Gas adsorption system and method for operating the gas adsorption system

Abstract

The present invention provides a gas adsorption system and a gas adsorption system operation method whereby it is possible to efficiently separate and recover a prescribed gas. A gas adsorption system according to an embodiment of the present invention comprises a plurality of gas adsorption units each including an electrochemical element configured to adsorb and release a prescribed gas. The plurality of gas adsorption units include a first adsorption unit to which the prescribed gas is supplied and a second adsorption unit to which gas that has passed through the first adsorption unit is supplied.

Description

[Technical Field]

[0001] The present invention relates to a gas adsorption system and a method for operating a gas adsorption system. [Background technology]

[0002] The development of technologies for separating and capturing specific gases from gas mixtures is continuously progressing. In particular, in recent years, efforts have been made to separate and capture carbon dioxide (CO2) from gas mixtures in response to the need to reduce carbon dioxide (CO2) emissions in order to mitigate global warming. A representative example of such efforts is the carbon dioxide capture, utilization, and storage (CCUS) cycle. Known methods for capturing carbon dioxide include chemical adsorption, physical adsorption, cryogenic separation, membrane separation, and electrochemical capture. However, currently, all of these technologies have insufficient carbon dioxide capture capacity and are limited in their efficient capture, leaving many issues to be addressed before they can be put to practical use. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-533470 Summary of the Invention [Problem to be solved by the invention]

[0004] A primary object of the present invention is to provide a gas adsorption system and a method for operating the gas adsorption system that can efficiently separate and recover a predetermined gas. [Means for solving the problem]

[0005] [1] A gas adsorption system according to an embodiment of the present invention includes a plurality of gas adsorption units each including an electrochemical element configured to adsorb and release a predetermined gas, the plurality of gas adsorption units including a first adsorption unit to which the predetermined gas is supplied and a second adsorption unit to which gas that has passed through the first adsorption unit is supplied. [2] In the gas adsorption system described in [1] above, the electrochemical device comprises a functional electrode containing a first active material and a counter electrode containing a second active material. [3] In the gas adsorption system described in [2] above, the predetermined gas may be carbon dioxide, the first active material may include anthraquinone, and the second active material may include polyvinylferrocene. [4] In the gas adsorption system described in any one of [1] to [3] above, the plurality of gas adsorption sections may further include a third adsorption section to which gas that has passed through the second adsorption section is supplied. [5] An operating method of a gas adsorption system according to an embodiment of the present invention is a method of operating the gas adsorption system described above, and includes a first adsorption step of supplying the specified gas to the first adsorption section and supplying the gas that has passed through the first adsorption section to the second adsorption section, thereby allowing the specified gas to be adsorbed by the first adsorption section and the second adsorption section; and a second adsorption step of stopping the supply of the specified gas to the first adsorption section and supplying the specified gas to the second adsorption section and supplying the gas that has passed through the second adsorption section to the third adsorption section, thereby allowing the specified gas to be adsorbed by the second adsorption section and the third adsorption section. [6] The method of operating the gas adsorption system described in [5] above may further include a first release step of releasing the specified gas adsorbed in the first adsorption section from the first adsorption section after completion of the first adsorption step and before completion of the second adsorption step, and a third adsorption step of stopping the supply of the specified gas to the second adsorption section and supplying the specified gas to the third adsorption section, supplying the gas that has passed through the third adsorption section to the first adsorption section, and adsorbing the specified gas into the first adsorption section and the third adsorption section. [7] The method of operating the gas adsorption system described in [6] above may further include a second release step of sequentially repeating the first adsorption step, the second adsorption step, and the third adsorption step, after completion of the second adsorption step and before completion of the third adsorption step, releasing the specified gas adsorbed in the second adsorption section from the second adsorption section, and a third release step of releasing the specified gas adsorbed in the third adsorption section from the third adsorption section after completion of the third adsorption step and before completion of the repeated first adsorption step. [Effects of the Invention]

