Gas separation cell with proton-based charge equalization

Abstract

The invention relates to an electrochemical gas separation cell (10) for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture, said separation cell having an adsorption electrode (20) comprising at least one electrochemically active material (21) for the reversible electrochemical adsorption of the Lewis acid, a counter electrode (30), and a separator (40) between the adsorption electrode (20) and the counter electrode (30). The aim of the invention is to provide a novel type of gas separation cell, in particular one which can be used for an electrochemical (potential)-swing adsorption process or an electro-swing adsorption (ESA) process. This is achieved in that the cell (10) has a proton-based charge equalization (H+) between the adsorption electrode (20) and the counter electrode (30). The invention also relates to such a gas separation system and to a method for operating same.

Description

[0001] Description

[0002] title

[0003] The present invention relates to an electrochemical gas separation cell for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, a gas separation system and an operating method therefor.

[0004] State of the art

[0005] Carbon dioxide is an electrophilic electron pair acceptor and is therefore a Lewis acid.

[0006] The separation of carbon dioxide from process gas streams or atmospheric air is also called carbon capture.

[0007] In the scientific publication Energy Environ. Sci., 2019, 12, 3530, Voskian and Hatton describe a gas separation cell for carbon dioxide capture that can be operated using electrochemical (potential) swing adsorption or electro(chemical) swing adsorption (ESA). The gas separation cell features an adsorption electrode based on polyanthraquinone-functionalized carbon nanotubes (PAQ-CNT) and a counter electrode based on polyvinyl ferrocene-functionalized carbon nanotubes (PVFc-CNT). Carbon dioxide is bound to the adsorption electrode by reacting with electrons. The necessary electrical charge equalization takes place via the counter electrode based on polyvinyl ferrocene-functionalized carbon nanotubes, which supplies electrons from the ferrocene.Charge equalization between the adsorption electrode and the counter electrode occurs via the ion mobility of an ionic liquid impregnated in both electrodes. A separator in the form of a porous membrane made of an insulating material impregnated with an ionic liquid is arranged between the electrodes. This separator, on the one hand, separates the electron conduction between the two electrode compartments and, at the same time, connects the two electrode compartments in an ion-conducting manner via diffusion of the ionic liquid through its pores.

[0008] The document US 2022 / 0339579 A1 describes a process for the electrochemical deposition of a gaseous Lewis acid from a fluid mixture containing the Lewis acid.

[0009] Disclosure of the invention

[0010] The present invention relates to an electrochemical gas deposition cell for the, in particular electrochemical, deposition of a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture, in particular a gas mixture, containing the Lewis acid.

[0011] A Lewis acid can be understood in particular as an electrophilic electron pair acceptor, i.e. a compound to which an electron pair of an electron pair donor can be attached, for example in which the compound has an empty orbital that is energetically accessible to the electron pair of the electron pair donor.

[0012] The gas separation cell comprises an adsorption electrode with at least one electrochemically active material for the reversible electrochemical adsorption of the Lewis acid, for example carbon dioxide, a counter electrode and a separator arranged between the adsorption electrode and the counter electrode.

[0013] In particular, the cell has a proton-based charge balance or a charge balance based on protons between the adsorption electrode and the counter electrode. In particular, charges between the adsorption electrode and the counter electrode can be balanced, in particular substantially, for example mainly, or possibly exclusively, by protons.

[0014] This advantageously provides a novel gas deposition cell. Furthermore, proton-based charge balancing allows the use of different counterelectrodes and / or electrolytes, thereby achieving advantages over counterelectrodes conventionally used in such gas deposition cells, for example, those based on ferrocene-functionalized carbon nanotubes, and / or electrolytes, such as ionic liquids.

[0015] The gas separation cell can be used particularly advantageously for the separation of carbon dioxide (carbon capture) and / or for electrochemical (potential) swing adsorption, in particular potential swing adsorption, or electro(chemical) swing adsorption (ESA).

[0016] Overall, a new type of gas capture cell can be provided for the capture of a gaseous Lewis acid, in particular which can be used, for example, for carbon capture and / or electrochemical (potential) swing adsorption (ESA).

