# US 10,767,308 B2 · Methods for separating and refining lignin from black liquor and compositions thereof

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- Number: US 10,767,308 B2
- Document ID: US10767308B2
- Status: Granted
- Kind: B2
- Application number: 15/319,935
- Filed: 2015-07-07
- Published: 2017-05-11
- Granted: 2020-09-08
- Earliest claimed: 2014-07-09
- Assignees: Virdia, Inc.
- Applicants: Virdia, Inc.
- Inventors: Robert Jansen; James Alan Lawson; Noa Lapidot
- Web page: https://patentgrep.com/patent/US10767308B2

## CPC

- D21C 11/0007: {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)}
- C07G 1/00: Low-molecular-weight derivatives of lignin (high-molecular-weight derivatives of lignin {C08H6/00})
- C08H 6/00: {Macromolecular compounds derived from lignin, e.g. tannins, humic acids}
- C12P 5/023: {Methane}
- D21C 11/0085: {Introduction of auxiliary substances into the regenerating system in order to improve the performance of certain steps of the latter, the presence of these substances being confined to the regeneration cycle (introduction of compounds in order to make up for the losses of pulping agents D21C11/0035; conventional causticizing of green liquors D21C11/0064; fractionating of spent liquors D21C11/0042)}
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- Y02P 20/582: Recycling of unreacted starting or intermediate materials
- D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- C07G: COMPOUNDS OF UNKNOWN CONSTITUTION (sulfonated fats, oils or waxes of undetermined constitution C07C309/62)
- C08H: DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS (polysaccharides C08B; natural rubber C08C; natural resins or their derivatives C09F; bituminous materials C10)
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The invention relates methods and processes for the separation and refining of lignin from spent cooking liquor, called black liquor, present in industrial chemical plants, and compositions thereof. A process is provided for separating black liquor into at least two, three, or four streams selected from: (i) a gaseous stream comprising volatile sulfur compounds; (ii) a lignin-comprising stream produced by extracting lignin into a limited solubility solvent S1; (iii) a salt stream, comprising solid sodium and sulfate salts; and (iv) a salt-depleted and lignin-depleted aqueous stream comprising hydrocarbons.

## Claims

### Claim 1

A process for separating lignin from black liquor, the process comprising:
(i) contacting the black liquor with a limited-solubility solvent, thereby forming a mixture;
(ii) neutralizing the mixture by addition of CO2;
(iii) filtering the mixture, thereby generating a filtrate and a filtration cake;
(iv) acidifying the filtrate;
(v) separating the filtrate into an organic phase and an aqueous phase;
(vi) removing metal cations from the organic phase; and
(vii) recovering lignin from the organic phase.

### Claim 2 (depends on 1)

The process of claim 1, wherein the limited-solubility solvent comprises a 4-to 8-carbon ketone.

### Claim 3 (depends on 2)

The process of claim 2, wherein the limited-solubility solvent is methyethyl ketone.

### Claim 4 (depends on 1)

The process of claim 1, wherein the contacting the black liquor with the limited-solubility solvent induces precipitation of a salt.

### Claim 5 (depends on 4)

The process of claim 4, wherein the salt comprises a carbonate, bicarbonate, sulfate, or bisulfate ion.

### Claim 6 (depends on 1)

The process of claim 1, wherein the mixture is maintained at a temperature of at least 30° C. to at most 90° C. during the addition of CO2.

### Claim 7 (depends on 1)

The process of claim 1, further comprising halting the addition of CO2 once the mixture has a pH of at least 7.1 to at most 9.5.

### Claim 8 (depends on 1)

The process of claim 1, wherein the acidifying of the filtrate is accomplished by addition of a mineral acid.

### Claim 9 (depends on 1)

The process of claim 1, wherein the recovering lignin from the organic phase comprises evaporating the organic phase, thereby forming a solid lignin.

### Claim 10 (depends on 1)

The process of claim 1, wherein the recovering lignin from the organic phase comprises contacting the organic phase with water at an elevated temperature, thereby forming a lignin precipitate.

### Claim 11 (depends on 10)

The process of claim 10, further comprising filtering the lignin precipitate, thereby collecting a solid lignin.

### Claim 12 (depends on 11)

The process of claim 11, further comprising dissolving the solid lignin in an organic solvent.

### Claim 13 (depends on 12)

The process of claim 12, further comprising subjecting the lignin solution to desulfurization reaction conditions.

### Claim 14 (depends on 13)

The process of claim 13, wherein the desulfurization reaction conditions comprise a desulfurization catalyst.

### Claim 15 (depends on 14)

The process of claim 14, wherein the desulfurization catalyst is selected from Raney nickel, MoS2, CoS2, or a combination thereof.

### Claim 16 (depends on 13)

The process of claim 13, wherein the desulfurization reaction conditions comprise a hydrogen donor.

### Claim 17 (depends on 16)

The process of claim 16, wherein the hydrogen donor is an alcohol.

### Claim 18 (depends on 17)

The process of claim 17, wherein the hydrogen donor is 2-butanol.

### Claim 19 (depends on 1)

The process of claim 1, further comprising subjecting lignin in the organic phase to desulfurization reaction conditions.

### Claim 20 (depends on 19)

The process of claim 19, wherein the desulfurization reaction conditions comprise a desulfurization catalyst.

### Claim 21 (depends on 1)

The process of-claim 1, further comprising contacting the filtration cake with the aqueous phase of the acidified filtrate, thereby forming a slurry.

### Claim 22 (depends on 21)

The process of claim 21, further comprising separating an aqueous solution suitable for anaerobic digestion from the slurry.

### Claim 23 (depends on 22)

The process of claim 22, further comprising anaerobically digesting the aqueous solution suitable for anaerobic digestion to produce methane.

### Claim 24 (depends on 1)

The process of claim 1, wherein the removing metal cations from the organic phase comprises contacting the organic phase with a strong acid cation exchange resin.