Carbon dioxide electrolysis device and method

Abstract

The present invention relates to a carbon dioxide electrolysis device including a carbon dioxide electrolysis cell including an anode, a cathode, an electrolyte, and a separation membrane disposed between the anode and the cathode, a supply line for supplying gaseous carbon dioxide and water vapor to the cathode, and a discharge line for discharging products and water vapor generated by the electrolysis reaction of carbon dioxide inside the carbon dioxide electrolysis cell to the outside of the cell, the discharge line including a condenser for condensing the water vapor discharged from the discharge line.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0007386, filed January 18, 2022, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an apparatus and method for electrolyzing carbon dioxide. [Background technology]

[0003] Carbon dioxide is a greenhouse gas that causes global warming and must be reduced. Known methods for reducing carbon dioxide include capture, chemical conversion, and electrochemical conversion. Among these, electrochemical conversion allows precise control of the components to produce other synthetic gases, and is more economically advantageous than simply removing carbon dioxide.

[0004] The process of electrochemically decomposing carbon dioxide is similar to that of water electrolysis, but since the activity of the electrochemical reaction improves in a strongly basic atmosphere, a KOH solution of a certain concentration is generally used as the electrolyte. When a current is applied while water is supplied to the anode, the water is decomposed into hydrogen ions and electrons, generating oxygen gas. The electrons move to the cathode via an external conductor, and the hydrogen ions move to the cathode via an ion-selective separation membrane. Here, the transferred electrons react with the carbon dioxide and water supplied to the cathode to produce carbon monoxide and hydroxide ions (OH - ) and the hydroxide ions generated are transported to the anode via hydrogen ions (H +) to produce water, resulting in an electrically neutral state. This process completes the electrochemical decomposition reaction of carbon dioxide. Here, the water supplied together with carbon dioxide reacts with the electrons that have moved separately from the carbon monoxide production reaction, and is electrolyzed to produce hydrogen gas and hydroxide ions. This reaction of water and electrons can be said to be in a competitive relationship with the carbon monoxide production reaction. Because this reaction is an electrochemical reaction, the amount of carbon monoxide produced and the hydrogen / carbon dioxide ratio can be easily adjusted by adjusting the voltage.

[0005] On the other hand, when a cation-conductive membrane is used as an ion-selective separation membrane, the K contained in the electrolyte + Ions move to the cathode through the separation membrane, and K + The ions react with carbon dioxide at the cathode to precipitate salts such as potassium carbonate (K2CO3). When an anion-conducting membrane is used as the ion-selective separation membrane, hydroxide ions mainly migrate, but K + Some cations such as ions also migrate, and in this case, salts are formed as in the case of using the cation-conductive membrane.

[0006] The salt generated and precipitated from the cathode accumulates inside the device as the carbon dioxide electrolysis process progresses. The salt accumulated inside the device clogs the inlet and outlet for supplying and discharging carbon dioxide, reducing the productivity and efficiency of the carbon dioxide electrolysis device and making it impossible to operate continuously for long periods of time. Furthermore, removing the salt requires additional equipment and work, which is inefficient in terms of facilities and operation. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Registration No. 10-1793711 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to remove salts generated from the electrolyte during the electrolysis of carbon dioxide by dissolving them in water.

[0009] That is, the present invention aims to provide an apparatus and method for electrolyzing carbon dioxide, which can dissolve and remove salts generated by a side reaction of electrolysis during the electrolysis of carbon dioxide by condensing water vapor supplied together with carbon dioxide to generate water when the water vapor is discharged together with the products of the electrolysis reaction. [Means for solving the problem]

[0010] The present invention provides an apparatus for electrolyzing carbon dioxide and a method for electrolyzing carbon dioxide.

[0011] (1) The present invention provides a carbon dioxide electrolysis device comprising: a carbon dioxide electrolysis cell including an anode, a cathode, an electrolyte, and a separation membrane disposed between the anode and the cathode; a supply line for supplying gaseous carbon dioxide and water vapor to the cathode; and a discharge line for discharging products and water vapor generated by the electrolysis reaction of carbon dioxide inside the carbon dioxide electrolysis cell to the outside of the cell, wherein the discharge line includes a condenser for condensing the water vapor discharged from the discharge line.

