Sept., 1921
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
Of almost equal importance with the development of a process is the problem of supply of raw material. On the basis of 50 gals. to the ton, 100,000,000 tons of raw material would be required to yield the almost 5,000,000,000 gals. of motor fuel produced in the United States last gear. This is more than one-fifth of the amount of bituminous coal mined in the United States in 1919. Yet it is slightly less than the weight of hay produced in this country in the same year. Not only must there be a plentiful supply of r s w niaterial, but it must also be cheap. I f it should cost one cent a pound or twenty dollars a ton the cost of the raw material alone would be 40 cents a gallon, even on the basis of 50 gals. to the ton. The supply of raw material must be constaiit enough t o permit plants to be operated throughout the year, and the distance over which it is transported must be such that transportation charges mill be low. The solution of the problem of supply will depend largely on the success that is met with in developing a satisfactory process, and it may lie in the utilization of wmte materia.ls and the production of rapid growing piants in a climate that permits growth during the whole or a large part of the year.
It is important that a change in government regulations be. secured, in order both t o simplify and cheapen this mork.
The adaptation of motors to utilize alcohol ef3iciently as fuel will come with the development of its distribution and use as a fuel. There are no doubt a number of other aiid smaller problems which may require considerable ebort, but which will be solved if the major difficulties are overcome. The iarge amount of research n-ork which has been done in the part by a number of different investigators in an effort to make alcohol from cellulose has resulted in certain definite aiid important discoveries. It has been demonstrated that cellulose can be changed aliiiost quan-
s ;1
titatively to dextrose, which in t u m can be converted to alcohol.1 While it has been found that different materials serve a s reagents for making this hydrolysis, only strong acids have so far been found to effect a n approximately quantita€i\-e conversion of cellulose to dextrose. The cost of these materials and the dificulty of their recovery makes a process for the manufacture of motor fuel which is based upon their use f a r from commercial. But cellulosecontaining materials give a considerable yield of fermentable sugar upon being subjected to the action of very dilute acids at elevated temperatures and under pressure. This is the basis of the process that is now used in making alcohol from waste wood, and which gives a yield of from 15 to 25 gals of alcohol per ton of dry wood.? The fact that a quantitative conversion of cellulose to dextrose can be accomplished shovs the possibility of this material a s a source of alcohol, if a process can be found which will approach on the one hand, the cheapness of the dilute acid process and, on the other, the almost quantitative yields of the strcmg acid process. The progress which has so far been made in the manufacture of alcohol from cellulose, and the great necessity for and possibilities of such a process, justify a large amount of further research being put into an effort to make the preparation of a liquid motor fuel from cellulose R commercia! success. And from all iiidications it will require a great amount of further research work to accomplish this result. The success of the efforts which are being made to establish or determine the chemical structure of the cellulose molecule should make a large contribution t o the advancement of cellulose chemistry. If the production of a liquid motor fuel from cellulose can be accoinplished on a large scale, it will add greatly to the importance and burden of this widely distributed and already very vnluxble product of nature, as well as solve the problcni of the future sup1)Iy of motor fuel.
The Role of t h e Chemist in Relation t o the Future Supply of Liquid Fuel1 By Harold Hibbert Department of Chemistry, Yale University, New Haven, Connecticut
According to a recent report of the United States Geological Survey, if the rate of production of crude oil in 1920, namely, about 443,000,000 barrels, continues t o be maintained our supply of crude oil will have become entirely exhausted in about 13 years. Does the average citizen understand what this m e a n s ? In from 1 0 t o 20 years this country will be dependent entirely upon outside sources for a supply of liyuid fuel f o r f a r m tractors, motor transportation, automobiles, the generation of heat and light for the thousands of country farms, the manufacture of gas, lubricants, paraffin and the hundreds of other uses in which this indispensable r a w material finds a n application in our daily life.
It must be frankly admitted t h a t at the present moment there is no solution in sight, and it looks as if in the rather near future this country will be under the necessity of paying out vast SUMS yearly in order to obtain supplies of crude oil from Mexico, Russia and Persia. I t is believed, however, that the chemist is capable OP solving this difficult problem on the understanding khat he be given opportunities and facilities for the necessarily laborious and painstaking research work involved. We already know, for example, t h a t it is possible t o obtain alcohol from corn and a variety of grains on the Read before the Cellulose Section at the 61st Meeting of the American Chemical Society, Rochester, N. Y., April 26 to 29. 1921. 1
one hand, and from wood, on the other. Such a synthesis of liquid €Eel is, in the last resort, nothing more than the utilization of the energy supplied by the rays of the sun. Through this agent the young plant is developed, crops a r e grown and harvested and from both a liquid fuel, namely alcohol, can be manufactured. There appears to be no doubt t h a t if the latter could be obtained at a reasonable cost and in quantities sufficient for the purpose the problem would be solved, since the evidence is fairly conclusive t h a t alcohol is capable of replacing gasoline with but little alteration necessary in the present type of engine design. The problem thus becomes one of finding a sufficient supply of suitable r a w material. As indicated by Boyd,3 the available quantity of blackstrap molasses is sufficient to supply only a very small fraction of the alcohol required, while the utilization of cereals cannot be undertaken without seriously endangering the nation's food supply. On the other hand, a s indicated in the interesting communications of both Boyd and W h i t f ~ r d ,i~t would seem t h a t cellulose in one form or another should be capable of filling the role. It is known t h a t when wood (which consists of about; 50 per cent cellulose) is treated with acids i t is converted 1 Willstattcr and Zechmeister Ber. 46 (1913), 2401; H. Ost, ihid., 2985.
