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Method of treating biomass material

  • US 5,536,325 A
  • Filed: 06/06/1994
  • Issued: 07/16/1996
  • Est. Priority Date: 03/23/1979
  • Status: Expired due to Term
First Claim
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1. A method of hydrolyzing lignocellulosic material containing hemicellulose, cellulose and lignin which comprises the following steps:

  • (a) subjecting such material to a first stage hydrolysis step in an aqueous medium and in comminuted form at a temperature and a pressure chosen to effect primarily depolymerization of hemicellulose without major depolymerization of cellulose to glucose, such step resulting in a slurry in which the liquid aqueous phase contains dissolved monosaccharides resulting from depolymerization of hemicellulose and a solid phase containing cellulose and lignin(b) separating from the product of step (a) at least a portion of such liquid aqueous phase(c) also separating from the product of step (a) the solid phase and subjecting it to attrition(d) subjecting the separated solid phase which has been subjected to attrition in step (c), in the form of an aqueous slurry, to a second stage hydrolysis step under conditions such that at least a major portion of the cellulose is depolymerized, such step resulting in a liquid aqueous phase containing dissolved therein the soluble depolymerization products of cellulose, such conditions being chosen to minimize the degradation of the depolymerization products of cellulose(e) separating from the product of step (d) at least a major portion of such liquid aqueous phase and(f) also separating from such product the undissolved solids(g) the various steps (a) through (f) being carried out under conditions to minimize the loss of heat from the system and to minimize the times of exposure of solutions resulting from steps (a) and (d) to elevated temperature.

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