System for reducing carbon dioxide, and electrolysis cell for same

Abstract

The invention relates to an electrolysis cell (1) for reducing carbon dioxide, comprising at least one stack (2) made of an anode chamber (3), a cathode chamber (4), and optionally a gas chamber (5) which adjoins the cathode chamber (4); fluid supply lines (61, 62, 63) and fluid discharge lines (71, 72, 73) which are designed to supply the anode chamber (3) with analyte, the cathode chamber (4) with catholyte or selectively gas, or the optional gas chamber (5) with gas; and a power line (8) for applying a voltage between the cathode chamber (4) and the anode chamber (5). According to the invention, multiple stacks (2) are provided, and the fluid supply lines (61, 62, 63), the fluid discharge lines (71, 72, 73), and the power line (8) are designed to simultaneously supply fluid and power to a plurality of the stacks (2), in particular all of the stacks.

Description

[0001] Carbon dioxide reduction plant and electrolysis cell for this purpose

[0002] The invention relates to an electrolysis cell for the reduction of carbon dioxide, comprising at least one stack of an anode compartment, a cathode compartment and optionally a gas compartment adjoining the cathode compartment, as well as fluid supply lines and fluid discharge lines which are designed to supply the anode compartment with anolyte, the cathode compartment with catholyte and optionally gas or the optional gas compartment with gas, and a power line for applying a voltage between the cathode compartment and the anode compartment.

[0003] Furthermore, the invention relates to a plant for the continuous reduction of carbon dioxide using such an electrolysis cell.

[0004] The increasing emission of carbon dioxide (CO2) into the atmosphere in recent decades is considered one of the main causes of global warming. As with other climate-relevant gases, efforts are being made to find solutions to this problem. A first approach is to reduce CO2 emissions. However, this is hardly feasible in the short term, especially at the international level. Furthermore, individual industrial sectors cannot easily be converted to CO2-free production or at least to production with reduced CO2 emissions. Therefore, a second approach is to keep the resulting CO2 emissions low by converting the carbon dioxide at the site of production into substances that are not harmful to the climate and can be advantageously reused in other reactions.Since reducing CO2 emissions may not be sufficient to stop global warming, this second approach is of great importance.

[0005] Among the various options for directly utilizing CO2 at the point of its production, the electrochemical reduction of CO2 to form fuels represents a particularly interesting possibility. State-of-the-art research has been underway for decades to convert CO2 into compounds such as methane, methanol, and / or ethanol in a so-called "dream reaction." If this could be achieved in an energy-efficient and environmentally friendly way, climate-damaging CO2 could be converted into usable substances, making it a truly perfect reaction for the environment. CO2 emissions from industry, such as flue gas, exhaust gases from heating systems, exhaust gases from biotechnology plants, and the like, could be utilized to produce useful products that could either be further processed or, if necessary, temporarily stored.

[0006] Although the conversion of CO2 as described above offers many advantages and has therefore been researched for decades, no decisive breakthrough has yet been achieved in the electrochemical conversion of CO2. Such an electrochemical conversion requires an electrolysis cell that allows the corresponding reaction to be carried out efficiently on a large-scale. While individual successes on a laboratory scale using an electrolysis cell of the type mentioned above can confirm theoretical approaches, they do not allow for efficient implementation on a larger scale.

[0007] This is where the invention comes in. The object of the invention is to provide an electrolysis cell of the type mentioned above, with which the electrochemical conversion of CO2 is possible efficiently, in a small space, and with high throughput.

[0008] Another goal is to create a plant with such an electrolysis cell.

[0009] The object of the invention is achieved if, in an electrolysis cell of the type mentioned at the outset, several stacks are provided and the fluid supply lines as well as the fluid discharge lines and the power line are arranged for the simultaneous fluid supply and current application to several, in particular all, stacks.