[0006] According to the embodiments of the present invention, it is possible to realize a gas adsorption system and a method for operating a gas adsorption system that can efficiently separate and recover a predetermined gas. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a gas adsorption system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view of an electrochemical element provided in the gas adsorption system of FIG. [Figure 3] 3 is a schematic cross-sectional view of the electrochemical device of FIG. 2 in a direction parallel to the direction in which the cells extend. [Figure 4] 4 is an enlarged schematic cross-sectional view of a main part of the electrochemical device of FIGS. 2 and 3 in a direction perpendicular to the direction in which the cells extend. FIG. [Figure 5] FIG. 4 is an enlarged schematic cross-sectional view of a main part of an electrochemical element according to another embodiment of the present invention, taken in a direction perpendicular to the direction in which the cells extend. [Figure 6] FIG. 10 is an enlarged schematic cross-sectional view of a main part of an electrochemical element according to yet another embodiment of the present invention, taken in a direction perpendicular to the direction in which the cells extend. [Figure 7] FIG. 10 is an enlarged schematic cross-sectional view of a main part of an electrochemical element according to yet another embodiment of the present invention, taken in a direction perpendicular to the direction in which the cells extend. [Figure 8] FIG. 10 is an enlarged schematic cross-sectional view of a main part of an electrochemical element according to yet another embodiment of the present invention, taken in a direction perpendicular to the direction in which the cells extend. [Figure 9] FIG. 1 is a process flow diagram illustrating a method of operating a gas adsorption system according to one embodiment of the present invention. [Figure 10] FIG. 10 is a process flow diagram illustrating the first adsorption step of FIG. 9. [Figure 11] FIG. 10 is a process flow diagram illustrating the second adsorption step of FIG. 9. [Figure 12] FIG. 10 is a process flow diagram illustrating the third adsorption step of FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

[0009] A. Overall configuration of the gas adsorption system A gas adsorption system according to an embodiment of the present invention separates and recovers a selected gas (e.g., carbon dioxide) from a gas mixture using an electrochemical element configured to adsorb and release the selected gas (e.g., carbon dioxide) through an electrochemical process.

[0010] 1 is a schematic diagram of a gas adsorption system according to one embodiment of the present invention. The illustrated gas adsorption system 110 includes a plurality of adsorption towers 11 as an example of a gas adsorption section. The adsorption tower 11 includes an electrochemical element configured to adsorb and release a predetermined gas (e.g., carbon dioxide). The plurality of adsorption towers 11 include a first adsorption tower 11a as an example of a first adsorption unit and a second adsorption tower 11b as an example of a second adsorption unit. The first adsorption tower 11a is supplied with the predetermined gas (e.g., carbon dioxide). The second adsorption tower 11b is supplied with the gas that has passed through the first adsorption tower 11a. With this configuration, the predetermined gas can be sequentially adsorbed in the first adsorption tower 11a and the second adsorption tower 11b. Even if the predetermined gas slips from the first adsorption tower 11a, the slipped predetermined gas can be adsorbed in the second adsorption tower 11b. For example, when separating and recovering a predetermined gas from a gas mixture using a single adsorption tower 11, it is necessary to provide a distance (inlet section) required for adsorption of the predetermined gas at the downstream end of the gas adsorption region of the adsorption tower 11 in the direction of passage of the gas mixture to prevent the predetermined gas from slipping from the adsorption tower 11. In a typical adsorption process, the inlet section is a marginal region that is not used for adsorption of the predetermined gas. In contrast, with the above-described configuration, even if the predetermined gas slips from the first adsorption tower 11a, the second adsorption tower 11b can adsorb the predetermined gas. Therefore, the inlet section in the gas adsorption region of the first adsorption tower 11a can be shortened, and the gas adsorption capacity of the first adsorption tower 11a can be efficiently utilized. Furthermore, the gas adsorption capacity of the first adsorption tower 11a can be fully utilized without providing an inlet section in the gas adsorption region of the first adsorption tower 11a. As a result, the predetermined gas can be efficiently separated and recovered from the gas mixture, and slippage of the predetermined gas from the gas adsorption system 110 can be suppressed. For example, exhaust gas from a factory or thermal power plant contains approximately 10% carbon dioxide. A gas mixture having a similar composition to such exhaust gas can be passed through the adsorption tower 11 in a gas adsorption system according to one embodiment of the present invention, with the carbon dioxide concentration reduced to 0.1% or less.

