Treatment of biomass to obtain ethanol

• US 20070031953A1
• Filed: 04/12/2006
• Published: 02/08/2007
• Est. Priority Date: 04/12/2005
• Status: Active Grant

• Current Assignee: Alliance For Sustainable Energy LLC, Sustainable Technology Corporation
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Tucker, Melvin, Elander, Richard, Hennessey, Susan, Dunson, James
• Granted Patent: US 7,998,713 B2
• Time in Patent Office: Days
• US Class Current: 435/161
• CPC Class Codes: C12M 27/02 Stirrer or mobile mixing elements
• CPC Class Codes: C12M 27/20 Baffles; Ribs; Ribbons; Auger vanes
• CPC Class Codes: C12M 45/02 by mechanical forces; Stirring; Trituration; Comminuting crushing, pulverizing, disintegrating in general B02C
• CPC Class Codes: C12M 45/09 by enzymatic treatment
• CPC Class Codes: C12P 19/02 Monosaccharides 2-ketogulonic acid C12P7/60
• CPC Class Codes: C12P 2201/00 Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
• CPC Class Codes: C12P 7/08 produced as by-product or from waste or cellulosic material substrate
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02W 10/40 Valorisation of by-products of wastewater, sewage or sludge processing

Abstract

Ethanol was produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

Claims

1. A method for producing ethanol comprising:

b) contacting biomass with an aqueous solution comprising ammonia, wherein the ammonia is present at a concentration at least sufficient to maintain alkaline pH of the biomass-aqueous ammonia mixture but wherein said ammonia is present at less than about 12 weight percent relative to dry weight of biomass, and further wherein the dry weight of biomass is at a high solids concentration of at least about 15 weight percent relative to the weight of the biomass-aqueous ammonia mixture;

b) contacting the product of step (a) with a saccharification enzyme consortium under suitable conditions to produce fermentable sugars; and

c) contacting the product of step (b) under suitable fermentation conditions with a suitable biocatalyst to produce ethanol.

2. The method of claim 1 wherein the suitable biocatalyst is selected from the group consisting of bacteria, filamentous fungi and yeast.

3. The method of claim 1 wherein the suitable biocatalyst is a wild type, mutant, or recombinant microorganism selected from the group consisting of Escherichia, Zymomonas, Saccharomyces, Candida, Pichia, Streptomyces, Bacillus, Lactobacillus, and Clostridium.

4. The method of claim 1 wherein the suitable biocatalyst is be selected from the group consisting of recombinant Escherichia coli, Zymomonas mobilis, Bacillus stearothermophilus, Saccharomyces cerevisiae, and Pichia stipitis.

5. The method of claim 1 wherein said suitable biocatalyst is recombinant Zymomonas mobilis.

6. The method of claim 1 wherein steps (b) and (c) are performed concurrently.

7. The method of claim 1 wherein the pH of the biomass-aqueous ammonia mixture is greater than 8.

8. The method of claim 1 wherein vacuum is applied to the biomass prior to contacting the biomass with an aqueous solution comprising ammonia.

9. The method of claim 1 wherein said dry weight of biomass is at a high solids concentration of from at least about 15% to about 80%.

10. The method of claim 9 wherein said dry weight of biomass is at a high solids concentration of from at least about 15% to about 60%.

11. The method of claim 1 wherein said ammonia is present at less than about 10 weight percent relative to dry weight of biomass.

12. The method of claim 11 wherein said ammonia is present at about 6% or less weight percent relative to dry weight of biomass.

13. The method of claim 1 wherein biomass is selected from the group consisting of bioenergy crops, agricultural residues, municipal solid waste, industrial solid waste, yard waste, wood and forestry waste.

14. The method of claim 1 wherein biomass is selected from the group consisting of switchgrass, waste paper, sludge from paper manufacture, corn grain, corn cobs, corn husks, corn stover, grasses, wheat, wheat straw, hay, barley, barley straw, rice straw, sugar cane bagasse, sorghum, soy, components obtained from processing of grains, trees, branches, roots, leaves, wood chips, sawdust, shrubs and bushes, vegetables, fruits, flowers and animal manure.

15. The method of claim 14 wherein biomass is selected from the group consisting of corn cobs, corn stover, corn husks, sugar cane bagasse, sawdust, switchgrass, wheat straw, hay, barley straw, rice straw, and grasses.

16. The method of claim 15 wherein biomass is selected from the group consisting of corn cobs, corn stover, sawdust, and sugar cane bagasse.

17. The method of claim 1 wherein ammonia selected from the group consisting of ammonia gas, ammonium hydroxide, urea, and combinations thereof.

18. The method of claim 1 wherein (a) is carried out at a temperature of from about 4°

C. to about 200°

C.

19. The method of claim 18 wherein (a) is carried out at a temperature of from about 75°

C. to about 150°

C.

20. The method of claim 19 wherein (a) is carried out at a temperature of from greater than 90°

C. to about 150°

C.

21. The method of claim 1 wherein (a) is carried out for a period of time of up to about 25 hours.

22. The method of claim 21 wherein (a) is carried out for a period of time of up to about 8 hours.

23. The method of claim 1 or claim 6 wherein at least a portion of the ammonia of a) is removed prior to (b).

24. The method of claim 23 wherein ammonia from (a) is recycled.

25. The method of claim 1 wherein the contacting of (b) is at a dry weight of biomass concentration of at least about 15%.

26. The method of claim 1 wherein (a), (b) or (a) and (b) are repeated at least one time.

27. The method of claim 1 further comprising adding at least one plasticizer, softening agent or combination thereof in (a).

28. The method of claim 27 wherein said at least one plasticizer, softening agent or combination thereof is selected from the group consisting of polyols, esters of polyols, glycol ethers, acetamide, ethanol, and ethanolamines.

29. The method of claim 1 further comprising applying energy before or during (a), before or during (b), or a combination thereof.

30. The method of claim 29 wherein said energy is selected from the group consisting of milling, crushing, grinding, shredding, chopping, disk refining, ultrasound and microwave.

31. The method of claim 1, wherein carbon dioxide from fermentation is used to adjust the pH of the pretreatment mixture prior to saccharification.

32. The method of claim 1 wherein said saccharification enzyme consortium comprises at least one glycosidase.

33. The method of claim 1 wherein said saccharification enzyme consortium comprises at least one enzyme selected from the group consisting of cellulose-hydrolyzing glycosidases, hemicellulose-hydrolyzing glycosidases, starch-hydrolyzing glycosidases, peptidases, lipases, ligninases and feruloyl esterases.

34. The method of claim 1 wherein said saccharification enzyme consortium comprises at least one enzyme selected from the group consisting of cellulases, endoglucanases, exoglucanases, cellobiohydrolases, β

-glucosidases, xylanases, endoxylanases, exoxylanases, β

-xylosidases, arabinoxylanases, mannases, galactases, pectinases, glucuronidases, amylases, α

-amylases, β

-amylases, glucoamylases, α

-glucosidases, isoamylases.

35. The method of claim 1 wherein (b) is performed at a temperature of from about 15°

C. to about 100°

C. and at a pH of from about 2 to about 11.