PRODUCTION OF FERMENTABLE C5 AND C6 SUGARS FROM LIGNOCELLULOSIC BIOMASS

摘要

In some variations, this invention provides a process for producing fermentable sugars from cellulosic biomass, comprising: extracting biomass with steam or hot water to produce an extract liquor containing hemicellulose oligomers, dissolved lignin, and cellulose-rich solids; separating and washing the cellulose-rich solids; removing a portion of glucan contained in the washed cellulose-rich solids as glucose oligomers using a liquefaction-focused blend of enzymes; co-hydrolyzing glucose oligomers and hemicellulose oligomers, with enzymes or chemical catalyst, to produce glucose and hemicellulose monomers; and recovering the glucose and hemicellulose monomers as fermentable sugars. The liquefaction-focused blend of enzymes contains endoglucanases and exoglucanases. Optionally, the glucose and the hemicellulose monomers may be recovered as separate streams. The residual cellulose (not hydrolyzed) as well as the lignin may be recovered and combusted, or utilized for other purposes, such as for energy-dense pellets.