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1. (CA2743450) ORGANIC SOLVENT PRETREATMENT OF BIOMASS TO ENHANCE ENZYMATIC SACCHARIFICATION
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CLAIMS
What is claimed is:
1. A method for producing carbohydrate-enriched biomass with high retention of hemicellulose comprising: (a) providing lignocellulosic biomass comprising lignin, cellulose and hemicellulose; (b) suspending the biomass of (a) in an organic solvent solution comprising water, ammonia in an amount of about 2% to about 20% relative to weight of dry biomass and one or more nucleophile, whereby a biomass-solvent suspension is formed under alkaline conditions; (c) heating the biomass-solvent suspension to a temperature of about 100-220 °C for about 5 minutes to about 5 hours whereby lignin is fragmented and is dissolved in the suspension; and (d) filtering free liquid under pressure after heating the suspension in (c) whereby the dissolved lignin is removed and whereby carbohydrate-enriched biomass with high retention of hemicellulose is produced.
2. The method of Claim 1 further comprising: (e) washing the biomass produced in step (d) with a solvent solution.
3. The method of Claim 2, further comprising: (f) washing the biomass produced after step (e) with water whereby readily saccharifiable carbohydrate-enriched biomass is produced.
4. The method of Claim 2, further comprising drying the biomass produced in step (e) whereby readily saccharifiable carbohydrate-enriched biomass is produced.
5. The method of Claims 2 or 3, further comprising repeating steps (e) and (f) one or more times.
6. The method of Claim 1, wherein said one or more nucleophile is selected from the group consisting of NaOH, one or more alkylamines, sulfide, hydrosulfide, polysulfide, hydropolysulfide, thiol reagents, and combinations thereof.
7. The method of Claim 1 wherein the one or more alkylamines is selected from the group consisting of R-NH2, R2-NH, R3N, (H2N-RNH2), (H2N-R(NH2)2), (HO-R-NH2), ((HO)2-R-NH2), (HO-R-(NH2)2), (HS-R-NH2), ((HS)2-R-NH2), (HS-R-(NH2)2) and (H2N-R(OH)(SH) and combinations thereof, wherein R is independently a monovalent, divalent or trivalent 1-6 carbon alkane, alkene or alkyne, linear, cyclic or branched.
8. The method of Claim 7 wherein R is independently methyl, ethyl, propyl or butyl.
9. The method of Claim 7 wherein the alkylamine is methylamine.
10. The method of Claim 1 wherein the solvent solution to biomass in step (b) has a weight ratio of about 10 to 1 to 0.5 to 1.
11. The method of Claim 1, wherein the heated suspension of step (c) is cooled to room temperature before filtering in step (d).
12. The method of Claim 2 further comprising evaporating off the solvent under vacuum of the filtered and washed biomass after step (e).
13. The method of Claims 3, 4 or 12 further comprising saccharifying the biomass with enzyme consortium whereby fermentable sugars are produced.
14. The method of Claim 3, further comprising saccharifying the biomass without drying by contacting said biomass with an enzyme consortium after washing with water in step (f), whereby fermentable sugars are produced.
15. The method of Claims 13 or 14, further comprising fermenting the sugars to produce a target product.
16. The method of Claim 15 wherein the target product is selected from the group consisting of ethanol, butanol, or 1,3-propanediol.
17. The method of Claim 1 wherein the biomass is selected from the group consisting of switchgrass, waste paper, sludge from paper manufacture, corn fiber, corn cobs, corn husks, corn stover, grasses, wheat, wheat straw, hay, barley, barley straw, rice straw, sugar cane bagasse, sugar cane straw, yellow poplar, sorghum, soy, components obtained from processing of grains, trees, branches, roots, leaves, wood chips, sawdust, shrubs and bushes, vegetables, fruits, flowers, animal manure and combinations thereof.
18. A method of simultaneous fragmentation and selective extraction of lignin from lignocellulosic biomass to produce a substantially lignin-free biomass comprising: (a) providing: 1) an amount of lignocellulosic biomass comprising ligning and carbohydrate; 2) a multi-component solvent solution comprising from about 40% to about 70% ethanol in water; 3) ammonia in an amount of 2% to about 20% 4) and one or more nucleophile(s) ; (b) contacting said biomass with the multi-component solvent solution of (a) to form a solvent-biomass mixture;
(c) placing the solvent-biomass mixture in a sealed pressure vessel whereby the mixture of (b) is heated at a temperature of about 100 °C to about 220 °C for about 5 minutes to about 5 hours whereby lignin is fragmented and dissolved in the solvent; (d) removing the dissolved lignin of (c) by filtration; and (e) washing the residual with organic solvent, whereby substantially lignin-free biomass is produced.
19. The method of Claim 18 wherein the substantially lignin-free biomass is from about 60% to about 100% original weight of the biomass.
20. The method of any one of Claims 1 or 18, wherein the organic solvent solution further comprises one or additional component selected from the group consisting of alkali or alkaline earth hydroxides or carbonates, ammonia, thiols, sulfides, hydrosulfides, polysulfides, hydropolysulfides, and combinations thereof.
21. The method of claims 1 or 18 wherein the solvent solution, and any ammonia or other unreacted components are recyclable.
22. The method of claims 1 or 18 wherein said organic solvent solution comprises a solvent selected from the group consisting of alcohols, diols and aprotic solvents
23. The method of claim 22 wherein the organic solvent solution comprises a solvent selected from the group consisting of methanol, ethanol, propanol, butanol, pentanol and hexanol, isomers thereof, and diols thereof.