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

• Current Assignee: Goran Hyoky, Heikki Heikkila, Heikki Ojamo, Leena Rahkila, Marja-Leena Sarkki, Olli-Pekka Eroma, Paivi Sarmala, Tapio Viljava
• Original Assignee: Goran Hyoky, Heikki Heikkila, Heikki Ojamo, Leena Rahkila, Marja-Leena Sarkki, Olli-Pekka Eroma, Paivi Sarmala, Tapio Viljava
• Inventors: Sarmala, Paivi, Hyoky, Goran, Eroma, Olli-Pekka, Sarkki, Marja-Leena, Heikkila, Heikki, Viljava, Tapio, Ojamo, Heikki, Rahkila, Leena
• Granted Patent: US 7,625,728 B2
• Time in Patent Office: Days
• US Class Current: 435/158
• CPC Class Codes: B01D 61/025 Reverse osmosis; Hyperfiltration
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: C12P 7/12 substrate containing sulfite waste liquor or citrus waste
• CPC Class Codes: C12P 7/18 polyhydric
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y10S 435/911 using fungi
• CPC Class Codes: Y10S 435/921 Candida
• CPC Class Codes: Y10S 435/924 Candida tropicalis

Abstract

Effective processes are provided for the production of xylitol and ethanol and other products from solutions derived from lignocellulose-containing material in biomass. The solutions can be hydrolyzed or partially hydrolyzed before being fermented with microbes. The fermented solution can be distilled and can be subsequently separated, such as, by chromatographic separation, membrane separation, etc. The recovered xylitol solution can be crystallized to provide pure xylitol crystals.

Claims

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.

2. A method according to claim 1 including crystallizing said xylitol to produce crystalline xylitol.

3. A method according to claim 1 wherein said xylitol comprises liquid xylitol.

4. A method according to claim 1 wherein:

said hydrolyzed solution is subjected to at least one treatment selected from the group consisting of;

pH adjustment, concentration, filtration, filtering with a pressure filter, filtering with diatomaceous earth, chromatographic separation, detoxification, removing inhibitors, overliming, calcium hydroxide addition, sodium hydroxide addition, activated charcoal, extraction with organic solvents, ion exchange, ion exclusion, molecular sieves, steam stripping, heating, removing furfural, stripping volatile compounds, and reduction of said hydrolyzed solution by sulphite addition;

said xylitol solution selected from the group consisting of a xylitol-rich solution and a xylose-rich solution;

said xylitol solution having a greater concentration of at least one compound on a dry substance (solids) basis than said compound in said hydrolyzed solution; and

said compound is selected from the group consisting of xylitol, xylose, arabinose, mannose, and galactose and rhamnose.

5. A method according to claim 4 wherein:

said separating comprises chromatographic separation; and

said chromatographic separation is selected from the group consisting of batch separation, continuous simulated moving bed separation, and sequential simulated moving bed separation.

6. A method according to claim 4 wherein:

said separating comprising filtering; and

said filtering is selected from the group consisting of membrane filtration, ultrafiltration, nanofiltration, and microfiltration.

7. A method according to claim 6 wherein:

said filtering comprises passing said distilled solution through at least one membrane; and

said membrane is selected from the group consisting of a high shear membrane, a vibrating membrane, a rotating membrane, a flat sheet membrane, a tubular membrane, a spiral membrane, a hollow fiber membrane, a neutral charged membrane, an ionic membrane, a cationic membrane, and an anionic membrane.

8. A method according to claim 1 further comprising crystallizing said xylitol fraction to produce xylitol crystals.

9. A method according to claim 8 wherein said crystallization is selected from the group consisting of cooling crystallization, evaporation crystallization, both cooling crystallization and evaporation crystallization, and a combination of cooling crystallization and evaporation crystallization.

10. A method according to claim 9 wherein said xylitol crystals are separated by centrifugation or filtration and washed with water to produce substantially pure crystalline xylitol.

11. A method according to claim 1 including hydrogenating said separated xylose fraction to produce hydrogenated xylitol.

12. A method according to claim 11 further comprising crystallizing said hydrogenated xylitol to produce xylitol crystals.

13. A method according to claim 1 including:

separating a substantial portion of said spent microbes from said fermented solution prior to said distilling to produce said fermented liquid derived from said fermented solution;

said fermented liquid comprising fermented ethanol, fermented xylitol, fermented xylose, and spent microbes;

said fermented liquid comprising substantially less spent microbes by weight on a dry substance (solids) basis that said spent microbes in said fermented solution; and

said separating of said substantial portion of said spent microbes from said fermented solution comprising at least one separating method selected from the group consisting of filtration, centrifugation, and decanting.

14. A method according to claim 1 including removing a substantial amount of solids from said hydrolyzed solution before fermenting, said removing comprising at least one removal step selected from the group consisting of filtration, centrifugation and decanting.

15. A method according to claim 1 wherein said hydrolyzing is selected from the group consisting of enzymatic hydrolysis of said lignocellulose-containing material with enzymes having a cellulolytic and xylanolytic activity to hydrolyze said lignocellulose-containing material, and acid hydrolysis of said lignocellulose-containing material.

16. A method according to claim 1 including pretreatment of said lignocellulose-containing material before said hydrolyzing, said pretreatment comprising at least one pretreatment method selected from the group consisting of prehydrolysis of said lignocellulose-containing material, steam explosion of said lignocellulose-containing material, alkaline treatment, solvent extraction, partial hydrolysis of said lignocellulose-containing material, and extraction by alkali, NaOH or —

NH4OH of said lignocellulose-containing material.

17. A method according to claim 1 wherein said hydrolyzed solution comprises biomass hydrolysates.

18. A method according to claim 17 wherein said biomass hydrolysates are obtained by a process selected from the group consisting of direct acid hydrolysis of said biomass, enzymatic prehydrolysate obtained by prehydrolysis of said biomass with steam or acetic acid;

acid hydrolysis of prehydrolysate obtained by prehydrolysis of said biomass with steam or acetic acid, a sa-prehydrolysis process, autohydrolysis using water or steam, and a sulphite pulping process.

19. A method according to claim 17 wherein said biomass hydrolysates are selected from the group consisting of spent sulphite pulping liquor, acid spent sulphite liquor, spent liquor from hardwood pulping, spent liquor from softwood pulping before hexoses are removed, spent liquor from softwood pulping after hexoses are removed, spent liquor from digestion of said biomass, spent liquor from hydrolysis of said biomass, spent liquor from solvent-based pulping, spent liquor from phenol based pulping, spent liquor from formic acid based pulping, spent liquor from ethanol-based pulping, mother liquor from crystallization of xylose, and diluted runoff of xylose crystallization of sulphite spent pulping liquor based liquor.

20. A method according to claim 1 wherein:

said pentose in said processed solution comprises arabinose; and

said arabinose is reduced to arabinitol during said fermentation.

21. A method according to claim 1 wherein said fermenting microorganism is a yeast selected from the group consisting of a yeast of the genera Candida, Pichia, Pachysolen, or Debaryomyces.

22. A method according to claim 21 wherein said yeast is selected from the group consisting of Candida shehatae CBS 2779 (ATCC60778), Candida tropicalis ATCC 9968 and Pachysolen tannophilus NRRL Y-2460 (=A TCC32691).

23. A method according to claim 22 wherein said fermenting occurs at a temperature ranging from about 10 to about 45 degrees C. at a pH ranging from 4 to 7 with a yeast concentration of about 1 to about 40 g of dry yeast per liter of hydrolyzed solution for about 24 to about 96 hours in the presence of at least one nutrient.