Control device for carbon dioxide separation device, control method therefor, and carbon dioxide separation system

Abstract

To provide a control device for a carbon dioxide separation device, a control method for the carbon dioxide separation device, and a carbon dioxide separation system comprising the control device for the carbon dioxide separation device that can efficiently use the carbon dioxide separation device regarding the viewpoint of energy consumption, and that can repeatedly separate carbon dioxide regarding the viewpoint of durability.SOLUTION: A control device for a carbon dioxide separation device of the present invention is a device for controlling power supply to a CO2 separation device which comprises a pair of first and second electrodes that are arranged on an electrolyte layer in a manner of interposing the electrolyte layer, and when power is supplied, takes in carbon dioxide (CO2) through the first electrode and releases the CO2 through the second electrode. The control device comprises: a constant voltage DC power supply that supplies power to the CO2 separation device and can vary current; a CO2 measurement unit that measures a CO2 concentration outside the first or second electrode; and a current control unit that controls the current of the constant voltage DC power supply according to the CO2 concentration measured by the CO2 measurement unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a carbon dioxide separator that controls a carbon dioxide separator, a control method for a carbon dioxide separator, and a carbon dioxide separation system equipped with the control device for a carbon dioxide separator. [Background technology]

[0002] In recent years, research and development of carbon dioxide-related technologies has progressed from the perspective of so-called carbon neutrality (zero carbon). One example of such technologies is a carbon dioxide separation device disclosed in Patent Document 1.

[0003] The carbon dioxide separation device disclosed in Patent Document 1 includes an electrolyte layer and a pair of gas-permeable electrodes disposed on the electrolyte layer with the electrolyte layer sandwiched therebetween, and the electrolyte layer contains an electrolytic solution capable of dissolving carbon dioxide and a redox compound having an N-oxy radical group in its molecule.

[0004] Incidentally, Patent Document 1 discloses the carbon dioxide separator itself, but does not disclose or suggest how to operate it. From the viewpoint of energy conservation, it is desirable to operate the carbon dioxide separator efficiently. It is also desirable to be able to repeatedly separate carbon dioxide from a gas containing carbon dioxide over a long period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6792969 (Patent Publication No. 2018-1131) Summary of the Invention

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a control device for a carbon dioxide separator, a control method for a carbon dioxide separator, and a carbon dioxide separation system equipped with the control device for a carbon dioxide separator, which allows the carbon dioxide separator to be used efficiently from the perspective of energy consumption and which allows carbon dioxide to be repeatedly separated from the perspective of durability.

[0007] The present invention provides a carbon dioxide separation device control device and a carbon dioxide separation device control method that control the power supply to a carbon dioxide separation device that includes a pair of gas-permeable first and second electrodes disposed on an electrolyte layer so as to sandwich the electrolyte layer, the pair taking in carbon dioxide through the first electrode and releasing the taken in carbon dioxide through the second electrode when power is supplied, and a carbon dioxide separation system that includes the carbon dioxide separation device control device. The carbon dioxide separation device control device includes a constant-voltage DC power supply that supplies power to the carbon dioxide separation device and is capable of varying current, a carbon dioxide measurement unit that measures the carbon dioxide concentration outside the first electrode or the second electrode, and a current control unit that controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration measured by the carbon dioxide measurement unit, and the electrolyte layer contains an electrolytic solution that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide by electrochemical reaction.

[0008] These and other objects, features and advantages of the present invention will become apparent from the following detailed description and accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration of a carbon dioxide separation system according to an embodiment. [Figure 2] 3 is a flowchart showing the operation of the carbon dioxide separation system. [Figure 3] FIG. 10 is a block diagram showing the configuration of a carbon dioxide separation system in a second modified embodiment. [Figure 4] 10 is a flowchart showing the operation of the carbon dioxide separation system in the fifth modified embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, components with the same reference numerals in each drawing indicate the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

[0011] The carbon dioxide separator control device in this embodiment is a device for controlling the power supply to a carbon dioxide separator that includes a pair of gas-permeable first and second electrodes disposed on an electrolyte layer so as to sandwich the electrolyte layer. When power is supplied, the carbon dioxide separator takes in carbon dioxide through the first electrode and releases the taken-in carbon dioxide through the second electrode. The carbon dioxide separator control device includes a constant-voltage DC power supply that supplies power to the carbon dioxide separator and is capable of varying current, a carbon dioxide measurement unit that measures the carbon dioxide concentration outside the first electrode or the second electrode, and a current control unit that controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration measured by the carbon dioxide measurement unit. The electrolyte layer contains an electrolyte solution that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction. The carbon dioxide separator control device and the carbon dioxide separator control method implemented therein will be described in more detail below, taking as an example a carbon dioxide separation system equipped with the carbon dioxide separator control device when measuring the carbon dioxide concentration outside the first electrode.

[0012] Figure 1 is a block diagram showing the configuration of a carbon dioxide separation system according to an embodiment. The carbon dioxide separation system according to the embodiment includes a carbon dioxide separator and a control device for the carbon dioxide separator. As shown in Figure 1, such a carbon dioxide separation system 1000 includes, for example, a carbon dioxide separator 1, a first flow path 2, a second flow path 3, a constant-voltage DC power supply 4, a carbon dioxide measurement unit 5, a control processing unit 6, a memory unit 7, a flow rate variable unit 8, an input unit 9a, a display unit 9b, and an interface unit (IF unit) 9c.

[0013] The carbon dioxide separation device 1 is a device that separates carbon dioxide from a gas containing carbon dioxide. More specifically, the carbon dioxide separation device 1 includes, for example, a pair of first and second electrodes 11 and 12 that are permeable to gas and are disposed on an electrolyte layer 13 so as to sandwich the electrolyte layer 13. When power is supplied, the carbon dioxide separation device 1 absorbs carbon dioxide through the first electrode 11 and releases the absorbed carbon dioxide through the second electrode 12. In other words, the electrolyte layer 13 is disposed between the opposing first and second electrodes 11 and 12, and the first electrode 11, the electrolyte layer 13, and the second electrode 13 are stacked in this order. The electrolyte layer 13 contains an electrolyte solution that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction. Preferably, the compound is a compound that adsorbs carbon dioxide by electrolytic reduction and desorbs carbon dioxide by electrolytic oxidation. Preferably, the compound is a compound that adsorbs carbon dioxide when the potential between the pair of first and second electrodes 11, 13 is relatively low and accepts electrons, and desorbs carbon dioxide when the potential is relatively high and supplies electrons. Preferably, the compound is a redox compound. Preferably, the compound is a redox compound having an N-oxy radical group in its molecule. In such a carbon dioxide separation device 1, when DC power is supplied to the first electrode 11 as the cathode and the second electrode as the anode, carbon dioxide is taken in through the first electrode 11, and the N-oxy anion group generated by reduction of the N-oxy radical group on the first electrode side combines with the carbon dioxide and migrates to the second electrode side, where it is oxidized to an N-oxy radical group, desorbing the bound carbon dioxide. This desorbed carbon dioxide is released through the second electrode 12. Such carbon dioxide separation devices are disclosed in Patent Document 1, International Publication No. 2022 / 019065, etc., and will be further described below.

[0014] The first flow path 2 is a box-like body to which a gas containing carbon dioxide is supplied, and is provided inside the first flow path 2 so as to face the first electrode 11 of the carbon dioxide separator 1. For example, in the example shown in Fig. 1, the first flow path 2 has a hollow rectangular parallelepiped shape, and one surface (side wall surface) thereof is formed by the first electrode 11 of the carbon dioxide separator 1. This allows the first electrode 11 of the carbon dioxide separator 1 to face the inside of the first flow path 2. A through-opening is formed on the other surface (for example, the top surface) of the first flow path 2 so as to be open to the atmosphere, which is an example of the gas containing carbon dioxide.

[0015] The second flow path 3 is a box that receives the carbon dioxide released from the carbon dioxide separator 1 and contains a gas containing the carbon dioxide, and is provided so that the second electrode 12 of the carbon dioxide separator 1 faces the inside of the second flow path 3. For example, in the example shown in FIG. 1 , the second flow path 3 has a hollow rectangular parallelepiped shape, similar to the first flow path 2, and one surface (side wall surface) of the second flow path 3 is formed by the second electrode 12 of the carbon dioxide separator 1. This means that the second electrode 12 of the carbon dioxide separator 1 faces the inside of the second flow path 3. The carbon dioxide separator 1 takes in carbon dioxide through the first flow path 2 and releases carbon dioxide through the second flow path 3, so that the carbon dioxide in the first flow path 2 moves to the second flow path 3. The second flow path 3 is connected to a host system that uses the carbon dioxide released from the carbon dioxide separator 1.

[0016] The constant-voltage DC power supply 4 is a DC power supply that supplies power to the carbon dioxide separation device 1 at a constant voltage and can vary the current. The constant-voltage DC power supply 4 is connected to the control processing unit 6 and controls the current under the control of the control processing unit 6. The constant-voltage DC power supply 4, for example, outputs a current of a first current value I1 at a predetermined voltage value, and outputs a current of a second current value I2 that is smaller than the first current value at the predetermined voltage value (I1>I2). In one example, the constant-voltage DC power supply 4 includes a first constant-voltage DC power supply that outputs a current of the first current value I1 at the predetermined voltage value, a second constant-voltage DC power supply that outputs a current of the second current value I2 at the predetermined voltage value, an output terminal, a first switch element interposed between the first constant-voltage DC power supply and the output terminal, and a second switch element interposed between the second constant-voltage DC power supply and the output terminal, and the control terminals of the first and second switch elements are connected to the control processing unit 6. In such a constant-voltage DC power supply 4, when the first switch element is turned on and the second switch element is turned off under the control of the control processing unit 6, a current of the first current value I1 is output from the output terminal, and when the first switch element is turned off and the second switch element is turned on under the control of the control processing unit 6, a current of the second current value I2 is output from the output terminal. For example, a GPS-3030D manufactured by Instex Japan can be used as the first and second constant-voltage DC power supplies.

