Patent ID: 8304535

Claim:
A process to produce a sugar solution from polysaccharide enriched biomass, the process comprising: a) providing a biomass comprising lignin and having a glucan/xylan weight ratio G 1 /X 1 ; b) contacting the biomass of (a) with water and at least one nucleophilic base, to form a biomass slurry having a pH of about 12.5 to about 13.0; and c) maintaining the biomass slurry under reaction conditions comprising a first temperature and first reaction time such that the slurry attains a pH of about 9.5 to about 10.0, wherein the slurry comprises a lignin-containing liquid fraction and a solid fraction comprising a polysaccharide enriched biomass wherein the biomass slurry has a glucan/xylan weight ratio G 2 /X 2 within about 15% of the value of G 1 /X 1 ; wherein G 1 and G 2 are grams of glucan per 100 grams of biomass and of biomass slurry respectively, and X 1 and X 2 are grams of xylan per 100 grams of biomass and biomass slurry respectively; d) contacting the polysaccharide enriched biomass solid fraction with an acid solution at a second temperature and for a second reaction time sufficient to produce a decrystallized biomass mixture, wherein the polysaccharides present in the polysaccharide enriched biomass solid fraction have been substantially decrystallized, and wherein the acid solution; i) comprises about 70 weight percent to about 100 weight percent sulfuric acid; or ii) comprises an acid mixture comprising phosphoric acid and sulfuric acid, wherein the molar ratio of phosphoric acid to sulfuric acid in the acid mixture is from about 3.39:1 to about 0.21:1; e) adding water to the decrystallized biomass mixture to produce a diluted biomass mixture, wherein the amount of water added is from about 20 weight percent to about 200 weight percent based on the weight of the decrystallized biomass mixture; and f) maintaining the diluted biomass mixture at a third temperature and for a third reaction time to produce a saccharification product comprising a sugar solution.