Carbon dioxide reduction device, carbon dioxide reduction system, and information processing method

Abstract

This technology provides a method for removing oxygen from the raw gas used in carbon dioxide reduction devices. [Solution] The carbon dioxide reduction device comprises an electrolyte membrane, a cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, a first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, and an oxygen removal unit provided on the first passage and containing an oxygen removal substance.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide reduction device, a carbon dioxide reduction system, and an information processing method.

Background Art

[0002] An increase in the emission of greenhouse gases such as carbon dioxide is cited as one of the causes of global warming. In order to reduce the emission of carbon dioxide, research and development of technologies for electrochemically reducing carbon dioxide to produce valuable substances have been carried out (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when converting carbon dioxide in a raw material gas containing multiple components such as exhaust gas or air into valuable substances, the raw material gas may contain oxygen. Oxygen in the raw material gas becomes an impurity that is disadvantageous for the production of valuable substances.

[0005] The present disclosure aims to provide a technology capable of removing oxygen contained in the raw material gas of a carbon dioxide reduction device.

Means for Solving the Problems

[0006] A carbon dioxide reduction device according to one aspect of the present disclosure includes an electrolyte membrane, a cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, a first passage connected to the cathode and through which a raw material gas containing carbon dioxide, water, and oxygen flows, and an oxygen removal unit provided on the first passage and containing an oxygen removal substance.

[0007] A carbon dioxide reduction system according to one aspect of the present disclosure comprises a carbon dioxide reduction device and a processing unit, the carbon dioxide reduction device comprising an electrolyte membrane, a cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, a first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, an oxygen removal unit provided on the first passage and containing an oxygen removal substance, a third passage connected to the cathode through which a reduction gas containing carbon compounds and hydrogen discharged from the cathode flows, a second passage branching off from the third passage and connected to the oxygen removal unit, and a switching unit that switches the flow path of the reduction gas between the second passage and the third passage, the processing unit acquires time-series data of voltage and current between the anode and the cathode, and generates switching information for switching the switching unit based on the acquired time-series data. [Effects of the Invention]

[0008] According to this disclosure, oxygen contained in the raw material gas of a carbon dioxide reduction device can be removed. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows an overview of the carbon dioxide reduction system of this embodiment. [Figure 2] This is a block diagram showing an example of a control device configuration. [Figure 3] This flowchart shows an example of a processing procedure performed by a control device. [Modes for carrying out the invention]

[0010] (1) A carbon dioxide reduction apparatus according to one aspect of the present disclosure comprises an electrolyte membrane, a cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, a first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, and an oxygen removal unit provided on the first passage and containing an oxygen removal substance.

[0011] The carbon dioxide reduction apparatus described in (1) above can remove oxygen contained in the raw material gas supplied to the electrochemical cell. Oxygen in the raw material gas suppresses the reduction reaction of carbon dioxide in the electrochemical cell, for example by causing an oxygen reduction reaction in the electrochemical cell, and becomes an impurity that is unfavorable for the production of valuable products. By performing the electrolytic reduction of carbon dioxide using raw material gas from which the impurity oxygen has been removed, the efficiency of production of valuable products can be improved.

[0012] (2) The carbon dioxide reduction apparatus described in (1) above may include a second passage for flowing the reducing gas containing the carbon compound and hydrogen generated in the cathode to the oxygen removal section.

[0013] According to the above configuration, by introducing the products of the reduction reaction into the oxygen removal section, the hydrogen contained in the products can be used as a refreshing agent to refresh (reduce) the oxygen removal substances in the oxygen removal section. By refreshing the oxidized oxygen removal substances with the hydrogen from the products, the oxygen removal performance (oxygen reduction activity) of the oxygen removal substances can be further maintained. This improves the utility of hydrogen, a by-product in carbon dioxide reduction devices whose main purpose is the reduction of carbon dioxide, and by recycling hydrogen, costs can be reduced compared to preparing a refreshing agent separately.

[0014] (3) The carbon dioxide reduction device described in (1) or (2) above includes a third passage connected to the cathode through which the reducing gas discharged from the cathode flows, the second passage is branched from the third passage and connected to the oxygen removal unit, and may include a switching unit that switches the flow path of the reducing gas between the second passage and the third passage.