[0017] The carbon dioxide measuring unit 5 is connected to the control processing unit 6 and is a device that measures the concentration of carbon dioxide outside the first electrode 11 under the control of the control processing unit 6. In the example shown in FIG. 1, the carbon dioxide measuring unit 5 measures the concentration of carbon dioxide in the first flow path. Note that the carbon dioxide measuring unit 5 may also measure carbon dioxide in a communication path (communication pipe) 84, which will be described later. The carbon dioxide measuring unit 5 is configured to include, for example, a CO2 sensor of the NDIR (Non-Dispersive Infrared) type (non-dispersive infrared absorption type).

[0018] The flow rate variable unit 8 is connected to the control processing unit 6 and is a device that varies the flow rate of gas (flow rate of gas per unit time) outside the first electrode 11 or outside the second electrode 12 under the control of the control processing unit 6. In the example shown in FIG. 1 , the flow rate variable unit 8 varies the flow rate of gas outside the first electrode 11, for example, the flow rate of gas supplied to the first flow path 2. More specifically, the flow rate variable unit 8 includes an air pump 81 that draws the gas from the first flow path 2, a communication passage (communication pipe) 84 that connects the first flow path 2 and the air pump 81, a flow rate adjustment valve 82 that is provided in the communication passage 84 and adjusts the flow rate of the gas flowing through the communication passage 84, and a flow rate control unit 83 (63) that controls the flow rate of the flow rate adjustment valve 82. The flow rate control unit 63 (83) is functionally provided in the control processing unit 6, as will be described later. One end of the communication passage 84 is connected to yet another surface of the first flow passage 2 (for example, the lower surface opposite the upper surface), and the other end of the communication passage 84 is connected to the suction port of the air pump 81. In such a flow rate variable unit 8, when the air pump 81 is activated (operated), the gas is drawn from the first flow passage 2, and as a result, air (an example of the gas) is supplied to the first flow passage 2 from the through-opening of the first flow passage 2, where it is accommodated and circulated. At this time, when the opening of the flow rate adjustment valve 82 is adjusted by the control processing unit 6, the air flows through the first flow passage 2 and the communication passage 84 at a flow rate corresponding to the adjusted opening. The air usually contains approximately 0.04% carbon dioxide.

[0019] The input unit 9a is connected to the control processing unit 6 and is a device that inputs various commands, such as a command to start operation, and various data required to operate the carbon dioxide separation system 1000, such as the first and second concentration thresholds described below, into the carbon dioxide separation system 1000, and is, for example, a keyboard, a mouse, or multiple input switches to which predetermined functions are assigned.

[0020] The display unit 9b is connected to the control processing unit 6 and is a device that displays commands, data, measurement results, etc. input from the input unit 9a in accordance with the control of the control processing unit 6, and is, for example, a CRT display, an LCD (liquid crystal display device), an organic EL display, etc.

[0021] The IF unit 9c is connected to the control processing unit 6 and is a circuit that inputs and outputs data to and from, for example, an external device under the control of the control processing unit 6, and is, for example, an interface circuit of RS-232C, which is a serial communication method, an interface circuit using the Bluetooth (registered trademark) standard, an interface circuit using the USB standard, etc. The IF unit 9c may also be, for example, a communication interface circuit that transmits and receives communication signals to and from an external device, such as a data communication card or a communication interface circuit conforming to the IEEE802.11 standard, etc.

[0022] The storage unit 7 is connected to the control processing unit 6 and is a circuit that stores various predetermined programs and various predetermined data under the control of the control processing unit 6.

[0023] The various predetermined programs include, for example, a control processing program, and the control processing program includes, for example, a control program, a current control program, and a flow rate control program. The control program is a program that controls each of the units 4, 7, 8, 9a to 9c of the carbon dioxide separation system 1000 according to the function of each unit. The current control program is a program that controls the current of the constant voltage DC power supply 4 according to the carbon dioxide concentration measured by the carbon dioxide measuring unit 5. The flow rate control program is a program that controls the flow rate of the flow rate adjustment valve 82 in the flow rate variable unit 8.

[0024] The various predetermined data include data necessary to execute each of these programs, such as the measurement results of the carbon dioxide measurement unit 5, the first and second concentration thresholds, and the first and second opening degrees θ1, θ2 (first and second flow rates v1, v2).

[0025] Such storage unit 7 includes, for example, a ROM (Read Only Memory) which is a nonvolatile storage element, an EEPROM (Electrically Erasable Programmable Read Only Memory) which is a rewritable nonvolatile storage element, etc. The storage unit 7 also includes a RAM (Random Access Memory) which serves as a so-called working memory of the control processing unit 6 and stores data generated during execution of the predetermined program, etc. The storage unit 7 may also be configured to include a hard disk device with a relatively large storage capacity.

[0026] The control processing unit 6 is a circuit that controls each of the units 4, 7, 8, 9a to 9c of the carbon dioxide separation system 1000 according to the function of each unit, and controls the power supply to the carbon dioxide separation device 1. The control processing unit 6 is configured to include, for example, a CPU (Central Processing Unit) and its peripheral circuits. When the control processing program is executed in the control processing unit 6, a control unit 61, a current control unit 62, and a flow rate control unit 63 are functionally configured.

[0027] The control unit 61 controls each of the units 4, 7, 8, 9a to 9c of the carbon dioxide separation system 1000 in accordance with the function of each unit, and is responsible for overall control of the carbon dioxide separation system 1000.

[0028] The current control unit 62 controls the current of the constant voltage DC power supply 4 in accordance with the concentration of carbon dioxide measured by the carbon dioxide measuring unit 5. More specifically, in this embodiment, the current control unit 62 controls the current of the constant voltage DC power supply 4 to decrease the current from a current value when the concentration of carbon dioxide measured by the carbon dioxide measuring unit 5 is equal to or less than a first threshold value (first concentration threshold) Th1, and controls the current of the constant voltage DC power supply 4 to increase the current from a current value when the concentration of carbon dioxide measured by the carbon dioxide measuring unit 5 is equal to or more than a second threshold value (second concentration threshold) Th2 that is greater than the first threshold value Th1. For example, the carbon dioxide separation system has, as its operating modes, a normal mode in which the constant-voltage DC power supply 4 outputs a current of a first current value I1, and a recovery mode in which the constant-voltage DC power supply 4 outputs a current of a second current value I2 that is smaller than the first current value I1, and when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or smaller than a first concentration threshold value Th1 while operating in the normal mode, the current control unit 62 controls the constant-voltage DC power supply 4 so that the constant-voltage DC power supply 4 outputs a current of a value from the current first current value I1 to the second current value I2. In the above example, the current control unit 62 outputs a control signal (recovery mode control signal) to the constant-voltage DC power supply 4 that turns off the first switch element and turns on the second switch element. This switches the operating mode from the normal mode to the recovery mode, and the carbon dioxide separation system 1000 operates in the recovery mode. Then, when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or exceeds the second concentration threshold value Th2 during operation in the recovery mode, the current control unit 62 controls the constant-voltage DC power supply 4 so that the constant-voltage DC power supply 4 outputs a current that changes from the current second current value I2 to the first current value I1. In the example described above, the current control unit 62 outputs a control signal (normal mode control signal) that turns on the first switch element and turns off the second switch element to the constant-voltage DC power supply 4. This switches the operation mode from the recovery mode to the normal mode, and the carbon dioxide separation system 1000 operates in the normal mode.

[0029] Each of the first and second current values I1 and I2 is appropriately set in advance from a plurality of samples. Each of the first and second concentration thresholds Th1 and Th2 is appropriately set in advance from a plurality of samples.

[0030] During operation (while in operation) of the carbon dioxide separation device 1, the current may be controlled within a range of current values greater than 0 (I1 > I2 > 0).

[0031] The flow rate control unit 63 (83) increases the flow rate of the gas from the current value while the current control unit controls the current of the constant voltage DC power supply to decrease the current. For example, when the air pump 81 is operating at a constant output, in the flow rate adjustment valve 82, at the first opening degree θ1, the gas flows at a first flow rate v1 per unit time, and at a second opening degree θ2 greater than the first opening degree θ1, the gas flows at a second flow rate v2 greater than the first flow rate v1 (θ1 < θ2, v1 < v2). When the flow rate control unit 63 (83) is operating in the normal mode, the flow rate control unit 63 (83) controls the flow rate adjustment valve 82 to be at the first opening degree θ1, and when operating in the recovery mode, controls the flow rate adjustment valve 82 to change from the current first opening degree θ1 to the second opening degree θ2. More specifically, when the flow rate control unit 63 (83) is operating in the normal mode, it outputs a control signal (first opening degree control signal) for setting the opening degree to the first opening degree θ1 to the flow rate adjustment valve 82, and when operating in the recovery mode, outputs a control signal (second opening degree control signal) for setting the opening degree to the second opening degree θ2 to the flow rate adjustment valve 82.

[0032] [[ID=eleven]] Each of the first and second opening degrees θ1 and θ2, and the first and second flow rates v1 and v2 are appropriately set in advance from a plurality of samples. [[ID=1 forty]]

[0033] In such a carbon dioxide separation system 1000, the first container 2, the constant voltage DC power supply 4, the carbon dioxide measurement unit 5, and the current control unit 62 correspond to an example of a control device for the carbon dioxide separation device, and the first container 2, the constant voltage DC power supply 4, the carbon dioxide measurement unit 5, the current control unit 62, the flow rate variable unit 8, and the flow rate control unit 63 (83) correspond to another example of a control device for the carbon dioxide separation device.

[0034] The control processing unit 6, input unit 9a, display unit 9b, IF unit 9c and storage unit 7 in the carbon dioxide separation system 1000 can be configured, for example, by a desktop or notebook computer. Note that the input unit 9a and display unit 9b may be omitted, and the control processing unit 6, IF unit 9c and storage unit 7 may be configured, for example, by a one-board or one-chip computer.

[0035] Next, the operation of this embodiment will be described below: Fig. 2 is a flowchart showing the operation of the carbon dioxide separation system.

