Gas separation cell with supply-side membrane

Abstract

The present invention relates to an electrochemical gas separation cell (10,10') for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture, in particular a gas mixture, containing the Lewis acid, which comprises an adsorption electrode (20,20') with at least one electrochemically active material for the reversible electrochemical adsorption of the Lewis acid, a counter electrode (30,30') and a separator (40,40') arranged between the adsorption electrode (20,20') and the counter electrode (30,30'). In order to provide a new type of gas separation cell (10,10') for the separation of a gaseous Lewis acid, in particular which can be used for electrochemical (potential) swing adsorption or electro-swing adsorption (ESA), a membrane (60,60') is arranged between the adsorption electrode (20,20') and a feed chamber (50) for supplying the fluid mixture.Furthermore, the invention relates to such a gas separation system and an operating method for it.

Description

[0001] 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 therein and an operating method therefor. State of the art

[0002] Carbon dioxide is an electrophilic electron pair acceptor and is therefore a Lewis acid.

[0003] The separation of carbon dioxide from process gas streams or atmospheric air is also known as carbon capture.

[0004] Hatton et al. describe a gas capture cell for carbon dioxide capture in their scientific publication Energy Environ. Sci., 2019, 12, 3530. This cell can be operated using electrochemical swing adsorption (ESA). The gas capture cell comprises a gas capture electrode based on para-anthraquinone-functionalized carbon nanotubes (PAQ-CNTs) and a counter electrode based on polyvinylene-ferrocene-functionalized carbon nanotubes (PVFc-CNTs). Carbon dioxide is captured at the gas capture electrode through a reaction with electrons. The necessary electrical charge balance is achieved via the counter electrode, which is based on polyvinylene-ferrocene-functionalized carbon nanotubes and supplies electrons from the ferrocene.Charge equalization between the adsorption electrode and the counter electrode occurs via the ion mobility of an ionic liquid with which both electrodes are impregnated. A separator in the form of a porous membrane made of an insulating material, impregnated with the ionic liquid, is positioned between the electrodes. This separator both isolates the electron conduction between the two electrode compartments and simultaneously connects them via diffusion of the ionic liquid through its pores, thus enabling ion conduction.

[0005] Document US 2022 / 0339579 A1 describes a method for the electrochemical deposition of a gaseous Lewis acid from a fluid mixture containing the Lewis acid. Disclosure of the invention

[0006] The present invention relates to an electrochemical gas separation cell for the, in particular electrochemical, separation of a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture, in particular a gas mixture, containing the Lewis acid.

[0007] 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.

[0008] 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, in particular with at least one electrochemically active material for charge balancing of the adsorption electrode, and a separator arranged between the adsorption electrode and the counter electrode.

[0009] In particular, a membrane is arranged between the adsorption electrode and a supply chamber for supplying the fluid mixture, in particular the gas mixture, in particular the Lewis acid, to the adsorption electrode.

[0010] Such a membrane advantageously makes it possible to equip and / or operate the cell with a gas separation chamber that is spatially separated from the supply chamber, in particular via which the gaseous Lewis acid can be discharged, in particular spatially separated from the fluid mixture, in particular gas mixture, for example raw gas.

[0011] This prevents the mixing of the fluid mixture, especially the gas mixture, for example raw gas, and the gaseous Lewis acid, which in particular has been separated. This makes it advantageously possible to reduce, at least to a tolerable level and possibly even to avoid, the evacuation and / or purging processes required to separate the gaseous Lewis acid from the raw gas in conventional gas separation cells with only a single chamber for supply and separation and / or removal, and thus to reduce the energy consumption of the cell.

[0012] The membrane also advantageously allows for at least a reduction, or even a complete elimination, of particle contamination of the adsorption electrode and / or the electrolyte for the cell's electrochemical reaction, which is typically an ionic liquid and therefore unavoidable in conventional gas separation cells. Furthermore, the membrane advantageously enables the feed chamber to be flushed with a suitable medium to remove any particles introduced into the feed chamber.

[0013] Furthermore, the membrane advantageously also allows, conversely, the contamination of the fluid mixture, in particular gas mixture, for example raw gas, with the electrolyte for the electrochemical reaction of the cell, for example an ionic liquid, or the carryover of the electrolyte by the fluid mixture or gas mixture flow, which is associated with electrolyte loss and thus also loss of function of the cell, to at least reduce or possibly even avoid.

[0014] Furthermore, the membrane advantageously prevents the electrolyte from flowing out of the cell for the electrochemical reaction, which advantageously allows the cell – in contrast to conventional gas separation cells, where gravity-induced electrolyte outflow is usually prevented by a special orientation and / or structure of the cell with respect to gravity, for example by a horizontal orientation of the cell planes – to be oriented and / or constructed differently, for example without considering the influence of gravity on this, for example with a vertical orientation of the cell planes, and thereby achieve advantageous effects.

[0015] The gas capture cell can be used particularly advantageously for carbon dioxide capture and / or for electrochemical swing adsorption (ESA).

[0016] Overall, this can provide a new type of gas capture cell for the capture of a gaseous Lewis acid, in particular one that can be used for the capture of, for example, carbon dioxide (carbon capture), and / or for electrochemical swing adsorption (ESA) and / or exhibits the advantages explained.

[0017] In one embodiment, the membrane is permeable to the Lewis acid in a liquid and / or electrolyte-soluble state under the operating conditions of the cell, and / or the membrane is impermeable to the Lewis acid in a gaseous state under the operating conditions of the cell.