[0017] A proton-based charge balance can be achieved in particular by the counter electrode being designed for the reversible electrochemical generation of protons, in particular for the reversible electrochemical generation and absorption of protons, and / or the cell comprising at least one proton-conducting electrolyte.

[0018] Within the scope of one embodiment, the counterelectrode is therefore designed for the reversible electrochemical generation of protons, in particular for the reversible electrochemical generation and uptake of protons, and / or the cell comprises at least one proton-conducting electrolyte. By using an electrode for the reversible electrochemical generation of protons, in particular which can reversibly electrochemically generate protons (and in particular also uptake them again), as the counterelectrode, a comparatively cost-intensive ferrocene-based electrode conventionally used as a counterelectrode in such gas deposition cells can advantageously be replaced. In addition, electrodes for the reversible electrochemical generation of protons can advantageously increase the electrochemical efficiency and / or the service life of the cell.

[0019] The at least one proton-conducting electrolyte advantageously enables optimized charge balancing during electrochemical vapor deposition by means of proton transfer or proton-based charge balancing. The at least one proton-conducting electrolyte can advantageously assume the function of an ionic liquid conventionally used in such vapor deposition cells and, for example, can be designed more cost-effectively than conventionally very expensive ionic liquids.

[0020] In another embodiment, the counter electrode is designed for the reversible electrochemical splitting of hydrogen into protons. Either hydrogen (H2) or a hydrogen storage medium, such as ammonia (NH3) and / or a liquid organic hydrogen carrier (LOHC), can be used as the proton source. The proton source can be gaseous, such as hydrogen and / or ammonia, or liquid, such as a liquid organic hydrogen carrier.

[0021] In a special embodiment, the counter electrode is a hydrogen electrode. This advantageously optimizes efficiency.

[0022] In another specific embodiment, however, the counter electrode is designed for the reversible electrochemical splitting of a hydrogen storage medium, in particular to hydrogen, and in particular to generate protons. The hydrogen storage medium can be, for example, ammonia and / or a liquid organic hydrogen carrier. This advantageously simplifies the cell design and / or increases safety.

[0023] In a further embodiment, the counter electrode comprises at least one electrochemically active catalyst for hydrogen splitting or hydrogen oxidation. For example, the counter electrode can comprise at least one noble metal catalyst, for example, a platinum-carbon catalyst (Pt / C).

[0024] The counter electrode can, in particular, be porous. In particular, the counter electrode can be open-pored. In particular, the counter electrode can have a sufficiently high porosity for gas and / or liquid transport.

[0025] In another embodiment, the counter electrode has a gas-tight, particularly hydrogen-tight, enclosure. This allows hydrogen to be trapped in the area of ​​the counter electrode.

[0026] In a further embodiment, the counter electrode and / or the gas-tight enclosure of the counter electrode is connectable or connected to a reservoir for storing hydrogen and / or a hydrogen storage medium, for example, ammonia and / or at least one liquid organic hydrogen carrier. Thus, in the event of any hydrogen slippage that may occur, a proton source can be replenished from the reservoir.

[0027] In a further embodiment, the at least one proton-conducting electrolyte comprises at least one proton-conducting solid electrolyte. In particular, the at least one proton-conducting electrolyte can be at least one proton-conducting solid electrolyte.

[0028] The proton-conducting solid electrolyte can advantageously assume the function of an ionic liquid conventionally used in such gas separation cells and, due to its solid (and thus immobile) nature, offers several advantages over liquid ionic liquids: Firstly, the proton-conducting solid electrolyte can simplify cell design, for example, by eliminating the need for liquid encapsulation measures, and / or avoid liquid-related disadvantages, such as a loss of cell function due to liquid loss, for example, in the event of liquid leakage due to mechanical damage and / or liquid discharge through the gas flow. Secondly, the proton-conducting solid electrolyte can increase the robustness of the cell, for example, against mechanical damage and / or quality deviations.In addition, proton-conducting solid electrolytes can be more cost-effective than ionic liquids.

[0029] Within the scope of a further embodiment, the at least one proton-conducting electrolyte, in particular a solid electrolyte, comprises or is at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer (PFSA). Thus, the proton-conducting electrolyte, in particular a solid electrolyte, can be realized in a simple and—compared to very expensive ionic liquids—cost-effective manner.