[0012] (2) The present invention provides the carbon dioxide electrolysis device according to (1) above, wherein the gaseous carbon dioxide is supplied in a state containing the water vapor.

[0013] (3) The present invention provides the carbon dioxide electrolyzer according to (1) or (2) above, wherein the water vapor supplied through the supply line has a temperature of 40°C to 60°C.

[0014] (4) The present invention provides the carbon dioxide electrolysis device according to any one of (1) to (3) above, wherein the condensation section is exposed to the outside of the carbon dioxide electrolysis cell.

[0015] (5) The present invention provides a carbon dioxide electrolysis device according to any one of (1) to (4), wherein the condensation section includes a storage section for storing water formed by condensing water vapor discharged from the discharge line.

[0016] (6) The present invention provides a carbon dioxide electrolysis device in any one of (1) to (5) above, wherein the discharge line includes a first line through which the product and water vapor discharged from the discharge line are transported from the carbon dioxide electrolysis cell to a condensation section, and a second line through which the product is discharged from the condensation section to the outside.

[0017] (7) The present invention provides the carbon dioxide electrolyzer according to (6), wherein the condenser is connected to the first line and the second line so that a step is formed between them.

[0018] (8) The present invention provides the carbon dioxide electrolyzer according to (7), wherein the second line is positioned higher than the first line by the step.

[0019] (9) The present invention provides a method for electrolyzing carbon dioxide, comprising the steps of: (S1) supplying gaseous carbon dioxide and water vapor to the cathode of a carbon dioxide electrolysis cell including an anode, a cathode, an electrolyte, and a separation membrane; (S2) electrolyzing the carbon dioxide supplied to the cathode in step (S1); (S3) discharging products produced by electrolysis in step (S2) and the water vapor supplied in step (S1) to the outside of the carbon dioxide electrolysis cell; and (S4) condensing the water vapor discharged in step (S3).

[0020] (10) The present invention provides the method for electrolyzing carbon dioxide according to (9), wherein the water formed by condensing the water vapor discharged in the step (S4) dissolves salt generated from the electrolyte by electrolysis in the step (S2).

[0021] (11) The present invention provides the method for electrolyzing carbon dioxide according to the above (10), wherein the salt is produced by reacting the electrolyte with supplied carbon dioxide.

[0022] (12) The present invention provides the method for electrolyzing carbon dioxide according to (10) or (11), wherein the salts are KHCO3 and K2CO3. [Effects of the Invention]

[0023] According to the carbon dioxide electrolysis device and method of the present invention, water can be produced by directly utilizing the water vapor supplied together with carbon dioxide during the electrolysis of carbon dioxide, and salt can be continuously removed using the produced water without the need for a separate salt removal device or salt removal operation.

[0024] Furthermore, the carbon dioxide electrolysis device of the present invention does not require a separate salt removal device or a separate salt removal operation, and therefore does not require a salt removal device or space to perform this, and the volume of the carbon dioxide electrolysis device can be reduced.

[0025] Furthermore, according to the carbon dioxide electrolysis device and method of the present invention, salt can be continuously removed without the need for a separate salt removal device or salt removal operation, and since the inlet and outlet of the carbon dioxide electrolysis device are not clogged with salt, smooth continuous operation is possible without any change in voltage, and production volume and electrolysis efficiency do not decrease even with continuous operation.

[0026] Furthermore, the carbon dioxide electrolysis device of the present invention can easily condense water and dissolve salt due to the special structure of the discharge line, eliminating the need for a separate condenser or water spray device, making it easy to install and maintain, and efficient in terms of structural equipment. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a cross-sectional view of a carbon dioxide electrolysis device according to one embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view of a conventional carbon dioxide electrolysis device. [Figure 3] 1 is a graph showing the change in voltage over time in Examples 1 and 2. [Figure 4] 10 is a graph showing the change in voltage over time in Example 3. [Figure 5] 1 is a graph showing the change in voltage over time for Examples 4, 5, 6 and 7. [Figure 6] 10 is a graph showing the change in voltage over time for Examples 8 and 9. [Figure 7] 10 is a graph showing the change in voltage over time in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be described in more detail below to facilitate understanding of the present invention. The terms and words used in the specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, but are to be construed as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concepts of terms in order to best describe his / her invention.

