Electrolysis device and electrolysis method

Abstract

The invention relates to an electrolysis device and an electrolysis method. A decrease in electrolysis efficiency is suppressed. This electrolysis device is provided with: an electrolysis unit; a cathode supply flow path through which a cathode supply fluid of a gas containing carbon dioxide flows; an anode supply flow path through which an anode supply fluid containing water flows; and a cathode discharge flow path through which a cathode discharge fluid containing a carbon compound and carbon dioxide flows. A cathode flow rate adjuster for adjusting the flow rate A of the cathode supply fluid; an anode flow rate adjuster for adjusting the flow rate B of the anode supply fluid; a first flow rate meter for measuring the flow rate C of the cathode supply fluid; a second flow rate meter for measuring the flow rate D of the anode supply fluid; the control device estimates the value of the Faraday efficiency in accordance with a relational expression in which the value of the Faraday efficiency of the carbon compound approximates a function including the flow rate C and the flow rate D, and controls the flow rate A by controlling the cathode flow rate adjuster on the basis of the estimated value of the Faraday efficiency.

Description

[0001] This application is based on Japanese Patent Application No. 2024-44763 (filing date: March 21, 2024), and claims the benefit of priority from the aforementioned application, the entire contents of which are incorporated herein by reference. Technical Field

[0002] Embodiments of the present invention relate to electrolysis devices and electrolysis methods. Background Art

[0003] In recent years, concerns about the depletion of fossil fuels such as oil and coal have led to a surge in expectations for sustainable renewable energy sources. Examples of renewable energy sources include solar cells and wind power generation. However, since their power generation depends on weather and natural conditions, ensuring a stable power supply is challenging. Consequently, efforts have been made to stabilize the power generated by renewable energy by storing it in batteries. However, this storage of power presents challenges, such as the cost of batteries and the resulting losses during storage.

[0004] In this regard, attention has been paid to electrolysis devices that use electricity generated from renewable energy to electrolyze water (H2O) to produce hydrogen (H2) from water, or electrochemically reduce carbon dioxide (CO2) to convert it into chemical substances (chemical energy) such as carbon compounds such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH3OH), methane (CH4), acetic acid (CH3COOH), ethanol (C2H5OH), ethane (C2H6), and ethylene (C2H4). When these chemical substances are stored in gas cylinders or tanks, the energy storage cost can be reduced compared to storing electricity (electrical energy) in batteries, and there is also the advantage of less storage loss. As an electrolysis device for carbon dioxide, for example, an electrolysis device that uses a silver nanoparticle catalyst at the cathode to reduce carbon dioxide to convert it into carbon monoxide has been developed. Summary of the Invention

[0005] The problem to be solved by the present invention is to suppress the reduction in electrolysis efficiency.

[0006] The electrolysis device of the embodiment comprises: an electrolysis unit having a cathode for reducing carbon dioxide to generate a carbon compound, an anode for oxidizing water to generate oxygen, a cathode flow path facing the cathode, and an anode flow path facing the anode; a cathode supply flow path connected to an inlet of the cathode flow path, through which a cathode supply fluid containing a gas of the carbon dioxide is supplied to the cathode flow path and flows; an anode supply flow path connected to an inlet of the anode flow path, through which an anode supply fluid containing water is supplied to the anode flow path and flows; a cathode discharge flow path connected to an outlet of the cathode flow path, through which a cathode discharge fluid containing the carbon compound and the carbon dioxide is discharged from the cathode flow path and flows; a cathode discharge flow path connected to the outlet of the anode flow path, through which flows an anode discharge fluid discharged from the anode flow path and containing the oxygen and the water; a cathode flow regulator that regulates a flow rate A of the cathode supply fluid supplied to the cathode flow path; an anode flow regulator that regulates a flow rate B of the anode supply fluid supplied to the anode flow path; a first flow meter that measures a flow rate C of the cathode discharge fluid discharged from the cathode flow path; a second flow meter that measures a flow rate D of the anode discharge fluid discharged from the anode flow path; and a control device that receives measurement data of the flow rate C from the first flow meter and measurement data of the flow rate D from the second flow meter. The control device uses the measurement data of the flow rates C and D to estimate a value of the Faraday efficiency of the carbon compound according to a relationship formula that approximates the value of the Faraday efficiency to a function containing the flow rates C and D, and controls the cathode flow regulator based on the estimated value of the Faraday efficiency to thereby control the flow rate A. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram for explaining a configuration example of an electrolysis device according to an embodiment.

[0008] Figure 2 It is a schematic diagram showing a modified example of the electrolysis device according to the embodiment.

[0009] Figure 3 It is a schematic diagram showing a modified example of the electrolysis device according to the embodiment.

[0010] Figure 4 To show FE CO A plot of y versus x.

[0011] Figure 5 To show FE CH4 A plot of y versus x.

[0012] Figure 6 To show FE C2H4 A plot of y versus x.

[0013] Figure 7 To show FE C2H6 A plot of y versus x.

[0014] Figure 8 To show FE CO A plot of y versus x.

[0015] Figure 9 To show FE CH4 A plot of y versus x.

[0016] Figure 10 To show FE C2H4 A plot of y versus x.

[0017] Figure 11 To show FE C2H6 A plot of y versus x.

[0018] (Explanation of Reference Numerals)

[0019] 1...Electrolysis device, 100...Electrolysis unit, 111...Anode, 112...Anode flow path, 113...Anode current collector, 114...Flow path plate, 121...Cathode, 122...Cathode flow path, 123...Cathode current collector, 124...Flow path plate, 131...Separator, 150...Power supply, 151...Flow meter, 152...Flow meter, 153...Temperature detector, 200...Anode supply unit, 201...Anode collector, 202...Anode flow regulator, 203...Anode pressure regulator Entire device, 300…cathode supply part, 301…supply source, 302…cathode flow regulator, 303…cathode pressure regulator, 400…cathode discharge part, 401…cathode collector, 500…control part, 501…control device, 600…back-end part, 601…back-end device, 602…hydrogen supply source, 701…energy converter, 702…energy converter, A…flow rate, B…flow rate, C…flow rate, CA…flow rate, CB…flow rate, D…flow rate, HA…flow rate DETAILED DESCRIPTION

[0020] The following describes an electrolysis device according to an embodiment with reference to the accompanying drawings. In the various embodiments described below, substantially identical components are denoted by the same reference numerals, and their descriptions may be partially omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of thickness of various components, and other aspects may differ from actual results.

[0021] In addition, in this specification, "connected" includes not only direct connection but also indirect connection in some cases, unless otherwise specified.

[0022] Figure 1 It is a schematic diagram for explaining a configuration example of an electrolysis device according to an embodiment. Figure 11 shows an electrolysis device 1. The electrolysis device 1 includes an electrolysis unit 100, an anode supply unit 200, a cathode supply unit 300, a cathode discharge unit 400, and a control unit 500.

[0023] The electrolysis unit 100 includes an anode 111, an anode flow path 112, an anode current collector 113, a cathode 121, a cathode flow path 122, a cathode current collector 123, and a separator 131. The anode 111, anode flow path 112, cathode 121, cathode flow path 122, and separator 131 constitute an electrolysis unit. Examples of electrolysis units include carbon dioxide electrolysis units. The electrolysis unit 100 may also include a unit stack formed by stacking multiple electrolysis units. For example, the multiple electrolysis units may be clamped by a pair of support plates and further secured with bolts or the like.

[0024] The anode supply unit 200 includes an anode collector 201 , an anode flow rate regulator 202 , and an anode pressure regulator 203 .

[0025] The cathode supply unit 300 includes a supply source 301 , a cathode flow rate regulator 302 , and a cathode pressure regulator 303 .

[0026] The cathode discharge portion 400 includes a cathode collector 401 .

[0027] The control unit 500 includes a control device 501 .

[0028] The anode 111 is connected to the separator 131. The anode 111 is an electrode for oxidizing the oxidation target (the substance to be oxidized) to generate an oxidation product. The anode 111 is an electrode for oxidizing the water of the oxidation target to generate oxygen (O2), hydrogen ions (H + ), or the hydroxide ions (OH - ) is oxidized to produce oxygen and water.

[0029] The anode 111 preferably includes a catalyst material (anode catalyst material) that can reduce the overvoltage of the oxidation reaction. Such catalyst materials include, for example, metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys containing these metals, intermetallic compounds, binary metal oxides such as manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), ruthenium oxide (Ru-O), lithium oxide (Li-O), and lanthanum oxide (La-O), ternary metal oxides such as Ni-Co-O, Ni-Fe-O, La-Co-O, Ni-La-O, and Sr-Fe-O, quaternary metal oxides such as Pb-Ru-IrO and La-Sr-Co-O, and metal complexes such as Ru complexes and Fe complexes.

[0030] The anode 111 includes a structure that enables liquid and ions to move between the separator 131 and the anode flow path 112, such as a base material with a porous structure such as a mesh material, a punching material, a porous body, a metal fiber sintered body, etc. The base material can be composed of metal materials such as titanium (Ti), nickel (Ni), iron (Fe), alloys containing at least one of these metals (such as SUS), etc., and can also be composed of the above-mentioned anode catalyst material. When an oxide is used as the anode catalyst material, it is preferred to attach or stack the anode catalyst material on the surface of the base material composed of the above-mentioned metal material to form a catalyst layer. As far as the anode catalyst material is concerned, in terms of improving the oxidation reaction, it is preferred to have nanoparticles, nanostructures, nanowires, etc. The so-called nanostructure is a structure with nano-scale concave and convex surfaces formed on the surface of the catalyst material.

[0031] The cathode 121 is connected to the separator 131. The cathode 121 is an electrode (reduction electrode) for causing a reduction reaction of a reduction target (a substance to be reduced) to produce a reduction product. Examples of the reduction target include carbon dioxide. Examples of reduction products include carbon compounds and ammonia. Examples of carbon compounds include carbon monoxide, formic acid (HCOOH), ethane, ethylene, methanol, acetic acid (CH3COOH), ethanol, propanol (C3H7OH), and ethylene glycol (C2H6O2). The reduction reaction at the cathode 121 may include a reduction reaction of the reduction target and a side reaction of water to produce hydrogen (H2).

[0032] The cathode 121 has a gas diffusion layer and a cathode catalyst layer provided on the gas diffusion layer. A porous layer denser than the gas diffusion layer may be provided between the gas diffusion layer and the cathode catalyst layer. The gas diffusion layer is provided on the cathode flow path 122 side, and the cathode catalyst layer is provided on the separator 131 side. The cathode catalyst layer may enter the gas diffusion layer. The cathode catalyst layer preferably has catalyst nanoparticles, catalyst nanostructures, etc. The gas diffusion layer is composed of, for example, carbon paper, carbon cloth, etc., and may be subjected to water-repellent treatment. The porous layer is composed of a porous body having a pore size smaller than that of the carbon paper or carbon cloth.

[0033] By applying appropriate water-repellent treatment to the gas diffusion layer, the reducing target gas reaches the cathode catalyst layer primarily through gas diffusion. The reduction reaction of the reducing target and the resulting carbon compounds occur near the boundary between the gas diffusion layer and the cathode catalyst layer, or near the cathode catalyst layer after it has entered the gas diffusion layer.

[0034] As far as the cathode catalyst layer is concerned, when carbon dioxide is reduced, it is preferably composed of a catalyst material (cathode catalyst material) that can reduce the overvoltage of the above-mentioned reduction reaction. Examples of such materials include, for example, gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), tin (Sn) and other metals, alloys containing at least one of these metals, metal materials such as intermetallic compounds, carbon (C), graphene, CNT (carbon nanotubes), fullerenes, carbon materials such as Ketjen black, Ru complexes, Re complexes and other metal complexes. For the cathode catalyst layer, various shapes such as plate, mesh, wire, particle, porous, film, and island can be applied.

[0035] The cathode catalyst material constituting the cathode catalyst layer preferably comprises nanoparticles of the aforementioned metal material, nanostructures of the metal material, nanowires of the metal material, or a composite of the aforementioned metal material nanoparticles supported on a carbon material such as carbon particles, carbon nanotubes, or graphene. By using catalyst nanoparticles, catalyst nanostructures, catalyst nanowires, or catalyst nanosupported structures as the cathode catalyst material, the efficiency of the reduction reaction of the reduction target at the cathode 121 can be improved.

[0036] The anode flow path 112 faces the anode 111 . The anode flow path 112 has a function of allowing an anode solution containing an oxidation target to flow and supplying the oxidation target to the anode 111 .

[0037] The anode solution is preferably a solution containing at least water (H2O) of the oxidizing target. Since the reducing target is supplied from the cathode flow path 122, the anode solution may or may not contain the reducing target.

[0038] The anode solution may be an electrolyte solution containing an electrolyte. Examples of the electrolyte solution include a hydroxide ion (OH - ), hydrogen ions (H + ), potassium ion (K + ), sodium ion (Na + ), lithium ion (Li + ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), nitrate ions (NO3 - ), sulfate ion (SO4 2- ), phosphate ions (PO4 2- ), borate ion (BO3 3- ), and bicarbonate ions (HCO3 -) is an aqueous solution of at least one of the following. In order to reduce the resistance of the anode solution, an alkaline solution in which an electrolyte such as potassium hydroxide or sodium hydroxide is dissolved at a high concentration is preferably used as the liquid. However, if the reduction target dissolves in the anode solution, the anode solution may gradually become neutral. In order to continuously carry out the electrolytic reaction, a large amount of alkaline solution is required, so there is a concern about corrosiveness and there are problems with sustainability. Therefore, if an electrolyte near neutrality is used, the reduction target such as carbon dioxide is saturated, and an electrolyte of the same pH can be used.

