INDUSTRIAL UTILIZATION OF FATS AND OILS ARTHUR GUILLAUDEU Swift & Company, Chicago, Ill.
H EMISTS generally recognixe t h a t t h e terms “fats and oils” a r e a l m o s t interchangeable; fats are usually solid a t room temperature, whereas oils a r e usually liquid. The composition of the fats will first be discussed as affecting their physical properties and uses. T h e principal uses will next be given as shown by the census figures for consumw tion; and then an attempt will be mide to forecast the trend of developments.
Acids of fish oils and marine animal oils are characterized by large proportions of acids of 20, 22, and 24 carbon atoms: No. of c Atoms 14 16 16 18
No.
Cottonseed Oil Sea Island Upland
c
Acid Myristic Palmjtic Stearic Oleic Linoleic
(10)
Soybean Oil (b
Corn Oil
(9)
%
%
%
%
ii:5 4.2 32.0 49.3 2.2 0.7 0.1
+:3 3.3 43.4 39.1
...
0.6
...
0:1
..
4.5 11.5 17.0 2.5
18 20 22 24
’
Acid Unsatd. Unsatd. Unsatd. IJnsatd.
7 Men-
g?den WEle Orl(16) Oil(i.9) 24.9 36.5 22.2 20.2
..
16.0 10.0 1.5
(1)
C22H3202, A 4:8:12:15:18:21 or A 4:8:11:14:17:20
Licanic acid, from oiticica oil, is unusual among the acids in two respects, the ketonic group and the conjugated double bonds ( 3 ) :
i):4 0.2
.” H H H H H H H H H HOOC--C-C-C-C-C-C-C-C=C-C=C-C=C-C= H H I
d
H H H H H H H H H C-C-C-C-CH H H H H
Chaulmoogric acid, from chaulmoogra oil, is one of the few naturally occurring fatty acids containing a ring. This oil has been used for the treatment of leprosy (18): H H
No. 6 8 10 12 14 16 18 18 18
i:S
No. ofC Atoms
By hydrogenation it is converted to stearic acid. Linoleic acid, linolenic acid, and other acids of the drying oils differ from it by having additional unsaturation. When acids are only slightly unsaturated, the double bond nearest the carboxyl group is usually a t the ninth carbon atom and the next one is a t the twelfth carbon. But other arrangements also occur. Introduction of a hydroxyl group on the twelfth carbon yields ricinoleic acid, the typical acid of castor oil. By dehydration a new double bond conjugated with respect to the first one is formed. This increases the reactivity of the oil and makes it valuable for the coating industry. The unsaturation of a single acid of a fish oil (16) is given to illustrate conditions prevailing in such oils:
The composition of any one oil will differ from variety to variety and according to cultural conditions. The variation in constituent acids as to length of chain is important as well as the variation in unsaturation. For instance, when completely hydrogenated, corn oil yields a fat of much higher melting point than does cottonseed oil because of the much lower percentage of acids other than 18-carbon acids. The acids of coconut oil and its related oils are much shorter than those of other groups (6), as the following table shows: of C Atoms
9.2 22.7
WEle Oil(f.3)
H H H H H H H H HOOC-C-C-C-C-C-C-C-C= H H H H H H H H H H H H H H H H C-C-C-C-C-C-C-C-CH H H H H H H H H
Most chemists now recognize that the fats are not mere mixtures of simple triglycerides such as tristearin, triolein, and tripalmitin. The characteristic compositions of typical vegetable oils are given in the following table: of
2Oil(f6) 22:
A great variety of acids is offered by plant and animal sources. Oleic acid occurs in almost every fat and oil:
Composition
Atoms
Acid Myristic Palmitic Unsatd. Stearic
Acid Caproic Caprylic Capric Lauric Myristic Palmitic Stearic Oleic Linoleic
Per Cent Trace
HOOC-(CHJ1z-C Hz H2
7.9 7.2 48.0 17.5 9.0 2.1 5.7 2.6
The assembly of the fatty acids into molecules also differs and causes large variations in physical properties. Cacao butter and mutton tallow have similar acids, but “cacao 15 8
INDUSTRIAL AND ENGINEERING CHEMISTRY
FEBRUARY, 1939
butter contains a large proportion of oleo distearin and oleo dipalmitin and is a hard, almost waxy fat with brittle fracture and comparatively low melting point (34 O C.), whereas mutton tallow with a higher melting point (44-49’ C.) is greasy to the feel and does not fracture cleanly” (8): % Cacao Butter (11) Fatty Acid Myristio Palmitic Stearic Oleic Linoleic GI ceride gully satd. Mono unsatd., di satd. Di unsatd., mono satd. Tri unsatd.