2 E. C. Shwrsrd, Chem. Age, i 9 (1$2r), 7G. 3 JOURNAL, 13 (1921), 836. 4 To be published later.
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T H E J O U R N A L OF I N D U S T R I A L ,4ND E N G I N E E R I N G C H E h f I S T R Y
into dextrose, which latter, on fermentation, yields ethyl alcohol, one ton of sawdust giving about 20 gallons of alcohol or roughly about 35 per cent of the theoretical quantity. On this basis the supply of wood necessary to produce 4,430,000,000 gallons (the present annual requirement assuming equal value per unit of motive power) would amount to around 221,500,000 tons, equivalent to about 14,760,000,000 cubic feet (assuming a cubic foot o f wood to weigh 30 pounds). The total amount of wood available for liquid fuel which could be secured from the forests of the United States without encroachment upon the supply of other forest products is estimated by Profesor Hawley of the Yale Forestry School a s amounting to about 11,030,000,000 cubic feet, or roughly 75 per cent of present requirements. This i s made up as follows:
... ..... . .. . 4,800,000,000 . . . . . . . . l,’iSO,000,000 . . 1,r~50,000,000 . . . . . 2,750,000,000 TOTAL, . . .11,030,000,000
Waste in the woods a n d a t the mills.. .. ... Losses from fire, insects and fungi (thinnings) . Excess of possible growth over annual cut (thinnings) . Increased growth due t o more intensive crop management (thinnings) . , .. . .. . .. ..... .. .,.. .
. . .. . . . . .
It is evident from these figures that a considerable percentage of the necessary raw material can be obtained from domestic sources, but is it available as the basis of a commercial proposition ? No definite figures a r e obtainable a s to the cost of transporting this enormous quantity of waste lumber t o suitable locations for conversion into alcohol, but the evidence indicates that it would be prohibitive under present conditions. As stated above, the present yield of alcohol is only about 20 gallons pein ton of wood, whereas, theoretically, it should be around 60. Furthermore, the present cost of Conversion, not assuming any value for the wood, cannot amount to less than approximately 20 cents per gallon. If the chemist could improve the yield considerably there is the possibility of decreasing this to around 10 cents, whereby the utilization of a wide variety of waste cellulosic material would then appear much more inviting. In view of the cost of “assembling” waste wood it would seem that products such a s flax straw, hemp hurds, sorghum, bagasse, corn straw and cobs, sugar cane and sawdust would seem to merit prior consideration, since the cost of “assembling” or “partially assembling” such materials has already been borne in connection with the manufacture of the primary raw product. The problem a s to the best and cheapest source of raw ‘cellulosic material is one which does not admit of easy solution, and the interesting and valuable data in Professor Whitford’s paper indicate the great importance of location, namely, tropical growths as compared with those of more temperate zones. His figures relative to bamboo and nipa palms a r e of interest, since they indicate that an area of the Philippines equal to some 63,300 square miles, if planted to bamboo, could probably be made to yield, by proper selection and cultivation, sufficient cellulose to supply our present demands for liquid fuel in the form of alcohol. The whole subject requires serious consideration on the part of plant physiologist, cellulose chemist and forester, and the activity at present being shown by the Government in furtherance of reforestation might, with advantage, also be extended to a study of the widest variety of “annuals” a s a source of raw material for liquid fuel. The amount of alcohol obtained on fermentation depends on the yield of sugar from the original cellulosic material, and the higher the content of this the greater the yield. In other words, if the plant physiologist could develop a rapid-growing species of tree or shrub, consisting of an outer cover of cellulose with an inner packing
Vol. 13, No. 9
of starch granules, this would presumably go a long way towards providing a solution of the problem of obtaining the necessary raw material. The task is one of such magnitude that none of the usual chemical manufacturing processes, involving only cheap chemicals and simple apparatus, need be taken into consideration, since the cost of operating by the usual methods would presumably be prohibitive. A process requiring, for example, only five pounds of any given chemical f o r the manufacture of 100 gallons of alcohol, would mean for an oulput of 4,430,000,000 gallons (the present requirements) some 100,000 tons. Similarly, each one per cent of by-products would represent about 20,000 tons. Figures such a s these would seem to indicate t h a t the solution of t h e problem will have to be found in some pi*ocess, not strictly chemical, and in which there a r e no by-products which cannot be utilized. Is there any possibility of finding such? Fortunately there is. SACCHARIFYING ORGANISMS Of all chemical processes those carried out by living organisms or enzymes are, comparatively speaking, the cheapest to operate, since the expense for labor, etc., is small, due to the efficient manner in which the tiny organisms operate. The recent work carried out by Boulard in France on the production of alcohol from starch by the action of certain alcohol-producing fungi indicates a new method of approach from which apparently much may be expected. By the action of these new agents it is claimed t h a t starch may be converted directly into alcohol, although