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Methods for treating lignocellulosic materials

  • US 9,783,861 B2
  • Filed: 11/10/2014
  • Issued: 10/10/2017
  • Est. Priority Date: 05/03/2012
  • Status: Active Grant
First Claim
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1. A method of producing high purity lignin from a biomass, comprising:

  • (i) removing an acidic hemicellulose sugar stream from the biomass, thereby obtaining a lignin-containing remainder;

    wherein the lignin-containing remainder comprises lignin and cellulose;

    (ii) contacting the lignin-containing remainder with a lignin extraction solution to produce a lignin extract and a cellulosic remainder;

    wherein the lignin extraction solution comprises a limited-solubility solvent, an organic acid, and water;

    (iii) separating the lignin extract from the cellulosic remainder;

    wherein the lignin extract comprises lignin dissolved in the lignin extraction solution, and wherein the limited-solubility solvent and the water form an organic phase and an aqueous phase;

    (iv) removing the organic phase from the lignin extract, thereby obtaining a lignin-containing organic stream;

    wherein the lignin-containing organic stream comprises the limited-solubility solvent and the lignin;

    (v) washing the cellulosic remainder with the limited-solubility solvent and with new water, thereby obtaining cellulose pulp;

    (vi) contacting the cellulose pulp with an acid to produce an acidic hydrolysate stream comprising cellulose sugars;

    (vii) contacting the acidic hydrolysate stream comprising the acid and one or more cellulose sugars with an S1 solvent extractant to form a first mixture;

    (viii) separating from the first mixture an organic stream comprising the acid and the S1 solvent extractant and an aqueous stream comprising the one or more cellulose sugars;

    (ix) evaporating the aqueous stream comprising the one or more cellulose sugars to form a concentrated aqueous stream;

    (x) contacting the concentrated aqueous stream with the S1 solvent extractant to form a second mixture; and

    (xi) separating from the second mixture a second organic stream comprising the acid and the S1 solvent extractant, and a second aqueous stream comprising the one or more cellulose sugars.

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