[0018] The operating conditions of the cell can be understood to mean, in particular, the conditions under which the cell can be used and / or operated for gas separation. Specifically, the operating conditions may include certain pressures and / or pressure ranges and / or certain pressure differentials and / or pressure differential ranges during cell operation. If applicable, the operating conditions may also include other parameters, such as certain temperatures and / or temperature ranges and / or liquid and / or electrolyte levels, for example, the presence of liquid and / or electrolyte during cell operation (e.g., during impregnation), etc.

[0019] Under the operating conditions of the cell, the membrane can, for example, prevent the passage of gases or gaseous substances, such as the fluid mixture, such as the gas mixture, in particular the gaseous Lewis acid, and / or be impermeable to gases or gaseous substances, such as the fluid mixture, such as the gas mixture, in particular the Lewis acid in the gaseous state, and also to other gases, for example, be gas-impermeable.

[0020] In particular, under the cell's operating conditions, the membrane can be permeable to the Lewis acid in a liquid and / or electrolyte solution and impermeable to the Lewis acid in a gaseous state. Thus, under the cell's operating conditions, the membrane can also be described as a semipermeable and / or selective membrane, specifically permeable to the Lewis acid in a liquid and / or electrolyte solution and impermeable to the Lewis acid in a gaseous state.

[0021] For example, under the operating conditions of the cell, the membrane can be permeable to the Lewis acid in a liquid and / or electrolyte-soluble state and impermeable to the Lewis acid in the gaseous state - and, for example, also to other gaseous substances, such as those in the fluid mixture or the gas mixture.

[0022] In another embodiment, the membrane itself is porous, in particular open-pored.

[0023] In a further embodiment, the membrane is saturated with liquid and / or electrolyte under the operating conditions of the cell. In particular, the pores of the membrane can be filled and / or saturated with a liquid and / or an electrolyte.

[0024] In a further embodiment, the membrane is a porous, liquid- and / or electrolyte-impregnated membrane under the operating conditions of the cell. Advantageously, such a membrane allows the Lewis acid to diffuse through in a state dissolved in the liquid and / or electrolyte, while simultaneously preventing the passage of gaseous substances, for example, of the fluid mixture, particularly the gas mixture, such as gaseous Lewis acid. Specifically, the membrane can be permeable to the Lewis acid in a liquid- and / or electrolyte-soluble state and impermeable to gaseous substances, for example, of the fluid mixture, particularly the gas mixture, such as gaseous Lewis acid, and especially also to other gaseous components of the fluid mixture, particularly the gas mixture.

[0025] The membrane can be designed in such a way, for example with narrow pores, that under the operating conditions of the cell, for example also under the pressures and / or pressure differences expected and / or occurring under the operating conditions of the cell, liquid and / or electrolyte is retained or held in the pores of the membrane, for example by capillary forces.

[0026] For example, the membrane can be designed to have a specific capillary inlet pressure that is greater than the pressures and / or pressure differences expected and / or occurring under the cell's operating conditions. Capillary inlet pressure is also used, for instance, in process engineering for dehumidifying filter cakes, where a certain gas pressure is required to at least partially dehumidify a liquid-saturated filter cake. No gas enters the filter cake if the capillary inlet pressure is not reached, as capillary forces retain the liquid within the filter cake.

[0027] For example, it is possible to equip the cell, for instance directly during its assembly or manufacture, with a porous, liquid- and / or electrolyte-impregnated membrane. This advantageously provides a cell with a membrane that is ready for immediate operation. In combination with a suitable membrane design featuring a sufficiently high capillary inlet pressure for the cell's operating conditions, a ready-to-use cell can thus be advantageously provided which, under the cell's operating conditions—particularly provided the capillary inlet pressure is not exceeded—is permeable to the Lewis acid in a liquid and / or electrolyte solution and impermeable to the Lewis acid in a gaseous state—and, for example, also to other gaseous substances, such as those in the fluid mixture or, in particular, the gas mixture.

[0028] However, it is also possible to initially equip the cell with only a porous membrane during its construction or manufacture, for example, a dry porous membrane. This dry porous membrane can initially be gas-permeable. Only later, for example, at a location designated for cell operation, can the initially dry porous membrane, and in particular its pores, be saturated with liquid and / or electrolyte.In combination with a suitable membrane design with a sufficiently high capillary inlet pressure for the cell's operating conditions, the cell can thus advantageously be made ready for operation only after its manufacture, for example after transport to a location intended for cell operation, for example by introducing liquid and / or electrolyte, and the originally dry and gas-permeable porous membrane is transformed into a liquid- and / or electrolyte-impregnated membrane, which is then, under the cell's operating conditions - in particular insofar as the capillary inlet pressure is not exceeded - permeable to the Lewis acid in a liquid- and / or electrolyte-soluble state and impermeable to the Lewis acid in the gaseous state - and, for example, also to other gaseous substances, for example of the fluid mixture, in particular the gas mixture - for example gas-impermeable.

[0029] In particular, the membrane can be impregnated with at least one liquid electrolyte and / or at least one ionic liquid. The at least one liquid electrolyte and / or the at least one ionic liquid can, for example, be at least partially similar to, or possibly identical with, an electrolyte used for the electrochemical reaction of the cell, for example in the adsorption electrode, such as an ionic liquid and / or liquid electrolyte. In particular, the porosity of the membrane can be set so fine that the capillary inlet pressure of the electrolyte used for the electrochemical reaction of the cell, for example in the adsorption electrode, is significantly higher than the expected pressure differences between the supply chamber and the gas separation chamber.

[0030] In a further embodiment, a gas separation chamber is formed on the side of the adsorption electrode facing away from the membrane. The gas separation chamber can, in particular, also be designed for the removal of gaseous Lewis acid. Specifically, the gas separation chamber can be designed to remove the gaseous Lewis acid, in particular spatially, separately from the fluid mixture, especially the gas mixture, for example, raw gas.

