Ethanol production with two stage continuous steam pre-treatment of lignocellulosic biomass

• US 9,255,189 B2
• Filed: 07/20/2012
• Issued: 02/09/2016
• Est. Priority Date: 07/28/2011
• Status: Expired due to Fees

• Current Assignee: GreenField Specialty Alcohols Inc.
• Original Assignee: GreenField Specialty Alcohols Inc.
• Inventors: Dottori, Frank A., Benson, Robert Ashley Cooper, Benech, Regis-Olivier
• Primary Examiner(s): Humphrey, Louise W
• Assistant Examiner(s): KELLER, CHRISTOPHER A
• Application Number:
  US13/554,601
• Publication Number:
  US 20130029406A1
• Time in Patent Office: 1,299 Days
• Field of Search: None
• US Class Current: 1/1
• 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 producing ethanol from lignocellulosic biomass, including a two stage steam pretreatment process. The first stage of the steam pretreatment is carried out by heating the biomass with high pressure steam 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 steam pretreatment stage is carried out by heating the biomass with high pressure steam to raise the biomass temperature 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. 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 process for the production of ethanol from lignocellulosic biomass, comprising:

a) conditioning the lignocellulosic biomass by pre-steaming the lignocellulosic biomass, compressing the pre-steamed lignocellulosic biomass for removing aqueous extractives and adjusting a water content of the lignocellulosic biomass after the removing step to 65% to 80% for generating a conditioned biomass;

b) subjecting the conditioned biomass to high pressure steam pretreatment to obtain pretreated biomass;

c) rapidly depressurizing the pretreated biomass;

d) separating purified cellulose from the depressurized pretreated biomass; and

e) producing ethanol from said cellulose;

the high pressure steam pretreatment being a two stage steam pretreatment comprising of the steps of

i) in a first stage of the steam pretreatment, heating the conditioned biomass with high pressure steam at a first stage pressure of 105 to 150 psig to a first stage temperature of 140°

C. to 180°

C. for a first stage time of 30 minutes to 2 hours to generate a partially pretreated biomass;

ii) after the first stage and while the partially pretreated biomass is still under pressure, removing hemicellulose and inhibitors to downstream hydrolysis and fermentation by squeezing the partially pretreated biomass in a modular screw device, a screw press or equivalent device for removing solubilized hemicellulose and inhibitors to downstream hydrolysis and fermentation, and feeding the squeezed biomass to a second stage;

iii) in the second stage of the steam pretreatment, heating the squeezed biomass with high pressure steam at a second stage pressure higher than the first stage pressure and at 167 to 262 psig for raising the temperature to a second stage temperature higher than the first stage temperature and at 190°

C. to 210°

C., for a second stage time of 2 to 10 minutes.

2. The process of claim 1, wherein the conditioning is carried out by atmospheric steam heating.

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

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

C. to 170°

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

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

C. to 210°

C. for 3 to 8 minutes.

6. 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 minutes.

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

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

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

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

squeezing and draining the steamed biomass to remove the aqueous extractives; and

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

9. The process of claim 8, wherein the aqueous extractives comprise fatty acids, and/or resins.

10. The process of claim 8, wherein the catalyst is sulfuric acid which is added at a concentration of from 0.15% to 2% of the weight of the biomass.

11. The process of claim 8, wherein the water content is 70% to 75% by weight of the biomass.

12. The process of claim 8, wherein in the conditioning step the lignocellulosic biomass is heated to 90°

C. to 100°

C. for 15 to 30 minutes.

13. The process of claim 8, wherein during the conditioning step, volatile gasses are released during the step of heating the biomass with steam.

14. A process for the production of ethanol from a lignocellulosic biomass, comprising:

a) conditioning the lignocellulosic biomass by

i) pre-steaming the lignocellulosic biomass,

ii) compressing the pre-steamed lignocellulosic biomass for removing aqueous extractives, and

iii) adjusting a water content of the lignocellulosic biomass after the removing step for generating a conditioned biomass;

b) subjecting the conditioned biomass to a first stage steam pretreatment by

i) heating the conditioned biomass with high pressure steam at a first stage pressure of 105 to 150 psig to a first stage temperature of 140°

C. to 180°

C. for a first stage time of 30 minutes to 2 hours, and

ii) after step i) and while maintaining the first stage pressure, removing hemicellulose and inhibitors to downstream hydrolysis and fermentation by squeezing, to generate a partially pretreated biomass;

c) subjecting the partially pretreated biomass to a second stage pretreatment by

i) increasing the temperature of the partially treated biomass by heating the partially pretreated biomass with high pressure steam to a second stage temperature higher than the first stage temperature and at 190°

C. to 210°

C. for a second stage time of 2 to 10 minutes, and increasing the pressure to a second stage pressure higher than the first stage pressure and at 167 to 262 psig; and

ii) removing hemicellulose and hemicellulose decomposition products by squeezing while maintaining the second stage pressure to generate a fully pretreated biomass;

e) following the second stage pretreatment rapidly decompressing the fully pretreated biomass for obtaining purified cellulose; and

f) producing ethanol from said cellulose.