[0029] Carbon dioxide electrolysis device FIG. 1 is a cross-sectional view illustrating a carbon dioxide electrolysis device according to one embodiment of the present invention.

[0030] Referring to FIG. 1, the carbon dioxide electrolysis device of the present invention includes a carbon dioxide electrolysis cell 1000 including an anode 100, a cathode 200, an electrolyte 400, and a separation membrane 300 disposed between the anode 100 and the cathode 200; a supply line 500 for supplying gaseous carbon dioxide and water vapor to the cathode 200; and a discharge line 700 for discharging products and water vapor generated by the carbon dioxide electrolysis reaction inside the carbon dioxide electrolysis cell 1000 to the outside of the cell, wherein the discharge line 700 may include a condenser 750 for condensing the water vapor discharged from the discharge line 700.

[0031] According to one embodiment of the present invention, the carbon dioxide electrolysis cell 1000 is a device that converts input carbon dioxide into carbon monoxide and may include an anode 100, a cathode 200, an electrolyte 400, and a separation membrane 300. Electrolysis refers to the decomposition of a substance through an oxidation-reduction reaction by applying a direct current voltage, which is a decomposition reaction that does not occur by itself. The anode 100 serves as an oxidation electrode, oxidizing water to generate oxygen, which generates hydrogen ions. The hydrogen ions generated from the anode 100 are transferred to the cathode 200 via the electrolyte 400. The cathode 200 serves as a reduction electrode, and reactants input to the cathode 200 react with the electrons and hydrogen ions transferred from the anode 100 to generate products. The separation membrane 300 may be disposed between the anode 100 and the cathode 200. The separator 300 may be made of an inert material that does not participate in the electrochemical reaction itself, but it can serve to provide a path through which ions can move between the anode 100 and the cathode 200 and to separate the anode 100 and the cathode 200 from physical contact.

[0032] The anode 100 and the cathode 200 of the carbon dioxide electrolysis cell 1000 of the present invention may each include a catalyst layer. Water vapor supplied together with carbon dioxide in the cathode region undergoes an electroreduction reaction on the surface of the cathode 200 to generate a reduction product. Therefore, the cathode 200 may include a gas diffusion layer 210 to uniformly supply humidified carbon dioxide gas to the cathode region. When the cathode 200 includes a hydrophobic gas diffusion layer 210, the supplied carbon dioxide can be smoothly diffused, distributed, and supplied to the cathode catalyst layer 230. The hydrophobic gas diffusion layer 210 effectively prevents water condensation, thereby ensuring a continuous and uniform supply of carbon dioxide and a smooth electrolysis reaction. The catalyst layer 230 may have a porous surface to enhance gas permeability.

[0033] According to one embodiment of the present invention, the anode 100 may include a catalyst active in water electrolysis, and the catalytic layer of the anode 100 may include at least one selected from the group consisting of Pt, Au, Pd, Ir, Ag, Rh, Ru, Ni, Al, Mo, Cr, Cu, Ti, W, alloys thereof, or mixed metal oxides such as Ta2O5, IrO2, etc., for the oxygen evolution reaction. Specifically, the anode 100 in the carbon dioxide electrolysis device of the present invention may include nickel (Ni) coated with ruthenium oxide (RuO2) and cerium oxide (CeO2).

[0034] Furthermore, since the carbon dioxide reduction reaction occurring in the cathode 200 is a competitive reaction with the hydrogen generation reaction, a large voltage is required for the hydrogen generation reaction, and a catalyst active in the carbon dioxide reduction reaction may be included. The catalyst layer 230 of the cathode 200 may contain one or more elements selected from the group consisting of Sn, Sn alloys, Al, Au, Ag, C, Cd, Co, Cr, Cu, Cu alloys, Ga, Hg, In, Mo, Nb, Ni, NiCo2O4, Ni alloys, Ni-Fe alloys, Pb, Rh, Ti, V, W, Zn, and mixtures thereof for the hydrogen generation reaction. Specifically, the cathode 200 in the carbon dioxide electrolysis device of the present invention may contain silver (Ag).

[0035] The separation membrane 300 may include a cation exchange membrane (CEM) or an anion exchange membrane (AEM).