[0031] In another embodiment, the gas separation chamber is at least partially formed by means of the separator. For this purpose, the separator can be structured in particular.

[0032] In one embodiment of this design, gas separation channels are formed in the separator, in particular extending in a direction perpendicular to the plane of the separator, and especially through the separator. Thus, the gas separation chamber can extend from a side of the adsorption electrode facing the separator through the separator to the side of the counter electrode, and gaseous Lewis acid can be separated from the adsorption electrode through the separator, particularly on the counter electrode side, and especially discharged.

[0033] In another, alternative, or additional embodiment of this design, gas separation channels are formed in the separator, in particular those extending in a direction parallel to the plane of the separator. The gas separation channels of the separator can be formed, for example, on the outer surface of the separator facing the adsorption electrode and / or on the outer surface of the separator facing the counter electrode and / or in an internal region of the separator. For example, the gas separation channels of the separator can be labyrinthine. In the case of gas separation channels formed on the outer surface of the separator facing the adsorption electrode, gaseous Lewis acid can be separated and, in particular, discharged on the adsorption electrode side, thus eliminating the need for gas separation shafts.In the case of gas separation channels formed in an interior area of ​​the separator, gaseous Lewis acid can be separated and, in particular, removed through the separator, and, for example, the formation of gas separation shafts extending through the separator to the counter electrode can be dispensed with.

[0034] In another, alternative, or additional embodiment of this design, the separator has corrugations and / or a wave-like shape and / or a wave-like cross-section to at least partially form the gas separation chamber. For example, the separator can be corrugated sheet-like. The gas separation chamber can be at least partially formed by cavities on the adsorption electrode side and / or on the counter electrode side.

[0035] In a further embodiment, the gas separation chamber is at least partially formed by means of the counter electrode. For this purpose, the counter electrode can be structured.

[0036] In one embodiment of this system, gas separation channels are formed in the counter electrode, in particular extending in a direction perpendicular to the plane of the counter electrode, and especially through the counter electrode. The gas separation chamber can extend from a side of the adsorption electrode facing the separator, through the separator and through the counter electrode to the outside of the counter electrode, and gaseous Lewis acid can be separated from the adsorption electrode, through the separator and through the counter electrode, and especially from the outside, and particularly discharged.

[0037] In another, alternative, or additional embodiment of this design, gas separation channels are formed in the counter electrode, in particular extending in a direction parallel to the plane of the counter electrode. The gas separation channels of the counter electrode can be located, for example, on the side of the counter electrode facing the separator, on the outside of the counter electrode, and / or in an internal region of the counter electrode. For example, the gas separation channels of the counter electrode can be labyrinthine.

[0038] In a further, alternative, or additional embodiment, the gas separation chamber is at least partially formed by means of the adsorption electrode. For this purpose, the adsorption electrode can be structured. For example, gas separation channels can be formed in the adsorption electrode, extending in a direction parallel to the plane of the adsorption electrode. For example, the gas separation channels can be formed on the side of the adsorption electrode facing the separator. The gas separation channels of the adsorption electrode can, for example, be labyrinthine.

[0039] The at least one electrochemically active material of the adsorption electrode can be capable, in at least one reduced state, of binding and / or adsorbing the Lewis acid, for example, carbon dioxide, and releasing it again by oxidation to an oxidized state. Charges formed during the binding and / or adsorption of the Lewis acid can be balanced, in particular, by the counter electrode. For example, the at least one electrochemically active material of the adsorption electrode can comprise or be at least one para-anthraquinone-functionalized carbon material, for example, para-anthraquinone-functionalized carbon nanotubes (PAQ-CNTs).

[0040] In addition to at least one electrochemically active material, the adsorption electrode may in particular comprise at least one electrolyte, for example at least one liquid electrolyte and / or at least one ionic liquid.

[0041] As part of the training process, nucleation structures that promote gas bubble formation, such as boiling-stone-like structures, are introduced or formed in the adsorption electrode. This accelerates the deposition of the gaseous Lewis acid.

[0042] The electrochemically active material of the counter electrode can, for example, be capable of donating electrons by oxidizing to an oxidized state and accepting electrons by reducing the oxidized state, thereby enabling charge equalization between the two electrodes. For example, the electrochemically active material of the counter electrode can comprise ferrocene. Specifically, the electrochemically active material of the counter electrode can be a polymer-bound ferrocene, such as polyvinylene ferrocene.

[0043] The separator can be, in particular, ion-conducting and electrically insulating. Thus, the separator can electrically isolate the adsorption electrode from the counter electrode, or prevent electron conduction between the electrodes, and simultaneously connect the adsorption electrode and the counter electrode ionically through its ion-conducting property.

[0044] In a further embodiment, the gas separation cell has a horizontal or horizontal structure. The adsorption electrode and / or the separator and / or the counter electrode and / or the feed chamber and / or the membrane and / or the gas separation chamber, for example the gas separation channels, and / or the bipolar plate described in more detail later, can have a substantially horizontal or horizontal extent or form horizontal or horizontal planes, in particular planes that are substantially parallel to each other. The gas separation chamber, for example the gas separation channels, can be located and / or arranged, in particular, above the adsorption electrode and / or above the separator and / or above the counter electrode and / or below the bipolar plate described in more detail later.The deposition of gaseous Lewis acid can thus be facilitated and / or accelerated by the gas separation chamber. The supply can be located adjacent to and / or below the membrane. It can also optionally be located below the adsorption electrode and / or the separator and / or the counter electrode and / or adjacent to and / or above the bipolar plate, which will be described in more detail later.

[0045] As already explained, the membrane also enables other advantageous cell structures.

