Electrochemical capture of Lewis acid gases

Patent metadata

Field	Value
Publication number	US-11857919-B2
Application number	US-202117508411-A
Country	US
Kind code	B2
Filing date	Oct 22, 2021
Priority date	Aug 28, 2019
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

Methods, apparatuses, and systems related to electrochemical capture of Lewis acid gases from fluid mixtures are generally described. Certain embodiments are related to electrochemical methods involving selectively removing a first Lewis acid gas from a fluid mixture containing multiple types of Lewis acid gases (e.g., a first Lewis acid gas and a second Lewis acid gas). Certain embodiments are related to electrochemical systems comprising certain types of electroactive species having certain redox states in which the species is capable of binding a first Lewis acid gas but for which binding with a second Lewis acid gas is thermodynamically and/or kinetically unfavorable. The methods, apparatuses, and systems described herein may be useful in carbon capture and pollution mitigation applications.

First claim

What is claimed is:

1. A method, comprising:
exposing a fluid mixture comprising a first gas comprising a first Lewis acid and a second gas comprising a second Lewis acid to one or more electroactive species in a reduced state;
forming first complexes between an amount of the first Lewis acid and a first portion of the one or more electroactive species in the reduced state;
forming second complexes between an amount of the second Lewis acid and a second portion of the one or more electroactive species in the reduced state; and
oxidizing at least some of the second complexes, while oxidizing essentially none of the first complexes or oxidizing less than or equal to 70 mole % of the first complexes.

2. The method of claim 1 , wherein forming the first complexes is via bonding the amount of the first Lewis acid to the first portion of the one or more electroactive species in the reduced state.

3. The method of claim 1 , wherein forming the second complexes is via bonding the amount of the second Lewis acid to the second portion of the one or more electroactive species in the reduced state.

4. The method of claim 1 , wherein the oxidizing at least some of the second complexes comprises dissociating the at least some of the second complexes and releasing an amount of the second Lewis acid from the second complexes.

5. The method of claim 4 , wherein the step of oxidizing at least some of the second complexes is performed while oxidizing essentially none of the first complexes or oxidizing less than or equal to 10 mole % of the first complexes.

6. The method of claim 4 , wherein the fluid mixture is a gas mixture or a liquid mixture.

7. The method of claim 4 , wherein the exposing is in the presence of a liquid comprising an electrolyte solution.

8. The method of claim 7 , wherein the liquid comprising the electrolyte solution comprises the one or more electroactive species.

9. The method of claim 4 , wherein the step of oxidizing at least some of the second complexes comprises exposing the second complexes to an oxidative potential caused by application of an electrical potential difference across an electrochemical cell.

10. The method of claim 9 , wherein the step of oxidizing at least some of the second complexes comprises exposing the second complexes to the electrochemical cell.

11. The method of claim 9 , wherein, during at least the step of oxidizing at least some of the second complexes, the one or more electroactive species are immobilized on an electrode of the electrochemical cell.

12. The method of claim 9 , wherein, during at least the step of exposing the fluid mixture to the one or more electroactive species in a reduced state, the one or more electroactive species are dissolved in a liquid that is a separate phase than the fluid mixture.

13. The method of claim 4 , wherein the step of oxidizing at least some of the second complexes is performed during a first period of time, and the method further comprises oxidizing at least some of the first complexes as part of a second oxidizing step performed during a second period of time.

14. The method of claim 13 , wherein the step of oxidizing at least some of the first complexes comprises exposing the first complexes to an oxidative potential caused by application of an electrical potential difference across an electrochemical cell.

15. The method of claim 13 , wherein the step of oxidizing at least some of the second complexes comprises exposing the second complexes to an oxidative potential caused by application of an electrical potential difference across a first electrochemical cell; and
the step of oxidizing at least some of the first complexes comprises exposing the first complexes to an oxidative potential caused by application of an electrical potential difference across a second electrochemical cell.

16. The method of claim 15 , wherein the electrical potential difference applied across the first electrochemical cell is different than the electrical potential difference applied across the second electrochemical cell.

17. The method of claim 13 , wherein the oxidizing at least some of the first complexes comprises dissociating the at least some of the first complexes and releasing an amount of the first Lewis acid gas from the first complexes.

18. The method of claim 4 , wherein the first Lewis acid is chosen from sulfur dioxide (SO 2 ), sulfur oxides (SO x ), nitrogen oxides (NO x ), R 2 S, carbonyl sulfide (COS), R 3 B, boron trifluoride (BF 3 ), or a combination thereof, wherein each R is independently H, branched or unbranched C 1 -C 8 alkyl, aryl, cyclyl, heteroaryl, or heterocyclyl.

19. The method of claim 18 , wherein R 2 S is hydrogen sulfide (H 2 S).

20. The method of claim 4 , wherein the second Lewis acid comprises one or more species chosen from carbon dioxide, nitrogen oxides, R 3 B, or R 2 S, wherein each R is independently H, branched or unbranched C 1 -C 8 alkyl, aryl, cyclyl, heteroaryl, or heterocyclyl.

21. The method of claim 4 , wherein the second Lewis acid gas is carbon dioxide (CO 2 ).

22. The method of claim 4 , wherein the one or more electroactive species comprises one or more organic species chosen from optionally-substituted quinone, optionally-substituted thiolate, an optionally-substituted bipyridine, an optionally-substituted phenazine, and an optionally-substituted phenothiazine.

23. An electrochemical apparatus for at least partial gas separation, comprising:
a first electrochemical cell comprising a first electrode;
a second electrochemical cell comprising a second electrode;
an inlet for receiving a fluid mixture;
a conduit in fluidic communication with the first electrode, the second electrode, and the inlet, wherein the inlet, conduit, and first electrode are arranged such that flow of the fluid mixture received by the inlet can expose the fluid mixture to the first electrode; and
an intermediate outlet positioned and configured to receive a reaction product produced at the first electrode and separated from the fluid mixture;
wherein the conduit and the second electrode are arranged such that flow of the fluid mixture at least partially depleted of the reaction product produced at the first electrode can expose the fluid mixture at least partially depleted of the reaction product to the second electrode.

24. The electrochemical apparatus of claim 23 , wherein the inlet is in fluidic communication with a source of the fluid mixture.

25. The electrochemical apparatus of claim 24 , wherein the fluid mixture comprises a first gas comprising a first Lewis acid and/or a first complex formed between a first Lewis acid and one or more electroactive species.

26. The electrochemical apparatus of claim 25 , wherein the inlet is also in fluidic communication with a liquid comprising one or more electroactive species.

27. The electrochemical apparatus of claim 23 , wherein at least a portion of one or more electroactive species are immobilized on the first electrode.

28. The electrochemical apparatus of claim 23 , wherein a first portion of one or more electroactive species are immobilized on the first electrode, and a second portion of the one or more electroactive species are immobilized on the second electrode.

29. The electrochemical apparatus of claim 25 , wherein the fluid mixture further comprises a second gas comprising a second Lewis ac

Assignees

• Massachusetts Inst Technology

Inventors

• Voskian Sahag
• Hatton Trevor Alan
• Halliday Cameron G

Classifications

• B01D53/326 Primary

  in electrochemical cells · CPC title

• B01D53/62

  Carbon oxides · CPC title

• B01D53/96

  Regeneration, reactivation or recycling of reactants · CPC title

• C25B9/05

  Pressure cells · CPC title

• C25B9/70

  Assemblies comprising two or more cells · CPC title