[0039] Anode flow path 112 is provided on the surface of flow plate 114. Flow plate 114 is made of, for example, a material with low chemical reactivity and no electrical conductivity. Examples of such materials include insulating resins such as acrylic resin, polyetheretherketone (PEEK), and fluororesin. Flow plate 114 has threaded holes (not shown) for fastening.

[0040] The cathode flow path 122 faces the cathode 121 . The cathode flow path 122 has a function of allowing cathode gas containing a reduction target to flow and supplying the reduction target to the cathode 121 .

[0041] The cathode flow path 122 is provided on the surface of a flow path plate 124. The flow path plate 124 is preferably made of a material with low chemical reactivity and high electrical conductivity. Examples of such materials include metals such as Ti and SUS, and carbon. The flow path plate 124 has an inlet and outlet for the cathode flow path 122 (not shown), as well as threaded holes for fastening. Furthermore, spacers (not shown) may be interposed between the front and rear of each flow path plate as needed.

[0042] Separator 131 includes an ion exchange membrane that allows ions to move between anode 111 and cathode 121 and separates anode 111 from cathode 121. Examples of ion exchange membranes include cation exchange membranes such as Nafion and Flemion, and anion exchange membranes such as Neosepta and Selemion. In addition to ion exchange membranes, separator 131 may also include a glass filter, a porous polymer membrane, a porous insulating material, or the like, as long as the material allows ions to move between anode 111 and cathode 121.

[0043] Anode 111 and cathode 121 can be connected to power supply 150. Examples of power supply 150 are not limited to conventional system power supplies or batteries, but can also include power sources that supply electricity generated by renewable energy sources such as solar cells and wind power. Power supply 150 can further include a power controller that adjusts the output of the power supply and controls the voltage between anode 111 and cathode 121. It should be noted that power supply 150 can be located external to electrolysis device 1.

[0044] The inlet of the anode flow path 112 is connected to the anode supply flow path P1. The outlet of the anode flow path 112 is connected to the anode discharge flow path P2. The anode supply flow path P1 and the anode discharge flow path P2 are formed by, for example, piping.

[0045] The inlet of the cathode flow path 122 is connected to the cathode supply flow path P3. The outlet of the cathode flow path 122 is connected to the cathode discharge flow path P4. The cathode supply flow path P3 and the cathode discharge flow path P4 are formed by, for example, piping.

[0046] The temperature of the electrolysis unit 100 can be measured using a temperature regulator 153 provided in the electrolysis apparatus 1. The temperature regulator 153 can measure the apparent temperature of the electrolysis cell. The temperature regulator 153 can be provided in contact with the electrolysis cell or connected to the electrolysis cell.

[0047] As the reaction proceeds in the electrolysis unit 100, heat is generated and the temperature rises. The temperature rise needs to be controlled within a certain range to maintain optimal operating conditions for the electrolyte membrane and unit components. Therefore, a cooling device for cooling the electrolysis unit 100 may be provided in the temperature regulator 153. For example, the electrolysis unit 100 can be cooled by controlling the cooling device using the control unit 500 based on the temperature detected by the temperature regulator 153. The temperature regulator 153 may include a heater that can be controlled by the control unit 500 based on the detected temperature to heat the electrolysis unit 100.

[0048] The anode collector 201 is connected to the anode discharge flow path P2. The anode collector 201 includes an anode tank capable of storing the anode fluid discharged from the anode flow path 112 and flowing through the anode discharge flow path P2, and an anode gas-liquid separator that separates the anode fluid into anode drain and anode exhaust. The anode drain contains an anode solution. The anode drain returns to the anode supply flow path P1 via a circulation flow path P5 connecting the anode supply flow path P1 and the anode discharge flow path P2, and is reused as an anode solution. The anode exhaust contains oxidation products and water vapor. The anode exhaust may contain unreacted oxidized substances.

[0049] The anode flow rate regulator 202 is provided midway in the anode supply flow path P1 and includes, for example, a pump, and controls the flow rate (anode inlet flow rate: flow rate B) of the anode supply fluid supplied to the anode flow path 112 via the anode supply flow path P1.

[0050] The anode pressure regulator 203 is provided in the middle of the anode discharge flow path P2 . The anode pressure regulator 203 controls the pressure of the anode flow path 112 by controlling the pressure of the anode discharge flow path P2 .

[0051] The flow rate of the anode exhaust fluid discharged from the anode flow path 112 can be measured using a flow meter 151 provided in the electrolysis apparatus 1. The flow meter 151 can measure the flow rate of the anode exhaust fluid discharged from the anode flow path 112 (anode outlet flow rate: flow rate D). The flow meter 151 can be provided after the anode flow path 112 and before the anode pressure regulator 203. The flow meter 151 can be provided midway along the anode exhaust flow path P2 and can be connected to the anode exhaust flow path P2.

[0052] The supply source 301 includes, for example, a cylinder chamber capable of containing a cathode supply fluid containing a reduction target. The cathode supply fluid contains, for example, carbon dioxide gas. The cathode supply fluid can contain water vapor by humidifying the carbon dioxide gas.

[0053] The cathode flow rate regulator 302 is provided midway in the cathode supply flow path P3 and includes, for example, a pump, and can control the flow rate of the cathode supply fluid supplied to the cathode flow path 122 (cathode inlet flow rate: flow rate A).

[0054] The cathode pressure regulator 303 is provided in the middle of the cathode discharge flow path P4. The cathode pressure regulator 303 can control the pressure of the cathode flow path 122 by controlling the pressure of the cathode discharge flow path P4.

[0055] The flow rate of the cathode exhaust fluid discharged from the cathode flow path 122 can be measured using a flow meter 152 provided in the electrolysis apparatus 1. The flow meter 152 can measure the flow rate of the cathode exhaust fluid discharged from the cathode flow path 122 (cathode outlet flow rate: flow rate C). The flow meter 152 can be provided at the rear section of the cathode flow path 122 and before the cathode pressure regulator 303. The flow meter 152 can be provided midway along the cathode exhaust flow path P4 and can be connected to the cathode exhaust flow path P4.

[0056] Cathode collector 401 is connected to cathode discharge flow path P4. Cathode collector 401 includes a tank capable of storing cathode fluid discharged from cathode flow path 122 and flowing through cathode discharge flow path P4, and a gas-liquid separator that separates the cathode fluid into cathode discharge liquid and cathode exhaust gas. The cathode exhaust gas contains reduction products, hydrogen gas from side reactions, and water vapor. The cathode discharge liquid may contain anode solution. The cathode discharge liquid may also contain unreacted reduction products.

[0057] Cathode exhaust Figure 2 As shown, it can be supplied from the cathode collector 401 to the rear section 600 . Figure 2 It is a schematic diagram showing a modified example of the electrolysis device according to the embodiment. Figure 2 The electrolysis device 1 shown is Figure 1 Compared with the electrolysis device 1 shown in FIG, the difference is that it has a rear section 600. For other parts, the Figure 1 The following is a description of the electrolysis device 1. The subsequent stage 600 includes a subsequent stage device 601 and a hydrogen supply source 602.

[0058] The post-stage device 601 is provided at the post-stage of the electrolysis device 1. The post-stage device 601 can generate compounds by chemically reacting carbon compounds and hydrogen contained in the cathode exhaust fluid. Examples of the post-stage device 601 include chemical synthesis reaction devices such as water electrolysis devices and hydrogen generators.

[0059] The control device 501 receives detection signals from, for example, the flowmeter 151, the flowmeter 152, and the temperature regulator 153, and sends a control signal to the anode flow regulator 202. The control device 501 is electrically connected to each component via a bidirectional signal line, a portion of which is omitted from the figure, to control them together. It should be noted that valves and pumps (not shown) are provided in each piping, and the opening and closing actions of the valves and pumps can be controlled by signals from the control device 501. The control device 501 can be connected to the subsequent device 601. The control device 501 can be connected to at least one of the power supply 150, the anode pressure regulator 203, the cathode pressure regulator 303, and the temperature regulator 153.

[0060] The control device 501 is, for example, Figure 3 As shown, it can be connected to the anode pressure regulator 203, the anode flow regulator 202, the hydrogen supply source 602, etc. Figure 3 This is a schematic diagram showing a modified example of the electrolysis device of the embodiment. Figure 2 Description.

[0061] The control device 501 can collect data representing at least one of the electrical cell outputs such as cell voltage, cell current, cathode potential, and anode potential, the pressure and pressure loss of the cathode flow path 122 , and the pressure and pressure loss of the anode flow path 112 .

[0062] The control device 501 can be configured using hardware such as a processor, etc. Each operation can be performed by storing each operation as an operation program in a computer-readable recording medium such as a memory and then appropriately reading the operation program stored in the recording medium using hardware.

[0063] Electrolysis device 1 such as Figure 3 As shown, there may be an energy converter 701 and an energy converter 702 . Figure 3 This is a schematic diagram showing a modified example of the electrolysis device. Figure 2 Description of the electrolysis device 1 shown.

[0064] Energy converter 701 is located midway along the anode exhaust flow path P2. Energy converter 701 can be located before or after the anode flow regulator 202. Energy converter 701 includes, for example, gears. Energy converter 701 can extract kinetic energy from the anode exhaust fluid flowing through anode exhaust flow path P2 and convert it into electrical energy or rotational energy.

[0065] Energy converter 702 is located midway along cathode exhaust flow path P4. Energy converter 702 can be located before or after cathode flow regulator 302. Energy converter 702 includes, for example, gears. Energy converter 702 can extract kinetic energy from cathode exhaust fluid flowing through cathode exhaust flow path P4 and convert it into electrical energy or rotational energy.

[0066] Next, an example of an electrolysis method using the electrolysis apparatus 1 will be described. In the example of the electrolysis method, the anode flow regulator 202 and the anode pressure regulator 203 are controlled to supply an anode supply fluid to the anode flow path 112 via the anode supply flow path P1. The cathode flow regulator 302 and the cathode pressure regulator 303 are controlled to supply a cathode supply fluid from the supply source 301 to the cathode flow path 122 via the cathode supply flow path P3. A voltage is applied between the anode current collector 113 and the cathode current collector 123 by the power supply 150, and current is supplied to the electrolysis unit via the anode 111 and the cathode 121.

[0067] When current flows through the anode 111 and the cathode 121, an oxidation reaction occurs near the anode 111 and a reduction reaction occurs near the cathode 121 as shown below. Here, the case where carbon dioxide as a reduction target is reduced to generate carbon monoxide (CO) as a reduction product is described. However, the reduction product is not limited to carbon monoxide and may be other carbon compounds such as the organic compounds mentioned above. In addition, as a reaction process using an electrolytic cell, it is considered that hydrogen ions (H + ) and the main generated hydroxide ions (OH - ), but is not limited to any one of these reaction processes.

[0068] For the oxidation of water (H2O) to generate hydrogen ions (H + ) will be described. If current is supplied between the anode 111 and the cathode 121, an oxidation reaction of water (H2O) occurs at the anode 111 in contact with the anode solution flowing in the anode flow path 112. Specifically, as shown in the following formula (1), the H2O contained in the anode solution is oxidized to generate oxygen (O2) and hydrogen ions (H + ).

[0069] 2H2O→4H + +O2+4e - …(1)

[0070] The H generated at the anode 111 + The electrons (e) are moved in the cathode gas in the cathode flow path 122 through the anode 111 and the separator 131 and arrive near the cathode 121. - ) and H moved to the vicinity of the cathode 121 + , a reduction reaction of carbon dioxide (CO2) occurs. Specifically, as shown in the following formula (2), CO2 contained in the cathode gas supplied from the cathode flow path 122 to the cathode 121 is reduced to generate CO.

[0071] 2CO2+4H + +4e - →2CO+2H2O…(2)

[0072] Secondly, for the reduction of carbon dioxide (CO2) to generate hydroxide ions (OH - ) is described below. If current is supplied between the anode 111 and the cathode 121, water (H2O) and carbon dioxide (CO2) are reduced near the cathode 121 to generate carbon monoxide (CO) and hydroxide ions (OH - ). Hydroxide ion (OH - ) diffuses to the vicinity of the anode 111, as shown in the following formula (4), the hydroxide ions (OH - ) is oxidized to produce oxygen (O2).

[0073] 2CO2+2H2O+4e - →2CO+4OH - …(3)

[0074] 4OH - →2H2O+O2+4e - …(4)

[0075] As mentioned above, if the electrolysis device is operated for a long time, hydrogen is produced through side reactions. The amount of hydrogen produced may increase depending on operating conditions such as the temperature of the electrolysis cell, the amount of current flowing through the electrolysis cell, the operating time, and the start-up and shutdown periods. Therefore, it is necessary to adjust the operating conditions of the electrolysis cell according to changes in the Faradaic efficiency.

[0076] Furthermore, the flow rates of the carbon compound and hydrogen supplied to the device installed in the subsequent device 601 need to be adjusted according to the flow rates of hydrogen and carbon compounds generated by the electrolysis unit. Therefore, in order to measure the Faraday efficiency of each component, it is considered to measure the composition of the generated gas, but this has the problem of expensive measuring equipment and increased cost of the entire system.

[0077] Furthermore, a pump for supplying fluid to the electrolytic cell requires energy to operate, which reduces its efficiency as an energy conversion device.

