Ethanol - American Chemical Society

4 Ethanol: Manufacture and Applications

Downloaded by PENNSYLVANIA STATE UNIV on December 5, 2014 | http://pubs.acs.org Publication Date: June 15, 1981 | doi: 10.1021/bk-1981-0159.ch004

I. B. MARGILOFF, A. J. REID, and T. J. O'SULLIVAN Publicker Industries Inc., 777 West Putnam Avenue, Greenwich, CT 06830

The production of ethanol via fermentation is in many cases easier done than avoided. Few if any primitive tribes are without their alcohol beverages based on local sugars or starches, and residues from beer have been discovered in the Pyramids. Thus it is impossible to set a time when production of ethanol for beverage purposes began. Most alcohol in undeveloped countries is still for beverages. Aside from beverage production, ethanol (ethyl alcohol or "alcohol") is made for industrial purposes by both synthetic and fermentation processes. S y n t h e t i c A l c o h o l Manufacture The f i r s t s y n t h e t i c ethanol was produced by a s u b s i d i a r y of Union Carbide a t South C h a r l e s t o n , West V i r g i n i a i n the l a t e 1920*s ; thus s y n t h e t i c p r o d u c t i o n i s over 50 years o l d . In the o r i g i n a l process, ethylene gas was fed i n t o s t r o n g s u l f u r i c a c i d (around 90 per cent) a t moderate temperatures and near atmospheric pressure. The ethylene was converted l a r g e l y to e t h y l hydrogen s u l f a t e , but p a r t l y to d i e t h y l s u l f a t e . Some p o l y m e r i z a t i o n of the ethylene a l s o took place. The r i c h a c i d was then d i l u t e d w i t h water and the temperature r a i s e d , h y d r o l y z i n g the e s t e r s and d r i v i n g o f f the a l c o h o l thus produced, along w i t h e t h y l ether and the lower b o i l i n g polymers. The d i l u t e a c i d was then concentrated a t atmospheric pressure, producing a reusable a c i d but a l s o a number of troublesome by-products. S u l f u r t r i o x i d e vapor was produced as the a c i d became more concentrated. This produced an i n t o l e r a b l e f o g , so e l e c t r o s t a t i c p r e c i p i t a t o r s were i n s t a l l e d and the remaining vapor was decomposed by heat i n t o s u l f u r d i o x i d e which was d i s charged from a h i g h stack. Much of the polymerized ethylene could be removed from the weak a c i d by skimming and f i l t r a t i o n , but a c e r t a i n amount r e mained. This was p a r t i a l l y o x i d i z e d by the a c i d during concent r a t i o n , producing carbon d i o x i d e and carbon; s u l f u r d i o x i d e was another product of t h e f t ^ n t f c a f t y ^ t Q . e s s .

0097-6156/81/0159-0047$05.00/0 © 1981 American Chemical Society

In Monohydric Alcohols; Wickson, E.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.