[0015] With the above configuration, the flow path of the products from the reduction reaction can be switched, allowing for the efficient and effective use of hydrogen and other valuable materials. When refreshing the oxygen removal substance is necessary, the hydrogen contained in the product can be introduced into the oxygen removal section, and when refreshing is not necessary, it can be appropriately recovered as a product.

[0016] (4) In any one of the carbon dioxide reduction devices according to (1) to (3) above, the switching unit may switch the flow path of the reducing gas based on the time-dependent data of the voltage or current between the anode and the cathode.

[0017] According to the above configuration, based on the voltage and current between the anode and the cathode that vary corresponding to the state of the oxygen-removing substance in the oxygen-removing unit, the flow path of the reducing gas can be switched to an appropriate state at an appropriate timing. For example, when the removal of oxygen in the oxygen-removing unit is not sufficient, the switching unit is switched so that the product of the reduction reaction flows through the branch path, thereby refreshing the oxygen-removing substance and improving the oxygen removal rate.

[0018] (5) In any one of the carbon dioxide reduction devices according to (1) to (4) above, the oxygen-removing substance may contain at least one metal selected from the group consisting of iron, nickel, manganese, and cobalt.

[0019] According to the above configuration, oxygen in the raw material gas can be satisfactorily removed by a metal having excellent oxygen reduction activity performance.

[0020] (6) A carbon dioxide reduction system according to one aspect of the present disclosure includes a carbon dioxide reduction device and a processing unit. The carbon dioxide reduction device includes an electrolyte membrane, a cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, a first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, an oxygen-removing unit provided on the first passage and containing an oxygen-removing substance, a third passage connected to the cathode through which a reducing gas containing a carbon compound and hydrogen discharged from the cathode flows, a second passage branched from the third passage and connected to the oxygen-removing unit, and a switching unit that switches the flow path of the reducing gas between the second passage and the third passage. The processing unit acquires time-dependent data of the voltage and current between the anode and the cathode, and generates switching information for switching the switching unit based on the acquired time-dependent data.

[0021] (7) The information processing method according to one aspect of the present disclosure is an information processing method related to a carbon dioxide reduction device. The carbon dioxide reduction device includes an electrolyte membrane, a cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, a first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, an oxygen removal unit provided on the first passage and containing an oxygen removal substance, a third passage connected to the cathode through which a reduction gas containing a carbon compound and hydrogen discharged from the cathode flows, a second passage branched from the third passage and connected to the oxygen removal unit, and a switching unit for switching the flow path of the reduction gas between the second passage and the third passage. A computer acquires time-series data of the voltage and current between the anode and the cathode, and executes a process of generating switching information for switching the switching unit based on the acquired time-series data.

[0022] According to the carbon dioxide reduction system of (6) above and the information processing method of (7), switching information for switching the switching unit in the carbon dioxide reduction device can be accurately and automatically generated based on the voltage and current between the anode and the cathode, and the operation of the carbon dioxide reduction device can be further optimized. It reduces the human cost for specifying appropriate switching timing and states, and enables a stable switching operation that does not depend on the skills of the operator. For example, by controlling the carbon dioxide reduction device according to the generated information, automation of the flow path switching can be achieved.

[0023] The present disclosure will be specifically described with reference to the drawings showing embodiments thereof.

[0024] FIG. 1 is a diagram showing an overview of the carbon dioxide reduction system 100 of the present embodiment. The carbon dioxide reduction system 100 includes a carbon dioxide reduction device 1 and a control device 2. The carbon dioxide reduction device 1 is a system that electrically reduces carbon dioxide contained in the raw material gas G1 to produce valuable substances such as carbon monoxide.

[0025] The carbon dioxide reduction device 1 comprises an electrochemical cell 10 that reduces carbon dioxide in a raw material gas G1 to produce a reduced gas G3 containing carbon monoxide, etc., a raw material gas supply unit 30 that supplies the raw material gas G1 to the electrochemical cell 10, an oxygen removal unit 40 that removes oxygen from the raw material gas G1, and a recovery unit 50 that recovers the reduced gas G3.

