# US 12,005,392 B2 · Electrochemical process for gas separation

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- Number: US 12,005,392 B2
- Document ID: US12005392B2
- Status: Granted
- Kind: B2
- Application number: 17/685,285
- Filed: 2022-03-02
- Published: 2022-06-16
- Granted: 2024-06-11
- Earliest claimed: 2015-10-27
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Sahag Voskian; Trevor Alan Hatton
- Web page: https://patentgrep.com/patent/US12005392B2

## CPC

- B01D 53/326: {in electrochemical cells}
- C25B 9/19: with diaphragms
- C25B 11/085: Organic compound
- C25B 13/04: characterised by the material
- B01D 2257/504: Carbon dioxide
- Y02C 20/40: of CO2
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

The present disclosure generally relates to apparatuses, systems, and methods for separating a target species (e.g., CO2) from a gas mixture (e.g., gas stream) via an electrochemical process.

## Claims

### Claim 1

A method of treating a gas stream, the method comprising:
applying a first potential difference across at least one negative electrode and a positive electrode of an electrochemical cell, wherein the at least one negative electrode comprises a first electroactive species, the positive electrode comprises a second electroactive species, and the electrochemical cell comprises a separator positioned between the at least one negative electrode and the positive electrode, wherein the separator comprises:
(a) a conductive electrolyte having a room temperature vapor pressure of less than 10−5 Pa; and/or
(b) a room temperature ionic liquid; and
introducing a gas stream comprising a target species comprising an aprotic acidic gas to the electrochemical cell to bond the target species to the first electroactive species to produce a treated gas stream; and
applying a second, different potential difference across the at least one negative electrode and the positive electrode of the electrochemical cell to release the target species from the first electroactive species to produce a target species-rich gas stream;
wherein:
the application of the first potential difference causes a reduction reaction resulting in at least some of the first electroactive species being in a reduced state;
the target species bonds to the first electroactive species in the reduced state to produce the treated gas stream;
the application of the second potential difference causes an oxidation reaction at the at least one negative electrode resulting in the oxidation of at least some of the first electroactive species in the reduced state bonded to the target species;
the target species is released from the oxidized first electroactive species to produce the target species-rich gas stream; and
the first electroactive species comprises a quinone.

### Claim 2 (depends on 1)

The method of claim 1, wherein the separator comprises a conductive electrolyte having a room temperature vapor pressure of less than 10−5 Pa.

### Claim 3 (depends on 2)

The method of claim 2, wherein the conductive electrolyte comprises a conductive liquid having a room temperature vapor pressure of less than 10−5 Pa.

### Claim 4 (depends on 1)

The method of claim 1, wherein the separator comprises a room temperature ionic liquid.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first electroactive species is immobilized on and/or within the at least one negative electrode.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first electroactive species comprises a polymeric quinone.

### Claim 7 (depends on 1)

The method of claim 1, wherein the aprotic acidic gas comprises carbon dioxide, sulfur dioxide, a borane, or a combination thereof.

### Claim 8 (depends on 7)

The method of claim 7, wherein the aprotic acidic gas comprises carbon dioxide.

### Claim 9 (depends on 8)

The method of claim 8, wherein the first electroactive species comprises polyanthraquinone.

### Claim 10 (depends on 1)

The method of claim 1, wherein the at least one negative electrode is porous.

### Claim 11 (depends on 1)

The method of claim 1, wherein the target species bonds to the first electroactive species in the reduced state via a covalent bond.

### Claim 12 (depends on 3)

The method of claim 3, wherein the first electroactive species is immobilized on and/or within the at least one negative electrode.

### Claim 13 (depends on 12)

The method of claim 12, wherein the first electroactive species comprises a polymeric quinone.

### Claim 14 (depends on 13)

The method of claim 13, wherein the aprotic acidic gas comprises carbon dioxide, sulfur dioxide, a borane, or a combination thereof.

### Claim 15 (depends on 14)

The method of claim 14, wherein the aprotic acidic gas comprises carbon dioxide.

### Claim 16 (depends on 15)

The method of claim 15, wherein the at least one negative electrode is porous.

### Claim 17 (depends on 16)

The method of claim 16, wherein the concentration of carbon dioxide in the gas stream introduced to the electrochemical cell is between 10 ppm and 500 ppm.

### Claim 18 (depends on 4)

The method of claim 4, wherein the first electroactive species is immobilized on and/or within the at least one negative electrode.

### Claim 19 (depends on 18)

The method of claim 18, wherein the first electroactive species comprises a polymeric quinone.

### Claim 20 (depends on 19)

The method of claim 19, wherein the aprotic acidic gas comprises carbon dioxide, sulfur dioxide, a borane, or a combination thereof.

### Claim 21 (depends on 20)

The method of claim 20, wherein the aprotic acidic gas comprises carbon dioxide.

### Claim 22 (depends on 21)

The method of claim 21, wherein the at least one negative electrode is porous.

### Claim 23 (depends on 22)

The method of claim 22, wherein the concentration of carbon dioxide in the gas stream introduced to the electrochemical cell is between 10 ppm and 500 ppm.

### Claim 24 (depends on 3)

The method of claim 3, wherein the first electroactive species comprises a polymeric quinone.

### Claim 25 (depends on 24)

The method of claim 24, wherein the aprotic acidic gas comprises carbon dioxide, sulfur dioxide, a borane, or a combination thereof.

### Claim 26 (depends on 25)

The method of claim 25, wherein the aprotic acidic gas comprises carbon dioxide.

### Claim 27 (depends on 26)

The method of claim 26, wherein the at least one negative electrode is porous.

### Claim 28 (depends on 27)

The method of claim 27, wherein the concentration of carbon dioxide in the gas stream introduced to the electrochemical cell is between 10 ppm and 500 ppm.

### Claim 29 (depends on 4)

The method of claim 4, wherein the first electroactive species comprises a polymeric quinone.

### Claim 30 (depends on 29)

The method of claim 29, wherein the aprotic acidic gas comprises carbon dioxide, sulfur dioxide, a borane, or a combination thereof.

### Claim 31 (depends on 30)

The method of claim 30, wherein the aprotic acidic gas comprises carbon dioxide.

### Claim 32 (depends on 31)

The method of claim 31, wherein the at least one negative electrode is porous.

### Claim 33 (depends on 32)

The method of claim 32, wherein the concentration of carbon dioxide in the gas stream introduced to the electrochemical cell is between 10 ppm and 500 ppm.

### Claim 34 (depends on 3)

The method of claim 3, wherein the at least one negative electrode is porous.

### Claim 35 (depends on 4)

The method of claim 4, wherein the at least one negative electrode is porous.

### Claim 36 (depends on 1)

The method of claim 1, wherein the concentration of the target species in the gas stream introduced to the electrochemical cell is between 10 ppm and 500 ppm.