[0078] The electrolysis device 1 adopts a control device 501, which uses the measurement data of the flow rate D (anode outlet flow rate) from the flow meter 151 and the measurement data of the flow rate C (cathode outlet flow rate) from the flow meter 152 to estimate parameters such as the Faraday efficiency. When the estimated value of the parameter does not meet the required standard when operating the electrolysis device 1, the operating condition of the electrolysis device 1 is changed. An example of the operation of changing the operating condition includes controlling the cathode flow regulator 302 to change the flow rate A. By controlling the operating conditions, it is possible to restore the output of the electrolysis unit, for example. In addition, by controlling the operating conditions, it is possible to detect abnormalities in the electrolysis reaction in the electrolysis unit and stop the operation of the electrolysis unit. Therefore, it is possible to suppress the reduction of the electrolysis efficiency.

[0079] The Faraday efficiency FE of carbon monoxide CO and the Faraday efficiency FE of hydrogen H2 The Faraday efficiency can generally be calculated using gas chromatography or infrared spectroscopy, by mixing with a gas containing oxygen, burning it with a catalyst such as platinum, and measuring the resulting temperature. Alternatively, it can be calculated using parameters such as the voltage and current supplied to the electrolysis cell, the cell temperature, the gas-liquid separation performance between the anode flow path 112 and the cathode flow path 122 (i.e., the amount of fluid such as liquid or gas transferred between the anode flow path 112 and the cathode flow path 122), the amount of product gas, and the voltage difference with a reference electrode. While it is possible to comprehensively predict the Faraday efficiency using these parameters, accurate determination is difficult.

[0080] When carbon dioxide is reduced to generate carbon monoxide in the electrolysis unit 100 , the same molar amount of carbon dioxide as the generated amount of carbon monoxide moves from the cathode flow path 122 to the anode flow path 112 .

[0081] For example, when carbon monoxide is produced, a two-electron reaction causes the same molar amount of carbon dioxide to move to the anode flow path 112. When methane or ethylene is produced, a six-electron reaction causes 3 moles of carbon dioxide to move to the anode flow path 112. When ethane is produced, an eight-electron reaction causes half the number of electrons used to reduce 4 moles of carbon dioxide to move to the anode flow path 112.

[0082] The total current value (total reaction current value) I flowing through the electrolysis cells or cell groups in the electrolysis unit 100 can be calculated by current density×electrode area×number of stacked cells.

[0083] The amount of carbon monoxide produced (flow rate) can be calculated by the total current value (total reaction current value) I (A) × 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) × FE CO Calculated. 60 (s) is the value used to calculate coulombs from the current value × time (s (seconds)). Since the generated amount is calculated using the flow rate (ccm), it is included for unit conversion. 22400 (cc / mol) represents the volume per 1 mole of gas.

[0084] The amount of hydrogen generated (flow rate) can be calculated by I(A)×60(s) / 96500(c / mol) / 2(number of reaction electrons)×22400(cc / mol)×(1-FE CO ) is calculated.

[0085] The amount (flow rate) of carbon dioxide moving to the anode flow path 112 can be calculated by I(A)×60(s) / 96500(c / mol) / 2(number of reaction electrons)×22400(cc / mol)×FE CO Figure it out.

[0086] The amount (flow rate) of oxygen generated by the anode 111 can be calculated by total current value (A)×60 (s) / 96500 (c / mol) / 22400 (cc / mol).

[0087] The amount (flow rate) of carbon dioxide supplied to the cathode flow path 122 needs to be twice the amount converted to carbon monoxide, which can be calculated by total current value (A)×60(s) / 96500(c / mol) / 2(number of reaction electrons)×22400(cc / mol)×2.

[0088] The remaining carbon dioxide flow rate a is obtained by subtracting the flow rate of carbon dioxide required for conversion to carbon monoxide from the flow rate of carbon dioxide contained in the cathode supply fluid supplied to the cathode flow path 122 .

[0089] The action based on the flow rates C and D can be determined from these flow rate ratios. Taking the value x obtained by dividing the flow rate D by the value obtained by subtracting the flow rate a from the flow rate C, x can be calculated as x=D / (Ca).

[0090] At this time, the Faraday efficiency FE of carbon monoxide CO As shown below, it is possible to use FE CO The relationship equation that approximates a quadratic function involving x is inferred.

[0091] FE CO =14.778x 2 -99.006x+205.41

[0092] The theoretical value of the flow rate of carbon dioxide required for the reduction reaction can be calculated by multiplying the total current value by 13.93, but FE CO When reducing, the cathode flow regulator 302 is controlled by the control device 501 so as to reduce the flow rate A according to the amount of the product. Among the gas components containing carbon monoxide and hydrogen, it is preferable for the hydrocarbon generator in the subsequent device 601 to reduce the amount of carbon dioxide.

[0093] However, if the flow rate A is reduced, the reaction becomes a strict condition, and sometimes FE CO Therefore, by CO When the flow rate A is further increased, the reaction becomes mild and the FE can be maintained. CO .

[0094] FE CO When x is 1.0 (100%), it is 1.33. CO The reduction of x Figure 4 Therefore, if the electrolysis unit is operated under the condition that the constant times (x-1.33) is added to the theoretical amount of carbon dioxide, then for FE CO If 1 times (x-1.33) is added, the effect is apparent, but if it is less than that, almost no effect is obtained. On the other hand, if more than 10 times (x-1.33) is added, the cathode exhaust fluid is excessively diluted, and for example, a carbon dioxide separation process is required for use in the reaction in the subsequent device 601, or the reaction efficiency of the subsequent device 601 is reduced, so it is not preferred. Therefore, it is preferred that the control device 501 is controlled by the FE CO The cathode flow regulator 302 is controlled based on the estimated value of , so that the flow rate A satisfies the equation represented by I × 13.93 + (x - 1.33) × 1 ≤ A ≤ I × 13.93 + (x - 1.33) × 10. 13.93 is a value calculated from 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) × 2.

[0095] This relationship holds true when the reduction product is carbon monoxide gas, a two-electron reaction. However, this relationship may no longer hold true when a liquid product is generated as the reduction product, or when multiple reaction products are generated in large proportions. This applies to situations where the reduction reaction primarily produces a gaseous component and a single reduction product. Furthermore, if the Faraday efficiency of a single reduction product is not 90% or higher, errors in this relationship are likely to increase.

[0096] Next, the Faraday efficiency FE is estimated when the reduction product is methane with an 8-electron reaction. CH4 In the case where the reduction product is methane, the reaction is based on CO2+8H + +8e - →CH4+2H2O represents the reaction. For one molecule of carbon dioxide, eight electrons are required to generate one molecule of methane. From the cathode flow path 122, four molecules of carbon dioxide move to the anode flow path 112. At this time, FE CH4 As shown below, it is possible to use FE CH4 The relationship equation that approximates a quadratic function involving x is inferred.

[0097] FE CH4 =12.053x 2 -73.921x+152.92

[0098] FE CH4 When FE is 1.0 (100%), x is 0.83. CH4 The reduction of x Figure 5 Therefore, if the operation is carried out under the condition that the constant times (x-0.83) is added to the theoretical amount of carbon dioxide, then for FE CH4 Therefore, it is preferred that the control device 501 is controlled by the FE CH4 The cathode flow regulator 302 is controlled based on the estimated value of , thereby controlling the flow rate A to satisfy the formula represented by I×13.93+(x-0.83)×1≤A≤I×13.93+(x-0.83)×12.

[0099] In the case of carbon monoxide in a two-electron reaction, it is 10 times (x-1.33), but in the case of methane in an eight-electron reaction, the change in Faraday efficiency and the rate of increase of x are different from those of carbon monoxide, so if more than 12 times (x-1.33) are added together, the cathode exhaust fluid is excessively diluted and is not preferred. This ratio is more than 10 times that of the two-electron reaction, but the separation of methane and carbon dioxide is easier than the separation of carbon monoxide and carbon dioxide, so it is preferably 12 times rather than 10 times. Methane is easy to liquefy and can be easily separated by liquefaction using a cryogenic method or the like. In the case of a ratio greater than this, the cathode exhaust fluid is excessively diluted, and for example, a carbon dioxide separation process is required in order to be used for the reaction in the subsequent device 601, or the reaction efficiency of the subsequent device 601 is reduced, so it is not preferred.

[0100] Next, the Faraday efficiency FE when the reduction product is estimated to be ethylene with 6 electrons C2H4 In the case where the reduction product is ethylene, the reaction is based on 2CO2+12H+ +12e - →C2H4+4H2O represents the reaction. For one molecule of carbon dioxide, six electrons are required to generate one molecule of ethylene. From the cathode flow path 122, three molecules of carbon dioxide move to the anode flow path 112. At this time, FE C2H4 As described below, it is possible to make FE C2H4 The relationship equation that approximates a quadratic function involving x is inferred.

[0101] FE C2H4 =12.317x 2 -73.313x+157.79

[0102] FE C2H4 When x is 1.0 (100%), it is 0.89. C2H4 The reduction of x Figure 6 Therefore, if the operation is carried out under the condition that the constant times (x-0.89) is added to the theoretical amount of carbon dioxide, then for FE C2H4 Therefore, it is preferred that the control device 501 is controlled by the FE C2H4 The cathode flow regulator 302 is controlled based on the estimated value of , thereby controlling the flow rate A to satisfy the formula represented by I×13.93+(x-0.89)×1≤A≤I×13.93+(x-0.89)×12.

[0103] In the case of ethylene, a six-electron reaction, the change in Faradaic efficiency with the rate of increase of x differs from that of carbon monoxide. Therefore, if the sum exceeds 12 times (x - 0.89), the cathode exhaust fluid is excessively diluted, which is not preferred. Separation of ethylene from carbon dioxide is easier than separation of carbon monoxide from carbon dioxide, so a ratio of 12 times, rather than 10 times, is preferred. A ratio greater than this is not preferred because the cathode exhaust fluid is diluted, requiring a carbon dioxide separation step for use in the subsequent reaction in the device 601, or reducing the reaction efficiency of the subsequent device 601.

[0104] Next, the Faraday efficiency FE is estimated when the reduction product is ethane with 8 electrons. C2H6 In the case where the reduction product is ethane, the reaction is based on 2CO2+16H + +16e - →C2H6+4H2O represents the reaction. For one molecule of carbon dioxide, eight electrons are required to generate one molecule of ethane. Four molecules of carbon dioxide move from the cathode flow path 122 to the anode flow path 112. At this time, FE C2H6 As described below, it is possible to make FE C2H6The relationship equation that approximates a quadratic function involving x is inferred.

[0105] FE C2H6 =12.053x 2 -73.921x+152.91

[0106] FE C2H6 When FE is 1.0 (100%), x is 0.83. C2H6 The reduction of x Figure 7 Therefore, if the operation is carried out under the condition that the constant times (x-0.83) is added to the theoretical amount of carbon dioxide, then for FE C2H6 Therefore, it is preferred that the control device 501 is controlled by the FE C2H4 The cathode flow regulator 302 is controlled based on the estimated value of , thereby controlling the flow rate A to satisfy the formula represented by I×13.93+(x-0.83)×1≤A≤I×13.93+(x-0.83)×12.

[0107] In the case of ethane, which undergoes an 8-electron reaction, the change in Faraday efficiency differs from the rate of increase of x in comparison to carbon monoxide. Therefore, if the sum exceeds 12 times (x - 0.83), the cathode exhaust fluid is excessively diluted, which is not preferred. Since the separation of ethane and carbon dioxide is easier than that of carbon monoxide and carbon dioxide, a factor of 12 is preferred, rather than 10. A factor greater than this dilution is not preferred because the cathode exhaust fluid is diluted, requiring a carbon dioxide separation step for use in the subsequent reaction in the device 601, or reducing the reaction efficiency of the subsequent device 601.

[0108] In order to more accurately measure flow C and flow D, it is preferred to measure the volume flow of the substance (material flow, in other words, molar flow). It is difficult to measure the flow of a fluid in which the ratio of each component is not determined, such as a mixture of carbon compounds such as carbon monoxide, hydrogen, carbon dioxide, and oxygen.

[0109] Fluid flow rates can typically be measured using instruments such as soap film flowmeters and cylinder-type volumetric flowmeters. However, these instruments are bulky, expensive, complex to operate, and difficult to automatically measure, making them difficult to install. Because the anode flow path 112 forms a double-layer flow of gas and electrolyte, the flow velocity can be determined by measuring the large amounts of gas and liquid flowing through the path, thereby calculating the fluid volumetric flow rate. In this case, a flowmeter is preferably installed upstream of the anode collector 201, such as a catch tank, which separates the anode discharge fluid into a gas-liquid separation zone.

[0110] On the other hand, the cathode exhaust fluid sometimes contains water vapor at the same temperature as the temperature of the electrolysis unit. The unit temperature is higher than the ambient temperature due to the heat of reaction, so if it is not kept warm, the water vapor condenses in the piping and changes into liquid. Therefore, it is possible to detect the liquid flowing in the large amount of gas flowing in the piping along the anode 111, find its flow rate, and thus calculate the volume flow rate. In this case, it is necessary to calculate the saturated water vapor amount from the piping temperature and remove the water vapor flow rate from the flow rate of the cathode exhaust fluid. In this case, it is preferred to set a flow meter at the front section of the cathode collector 401 having a capture tank or the like for gas-liquid separation of the cathode exhaust fluid discharged from the cathode flow path 122.