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Vacuum c o n c e n t r a t i o n of the a c i d using Mantius, Swenson and other concentrators was used to some extent, but presented operational d i f f i c u l t i e s . Although a patent was issued as e a r l y as 1936 covering aqueous phosphoric a c i d ^ the s u l f u r i c a c i d e s t e r process was unchallenged f o r n e a r l y 20 years i n s p i t e of c o r r o s i o n and p o l l u t i o n problems, but i s no longer i n much use. Current s y n t h e t i c production uses a weaker n o n - o x i d i z i n g a c i d . A r e s p e c t a b l e r e a c t i o n r a t e r e q u i r e s higher temperatures, which s h i f t s the e q u i l i b r i u m unfavorably, and h i g h pressures. T y p i c a l l y , a r e a c t o r i s operated using phosphoric a c i d on a porous c a r r i e r w i t h a temperature around 250° C and a pressure of 70 bars. The S h e l l process uses granular s i l i c a g e l , w h i l e Veba-Cheraie (now part of Chemische Werke Huels) uses b a l l s appare n t l y made of c l a y which i s leached a f t e r f i r i n g . The s i l i c a g e l apparently produces more conversion per pass, w h i l e the Veba c a t a l y s t i s f a r more durable. "Case hardening" of s i l i c a g e l ^ g r e a t l y improves d u r a b i l i t y , and the Davison d i v i s i o n of W. R. Grace & Co. has an experimental p e l l e t e d c a t a l y s t c a r r i e r based on s i l i c a g e l which i s claimed to be even b e t t e r . T y p i c a l l y , the h y d r a t i o n occurs using 0.3 - 0.5 moles water per mole ethylene and a space v e l o c i t y around 1 min with 4-5 per cent conversion of ethylene per pass. The r e a c t i o n i s exothermic but because of low conversion the r e a c t i n g mixture does not r e q u i r e c o o l i n g . Ether i s produced but may be r e c y c l e d i f i t i s not wanted as a by-product. Increased ethylene c o n c e n t r a t i o n or temperature produces more o i l s , butanes, carbon, e t c . , w h i l e more water d i l u t e s the phosphoric a c i d and reduces i t s a c t i v i t y . Exact operating c o n d i t i o n s w i l l vary w i t h the c o n d i t i o n of the c a t a l y s t . There i s some l o s s of phosphoric a c i d i n t o the product l e a v i n g the r e a c t o r i n the form of an e t h y l e s t e r or perhaps as some species of phosphoric a c i d . I t i s replaced by e i t h e r cont i n o u s l y or i n t e r m i t t e n t l y adding makeup a c i d or by shutdowns and reirapregnation. I t i s not impossible that other a c i d s could be used i n s t e a d of phosphoric. One would look f o r an extremely n o n - v o l a t i l e a c i d , probably a t r a n s i t i o n metal oxide w i t h good r e s i s t a n c e to reduct i o n and low water s o l u b i l i t y ( t o permit more water i n the f e e d ) . One producer may be using such an a c i d . F o l l o w i n g r e a c t i o n , the ethylene gas i s scrubbed to remove the a l c o h o l and more or l e s s of the ether and i s then r e c y c l e d . A side stream i s p u r i f i e d , vented, or used i n another process. A crude s y n t h e t i c a l c o h o l i s obtained at 15 - 30 per cent a l c o h o l and contains acetaldehyde, o i l s , butanols, ether and some d i s s o l v e d C4 - C5 hydrocarbons along w i t h ethylene. I t i s d i s t i l l e d to remove low and h i g h - b o i l i n g i m p u r i t i e s and to concentrate to 190 proof. D e t a i l s of the d i s t i l l a t i o n are o f t e n p r o p r i e t a r y . A good " s p i r i t s " grade of s y n t h e t i c a l c o h o l i s at l e a s t as pure as the best fermentation a l c o h o l .


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Small amounts of s y n t h e t i c a l c o h o l occur as by-products i n various chemical processes, p a r t i c u l a r l y production of a c e t i c a c i d v i a butane o x i d a t i o n . One company i s producing about 12 m i l l i o n g a l l o n s of by-product ethanol a t present but i s not recovering i t . 3