[0030] In a further embodiment, the adsorption electrode and / or the separator and / or the counterelectrode comprises at least one proton-conducting electrolyte, in particular a solid electrolyte. In particular, the adsorption electrode and / or the separator and / or the counterelectrode can comprise at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer. In principle, the proton-conducting electrolyte, in particular a solid electrolyte, or the sulfonic acid ionomer can be advantageously used in just one of these components, in two of these components, or in all of these components.

[0031] Within the scope of one embodiment of this embodiment, the counterelectrode comprises at least one proton-conducting electrolyte, in particular a solid electrolyte. In particular, the counterelectrode can comprise at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer. Thus, charge balance can be improved by the counterelectrode. The counterelectrode can, in particular, be designed such that the at least one electrochemically active catalyst, the at least one proton-conducting electrolyte, in particular a solid electrolyte, for example the at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer, and hydrogen and / or a / the hydrogen storage medium form three-phase boundaries.

[0032] Within the scope of another additional or alternative embodiment of this embodiment, the adsorption electrode comprises at least one proton-conducting electrolyte, in particular a solid electrolyte. In particular, the counterelectrode can comprise at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer. Thus, charge balance can be improved by the adsorption electrode. The adsorption electrode can, in particular, be designed such that the at least one electrochemically active material, the at least one proton-conducting electrolyte, in particular a solid electrolyte, for example the at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer, and the fluid mixture, in particular a gas mixture, or the Lewis acid to be deposited, for example carbon dioxide, form three-phase boundaries.

[0033] In a further additional or alternative embodiment of this embodiment, the separator comprises at least one proton-conducting electrolyte, in particular a solid electrolyte. In particular, the separator can comprise or be formed from at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer. Thus, charge balancing can be improved by the separator.

[0034] In a specific embodiment of this embodiment, the adsorption electrode, the separator, and the counter electrode comprise at least one proton-conducting electrolyte, in particular a solid electrolyte, for example at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer. This allows charge balance to be optimized throughout the entire cell.

[0035] The separator can in particular be proton-conducting and electrically insulating.

[0036] The separator can thus electrically separate the adsorption electrode from the counter electrode and at the same time, through its proton-conducting properties, connect the adsorption electrode and the counter electrode in a proton-conducting manner.

[0037] In another embodiment, the separator is designed to be gas-tight and / or liquid-tight. This allows the separator to spatially separate the adsorption electrode from the counter electrode.

[0038] In a further embodiment, the separator is formed from at least one proton-conducting electrolyte, in particular a solid electrolyte, for example from at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer. This can be particularly advantageous.

[0039] In a further embodiment, the at least one electrochemically active material of the adsorption electrode is capable of binding and / or adsorbing the Lewis acid, for example, carbon dioxide, in at least one reduced state and releasing it again into an oxidized state through oxidation. Charges formed during the binding and / or adsorption of the Lewis acid can be balanced, in particular, by protons. This has proven particularly advantageous.

[0040] In a further embodiment, the at least one electrochemically active material of the adsorption electrode comprises or is at least one quinone-functionalized carbon material. For example, the at least one electrochemically active material of the adsorption electrode can comprise or be at least one para-quinone-functionalized carbon material and / or at least one ortho-quinone-functionalized carbon material. The quinone can, in particular, be a polyquinone and / or polymerized and / or polymer-bound.For example, the at least one electrochemically active material of the adsorption electrode can comprise or be at least one poly- and / or para-quinone-functionalized carbon material, in particular at least one poly- and / or para-anthraquinone-functionalized carbon material, for example at least one polyanthraquinone-functionalized carbon material, for example polyanthraquinone-functionalized carbon nanotubes (PAQ-CNT). The adsorption electrode can, in particular, be porous. In particular, the adsorption electrode can be open-pored. In this case, the adsorption electrode can, in particular, have a porosity sufficiently high for gas transport.