[0036] When the carbon dioxide separation system 1000 having such a configuration is powered on, it initializes the necessary parts and starts operation. In the control processing unit 6, a control unit 61, a current control unit 62, and a flow rate control unit 63 (83) are functionally configured by executing the control processing program.

[0037] When operation begins, the carbon dioxide separation system 1000 operates in normal mode. More specifically, in the example described above, the current control unit 62 of the control processing unit 6 outputs a normal mode control signal to the constant-voltage DC power supply 4 that turns on the first switch element and turns off the second switch element so as to operate in normal mode, and the flow rate control unit 63 (83) of the control processing unit 6 outputs a first opening control signal to the flow rate adjustment valve 82 that sets the opening to the first opening θ1. Then, the carbon dioxide separation system 1000 repeatedly executes each of the processes S1 to S7 shown in Fig. 2 at predetermined control intervals, thereby controlling the power supply to the carbon dioxide separation device 1.

[0038] In FIG. 2, first, the carbon dioxide separation system 1000 acquires the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 from the carbon dioxide measuring unit 5 by the control unit 61 of the control processing unit 6, and stores it in the memory unit 7 (S1).

[0039] Next, the carbon dioxide separation system 1000 determines the current operation mode by the current control unit 62 of the control processing unit 6 (S2). If the result of this determination shows that the operation mode is the normal mode, the carbon dioxide separation system 1000 then executes process S3, while if the result of the determination shows that the operation mode is the recovery mode, the carbon dioxide separation system 1000 then executes process S6.

[0040] In this process S3, the carbon dioxide separation system 1000 determines, by the current control unit 62, whether the concentration of carbon dioxide measured by the carbon dioxide measurement unit 5 in process S1 is equal to or less than the first concentration threshold Th1 (or less). If the result of this determination is that the measured concentration of carbon dioxide is equal to or less than the first concentration threshold Th1 (Yes), the carbon dioxide separation system 1000 then executes process S4, while if the result of the determination is that the measured concentration of carbon dioxide is not equal to or less than the first concentration threshold Th1 (No), the carbon dioxide separation system 1000 then executes process S5.

[0041] In process S4, the carbon dioxide separation system 1000 operates in recovery mode. More specifically, in the example described above, the carbon dioxide separation system 1000 outputs a recovery mode control signal to the constant-voltage DC power supply 4 via the current control unit 62, which turns off the first switch element and turns on the second switch element, thereby switching the output of the constant-voltage DC power supply 4 from a current of a first current value I1 to a current of a second current value I2. Then, the carbon dioxide separation system 1000 outputs a second opening control signal to the flow rate adjustment valve 82 via the flow rate control unit 63, which sets the opening to a second opening θ2, thereby switching the flow rate of the flow rate variable unit 8 from a first flow rate v1 to a second flow rate v2.

[0042] Meanwhile, in process S6, the carbon dioxide separation system 1000 determines, by the current control unit 62, whether the carbon dioxide concentration measured by the carbon dioxide measurement unit 5 in process S1 is equal to or greater than (or exceeds) the second concentration threshold Th2. If the result of this determination is that the measured carbon dioxide concentration is equal to or greater than (or exceeds) the second concentration threshold Th2 (Yes), the carbon dioxide separation system 1000 then executes process S7, while if the result of the determination is that the measured carbon dioxide concentration is not equal to or greater than (or exceeds) the second concentration threshold Th2 (No), the carbon dioxide separation system 1000 then executes process S5.

[0043] In process S7, the carbon dioxide separation system 1000 operates in normal mode. More specifically, in the example described above, the carbon dioxide separation system 1000 causes the current control unit 62 to output a normal mode control signal to the constant voltage DC power supply 4 that turns on the first switch element and turns off the second switch element, thereby switching the output of the constant voltage DC power supply 4 from a current of the second current value I2 to a current of the first current value I1. Then, the carbon dioxide separation system 1000 causes the flow rate control unit 63 to output a first opening control signal to the flow rate adjustment valve 82 that sets the opening to the first opening θ1, thereby switching the flow rate of the flow rate variable unit 8 from the second flow rate v2 to the first flow rate v1.

[0044] Then, in process S5, the control unit 61 of the control processing unit 6 displays predetermined items (items) on the display unit 9b, such as the current operating mode and the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 in process S1, and ends the processing at this control timing.

[0045] As described above, the carbon dioxide separation system 1000 of the embodiment, the carbon dioxide separation device control device provided therein, and the carbon dioxide separation device control method implemented therein control the current of the constant voltage DC power supply 4 in accordance with the carbon dioxide concentration outside the first electrode 11, allowing the carbon dioxide separation device 1 to be used efficiently from the viewpoint of energy consumption. The carbon dioxide separation system 1000, the carbon dioxide separation device control device, and the carbon dioxide separation device control method can suppress continuous activation of organic matter, allowing the organic matter to be used stably over a long period of time and carbon dioxide to be separated.

[0046] The carbon dioxide separation system 1000, the control device for a carbon dioxide separator, and the control method for a carbon dioxide separator increase the gas flow rate while the current control unit 62 controls the current of the constant-voltage DC power supply 4 to decrease the current, and therefore, during that time, the decreased carbon dioxide concentration, in the first flow path where the carbon dioxide concentration has decreased above, can be restored. In the above example, the first flow path 2 is open to the atmosphere, so the carbon dioxide concentration in the first flow path can be restored to the carbon dioxide concentration in the atmosphere (approximately 0.04%]).

[0047] In this embodiment, the electrolyte layer 13 in the carbon dioxide separation device 1 contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction. The compound preferably contains a redox compound, more preferably a redox compound having an N-oxy radical group in its molecule. When power is supplied to this carbon dioxide separation device 1, electrons are transferred from the first electrode 11 to the second electrode 12 by a hopping mechanism caused by the compound, regardless of whether the compound transports carbon dioxide from the first electrode 11 to the second electrode 12. This consumes electrical energy. The carbon dioxide separation system 1000, the carbon dioxide separation device control device, and the carbon dioxide separation device control method control the current of the constant-voltage DC power supply 4 in accordance with the carbon dioxide concentration. Therefore, the transfer of electrons by the compound can be reduced when the carbon dioxide concentration is low and therefore the compound is unlikely to transport carbon dioxide from the first electrode 11 to the second electrode 12. This makes these systems suitable for the carbon dioxide separation system 1000, the carbon dioxide separation device control device, and the carbon dioxide separation device control method.

[0048] In the above embodiment, the flow rate variable unit 8 is provided downstream of the gas flowing through the first flow path so that the air pump 81 draws the gas from the first flow path 2, but the air pump may also be provided upstream of the gas flowing through the first flow path so that the air pump sends the gas to the first flow path 2 (first modified embodiment). In this case, the atmosphere, which is an example of the gas, is sent to the first flow path 2 via the flow rate variable unit 8.

[0049] Furthermore, in the above-described embodiment, the carbon dioxide separation system 1000 is configured to control the current of the constant voltage DC power supply 4 in accordance with the concentration of carbon dioxide measured by the carbon dioxide measuring unit 5 that measures the concentration of carbon dioxide outside the first electrode 11, but the carbon dioxide separation system 1000A may also be configured to control the current of the constant voltage DC power supply 4 in accordance with the concentration of carbon dioxide measured by the carbon dioxide measuring unit 5A that measures the concentration of carbon dioxide outside the second electrode 12 (second modified embodiment). This second modified embodiment controls the current of the constant voltage DC power supply 4 in accordance with the concentration of carbon dioxide outside the second electrode 12, and therefore allows the carbon dioxide separation device 1 to be used efficiently from the perspective of energy consumption. Other than that, the same effects as those of the above-described embodiment are achieved.

[0050] Fig. 3 is a block diagram showing the configuration of a carbon dioxide separation system in the second modified embodiment. A carbon dioxide separation system 1000A in the second modified embodiment includes, for example, a carbon dioxide separator 1, a first flow path 2, a second flow path 3, a constant-voltage DC power supply 4, a carbon dioxide measurement unit 5A, a control processing unit 6, a storage unit 7, a flow rate varying unit 8A, an input unit 9a, a display unit 9b, and an interface unit (IF unit) 9c, as shown in Fig. 3.

[0051] The carbon dioxide separation device 1, first flow path 2, second flow path 3, constant voltage DC power supply 4, control processing unit 6, memory unit 7, input unit 9a, display unit 9b and IF unit 9c in this second modified form of carbon dioxide separation system 1000A are respectively similar to the carbon dioxide separation device 1, first flow path 2, second flow path 3, constant voltage DC power supply 4, control processing unit 6, memory unit 7, input unit 9a, display unit 9b and IF unit 9c in the carbon dioxide separation system 1000 of the above-mentioned embodiment, and therefore their description will be omitted.

[0052] The carbon dioxide measuring unit 5A is connected to the control processing unit 6 and is a device that measures the concentration of carbon dioxide outside the second electrode 12 under the control of the control processing unit 6. In the example shown in Fig. 3, the carbon dioxide measuring unit 5A measures the concentration of carbon dioxide in the second flow path. Note that the carbon dioxide measuring unit 5A may also measure the carbon dioxide in a communication path (communication pipe) 84A, which will be described later.

[0053] The flow rate variable unit 8A is connected to the control processing unit 6 and is a device that varies the flow rate of the gas (flow rate of the gas per unit time) at the second electrode 13 under the control of the control processing unit 6. For example, the flow rate variable unit 8A varies the flow rate of the gas supplied to the second flow path 3. More specifically, the flow rate variable unit 8A includes a communication passage (communication pipe) 84A that connects the second flow path 3 to the host system, a flow rate adjustment valve 82A that is provided in the communication passage 84A and adjusts the flow rate of the gas flowing through the communication passage 84A, and a flow rate control unit 83 (63) that controls the flow rate of the flow rate adjustment valve 82A. The flow rate control unit 63 (83) in this second modified embodiment is similar to the flow rate control unit 63 (83) in the above-described embodiment, and therefore a description thereof will be omitted. In the example shown in FIG. 3, the flow rate adjustment valve 82A is provided in the communication passage 84A between the second flow path 3 and the host system, downstream of the second flow path 3. In the communication passage 84A, gas flows due to an air pump (not shown) of the upper system, and the gas is supplied to, accommodated in, and discharged from the second flow passage 3. At this time, when the opening of the flow rate adjustment valve 82A is adjusted by the control processing unit 6, the gas flows through the second flow passage 3 and the communication passage 84A at a flow rate according to the adjusted opening.

