can be produced. Exceptions t o the economics of a cheap source of hydrogen are companies that are producing hydrogenated products by processes covered by patents so that competition is prohibited. These companies may use hydrogen from a source that may be classed as expensive. Also companies fall within this class that produce high-molecular-weight products, whereby the hydrogen cost is not an important factor as regards total cost, unless the hydrogen requirements are very large.
SEPTEMBER, 1940
INDUSTRIAL AND ENGINEERING CHEMISTRY
Sources of Hydrogen The unit process of hydrogenation employs just one agenthydrogen. However, the means for obtaining the hydrogen vary greatly, according to the purity desired, scale of manufacture, and particular raw materials available. Thus one process will be more important in one country than in another, or even in different sections of a given country. Narrowing the source of hydrogen down to definite cases, the most important factors regarding a source of cheap hydrogen are the quantities and purity required. The purity required is of the utmost importance, especially if large quantities are desired. Impurities, such as the carbon oxides and water vapor, are generally not detrimental for reduction of the carbonyl groups or of the carboxyl derivatives. Usually for the reduction of the ethylenic linkage, the hydrogen must be free from all carbon oxides. The hydrogenation of nitrogen to ammonia requires a very pure hydrogen, in which impurities of carbon oxides or water vapor to the extent of 0.01 per cent are injurious to the catalyst. Sulfur compounds, usually found in hydrogen produced from cheap sources such as water gas, petroleum, and refinery gases, are considered an all-round poison to most hydrogenated catalysts. I n some cases catalysts containing metal sulfides have overcome this poisonous effect. Hydrogen from cheap sources also contains some nitrogen and saturated hydrocarbons, such as methane. These gases act mostly as inerts and generally have no bad effect on hydrogenation reactions except in lowering the partial pressure of the hydrogen and necessitating purging of the system to keep them down to a certain percentage. Hydrogen produced by electrolysis is the standard or purest form. No purification is necessary unless the water vapor is injurious to the catalyst or reaction. Electrolytic hydrogen is generally used by most companies producing hydrogenated products where their requirements are up t o several hundred thousand cubic feet per day. Beyond these quantities, unless the company has a cheap source of power or needs large amounts of process steam which could be used first in generating power, i t is cheaper to produce the hydrogen by such processes as the reaction of steam on hydrocarbons or a watergas catalytic unit. Hydrogen produced by the reaction of steam with hydrocarbon is the lowest cost pure hydrogen obtainable in large quantities if produced in locations where cheap natural gas is available. Hydrogen produced by water gas and steam or from cokeoven gas is preferred by the synthetic ammonia producers, who are the largest individual consumers of hydrogen in this country and in the world. I n this country the synthetic ammonia producers evidently considered coal as a longer lasting source of raw material than natural gas. I n the past few years the petroleum companies have consumed large quantities of hydrogen for production of special high-octane gasolines and lubricating oils. Their source of hydrogen is the reaction of steam with natural gas or waste refinery gases. The source of hydrogen for the synthetic methanol producers is from water gas and natural gas. The hydrogen in this gas cannot be compared as to cost with pure hydrogen, since the hydrogen is mixed with carbon monoxide, carbon dioxide, and inerts. A careful study of the production of hydrogen has been made by a number of interests, specifically by the United States Tariff Commission ( 6 ) , Curtis (Z), and Fenske (3). Referring to the world production, the Bureau of Foreign and Domestic Commerce reported recently as follows (6) : “The three methods used for almost the entire world commercial production of hydrogen are: (a) total gasification of coal, coke, and lignite by the water-gas and producer-gas