[0011] In one embodiment of the present invention, the multiple adsorption towers 11 further include a third adsorption tower 11c as an example of a third adsorption section. That is, the multiple adsorption towers 11 may include a first adsorption tower 11a, a second adsorption tower 11b, and a third adsorption tower 11c. The third adsorption tower 11c is supplied with gas that has passed through the second adsorption tower 11b. With this configuration, after the first adsorption tower 11a has completed adsorption of the predetermined gas, the second adsorption tower 11b and the third adsorption tower 11c can be used to adsorb the predetermined gas. Furthermore, during adsorption of the predetermined gas in the second adsorption tower 11b and the third adsorption tower 11c, the predetermined gas can be released from the first adsorption tower 11a.

[0012] In one embodiment of the present invention, the gas adsorption system 110 includes, in addition to a plurality of adsorption towers 11, a gas supply unit 21, an exhaust unit 31, a gas recovery unit 41, a first connection unit 61, a second connection unit 71, a third connection unit 81, and a control unit 51. With this configuration, a predetermined gas (e.g., carbon dioxide) can be smoothly separated and recovered from a gas mixture, and the predetermined gas adsorbed in the adsorption towers 11 can be smoothly released from the adsorption towers 11.

[0013] The components of the gas adsorption system will now be described in detail.

[0014] B. Adsorption tower In one embodiment of the present invention, the multiple adsorption towers 11 (first adsorption tower 11a, second adsorption tower 11b, and third adsorption tower 11c) may have the same configuration as each other or different configurations from each other. The multiple adsorption towers 11 (first adsorption tower 11a, second adsorption tower 11b, and third adsorption tower 11c) preferably have the same configuration as each other. If the multiple adsorption towers 11 have the same configuration as each other, equipment costs can be reduced. The adsorption tower 11 includes multiple electrochemical elements and a reaction vessel that houses the multiple electrochemical elements.

[0015] B-1. Electrochemical element Fig. 2 is a schematic perspective view of an electrochemical element included in the gas adsorption system of Fig. 1; Fig. 3 is a schematic cross-sectional view parallel to the direction in which the cells of the electrochemical element of Fig. 2 extend; and Fig. 4 is an enlarged schematic cross-sectional view of a main part of the electrochemical element of Fig. 2 and Fig. 3, taken in a direction perpendicular to the direction in which the cells extend. The electrochemical element 100 of the illustrated example includes a functional electrode 50 and a counter electrode 60.

[0016] B-1-1. Functional electrode The functional electrode includes a first active material and is configured to collect and release a predetermined gas (e.g., carbon dioxide). A typical example of the first active material is anthraquinone. Anthraquinone can collect (capture, adsorb) and release carbon dioxide through an electrochemical reaction described below. The anthraquinone may be a polyanthraquinone (i.e., a polymer). Examples of polyanthraquinone include poly(1,4-anthraquinone), poly(1,5-anthraquinone), poly(1,8-anthraquinone), and poly(2,6-anthraquinone) represented by the following formula (I). These may be used alone or in combination. [ka]

[0017] The first active material may be any suitable material other than anthraquinone, as long as it can capture and release (particularly capture) a predetermined gas (e.g., carbon dioxide). Examples of such materials include tetrachlorohydroquinone (TCHQ), hydroquinone (HQ), dimethoxybenzoquinone (DMBQ), naphthoquinone (NQ), tetracyanoquinodimethane (TCNQ), dihydroxybenzoquinone (DHBQ), and polymers thereof.