[0041] In a further embodiment, the Lewis acid, in particular a gaseous one, is carbon dioxide (CO2), carbonyl sulfide (COS), a sulfur oxide, such as sulfur dioxide (SO2) or sulfur trioxide (SO3), a sulfuric acid ester, for example with the general chemical formula R2SO4, for example dimethyl sulfate, a nitrogen oxide, such as nitrogen dioxide (NO2) or nitrogen trioxide (NO3), a phosphoric acid ester, for example with the general chemical formula: R3PO4, for example trimethyl phosphate, a sulfide, for example with the general chemical formula R2S, a carboxylic acid ester, for example with the general chemical formula: RCOOR', such as methyl formate or methyl acrylate, an aldehyde, for example with the general chemical formula: RCHO, such as formaldehyde or acrolein, a ketone, for example with the general chemical formula: R'2CO, such as acetone, an isocyanate, for example with the general chemical formula: R'NCO,such as methyl isocyanate, an isothiocyanate, for example with the general chemical formula: R'NCS, a borane, for example with the general chemical formula: BR"3, such as trimethylborane, or a borate, for example with the general chemical formula: R' sBOs, such as trimethyl borate, or a combination thereof. R, in particular each R independently of one another, can represent a hydrogen atom, an alkyl group, in particular having 1 to 12 carbon atoms, a cycloalkyl group, in particular having 3 to 12 carbon atoms, a heterocycloalkyl group, in particular having 1 to 12 carbon atoms, an acryloyl group, in particular having 6 to 20 carbon atoms, or a heteroaryl group, in particular having 1 to 12 carbon atoms. R', in particular each R' independently of one another, can represent an alkyl group, in particular having 1 to 12 carbon atoms, a cycloalkyl group, in particular having 3 to 12 carbon atoms, a heterocycloalkyl group,in particular having 1 to 12 carbon atoms, an aryl group, in particular having 6 to 20 carbon atoms, or a heteroaryl group, in particular having 1 to 12 carbon atoms. R", in particular each R", independently of one another, can represent a hydrogen atom, a halogen atom, an alkyl group, in particular having 1 to 12 carbon atoms, a cycloalkyl group, in particular having 3 to 12 carbon atoms, a heterocycloalkyl group, in particular having 1 to 12 carbon atoms, an aryl group, in particular having 6 to 20 carbon atoms, or a heteroaryl group, in particular having 1 to 12 carbon atoms.

[0042] Within the scope of one embodiment of this embodiment, the Lewis acid, in particular gaseous, is carbon dioxide (CO2), carbonyl sulfide (COS), sulfur dioxide (SO2), sulfur trioxide (SO3), nitrogen dioxide (NO2) or nitrogen trioxide (NO3) or a combination thereof.

[0043] In a preferred embodiment of this method, the Lewis acid, particularly in gaseous form, is carbon dioxide (CO2). The gas separation cell can be used particularly advantageously for carbon capture.

[0044] Within the scope of a further embodiment, the gas separation cell is designed for the separation of carbon dioxide and / or the adsorption electrode is designed for the reversible electrochemical adsorption of carbon dioxide and / or the at least one electrochemically active material of the adsorption electrode is capable of binding and / or adsorbing carbon dioxide in at least one reduced state and releasing it again by oxidation into an oxidized state, in particular wherein charges formed during the binding and / or adsorption of carbon dioxide can be balanced by protons, and / or the at least one electrochemically active material of the adsorption electrode has carboxylic acid groups in at least one reduced, carbon dioxide-binding state.

[0045] The proton-conducting electrolyte, in particular solid electrolyte, and / or the carboxylic acid groups formed in the reduced state of the electrochemically active material of the adsorption electrode can be detected, for example, by chemical analysis methods.

[0046] With regard to further technical features and advantages of the inventive

[0047] Gas separation cell, explicit reference is hereby made to the explanations in connection with the gas separation system according to the invention and the operating method according to the invention as well as to the figure and the figure description.

[0048] A further subject matter of the invention is an electrochemical gas separation system for the, in particular electrochemical, separation of a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture, which comprises gas separation cells according to the invention, for example a plurality of gas separation cells according to the invention.

[0049] With regard to further technical features and advantages of the gas separation system according to the invention, reference is hereby explicitly made to the explanations in connection with the gas separation cell according to the invention and the operating method according to the invention as well as to the figure and the figure description.

[0050] Furthermore, the invention relates to a method for operating a gas separation cell according to the invention and / or a gas separation system according to the invention for the, in particular electrochemical, separation of a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture.

[0051] In the process, the gas separation cell or cells are operated in particular by means of electrochemical (potential) swing adsorption, in particular potential swing adsorption, or electro(chemical) swing adsorption (ESA).

