Indirect production of butanol and hexanol

Abstract

A process for the conversion of carbohydrates from any of a number of sources into butanol and hexanol for fuel or chemical use is disclosed. The process includes conducting a homoacetogenic fermentation to produce an acetic acid intermediate which is chemically converted to ethanol. The ethanol and a remaining portion of the acetic acid intermediate are used as a substrate in an acidogenic fermentation to produce butyric and caproic acid intermediates which are then chemically converted to butanol and hexanol.

1 . A method to produce butanol and hexanol, comprising:
 (a) treating biomass to produce a fermentation medium comprising carbohydrates;   (b) culturing a homoacetogenic fermentation in a the fermentation medium to produce acetate, acetic acid or mixtures thereof;   (c) chemically converting a portion of the acetate, acetic acid or mixtures thereof to ethanol;   (d) conducting an acidogenic fermentation in a medium comprising the ethanol and a portion of the acetate, acetic acid or mixtures thereof to produce butyrate, butyric acid, caproate, caproic acid or mixtures thereof; and   (e) chemically converting the butyrate, butyric acid, caproate, caproic acid or mixtures thereof to the butanol and hexanol.   
     
     
         2 . The method of  claim 1 , wherein at least about 70% of carbon in the carbohydrate is converted into the butanol and hexanol. 
     
     
         3 . The method of  claim 1 , wherein at least about 80% of carbon in the carbohydrate is converted into the butanol and hexanol. 
     
     
         4 . The method of  claim 1 , wherein at least about 90% of carbon in the carbohydrate is converted into the butanol and hexanol. 
     
     
         5 . The method of  claim 1 , wherein essentially none of the carbon in the carbohydrate is evolved as carbon dioxide. 
     
     
         6 . The method of  claim 1 , wherein the step of chemically converting a portion of the acetate, acetic acid or mixtures thereof to ethanol comprises acidifying the homoacetogenic fermentation medium to convert acetate to acetic acid; esterifying the acetic acid; and reducing the acetic acid ester to form ethanol. 
     
     
         7 . The method of  claim 6 , wherein the step of acidifying comprises introducing carbon dioxide or an acid with a lower pKa than acetic acid to the fermentation medium comprising a salt of acetic acid. 
     
     
         8 . The method of  claim 6 , wherein said step of acidifying comprises introducing an amine to the fermentation medium to form an acetic acid/amine complex. 
     
     
         9 . The method of  claim 8 , further comprising contacting the acid/amine complex with a water immiscible solvent to form an ester of the water immiscible solvent and the acetic acid. 
     
     
         10 . The method of  claim 1 , wherein the step of chemically converting butyrate, butyric acid, caproate, caproic acid or mixtures to butanol and hexanol comprises acidifying the acidogenic fermentation medium to convert butyrate and caproate to butyric acid and caproic acid; esterifying the butyric acid and caproic acid; and reducing the butyric acid and caproic acid esters to form butanol and ethanol. 
     
     
         11 . The method of  claim 10 , wherein the step of acidifying comprises introducing carbon dioxide or an acid with a lower pKa than butyric acid and caproic acid to the fermentation medium comprising a salt of butyric acid and caproic acid. 
     
     
         12 . The method of  claim 10 , wherein said step of acidifying comprises introducing an amine to the fermentation medium to form butyric acid/amine and caproic acid/amine complexes. 
     
     
         13 . The method of  claim 12 , further comprising contacting the acid/amine complexes with a water immiscible solvent to form an ester of the water immiscible solvent and the butyric acid and an ester of the water immiscible solvent and the caproic acid. 
     
     
         14 . The method of  claim 6 , wherein a reductant for the step of reducing is produced by thermochemical processing of a portion of the biomass. 
     
     
         15 . The method of  claim 14 , wherein the thermochemical processing is selected from the group consisting of gasification, pyrolysis, reforming, and partial oxidation. 
     
     
         16 . (canceled) 
     
     
         17 . The method of  claim 6 , wherein the step of reducing is selected from the group consisting of hydrogenation, hydrogenolysis and reduction by carbon monoxide. 
     
     
         18 . The method of  claim 1 , wherein the step of conducting a homoacetogenic fermentation in a medium comprises culturing a microorganism of the genus  Moorella  or  Clostridium  in the medium. 
     