[0046] In another embodiment, the gas separation cell has a vertical or perpendicular structure. In this configuration, the adsorption electrode and / or the separator and / or the counter electrode and / or the feed chamber and / or the membrane and / or the gas separation chamber, for example, the gas separation channels, and / or the bipolar plate (described in more detail later) can have a substantially vertical or perpendicular extension or form vertical or perpendicular planes, particularly planes that are substantially parallel to each other. The gas separation chamber, for example, the gas separation channels, can be formed and / or arranged, in particular, laterally to the side of the adsorption electrode and / or to the side of the separator and / or to the side of the counter electrode and / or to the side of the bipolar plate (described in more detail later).The deposition of gaseous Lewis acid can also be facilitated and / or accelerated by the gas separation chamber, since the gaseous Lewis acid can escape upwards due to its vertical extension. The supply can be located, in particular, laterally to the membrane (and also laterally to the adsorption electrode and / or the separator and / or the counter electrode and / or the bipolar plate, which will be explained in more detail later).

[0047] In a further embodiment, the Lewis acid, particularly in its gaseous form, 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 acrylic, 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"3BO3, such as trimethylborate, or a combination thereof. R, in particular each R independently, can represent a hydrogen atom, an alkyl group, in particular with 1 to 12 carbon atoms, a cycloalkyl group, in particular with 3 to 12 carbon atoms, a heterocycloalkyl group, in particular with 1 to 12 carbon atoms, an aryl group, in particular with 6 to 20 carbon atoms, or a heteroaryl group, in particular with 1 to 12 carbon atoms. R', in particular each R' independently, can represent an alkyl group, in particular with 1 to 12 carbon atoms, a cycloalkyl group, in particular with 3 to 12 carbon atoms, a heterocycloalkyl group,in particular with 1 to 12 carbon atoms, an aryl group, in particular with 6 to 20 carbon atoms, or a heteroaryl group, in particular with 1 to 12 carbon atoms. R", in particular each R" independently, can represent a hydrogen atom, a halogen atom, an alkyl group, in particular with 1 to 12 carbon atoms, a cycloalkyl group, in particular with 3 to 12 carbon atoms, a heterocycloalkyl group, in particular with 1 to 12 carbon atoms, an aryl group, in particular with 6 to 20 carbon atoms, or a heteroaryl group, in particular with 1 to 12 carbon atoms.

[0048] In one embodiment of this design, 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.

[0049] In a preferred embodiment of this system, the Lewis acid, particularly in its gaseous form, is carbon dioxide (CO2). The gas capture cell can be used particularly advantageously for carbon dioxide capture.

[0050] In particular, the gas separation cell can be designed for the separation of carbon dioxide and / or the adsorption electrode can be designed for the reversible electrochemical adsorption of carbon dioxide and / or the at least one electrochemically active material of the adsorption electrode can be capable of binding and / or adsorbing carbon dioxide in at least one reduced state and releasing it again by oxidation to an oxidized state and / or the at least one electrochemically active material of the adsorption electrode can have carboxylic acid groups in at least one reduced, carbon dioxide-binding state.

[0051] With regard to further technical features and advantages of the gas separation cell according to the invention, 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 description of the figures.

[0052] Another object 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 at least two gas separation cells according to the invention, for example a plurality of gas separation cells according to the invention.

[0053] In a further embodiment, a bipolar plate is arranged between two adjacent gas separation cells (each), particularly for electrically conductive connection and / or for ionic insulating separation and / or for spatial separation of adjacent gas separation cells. In particular, a bipolar plate can be arranged between the membrane of one gas separation cell and the counter electrode of an adjacent gas separation cell (each).

[0054] In a further embodiment, the gas separation chamber and / or the feed chamber is at least partially formed by means of a bipolar plate. In particular, the gas separation chamber of a gas separation cell can be at least partially formed by means of a bipolar plate, which also forms at least part of the feed chamber of an adjacent cell, and / or – particularly conversely – the feed chamber of a gas separation cell can be at least partially formed by means of a bipolar plate, which also forms at least part of the gas separation chamber of an adjacent cell. For example, the gas separation chamber of one cell and the feed chamber of an adjacent cell can be formed by means of a (single) bipolar plate. For this purpose, the bipolar plate(s) can be structured.

[0055] In one embodiment of this design, the bipolar plate(s) have corrugations and / or a wave-like shape and / or a wave-like cross-section to at least partially form the gas separation chamber and / or feed chamber. For example, the bipolar plate(s) can be corrugated. The gas separation chamber and / or the feed chamber can be formed, in particular, by the corrugations and / or the wave-like shape and / or the wave-like cross-section of the bipolar plate. The gas separation chamber can be formed, at least partially, by cavities on the counter-electrode side, and the feed chamber, at least partially, by cavities on the adsorption electrode side.

[0056] In another, alternative, or additional embodiment of this design, gas deposition channels and / or supply channels are formed in the bipolar plate(s), in particular extending in a direction parallel to the plane of the bipolar plate. The gas deposition channels of the bipolar plate(s) can, for example, be located on the side of the bipolar plate(s) facing the counter electrode, and / or the supply channels on the side of the bipolar plate(s) facing the adsorption electrode. For example, the gas deposition channels and / or the supply channels of the bipolar plate(s) can be configured in a labyrinthine manner.

[0057] In a further embodiment, the gas separation chamber is at least partially formed by means of a gas-conducting, in particular gas-conducting and electrically conductive, intermediate layer between the counter electrode and the bipolar plate. This embodiment allows the bipolar plate(s) to be made flat. This advantageously reduces manufacturing costs. The intermediate layer between the counter electrode and the bipolar plate can, for example, be made of expanded metal, a metallic fabric, a metallic fleece, or in another porous and / or gas-conducting and, in particular, electrically conductive, i.e., electron-conducting, form.