[0052] Within the scope of one embodiment, in an adsorption operation of the gas separation cell, the fluid mixture containing the Lewis acid, in particular gas mixture, is passed over and / or through the adsorption electrode and a potential (or a voltage) is set between the adsorption electrode and the counter electrode of the cell in such a way that the at least one electrochemically active material of the adsorption electrode is reduced by absorbing electrons, by binding and / or adsorbing the Lewis acid and by forming charges, in particular negative ones, and the charges, in particular negative ones, are balanced by protons generated by the counter electrode and / or conducted by the at least one proton-conducting electrolyte, in particular solid electrolyte.

[0053] The gas separation cell can, for example, be operated in adsorption mode up to a certain saturation, for example up to a complete saturation, of the at least one electrochemically active material of the adsorption electrode with the Lewis acid.

[0054] After reaching the certain saturation of the at least one electrochemically active material of the adsorption electrode with the Lewis acid, the gas separation cell can then be switched to and / or operated in a gas release mode.

[0055] Within the scope of a further embodiment, in a / the gas release operation of the gas separation cell, the potential set between the adsorption electrode and the counter electrode of the cell (or the voltage applied between the adsorption electrode and the counter electrode of the cell) is reversed or reversed, in particular compared to the adsorption operation, wherein the at least one electrochemically active material of the adsorption electrode is oxidized with the release of electrons, with the release of gaseous Lewis acid, in particular with charge neutralization, and with the release of protons, and the released protons are conducted through the at least one proton-conducting electrolyte, in particular solid electrolyte, and / or to the counter electrode and / or from the counter electrode, in particular into hydrogen and / or into a hydrogen storage medium, for example ammonia and / or at least one liquid organic hydrogen carrier,be converted.,

[0056] The released gaseous Lewis acid, in particular carbon dioxide, can be separated or separated. The gas separation cell can be operated in gas release mode, for example, up to a certain degree of desorption, for example, up to complete desorption, of the at least one electrochemically active material of the adsorption electrode by the Lewis acid.

[0057] After reaching the specific degree of desorption of the at least one electrochemically active material of the adsorption electrode, the gas separation cell can be switched back to adsorption mode and / or operated in it.

[0058] Part of the electrical energy used to apply voltage in adsorption operation can, if necessary, be recovered in gas release operation.

[0059] The operating process can be carried out in cycles, in particular, with each cycle comprising at least one adsorption phase and one gas release phase. The Lewis acid can be separated, in particular, by repeatedly running through these cycles.

[0060] With regard to further technical features and advantages of the operating method according to the invention, reference is hereby explicitly made to the explanations in connection with the gas separation cell according to the invention and the gas separation system according to the invention as well as to the figure and the figure description.

[0061] drawing

[0062] Further advantages and advantageous embodiments of the inventive objects are illustrated by the drawings and explained in the following description. It should be noted that the drawings are for descriptive purposes only and are not intended to limit the invention in any way. It shows

[0063] Fig. 1 shows a schematic cross-section through an embodiment of an electrochemical gas deposition cell according to the invention. Figure 1 shows that the gas deposition cell 10 for separating a gaseous Lewis acid, for example carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture, in the embodiment shown therein comprises an adsorption electrode 20 with an electrochemically active material 21 for the reversible electrochemical adsorption of the Lewis acid, for example carbon dioxide, a counter electrode 30, and a separator 40 arranged between the adsorption electrode 20 and the counter electrode 30. The IT double arrow in Figure 1 illustrates that the cell 10 has a proton-based charge equalization IT between the adsorption electrode 20 and the counter electrode 30. For this purpose, the counter electrode 30 in the cell 10 shown is for the reversible electrochemical generation of protons H+ and the adsorption electrode 20, the counter electrode 30 and the separator 40 each comprise a proton-conducting electrolyte 22,PFE; 32,PFE; 40,PFE.

[0064] The proton-conducting electrolyte 22,PFE;32,PFE;40,PFE of the adsorption electrode 20, the counter electrode 30 and the separator 40 can in particular be a proton-conducting solid electrolyte, for example a proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer.

