Selective solvent extraction of cellulosic material

• US 4,395,543 A
• Filed: 08/12/1981
• Issued: 07/26/1983
• Est. Priority Date: 08/12/1981
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Wang, Daniel I. C., Avgerinos, George C.
• Primary Examiner(s): Griffin, Ronald W.
• Application Number:
  US06/292,314
• Time in Patent Office: 713 Days
• Field of Search: 536/56, 162/77, 162/90, 162/97, 127/37
• US Class Current: 536/56
• CPC Class Codes: C08H 6/00 Macromolecular compounds derived from lignin, e.g. tannins, humic acids
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N

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

Claims

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°

C. and about 70°

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

2. 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.

3. 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.

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

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

6. The process of claim 1 wherein the temperature is between about 15°

C. and 30°

C.

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

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

9. 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.

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