Fermentation A l c o h o l Manufacture United States c a p a c i t y f o r fermentation i n d u s t r i a l ethanol i s estimated a t 80 - 90 m i l l i o n g a l l o n s per year but t h i s could be increased by d i v e r s i o n of d i s t i l l e d beverage production. About 10 m i l l i o n g a l l o n s of the fermentation a l c o h o l i s d e r i v e d from wastes such as s u l f i t e l i q u o r or whey, but the balance p r e s e n t l y depends on damaged g r a i n or sugar, crop surpluses and molasses. R e l a t i v e costs of ethylene and carbohydrates w i l l change t h i s i n a few years, but no r e v e r s a l to ethanol-based ethylene i s l i k e l y i n t h i s country f o r much longer, perhaps through 1990. There i s c u r e n t l y a government-sponsored program to i n crease fermentation a l c o h o l c a p a c i t y to provide m a t e r i a l f o r gasohol. The issues here are numerous and complex, and e m o t i o n a l l y - c o l o r e d e v a l u a t i o n s are c l e a r l y evident even among those who profess to have purely s c i e n t i f i c or t e c h n i c a l i n t e r e s t s . B a r r i n g a d r a s t i c r i s e i n g r a i n p r i c e s the program i s l i k e l y to continue. The basic process f o r fermentation a l c o h o l i s l i t t l e changed over the l a s t hundred years. T y p i c a l l y the g r a i n i s ground, s l u r r i e d w i t h water and cooked. The cooking process causes the s t a r c h granules to take i n water, s w e l l and e v e n t u a l l y rupture. This releases the s t a r c h molecules i n t o the mash as long chain d e x t r i n s which are i n turn broken down by the a c t i o n of a s a c c h a r i f y i n g enzyme to simple sugars. Yeast i s added to the mixture, and the sugars are converted to a l c o h o l and carbon d i o x i d e . The fermented mash, now c a l l e d beer, i s s t r i p p e d of i t s a l c o h o l by d i s t i l l a t i o n . The spent beer which c o n s i s t s of the non-fermentable p o r t i o n s of the g r a i n i s separated i n t o two f r a c t i o n s , the s o l u b l e s and i n s o l u b l e s . The s o l u b l e p o r t i o n i s evaporated to produce a syrup c o n t a i n i n g 35 - 50 per cent t o t a l s o l i d s . This can be marketed as i s or d r i e d with the i n s o l u b l e p o r t i o n to form d i s t i l l e r s d r i e d g r a i n s w i t h s o l u b l e s DDGS. The i n s o l u b l e f r a c t i o n can be marketed wet or d r i e d to form d i s t i l l e r s d r i e d grains DDG. These by-products are u s u a l l y sold as d a i r y r a t i o n supplements, e s p e c i a l l y the wet g r a i n s and whole s t i l l a g e f r a c t i o n s . Molasses fermentation i s more s t r a i g h t f o r w a r d , as the m i l l ing and s a c c h a r i f y i n g operations are not needed. The molasses i s d i l u t e d to 15 - 20 per cent sugars, depending on c o n d i t i o n s , f e r mented, d i s t i l l e d and the remainder evaporated to a syrup. However, t h i s syrup can only be used i n s m a l l p r o p o r t i o n s f o r 4



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feeding because of i t s high potassium content. Alfa-Laval-* i s promoting a process f o r reducing t h i s potash l e v e l i n the syrup and o b t a i n i n g potassium f o r f e r t i l i z e r use and r e t u r n to the land. The s u l f i t e process f o r paper-making produces a c e r t a i n amount of wood sugars which cannot be sewered because of p o l l u t i o n laws. Fermentation permits recovery of the sugar as a l c o h o l and s i n g l e c e l l p r o t e i n . A commercial plant i s i n o p e r a t i o n . An economically i d e a l s u b s t r a t e f o r fermentation i s c e l l u l o s e . However, i t i s a s s o c i a t e d w i t h l i g n i n which i n h i b i t s h y d r o l y s i s of the c e l l u l o s e to simple sugars. The e a r l i e s t s t u d i e s of ethanol production v i a h y d r o l y s i s of c e l l u l o s e were c a r r i e d out i n Germany during World War I . At that time two proceses were developed; the weak a c i d S c h o l l e r process and the strong Rheinau technique. Studies on the enzymatic h y d r o l y s i s of c e l l u l o s e were i n i t i a t e d during World War I I to t r y to f i n d a remedy f o r the m i c r o b i o l o g i c a l degradation of s o l d i e r s u n i forms. However, i t i s only w i t h i n the l a s t ten years that a renewed i n t e r e s t i n h y d r o l y s i s of c e l l u l o s e has taken place and c e l l u l a s e enzymes are now being developed. V a r i a t i o n s of a c i d h y d r o l y s i s processes are being i n v e s t i gated. C e r t a i n f u n g i , e s p e c i a l l y Trichoderma r e e s e i , can a l s o degrade c e l l u l o s e to sugars. To date, most r e s u l t s of c e l l u l o s e type enzymatic degradations produce only low sugar c o n c e n t r a t i o n s (e.g. 50 - 60 per cent y i e l d a t 5 - 10 per cent g l u c o s e ^ ) . The technology though not the b a s i c process associated w i t h fermentation has developed c o n s i d e r a b l y over the l a s t f i f t y years. One of the major breakthroughs was the M e l l e process f o r the reuse of yeast. This was developed by Les Usines de Melle'' and i n c o r p o r a t e d the use of c e n t r i f u g e s to recover yeast from the beer p r i o r to d i s t i l l a t i o n . This yeast was i n t u r n used to i n o c u l a t e the next fermentor. The process has three major advantages: 1. the e f f i c i e n c y of fermentation i n c r e a s e s , reaching the Pasteur t h e o r e t i c a l , 2. fermentation takes place a t a f a s t e r r a t e , and 3. the cost of yeast replacement i s c o n s i d e r a b l y reduced. The a c c l i m a t i o n of the yeast c e l l s to the p a r t i c l u a r s u b s t r a t e combined with the l a r g e numbers account f o r the f i r s t two advantages, and the t h i r d can be costed out on the b a s i s of yeast cost versus purchase and o p e r a t i o n of c e n t r i f u g e s . C e l l recovery i s mainly concerned w i t h what i s known as c l e a r mash, i . e . sugar s o l u t i o n s without any e n t r a i n e d s o l i d s suchas as those i n a whole-grain mash. The use of c e l l recovery on mash can be accomplished by c l a r i f y i n g the mash p r i o r to fermentation or e l s e i n c o r p o r a t i n g a w e t - m i l l i n g f r o n t end and t a k i n g the s a c c h a r i f i e d s t a r c h as s u b s t r a t e . However the product i o n of a c l e a r mash d i r e c t l y from c e r e a l mash i s p r e s e n t l y not f e a s i b l e . This i s due to excessive l o s s e s of carbohydrate i n the cake or non-fermentable e x t r a c t ranging from 10 to 20 per 1