[0036] The electrolyte 400 may also contain KHCO3, K2CO3, KOH, KCl, KClO4, K2SiO3, Na2SO4, NaNO3, NaCl, NaF, NaClO4, CaCl2, guanidinium cations, H + The electrolyte 400 of the carbon dioxide electrolysis device of the present invention can be selected from the group consisting of aqueous solutions containing cations, alkali metal cations, ammonium cations, alkylammonium cations, halide ions, alkylamines, borates, carbonates, guanidinium derivatives, nitrites, nitrates, phosphates, polyphosphates, perchlorates, silicates, sulfates, tetraalkylammonium salts, or mixtures thereof, and can include KOH.

[0037] In addition, the gas diffusion layer 210 may be a porous body using a carbon material such as carbon fiber cloth, carbon fiber felt, or carbon fiber paper, or a metal porous body made of a thin metal sheet with a mesh structure such as expanded metal or metal mesh. In the carbon dioxide electrolysis device of the present invention, the gas diffusion layer may be made of carbon fiber cloth.

[0038] According to one embodiment of the present invention, the carbon dioxide electrolysis device of the present invention may include a supply line 500 that supplies gaseous carbon dioxide and water vapor to the cathode 200, a transfer line 600 that transports the supplied carbon dioxide and water vapor to the cathode 200 area so that they can participate in the reaction with minimal resistance, and a discharge line 700 that discharges products and water vapor generated by the reaction to the outside of the cell.

[0039] The length, material, and shape of the supply line 500, transfer line 600, and discharge line 700 are not limited as long as they can smoothly transfer carbon dioxide and water vapor. The transfer line 600 may have a parallel structure in which straight lines are arranged parallel to each other, or a serpentine structure having repeated "S" shapes. The supply line and discharge line may be connected to the carbon dioxide electrolysis cell 1000, and the transfer line 600 may be disposed adjacent to the cathode 200 inside the carbon dioxide electrolysis cell 1000. However, as described below, the discharge line 700 may include a condenser 750 and is preferably located outside the carbon dioxide electrolysis cell 1000 and connected to the carbon dioxide electrolysis cell 1000.

[0040] According to one embodiment of the present invention, the carbon dioxide electrolysis apparatus of the present invention may include a condenser 750 in the discharge line 700. The condenser 750 may condense the water vapor supplied through the supply line 500 when the water vapor passes through the reaction line and is discharged from the discharge line 700 to produce water.

[0041] Meanwhile, in a carbon dioxide electrolyzer, electrolyte 400-1 used during the electrolysis reaction exists in the form of cations and anions. When some cations migrate to the cathode region through separator 300-1, they react with carbon dioxide supplied to the cathode region to form and precipitate salt. In conventional carbon dioxide electrolyzers, the salt cannot be removed and accumulates continuously in the carbon dioxide electrolysis cell, supply line 500-1, and discharge line 700-1, eventually clogging the supply line 500-1 and discharge line 700-1. This prevents the carbon dioxide electrolyzer from operating continuously, making it difficult to conduct experiments and research that require long-term evaluation. Therefore, in the carbon dioxide electrolyzer of the present invention, the condenser 750 located in discharge line 700 converts supplied water vapor into water to dissolve the salt, thereby solving the above-mentioned conventional problems.

[0042] According to one embodiment of the present invention, the gaseous carbon dioxide may be supplied in a state containing the water vapor. This allows for a larger amount of carbon dioxide to be supplied than when carbon dioxide is supplied alone, thereby improving the efficiency of the carbon dioxide electrolysis device. Specifically, the carbon dioxide may be supplied in a state containing the water vapor by bubbling the carbon dioxide and water vapor through a separate humidifier, or the carbon dioxide and water vapor may be supplied in a mixed state by contacting each other through a separate device. In this case, the method of supplying the humidified carbon dioxide is not limited as long as the carbon dioxide can be supplied to the cathode 200 region through the supply line 500 in a humidified state.

[0043] When the carbon dioxide is supplied in a humidified state, it can be converted into water through the condenser 750 included in the discharge line 700, which has the effect of reducing the volume and simplifying the carbon dioxide electrolysis device.

