Patent ID: 8030039
Filing Date: 2011-10-04
Classification: C12P,C13K,D21C,Y02E

Abstract:
1. A process for producing fermentable hemicellulose sugars from a lignocellulosic material, said process comprising: (a) contacting a lignocellulosic material with a first solution of an aliphatic alcohol, water, and a first amount of sulfur dioxide in a first stage to produce a first mixture comprising cellulose, hemicellulose oligomers, lignin, and lignosulfonates, wherein said first amount of sulfur dioxide is in a moisture-adjusted concentration of from 12 wt % to 30 wt % in said first solution within said first stage; (b) removing and recovering cellulose pulp from said first mixture, to produce a second mixture comprising hemicellulose oligomers, lignin, and lignosulfonates; (c) contacting said second mixture with a second amount of sulfur dioxide in a second stage, in the presence of heat, to further hydrolyze said hemicellulose oligomers into fermentable hemicellulose sugars, wherein said second amount of sulfur dioxide is in a concentration of from 0.05 wt % to 9 wt % in a second solution within said second stage; (d) removing at least a portion of said aliphatic alcohol from said second mixture, thereby producing a third mixture comprising fermentable hemicellulose sugars; and (e) recovering said fermentable hemicellulose sugars.