Patent ID: 8603295

Claim:
A process for producing reactive cellulose from lignocellulosic biomass having a hemicellulose content and a lignin content, comprising the steps of: (a) pretreating the lignocellulosic biomass under pressure with steam and solvent to obtain pressurized solvent washed biomass by (a1) maintaining the lignocellulosic biomass at a pressure equivalent to a saturated steam pressure at a first preselected temperature of 150° C. to 200° C. until a preselected degree of hemicellulose hydrolysis is achieved; (a2) pressing the pretreated biomass while under pressure to remove 80% to 90% of the hemicellulose hydrolyzate to obtain pretreated extracted biomass; (a3) contacting the pretreated extracted biomass while under pressure and at 180° C. to 200° C. with a solvent to hydrolyze and dissolve lignin in the pretreated extracted biomass; (a4) maintaining the pretreated extracted biomass in contact with the solvent for a selected period of time to obtain solvent treated biomass; (a5) pressing the solvent treated biomass using a modular screw device while under pressure for removing solvent and dissolved lignin; and (a6) washing the pressed solvent treated biomass under pressure by adding additional solvent to said modular screw device to remove additional lignin from the pretreated biomass mixture and further pressing the pretreated biomass mixture to obtain a pressurized solvent washed biomass; (b) generating a purified cellulose stream and a vapour stream by flashing the pressurized solvent washed biomass into a separator to subject the pressurized solvent washed biomass to explosive decompression and subsequent separation into the purified cellulose stream and the vapour stream; and (c) collecting the purified cellulose stream and recovering the solvent in the vapor stream.