[0054] In addition, the carbon dioxide separation system 1000A in this second modified form is provided with an air pump 81 that draws the gas from the first flow path 2, and a communication passage (communication pipe) 84 that connects the first container 2 and the air pump 81.

[0055] Furthermore, in the second modified embodiment described above, the flow rate adjustment valve 82A is provided downstream of the gas flowing through the second flow path 3, but it may also be provided upstream of the gas flowing through the second flow path 3 (third modified embodiment). That is, the flow rate adjustment valve 82A is provided upstream of the second flow path 3, in a communication passage between the second flow path 3 and the host system.

[0056] Furthermore, in the above-described embodiment and its first to third modified embodiments, the current control unit 62 controls the current of the constant-voltage DC power supply 4 to decrease the current from the current value in order to switch from normal mode to recovery mode when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or less than a first concentration threshold Th1, and controls the current of the constant-voltage DC power supply 4 to increase the current from the current value in order to switch from recovery mode to normal mode when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or less than a second concentration threshold Th2. However, the current control unit 62 may also control the current of the constant-voltage DC power supply 4 to stop power supply when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or less than a third threshold (third concentration threshold) Th3 in order to switch from normal mode to recovery mode, and to start power supply when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or more than a fourth threshold (fourth concentration threshold) Th4 that is greater than the third threshold Th3 (fourth threshold Th4) (fourth modified embodiment). In this case, the flow rate variable unit 8 increases the flow rate of the gas above the current value while the current control unit 62 controls the current of the constant-voltage DC power supply 4 to stop the power supply. The third concentration threshold Th3 may be the same value as the first concentration threshold Th1 or may be a different value. The fourth concentration threshold Th4 may be the same value as the second concentration threshold Th2 or may be a different value.

[0057] Such carbon dioxide separation system 1000, carbon dioxide separator control device, and carbon dioxide separator control method stop power supply when the carbon dioxide concentration becomes equal to or less than the third threshold value Th3, allowing the carbon dioxide separator to be used more efficiently. The carbon dioxide separation system 1000, carbon dioxide separator control device, and carbon dioxide separator control method increase the gas flow rate while current control unit 62 controls the current of constant-voltage DC power supply 4 so as to stop power supply, and therefore can restore the reduced carbon dioxide concentration, in the first flow path or second flow path where the carbon dioxide concentration has decreased as described above.

[0058] In the above description, power supply is stopped as another aspect of the recovery mode, but in the recovery mode in which power is supplied at the second current value I2, the current control unit 62 may control the current of the constant voltage DC power supply 4 to stop power supply when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or less than a third threshold value (third concentration threshold) Th3, and may control the current of the constant voltage DC power supply 4 to start power supply when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or more than a fourth threshold value (fourth concentration threshold) Th4 that is greater than the third threshold value Th3 (fifth modified embodiment). In the recovery mode, it is possible to deal with a case in which carbon dioxide separation exceeds the recovery of carbon dioxide concentration.

[0059] In this case, the carbon dioxide separation system has, as its operating modes, in addition to the normal mode and the recovery mode, a power supply stop mode in which the constant-voltage DC power supply 4 stops supplying power, and when operating in the recovery mode, the current control unit 62 controls the constant-voltage DC power supply 4 so that the constant-voltage DC power supply 4 stops supplying power when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or less than the third concentration threshold Th3. In the above example, the current control unit 62 outputs a control signal (power supply stop mode control signal) to the constant-voltage DC power supply 4 that turns off the first switch element and the second switch element. This switches the operating mode from the recovery mode to the power supply stop mode, and the carbon dioxide separation system 1000 operates in the power supply stop mode. Then, when operating in the power supply stop mode, the current control unit 62 controls the constant-voltage DC power supply 4 so that the constant-voltage DC power supply 4 starts supplying power when the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 becomes equal to or more than the fourth concentration threshold Th4. In the above example, the current control unit 62 outputs a recovery mode control signal to the constant voltage DC power supply 4. This switches the operation mode from the power supply stop mode to the recovery mode, and the carbon dioxide separation system 1000 resumes the recovery mode and operates in the recovery mode. The first concentration threshold Th1 is set to be greater than the third and fourth concentration thresholds Th3 and Th4 (Th1>Th3, Th1>Th4).

[0060] Fig. 4 is a flowchart showing the operation of the carbon dioxide separation system in the fifth modified embodiment. The carbon dioxide separation system 1000 in this fifth modified embodiment repeatedly executes steps S1, S2a, S3 to S7, and S11 to S13 shown in Fig. 4 at predetermined control intervals, thereby controlling the power supply to the carbon dioxide separation device 1.

[0061] In Figure 4, first, the carbon dioxide separation system 1000, similar to process S1 shown in Figure 2, acquires the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 from the carbon dioxide measuring unit 5 by the control unit 61 of the control processing unit 6 and stores it in the memory unit 7 (S1).

[0062] Next, the carbon dioxide separation system 1000 determines the current operation mode by the current control unit 62 of the control processing unit 6 (S2a). If the result of this determination is that the operation mode is the normal mode, the carbon dioxide separation system 1000 executes each of the processes S3 to S5 described above with reference to Figure 2, and therefore a description thereof will be omitted. If the result of the determination is that the operation mode is the power supply stop mode, the carbon dioxide separation system 1000 next executes process S11. If the result of the determination is that the operation mode is the recovery mode, the carbon dioxide separation system 1000 next executes process S12.

[0063] In this process S11, the carbon dioxide separation system 1000 determines, by the current control unit 62, whether the concentration of carbon dioxide measured by the carbon dioxide measurement unit 5 in process S1 is equal to or greater than (or exceeds) the fourth concentration threshold Th4. If the result of this determination is that the measured concentration of carbon dioxide is equal to or greater than (or exceeds) the fourth concentration threshold Th4 (Yes), the carbon dioxide separation system 1000 then executes process S4. On the other hand, if the result of the determination is that the measured concentration of carbon dioxide is not equal to or greater than (or exceeds) the fourth concentration threshold Th4 (No), the carbon dioxide separation system 1000 then executes process S5. Processes S4 and S5 are the same as processes S4 and S5 described above with reference to FIG. 2, and therefore description thereof will be omitted.

[0064] In step S12, the carbon dioxide separation system 1000 determines, by the current control unit 62, whether the concentration of carbon dioxide measured by the carbon dioxide measurement unit 5 in step S1 is equal to or less than the third concentration threshold Th3 (or less). If the result of this determination is that the measured concentration of carbon dioxide is equal to or less than the third concentration threshold Th3 (Yes), the carbon dioxide separation system 1000 then executes step S13. On the other hand, if the result of the determination is that the measured concentration of carbon dioxide is not equal to or less than the third concentration threshold Th3 (No), the carbon dioxide separation system 1000 executes steps S6 and S7 described above with reference to Figure 2, and therefore their description will be omitted.

[0065] In this process S13, the carbon dioxide separation system 1000 operates in a power supply stop mode. More specifically, in the example described above, the carbon dioxide separation system 1000 outputs a power supply stop mode control signal to the constant voltage DC power supply 4 by the current control unit 62, which turns off the first switch element and the second switch element, thereby stopping the power supply from the constant voltage DC power supply 4. Then, the carbon dioxide separation system 1000 may, for example, maintain the flow rate of the flow rate variable unit 8 at the second flow rate v2 without outputting a control signal to the flow rate adjustment valve 82, or, for example, the carbon dioxide separation system 1000 may output, by the flow rate control unit 63, a control signal (second opening control signal) to the flow rate adjustment valve 82, which changes the opening to a third opening θ3 that is larger than the second opening θ2, thereby switching the flow rate of the flow rate variable unit 8 from the second flow rate v2 to a third flow rate v3 that is larger than the second flow rate v2 (θ2<θ3, v2 <v3)。

[0066] Then, following this process S13, the carbon dioxide separation system 1000 executes the process S5 described above with reference to FIG.

[0067] In the above-described fifth modified embodiment, the current control unit 62 outputs a recovery mode control signal to the constant voltage DC power supply 4 in order to switch from the power supply stop mode to the recovery mode, but the current control unit 62 may also output a normal mode control signal to the constant voltage DC power supply 4 in order to switch from the power supply stop mode to the normal mode.

[0068] Furthermore, in the above-described embodiment and its first to fifth modified embodiments, the constant-voltage DC power supply 4 may be configured to include, for example, a solar cell and its peripheral circuitry, or may be configured to include, for example, a fuel cell and its peripheral circuitry (sixth modified embodiment). Such a carbon dioxide separation system 1000, a carbon dioxide separation apparatus control device, and a carbon dioxide separation apparatus control method can contribute to carbon neutrality during operation of the carbon dioxide separation apparatus. For example, the constant-voltage DC power supply 4 may be configured to include a series solar cell set in which a first number of solar cells are connected in series to output the predetermined voltage value, a first constant-voltage DC power supply in which a second number of series solar cell sets are connected in parallel to output the first current value I1, and a second constant-voltage DC power supply in which a third number of series solar cell sets are connected in parallel to output the second current value I2 ((first number) > (second number)).

[0069] Furthermore, in the above-described embodiment and its first to sixth variants, the output of the constant-voltage DC power supply 4 is changed to two discrete values ​​(first and second current values ​​I1, I2) or three discrete values ​​(first and second current values ​​I1, I2 and 0), but the current control unit 62 may also control the current of the constant-voltage DC power supply 4 continuously (for example, linearly) according to the carbon dioxide concentration measured by the carbon dioxide measuring unit 5 (seventh variant).