[0010] An electrolysis cell according to the invention combines several advantages: First, the electrolysis cell comprises several stacks arranged adjacent to one another, enabling a space-saving design. The stacks are advantageously constructed as three-chamber systems, each having a gas chamber, a cathode chamber, and an anode chamber. The gas chamber is operatively connected to the cathode chamber such that supplied CO2 can enter the cathode chamber via a membrane, foil, or the like, according to the principle of a gas diffusion electrode. Due to the arrangement of several adjacent stacks, the electrolysis cell is highly efficient with regard to CO2 conversion. This makes it possible to achieve the same efficiency, yield, selectivity, and final conversion as with larger cells.Typically, a single electrolysis cell contains between 2 and 50 stacks, particularly between 2 and 25, for example, between 3 and 10. However, the number of stacks is not limited to 50 and can, in principle, be chosen arbitrarily, as long as sufficient operational stability is achieved. In practice, the number of stacks or connected cells can be designed according to the desired productivity and / or cell volume.

[0011] Furthermore, the electrolysis cell is compact due to the series-connected stacks, thus ensuring high efficiency in terms of space and volume. The stacks can be arranged in series because they are conductively connected to one another. For this purpose, bipolar electrodes are provided at the ends of the stacks, allowing current to flow to the next stack. This allows the individual stacks to be placed side by side without any gaps. Thus, the stacks can be positioned directly next to one another.

[0012] The corresponding advantages can be realized because, with the given stack arrangement, the fluid supply lines, fluid discharge lines, and power line are additionally configured for the simultaneous fluid supply and current application to several stacks. A single fluid supply for the anolyte can supply all anode compartments of the individual stacks with anolyte simultaneously. Similarly, the anolyte can be removed from the anode compartments via a single fluid discharge line. The same applies to the cathode compartments, which can also be supplied with a single fluid supply line, with a single fluid discharge line provided for the removal of catholyte from the cathode compartments. The same applies analogously to the gas supply.

[0013] The power supply is also configured so that a voltage can be applied to all stacks via a single power line to carry out the electrochemical reduction of CO2. Since the individual stacks are conductively connected to each other via bipolar electrodes, a voltage can be applied to all stacks simultaneously using a single power rail. Similar to the fluid supply and discharge lines, the current is supplied to the individual stacks via a first power rail, and a second power rail serves as the current collector.

[0014] The above statements regarding the structure also apply if the stacks are designed as 2-chamber systems, which is also possible within the scope of the invention. In this case, the gas is fed into the cathode compartment, not the gas compartment. In this case, the cathode compartment can also be constructed very simply by comprising a membrane that is merely kept moist, so that in this case the supplied moisture can be regarded as the catholyte. In principle, however, 3-chamber systems are preferred, since in these CO2 can be supplied at virtually 100%, whereas in 2-chamber systems the CO2 solubility in the catholyte is limiting. 3-chamber systems with separate feed of anolyte into the anode compartment, catholyte into the cathode compartment, and gas into the gas compartment are therefore preferred with regard to high CO2 conversion.

[0015] The stacks can basically be designed in any way. However, to save space and enable easy fluid supply and removal, it is preferred if the stacks are each constructed in layers. A stack then comprises a layered anode chamber, an adjoining layered cathode chamber, and a layered gas chamber through which the CO2 is supplied. If the stacks are adjacent to one another, the stack also comprises an insulating layer to ensure insulation from the next adjacent stack. The layered design of a stack or of all stacks is advantageously such that the maximum diameter of a layer is at least 5 times, preferably at least 10 times, in particular at least 20 times, the thickness of the layer. The shape of each layer can be arbitrary. The layered stacks are advantageously approximately circular in plan view.This offers advantages both in terms of production technology and for the construction of the electrolysis cell, as the electrolysis cell can then be constructed with a cylindrical shape, which proves advantageous for high loads on the electrolysis cell during use, especially since high pressures are present and the electrolysis cell must withstand these pressures through suitable pressing forces. This can be achieved satisfactorily if the stacks form a cylinder, with the stacks resting against one another. For example, the stacks can then be screwed between two end plates, via which the stacks are subjected to suitable pressing forces.

