Methods for treating lignocellulosic materials

1. A method of producing high purity lignin from a biomass, comprising:

(i) removing an acidic hemicellulose sugar stream from the biomass, thereby obtaining a lignin-containing remainder; wherein the lignin-containing remainder comprises lignin and cellulose;

(ii) contacting the lignin-containing remainder with a lignin extraction solution to produce a lignin extract and a cellulosic remainder; wherein the lignin extraction solution comprises a limited-solubility solvent, an organic acid, and water;

(iii) separating the lignin extract from the cellulosic remainder; wherein the lignin extract comprises lignin dissolved in the lignin extraction solution, and wherein the limited-solubility solvent and the water form an organic phase and an aqueous phase;

(iv) removing the organic phase from the lignin extract, thereby obtaining a lignin-containing organic stream; wherein the lignin-containing organic stream comprises the limited-solubility solvent and the lignin;

(v) washing the cellulosic remainder with the limited-solubility solvent and with new water, thereby obtaining cellulose pulp;

(vi) contacting the cellulose pulp with an acid to produce an acidic hydrolysate stream comprising cellulose sugars;

(vii) contacting the acidic hydrolysate stream comprising the acid and one or more cellulose sugars with an S1 solvent extractant to form a first mixture;

(viii) separating from the first mixture an organic stream comprising the acid and the S1 solvent extractant and an aqueous stream comprising the one or more cellulose sugars;

(ix) evaporating the aqueous stream comprising the one or more cellulose sugars to form a concentrated aqueous stream;

(x) contacting the concentrated aqueous stream with the S1 solvent extractant to form a second mixture; and

(xi) separating from the second mixture a second organic stream comprising the acid and the S1 solvent extractant, and a second aqueous stream comprising the one or more cellulose sugars.

2. The method of claim 1 , wherein a ratio of the limited-solubility solvent and the water in the lignin extraction solution is about 1:1 v/v.

3. The method of claim 1 , wherein the cellulose pulp comprises lignin in an amount up to 10% weight/weight.

4. The method of claim 1 , further comprising contacting the lignin-containing organic stream with a strong acid cation exchanger to remove residual cations, thereby obtaining a purified lignin extract.

5. The method of claim 1 , further comprising separating the limited-solubility solvent from the lignin-containing organic stream, thereby obtaining high purity lignin.

6. The method of claim 5 , wherein the separating comprises evaporating the limited-solubility solvent from the lignin-containing organic stream.

7. The method of claim 6 , wherein the evaporating comprises spray drying.

8. The method of claim 1 , wherein the limited-solubility solvent is selected from methylethylketone, methylisobutylketone, diethylketone, methyl isopropyl ketone, methylpropylketone, mesityl oxide, diacetyl, 2,3-pentanedione, 2,4-pentanedione, 2,5-dimethylfuran, 2-methylfuran, 2-ethylfuran, 1-chloro-2-butanone, methyl tert-butyl ether, diisopropyl ether, anisole, ethyl acetate, methyl acetate, ethyl formate, isopropyl acetate, propyl acetate, propyl formate, isopropyl formate, 2-phenylethanol, toluene, 1-phenylethanol, phenol, m-cresol, 2-phenylethyl chloride, 2-methyl-2H-furan-3-one, γ-butyrolactone, acetal, methyl ethyl acetal, and dimethyl acetal.

9. The method of claim 1 , wherein the limited-solubility solvent is methylethylketone.

10. The method of claim 1 , further comprising

contacting the acidic hemicellulose sugar stream with an amine extractant to form a fourth mixture; and

separating from the fourth mixture (i) an amine extraction stream comprising the acid and the amine extractant and (ii) a sugar stream comprising the one or more hemicellulose sugars.

11. The method of claim 1 , further comprising adjusting pH of the lignin extract to 3.0-4.5.

12. The method of claim 1 , further comprising contacting the lignin-containing organic stream with a liquid having a temperature of less than 100° C., thereby separating the limited-solubility solvent from the lignin-containing organic stream.

