# US 4,395,543 A · Selective solvent extraction of cellulosic material

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- Number: US 4,395,543 A
- Document ID: US4395543A
- Status: Granted
- Kind: A
- Application number: 06/292,314
- Filed: 1981-08-12
- Granted: 1983-07-26
- Earliest claimed: 1981-08-12
- Assignees: Massachusetts Institute of Technology
- Inventors: Daniel I. C. Wang; George C. Avgerinos
- Web page: https://patentgrep.com/patent/US4395543A

## CPC

- C08H 6/00: {Macromolecular compounds derived from lignin, e.g. tannins, humic acids}
- C08H 8/00: Macromolecular compounds derived from lignocellulosic materials {(pretreatment thereof B27N)}
- C08H: DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS (polysaccharides C08B; natural rubber C08C; natural resins or their derivatives C09F; bituminous materials C10)

## 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.degree. and about 70.degree. C. and for a time period between about 2 and about 80 hours.

## Claims

### Claim 1

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.degree. C. and about 70.degree. C. for a period of time of between about 2 and about 80 hours.

### Claim 2 (depends on 1)

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 3 (depends on 2)

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 4 (depends on 1)

The process of claim 1 wherein the base is sodium hydroxide.

### Claim 5 (depends on 1)

The process of claim 1 wherein the pH is between about 12 and 14.

### Claim 6 (depends on 1)

The process of claim 1 wherein the temperature is between about 15.degree. C. and 30.degree. C.

### Claim 7 (depends on 1)

The process of claim 1 wherein the extraction time is between about 2 and about 80 hours.

### Claim 8 (depends on 1)

The process of claim 1 wherein the extracting solvent comprising water and ethanol is recovered by addition of calcium to remove lignin therefrom.

### Claim 9 (depends on 1)

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 10 (depends on 1)

The process of claim 1 wherein the extracting solvent comprising water and ethanol is recovered by adsorption to remove lignin therefrom.