Process for the manufacture of butanol or acetone

Abstract

A process for the manufacture of butanol, acetone and/or other renewable chemicals is provided wherein the process utilises one or more of the group comprising by-products of the manufacture of malt whisky, such as draff, pot ale and/or spent lees, biomass substrates, such as paper, sludge from paper manufacture and spent grains from distillers and brewers, and diluents, such as water and spent liquid from other fermentations. The process comprises treating a substrate to hydrolyse it and fermenting the treated substrate at an initial pH in the range of 5.0 to 6.0. Also provided is a biofuel comprising butanol manufactured according to the process of the invention.

1 . A process for the manufacture of butanol and/or acetone, comprising at least the steps of:
 treating a substrate comprising draff, or a derivative thereof, and pot ale to hydrolyse the substrate to provide a treated substrate, said draff comprising spent grain consisting essentially of malted barley; and   fermenting the treated substrate in the presence of a culture of butanol- and/or acetone-forming micro-organisms at an initial pH in the range of 5.0 to 6.0 and at a concentration of free copper ions of less than 20 μM to provide a fermented product containing butanol and/or acetone.   
     
     
         2 . The process as claimed in  claim 1  wherein the initial pH is in the range of 5.3 to 5.7. 
     
     
         3 . The process as claimed in  claim 1  wherein the fermentation step is carried out without the removal of solids therefrom. 
     
     
         4 . The process as claimed in  claim 1  wherein the draff and/or pot ale are by-products of the manufacture of malt whisky. 
     
     
         5 . The process as claimed in  claim 1  wherein the spent grain consists of 100% malted barley. 
     
     
         6 . The process as claimed in  claim 1  in which the treating and fermenting steps are carried out simultaneously. 
     
     
         7 . The process as claimed in  claim 1  in which the treating and fermenting steps are carried out sequentially. 
     
     
         8 . The process as claimed in  claim 1  wherein the substrate is diluted to lower the concentration of free copper ions to below 15 μM during at least the fermentation step. 
     
     
         9 . The process as claimed in  claim 1  wherein the draff is provided by the further steps of:
 grinding malted barley comprising starch to provide ground malted barley; 
 mixing the ground malted barley with water to provide a mash comprising water and ground malted barley; 
 hydrolysing at least a part of the starch in the ground malted barley of the mash to provide draff comprising spent barley solids and wort comprising water and one or more carbohydrates selected from the group comprising glucose and oligosaccharides of glucose; and 
 separating the draff from the wort. 
 
     
     
         10 . The process as claimed in  claim 9  wherein the pot ale is provided by the further steps of:
 adding yeast to the wort; 
 fermenting the wort to provide a wash comprising water and one or more alcohols; and 
 distilling the wash in a copper distillation vessel to provide a low wines distillate comprising one or more alcohols and a distillation residue of pot ale. 
 
     
     
         11 . The process as claimed in  claim 1  wherein the treating of the substrate to hydrolyse it comprises the step of:
 hydrolysing the substrate in the presence of water and hydrogen ions or water and hydroxide ions. 
 
     
     
         12 . The process as claimed in  claim 1  wherein the treating of the substrate to hydrolyse it comprises the step of:
 hydrolysing the substrate in the presence of an aqueous solution of sulphuric acid. 
 
     
     
         13 . The process as claimed in  claim 1  wherein the treating of the substrate to hydrolyse it comprises the step of:
 treating the substrate with one or more enzymes. 
 
     
     
         14 . The process as claimed in  claim 1  wherein the culture of butanol- and/or acetone-forming micro-organisms comprises bacteria of the genus  Clostridium.    
     
     
         15 . The process as claimed in  claim 1  wherein the fermented product further comprises one or more of the compounds selected from the group comprising ethanol, carbon dioxide, hydrogen, acetate and butyrate. 
     
     
         16 . The process according to  claim 4  wherein the malt whisky is Scotch malt whisky. 
     
     
         17 . A biofuel comprising butanol and/or acetone manufactured according to the process of  claim 1 . 
     
     
         18 - 38 . (canceled)