Compositions, methods, and systems for carbon capture

Abstract

Described herein are methods and systems for capturing carbon dioxide gas from a gas stream.

Description

[0001] COMPOSITIONS, METHODS, AND SYSTEMS FOR CARBON CAPTURE

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims benefit of priority7of U.S. Provisional Application No. 63 / 650,870, filed May 22, 2024, which is hereby incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] Economies have begun transitioning towards less-carbon intensive energy' sources for transportation, electricity generation, industrial processes, and heating. While use of renewable energy sources is expected to grow, fossil fuels are expected to remain a major energy source for many years to come. Therefore, carbon capture, utilization, and storage will be a crucial bridging technology7in the sustainable transition of energy sources.

[0006] SUMMARY

[0007] Carbon capture, utilization, and storage (CCUS) has been considered crucial toward carbon neutrality7in response to environmental concerns associated with excessive emissions of carbon dioxide (CO2). As part of CCUS, amine-based post-combustion capture (PCC) has been commercially used, but it is energy-intensive to strip the CO2 captured by conventional amine solutions as carbamates while regenerating the amine solvent by heating it to a high temperature (e.g., 120 - 180°C). The regeneration step accounts for a large fraction of the total operating cost. Also, the traditional method of CO2 “catch-and-release” is unnecessary' when the downstream processes in carbon management do not require CO2 as a carbon carrier. Many green chemicals can be generated from bicarbonate in aqueous media at lower costs and carbon intensity than from CO2.

[0008] Described herein are methods that involve CO2 capture as bicarbonate, improving the overall efficiency of carbon management by not using CO2 as a carbon carrier. These methods can involve (i) CO2 capture as bicarbonate, for example, using a surface-active tertiary amine; and / or (ii) bicarbonate separation and amine regeneration in a single step using electrochemical methods. These methods can substantially increase the energy efficiency of CO2 capture in comparison to conventional CO2 stripping processes that involve (and are thus burdened by) the need for temperature swings. Amine-based post-combustion capture (PCC) is a well-proven and commercially used technology for CO2 capture with CO2 recovery rates of up to 800 tonnes / day. PCC typically uses a single or a blend of reactive aqueous amine solutions to react chemically with CO2 gas in an acid-base reaction. Then, the CO2 gas is subsequently stripped from the amine solution at high temperatures (e.g., 120-180°C), while regenerating the amine solvent. The regeneration step is considered the main drawback of this technology, and its regeneration cost can be as high as 70% of the total operating cost. The methods described herein can improve the energy efficiency of CO2 capture as part of overall carbon management processes.

[0009] A widely studied strategy for improving the energy efficiency in PCC is the development of less energy-intensive capture solvents; for example, mixtures of different amines, ionic liquids (IL), and mesoporous catalysts. Alternatively, capturing CO2 in a non- gaseous form such as bicarbonate (HCO3J is an effective, practical, and stable method for delivering CCh-bearing species to the utilization unit (such as an electrolyzer) that produces green chemicals, such as formate / formic acid. Figure 1 schematically shows the bicarbonate pathway of CO2 capture in PCC to be integrated with bicarbonate electrolysis for a variety of chemicals and fuels, including formate species.

[0010] Capturing CO2 as bicarbonate is a new process that necessitates a process of bicarbonate separation and amine deprotonation. This separation process is directly compared with the energy-intensive process of CO2 sorption / desorption by temperature swing with conventional amines. We propose methods that involve bicarbonate separation and amine regeneration in one step using ion exchange membranes in a bipolar membrane electrodialysis (BPED) process.

[0011] In the proposed bicarbonate pathway, the separation and regeneration processes can be more energy-efficient than the conventional technologies because of two main differences: (1) the bicarbonate product and the base (surface-active amine) are not attached, but co-exist as ionic interactions. This chemical environment is a key difference that can yield a greater energy reduction in comparison to thermal methods; and (2) the bicarbonate product is not chemically altered to be released as CO2 gas during the separation. Further, the proposed system can be completely electrified with no need for heat or pressurization in any aspect of the process.

[0012] The integration of ion exchange membrane separations within the BPED technology into the CCh-capture-as-bicarbonate pathway can represent a significant departure from conventional methodologies. This strategy enables separation of the bicarbonate product from the CO2 capture process, and deprotonation of the surface-active tertiary amine simultaneously.

[0013] The methods described herein can provide one or more of the following advantages over the use of CO2 gas as a carbon carrier for an integrated carbon capture / conversion process: (i) operational benefits since it can substantially reduce the complexity’ of transportation / storage facilities related to handling high-pressure CO2 gas (e.g.. 14 MPa); ii) improvement of the CO2 mass transfer rates in aqueous carbon capture technologies because of the 100 times greater carbon concentration in saturated solutions (3.3 M for saturated KHCOs compared with 0.033 M for saturated CO2); (iii) 50% less energy-intensive bicarbonate conversion into formic acid and formate species using an electrochemical reduction, in comparison to CO2 gas reduction; and / or iv) no need to strip the CO2 captured by amine solutions using an energy-intensive temperature swing process, unlike in the traditional CCh-catch-and-release process.

[0014] Accordingly, provided herein are methods for capturing carbon dioxide gas from a gas stream. These methods can comprise contacting the gas stream with a capture solution comprising a surface-active gas capture agent to form a bicarbonate salt of the surface-active gas capture agent; and processing the capture solution to separate the bicarbonate from the capture solution and regenerate the surface-active gas capture agent.

[0015] In some embodiments, the surface-active gas capture agent comprises an amine moiety, and processing the capture solution to regenerate the surface-active gas capture agent comprises deprotonating the amine moiety'.

[0016] In some embodiments, processing the capture solution comprises subjecting the capture solution to electrodialysis to separate the bicarbonate from the capture solution. In some embodiments, the electrodialysis comprises electrically driven separation of bicarbonate ions from protonated surface-active gas capture agent. In some embodiments, the electrodialysis is performed in an electrochemical cell comprising an anode, a cathode, and one or more compartments for fluid flow defined by ion exchange membranes.

[0017] In some embodiments, the electrodialysis comprises bipolar membrane electrodialysis (BPED). In some embodiments, the surface-active gas capture agent comprises an amine moiety’, and BPED further comprises amine deprotonation by hydroxyl ions generated from water splitting to regenerate the surface-active gas capture agent. In some embodiments, the surface-active gas capture agent comprises an amine moiety, and processing the capture solution further comprises subjecting a solution comprising a base to electrodialysis to provide hydroxyl ions to regenerate the surface-active gas capture agent.

[0018] In some embodiments, bicarbonate separation and regeneration of the surface-active gas capture agent occur in a single step. In some embodiments, the bicarbonate separation and the regeneration of the surface-active gas capture agent occurs in a single compartment.

[0019] In other embodiments, bicarbonate separation and regeneration of the surface-active gas capture agent occur in two separate steps performed in two separate compartments.

[0020] In some embodiments, the method further comprises electrochemical conversion of the bicarbonate.

[0021] In some embodiments, processing the capture solution further comprises subjecting a solution comprising a potassium salt or a sodium salt to electrodialysis to provide potassium ions or sodium ions to produce a product stream comprising potassium bicarbonate or sodium bicarbonate.

[0022] In some embodiments, the surface-active gas capture agent comprises a blend of a gas capture agent and a surfactant. In other embodiments, the surface-active gas capture agent comprises a surfactant comprising an amine moiety.

[0023] In some embodiments, the surface-active gas capture agent is present in the capture solution in an amount of from 0.5% by weight up to an aqueous solubility limit of the surface-active gas capture agent, based on a total weight of the capture solution, such as from 0.5% to 40% by weight, from 5% to 40% by weight, from 10% to 40% by weight, from 15% to 40% by weight, from 20% to 40% by weight, or from 25% to 40% by weight, based on a total weight of the capture solution.

[0024] In some embodiments, the capture solution further comprises a surfactant.

[0025] In some embodiments, the capture solution comprises an aqueous solution.

[0026] The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

[0027] DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic representation of a proposed CO2 capture into bicarbonate pathway for CCUS technologies. Figure 2 illustrates a proposed mechanism for the separation of bicarbonate while deprotonating amine.

[0029] Figure 3 is a schematic illustration of the proposed Direct Air CO2 capture as a bicarbonate pathway for efficient carbon management

[0030] Figure 4 is a schematic illustration of the electrochemically driven amine regeneration and bicarbonate separation using BPED.

[0031] Figures 5A and 5B schematically illustrate the principles involved in bicarbonate separation and amine regeneration using ion exchange membranes.

[0032] Figure 6 shows an example system for performing bipolar membrane electrodialysis in a single step to both separate the bicarbonate and regenerate the amine capture agent.

[0033] Figure 7 shows an example system for performing two-step bipolar membrane electrodialysis.

[0034] Figure 8 is a plot comparing the performance of the process illustrated in Figure 6 (bipolar membrane electrodialysis in a single step; "Single Step BPED"’) and the process illustrated in Figure 7 (two-step bipolar membrane electrodialysis; “2-Step BPED).

[0035] Figure 9 shows an example in which bicarbonate separation and amine regeneration were performed in a single step using “Anion-Exchange Enhanced Electrodialysis” (AE-ED)

[0036] Figure 10 is a plot showing the performance of the AE-ED system illustrated in Figure 9.

[0037] Figure 11 is a plot showing the results of preliminary studies to evaluate the effect of different applied voltages on BPED systems.

[0038] DETAILED DESCRIPTION

[0039] A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

[0040] Definitions

[0041] To facilitate understanding of the disclosure set forth herein, a number of terms are defined below. Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference. General Definitions

[0042] As used in this specification and the following claims, the terms “comprise” (as well as forms, derivatives, or variations thereof, such as “comprising” and “comprises”) and “include” (as well as forms, derivatives, or variations thereof, such as “including” and “includes”) are inclusive (i.e., open-ended) and do not exclude additional elements or steps. For example, the terms "comprise" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Other than where noted, all numbers expressing quantities of ingredients, reaction conditions, geometries, dimensions, and so forth used in the specification and claims are to be understood at the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, to be constmed in light of the number of significant digits and ordinary rounding approaches.

[0043] Accordingly, these terms are intended to not only cover the recited element(s) or step(s), but may also include other elements or steps not expressly recited. Furthermore, as used herein, the use of the terms “a”, “an”, and “the” when used in conjunction with an element may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” Therefore, an element preceded by “a” or “an” does not. without more constraints, preclude the existence of additional identical elements.

[0044] Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. By “about” is meant within 5% of the value, e.g., within 4, 3, 2, or 1% of the value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. A range may be construed to include the start and the end of the range. For example, a range of 10% to 20% (i.e., range of 10%-20%) can includes 10% and also includes 20%, and includes percentages in between 10% and 20%, unless explicitly stated otherwise herein. As used herein, the terms "may," "optionally," and "may optionally" are used interchangeably and are meant to include cases in which the condition occurs as well as cases in which the condition does not occur. Thus, for example, the statement that a formulation "may include an excipient" is meant to include cases in which the formulation includes an excipient as well as cases in which the formulation does not include an excipient.

[0045] It is understood that when combinations, subsets, groups, etc. of elements are disclosed (e.g.. combinations of components in a composition, or combinations of steps in a method), that while specific reference of each of the various individual and collective combinations and permutations of these elements may not be explicitly disclosed, each is specifically contemplated and described herein. By way of example, if a composition is described herein as including a component of type A, a component of type B, a component of type C, or any combination thereof, it is understood that this phrase describes all of the various individual and collective combinations and permutations of these components. For example, in some embodiments, the composition described by this phrase could include only a component of type A. In some embodiments, the composition described by this phrase could include only a component of type B. In some embodiments, the composition described by this phrase could include only a component of type C. In some embodiments, the composition described by this phrase could include a component of type A and a component of type B. In some embodiments, the composition described by this phrase could include a component of type A and a component of type C. In some embodiments, the composition described by this phrase could include a component of type B and a component of type C. In some embodiments, the composition described by this phrase could include a component of type A, a component of type B, and a component of type C. In some embodiments, the composition described by this phrase could include two or more components of type A (e.g.. Al and A2). In some embodiments, the composition described by this phrase could include two or more components of type B (e.g., Bl and B2). In some embodiments, the composition described by this phrase could include two or more components of type C (e.g., Cl and C2). In some embodiments, the composition described by this phrase could include two or more of a first component (e.g., two or more components of type A (Al and A2)), optionally one or more of a second component (e g., optionally one or more components of type B), and optionally one or more of a third component (e.g., optionally one or more components of type C). In some embodiments, the composition described by this phrase could include two or more of a first component (e.g., two or more components of type B (Bl and B2)), optionally one or more of a second component (e.g., optionally one or more components of type A), and optionally one or more of a third component (e.g.. optionally one or more components of type C). In some embodiments, the composition described by this phrase could include two or more of a first component (e.g., two or more components of type C (Cl and C2)), optionally one or more of a second component (e.g., optionally one or more components of type A), and optionally one or more of a third component (e.g.. optionally one or more components of type B).

[0046] Chemical Definitions

[0047] Terms used herein will have their customary' meaning in the art unless specified otherwise. The organic moieties mentioned when defining variable positions within the general formulae described herein (e.g., the term "‘halogen”) are collective terms for the individual substituents encompassed by the organic moiety. Ph in Formula I refers to a phenyl group.

[0048] The prefix Cn-Cm preceding a group or moiety indicates, in each case, the possible number of carbon atoms in the group or moiety that follows.

[0049] As used herein, the term ‘‘substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, and aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, those described below. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, heteroatoms present in a compound or moiety, such as nitrogen, can have hydrogen substituents and / or any permissible substituents of organic compounds described herein which satisfy the valency of the heteroatom. This disclosure is not intended to be limited in any manner by the permissible substituents of organic compounds. Also, the terms “substitution” or “substituted with” include the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound (e.g., a compound that does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc.

[0050] The term "optionally substituted," as used herein, means that substitution with an additional group is optional and therefore it is possible for the designated atom to be unsubstituted. Thus, by use of the term “optionally substituted” the disclosure includes examples where the group is substituted and examples where it is not. “Z1,” “Z2,” “Z?,” and “Z4” are used herein as generic symbols to represent various specific substituents. These symbols can be any substituent, not limited to those disclosed herein, and when they are defined to be certain substituents in one instance, they can, in another instance, be defined as some other substituents.