[0065] The reversible electrochemical generation of protons H + designed counter electrode 30 can in particular comprise an electrochemically active catalyst 31 for hydrogen splitting, for example a noble metal catalyst, for example a platinum-carbon catalyst (Pt / C), and in particular for the reversible electrochemical splitting of hydrogen into protons H +and / or for the reversible electrochemical splitting of a hydrogen storage medium, for example, ammonia and / or at least one liquid organic hydrogen carrier. Figure 1 illustrates that the counter electrode 30 has a gas-tight enclosure 33. The counter electrode 30 and / or the gas-tight enclosure 33 of the counter electrode 30 can optionally be connectable or connected to a reservoir for storing hydrogen and / or a hydrogen storage medium, for example, ammonia and / or a liquid organic hydrogen carrier (not shown).Figure 1 indicates that the counter electrode 30 can in particular be designed such that the electrochemically active catalyst 31, the proton-conducting electrolyte, in particular solid electrolyte, 32, PFE, and hydrogen and / or a hydrogen storage medium form three-phase boundaries (not explicitly shown) in free areas and / or spaces of the counter electrode 30.

[0066] Furthermore, Figure 1 indicates that the adsorption electrode 20 can be designed in particular such that the at least one electrochemically active material 21, the proton-conducting electrolyte, in particular solid electrolyte, 21, PFE, and the fluid mixture, in particular the gas mixture, or the Lewis acid to be deposited, for example carbon dioxide, form three-phase boundaries (not explicitly shown) in free areas and / or spaces of the adsorption electrode 20.

[0067] The separator 40 can be formed in particular from the proton-conducting electrolyte, in particular solid electrolyte, 40,PFE, in particular gas-tight and / or liquid-tight.

[0068] The electrochemically active material 21 of the adsorption electrode 20 can, in particular in at least one reduced state, be capable of binding and / or adsorbing the Lewis acid, in particular carbon dioxide, and releasing it again into an oxidized state through oxidation. Charges formed during the binding and / or adsorption of the Lewis acid can be balanced by protons IT. For example, the electrochemically active material 21 of the adsorption electrode 20 can comprise or be a quinone-functionalized, in particular poly- and / or para-anthraquinone-functionalized, carbon material, for example, polyanthraquinone-functionalized carbon nanotubes (PAQ-CNT).

[0069] The gas adsorption cell 10 shown in Figure 1 can be operated by means of electrochemical (potential) alternating adsorption, for example in two, in particular alternating, phases, namely in an adsorption mode and in a gas release mode.In adsorption operation, the Lewis acid, for example carbon dioxide, for example in the form of a fluid mixture, in particular a gas mixture, with a high carbon dioxide content, can be passed in particular over and / or through the adsorption electrode 20, wherein, for example by a voltage source 50, a potential is set between the adsorption electrode 20 and the counter electrode 30 of the cell 10 such that the at least one electrochemically active material 21 of the adsorption electrode 20 is reduced by absorbing electrons, by binding and / or adsorbing the Lewis acid and by forming charges, in particular negative ones, and the charges, in particular negative ones, are balanced by protons (IT) generated by the counter electrode 30 and / or conducted through the at least one proton-conducting electrolyte, in particular solid electrolyte, 22,PFE;32,PFE;40,PFE.

[0070] In adsorption operation for adsorbing the Lewis acid carbon dioxide (CO2), the partial reaction can be carried out, particularly at the adsorption electrode 20

[0071] A + 2 CO2 + 2 H + + 2 e A(-COO H + )2, where A stands for quinone, for example anthraquinone, for example polyanthraquinone (PAQ), of the electrochemically active material 21 of the adsorption electrode 20, and at the counter electrode 30 the partial reaction

[0072] H22 H + + 2 e- expire.