[0018] The functional electrode may further include a substrate. Here, the term "substrate" refers to a component that shapes the electrode (layer) and maintains its shape. Furthermore, the substrate may support a first active material. The substrate is typically conductive. Examples of the substrate include carbonaceous materials. Examples of carbonaceous materials include carbon nanotubes (e.g., single-walled carbon nanotubes, multi-walled carbon nanotubes), carbon black, Ketjen Black, carbon black Super P, and graphene. By using such a carbonaceous material as the substrate, electron transfer can be easily performed, thereby enabling the oxidation-reduction reaction of the first active material to be performed satisfactorily. For example, when anthraquinone or polyanthraquinone is used as the first active material, the average pore diameter of the substrate is preferably 2 nm to 50 nm, more preferably 2 nm to 20 nm, and even more preferably 3 nm to 10 nm. If the average pore diameter is too small, the first active material may not be supported inside. If the average pore diameter is too large, the first active material may fall off during operation of the functional electrode. The average pore diameter of the substrate may vary depending on the first active material. For example, when naphthoquinone is used as the first active material, the average pore diameter is preferably about two-thirds of the above size. The average pore diameter can be calculated, for example, using BJH analysis in a nitrogen gas adsorption method.

[0019] The content of the first active material in the functional electrode may be, for example, 10% to 70% by mass, or 20% to 50% by mass, based on the total mass of the functional electrode. When the content of the first active material is within this range, good gas recovery and release performance can be achieved.

[0020] B-1-2. Counter electrode The counter electrode can function as an electron source for the reduction of the first active material and as an electron acceptor for the oxidation of the first active material. In other words, the counter electrode plays an auxiliary role in ensuring good functioning of the functional electrode. The counter electrode contains a second active material. Any appropriate material can be used as the second active material as long as it can efficiently exchange electrons with the functional electrode. Examples of the second active material include polyvinylferrocene and poly(3-(4-fluorophenyl))thiophene. The counter electrode has the highest potential, so it is required to be resistant to oxidation by oxygen in the gas mixture. If oxidation resistance is ensured, a carbon material may be used as the second active material.

[0021] The counter electrode may further include a substrate. The substrate is as described above in Section B-1-1 for the functional electrode. In one embodiment, the second active material is dispersed in the substrate. Dispersing the second active material in the substrate can achieve excellent electronic conductivity within the electrode.

[0022] The counter electrode may further contain an ionic liquid. By containing an ionic liquid in the counter electrode, the counter electrode can function three-dimensionally, and the capacity for donating and receiving electrons can be increased. As the ionic liquid, any appropriate ionic liquid can be used depending on the purpose, the configuration of the electrochemical device, etc. The ionic liquid may typically contain an anion component and a cation component. Examples of the anion component of the ionic liquid include halides, sulfates, sulfonates, carbonates, bicarbonates, phosphates, nitric acids, acetic acids, and PF6. - , BF4 -, triflates, nonaflates, bis(triflyl)amides, trifluoroacetic acids, heptafluorobutanoic acids, haloaluminates, triazolides, and amino acid derivatives (e.g., proline with the nitrogen proton removed). Examples of the cationic component of ionic liquids include imidazolium, pyridinium, pyrrolidinium, phosphonium, ammonium, sulfonium, thiazolium, pyrazolium, piperidinium, triazolium, pyrazolium, oxazolium, guanazinium, and dialkylmorpholinium. Examples of ionic liquids include 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]). + [BF4] - When the gas species to be separated and recovered is carbon dioxide, it is preferable to use a non-aqueous ionic liquid, since water may be electrolyzed due to the potential window.

[0023] The content of the second active material in the counter electrode may be, for example, 10% to 90% by mass, or 30% to 70% by mass, based on the total mass of the counter electrode. If the content of the second active material is within this range, the amount of electrolyte (ionic liquid) used can be reduced, and the second active material in the counter electrode can be effectively utilized.

[0024] When the counter electrode contains an ionic liquid, the content thereof may be, for example, 10% to 90% by mass, or, for example, 30% to 70% by mass, based on the total mass of the counter electrode. If the content of the ionic liquid is within this range, the electrolyte (ionic liquid) can be continuously supplied to the functional electrode for a long period of time.

[0025] B-1-3.Support In one embodiment of the present invention, the functional electrode 50 and the counter electrode 60 are supported by a support 80. The support 80 has an outer peripheral wall 10 and partition walls 40 disposed inside the outer peripheral wall 10 and defining a plurality of cells 30, 30, ... extending from a first end surface 20 a to a second end surface 20 b.

