Method for the production of alcohol from a pretreated lignocellulosic feedstock
First Claim
1. A process for increasing the hydrolysis of cellulose in the production of alcohol from a lignocellulosic feedstock, comprising the steps of:
- (i) pretreating a lignocellulosic feedstock under conditions to produce a composition comprising a pretreated lignocellulosic feedstock having a disrupted fiber structure and increased accessibility of the feedstock to being hydrolyzed;
(ii) enzymatically hydrolyzing the pretreated lignocellulosic feedstock with cellulase enzymes to produce a hydrolyzate slurry comprising glucose and unhydrolyzed cellulose;
(iii) fermenting said hydrolyzate slurry to produce a fermentation broth comprising alcohol and unhydrolyzed cellulose;
(iv) separating the alcohol from the fermentation broth by distillation to obtain a stream comprising concentrated alcohol and a still bottoms stream comprising the unhydrolyzed cellulose and the cellulase enzymes, said distillation resulting in heat treatment of the unhydrolyzed cellulose, which heat treatment is conducted at a temperature between 70 and 200°
C. so as to denature the cellulase enzymes; and
(v) further hydrolyzing at least a portion of the still bottoms stream with cellulase enzymes to convert at least a portion of the unhydrolyzed cellulose present in said still bottoms stream to glucose, thereby increasing cellulose hydrolysis.
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Abstract
A process for the production of glucose from a pretreated lignocellulosic feedstock is provided. The method comprises enzymatically hydrolyzing the pretreated lignocellulosic feedstock with cellulase enzymes to produce a hydrolyzate slurry comprising glucose and unhydrolyzed cellulose and fermenting the hydrolyzate slurry in a fermentation reaction to produce a fermentation broth comprising alcohol. A process stream is obtained comprising unhydrolyzed cellulose, which is then subjected to a denaturing step, preferably comprising exposing the unhydrolyzed cellulose to elevated temperatures, thereby producing a heat-treated stream comprising the unhydrolyzed cellulose. The heat-treated stream comprising unhydrolyzed cellulose is then further hydrolyzed with cellulase enzymes to hydrolyze the cellulose to glucose.
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Citations
18 Claims
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1. A process for increasing the hydrolysis of cellulose in the production of alcohol from a lignocellulosic feedstock, comprising the steps of:
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(i) pretreating a lignocellulosic feedstock under conditions to produce a composition comprising a pretreated lignocellulosic feedstock having a disrupted fiber structure and increased accessibility of the feedstock to being hydrolyzed; (ii) enzymatically hydrolyzing the pretreated lignocellulosic feedstock with cellulase enzymes to produce a hydrolyzate slurry comprising glucose and unhydrolyzed cellulose; (iii) fermenting said hydrolyzate slurry to produce a fermentation broth comprising alcohol and unhydrolyzed cellulose; (iv) separating the alcohol from the fermentation broth by distillation to obtain a stream comprising concentrated alcohol and a still bottoms stream comprising the unhydrolyzed cellulose and the cellulase enzymes, said distillation resulting in heat treatment of the unhydrolyzed cellulose, which heat treatment is conducted at a temperature between 70 and 200°
C. so as to denature the cellulase enzymes; and(v) further hydrolyzing at least a portion of the still bottoms stream with cellulase enzymes to convert at least a portion of the unhydrolyzed cellulose present in said still bottoms stream to glucose, thereby increasing cellulose hydrolysis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A process for improving cellulose hydrolysis in the production of ethanol from a lignocellulosic feedstock, comprising the steps of:
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(i) pretreating a lignocellulosic feedstock under conditions to produce a composition comprising a pretreated lignocellulosic feedstock having a disrupted fiber structure and increased accessibility of the feedstock to being hydrolyzed; (ii) enzymatically hydrolyzing the pretreated lignocellulosic feedstock with cellulase enzymes to produce a hydrolyzate slurry comprising glucose and unhydrolyzed cellulose; (iii) fermenting said hydrolyzate slurry to produce a fermentation broth comprising ethanol; (iv) separating the ethanol from the fermentation broth by distillation to obtain a stream comprising concentrated ethanol and a remaining still bottoms stream comprising unhydrolyzed cellulose and the cellulase enzymes, said distillation resulting in heat treatment of the unhydrolyzed cellulose, which heat treatment is conducted at temperatures between 70 and 200°
C. so as to denature the cellulase enzymes;(v) further hydrolyzing at least a portion of the still bottoms stream with cellulase enzymes to convert the unhydrolyzed cellulose to glucose by recycling at least a portion of the still bottoms stream back to step (ii), thereby increasing cellulose hydrolysis; and (vi) subsequent to the distillation, obtaining a concentrated ethanol product. - View Dependent Claims (15)
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16. A process for producing glucose from a lignocellulosic feedstock, comprising the steps of:
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(i) pretreating the lignocellulosic feedstock under conditions to produce a pretreated lignocellulosic feedstock having disrupted fiber structure and increased accessibility of the lignocellulosic feedstock to being hydrolyzed; (ii) enzymatically hydrolyzing the pretreated lignocellulosic feedstock with cellulase enzymes to produce a hydrolyzate slurry comprising glucose and unhydrolyzed cellulose and fermenting the glucose to produce a fermentation broth comprising alcohol; (iii) obtaining at least a portion of the hydrolyzate slurry comprising the unhydrolyzed cellulose; (iv) subjecting at least a portion of said hydrolyzate slurry to a processing step comprising exposing the unhydrolyzed cellulose to a temperature of between about 70°
C. and about 250°
C., thereby producing a hydrolyzate slurry comprising heat-treated unhydrolyzed cellulose; and(v) further hydrolyzing the heat-treated unhydrolyzed cellulose in said hydrolyzate slurry with cellulase enzymes to convert at least a portion of the unhydrolyzed cellulose to glucose. - View Dependent Claims (17, 18)
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Specification