Selective solvent extraction of cellulosic material
AssigneeMassachusetts Institute of Technology
InventorsDaniel I. C. Wang, George C. Avgerinos
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Abstract
Cellulosic products having a high hemicellulose to lignin weight ratio are obtained by extracting a cellulosic composition with basic ethanol-water solution having a pH between about 12 and about 14 at a temperature between about 15.degree. and about 70.degree. C. and for a time period between about 2 and about 80 hours.
Claims10
The process for selectively extracting lignin from a cellulosic material containing cellulose, hemicellulose and lignin in order to obtain a cellulose composition wherein the weight ratio of pentosan to lignin is at least about 5:1 and the weight ratio of cellulose and hemicellulose to lignin is at least about 10:1 and greater than 90% of the initial cellulose and pentosan is retained, which comprises contacting said material with a solvent composition comprising water, between about 40 and about 75 volume % ethanol and a base, said solvent composition having a pH between about 11 and about 14, said extraction being conducted at a temperature between about 15.degree. C. and about 70.degree. C. for a period of time of between about 2 and about 80 hours.
Dependencies are inferred from the claim text.