[0016] A particularly advantageous variant is provided when the fluid supply lines are arranged perpendicular to the stacks. In this case, in particular, a single fluid supply line can be provided for all anode compartments, as well as a single fluid supply line for all cathode compartments, and a single fluid supply line for supplying CC>2-containing gas to the gas compartments. Particularly when the stacks are layered, the respective fluid supply line can be arranged laterally. For these reasons, it is also expedient for the fluid outlet lines to be arranged perpendicular to the stacks.

[0017] For the appropriate introduction and discharge of fluids, it is expedient if the cathode chamber of a stack has a cathode chamber inlet which is connected to the fluid supply line for the cathode chamber, and a cathode chamber outlet which is connected to the fluid discharge from the cathode chamber. In this context, it is particularly expedient, especially in a layered structure of the stack, for the cathode chamber outlet to be located opposite the cathode chamber inlet, in particular offset by 180°. With this design, all cathode chambers in the respective layer or level can be fed laterally via a single fluid supply line. A discharge then takes place on the opposite side of the respective layer so that the layer or level can be fully utilized.

[0018] For analogous reasons, it is particularly expedient if the anode chamber of a stack has an anode chamber inlet that is connected to the fluid supply line for the anode chamber and an anode chamber outlet that is connected to the fluid discharge line from the anode chamber. In this case, too, it is particularly expedient for the anode chamber outlet to be located opposite the anode chamber inlet, in particular offset by 180°. This arrangement is particularly expedient when the stacks are each layered.

[0019] Finally, the gas space of a stack also advantageously has a gas space inlet connected to the fluid supply line for the gas space and a gas space outlet connected to the fluid discharge line from the gas space. In this case, too, the gas space outlet can be located opposite the gas space inlet, in particular offset by 180°, which is particularly advantageous in a layered stack structure. Gas can be fed in, for example, at a pressure of 1 bar to 20 bar, in particular 1 bar to 10 bar.

[0020] To ensure that all stacks can be fed with a single fluid supply line and that outflowing fluids can be removed with a single fluid outlet, the individual fluid supply lines are offset from one another in a top view of the stacks. This also applies to the fluid outlets.

[0021] If, as explained above, a fluid inlet and outlet are designed such that in each stack, the fluids enter the fluid inlet at one edge and exit the fluid outlet at another edge, the fluids flow parallel to each other and perpendicular to a longitudinal axis of the electrolysis cell through each layer. However, it is also possible for the inlets and outlets to be designed such that the fluids flow in series through all stacks before finally exiting. For this, it is only necessary to close individual inlets and outlets, with the structure otherwise unchanged. The fluids can then flow in a loop or meandering pattern through the individual stacks.

[0022] Particularly in the case of a layered structure of the stacks, which can each be present separately in a cylindrical form and positioned adjacent to one another, it is recommended that the stacks be clamped between end plates. Since the cathode and anode chambers are provided with corresponding fittings surrounded by clamping rings, a particularly high pressing force is advantageous in order to ensure that the electrolysis cell as a whole is leak-tight. The individual fluids are then preferably supplied in such a way that the fluid inlets and outlets run through the end plates. This results in an approximately cylindrical design of the electrolysis cell with two end plates that protrude when viewed from the front, through which the fluid inlets and outlets are routed. The individual fluid inlets and outlets are offset from one another.Firstly, the fluid supply line for a medium, for example the catholyte or the anolyte or the gas, is preferably offset by 180° relative to the corresponding fluid outlet for the catholyte, the anolyte or the gas. Furthermore, the individual fluid supply lines and thus also, with a predetermined offset, the corresponding fluid outlets are offset from one another, so that an angle of, for example, 10° to 90° exists between the individual supply lines or outlets. For example, a fluid supply line for the anolyte can be offset by 60° compared to a fluid supply line for the catholyte. The same applies to the corresponding fluid outlets. A fluid supply line for the gas can in turn be offset by 60° compared to the fluid supply line for the anolyte.Since the same applies to the fluid discharge for the gas, the individual fluid supply and discharge lines can be arranged with a high degree of symmetry in the end plates, resulting in a balanced stress profile with regard to the forces that occur. Furthermore, corresponding bolts are provided, which connect the end plates with corresponding nuts so that the electrolysis cell can withstand the overall pressure during operation. Since the bolts are not intended to penetrate the stacks, the end plates are preferably made wider than the stacks. Like the stacks, the end plates can also be circular.