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processes, which appears to account a t the present time for about 55 per cent of the total; (b) separation from coke-oven gas by the use of Linde, Claude, and similar low-temperature compression liquefaction plants, corresponding t o about 26 per cent of the total; and (c) electrolysis*of water, amounting to about 16 per cent, leaving 3 per cent for all other methods. These include electrolysis of salt solution, fermentation, cracking of petroleum gases, natural gas, and coke-oven gas, and the action of steam on iron or iron oxide.” About 1926, as shown in the report on chemical nitrogen (67, practically 90 per cent of the world production of hydrogen for all of its varied applications came from water gas. The preponderance of this method declined rapidly until for 1933-34 it was only 57 per cent of the total; the coke-oven gas sources and that from the electrolysis of water increased correspondingly. However, in the United States the cokeoven production, with its accompanying liquefaction, has not proved so economical in competition with the water-gas procedure. Because of the difficulty of transportation of hydrogen and the complexity of the plant necessary for its manufacture, the bulk of the supply is consumed in the factories where i t is made. Table I, revised from Fenske (S), gives an approximation for the consumption of hydrogen in the United States. TABLE I. ESTIMATED HYDROGEN CONSUMPTION OF THE UNITED METHANOL, ISOOCTANE, AND STATESIN 1939 FOR AMMONIA, PETROLEUM HYDROG~NATION Synthetic ammonia Synthetic methanol Technical isooctane Petroleum hydrogenation
Hz Consumed, Production Million Cu. Ft. 200 000 tons 16,500 34,255,699 gal. 7,880 2,400 1,500,000 bbl. 9 plants producing 1,500,000 bbl. aviation and special gasolines by hydrogenation 7,000
-
Total 34,050
As is usual with our manufactures, reports are sent in to our Bureau of Census. The available census data relate only to the hydrogen produced for sale and are based upon returns submitted by establishments engaged primarily in production of compressed and liquefied gases. However, there is included some electrolytic alkali by-product hydrogen delivered by pipes for the manufacture of ammonia and other commodities. These census data follow: No. of establishments Thousand cubic feet
Value
1933 36 589,290 $914,532
1935 40
743,560 $1,556,658
1937 41 1,103,177 %1,848,529
Factories for the manufacture of compressed hydrogen for sale are located all over the United States. This is apparent from Table 11. Such widespread distribution is due to the expense of shipping and returning the cylinders in which the compressed hydrogen is sold. These sales, however, have little to do with large-scale hydrogenations; they are largely the result of the need for hydrogen in welding, small-scale fat hydrogenation, etc. Bottled hydrogen would in most instances be too expensive for the hydrogenation industry. The cost of cylinder or bottled hydrogen is very high, because of shipping charges of the cylinder back and forth, together with the labor and maintenance involved in charging the cylinder. The standard cylinder contains 200 cubic feet of hydrogen under a pressure of 1800 pounds. Its net delivered cost varies according to location. Data pertaining to the cost of producing hydrogen have been published (3, 6). I n the electrolysis of brine for the primary production of sodium hydroxide and chlorine, the hydrogen that was once wasted is now being used in hydrogenations and is conse-
INDUSTRIAL AND ENGINEERING CHEMISTRY
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TABLE11. LOCATION OF HYDROGEN ESTABLISHMENTS IN THE UNITED STATES State Ark. Calif.
Ga.
Ill. Ind.
KY.
Mass. Mich. Minn.
Mo. N. J. N. Y.
1933 1 3 1 2 1 1 1 2 1 2 1 3
1935 & 3 1 2 2 1 1 2 1 1 3 4
1937 1 4 1 2
2 1 1 2
..1 3 4
State Ohio
Oreg.
Penna. Tenn. Texas Utah Va. Wash.
W. Va.
Wis.
Total
1933 5 1 3 1 2
..2 ..21 -
36
1935 4 1 4 1 2 1 2 1 1 1
1937 3 1 6 1 2
40
41
-
*.
2
..22 -
quently the cheapest hydrogen available. Its value should be that a t which a comparative quantity could be manufactured by the cheapest method a t that location. Summarizing Fenske's discussion of this cost, it may be said that for 1000 cubic feet of hydrogen at ordinary pressure and temperature, the total cost of the hydrogen may be anywhere from $1.45 to as low as $0.15 per thousand cubic feet; the latter low cost is for large quantities from natural gas or waste refinery gas as the basic raw material, coupled with a very low power cost. The average selling price given for 1937 from the census figures quoted above indicate a price of $1.60 per 1000 cubic feet. This, however, is undoubtedly the naked selling price f. 0. b. factory, compressed for sale in cylinders.