[0044] According to one embodiment of the present invention, the temperature of the steam supplied through the supply line 500 may be 40°C to 60°C. Specifically, the temperature of the steam supplied may be 40°C or higher, 43°C or higher, 46°C or higher, or 49°C or higher, or 60°C or lower, 57°C or lower, 54°C or lower, or 51°C or lower. The carbon dioxide electrolyzer can be operated at a temperature of 40°C to 60°C, but the temperature of the device may rise due to heat generation or the temperature of the supplied materials. When the carbon dioxide electrolyzer is operated within this temperature range, the electrolysis efficiency is maintained and the product production rate does not decrease. Therefore, when the temperature of the supplied steam satisfies this range, the appropriate temperature of the carbon dioxide electrolyzer can be maintained, product production rate is maintained, and electrolysis efficiency is increased.

[0045] According to one embodiment of the present invention, the condenser 750 may be exposed to the outside of the carbon dioxide electrolysis cell 1000. As described above, the condenser 750 may condense the water vapor supplied via the supply line 500 and convert it into water, and the condenser 750 may be included in the discharge line 700 connected to the carbon dioxide electrolysis cell 1000. In addition, the condenser 750 is exposed to the outside of the carbon dioxide electrolysis cell 1000 and is in contact with external air at room temperature, allowing the water vapor to be naturally condensed by the air at room temperature without the need for a separate condenser or heat exchanger. By exposing the condenser 750 to the outside of the carbon dioxide electrolysis cell 1000, the carbon dioxide electrolysis device of the present invention has the advantages of not requiring a separate condensation facility, reducing the volume of the device, and not requiring additional energy.

[0046] According to an embodiment of the present invention, the condenser 750 may include a storage unit 770 that stores water formed by condensing water vapor discharged from the discharge line 700. The condenser condenses water vapor discharged from the discharge line 700 to form water, and the formed water serves to dissolve and remove salt, which will be described later. Therefore, the formed water may be stored in a predetermined space, and a space may be required for the salt to come into contact with and dissolve in the water when it is discharged through the discharge line 700. However, the carbon dioxide electrolyzer of the present invention includes a storage unit 770 in the condenser 750 included in the discharge line 700, thereby storing the condensed water and dissolving the salt in the storage unit 770.

[0047] According to an embodiment of the present invention, the discharge line 700 may include a first line 710 through which the products and water vapor discharged from the discharge line 700 are transported from the carbon dioxide electrolysis cell 1000 to a condenser 750, and a second line 730 through which the products are discharged from the condenser 750 to the outside. The condenser 750 is included in the discharge line 700 connected to the carbon dioxide electrolysis cell 1000 and may serve to connect the first line 710 and the second line 730. The first line 710 may serve to transport products and water vapor generated by an electric reaction from the cathode 200 region to the condenser 750, where the water vapor may partially participate in the reaction and partially discharge the supplied water vapor. In addition, the second line 730 may serve to discharge the products and ions generated by dissolving the salt from the condenser 750 to the outside.

[0048] Meanwhile, in conventional carbon dioxide electrolyzers, discharge line 700-1 generally has a simple, straight pipe shape and is solely responsible for discharging the products of the electrolysis reaction. In contrast, in the carbon dioxide electrolyzer of the present invention, the discharge line 700 has a structure in which a condenser 750 is disposed between and connected to a first line 710 and a second line 730. This eliminates the need to dispose the condenser 750 in a separate space outside the discharge line 700, and not only allows products to be discharged to the outside without the need for multiple separate discharge lines 700, but also allows salt generated as a by-product during the electrolysis reaction to be removed.

[0049] According to an embodiment of the present invention, the condenser 750 may be connected to the first line 710 and the second line 730 so that a step is formed between them, and the second line 730 may be disposed higher than the first line 710 due to the step. In the carbon dioxide electrolysis apparatus of the present invention, the first line 710 and the second line 730 include a discharge line 700 having a step structure, so that the condenser 750 and the storage unit 770 can be simultaneously included in the discharge line 700 without the need to install additional space and devices in the discharge line 700.

