TWO STAGE CONTINUOUS PRE-TREATMENT OF LIGNOCELLULOSIC BIOMASS

• US 20130029406A1
• Filed: 07/20/2012
• Published: 01/31/2013
• Est. Priority Date: 07/28/2011
• Status: Active Grant

• Current Assignee: GreenField Specialty Alcohols Inc.
• Original Assignee: GreenField Ethanol Inc.
• Inventors: DOTTORI, Frank A., BENSON, Robert Ashley Cooper, BENECH, Regis-Olivier
• Granted Patent: US 9,255,189 B2
• Time in Patent Office: Days
• US Class Current: 435/274
• CPC Class Codes: C08B 37/0057 beta-D-Xylans, i.e. xylosaccharide, e.g. arabinoxylan, arabinofuronan, pentosans; (beta-1,3)(beta-1,4)-D-Xylans, e.g. rhodymenans; Hemicellulose; Derivatives thereof
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

Disclosed is a method of pretreating biomass in two pretreatment stages as part of a biofuel production process. The first stage pretreatment is carried out by heating the biomass to a first stage temperature of 140° C. to 180° C. for a first stage time of 30 minutes to 2 hours at a first stage pressure of 105 to 150 psig; and the second stage is carried out by heating the biomass to a second stage temperature of 190° C. to 210° C. for a second stage time of 2 to 10 minutes at a second stage pressure of 167 to 262 psig. The biomass may be initially conditioned prior to the first pretreatment stage by atmospheric steam heating and adjusting the moisture content of the biomass. Hemicellulose and inhibitors (inhibitory compounds) to downstream hydrolysis and fermentation are preferably removed between the first and second pretreating stages, more preferably after each pretreatment stage.

Claims

1. A two stage pretreatment process for the recovery of carbohydrates from lignocellulosic biomass, comprising:

a) pretreating the biomass in a first stage by heating the biomass to a first stage temperature of 140°

C. to 180°

C. for a first stage time of 30 minutes to 2 hours at a first stage pressure of 105 to 150 psig; and

b) pretreating the biomass in a second stage by heating the biomass to a second stage temperature of 190°

C. to 210°

C. for a second stage time of 2 to 10 minutes at a second stage pressure of 167 to 262 psig.

2. The process of claim 1, further comprising a step of conditioning by atmospheric steam heating and adjusting a moisture content of the biomass prior to the first stage pretreating.

3. The process of claim 1, wherein the first stage pretreating further comprises the addition of water and at least one o f an acid promoting hemicellulose hydrolysis, sulfuric acid, sulfur dioxide, acetic acid and a chemical catalyst promoting hemicellulose hydrolysis.

4. The process of claim 1, wherein hemicellulose and inhibitors to downstream hydrolysis and fermentation are removed between the first stage pretreating and the second stage pretreating.

5. The process of claim 1, wherein the first stage pretreating is carried out at a temperature of 140°

C. to 170°

C. for a time of 50 minutes to 2 hours.

6. The process of claim 1, wherein the second stage pretreating is carried out at a temperature of 200°

C. to 210°

C. for 3 to 8 minutes.

7. The process of claim 4, wherein the removal of hemicellulose and inhibitors to downstream hydrolysis and fermentation is performed by squeezing the biomass in a modular screw device, a screw press or equivalent device.

8. The process of claim 4, further comprising a subsequent step of squeezing the biomass after the second stage pretreatment to further remove hemicellulose and inhibitors to downstream hydrolysis and fermentation.

9. The process of claim 1, wherein the first stage temperature is 150°

C., the first stage pressure is 105 psig, and the first stage time is 55 min.

10. The process of claim 1, wherein the second stage temperature is 205°

C., the second stage pressure is 235 psi, and the second stage time is 6.7 minutes.

11. The process of claim 2, wherein the conditioning step comprises:

heating the biomass with steam at atmospheric pressure for 10 to 60 minutes;

squeezing and draining the biomass to remove liquid containing toxins detrimental to downstream hydrolysis and fermentation; and

evenly adding water and a catalyst promoting hemicellulose hydrolysis to adjust the biomass to a water content of 65% to 80% prior to the first stage.

12. The process of claim 11, wherein the toxins comprise fatty acids, and/or resins.

13. The process of claim 11, wherein the catalyst is sulfuric acid which is added at a concentration of from 0.15% to 2% of the weight of the biomass.

14. The process of claim 11, wherein the water content is 70%-75% by weight of the biomass.

15. The process of claim 11, wherein in the conditioning step the biomass is heated to 90-100°

C. for 15 to 30 minutes.

16. The process of claim 11, wherein during the conditioning step, volatile gasses are released during the step of heating the biomass with steam.