Two-stage dilute acid prehydrolysis of biomass

• US 5,125,977 A
• Filed: 04/08/1991
• Issued: 06/30/1992
• Est. Priority Date: 04/08/1991
• Status: Expired due to Fees

• Current Assignee: United States Department of Energy
• Original Assignee: United States Department of Energy
• Inventors: Grohmann, Karel, Torget, Robert W.
• Primary Examiner(s): Morris, Theodore
• Assistant Examiner(s): HAILEY, PATRICIA L
• Application Number:
  US07/681,299
• Time in Patent Office: 449 Days
• Field of Search: 127/36, 127/37, 127/38, 127/44
• US Class Current: 127/36
• CPC Class Codes: C13K 13/002 Xylose

Abstract

A two-stage dilute acid prehydrolysis process on xylan containing hemicellulose in biomass is effected by: treating feedstock of hemicellulosic material comprising xylan that is slow hydrolyzable and xylan that is fast hydrolyzable under predetermined low temperature conditions with a dilute acid for a residence time sufficient to hydrolyze the fast hydrolyzable xylan to xylose; removing said xylose from said fast hydrolyzable xylan and leaving a residue; and treating said residue having a slow hydrolyzable xylan with a dilute acid under predetermined high temperature conditions for a residence time required to hydrolyze said slow hydrolyzable xylan to xylose.

Claims

1. A two-stage dilute acid prehydrolysis process on xylan containing hemicellulose in biomass, comprising:

treating a feedstock of hemicellulosic material comprising xylan that is slow hydrolyzable and xylan that is fast hydrolyzable under predetermined low temperature conditions with a dilute acid for a residence time sufficient to hydrolyze said fast hydrolyzable xylan at temperatures between about 90 to about 180°

C. to xylose;

removing said xylose from said fast hydrolzable xylan and leaving a residue having slow hydrolyzable xylan;

treating said residue having slow hydrolyzable xylan with a dilute acid under predetermined higher temperature conditions for a residence time sufficient to hydrolyze said slow hydrolyzable xylan at temperatures between about 160°

to 220°

C. to xylose; and

removing said xylose from said slow hydrolyzable xylan to obtain over 90% hydrolysis of xylan.

2. The process of claim 1, wherein the feedstock of hemicellulosic material is aspen wood meal, wheat straw, corn stover, corn cobs, corn fiber and waste paper.

3. The process of claim 1, wherein said dilute acid is selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, sulfurous acid, carbonic acid, formic acid, acetic acid, tartaric acid, citric acid, glucuronic acid, 4-0-methylglucuronic acid, galacturonic acid and oligosaccharides containing these acids.

4. The process of claim 3, wherein the dilute acid is sulfuric acid.

5. The process of claim 4, wherein said sulfuric acid is about 0.1 to about 2.0 wt %.

6. The process of claim 5, wherein the predetermined low temperature is about 145°

C. and the predetermined higher temperature is about 180°

C.

7. The process of claim 6, wherein the residence time under the predetermined low temperature is about 8 minutes and the residence time under the predetermined higher temperature is about 4 minutes.

8. The process of claim 7, wherein the xylose yield is about 90.75% or greater.