[0050] Meanwhile, the discharge line 700-1 of a conventional carbon dioxide electrolyzer generally has a linear tubular structure for discharging the generated gaseous products to the outside. In contrast, the discharge line 700 of the carbon dioxide electrolyzer of the present invention connects the first line 710 connected to the carbon dioxide electrolysis cell 1000 and the second line 730 for discharging the products to the outside via the condenser 750. The second line 730 is positioned higher than the first line 710, providing a step, thereby functioning as a filter or inlet. Specifically, the products generated by the carbon dioxide electrolysis reaction may be carbon monoxide and hydrogen gas, and the products and unreacted carbon dioxide gas may be discharged together. Meanwhile, the salt generated as a by-product of the electrolysis is formed by ionic bonding between the cations of the electrolyte 400 and the carbon dioxide, and has a solid phase. Therefore, gaseous products generated by the electrolysis reaction can be discharged to the outside through the discharge line, and salt generated as a by-product during the electrolysis reaction cannot be discharged to the outside due to the step, but can be dissolved by contacting with the water in the storage unit 770. The height of the step may be such that the gaseous products can be discharged and the water generated by condensation of the water vapor can be stored and brought into contact with the salt, but is not limited thereto.

[0051] Carbon dioxide electrolysis method The carbon dioxide electrolysis method of the present invention includes a step (S1) of supplying gaseous carbon dioxide and water vapor to the cathode 200 of a carbon dioxide electrolysis cell 1000 including an anode 100, a cathode 200, an electrolyte 400, and a separation membrane 300; a step (S2) of electrolyzing the carbon dioxide supplied to the cathode 200 in the step (S1); a step (S3) of discharging the product produced by electrolysis in the step (S2) and the water vapor supplied in the step (S1) to the outside of the carbon dioxide electrolysis cell 1000; and a step (S4) of condensing the water vapor discharged in the step (S3).

[0052] According to one embodiment of the present invention, the water formed by condensing the discharged water vapor in step (S4) can dissolve the salt generated from the electrolyte 400 by electrolysis in step (S2).

[0053] Meanwhile, in conventional carbon dioxide electrolysis, cations contained in electrolyte 400-1 migrate to the cathode region through separation membrane 300-1 and react with supplied carbon dioxide to precipitate salt. The salt exists in solid form in catalyst layer 230-1 and gas diffusion layer 210-1 of the carbon dioxide electrolysis device and accumulates in supply line 500-1 and discharge line 700-1. This leads to reduced efficiency over longer periods of experimentation or research, limiting continuous experimentation or research over long periods of time and making it difficult to maintain a constant product production rate. Furthermore, removing the salt requires the installation of a separate salt removal device or water treatment device, or the use of direct salt removal methods, resulting in inefficient equipment and potentially increasing the volume of the device itself.

[0054] In order to solve the above problems, the method for electrolyzing carbon dioxide according to the present invention condenses the water vapor supplied together with the products produced by electrolysis and carbon dioxide to convert it into water when the water vapor is discharged, thereby effectively removing salt.

[0055] The method for electrolyzing carbon dioxide according to the present invention can condense the water vapor to produce water and dissolve and remove salts when discharging the products and water vapor, thereby eliminating the inconvenience of requiring a complex and separate device compared to the conventional method, and has the advantage of being simple and enabling continuous long-term experiments and research.

[0056] In addition, the method for electrolyzing carbon dioxide according to the present invention has an effect of increasing the amount of carbon dioxide supplied by supplying both carbon dioxide and water vapor, thereby increasing the amount of carbon monoxide produced, and has an effect of improving process efficiency because the supplied water vapor is used for condensation, eliminating the need to supply additional water to dissolve salt when discharging the product and water vapor.

[0057] According to one embodiment of the present invention, the salt may be generated by a reaction between the electrolyte 400 and the supplied carbon dioxide, and the salt may be KHCO3 or K2CO3. Specifically, in the method for electrolyzing carbon dioxide of the present invention, since KOH is used as the electrolyte, potassium ions can react with carbon dioxide to generate potassium carbonate salt.

[0058] While the present invention may be embodied in various different forms, it is to be understood that the invention is not limited to the specific embodiments set forth herein, and that the invention may be embodied in various different forms without departing from the spirit or scope of the present invention.

[0059] Example 1 As shown in Figure 1, a carbon dioxide electrolysis device was prepared to produce carbon monoxide by electrolytic reduction of carbon dioxide. The carbon dioxide electrolysis device included a condenser 750 in a discharge line 700, and the electrolysis of carbon dioxide was carried out by adjusting the operating conditions of the carbon dioxide electrolysis device as follows.