[0051] As used herein, the term “alkyl” refers to saturated, straight-chained or branched saturated hydrocarbon moieties. Unless otherwise specified, C1-C24 (e.g., C1-C22. C1-C20. Ci- Cis, C1-C16, C1-C14, C1-C12, C1-C10, Ci-Cs, C1-C6. or C1-C4) alkyl groups are intended. Examples of alkyl groups include methyl, ethyl, propyl, 1-methyl-ethyL butyl, 1 -methylpropyl, 2-methyl-propyl, 1,1-dimethyl-ethyl, pentyl, 1 -methyl-butyl, 2-methyl-butyl, 3- methyl-butyl, 2,2-dimethyl-propyl, 1-ethyl-propyl, hexyl, 1,1-dimethyl-propyl, 1,2-dimethyl- propyl, 1-methyl-pentyl. 2-methyl-pentyl. 3-methyl-pentyl, 4-methyl-pentyl, 1.1 -dimethylbutyl, 1,2-dimethyl-butyl, 1,3-dimethyl-butyl, 2,2-dimethyl-butyL 2,3-dimethyl-butyl, 3,3- dimethyl-butyl, 1-ethyl-butyl, 2-ethyl-butyl, 1,1,2-trimethyl-propyl, 1 ,2,2-trimethyl-propyl, 1- ethyl-l-methyl-propyl, and l-ethyl-2-methyl-propyl. Alky l substituents may be unsubstituted or substituted with one or more chemical moieties. The alkyd group can be substituted with one or more groups including, but not limited to, hydroxy, halogen, acyl, alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, acyl, aldehyde, amino, carboxylic acid, ester, ether, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, thiosulfonate (e.g., -SSChRa), or thiol, as described below, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied. The alkyl group can also include one or more heteroatoms (e.g., from one to three heteroatoms) incorporated within the hydrocarbon moiety. Examples of heteroatoms include, but are not limited to, nitrogen, oxygen, sulfur, and phosphorus.

[0052] Throughout the specification “alkyl” is generally used to refer to both unsubstituted alkyl groups and substituted alkyl groups; however, substituted alkyl groups are also specifically referred to herein by identifying the specific substituent(s) on the alkyl group. For example, the term “halogenated alky l” specifically refers to an alkyl group that is substituted with one or more halides (halogens; e.g., fluorine, chlorine, bromine, or iodine). The term “alkoxyalkyl” specifically refers to an alkyl group that is substituted with one or more alkoxy groups, as described below. The term “alkylamino” specifically refers to an alkyl group that is substituted with one or more amino groups, as described below, and the like. The term “alkylthiol” specifically refers to an alkyl group that is substituted with one or more thiol groups, as described below, and the like. When “alkyl” is used in one instance and a specific term such as “alkylalcohol” is used in another, it is not meant to imply that the term “alkyl” does not also refer to specific terms such as “alkylalcohol” and the like.

[0053] This practice is also used for other groups described herein. That is, while a term such as “cycloalkyl” refers to both unsubstituted and substituted cycloalkyd moieties, the substituted moieties can, in addition, be specifically identified herein; for example, a particular substituted cycloalkyl can be referred to as, e.g, an “alkylcycloalky l.” Similarly, a substituted alkoxy can be specifically referred to as. e.g, a “halogenated alkoxy.” a particular substituted alkenyl can be, e.g., an “alkenylalcohol,” and the like. Again, the practice of using a general term, such as “cycloalkyl,” and a specific term, such as “alkylcycloalkyl,” is not meant to imply that the general term does not also include the specific term.

[0054] As used herein, the term “alkenyl” refers to unsaturated, straight-chained, or branched hydrocarbon moieties containing a double bond. Unless otherwise specified, C2-C24 (e.g., C2- C22, C2-C20, C2-C18, C2-C16, C2-C14, C2-C12, C2-C10, C2-C8, C2-C6, C2-C4) alkenyl groups are intended. Alkenyl groups may contain more than one unsaturated bond. Examples include ethenyl, 1-propenyl, 2-propenyl. 1 -methylethenyl. 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-

[0055] 1 -propenyl, 2-methyl- 1-propenyl, 1 -methyl-2-propenyl, 2-methyl-2-propenyl, 1 -pentenyl, 2- pentenyl, 3-pentenyl, 4-pentenyl, 1 -methyl- 1-butenyl, 2-methyl- 1-butenyl, 3-methyl-l- butenyl, 1 -methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, l-methyl-3-butenyl, 2- methyl-3-butenyl, 3-methyl-3-butenyl, l,l-dimethyl-2-propenyl, 1 ,2-dimethyl- 1-propenyl,

[0056] 1.2-dimethyl-2-propenyl, 1 -ethyl- 1-propenyl, 1 -ethyl-2-propenyl. 1-hexenyL 2-hexenyl, 3- hexenyl, 4-hexenyl, 5-hexenyl, 1 -methyl- 1 -pentenyl, 2-methyl- 1 -pentenyl, 3-methyl-l - pentenyl, 4-methyl-l -pentenyl, 1 -methyl-2-pentenyl, 2-methyl-2-pentenyl, 3-methyl-2- pentenyl, 4-methyl-2-pentenyl, l-methyl-3-pentenyl, 2-methyl-3-pentenyl, 3-methyl-3- pentenyl. 4-methyl-3-pentenyl, l-methyl-4-pentenyl, 2-methyl-4-pentenyl, 3-methyl-4- pentenyl, 4-methyl-4-pentenyL l,l-dimethyl-2-butenyl, l,l-dimethyl-3-butenyl, 1,2- dimethyl- 1 -butenyl, 1 ,2-dimethyl-2-butenyl, 1 ,2-dimethyl-3-butenyl, 1 ,3-dimethyl- 1 -butenyl,

[0057] 1.3-dimethyl-2-butenyl, l,3-dimethyl-3-butenyl, 2, 2-dimethy 1-3 -butenyl, 2,3 -dimethyl- 1- butenyl, 2,3-dimethyl-2-butenyl. 2,3-dimethyl-3-butenyl, 3.3-dimethyl- 1-butenyl, 3,3- dimethyl-2-butenyl, 1 -ethyl- 1-butenyl, l-ethyl-2-butenyl. l-ethyl-3-butenyl, 2-ethyl-l- butenyl, 2-ethyl-2 -butenyl, 2-ethyl-3-butenyl, l,l,2-trimethyl-2-propenyl, 1 -ethyl- 1-methyl-

[0058] 2-propenyl, 1 -ethyl-2-methyl- 1-propenyl, and l-ethyl-2-methyl-2-propenyl. The term “vinyl” refers to a group having the structure -CH=CH2; 1 -propenyl refers to a group with the structure-CH=CH-CHs; and 2- propenyl refers to a group with the structure -CH2-CEUCH2. Asymmetric structures such as (Z1Z2)C=C(Z3Z4) are intended to include both the E and Z isomers. This can be presumed in structural formulae herein wherein an asymmetric alkene is present, or it can be explicitly indicated by the bond symbol C=C. Alkenyl substituents may be unsubstituted or substituted with one or more chemical moieties. Examples of suitable substituents include, for example, alky l, halogenated alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, acyl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, thiosulfonate (e.g., -SSChRa). or thiol, as described below, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied.

[0059] As used herein, the term “alkynyl” represents straight-chained or branched hydrocarbon moieties containing a triple bond. Unless otherwise specified. C2-C24 (e.g., C2- C22, C2-C20, C2-C18, C2-C16, C2-C14, C2-C12, C2-C10, C2-C8, C2-C6, C2-C4) alkynyl groups are intended. Alkynyl groups may contain more than one unsaturated bond. Examples include C2-Ce-alkynyl, such as ethynyl, 1-propynyl, 2-propynyl (or propargyl), 1-butynyl, 2-butynyl, 3-butynyl, l-methyl-2-propynyl. 1 -pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl. 3-methyl-l- butynyl, l-methyl-2-butynyl, l-methyl-3-butynyl, 2-methyl-3-butynyl, Ll-dimethyl-2- propynyl, 1 -ethyl-2-propynyl, 1 -hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 3- methyl-1 -pentynyl, 4-methyl-l -pentynyl, 1 -methyl-2-pentynyl, 4-methyl-2-pentynyl, 1- methyl-3-pentynyl, 2-methyl-3-pentynyl, 1 -methyl-4-pentynyl, 2-methyl-4-pentynyl, 3- methyl-4-pentynyl, l,l-dimethyl-2-butynyl. l,l-dimethyl-3-butynyl, 1.2-dimethyl-3-butynyl, 2,2-dimethyl-3-butynyl, 3, 3-dimethyl- 1 -butynyl, l -ethyl-2-butynyl, l-ethyl-3-butynyl, 2- ethyl-3-butynyl, and l-ethyl-l-methyl-2-propynyl. Alkynyl substituents may be unsubstituted or substituted with one or more chemical moieties. Examples of suitable substituents include, for example, alkyl, halogenated alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, acyl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, thiosulfonate (e.g., -SSChRa), or thiol, as described below.

[0060] As used herein, the term “aryl,” as well as derivative terms such as aryloxy, refers to groups that include a monovalent aromatic carbocyclic group of from 3 to 20 carbon atoms. Aryl groups can include a single ring or multiple condensed rings. In some embodiments, aryl groups include Ce-Cio aryl groups. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, naphthyl, tetrahydronaphthyl, phenylcyclopropyl, and indanyl. In some embodiments, the ary l group can be a phenyl, indanyl or naphthyl group. The term “heteroaryl” is defined as a group that contains an aromatic group that has at least one heteroatom incorporated within the ring of the aromatic group. Examples of heteroatoms include, but are not limited to, nitrogen, oxygen, sulfur, and phosphorus. The term “non- heteroaryl,” which is included in the term '‘and,’’ defines a group that contains an aromatic group that does not contain a heteroatom. The aryl or heteroaryl substituents may be unsubstituted or substituted with one or more chemical moieties. Examples of suitable substituents include, for example, alkyl, halogenated alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, acyl, aldehyde, amino, carboxylic acid, cycloalkyl, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, or thiol as described herein. The term "bi an 1” is a specific type of and group and is included in the definition of aryl. Biaryl refers to two aryl groups that are bound together via a fused ring structure, as in naphthalene, or are attached via one or more carbon-carbon bonds, as in biphenyl.

[0061] The term '‘cycloalkyl” as used herein is a non-aromatic carbon-based ring composed of at least three carbon atoms. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyd, cyclohexyl, etc. The term “heterocycloalkyl” is a cycloalkyl group as defined above where at least one of the carbon atoms of the ring is substituted with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkyl group and heterocycloalkyl group can be substituted or unsubstituted. The cycloalky l group and heterocycloalkyl group can be substituted with one or more groups including, but not limited to, alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, acyl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, or thiol as described herein.

[0062] The term “cycloalkenyl” as used herein is a non-aromatic carbon-based ring composed of at least three carbon atoms and containing at least one double bound, i.e., C=C. Examples of cycloalkenyl groups include, but are not limited to, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, cyclohexadienyl, and the like. The term “heterocycloalkenyl” is a type of cycloalkenyl group as defined above, and is included within the meaning of the term “cycloalkenyl,” where at least one of the carbon atoms of the ring is substituted with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkenyl group and heterocycloalkenyl group can be substituted or unsubstituted. The cycloalkenyl group and heterocycloalkenyl group can be substituted with one or more groups including, but not limited to, alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, acyl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, or thiol as described herein. The term “cyclic group” is used herein to refer to either aryl groups, non-aryl groups (z.e., cycloalkyl, heterocycloalkyl, cycloalkenyl, and heterocycloalkenyl groups), or both. Cyclic groups have one or more ring systems that can be substituted or unsubstituted. A cyclic group can contain one or more aryl groups, one or more non-aryl groups, or one or more aryl groups and one or more non-aryl groups.

[0063] As used herein, “heteroaryl” refers to a monocyclic or polycyclic aromatic heterocycle having at least one heteroatom ring member selected from sulfur, oxygen, and nitrogen. In some embodiments, the heteroaryl ring has 1, 2, 3, or 4 heteroatom ring members independently selected from nitrogen, sulfur and oxygen. In some embodiments, any ringforming N in a heteroaryl moiety can be an N-oxide. In some embodiments, the heteroaryl has 5-10 ring atoms and 1. 2, 3 or 4 heteroatom ring members independently selected from nitrogen, sulfur and oxygen. In some embodiments, the heteroaryl has 5-6 ring atoms and 1 or 2 heteroatom ring members independently selected from nitrogen, sulfur and oxygen. In some embodiments, the heteroar l is a five-membered or six-membered heteroaryl ring. A fivemembered heteroaryl ring is a heteroaryl with a ring having five ring atoms wherein one or more (e.g., 1, 2, or 3) ring atoms are independently selected from N, O, and S. Exemplary five-membered ring heteroaryls are thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3- oxadiazolyl, 1,2,4-triazolyl, 1,2,4-thiadiazolyl, 1,2,4-oxadiazolyl, 1,3,4-triazolyl, 1,3,4- thiadiazolyl, and 1.3.4-oxadiazolyl. A six-membered heteroaryl ring is a heteroaryl with a ring having six ring atoms wherein one or more (e.g., 1 , 2, or 3) ring atoms are independently selected from N, O, and S. Exemplary7six-membered ring heteroaryls are pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl.

[0064] As used herein, “heterocycloalky7!” refers to non-aromatic monocyclic or polycyclic heterocycles having one or more ring-forming heteroatoms selected from O, N, or S. Included in heterocycloalkyl are monocyclic 4-, 5-, 6-, and 7-membered heterocycloalkyl groups. Heterocycloalkyl groups can also include spirocycles. Example heterocycloalkyl groups include pyrrolidin-2-one, l,3-isoxazolidin-2-one, pyranyl, tetrahydropuran. oxetanyl, azetidinyl, morpholino, thiomorpholino, piperazinyl, tetrahydrofuranyl. tetrahydrothienyl, piperidinyl, pyrrolidinyl, isoxazolidinyl, isothiazolidinyl, pyrazolidinyl, oxazolidinyl, thiazolidinyl, imidazolidinyl, azepanyl, benzazapene, and the like. Ring-forming carbon atoms and heteroatoms of a heterocycloalkyl group can be optionally substituted by oxo or sulfido (e.g., C(O). S(O), C(S), or S(O)2, etc.). The heterocycloalkyl group can be attached through a ring-forming carbon atom or a ring-forming heteroatom. In some embodiments, the heterocycloalkyl group contains 0 to 3 double bonds. In some embodiments, the heterocycloalkyl group contains 0 to 2 double bonds. Also included in the definition of heterocycloalkyl are moieties that have one or more aromatic rings fused (i.e., having a bond in common with) to the cy cloalkyl ring, for example, benzo or thieny l derivatives of piperidine, morpholine, azepine, etc. A heterocycloalkyl group containing a fused aromatic ring can be attached through any ring-forming atom including a ring-forming atom of the fused aromatic ring. In some embodiments, the heterocycloalkyl has 4-10, 4-7 or 4-6 ring atoms with 1 or 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur and having one or more oxidized ring members.

[0065] At certain places, the definitions or embodiments refer to specific rings (e.g., an azetidine ring, a pyridine ring, etc.). Unless otherwise indicated, these rings can be attached to any ring member provided that the valency of the atom is not exceeded. For example, an azetidine ring may be attached at any position of the ring, whereas a py ri din-3 -yl ring is attached at the 3 -position.

[0066] The term “acyl” as used herein is represented by the formula -CIO) / 1where Z1can be a hydrogen, hydroxyl, alkoxy, alkyd, halogenated alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalky l, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl group described above. As used herein, the term “acyl” can be used interchangeably with “carbonyl.” Throughout this specification “C(O)” or “CO” is a short hand notation for C=O.