[0073] The electrochemically active material 21 (A) of the adsorption electrode 20 can be reduced by absorbing electrons (e), by binding and / or adsorbing the Lewis acid carbon dioxide (CO2), and by forming negative charges, particularly in the form of carboxylate groups (-COO). The negative charges, particularly of the carboxylate groups (-COO), can be balanced by protons (IT) generated by the counter electrode 30 through the splitting of hydrogen (H2) and / or conducted through the proton-conducting solid electrolyte 22,PFE;32,PFE;40,PFE, forming carboxylic acid groups (-COOH). Thus, the electrochemically active material 21 of the adsorption electrode 20 can have carboxylic acid groups (-COOH) in the reduced, carbon dioxide-binding state.In adsorption operation, the Lewis acid carbon dioxide (CO2) can thus be adsorbed from the fluid mixture, in particular gas mixture, passed over and / or through the adsorption electrode 20 and its carbon dioxide content can thereby be reduced, so that the fluid mixture, in particular gas mixture, after flowing over and / or through the adsorption electrode 20, can have a reduced carbon dioxide content or can possibly even be substantially carbon dioxide-free.

[0074] In gas release mode, the potential set at the adsorption electrode 20 and the counter electrode 30 of the cell 10 can be reversed, particularly compared to adsorption mode. This also reverses the reaction direction.

[0075] In gas release mode, the partial reaction can be carried out with the release of the gaseous Lewis acid carbon dioxide (CO2), particularly at the adsorption electrode 20

[0076] A(-COO H + )2A + 2 CO2 + 2 H + + 2 e , where A stands for quinone, for example anthraquinone, for example polyanthraquinone (PAQ), of the electrochemically active material 21 of the adsorption electrode 20, and at the counter electrode 30 the partial reaction:

[0077] 2 H + + 2 e- H2 expire.

[0078] The electrochemically active material 21 of the adsorption electrode 20 can be oxidized by releasing electrons (e ), in particular which migrate via the circuit to the counter electrode (30), releasing the gaseous Lewis acid carbon dioxide (CO2), and releasing protons (IT). The released protons (IT) can be conducted through the proton-conducting solid electrolyte 22,PFE;32,PFE;40,PFE and / or to the counter electrode 30 and / or converted by the counter electrode 30 to hydrogen (H2) and / or into a hydrogen storage medium, for example ammonia and / or a liquid organic hydrogen carrier. Concentrated gaseous Lewis acid can be released in the form of concentrated gaseous carbon dioxide (CO2), which can then be separated.

[0079] In this case, an adsorption phase and a gas release phase can, in particular, jointly form a cycle. The separation of the Lewis acid, especially carbon dioxide, can be achieved, for example, by repeatedly running through these cycles.

Claims

Claims 1 . Electrochemical gas separation cell (10) for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture, comprising - an adsorption electrode (20) with at least one electrochemically active material (21) for the reversible electrochemical adsorption of the Lewis acid, - a counter electrode (30) and - a separator (40) arranged between the adsorption electrode (20) and the counter electrode (30), wherein the cell (10) has a proton-based charge balance (IT) between the adsorption electrode (20) and the counter electrode (30).

2. Gas deposition cell (10) according to claim 1, wherein the counter electrode (30) is designed for the reversible electrochemical generation of protons (IT) and / or wherein the cell (10) comprises at least one proton-conducting electrolyte (PFE).

3. Gas deposition cell (10) according to claim 1 or 2, wherein the counter electrode (30) is used for the reversible electrochemical splitting of hydrogen into protons (H + ), in particular wherein the counter electrode (30) is a hydrogen electrode.

4. Gas deposition cell (10) according to one of claims 1 to 3, wherein the counter electrode (30) is designed for the reversible electrochemical splitting of a hydrogen storage medium, in particular of ammonia and / or of at least one liquid organic hydrogen carrier.

5. Gas deposition cell (10) according to one of claims 1 to 4, wherein the counter electrode (30) has at least one electrochemically active catalyst (31), in particular a noble metal catalyst, in particular a platinum-carbon catalyst, for hydrogen splitting.

6. Gas deposition cell (10) according to one of claims 1 to 5, wherein the counter electrode (30) has a gas-tight enclosure (33), in particular wherein the counter electrode (30) and / or the gas-tight enclosure (33) of the counter electrode (30) is connectable or connected to a storage container for storing hydrogen and / or a hydrogen storage medium, in particular ammonia and / or at least one liquid organic hydrogen carrier.

7. Gas deposition cell (10) according to one of claims 2 to 6, wherein the at least one proton-conducting electrolyte (PFE) comprises or is at least one proton-conducting solid electrolyte (PFE).

8. Gas deposition cell (10) according to one of claims 2 to 7, wherein the at least one proton-conducting electrolyte (PFE), in particular solid electrolyte, comprises or is at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer.