     
         19 . The method of  claim 1 , wherein the step of conducting a homoacetogenic fermentation in a medium comprises culturing a microorganism of the species  Moorella thermoaceticum  or  Clostridium formicoaceticum  in the medium. 
     
     
         20 . The method of  claim 1 , wherein the step of conducting an acidogenic fermentation in a medium comprises culturing a microorganism of the genus  Clostridium  in the medium. 
     
     
         21 . The method of  claim 1 , wherein the step of conducting an acidogenic fermentation in a medium comprises culturing a microorganism of the species  Clostridium kluyveri  in the medium. 
     
     
         22 . (canceled) 
     
     
         23 . The method of  claim 2 , wherein the step of treating comprises fractionating the material to form a carbohydrate-containing fraction for homoacetogenic fermentation, and to form a residue fraction comprising lignin for conversion to a product by a thermochemical conversion process. 
     
     
         24 . The method of  claim 23 , wherein the product of the thermochemical conversion process is used in the step of chemically converting a portion of the acetate, acetic acid or mixtures thereof to ethanol or the step of chemically converting the butyrate, butyric acid, caproate, caproic acid or mixtures thereof to the butanol and hexanol or both. 
     
     
         25 . The method of  claim 23 , wherein the step of fractionating is selected from the group consisting of physical treatment, metal ion treatment, ultraviolet light treatment, ozone treatment, oxygen treatment, organosolv treatment, steam explosion treatment, lime impregnation with steam explosion treatment, lime impregnation without steam treatment, hydrogen peroxide treatment, hydrogen peroxide/ozone (peroxone) treatment, acid treatment, dilute acid treatment, and base treatment. 
     
     
         26 . (canceled) 
     
     
         27 . The method of  claim 1 , wherein the biomass comprises herbaceous matter, agricultural residue, forestry residue, municipal solid waste, waste paper, pulp or paper mill residue. 
     
     
         28 . The method of  claim 1 , wherein the biomass comprises trees, shrubs, grasses, wheat, wheat straw, wheat midlings, sugar cane bagasse, corn, corn husks, corn kernel, corn fiber, municipal solid waste, waste paper, yard waste, branches, bushes, energy crops, fruits, fruit peels, flowers, grains, herbaceous crops, leaves, bark, needles, logs, roots, saplings, short rotation woody crops, switch grasses, vegetables, vines, sugar beet pulp, oat hulls, hard woods, wood chips, intermediate streams from pulping operations or soft woods. 
     
     
         29 . (canceled) 
     
     
         30 . The method of  claim 1 , wherein the carbohydrates make up less than about 75% by weight of the carbon-containing compounds in the biomass and the chemical energy efficiency of the method is at least about 50%. 
     
     
         31 . The method of  claim 1 , wherein the carbohydrates make up less than about 75% by weight of the carbon-containing compounds in the biomass and the chemical energy efficiency of the method is at least about 60%. 
     
     
         32 . The method of  claim 1 , wherein the carbohydrates make up less than about 75% by weight of the carbon-containing compounds in the biomass and the chemical energy efficiency of the method is at least about 70%. 
     
     
         33 . The method of  claim 1 , wherein the carbohydrates make up less than about 75% by weight of the carbon-containing compounds in the biomass and the yield of butanol and hexanol is at least about 100 gal/BDT of carbohydrate source. 
     
     
         34 . The method of  claim 1 , wherein the carbohydrates make up less than about 75% by weight of the carbon-containing compounds in the biomass and the yield of butanol and hexanol is at least about 120 gal/BDT of carbohydrate source. 
     
     
         35 . The method of  claim 1 , wherein the carbohydrates make up less than about 75% by weight of the carbon-containing compounds are carbohydrate substances in the biomass and the yield of butanol and hexanol is at least about 140 gal/BDT of carbohydrate source. 
     
     
         36 - 76 . (canceled) 
     
     
         77 . The method of  claim 10 , wherein a reductant for the step of reducing is produced by thermochemical processing of a portion of the biomass. 
     
     
         78 . The method of  claim 10 , wherein the step of reducing is selected from the group consisting of hydrogenation, hydrogenolysis and reduction by carbon monoxide.