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cent of t o t a l s t a r c h . This cake even, w i t h a higher carbohydrate content than DDG, i s not as valuable as DDG because of i t s lower protein concentration. Taking the idea of yeast recovery one step f u r t h e r i s continuous fermentation. This i n c o r p o r a t e s a v e s s e l o r v e s s e l s i n o c u l a t e d w i t h yeast through which the fermentable s u b s t r a t e i s passed c o n t i n u o u s l y . The flow i s designed to ensure that a l l the sugar i s fermented before i t e x i t s the f i n a l ferraenter as beer. This beer i s c l a r i f i e d to remove any e n t r a i n e d yeast c e l l s and a percentage of the yeast i s r e c y c l e d back i n t o the system. The excess can be f u r t h e r processed depending on the market a p p l i c a t i o n , i . e . f o r human o r animal use. A great amount of time, money and e f f o r t i s being devoted t o the use of c e l l u l o s e as a feedstock f o r the production of e t h a n o l . The s t u d i e s i n c o r p o r a t e chemical or enzymatic conversion of the c e l l u l o s e to glucose and the conversion of t h i s to ethanol w i t h yeast (Saccharomyces) or b a c t e r i a (Zymomonas). However, a t h i r d process i s p r e s e n t l y under development at Massachusetts I n s t i t u t e of Technology whereby the d i r e c t conversion of c e l l u l o s e to ethan o l i s being attempted without a separate h y d r o l y s i s step.** This i s accomplished by u t i l i z i n g two separate microorganisms which work s y m b i o t i c a l l y w i t h each other, C l o s t r i d i u m thermo— cellum and C l o s t r i d i u m thermosaccharolyticum to produce e t h a n o l . The research i s s t i l l i n i t s infancy and s e v e r a l years of r e search and development are a n t i c i p a t e d before i t s use commercially. W i t h i n the l a s t ten years phenomenal advances i n the f i e l d of genetic engineering have taken place. I t i s hoped, but not yet demonstrated, that gene s p l i c i n g may lead to major advances i n the production of a l c o h o l , but c a r e f u l l y c o n t r o l l e d use of conventional microorganisms i s now the best p o t e n t i a l route to good economics. Applications S y n t h e t i c a l c o h o l demand i n the United States i n 1979 was estimated at 208 m i l l i o n g a l l o n s (190 p r o o f ) . ^ The same source l i s t s 94 m i l l i o n g a l l o n s f o r chemical manufacture, 42 m i l l i o n f o r t o i l e t r i e s and cosmetics, 25 m i l l i o n f o r detergents, f l a v o r s and d i s i n f e c t a n t s , 23 m i l l i o n f o r coatings and 25 m i l l i o n f o r other uses. S y n t h e t i c a l c o h o l i s not used i n beverages o r gasohol (motor f u e l ) . Fermentation a l c o h o l has been used almost e n t i r e l y f o r beverage purposes i n l e s s developed c o u n t r i e s . In i n d u s t r i a l i z e d n a t i o n s , even w i t h a v a i l a b l e ethylene, fermentation a l c o h o l i s produced from low-cost surplus and waste m a t e r i a l s . With the s h i f t i n economics i t w i l l compete w i t h s y n t h e t i c i n the l a t t e r * s f i e l d s . I t has a monopoly of "gasohol" f o r p o l i t i c a l reasons and of beverages f o r emotional reasons. Fermentation a l c o h o l c a p a c i t y i n the United States i s u n c e r t a i n but i s estimated a t