[0023] The aim is to achieve the highest possible efficiency for the desired reactions in the cathode and anode compartments, which overall relates to the conversion of CO2. For this reason, it is advantageous for the stacks in the cathode and / or anode compartments to be designed with, in particular, static, mixing elements. Static mixing elements can be implemented in various ways. For example, it is possible for the corresponding internals in the cathode and / or anode compartments to be designed as metal foam or metal mesh. It has proven particularly advantageous if the mixing elements have spiral fluid paths. In particular, if a lateral supply of the respective fluid is provided, a spiral guidance of the respective fluid leads to a comparatively long residence time before the fluid is discharged again via the corresponding fluid discharge.This long residence time in the actual reaction chamber benefits high efficiency in the conversion of CO2. The further objective of the invention is achieved when a plant for the continuous reduction of carbon dioxide comprises an electrolysis cell according to the invention.

[0024] In a corresponding system, the advantages explained for the electrolysis cell are fully realized due to the additional peripherals provided, in particular an anolyte tank for supplying anolyte to the anode compartments of the stacks and a catholyte tank for supplying catholyte to the cathode compartments, including the corresponding discharges.

[0025] It is advantageous to provide a carbon dioxide cycle through which unconverted carbon dioxide can be returned to the stacks for further conversion. This ensures that the supplied carbon dioxide is largely converted.

[0026] As explained above, stacks constructed either as a three-chamber system or a two-chamber system can be used within the scope of the invention. If multiple electrolysis cells are used, it is also conceivable to implement combinations of three-chamber and two-chamber systems in one system.

[0027] However, 3-chamber systems are generally preferred as they lead to a better product yield.

[0028] Further features, advantages, and effects of the invention will become apparent from the following exemplary embodiments. Reference is made to the drawings, which show:

[0029] Fig. 1 an electrolysis cell with a stack in 3-chamber design;

[0030] Fig. 2 shows an electrolysis cell with several stacks in a front view;

[0031] Fig. 3 shows the electrolysis cell from Fig. 2 in a plan view;

[0032] Fig. 4 shows the electrolysis cell from Fig. 2 and Fig. 3 in a perspective view;

[0033] Fig. 5 to Fig. 7 the electrolysis cell from Fig. 2 to Fig. 4 with a representation of the fluid supply lines and fluid discharge lines for gas (Fig. 5), for the catholyte (Fig. 6) and the anolyte (Fig. 7);

[0034] Fig. 8 is a schematic representation of a current flow; Fig. 9 is a plan view of an installation for a cathode compartment and / or an anode compartment;

[0035] Fig. 10 a variant of an installation;

[0036] Fig. 11 shows another variant of an installation;

[0037] Fig. 12 an electrolysis cell with a stack in a 2-chamber design;

[0038] Fig. 13 a plant with an electrolysis cell according to the invention for the reduction of CO2.

[0039] Fig. 1 shows an electrolysis cell 1. The electrolysis cell 1 comprises three stacks 2, each containing a three-chamber cell. The illustration in Fig. 1 serves merely as an example. An electrolysis cell 1 according to the invention can, in principle, comprise any number of stacks 2, in particular 3 to 15 stacks 2.

[0040] The electrolysis cell 1 shown in Fig. 1 is constructed such that it has two end plates 9. The end plates 9 are circular. The two end plates 9 have a plurality of openings for purposes to be explained later.

