US4070232A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Prehydrolysis and digestion of plant material
Assignee: Individual
•
Filing: 1975-05-30
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Granted: 1978-01-24
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Expires: 1995-05-30
Abstract
Abstract Plant material containing hemicellulose and lignin is prehydrolyzed in the presence of steam and the vapors of a dilute acid solution having a pH of 1.5-3.5 at a temperature of 105° C to 135° C for 7-20 minutes to hydrolyze the hemicellulose into pentoses and hexoses and to leave a fibrous material and a liquid, said liquid containing said pentoses and hexoses. The liquid is separated from the fibrous material, and the pentoses and hexoses are recovered from the liquid. The fibrous material is digested with white liquor at a temperature of 105° C to 135° C.
Inventors
- 👤 Harald F. Funk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:05
CPC Classifications
C; C13; C13K; C13K13/00; C13K13/002; D; D21; D21C; D21C1/00; D21C1/04
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
171 words
A method for treating annual, vascular plant material containing hemicellulose and lignin which comprises the steps of: a. prehydrolyzing said plant material by heating said plant material under pressure in the presence of steam and the vapors of a dilute acid solution having a pH in the range from 1.5 to about 3.5 at a temperature ranging between about 105° C. and about 135° C. for between 7 minutes and about 20 minutes to hydrolyze at least a portion of said hemicellulose into pentoses and hexoses and to leave a fibrous material and a liquid, said liquid containing said pentoses and hexoses; b. separating said liquid from said fibrous material, and recovering the pentoses and hexoses from said liquid; c. heating said fibrous material under pressure in the presence of white liquor at a temperature ranging between about 105° C. and about 135° C. for a time sufficient to digest said fibrous material; d. separating the digested fibrous material from spent digestion liquor; and then e. washing the digested fibrous material.
Claim 2
Independent Claim
171 words
A method for treating annual, vascular plant material containing hemicellulose and lignin which comprises the steps of: a. prehydrolyzing said plant material by heating said plant material under pressure in the presence of steam and the vapors of a dilute acid solution having a pH in the range from 1.5 to about 3.5 at a temperature ranging between about 105° C. and about 135° C. for between 7 minutes and about 20 minutes to hydrolyze at least a portion of said hemicellulose into pentoses and hexoses and to leave a fibrous material and a liquid, said liquid containing said pentoses and hexoses; b. separating said liquid from said fibrous material, and recovering the pentoses and hexoses from said liquid; c. heating said fibrous material under pressure in the presence of white liquor at a temperature ranging between about 105° C. and about 135° C. for a time sufficient to digest said fibrous material; d. separating the digested fibrous material from spent digestion liquor; and then e. washing the digested fibrous material.
Claim 3
Dependent Claim
26 words
The method set forth in claim 1 in which the prehydrolysis is performed at a weight ratio of acid solution to plant material of about 3:1.
Claim 4
Dependent Claim
33 words
The method set forth in claim 2 in which the weight ratio of white liquor to fibrous material is about 6:1 and said digestion is completed in from 15 to about 55 minutes.
Claim 5
Dependent Claim
39 words
The method set forth in claim 1 in which the acid solution of the prehydrolyzing step contains about 0.2% by weight of hydrochloric acid, about 1.3% by weight of formic acid and about 2.7% by weight of acetic acid.
Claim 6
Dependent Claim
20 words
The method set forth in claim 1 in which said white liquor to fibrous material weight ratio is about 6:1.
Claim 7
Dependent Claim
25 words
The method set forth in claim 1 in which the heating time of the digestion step is between about 15 minutes and about 55 minutes.
Claim 8
Dependent Claim
31 words
The method set forth in claim 1 in which the digestion step is carried out in an aqueous solution containing between about 12% and about 15% by weight of active alkali.
Claim 9
Dependent Claim
38 words
The method set forth in claim 1 in which the digestion step is carried out in an aqueous solution containing between about 12% and about 15% by weight of active alkali and having a sulfidity of about 25%.
Claim 10
Dependent Claim
16 words
The method set forth in claim 1 in which said annual, vascular plant material is bagasse.
Claim 11
Dependent Claim
34 words
The method set forth in claim 1 wherein said plant material is prehydrolyzed at 125° C. for about 15 minutes and said fibrous material is digested at about 120° C. for about 20 minutes.
Claim 12
Dependent Claim
28 words
The method set forth in claim 1 wherein said dilute acid solution contains an acid selected from the group consisting of organic acids, mineral acids, and mixtures thereof.
Claim 13
Dependent Claim
27 words
The method set forth in claim 1 wherein the active alkali in said white liquor is selected from the group consisting of sodium oxide and sodium carbonate.
Claim 14
Dependent Claim
144 words
In a method for prehydrolyzing and digesting annual, vascular plants containing hemicellulose and lignin including the steps of prehydrolyzing said plants in an acidic aqueous medium under pressure in the presence of steam resulting in a fibrous material and a liquid, said liquid containing pentoses and hexoses, and digesting the resulting fibrous material in an aqueous alkaline medium containing sulfide values therein, the improvement comprising: prehydrolyzing said plants in contact with the vapors of a dilute acid solution having a pH in the range from 1.5 to about 3.5 at a temperature in the range from 105° C. to about 135° C. for from about 7 to 20 minutes to convert at least a portion of said hemicellulose to pentoses and hexoses, separating said liquid from said fibrous material prior to digesting said fibrous material and recovering said pentoses and hexoses from said liquid.
Claim 15
Dependent Claim
144 words
In a method for prehydrolyzing and digesting annual, vascular plants containing hemicellulose and lignin including the steps of prehydrolyzing said plants in an acidic aqueous medium under pressure in the presence of steam resulting in a fibrous material and a liquid, said liquid containing pentoses and hexoses, and digesting the resulting fibrous material in an aqueous alkaline medium containing sulfide values therein, the improvement comprising: prehydrolyzing said plants in contact with the vapors of a dilute acid solution having a pH in the range from 1.5 to about 3.5 at a temperature in the range from 105° C. to about 135° C. for from about 7 to 20 minutes to convert at least a portion of said hemicellulose to pentoses and hexoses, separating said liquid from said fibrous material prior to digesting said fibrous material and recovering said pentoses and hexoses from said liquid.
References Cited (Backward Citations)
US2898994A
Cited
US2992155A
Cited
US2944929A
Cited
US3051611A
Cited
US3081218A
Cited
US3212933A
Cited
US3251716A
Cited
US3479248A
Cited
US3523911A
Cited
US3738908A
Cited
US3923591A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-01-23 | 1981-07-25 | 1982-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-23 | 1985-07-25 | 1986-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-23 | 1989-07-25 | 1990-01-24 | $7700.00 | Window Closed / Lapsed |