[0111] However, it is difficult to determine the volume flow rate of the fluid. In this regard, there is a thermal mass flowmeter as a flowmeter that can easily determine the flow rate. The thermal mass flowmeter has a thermal mass sensor used internally. The thermal mass flowmeter measures the temperature of at least one point before and after a heater installed in at least one flow path or bypass section. Due to the flow velocity of the fluid, a temperature difference is generated, so the flow velocity can be determined from the temperature difference and the flow rate can be calculated. Thermal mass flowmeters generally use an element whose resistance changes with temperature, and the resistance difference before and after the element is detected using a bridge circuit to determine the flow rate. In the case of a bypass, the diversion ratio is calculated to determine the overall flow rate. However, this method has the problem that it cannot be used if the gas species is different, and is manufactured based on nitrogen. In the case of different gas species, it can be adjusted using the value of the conversion factor (CF) that represents the difference in flow rate caused by the gas species. The CF of hydrogen and the CF of carbon monoxide are 1.0, the same as the CF of nitrogen, and the CF of carbon dioxide is 0.74.

[0112] Thermal mass flow meters can measure even when the gas species are different, but they cannot measure fluids containing multiple components if the composition ratios are different. This makes them inapplicable in cases where the composition ratio of the cathode discharge fluid varies, such as in a carbon dioxide electrolysis cell.

[0113] Electrolysis apparatus 1 has the following conditions: the amount of carbon monoxide produced is equal to the mass of carbon dioxide transferred to anode flow path 112; the CF of the other products (hydrogen and oxygen) is 1.0, the only gas species with a different CF is carbon dioxide; and all products are gases. Therefore, thermal mass flowmeters can be used for flowmeters 151 and 152, and flow rates C and D can be measured using the thermal mass flowmeters. The Faraday efficiency of carbon compounds can be estimated using the measurement data of flow rates C and D.

[0114] When the carbon compound is carbon monoxide, the flow rate CA of carbon dioxide contained in the cathode exhaust fluid is calculated using a nitrogen-based thermal mass flow meter using the following formula.

[0115] CA = (total current value (A) × 60 (s) / 96500 (c / mol) / 2 × 22400 (cc / mol) × FE CO +a)×0.74

[0116] When a nitrogen-based thermal mass flow meter is used, the flow rate CB of carbon dioxide flowing from the cathode flow path 122 to the anode flow path 112 is calculated using the following formula.

[0117] CB=(total current value (A)×60(s) / 96500(c / mol) / 2×22400(cc / mol)×FE CO +a)×0.74

[0118] At this time, FE CO As shown below, it is possible to use FE CO The relationship equation that approximates a quadratic function involving x is inferred.

[0119] FE CO =16.857x 2 -113.03x+225.17

[0120] In this way, even when using a thermal mass flowmeter, the Faraday efficiency of the carbon compound can be estimated. The theoretical amount of carbon dioxide required for the reduction reaction can be calculated using 1×13.93. However, when the Faraday efficiency decreases, the cathode flow regulator 302 is controlled by the control device 501 so that the amount of carbon dioxide is increased according to the amount of carbon compound. This maintains the Faraday efficiency of the carbon compound, thereby suppressing a decrease in electrolysis efficiency.

[0121] In FE CO When CF is 1.0 (100%), the x obtained by calculating the flow rate measured by the thermal mass flow meter is 1.40. CO The reduction of x Figure 8 Therefore, if the operation is carried out under the condition that the constant times x-1.40 is added to the theoretical amount of carbon dioxide, then for FE CO If 1 times of x-1.40 is added, the effect is apparent, but if it is less than that, almost no effect is obtained. On the other hand, if more than 7 times of (x-1.40) are added, the cathode exhaust fluid is excessively diluted, and for example, a carbon dioxide separation process is required for use in the reaction in the subsequent device 601, or the reaction efficiency of the subsequent device 601 is reduced, which is not preferred. Therefore, it is preferred that the control device 501 is controlled by the FE COThe cathode flow regulator 302 is controlled based on the estimated value of , thereby controlling the flow rate A to satisfy I×13.93+(x-1.40)×1≤A≤I×13.93+(x-1.40)×7.

[0122] Next, for the FE when the carbon compound is assumed to be methane CH4 In the case of methane, the carbon compound is generated by CO2+8H + +8e - →CH4+2H2O. 8 electrons are required for 1 molecule of carbon dioxide to generate 1 molecule of methane. 4 molecules of carbon dioxide move from the cathode flow path 122 to the anode flow path 112. In addition, the CF of methane is 0.74. At this time, FE CH4 As shown below, it is possible to use FE CH4 The relationship equation that approximates a quadratic function involving x is inferred.

[0123] FE CH4 =46.722x 2 -220.93x+296.9

[0124] In FE CH4 When x is 1.0 (100%), it is 1.19. CH4 The reduction of x Figure 9 Therefore, if the operation is carried out under the condition that the constant times (x-1.19) is added to the theoretical amount of carbon dioxide, then for FE CH4 Therefore, it is preferred that the control device 501 is controlled by the FE CH4 The cathode flow regulator 302 is controlled based on the estimated value of , thereby controlling the flow rate A to satisfy the formula represented by I×13.93+(x-1.19)×1≤A≤I×13.93+(x-1.19)×12.

[0125] In the case of methane, which undergoes an 8-electron reaction, the change in Faraday efficiency and the rate of increase of x differ from those of carbon monoxide. Therefore, if the sum exceeds 12 times (x - 0.83), the cathode exhaust fluid will be excessively diluted, which is not preferred. For example, methane is easily liquefied and can be easily separated by liquefaction using cryogenic methods. Exceeding this ratio dilutes the cathode exhaust fluid, requiring a carbon dioxide separation step for use in the subsequent reaction in the device 601, or reducing the reaction efficiency of the subsequent device 601, which is not preferred.

[0126] Next, for the case where the carbon compound is assumed to be ethylene, C2H4 In the case of ethylene with 6 electrons, when the carbon compound is ethylene, the reaction based on 2CO2+12H+ +12e - →C2H4+4H2O. 6 electrons are required for 1 molecule of carbon dioxide to generate 1 molecule of ethylene. 3 molecules of carbon dioxide move from the cathode flow path 122 to the anode flow path 112. In addition, the CF of ethylene is 0.64. At this time, FE C2H4 As shown below, it is possible to use FE C2H4 The relationship equation that approximates a quadratic function involving x is inferred.

[0127] FE C2H4 =27.031x 2 -167.8x+296.12

[0128] FE C2H4 When x is 1.0 (100%), it is 1.56. C2H4 The reduction of x Figure 10 Therefore, it is preferable to operate the system under the condition that a constant multiple of (x-1.56) is added to the theoretical amount of carbon dioxide in order to maintain the Faraday efficiency. C2H4 The cathode flow regulator 302 is controlled based on the estimated value of , thereby controlling the flow rate A to satisfy the formula represented by I×13.93+(x-1.56)×1)≤A≤I×13.93+(x-1.56)×8.

[0129] In the case of ethylene, which undergoes a six-electron reaction, the change in Faraday efficiency and the rate of increase of x differ from those of carbon monoxide. Therefore, if the sum exceeds 8 times (x - 1.56), the cathode exhaust fluid will be excessively diluted, which is not preferred. Since the separation of ethylene from carbon dioxide is easier than that of carbon monoxide, an 8-fold rather than a 7-fold is preferred.

[0130] Next, the Faraday efficiency FE when the carbon compound is estimated to be ethane C2H6 In the case of ethane, the carbon compound is ethane, which is based on the reaction of 2CO2+16H + +16e - →C2H6+4H2O represents the reaction. 8 electrons are required for 1 molecule of carbon dioxide to generate 1 molecule of ethane. 4 molecules of carbon dioxide move from the cathode flow path 122 to the anode flow path 112. In addition, the CF of ethane is 0.51. At this time, FE C2H6 As shown below, it is possible to use FE C2H6 The relationship equation that approximates a quadratic function involving x is inferred.

[0131] FE C2H6 =49.875x2 -227.47x+295.07

[0132] FE C2H6 When x is 1.15, the FE C2H6 The reduction of x Figure 11 Therefore, if the operation is carried out under the condition that the constant times (x-1.15) is added to the theoretical amount of carbon dioxide, then for FE C2H6 It is preferable to control in the range of I×13.93+(x-1.15)×1 to I×13.93+(x-1.15)×8.

[0133] In the case of ethane, which undergoes an 8-electron reaction, the change in Faraday efficiency and the rate of increase of x differ from those of carbon monoxide. Therefore, if the sum exceeds 8 times (x - 1.15), the cathode exhaust fluid is excessively diluted, which is not preferred. Since the separation of ethane from carbon dioxide is easier than that of carbon monoxide, an 8-fold rather than a 7-fold is preferred.

[0134] As described above, since the Faraday efficiency can be estimated using the measurement data of flow rates C and D, if the side reaction is primarily hydrogen and the total Faraday efficiency, including hydrogen from the main reaction and side reactions, is 0.8 (80%) or less, it can be determined that there is an abnormality in the electrolysis reaction or an abnormality in the electrolysis device 1. Possible causes of a drop below 80% include the generation of unexpected hydrogen as a side reaction, the generation of substances other than the main product, electrolytic corrosion (electrocorrosion) of the anode 111 and cathode 121, and crossover of substances between the anode flow path 112 and cathode flow path 122. Crossover involves, for example, a reaction in which the generated hydrogen gas moves back to the anode flow path 112, is oxidized at the anode 111, and is converted back into water. The current consumed by this reaction leads to a decrease in the total Faraday efficiency.

[0135] When the carbon compound is carbon monoxide, the amount (flow rate) of generated carbon monoxide can be calculated using the following formula.

[0136] Amount of carbon monoxide generated = total current value (A) × 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) × FE CO

[0137] The amount (flow rate) of generated hydrogen can be calculated using the following formula.

[0138] Amount of hydrogen generated = total current value (A) × 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) × (1-FECO )

[0139] The flow rate C can be calculated using the following formula.

[0140] Flow rate C = Flow rate A - Flow rate of carbon dioxide converted to carbon monoxide + Flow rate of generated carbon monoxide - Flow rate of carbon dioxide moving to the anode flow path 112 + Flow rate of generated hydrogen

[0141] The flow rate of generated carbon monoxide = the flow rate of carbon dioxide moving to the anode flow path 112. The flow rate of carbon dioxide converted into carbon monoxide = the flow rate of generated carbon monoxide. Based on these relationships, the flow rate C can be calculated using the following formula.

[0142] Flow rate C = Flow rate A - Flow rate of carbon dioxide moving to the anode flow path 112 + Flow rate of generated hydrogen

[0143] On the other hand, the flow rate D can be calculated using the flow rate of carbon dioxide moving to the anode flow path 112 + the flow rate of generated oxygen. The flow rate of generated oxygen is half the flow rate of generated carbon monoxide.

[0144] Since the flow rate of generated carbon monoxide equals the flow rate of carbon dioxide flowing to the anode flow path 112, and the flow rate of generated oxygen is half the flow rate of carbon monoxide, the flow rate D can be calculated by multiplying the flow rate of carbon dioxide flowing to the anode flow path 112 by 1.5 and adding half the flow rate of generated hydrogen, i.e., the flow rate of oxygen for hydrogen generation. Furthermore, the difference between the cathode supply fluid and the cathode discharge fluid (cathode flow rate increase) can be calculated by subtracting the flow rate of carbon dioxide flowing to the anode flow path 112 from the flow rate of generated hydrogen.

[0145] However, the total Faradaic efficiency FE of the reduction products generated by the electrolysis unit is TOTAL When it is 80%, the flow rate CB of carbon dioxide moving to the anode flow path 112 can be calculated using the following formula.

[0146] CB = total current value (A) × 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) × FE TOTAL ×0.8

[0147] The flow rate HA of generated hydrogen can be calculated using the following formula: FE RP is the Faradaic efficiency of the carbon compound.

[0148] HA = total current value (A) × 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) × (1-FE RP )×0.8

[0149] Since the flow rate of generated carbon monoxide = the flow rate of carbon dioxide moving to the anode flow path 112 , the flow rate C can be calculated using the following formula.

[0150] Flow rate C = Flow rate A - Flow rate of carbon dioxide converted to carbon monoxide + Flow rate of generated carbon monoxide - Flow rate of carbon dioxide moving to the anode flow path 112 + Amount of generated hydrogen

[0151] The amount of increase in the flow rate of the cathode exhaust fluid relative to the cathode supply fluid (cathode flow rate increase Cinout) can be calculated by subtracting the flow rate of carbon dioxide that has moved to the anode flow path 112 from the flow rate of generated hydrogen.

[0152] Furthermore, since 60(s) / 96500(c / mol) / 2(number of reaction electrons)×22400(cc / mol)=6.9637(cc / min×c), Cinout can be calculated using the following formula.

[0153] Cinout = (total current value I (A) × 6.9637 (cc / min × c) × FE H2 )-(total current value I(A)×6.9637(cc / min×c)×FE CO )=I(A)×6.9637(cc / min×c)×(FE H2 -FE CO )

[0154] On the other hand, the flow rate D can be calculated using the following formula.

[0155] D=(total current value I(A)×6.9637(cc / min×c)×(1 / 2)×(FE H2 +FE CO ))

[0156] +(Total current value I(A)×6.9637(cc / min×c)×FE CO )=Total current value I(A)×6.9637(cc / min×c)×(1 / 2)×(FE H2 +(3 / 2×FE CO )))

[0157] According to the above relationship, FE, which is the sum of the Faraday efficiency of hydrogen and the Faraday efficiency of carbon monoxide, is TOTAL It can be calculated using the following formula.

[0158] FE TOTAL =FE H2 +FE CO=(((Cinout+A×2) / 2×I(A)×6.9637(cc / min

[0159] ×c)

[0160] Thus, the control device 501 can estimate FE using the measurement data of the flow rate C and the measurement data of the flow rate D. TOTAL . Thus, for example, FE TOTAL When it is 0.8 (80%) or less, it is determined that an abnormal reaction has occurred, and, for example, the control device 501 can be used to stop the operation of the electrolysis unit.

