Process for converting cellulosic materials into fuels and chemicals

Claim 1

A process for converting cellulosic material into glucose and ethanol comprising the steps of: shredding a cellulosic material to increase the surface area of the cellulosic material; mixing the shredded cellulosic material with a sufficient amount of water to form a slurry; introducing the slurry into a first reaction vessel; introducing cellulase into the first reaction vessel under conditions suitable to cause a hydrolysis reaction of the cellulose, the hydrolysis reaction forming glucose and cellobiose from the cellulose; circulating the slurry from the first reaction vessel through an attritor and then through a cellobiase reactor and back to the first reaction vessel, the attritor comprising a centrifugal pump, the attritor being in fluid communication with the first reaction vessel, the cellobiase reactor comprising a fixed bed of immobilized cellobiase, the cellobiase reactor being in fluid communication with the attritor and the first reaction vessel, the attritor providing increased surface area to the cellulosic material, the cellobiase reactor providing continuous removal of cellobiose from the first reaction vessel; recovering from the first reaction vessel a first hydrolysis product stream, the first hydrolysis product stream containing glucose, cellulase and particulate matter; filtering the first hydrolysis product stream to remove particulate matter and to form a second hydrolysis product stream, the second hydrolysis product stream containing cellulase and glucose; contacting a first sorbent with the second hydrolysis product stream at a basic pH to sorb the cellulase to form a cellulase-sorbent complex; contacting the cellulase-sorbent complex with a solution having an acidic pH to separate the cellulase from the cellulase-sorbent complex; returning the cellulase to the first reaction vessel; fermenting the glucose of the second hydrolysis product stream to ethanol by action of a biocatalyst in a biparticle fluidized-bed bioreactor, the biparticle fluidized-bed bioreactor containing the biocatalyst and a second sorbent, the biocatalyst being Zymomonas mobilis, the ethanol being sorbed by the second sorbent to form an ethanol-sorbent complex; and desorbing the ethanol from the ethanol-sorbent complex.