Process for producing bioethanol by enzymatic hydrolysis of cellulose

• US 9,518,274 B2
• Filed: 10/05/2011
• Issued: 12/13/2016
• Est. Priority Date: 10/13/2010
• Status: Active Grant

• Current Assignee: Compagnie Industrielle De La Matiere Vegetale-Cimv
• Original Assignee: Compagnie Industrielle De La Matiere Vegetale-Cimv
• Inventors: Delmas, Michel, Benjelloun Mlayah, Bouchra
• Primary Examiner(s): Landau, Sharmila G.
• Assistant Examiner(s): MACAULEY, SHERIDAN R
• Application Number:
  US13/822,972
• Publication Number:
  US 20130183733A1
• Time in Patent Office: 1,896 Days
• Field of Search: 435/165
• US Class Current: 1/1
• CPC Class Codes: A23L 33/135 Bacteria or derivatives thereof, e.g. probiotics
• CPC Class Codes: A23V 2002/00 Food compositions, function of food ingredients or processes for food or foodstuffs
• CPC Class Codes: A23V 2250/5108 Cellulose
• 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: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

A process for producing bioethanol includes the steps of pretreatment (consisting in destructuring the lignocellulosic vegetable raw material by placing it in the presence of a mixture containing formic acid, acetic acid and water, then in separating cellulose), of enzymatic hydrolysis and of alcoholic fermentation, characterized in that it includes, prior to the enzymatic hydrolysis, a step of partial elimination of the lignins so as to obtain a residual overall level of lignins (T), expressed as percentage by weight, which is non-zero and which is included in a range determined by a lower limit, and an upper limit Bsup, respectively equal to 0.30% and 4%. In order to obtain conditions of acidification before the enzymatic hydrolysis step, the process includes a step for re-acidification of the mixture, which is carried out with an acid, or of a mixture of acids, of determined pKa, and preferably with weak organic.

Claims

1. A process for producing bioethanol from a lignocellulosic vegetable raw material, comprising:

(a) pretreatment of the lignocellulosic vegetable raw material in order to separate cellulose, hemicelluloses and lignins contained in the lignocellulosic vegetable raw material, the pretreatment comprising;

(i) destructuring the lignocellulosic vegetable raw material by placing the material in the presence of a mixture comprising formic acid and water, at a reaction temperature between 95°

C. and 110°

C.;

(ii) then, at atmospheric pressure and prior to any hydrolysis and fermentation action, separating;

a solid phase comprising said cellulose and residual lignins; and

a liquid phase, comprising a solution of water, the formic acid, the lignins and the hemicelluloses;

(b) partial elimination of residual lignins from the solid phase so as to obtain a residual overall level of lignins in a range of 0.30% to 4% by weight;

(c) enzymatic hydrolysis of said solid phase; and

(d) alcoholic fermentation of products resulting from said enzymatic hydrolysis step to produce the bioethanol.

2. The process according to claim 1, wherein the residual overall level of lignins is in a range of 0.35% to 3.5% by weight.

3. The process according to claim 2, wherein the residual overall level of lignins is equal to approximately 1.65% by weight.

4. The process according to claim 1, wherein said step of partial elimination of residual lignins is carried out by a treatment with sodium hydroxide, followed by a washing step to remove residual sodium hydroxide before the enzymatic hydrolysis step.

5. The process according to claim 1, wherein in order to obtain conditions of acidification before the enzymatic hydrolysis step, the process comprises a step of re-acidification of the mixture, which is carried out by an acid, or a mixture of acids, of determined pKa.

6. The process according to claim 5, wherein said acid is acetic acid, formic acid, citric acid, or a mixture thereof.

7. The process according to claim 6, wherein said acid is a mixture of 0.4% by weight acetic acid and 0.2% by weight formic acid.

8. The process according to claim 5, wherein after said re-acidification step, the pH of the mixture is between 4 and 6.

9. The process according to claim 8, wherein after said re-acidification step, the pH of the mixture is between 4.5 and 5.5.

10. The process according to claim 9, wherein after said re-acidification step, the pH of the mixture is equal to about 5.

11. The process according to claim 1, wherein said step for partial elimination of the lignins is carried out at a temperature between 80°

C. and 85°

C.

12. The process according to claim 1, wherein said step for partial elimination of the lignins is carried out at atmospheric pressure.

13. A process for producing bioethanol from a lignocellulosic vegetable raw material, comprising:

(a) pretreatment of the lignocellulosic vegetable raw material in order to separate cellulose, hemicelluloses and lignins contained in the lignocellulosic vegetable raw material, the pretreatment comprising;

(i) destructuring the lignocellulosic vegetable raw material by placing the material in the presence of a mixture comprising formic acid and water, at a reaction temperature between 95°

C. and 110°

C.;

(ii) then, at atmospheric pressure and prior to any hydrolysis and fermentation action, separating;

a solid phase comprising said cellulose and residual lignins, and

a liquid phase comprising a solution of water, formic acid, lignins and hemicelluloses;

(b) partial elimination of the residual lignins from the solid phase by treating the solid phase with sodium hydroxide, so as to obtain a residual overall level of lignins in a range of 0.30% to 4% by weight,

(c) re-acidification of the solid phase mixture from step (b) by treating the mixture with an acid,

(d) enzymatic hydrolysis of said re-acidified solid phase mixture from step (c); and

(d) alcoholic fermentation of products resulting from said enzymatic hydrolysis step to produce the bioethanol.

14. The process according to claim 13, wherein the partial elimination of the residual lignins comprises treating the solid phase with sodium hydroxide at a temperature of 80°

C. to 85°

C.

15. The process according to claim 13, further comprising a washing step to remove the sodium hydroxide before the re-acidification.

16. The process according to claim 13, comprising re-acidification of the solid phase mixture from step (b) by treating the mixture with acetic acid, formic acid, citric acid, or a mixture thereof.