[0041] Between the two end plates 9 is a structure for the electrochemical reduction of CO2. Starting on the left side of the exploded view in Fig. 1, a first power connection 83 of a power line 8 is provided. A separating plate 10 is connected to this, which insulates the end plate 9 from the power connection 83. The power connection 83 is followed by several stacks 2, with one stack 2 being shown in an exploded view, whereas the other two stacks are shown in an assembled view. For the stack 2 shown in the exploded view, the structure for an anode chamber 3 first follows, beginning with a bipolar plate 58 or bipolar electrode. The anode chamber 3 comprises a central anode assembly 33, which is surrounded by an anolyte chamber plate 34 and a seal 35. The seal 35 can be made of polytetrafluoroethylene (PTFE).The anode assembly 33 is held in place by the anolyte chamber plate 34 and the seal 35. This is followed by a membrane 36, which establishes a connection to a cathode chamber 4. A cathode assembly 43 is provided in the cathode chamber 4. The cathode assembly 43 can be designed analogously to the anode assembly 33, as shown in Fig. 9 to Fig. 11.

[0042] In particular, both the anode assembly 33 and the cathode assembly 43 can be provided with spiral-shaped fluid guides, as shown in Fig. 9. The cathode chamber 4 comprises a catholyte chamber plate 44 and a further seal 45 made of PTFE, as well as a conductive seal 46. This conductive seal 46 enables current to pass from otherwise insulated components, so that current can flow through the cathode chamber 4 and the anode chamber 3 via the conductive seal 46. The current is supplied from the outside and then enters the interior of the components for the cathode chamber 4 and the anode chamber 3 before the current is removed again. The conductive seal 46 can be made of graphite, in particular.

[0043] A gas chamber 5 adjoins the cathode chamber 4. The gas chamber 5 initially comprises a conductive support plate 53. A gas diffusion electrode 54 is connected to this support plate 53. This, in turn, is initially connected to another seal made of a conductive material such as graphite, in particular a graphite sealing ring 55. A gas chamber plate 56, a gas chamber insert 57, and a bipolar plate 58 seal off the gas chamber 5. The gas chamber plate 56 can also be omitted in order to reduce current resistance and the associated reduction in gas chamber volume; in this case, fluid is supplied and discharged via the seal 55. This is followed by a second power connection 84 and another separating plate 10, before the second end plate 9 follows.

[0044] As mentioned, the two end plates 9 each have a plurality of openings or bores. Some of these bores are intended to hold the electrolysis cell 1 and the individual components, as well as the surrounding rings, together by means of appropriate bolt-nut combinations, as can be seen in Fig. 2 and Fig. 4. The remaining openings serve to form fluid supply lines 61, 62, 63 and fluid discharge lines 71, 72, 73, and ultimately a power line 8, also equipped with a supply line and a discharge line.

[0045] The corresponding supply and discharge lines are shown in Fig. 2 to Fig. 4 and in particular Fig. 5 to Fig. 7 using the countercurrent principle. However, the electrolysis cell can also be designed so that the fluids are conducted in cocurrent. In a corresponding electrolysis cell according to Fig. 2 to Fig. 7, several stacks 2 are provided, namely three. However, the number of stacks 2 can certainly be higher. The individual stacks 2 are constructed as shown in Fig. 1 and, in contact with one another, are electrically connected via the bipolar plates 58. With a corresponding layered structure of the stacks 2, a compact arrangement can be achieved. This compact arrangement is supported by fluid supply lines 61, 62, 63 running perpendicular to the individual stacks 2. One fluid supply line 61, 62, 63 is provided for the anode compartment 3, the cathode compartment 4 and the gas compartment 5 of each stack 2.Due to the corresponding vertical arrangement, a supply line can be established from the side to the respective chambers, such as the anode chamber 3 or cathode chamber 4, as well as the gas chamber 5. For this purpose, the individual chambers each have suitable inlets and, for the discharge lines in the form of the fluid discharge lines 71, 72, 73, suitable outlets. These inlets are visible in Fig. 1, namely the anode inlets 31, the anode outlets 32, the cathode inlets 41, the cathode outlets 42, as well as the gas inlets 51 and the gas outlets 52. The vertically running supply lines and discharge lines thus allow fluid to be supplied from the side into each chamber, and fluid to be discharged, likewise from the side. To achieve the highest possible efficiency, the corresponding supply and discharge lines, or inlets and outlets, are arranged 180° opposite each other, so that the residence time within a single layer can be optimized as much as possible. As can be seen particularly in Fig.As can be seen in Fig. 3, a corresponding arrangement requires that the inlets and outlets are offset from one another so that the individual fluid supply lines 61, 62, 63 and the fluid outlet lines 71, 72, 73 do not collide with one another. An arrangement according to Fig. 3 proves to be expedient in this regard. If the individual supply and outlet lines are offset from one another at an appropriate angle of, for example, 45°, the available area can be effectively utilized. It should also be noted in this context that the power supply and outlet lines are also implemented accordingly, and space must also be provided for this in the selected configuration.