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about 100 m i l l i o n g a l l o n s per year apart from beverages (65 m i l l i o n g a l l o n s produced i n 1978 c a p a c i t y not a v a i l a b l e ) . As many as 70 products were at one time produced commerc i a l l y from e t h a n o l . Some of these downstream products are butanol, 2 - e t h y l hexanol, crotonaldehyde, butyraldehyde, a c e t aldehyde, a c e t i c a c i d , butadiene, s o r b i c a c i d , 2 - e t h y l b u t a n o l , e t h y l ether, many e s t e r s , e t h a n o l - g l y c o l e t h e r s , a c e t i c anhydride, v i n y l a c e t a t e , e t h y l v i n y l e t h e r , even ethylene gas. Many of these products are now more economically made from other feedstocks such as ethylene f o r acetaldehyde and raethanol-carbon monoxide f o r a c e t i c a c i d . Time w i l l t e l l when a r e v i v a l of b i o l o g i c a l l y - o r i e n t e d processes w i l l o f f e r lower-cost routes to at l e a s t the s i m p l e r products. Recent Developments The outstanding recent development i n e t h y l a l c o h o l i s "gasohol", a blend of fermentation e t h a n o l (10 per cent) w i t h inn LU

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g a s o l i n e . I t was s t u d i e d thoroughly about 50 years ago- > - but forced out by cheap o i l . The a l c o h o l must be n e a r l y 200 proof, e s p e c i a l l y i n c o l d areas. Apart from extending the petroleum supply d i r e c t l y , i t permits use of lower-base octane g a s o l i n e and thus i n d i r e c t l y f u r t h e r increases the y i e l d of g a s o l i n e per b a r r e l of crude o i l . Cooler engine temperatures reduce engine wear and p o l l u t i o n . Views on gasohol are h e l d , o f t e n q u i t e e m o t i o n a l l y , and s p l i t i n t o two camps. The opponents c l a i m the energy r e q u i r e d to produce the a l c o h o l i s g r e a t e r than the energy i t c o n t a i n s . They ignore the f a c t that gasohol seems to g i v e the same gas mileage as g a s o l i n e i n s p i t e of a lower Btu content per g a l l o n and t h a t g a s o l i n e i t s e l f i s subject to the same c r i t i c i s m . Their energy values are suspect because e x i s t ing d i s t i l l e r i e s poor energy economics are a legacy of the age when energy was cheap; there has been no demand f o r b e t t e r technology u n t i l r e c e n t l y . The proponents of gasohol are o f t e n o r i e n t e d toward the a g r i c u l t u r a l b e n e f i t s of i n c r e a s i n g the demand f o r c e r e a l g r a i n s and other ferraentables. The middle ground i s c l e a r l y to be p r e f e r r e d ; some a l c o h o l w i l l be made f o r motor f u e l out of economically a v a i l a b l e s u b s t r a t e s , but we cannot r e a l i s t i c a l l y expect or demand that a l l motor f u e l s o l d i n t h i s country have ten per cent fermentation a l c o h o l based s o l e l y on f o o d s t u f f s . Several s u p p l i e r s of motor f u e l are c o n s i d e r i n g c o n t r a c t s and j o i n t ventures with a l c o h o l producers or b u i l d i n g p l a n t s independently. One view would suspect the choice of p o s i t i o n s may r e f l e c t a company's a b i l i t y to produce premium unleaded g a s o l i n e i n d e s i r e d amounts or i t s c r u d e - o i l p o s i t i o n . A second recent development i s increased i n t e r e s t i n the conversion of c e l l u l o s e to fermentable sugar f o r conversion to a l c o h o l . The enzymatic conversion i s thus f a r not w e l l enough developed to be s u c c e s s f u l commercially, although break1