[0058] In one embodiment of this design, the intermediate layer between the counter electrode and the bipolar plate is porous.

[0059] In another, alternative, or additional embodiment of this design, gas deposition channels are formed in the intermediate layer between the counter electrode and the bipolar plate, in particular those extending in a direction parallel to the plane of the intermediate layer. For example, the gas deposition channels of the intermediate layer between the counter electrode and the bipolar plate can be labyrinthine. For example, in the case of a flat bipolar plate, the gaseous Lewis acid can be collected, for example, in a metallic labyrinth, for instance, above the counter electrode.

[0060] In a further embodiment, the supply chamber is at least partially formed by means of a gas-conducting, in particular gas-conducting and electrically conductive, intermediate layer between the bipolar plate and the membrane. This embodiment makes it possible to design the bipolar plate(s) as a flat surface. The intermediate layer between the bipolar plate and the membrane can be, for example, expanded metal, a metallic fabric, a metallic fleece, or in another porous and / or gas-conducting and, in particular, electrically conductive, i.e., electron-conducting, form.

[0061] In one embodiment of this design, the intermediate layer between the bipolar plate and the membrane is porous.

[0062] In another, alternative, or additional embodiment of this design, supply channels are formed in the intermediate layer between the bipolar plate and the membrane, in particular those extending in a direction parallel to the plane of the intermediate layer. For example, the supply channels of the intermediate layer between the bipolar plate and the membrane can be labyrinthine.

[0063] In another embodiment, the gas separation cells are arranged in a stacked manner.

[0064] In one embodiment of this design, the gas separation cells are arranged in the form of a horizontal stack or a stack with horizontal planes.

[0065] In another preferred embodiment of this design, the gas separation cells are arranged in the form of a vertical stack or a stack with vertical planes. This allows the separation of the gaseous Lewis acid by the gas separation chamber to be promoted and / or accelerated, since the gaseous Lewis acid can escape through its vertical extent.

[0066] In another embodiment, the membrane is at least partially, and optionally completely, electrically conductive, i.e., electron-conducting. For example, the membrane can comprise electrically conductive particles. In this way, the adsorption electrode can be electrically connected to the bipolar plate via the membrane.

[0067] In another embodiment, the bipolar plate has contact points that penetrate the membrane. This allows the adsorption electrode to be electrically connected to the bipolar plate through the membrane.

[0068] In a further embodiment, the membrane has continuous recesses through which the bipolar plate extends partially to the adsorption electrode. These continuous recesses can be formed in the membrane before assembly or created during assembly by piercing the bipolar plate, for example, with points. The bipolar plate can, in particular, close and / or seal the recesses. For example, the grooves of the bipolar plate can extend partially through the recesses, thereby closing and / or sealing them, especially through high surface pressure. In this way, the adsorption electrode can be electrically connected to the bipolar plate through the recesses in the membrane.

[0069] In another embodiment, the adsorption electrode has, for example, secondary, metallic structures for electrically contacting the bipolar plate. In this way, the adsorption electrode can be electrically connected to the bipolar plate via these metallic structures.

[0070] The gas separation system and / or the gas separation cell according to the invention can be used, for example, to clean exhaust gas of Lewis acid, in particular carbon dioxide, especially from a ship or, for example, a locomotive or other vehicle with sufficient installation space for this purpose, or from a stationary plant, for example, a heating system and / or a fuel cell system and / or a generator and / or a heat engine and / or an industrial plant and / or a chemical plant, for example, in which carbon dioxide is produced as a by-product, for example, during the burning of lime in cement production (CaCO3 → CaO + CO2), and / or for carbon dioxide capture from air (DAC; English: Direct Air Capture).

[0071] With regard to further technical features and advantages of the gas separation system according to the invention, explicit reference is hereby 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.

[0072] Furthermore, the invention relates to a method for operating a gas separation cell 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, in particular a gas mixture, containing the Lewis acid.

[0073] In this process, the gas separation cell or gas separation cells are operated in particular by means of electrochemical (potential) swing adsorption or electro-swing adsorption (ESA).

[0074] In one embodiment, during adsorption operation of the gas separation cell(s), the fluid mixture, particularly a gas mixture, containing the Lewis acid is passed through the feed chamber over the membrane. The Lewis acid can dissolve, or become dissolved, particularly in the membrane, especially in the liquid and / or electrolyte of the membrane. In the liquid and / or electrolyte-soluble state, the Lewis acid can diffuse through the membrane to the adsorption electrode. During adsorption operation, a potential is established between the adsorption electrode and the counter electrode of the cell such that the at least one electrochemically active material of the adsorption electrode is reduced by accepting electrons and binding and / or adsorbing the Lewis acid, and the at least one electrochemically active material of the counter electrode is oxidized by releasing electrons.

[0075] The gas separation cell can, for example, be operated in adsorption mode up to a certain saturation, such as complete saturation, of the at least one electrochemically active material of the adsorption electrode with the Lewis acid.

[0076] After reaching the specified 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 gas release mode and / or operated.

[0077] In a further embodiment, in the gas release operation of the gas separation cell(s), 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), particularly in comparison to the adsorption operation, is reversed or polarized in such a way that the at least one electrochemically active material of the adsorption electrode is oxidized by releasing electrons and gaseous Lewis acid, in particular carbon dioxide, especially into the gas separation chamber, and the at least one electrochemically active material of the counter electrode is reduced by absorbing electrons.

[0078] The released gaseous Lewis acid, especially carbon dioxide, can be particularly captured or separated.

[0079] The gas separation cell can, for example, be operated in gas release mode 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.

