Inorganic salt recovery during processing of lignocellulosic feedstocks

• US 20080102502A1
• Filed: 10/25/2006
• Published: 05/01/2008
• Est. Priority Date: 10/25/2006
• Status: Active Grant

• Current Assignee: Iogen Energy Corporation (Iogen Corporation)
• Original Assignee: Iogen Energy Corporation (Iogen Corporation)
• Inventors: Anand, Vijay, Tolan, Jeffrey S., Foody, Brian, Rahme, Ziyad
• Granted Patent: US 7,670,813 B2
• Time in Patent Office: Days
• US Class Current: 435/161
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: C12P 19/02 Monosaccharides 2-ketogulonic acid C12P7/60
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

A method for recovering inorganic salt during processing of a lignocellulosic feedstock is provided. The method comprises pretreating the lignocellulosic feedstock by adding an acid or a base to the feedstock to produce a pretreated lignocellulosic feedstock. A soluble base or acid is then added to the pretreated lignocellulosic feedstock to adjust the pH and produce a neutralized feedstock. The neutralized feedstock is then hydrolyzed to produce an hydrolyzed feedstock and a sugar stream. Inorganic salt is recovered from a wash stream obtained from the pretreated lignocellulosic feedstock, a stream obtained from the neutralized feedstock, a stream obtained from the sugar stream, or a combination of these streams. The inorganic salt may be concentrated, clarified, recovered and purified by crystallization, electrodialysis, drying, or agglomeration and granulation, and then used as desired, for example, as a fertilizer.

Claims

1. A method for processing a lignocellulosic feedstock and obtaining an inorganic salt, said method comprising:

(a) pretreating the lignocellulosic feedstock by adding one or more than one soluble base to the lignocellulosic feedstock to produce a pretreated lignocellulosic feedstock;

(b) adding one or more than one acid to the pretreated lignocellulosic feedstock to adjust the pH of the pretreated lignocellulosic feedstock produce a neutralized feedstock;

(c) hydrolyzing the neutralized feedstock to produce a sugar stream and a hydrolyzed feedstock; and

(d) recovering the inorganic salt from a stream obtained from the neutralized feedstock, the sugar stream, or a combination thereof.

2. The method of claim 1, wherein the lignocellulosic feedstock is selected from the group consisting of corn stover, wheat straw, barley straw, canola straw, rice straw, oat straw, soybean stover, grass, switch grass, miscanthus, cord grass, and reed canary grass, aspen wood, sawdust, bagasse and beet pulp.

3. The method of claim 1, wherein, in the step of recovering (step (d)), the inorganic salt is recovered by ion exclusion.

4. The method of claim 3, wherein the step of recovering (step (d)) is followed by crystallization of the inorganic salt, electrodialysis, drying, or agglomeration and granulation.

5. The method of claim 1, wherein, in the step of recovering (step (d)), the inorganic salt comprises ammonium sulfate salts, ammonium phosphate salts, potassium phosphate salts, ammonium carbonate salts, ammonium chloride salts, ammonium sulfite salts, potassium sulfate salts, potassium chloride salts, or a mixture thereof.

6. The method of claim 5, wherein the salt comprises ammonium sulfate salts, ammonium phosphate salts, ammonium chloride salts, or a mixture thereof.

7. The method of claim 5, wherein the salt comprises ammonium carbonate salts.

8. The method of claim 7, further comprising decomposing the ammonium carbonate salts to form ammonia and carbon dioxide and recovering the ammonia.

9. The method of claim 3, wherein the inorganic salt is concentrated by evaporation, membrane filtration, or a combination thereof, prior to recovery to produce a concentrated solution comprising the inorganic salt.

10. The method of claim 9, wherein the concentrated solution is clarified by microfiltration, plate and frame filtration, or centrifugation prior to recovery.

11. The method of claim 1, wherein, in the step of adding acid (step (b)), the one or more than one acid is selected from the group consisting of sulfuric acid, sulfurous acid, sulfur dioxide, phosphoric acid, carbonic acid, carbon dioxide, hydrochloric acid and a combination thereof.

12. The method of claim 11, wherein the one or more than one acid is sulfuric acid.

13. The method of claim 1, wherein, in the step of pretreating (step (a)), the one or more than one soluble base is selected from the group consisting of ammonia, ammonium hydroxide, potassium hydroxide and sodium hydroxide.

14. The method of claim 13, wherein the one or more than one soluble base is selected from the group consisting of ammonium hydroxide and ammonia.

15. The method of claim 14, wherein the step of pretreating (step (a)) is performed at a temperature from about 20°

C. to about 200°

C., at a pH from about pH 9.5 to about 12 and for a time period of from about 2 to about 20 minutes.

16. The method of claim 1, further comprising the steps of:

(e) fermenting the sugar stream to produce a fermentation broth comprising ethanol; and

(f) distilling the fermentation broth to produce concentrated ethanol and still bottoms.

17. The method of claim 16, further comprising a step of recovering the inorganic salt from the still bottoms followed by purifying the inorganic salt.

18. The method of claim 17, wherein, prior to the step of recovering the inorganic salt from the still bottoms, the concentration of the still bottoms is increased by evaporation, membrane filtration, or a combination thereof, to produce concentrated still bottoms, followed by a step of ion exclusion chromatography using a simulated moving bed (SMB) process.

19. The method of claim 18, wherein the concentrated still bottoms are clarified by microfiltration, plate and frame filtration or centrifugation, prior to the step of ion exclusion chromatography.