[0026] The electrochemical cell 10 includes an electrolyte membrane 11, a cathode 12 provided on one side of the electrolyte membrane 11, and an anode 13 provided on the other side of the electrolyte membrane 11. The electrochemical cell 10 has a cathode chamber 14 and an anode chamber 15, which are separated by the electrolyte membrane 11 having the cathode 12 and anode 13. The electrochemical cell 10 may also include a separator that separates the cathode chamber 14 and the anode chamber 15. In this embodiment, the case in which the electrochemical cell 10 functions as a solid oxide electrolysis cell (SOEC) will be described as an example.

[0027] A power supply 16 is connected to the cathode 12 and anode 13, and a voltage is applied between the cathode 12 and anode 13 by the power supply 16. The high-potential terminal of the power supply 16 is electrically connected to the anode 13, and the low-potential terminal is electrically connected to the cathode 12.

[0028] Figure 1 illustrates a carbon dioxide reduction device 1 comprising one electrochemical cell 10. Alternatively, the carbon dioxide reduction device 1 may be configured to comprise multiple stacked electrochemical cells 10.

[0029] The introduction passage 61 connects the raw material gas supply unit 30 and the cathode chamber 14. The introduction passage 61 flows the raw material gas G1 from the raw material gas supply unit 30 to the cathode chamber 14. An oxygen removal unit 40 is provided on the introduction passage 61. The discharge passage 62 connects the cathode chamber 14 and the recovery unit 50. The discharge passage 62 flows the reduced gas G3 from the cathode chamber 14 to the recovery unit 50. A branch passage 63 is provided downstream of the discharge passage 62. One end of the branch passage 63 is connected to the oxygen removal unit 40. A switching valve 64 is provided at the connection between the discharge passage 62 and the branch passage 63, allowing the flow path of the reduced gas G3 to be switched between the discharge passage 62 and the branch passage 63. The introduction passage 61, discharge passage 62, and branch passage 63 are not particularly limited, and known piping can be used as appropriate.

[0030] The raw material gas G1 is, for example, air or exhaust gas. The raw material gas G1 is a mixed gas containing carbon dioxide, water (water vapor), and oxygen. The raw material gas G1 may also contain nitrogen, carbon monoxide, hydrogen sulfide, carbonyl sulfide, sulfur dioxide, nitrogen dioxide, methane, hydrogen, etc. The raw material gas G1 is introduced into the oxygen removal unit 40 via the introduction passage 61.

[0031] The oxygen removal unit 40 contains an oxygen removal substance and removes oxygen (O2) contained in the raw material gas G1 from the raw material gas G1. Examples of oxygen removal substances include substances having oxygen reduction activity. Specifically, examples of oxygen removal substances include metals such as iron, nickel, manganese, and cobalt, or alloys containing these metals. From the viewpoint of oxygen removal performance, the oxygen removal substance is preferably iron. The oxygen removal substance may be used alone or in combination of two or more types.

[0032] The oxygen removal unit 40 comprises a main body case 41 filled with powdered oxygen removal material, a first inlet 42 into which raw material gas G1 is introduced, a second inlet 43 into which reducing gas G3 is introduced, and a first discharge port 44 for discharging the raw material gas G1 after oxygen removal. The oxygen removal unit 40 may also include a filter material (not shown). In the oxygen removal unit 40, as the raw material gas G1 taken in from the first inlet 42 passes through the inside of the main body case 41, the oxygen removal material removes the oxygen contained in the raw material gas G1, and raw material gas G1 containing almost no oxygen can be discharged from the first discharge port 44. Hereinafter, for convenience, the raw material gas G1 discharged from the oxygen removal unit 40 after oxygen removal will also be referred to as post-oxygen removal gas G2. Post-oxygen removal gas G2 contains carbon dioxide and water, etc.

[0033] The raw material gas G1 or the gas G2 after oxygen removal may be subjected to a separation treatment using a separation device to separate other components, if necessary. These other components are components other than carbon dioxide contained in the raw material gas G1, and other than oxygen (for example, nitrogen).