[0080] Once the specified degree of desorption of at least one electrochemically active material of the adsorption electrode has been reached, the gas separation cell can be operated again in adsorption mode.

[0081] Some of the electrical energy used to apply voltage in adsorption operation can potentially be recovered in gas release operation.

[0082] The operating process can be carried out in cycles, with each cycle comprising at least one adsorption phase and one gas release phase. The Lewis acid can be separated, in particular, by repeatedly performing these cycles.

[0083] During operation of the gas separation cell(s), the pressure in the feed chamber and in the gas separation chamber can be at different levels.

[0084] In a further embodiment, the pressure in the gas separation chamber is reduced during the gas release operation of the gas separation cell(s). This can advantageously promote and / or accelerate the release of the Lewis acid.

[0085] In a further embodiment, the pressure in the gas separation chamber is increased during adsorption operation of the gas separation cell(s). This advantageously promotes and / or accelerates the dissolution of the Lewis acid in the membrane, particularly in the liquid and / or electrolyte of the membrane.

[0086] In a further embodiment, the feed chamber of the gas separation cell(s) is partially or completely evacuated before gas release operation, particularly between adsorption and gas release operation. Partial evacuation can be understood to mean, in particular, a pressure reduction to an average pressure level, for example, to approximately 500 mbar, and / or only the evacuation of certain channels of the system. This advantageously counteracts the potential dissolution of gases other than the Lewis acid to be deposited in the membrane, especially in the liquid and / or electrolyte of the membrane, without affecting or removing the Lewis acid, for example, carbon dioxide, bound to the at least one electrochemically active material of the adsorption electrode.This advantageously ensures that the volume evacuated from the gas separation chamber is usable product gas.

[0087] In a further embodiment, the gas separation chamber of the gas separation cell(s) is partially or completely evacuated before adsorption operation, particularly between gas release and adsorption operation. During this process, evacuated gas, especially gaseous Lewis acid, can be returned from the gas separation chamber of one cell to another, for example, the same cell or a neighboring cell. This advantageously allows further gaseous Lewis acid to be desorbed, released, and / or removed, thereby achieving an improved yield of the gaseous Lewis acid.

[0088] In a further embodiment, adsorptive fine purification of the gaseous Lewis acid is carried out at the end of the gas separation chamber. For this purpose, a fine purification device can be provided at the end of the gas separation chamber of the gas separation cell(s).

[0089] With regard to further technical features and advantages of the operating method according to the invention, explicit reference is hereby made to the explanations in connection with the gas separation cell and the gas separation system according to the invention, as well as to the figure and the description of the figures. drawing

[0090] Further advantages and advantageous embodiments of the objects according to the invention are illustrated by the drawing and explained in the following description. It should be noted that the drawing is for descriptive purposes only and is not intended to limit the invention in any way. It shows Fig. 1 a schematic cross-section through an embodiment of an electrochemical gas separation system according to the invention with electrochemical gas separation cells according to the invention.

[0091] Fig. Figure 1 shows that the electrochemical gas separation system 100 for the electrochemical separation of a gaseous Lewis acid, for example carbon dioxide, from a fluid mixture, in particular a gas mixture, containing the Lewis acid, comprises at least two electrochemical gas separation cells 10, 10' in the embodiment shown therein. The reference numerals 10* and 10** with the dashed arrows indicate that adjacent to the gas separation cell 10 there is another, not fully shown, gas separation cell 10* (of the one shown in Figure 1). Fig. 1 only a feed chamber 50* is visible) and next to the gas separation cell 10' another gas separation cell 10** is or may be arranged.

[0092] Fig. Figure 1 shows that the gas separation cells 10, 10' each have an adsorption electrode 20, 20' with an electrochemically active material for the reversible electrochemical adsorption of the Lewis acid (CO2), in particular carbon dioxide, for example para-anthraquinone (PAQ), and a counter electrode 30, 30', in particular with an electrochemically active material for charge balancing of the adsorption electrode 20, 20', for example polyvinylene ferrocene (PVFc). A separator 40, 40' is arranged between the adsorption electrode 20, 20' and the counter electrode 30, 30'.

[0093] Fig. Figure 1 further shows that a membrane 60 is arranged between the adsorption electrode 20 and a supply chamber 50 for supplying the fluid mixture, in particular a gas mixture, to the adsorption electrode 20. The membrane 60, 60' can be permeable to the Lewis acid in a liquid and / or electrolyte-soluble state, particularly under the operating conditions of the cell 10, and impermeable to the Lewis acid in the gaseous state—and, for example, also to other gaseous substances, such as those in the fluid mixture or the gas mixture. The membrane 60, 60' can, for example, be a porous, liquid- and / or electrolyte-impregnated membrane under the operating conditions of the cell 10. The membrane 60,60' advantageously allows the feed chamber 50,50* and thus the raw gas to be separated from the separated Lewis acid (CO2), which can be released in a gas separation chamber 41,31,80,41',31',80'.The separated Lewis acid (CO2) can be removed from the gas separation chamber 41,31,80,41',31',80' for further use, or possibly extracted.

[0094] Fig. Figure 1 further shows that the gas separation chamber 41, 31, 80, 41', 31', 80' is formed on the side of the adsorption electrode 20, 20' facing away from the membrane 60, 60'. In the Fig. In the embodiment shown in Figure 1, the gas separation chamber 41, 31, 80, 41', 31', 80' is at least partially separated by means of the separator 40, 40', in particular by means of gas separation channels 41, 41' formed in the separator 40, 40', which extend through the separator 40, 40' in a direction perpendicular to the plane of the separator 40, 40', and at least partially separated by means of gas separation channels 31, 31' formed in the counter electrode 30, 30', which extend through the counter electrode 30, 30' in a direction perpendicular to the plane of the counter electrode 30, 30', and at least partially separated by a bipolar plate 70' with grooves and / or a wave-like feature and / or a It has a wave-like cross-section.

