Electrochemically mediated gas capture, including from low concentration streams

Patent metadata

Field	Value
Publication number	US-11598012-B2
Application number	US-202017005243-A
Country	US
Kind code	B2
Filing date	Aug 27, 2020
Priority date	Aug 28, 2019
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

Methods, apparatuses, and systems related to the electrochemical separation of target gases from gas mixtures are provided. In some cases, a target gas such as carbon dioxide is captured and optionally released using an electrochemical cell (e.g., by bonding to an electroactive species in a reduced state). Some embodiments are particularly useful for selectively capturing the target gas while reacting with little to no oxygen gas that may be present in the gas mixture. Some such embodiments may be useful in applications involving separations from gas mixtures having relatively low concentrations of the target gas, such as direct air capture and ventilated air treatment.

First claim

What is claimed is:

1. A gas separation system comprising:
a plurality of electrochemical cells in fluidic communication with a gas inlet and a gas outlet, wherein each of the electrochemical cells comprises:
a negative electrode comprising a first electroactive species;
a positive electrode; and
a separator between the negative electrode and the positive electrode, the separator being capable of containing a conductive liquid;

wherein the first electroactive species has:
an oxidized state; and
at least one reduced state in which the species is capable of bonding with a target gas, but for which a reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at at least one temperature that is within a range greater than or equal to 223 K and less than or equal to 573 K.

2. The gas separation system of claim 1 , wherein the at least one reduced state is one in which the species is capable of bonding with the target gas, but for which the reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at at least one temperature that is within a range greater than or equal to 223 K and less than or equal to 373 K.

3. The gas separation system of claim 2 , wherein the first electroactive species comprises an optionally-substituted quinone.

4. The gas separation system of claim 2 , wherein the target gas is carbon dioxide.

5. The gas separation system of claim 1 , wherein the at least one reduced state is one in which the species is capable of bonding with the target gas, but for which the reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at 298 K.

6. The gas separation system of claim 1 , wherein there is a flow field between at least some of the plurality of electrochemical cells.

7. The gas separation system of claim 1 , wherein the at least one reduced state is one in which the species is capable of bonding with the target gas, but for which the reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at at least one temperature that is within a range greater than or equal to 223 K and less than or equal to 423 K.

8. The gas separation system of claim 1 , wherein the first electroactive species comprises an optionally-substituted quinone.

9. The gas separation system of claim 1 , wherein the negative electrode comprises a gas permeable layer.

10. The gas separation system of claim 1 , wherein the target gas is carbon dioxide.

11. A gas separation system comprising:
a plurality of electrochemical cells in fluidic communication with a gas inlet and a gas outlet, wherein each of the electrochemical cells comprises:
a negative electrode comprising a first electroactive species immobilized on the negative electrode; and
a positive electrode;

wherein the first electroactive species has:
an oxidized state; and
at least one reduced state in which the species is capable of bonding with a target gas but for which a reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at at least one temperature that is within a range greater than or equal to 223 K and less than or equal to 573 K.

12. The gas separation system of claim 11 , wherein the at least one reduced state is one in which the species is capable of bonding with the target gas, but for which the reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at at least one temperature that is within a range greater than or equal to 223 K and less than or equal to 373 K.

13. The gas separation system of claim 12 , wherein the negative electrode comprises a primary electroactive composite layer comprising the first electroactive species.

14. The gas separation system of claim 12 , wherein the first electroactive species is part of a polymeric material immobilized on the negative electrode.

15. The gas separation system of claim 12 , wherein the first electroactive species comprises an optionally-substituted quinone.

16. The gas separation system of claim 12 , wherein the first electroactive species comprises one or more of structures chosen from formula (IA) and (IB):

wherein R 1 , R 2 , R 3 , and R 4 can be the same or different, and can be hydrogen, halo, hydroxyl, carboxylate/carboxylic acid, sulfonate/sulfonic acid, alkylsulfonate/alkylsulfonic acid, phosphonate/phosphonic acid, alkylphosphonate/alkylphosphonic acid, acyl, amino, amido, quaternary ammonium, branched or unbranched alkyl, heteroalkyl, alkoxy, glycoxy, polyalkyleneglycoxy, imino, polyimino, branched or unbranched alkenyl, branched or unbranched alkynyl, aryl, heteroaryl, heterocyclyl, nitro, nitrile, thiyl, and/or carbonyl groups, any of which is optionally-substituted, and/or any two adjacent groups of R 1 —R 4 can be joined together to form an optionally-substituted ring.

17. The gas separation system of claim 12 , wherein the first electroactive species comprises one or more of phenanthrenequinone ester (PQ-ester), iodo-phenanthrenequinone (PQ-I), di-iodo-phenanthrenequinone (PQ-I 2 ), phenanthrenequinone (PQ), ortho-naphthquinone (o-NQ), dimethyl-para-naphthquinone (p-NQ-Me 2 ), para-naphthquinone (p-NQ), di-tert-butyl-benzoquinone (TBQ), and benzoquinone (BQ), the structures of which are shown below:

wherein R 5 is optionally-substituted branched or unbranched C1-C18 alkyl.

18. The gas separation system of claim 12 , wherein the negative electrode comprises a gas permeable layer.

19. The gas separation system of claim 12 , wherein the negative electrode is porous.

20. The gas separation system of claim 12 , wherein the each of the electrochemical cells further comprises a conductive liquid, and wherein the conductive liquid comprises a room temperature ionic liquid.

21. The gas separation system of claim 12 , wherein the target gas is carbon dioxide.

22. The gas separation system of claim 12 , wherein each of the electrochemical cells comprises a separator between the negative electrode and the positive electrode, the separator being capable of containing a conductive liquid.

23. The gas separation system of claim 22 , wherein the negative electrode is a first negative electrode, the separator is a first separator, and the each of the electrochemical cells further comprises:
a second negative electrode comprising the first electroactive species; and
a second separator capable of being saturated with a conductive liquid between the positive electrode and the second negative electrode.

24. The gas separation system of claim 11 , wherein the at least one reduced state is one in which the species is capable of bonding with the target gas, but for which the reaction with oxygen (O 2 ) has a change in Gibbs free energy that is greater than or equal to 0 kcal/mol at 298 K.

25. The gas separation system of claim 11 , wherein each of the electrochemical cells further comprises a conductive liquid, and wherein a standard reduction potential for the generation of the at least one reduced state of the first electroactive species in the conductive liquid is more positive than is the standard red

Assignees

• Massachusetts Inst Technology

Inventors

• Voskian Sahag
• Hatton Trevor Alan

Classifications

• C25B9/19

  with diaphragms · CPC title

• C25B11/031

  Porous electrodes · CPC title

• C25B13/02

  characterised by shape or form · CPC title

• Y02P20/151

  Reduction of greenhouse gas [GHG] emissions, e.g. CO2 · CPC title

• Y02C20/40

  of CO2 · CPC title