Patent ID: 6228177
Filing Date: 2001-05-08
Classification: C07G,C08H,C13K,D21C

Abstract:
In a multi-function process for hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components comprising extractives and proteins; a portion of a solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass, the improvement comprising:a) introducing either solid fresh biomass or partially fractioned lignocellulosic biomass material containing entrained water or acid at pH<5.0 into a reactor and heating to a temperature from about 185.degree. C. to about 205.degree. C.;b) allowing the reaction to proceed to a point where about 60% by weight of the hemicellulose has been hydrolyzed, in the case of water only for about 6-10 minutes, or in the case when acid is present for about 5-10 minutes for complete dissolution;c) adding a dilute acid liquid at a pH below about 5.0 at a temperature of up to about 205.degree. C. for a period ranging from about 5 to about 10 minutes when water is used in step b);d) quenching the reaction at an average temperature of up to about 140.degree. C. to quench all degradation and hydrolysis reactions; ande) introducing into said reaction chamber and simultaneously removing from said reaction chamber, a volumetric flow rate of dilute acid at an average temperature of up to about 140.degree. C. to wash out the majority of the solubilized biomass components, to obtain improved hemicellulosic sugar yields and prevent recondensation reactions from occuring.