[0046] Fig. 5 to Fig. 7 show by way of example how a corresponding arrangement behaves with regard to the supply of the individual components (gas in Fig. 5, catholyte in Fig. 6 and anolyte in Fig. 7), with reference to the sections shown in Fig. 3. As can be seen, all spaces of all stacks 2 are supplied simultaneously by the corresponding guides and, in turn, material can be discharged from all spaces at the same time. Fig. 8 shows a current flow which, via two busbars 81, 82 and the first current connection 83 and the second current connection 84, is set up to supply all stacks 2 with current simultaneously, similar to the fluid supply lines 61, 62, 63 and the fluid discharge lines 71, 72, 73.

[0047] Fig. 9 to Fig. 11 show various installations which can be used for the anode chamber 3 and / or the cathode chamber 4 and / or the gas chamber 5. It is expedient to enable the most intimate exchange possible. For this purpose, a spiral design as shown in Fig. 8 is preferably provided, so that the supplied fluid has to travel as long and as equal a path as possible before it can be discharged again via a fluid discharge line 71, 72, 73. Alternatives are shown in Fig. 9 (metal foam) and Fig. 10 (metal mesh installation). Efficiency is also maximized in this case. With a metal foam, the flow channel can be controlled via the pore size of the sponge, resulting in a very even current distribution.

[0048] Fig. 12 shows an alternative electrolysis cell 1. This alternative variant is basically designed the same as the previously explained electrolysis cell 1 with a 3-chamber system, with the same reference numerals corresponding to the same parts. In Fig. 12, however, the gas chamber 5 and the devices required for it are omitted, so that the electrolysis cell 1 is designed with a stack of 2-chamber systems while otherwise having a fundamentally similar structure. Current is applied and the fluids, including the gas, are supplied largely in a similar way to the electrolysis cell 1 with a 3-chamber system, as explained with reference to Figs. 1 to 11. The anode chamber 3 and the cathode chamber 4 can also be designed as explained for Figs. 1 to 11.

[0049] Fig. 13 shows a system 11 with an electrolysis cell 1 according to the invention, preferably in the design of a 3-chamber system. In addition to the electrolysis cell 1, the system 11 comprises an anolyte container 12 and a catholyte container 13 as well as a product container 14 from which, for example, methanol and / or formic acid can be withdrawn. The corresponding containers are connected to the electrolysis cell 1. In particular, suitable lines are provided which are designed to introduce anolyte into the electrolysis cell 1 and to return it therefrom. The same is provided with regard to circulation of the catholyte. In addition, a corresponding line is provided for the gas supply, which is designed to supply carbon dioxide or, if appropriate, a gas containing carbon dioxide into the respective gas spaces 5 of the electrolysis cell 1. The gas is supplied at a pressure in the range of, for example, 1.5 bar or more.The gas can be circulated, as shown in Fig. 11. This allows CO2 to be circulated so that it can be converted as efficiently as possible. Gaseous products can be collected in a container 15. For this purpose, the converted product is separated by a suitable separation device and stored, for example, in the container 15. Unconverted CO2 is returned to the cycle.

