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Process for the simultaneous production of xylitol and ethanol

  • US 20060246563A1
  • Filed: 06/30/2006
  • Published: 11/02/2006
  • Est. Priority Date: 01/15/1990
  • Status: Active Grant
First Claim
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1. A method of processing lignocellulose-containing material from xylan-containing biomass comprising pentoses and hexoses to produce ethanol and xylitol, comprising the steps of hydrolyzing lignocellulose-containing material from xylan-containing biomass comprising pentoses and hexoses to produce a hydrolyzed solution comprising free pentoses and hexoses;

  • said lignocellulose-containing material comprising at least one lignocellulosic material selected from the group consisting of cellulose and hemicellulose, said pentoses comprising at least one pentose-containing material selected from the group consisting of xylose and arabinose;

    said hexoses comprising at least one hexose-containing material selected from the group consisting of glucose, galactose, rhamnose, mannose, and other monosaccharides;

    said xylan-containing matter selected from the group consisting of wood, hardwood, softwood, plants, plant constituents, grains, particulates of grains, stems, fiber, shells, corn cobs, corn stems, corn fibers, nutshells, almond shells, coconut shells, bagasse, cotton seed bran, cotton seed skins, wood chips, sawdust, woodpulp, processed paper, spent sulphite liquor, spent liquor from hardwood pulping, spent liquor from paper processing, spent liquor from woodpulp processing, sulphite cooking liquor, and liquids derived from any of the preceding;

    fermenting said hydrolyzed solution with microbes to produce a fermented solution comprising fermented ethanol, fermented xylitol, fermented xylose, and spent microbes, said fermenting comprising converting a substantial amount of said hexose in said hydrolyzed solution to fermented ethanol and reducing a substantial amount of said pentose in said hydrolyzed solution to fermented xylitol and fermented ethanol solution;

    said microbes comprising at least one fermenting microorganism selected from the group consisting of naturally occurring bacteria, recombinant bacteria, naturally occurring yeast, recombinant yeast, and fungi;

    wherein said microbes are capable of converting xylose to ethanol and xylitol, and capable of converting hexoses to ethanol; and

    distilling fermented liquid derived from said fermented solution to produce distilled ethanol and a distilled solution comprising distilled xylitol solution, distilled xylose and spent microbes, said distilled ethanol comprising a greater concentration of distilled ethanol by weight on a liquid basis than said fermented ethanol in said fermented solution, said distilled solution having a greater concentration of distilled xylitol solution by weight on a dry substance (solids) basis than said fermented xylitol solution in said fermented solution; and

    separating said distilled solution by fractionating said distilled solution into fractions comprising a separated xylitol-producing fraction and a separated xylose fraction, said separated xylitol-producing fraction comprising a greater concentration of xylitol-producing solution by weight on a dry substance (solids) basis than said distilled xylitol-producing solution in said distilled solution.

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