5% Mutton Tallow (7)
Of the total inedible fats, 1,475,756,000 pounds or 56 per cent were used for making soap (Table I). The harder fatstallow, palm oil, grease-yield the firmer soaps. Softer oils, such as fish oil or soybean oil, can be hydrogenated to resemble, and to some extent to replace, the natural hard fat. But the fatty acids formed during the process are not entirely the same structurally as those occurring in the natural fats, and this must be taken into account when soaps are formulated. FATSUSEDIN VARIOUS INDUSTRIES (4) TABLEI. INEDIBLE
2.6 77 16 4
26 30-52 44-0 0-22
Use Soap
As raw materials for further chemical processing, the fats and oils can be hydrogenated, oxidized, sulfonated, converted to mono- and diglycerides, or by hydrolysis be split into fatty acids and glycerol for use separately or for reassembly into glycerides more homogeneous than any natural ones. The fatty acids, again, can serve as starting points for nitriles, amines, and other derivatives. For along time little attention was paid to the fundamental studies of fats, but in recent years this has not been true. For instance, analytical methods have been developed to determine not only the constituent fatty acids and the locations of double bonds, but also their grouping into molecules. The reactions undergone during oxidation, hydrogenation, or pyrolysis have been studied to throw light on the manufacture and on the properties of edible products, coating compounds, soaps, etc.
Paint and varnish
Oilcloth and linoleum
Printing ink
Loss (including foots)
Principal Uses Much might be said about interchangeability through substitution of one oil for another or through diversion from one use to another, By judicious changes of formula, the soapmaker produces soaps of much the same characteristics from different combinations of fats and thus adjusts his costs to conform to the market. And for protective coatings, linseed oil competes with other unsaturated oils. But fats such as tallow or cottonseed oil, with their 16- and 18-carbon acids, are not freely interchangeable with coconut oil and its acids averaging around 12 carbons. Similarly, each of t,he unsaturated oils-for example, linseed, soybean, tung, perilla, oiticica-has its advantages and disadvantages which affect the formulation for coatings. According to the census report for 1937, there were consumed in this country nearly 5,000,000,000 pounds of glycerides (animal and vegetable) for all purposes (4): Fats and Oils Edible Inedible
Thousand Pounds 2,372,430 2,621,484
Total
159
Miscellaneous
Fat or Oil Tallow Coconut oil Palm oil Fish oil Palm kernel oil Greases Linseed oil Tung oil Perilla oil Fish oil Soybean oil Castor oil Linseed oil Fish oil Perilla. oil Tung-oiiCastor oil Soybean oil
Thousand Pounds 613,652 252,241 141,358 123,879 111,514 94,247 267,184 105,731 31,776 27,277 16,143 6,455 68,151 16,765 8,053 7,198 1,653 934
Per Cent 41.6 17.1 9.6 8.4 7.6 6.4 58.4 23 1 6.9 6.0 3.5 1.4 66.3 16.3 7.8 7.0 1.6 0.9
Linseed oil Tung oil Perilla oil Greases Fish oil Castor oil Cottonseed oil Palm oil Coconut oil Corn oil Soybean oil Sesame oil Greases Tallow Fish oi! Palm oil Castor oil
20,342 2,762 1,752 509 298 260 112,708 30,706 29,468 10,036 9,926 1,937 120,421 62,633 37,966 33,303 24,321
77.5
10.5
6.7 1.9 1.1 1.0 54.4 14.8 14.2 4.9 4.8 0.9 34.3 17.8 10.8 9.5 6.9
To provide soaps which lather freely in cold, hard, or salt water, large quantities of coconut oil and other tropical oils are used. Similar soapmaking properties are not found in animal fats or in domestic vegetable oils, so that the tropical
Per Cent 47 5 62 5
4,993,914
Of this total, 52.5 per cent or over 2.5 billion pounds were used for inedible purposes. Over half of the fat used for inedible purposes could have been prepared for edible uses if necessary. We consider here the factory consumption of primary animal and vegetable fats only for the so-called inedible uses (4): Use Soap ’ Paint and varnish Linoleum and oilcloth Printing ink Loss including foots Miscilaneous
Thousand Pounds 1,475,756 457,785 102.763 26,213 207,201 351,766
Per Cent 56.33 17.44 3.92 1.00 7.90 13.41