[0070] The carbon dioxide separator that can be used in the above-described embodiment will be further described.

[0071] Separation of carbon dioxide by the carbon dioxide separator 1 is considered to be due to the following, taking as an example a system containing a redox compound having an N-oxy radical group in the electrolyte layer.

[0072] The carbon dioxide that has contacted and permeated the first electrode 11 then contacts the electrolyte layer 13 and is dissolved in the electrolyte solution contained in the electrolyte layer 13. At this time, due to the supply of power, the N-oxy radical groups of the redox compound contained in the electrolyte layer 13 on the side closer to the first electrode 11 are reduced to N-oxy anion groups. These N-oxy anion groups are easily bonded with carbon dioxide dissolved in the electrolyte solution, accelerating the dissolution of carbon dioxide into the electrolyte solution. This promotes the uptake of carbon dioxide into the first electrode 11. Meanwhile, due to the supply of power, the N-oxy anion groups of the redox compound contained in the electrolyte layer 13 on the side closer to the second electrode 12 are oxidized to N-oxy radical groups, even if they were originally N-oxy anion groups. Even if carbon dioxide is bonded to the N-oxy anion groups, carbon dioxide is released from the redox compound when the N-oxy anion groups become N-oxy radical groups. Therefore, carbon dioxide is bound to the redox compound on the side closer to the first electrode 11, and then, when the redox compound bound to carbon dioxide flows through the electrolyte layer 13 to the side closer to the second electrode 12, carbon dioxide is desorbed from the redox compound on the side closer to the second electrode 12. It is believed that this binding and desorption of carbon dioxide to the redox compound enables the carbon dioxide separation device 1 to take in carbon dioxide on the first electrode 11 side and release carbon dioxide on the second electrode side.

[0073] The electrodes 11, 12 are not particularly limited as long as they are gas-permeable. That is, the electrodes 11, 12 may be conductive materials that are permeable to gases such as carbon dioxide and allow current to flow through the electrolyte layer 13 sandwiched between the pair of electrodes 11, 12. The electrodes 11, 12 are preferably porous materials that are conductive enough not to inhibit the movement of electrons and have excellent breathability, and specific examples thereof include electrodes made of porous conductive materials. More specific examples of the electrodes 11, 12 include porous materials containing carbon as a main component, porous materials made of carbon, and porous metal layers.

[0074] Specific examples of the carbon contained in the porous body include carbonaceous materials such as graphite, carbon nanotubes, activated carbon, activated carbon fiber, and carbon fiber. From the viewpoints of corrosion resistance and specific surface area, activated carbon and activated carbon fiber are preferred. Various carbonaceous materials may be used alone or in combination. The carbon-containing porous body is preferably a carbonaceous material in the form of cloth or felt. Therefore, more specific examples of the porous electrode include carbon sheets, carbon cloth, and carbon paper. Examples of the porous electrode include carbon-based electrodes using activated carbon or carbon fiber, and electrodes with high porosity using needle-shaped conductive materials. Among the above electrodes, the electrode preferably contains at least one material selected from the group consisting of graphite, carbon nanotubes, and carbon fiber. Such an electrode is believed to allow gas to pass through it, allowing the voltage application unit to apply a voltage between the electrodes. Therefore, by using this electrode, a carbon dioxide separation device can be obtained that can more efficiently separate carbon dioxide from a carbon dioxide-containing gas.

[0075] The porous metal layer is a metal layer having a large number of pores formed therein. The pores are preferably formed throughout the entire metal layer to provide excellent breathability. The method for obtaining the porous metal layer is not particularly limited, as long as it involves subjecting a metal layer without a large number of pores to a treatment to form a large number of pores (a porosity-improving method). Examples of such methods include physical methods such as cutting, polishing, and sandblasting, and chemical methods such as electrolytic etching and electroless etching using an acidic or alkaline etchant. The porosity-improving method may be used alone or in combination of two or more. Chemical methods are preferred for increasing the surface area and for forming denser pores (micropores). The material of the metal layer is not particularly limited, and examples include aluminum, copper, iron, titanium, tungsten, nickel, and alloys thereof. Among these, aluminum is preferred as the material for the metal layer from the standpoints of cost and processability. The metal layer is preferably an aluminum foil.

[0076] The BET specific surface area of ​​each of the electrodes 11 and 12 is not particularly limited, but may be, for example, 1 m 2 / g or more, and 100m 2 / g or more is more preferable, and 500m 2 The BET specific surface area of ​​each of the electrodes 11 and 12 is preferably large from the viewpoint of gas permeability (air permeability). 2 Therefore, the BET specific surface area of ​​each of the electrodes 11 and 12 is preferably 1 to 3000 m / g. 2 / g, and 100 to 2500m 2 / g, and more preferably 500 to 2000m 2 / g is more preferable. If the BET specific surface area of ​​each electrode is too small, gas permeability (air permeability) decreases, and permeation of carbon dioxide tends to be inhibited. If the BET specific surface area of ​​each electrode is too large, the strength of the electrode tends to be insufficient. For these reasons, if the BET specific surface area of ​​each electrode is within the above range, carbon dioxide separation can be achieved over a long period of time. The BET specific surface area is the specific surface area measured by the BET method and can be measured by a known method. Examples of methods for measuring the BET specific surface area include a method in which a nitrogen adsorption isotherm is measured and the BET specific surface area is calculated from the obtained adsorption isotherm.

[0077] As described above, each of the electrodes 11 and 12 is a conductive member that can pass a current through the electrolyte layer 13 sandwiched between the pair of electrodes 11 and 12, and the smaller the surface resistance, the better. For example, it is preferably 1 kΩ / sq or less, and more preferably 200 Ω / sq or less. Furthermore, the smaller the surface resistance of each electrode, the better, but in practice, 1 Ω / sq is the limit. Therefore, the surface resistance of each electrode is preferably 1 Ω / sq to 1 kΩ / sq, and more preferably 10 to 200 Ω / sq. Electrodes with such a surface resistance can pass a current through the electrolyte layer 13 and separate carbon dioxide effectively.

[0078] The thickness of each of the electrodes 11 and 12 is not particularly limited, but is preferably a thickness that can adsorb carbon dioxide and suitably prevent leakage of the electrolyte. The thickness of each of the electrodes 11 and 12 is preferably, for example, 20 μm to 10 mm, and more preferably 50 μm to 5 mm. If each of the electrodes is too thin, the strength of the electrode tends to be insufficient. If each of the electrodes is too thick, the gas permeability (breathability) tends to decrease, and the permeation of carbon dioxide tends to be hindered. For these reasons, if the thickness of each of the electrodes is within the above range, carbon dioxide separation can be achieved over a long period of time.

[0079] The electrolyte layer 13 is not particularly limited as long as it contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of absorbing and desorbing carbon dioxide through an electrochemical reaction. As described above, the electrolyte layer 13 is a carbon dioxide separator that contributes to the separation of carbon dioxide. The thickness of the electrolyte layer 13 is not particularly limited, but is preferably 0.1 μm to 2 mm, and more preferably 1 μm to 1 mm. If the electrolyte layer 13 is too thin, tiny holes, i.e., pinholes, tend to form in the electrolyte layer. If pinholes form, carbon dioxide cannot be suitably separated. If the electrolyte layer 13 is too thick, the carbon dioxide permeation rate, i.e., the carbon dioxide absorption and release rates, tend to be too slow.

[0080] The electrolyte solution is not particularly limited as long as it is an electrolyte solution capable of dissolving carbon dioxide, and may be an electrolyte solution containing an electrolyte and a solvent, or an electrolyte solution containing an ionic liquid. The electrolyte solution capable of dissolving carbon dioxide may be any electrolyte solution other than one in which carbon dioxide is not dissolved; that is, any electrolyte solution in which even a small amount of carbon dioxide dissolves is sufficient, and high solubility is not required. This is thought to be due to the following. As described above, in the carbon dioxide separation device according to this embodiment, carbon dioxide separation is thought to proceed through a mechanism in which carbon dioxide is taken up in the electrolyte layer on one electrode side by binding and desorption of carbon dioxide to the redox compound, and carbon dioxide is released in the electrolyte layer on the other electrode side. Therefore, it is thought that carbon dioxide separation will proceed if even a small amount of carbon dioxide dissolves in the electrolyte solution contained in the electrolyte layer.

[0081] The solvent is preferably an electrochemically stable compound with a wide potential window, and may be either an aqueous solvent or an organic solvent. Examples of the solvent include water, carbonate compounds, ester compounds, ether compounds, heterocyclic compounds, nitrile compounds, and aprotic polar compounds. Examples of the carbonate compounds include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate. Examples of the ester compounds include methyl acetate, methyl propionate, and γ-butyrolactone. Examples of the ether compounds include diethyl ether, 1,2-dimethoxyethane, 1,3-dioxosilane, tetrahydrofuran, and 2-methyl-tetrahydrofuran. Examples of the heterocyclic compounds include 3-methyl-2-oxazolidinone and 2-methylpyrrolidone. Examples of the nitrile compounds include acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and nitrile valerate. Examples of the aprotic polar compound include sulfolane, dimethyl sulfoxide, and dimethylformamide. The solvent may be any of the solvents exemplified above, or two or more of them may be used in combination. Among the solvents exemplified above, carbonate compounds such as ethylene carbonate and propylene carbonate, ester compounds such as γ-butyrolactone, heterocyclic compounds such as 3-methyl-2-oxazolidinone and 2-methylpyrrolidone, and nitrile compounds such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and valeric acid nitrile are preferred. When two or more of the solvents are used in combination, water is preferred from the viewpoint of dissolving carbon dioxide.