[0067] As used herein, the term “alkoxy” refers to a group of the formula Z'-O-. where Z1is unsubstituted or substituted alkyl as defined above. Unless otherwise specified, alkoxy groups wherein Z1is a C1-C24 (e.g., C1-C22, C1-C20, Ci-Cis, C1-C16, C1-C14, C1-C12. C1-C10, Ci-Cs, Ci-Ce, C1-C4) alkyl group are intended. Examples include methoxy, ethoxy, propoxy. 1 -methyl-ethoxy, butoxy, 1 -methyl-propoxy, 2-methyl-propoxy, 1,1 -dimethyl-ethoxy, pentoxy, 1-methyl-butyloxy, 2-methyl-butoxy, 3-methyl-butoxy, 2,2-di-methyl-propoxy, 1- ethyl-propoxy, hexoxy, 1,1-dimethyl-propoxy, 1,2-dimethyl-propoxy, 1-methyl-pentoxy, 2- methyl-pentoxy, 3-methyl-pentoxy, 4-methyl-penoxy, 1,1-dimethyl-butoxy, 1,2-dimethyl- butoxy. 1,3-dimethyl-butoxy, 2,2-dimethyl-butoxy, 2.3-dimethyl-butoxy. 3,3-dimethyl- butoxy, 1-ethyl-butoxy, 2-ethylbutoxy, 1,1,2-trimethyl-propoxy, 1,2,2-trimethyl-propoxy, 1- ethyl-1 -methyl-propoxy, and l-ethyl-2-methyl-propoxy.

[0068] The term “aldehyde” as used herein is represented by the formula — C(O)H. The terms “amine’' or “amino’' as used herein are represented by the formula — NZ'Z2. where Z1and Z2can each be substitution group as described herein, such as hydrogen, an alkyl, halogenated alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl group described above. “Amido” is — C(O)NZ1Z2.

[0069] The term “carboxylic acid” as used herein is represented by the formula — C(O)OH. A “carboxylate” or “carboxyl” group as used herein is represented by the formula — C(O)O’.

[0070] The term “ester” as used herein is represented by the formula — OC(O)Z' or — C(O)OZ1, where Z1can be an alkyd, halogenated alky l, alkenyl, alkynyl, aryl, heteroaryl, cycloalky l, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl group described above.

[0071] The term “ether” as used herein is represented by the formula ZXOZ2. where Z1and Z2can be, independently, an alkyl, halogenated alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalky 1, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl group described above.

[0072] The term “ketone” as used herein is represented by the formula Z1C(O)Z2, where Z1and Z2can be, independently, an alkyl, halogenated alkyl, alkenyl, alkynyl. aryl, heteroaryl, cycloalky 1, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl group described above.

[0073] The term “halide” or “halogen” or “halo” as used herein refers to fluorine, chlorine, bromine, and iodine.

[0074] The term “hydroxyl” as used herein is represented by the formula — OH.

[0075] The term “nitro” as used herein is represented by the formula — NO2.

[0076] The term “silyl” as used herein is represented by the formula — SiZ^Z3, where Z1, Z2, and Z3can be, independently, hydrogen, alkyd, halogenated alkyl, alkoxy, alkeny 1, alky nyl, ary 1. heteroary l, cycloalky 1, cycloalkeny l, heterocycloalkyl, or heterocycloalkenyl group described above.

[0077] The term “sulfonyl” is used herein to refer to the sulfo-oxo group represented by the formula — S(O)2Z', where Z1can be hydrogen, an alkyl, halogenated alkyl, alkenyl, alky nyl, ary l, heteroaryl, cycloalkyl, cycloalkenyl, heterocycloalky 1, or heterocycloalkenyl group described above.

[0078] The term “sulfonyl amino” or “sulfonamide” as used herein is represented by the formula — S(O)2NH — .

[0079] The term “thiol” as used herein is represented by the formula — SH.

[0080] The term “thio” as used herein is represented by the formula — S — . As used herein. Me refers to a methyl group; OMe refers to a methoxy group; and z-Pr refers to an isopropyl group.

[0081] “R1,” -‘ 2 ” “3” “Rn’etc., where n is some integer, as used herein can, independently, possess one or more of the groups listed above. For example, if R1is a straight chain alkyl group, one of the hydrogen atoms of the alk l group can optionally be substituted with a hydroxyl group, an alkoxy group, an amine group, an alkyl group, a halide, and the like. Depending upon the groups that are selected, a first group can be incorporated within second group or, alternatively, the first group can be pendant (i.e., attached) to the second group. For example, with the phrase “an alkyl group comprising an amino group,” the amino group can be incorporated within the backbone of the alkyl group. Alternatively, the amino group can be attached to the backbone of the alkyl group. The nature of the group(s) that is (are) selected will determine if the first group is embedded or attached to the second group.

[0082] The term "substituted" refers to a molecule wherein at least one hydrogen atom is replaced with a substituent. When substituted, one or more of the groups are "substituents." The molecule can be multiply substituted. In the case of an oxo substituent ("=O"), two hydrogen atoms are replaced. Example substituents within this context can include halogen, hydroxy, alkyl, alkoxy, nitro, cyano, oxo, carbocyclyl, carbocycloalkyl, heterocarbocyclyl, heterocarbocycloalkyl, ary l, arylalkyl, heteroaryl, heteroarylalkyl, -NRaRb, -NRaC(=O)Rb, - NRaC(=O)NRaNRb. -NRaC(=O)ORb, - NRaSChRb, -C(=O)Ra, -C(=O)ORa, -C(=O)NRaRb, -OC(=O)NRaRb, -ORa, -SRa. -SORa. - S(=O)2Ra, -OS(=O)2Ra and -S(=O)2ORa. Ra and Rb in this context can be the same or different and independently hydrogen, halogen hydroxyl, alkyl, alkoxy, alkyd, amino, alkylamino, dialkylamino, carbocyclyl, carbocycloalky 1, heterocarbocyclyl, heterocarbocycloalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl.

[0083] Unless stated to the contrary, a formula with chemical bonds shown only as solid lines and not as wedges or dashed lines contemplates each possible stereoisomer or mixture of stereoisomer (e.g., each enantiomer, each diastereomer, each meso compound, a racemic mixture, or scalemic mixture).

[0084] Methods and Systems

[0085] Accordingly, provided herein are methods for capturing carbon dioxide gas from a gas stream. These methods can comprise contacting the gas stream w ith a capture solution comprising a surface-active gas capture agent to form a bicarbonate salt of the surface-active gas capture agent; and processing the capture solution to separate the bicarbonate from the capture solution and regenerate the surface-active gas capture agent.

[0086] In some embodiments, the surface-active gas capture agent comprises an amine moiety, and processing the capture solution to regenerate the surface-active gas capture agent comprises deprotonating the amine moiety.

[0087] In some embodiments, processing the capture solution comprises subjecting the capture solution to electrodialysis to separate the bicarbonate from the capture solution. In some embodiments, the electrodialysis comprises electrically driven separation of bicarbonate ions from protonated surface-active gas capture agent. In some embodiments, the electrodialysis is performed in an electrochemical cell comprising an anode, a cathode, and one or more compartments for fluid flow defined by ion exchange membranes. Depending upon the system utilized, these ion exchange membranes can comprise an anion exchange membrane, a cationic exchange membrane, and / or a bipolar membrane. Examples of such membranes are known in the art. Example architectures are described in the Examples below.

[0088] In some embodiments, electrodialysis is performed at a voltage of from about IV to about 10V (e.g., about 2V to about 10V, about 2V to about 8V, about 2V to about 6V, or about 2V to about 5V).

[0089] In some embodiments, electrodialysis is performed at a current density of from 0. 1 mA / cm2to 2 A / cm2In certain embodiments, electrodialysis is performed at a cunent density of from 0.5 mA / cm2to 20 mA / cm2. In certain embodiments, electrodialysis is performed at a current density7of from 0.1 A / cm2to 2 A / cm2.

[0090] In some embodiments, the electrodialysis comprises bipolar membrane electrodialysis (BPED). In some embodiments, the surface-active gas capture agent comprises an amine moiety, and BPED further comprises amine deprotonation by hydroxyl ions generated from water splitting to regenerate the surface-active gas capture agent.

[0091] In some embodiments, the surface-active gas capture agent comprises an amine moiety, and processing the capture solution further comprises subjecting a solution comprising a base to electrodialysis to provide hydroxyl ions to regenerate the surface-active gas capture agent.

[0092] In some embodiments, bicarbonate separation and regeneration of the surface-active gas capture agent occur in a single step. In some embodiments, the bicarbonate separation and the regeneration of the surface-active gas capture agent occurs in a single compartment. In other embodiments, bicarbonate separation and regeneration of the surface-active gas capture agent occur in two separate steps performed in two separate compartments.

[0093] In some embodiments, the method further comprises electrochemical conversion of the bicarbonate.

[0094] In some embodiments, processing the capture solution further comprises subjecting a solution comprising a potassium salt or a sodium salt to electrodialysis to provide potassium ions or sodium ions to produce a product stream comprising potassium bicarbonate or sodium bicarbonate.

[0095] In some embodiments, the surface-active gas capture agent comprises a blend of a gas capture agent and a surfactant. In other embodiments, the surface-active gas capture agent comprises a surfactant comprising an amine moiety.

[0096] In some embodiments, the surface-active gas capture agent is present in the capture solution in an amount of from 0.5% by weight up to an aqueous solubility limit of the surface-active gas capture agent, based on a total weight of the capture solution, such as from 0.5% to 40% by weight, from 5% to 40% by weight, from 10% to 40% by weight, from 15% to 40% by weight, from 20% to 40% by weight, or from 25% to 40% by weight, based on a total weight of the capture solution.

[0097] In some embodiments, the capture solution further comprises a surfactant.

[0098] In some embodiments, the capture solution comprises an aqueous solution.

[0099] In some embodiments, the gas stream comprises one or more gases chosen from air, a flue gas, a natural gas, a hydrogen gas, and a synthesis gas. In some embodiments, the gas stream can comprise carbon dioxide in combination with one or more additional gases (e.g., nitrogen, water vapor, carbon monoxide, oxygen, or a combination thereol). In some embodiments, the gas stream can comprise from 400 ppm to 5000 ppm carbon dioxide (e.g., from 400 ppm to 1000 ppm carbon dioxide). In other embodiments, the gas stream can comprise at least 1% by volume carbon dioxide (e.g., from 5% to 30% carbon dioxide, or from 10% to 25% carbon dioxide).

[0100] Ion Exchange Membranes

[0101] Suitable ion exchange membranes that can be used in the electrochemical cells described herein are known in the art. Suitable membranes may comprise any suitable polymer, typically an ion exchange resin, for example comprising a polymeric anion or cation exchange resin, or combination thereof. Suitable solid cationic exchange polymers include use of one or more of the following polymers: cross-linked halogenated alkylated compound with a polyamine, a cross-linked aromatic polysulfone t pe polymer with a polyamine, perfluorinated hydrocarbon sulfonate ionomers, sulfonated poly ether ether ketone (sPEEK), sulfonated poly(phthalazinone ether ketone), sulfonated phenolphthalein poly(ether sulfone), sulfonated polyimides, sulfonated polyphosphazene, sulfonated polybenzimidazole, aromatic polymers containing a sulfonic acid group, sulfonated perfluorinated polymer, fluorinated ionomers with sulfonate groups, carboxylate groups, phosphate groups, boronate acid groups, polyaromatic ethers with sulfonate or carboxylate groups, poly(4-vinyl pyridine, poly(2 -vinyl pyridine), poly(styrene-b-2-vinylpyridine), poly(vinyl pyrrolidine), poly(l-methyl-4-vinylpyridine), poly[(2,2'-m-phenylene)-5,5'- bibenzimidazole][poly(2,2'-(m-phenylene)-5,5'-bibenzimidazole], poly(2,5-benzimidazole), polyacrylate, polymethacrylate or combinations thereof. Suitable solid anionic exchange membranes include the use of one or more of the following polymers: polydiaryl dimethyl ammonium, poly(methacryloyloxyethyl triethylammonium), poly(diallylammonium), or combinations thereof. Additionally, substantially nonfluorinated membranes that are modified with sulfonic acid groups (or cation exchanged sulfonate groups) may also be used. Such membranes include those with substantially aromatic backbones, e.g., poly-styrene, polyphenylene, bi-phenyl sulfone (BPSH), or thermoplastics such as polyetherketones or poly ethersulfones.

[0102] A cation exchange membrane substantially permits the passage of cations and substantially blocks anions. Examples of commercially available cation exchange membranes include those available under the designators NEOSEPTA, CM-1 , CM-2, CMX, CMS, and CMB from Tokuyama Co., Ltd. Conversely, an anion exchange membrane substantially permits the passage of anions and substantially blocks cations. Examples of commercially available anion exchange membranes include those available under the designators NEOSEPTA, AM-1, AM-3, AMX, AHA, ACH, and ACS also from Tokuyama Co., Ltd. Further examples of ion exchange membranes are provided throughout the present disclosure.

[0103] The term “bipolar membrane” generally refers to a membrane that is selective to two different charges or polarities. Unless specified otherwise, a bipolar membrane may take the form of a unitary membrane structure a multiple membrane structure, or a laminate. The unitary membrane structure may have a first portion including cation ion exchange materials or groups and a second portion opposed to the first portion, including anion ion exchange materials or groups. The multiple membrane structure (e.g., two film) may be formed by a cation exchange membrane laminated, attached, or otherwise coupled to an anion exchange membrane. The cation and anion exchange membranes initially start as distinct structures, and may or may not retain their distinctiveness in the structure of the resulting bipolar membrane.

[0104] Capture Solutions

[0105] Example aspects of capture solutions for use in conjunction with the methods described herein are described in International Publication No. WO 2023 / 244541, which is incorporated herein by reference in its entirety.

[0106] In some embodiments, the surface-active gas capture agent can comprise a blend of a gas capture agent and a surfactant. By way of example, the surface-active gas capture agent can comprise a surfactant (e.g., a nonionic surfactant such as an alcohol alkoxylate) in combination with a gas capture agent (e.g., an amine gas capture agent such as MEA, MDEA, and / or AMP) to enhance the CO2 capacity and reaction rate of the capture solution.

[0107] In some embodiments, the surface-active gas capture agent can comprise a surfactant comprising an amine moiety (e.g., a tertiary amine moiety). The surface-active character of this active agent can improve the CO2 capacity and reaction rate of the capture solution as compared to conventional amine capture agents such as MEA. Optionally, one or more additional surfactants can be added to these capture solutions to further enhance the CO2 capacity and reaction rate of the capture solution. These surface-active gas capture agents can form a bicarbonate salt upon exposure to gaseous CO2.

[0108] The surface-active gas capture agent can be present in the capture solution in an amount of from 0.5% by weight up to an aqueous solubility limit of the surface-active gas capture agent, based on a total weight of the capture solution, such as from 0.5% to 40% by weight, from 5% to 40% by weight, from 10% to 40% by weight, from 15% to 40% by weight, from 20% to 40% by weight, or from 25% to 40% by weight, based on a total weight of the capture solution.

[0109] Gas Capture Agents

[0110] The gas capture agent can include, but is not limited to, an amine gas capture agent such as a monoamine, a diamine, or a polyamine. In some embodiments, the amine gas capture agent can include a monoamine. In some embodiments, the amine gas capture agent can include a diamine. In some embodiments, the amine gas capture agent can include a polyamine. In some embodiments, the amine gas capture agent can include a tertiary amine or a sterically hindered amine. In some embodiments, the amine gas capture agent can include a tertiary amine. In some embodiments, the amine gas capture agent can include a sterically hindered amine.