EQUIPMENT FOR BLEACHING FATSAND OILS BY FULLER’S EARTH
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INDUSTRIAL AND ENGINEERING CHEMISTRY
withstanding relatively high temperatures, and at the same time to nhimize its objectionable properties, such as odor. The paper industry is experimenting with the use of edible fats, especially with hydrogenated oil, for some of ita coating problems to supplement paraffi wax. For the manufacture of oilcloth and linoleum, 102,763,000 pounds or nearly 4 per cent of the total inedible fats were used (Table I), and the printing ink industry consumed 26,213,000 pounds or 1 per cent. In these fields, as in other coating fields, synthetic resins and cellulose derivatives are mpplementing the older raw materials Fable I). Of the total inedible fats, 207,201,000 pounds or nearly 8 per cent were listed as loss (Table I). This term is somewhat misleading since a large part consisted of foots from refining oils by alkali and was processed to yield soaps, fatty acids, or the so-called black grease. Other fats are recovered from the wastes of bntcher shops, households, municipalities, tin plate mills, etc. In regard to fatty acids, the census for 1933 records the consumption of over 130,M)0,000 pounds, although estimates from other sources would raise this figure to around 175,000,000 pounds. A comparison of this weight with those of other acids used in this country during the same period emphasizes the important place of fatty acids in industry (24): Acid S"1f"iiC Fatty
A DEODORIZER FOR VERBTABLEOILS oils continue to be imported to fill a definite need. Some acids of similar soapmaking properties are being prepared from petroleum and niay compete to an increasing extent. The coating industry includes the manufacture of paint, varnish, lacquer, enamel, synthetic resins, oilcloth, linoleum, printing ink, insulations, waterproofing, etc. The paint and varnish industry used 457,785,000 pounds or 17 per cent of the total inedible fat (Table I). I t continues to use more linseed oil than any other oil. It has been making large cooperative studies of raw materials and their uses aud has encouraged exchanges of information. NOWby blending linseed oil with other oils and by using the Synthetic resins and the cellulose derivatives, a wide variety of new and useful coatings has been developed. Early in the manufacture of the synthetic resins, compounds of phthalic anhydride and glycerol were invented; the glycerol, of course, was a by-product of the soap industry and was therefore produced from fats and oils. These esters have been modified and their applications broadened by replacing part of the phthalic anhydride by fatty acids. Linseed acids are used for airdrying products. Soybean acids are much used for baking finishes. More saturated acids, such as those of cottonseed oil and even of coconut oil, are employed in surprisingly large quantities. Modifications of the process allow the separate addition of glycerol and of fatty acids or of their use combined as glycerides. The choice depends largely upon market conditions. The fats have also supplied a dibasic acid for these res+namely, sebacic acid, a derivative of castor oil. Another large development has been the use of cellulose derivatives in the coating industry. Nitrocellulose requires incorporation of a plasticizer to overcome its brittleness. Castor oil, both raw and blown, has been used in large quantities along with smaller quantities of blown liieed, soybean, rapeseed, and cottonseed oils. Synthetic organic chemicals are becoming more prominent for this purpose. Much work has been done on fish oil. It is processed to retain its desirable properties of forming elastic films and OF
Carbon dioiriie Hydrochloric (300%) Nitric
Thousend Pounds 4,785,400 132.875 117 782
9o:boo 66,000
Acid AoetiC 1100% oleic
Phosphorio EiteLWi0
Tartaric
Thousand Pounda 65.150 27.890 24,653 23.874 6,788