[0082] The electrolyte is not particularly limited, and examples thereof include quaternary ammonium salts, inorganic salts, and hydroxides. Examples of the quaternary ammonium salts include tetramethylammonium tetrafluoroborate, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, n-hexadecyltrimethylammonium tetrafluoroborate, tetra-n-hexadecylammonium tetrafluoroborate, tetra-n-octylammonium tetrafluoroborate, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium perchlorate, and tetraoctadecylammonium perchlorate. Examples of the inorganic salts include lithium perchlorate, sodium perchlorate, potassium perchlorate, sodium acetate, potassium acetate, sodium nitrate, and potassium nitrate. Examples of the hydroxides include sodium hydroxide and potassium hydroxide. Among the above-listed electrolytes, tetramethylammonium tetrafluoroborate, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, n-hexadecyltrimethylammonium tetrafluoroborate, tetra-n-hexadecylammonium tetrafluoroborate, tetra-n-octylammonium tetrafluoroborate, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium perchlorate, tetraoctadecylammonium perchlorate, lithium perchlorate, sodium perchlorate, sodium acetate, and potassium acetate are preferred. Among these, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, lithium perchlorate, and sodium perchlorate are more preferred, and tetra-n-butylammonium tetrafluoroborate and lithium perchlorate are even more preferred.The electrolyte may have a pH buffering ability by stabilizing carbonate ions or bicarbonate ions as a supporting salt. Specific examples of the electrolyte include sodium bicarbonate, sodium carbonate, acetic acid, and sodium acetate. The electrolyte may be any of the above-listed electrolytes, or a combination of two or more of them.

[0083] As described above, the electrolyte solution may be an electrolyte solution containing an ionic liquid (ionic liquid). When an ionic liquid is used as the electrolyte solution, the ionic liquid can have the functions of both an electrolyte and a solvent, without the need to include both. The electrolyte solution may contain an ionic liquid, and may be a liquid containing an electrolyte in an ionic liquid, a liquid containing a solvent in an ionic liquid, a liquid containing an electrolyte and a solvent in an ionic liquid, or a liquid consisting of an ionic liquid. Using an ionic liquid as the electrolyte solution is preferred because the ionic liquid is less likely to volatilize and has high flame retardancy. The ionic liquid is not particularly limited as long as it is a known ionic liquid, but examples include imidazolium-based ionic liquids, pyridine-based ionic liquids, alicyclic amine-based ionic liquids, and azonium amine-based ionic liquids. Examples of the ionic liquid include 1-methyl-3-octylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, 1,3-dimethoxyimidazolium tetrafluoroborate, and 1,3-diethoxyimidazolium tetrafluoroborate. trifluoroborate, 1-methyl-3-octylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-decyl-3-methylimidazolium hexafluorophosphate, 1,3-dimethoxyimidazolium hexafluorophosphate, and 1,3-diethoxyimidazolium hexafluorophosphate.Of the ionic liquids exemplified above, 1-methyl-3-octylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), 1,3-dimethoxyimidazolium tetrafluoroborate, 1-methyl-3-octylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluorophosphate are preferred as the ionic liquid. The ionic liquid is more preferably 1-methyl-3-octylimidazolium tetrafluoroborate, 1,3-dimethoxyimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), 1-butyl-3-methylimidazolium chloride, or 1-methyl-3-octylimidazolium hexafluorophosphate, and even more preferably 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), 1-butyl-3-methylimidazolium chloride, or 1-methyl-3-octylimidazolium tetrafluoroborate.

[0084] The electrolyte layer may be formed by gelling the electrolyte solution. Specifically, a gelling agent for gelling the electrolyte solution may be added, or a gelled electrolyte or polymer electrolyte may be used. Examples of the gelling agent include polymers, gelling agents that utilize techniques such as polymer crosslinking reactions, polymerizable polyfunctional monomers, and oil gelling agents. The gelled electrolyte and the polymer electrolyte are not particularly limited as long as they can be used as a gelled electrolyte or a polymer electrolyte. Examples include vinylidene fluoride polymers such as polyvinylidene fluoride, acrylic acid polymers such as polyacrylic acid, acrylonitrile polymers such as polyacrylonitrile, polyether polymers such as polyethylene oxide, and compounds having an amide structure in their structure.

[0085] Compounds capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction include organic redox compounds, redox compounds such as redox compounds having a quinone group in the molecule, and neutral radical compounds. Among these, redox compounds having an N-oxy radical group in the molecule, which are more durable than quinone compounds, are preferred from the standpoint of durability. When this redox compound is placed in a state where the N-oxy radical group is reduced by applying a voltage between the electrodes, the N-oxy radical group becomes an N-oxy anion group. When the N-oxy anion group is placed in a state where it is oxidized by applying a voltage between the electrodes, the N-oxy anion group returns to an N-oxy radical. The redox compound is a compound in which the N-oxy radical group changes through oxidation-reduction in this manner.

[0086] Specific examples of the redox compound include a compound represented by the following formula (1) and a compound having a group in which one hydrogen atom has been eliminated from the compound represented by the following formula (1). The compound having a group in which one hydrogen atom has been eliminated from the compound represented by the following formula (1) may be any compound having such a group, and may be a compound bonded to another low molecular weight compound or a high molecular weight compound.

[0087] [ka]

[0088] In formula (1), Z is -CR5R6CR7R8-, -CR9R 10 CR 11 R 12 CR 13 R 14 -, -(CR 15 R 16 )O-, -(CR 17 R 18 )NR 27 -, -(CR 19 R 20 )O(CR 21 R 22 )-, or -(CR 23 R 24 )NR28 (CR 25 R 26 )-, R1~R 28 each independently represents a hydrogen atom or a substituent.

[0089] It is preferable that at least one of R1 to R4 is a substituent, more preferably two or more are substituents, and even more preferably all four are substituents. That is, the compound represented by formula (1) is preferably a compound in which two quaternary carbons are bonded to the N-oxy radical group. Furthermore, it is preferable that the redox compound is a compound in which two quaternary carbons are bonded to the N-oxy radical group, or a compound having a group in which one hydrogen atom has been eliminated from this compound. It is believed that such a compound is more likely to undergo oxidation-reduction by the N-oxy radical group, and that the redox compound can more efficiently take in and release carbon dioxide. Therefore, by incorporating such a compound into the electrolyte layer, a carbon dioxide separator can be obtained that can more efficiently separate carbon dioxide from a gas containing carbon dioxide.

[0090] In the compound represented by the formula (1), Z is -CR5R6CR7R8, -CR9R 10 CR 11 R 12 CR 13 R 14 -, -(CR 19 R 20 )O(CR 21 R 22 )-and-(CR 23 R 24 )NR 28 (CR 25 R 26 )- is preferred.

[0091] The R1 to R 28Examples of the substituent in R1 to R2 include a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 10 carbon atoms, a hydroxyl group, an amino group which may be substituted (an unsubstituted or substituted amino group), a carboxyl group, a thiol group, and a silyl group which may be substituted (an unsubstituted or substituted silyl group). 26 Among these, the substituents in R are preferably a hydrocarbyl group having 1 to 30 carbon atoms, a hydroxy group, and an unsubstituted or substituted amino group. 27 , R 28 The substituent in is preferably a hydrocarbyl group having 1 to 30 carbon atoms.

[0092] Here, "optionally substituted" includes both cases where the hydrogen atoms constituting the compound or group described immediately thereafter are unsubstituted and cases where some or all of the hydrogen atoms are substituted with substituents.

[0093] The hydrocarbyl group is not particularly limited and may be linear, branched, or cyclic. Examples of the hydrocarbyl group include a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, a 1-butyl group, a 2-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a norbornyl group, an ammonium ethyl group, a benzyl group, an α,α-dimethylbenzyl group, a 1-phenethyl group, a 2-phenethyl group, a vinyl group, a propenyl group, a butenyl group, an oleyl group, an eicosapentaenyl group, a docosahexaenyl group, a 2,2-diphenylvinyl group, a 1,2,2-tri ... Examples of such groups include a phenylvinyl group, a 2-phenyl-2-propenyl group, a phenyl group, a 2-tolyl group, a 4-tolyl group, a 4-trifluoromethylphenyl group, a 4-methoxyphenyl group, a 4-cyanophenyl group, a 2-biphenylyl group, a 3-biphenylyl group, a 4-biphenylyl group, a terphenylyl group, a 3,5-diphenylphenyl group, a 3,4-diphenylphenyl group, a pentaphenylphenyl group, a 4-(2,2-diphenylvinyl)phenyl group, a 4-(1,2,2-triphenylvinyl)phenyl group, a fluorenyl group, a 1-naphthyl group, a 2-naphthyl group, a 9-anthryl group, a 2-anthryl group, a 9-phenanthryl group, a 1-pyrenyl group, a chrysenyl group, a naphthacenyl group, and a coronyl group.Among these, methyl group, ethyl group, 1-propyl group, 2-propyl group, 1-butyl group, 2-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, 2-ethylhexyl group, 3,7-dimethyloctyl group, benzyl group, α,α-dimethylbenzyl group, 1-phenethyl group, 2-phenethyl group, vinyl group, propenyl group, butenyl group, oleyl group, eicosapentaenyl group, docosahexaenyl group, 2,2-diphenylvinyl group, 1,2,2-triphenylvinyl group, 2-phenyl-2-propenyl group, phenyl Preferred are phenyl, 2-tolyl, 4-tolyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-cyanophenyl, 2-biphenylyl, 3-biphenylyl, 4-biphenylyl, terphenylyl, 3,5-diphenylphenyl, 3,4-diphenylphenyl, pentaphenylphenyl, 4-(2,2-diphenylvinyl)phenyl, 4-(1,2,2-triphenylvinyl)phenyl, fluorenyl, 1-naphthyl, 2-naphthyl, 9-anthryl, 2-anthryl, and 9-phenanthryl groups. Furthermore, among these, methyl group, ethyl group, 1-propyl group, 2-propyl group, 1-butyl group, 2-butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, 3,7-dimethyloctyl group, benzyl group, and phenyl group are preferred, and methyl group, ethyl group, 1-propyl group, 2-propyl group, 1-butyl group, 2-butyl group, isobutyl group, tert-butyl group, pentyl group, and hexyl group are even more preferred.