13. The method of claim 12 , wherein the liquid comprises water.

14. A method of producing high purity lignin from a biomass, comprising:

(i) removing an acidic hemicellulose sugar stream from the biomass, thereby obtaining a lignin-containing remainder; wherein the lignin-containing remainder comprises lignin and cellulose;

(ii) contacting the lignin-containing remainder with a lignin extraction solution to produce a lignin extract and a cellulosic remainder; wherein the lignin extraction solution comprises a limited-solubility solvent, an organic acid, and water;

(iii) separating the lignin extract from the cellulosic remainder; wherein the lignin extract comprises lignin dissolved in the lignin extraction solution, and wherein the limited-solubility solvent and the water form an organic phase and an aqueous phase; and

(iv) contacting the organic phase with a strong acid cation exchanger to remove residual cations, thereby obtaining a purified lignin extract.

15. The method of claim 14 , wherein a ratio of the limited-solubility solvent and the water in the lignin extraction solution is about 1:1 v/v.

16. The method of claim 14 , further comprising purifying the cellulosic remainder to obtain cellulose pulp.

17. The method of claim 16 , wherein the cellulose pulp comprises lignin in an amount up to 10% weight/weight.

18. The method of claim 14 , further comprising separating the limited-solubility solvent from the purified lignin extract, thereby obtaining high purity lignin.

19. The method of claim 18 , wherein the separating comprises evaporating the limited-solubility solvent from the lignin extract.

20. The method of claim 19 , wherein the evaporating comprises spray drying.

21. The method of claim 14 , further comprising washing the cellulosic remainder with the limited-solubility solvent and with new water, thereby obtaining cellulose pulp.

22. The method of claim 21 , further comprising contacting the cellulose pulp with an acid to produce an acidic hydrolysate stream comprising cellulose sugars.

23. The method of claim 22 , further comprising

contacting the acidic hydrolysate stream comprising an acid and one or more cellulose sugars with a S1 solvent extractant to form a first mixture; and

separating from the first mixture an organic stream comprising the acid and the S1 solvent extractant and an aqueous stream comprising the one or more cellulose sugars.

24. The method of claim 23 , further comprising

evaporating the aqueous stream comprising the one or more cellulose sugars to form a concentrated aqueous stream;

contacting the concentrated aqueous stream with the S1 solvent extractant to form a second mixture; and

separating from the second mixture a second organic stream comprising the acid and the S1 solvent extractant and a second aqueous stream comprising the one or more cellulose sugars.

25. The method of claim 23 , further comprising

contacting the aqueous stream with an amine extractant to form a third mixture; and

separating from the third mixture an amine extraction stream comprising the acid and the amine extractant and a sugar stream comprising the one or more cellulose sugars.

26. The method of claim 14 , wherein the limited-solubility solvent is selected from methylethylketone, methylisobutylketone, diethylketone, methyl isopropyl ketone, methylpropylketone, mesityl oxide, diacetyl, 2,3-pentanedione, 2,4-pentanedione, 2,5-dimethylfuran, 2-methylfuran, 2-ethylfuran, 1-chloro-2-butanone, methyl tert-butyl ether, diisopropyl ether, anisole, ethyl acetate, methyl acetate, ethyl formate, isopropyl acetate, propyl acetate, propyl formate, isopropyl formate, 2-phenylethanol, toluene, 1-phenylethanol, phenol, m-cresol, 2-phenylethyl chloride, 2-methyl-2H-furan-3-one, γ-butyrolactone, acetal, methyl ethyl acetal, and dimethyl acetal.

27. The method of claim 14 , wherein the limited-solubility solvent is methylethylketone.

28. The method of claim 14 , further comprising

contacting the acidic hemicellulose sugar stream with an amine extractant to form a fourth mixture; and

separating from the fourth mixture (i) an amine extraction stream comprising the acid and the amine extractant and (ii) a sugar stream comprising the one or more hemicellulose sugars.

29. The method of claim 14 , further comprising removing the organic phase from the lignin extract, thereby obtaining a lignin-containing organic stream; wherein the lignin-containing organic stream comprises the limited-solubility solvent and the lignin.

30. The method of claim 14 , further comprising adjusting pH of the lignin extract to 3.0-4.5.

31. The method of claim 14 , further comprising contacting the purified lignin extract with a liquid having a temperature of less than 100° C., thereby separating the limited-solubility solvent from the purified lignin extract.

32. The method of claim 31 , wherein the liquid comprises water.