[0095] Fig. Figure 1 shows that the bipolar plate 70,70' can directly make electrical contact with the counter electrode 30,30'. Electrical contact between the bipolar plate 70' and the adsorption electrode 20' can be achieved, for example, by an electrically conductive design of the membrane 60' and / or perforations in the membrane 60 and / or contact points on the bipolar plate 70' and / or the adsorption electrode 20.

[0096] In the Fig. In the embodiment shown in Figure 1, the separator 40, 40' and the counter electrode 30, 30' are perforated by the gas separation channels 41, 41'; 31, 31'. This allows any gas bubbles that form, for example CO2 bubbles, to flow through the perforation and collect in the area of ​​the grooves of the bipolar plate 70, 70' above. However, these perforations are not mandatory. Other embodiments without such perforations or gas separation channels 41, 41'; 31, 31' are explained in the general description section.

[0097] Fig. Figure 1 illustrates that the bipolar plate 70,70' with corrugations and / or a wave-like shape and / or a wave-like cross-section also at least partially forms the supply space 50,50*. Fig. Figure 1 illustrates that by means of a bipolar plate 70,70' both the gas separation chamber 41,31,80, 41',31',80' of a gas separation cell 10,10' and the supply chamber 50*,50 of an adjacent cell 10*,10 is at least partially formed.

[0098] Fig. Figure 1 also shows that the gas separation cells are arranged in a stacked fashion 10,10'.

[0099] In principle, the gas separation system 100 and the gas separation cells 10,10' can have a horizontal or horizontal structure, in particular in the form of a stack with horizontal or horizontal planes, wherein Fig. 1 would show a side view - similar to a side view of a stack of books on a table.

[0100] Preferably, however, the gas separation system 100 and the gas separation cells 10,10' have a vertical or perpendicular structure, in particular in the form of a stack with vertical or perpendicular planes, which is why Fig. 1 preferably shows a top view - similar to a top view of vertically stacked books in a bookshelf.

[0101] The in Fig. The gas separation system 100 and its gas separation cells 10,10' shown in Figure 1 can be operated, for example, in two phases, in particular alternating phases, namely in an adsorption operation and in a gas release operation, by means of electrochemical (potential) alternating adsorption.

[0102] In the adsorption operation of the gas separation cells 10, 10', the fluid mixture, in particular a gas mixture, containing the Lewis acid (CO2) can be passed through the feed chamber 50 over the membrane 60, whereby the Lewis acid (CO2) dissolves in the membrane 60, in particular in the liquid and / or in the electrolyte of the membrane 60, so that the Lewis acid (CO2) can diffuse through the membrane 60 to the adsorption electrode 20 in the liquid and / or electrolyte dissolved state. A potential is thereby established between the adsorption electrode 20 and the counter electrode 30 of the cell 10 such that the at least one electrochemically active material of the adsorption electrode 20 is reduced by accepting electrons and binding and / or adsorbing the Lewis acid (CO2), and the at least one electrochemically active material of the counter electrode 30 is oxidized by releasing electrons.

[0103] In adsorption operation, the Lewis acid carbon dioxide (CO2) can thus be adsorbed from the fluid mixture, in particular gas mixture, passed over the membrane 60 at the adsorption electrode 20, thereby reducing its carbon dioxide content, so that the fluid mixture, in particular gas mixture, after passing over the membrane 60 may have a reduced carbon dioxide content or may even be essentially carbon dioxide-free.

[0104] In a gas release operation of the gas separation cell / n 10, the potential set between the adsorption electrode 20 and the counter electrode 30 of the cell 10 can then be reversed or reversed, in particular in comparison to the adsorption operation, whereby the at least one electrochemically active material of the adsorption electrode 20 is oxidized by releasing electrons and gaseous Lewis acid (CO2), in particular carbon dioxide, and the at least one electrochemically active material of the counter electrode 30 is reduced by taking up electrons. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2022 / 0339579 A1

[0005] Cited non-patent literature

[0000] Hatton et al. describe in the scientific publication Energy Environ. Sci., 2019, 12, 3530

[0004]