[0094] The hydrocarbyloxy group is not particularly limited, and may be linear, branched, or cyclic. Examples of the hydrocarbyloxy group include a methoxy group, an ethoxy group, a 1-propyloxy group, a 2-propyloxy group, a 1-butoxy group, a 2-butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a decyloxy group, a dodecyloxy group, a 2-ethylhexyloxy group, a 3,7-dimethyloctyloxy group, a cyclopropanoxy group, a cyclopentyloxy group, a cyclohexyloxy group, a 1-adamantyloxy group, a 2-adamantyloxy group, a norbornyloxy group, an ammoniumethoxy group, a trifluoromethoxy group, a benzyloxy group, an α,α-dimethylbenzyloxy group, a 2-phenethyloxy group, a 1-phenethyloxy group, a phenoxy group, an alkoxyphenoxy group, an alkylphenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, and a pentafluorophenyloxy group. Among these, methoxy, ethoxy, 1-propyloxy, 2-propyloxy, 1-butoxy, 2-butoxy, tert-butoxy, pentyloxy, hexyloxy, octyloxy, decyloxy, dodecyloxy, 2-ethylhexyloxy, and 3,7-dimethyloctyloxy are preferred, and among these, methoxy, ethoxy, 1-propyloxy, 2-propyloxy, 1-butoxy, 2-butoxy, isobutoxy, tert-butoxy, pentyloxy, and hexyloxy are more preferred.

[0095] The amino group is not particularly limited and may be linear, branched, or cyclic. Examples of the amino group include a methylamino group, an ethylamino group, a 1-propylamino group, a 2-propylamino group, a 1-butylamino group, a 2-butylamino group, an isobutylamino group, a tert-butylamino group, a pentylamino group, a hexylamino group, an octylamino group, a decylamino group, a dodecylamino group, a 2-ethylhexylamino group, a 3,7-dimethyloctylamino group, a cyclopropylamino group, a cyclopentylamino group, a cyclohexylamino group, a 1-adamantylamino group, a 2-adamantylamino group, a norbornylamino group, an ammoniumethylamino group, a trifluoromethylamino group, a benzylamino group, an α,α-dimethylbenzylamino group, a 2-phenethylamino group, a 1-phenethylamino group, a phenylamino group, an alkoxyphenylamino group, an alkylphenylamino group, a 1-naphthylamino group, a 2-naphthylamino group, and a pentafluorophenylamino group. Among these, methylamino, ethylamino, 1-propylamino, 2-propylamino, 1-butylamino, 2-butylamino, tert-butylamino, pentylamino, hexylamino, octylamino, decylamino, dodecylamino, 2-ethylhexylamino, and 3,7-dimethyloctylamino are preferred, and among these, methylamino, ethylamino, 1-propylamino, 2-propylamino, 1-butylamino, 2-butylamino, isobutylamino, tert-butylamino, pentylamino, and hexylamino are more preferred.

[0096] The silyl group is not particularly limited, and examples of the silyl group include a dimethylsilyl group, a diethylsilyl group, a diphenylsilyl group, a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group, a t-butyldiphenylsilyl group, and a tristrimethylsilyl group.

[0097] As described above, the compound represented by formula (1) is preferably a compound in which two quaternary carbons are bonded to the N-oxy radical group. It is believed that the radical stability is increased and radical coupling can be suppressed by bonding a group with high steric hindrance to a site adjacent to the N-oxy radical group. Therefore, it is believed that by incorporating such a compound into the electrolyte layer, a carbon dioxide separator capable of more effectively separating carbon dioxide from a gas containing carbon dioxide can be obtained.

[0098] Examples of the compound represented by formula (1) include N,N-di-tert-butyl nitroxide radical, N,N-diphenyl nitroxide radical, N,N-dinaphthyl nitroxide radical, N,N-di-2-methylphenyl nitroxide radical, N,N-di-3-methylphenyl nitroxide radical, N,N-di-4-methylphenyl nitroxide radical, N,N-di-2-ethylphenyl nitroxide radical, N,N-di-2-propylphenyl nitroxide radical, N,N-di-2-butylphenyl nitroxide radical, N ,N-di-2-pentylphenyl nitroxide radical, N,N-di-2-hexylphenyl nitroxide radical, N,N-di-2-isopropylphenyl nitroxide radical, N,N-di-2-isobutylphenyl nitroxide radical, N,N-di-2-sec-butylphenyl nitroxide radical, N,N-di-2-tert-butylphenyl nitroxide radical, N,N-di-4-tert-butylphenyl nitroxide radical, N,N-di-(3,5-di-tert-butyl)phenyl nitroxide radical, N,N-di -4-pyridyl nitroxide radical, N,N-di-4-pyridazyl nitroxide radical, poly(ethylene glycol)-bis-2,2,6,6-tetramethylpiperidinyloxy radical, N-phenyl-N-oxy-tert-butylamine, N-naphthyl-N-oxy-tert-butylamine, N-tert-butyl-N-oxy-2-quinoline, 2,2,6,6-tetramethylpiperidinyloxy radical (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-amino-2,2,6, 6-Tetramethylpiperidinyloxy radical, 4-carboxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-methoxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-oxo-2,2,6,6-tetramethylpiperidinyloxy radical, 4-acetamido-2,2,6,6-tetramethylpiperidinyloxy radical, 4-octyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, 2,2,5,5-tetramethylpyrrolidineoxy radical, 3-carbamoyl-2,2,5,Examples include 5-tetramethylpyrrolidine-oxy radical, 3-carboxy-2,2,5,5-tetramethylpyrrolidine-oxy radical, 2,2,6,6-tetramethylmorpholine-N-oxy radical, and 2,2,6,6-tetramethylmorpholinepiperazine-N-oxy radical.

[0099] As described above, the redox compound may be a polymeric compound, and examples thereof include compounds obtained by polymerizing a compound represented by formula (1). Examples of the polymeric compound include compounds obtained by polymerizing a monomer such as a 4-acryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, a 4-methacryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, a 3-acryloyloxy-2,2,6,6-tetramethylpyrrolidinyloxy radical, a 3-methacryloyloxy-2,2,6,6-tetramethylpyrrolidinyloxy radical, a 4-vinyloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, or a 4-vinyloyloxy-2,2,5,5-tetramethylpyrrolidinyloxy radical. The polymeric compound may be a compound obtained by polymerizing a single monomer, or may be a compound obtained by polymerizing two or more of the monomers in combination. The polymer compound may be a compound obtained by polymerizing the compound represented by formula (1), or may be a copolymer obtained by copolymerizing the compound with a copolymerizable monomer such as ethylene, propylene, butadiene, isoprene, styrene, vinyl acetate, etc. These copolymerizable monomers may also be used alone or in combination of two or more.

[0100] The compound represented by formula (1) may be a compound obtained by synthesis using a predetermined synthesis method, or may be a commercially available product. The synthesis method is not particularly limited as long as it is a synthesis method that can obtain the compound represented by formula (1), and examples thereof include a method of nitroxidizing the amino group of a disubstituted amine compound.

[0101] The electrolyte layer 13 may contain components other than the electrolytic solution and the redox compound. Examples of other components contained in the electrolyte layer 13 include polyethylene glycol, polyacrylate, polymethacrylate, and polyvinyl alcohol acetal.

[0102] The electrolyte layer 13 may include a substrate. For example, the electrolyte layer 13 may be formed by impregnating the substrate with the electrolytic solution containing the compound. Examples of the substrate include synthetic fiber nonwoven fabric and glass fiber nonwoven fabric.

[0103] The method for producing the electrolyte layer 13 is not particularly limited as long as the electrolyte layer 13 can be produced. When the electrolyte layer 13 includes the base material, for example, a method can be used in which the compound is dispersed or dissolved in the electrolyte solution and the base material is impregnated with the electrolyte solution containing the compound. The impregnation is preferably carried out while applying ultrasonic vibrations to the electrolyte solution and the base material. This can prevent the formation of minute holes, i.e., pinholes, in the electrolyte layer.

[0104] There are no particular limitations on the manufacturing method of the carbon dioxide separation device 1 as long as it can be manufactured with the above structure. Specifically, examples include a method of assembling the electrodes 11, 12 and the electrolyte layer 13 using a general assembly method so as to form the structure shown in FIG.

[0105] This specification discloses various aspects of the technology as described above, but the main technologies among them are summarized below.

[0106] A control device for a carbon dioxide separation device according to one embodiment is a control device for a carbon dioxide separation device that controls the power supply to a carbon dioxide separation device that has a pair of first and second electrodes that are permeable to gases and are arranged on either side of an electrolyte layer, and that, when power is supplied, takes in carbon dioxide through the first electrode and releases the taken-in carbon dioxide through the second electrode.The control device comprises a constant-voltage DC power supply that supplies power to the carbon dioxide separation device and is capable of varying the current, a carbon dioxide measuring unit that measures the carbon dioxide concentration outside the first electrode or the second electrode, and a current control unit that controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration measured by the carbon dioxide measuring unit, and the electrolyte layer contains an electrolytic solution that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction.

[0107] Such a carbon dioxide separation apparatus control device controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration outside the first electrode or outside the second electrode, allowing the carbon dioxide separation apparatus to be used efficiently from the viewpoint of energy consumption.The above-mentioned carbon dioxide separation apparatus control device can suppress continuous activation of organic matter, allowing the organic matter to be used stably over a long period of time and carbon dioxide to be separated.