[0161] For example, the control device 501 preferably stops the operation of the electrolysis unit when the value calculated using the following formula is 0.8 or less.

[0162] (Increase in cathode flow rate + D) / total reaction current value in the electrolysis unit / 60 (s) / 96500 (cc / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) / 1.5

[0163] The value calculated above is equivalent to FE TOTAL .

[0164] Next, consider the case of using a conventional mass flow controller capable of measuring nitrogen, air, etc. Since the CF of the mass flow controller for hydrogen is 1.0 and the CF of carbon dioxide is 0.74, the Faraday efficiency can be estimated considering only this.

[0165] When considering the inlet of an electrolysis cell or electrolysis device (system) as volumetric flow rate, the calculation can be performed assuming the CF of the carbon dioxide at the outlet of the electrolysis cell or electrolysis device (system) is 0.74. When considering the flow rate of a thermal mass flow controller with nitrogen inlet and an air-based CF of 1.0, the CF of the carbon dioxide at the outlet is 0.74. Since it is a single-component gas, it can be considered as a volumetric flow rate. However, since the outlet gas is a mixed gas with different CFs, each component must be considered.

[0166] The flow rate C can be calculated using the following formula.

[0167] Flow rate C=flow rate A−flow rate of carbon dioxide converted to carbon monoxide+flow rate of generated carbon monoxide−flow rate of carbon dioxide moved to the anode flow path 112+flow rate Cinout of generated hydrogen can be calculated using the following formula.

[0168] Cinout = Flow rate of generated hydrogen - Flow rate of carbon dioxide moving to the anode flow path 112

[0169] However, regarding the measurement value obtained by using a thermal mass flow controller, it is necessary to consider CF regarding the flow rate of the reduced carbon dioxide gas.

[0170] Therefore, Cinout can be calculated using the following formula.

[0171] Cinout=(I(A)×6.9637(cc / min×c)×FE H2 )-(CF×I(A)

[0172] ×6.9637(cc / min×c)×FE CO )=I(A)×6.9637(cc / min×c)×(FE H2 -(CF×FE CO ))

[0173] On the other hand, the flow rate D is calculated. The CF of oxygen is 1.0.

[0174] The flow rate of generated oxygen can be calculated using the following formula.

[0175] Oxygen flow rate = I(A)×6.9637(cc / min×c)×(1 / 2)×(FE H2 +FE CO) )

[0176] The flow rate of carbon dioxide moving from the cathode flow path 122 can be calculated using the following formula.

[0177] Flow rate of carbon dioxide moving from cathode flow path 122 = I(A)×6.9637(cc / min×c)×FE CO

[0178] Furthermore, the flow rate of carbon dioxide flowing from the cathode flow path 122 , measured using a thermal mass flow controller, can be calculated using the following formula.

[0179] Flow rate of carbon dioxide moving from the cathode flow path 122 = I(A)×6.9637(cc / min×c)×CF×FE CO

[0180] From these relationships, the flow rate D can be calculated using the following formula.

[0181] D=(total current value I(A)×6.9637(cc / min×c)×(1 / 2)×(FE H2 +FE CO) ))

[0182] +(Total current value I(A)×6.9637(cc / min×c)×CF×FE CO)=(I(A)×6.9637(cc / min×c)×((1 / 2)×FE H2 +((1 / 2)+CF)×FE CO )

[0183] The value obtained by subtracting the flow rate C measured by the thermal mass flow meter from the volume flow rate of the cathode supply fluid can be calculated using the following formula.

[0184] I(A)×6.9637(cc / min×c)×(1+3×CF)×FE CO

[0185] On the other hand, the value of flow rate D measured by a thermal mass flow meter minus the value of flow rate C measured by a thermal mass flow meter from the volume flow rate of the cathode supply fluid (flow path A) × (0.5 + CF) can be calculated using the following formula.

[0186] I(A)×6.9637(cc / min×c)×(2 / 3+CF)×FE H2 )

[0187] From these relationships, the following relationship holds.

[0188] FE TOTAL =FE CO +FE H2 (Value of flow rate D measured by a thermal mass flowmeter × 2 - Value obtained by subtracting the value of flow rate C measured by a thermal mass flowmeter from the volumetric flow rate of the cathode supply fluid) / I(A) × 6.9637 (cc / min × c) × (2 / 3 + CF) + Value of flow rate D measured by a thermal mass flowmeter - Value obtained by subtracting the value of flow rate C measured by a thermal mass flowmeter from the volumetric flow rate of the cathode supply fluid / I(A) × 6.9637 (cc / min × c) × (1.5 + CF)

[0189] If the CF of carbon dioxide is set to 0.74, then FE TOTAL It can be calculated using the following formula.

[0190] FE TOTAL =(Flow rate D measured by a thermal mass flowmeter × 6.22) - (Value obtained by subtracting the flow rate C measured by a thermal mass flowmeter from the volumetric flow rate of the cathode supply fluid × 0.0824 / Total reaction current in the electrolysis cell / 60 (s) / 96500 (cc / mol) / 2 (Number of reaction electrons) × 22400 (cc / mol) × 3.898)

[0191] As described above, the control device 501 can estimate FE using the measurement data of the flow rate C and the measurement data of the flow rate D. TOTAL , for example, in FE TOTAL If the estimated value of is 0.8 or less, it is determined that an abnormal reaction has occurred, and the control device 501 can be used to perform operations such as stopping the operation of the electrolysis unit.

[0192] When the carbon compound is methane, the flow rate of generated methane can be calculated using the following formula from the relationship: flow rate of generated methane × 4 = flow rate of carbon dioxide moving to the anode flow path 112 .

[0193] Flow rate of generated methane = total current value I (A) × 60 (s) / 96500 (cc / mol) / 8 (number of reaction electrons) × 22400 (cc / mol) × FE CH4

[0194] When the carbon compound is ethylene, the flow rate of generated ethylene × 3 = the flow rate of carbon dioxide moving to the anode flow path 112 . Therefore, the flow rate of generated ethylene can be calculated using the following formula.

[0195] Ethylene flow rate generated = total current value I (A) × 60 (s) / 96500 (cc / mol) / 6 (number of reaction electrons) × 22400 (cc / mol) × FE C2H4

[0196] When the carbon compound is ethane, the flow rate of generated ethane can be calculated using the following formula from the relationship: flow rate of generated ethane × 4 = flow rate of carbon dioxide moving to the anode flow path 112 .

[0197] Flow rate of generated ethane = I(A) × 60(s) / 96500(cc / mol) / 8(number of reaction electrons) × 22400(cc / mol) × FE C2H6

[0198] In addition, if the number of reaction electrons is N, the flow rate of the generated carbon compound can be calculated using the following formula.

[0199] Carbon compound flow rate = total current value I (A) × 60 (s) / 96500 (c / mol) / N (number of reaction electrons) × FE RP

[0200] In the two-electron reaction, the flow rate of generated hydrogen can be calculated using the following formula.

[0201] Flow rate of generated hydrogen = total current value I (A) × 6.9637 (cc / min × c) × (1-FE H2 )

[0202] In the case of methane, the flow rate C can be calculated using the following formula.

[0203] Flow rate C = Flow rate A - Flow rate of carbon dioxide converted to methane + Flow rate of generated methane - Flow rate of carbon dioxide transferred to the anode flow path 112 + Flow rate of generated hydrogen

[0204] Furthermore, the flow rate of generated methane × 4 = the amount of carbon dioxide that moves to the anode flow path 112 , and the flow rate of carbon dioxide converted to methane = the flow rate of generated methane.

[0205] The flow rate of generated ethylene × 3 = the flow rate of carbon dioxide moving to the anode flow path 112 , and the flow rate of carbon dioxide converted to ethylene = the flow rate of generated ethylene.

[0206] In the case of ethylene, the flow rate C can be calculated using the following formula.

[0207] C = A - the flow rate of carbon dioxide converted to ethylene + the flow rate of generated ethylene - the flow rate of carbon dioxide transferred to the anode flow path 112 + the flow rate of generated hydrogen

[0208] Furthermore, the flow rate of generated ethane × 4 = the flow rate of carbon dioxide moving to the anode flow path 112 , and the flow rate of carbon dioxide converted to ethane = the flow rate of generated ethane.

[0209] The flow rate C can be calculated using the following formula.

[0210] C = A - the flow rate of carbon dioxide converted to methane + the flow rate of generated methane - the flow rate of carbon dioxide moving to the anode flow path 112 + the flow rate of generated hydrogen

[0211] On the other hand, in the case of methane, the flow rate D can be calculated from the sum of the flow rate of carbon dioxide flowing to the anode flow path 112 and the flow rate of generated oxygen. Since the flow rate of generated methane × 4 = the flow rate of carbon dioxide flowing to the anode flow path 112, and since the reaction of generated methane generates twice as much oxygen, the flow rate D can be calculated as the amount of carbon dioxide flowing to the anode flow path 112 × 1.5. Therefore, the following relationship holds true.

[0212] Flow rate D = total current value I (A) × 13.9278 (cc / min × c) / 2 (number of reaction electrons) × ((1 / 2) FE H2 +((1 / 2)(Number of Reaction Electrons)FE CH4 )+(8(number of reaction electrons) / 2×FE CH4 )

[0213] In the case of ethylene, the flow rate of generated ethylene × 3 = the flow rate of carbon dioxide moving to the anode flow path 112. Since the reaction of the generated ethylene generates three times the amount of oxygen, the flow rate A can be calculated using the equation: the amount of carbon dioxide moving to the anode flow path 112 × 2. Therefore, the following equation holds true.

[0214] Flow rate D = total current value I (A) × 13.9278 (cc / min × c) / 2 (number of reaction electrons) × ((1 / 2) FE H2 +(1 / 2)FE C2H4 +6(number of reaction electrons) / 2×FE C2H4 )

[0215] In the case of ethane, since the flow rate of generated ethane × 4 = the flow rate of carbon dioxide moving to the anode flow path 112, twice the amount of oxygen is generated in the reaction of the generated ethane, the flow rate D is calculated based on the amount of carbon dioxide moving to the anode flow path 112 × 1.5, and the following formula holds.

[0216] Flow rate D = total current value I (A) × 13.9278 (cc / min × c) / 2 (number of reaction electrons) × ((1 / 2) FE H2 +(1 / 2)FE C2H6 +8(number of reaction electrons) / 2×FE C2H6 )

[0217] When the number of reaction electrons of the carbon compound (RP) of carbon dioxide is N (N is a natural number), the flow rate D can be calculated using the following formula.

[0218] Flow rate D = total current value I (A) × 13.9278 (cc / min × c) / 2 (number of reaction electrons) × ((1 / 2) FE H2 +(1 / 2)FE RP +N(number of reaction electrons) / 2×FE RP )

[0219] Cinout can be calculated by the flow rate of generated hydrogen minus the flow rate of carbon dioxide moving to the anode flow path 112. However, in FE TOTAL When (here, the total value of the Faraday efficiency of hydrogen and the Faraday efficiency of the carbon compound) reaches 0.8, the flow rate of carbon dioxide moving to the anode flow path 112 can be calculated using the following formula.

[0220] Flow rate of carbon dioxide moving to the anode flow path 112 = I(A)×60(s) / 96500(c / mol) / N(number of reaction electrons)×22400(cc / mol)×FE RP ×0.8

[0221] The amount of generated hydrogen can be calculated using the following formula.

[0222] Amount of hydrogen generated = total current value I (A) × 60 (s) / 96500 (c / mol) / N (number of reaction electrons) × 22400 (cc / mol) × (1-FE RP )×0.8

[0223] Since the flow rate of the generated carbon compound = the flow rate of carbon dioxide moving to the anode flow path 112 , the flow rate C can be calculated using the following formula.

[0224] C=A-the flow rate of carbon dioxide converted into carbon compounds+the flow rate of generated carbon compounds-the flow rate of carbon dioxide moving to the anode flow path 112+the flow rate of generated hydrogen

[0225] Cinout can be calculated using the following formula.

[0226] Cinout = total current (A) × 13.9275 / 2 × FE H2 -I(A)×13.9275 / N

[0227] (Number of reaction electrons) × FE RP

[0228] In the case of carbon compounds, the flow rate D can be calculated using the following formula.

[0229] D = total current (A) × 13.9275 / 2 × ((1 / 2)FE H2 +(1 / 2)FE(Faraday efficiency of carbon compound)+N(number of reaction electrons) / 2×FE RP

[0230] In the case of a thermal mass flow controller, Cinout can be calculated using the following formula.

[0231] Cinout=(I(A)×13.9275 / 2×FE H2 )-(I(A)×13.9275 / N(reverse

[0232] (number of electrons) × FE RP ×CF)

[0233] In the case of a thermal mass flow controller, the flow rate D can be calculated using the following formula.

[0234] D=I(A)×13.9275 / 2×((1 / 2)FE H2 +(1 / 2)FE RP +N(reaction electrons

[0235] Number) / 2×FERP ×CF

[0236] In the case of a thermal mass flow controller, the following equation holds true.

[0237] D-(1 / 2)×Cinout=Total current (A)×13.9275 / 2×((1 / 2)×FE RP +N(number of reaction electrons) / 2×FE RP ×CF+(1 / 2)×N(number of reaction electrons)FE RP ×CF=total current (A)×13.9275×1 / 4×FE RP ×(1-N(number of reaction electrons)×CF+1 / N(number of reaction electrons)×CF

[0238] According to this relationship, FE RP It can be calculated using the following formula.