[0034] The oxygen-removed gas G2 is introduced into the cathode chamber 14 via the introduction passage 61. The cathode chamber 14 is not filled with a solvent such as water or electrolyte, and it is preferable to bring gaseous carbon dioxide containing water (H2O) into contact with the cathode 12. The gas introduced into the cathode chamber 14 may be the raw material gas G1 or the oxygen-removed gas G2 to which water vapor has been added using a method such as bubbling.

[0035] The cathode chamber 14 is provided with a fourth inlet 141 connected to the inlet passage 61 into which the oxygen-removed gas G2 is introduced, and a fourth outlet 142 connected to the discharge passage 62 for discharging the reducing gas G3. The oxygen-removed gas G2, which contains carbon dioxide and water, is introduced into the cathode 12 via the fourth inlet 141.

[0036] Cathode 12 is an electrode that promotes the reduction reaction of carbon dioxide (CO2) and water (H2O), producing reduced products which are carbon compounds derived from carbon dioxide and hydrogen (H2) as a byproduct. Examples of reduced products include carbon monoxide, methane, ethylene, and formic acid. In this embodiment, cathode 12 dissociates the oxygen from carbon dioxide in gas G2 after oxygen removal, producing a reduced gas G3 containing carbon monoxide (CO) and hydrogen (H2), and oxide ions (O2). 2- ) generates [the following]. The reducing gas G3 may contain unreacted carbon dioxide.

[0037] Cathode 12 can contain a cathode catalyst that reduces carbon dioxide and is capable of carrying out a reduction reaction. For example, various metals or metal compounds can be used as the cathode catalyst. Examples of metals used as cathode catalysts include La, Sr, Mn, Co, Fe, Ni, and Nd. The cathode catalyst may be used individually or in combination of two or more metals. Examples of metal compounds include metal oxides and metal hydroxides containing these metals.

[0038] The cathode 12 preferably contains a conductive material in addition to the cathode catalyst, and more preferably a conductive porous material. Examples of conductive materials include porous carbon fiber sheets such as carbon paper, carbon cloth, and carbon felt, and sintered bodies made from carbon particles, with carbon paper being preferred. Other conductive materials may include sintered bodies of metal fibers made from titanium alloys, stainless steel, etc., sintered bodies of powdered metals, metal meshes, foamed metal bodies, etc.

[0039] The cathode 12 is preferably formed by highly dispersing fine particles of the cathode catalyst on a conductive material such as carbon paper. The cathode 12 can be formed, for example, by dispersing the cathode catalyst in a solvent, coating it onto a conductive material, and drying it.

[0040] The anode chamber 15 includes a fifth inlet 151 into which a predetermined fluid is introduced, and a fifth outlet 152 for discharging oxygen (O2) and the like generated in the anode 13. It is preferable that the anode chamber 15 is not filled with water or a solvent such as an electrolyte, and that a gaseous supply gas is brought into contact with the anode 13. A mixed gas containing, for example, nitrogen, oxygen, and hydrogen is introduced into the fifth inlet 151 of the anode chamber 15. The mixed gas introduced into the anode chamber 15 may be air.

[0041] Anode 13 is an electrode that promotes the oxidation reaction of oxide ions supplied through the electrolyte membrane 11, generating oxygen (O2). Anode 13 can be any material capable of initiating an oxidation reaction. Anode 13 includes, for example, an anode catalyst. As the anode catalyst, various metals or metal compounds can be used. Examples of metals used as anode catalysts include platinum, gold, ruthenium, rhodium, palladium, iridium, nickel, copper, and cobalt. The anode catalyst may be used individually or in combination of two or more metals. Examples of metal compounds include metal oxides and metal hydroxides containing these metals.

[0042] The anode 13 preferably contains a conductive material in addition to the anode catalyst. Examples of conductive materials include those similar to those used for the anode 13.

[0043] The anode 13 can be formed, for example, by dispersing the anode catalyst in a solvent, coating it onto a conductive material such as carbon paper, and drying it.