[0060] Reaction current density: 200mA / cm 2 (Constant current operation) Reaction voltage: 3~3.5V Reaction temperature: 40℃ Reaction pressure: 1 atm (normal pressure) Separation membrane: Anion exchange membrane (Sustainion X37, dioxide) Anode catalyst: RuO2+CeO2on Ni mesh Cathode catalyst: Ag powder Electrode area: 100cm2 Gas diffusion layer: Sigracet 39BB Anode electrolyte: 1M KOH (200ml / min) Cathode reactant: 40°C humidified CO2 gas (800 ccm) Transfer line type: parallel type Cross-sectional area of ​​transfer line: 0.55mm 2 During the electrolysis, the carbon monoxide conversion rate (%), the carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and the voltage were measured.

[0061] Example 2 Reaction current density: 300mA / cm 2 The same procedures as in Example 1 were carried out except that the temperature was set to 50°C, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during the electrolysis were measured.

[0062] Example 3 The same procedure as in Example 1 was carried out except that 1 M KHCO (200 ml / min) was used as the anode electrolyte, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during electrolysis were measured.

[0063] Example 4 The same procedure as in Example 1 was carried out, except that the shape of the transfer line was changed from a parallel type to a serpentine type with repeated "S" shapes. The CO conversion rate (%), CO Faraday efficiency (%), and voltage during electrolysis were measured.

[0064] Example 5 Reaction current density: 300mA / cm 2The same procedures as in Example 4 were carried out except that the temperature was set to 50°C, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during the electrolysis were measured.

[0065] Example 6 The cross-sectional area of ​​the transfer line is 0.75 mm 2 The same procedures as in Example 1 were carried out except for changing the above, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during the electrolysis were measured.

[0066] Example 7 Reaction current density: 300mA / cm 2 The same procedures as in Example 6 were carried out except that the temperature was set to 50°C, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during the electrolysis were measured.

[0067] Example 8 The carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage were measured in the same manner as in Example 1, except that the anode catalyst was changed from RuO2+CeO2 on Ni mesh to IrO2-Ti mesh.

[0068] Example 9 Reaction current density: 300mA / cm 2 The same procedures as in Example 8 were carried out except that the temperature was set to 50°C, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during the electrolysis were measured.

[0069] Comparative Example 1 The same procedure as in Example 1 was carried out except that no condensation section was included, and the carbon monoxide conversion rate (%), carbon monoxide Faraday efficiency (CO Faraday efficiency, %), and voltage during the electrolysis were measured.

[0070] *Measurement method (1) Carbon monoxide conversion rate (%) The conversion rate (%) was calculated as the ratio of carbon monoxide (CO) produced to the amount of carbon dioxide (CO2) gas input per hour.

[0071] (2) Faraday efficiency of carbon monoxide (%) The gas composition was measured by GC (Gas Chromatography) analysis in the exhaust line. product ) was calculated using the following formula:

[0072] [Formula 1] FE product (%)=(i product / i total )×100=[(V product ×Q×(2Fp / RT)) / i total ] x 100

[0073] In the above equation, Q is the flow rate in the exhaust line, F is the Faraday constant, p is the pressure, T is the measured temperature, and R is the ideal gas constant. total ) is the value of the total current applied over time, and the current to the product (i product ) is the volume of gas measured by GC analysis (V product ) is the value calculated from

[0074] (3) Voltage (V) The application of current and the measurement of voltage were carried out using a VSP potentiostat manufactured by BioLogic. An 80 A booster was attached to apply a current corresponding to a large area. The current application was 100 mA / cm. 2 , 200mA / cm 2 , 300mA / cm 2 After maintaining the voltage for a predetermined time at each stage, the voltage was recorded after 10 minutes had elapsed. Gas chromatography (GC) analysis was also performed at the same time.

[0075] [Table 1]

[0076] Referring to Table 1, Comparative Example 1, which does not include a condenser in the discharge line, exhibits inferior results in terms of carbon monoxide conversion rate, carbon monoxide faradaic efficiency, and voltage compared to Examples 1 to 6, which include a condenser. Furthermore, Example 4 exhibits a similar carbon monoxide conversion rate to Comparative Example 1, but exhibits superior results in terms of carbon monoxide faradaic efficiency and voltage. These results confirm that by providing a condenser in the discharge line and removing salt, it is possible to maintain a high carbon monoxide conversion rate and carbon monoxide faradaic efficiency without overvoltage.