20. The method of claim 19, wherein the step of purifying the inorganic salt comprises crystallization of the inorganic salt, electrodialysis, drying, or agglomeration and granulation.

21. The method of claim 1, wherein, in the step of hydrolyzing (step (c)), one or more than one cellulase enzyme is added to the neutralized feedstock so that at least a portion of cellulose in the neutralized feedstock is hydrolyzed to produce glucose.

22. The method of claim 1, wherein, after the step of hydrolysing (step (c)), the sugar stream is separated from the hydrolyzed feedstock to form a solid residue and a sugar hydrolyzate stream.

23. The method of claim 22, wherein the inorganic salt is concentrated by evaporation, membrane filtration, or a combination thereof.

24. The method of claim 1, wherein, in the step of hydrolyzing (step (c)), the neutralized feedstock is treated with one or more than one acid so that at least a portion of cellulose and hemicellulose in the neutralized feedstock is hydrolyzed to produce a sugar stream comprising glucose, xylose, arabinose, mannose and galactose.

25. The method of claim 1, wherein the inorganic salt is soluble.

26. The method of claim 1, wherein the inorganic salt is for use as a fertilizer.

27. The method of claim 26, wherein the inorganic salt for use as a fertilizer is selected from the group consisting of ammonium sulfate, ammonium phosphate, potassium phosphate, ammonium chloride, potassium sulfate, potassium chloride and a combination thereof.

28. A method for processing of a lignocellulosic feedstock and obtaining an inorganic salt, said method comprising:

(a) pretreating the lignocellulosic feedstock by adding one or more than one soluble base, to the lignocellulosic feedstock to produce a pretreated lignocellulosic feedstock;

(b) adding one or more than one acid to the pretreated lignocellulosic feedstock to adjust the pH of the pretreated lignocellulosic to produce a neutralized feedstock;

(c) hydrolysing the neutralized feedstock to produce a sugar stream and a hydrolyzed feedstock;

(d) fermenting the sugar stream to produce a fermentation broth comprising ethanol or butanol;

(e) separating ethanol or butanol from the fermentation broth by distillation, membrane filtration, liquid-liquid extraction or gas stripping to produce concentrated ethanol or butanol and an aqueous stream comprising the inorganic salt; and

(f) recovering the inorganic salt from the aqueous stream to produce a recovered inorganic salt.

29. The method of claim 28, further comprising the steps of purifying the recovered inorganic salt to obtain a purified inorganic salt and producing a product comprising the purified inorganic salt.

30. The method of claim 29, wherein the step of purifying comprises performing ion exclusion chromatography, followed by electrodialysis, crystallization, drying, or agglomeration and granulation.

31. A method for processing a lignocellulosic feedstock and obtaining an inorganic salt, said method comprising:

(a) pretreating the lignocellulosic feedstock by adding one or more than one soluble base comprising ammonia or ammonium hydroxide, or a combination thereof, to the lignocellulosic feedstock to produce a pretreated lignocellulosic feedstock;

(b) adding one or more than one acid comprising sulfuric acid to the pretreated lignocellulosic feedstock to adjust the pH of pretreated lignocellulosic feedstock produce a neutralized feedstock and an inorganic salt comprising ammonium sulfate; and

(c) recovering the inorganic salt from a stream obtained from the neutralized feedstock, the sugar stream, or a combination thereof.

32. The method of claim 31, wherein, in the step of recovering (step (c), the inorganic salt is recovered by ion exclusion.

33. The method of claim 32, wherein the step of recovering (step (c)) is followed by crystallization of the inorganic salt, electrodialysis, drying, or agglomeration and granulation.

34. The method of claim 31, wherein the step of pretreating (step (a)) is performed at a temperature from about 20°

C. to about 200°

C., at a pH from about pH 9.5 to about 12 and for a time period of from about 2 to about 20 minutes.

35. The method of claim 34, wherein the ammonium sulfate is for use as a fertilizer.

36. A method for processing a lignocellulosic feedstock and obtaining an inorganic salt, said method comprising:

(a) pretreating the lignocellulosic feedstock by adding one or more than one soluble base to produce a pretreated lignocellulosic feedstock;

(b) washing the pretreated lignocellulosic feedstock to produce a wash stream and a washed feedstock;

(c) neutralizing the wash stream by treatment with one or more than one acid to produce a neutralized wash stream comprising an inorganic salt; and

(d) recovering a salt comprising the inorganic salt from the neutralized wash stream.

37. The method of claim 36, wherein, in the step of recovering (step (d)), the inorganic salt comprises ammonium sulfate salts, ammonium phosphate salts, potassium phosphate salts, ammonium carbonate salts, ammonium chloride salts, ammonium sulfite salts, potassium sulfate salts, potassium chloride salts, or a mixture thereof.

38. The method of claim 37, wherein the salt comprises ammonium sulfate salts, ammonium phosphate, ammonium chloride salts, or a mixture thereof.

39. The method of claim 37, wherein the salt comprises ammonium carbonate salts.

40. The method of claim 39, further comprising decomposing the ammonium carbonate salts to form ammonia and carbon dioxide and recovering the ammonia.

41. The method of claim 36, wherein, in the step of neutralizing (step (c)), the one or more than one acid is selected from the group consisting of sulfuric acid, sulfurous acid, sulfur dioxide, phosphoric acid, carbonic acid, carbon dioxide, hydrochloric acid and a combination thereof.

42. The method of claim 36, wherein the inorganic salt is for use as a fertilizer.

43. The method of claim 36, wherein the wash stream is neutralized by treatment with a strong acid cation exchange resin.