Paper mills using the sulfate process are potential source8 of millions of pounds of fatty acids. From their waste liquors, a mixture of oleic, linoleic, and resin acids may be liberated. This mixture bas becn marketed as such and has been used for making soft soaps and emulsions. More recently, equipment and process have been developed for distilling the mixed acids and separating the fatty acids from the resin acids. Although the production of acids from petroleum and from coal-tar distillates by oxidation has been known for many years, a more recrut development has been the prodyction of glycerol from the propane of the refinery gases. Thls would make it possible to synthesiae complete fats from petroleum. Miscellaneous uses required a surprisingly large amount of fats, 351,766,000 pounds or 13 per cent of the total inedible fats. This clsssi6cation covers thc widest variety of products and uses. and its scoue can be indicated only by a few items (Table I). The recent uateut literature details compositions and uses for scores of detergent and wetting agents of all descriptions. Sulfates and sulfonates of fatty alcohols are among the newer developments. The alcohols are derived either from the natural waxes such as sperm oil or by reduction of fatty acids or of fats. In addition, over 41,000,000 pounds of glycerides were sulfonated in 1937. The textile industry is a large user of such products ( 5 ) : Sulfonated FaL castor Oil cod Oil
Tallow Tea-aeed oil "live Oil .~~ ~
~~
sperm oil Nest's-loot oil Red oil coconut oil Rspeseed oil corn Oil Miscellaneous vegetable oils Miscelianeoua animal oils All anima3 oils AU vegetsble oils
PC7"Ilds 13 088 148 8'0a1'232 5:723:660 3 4.2 558 2:&o8s 2 195 774 1'801'169
Per Cent 31.3 19.3 13.8 8.3 6.0
5.3 3.9
1:440:540
3.5 2.7
772.727 353.537 922,809 339.631
0.8 2.2
18,321,996
46.6 53.4
1.107,362
-
22,188,221
41,510,217
1.8
0.8
FEBRUARY. 1939
INDUSTRIAL AND ENGINEElUNG CHEMISTRY
Another large item was the use in 1937 of over 30,OW,OOO pounds of palm oil by the tin and terne plate industry. The plated sheets are pulled from the tin bath through a layer of molten oil to protect them from oxidation and to remove oxides of tin. The excess of oil which adheres to the sheet is absorbed in bran and may be used in stock feed. Palm oil has been used in this way for centuries, but other fats should be adaptable for the purpose. B ~ f i i ~compounds g for polishing metals and electroplated ware contain tripoli, rouge, and other abrasives held together and lubricated by stearic acid, tallow, or various soaps such as lime soap. Metallic soaps have medicinal uses and also enter into the manufacture of rubber, lubricants for wire drawing, lubricating greases, molding powders, insecticides, adhesive tape, etc. They are used for applying metallic color to ceramic wares, for desulfurizing gasoline, and other purposes. For nearly twenty years the rubber industry has used small percentages of commercial stearic acid to assist in curing some rubbers which were unsatisfactory without this addition. The use of fatty acids has grown to millions of pounds and now includes those of hydrogenated fish oil, some rather crude acids, and some of the high-acid greases. The usage is higher in the manufacture of molded goods than in other branches of the industry. Zinc laurate and similar salts are used to accelerate the cure and to soften or plasticize the rubber. Rubber substitutes are produced from vegetable oils by reaction with sulfur chloride to form the well-known Artgum, or by reaction with sulfur to form darker, more solid suhstitu&. Rapeseed oil, soybean oil, and corn oil have been preferred. Only the briefest reference can he made here to such items as stearic acid and tallow in crayons and marking pencils; castor oil io hydraulic brake fluids; lard oil in cutting oils
161
and lubricants; a wide variety of oils in tanning and finishing feather; fats, fatty acids, soaps, glycerol, mono- and diglycerides, and other fatty esters in emulsions, polishes, and creams; glycerides as fuel for Diesel engines where other oils are more expensive; the technically successful but commercially uneconomic cracking of vegetable oils to form gasoline and other hydrocarbons. These items are d r a m almost a t random to illustrate the wide adaptability of glycerides to man's needs.