[0026] The plurality of cells 30, 30, ... includes a first cell 30a and a second cell 30b. A functional electrode 50 containing a first active material is formed on the surface of the partition wall 40 defining the first cell 30a. This configuration significantly increases the contact area between the functional electrode and a predetermined flow rate of a gas mixture (substantially, the gas to be separated and recovered) while ensuring sufficient strength. As a result, a predetermined gas (e.g., carbon dioxide) can be separated and recovered with extremely high efficiency. Furthermore, it is possible to efficiently separate and recover a predetermined gas (e.g., carbon dioxide) even with a small-scale facility, and the energy required for separating and recovering the gas can be significantly reduced. Thus, according to one embodiment of the present invention, by adopting the above-described so-called honeycomb structure as the basic structure of an electrochemical element, it is possible to efficiently separate and recover gases with energy savings and a small-scale facility.

[0027] A gas flow path 70 is formed in the center of the first cell 30a in a cross section perpendicular to the cell extension direction (i.e., the portion where the functional electrode 50 is not formed). The functional electrode 50 may be formed on the entire surface of the partition wall 40 (i.e., so as to surround the gas flow path 70) as in the illustrated example, or may be formed on a portion of the surface of the partition wall. In consideration of the efficiency of gas separation and recovery, it is preferable that the functional electrode 50 be formed on the entire surface of the partition wall 40.

[0028] The thickness of the functional electrode 50 may be, for example, 20 μm to 300 μm, or may be, for example, 100 μm to 200 μm. If the thickness of the functional electrode is within this range, it is possible to ensure a desired gas flow path while maintaining good gas recovery and release performance.

[0029] The functional electrode 50 can be formed, for example, by applying a functional electrode-forming material containing a first active material, a substrate, and a binding binder to the surface of the partition wall under a dry reduced pressure, followed by heat treatment.

[0030] A counter electrode 60 containing a second active material is disposed inside the second cell 30b. The second cell 30b is typically filled with the counter electrode 60. Filling the second cell 30b with the counter electrode allows the electrolyte (ionic liquid) to be continuously supplied to the functional electrode for a long period of time.

[0031] Counter electrode 60 can be formed, for example, by placing a counter electrode-forming material containing a second active material, a substrate, preferably an ionic liquid, and optionally a solvent or dispersion medium in a cell (typically, by filling the cell).

[0032] The arrangement pattern of the first cells 30a and the second cells 30b can be appropriately set depending on the purpose as long as the effects of the embodiments of the present invention can be obtained. In the example shown in FIGS. 2 to 4, the first cells 30a and the second cells 30b are arranged alternately (i.e., in a checkerboard pattern). This configuration allows the counter electrode to function properly, thereby enabling the electrochemical reaction at the functional electrode to proceed smoothly. Furthermore, the proportion of second cells 30b among the multiple cells 30, 30, . . . may be reduced as long as the number (proportion) of counter electrodes that can function is ensured. That is, the proportion of first cells 30a (effectively, the functional electrode 50 and the gas flow path 70) may be increased. For example, in the example shown in FIGS. 5 to 8, the second cells 30b are arranged so as not to be adjacent to each other. In this case, the first cells 30a may be arranged so as to be adjacent to each other. Here, "not adjacent to each other" means that two cells do not share any sides or vertices of the partition walls that define each cell. With this configuration, the contact area between a predetermined flow rate of the gas mixture (substantially, the gas to be separated and recovered) and the functional electrode can be further increased, thereby further improving the gas separation and recovery performance. In this case, the first cell 30a can typically share the partition wall 40 with at least one second cell 30b. For example, the second cells 30b may be arranged as shown in each of FIGS. 5 to 8.