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throughs may come any day. This new i n t e r e s t has been spurred on by d i m i n i s h i n g petroleum stocks and r i s i n g p r i c e s . I t i s envisaged that c e l l u l o s e , the most abundant polysaccharide i n nature, w i l l f u l f i l l part of our l i q u i d f u e l needs. A c i d hydrol y s i s i s f e a s i b l e , i n f a c t was p r a c t i c e d i n Europe during World War I I to provide motor f u e l , but t h i s route i s now no more than m a r g i n a l l y p r o f i t a b l e . The readjustments of energy and raw m a t e r i a l costs now t a k i n g place w i l l i n e v i t a b l y b r i n g about d e s i r a b l e t e c h n i c a l developmetns i n c l u d i n g more f a v o r a b l e energy balances. Use of s t r a i g h t 190-proof a l c o h o l (95 volume per cent) as an automobile f u e l i s being pushed i n B r a z i l and may f i n d a place i n l e s s temperate c l i m a t e s as w e l l . The need f o r production of anhydrous a l c o h o l f o r gasohol has s t i m u l a t e d a search f o r new methods to replace the c o n v e n t i o n a l ternary azeotrope method based on benzene o r cyclohexane. Adsorption and e x t r a c t i v e d i s t i l l a t i o n along with other azeotroping agents and o p e r a t i o n a t v a r i o u s pressures are a l s o being mentioned. F i n a l l y , i t should be noted that commercial production of ethanol by continuous fermentation of g r a i n mash has r e p o r t e d l y been achieved a t Archer-Daniels-Midland Company and that N a t i o n a l D i s t i l l e r s researchers have a l s o developed such a process. Although continuous fermentation, per se, i s not new there i s some s k e p t i c i s m concerning the degree to which t h i s represents a r e a l t e c h n i c a l and economic advance. A few other comments: Ethanol i s l i s t e d by OSHA as a suspect but unproved carcinogen, but OSHA does not have j u r i s d i c t i o n over beverage a l c o h o l , nor, s i n c e i t i s a n a t u r a l product, does the Delaney Amendment apply. This could lead to p a r a d o x i c a l s i t u a t i o n s . Ethanol w i l l continue to grow e x p l o s i v e l y i n volume i n the next few years as a motor f u e l ; indeed, t h i s has happened i n B r a z i l . The f i e l d i s extremely v o l a t i l e , and new developments occur every week, p a r t i c u l a r l y w i t h respect to fermentation and gasohol. Things should be c l e a r e r i n about f i v e years, and we should remind ourselves to take a s i m i l a r look a t ethanol then. 1


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Literature Cited 1.

U.S. Patent 2,050,445; August 11, 1936 "Manufacture of Ethyl Alcohol", Floyd J . Metzger Assignee: Air Reduction Company, New York, New York

2.

U.S. Patent 3,914,721; October 21, 1975 "Combination Specular-Diffuse Projection Device and Method", John S. Pollock, Rochester, New York Assignee: Eastman Kodak Company, Rochester, New York

3.

Chemical Marketing Reporter, July 16, 1979, Vol. 217, No. 3 Chem Profile, page 9.

4.

Anon. Chem Week, 1980, Vol 127, No. 19, page 41

5.

Company literature, Alfa-Laval

6.

"Molasses & Industrial Alcohol", Development Centre, OECD, Paris, 1978

7.

Canadian Patent No. 341,720; May 15, 1934 "Alcoholic Fermentation", Les Usines de Melle Canadian Patent No. 402,847; February 10, 1942 "Alcohol Production by Fermentation", Les Usines de Melle Canadian Patent No. 348,549

8.

Wang, D.I.C., R. J. Fleischaker and G. Y. Wang, Chemical Engineering Progress Symposium Series, 1978

9.

Johnston, P.J., Ethanol: An Alternative to Its Use as Fuel, Workshop on Fermentation Alcohol in Developing Countries, March 26 - 30, 1979

10.

Christensen, L.M., Hixon, R.M., Fulmer, E . J . , "Power Alcohol and Farm Relief", The Deserted Village, No. 3; Iowa State College, Ames, Iowa, 1934

11.

"Use of Alcohol from Farm Products in Motor Fuel", Letter from the Secretary of Agriculture to the Senate, May 3, 1933, Senate Document No. 57, 73rd Congress, 1st Session

12.

Bishop, J.E., Wall Street Journal, November 14, 1980, p. 27

RECEIVED

March 3, 1 9 8 1 .


Ethanol - American Chemical Society

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