[0044] The electrolyte membrane 11 is composed of a solid electrolyte membrane. The electrolyte membrane 11 can be made of a material that has electronic insulating and oxygen ion conductive properties at high temperatures. The electrolyte membrane 11 conducts oxide ions generated at the cathode 12 to the anode 13. The electrolyte membrane 11 is a dense oxide membrane and functions as a barrier for the gas atmosphere. The electrolyte membrane 11 can be formed using, for example, stabilized zirconia, perovskite-type oxides, or ceria-based electrolyte solid solutions. Stabilized zirconia is zirconia in which a stabilizing agent is dissolved in zirconia. Examples of stabilizing agents include Y2O3, Sc2O3, Yb2O3, Gd2O3, Nd2O3, CaO, and MgO.

[0045] In this embodiment, an example is shown where the electrochemical cell 10 is a SOEC, but it is not limited to this. The electrochemical cell 10 may be a solid polymer cell, for example, using an ion exchange membrane for the electrolyte membrane 11.

[0046] When the electrochemical cell 10 is a solid polymer type, the electrolyte membrane 11 is an ion-exchange membrane having ion conductivity. Examples of electrolyte membranes 11 include anion exchange membranes that move anions such as hydroxide ions, and cation exchange membranes that move cations such as protons. Examples of anion exchange membranes include solid polymer membranes (anion exchange resins) having anion exchange groups such as quaternary ammonium groups and pyridinium groups. Examples of cation exchange include fluororesin systems such as perfluoroethylene sulfonic acid.

[0047] The electrochemical cell 10 can employ any configuration that is capable of electrolytically reducing carbon dioxide. For example, water, or an aqueous solution containing hydroxide ions or hydrogen, may be introduced into the anode chamber 15.

[0048] A voltage is applied from the power supply 16 to the electrochemical cell 10, and the deoxygenated gas G2 is introduced into the cathode 12. The deoxygenated gas G2 is electrolyzed at the cathode 12 to produce carbon monoxide, hydrogen, and oxide ions. The carbon monoxide and hydrogen are discharged as reduced gas G3 from the fourth outlet 142. The oxide ions pass through the electrolyte membrane 11 and are oxidized at the anode 13 to produce oxygen and electrons. The oxygen is discharged from the fifth outlet 152.

[0049] The reducing gas G3 discharged from the fourth discharge port 142 flows into the discharge passage 62 and is introduced into either the recovery section 50 or the oxygen removal section 40. The flow path of the reducing gas G3 is switched by a switching valve 64. The switching valve 64 is composed of a known solenoid valve or the like. The switching valve 64 can switch the flow path in response to a signal provided by the control device 2, selectively allowing fluid to flow through a specific flow path. The switching valve 64 may also have the function of a flow control valve that adjusts the flow rate of the fluid passing through when in a communication state. The switching valve 64 is an example of a switching unit that switches the flow path of the reducing gas G3.

[0050] The switching valve 64 switches the flow path of the reducing gas G3 between the discharge passage 62 and the branch passage 63. In other words, the switching valve 64 switches between a state in which the upstream side of the discharge passage 62 and the downstream side of the discharge passage 62 are in communication and the reducing gas G3 is introduced into the recovery section 50, and a state in which the upstream side of the discharge passage 62 and the branch passage 63 are in communication and the reducing gas G3 is introduced into the oxygen removal section 40. The flow path of the reducing gas G3 is switched according to whether or not the reducing gas G3 needs to be recycled. Whether or not the reducing gas G3 needs to be recycled corresponds to whether or not the oxygen removal section 40 needs to be refreshed.

[0051] If the recycling of reducing gas G3 is not required, the flow path of reducing gas G3 is switched to introduce it into the recovery unit 50. The carbon monoxide and hydrogen in the reducing gas G3 recovered in the recovery unit 50 can be used as various materials.

[0052] When the recycling of reducing gas G3 is required, the flow path of reducing gas G3 is switched to introduce reducing gas G3 into the oxygen removal unit 40. The reducing gas G3 introduced into the oxygen removal unit 40 functions as a refresher for the oxygen removal substance. The hydrogen contained in reducing gas G3 comes into contact with the oxygen removal substance inside the main case 41, reducing the oxygen removal substance that has been oxidized during oxygen removal. The introduction of reducing gas G3 restores the oxygen reduction activity of the oxygen removal substance. When carbon monoxide contained in reducing gas G3 is introduced into the oxygen removal unit 40, it is oxidized by the oxygen removal substance to carbon dioxide, which can then be electrolyzed in the electrochemical cell 10.