9. Gas deposition cell (10) according to one of claims 2 to 8, wherein the adsorption electrode (20) and / or the separator (40) and / or the counter electrode (30) comprises at least one proton-conducting electrolyte (PFE), in particular solid electrolyte, in particular at least one proton-conducting, fluorinated, in particular perfluorinated, sulfonic acid ionomer.

10. Gas deposition cell (10) according to one of claims 1 to 9, wherein the separator (40) is formed from at least one proton-conducting electrolyte (PFE), in particular solid electrolyte, in particular from at least one proton-conducting, fluorinated sulfonic acid ionomer, and / or wherein the separator (40) is gas-tight and / or liquid-tight.

11. Gas separation cell (10) according to one of claims 1 to 10, wherein the at least one electrochemically active material (21) of the adsorption electrode (20) is capable of binding and / or adsorbing the Lewis acid, in particular carbon dioxide, in at least one reduced state and of releasing it again into an oxidized state by oxidation, wherein charges formed during the binding and / or adsorption of the Lewis acid can be balanced by protons (IT).

12. Gas deposition cell (10) according to one of claims 1 to 11, wherein the at least one electrochemically active material (21) of the adsorption electrode (20) comprises or is at least one quinone-functionalized carbon material.

13. Gas deposition cell (10) according to one of claims 1 to 12, wherein the Lewis acid is carbon dioxide, carbonyl sulfide, sulfur dioxide, sulfur trioxide, a sulfuric acid ester, nitrogen dioxide, nitrogen trioxide, a phosphoric acid ester, a sulfide, a carboxylic acid ester, an aldehyde, a ketone, an isocyanate, an isothiocyanate, a borane or a borate or a combination thereof, in particular wherein the Lewis acid is carbon dioxide.

14. Gas separation cell (10) according to one of claims 1 to 13, wherein the gas separation cell (10) is designed for the separation of carbon dioxide, and / or wherein the adsorption electrode (20) is designed for the reversible electrochemical adsorption of carbon dioxide, and / or wherein the at least one electrochemically active material (21) of the adsorption electrode (20) is capable, in at least one reduced state, of binding and / or adsorbing carbon dioxide and releasing it again by oxidation into an oxidized state, in particular wherein charges formed during the binding and / or adsorption of carbon dioxide can be balanced by protons (IT), and / or wherein the at least one electrochemically active material (21) of the adsorption electrode (20) has carboxylic acid groups in at least one reduced, carbon dioxide-binding state.

15. An electrochemical gas separation system for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture, comprising electrochemical gas separation cells (10) according to one of claims 1 to 14.

16. A method for operating a gas separation cell (10) according to one of claims 1 to 14 and / or a gas separation system according to claim 15 for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular gas mixture, in which the gas separation cell (10) or the gas separation cells are operated by means of electrochemical alternating adsorption, in particular potential swing adsorption, in particular wherein in an adsorption operation of the gas separation cell (10) the fluid mixture containing the Lewis acid, in particular gas mixture, is passed over and / or through the adsorption electrode (20) and a potential is set between the adsorption electrode (20) and the counter electrode (30) of the cell in such a way that the at least one electrochemically active material (21) of the adsorption electrode (20) absorbs electrons,by binding and / or adsorbing the Lewis acid and forming, in particular, negative charges, and the charges are balanced by protons (IT) generated by the counter electrode (30) and / or conducted by the at least one proton-conducting electrolyte (FPE), in particular solid electrolyte, and / or wherein in a gas release operation of the gas separation cell (10), the potential set between the adsorption electrode (20) and the counter electrode (30) of the cell (10) is reversed, in particular compared to the adsorption operation, wherein the at least one electrochemically active material (21) of the adsorption electrode, (20) is oxidized with the release of electrons, with the release of gaseous Lewis acid, in particular carbon dioxide, and with the release of protons (IT), and the released protons (IT) are conducted through the at least one proton-conducting electrolyte (FPE), in particular solid electrolyte, and / or to the counter electrode (30) and / or are converted by the counter electrode (30), in particular into hydrogen and / or into a hydrogen storage medium, in particular wherein the released gaseous Lewis acid, in particular carbon dioxide, is separated or separated.

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