in practice it has been found better to use the fungi only f o r converting the starch into sugar and then to ferment the latter with yeast. Much higher yields are claimed than where the saccharification is effected by acids or by malt. Large-scale experiments a r e stated to show a yield of 39 to 44 liters of pure alcohol from 100 kilograms of grain compared with 27 to 33 by the acid and 34 by the malt process. This utilization of fungi for effecting saccharification (conversion of starch, etc. into sugar) would seem to have an important bearing on the subject under discussion. The evidence which is accumulating with such extraordinary rapidity from day to day relative to t h e constitution of starch and cellulose1 indicates that they are relatively simple products, the properties of which i t is now possible to predict with some degree of certainty. There is also no doubt but that in a short time the nature of the intimate connection between these two materials will have been definitely established. This being the case, the recent work of Pringsheim2 in Germany on the aclion of certain fungi on cellulose assumes considerable importance. This scientist (not inventor, technical or consulting chemist, be i t noted, guided by the epoch-making work or‘ Euechner on fermentation and the action of ferments, has been able to show t h a t there is a strict analogy between the Permentation of certain carbohydrates such as maltose, cane sugar, starch dextrins, etc., and t h a t of cellulose, In the former cases fermentation takes place in two stages in which two different groups of ferments play an active role. These a r e the “hydrolytic” and “fermenting” types, respectively. The former bring about the 1 Karrer and Naegeli, HELVETICA CHIM. ACTA, 4 (1921), 169, 185, 2 6 3 ; Hess, Z . ELEKTROCHEM.. 26 (1920), 2 3 2 ; Karrar and Widmer, HELVETICA CHIM. ACTA, 4 (1921), 1 7 4 ; Freudenberg, BEE., 65 (1921) : Hibbert, THIS JOURNAL, 13 ( 1 9 2 1 ) , 256, 334. , 2 H a n s Pringsheirn, 2. PHYSIOL. CHEM., 78 (1912), 266. I
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T H E JOURhTAL O F I N D U S T I U A L A N D ENGINEERING CHEMISTRY
Sept., 1921
hydrolytic conversion of the maltose, starch dextrins, etc. into glucose, while the latter induce fermentation of this with formation of alcohol. Similarly under the action of certain ferments, associated with specific microijrganisms found in horsemanure, river mud, etc., cellulose is converted into glucose. The first change is brought about by the action of the hydrolytic ferment “cellulase” which converts the cellulose into cellobiose. Under the action of a second ferment “cellobiase” the cellobiose is converted into glucose. Cellobiose has recently been shown1 t o possess the structure CH~OH-CHOH-CH-CHOH-CHOH-CH-O-CH-CHOH-CHQH-CHOH-CHOH CHaQH
I__.--.-
O-----,
0-1
1
and its close relationship t o dextrose on the one hand and to cellulose on the other has been recently emphasized by various chemists, including the author.* The data obtained by Pringsheim would appear t o have an important bearing on the subject under discussion, since if it were possible t o translate the same into commercial practice, in which any type of waste cellulosic material (Vegetation, fibers, etc.) could be utilized, the probleni of a future supply of liquid fuel would seem to be much nearer a solution. E t thus becomes possible, and permissible, to draw on the imagination and t o visualize our future supply of liquid fuel as resulting from a direct conversion of the sun’s rays through the medium of vegetation, the cellulose in which, under the‘influence of specific microorganisms i s transformed first into cellobiose, secondly into glucose, and then into alcohol. This would mean the utilization of most of our waste fiber such a s corn stalks, flax, waste wood, etc., by Ihe cheapest and most economical of all processes, namely a combined saccharification-fermentation process brought about by the ceaseless activity of myriads of tiny microorganisms. The apparatus would probably consist of a simple type of vat for conducting the fermentation of the ground cellulosic material, together with stills for the rectification of the alcohol. This visualization of the important role t o be played by alcohol in the future economic life of the nation points to the imperative necessity for the fostering of anything calculated to develop and maintain the manufacture of ind u s t r i d alcohol at the highest point of efficiency. A t the moment there is some danger t h a t the recent brilliant accomplishments in this field, may, under the influence of pernicious and unenlightened legislation, be stultified to such a n extent a s not Merely t o cripple existing chemical industries, but to endanger our national standing and security, associated a s it is so intimately with t h a t of a n adequate future supply of liquid fuel for transpoitation purposes. SOURCES OTHERTHAVALCOHOL While throughout this paper especial importance has been placed on the production of alcohol, the possibility of a cheap fuel from other sources of available raw material such, f o r example, a s t h a t of furfuraldehyde €rom corncobs should not be overlooked, and the interesting results of La Forge in this field are entitled t o serious consideration, especially in view of the data submitted. Accordjng to this authority the corn waste (stalks and CObS) amounts to about 130,000,000 tons, capable of yield1 Haworth a n d Hirst, J. CHEM. SOC., 119 (1921). 193. a Priugsheim, LOC. CIT., 2 8 0 ; Hess, LOC. CIT., Karrer and Widmer, LOC. CIT., Heuser. “Lehrbueh der Cellulosechemie,” 1 9 2 1 : Hibbert, LOG. CIT.