[0111] In some embodiments, the gas capture agent can include, but is not limited to, methylamine, ethylamine, propylamine, iso-propylamine, butylamine, iso-butylamine, secbutylamine, tert-butylamine, pentylamine, iso-pentylamine, sec-pentylamine, tertpentylamine, hexylamine, iso-hexylamine, sec-hexylamine, tert-hexylamine, ethylenediamine. (2-methylbutyl)amine. 2-aminopentane. 3-(tert-butoxy)propylamine. 2- amino-6-methylheptane, 1 -ethylpropylamine dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentyd amine, dihexy lamine, N-ethy Imethylamine, N-isopropylmethy lamine, N-butylmethylamine, N-ethy lisopropylamine, N-tert-butylmethylamine, N-ethylbutylamine, 3-isopropoxypropylamine. chloro(diethylamino)dimethylsilane, 2,2'- (ethylenedioxy)bis(ethylamine), 1, 3-bis(chloromethyl)-l,l, 3, 3-tetramethyl disilazane, N-tert- butylisopropylamine, N,N-diethyltrimethy Isilylamine, di-sec-butylamine, trimethylamine, triethy lamine, tripropylamine, tributy lamine, dimethylpropy lamine. diethylpropy lamine, N,N-diisopropylmethylamine, N-ethyldiisopropylamine, N.N-dimethylethy lamine. N,N- diethylbutylamine, 1,2-dimethylpropylamine, N,N-diethylmethylamine, N,N- dimethylisopropylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, N,N- dimethylbuty lamine, tetramethylethy lenediamine (TMEDA), tetraethylmethanediamine (TEMDA), tetramethylmethanediamine (TMMDA), tetramethyl-l,3-diaminopropane (TMPDA) or triethylamine (TEA), monoethanolamine (MEA). diethanolamine (DEA), N- methyl di ethanol amine (MDEA), 2-diethylaminoethanol (DEAE), 3-(diethylamino)-l,2- propanediol (DAPD) or 2-amino-2-methy 1 propan-1 -ol (AMP), piperazine (PZ), morpholine, piperidine, pyrrolidine, l,8-diazabicyclo[5.4.0]undec-7-ene (DBU). glycine, or a combination thereof.

[0112] In some embodiments, the gas capture agent can comprise a polyamine. Examples of suitable polyamines include, but are not limited to, polyethyleneimines or oligomeric forms thereof (e.g., diethy lenetriamine, triethylenetetramine, or tetraethy lenepentamine where the nitrogen atoms are tertiary by way of alkylation or alkoxylation) and polyvinylamines or oligomeric forms thereof (containing tertiary amines).

[0113] Surfactants Comprising an Amine Moiety

[0114] The surface-active gas capture agent can include a surfactant comprising an amine moiety. In some embodiments, the amine moiety' can include a tertiary amine moiety, or a sterically hindered amine moiety. In some embodiments, the surface-active gas capture agent can include a surfactant including a tertiary amine moiety. In some embodiments, the surfaceactive gas capture agent can include a surfactant including a sterically hindered amine moiety.

[0115] In some embodiments, the surface-active gas capture agent can include a compound defined by Formula II or Formula III

[0116] R2

[0117] N-(PO)y-(EO)z-Q

[0118] R2

[0119] Formula II

[0120] Formula III wherein, individually for each occurrence.

[0121] PO represents -CH2-CH(methyl)-O-;

[0122] EO represents -CH2-CH2-O-;

[0123] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an aryl group, an alkylaryl group, or oxyalkydene group POyEOz-Q;

[0124] Q is hydrogen; y is an integer from 0 to 60; and z is an integer from 0 to 40, with the proviso that at least one of y and z is greater than 0.

[0125] In some embodiments, the surface-active gas capture agent can include a compound defined by Formula II

[0126] R2

[0127] N-(PO)y-(EO)z-Q

[0128] R2

[0129] Formula II wherein, individually for each occurrence,

[0130] PO represents -CH2-CH(methyl)-O-;

[0131] EO represents -CH2-CH2-O-;

[0132] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an and group, an alkylaryl group, or oxyalkydene group POyEOz-Q; Q is hydrogen; y is an integer from 0 to 60; and z is an integer from 0 to 40, with the proviso that at least one of y and z is greater than 0.

[0133] In some embodiments, the surface-active gas capture agent can include a compound defined by Formula III

[0134] Formula III wherein, individually for each occurrence,

[0135] PO represents -CH2-CH(methyl)-O-;

[0136] EO represents -CH2-CH2-O-;

[0137] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an aryl group, an alkylaryl group, or oxyalkylene group POyEOz-Q;

[0138] Q is hydrogen; y is an integer from 0 to 60; and z is an integer from 0 to 40, with the proviso that at least one of y and z is greater than 0.

[0139] In some embodiments, R2can be hydrogen. In some embodiments, R2can be a Ci-Cs alkyl group. In some embodiments, R2can be a C2-C8 alkenyl group. In some embodiments, R2can be a C2-C8 alky nyl group. In some embodiments, R2can be an aryl group. In some embodiments, R2can be an alkylaryl group. In some embodiments. R2can be a methyl group.

[0140] In some embodiments, L can be a Ci-Cs alkyl, a C2-C8 alkenyl, a C2-C8 alkynyl. In some embodiments, L can be a Ci-Cs alkyl. In some embodiment, L can be a C3 alkyd.

[0141] In some embodiments, y can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29. 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40.

[0142] In some embodiments, y can be at least 0. 1 (e.g., at least 1, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, y can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 5 or less, or 1 or less).

[0143] The y can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, y can be an integer from 0 to 40 (e.g., from 0 to 35. from 0 to 30, from 0 to 25, from 0 to 20, from 0 to 15, from 0 to 10. from 0 to 5, from 1 to 40, from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15, from 5 to 10, from 10 to 40, from 10 to 35, from 10 to 30, from 10 to 25, from 10 to 20, from 10 to 15, from 15 to 40, from 15 to 35, from 15 to 30, from 15 to 25, from 15 to 20, from 20 to 40. from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30. from 30 to 40, from 30 to 35, from 30 to 40. or from 35 to 40).

[0144] In some embodiments, z can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40.

[0145] In some embodiments, z can be at least 0. 1 (e.g., at least 1, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, z can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 5 or less, or 1 or less).

[0146] The z can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, z can be an integer from 0 to 40 (e.g., from 0 to 35, from 0 to 30, from 0 to 25, from 0 to 20, from 0 to 15, from 0 to 10, from 0 to 5, from 1 to 40, from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25. from 5 to 20. from 5 to 15. from 5 to 10. from 10 to 40, from 10 to 35, from 10 to 30, from 10 to 25, from 10 to 20, from 10 to 15, from 15 to 40, from 15 to 35, from 15 to 30, from 15 to 25, from 15 to 20, from 20 to 40, from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30, from 30 to 40, from 30 to 35, from 30 to 40, or from 35 to 40).

[0147] In some embodiments, z is 0. In some embodiments, y is from 3 to 5. In some embodiments, y is from 8 to 12. In some embodiments, y is 4. In some embodiments, y is 10. In some embodiments, y is 4 and z is 0. In some embodiments, y is 10 and z is 0.

[0148] In some embodiments, the surface-active gas capture agent can include a compound defined by Formula II or Formula Ill

[0149] R2

[0150] N-(PO)y-(EO)z-Q

[0151] R2

[0152] Formula II

[0153] Formula III wherein, individually for each occurrence.

[0154] PO represents -CH2-CH(methyl)-O-;

[0155] EO represents -CH2-CH2-O-;

[0156] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an ary l group, an alkylaryl group, or oxy alkylene group POyEOz-Q;

[0157] Q is hydrogen; y is an integer from 1 to 60; and z is an integer from 0 to 40.

[0158] In some embodiments, the surface-active gas capture agent can include a compound defined by Formula II

[0159] R2

[0160] N-(PO)y-(EO)z-Q

[0161] R2

[0162] Formula II wherein, individually for each occurrence.

[0163] PO represents -CH2-CH(methyl)-O-;

[0164] EO represents -CH2-CH2-O-;

[0165] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an ary l group, an alkylaryl group, or oxyalkylene group POyEOz-Q;

[0166] Q is hydrogen; y is an integer from 1 to 60; and z is an integer from 0 to 40.

[0167] In some embodiments, the surface active gas capture agent can include a compound defined by Formula III

[0168] Formula III wherein, individually for each occurrence. PO represents -CH2-CH(methyl)-O-;

[0169] EO represents -CH2-CH2-O-;

[0170] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an aryl group, an alkylaryl group, or oxyalkylene group POyEOz-Q;

[0171] Q is hydrogen; y is an integer from 1 to 60; and z is an integer from 0 to 40.

[0172] In some embodiments, R2can be hydrogen. In some embodiments, R2can be a Ci-Cs alkyl group. In some embodiments, R2can be a C2-C8 alkenyl group. In some embodiments, R2can be a C2-C8 alkynyl group. In some embodiments, R2can be an aryl group. In some embodiments, R2can be an alkylaryl group. In some embodiments. R2can be a methyl group.

[0173] In some embodiments, L can be a Ci-Cs alkyl, a C2-C8 alkenyl, a C2-C8 alkynyl. In some embodiments, L can be a Ci-Cs alkyl. In some embodiment, L can be a C3 alkyd.

[0174] In some embodiments, y can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. 31. 32. 33, 34, 35, 36, 37, 38, 39, or 40.

[0175] In some embodiments, y can be at least 1 (e.g., at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, y can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less).

[0176] The y can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, y can be an integer from 1 to 40 (e.g., from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15, from 5 to 10, from 10 to 40, from 10 to 35, from 10 to 30. from 10 to 25, from 10 to 20, from 10 to 15, from 15 to 40. from 15 to 35, from 15 to 30, from 15 to 25, from 15 to 20, from 20 to 40, from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30, from 30 to 40, from 30 to 35, from 30 to 40, or from 35 to 40).

[0177] In some embodiments, z can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,

[0178] 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. 31. 32, 33, 34, 35, 36, 37, 38, 39, or 40.

[0179] In some embodiments, z can be at least 0.1 (e.g., at least 1, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, z can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 5 or less, or 1 or less). The z can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, z can be an integer from 0 to 40 (e.g., from 0 to 35, from 0 to 30, from 0 to 25, from 0 to 20, from 0 to 15, from 0 to 10, from 0 to 5, from 1 to 40, from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15. from 5 to 10. from 10 to 40, from 10 to 35, from 10 to 30, from 10 to 25, from 10 to 20, from 10 to 15. from 15 to 40, from 15 to 35, from 15 to 30. from 15 to 25, from 15 to 20, from 20 to 40, from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30, from 30 to 40, from 30 to 35, from 30 to 40, or from 35 to 40).

[0180] In some embodiments, z is 0. In some embodiments, y is from 3-15. In some embodiments, y is from 15-35. In some embodiments, y is 4. In some embodiments, y is 6. In some embodiments, y is 8. In some embodiments, y is 10. In some embodiments, y is 12. In some embodiments, y is 30. In some embodiments, y is 4 and z is 0. In some embodiments, y is 6 and z is 0. In some embodiments, y is 8 and z is 0. In some embodiments, y is 10 and z is 0. In some embodiments, y is 12 and z is 0. In some embodiments, y is 30 and z is 0.

[0181] In some embodiments, the surface-active gas capture agent can be defined by the structure below: wherein individually for each occurrence,

[0182] PO represents -CH2-CH(methyl)-O-;

[0183] R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an ar l group, an alkylaryl group, or oxyalkylene group POyEOz-Q; y is an integer from 1 to 60.

[0184] In some embodiments, the surface-active gas capture agent can be selected from:

[0185] Surfactants

[0186] The surfactant can include, but is not limited to, a non-ionic surfactant. The non-ionic surfactant can include a hydrophobic tail comprising from 8 to 32 carbon atoms. In some embodiments, the non-ionic surfactant can include a hydrophobic tail that includes at least 8 carbon atoms (e.g., at least 9 carbon atoms, at least 10 carbon atoms, at least 11 carbon atoms, at least 12 carbon atoms, at least 13 carbon atoms, at least 14 carbon atoms, at least 15 carbon atoms, at least 16 carbon atoms, at least 17 carbon atoms, at least 18 carbon atoms, at least 19 carbon atoms, at least 20 carbon atoms, at least 21 carbon atoms, at least 22 carbon atoms, at least 23 carbon atoms, at least 24 carbon atoms, at least 25 carbon atoms, at least 26 carbon atoms, at least 27 carbon atoms, at least 28 carbon atoms, at least 29 carbon atoms, at least 30 carbon atoms, or at least 31 carbon atoms). In some embodiments, the non-ionic surfactant can include a hydrophobic tail that comprises 32 carbon atoms or less (e.g., 31 carbon atoms or less, 30 carbon atoms or less, 29 carbon atoms or less, 28 carbon atoms or less, 27 carbon atoms or less, 26 carbon atoms or less, 25 carbon atoms or less, 24 carbon atoms or less, 23 carbon atoms or less. 22 carbon atoms or less, 21 carbon atoms or less, 20 carbon atoms or less, 19 carbon atoms or less. 18 carbon atoms or less, 17 carbon atoms or less, 16 carbon atoms or less, 15 carbon atoms or less, 14 carbon atoms or less, 13 carbon atoms or less, 12 carbon atoms or less, 11 carbon atoms or less, 10 carbon atoms or less, or 9 carbon atoms or less).

[0187] The non-ionic surfactant can include a hydrophobic tail that comprises a number of carbon atoms ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the non-ionic surfactant can include a hydrophobic tail comprising from 8 to 32 carbon atoms (e.g., from 10 to 32, from 15 to 32, from 20 to 32, from 25 to 32, from 8 to 30, from 10 to 30. from 15 to 30, from 20 to 30, from 25 to 30, from 8 to 25, from 10 to 25. from 15 to 25. from 20 to 25, from 8 to 20, from 10 to 20, from 15 to 20, from 8 to 15, from 10 to 15, or from 8 to 10). In some cases, the hydrophobic tail may be a straight chain, branched chain, and / or may comprise cyclic structures. The hydrophobic carbon tail may include single bonds, double bonds, triple bonds, or any combination thereof. In some cases, the hydrophobic tail can comprise an alky l group, with or without an aromatic ring (e.g., a phenyl ring) attached to it. In some embodiments, the hydrophobic tail can comprise a branched hydrophobic tail derived from Guerbet alcohols.

