# US 9,518,274 B2 · Process for producing bioethanol by enzymatic hydrolysis of cellulose

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- Number: US 9,518,274 B2
- Document ID: US9518274B2
- Status: Granted
- Kind: B2
- Application number: 13/822,972
- Filed: 2011-10-05
- Published: 2013-07-18
- Granted: 2016-12-13
- Earliest claimed: 2010-10-13
- Assignees: Compagnie Industrielle De La Matiere Vegetale-Cimv
- Applicants: Michel Delmas; Bouchra Benjelloun Mlayah
- Inventors: Michel Delmas; Bouchra Benjelloun Mlayah
- Web page: https://patentgrep.com/patent/US9518274B2

## CPC

- C12P 7/10: substrate containing cellulosic material
- A23L 33/135: Bacteria or derivatives thereof, e.g. probiotics
- C13K 1/02: obtained by saccharification of cellulosic materials (manufacture of fodder A23K10/32)
- A23V 2002/00: Food compositions, function of food ingredients or processes for food or foodstuffs
- C12P 2201/00: Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
- Y02E 50/10: Biofuels, e.g. bio-diesel
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}
- A23L: FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES, NOT OTHERWISE PROVIDED FOR; PREPARATION OR TREATMENT THEREOF (preservation thereof A23B)
- C13K: SACCHARIDES OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DISACCHARIDES, OLIGOSACCHARIDES OR POLYSACCHARIDES (chemically synthesised sugars or sugar derivatives C07H; polysaccharides, e.g. starch, derivatives thereof C08B; malt C12C; fermentation or enzyme-using processes for preparing compounds containing saccharide radicals C12P19/00; production of sucrose C13B)
- A23V: INDEXING SCHEME RELATING TO FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES AND LACTIC OR PROPIONIC ACID BACTERIA USED IN FOODSTUFFS OR FOOD PREPARATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## 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

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 2)

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

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 5)

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

### Claim 7 (depends on 6)

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.

### Claim 8 (depends on 5)

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

### Claim 9 (depends on 8)

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

### Claim 10 (depends on 9)

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

### Claim 11 (depends on 1)

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.

### Claim 12 (depends on 1)

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

### Claim 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.

### Claim 14 (depends on 13)

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.

### Claim 15 (depends on 13)

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

### Claim 16 (depends on 13)

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.