Pretreatment of softwood

Patent metadata

Field	Value
Publication number	US-2022017928-A1
Application number	US-201817309080-A
Country	US
Kind code	A1
Filing date	Nov 9, 2018
Priority date	Nov 9, 2018
Publication date	Jan 20, 2022
Grant date	—

Abstract

A process for producing a fuel from a softwood. A feedstock containing softwood is pretreated, where the pretreating includes heating the feedstock in a pretreatment liquor containing sulfur dioxide and bisulfite salt. The heating is conducted between 110° C. and 160° C. The pretreatment liquor has a sulfur dioxide concentration that is greater than 6.5 wt % on liquor and a pH at 25° C. that is less than 1.3. The cellulose in the pretreated material is hydrolysed to glucose. The glucose may be fermented to a fermentation product such as ethanol.

First claim

1 . A process for producing a fuel from softwood, said process comprising:
(a) obtaining a feedstock comprising softwood; (b) pretreating the feedstock, said pretreating comprising heating the feedstock in a pretreatment liquor comprising sulfur dioxide and bisulfite salt, said heating conducted between 110° C. and 160° C., wherein the pretreatment liquor has a pH at 25° C. that is less than 1.3 and has a sulfur dioxide concentration that is greater than 6.5 wt % on liquor, (c) obtaining a slurry of pretreated material produced in (a), said slurry having a solid fraction comprising cellulose and a liquid fraction comprising solubilized hemicellulose; (d) hydrolyzing the cellulose to glucose, said hydrolyzing comprising adding cellulase to at least the solid fraction; (e) fermenting the glucose to a fermentation product, said fermenting comprising adding a microorganism to at least the glucose; and (f) recovering the fermentation product,
wherein the fuel comprises the fermentation product.

2 . The process according to claim 1 , wherein the softwood comprises resinous softwood.

3 . The process according to claim 1 , wherein the softwood comprises pine, Douglas fir, or a combination thereof.

4 . The process according to claim 1 , wherein the feedstock comprises woodchips.

5 . The process according to claim 1 , wherein the feedstock comprises sawdust.

6 . The process according to claim 1 , wherein said heating is conducted between 120° C. and 150° C.

7 . The process according to claim 1 , wherein said heating is conducted for between 30 minutes and 4 hours.

8 . The process according to claim 1 , wherein the liquid to solid weight ratio in the pretreatment is between 1.5 and 9.

9 . The process according to claim 1 , wherein the concentration of sulfur dioxide in the pretreatment is between 7.8 wt % on liquor and 19.5 wt % on liquor.

10 . The process according to claim 1 , wherein the concentration of sulfur dioxide in the pretreatment is greater than 65 wt % on dry solids.

11 . The process according to claim 1 , wherein a concentration of alkali in the pretreatment is at least 0.05 wt % expressed as weight percent hydroxide on liquor.

12 . The process according to claim 1 , wherein a ratio of concentration of sulfur dioxide on liquor to concentration of alkali, expressed as weight percent hydroxide, on liquor is greater than 30.

13 . The process according to claim 1 , wherein a concentration of sulfur dioxide in the pretreatment is greater than 36 wt % on dry solids, and wherein a concentration of alkali is less than 0.25 wt % expressed as weight percent hydroxide on liquor.

14 . The process according to claim 1 , wherein the pH of the pretreatment liquor at 25° C. is between 0.9 and 1.1.

15 . The process according to claim 1 , wherein the pH of the slurry of pretreated material is less than 1.

16 . The process according to claim 1 , comprising:
subjecting the slurry of pretreated material to a solid-liquid separation to separate the solid fraction and the liquid fraction; and washing the solid fraction produced by the solid-liquid separation with water, wherein adding cellulase to at least the solid fraction comprises adding the cellulase to the washed solid fraction.

17 . The process according to claim 1 , comprising producing one or more products from the liquid fraction, said one or more products comprising at least one of xylose, xylitol, methane, ethanol, or lignosulfonate.

18 . The process according to claim 1 , wherein the fermentation product is ethanol.

19 . A process for producing ethanol comprising:
(a) obtaining a feedstock, said feedstock comprising softwood woodchips; (b) pretreating the feedstock, said pretreating comprising heating the feedstock in a pretreatment liquor comprising sulfur dioxide and bisulfite salt, said heating conducted between 110° C. and 160° C. for at least 30 minutes, wherein the pretreatment liquor has a pH at 25° C. that is less than 1.3 and has a sulfur dioxide concentration that is greater than 6.5 wt % on liquor; (c) obtaining a slurry of pretreated material produced in (a), said slurry having a solid fraction comprising cellulose and a liquid fraction comprising solubilized hemicellulose; (d) hydrolyzing the cellulose to glucose, said hydrolyzing comprising adding cellulase to at least the solid fraction; (e) fermenting the glucose to ethanol, said fermenting comprising adding a microorganism to at least the glucose; (f) recovering the ethanol; and (g) producing one or more products from the liquid fraction, said one or more products comprising at least one of xylose, xylitol, methane, ethanol, or lignosulfonate.

Assignees

• Iogen Corp

Inventors

• Marleau-Gillette Joshua
• Macdonald Daniel G
• Tolan Jeffrey S
• Foody Brian

Classifications

• C10L2290/26

  Composting, fermenting or anaerobic digestion fuel components or materials from which fuels are prepared · CPC title

• Y02E50/10

  Biofuels, e.g. bio-diesel · CPC title

• C12P19/02

  Monosaccharides (2-ketogulonic acid C12P7/60) · CPC title

• C12P5/023

  Methane · CPC title

• C10L2200/0469

  Renewables or materials of biological origin · CPC title