[0239] FE RP =4×(D-(1 / 2)×Cinout) / total current value (A)×13.9275×(1-N

[0240] (number of reaction electrons) × CF + 1 / N (number of reaction electrons) × CF) = 4 × (D - (1 / 2) × Cinout) / total current value (A) × 13.9275 × α

[0241] α=(1-N(number of reaction electrons)×CF+1 / N(number of reaction electrons)×CF)

[0242] In the case of methane with an 8-electron reaction, α = 9.125. In the case of a thermal mass flow controller, since CF = 0.74, α MFC =7.0125. In the case of ethylene with 6 electrons, α MFC =7.1666. In the case of a thermal mass flow controller, since CF = 0.64, α MFC =4.9466. In the case of ethane with 8 electrons, α MFC =9.125. In the case of a mass flow controller, since CF = 0.51, α MFC =5.14375.

[0243] In addition, in the case of thermal mass flow controllers, FE H2 It can be calculated using the following formula.

[0244] FE H2 = Cinout × 2 / total current value (A) × 13.9275 + CF / N (number of reaction electrons) × FE RP

[0245] By this relationship, by FE H2 and FE CO The total value of FE TOTAL It can be calculated using the following formula.

[0246] FE TOTAL =FE H2 +FE CO = Cinout × 2 / total current value (A) × 13.9275 + CF / N (number of reaction electrons) × FE RP +4×(D-(1 / 2)×Cinout) / total current (A)×13.9275×α

[0247] As described above, the control device 501 can estimate FE using the measurement data of the flow rate C and the measurement data of the flow rate D. TOTAL . Thus, for example, in FE TOTAL When it is 0.8 (80%) or less, it is determined that an abnormal reaction has occurred in the electrolysis device 1 , and the control device 501 can be used to perform operations such as stopping the operation of the electrolysis unit.

[0248] Furthermore, if Figure 3 As shown, by providing energy converters 701 and 702, the kinetic energy of the anode exhaust fluid and the cathode exhaust fluid can be used to drive the anode flow regulator 202 to supply the anode supply fluid and the cathode flow regulator 302 to supply the cathode supply fluid. This reduces the overall energy consumption of the electrolysis device and improves efficiency. Specifically, gears or the like can be provided as energy converters 701 and 702 to generate kinetic energy.

[0249] At this time, the kinetic energy can be temporarily converted into electrical energy, and the electrical energy can be converted into kinetic energy again to drive the anode flow regulator 202 and the cathode flow regulator 302 .

[0250] In addition, all of the kinetic energy can not be used for the drive of the anode flow regulator 202 and the cathode flow regulator 302, which reduces the change efficiency. According to this value, a certain proportion of kinetic energy is reduced for driving. When the kinetic energy is used for the supply of the anode supply fluid, the anode supply fluid of a flow rate sufficient for the reaction can be supplied, so even if the ratio changes, the impact is also very small, so it will not be a problem. If the flow of the anode supply fluid is reduced, even if it is excessive in stoichiometry, the performance degradation caused by the reduction of the contact area of ​​the catalyst surface caused by the oxygen sometimes produced also becomes a problem, but it can be solved by measures such as increasing the specific surface area of ​​the catalyst. For example, a material hardened by a non-woven fabric of titanium, a granular layer of titanium, sintering, etc. can be used.

[0251] On the other hand, changes in the amount of gas supplied to the cathode significantly impact performance. When Faraday efficiency decreases, increasing flow rate A can stabilize it. Flow rate A is calculated by multiplying the total of flow rates C and D by 0.7. Table 1 shows examples of calculation results for flow rate A and flow rate C + flow rate D, assuming the cathode supply fluid is supplied.

[0252]

Table 1

[0253] FE A(ccm) C+D(ccm) 100％ 10.70 14.49 95％ 11.05 14.97 90％ 11.45 15.51 85％ 11.85 16.06 80％ 12.25 16.59 75％ 12.60 17.08 70％ 13.00 17.62 65％ 13.40 18.16 60％ 13.80 18.70 55％ 14.20 19.24 50％ 14.60 19.78

[0254] As shown in Table 1, by reducing flow rate A based on the sum of flow rates C and D when the Faraday efficiency decreases, the flow rate of carbon dioxide in the cathode exhaust fluid is reduced. Reducing the flow rate of carbon dioxide, as a component of carbon monoxide and hydrogen, is preferable for the hydrocarbon generator utilized in the downstream device 601. However, reducing flow rate A leads to stricter reaction conditions, further reducing the Faraday efficiency. Therefore, by increasing flow rate A when the Faraday efficiency decreases, the reaction conditions are controlled to milder conditions, thereby maintaining the Faraday efficiency. This can suppress the decrease in electrolysis efficiency. It should be noted that using 70% of the kinetic energy of the anode and cathode exhaust fluids to supply the cathode supply fluid is a result of consideration of the reduction in efficiency.

[0255] In this way, the flow rate A can be controlled without measuring the Faraday efficiency using analytical equipment such as a gas chromatograph. Furthermore, the Faraday efficiency can be estimated using the control device 501 using the measurement data of the flow rates C and D. Therefore, it is not necessary to have equipment for measuring the Faraday efficiency, and it is not necessary to separately provide equipment for controlling the flow rate A, which is preferable.

[0256] The control device 501 preferably uses a value calculated using the following formula, for example:

[0257] I×6.964×(100-14.778x 2 -99.006x+205.41)

[0258] The flow rate of hydrogen generated by the electrolysis device 1 is calculated, and the hydrogen supply source 602 is controlled. Based on the calculated hydrogen flow rate, the flow rate of the fluid containing hydrogen supplied from the hydrogen supply source 602 to the subsequent device 601 is reduced. The above value is equivalent to, for example, FE H2 For example, the flow rate of the fluid containing hydrogen supplied to the subsequent device 601 is reduced from the FE initially assumed at the start of operation in the hydrogen supply source 602. TOTAL The flow rate of the part that is reduced by 100%. That is, due to I (total current value) × 6.964 × 100-FE RPSince the flow rate of hydrogen partially increases, it is preferable to correct this portion.

[0259] Example

[0260] (Comparative Example 1, Example 1 (Carbon Monoxide))

[0261] Assembly with Figure 1 The electrolysis performance of the electrolysis device with the structure shown was examined. In the electrolysis unit, a cathode was used in which carbon particles loaded with gold nanoparticles were coated on carbon paper with a porous layer. The cathode was made using the following steps. First, a coating solution was prepared by mixing carbon particles loaded with gold nanoparticles with pure water, Nafion solution, and ethylene glycol. The average particle size of the gold nanoparticles was 8.7 nm, and the loading amount was 18.9% by mass. The coating solution was filled in an air brush and sprayed on the carbon paper with a porous layer using nitrogen. After coating, it was rinsed with pure water for 30 minutes, and then immersed in hydrogen peroxide water to oxidize and remove organic matter such as ethylene glycol. It was cut into a size of 2 cm × 2 cm to form a cathode 121. It should be noted that the amount of gold coated was estimated to be about 0.4 mg / cm based on the mixed amount of gold nanoparticles and carbon particles in the coating solution. 2 An electrode having a Ti mesh coated with IrO2 nanoparticles as an anode catalyst was used as the anode 111. An IrO2 / Ti mesh electrode was cut into 10 cm x 10 cm pieces for use as the anode 111.

[0262] The catalyst area of ​​the electrolysis unit is 100 cm 2 The depth of the anode flow path 112 and the cathode flow path 122 was set to 1.0 mm.

[0263] The flow rate of carbon dioxide supplied as the cathode fluid was set to a constant value of 11.5 ccm per monomer unit. A slightly higher amount of carbon dioxide than the theoretical amount was supplied to operate the electrolysis unit. A 0.1 M aqueous KHCO solution was circulated as the anode fluid at a flow rate of 0.4 ccm.

[0264] The fastening plate, insulating plate, current collecting plate, unit, current collecting plate, insulating plate, and fastening plate are stacked in order to make a structure. 2 、Unit area 4cm 2 , so that a total current of 0.8 A flows into the unit. Heat is generated during operation, but since the unit has a large heat capacity and heat dissipation, it basically operates at room temperature.

[0265] The control unit 500 is used to obtain all the voltage, flow rate and other data during the reaction. In addition, the flow rate of the cathode discharge fluid from the cathode discharge flow path is set to flow rate C, and the flow rate of the anode discharge fluid from the anode discharge flow path is set to flow rate D. Flow rate C and flow rate D are measured using a thermal mass flow meter with a volume flow rate and a nitrogen reference. For confirmation, gas chromatography (GC) is used to analyze the flow rates of carbon monoxide and hydrogen generated by the reduction reaction of carbon dioxide and the reduction reaction of water. In addition, for confirmation, the ratio of the partial current density of carbon monoxide to the partial current density of hydrogen and the total current density to the partial current density, that is, the Faraday efficiency, is calculated from the amount of the product analyzed by the control device 501.

[0266] Table 2 shows the cell voltage and the Faraday efficiency of carbon monoxide (FE(GC)) at the initial stage and 50 hours after the start of operation. Furthermore, the values ​​of x(D / (Ca)) calculated using a volume flowmeter and x(MFC) based on the flow rates C and D obtained using a thermal mass flowmeter were calculated and shown in Table 2. Table 2 also shows the Faraday efficiency of carbon compounds estimated from the x values ​​using the following equations (estimated FE and estimated FE(MFC)). Other conditions and results are also shown in Table 2.

[0267] In the case of volume flow rate, FE = 14.778x 2 -99.006x+205.1

[0268] In the case of thermal mass flowmeter, FE = 16.857x 2 -113.03x+225.17

[0269] (Example 1 (×1, ×5, ×10, ×12))

[0270] The control was performed for a long time by adding 1, 5, 10, and 12 times (x-1.33) to the theoretical flow rate, and the operation was continued for 50 hours. The conditions and results in this case are shown in Table 2.

[0271] (Comparative Example 1 (×0.5, ×15))

[0272] The control was performed for a long time by adding 0.5 times and 15 times (x-1.33) to the theoretical flow rate, and the operation was continued for 50 hours. The conditions and results in this case are shown in Table 2.

[0273]

Table 2

[0274] Example 1 (initial value) Comparative Example 1 (initial value) Comparative Example 1 (×0.5) Example 1 (×1) Example 1 (×5) Example 1 (×10) Example 1 (×12) Comparative Example 1 (×15) Flow rate A[ccm] 11.50 11.50 11.14 11.86 11.98 11.98 12.14 16.67 <![CDATA[CO2 theoretical flow rate [ccm]]]> 11.14 11.14 11.14 11.14 11.14 11.14 11.14 11.14 <![CDATA[Excess CO2 introduction flow rate [ccm]]]> 0.36 0.36 0 0.72 0.84 0.84 1 5.53 <![CDATA[Flow A (N2_MFC) [ccm]]]> 8.51 8.51 8.2436 8.7764 8.8652 8.8652 8.9836 12.3358 Flow rate B [ccm] 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Flow rate C[ccm] 11.82 12.60 12.52 12.50 12.26 12.05 12.20 17.75 Flow rate Ca[ccm] 11.46 12.24 12.52 11.78 11.42 11.21 11.20 12.22 Flow C (MFC) [ccm] 9.98 10.75 10.55 10.43 9.87 9.72 9.75 10.50 Flow Ca(MFC)[ccm] 9.71 10.48 10.55 9.90 9.25 9.10 9.01 6.41 Flow rate D[ccm] 8.35 7.26 7.35 7.83 8.05 8.15 8.12 7.20 Flow rate D (MFC) [ccm] 6.98 6.15 6.05 6.54 6.73 6.80 6.78 6.04 ×(D / (Ca)) 1.37 1.69 1.70 1.50 1.42 1.39 1.38 1.70 ×(MFC) 1.43 1.75 1.74 1.59 1.47 1.43 1.44 1.74 FE(GC)[%] 98.0 80.2 80.8 88.0 94.5 97.2 97.0 80.5 Estimated FE [%] 97.4 80.4 79.5 89.8 94.6 97.1 96.9 79.8 Estimated FE(MFC)[%] 98.0 79.1 79.3 87.8 95.7 98.0 97.5 79.6 Cell voltage [V] 2.42 2.54 2.56 2.51 2.48 2.44 2.44 2.45

[0275] Table 2 confirms that, compared to Comparative Example 1 (×0.5), Example 1 (×1, ×5, ×10, and ×12) exhibited lower cell voltages and higher Faraday efficiencies after 50 hours of operation. This is likely due to the increase in flow rate A, which resulted in a decrease in the estimated Faraday efficiency. Meanwhile, in Comparative Example 1 (×15), while the cell voltage decreased, the Faraday efficiency also decreased.

[0276] (Comparative Example 2, Example 2 (ethylene))

[0277] The reaction was conducted using a Cu alloy nanocatalyst, specifically designed for ethylene production, as the cathode catalyst. Furthermore, flow rate A was initially set to 11.5 ccm. x was calculated from flow rates C and D. The Faradaic efficiencies were estimated from the value of x using the above formula corresponding to ethylene production. Other than these, the process was identical to Comparative Example 1 and Example 1. The conditions and results are shown in Table 3.

[0278] (Comparative Example 2 (×0.5, ×15)

[0279] The control was performed for a long time by adding 0.5 times and 15 times (x-0.89) to the theoretical flow rate, and the operation was continued for 50 hours. The conditions and results in this case are shown in Table 3.