843
ing 13,000,000 gallons of furfuraldehyde or a total of 5,900,000,000 gallons. In addition t o this there is also obtained an immense quantity of cellulose which could be convei-bed into alcohol. While the few experiments already carried out on the use of furfuraldehyde a s a motor fuel apparently indicate its unsuitability on the ground of “pre-ignition” in the motor, it is not improbable, should the necessity arise, that this could be overcome. There is also the question of the extensive deposits of shale awaiting suitable development for conversion into liquid fuel, and it may reasonably be expected t h a t exploitation of these will take place in the not-too-distant future. The important task for our domestic companies concerned with the production and marketing of gasoline, and faced with a n impending shortage‘ of their raw material in the near future, would seem to lie in intensive scientific research work in the fields of cellulose and plant chemistry on the one hand, and of bacteriology on the other. I t would be no small laurel in the crown of one of the two or three leading oil companies, t o whose ingenuity, skill, and daring the present generation owes no small part of its everyday comfort, if within the next ten years they were able to announce the completion of the first commercial unit, in which pulped cellulosic material from any source could, under the action of sturdy microorganisms be converted with theoretical yield, first into sugar and then into alcohol. Failing tlie necessary interest on tlie p a r t of the oil companies, perhaps t h a t peculiarly American genius, Mi”. Ford, might be induced t o add t o his industrial conquest of the “cheapest car,” not only “cheap fertilizer” but also “cheap synthetic fuel,” and in so doing increase still further the debt of gratitude on the part of the American public. For the moment the solution outlined above is simply a “scientific dream” but wilder phantasies than this have proved capable of realization! “Patient, intensive, scientific research” is the keynote the writer desires t o leave a s his closing phrase t o those most interested in the solution of this fascinting problem. The Bureau of Chemistry, United States Department of Agriculture has just completed a compilation of reports from the individual producers and consumers of naval stores for the 1920 producing season, which shows that 488,548 casks of gum spirits of turpentine, and 1,577,398 round barrels of gum rosin were made. There were on hand at the stills on March 31, 1921, the close of the 1920 season, 30,429 casks of spirits of turpentine and 327,055 round barrels of rosin. The following table shows the above data in comparison with t h a t for the 1919 Season 1920 Season 1919 Turps. Rosin Turps. Rosin Production from pine g u m . . . . . ,488,548 1,577,398 366,000 1,237,000 Production from wood End 30,889 159,271 180,138 still wastes . . . . . . . . . , , . . . . 34,932 Feb. 2, 1920 March 31, 1921 Stocks on hand at stills, end of $3,394 138,525 327,055 season . . . . . . . . . . . , , . . . . . ,. . . . . 30,429 Season 1919 Season 1920 Stocks a t wood distilling and rosin reclaiming plants end of calenl,i64 22,593 50,822 dar year . . . . . . . . . . . . . . . . . . . . . 7,616 Feb. 2, 1920 March 31, 1921 26,340 290,045 Stocks in hands of consumzrs.. 30,528 217,302 Stocks a t ports and yards, pri34,519 211,238 mary southern ports .. , , 60,916 432,238 Eastern ports and distributing 11,068 points , , . , . , . , . . , . . , . . , 2,568 Central distributing points. . , . . . 10,364 35,567 Western distributing points. . 848 275 Total .... . , , . , , , , . , . , . , . . . . 74,F86 ’ 479,142 Total production , , , . , , , , . . . . ,623,480 1,757,536 Exports, calendar y e a r . . , . . . ,189,168 652,023 Left for domestic u s e s . . . , , . . . ,334,312 1,106,513
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