Process for producing a concentrated sugar solution by enzymatic saccharification of polysaccharide enriched biomass

• US 8,524,474 B2
• Filed: 11/19/2009
• Issued: 09/03/2013
• Est. Priority Date: 11/20/2008
• Status: Active Grant

• Current Assignee: Sustainable Technology Corporation
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Sabesan, Subramaniam, Spado, Christina Jacy
• Primary Examiner(s): Rao, Manjunath
• Assistant Examiner(s): Moore, William W
• Application Number:
  US12/621,579
• Publication Number:
  US 20100124770A1
• Time in Patent Office: 1,384 Days
• Field of Search: None
• US Class Current: 435/165
• 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: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

Methods for obtaining concentrated sugar solution from polysaccharide enriched biomass by contacting biomass with water and at least one nucleophilic base to produce a polysaccharide enriched biomass comprising a solid fraction and a liquid fraction and then contacting the solid fraction with saccharification enzyme consortium to produce a saccharification product comprising at least about 7 percent by weight sugars in 24 hours. The methods include optionally adding at least one additive selected from the group consisting of polyethylene glycols, fatty acid esters, fatty acid ethoxylates, nonionic surfactants derived from polyethoxylated sorbitan and a fatty acid, sodium lauriminodipropionate, sodium cocoamphoacetate, sodium tridecyl ether sulfate and a combination of these, such that enzyme loading of the saccharification enzyme consortium can be reduced.

Claims

1. A method of producing a concentrated sugar solution from biomass, the method comprising:

a) delignifying biomass comprising the substeps of

i) contacting with water and at least one nucleophilic base, a biomass comprising lignin and having a glucan/xylan weight ratio G₁/X₁ to form a biomass slurry having a pH of about 12.5 to about 13.0; and

ii) maintaining the biomass slurry under reaction conditions such that the slurry attains a pH of about 9.5 to about 10.0 and has a glucan/xylan weight ratio G₂/X₂ within 10% of the value of G₁/X₁, and wherein the slurry comprises a lignin-containing liquid fraction and a solid fraction comprising a polysaccharide enriched biomass;

wherein G₁ and G₂ are grams of glucan per 100 grams of biomass and biomass slurry respectively, and X₁ and X₂ are grams of xylan per 100 grams of biomass and biomass slurry respectively; and

wherein the water soluble metal hydroxide is selected from the group consisting of sodium hydroxide, and the metal carbonate or the organic hydroxide is selected from the group consisting of sodium carbonate, potassium carbonate, ammonium hydroxide; and

wherein the reaction conditions include a temperature from about 20°

C. to about 110°

C. and a reaction time of about 4 hours to about 30 days; and

b) adding an additive selected from the group consisting of polyethylene glycols, fatty acid esters, fatty acid ethoxylates, nonionic surfactants derived from polyethoxylated sorbitan and a fatty acid, sodium lauriminodipropionate, sodium cocoamphoacetate, sodium tridecyl ether sulfate, and a combination of these, such that the enzyme loading of the saccharification enzyme consortium is reduced relative to the loading of the saccharification enzyme consortium when none of the additives is added; and

c) contacting with a saccharification enzyme consortium an aqueous suspension of at least a portion of the solid fraction of the polysaccharide enriched biomass,

the solid fraction of the polysaccharide enriched biomass being 13 weight percent to about 30 weight percent of the aqueous suspension,

at reaction conditions sufficient to produce a saccharification product comprising at least about 7 percent by weight sugars, based on the total weight of the saccharification product, in 24 hours of contact with the saccharification enzyme consortium.

2. The method of claim 1 wherein the saccharification product comprises at least about 18 percent by weight sugars in 168 hours.

3. The method of claim 1 wherein the additive is from about 0.1 weight percent to about 5 weight percent, based on the weight of the solid fraction of the polysaccharide enriched biomass solid fraction in the aqueous suspension.

4. The method of claim 3, wherein the additive is a polyethylene glycol of molecular weight 500 to 50,000 Daltons, a fatty acid ester selected from the group consisting of methyl esters of C₁₂ to C₃₀ fatty acid esters, fatty acid ethoxylates of C₁₂ to C₃₀ fatty acids, nonionic surfactants derived from polyethoxylated sorbitan and a C₁₂ to C₃₀ fatty acid, and a combination of these.

5. The method of claim 1 wherein at least about 70 percent of the lignin in the biomass is delignified in the solid fraction of the polysaccharide enriched biomass.

6. The method of claim 1 wherein the concentration of the solid fraction in the aqueous suspension is from about 21 weight percent to about 30 weight percent, and the saccharification product comprises sugars corresponding to at least a 65% saccharification yield based on the sum of glucan and xylan in the polysaccharide enriched biomass.

7. The method of claim 1 wherein the sugars comprise at least one sugar monomer selected from the group consisting of glucose, arabinose, xylose, mannose, and galactose, and a combination of these.