fish oils, such as whale, etc. Without hydrogenation many fish oils would be unsalable because of their taste and odor. The cost of such hydrogenation varies from slightly lower to slightly above one half cent per pound. The Bureau of Census reports (Table 111) the production and consumption of these hydrogenated oils. REDUCTION OF CARBONYL GROUPS,OR OF CARBONMONOXIDE, TO ALCOHOLS.The most outstanding example under this classification is the manufacture of methanol from carbon monoxide through hydrogenation. The economic influence of this synthesis has been of considerable significance in this field, since it has forced down the price of methanol produced from the destructive distillation of wood and greatly extended the use of methanol. The growth of the importance of the synthetic methanol production is apparent from Table IV. The present capacities of the synthetic methanol plants in this country exceed 50,000,000 gallons a year. When not producing methanol they can be used for making a mixture of higher alcohols and methanol by increasing the temperature and changing the catalyst. Isobutyl alcohol can be produced in conjunction with methanol. These plants are also closely connected with the manufacture of ammonia. TABLEIV. PRODUCTION OF METHANOL
STATES PRODUCTION AND CONSUMPTION OF TABLE 111. UNITED HYDROGENATED OILS, 1934-1939 Year 1934 1935 1936 1937 1938 1939
Production. Pounds 551,483,223 748,390,732 885,953,369 753,693,204 722,624,913 819,949,868
Consum tion, Pounas 5 13,170,160 688,307,958 809,417,166 669,035,825 668,761,113 768,331,370
The initial industrial application of hydrogenation was in the so-called hardening of fats, in which the ethylenic linkage is hydrogenated. Here, among other reactions, the glyceride of oleic acid is reduced to the glyceride of stearic acid. The economic importance of this simple reaction is tremendous, not only in the United States but throughout the world, since these hardened or hydrogenated fatty oils are much better in quality and hence more salable than is the crude oil. The odor and taste are improved and the tendency to rancidity is greatly decreased. Although cottonseed oil is one of the principal oils hydrogenated, this process is also used on many
Synthetic, Gallons 500,000 7,007,332 13,359,247 33,374,015 34,255,699
Year 1927 1931 1935 1937 1939
Products of Hydrogenation REDUCTION OF ETHYLENIC LINKAGE. This may be considered to apply to both the aromatic and aliphatic series, and in both of them i t has reached considerable industrial importance. I n Germany and in the United States phenol and naphthalene are hydrogenated to yield cyclohexanol (Hexalin) and tetrahydronaphthalene (Tetralin) or decahydronaphthalene (Decalin). These materials are liquids and have attained some importance as solvents. The manufacture of nylon will stimulate the hydrogenation of phenol as a step in making the constituents of this artificial fiber, which are assumed to be adipic acid and hexamethylenediamine. Reliable information indicates a n annual production of 8,000,000 pounds of nylon in about a year's time. The tremendous demand for aviation gasoline has pushed hydrogenation to the forefront; in its production the polymerization products of butene and isobutene are hydrogenated to technical isooctane. Such production amounted to approximately 225,000 barrels of technical isooctane in 1937, and had increased to 1,500,000 barrels in 1939.
VOL. 32, NO. 9
From Wood, Gallons
.....
2,737,046 3,648.180 3,437,758 3,960,000
The possibilities of the hydrogenation of carbon monoxide, giving varieties of products, are of considerable economic importance, particularly in the future years or whenever there may be a n increase in the price of petroleum products that may compete in this field. REDUCTION OF CARBOXYL DERIVATIVES TO A N ALCOHOL. For generations, soaps have maintained the leading economic and technical position in cleansing compounds. I n the last few years the introduction of the sulfated higher alcohols has furnished new detergents in the field in which the ordinary soap does not function well. The underlying chemical reaction has been the reduction of RCOOH to RCHsOH, where R is, for example, a n all-carbon chain. This resulted in the production by hydrogenation of lauryl alcohol from the lauryl acid in the glyceride present in coconut oil. These products are on the market in the form of sodium lauryl sulfate, with varying amounts of sodium oleyl sulfate, etc., under the various names of Gardinol or Dreft. The initial work in this field was carried out in Germany. Table V gives imports into the United States. TABLEV. UNITEDSTATESIMPORTS, FOR CONSUMPTION, OF SULFATED" FATTY ALCOHOLS AND FATTYACIDS AND SULFATEDO SALTS OF FATTY ACIDS Year 1937 1938 1939b a
Quantity 33,875 154,342 289,515
Value $ 7,209
37,110 69,410
Not elsewhere specified
b Preliminary
figures.
Statistics of domestic production are not easy t o arrive at, but for 1938 a United States production was reported of 7,668,458 pounds of sulfated fatty alcohols and sulfated fatty acids. Included in this figure are the statistics for the fundamental sulfated fatty alcohols contained in the detergents Gardinols, Dreft, and Drene.