[0108] In another aspect, the above-mentioned carbon dioxide separator control device further includes a flow rate variable unit that varies the flow rate of the gas outside the first electrode or the second electrode, and the current control unit controls the current of the constant-voltage DC power supply to decrease the current when the carbon dioxide concentration measured by the carbon dioxide measuring unit is equal to or less than a first threshold, and controls the current of the constant-voltage DC power supply to increase the current when the carbon dioxide concentration measured by the carbon dioxide measuring unit is equal to or greater than a second threshold that is greater than the first threshold, and the flow rate variable unit increases the flow rate of the gas while the current control unit is controlling the current of the constant-voltage DC power supply to decrease the current. Preferably, in the above-mentioned carbon dioxide separator control device, the flow rate variable unit includes an air pump (fan) that sends the gas to a first flow path or draws the gas from the first flow path, a flow rate adjustment valve that is provided in a communication path that communicates the first flow path with the air pump and adjusts the flow rate of the gas flowing through the communication path, and a flow rate control unit that controls the flow rate of the flow rate adjustment valve. Preferably, in the above-mentioned control device for a carbon dioxide separator, the flow rate varying unit is provided in a communication passage that communicates with a host system on the upstream side or downstream side of the second flow passage, and includes a flow rate adjustment valve that adjusts the flow rate of the gas flowing through the communication passage, and a flow rate control unit that controls the flow rate of the flow rate adjustment valve. Note that the first flow passage may be a container (first container), and the second flow passage may be a container (second container).

[0109] Such a control device for a carbon dioxide separator increases the flow rate of gas while the current control section controls the current of the constant voltage DC power supply so as to decrease the current, and therefore, during that time, the decreased carbon dioxide concentration can be restored.

[0110] In another aspect, the above-mentioned control device for a carbon dioxide separation device further includes a flow rate variable unit that varies the flow rate of the gas outside the first electrode or outside the second electrode, and the current control unit controls the current of the constant-voltage DC power supply to stop power supply when the carbon dioxide concentration measured by the carbon dioxide measuring unit is equal to or less than a third threshold, and controls the current of the constant-voltage DC power supply to start power supply when the carbon dioxide concentration measured by the carbon dioxide measuring unit is equal to or greater than a fourth threshold that is greater than the third threshold, and the flow rate variable unit increases the flow rate of the gas while the current control unit is controlling the current of the constant-voltage DC power supply to stop power supply.

[0111] This carbon dioxide separation apparatus control device stops power supply when the carbon dioxide concentration becomes equal to or less than the third threshold, allowing for more efficient use of the carbon dioxide separation apparatus.The carbon dioxide separation apparatus control device increases the gas flow rate while the current control unit controls the current of the constant-voltage DC power supply to stop power supply, allowing the reduced carbon dioxide concentration to recover during that time.

[0112] In another aspect, in the above-described carbon dioxide separator control device, the constant voltage DC power supply comprises a solar cell or a fuel cell.

[0113] Such a control device for a carbon dioxide separation device can contribute to carbon neutrality during operation of the carbon dioxide separation device.

[0114] In another aspect, in the above-mentioned carbon dioxide separator control device, the compound is a compound that adsorbs carbon dioxide by electrolytic reduction and desorbs carbon dioxide by electrolytic oxidation. Preferably, in the above-mentioned carbon dioxide separator control device, the compound is a compound that adsorbs carbon dioxide when the potential between the pair of first and second electrodes is relatively low and accepts electrons, and desorbs carbon dioxide when the potential is relatively high and supplies electrons. Preferably, in the above-mentioned carbon dioxide separator control device, the compound is a redox compound. Preferably, in the above-mentioned carbon dioxide separator control device, the compound is a redox compound having an N-oxy radical group in the molecule.

[0115] When power is supplied to this carbon dioxide separation device, electrons move from the first electrode to the second electrode due to a hopping mechanism caused by the compound, regardless of whether or not the compound transports carbon dioxide from the first electrode to the second electrode, thereby consuming electrical energy. The carbon dioxide separation device control device controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration, and therefore can reduce the movement of electrons caused by the compound when the carbon dioxide concentration is low and therefore the compound is likely not to transport carbon dioxide from the first electrode to the second electrode, making the carbon dioxide separation device suitable for the carbon dioxide separation device control device.

[0116] A control method for a carbon dioxide separation device according to one embodiment is a control method for a carbon dioxide separation device that controls the power supply to a carbon dioxide separation device that has a pair of first and second electrodes that are arranged on an electrolyte layer so as to sandwich the electrolyte layer and are permeable to gases, and that, when powered by a constant-voltage DC power supply that can vary the current, takes in carbon dioxide through the first electrode and releases the taken-in carbon dioxide through the second electrode, and includes a carbon dioxide measurement step that measures the carbon dioxide concentration outside the first electrode or the second electrode, and a current control step that controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration measured in the carbon dioxide measurement step, and the electrolyte layer contains an electrolytic solution that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction.

[0117] This carbon dioxide separation apparatus control method controls the current of the constant-voltage DC power supply in accordance with the carbon dioxide concentration outside the first electrode or outside the second electrode, allowing the carbon dioxide separation apparatus to be used efficiently from the viewpoint of energy consumption.The carbon dioxide separation apparatus control method can suppress continuous activation of organic matter, allowing the organic matter to be used stably over a long period of time and carbon dioxide to be separated.

[0118] One embodiment of the carbon dioxide separation system comprises a carbon dioxide separation device that is arranged on an electrolyte layer so as to sandwich the electrolyte layer and has a pair of first and second electrodes that are permeable to gas, and that, when power is supplied, takes in carbon dioxide through the first electrode and releases the taken-in carbon dioxide through the second electrode, and a carbon dioxide separation device control device that controls the carbon dioxide separation device, and the carbon dioxide separation device control device is any of the carbon dioxide separation device control devices described above.

[0119] This provides a carbon dioxide separation system equipped with any of the above-described carbon dioxide separator control devices. This carbon dioxide separation system allows the carbon dioxide separator to be used efficiently from the viewpoint of energy consumption. The carbon dioxide separation system can suppress continuous activation of organic matter, allowing the organic matter to be used stably over a long period of time and carbon dioxide to be separated.

[0120] This application is based on Japanese Patent Application No. 2024-039208, filed on March 13, 2024, the contents of which are incorporated herein by reference.

[0121] In order to express the present invention, the present invention has been properly and sufficiently described above through the embodiments with reference to the drawings, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims. [Industrial Applicability]

[0122] According to the present invention, it is possible to provide a control device for a carbon dioxide separator, a control method for a carbon dioxide separator, and a carbon dioxide separation system including the control device for a carbon dioxide separator.

Claims

1. A control device for a carbon dioxide separation device that controls the supply of power to a carbon dioxide separation device comprising a pair of first and second electrodes that are provided on an electrolyte layer so as to sandwich the electrolyte layer, and that are permeable to gas, and that takes in carbon dioxide through the first electrode when power is supplied and releases the taken-in carbon dioxide through the second electrode, a constant voltage DC power supply that supplies power to the carbon dioxide separation device and is capable of varying current; a carbon dioxide measuring unit that measures the concentration of carbon dioxide outside the first electrode or the second electrode; a current control unit that controls the current of the constant voltage DC power supply in accordance with the concentration of carbon dioxide measured by the carbon dioxide measuring unit, the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of absorbing and desorbing carbon dioxide through an electrochemical reaction; Control device for carbon dioxide separation unit.

2. a flow rate varying unit that varies a flow rate of the gas outside the first electrode or outside the second electrode; the current control unit controls the current of the constant voltage DC power supply to decrease the current when the concentration of carbon dioxide measured by the carbon dioxide measuring unit is equal to or less than a first threshold, and controls the current of the constant voltage DC power supply to increase the current when the concentration of carbon dioxide measured by the carbon dioxide measuring unit is equal to or more than a second threshold that is greater than the first threshold, the flow rate varying unit increases the flow rate of the gas while the current control unit controls the current of the constant voltage DC power supply so as to decrease the current; The control device for a carbon dioxide separator according to claim 1 .

3. a flow rate varying unit that varies a flow rate of the gas outside the first electrode or outside the second electrode; the current control unit controls the current of the constant voltage DC power supply to stop power supply when the concentration of carbon dioxide measured by the carbon dioxide measuring unit is equal to or less than a third threshold, and controls the current of the constant voltage DC power supply to start power supply when the concentration of carbon dioxide measured by the carbon dioxide measuring unit is equal to or more than a fourth threshold that is greater than the third threshold, the flow rate varying unit increases the flow rate of the gas while the current control unit controls the current of the constant voltage DC power supply so as to stop the power supply. The control device for a carbon dioxide separator according to claim 1 .

4. The constant voltage DC power supply comprises a solar cell or a fuel cell. The control device for a carbon dioxide separator according to claim 1 .

5. The compound is a compound that adsorbs carbon dioxide by electrolytic reduction and desorbs carbon dioxide by electrolytic oxidation. The control device for a carbon dioxide separator according to claim 1 .

6. the compound is a compound that adsorbs carbon dioxide when it accepts electrons when the potential between the pair of first and second electrodes is relatively low, and desorbs carbon dioxide when it supplies electrons when the potential between the pair of first and second electrodes is relatively high; The control device for a carbon dioxide separator according to claim 1 .

7. The compound is a redox compound. The control device for a carbon dioxide separator according to claim 1 .

8. The compound is a redox compound having an N-oxy radical group in the molecule. The control device for a carbon dioxide separator according to claim 1 .

9. A control method for a carbon dioxide separator, comprising: a pair of first and second electrodes that are disposed on an electrolyte layer so as to sandwich the electrolyte layer and are permeable to gas; and when power is supplied from a constant-voltage DC power supply that can vary current, the carbon dioxide separator takes in carbon dioxide via the first electrode and releases the taken-in carbon dioxide via the second electrode, a carbon dioxide measuring step of measuring a carbon dioxide concentration outside the first electrode or outside the second electrode; a current control step of controlling the current of the constant voltage DC power supply in accordance with the concentration of carbon dioxide measured in the carbon dioxide measurement step, the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of absorbing and desorbing carbon dioxide through an electrochemical reaction; Control method for a carbon dioxide separator.

10. a carbon dioxide separation device comprising a pair of first and second electrodes that are disposed on the electrolyte layer so as to sandwich the electrolyte layer, and that are permeable to gases, and that, when power is supplied, takes in carbon dioxide through the first electrode and releases the taken carbon dioxide through the second electrode; a carbon dioxide separation apparatus control device that controls the carbon dioxide separation apparatus, The carbon dioxide separation apparatus control device is the carbon dioxide separation apparatus control device according to any one of claims 1 to 8. Carbon dioxide separation system.

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