[0280] (Example 2 (×1, ×5, ×10, ×12))

[0281] The control was performed for a long time by adding 1, 5, 10, and 12 times (x-0.89) to the theoretical flow rate, and the operation was continued for 50 hours. The conditions and results in this case are shown in Table 3.

[0282]

Table 3

[0283] Example 2 (initial value) Comparative Example 2 (initial value) Comparative Example 2 (×0.5) Example 2 (×1) Example 2 (×5) Example 2 (×10) Example 2 (×12) Comparative Example 2 (×15) Flow rate A[ccm] 11.50 11.50 11.32 11.42 12.44 13.64 14.05 17.22 <![CDATA[CO2 theoretical flow rate [ccm]]]> 11.14 11.14 11.14 11.14 11.14 11.14 11.14 11.14 <![CDATA[Excess CO2 inlet flow rate [ccm]]]> 0.36 0.36 0.18 0.28 1.3 2.5 2.91 6.08 <![CDATA[Flow A (N2MFC) [ccm]]]> 8.51 8.51 8.3768 8.4508 9.2056 10.0936 10.397 12.7428 Flow rate B [ccm) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Flow rate C[ccm] 8.70 9.61 9.40 9.08 9.90 10.98 11.51 15.58 Flow rate Ca[ccm] 8.34 9.25 9.22 8.80 8.60 8.48 8.60 9.50 Flow C (MFC) [ccm] 10.93 11.01 11.02 11.03 10.98 10.99 10.91 11.12 Flow Ca(MFC)[ccm] 10.66 10.74 10.89 10.82 10.02 9.14 8.76 6.62 Flow rate D[ccm] 7.77 7.30 7.25 7.54 7.62 7.68 7.72 7.14 Flow rate D (MFC) [ccm] 6.48 6.10 6.12 6.32 6.37 6.40 6.38 5.98 ×(D / (Oa)) 1.07 1.27 1.27 1.17 1.13 1.10 1.11 1.33 ×(MFC) 1.69 1.80 1.80 1.75 1.72 1.72 1.71 1.86 FE(GC)[%] 90.0 81.0 81.2 85.0 86.9 88.1 88.2 78.0 Estimated FE[%] 90.0 80.8 80.6 85.5 87.3 88.5 88.0 78.0 Estimated FE(MFC)[%] 90.0 81.3 81.6 85.6 87.2 87.7 88.2 77.6 Cell voltage [V] 3.76 3.88 3.88 3.75 3.73 3.73 3.73 3.78

[0284] As shown in Table 3, while flow rate A is reduced in Comparative Example 2 (×0.5) compared to Comparative Example 2 (ethylene), the Faradaic efficiency and cell voltage are comparable to those of Comparative Example 2 (ethylene). This suggests that, while the reaction conditions are more stringent, adjusting flow rate A based on the estimated Faradaic efficiency results in more stable operation. However, the performance remains similar to that of Comparative Example 2 (ethylene), and no improvement in overall cell performance is achieved.

[0285] Table 3 confirms that Example 2 (×1, ×5, ×10, and ×12) exhibited lower cell voltages and higher Faraday efficiencies after 50 hours of operation compared to Comparative Example 2 (×0.5). This is likely due to the increase in flow rate A, which resulted in a decrease in the estimated Faraday efficiency. Meanwhile, in Comparative Example 2 (×15), while the cell voltage decreased, the Faraday efficiency also decreased.

[0286] (Comparative Example 3, Example 3 (Methane))

[0287] The reaction was conducted using a Cu alloy nanocatalyst specifically designed for methane production as the cathode catalyst. Flow rate A was initially set to 11.5 cm3, and x was calculated from flow rates C and D. The Faradaic efficiencies were estimated from the value of x using the above equation corresponding to the case of methane. Otherwise, the reaction was conducted in the same manner as in Comparative Example 1 and Example 1. The conditions and results are shown in Table 4.

[0288] (Comparative Example 3 (×0.5, ×15)

[0289] The control was performed for a long time by adding 0.5 times and 15 times (x-0.83) to the theoretical flow rate, and the operation was continued for 50 hours. The conditions and results in this case are shown in Table 4.

[0290] (Example 3 (×1, ×5, ×10, ×12)

[0291] The control was performed for a long time, with 1, 5, 10, and 12 times (x-0.83) added to the theoretical flow rate, and the operation was continued for 50 hours. Except for this, the same operation as in Comparative Example 3 was carried out. The conditions and results in this case are shown in Table 4.

[0292]

Table 4

[0293] Example 3 (initial value) Comparative Example 3 (initial value) Comparative Example 3 (×0.5) Example 3 (×1) Example 3 (×5) Example 3 (×10) Example (×12) Comparative Example 3 (×15) Flow rate A[ccm] 11.50 11.50 11.34 11.48 12.62 14.00 14.49 17.17 <![CDATA[CO2 theoretical flow rate [ccm]]]> 11.14 11.14 11.14 11.14 11.14 11.14 11.14 11.14 <![CDATA[Excess CO2 introduction flow rate [ccm]]]> 0.36 0.36 0.20 0.34 1.48 2.86 3.35 6.03 <![CDATA[Flow A (N2MFC) [ccm]]]> 8.51 8.51 8.3916 8.4952 9.3388 10.36 10.7226 12.7058 Flow rate B [ccm] 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Flow rate C[ccm] 8.35 9.40 9.20 9.04 9.80 11.08 11.55 14.98 Flow rate Ca[ccm] 7.99 9.04 9.00 8.70 8.32 8.22 8.20 8.95 Flow C (MFC) [ccm] 8.37 8.43 8.47 8.43 8.38 8.38 8.37 8.46 Flow Ca(MFC)(ccm] 8.10 8.16 8.32 8.18 7.28 6.26 5.89 4.00 Flow rate D[ccm] 7.81 7.18 7.18 7.39 7.55 7.62 7.63 7.21 Flow rate D (MFC) [ccm] 6.46 6.01 6.06 6.17 6.34 6.36 6.34 6.05 ×(D / (Ca)) 1.02 1.26 1.25 1.18 1.10 1.08 1.07 1.24 ×(MFC) 1.30 1.40 1.40 1.37 1.32 1.32 1.32 1.40 FE(GC)[%] 89.7 79.2 79.4 83.0 86.5 87.7 87.4 79.3 Estimated FE[%] 89.9 79.0 79.2 82.6 86.1 87.2 87.4 79.7 Estimated FE(MFC)[%] 89.1 78.9 79.4 82.3 86.5 86.9 86.7 79.3 Cell voltage [V] 3.76 3.95 4.05 3.92 3.88 3.85 3.95 4.02

[0294] As shown in Table 4, while flow rate A is reduced in Comparative Example 3 (×0.5) compared to Comparative Example 3 (methane), the Faradaic efficiency and cell voltage are comparable to those in Comparative Example 3 (methane). This suggests that, while the reaction conditions are more stringent, adjusting flow rate A based on the estimated Faradaic efficiency results in more stable operation. However, the performance remains similar to that of Comparative Example 3 (methane), and no improvement in overall cell performance is achieved.

[0295] Table 4 confirms that, compared to Comparative Example 3 (×0.5), Example 3 (×1, ×5, ×10, and ×12) exhibited lower cell voltages and higher Faraday efficiencies after 50 hours of operation. This is likely due to the increase in flow rate A, which resulted in a decrease in the estimated Faraday efficiency. Meanwhile, in Comparative Example 3 (×15), while the cell voltage decreased, the Faraday efficiency also decreased.

[0296] (Comparative Example 4, Example 4 (Ethane))

[0297] The reaction was conducted using a Cu alloy nanocatalyst, specifically designed for ethane production, as the cathode catalyst. Flow rate A was initially set to 11.5 cm3. x was calculated from flow rates C and D. The Faradaic efficiencies were estimated from the x value using the above formula corresponding to ethane. Otherwise, the reaction was conducted in the same manner as in Comparative Example 1 and Example 1. Other conditions and results are shown in Table 5.

[0298] (Comparative Example 4 (×0.5, ×15)

[0299] Flow rate A was initially set at 11.5 ccm, and x was calculated from flow rates C and D. Control was then performed over a long period of time, with 0.5 and 15 times (x - 0.83) added to the theoretical flow rate. Operation was continued for 50 hours. The conditions and results for this situation are shown in Table 5.

[0300] (Example 4 (×1.0, ×5.0, ×10, ×12))

[0301] Flow rate A was initially set at 11.5 ccm, and x was calculated from flow rates C and D. Control was then performed over a long period of time, with 1, 5, 10, and 12 times (x - 0.83) added to the theoretical flow rate. Operation was continued for 50 hours. The conditions and results for this situation are shown in Table 5.

[0302]

Table 5

[0303] Example 4 (initial value) Comparative Example 4 (initial value) Comparative Example 4 (×0.5) Example 4 (×1) Example 4 (×5) Example 4 (×10) Example 4 (×12) Comparative Example 4 (×15) Flow rate A[ccm] 11.50 11.50 11.36 11.56 12.52 13.92 14.29 17.89 <![CDATA[CO2 theoretical flow rate [ccm]]]> 11.14 11.14 11.14 11.14 11.14 11.14 11.14 11.14 <![CDATA[Excess CO2 introduction flow rate [cc m > 0.36 0.36 0.22 0.42 1.38 2.78 3.15 6.75 <![CDATA[Flow rate A (N2MFC) [ccm]]]> 8.51 8.51 8.4064 8.5544 9.2648 10.3008 10.5746 13.2386 Flow rate B [ccm] 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Flow rate C[ccm] 8.51 9.38 9.25 9.01 9.70 11.08 11.48 15.88 Flow rate Ca[ccm] 8.15 9.02 9.03 8.59 8.32 8.30 8.33 9.13 Flow C (MFC) [ccm] 8.05 8.16 8.18 8.10 8.06 8.05 8.04 8.18 Flow Ca(MFC)[ccm] 7.78 7.89 8.02 7.79 7.04 5.99 5.71 3.19 Flow rate D[ccm] 7.53 7.15 7.18 7.37 7.58 7.62 7.67 7.13 Flow rate D (MFC) [ccm] 6.35 6.03 6.04 6.20 6.33 6.35 6.34 6.03 ×(D / (Ca)) 1.08 1.26 1.26 1.17 1.10 1.09 1.09 1.28 ×(MFC) 1.27 1.35 1.35 1.31 1.27 1.27 1.27 1.36 FE(GC)[%] 87.2 78.5 78.7 83.0 86.2 87.0 87.1 78.1 Estimated FE[%] 87.0 78.8 79.0 83.1 86.3 86.7 86.9 78.0 Estimated FE(MFC)[%] 86.9 78.6 78.5 83.0 86.3 86.9 86.8 78.3 Cell voltage (V) 3.88 4.08 4.15 3.98 3.92 3.89 3.95 4.12

[0304] As shown in Table 5, although flow rate A is reduced in Comparative Example 4 (×0.5) compared to Comparative Example 4 (Ethane), the Faradaic efficiency and cell voltage are comparable to those of Comparative Example 4 (Ethane). This suggests that, while the reaction conditions are more stringent, adjusting flow rate A based on the estimated Faradaic efficiency results in more stable operation. However, the performance remains similar to that of Comparative Example 4 (Ethane), and no improvement in overall cell performance is achieved.

[0305] Table 5 confirms that, compared to Comparative Example 4 (×0.5), Example 4 (×1, ×5, ×10, and ×12) exhibited lower cell voltages and higher Faraday efficiencies after 50 hours of operation. This is likely due to the increase in flow rate A, which resulted in a decrease in the estimated Faraday efficiency. Meanwhile, in Comparative Example 4 (×15), while the cell voltage decreased, the Faraday efficiency also decreased.

[0306] If the flow rate A is increased excessively, as in the case of 15 times, the Faraday efficiency decreases due to factors such as drying of the catalyst surface, drying of the separator, and pressure and temperature distribution within the cell. To prevent drying of the separator and catalyst layer, humidification is sometimes performed, and sometimes water is heated at the same temperature as the cell to form water vapor. However, to improve the purity of the generated gas, if utilization is considered, the water vapor must be removed after the reaction. Furthermore, since the energy required to generate water vapor is high, the overall efficiency decreases. In particular, if the flow rate is increased, the energy required to generate water vapor, the energy required to preheat the reaction gases, and the energy required to remove the water vapor from the heated cathode exhaust fluid increase, resulting in greater heat energy loss. Furthermore, even if the Faraday efficiency is maintained, the concentration of the generated gas in the cathode exhaust fluid decreases, necessitating subsequent purification steps, resulting in a decrease in the overall efficiency of the system. This not only reduces the efficiency, but also the efficiency of the entire system. Therefore, an extreme increase in the flow rate reduces the overall system efficiency, which is not preferred.

[0307] As described above, by controlling the flow rate A based on the estimated value of the Faraday efficiency, it is possible to suppress a decrease in the electrolysis efficiency.

[0308] It should be noted that the configurations of the above-mentioned embodiments can be applied in combination, and a portion can also be replaced. Here, several embodiments of the present invention are described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope and subject matter of the invention, and are also included in the invention described in the patent claims and their equivalents.

[0309] The above-mentioned embodiments can be summarized into the following technical solutions.