Claims

[1] Electrochemical gas separation cell (10,10') 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 (20,20') with at least one electrochemically active material for the reversible electrochemical adsorption of the Lewis acid, - a counter electrode (30,30') and - a separator (40,40') arranged between the adsorption electrode (20,20') and the counter electrode (30,30'), wherein a membrane (60,60') is arranged between the adsorption electrode (20,20') and a feed chamber (50) for supplying the fluid mixture. [2] Gas separation cell (10,10') according to claim 1, wherein the membrane (60,60') is permeable to the Lewis acid in a liquid and / or electrolyte-soluble state under the operating conditions of the cell (10,10'), and wherein the membrane (60,60') is impermeable to the Lewis acid in the gaseous state under the operating conditions of the cell (10,10'), in particular where the membrane (60,60') is porous as such, and / or wherein the membrane (60,60') is saturated with liquid and / or electrolyte under the operating conditions of the cell (10,10'), and / or where the membrane (60,60') is a porous, liquid- and / or electrolyte-impregnated membrane under the operating conditions of the cell (10,10'). [3] Gas separation cell (10,10') according to claim 1 or 2, wherein a gas separation chamber (41,31,80,41',31',80') is formed on the side of the adsorption electrode (20,20') facing away from the membrane (60,60'). [4] Gas separation cell (10,10') according to claim 3, wherein the gas separation chamber (41,31,80,41',31',80') is formed at least partially by means of the separator (40,40'), in particular wherein gas separation shafts (41,41') are formed in the separator (40,40') which extend through the separator (40,40') in a direction perpendicular to the plane of the separator (40,40'), and / or wherein gas separation channels are formed in the separator (40,40') which extend in a direction parallel to the plane of the separator (40,40'), and / or wherein the separator (40,40') has corrugations and / or a wave-like shape and / or a wave-like cross-section to at least partially form the gas separation chamber (41,31,80,41',31',80'). [5] Gas separation cell (10, 10') according to claim 3 or 4, wherein the gas separation chamber (41, 31, 80, 41', 31', 80') is at least partially formed by means of the counter electrode (30, 30'), in particular wherein gas separation channels (31,31') are formed in the counter electrode (30,30') which extend through the counter electrode (30,30') in a direction perpendicular to the plane of the counter electrode (30,30'), and / or wherein gas separation channels are formed in the counter electrode (30,30') which extend in a direction parallel to the plane of the counter electrode (30,30'). [6] Gas separation cell (10,10') according to any one of claims 1 to 5, wherein the gas separation cell (10,10') has a vertical structure, in particular wherein the adsorption electrode (20,20') and / or the separator (40,40') and / or the counter electrode (30,30') and / or the feed chamber (50,50*) and / or the membrane (60,60') and / or the gas separation chamber (41,31,80,41',31',80') have a substantially vertical extent, or wherein the gas separation cell (10,10') has a horizontal structure, in particular wherein the adsorption electrode (20,20') and / or the separator (40,40') and / or the counter electrode (30,30') and / or the feed chamber (50,50*) and / or the membrane (60,60') and / or the gas separation chamber (41,31,80,41',31',80') have a substantially horizontal extent. [7] Gas separation cell (10,10') according to any one of claims 1 to 6, wherein the Lewis acid 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 is in particular where the Lewis acid is carbon dioxide (CO2). [8] Gas separation system (100) 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, comprising at least two electrochemical gas separation cells (10,10') according to any one of claims 1 to 7. [9] Gas separation system (100) according to claim 8, wherein a bipolar plate (70') is arranged between two adjacent gas separation cells (10, 10'), in particular wherein a bipolar plate (70') is arranged between the membrane (60) of a gas separation cell (10) and the counter electrode (20') of an adjacent gas separation cell (10'). [10] Gas separation system (100) according to claim 8 or 9, wherein the gas separation chamber (41, 31, 80, 41', 31', 80') and / or the feed chamber (50, 50*) is at least partially formed by means of a bipolar plate (70, 70'), in particular wherein a gas separation chamber (41,31,80,41',31',80') of a cell (10,10') and a supply chamber (50*;50) of an adjacent cell (10*,10) are formed by means of a bipolar plate (70,70'), and / or wherein the bipolar plate (70,70') has corrugations and / or a wave-like shape and / or a wave-like cross-section to at least partially form the gas separation chamber (41,31,80,41',31',80') and / or the feed chamber (50,50*), and / or wherein gas separation channels and / or supply channels are formed in the bipolar plate (70,70') which extend in a direction parallel to the plane of the bipolar plate (70,70'). [11] Gas separation system (100) according to one of claims 9 to 10, wherein the gas separation chamber (41,31,80,41',31',80') is formed at least partially by means of a gas-conducting, in particular gas-conducting and electrically conductive, intermediate layer between the counter electrode (40,40') and the bipolar plate (70,70'), and / or wherein the supply space (50) is formed at least partially by means of a gas-conducting, in particular gas-conducting and electrically conductive, intermediate layer between the bipolar plate (70') and the membrane (60). [12] Gas separation system (100) according to one of claims 9 to 11, wherein the gas separation cells (10,10') are arranged in a stack, wherein the gas separation cells (10,10') are arranged in the form of a vertical stack or in the form of a horizontal stack, in particular in the form of a vertical stack. [13] Gas separation system (100) according to any one of claims 9 to 12, wherein the membrane (60,60') is at least partially electrically conductive; and / or wherein the bipolar plate (70') has contact points which penetrate the membrane (60), and / or wherein the membrane (60) has continuous recesses through which the bipolar plate (70') extends partially to the adsorption electrode (20), in particular wherein the bipolar plate (70') closes and / or seals the recesses, and / or wherein the adsorption electrode (20) has metallic structures for electrical contacting the bipolar plate (70'). [14] Operating method for operating a gas separation cell (10,10') according to one of claims 1 to 8 and / or a gas separation system (100) according to one of claims 9 to 13 for separating a gaseous Lewis acid, in particular carbon dioxide, from a fluid mixture containing the Lewis acid, in particular a gas mixture, in which the gas separation cell (10,10') or the gas separation cells (10,10') are operated by means of electrochemical alternating adsorption, in particular potential swing adsorption. [15] Operating method according to claim 14, wherein in an adsorption operation of the gas separation cell (10,10') the fluid mixture containing the Lewis acid, in particular a gas mixture, is passed through the feed chamber (50) over the membrane (60) and 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 of the adsorption electrode (20) is reduced by accepting electrons and by binding and / or adsorption of the Lewis acid and the at least one electrochemically active material of the counter electrode (30) is oxidized by releasing electrons, and / or wherein in a gas release operation of the gas separation cell / s (10,10') the potential set between the adsorption electrode (20) and the counter electrode (30) of the cell (10) is reversed or repolarized, in particular in comparison to the adsorption operation, such that the at least one electrochemically active material of the adsorption electrode (20) is oxidized by releasing electrons and gaseous Lewis acid, in particular carbon dioxide, especially into the gas separation chamber, and the at least one electrochemically active material of the counter electrode (30) is reduced by absorbing electrons.

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