Biomass Pretreatment

• US 20090053770A1
• Filed: 08/22/2007
• Published: 02/26/2009
• Est. Priority Date: 08/22/2007
• Status: Active Grant

• Current Assignee: Alliance For Sustainable Energy LLC, United States Department of Energy (Government of the United States of America), Sustainable Technology Corporation
• Original Assignee: Alliance For Sustainable Energy LLC
• Inventors: Friend, Julie, Hennessey, Susan Marie, Elander, Richard T., Tucker, Melvin P. III
• Granted Patent: US 8,445,236 B2
• Time in Patent Office: Days
• US Class Current: 435/72
• 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 7/10 substrate containing cellulosic material
• CPC Class Codes: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: D21C 11/0007 Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042
• CPC Class Codes: D21C 3/024 with NH3 or H2O
• 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

Abstract

A method is provided for producing an improved pretreated biomass product for use in saccharification followed by fermentation to produce a target chemical that includes removal of saccharification and or fermentation inhibitors from the pretreated biomass product. Specifically, the pretreated biomass product derived from using the present method has fewer inhibitors of saccharification and/or fermentation without a loss in sugar content.

Claims

1. A method for preparing an improved pretreated biomass product comprising:

a) providing biomass;

b) pretreating said biomass by contacting said biomass under suitable conditions with an aqueous solution comprising ammonia to form a biomass-aqueous ammonia mixture, 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 whereby a pretreated biomass solids product and a biomass pretreatment liquor comprising one or more inhibitor compounds is formed; and

c) removing said biomass pretreatment liquor;

wherein the pretreated biomass solids product has a reduced amount of inhibitor compounds and insubstantial reduction in sugar content.

2. The method of claim 1, further comprising adding an additional aqueous component in one or more of the following ways:

i) prior to step (b)

ii) as an additional component in step (b);

or

iii) after step (b) as a wash step.

3. The method of claim 2 wherein said additional aqueous component is selected from the group consisting of steam, water, and buffer.

4. The method of claim 3, wherein the aqueous component is steam and is added as an additional component in step (b) wherein the steam partially condenses during pretreatment to form part of the biomass pretreatment liquor.

5. The method of claim 1, further comprising the step of saccharifying the pretreated biomass solids product to form fermentable sugars.

6. The method of claim 5, further comprising fermenting the sugars of claim 5 to produce a target chemical.

7. The method of claim 1 wherein the method of liquor removal is selected from the group consisting of draining, decanting, filtering, centrifuging, and pressing.

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

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

10. 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% relative to the weight of the biomass-aqueous ammonia mixture.

11. The method of claim 10 wherein said dry weight of biomass is at a high solids concentration of from at least about 15% to about 60% relative to the weight of the biomass-aqueous ammonia mixture.

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

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

14. 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.

15. 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, corn fiber, grasses, wheat, wheat straw, hay, barley, barley straw, rice straw, sugar cane bagasse, sorghum, soy, components obtained from milling of grains, trees, branches, roots, leaves, wood chips, sawdust, shrubs and bushes, vegetables, fruits, flowers and animal manure.

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

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

18. The method of claim 1 wherein biomass is derived from multiple feedstocks.

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

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

C. to about 200°

C.

21. The method of claim 15 wherein (b) is carried out at a temperature of from about 75°

C. to about 150°

C.

22. The method of claim 16 wherein (b) is carried out at a temperature of from greater than 90°

C. to about 150°

C.

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

24. The method of claim 18 wherein (b) is carried out for a period of time of up to about 8 hours.

25. The pretreated biomass product produced by the method of claim 1.

26. A hydrolysate produced by saccharification of the pretreated biomass product that has been produced by the method of claim 1.

27. A target chemical produced by fermentation of the hydrolysate of claim 26 using a biocatalyst.

28. The target chemical of claim 27, wherein said target chemical is selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propanediol, butanediol, glycerol, erythritol, xylitol, sorbitol, acetic acid, lactic acid, propionic acid, 3-hydroxypropionic acid, butyric acid, gluconic acid, itaconic acid, citric acid, succinic acid, levulinic acid, glutamic acid, aspartic acid, methionine, lysine, glycine, arginine, threonine, phenylalanine, tyrosine, methane, ethylene, acetone, and industrial enzymes.

29. A target chemical of claim 28, wherein said target chemical is selected from the group consisting of ethanol, butanol, and propanediol.