Recent Developments and Future Possibilities Economic conditions are causing many of the more capable young men to pursue postgraduate training. This additional training and the increased number of such men should speed up reswch and development. There are ample fields for progress in analytical methods, in equipment, in processing, in compounding, and in applications. Improved materials of construction and better meam of maintaining high vacuum are encouraging more thorough manipulation and sharper separations of the raw materials, The fats are being taken apart more thoroughly than heretofore and can be put together again in different fashion. Development of the molecular still offers interesting pos&ilities of separating not only the vitamins and the sterols from the oils, but also of separating other materials such as unoxidiaed oils from oxidized products. The art of refining is being studied in the light of the new mechanical developments. By distilling off the free acids hefore refining with alkali, losses are reduced. Continuous proew e s of,refining, bleaching, and deodorizing are replacing the batch processes. Hydrogenation is being improved, especially hy catalysts which are more selective and more resistant to poisoning. The importance of accurate control nf temperature, rate of heating, duration of exposure, etc., is receiving increased attention. Automatic control of process conditions is being applied to a large extent. The rule of thumb is being displaced by chemical engineering data and calculations. Along with these changes in processing and equipment, other changes are being caused by the disturbed political conditions in many parts of the world. National strivings for economic self-sufficiency have upset the previous flow of raw materials and finished products. Domestically, there is the increased raising of soybeans, the planting of tung trees in our extreme southern states, and the experimental raising of perilla, safflower, and other oily seeds. This intcrest in an adequate domestic supply of fats and oils for food, for soaps, for protective coatings, and for other industrial purposes, is easily understood in the light of wars, blockades, and jeslousies. Some countries which do not raise enough fats and oils for their domestic purposes are resorting to whaling and fishing to offset this shortage. The entire whaling industry has become the subject of international committee activities. Probably the future holds t h e e things in store for us: A more thorough understanding of the components and the structure of fats and oils. Somewhat decreased domestic production of animal
duce'losses, bo provide purer oils, t o sat&te or desaturate glycerides as desired, and to supply more homogeneous glycerides made especially to suit particular CENTRIFUGAL SEPARATION OF VEQETABlE OIL FROY F O O T 8
purposes.
162
INDUSTRIAL AND ENGINEERING CHEMISTRY
A continued shifting of usages according to supplies and including animal, vegetable, and marine oils. Increased attempts to develop a substitute for coconut oil. Increased use of fatty acids as raw materials. Increased competition from petroleum derivatives and cellulose derivatives. The fats and oils, however, will continue to be used in large quantities for a wide variety of industrial purposes and will retain the major portions of their present markets.
Literature Cited (1) Baughman, W. F., and Jamieson, G. S., J . Am. Chem. SOC.,43, 2696-2702 (1921). (2) Ibid., 44,2947-52 (1922). (3) Brown, W. B., and Farmer, E. H., Biochem. J.,29,631-9 (1935). (4) Bur. of Census Bull., “Animal and Vegetable Fats and Oils” (1937). ( 5 ) Ibid., “Fats and Oils Subjected to Sulphonation during 1937” (1938).