[0188] Example non-ionic surfactants include alkyl aryl alkoxy alcohols, alkyl alkoxy alcohols, or any combination thereof. In embodiments, the non-ionic surfactant may be a mix of surfactants with different length lipophilic tail chain lengths. For example, the non-ionic surfactant may be C8-C11 :9PO, which indicates a mixture of non-ionic surfactants that have a lipophilic tail length of 8 carbon to 11 carbon, which is followed by a chain of 9 POs. The hydrophilic moiety is an alkyleneoxy chain (e g., an ethoxy (EO). butoxy (BO) and / or propoxy (PO) chain with two or more repeating units of EO, BO. and / or PO). In some embodiments, 0-40 repeating units of EO are present. In some embodiments, 0-40 repeating units of PO are present. In some embodiments, 0-10 repeating units of BO are present. For example, the non-ionic surfactant could comprise 7PO:8EO or 10PO. In some embodiments, the non-ionic surfactant may be a mix of surfactants with different length lipophilic tail chain lengths. For example, the non-ionic surfactant may be C8-C11:7PO:8EO, which indicates a mixture of non-ionic surfactants that have a lipophilic tail length of 9 carbon to 11 carbon, which is followed by a chain of 7 Pos and 8 Eos. In some embodiments, the non-ionic surfactant is a Guerbet PO(0-40) and EO(0-40) (Guerbet can be C8-C32); or alkyl PO(0-40) and EO(0-40): where the alkyl group is linear or branched C8-C32. In some embodiments, the non-ionic surfactant is a Guerbet P0(0-40) and EO(1 -40) (Guerbet can be C8-C32); or alkyl PO(0-40) and EO(1-40): where the alkyl group is linear or branched C8-C32. In some embodiments, the non-ionic surfactant is a Guerbet PO(1-40) and EO(0-40) (Guerbet can be C8-C32): or alkyl PO(1-40) and EO(0-40): where the alkyl group is linear or branched C8- C32. In some embodiments, the non-ionic surfactant is a Guerbet PO(1-40) and EO(1-40) (Guerbet can be C8-C32); or alkyl PO(1-40) and EO(1-40): where the alkyd group is linear or branched C8-C32. In some embodiments, the non-ionic surfactant is a Guerbet PO(6-8) and EO(7-9) (Guerbet can be C8-C12); or alkyl PO(6-8) and EO(7-9): where the alkyd group is linear or branched C8-C12. In some examples, the non-ionic surfactant can comprise a branched or unbranched C8-C32:PO(0-40):EO(0-40) (e.g., a branched or unbranched C8- C32:PO(1-40):EO(0-40), a branched or unbranched C8-C32:PO(0-40):EO(1-40), a branched or unbranched C8-C32:PO(1-40):EO(1-40), a branched or unbranched C8-C32:PO(6- 8):EO(7-9), a branched or unbranched C8-C32:PO(6-8):EO(7-9). a branched or unbranched C8-C12:PO(30-40):EO(25-35), a branched or unbranched C8-C12:PO(30-40):EO(25-35), a branched or unbranched C8-30:EO(8-30), or any combination thereof).

[0189] In some embodiments, the surfactant can include an alcohol alkoxylate. In some embodiments, the alcohol alkoxylate can include at least one propoxy segment.

[0190] In some embodiments, the surfactant can be defined by Formula I

[0191] R1— O-(BO)x-(PO)y-(EO)z-Q

[0192] Formula I wherein

[0193] BO represents -CH2-CH(ethyl)-O- and / or -CH2CH(-)CH(O-)CH2-;

[0194] PO represents -CH2-CH(methyl)-O-;

[0195] EO represents -CH2-CH2-O-;

[0196] R1represents a C8-C32 alkyl group, a C8-C32 alkenyl group, a C8-C32 alkynyl group, an aryl group, or an alkyl aryl group;

[0197] Q is hydrogen; x is an integer from 0 to 10; y is an integer from 0 to 40; and z is an integer from 0 to 40, with the proviso that at least one of x, y, and z is greater than 0.

[0198] In some embodiments, R1can be a C8-C32 alkyd group. In some embodiments, R1can be a C8-C32 alkenyl group. In some embodiments, R1can be a C8-C32 alkynyl group. In some embodiments, R1can be an ar l group. In some embodiments, R1can be an alkylaryl group. In some embodiments, R1can be a Cs alky 1 group.

[0199] In some embodiments, x can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0200] In some embodiments, x can be at least 0. 1 (e.g., at least 0.5, at least 1, at least 2.5, at least 5. or at least 7.5). In some embodiments, x can be 10 or less (e.g., 7.5 or less, 5 or less, 2.5 or less, 1 or less, or 0.5 or less).

[0201] The x can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, x can be an integer from 0 to 10 (e.g.. from 0 to 7.5, from 0 to 5, from 0 to 2.5, from 1 to 10, from 1 to 7.5, from 1 to 5, from 1 to 2.5, from 5 to 10, from 5 to 7.5, or from 7.5 to 10).

[0202] In some embodiments, y can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40. In some embodiments, y can be at least 0. 1 (e.g., at least 1, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, y can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 5 or less, or 1 or less).

[0203] The y can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, y can be an integer from 0 to 40 (e.g.. from 0 to 35. from 0 to 30, from 0 to 25, from 0 to 20, from 0 to 15, from 0 to 10, from 0 to 5, from 1 to 40, from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15, from 5 to 10. from 10 to 40, from 10 to 35, from 10 to 30, from 10 to 25, from 10 to 20, from 10 to 15. from 15 to 40, from 15 to 35, from 15 to 30, from 15 to 25, from 15 to 20, from 20 to 40, from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30, from 30 to 40, from 30 to 35, from 30 to 40, or from 35 to 40).

[0204] In some embodiments, z can be 0, 1. 2, 3, 4, 5. 6, 7, 8. 9, 10, 11, 12. 13. 14. 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40.

[0205] In some embodiments, z can be at least 0.1 (e.g., at least 1, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, z can be 40 or less (e.g., 35 or less. 30 or less, 25 or less, 20 or less, 15 or less, 10 or less. 5 or less, or 1 or less).

[0206] The z can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, z can be an integer from 0 to 40 (e.g., from 0 to 35, from 0 to 30, from 0 to 25, from 0 to 20, from 0 to 15, from 0 to 10, from 0 to 5, from 1 to 40, from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15, from 5 to 10, from 10 to 40, from 10 to 35, from 10 to 30, from 10 to 25, from 10 to 20, from 10 to 15, from 15 to 40, from 15 to 35, from 15 to 30. from 15 to 25, from 15 to 20, from 20 to 40. from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30. from 30 to 40, from 30 to 35, from 30 to 40. or from 35 to 40).

[0207] In some embodiments, at least x is greater than 0. In some embodiments, at least y is greater than 0. In some embodiments, at least z is greater than 0. In some embodiments, x is 0. In some embodiments, y is from 5 to 10. In some embodiments, z is from 5 to 10. In some embodiments, y is from 6 to 8. In some embodiments, z is from 7 to 9. In some embodiments, x is 0, y is from 5 to 10, and z is from 5 to 10. In some embodiments, x is 0, y is from 6 to 8. and z is from 7 to 9. In some embodiments, x is 0, y is 7 and z is 8.

[0208] In some embodiments, the surfactant can be defined by Formula I A

[0209] R1— O— (PO)y-(EO)z— Q

[0210] Formula I A wherein

[0211] BO represents -CH2-CH(ethyl)-O- and / or -CH2CH(-)CH(O-)CH2-;

[0212] PO represents -CH2-CH(methyl)-O-;

[0213] EO represents -CH2-CH2-O-;

[0214] R1represents a C8-C32 alkyl group, a C8-C32 alkenyl group, a C8-C32 alkynyl group, an aryl group, or an alkylaryl group;

[0215] Q is hydrogen; y is an integer from 1 to 40; and z is an integer from 1 to 40.

[0216] In some embodiments, R1can be a C8-C32 alkyd group. In some embodiments, R1can be a C8-C32 alkenyl group. In some embodiments, R1can be a C8-C32 alkynyl group. In some embodiments, R1can be an ar l group. In some embodiments, R1can be an alkylaryl group. In some embodiments, R1can be a Cs alkyl group.

[0217] In some embodiments, the surfactant of Formula I can be defined by the structure below: wherein

[0218] PO represents -CH2-CH(methyl)-O-;

[0219] EO represents -CH2-CH2-O-; y is an integer from 1 to 40; and z is an integer from 1 to 40.

[0220] In some embodiments, y can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40. In some embodiments, y can be at least 1 (e.g., at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, y can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less).

[0221] The y can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, y can be an integer from 1 to 40 (e.g.. from 1 to 35. from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15. from 1 to 10. from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15, from 5 to 10, from 10 to 40, from 10 to 35, from 10 to 30, from 10 to 25, from 10 to 20, from 10 to 15, from 15 to 40, from 15 to 35, from 15 to 30, from 15 to 25, from 15 to 20, from 20 to 40, from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30, from 30 to 40. from 30 to 35, from 30 to 40, or from 35 to 40).

[0222] In some embodiments, z can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40.

[0223] In some embodiments, z can be at least 1 (e.g., at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35). In some embodiments, z can be 40 or less (e.g., 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less).

[0224] The z can be an integer ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, z can be an integer from 1 to 40 (e.g., from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 20, from 1 to 15. from 1 to 10. from 1 to 5, from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20, from 5 to 15, from 5 to 10, from 10 to 40, from 10 to 35, from 10 to 30, from 1 to 25, from 10 to 20, from 10 to 15, from 15 to 40, from 15 to 35, from 15 to 30, from 15 to 25, from 15 to 20, from 20 to 40, from 20 to 35, from 20 to 30, from 20 to 25, from 25 to 40, from 25 to 35, from 25 to 30, from 30 to 40. from 30 to 35, from 30 to 40, or from 35 to 40).

[0225] In some embodiments, y is from 5 to 10. In some embodiments, z is from 5 to 10. In some embodiments, y is from 6 to 8. In some embodiments, z is from 7 to 9. In some embodiments, y is from 5 to 10, and z is from 5 to 10. In some embodiments, y is from 6 to 8, and z is from 7 to 9. In some embodiments, y is 7 and z is 8.

[0226] In some embodiments, the surfactant exhibits an HLB value of at least 6 (e.g., at least 5, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, or at least 14).

[0227] In some embodiments, the surfactant exhibits an HLB value of 15 or less (e.g., 15 or less, 14 or less. 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, or 7 or less). In some embodiments, the surfactant exhibits an HLB value of from 6 to 15 (e.g., from 6 to 8, from 6 to 10, from 6 to 12, from 6 to 14 from 8 to 10, from 8 to 12, from 8 to 15, from 10 to 12, from 10 to 15, or from 12 to 15).

[0228] In some embodiments, the surfactant can be present in the capture solution in an amount of at least 0.5% by weight, based on the total weight of the capture solution (e.g., at least 1%, at least 2%, at least 3%, or at least 4%).

[0229] In some embodiments, the surfactant can be present in the capture solution in an amount of 5% by weight or less (e.g., 4% or less, 3% or less, 2% or less, or 1% or less).

[0230] The surfactant can be present in the capture solution in an amount ranging from any of the minimum values described above to any of the maximum values described above. For examples, in some embodiments, the surfactant can be present in the capture solution in an amount of from 0.5% to 5% by weight, based on the total weight of the capture solution (e.g., from 0.5% to 4% by weight, from 0.5% to 3% by weight, from 0.5% to 2% by weight, from 0.5% to 1% by weight, from 1% to 5% by weight, from 1% to 4% by weight, from 1 % to 3% by weight, from 1% to 2% by weight, from 2% to 5% by weight, from 2% to 4% by weight, from 2 % to 3% by weight, from 3% to 5% by weight, from 3% to 4% by weight, or from 4 % to 5% by weight).

[0231] By way of non-limiting illustration, examples of certain embodiments of the present disclosure are given below.

[0232] EXAMPLES

[0233] Example 1: CO2 Capture as Bicarbonate as an Efficient Pathway in Carbon Management

[0234] Summary

[0235] Carbon capture, utilization, and storage (CCUS) has been considered crucial toward carbon neutrality in response to environmental concerns associated with excessive emissions of carbon dioxide (CO2). As part of CCUS, amine-based post-combustion capture (PCC) has been commercially used, but it is energy -intensive to strip the CO2 captured by conventional amine solutions as carbamates while regenerating the amine solvent by heating it to a high temperature (e.g., 120 - 180°C). The regeneration step accounts for a large fraction of the total operating cost. Also, the traditional method of CO2 “catch-and-release” is unnecessary when the downstream processes in carbon management do not require CO2 as a carbon carrier. Many green chemicals can be generated from bicarbonate in aqueous media at lower costs and carbon intensity than from CO2.

[0236] Described herein are methods that involve CO2 capture as bicarbonate, aiming to improve the overall efficiency of carbon management by not using CO2 as a carbon carrier. Components of these methods can include (i) CO2 capture as bicarbonate using, for example, a surface-active tertiary amine; and / or (ii) the bicarbonate separation and amine regeneration in a single step using bipolar membrane electrodialysis. The overall objective of this research is to examine the energy efficiency of the bicarbonate pathway in comparison to the conventional CO2 stripping process that is enabled and thus burdened by the need for temperature swings. Successful outcomes of these efforts include proof-of-concept data that demonstrates energy efficient CO2 capture in carbon management.

[0237] Potential and Significance

[0238] The current global energy supplies mainly rely on fossil fuels, such as coal, oil, and natural gas. Their emitted pollutants have led to adverse effects on the environment. In particular, CO2 as a greenhouse gas is viewed as a long-term cause of climate change and in the U.S., 92.4% of the CO2 emissions came from the combustion of fossil fuels in 2019.

[0239] Reduction of CO2 emissions is possible in various ways, such as improving energy efficiency, shifting to low-carbon or non-carbon energy' sources, and implementing CCUS. CO2 capture and conversion into fuels and chemicals is considered a practical option to stabilize atmospheric CO2 concentrations in the midterm. Capturing CO2 from the industry’s emissions has been implemented at a cost of approximately USD 47 / tonne-CO2 and is regarded as a valuable carbon resource.

[0240] Amine-based post-combustion capture (PCC) is a well-proven and commercially used technology for CO2 capture with CO2 recovery rates of up to 800 tonnes / day. PCC typically uses a single or a blend of reactive aqueous amine solutions to react chemically with CO2 gas in an acid-base reaction. Then, the CO2 gas is subsequently stripped from the amine solution at high temperatures (e.g., 120-180°C), while regenerating the amine solvent. The regeneration step is considered the main drawback of this technology, and its regeneration cost can be as high as 70% of the total operating cost. The proposed project aims to improve the energy efficiency of CO2 capture as part of overall carbon management processes as described below.

[0241] A widely studied strategy for improving the energy efficiency in PCC is the development of less energy-intensive capture solvents; for example, mixtures of different amines, ionic liquids (IL), and mesoporous catalysts. Alternatively, capturing CO2 in a non- gaseous form such as bicarbonate (HCO3 ) is an effective, practical, and stable method for delivering CCh-bearing species to the utilization unit (such as an electrolyzer) that produces green chemicals, such as formate / formic acid. Figure 1 schematically shows the bicarbonate pathway of CO2 capture in PCC to be integrated with bicarbonate electrolysis for a variety of chemicals and fuels, including formate species.

[0242] The central hypothesis in our investigation into the bicarbonate pathway (Figure 1) lies in one or more of the following advantages over the use of CO2 gas as a carbon carrier for an integrated carbon capture / conversion process: (i) economical and operational benefits since it can substantially reduce the trans portation / storage costs related to handling high- pressure CO2 gas (e.g.. 14 MPa); (ii) improvement of the CO2 mass transfer rates in aqueous carbon capture technologies because of the 100 times greater carbon concentration in saturated solutions (3.3 M for saturated KHCOs compared with 0.033 M for saturated CO2); (iii) 50% less energy -intensive bicarbonate conversion into formic acid and formate species using an electrochemical reduction, in comparison to CO2 gas reduction; and (iv) no need to strip the CO2 captured by amine solutions using an energy -intensive temperature swing process, unlike in the traditional CCh-catch-and-release process.