SEPTEMBER, 1940
INDUSTRIAL AND ENGINEERING CHEMISTRY
HYDROGENATION OF COAL, PETF~OLEUM, OR TARS.I n future years this aspect of hydrogenation will be one of the most important industrial chemical reactions. Already in the petroleum field it has attracted wide attention. It results in upgrading of the raw materials. KO coke or tars are formed such as characterize cracking operations. Nine plants for the hydrogenation of petroleum have been constructed ‘and operated at various points in the United States, and are fully described in the literature (1). Their source of hydrogen is the reaction of waste refinery gases with steam to form hydrogen and carbon dioxide; the latter are removed by scrubbing with water under pressure or by triethanolamine. The hydrogenation of unsaturated products giving, for example, isooctane, has already been mentioned under the ethylenic linkage. When our petroleum riches begin to decrease, there is no question but that the hydrogenation of coal and tars will be pushed to the fore in order to furnish products now obtained from petroleum. Such plants in the petroleumpoor countries are now very important industrially for s u p plying motor spirits. This is true of both England and Germany. Fenske (3) gives flow sheets and general procedures for these operations. Our Government, or other forwardlooking research agencies, should study these procedures intensively from the American economic viewpoint, both from the chemical engineering and economic aspects. Then when the demand comes for a greater supply of motor spirits, solvents, and other such compounds than can be supplied by the petroleum industry, this can be met, in part at least, by the hydrogenation of coal. HYDROGENATION OF NITROGEN TO AMMONIA.No reaction that has been commercialized in recent years has had a more profound economic importance than the hydrogenation of nitrogen to ammonia, particularly by the catalytic processes such as the Haber-Bosch process. This has resulted in cutting the price of ammonia, not only for fertilizers but also for the manufacture of nitric acid for explosives and other purposes. It means that not only can we secure a t reasonable prices adequate supplies of nitrogenous fertilizers, but that the whole extensive nitrogen industry of the world is now based on a reasonably priced and practically inexhaustible raw material. This industry has shown the road to the most economical methods for carrying out hydrogenation and the cheapest
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means for manufacturing hydrogen. Such hydrogen is largely produced by a modified water-gas reaction in this country, or from the liquefaction of coke-oven gas in other countries. Full details of such procedures are given in articles already cited. HYDROQENOLYSIS. A recent and important feature of hydrogenation is the introduction of hydrogen accompanied by splitting of the molecule. This we call “hydrogenolysis”; excellent examples are given by Fenske (3). Sugars can be hydrogenated to give, in the first place, reduced products such as are now being commercialized by the Atlas Powder Company (4). Although the Atlas Powder procedure yields only hydrogenation products, other researches have carried the hydrogenation of these initial products, particularly of the sorbitol, to a further stage; the result is a carbon-to-carbon cleavage yielding glycerol and propylene glycol. Such a hydrogenolysis reaction has not been commercialized, but i t may well be that procedure to which industry can turn in case of a shortage in the normal supplies of glycerol or in case of an increased demand. Such hydrogenolysis reactions utilize catalysts a t elevated temperatures and pressures.
REQUIRED TABLE VI. HYDROGEN
Raw Material Phenol Naphthalene Olein Diisobutylene
TYPICAL PRODUCTS
FOR
Product Cyclohexanol Tetralin Stearin Isooctane
Cu. Ft. H1 Required ( a t 60’ F.) per Ton Product 23,000 12,000 2,600 6,700
Literature Cited Byrne, P. J., Jr., et al., IND.ENCI.CHEM.,24, 1129 (1932): Murphree, E. V., et al., Ibid., 32, 1203 (1940). Curtis, H. A., “Fixed Nitrogen”, A. C. 5. Monograph 59, New York, Reinhold Pub. Corp., 1936. Fenske, M. R., in Groggins’ “Unit Processes in Organic Synthesis”, 2nd ed., Chap. 8, p. 422, New York, McGraw-Hill Book Co., 1938. Taylor, R. L., Chem. & Met. Eng., 44,588 (1937). U. S. Bur. Foreign & Domestic Commerce, private communicstion, 1940. U. S. Tariff Comm., Rept. 114, 41 et seq. (1937).
HYDROGENATION OF ANILINE CHARLES F. WINANS The Goodyear Tire & Rubber Company, Akron, Ohio
Technical cobalt oxide activated by powdered calcium oxide is recommended as a catalyst for the hydrogenation of aniline to cyclohexylamine. The presence of ammonia in the initial reaction mixture retards the conversion by dissolving the catalyst. The addition of dicyclohexylamine represses the loss of cyclohexylamine through autoalkylation and improves the yield of primary amines without interfering with the completeness of hydrogenation. I
Present address, Mellon Institute, Pittsburgh, Pennn
ATALYSTS and conditions of reaction for the hydrogenation of aniline to cyclohexylamine have been the subject of numerous investigations ( 3 ) . This paper describes the development of a process for improving the yield of cyclohexylamine (6) by the selection of catalysts and by the control of side reactions. The catalyzed chemical reactions are the hydrogenation of aniline to cyclohexylamine, CeHs.NHs 3Hz +CeHii.NHz (1)
C
+
the autoalkylation of cyclohexylamine,
+
2CeHii.NHt --f (CeHn)zNH NHI (2) and to a smaller extent the hydrogenolysis of cyclohexylamine to cyclohexane and ammonia,