[0077] 3 to 6 are graphs showing the change in voltage over time in Examples 1 to 6, and FIG. 7 is a graph showing the change in voltage over time in Comparative Example 1. Referring to FIGS. 3 to 7, it was confirmed that in Comparative Example 1, the supply line and discharge line were clogged with salt generated during electrolysis, causing abnormalities in supply and flow, resulting in a sudden change in voltage over time. In contrast, it was confirmed that in each Example, the change in voltage over time was not large, and carbon monoxide conversion was carried out smoothly. [Explanation of symbols]

[0078] 100 anodes 200 cathode 210 Gas diffusion layer 230 Catalyst layer 300 Separation membrane 400 electrolytes 1000 Carbon Dioxide Electrolysis Cell 500 Supply Lines 600 Transfer Line 700 discharge line 710 First Line 730 Second Line 750 condensation section 770 Storage Unit 100-1 Anode of conventional carbon dioxide electrolysis device 200-1 Cathode of conventional carbon dioxide electrolysis device 210-1 Gas diffusion layer of conventional carbon dioxide electrolysis device 230-1 Catalyst layer of conventional carbon dioxide electrolysis device 300-1 Separation membrane of conventional carbon dioxide electrolysis device 400-1 Electrolyte of conventional carbon dioxide electrolysis device 1000-1 Conventional Carbon Dioxide Electrolysis Device Carbon Dioxide Electrolysis Cell 500-1 Conventional carbon dioxide electrolysis equipment supply line 600-1 Transfer line for conventional carbon dioxide electrolysis equipment 700-1 Conventional carbon dioxide electrolysis device discharge line

Claims

1. a carbon dioxide electrolysis cell including an anode, a cathode, an electrolyte, and a separation membrane disposed between the anode and the cathode; a supply line for supplying gas phase carbon dioxide and water vapor to the cathode; and an exhaust line for exhausting products and water vapor generated by the electrolysis reaction of the carbon dioxide in the carbon dioxide electrolysis cell to the outside of the cell, The carbon dioxide electrolysis device, wherein the exhaust line includes a condensation section that condenses water vapor exhausted from the exhaust line.

2. The carbon dioxide electrolysis apparatus according to claim 1 , wherein the gas-phase carbon dioxide is supplied in a state containing the water vapor.

3. 3. The carbon dioxide electrolysis device according to claim 1, wherein the temperature of the steam supplied through the supply line is 40° C. to 60° C.

4. The carbon dioxide electrolysis device according to claim 1 or 2, wherein the condensation section is exposed to the outside of the carbon dioxide electrolysis cell.

5. The carbon dioxide electrolysis device according to claim 1 or 2, wherein the condensation unit includes a storage unit for storing water formed by condensing the water vapor discharged from the discharge line.

6. The discharge line is a first line through which the product and water vapor discharged from the discharge line are transported from the carbon dioxide electrolysis cell to a condenser; The carbon dioxide electrolysis apparatus according to claim 1 or 2, further comprising: a second line through which the product is discharged from the condensation section to the outside.

7. The carbon dioxide electrolysis device according to claim 6 , wherein the condenser is connected to the first line and the second line such that a step is formed between the first line and the second line.

8. The carbon dioxide electrolysis device according to claim 7 , wherein the second line is disposed higher than the first line by the step.

9. A step (S1) of supplying gaseous carbon dioxide and water vapor to a cathode of a carbon dioxide electrolysis cell including an anode, a cathode, an electrolyte, and a separation membrane; A step (S2) of electrolyzing the carbon dioxide supplied to the cathode in the step (S1); A step (S3) of discharging the product produced by electrolysis in the step (S2) and the water vapor supplied in the step (S1) to the outside of the carbon dioxide electrolysis cell; and (S4) condensing the water vapor discharged in the step (S3).

10. The method for electrolyzing carbon dioxide according to claim 9, wherein the water formed by condensing the water vapor discharged in step (S4) dissolves salt generated from the electrolyte by electrolysis in step (S2).

11. The method for electrolyzing carbon dioxide according to claim 10, wherein the salt is produced by a reaction between an electrolyte and supplied carbon dioxide.

12. The salt is KHCO ３ and K. ２ CO ３ The method for electrolyzing carbon dioxide according to claim 10 or 11,

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