[0243] The envisioned applications of CO2 capture as bicarbonate include the development of an integrated CO2 capture / conversion process via bicarbonate electrolysis to produce formate / formic acid as part of the potential pathways for CCUS (e.g.. the potential use of formate species as carbon carriers that are highly soluble in water or brine). The amount of carbon that one barrel of water or brine can contain as formate is equivalent to 70 - 100 kg of CO2 even at standard conditions. Therefore, potential value chains have been studied regarding the use of aqueous formate solution as a carbon carrier for surface storage and transportation, as well as for geologic carbon sequestration and enhanced oil recovery (EOR). The utilization of liquid carbon carriers as a way of storing CO2 represents an attractive strategy that benefits from their volumetric capacity, which substantially impacts other aspects including transportation and footprint per unit of CO2. Thus, the development of advanced CO2 carrier technologies has a crucial role in enabling the deployment of carbon removal technologies in the next decade.

[0244] With a focus on the bicarbonate pathway, we have studied the incorporation of surface activity into tertiary amines for enhanced in-situ generation of bicarbonate while capturing CO2 gas. Among several other compounds, surface-active amines were generated by chemically attaching propylene (PO) groups to the primary amino group of 3- dimethylaminopropylamine (DMAPA) at different levels: that is, DMAPA-xPO. where x = 4, 6, 8, 12. DMAPA with no PO is a diamine with one tertiary and primary amino group, but the incorporation of surface activity via PO groups made them efficient tertiary amines for bicarbonate generation. The CO2 capture capacity and bicarbonate generation by DMAPA- xPO were determined by13C NMR spectroscopy. In the experimental setup, a constant rate of CO2 at 50 mL / min was introduced into the 0.25 mol / L DMAPA-xPO solution at room temperature. Results showed that DMAPA (with no PO) formed two carbon species: carbamate derived from the reaction of CO2 with the primary amino group, and bicarbonate from the tertiary amino group with a maximum concentration of 0.36 mol / L after 60 min. DMAPA-xPO generated only bicarbonate during the CO2 capture process, as confirmed by13C NMR analysis. DMAPA-6PO was the optimum among the different PO levels tested with the final bicarbonate concentration of 0.55 mol / L. This represents the enhancement of bicarbonate generation by 54% in comparison to DMAPA (with no PO). The observed enhancement was attributed to the PO incorporation that increased the amount of dissolved CO2 in the amine solution up to 8.4 g CO2 / L for DMAPA-6PO, which was effectively converted into bicarbonate by the tertiary amino groups. Other tertiary amine species with surface activity' have also been successfully tested. We will continue to evaluate these surface-active tertiary amines for their chemical stability, regeneration methods, and longterm efficiency, and conduct a detailed economic analysis.

[0245] The bicarbonate pathway for integrated CO2 capture / utilization processes described herein can also include bicarbonate separation from the capture solution, and deprotonation of the surface-active amine. Capturing CO2 as bicarbonate is a relatively new process that necessitates this new research on bicarbonate separation and amine deprotonation. This separation process will be directly compared with the energy -intensive process of CO2 sorption / desorption by7temperature swing with conventional amines.

[0246] The research approach to evaluating both bicarbonate separation and amine regeneration in one step is through ion exchange membranes in a bipolar membrane electrodialysis (BPED) process. BPED is a common technology' in a class of electrical-driven separations used to extract ions from aqueous solutions at minimum operating cost. BPED systems are comprised of two electrodes separated by alternate liquid chambers filled with ion exchange resins divided by alternate cation exchange and anion exchange membranes with interspersed bipolar membranes. The applied current causes ions to move towards their respective oppositely-charged electrodes extracting them into concentrated compartments. We will use this phenomenon to separate bicarbonate from the surface-active amine in an adjacent chamber. Concurrently, the application of a potential across the bipolar membrane leads to water splitting and migration of proton and hydroxide ions in chambers on the opposite side of the bipolar membranes. When combined with appropriate counter ions (Na+or Cl'), it can be used to form acids and bases. The bases will be combined with the protonated amine to regenerate it for reuse while the recovered bicarbonate will be sent to the electrolyzer.

[0247] During the separation process, the protonated amine will remain isolated on the opposite side of the bicarbonate-rich chamber, as only bicarbonate will move across the anion exchange membrane, within the BPED unit. In this way, the protonated amine will be concentrated and tested for deprotonation to reutilize it for consecutive CO2 capture reactions, as shown in Figure 2. Contrary to the conventional amine regeneration by thermal stripping process, the surface-active amine deprotonation will be assessed by adding an alkaline solution that removes the proton attached to the amine until it becomes basic (free) again. In this way, the nitrogen group from the surface- active amine will be ready to react with more CO2 molecules producing bicarbonate.

[0248] BPED can effectively regenerate protonated bases in the CO2 capture process. Initial studies have involved the separation and regeneration of several bases, such as sodium hydroxide (NaOH), ammonia (NH3), and amine-based compounds [e.g., monoethanolamine (MEA) and aniline], after they w ere used for CO2 capture. Throughout this regenerative process, CO2 gas w as extracted from the solution as part of the “catch-and-release” application. These efforts confirmed that a chemical base regeneration through BPED was technically feasible with an energy’ reduction of around 30% in comparison to thermal methods. However, in these studies, CO2 was captured and attached to the amine in the form of carbamate (R-NH2+) or carbonate (CDs2-) species before the BPED step. Thus, the CO2 w as stripped off from the carbamate or chemically dissociated from carbonates to be released as a gas with an extra energy input in order to regenerate the base.

[0249] In the proposed bicarbonate pathway described herein, the separation and regeneration processes can be more energy-efficient than the above-mentioned technologies because of two main differences: (1) the bicarbonate product and the base (surface-active amine) are not attached, but co-exist as ionic interactions. This chemical environment is a key difference that will yield a greater energy reduction in comparison to thermal methods: and (2) the bicarbonate product is not chemically altered to be released as CO2 gas during the separation. Further, the proposed system is completely electrified with no need for heat or pressurization in any aspect of the process.

[0250] We will, as a result of this process, integrate ion exchange membrane separations within the BPED technology into the CCh-capture-as-bicarbonate pathway for the first time. This strategy will allow us to separate the bicarbonate product from the CO2 capture process, and deprotonate the surface- active tertiary amine simultaneously. Thermodynamic and kinetic considerations such as energy consumption and chemical stability need to be determined during the bicarbonate separation and surface-active amine regeneration assessments.

[0251] The development and utilization of surface-active tertiary amines are alternative strategies that contend directly with the conventional post-combustion carbon capture technology. Overall, the surface-active amines are mainly focused on capturing CO2 as bicarbonate. Contrary to the “CO2 catch-and-release” from the conventional capture technology, the bicarbonate product is a higher carbon-content solution that can be either transported / stored and utilized to produce green chemicals with lower energy consumption than with gaseous CO2. This bicarbonate strategy was proposed and studied as a potential carbon management pathway. Consequently, the incorporation of an ion exchange membrane technology to separate the carbonate product while performing the amine regeneration stands as the next pivotal step. The resulting CO2 capture process via bicarbonate can be much less energy intensive in comparison to conventional CO2 catch-and-release, which will be quantified as part of the project.

[0252] Results from this project will provide proof-of-concept validation for the proposed CO2 capture as bicarbonate pathway with practical recyclability of the surface-active tertiary amines derived from the separation process by membranes. Such successful research outcomes will be integrated with another active project on bicarbonate electrolysis to develop a lab-scale prototype for CO2 capture / conversion.

[0253] Experimental Methods

[0254] Example experimental analysis and methods are presented below:

[0255] CO2 capture as bicarbonate . A gas mixture of CO2 and N2 will be introduced into a closed three-neck flask containing 200 mL of the surface-active tertiary amine solution. Its optimal molar concentration will be studied between 0. 1 and 1 mol / L. The CO2 concentration will be varied from 3 - 20% in the mixtures with N2 within a mixer using mass flow controllers. The flow rate of the mixture will be 90 mL / min. A CO2 infrared analyzer will be placed at the outlet. The temperature during the capture process will be also tested in a range of 25 - 40°C through a water bath. The generated bicarbonate amount and the chemical alterations of the amine (protonation) during the experiments will be analyzed by 'H and13C NMR and FTIR spectroscopies by taking liquid samples every 10 min. The CO2 loading amount defined as the mole number of captured CO2 per mole of amine will be determined by acidic titration with 1 M HC1 solution with methyl orange as an indicator. The pH will be also monitored during the experiments.

[0256] Bicarbonate separation. We will utilize an existing PC-Cell BPED cell that is currently in operation by reconfiguring it to have each stack of membranes containing an anion exchange membrane (AIM) and a cation exchange membrane (CIM) between two bipolar membranes (BPM). In this setup, the bicarbonate containing amine will simultaneously be stripped of bicarbonate while being regenerated using the base generated from the bipolar membrane. We will test membranes from Veolia and PCCell that are already in use in our lab to conduct initial experiments with loaded amines to evaluate the production of stripped bicarbonate as well as the efficiency of regeneration of the tertiary amine. We will utilize a constant current density' operation profile with tests ranging from 6 - 12 mA / cm2and flows adjusted to maintain stable performance.

[0257] Deprotonation analysis. A potentiometric titration with an alkaline solution will be used to evaluate the deprotonation level of amine after the ion exchange membrane separation from bicarbonate. This method is widely used in the analysis of weak acid and weak base content by measuring the pH or the potential value of the titration indicating the endpoint of the reaction. This titration will be carried out utilizing a Mettler-Toledo T50 automatic potentiometric titrator equipped with a DG113-SC glass electrode. Typically, a 2 rnL sample will be placed in the sample container and titrated with a standardized 1 M NaOH solution. During this time, pH values and titrant volume will be recorded until the end of the neutralization reaction. Then, the derivation method is used to calculate the concentration of the amine sample at the stoichiometric point.

[0258] References

[0259] 1. Environmental Protection Agency. Inventory of U.S. Greenhouse Gas Emissions and

[0260] Sinks: 1990-2019. 2021. 2. Liu Z, Deng Z, Davis SJ. Giron C, Ciais P. Monitoring global carbon emissions in 2021. Nat Rev Earth Environ 2022; 3:217-9.

[0261] 3. Wang X, Song C. Carbon Capture From Flue Gas and the Atmosphere: A Perspective. Front Energy Res 2020; 8.

[0262] 4. Nesbitt ER. Using Waste Carbon Feedstocks to Produce Chemicals. Industrial Biotechnology 2020: 16:147-63.

[0263] 5. Peplow M. The race to upcycle CO2 into fuels, concrete and more. Nature 2022; 603:780-3.

[0264] 6. Jiang Y, Mathias PM, Freeman CJ, Swisher JA, Zheng RF, Whyatt GA, Heldebrant DJ, Techno-economic comparison of various process configurations for post-combustion carbon capture using a single-component water-lean solvent. International Journal of Greenhouse Gas Control 2021; 106: 103279.

[0265] 7. Rochelle GT. Conventional amine scrubbing for CO2 capture. Absorption-Based Post- Combustion Capture of Carbon Dioxide, Elsevier Inc.; 2016, p. 35-67.

[0266] 8. Wall TF. Combustion processes for carbon capture. Proceedings of the Combustion Institute 2007; 31 :31-47.

[0267] 9. Raganati F, Miccio F, Ammendola P. Adsorption of Carbon Dioxide for Postcombustion Capture: A Review. Energy' and Fuels 2021; 35: 12845-68.

[0268] 10. Gutierrez-Sanchez O, Bohlen B, Daems N, Bulut M, Pant D, Breugelmans T. A State- of-the- Art Update on Integrated CO2 Capture and Electrochemical Conversion Systems. ChemElectroChem 2022; 9.

[0269] 11. Bairq ZAS, Gao H, Murshed FAM, Ton tiwachwuthi kul P, Liang Z. Modified Heterogeneous Catalyst- Aided Regeneration of CO2 Capture Amines: A Promising Perspective for a Drastic Reduction in Energy Consumption. ACS Sustain Chem Eng 2020; 8:9526-36.

[0270] 12. Metz B, Davidson O, de Conick H, Loos M, Meyer L. Carbon Dioxide Capture and Storage, The Intergovernmental Panel on Climate Change (IPCC). 2005.

[0271] 13. Li T, Lees EW. Goldman M. Salvatore DA, Weekes DM, Berlinguette CP. Electrolytic Conversion of Bicarbonate into CO in a Flow Cell. Joule 2019; 3: 1487-97.

[0272] 14. Welch AJ, Dunn E, Duchene JS, Atwater HA. Bicarbonate or Carbonate Processes for Coupling Carbon Dioxide Capture and Electrochemical Conversion. ACS Energy Lett 2020; 5: 940-5. 15. Zhang Z, Lees EW, Ren S, Huang A, Berlinguette CP. Electrolytic Conversion of Bicarbonate Solutions to CO at >500 mA cm'2and 2.2 V. ChemRxiv 2021: 1-13.

[0273] 16. Li T, Lees EW, Zhang Z, Berlinguette CP. Conversion of Bicarbonate to Formate in an Electrochemical Flow Reactor. ACS Energy Lett 2020; 5:2624-30.

[0274] 17. Hanna Marie Breunig, Fabian Rosner, Tae-Hwan Lim, Peng Peng. Emerging concepts in intermediate carbon dioxide emplacement to support carbon dioxide removal. Energy Environ. Sci. 2023,16. 1821-1837.

[0275] 18. Oyenowo, O.P., Wang, H , Mirzaei-Paiaman, A., Carrasco-Jaim, O.A., Sheng, K., Okuno, R. Geochemical Impact of High-Concentration Formate Solution on Rock Wettability for Enhanced Oil Recovery' and Geological Carbon Storage. Energy & Fuels. 2024. In press.

[0276] 19. Wang, H., Oyenowo. P.O.. Okuno, R.. Aqueous Formate Solution for Enhanced Water Imbibition in Oil Recovery and Carbon Storage in Carbonate Reservoirs. Fuel. 2023; 345, 128198.

[0277] 20. Oyenowo, O.P., Sheng, K., Okuno, R.. Simulation Case Studies of Aqueous Formate Solution for Geological Carbon Storage. Fuel. 2023; 334, 126643.

[0278] 21. Baghishov, I., Abeykoon, G.A., Mingyuan, W., Oyenowo, O.P., Argiielles-Vivas, F.J., Okuno, R., A Mechanistic Comparison of Formate, Acetate, and Glycine as Wettability Modifiers for Carbonate and Shale Formations. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2022; 652, 129849.

[0279] 22. Carrasco-Jaim. OA, Xia H, Weerasooriya UP. Okuno R. CO2 capture as bicarbonate using DMAPA with incorporation of surface activity. Fuel 2023; 348, 128554.

[0280] 23. B. Senthil Rathi, P. Senthil Kumar. Electrodeionization theory, mechanism and environmental applications. A revieyv. Environmental Chemistry Letters. 2020; 18: 1209- 1227.