[0053] The flow path configuration of the carbon dioxide reduction device 1 is not limited to the example in Figure 1, as long as the flow path of the reducing gas G3 can be switched. The carbon dioxide reduction device 1 may include, for example, a passage connecting the fourth discharge port 142 and the recovery unit 50, and a passage connecting the fourth discharge port 142 and the oxygen removal unit 40, and switching units such as on-off valves that allow or restrict the passage of fluid may be provided on each passage. By controlling the opening / closing of each on-off valve, the flow path of the reducing gas G3 can be switched.

[0054] The carbon dioxide reduction device 1 is equipped with measuring instruments 70 for detecting the operating state of the carbon dioxide reduction device 1 in a time series. Multiple measuring instruments 70 may be provided. Examples of measuring instruments 70 include a current sensor for measuring the current flowing between the anode 13 and cathode 12 of the electrochemical cell 10, a voltage sensor for measuring the voltage between the anode 13 and cathode 12, and a flow sensor for measuring the flow rate of the fluid flowing through the electrochemical cell 10. Each measuring instrument 70 may be installed at an appropriate position depending on the detection content and target. By analyzing the measurement data obtained by the measuring instruments 70, the performance of the oxygen removal unit 40 and the necessity of recycling the reducing gas G3 according to the performance of the oxygen removal unit 40 can be determined.

[0055] The control device 2 is a computer that controls the operation of the carbon dioxide reduction device 1. Based on measurement data from the measuring instrument 70, the control device 2 generates control information to control the operation of the carbon dioxide reduction device 1 and controls the drive of the carbon dioxide reduction device 1. The control information includes switching information for switching the switching unit.

[0056] Figure 2 is a block diagram showing an example configuration of the control device 2. The control device 2 includes a processing unit 21, a storage unit 22, and an input / output unit 23, etc. The control device 2 may be a single computer, or it may be a computer system composed of multiple computers and peripheral devices. The control device 2 may be a virtualized virtual machine, or it may be a cloud.

[0057] The processing unit 21 comprises one or more processors such as a CPU (Central Processing Unit) or MPU (Micro-Processing Unit). The processing unit 21 includes temporary storage media such as SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory), a clock, counters, etc. The processing unit 21 may be implemented in software, or part or all of it may be implemented in hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array).

[0058] The storage unit 22 includes, for example, a non-volatile storage device such as a hard disk or flash memory. The storage unit 22 stores various computer programs and data that the processing unit 21 references. The storage unit 22 also stores a program 221 that causes the computer to execute processing related to the generation of control information.

[0059] The computer program (program product) including program 221 may be provided on a non-temporary recording medium 2A on which the computer program is recorded in a readable format. The recording medium 2A is a portable memory such as a CD-ROM, USB memory, or SD (Secure Digital) card. The processing unit 21 reads the desired computer program from the recording medium 2A using a reading device (not shown) and stores the read computer program in the storage unit 22. Alternatively, the computer program may be provided by communication. Program 221 may be a single computer program or may consist of multiple computer programs. Program 221 may also be executed on a single computer or executed collaboratively by multiple computers.

[0060] The input / output unit 23 is equipped with an input / output interface for connecting external devices. The connection between the input / output unit 23 and the external device may be wired or wireless. The input / output unit 23 is connected to a switching valve 64, a power supply 16, and measuring instruments 70, etc. The processing unit 21 acquires measurement data output from the measuring instruments 70 via the input / output unit 23 as needed. The processing unit 21 outputs control signals to the switching valve 64 via the input / output unit 23 to control their operation.

[0061] The control device 2 may further include a communication unit for communication via a communication network, a display unit for displaying images, an operation unit for receiving user input, and so on.