VOL. 31, NO. 2
(6) Collin, G.,and Hilditch, T. P., J. SOC.Chem. Ind., 47, 261-9T (1928). (7) Collin, G.,Hilditch, T. P., and Lea, C. H., Ibid., 48, 46-50T (1929). (8) Hilditch, T. P.,“Industrial Chemistry of Fats and Waxes,” p. 25,London, BailliBre, Tindall and Cox, 1927. (9) Jamieson, G. S., and Baughman, W. F., J. Am. Chem. Soc., 42, 1197-1204 (1920). (IO) Jamieson, G. S., and Baughman, W. F., Oil Fat Industries, 4 131-3 (1927). J . SOC.Chem. Ind., 48,41-6T (1929). (11) Lea, C. H., (12) Milligan, C. H.,Knuth, C. A., and Richardson, A. S., J. Am. Chem. SOC.,46, 157-66 (1924). (13) Shriner, R. L., and Adarns, Roger, Ibid., 47,2727-39 (1925). (14) Statistical Abstract of U.S., p. 771 (1936). (15) Toyama, Y., and Tsuchiya, T.,Bull. Chem. SOC.Japan, 10,53943 (1935). (16) Twitchell, E.,J. IND. ENG.CHEM.,6,564-9 (1914). RECH~IVED September 12, 1938.
ALCOHOL FROM FARM PRODUCTS P. BURKE JACOBS Industrial Farm Products Research Division, Bureau of Chemistry and Soils, U. S. Department of Agriculture, Washington, D. C.
ECAUSE of the paramount importance of motor fuels in modern civilization, numerous efforts have been made in recent years to develop substitute fuels with which to supplement petroleum resources. The greatest activity in this movement has been i n foreign countries whose natural petroleum resources are inadeauate. * , emeciallv for defense needs. Since certain chemical compounds prod;cible by chemical or bacteriological processes from saccharine, starchy, or cellulosic vegetable materials, particularly ethyl alcohol, can be used with comparative success as fuel in the modern type of internal combustion engine, much of the experimentation for the production of such substitute motor fuels has been based on the use of agricultural products as raw material. In some cases this activity has been interrelated with a national agricultural program, This foreign experimentation with agricultural materials as fuel sources has aroused great interest in the United States, since here, as well as abroad, disturbed agricultural conditions have been experienced, as well as variations in farm crop prices resulting from over- or underproduction, fluctuating demand, etc. But the situation here differs from that obtaining in most of the foreign countries, since many of the countries which have resorted to the expedient of diverting crops to alcohol fuel as a means of raising farm prices or stabilizing agriculture have been mainly actuated by a need of fuel.
Means for Petroleum Conservation In this country we had originally a considerable part of the world’s supply of petroleum, and therg has as yet been little
indication of approaching shortage or need for replacement fuels. Prices of petroleum products are extremely low, in contrast to the foreign situation. However, a t the present rates of consumption eventually the supply will diminish, with corresponding price advances, and some thought should be given to the situation then to be faced. Whether our petroleum supply will last ten or twenty years is immaterial. The supply is irreplaceable, and conservation should be practiced up to the time when a better source of motive power is developed to the commercial point. But actually the use of alcohol motor fuel has been advocated in this country mainly as a farm-relief or crop-price-raising expedient rather than as a conservation measure. Such proposals bring complications into the problem. If high prices are paid to the farmer for alcohol materials to increase farm income, the cost of the alcohol becomes impractical. Any increase in farm income from alcohol fuels, therefore, must rather come from such portions of crops now unsold or unusable which could be utilized industrially without disturbance to the price structure.
Potential Sources of Farm Income The problem of uncontrolled production of crops and of unsalable surpluses which remain on hand to depress prices has recently been countered by governmental measures tending to restrict crop raising. But besides crop surpluses, for which present markets are lacking, great quantities of unmarketable culls and wastes are also produced each year and represent further loss of potential farm income. But these materials are scattered over the 6,800,000 farms of the country and are largely uncollectable for industrial use. Another loss of potential farm income attends the production of quantities of relatively perishable crops which by reason of geographical location or temporarily glutted markets cannot be sold before they deteriorate. In addition, the various crops are classified into several standard grades according to quality, and usually there is difficulty in disposing of the poorer grades. In normal production years crops are usually produced in excess of food market requirements, and some form of industrial utilization to use up any surplus above the normal carry-over should be found, es-