[0033] The cells 30, 30, ... have any appropriate cross-sectional shape in a direction perpendicular to the cell extension direction. In the example shown in Figures 2 to 6, the partition walls 40 defining the cells are perpendicular to each other, defining cells having a quadrangular (square in the illustrated example) cross-sectional shape except for the portion in contact with the outer peripheral wall 10. In one embodiment, the cross-sectional shape of the cells is a uniform quadrangular shape (e.g., square, rectangle, parallelogram, or rhombus). The cross-sectional shape of the cells may be a square, a circle, an ellipse, a triangle, a pentagon, a polygon having hexagons or more, or other shapes. For example, in the example shown in Figures 7 and 8, the cross-sectional shape of the cells is hexagonal. This configuration has the advantages of easy formation of the functional electrode and counter electrode, small pressure loss when gas flows, and excellent separation and recovery performance.

[0034] The cell density in the direction perpendicular to the cell extension direction (i.e., the number of cells 30, 30, ... per unit area) can be appropriately set depending on the purpose. The cell density is, for example, 4 cells / cm 2 ~320 cells / cm 2 If the cell density is within this range, the contact area between the gas mixture at a predetermined flow rate (substantially, the gas to be separated and recovered) and the functional electrode can be made very large. As a result, it is possible to separate and recover a predetermined gas (e.g., carbon dioxide) with extremely high efficiency. For example, if the packing density of a flat gas separation element in which a functional electrode and a counter electrode are opposed to each other via a separator is 0.2 m 2 / L, whereas the above configuration is 2m 2 This allows for a packaging density of approximately 10 times that of conventional gas separators. As a result, it becomes possible to efficiently separate and capture specific gases (e.g., carbon dioxide) using small-scale equipment, and the energy required for the separation and capture of the gas can be significantly reduced. Furthermore, by ensuring this packaging density, it may become possible to separate and capture carbon dioxide from the atmosphere (Direct Air Capture: DAC).

[0035] The support 80 (the outer peripheral wall 10 and the partition walls 40) is typically made of a porous material containing insulating ceramics. The insulating ceramic typically contains cordierite, alumina, or silicon carbide and silicon (hereinafter, sometimes referred to as a silicon carbide-silicon composite). The ceramic contains cordierite, alumina, silicon carbide, and silicon in a total amount of, for example, 90 mass% or more, for example, 95 mass% or more. This configuration can sufficiently increase the volume resistivity of the outer peripheral wall and the partition walls at 400°C, thereby suppressing leakage current due to electronic conductivity. Therefore, only the desired electrochemical reaction can be efficiently carried out throughout the entire functional electrode 50 and the counter electrode 60. The ceramic may contain a substance other than the silicon carbide-silicon composite. Examples of such substances include strontium.

[0036] A silicon carbide-silicon composite typically contains silicon carbide particles as an aggregate and silicon as a binder that bonds the silicon carbide particles. In the silicon carbide-silicon composite, for example, a plurality of silicon carbide particles are bonded by silicon so as to form pores (voids) between the silicon carbide particles. That is, the partition wall 40 and the outer peripheral wall 10 containing the silicon carbide-silicon composite may be, for example, porous.

[0037] The silicon content in the silicon carbide-silicon composite is preferably 10% by mass to 40% by mass, and more preferably 15% by mass to 35% by mass. If the silicon content is too low, the strength of the outer peripheral wall and partition walls may be insufficient. If the silicon content is too high, the outer peripheral wall and partition walls may not be able to maintain their shape during firing.

[0038] The average particle diameter of the silicon carbide particles is preferably 3 μm to 50 μm, more preferably 3 μm to 40 μm, and even more preferably 10 μm to 35 μm. When the average particle diameter of the silicon carbide particles is within this range, the volume resistivity of the outer peripheral wall and partition walls can be set to the appropriate range as described above. If the average particle diameter of the silicon carbide particles is too large, the raw material may clog the molding die when molding the outer peripheral wall and partition walls. The average particle diameter of the silicon carbide particles can be measured, for example, by laser diffraction.

[0039] The average pore diameter of the support 80 (the outer peripheral wall 10 and the partition walls 40) is preferably 2 μm to 20 μm, more preferably 10 μm to 20 μm. When the average pore diameter of the outer peripheral wall and the partition walls is within this range, the ionic liquid can be impregnated well. If the average pore diameter is too large, the carbonaceous material in the counter electrode or the functional electrode may leak into the partition walls, which may result in an internal short circuit. The average pore diameter can be measured, for example, by a mercury porosimeter.

