Method for extracting lignin

• US 20160326203A1
• Filed: 01/09/2015
• Published: 11/10/2016
• Est. Priority Date: 01/10/2014
• Status: Active Grant

• Current Assignee: CH-Bioforce Oy
• Original Assignee: Ab BLN-Woods Ltd
• Inventors: von SCHOULTZ, Sebastian
• Granted Patent: US 10,407,452 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C07G 1/00 Lignin; Lignin derivatives
• CPC Class Codes: C08B 1/00 Preparatory treatment of cellulose for making derivatives thereof , e.g. pre-treatment, pre-soaking, activation
• CPC Class Codes: C10L 2200/0469 Renewables or materials of biological origin
• CPC Class Codes: C10L 2290/06 Heat exchange, direct or indirect
• CPC Class Codes: C10L 2290/30 Pressing, compressing or compacting
• CPC Class Codes: C10L 2290/544 Extraction for separating fractions, components or impurities during preparation or upgrading of a fuel
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/442 Wood or forestry waste
• CPC Class Codes: D21C 1/10 Physical methods for facilitating impregnation
• CPC Class Codes: D21C 3/02 with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
• CPC Class Codes: D21C 3/04 with acids, acid salts or acid anhydrides D21C3/003 and D21C3/222 take precedence
• CPC Class Codes: D21C 3/22 Other features of pulping processes
• 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

The invention relates to a method for removing lignin from lignocellulosic biomass. The method comprises feeding of lignocellulosic biomass and a first aqueous solution into a reactor vessel, the lignocellulosic biomass and the first aqueous solution forming a reaction mixture; reducing the pressure in the reactor vessel below 0.8 bar absolute pressure, preferably 0.5 bar absolute pressure, more preferably below 0.2 bar absolute pressure; keeping the reaction mixture in a predetermined extraction temperature, and adding at least one extraction chemical, such as base or acid, to the reaction vessel and extracting lignin from the biomass to the liquid phase of the reaction mixture.

Claims

1. A method for removing lignin from lignocellulosic biomass, the method comprising:

feeding lignocellulosic biomass and a first aqueous solution, which comprises at least 95 weight-% of water, into a reactor vessel, the lignocellulosic biomass and the first aqueous solution forming a reaction mixture,

reducing the pressure in the reactor vessel below 0.8 bar absolute pressure, and then

heating the reaction mixture in a predetermined extraction temperature of 70-250°

C., and

adding at least one extraction chemical, which comprises a base or an acid, to the reaction vessel when the extraction temperature is reached, and extracting lignin from the biomass to the liquid phase of the reaction mixture.

2. The method according claim 1, further comprising adding the at least one extraction chemical as one single dose when the predetermined extraction temperature is reached.

3. The method according claim 1, wherein the extraction chemical comprises a base, which is sodium hydroxide, potassium hydroxide, magnesium hydroxide, sodium sulfide, an acid, which is formic acid, acetic acid, hydrochloric acid or sulfuric acid, or an organosolv, which is acetic acid, acetone, ethanol or any mixture thereof.

4. The method according claim 1, wherein the extraction chemical comprises a base and the pH during the extraction of lignin is >

10.

5. The method according to claim 1, further comprising using lignin rich extract from a previous extraction as an extraction chemical.

6. The method according to claim 1, wherein the predetermined extraction temperature is in the range of 110-250°

C.

7. The method according to claim 1, wherein the pressure inside the reactor vessel during the extraction of lignin is 5-8 bar absolute pressure.

8. The method according to claim 1, further comprising separating carbohydrates from the reaction mixture, prior to the extraction of lignin, by extracting the reaction mixture with a second aqueous solution.

9. The method according to claim 8, wherein the pH of the second aqueous solution is 3-10.

10. The method according to claim 1, further comprising adding at least one chemical oxygen scavenger, such as ascorbic acid or the like to the first aqueous solution and/or to the second aqueous solution.

11. The method according to claim 1, further comprising continuing the lignin extraction by circulating the liquid phase of the reaction mixture through the biomass as long as the desired reduced lignin content of the biomass is reached.

12. The method according to claim 1, further comprising using the biomass, after the extraction of lignin,

for production of paper, board, or the like;

for production of dissolving pulp or nanocellulose;

for production pellets or as raw material for fuel; and

/or

for production of particle board (chipboard).

13. The method according to according to claim 1, further comprising using the extracted lignin, after the separation from the reaction mixture, for production of energy or fuel and/or as raw material for chemical products, such as carbon fibers, phenols or biocomposites.

14. The method according to claim 1, wherein the biomass is selected from biomass comprising wood-based materials, such as genus Pinus, Betula or Picea, and/or from non-wood materials, such as bamboo, bagasse, hemp, wheat or rice straw.

15. The method according to claim 1, wherein the biomass is fed to the reaction vessel, the pressure in the reactor vessel is reduced to the desired level and the first aqueous solution is fed to the reactor vessel while the pressure is kept reduced.

16. The method according to claim 1, wherein the pressure in the reactor vessel is reduced below 0.5 bar absolute pressure.

17. The method according to claim 1, wherein the pressure in the reactor vessel is reduced below 0.2 bar absolute pressure.

18. The method according to claim 1, wherein the extraction chemical comprises a base and the pH during the extraction of lignin is >

12.

19. The method according to claim 1, wherein the extraction chemical comprises a base and the pH during the extraction of lignin is >

13.

20. The method according to claim 1, wherein the predetermined extraction temperature is in the range of 135-160°

C.