FRACTIONATION PROCESSES FOR HIGH-ASH LIGNOCELLULOSIC BIOMASS FEEDSTOCKS

摘要

A process for fractionating high-ash lignocellulosic biomass is provided, comprising: (a) providing a biomass feedstock comprising lignocellulosic material and ash, some of which may be removed before digestion; (b) contacting the feedstock with a digestor solution comprising a first organic solvent, an acid catalyst, and water, under effective digestor conditions and controlled acidity to produce intermediate solids and a first liquid phase comprising hemicelluloses and lignin; (c) separating the first liquid phase from the intermediate solids; (d) washing the intermediate solids with a wash solution comprising a second organic solvent and water, under effective washing conditions to produce cellulose-rich solids and a second liquid phase comprising hemicelluloses and lignin; and (e) separating the cellulose-rich solids from the second liquid phase. The solvent type is optimized to control acidity in the digestor. Controlling the acidity may also include adjusting digestor pH to a value between about 0.5 and about 2.0.