[0040] The porosity of the support 80 (outer peripheral wall 10 and partition walls 40) is preferably 15% to 60%, and more preferably 30% to 45%. If the porosity is too small, the outer peripheral wall and partition walls may be significantly deformed during firing. If the porosity is too large, the strength of the outer peripheral wall and partition walls may be insufficient. The porosity can be measured, for example, by a mercury porosimeter.

[0041] The thickness of the partition wall 40 can be appropriately set depending on the purpose. The thickness of the partition wall 40 is, for example, 50 μm to 1.0 mm, or may be, for example, 70 μm to 600 μm. When the thickness of the partition wall is within this range, the electrochemical device can have sufficient mechanical strength and a sufficient opening area (total area of ​​the cells in the cross section), thereby significantly improving the gas separation and recovery efficiency.

[0042] The density of the partition walls 40 can be appropriately set depending on the purpose. The density of the partition walls 40 is, for example, 0.5 g / cm 3 ~5.0g / cm3 If the density of the partition wall is in this range, the electrochemical device can be made lighter and have sufficient mechanical strength. The density can be measured by, for example, the Archimedes method.

[0043] In one embodiment of the present invention, the thickness of the outer peripheral wall 10 is greater than the thickness of the partition walls 40. With this configuration, it is possible to prevent the outer peripheral wall from being broken, broken, cracked, etc. due to external forces. The thickness of the outer peripheral wall 10 is, for example, 0.1 mm to 5 mm, and can also be, for example, 0.3 mm to 2 mm.

[0044] In one embodiment of the present invention, the voids in the partition wall 40 and the outer peripheral wall 10 are impregnated with an ionic liquid. With this configuration, the partition wall and the outer peripheral wall (particularly the partition wall) can function well as a separator between the functional electrode and the counter electrode. Furthermore, impregnation with the ionic liquid suppresses electronic conductivity, allowing only the desired electrochemical reaction to occur efficiently. In one embodiment, the ionic liquid contained in the functional electrode is the same as the ionic liquid contained in the outer peripheral wall and the partition wall (particularly the partition wall). With this configuration, the electrochemical device can be manufactured simply and easily, and adverse effects on the electrochemical reaction of the functional electrode can be prevented.

[0045] The shape of the electrochemical element can be appropriately designed depending on the purpose. The electrochemical element 100 in the illustrated example is cylindrical (the cross-sectional shape in the direction perpendicular to the cell extension direction is circular), but the electrochemical element may also be cylindrical, for example, with an elliptical or polygonal cross-sectional shape (e.g., quadrilateral, pentagonal, hexagonal, or octagonal). The length of the electrochemical element can be appropriately set depending on the purpose. The length of the electrochemical element can be, for example, 5 mm to 500 mm. The diameter of the electrochemical element can be appropriately set depending on the purpose. The diameter of the electrochemical element can be, for example, 20 mm to 500 mm. When the cross-sectional shape of the electrochemical element is not circular, the diameter of the electrochemical element can be the diameter of the largest inscribed circle inscribed in the cross-sectional shape (e.g., polygonal) of the electrochemical element. The aspect ratio (diameter:length) of the electrochemical element is, for example, 1:12 or less, for example, 1:5 or less, or for example, 1:1 or less. If the aspect ratio is within this range, the current collection resistance can be set within an appropriate range.

[0046] For convenience, the configuration of the electrochemical device 100 has been described above by illustrating one electrochemical device 100. However, in one embodiment of the present invention, a plurality of electrochemical devices 100 are housed in the reaction vessel of the adsorption tower 11. The region in the adsorption tower 11 where the plurality of electrochemical devices 100 are arranged is the gas adsorption region. The plurality of electrochemical devices 100 housed in the reaction vessel may be aligned in the direction in which the cells extend so that the gas flow paths 70 communicate with each other. Furthermore, the rows of the plurality of electrochemical devices 100 aligned in the direction in which the cells extend may be arranged in a direction perpendicular to the direction in which the cells extend. Furthermore, the electrochemical devices 100 housed in the reaction vessel may be arranged so that the direction in which the cells extend is parallel to the vertical direction.

