Methods and systems for producing fermentation products from carbohydrate-rich substrates

• US 9,428,772 B2
• Filed: 10/27/2015
• Issued: 08/30/2016
• Est. Priority Date: 02/02/2014
• Status: Active Grant

• Current Assignee: Edward Brian Hamrick
• Original Assignee: Edward Brian Hamrick
• Inventors: Hamrick, Edward Brian
• Primary Examiner(s): Mayes, Melvin C
• Assistant Examiner(s): CALL, DOUGLAS BRYANT
• Application Number:
  US14/924,462
• Publication Number:
  US 20160046966A1
• Time in Patent Office: 308 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: C08B 37/0003 General processes for their isolation or fractionation, e.g. purification or extraction from biomass
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: C12P 19/00 Preparation of compounds containing saccharide radicals ketoaldonic acids C12P7/58
• CPC Class Codes: C12P 19/02 Monosaccharides 2-ketogulonic acid C12P7/60
• CPC Class Codes: C12P 19/14 produced by the action of a carbohydrase (EC 3.2.x), e.g. by alpha-amylase , e.g. by cellulase, hemicellulase
• CPC Class Codes: C12P 2201/00 Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
• CPC Class Codes: C12P 2203/00 Fermentation products obtained from optionally pretreated or hydrolyzed cellulosic or lignocellulosic material as the carbon source
• CPC Class Codes: C12P 7/14 Multiple stages of fermentation; Multiple types of microorganisms or re-use of microorganisms
• CPC Class Codes: C12P 7/16 Butanols
• CPC Class Codes: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: C13K 1/06 obtained by saccharification of starch or raw materials containing starch
• CPC Class Codes: C13K 13/00 Sugars not otherwise provided for in this class
• CPC Class Codes: C13K 13/002 Xylose
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02P 20/582 Recycling of unreacted starting or intermediate materials

Abstract

A method for producing fermentation products from lignocellulosic biomass is provided. Lignocellulosic biomass is composed of lignocellulosic fibers which are hollow and primarily contain cellulose, hemicellulose and lignin. Lignin is concentrated in the outer fiber wall and glues the fibers into bundles, but the inner fiber wall has a much lower concentration of lignin and has more easily accessible cellulose and hemicellulose. This method uses vacuum infusion to infuse enzymes into the lumen (hollow center) of lignocellulosic fibers to hydrolyze the hemicellulose and cellulose to produce sugars and oligomers, and then uses cycles of vacuum pressure to pump these homogeneous reagents and sugars and oligomers into and out of the lumen. These reagents are homogenized by mixing the reagents with process water using turbulent mixing to produce a homogeneous reagent. The sugars may be fermented, such as with yeast, to a fermentation product, such as ethanol or butanol.

Claims

1. A process for producing a fermentation product from a carbohydrate-rich substrate, said process comprising the steps of:

(a) providing a carbohydrate-rich substrate and an aqueous solution containing a hydrolysis catalyst and a fermentation organism, and maintaining a gas pressure above said carbohydrate-rich substrate at an evacuation pressure and for an evacuation time to infuse said aqueous solution into said carbohydrate-rich substrate at an infusion temperature, thereby generating a reaction mixture;

(b) exposing said reaction mixture to a gas-phase reaction pressure that is higher than said evacuation pressure;

(c) maintaining said reaction mixture at a reaction temperature for a reaction time to generate sugar monomers within lumen space of said carbohydrate-rich substrate;

(d) exposing said reaction mixture to a gas-phase expulsion pressure that is lower than said reaction pressure, to pump said sugar monomers out of said lumen space and into said aqueous solution;

(e) maintaining said reaction mixture at an expulsion temperature for an expulsion time;

(f) repeating steps (b) to (e) for at least two pressure cycles to remove, by a pumping mechanism, said sugar monomers from said lumen space;

(g) fermenting at least a portion of said sugar monomers with said fermentation organism to generate a fermentation product in said aqueous solution; and

(h) recovering said fermentation product from said aqueous solution,

wherein said process does not include steam explosion or ammonia fiber expansion of said carbohydrate-rich substrate.

2. The process of claim 1, wherein said carbohydrate-rich substrate is selected from the group consisting of naturally occurring lignocellulosic biomass, processed lignocellulosic biomass, pulp, paper, paper-based products, carbohydrate-rich industrial waste, and combinations thereof.

3. The process of claim 2, wherein said carbohydrate-rich substrate includes (i) said naturally occurring lignocellulosic biomass selected from the group consisting of size-reduced softwood, sugarcane bagasse, wheat straw, corn stover, switchgrass, miscanthus, and combinations thereof and/or (ii) said carbohydrate-rich industrial waste selected from the group consisting of food waste, components of municipal solid waste, and combinations thereof.

4. The process of claim 1, wherein said sugar monomers comprise one or more of xylose, arabinose, glucose, mannose, or galactose.

5. The process of claim 1, wherein said hydrolysis catalyst comprises one or more enzymes each with cellulolytic activity and/or hemicellulolytic activity.

6. The process of claim 1, wherein said aqueous solution in step (a) is a homogeneous mixture, said process further comprising mixing said hydrolysis catalyst and said fermentation organism with process water using turbulent energy in the range of about 0.5 W/kg to about 5 W/kg to produce said homogeneous mixture.

7. The process of claim 1, wherein said reaction temperature is about 25°

C. to about 40°

C.

8. The process of claim 1, wherein said reaction time is about 15 minutes to about 8 hours.

9. The process of claim 1, wherein said expulsion time is about 1 second to about 60 minutes.

10. The process of claim 1, wherein said expulsion pressure is from about 100% to about 200% of the water equilibrium pressure at said reaction temperature.

11. The process of claim 1, wherein said number of pressure cycles is from 3 to about 200.

12. The process of claim 1, wherein said infusion temperature is less than or equal to the boiling point of water at said evacuation pressure.

13. The process of claim 1, wherein said infusion temperature is from about 25°

C. to about 40°

C.

14. The process of claim 1, wherein said evacuation pressure is from about 105% to about 200% of the water equilibrium pressure at said infusion temperature.

15. The process of claim 1, wherein said evacuation time is about 1 minute to about 2 hours.

16. The process of claim 1, said process further comprising controlling pH of said reaction mixture from about 4 to about 7 by adjusting gas-phase composition above, or in equilibrium with, said aqueous solution.

17. The process of claim 1, wherein said fermentation organism is a yeast.

18. The process of claim 1, wherein step (h) includes vacuum stripping to recover said fermentation product from said aqueous solution.

19. The process of claim 1, wherein said fermentation product is ethanol.

20. The process of claim 1, wherein said fermentation product is butanol.