Efficient process for producing alcohol

Abstract

A process for producing ethanol including a combination of biochemical and synthetic conversions results in high yield ethanol production with concurrent production of high value coproducts. An acetic acid intermediate is produced from carbohydrates, such as corn, using enzymatic milling and fermentation steps, followed by conversion of the acetic acid into ethanol using esterification and hydrogenation reactions. Coproducts can include corn oil, and high protein animal feed containing the biomass produced in the fermentation.

1 - 75 . (canceled) 
     
     
         76 . A method comprising:
 a) culturing a microorganism to produce a dilute solution of a carboxylic acid salt, the cation of which is capable of producing an insoluble salt when combined with a weak acid; and,   b) chemically converting the carboxylic acid to an alcohol.   
     
     
         77 . The method of  claim 76 , wherein the microorganism is cultured in medium comprising a carbohydrate source. 
     
     
         78 . The method of  claim 77 , wherein the carbohydrate source is obtained from biomass. 
     
     
         79 . The method of  claim 78 , wherein the biomass is selected from the group consisting of grass, trees, wood, paper, corn, rice, manure, crop residue, agricultural waste, and municipal waste. 
     
     
         80 . The method of  claim 78 , wherein prior to fermentation, the biomass is treated using at least one treatment selected from the group consisting of heating and enzymatic hydrolysis. 
     
     
         81 . The method of  claim 77 , wherein at least 60% of the carbon in the carbohydrate source is converted into the alcohol. 
     
     
         82 . The method of  claim 77 , wherein essentially none of the carbon in the carbohydrate is evolved as carbon dioxide. 
     
     
         83 . The method of  claim 76 , wherein the carboxylic acid is selected from the group consisting of lactic acid and acetic acid. 
     
     
         84 . The method of  claim 76 , wherein the cation is calcium. 
     
     
         85 . The method of  claim 76  wherein the weak acid is CO 2 . 
     
     
         86 . The method of  claim 76 , wherein the insoluble salt is a carbonate salt. 
     
     
         87 . The method of  claim 76 , wherein the insoluble salt is calcium carbonate. 
     
     
         88 . The method of  claim 76 , wherein the step of culturing comprises:
 (i) producing lactic acid, lactate, or mixtures thereof, by fermentation; and   (ii) converting the lactic acid, lactate, or mixtures thereof, into acetic acid, acetate or mixtures thereof.   
     
     
         89 . The method of  claim 88 , wherein the lactic acid is converted into acetic acid by fermentation. 
     
     
         90 . The method of  claim 76 , wherein the step of culturing comprises using at least one homofermentative organism. 
     
     
         91 . The method of  claim 76 , wherein the step of culturing comprises using at least one homoacetogenic organism. 
     
     
         92 . The method of  claim 76 , wherein the step of culturing comprises using at least one organism from a genus selected from the group consisting of  Lactobacillus, Clostridium, Acetobacterium , and  Peptostreptococcus.    
     
     
         93 . The method of  claim 76 , wherein the step of culturing comprises using at least one organism selected from the group consisting of  Lactobacillus casei, Clostridium formicoaceticum , and  Clostridium thermoaceticum.    
     
     
         94 . The method of  claim 76 , wherein the alcohol is selected from the group consisting of methanol, ethanol and mixtures thereof. 
     
     
         95 . The method of  claim 76 , wherein the step of chemically converting is not fermentation. 
     
     
         96 . The method of  claim 76 , wherein the step of chemically converting comprises:
 (i) acidifying the dilute carboxylic acid salt solution with a weak acid to produce a carboxylic acid and an insoluble salt of the cation and the weak acid;   (ii) reacting the carboxylic acid with an amine to produce an acid/amine complex;   (iii) recovering and decomposing the acid/amine complex to regenerate the amine and form the carboxylic acid; and   (iv) converting the carboxylic acid to an alcohol.   
     
     
         97 . The method of  claim 96 , wherein the step of converting the carboxylic acid to an alcohol comprises forming an ester of the carboxylic acid and a second alcohol and hydrogenating the ester to produce the alcohol and recover the second alcohol. 
     
     
         98 . The method of  claim 96 , wherein the hydrogen for the step of hydrogenating is produced by a method selected from the group consisting of steam reforming, water electrolysis, gasification from biomass, partial oxidation of hydrocarbons, and partial oxidation of coal. 
     
     
         99 . The method of  claim 96 , wherein the step of converting the carboxylic acid to an alcohol comprises directly hydrogenating the carboxylic acid.