[0062] The control device 2 may be located away from the carbon dioxide reduction device 1. The control device 2 may be connected to the carbon dioxide reduction device 1 via a communication network such as the Internet or a LAN (Local Area Network), and may send and receive measurement data and control information to and from the carbon dioxide reduction device 1 via the communication network. The control device 2 may also send and receive various information to and from the carbon dioxide reduction device 1 via a computer located near the carbon dioxide reduction device 1.

[0063] Figure 3 is a flowchart showing an example of a processing procedure performed by the control device 2. The following processing is performed by the processing unit 21 according to the program 221 stored in the storage unit 22 of the control device 2. The timing of the processing may be, for example, at regular intervals, or when new measurement data is measured by the measuring instrument 70.

[0064] The processing unit 21 of the control device 2 acquires measurement data measured by the measuring instrument 70 (step S1). The measurement data includes, for example, the current and voltage in the electrochemical cell 10.

[0065] The processing unit 21 calculates the change in current or voltage based on the acquired current and voltage time-series data, and determines whether or not to recycle the reducing gas G3 based on the calculated change (step S2).

[0066] An example of a method for determining whether recycling is necessary is shown below. The processing unit 21 calculates the voltage increase or the decrease in current (absolute value of the decrease) when the current of the electrochemical cell 10 is constant. If the calculated voltage increase or current decrease is greater than or equal to a preset threshold, the processing unit 21 determines that the performance of the oxygen removal unit 40 has deteriorated and that recycling of the reducing gas G3 is necessary. If the calculated voltage increase or current decrease is less than a preset threshold, the processing unit 21 determines that the performance of the oxygen removal unit 40 has recovered or is maintained and that recycling of the reducing gas G3 is unnecessary. The change in voltage or current in the above determination may be the change from the previous measurement data, or it may be the change from a predetermined reference time (for example, the most recent switching time of the switching valve 64). The above determination conditions may also be applied when the current flow path of the reducing gas G3 is connected to the recovery unit 50.

[0067] Furthermore, the processing unit 21 calculates the amount of voltage decrease (absolute value of the decrease) or the amount of current increase when the current of the electrochemical cell 10 is constant. If the calculated amount of voltage decrease or current increase is greater than or equal to a preset threshold, the processing unit 21 determines that the recycling of the reducing gas G3 is unnecessary. If the calculated amount of voltage decrease or current increase is less than a preset threshold, the processing unit 21 determines that the recycling of the reducing gas G3 is necessary. The above determination conditions may also be applied when the current flow path of the reducing gas G3 is connected to the oxygen removal unit 40.

[0068] The processing unit 21 generates switching information based on the determination result of whether or not recycling is necessary (step S3). If it is determined that recycling of the reducing gas G3 is necessary, the processing unit 21 generates switching information to switch the flow path so that the reducing gas G3 is introduced into the oxygen removal unit 40. The processing unit 21 generates a signal to instruct the switching valve 64 to open / close so that the upstream side of the discharge path 62 and the branch path 63 are connected. If it is determined that recycling of the reducing gas G3 is unnecessary, the processing unit 21 generates switching information to switch the flow path so that the reducing gas G3 is introduced into the recovery unit 50. The processing unit 21 generates a signal to instruct the switching valve 64 to open / close so that the upstream side of the discharge path 62 and the downstream side of the discharge path 62 are connected.

[0069] The processing unit 21 outputs the generated switching information to the switching valve 64 of the carbon dioxide reduction device 1 (step S4).

[0070] The processing unit 21 repeatedly performs the above-described process. If it estimates that the performance of reducing gas G3 has deteriorated, it circulates the reducing gas G3 to the oxygen removal unit 40. If it estimates that the performance of reducing gas G3 has recovered, it terminates the circulation of reducing gas G3. Subsequently, if it estimates that the performance of reducing gas G3 has deteriorated again, it recirculates the reducing gas G3. By continuously monitoring the measurement data, it becomes possible to take early action according to the operating status of the carbon dioxide reduction device 1.

[0071] The generation and output of switching information may be performed only when a switching of the flow path is necessary because the state of a newly identified flow path differs from the state of the current flow path. The control device 2 may receive a response from a user, such as an operator, regarding whether or not the switching is permitted, and output the switching information to the switching valve 64 only if the switching is permitted.

