US4395543A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective solvent extraction of cellulosic material
Assignee: Massachusetts Institute of Technology
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Filing: 1981-08-12
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Granted: 1983-07-26
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Expires: 2001-08-12
Abstract
Abstract Cellulosic products having a high hemicellulose to lignin weight ratio are obtained by extracting a cellulosic composition with basic ethanol-water solution having a pH between about 12 and about 14 at a temperature between about 15 DEG and about 70 DEG C. and for a time period between about 2 and about 80 hours.
Inventors
- 👤 Daniel I. C. Wang
- 👤 George C. Avgerinos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:28
CPC Classifications
C; C08; C08H; C08H6/00; C08H8/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
125 words
The process for selectively extracting lignin from a cellulosic material containing cellulose, hemicellulose and lignin in order to obtain a cellulose composition wherein the weight ratio of pentosan to lignin is at least about 5:1 and the weight ratio of cellulose and hemicellulose to lignin is at least about 10:1 and greater than 90% of the initial cellulose and pentosan is retained, which comprises contacting said material with a solvent composition comprising water, between about 40 and about 75 volume % ethanol and a base, said solvent composition having a pH between about 11 and about 14, said extraction being conducted at a temperature between about 15° C. and about 70° C. for a period of time of between about 2 and about 80 hours.
Claim 2
Dependent Claim
125 words
The process for selectively extracting lignin from a cellulosic material containing cellulose, hemicellulose and lignin in order to obtain a cellulose composition wherein the weight ratio of pentosan to lignin is at least about 5:1 and the weight ratio of cellulose and hemicellulose to lignin is at least about 10:1 and greater than 90% of the initial cellulose and pentosan is retained, which comprises contacting said material with a solvent composition comprising water, between about 40 and about 75 volume % ethanol and a base, said solvent composition having a pH between about 11 and about 14, said extraction being conducted at a temperature between about 15° C. and about 70° C. for a period of time of between about 2 and about 80 hours.
Claim 3
Dependent Claim
40 words
A cellulose composition wherein the weight ratio of pentosan to lignin is at least 5:1 and the weight ratio of cellulose and pentosan to lignin is at least about 10:1, said composition being prepared by the process of claim 1.
Claim 4
Dependent Claim
33 words
The composition of claim 2 wherein the weight ratio of pentosan to lignin is at least about 6:1 and the weight ratio of cellulose and pentosan to lignin is at least about 13:1.
Claim 5
Dependent Claim
11 words
The process of claim 1 wherein the base is sodium hydroxide.
Claim 6
Dependent Claim
14 words
The process of claim 1 wherein the pH is between about 12 and 14.
Claim 7
Dependent Claim
16 words
The process of claim 1 wherein the temperature is between about 15° C. and 30° C.
Claim 8
Dependent Claim
17 words
The process of claim 1 wherein the extraction time is between about 2 and about 80 hours.
Claim 9
Dependent Claim
23 words
The process of claim 1 wherein the extracting solvent comprising water and ethanol is recovered by addition of calcium to remove lignin therefrom.
Claim 10
Dependent Claim
31 words
The process of claim 1 wherein the extracting solvent comprising water and ethanol is recovered by reducing the pH of the solvent to below about 10 thereby to remove lignin therefrom.
Claim 11
Dependent Claim
21 words
The process of claim 1 wherein the extracting solvent comprising water and ethanol is recovered by adsorption to remove lignin therefrom.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-25 | 1987-01-24 | 1987-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-25 | 1991-01-24 | 1991-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-25 | 1995-01-24 | 1995-07-26 | $7700.00 | Window Closed / Lapsed |