Claims

Patent claims 1. Electrolysis cell (1) for the reduction of carbon dioxide, comprising at least one stack (2) of an anode chamber (3), a cathode chamber (4) and optionally a gas chamber (5) adjoining the cathode chamber (4), as well as fluid supply lines (61, 62, 63) and fluid discharge lines (71, 72, 73) which are designed to supply the anode chamber (3) with anolyte, the cathode chamber (4) with catholyte and optionally gas or the optional gas chamber (5) with gas, and a power line (8) for applying a voltage between the cathode chamber (4) and the anode chamber (5), characterized in that several stacks (2) are provided and the fluid supply lines (61, 62, 63) as well as the fluid discharge lines (71, 72, 73) and the power line (8) for the simultaneous fluid supply and current application to several, in particular all, Stack (2) are set up.

2. Electrolysis cell (1) according to claim 1, characterized in that the stacks (2) are each constructed in layers.

3. Electrolysis cell (1) according to claim 1 or 2, characterized in that the stacks (2) form a cylinder, wherein the stacks (2) lie against one another.

4. Electrolysis cell (1) according to one of claims 1 to 3, characterized in that the fluid supply lines (61, 62, 63) are arranged perpendicular to the stacks (2).

5. Electrolysis cell (1) according to one of claims 1 to 4, characterized in that the fluid discharge lines (71, 72, 73) are arranged perpendicular to the stacks (2).

6. Electrolysis cell (1) according to one of claims 1 to 5, characterized in that the cathode chamber (4) of a stack (2) has a cathode chamber inlet (41) which is connected to the fluid supply line (62) for the cathode chamber (4), and a cathode chamber outlet (42) which is connected to the fluid discharge line (72) from the cathode chamber (4).

7. Electrolysis cell (1) according to claim 6, characterized in that the cathode chamber outlet (42) is opposite the cathode chamber inlet (41), in particular is offset by 180°.

8. Electrolysis cell (1) according to one of claims 1 to 7, characterized in that the anode chamber (4) of a stack (2) has an anode chamber inlet (31) which is connected to the fluid supply line (61) for the anode chamber (3), and an anode chamber outlet (32) which is connected to the fluid discharge line (71) from the anode chamber (3).

9. Electrolysis cell (1) according to claim 8, characterized in that the anode chamber outlet (32) is opposite the anode chamber inlet (31), in particular is offset by 180°.

10. Electrolysis cell (1) according to one of claims 1 to 9, characterized in that the gas space (5) of a stack (2) has a gas space inlet (51) which is connected to the fluid supply line (63) for the gas space (5), and a gas space outlet (52) which is connected to the fluid discharge line (73) from the gas space (5).

11. Electrolysis cell (1) according to claim 10, characterized in that the gas space outlet (52) is opposite the gas space inlet (51), in particular is offset by 180°.

12. Electrolysis cell (1) according to one of claims 1 to 11, characterized in that the stacks (2) are clamped between end plates (9).

13. Electrolysis cell (1) according to claim 12, characterized in that the fluid supply lines (61, 62, 63) and the fluid discharge lines (71, 72, 73) run through the end plates (9).

14. Electrolysis cell (1) according to one of claims 1 to 13, characterized in that the stacks (2) in the anode chamber (3) and / or in the cathode chamber (4) and / or gas chamber (5) are formed with, in particular static, mixing elements.

15. Electrolysis cell (1) according to claim 14, characterized in that the mixing elements have spiral-shaped fluid paths.

16. Plant (11) for the continuous reduction of carbon dioxide, comprising an electrolysis cell (1) according to one of claims 1 to 15.

17. Plant (1) according to claim 16, characterized in that an anolyte container (12) for supplying anolyte into the anode compartments (3) of the stacks (2) and a catholyte container (13) for supplying catholyte into the cathode compartments (4) are provided and are arranged for the corresponding supply.

18. Plant (1) according to claim 16 or 17, characterized in that a circuit for carbon dioxide is provided, via which unconverted carbon dioxide can be returned to the stacks (2) for further conversion.

19. Plant (1) according to one of claims 16 to 18, characterized in that a separation device is provided for separating gaseous products, wherein the separation device is designed to recycle unreacted carbon dioxide for further conversion.

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