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Prehydrolysis and digestion of plant material

  • US 4,070,232 A
  • Filed: 05/30/1975
  • Issued: 01/24/1978
  • Est. Priority Date: 02/15/1974
  • Status: Expired due to Term
First Claim
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1. A method for treating annual, vascular plant material containing hemicellulose and lignin which comprises the steps of:

  • a. prehydrolyzing said plant material by heating said plant material under pressure in the presence of steam and the vapors of a dilute acid solution having a pH in the range from 1.5 to about 3.5 at a temperature ranging between about 105°

    C. and about 135°

    C. for between 7 minutes and about 20 minutes to hydrolyze at least a portion of said hemicellulose into pentoses and hexoses and to leave a fibrous material and a liquid, said liquid containing said pentoses and hexoses;

    b. separating said liquid from said fibrous material, and recovering the pentoses and hexoses from said liquid;

    c. heating said fibrous material under pressure in the presence of white liquor at a temperature ranging between about 105°

    C. and about 135°

    C. for a time sufficient to digest said fibrous material;

    d. separating the digested fibrous material from spent digestion liquor; and

    thene. washing the digested fibrous material.

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