USE OF LIGNOCELLULOSICS SOLVATED IN IONIC LIQUIDS FOR PRODUCTION OF BIOFUELS

• US 20080190013A1
• Filed: 02/06/2008
• Published: 08/14/2008
• Est. Priority Date: 02/06/2007
• Status: Active Grant

• Current Assignee: North Carolina State University (University of North Carolina System)
• Original Assignee: North Carolina State University (University of North Carolina System)
• Inventors: Argyropoulos, Dimitris
• Granted Patent: US 8,182,557 B2
• Time in Patent Office: Days
• US Class Current: 44/307
• CPC Class Codes: C08J 2397/02 Lignocellulosic material, e.g. wood, straw or bagasse
• CPC Class Codes: C08J 3/096 Nitrogen containing compounds
• CPC Class Codes: C10G 1/002 in combination with oil conversion- or refining processes
• CPC Class Codes: C10G 1/04 by extraction
• CPC Class Codes: C10G 2300/1014 of vegetal origin
• CPC Class Codes: C10G 3/00 Production of liquid hydrocarbon mixtures from oxygen-containing organic materials, e.g. fatty oils, fatty acids production from non-melting solid oxygen-containing carbonaceous materials C10G1/00
• CPC Class Codes: C10L 1/02 essentially based on components consisting of carbon, hydrogen, and oxygen only
• 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: 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: Y02P 30/20 using bio-feedstock

Abstract

The present invention provides a method for converting lignocellulosic material into biofuel. In particular embodiments, the method comprises pre-treating lignocellulosic material by dissolving the material in ionic liquids. The pretreated lignocellulosic material can be isolated, such as by precipitation with a regenerating solvent (e.g., water), and be used directly in the formation of biofuel, including undergoing hydrolysis to form sugar and fermentation to form fuel, such as bioethanol. The ionic liquid can be recycled for further use, such as by evaporation of the water introduced during precipitation, and the recycling provides a route to a hemicellulose rich fraction and an ionic liquid of consistent quality and wood dissolution characteristics. The recovered hemicelluloses are of significant utilization potential toward commodity and specialty applications.

Claims

1. A method of converting a lignocellulosic material into biofuel comprising pre-treating the lignocellulosic material by dissolving in ionic liquid to form a solution of dissolved lignocellulosic material in ionic liquid, and carrying out one or more further steps to convert the dissolved lignocellulosic material to a biofuel or to a reactant in the direct preparation of a biofuel.

2. The method of claim 1, wherein said dissolving comprises mixing while heating at a temperature of about 50°

C. to about 150°

C.

3. The method of claim 1, wherein said dissolving is carried out in the substantial absence of water.

4. The method of claim 3, wherein said dissolving is carried out such that the ionic liquid comprises less than about 1% by weight water.

5. The method of claim 1, wherein said dissolving is carried out in the substantial absence of a nitrogen-containing base.

6. The method of claim 5, wherein said dissolving is carried out such that the ionic liquid comprises less than about 1% by weight of a nitrogen-containing base.

7. The method of claim 1, wherein the ionic liquid comprises a material formed of a cation and an anion, wherein the cation is selected from the group consisting of imidazoles, pyrazoles, thiazoles, isothiazoles, azathiozoles, oxothiazoles, oxazines, oxazolines, oxazaboroles, dithiozoles, triazoles, delenozoles, oxaphospholes, pyrroles, boroles, furans, thiophenes, phospholes, pentazoles, indoles, indolines, oxazoles, isoxazoles, isotetrazoles, tetrazoles, benzofurans, dibenzofurans, benzothiophenes, dibenzothiophenes, thiadiazoles, pyridines, pyrimidines, pyrazines, pyridazines, piperazines, piperidines, morpholones, pyrans, annolines, phthalazines, quinazolines, guanidiniums, quinxalines, choline-based analogues, derivatives thereof, and combinations thereof, and wherein the anion is selected from the group consisting of halogens, phosphates, alkylphosphates, alkenylphosphates, BF₄⁻

, PF₆⁻

, AsF₆⁻

, NO₃⁻

, N(CN)₂⁻

, N(SO₃CF₃)₂⁻

, amino acids, substituted or unsubstituted carboranes, perchlorates, pseudohalogens, metal chloride-based Lewis acids, C_1-6 carboxylates, and combinations thereof.

