Process for production of lignin, organic acids, organic chemicals, pure co2, and water from kraft black liquor with operational efficiencies

Patent metadata

Field	Value
Publication number	US-2025257526-A1
Application number	US-202519054341-A
Country	US
Kind code	A1
Filing date	Feb 14, 2025
Priority date	Feb 14, 2024
Publication date	Aug 14, 2025
Grant date	—

Abstract

An exemplary embodiment of the present disclosure provides a process for generating new products from a kraft mill and improving operational efficiency of a kraft mill through extraction of bioderived organic acids and liquid CO2 from weak black liquor generated during a kraft process, comprising the steps of: filtering a weak black liquor (BL) stream generated in the kraft process downstream from a brownstock washer to remove a first portion of lignin and generate a reduced lignin or de-lignified permeate and a retentate; removing the reduced lignin or de-lignified permeate from the kraft process; processing at least the de-lignified permeate to generate organic acids, liquid CO2, water, and raffinate containing salts; recovering the organic acids and liquid CO2; and returning the raffinate containing salts to the kraft process downstream of a recovery boiler.

First claim

What is claimed is:

1 . A process for obtaining new products from a kraft mill and for improving operational efficiency of a kraft mill through extraction of bioderived organic acids and liquid CO 2 from weak black liquor generated during a kraft process, comprising the steps of:
filtering a weak black liquor (BL) stream generated in the kraft process downstream from a brownstock washer to remove a first portion of lignin and generate a reduced lignin or delignified permeate and a retentate; removing the reduced lignin or de-lignified permeate from the kraft process; processing at least the de-lignified permeate to generate organic acids, liquid CO 2 , water, and raffinate containing salts; recovering the organic acids, and liquid CO 2 ; and returning the raffinate containing salts to the kraft process downstream of a recovery boiler.

2 . The process of claim 1 , further comprising the step of, allowing the retentate of the filtered weak BL stream to remain within the kraft process.

3 . The process of claim 1 , wherein the processing step further comprises the steps of, passing the reduced lignin or de-lignified permeate through a gas bubbler to generate an aqueous stream and a gas stream;
passing the aqueous stream through an adsorption column to remove a second portion of lignin from the reduced lignin permeate to generate a delignified BL stream; passing the delignified BL stream to a crystallizer to precipitate at least a portion of salt in the delignified BL stream to generate a pretreated BL stream.

4 . The process of claim 3 , wherein the processing step further comprises the steps of:
passing the gas stream to a liquifying unit configured to liquify the gas stream to liquid CO 2 and storing the liquid CO 2 .

5 . The process of claim 3 , further comprising the step of regenerating the adsorption column with an acetone-water mixture.

6 . The process of claim 5 , wherein the processing step further comprises the steps of:
removing, at least a portion of organic acids in the pretreated BL stream to generate a reduced-acid or acid-lean pretreated BL stream and converting the organic acids to one or more organic chemicals; and passing the reduced-acid pretreated BL stream through a reverse-osmosis membrane to generate the water and the raffinate containing salts.

7 . A method of obtaining components from a kraft black liquor feedstock, comprising:
passing a BL feedstock through a NF membrane to remove a first portion of lignin in the BL feedstock to generate a NF permeate; acidifying, with an acidification unit, the NF permeate to generate an aqueous stream and an off-gas stream including CO 2 ; filtering, with a filtration unit, the aqueous stream to remove a second portion of lignin from the aqueous stream to generate a delignified BL stream; removing, at least a portion of organic acids in the pretreated BL stream to generate a reduced-acid pretreated BL stream and a recovered organic acid stream; passing the reduced-acid pretreated BL stream through a membrane to generate a water permeate and a raffinate comprising salt and recovering the water permeate; passing the raffinate comprising salt through a membrane electrolyzer to generate an acidic stream and a basic stream; and liquifying gaseous CO 2 from within the off-gas stream into a liquified CO 2 stream and recovering the liquified CO 2 stream.

8 . The method of claim 7 , wherein the membrane electrolyzer is a Bipolar Membrane Electrodialyzer (BMED).

9 . The method of claim 7 , further comprising causing one or more reactions between the at least a portion of the organic acids from the recovered organic acid stream and one or more catalysts to produce organic chemicals.

10 . The method of claim 9 , wherein the one or more reactions comprise one or more reactions selected from the group consisting of deoxygenation, dehydroxylation, and oligomerization.

11 . The method of claim 7 , wherein the NF membrane is an alkali-stable NF membrane.

12 . The method of claim 7 , wherein the first portion of lignin in the BL feedstock comprises at least 93% of lignin in the BL feedstock.

13 . The method of claim 7 , wherein the filtration unit includes a filter and the aqueous stream passing though the filter has a pH of at least 11.

14 . The method of claim 7 , wherein the second portion of lignin from the NF permeate comprises at least 3% of lignin in the BL feedstock.

15 . The method of claim 7 , wherein passing the BL feedstock through a NF membrane further comprises, separating the NF permeate from a retentate, and wherein the BL feedstock is taken from a kraft process and the NF permeate is processed outside of the kraft process and wherein the retentate is returned to the kraft process.

16 . The method of claim 7 , wherein the acidifying step includes acidifying the NF permeate with H 2 SO 4 to generate the aqueous stream and wherein the off-gas stream includes H 2 S, SO 2 , and CO 2 .

17 . The method of claim 16 , further comprising scrubbing the off-gas stream with a gas scrubber, wherein scrubbing includes introducing the off-gas stream and the basic stream into the gas scrubber, and generating the gaseous CO 2 stream.

18 . The method of claim 7 , wherein the removing step includes removing organic acids from the pretreated BL stream with a simulated-moving bed unit, wherein the simulated-moving bed removes at least 90% of organic acids in the pretreated BL stream.

19 . The method of claim 18 , wherein the simulated-moving bed utilizes a methanol or acetone desorbent.

Assignees

• Georgia Tech Res Inst

Inventors

• Fu Qiang
• Ojelade Opeyemi
• Tran Quyen
• Avendano Marco
• Sinquefield Scott
• Shofner Meisha
• Jones Christopher W
• Nair Sankar

Classifications

• D21C11/0007 Primary

  Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for (volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042) · CPC title

• D21C11/0014

  Combination of various pulping processes with one or several recovery systems (cross-recovery) · CPC title

• D21C11/0042 Primary

  Fractionating or concentration of spent liquors by special methods (concentration by evaporation D21C11/10) · CPC title