Patent ID: 8003352

Claim:
A process for obtaining a product sugar stream from cellulosic biomass comprising cellulose and hemicellulose, the process comprising: a) pretreating the cellulosic biomass at a pH of about 0.4 to about 2.0 by adding one or more than one acid to the cellulosic biomass to hydrolyze a portion of the cellulose and at least a portion of the hemicellulose in the cellulosic biomass to produce a pretreated cellulosic biomass comprising glucose, acetic acid and a sugar monomer selected from the group consisting of xylose, arabinose, mannose, galactose and a combination thereof; b) adding one or more than one base to the pretreated cellulosic biomass to adjust the pretreated cellulosic biomass to a pH of about 4.0 to about 6.0, thereby producing a neutralized cellulosic biomass comprising inorganic salt and acetate salt; c) hydrolyzing the neutralized cellulosic biomass with cellulase enzymes to produce a crude sugar stream; d) separating insoluble residue from the crude sugar stream to produce a clarified sugar stream; e) treating the clarified sugar stream by ion exclusion chromatography with a cation exchange resin at a pH from 5.0 to 10.0 to produce one or more than one raffinate stream comprising the inorganic salt and acetate salt and a product sugar stream comprising sugar, wherein the concentration of acetic acid plus acetate salt in the clarified sugar stream fed to the ion exclusion chromatography step is greater than 5 g/L; and f) recovering the product sugar stream.