8. The method of claim 7, wherein the cation is selected from the group consisting of imidazoles and pyridines, and the anion is selected from the group consisting of halogens, phosphates, alkylphosphates, alkenylphosphates, and bis(trifluoromethylsulfonyl)imide.

9. The method of claim 1, wherein the lignocellulosic material is selected from the group consisting of tobacco, corn, corn stovers, corn residues, cornhusks, sugarcane bagasse, castor oil plant, rapeseed plant, soybean plant, cereal straw, grain processing by-products, bamboo, bamboo pulp, bamboo sawdust, energy grasses, rice straw, paper sludge, waste papers, recycled paper, recycled pulp, and combinations thereof.

10. The method of claim 1, wherein the lignocellulosic material is a wood.

11. The method of claim 10, wherein the wood, prior to dissolving in the ionic liquid, is in a form selected from the group consisting of ball-milled wood powder, sawdust, thermomechanical pulp fibers, wood chips, and combinations thereof.

12. The method of claim 1, further comprising precipitating the pretreated lignocellulosic material from the ionic liquid to form a regenerated lignocellulosic material.

13. The method of claim 12, wherein the precipitation step comprises adding a regenerating solvent to the solution.

14. The method of claim 12, wherein the regenerated lignocellulosic material has a basic structure that is at least about 95% amorphous.

15. The method of claim 12, further comprising recycling the ionic liquid after precipitation of the lignocellulosic material.

16. The method of claim 15, wherein said recycling comprising removing the regenerating solvent from the ionic liquid.

17. The method of claim 1, wherein said ionic liquid comprises an ionic liquid that has been recycled from a previous pre-treatment step.

18. The method of claim 1, wherein the one or more further steps comprises isolating the lignocellulosic material from the ionic liquid and converting the isolated lignocellulosic material into a sugar.

19. The method of claim 18, wherein said converting step comprises enzymatic hydrolysis.

20. The method of claim 18, further comprising microbially converting the sugar into a biofuel.

21. The method of claim 20, wherein said microbially converting step comprises contacting the sugar with ethanol forming bacteria.

22. The method of claim 1, wherein the biofuel comprises ethanol.

23. The method of claim 1, wherein the reactant comprises glucose.

24. A regenerated lignocellulosic material, said regenerated lignocellulosic material having a basic physical structure that is at least 50% amorphous, said regenerated lignocellulosic material comprising a lignocellulosic material that, in its native state, has a basic physical structure that is less than 50% amorphous.

25. The regenerated lignocellulosic material of claim 24 comprising amorphous regenerated wood.

26. The regenerated lignocellulosic material of claim 25, wherein the basic physical structure of the regenerated wood is at least about 90% amorphous.

27. A method for preparing a highly porous, reactive lignocellulosic substrate, the method comprising:

(a) dissolving a lignocellulosic material in an ionic liquid to form a solution; and

(b) precipitating the dissolved lignocellulosic material from the ionic liquid to form the highly porous, reactive lignocellulosic substrate.

28. The method of claim 27, wherein said precipitating step comprises adding a regenerating solvent to the solution.

29. A method for isolating hemicellulose from a lignocellulosic material, said method comprising:

(a) dissolving the lignocellulosic material in an ionic liquid;

(b) regenerating the lignocellulosic material having a reduced hemicellulose content;

(c) separating the regenerated lignocellulose material from the ionic liquid to provide a recycled ionic liquid; and

(d) isolating hemicellulose from the recycled ionic liquid.

30. The method of claim 29, wherein said isolating step comprises precipitating the hemicellulose from the ionic liquid.

31. The method of claim 30, wherein said precipitating comprises adding to the recycled ionic liquid a solvent in which the hemicellulose is not soluble.