[0072] The output destination for the switching information is not limited to the carbon dioxide reduction device 1, but may also be an external device such as a user terminal managed by the user. The switching information may include information that visually indicates the determination result of whether or not the reduced gas G3 needs to be recycled, and the switching direction of the flow path of the reduced gas G3, and may be information provided to the user. The switching information may also be information that visually indicates the recommended flow path switching state using a diagram showing the configuration of the carbon dioxide reduction device 1.

[0073] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the claims and equivalents thereof. The sequences shown in each embodiment are not limiting, and within the bounds of consistency, the order of each processing step may be changed, and multiple processes may be executed in parallel. The processing entity for each process is not limiting, and within the bounds of consistency, the processing of each device may be executed by other devices.

[0074] The matters described in each embodiment can be combined with each other. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. In addition, the claims use a form in which claims referencing two or more other claims (multi-claim form), but are not limited to this. A form in which multi-claims referencing at least one multi-claim (multi-multi-claim) may also be used. [Explanation of Symbols]

[0075] 100 Carbon Dioxide Reduction Systems 1. Carbon dioxide device 10 Electrochemical Cells 11 Electrolyte membrane 12 Cathode 13 Anodes 14 Cathode Chamber 15 Anode Chamber 40 Oxygen Removal Unit 50 Recovery Section 61 Introductory passage (1st passage) 62 Discharge passage (3rd passage) 63. Branching road (Second passage) 64. Switching valve (switching section) 2 Control device 21 Processing Unit 22 Memory section 23 Input / output section 221 Programs 2A recording medium

Claims

1. Electrolyte membrane, A cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, A first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, An oxygen removal unit containing an oxygen removal substance is provided on the first passage, Equipped with Carbon dioxide reduction device.

2. The oxygen removal section is provided with a second passage through which the reducing gas containing carbon compounds and hydrogen generated in the cathode is passed. The carbon dioxide reduction apparatus according to claim 1.

3. It is connected to the cathode and comprises a third passage through which the reducing gas discharged from the cathode flows, The second passage branches off from the third passage and is connected to the oxygen removal section. The system includes a switching unit that switches the flow path of the reducing gas between the second passage and the third passage. The carbon dioxide reduction apparatus according to claim 2.

4. The switching unit switches the flow path of the reducing gas based on time-dependent voltage or current data between the anode and the cathode. The carbon dioxide reduction apparatus according to claim 3.

5. The oxygen-removing substance includes at least one metal selected from the group consisting of iron, nickel, manganese, and cobalt. A carbon dioxide reduction apparatus according to claim 1 or claim 2.

6. It comprises a carbon dioxide reduction device and a processing unit, The carbon dioxide reduction device is Electrolyte membrane, A cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, A first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, An oxygen removal unit containing an oxygen removal substance is provided on the first passage, A third passage connected to the cathode through which a reducing gas containing carbon compounds and hydrogen discharged from the cathode flows, A second passage that branches off from the third passage and is connected to the oxygen removal section, A switching unit that switches the flow path of the reducing gas between the second passage and the third passage. Equipped with, The aforementioned processing unit, Time-series data of voltage and current between the anode and the cathode are acquired. Based on the acquired time-series data, switching information is generated for switching the switching unit. Carbon dioxide reduction system.

7. A method for processing information related to a carbon dioxide reduction device, The carbon dioxide reduction device is Electrolyte membrane, A cathode provided on one side of the electrolyte membrane, an anode provided on the other side of the electrolyte membrane, A first passage connected to the cathode through which a raw material gas containing carbon dioxide, water, and oxygen flows, An oxygen removal unit containing an oxygen removal substance is provided on the first passage, A third passage connected to the cathode through which a reducing gas containing carbon compounds and hydrogen discharged from the cathode flows, A second passage that branches off from the third passage and is connected to the oxygen removal section, A switching unit that switches the flow path of the reducing gas between the second passage and the third passage. Equipped with, Computers Time-series data of voltage and current between the anode and the cathode are acquired. Based on the acquired time-series data, switching information is generated for switching the switching unit. An information processing method that performs a process.

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