METHOD FOR THE PRODUCTION OF ALCOHOL FROM A PRETREATED LIGNOCELLULOSIC FEEDSTOCK
First Claim
1. A process for the production of alcohol from a lignocellulosic feedstock which comprises the steps of:
- (i) pretreating a lignocellulosic feedstock under conditions to disrupt fiber structure and increase accessibility of the feedstock to being hydrolyzed in order to produce a composition comprising a pretreated lignocellulosic feedstock;
(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, said distillation resulting in heat treatment of the unhydrolyzed cellulose; 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.
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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
37 Claims
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1. A process for the production of alcohol from a lignocellulosic feedstock which comprises the steps of:
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(i) pretreating a lignocellulosic feedstock under conditions to disrupt fiber structure and increase accessibility of the feedstock to being hydrolyzed in order to produce a composition comprising a pretreated lignocellulosic feedstock; (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, said distillation resulting in heat treatment of the unhydrolyzed cellulose; 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A process for the production of ethanol from a lignocellulosic feedstock which comprises the steps of:
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(i) pretreating a lignocellulosic feedstock under conditions to disrupt fiber structure and increase accessibility of the feedstock to being hydrolyzed in order to produce a composition comprising a pretreated lignocellulosic feedstock; (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, said distillation resulting in heat treatment of the unhydrolyzed cellulose; and (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).
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18. 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 disrupt fiber structure and increase accessibility of the lignocellulosic feedstock to being hydrolyzed in order to produce a pretreated lignocellulosic feedstock; (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 a process stream comprising the unhydrolyzed cellulose; (iv) subjecting at least a portion of said process stream to a processing step comprising exposing the unhydrolyzed cellulose to a temperature of between about 70°
C. and about 250°
C., thereby producing a stream comprising heat-treated unhydrolyzed cellulose; and(v) further hydrolyzing the heat-treated unhydrolyzed cellulose with cellulase enzymes to convert at least a portion of the unhydrolyzed cellulose to glucose. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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26. In a process for the production of alcohol from a lignocellulosic feedstock which comprises the steps of a process stream, the improvement which comprises:
- subjecting unhydrolyzed cellulose resulting from a previous pretreatment and cellulase hydrolysis of a lignocellulosic feedstock to exposing said unhydrolyzed cellulose in said process stream to conditions which denature bound cellulase enzyme; and
then hydrolyzing said unhydrolyzed cellulose which has been so exposed to said denaturing conditions to glucose by further hydrolysis with cellulase enzymes. - View Dependent Claims (27, 28)
- subjecting unhydrolyzed cellulose resulting from a previous pretreatment and cellulase hydrolysis of a lignocellulosic feedstock to exposing said unhydrolyzed cellulose in said process stream to conditions which denature bound cellulase enzyme; and
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29. 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 disrupt fiber structure and increase accessibility of the lignocellulosic feedstock to being hydrolyzed in order to produce a pretreated lignocellulosic feedstock; (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 a process stream comprising the unhydrolyzed cellulose; (iv) subjecting at least a portion of said process stream to a processing step comprising exposing the unhydrolyzed cellulose to an enzyme denaturing step to denature cellulase enzymes bound to the unhydrolyzed cellulose; and (v) further hydrolyzing the process stream comprising the unhydrolyzed cellulose subjected to said denaturing step with cellulase enzymes to convert at least a portion of the unhydrolyzed cellulose to glucose. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. A process which comprises exposing unhydrolyzed cellulose in a process stream comprising unhydrolyzed cellulose resulting from a previous pretreatment and cellulase hydrolysis of a lignocellulosic feedstock to conditions which denature bound cellulase enzyme and subsequently hydrolyzing said unhydrolyzed cellulose, which has been exposed to such denaturing conditions, to glucose by further hydrolysis with cellulase enzymes.
Specification