[0310] (Technical Solution 1)

[0311] An electrolysis device comprising:

[0312] an electrolysis unit having a cathode for reducing carbon dioxide to generate carbon compounds, an anode for oxidizing water to generate oxygen, a cathode flow path facing the cathode, and an anode flow path facing the anode;

[0313] a cathode supply flow path connected to the inlet of the cathode flow path and through which a cathode supply fluid containing the carbon dioxide gas supplied to the cathode flow path flows;

[0314] an anode supply flow path connected to the inlet of the anode flow path and through which an anode supply fluid containing the water flows and is supplied to the anode flow path;

[0315] a cathode exhaust flow path connected to an outlet of the cathode flow path and through which flows a cathode exhaust fluid discharged from the cathode flow path and containing the carbon compound and the carbon dioxide;

[0316] an anode exhaust flow path connected to an outlet of the anode flow path and through which flows an anode exhaust fluid discharged from the anode flow path and containing the oxygen and the water;

[0317] a cathode flow regulator for regulating a flow rate A of the cathode supply fluid supplied to the cathode flow path;

[0318] an anode flow regulator for regulating a flow rate B of the anode supply fluid supplied to the anode flow path;

[0319] a first flow meter for measuring a flow rate C of the cathode exhaust fluid discharged from the cathode flow path;

[0320] a second flow meter for measuring a flow rate D of the anode off-flow fluid discharged from the anode flow path; and

[0321] a control device that receives measurement data of the flow rate C from the first flow meter and measurement data of the flow rate D from the second flow meter,

[0322] The control device uses the measurement data of the flow C and the measurement data of the flow D to estimate the value of the Faraday efficiency according to a relationship that makes the value of the Faraday efficiency of the carbon compound approximate to a function including the flow C and the flow D, and controls the cathode flow regulator based on the estimated value of the Faraday efficiency, thereby controlling the flow A.

[0323] (Technical Solution 2)

[0324] The electrolysis device according to technical solution 1, wherein the control device controls the cathode flow regulator according to the estimated value of the Faraday efficiency, thereby controlling the flow rate A to satisfy I×13.93+(x-1.33)×1≤A≤I×13.93+(x-1.33)×10, wherein I represents the total reaction current value in the electrolysis unit, x satisfies x=D / (Ca), and a represents the flow rate of the carbon dioxide gas contained in the cathode exhaust fluid.

[0325] (Technical Solution 3)

[0326] According to the electrolysis device described in Technical Solution 1, wherein the first flowmeter is a first thermal mass flowmeter, the second flowmeter is a second thermal mass flowmeter, and the control device controls the cathode flow regulator according to the estimated value of the Faraday efficiency, thereby controlling the flow rate A to satisfy I×13.93+(x-1.40)×1≤A≤I×13.93+(x-1.40)×7, wherein I represents the total reaction current value, x satisfies x=D / (Ca), and a represents the flow rate of the remaining unreduced carbon dioxide in the carbon dioxide contained in the cathode supply fluid.

[0327] (Technical Solution 4)

[0328] An electrolysis device according to any one of Technical Solutions 1 to Technical Solutions 3, wherein the control device is connected to at least one device selected from a power supply for supplying current or voltage between the anode and the cathode, a cathode pressure regulator for controlling the pressure of the cathode flow path, an anode pressure regulator for controlling the pressure of the anode flow path, and a temperature regulator for adjusting the temperature of the electrolysis unit.

[0329] (Technical Solution 5)

[0330] According to the electrolysis device described in Technical Solution 1, the control device stops the operation of the electrolysis unit when the value calculated by using (cathode flow increase + D) / total reaction current value in the electrolysis unit / 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) / 1.5 is less than 0.8.

[0331] (Technical Solution 6)

[0332] According to the electrolysis device described in Technical Solution 1, wherein the first flowmeter is a first thermal mass flowmeter, the second flowmeter is a second thermal mass flowmeter, and the control device stops the operation of the electrolysis unit when the total Faraday efficiency of the reduction product generated by the electrolysis unit is below 0.8.

[0333] (Technical Solution 7)

[0334] An electrolysis device according to any one of Technical Solutions 1 to Technical Solutions 6, wherein the control device is connected to a hydrogen supply source that supplies a fluid containing the hydrogen to a chemical synthesis reaction device that is arranged in a subsequent section of the electrolysis device and generates compounds by using a chemical reaction between the carbon compound and hydrogen.

[0335] (Technical Solution 8)

[0336] According to the electrolysis device of technical solution 7, wherein the first flow meter is a first thermal mass flow meter, the second flow meter is a second thermal mass flow meter, and the control device is composed of I×6.964×(100-14.778x 2 The flow rate of hydrogen generated by the electrolysis device is calculated using a value calculated by (-99.006x+205.41), the hydrogen supply source is controlled, and the flow rate of the fluid containing hydrogen supplied to the chemical synthesis reaction device is reduced according to the calculated hydrogen flow rate.

[0337] (Technical Solution 9)

[0338] The electrolysis device according to any one of Technical Solutions 1 to Technical Solutions 8 comprises a first energy converter arranged in the middle of the anode exhaust flow path and converting the first energy of the anode exhaust fluid flowing in the anode exhaust flow path into a first electrical energy or a first rotational energy, and using the first electrical energy or the first rotational energy to drive the anode flow regulator.

[0339] (Technical Solution 10)

[0340] An electrolysis device according to any one of Technical Solutions 1 to Technical Solutions 8 comprises a second energy converter arranged in the middle of the cathode discharge flow path, which converts the second energy of the cathode discharge fluid flowing in the cathode discharge flow path into second electrical energy or second rotational energy, and uses the second electrical energy or the second rotational energy to drive the cathode flow regulator.

[0341] (Technical Solution 11)

[0342] An electrolysis method using an electrolysis device, wherein the electrolysis device comprises:

[0343] an electrolysis unit having a cathode for reducing carbon dioxide to generate carbon compounds, an anode for oxidizing water to generate oxygen, a cathode flow path facing the cathode, and an anode flow path facing the anode;

[0344] a cathode supply flow path connected to the inlet of the cathode flow path and through which a cathode supply fluid containing the carbon dioxide gas supplied to the cathode flow path flows;

[0345] an anode supply flow path connected to the inlet of the anode flow path and through which an anode supply fluid containing the water flows and is supplied to the anode flow path;

[0346] a cathode exhaust flow path connected to an outlet of the cathode flow path and through which flows a cathode exhaust fluid discharged from the cathode flow path and containing the carbon compound and the carbon dioxide;

[0347] an anode exhaust flow path connected to an outlet of the anode flow path and through which flows an anode exhaust fluid discharged from the anode flow path and containing the oxygen and the water;

[0348] a cathode flow regulator for regulating a flow rate A of the cathode supply fluid supplied to the cathode flow path;

[0349] an anode flow regulator for regulating a flow rate B of the anode supply fluid supplied to the anode flow path;

[0350] a first flow meter for measuring a flow rate C of the cathode exhaust fluid discharged from the cathode flow path; and

[0351] a second flow meter for measuring a flow rate D of the anode off-flow fluid discharged from the anode flow path,

[0352] The electrolysis method uses the measurement data of the flow C from the first flow meter and the measurement data of the flow D from the second flow meter to estimate the value of the Faraday efficiency according to a relationship that makes the value of the Faraday efficiency of the carbon compound approximate to a function including the flow C and the flow D. Based on the estimated value of the Faraday efficiency, the cathode flow regulator is controlled to control the flow A.

Claims

1. An electrolysis device comprising: an electrolysis unit having a cathode for reducing carbon dioxide to generate carbon compounds, an anode for oxidizing water to generate oxygen, a cathode flow path facing the cathode, and an anode flow path facing the anode; a cathode supply flow path connected to the inlet of the cathode flow path and through which a cathode supply fluid containing the carbon dioxide gas supplied to the cathode flow path flows; an anode supply flow path connected to the inlet of the anode flow path and through which an anode supply fluid containing the water flows and is supplied to the anode flow path; a cathode exhaust flow path connected to an outlet of the cathode flow path and through which flows a cathode exhaust fluid discharged from the cathode flow path and containing the carbon compound and the carbon dioxide; an anode exhaust flow path connected to an outlet of the anode flow path and through which flows an anode exhaust fluid discharged from the anode flow path and containing the oxygen and the water; a cathode flow regulator for regulating a flow rate A of the cathode supply fluid supplied to the cathode flow path; an anode flow regulator for regulating a flow rate B of the anode supply fluid supplied to the anode flow path; a first flow meter for measuring a flow rate C of the cathode exhaust fluid discharged from the cathode flow path; a second flow meter for measuring a flow rate D of the anode off-flow fluid discharged from the anode flow path; and a control device that receives measurement data of the flow rate C from the first flow meter and measurement data of the flow rate D from the second flow meter, The control device uses the measurement data of the flow C and the measurement data of the flow D to estimate the value of the Faraday efficiency according to a relationship that makes the value of the Faraday efficiency of the carbon compound approximate to a function including the flow C and the flow D, and controls the cathode flow regulator based on the estimated value of the Faraday efficiency, thereby controlling the flow A.

2. The electrolysis device according to claim 1, wherein The control device controls the cathode flow regulator according to the estimated value of the Faraday efficiency, thereby controlling the flow rate A to meet I×13.93+(x-1.33)×1≤A≤I×13.93+(x-1.33)×10 Wherein I represents the total reaction current value in the electrolysis unit, x satisfies x=D / (Ca), and a represents the flow rate of the carbon dioxide gas contained in the cathode exhaust fluid.

3. The electrolysis device according to claim 1, wherein The first flow meter is a first thermal mass flow meter, the second flow meter is a second thermal mass flow meter, and the control device controls the cathode flow regulator according to the estimated value of the Faraday efficiency, thereby controlling the flow rate A to meet I×13.93+(x-1.40)×1≤A≤I×13.93+(x-1.40)×7 Wherein I represents the total reaction current value, x satisfies x=D / (Ca), and a represents the flow rate of the remaining carbon dioxide that has not been reduced in the carbon dioxide contained in the cathode supply fluid.

4. The electrolysis device according to claim 1, wherein The control device is connected to at least one device selected from a power supply that supplies current or voltage between the anode and the cathode, a cathode pressure regulator that controls the pressure of the cathode flow path, an anode pressure regulator that controls the pressure of the anode flow path, and a temperature regulator that adjusts the temperature of the electrolysis unit.

5. The electrolysis device according to claim 1, wherein The control device stops the operation of the electrolysis unit when the value calculated by (cathode flow increase + D) / total reaction current value in the electrolysis unit / 60 (s) / 96500 (c / mol) / 2 (number of reaction electrons) × 22400 (cc / mol) / 1.5 is less than 0.

8.

6. The electrolysis device according to claim 1, wherein The first flowmeter is a first thermal mass flowmeter, the second flowmeter is a second thermal mass flowmeter, and the control device stops the operation of the electrolysis unit when the total Faraday efficiency of the reduction product generated by the electrolysis unit is 0.8 or less.

7. The electrolysis device according to any one of claims 1 to 6, wherein: The control device is connected to a hydrogen supply source that supplies a fluid containing the hydrogen to a chemical synthesis reaction device that is provided at a subsequent stage of the electrolysis device and generates a compound by a chemical reaction between the carbon compound and hydrogen.

8. The electrolysis device according to claim 7, wherein: The first flow meter is a first thermal mass flow meter, the second flow meter is a second thermal mass flow meter, and the control device is composed of I×6.964×(100-14.778x 2 The flow rate of hydrogen generated by the electrolysis device is calculated using a value calculated by (-99.006x+205.41), the hydrogen supply source is controlled, and the flow rate of the fluid containing hydrogen supplied to the chemical synthesis reaction device is reduced according to the calculated hydrogen flow rate.

9. An electrolysis device according to any one of claims 1 to 6, comprising a first energy converter arranged in the middle of the anode exhaust flow path, which converts the first energy of the anode exhaust fluid flowing in the anode exhaust flow path into a first electrical energy or a first rotational energy, and uses the first electrical energy or the first rotational energy to drive the anode flow regulator.

10. An electrolysis device according to any one of claims 1 to 6, comprising a second energy converter arranged in the middle of the cathode discharge flow path, which converts the second energy of the cathode discharge fluid flowing in the cathode discharge flow path into a second electrical energy or a second rotational energy, and uses the second electrical energy or the second rotational energy to drive the cathode flow regulator.

11. An electrolysis method using an electrolysis device, wherein the electrolysis device comprises: an electrolysis unit having a cathode for reducing carbon dioxide to generate carbon compounds, an anode for oxidizing water to generate oxygen, a cathode flow path facing the cathode, and an anode flow path facing the anode; a cathode supply flow path connected to the inlet of the cathode flow path and through which a cathode supply fluid containing the carbon dioxide gas supplied to the cathode flow path flows; an anode supply flow path connected to the inlet of the anode flow path and through which an anode supply fluid containing the water flows and is supplied to the anode flow path; a cathode exhaust flow path connected to an outlet of the cathode flow path and through which flows a cathode exhaust fluid discharged from the cathode flow path and containing the carbon compound and the carbon dioxide; an anode exhaust flow path connected to an outlet of the anode flow path and through which flows an anode exhaust fluid discharged from the anode flow path and containing the oxygen and the water; a cathode flow regulator for regulating a flow rate A of the cathode supply fluid supplied to the cathode flow path; an anode flow regulator for regulating a flow rate B of the anode supply fluid supplied to the anode flow path; a first flow meter for measuring a flow rate C of the cathode exhaust fluid discharged from the cathode flow path; and a second flow meter for measuring a flow rate D of the anode off-flow fluid discharged from the anode flow path, The electrolysis method uses the measurement data of the flow C from the first flow meter and the measurement data of the flow D from the second flow meter to estimate the value of the Faraday efficiency according to a relationship that makes the value of the Faraday efficiency of the carbon compound approximate to a function including the flow C and the flow D. Based on the estimated value of the Faraday efficiency, the cathode flow regulator is controlled to control the flow A.

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