[0281] 24. B. Senthil Rathi, P. Senthil Kumar, R. Parthiban. A review on recent advances in electrodeionization for various environmental applications. Chemosphere. 2022; 28: 133223.

[0282] 25. Zhengyuan Song, Guogang Sun, Zetao Wang, Shiwei Yuan, Chenhao Xi. Design and study of a novel ammonia-based CO2 capture process with bipolar membrane electrodialysis. Can J Chem Eng. 2023; 102: 658-668.

[0283] 26. Sriram Valluri, S.K. Kawatra. Reduced reagent regeneration energy for CO2 capture with bipolar membrane electrodialysis. Fuel Processing Technology7. 2021. 213: 106691. 27. Qiuyue Wang, Chenxiao Jiang, Yaoming Wang. Zhengjin Yang, Tongwen Xu. Reclamation of Aniline Wastewater and CO2 Capture Using Bipolar Membrane Electrodialysis. ACS Sustainable Chem. Eng. 2016. 4; 5743-5751.

[0284] 28. Stepan Bazhenov, Alexander Rieder, Bemd Schallert, Vladimir Vasilevsky7, Sven Unterberger, Evgeniia Grushevenko, Vladimir Volkov, Alexey Volkov. Reclaiming of degraded MEA solutions by electrodialysis: Results of ED pilot campaign at post-combustion CO2 capture pilot plant. International Journal of Greenhouse Gas Control. 2015. 42; 593- 601.

[0285] Additional References

[0286] 1. Rochelle GT. Conventional amine scrubbing for CO2 capture. Absorption-Based PostCombustion Capture of Carbon Dioxide, Elsevier Inc.; 2016, p. 35-67.

[0287] 2. Wall TF. Combustion processes for carbon capture. Proceedings of the Combustion Institute 2007; 31 :31-47.

[0288] 3. Raganati F, Miccio F, Ammendola P. Adsorption of Carbon Dioxide for Postcombustion Capture: A Review. Energy and Fuels 2021; 35: 12845-68.

[0289] 4. Gutierrez-Sanchez O, Bohlen B, Daems N, Bulut M, Pant D, Breugelmans T. A State- of-the-Art Update on Integrated CO2 Capture and Electrochemical Conversion Systems. ChemElectroChem 2022; 9.

[0290] 5. Bairq ZAS. Gao H. Murshed FAM, Tontiwachwuthikul P, Liang Z. Modified Heterogeneous Catalyst-Aided Regeneration of CO2 Capture Amines: A Promising Perspective for a Drastic Reduction in Energy Consumption. ACS Sustain Chem Eng 2020; 8:9526-36.

[0291] 6. Metz B, Davidson O. de Conick H, Loos M, Meyer L. Carbon Dioxide Capture and Storage, The Intergovernmental Panel on Climate Change (IPCC). 2005.

[0292] 7. Li T, Lees EW, Goldman M, Salvatore DA, Weekes DM, Berlinguette CP. Electrolytic Conversion of Bicarbonate into CO in a Flow Cell. Joule 2019; 3: 1487-97.

[0293] 8. Welch AJ, Dunn E, Duchene JS, Atwater HA. Bicarbonate or Carbonate Processes for Coupling Carbon Dioxide Capture and Electrochemical Conversion. ACS Energy Lett 2020: 5:940-5.

[0294] 9. Zhang Z, Lees EW, Ren S, Huang A, Berlinguette CP. Electrolytic Conversion of Bicarbonate Solutions to CO at >500 mA cm'2and 2.2 V. ChemRxiv 2021:1-13.

[0295] 10. Li T, Lees EW. Zhang Z, Berlinguette CP. Conversion of Bicarbonate to Formate in an Electrochemical Flow Reactor. ACS Energy Lett 2020;5:2624-30. Example 2. Electrochemical Regeneration of Surface-Active Amines for Enhanced CO2 Capture and Bicarbonate Utilization.

[0296] Overview

[0297] The overall objective of this work is to advance direct air CO2 capture (DAC) through an integrated bicarbonate pathway. Bicarbonate is generated and utilized in this pathway as part of an integrated carbon management strategy, spanning from the capture to the carbon utilization process. This approach relies on a class of surface-active tertian amines that enhance bicarbonate generation in aqueous CO2 capture reactions. Utilizing bicarbonate solutions as carbon carriers offers several advantages, including reduced transportation costs and footprint, increased carbon concentration per storage unit, easier sorbent regeneration, and lower energy requirements for producing green chemicals (through electrolysis).

[0298] This example further describes electrochemical methods for regenerating the tertiary amines used in CO2 capture as bicarbonate. The process leverages ion exchange membranes within bipolar electrodialysis (BPED) technology, facilitating selective bicarbonate ion transport from the amine capture solution while simultaneously regenerating the amines through deprotonation. The example also describes new- insights into electrochemical membrane-based processes for carbon capture by investigating key factors governing bicarbonate transport and amine regeneration, such as pH, ion conductivity, and membrane selectivity. The example also offers innovative pathways for designing specialized membranes crucial to the energy transition.

[0299] Introduction and Necessity

[0300] An example process of CO2 capture applies to both traditional post-combustion carbon capture (PCC) and the relatively new DAC processes. Amine-based PCC is a well- proven, commercially used technology for CO2 capture with CO2 recovery rates of up to 800 tonnes / day. PCC typically uses a single or a blend of reactive aqueous amine solutions to react chemically with CO2 gas in an acid-base reaction. Then, the CO2 gas is subsequently stripped from the amine solution (catch-and-release) at high temperatures (e.g.. 120-180°C) while regenerating the amine solvent. The regeneration step is considered the main drawback of this technology, and its regeneration cost can be as high as 70% of the total operating cost.

[0301] A w idely studied strategy for improving the energy efficiency in PCC is the development of less energy-intensive capture solvents; for example, mixtures of different amines, ionic liquids (IL), and mesoporous catalysts. Alternatively, capturing CO2 in a non- gaseous form, such as bicarbonate (HCCh ). is an effective, practical, and stable method for delivering CCh-bearing species to the utilization unit (such as an electrolyzer) that produces green chemicals, including formate / formic acid, carbon monoxide, methanol, and others. Figure 3 schematically shows the bicarbonate pathway of CO2 capture and conversion into chemicals and fuels (for both PCC and that proposed for DAC). The benefits of using bicarbonate as a carbon carrier over CO2 gas for integrated carbon management are: (a) economic and operational advantages, which reduce the transportation and storage costs and footprint by not using pressurized CO2 (typically around 14 MPa); (b) high carbon concentration in saturated aqueous media (a hundred times greater than CO2 saturated solution); and (c) energy reduction in the electrochemical conversion to produce chemicals (around 50% less energy than using CO2 gas electrolysis).

[0302] Technical Approach

[0303] The first step within the proposed bicarbonate pathway (Figure 3) is capturing CO2 as aqueous bicarbonate solution. In this regard, we have studied the incorporation of surface activity into tertiary amines for enhanced in-situ bicarbonate generation while capturing CO2 gas. Among several other compounds, surface-active amines (SAA) were generated by chemically attaching propylene (PO) groups to the primary amino group of 3- dimethylaminopropylamine (DMAPA) at different levels; that is, DMAPA-xPO, where x = 4, 6, 8, 12. DMAPA with no PO is a diamine with one tertiary and primary amino group, but the incorporation of surface activity via PO groups made them efficient tertian’ amines for bicarbonate generation. We have tested several tertiary amine species for efficient bicarbonate generation from low-concentration CO2 sources with varying amine concentrations. One of the primary' benefits of using SAAs is that they generate bicarbonate from captured CO2 with 100% selectivity without generating carbamates that require high energy input to release CO2. Compared to conventional tertiary amines, SAAs generate bicarbonate with faster kinetics because of their improved CO2 solubility, benefiting the overall performance without using any additive or amine mixture.

[0304] The second step is the separation of bicarbonate and the amine regeneration (Figure 3). As an alternative to the ty pical high-energy requirement temperature swing, electrochemically driven separation (electrodialysis) and regeneration have advantages owing to their high adaptability to diverse solute concentrations and compositions without needing thermal energy (heating). Ion exchange membrane (IEM) technology has been successfully utilized in water, environmental, energy, and chemical production applications, such as electrodialysis desalination, fuel cells, and chloralkali production.

[0305] In some embodiments, the process can comprise (1) electrodialysis performed in a cell using a cation exchange membrane and an anion exchange membrane to afford separation of the bicarbonate; and (2) amine regeneration. In some examples, both bicarbonate separation and amine regeneration can be performed using ion exchange membranes in a bipolar membrane electrodialysis (BPED) process. BPED is an electrochemical membrane process that hybridizes the ion migration capabilities of the ED with water splitting in the bipolar membrane (BP). A schematic representation of an example proposed bicarbonate separation and amine regeneration mechanism is shown in Figure 4. The capture solution containing the bicarbonate product and the resulting SAA+will be introduced to a feed chamber. From there, the bicarbonate ions will move across the anion exchange membrane into a product chamber to be separated from the capture solution. On the other hand, the SAA+will remain on the opposite side of the bicarbonate-rich chamber next to the bipolar membrane. The applied potential across the bipolar membrane will drive the water-splitting reaction, providing hydroxyl ions (OH') needed to regenerate the SAA in an acid-base reaction (deprotonation). After these two simultaneous reactions, the regenerated SAA will be reutilized to capture more CO2, while the separated bicarbonate solution can be directly used as a feedstock. Optionally, the overall bicarbonate pathway (Figure 3) can further include the electrochemical conversion of bicarbonate into value-added carbon materials as a further step. However, this example focuses on the two steps prior to the bicarbonate conversion, especially for applications to low-concentration CO2 sources, including direct air capture (DAC). We have obtained promising preliminary data for this approach at a range of CO2 concentrations. A general outline of tasks performed as part of our investigation of these processes.

[0306] Task 1 - SAA for low-concentration CO2 sources. Surface-active tertiary amines (S AAs) for bicarbonate generation with 100% selectivity from the CO2 capture reaction have been developed and successfully tested. We have explored physicochemical properties that facilitated this improved bicarbonate formation. Further efforts will focus on optimizing CO2 capture with an SAA bench-scale system for low-concentration CO2 sources (0.4% to 20%), with a daily capture capacity' of 1 kg CO2.

[0307] A gas mixture of CO2 and N2 will be introduced into a closed three-neck flask containing the tertiary surface-active amine (SAA) solution to be tested. Its optimal molar concentration will be studied below the aqueous stability limit, which depends on the SAA to be tested. In detail, the SAA concentration will be tested from 0. 1 to 3 mol / L (—2.5 to 40 wt .%) for a relevant industrial range. The CO2 concentration will be varied from 20% to 0.4% in the mixture with N2 within a mixer. The flow rate of the mixture will be kept constant, for example, at 100 mL / min. A CO2 infrared analyzer (Quantek, Model 906) will be placed at the outlet to evaluate the progress of the capture reaction. The %CCh readings will be taken from this analyzer. The pH will also be monitored during the experiments (Fisher Scientific. AE150). During the capture process, the temperature will also be tested at 25 - 40°C through a water bath (Julabo, Model F32). The generated bicarbonate amount and the chemical alterations of the amine (protonation) during the experiments will be analyzed and quantified by 'H and13C NMR and FTIR spectroscopies by taking liquid samples every 10 min. The total mass of captured CO2 will be calculated from the analyzer readings to determine the CO2 loading amount, defined as the mole number of captured CO2 per mole of amine.

[0308] Task 2 - BPED system for amine regeneration / bicarbonate separation. We will evaluate separating the bicarbonate product from the capture solution and regenerating the surface-active amine. This will be achieved through bipolar electrodialysis (BPED), an advanced electro-membrane process gaining attention for carbon capture due to its versatility, simple operation, and low energy consumption. The goal is to achieve an energy7consumption of less than 4 MJ / kg CO2 captured, corresponding to the energy efficiency of the conventional thermal regeneration method.

[0309] After the capture solution mixture is generated (Task 1), the electrochemical separation and regeneration reactions will take place in an existing BPED system (PCCell, ED 64004 model) that is currently in operation in our labs at UT Austin. The laboratory now features a second electrodialyzer system (YAS A ET, Desalt-EDBM). enabling faster progress in this task. The BPED will be reconfigured to have each stack of membranes containing an anion exchange membrane (AIM) and a cation exchange membrane (CIM) between two bipolar membranes (BPM), as illustrated in Figure 4. Ion-exchange membranes from Veolia will be utilized for this research, including CEM CR61, AEM AR103, and BPM AR103BP. Other sources for IX and BPM membranes will also be used. The capture solution mixture containing the bicarbonate product and the protonated surface-active amine (SAA+) will be fed into the cell using a recirculating configuration. Based on previous works, constant potential / current will be tested, ranging from 3 - 20 V and 0.5 - 1 A, respectively. The flow will be adjusted to 0.1 GPM to maintain stable performance. Parameters such as pH, temperature, and conductivity will be constantly monitored during the reactions. Results from these evaluations will provide a relationship between the concentration of the CO2 input stream, the bicarbonate generation rates, the SAA concentration, and the energy consumption for its regeneration

[0310] Preliminary Results

[0311] Figures 5A and 5B schematically illustrate the principles involved in bicarbonate separation and amine regeneration using ion exchange membranes. Anion exchange membranes selectively permit transport of negatively charged ions (e g. OH", HCO ) across the membrane. Cation exchange membranes selectively permit transport of positively charged ions (e.g. H+, Na+) across the membrane. Bipolar membrane can comprise a combination of anion and cation exchange membrane (e.g., sandwiched together). Under an applied potential, bipolar membranes can be used for water dissociation, forming a source of hydroxide ions for amine regeneration.

[0312] A variety of electrochemical cells can be used to effectuate bicarbonate separation and amine regeneration. These electrochemical cells can utilize electrodialysis in combination with ion exchange membranes to separate bicarbonate ions. By way of example, bicarbonate separation and amine regeneration can be performed in an electrochemical cell including an anode, a cathode, and one or more chambers or compartments disposed between the anode and the cathode. The one or more chambers or compartments can comprise paths for fluid flow bounded by one or more ion exchange membranes.

[0313] Figure 5B illustrates an example how such systems can be employed to separate bicarbonate ions. In the example systems illustrated in Figure 5B, the electrochemical cell includes an anode, a cathode, and three compartments disposed between the anode and the cathode separated by anion exchange membranes. Capture solution can flow into the middle (second) compartment. A source of hydroxide ions can be provided in the left (first) compartment. Under an applied potential, negative ions can migrate tow ards the cathode. The anion exchange membrane can selectively permit migration of bicarbonate from the second compartment to the right (third) compartment. In this ay, the bicarbonate ions can be separated from the capture solution. Likewise, the anion exchange membrane can selectively permit migration of hydroxide ions from the first compartment to the second compartment, where the hydroxide ions can neutralize and regenerate the amine capture agent. Such a cell can thus be used to separate bicarbonate ions and regenerate the amine capture agent. By way of example, certain example strategies for processing the capture solution are described below.

[0314] Figure 6 shows an example strategy for performing bipolar membrane electrodialysis in a single step to both separate the bicarbonate and regenerate the amine capture agent. As shown in Figure 6, a feed comprising the capture solution comprising a bicarbonate salt of the amine capture agent flows into a first compartment. In this system, bicarbonate separation and amine deprotonation both occur in the same compartment (the first compartment). The first compartment is bounded by an anionic exchange membrane and a bipolar membrane. Under applied potential, negative ions can migrate towards the cathode. The anion exchange membrane can selectively permit migration of bicarbonate from the first compartment to a second compartment. In this way. the bicarbonate ions can be separated from the capture solution. Further, under an applied potential, the bipolar membrane provides for hydroxyl ions (generated from water splitting) to regenerate the surface-active gas capture agent. In this example, a sodium salt (sodium chloride) introduced into another compartment is also subjected to electrodialysis to provide sodium ions. These sodium ions can migrate into the compartment where bicarbonate migrates so as to produce a product stream comprising sodium bicarbonate.

[0315] Figure 7 shows an example strategy for performing two-step bipolar membrane electrodialysis. Here, bicarbonate separation and amine regeneration processes occur in two different compartments present in two different electrochemical cells disposed in series. In this example arrangement, the first cell includes a first compartment is bounded by an anionic exchange membrane and a cation exchange membrane. Under applied potential, negative ions can migrate towards the cathode. The anion exchange membrane can selectively permit migration of bicarbonate from the first compartment to a second compartment. In this way, the bicarbonate ions can be separated from the capture solution. In this example, a sodium salt (sodium chloride) introduced into another compartment is also subjected to electrodialysis to provide sodium ions. These sodium ions can migrate into the compartment where bicarbonate migrates so as to produce a product stream comprising sodium bicarbonate. Meanwhile, the capture solution (still containing protonated capture agent), flows into a second electrochemical cell where regeneration is performed. In this second cell, BPED can be performed to allow the amine to be deprotonated by hydroxyl ions generated from water splitting, thereby regenerating the surface-active gas capture agent. Figure 8 is a plot comparing the performance of the process illustrated in Figure 6 (bipolar membrane electrodialysis in a single step; "Single Step BPED”) and the process illustrated in Figure 7 (two-step bipolar membrane electrodialysis: ‘'2-Step BPED). As shown in Figure 8, two-step bipolar membrane electrodialysis system affords 50% more separation while requiring 40% less energy.

[0316] Figure 9 shows an example in which a base was subjected to electrodialysis to provide hydroxyl ions to regenerate the surface-active gas capture agent. Here, bicarbonate separation and amine regeneration are performed in a single step using '‘Anion-Exchange Enhanced Electrodialysis” (AE-ED). Because water dissociation is not require to provide hydroxyl ions, a lower energy is required. The system also provides for faster OH- diffusion and better control over OH- transport and concentration.

[0317] In the example systems illustrated in Figure 9, the electrochemical cell includes an anode, a cathode, and five compartments disposed between the anode and the cathode. Capture solution can flow into the middle (third) compartment. A source of hydroxide ions (a base such as NaOH) can be provided in the second compartment from the left. Under an applied potential, negative ions can migrate towards the cathode. An anion exchange membrane can selectively permit migration of bicarbonate from the third compartment to the fourth compartment from the left. In this way, the bicarbonate ions can be separated from the capture solution. Likewise, an anion exchange membrane can selectively permit migration of hydroxide ions from the second compartment to the third compartment, where the hydroxide ions can neutralize and regenerate the amine capture agent. Such a cell can thus be used to separate bicarbonate ions and regenerate the amine capture agent.

[0318] Figure 10 is a plot showing the performance of the AE-ED system illustrated in Figure 9. As shown in Figure 10, the system achieved around 80% bicarbonate separation, and required 60% less energy (1.5 MJ / kg CO2) than thermal regeneration.

[0319] We also performed preliminary studies to evaluate the effect of different applied voltages on BPED systems. As shown in Figure 11, lower voltages improved system performance by preventing CO2 off-gassing.

[0320] References

[0321] 1. Gutierrez-Sanchez O, Bohlen B, Daems N, Bulut M, Pant D, Breugelmans T. A State- of-the-Art Update on Integrated CO2 Capture and Electrochemical Conversion Systems. ChemElectroChem 2022;9. 2. Metz B, Davidson O. de Conick H, Loos M, Meyer L. Carbon Dioxide Capture and Storage, The Intergovernmental Panel on Climate Change (IPCC). 2005.

[0322] 3. Li T, Lees EW, Goldman M, Salvatore DA, Weekes DM, Berlinguette CP. Electrolytic Conversion of Bicarbonate into CO in a Flow Cell. Joule 2019;3: 1487-97.

[0323] 4. Welch AJ, Dunn E, Duchene JS, Atwater HA. Bicarbonate or Carbonate Processes for Coupling Carbon Dioxide Capture and Electrochemical Conversion. ACS Energy Lett 2020;5:940-5.

[0324] 5. Zhang Z, Lees EW, Ren S, Huang A, Berlinguette CP. Electrolytic Conversion of Bicarbonate Solutions to CO at >500 mA cm-2 and 2.2 V. ChemRxiv 2021: 1-13.

[0325] 6. Li T, Lees EW. Zhang Z, Berlinguette CP. Conversion of Bicarbonate to Formate in an Electrochemical Flow Reactor. ACS Energy Lett 2020;5:2624-30.

[0326] 7. Adekomi A. A., Carrasco-Jaim O. A., Weerasooriya U. P., Okuno R. Enhanced CO2 Capture-Desorption by Surface- Active Amine. Energy Fuels 2024, 38, 14435-14448.

[0327] 8. Carrasco-Jaim O. A., Xia H.. Weerasooriya U. P., Okuno R. CO2 Capture as Bicarbonate using DMAPA with Incorporation of Surface Activity. Fuel 2023. 348, 128554.

[0328] 9. H. Wang, J. Yan, W. Song, C Jiang, Y. Wang, T. Xu. Ion exchange membrane related processes towards carbon capture, utilization and storage: Current trends and perspectives. Separation and Purification Technology7. 2022; 296:121390.

[0329] The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims and any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compositions and method steps disclosed herein are specifically described, other combinations of the compositions and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein; however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

Claims

WHAT IS CLAIMED IS:1 . A method for capturing carbon dioxide gas from a gas stream, the method comprising: contacting the gas stream with a capture solution comprising a surface-active gas capture agent to form a bicarbonate salt of the surface-active gas capture agent; and processing the capture solution to separate the bicarbonate from the capture solution and regenerate the surface-active gas capture agent.

2. The method of claim 1, wherein the surface-active gas capture agent comprises an amine moiety, and processing the capture solution to regenerate the surface-active gas capture agent comprises deprotonating the amine moiety.

3. The method of any one of claims 1-2, wherein processing the capture solution comprises subjecting the capture solution to electrodialysis to separate the bicarbonate from the capture solution.

4. The method of claim 3, wherein the electrodialysis comprises electrically driven separation of bicarbonate ions from protonated surface-active gas capture agent.

5. The method of any one of claims 3-4, wherein the electrodialysis is performed in an electrochemical cell comprising an anode, a cathode, and one or more compartments for fluid flow defined by ion exchange membranes.

6. The method of any one of claims 3-5, wherein the electrodialysis comprises bipolar membrane electrodialysis (BPED).

7. The method of claim 6, wherein the surface-active gas capture agent comprises an amine moiety, and BPED further comprises amine deprotonation by hydroxyl ions generated from water splitting to regenerate the surface-active gas capture agent.

8. The method of any one of claims 3-5, wherein the surface-active gas capture agent comprises an amine moiety, and processing the capture solution further comprises subjectinga solution comprising a base to electrodialysis to provide hydroxyl ions to regenerate the surface-active gas capture agent.

9. The method of any one of claims 3-8, wherein bicarbonate separation and regeneration of the surface-active gas capture agent occur in a single step.

10. The method of claim 9, wherein the bicarbonate separation and the regeneration of the surface-active gas capture agent occurs in a single compartment.

11. The method of any one of claims 3-8, wherein bicarbonate separation and regeneration of the surface-active gas capture agent occur in two separate steps performed in two separate compartments.

12. The method of any one of claims 1-11, wherein the method further comprises electrochemical conversion of the bicarbonate.

13. The method of any one of claims 1-11, wherein the processing the capture solution further comprises subjecting a solution comprising a potassium salt or a sodium salt to electrodialysis to provide potassium ions or sodium ions to produce a product stream comprising potassium bicarbonate or sodium bicarbonate.

14. The method of any one of claims 1-13, wherein the surface-active gas capture agent comprises a blend of a gas capture agent and a surfactant.

15. The method of claim 14, wherein the surfactant exhibits an HLB value of from 6 to15. such as from 6 to 8, from 6 to 10, from 6 to 12, from 8 to 10, from 8 to 12, from 8 to 15, from 10 to 12, from 10 to 15, or from 12 to 15.

16. The method of any of claims 14-15, wherein the surfactant comprises a non-ionic surfactant.

17. The method of any of claims 14-16, wherein the surfactant comprises an alcohol alkoxylate.

18. The method of claim 17, wherein the alcohol alkoxylate comprises at least one propoxy segment.

19. The method of any of claims 14-18, wherein the surfactant is defined by Formula IR1— O-(BO)x-(PO)y-(EO)z- QFormula I whereinBO represents -CH2-CH(ethyl)-O- and / or -CH2CH(-)CH(O-)CH2-;PO represents -CH2-CH(methyl)-O-;EO represents -CH2-CH2-O-;R1represents a C8-C32 alky l group, a C8-C32 alkenyl group, a C8-C32 alkynyl group, an aryl group, or an alkylaryl group;Q is hydrogen; x is an integer from 0 to 10; y is an integer from 0 to 40; and z is an integer from 0 to 40, with the proviso that at least one of x, y, and z is greater than 0.

20. The method of any of claims 14-19, wherein the surfactant is defined by Formula IAR'-O-(PO)y-(EO)z-QFormula I A whereinBO represents -CH2-CH(ethyl)-O- and / or -CH2CH(-)CH(O-)CH2-;PO represents -CH2-CH(methyl)-O-;EO represents -CH2-CH2-O-;R1represents a C8-C32 alkyl group, a C8-C32 alkenyl group, a C8-C32 alkynyl group, an ary l group, or an alkyl aryl group;Q is hydrogen; y is an integer from 1 to 40; and z is an integer from 1 to 40.

21. The method of any of claims 14-20, wherein the gas capture agent comprises an amine gas capture agent.

22. The method of claim 21, wherein the amine gas capture agent comprises a monoamine, a diamine, or a polyamine.

23. The method of any of claims 21-22, wherein the amine gas capture agent comprises a tertiary amine.

24. The method of any of claims 21-23, wherein the amine gas capture agent comprises a sterically hindered amine.

25. The method of any of claims 21-24, wherein the gas capture agent comprises methylamine, ethylamine, propylamine, iso-propylamine, buty lamine, iso-butylamine, secbutylamine, tert-butylamine. pentylamine, iso-pentylamine. sec-penlylamine. tertpentylamine, hexylamine, iso-hexylamine, sec-hexylamine, tert-hexylamine, ethylenediamine, (2-methylbutyl)amine, 2-aminopentane, 3-(tert-butoxy)propylamine, 2- amino-6-methylheptane, 1 -ethylpropylamine dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine. N-ethylmethylamine, N-isopropylmethylamine, N-butylmethylamine, N-ethylisopropylamine. N-tert-butylmethylamine, N-ethylbutylamine. 3-isopropoxypropylamine, chloro(diethylamino)dimethylsilane, 2,2'- (ethylenedioxy)bis(ethylamine), 1 ,3-bis(chloromethyl)-l , 1 ,3,3-tetramethyldisilazane, N-tert- butylisopropylamine, N,N-diethyltrimethylsilylamine, di-sec-butylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylpropylamine, diethylpropylamine, N,N-diisopropylmethylamine, N-ethyldiisopropylamine, N,N-dimethylethylamine, N,N- di ethylbutylamine, 1,2-dimethylpropylamine, N,N-diethylmethylamine, N,N- dimethylisopropylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, N,N- dimethylbutylamine, tetramethylethylenediamine (TMEDA), tetraethylmethanediamine (TEMDA). tetramethylmethanediamine (TMMDA), tetramethyl-1.3-diaminopropane (TMPDA) or triethylamine (TEA), polyethyleneimines or oligomeric forms thereof (e.g., diethylenetriamine, triethylenetetramine, or tetraethylenepentamine where the nitrogen atoms are tertiary by way of alkylation or alkoxylation), polyvinylamines or oligomeric forms thereof (containing tertiary amines), monoethanolamine (MEA), diethanolamine (DEA). N-methyldiethanolamine (MDEA). 2-di ethylaminoethanol (DEAE), 3-(di ethylamino)- 1,2- propanediol (DAPD) or 2-amino-2-methyl propan- l-ol (AMP), piperazine (PZ), morpholine, piperidine, pyrrolidine, l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), glycine, or a combination thereof.

26. The method any one of claims 1-13, wherein the surface-active gas capture agent comprises a surfactant comprising an amine moiety.

27. The method of claim 26, wherein the surface-active gas capture agent comprises a surfactant comprising a tertiary' amine moiety.

28. The method of any one of claims 26-27, wherein the surface-active gas capture agent comprises a surfactant comprising a sterically hindered amine moiety.

29. The method of any one of claims 26-28, wherein the surface-active gas capture agent comprises a compound defined by Formula II or Formula IIIR2N-(PO)y-(EO)z-Q R2Formula IIR2 z(PO)y-(EO)z-QL-NR2z(PO)y-(EO)z-QFormula III wherein, individually for each occurrence,PO represents -CH2-CH(methyl)-O-;EO represents -CH2-CH2-O-;R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an aryl group, an alkylaryl group, or oxyalkylene group POyEOz-Q;Q is hydrogen; y is an integer from 0 to 60; and z is an integer from 0 to 40, with the proviso that at least one of y and z is greater than 0.

30. The method of any one of claims 26-29, wherein the surface-active gas capture agent comprises a compound defined by Formula II or Formula IIIR2N-(PO)y-(EO)z-Q R2Formula IIFormula III wherein, individually for each occurrence.PO represents -CH2-CH(methyl)-O-;EO represents -CH2-CH2-O-;R2represents, hydrogen, a Ci-Cs alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, an aryl group, an alkylaryl group, or oxyalkylene group POyEOz-Q;Q is hydrogen; y is an integer from 1 to 60; and z is an integer from 0 to 40.

31. The method of any one of claims 1-13, wherein the surface-active gas capture agent is present in the capture solution in an amount of from 0.5% by weight up to an aqueous solubility limit of the surface-active gas capture agent, based on a total weight of the capture solution, such as from 0.5% to 40% by weight, from 5% to 40% by weight, from 10% to 40% by weight, from 15% to 40% by weight, from 20% to 40% by weight, or from 25% to 40% by weight, based on a total weight of the capture solution.

32. The method of any of claims 1-31, wherein the capture solution further comprises a surfactant.

33. The method of any of claims 1-32, wherein the capture solution comprises an aqueous solution.

34. The method of any of claims 1-33. wherein the gas stream comprises one or more gases chosen from a flue gas, a natural gas, a hydrogen gas, and a synthesis gas.

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