[0047] Although not shown, in one embodiment of the present invention, the functional electrode 50 and the counter electrode 60 included in the electrochemical device 100 are electrically connected to a power supply. The power supply can apply a voltage to the functional electrode 50. The power supply includes a constant voltage power supply and a polarity reversing circuit that can reverse the polarity of the voltage applied to the functional electrode 50.

[0048] In the embodiment of the present invention described above, the electrochemical device 100 includes a support 80 having multiple cells 30, and the support 80 supports the functional electrode 50 and the counter electrode 60. However, the electrochemical device is not limited to this configuration. For example, the electrochemical device may include multiple flat gas separation elements, each of which has a functional electrode and a counter electrode facing each other with a separator interposed therebetween, spaced apart in a direction parallel to the thickness of the gas separation element. The gas separation element may have a rectangular shape elongated in a predetermined direction when viewed in the thickness direction. An example of such an electrochemical device is the electrochemical cell described in JP-A-2018-533470. When multiple electrochemical devices each having a gas separation element are housed in the reaction vessel of the adsorption tower 11, the multiple electrochemical devices may be aligned in the longitudinal direction of the gas separation element so that adjacent gas separation elements are connected to each other. Furthermore, the rows of multiple electrochemical devices aligned in the longitudinal direction of the gas separation element may be arranged in a direction intersecting the longitudinal direction of the gas separation element.

[0049] B-1-4. Electrochemical reaction The operation of the electrochemical device 100 will be outlined below. For example, the case will be described where the gas to be separated and recovered is carbon dioxide, the first active material of the functional electrode 50 contains anthraquinone, and the second active material of the counter electrode 60 contains polyvinylferrocene. The anthraquinone of the functional electrode 50 can be reduced when a positive voltage is applied as an adsorption voltage in the charging mode (the functional electrode is the negative electrode).

[0050] When a gas mixture containing carbon dioxide is passed through the gas flow path 70 of the electrochemical device, the following reaction (1) occurs between the anthraquinone in a reduced state on the functional electrode 50 and the carbon dioxide, and the carbon dioxide is captured by the anthraquinone. In this way, carbon dioxide can be recovered. [ka]

[0051] At this time, the polyvinylferrocene of the counter electrode 60 can be oxidized, i.e., the polyvinylferrocene can function as an electron source for the reduction of anthraquinone in the charging mode.

[0052] Furthermore, anthraquinone in the functional electrode 50 can be oxidized when a negative voltage of opposite polarity to the adsorption voltage is applied as a release voltage in a discharge mode (when the functional electrode is a positive electrode).

[0053] When the anthraquinone that has captured carbon dioxide is oxidized at the functional electrode 50, the following reaction (2) occurs, and the carbon dioxide captured by the anthraquinone is released from the bond with the anthraquinone. In this way, the carbon dioxide can be released from the functional electrode 50 to the gas flow path 70. [ka]

[0054] At this time, the polyvinylferrocene of the counter electrode 60 can be reduced, i.e., the polyvinylferrocene can act as an electron acceptor during the oxidation of anthraquinone in the discharge mode.

[0055] As described above, by switching the polarity of the functional electrode (and consequently the counter electrode), the electrochemical device (effectively the functional electrode) can capture (capture, adsorb) and release carbon dioxide. In particular, by utilizing the reduced anthraquinone in the charging mode, carbon dioxide can be separated and captured (captured) from the gas mixture. In this way, the electrochemical device 100 can capture carbon dioxide.

[0056] C. Gas supply section 1, the gas supply unit 21 can supply a gas mixture (e.g., exhaust gas) containing a predetermined gas (e.g., carbon dioxide) to the adsorption towers 11 (first adsorption tower 11a, second adsorption tower 11b, and third adsorption tower 11c). In one embodiment of the present invention, the gas supply unit 21 includes a gas supply line 21a, a first supply valve 21b, a second supply valve 21c, a third supply valve 21d, and a blower 21e.

[0057] The gas supply line 21a is a pipe through which a gas mixture containing a predetermined gas can pass. The downstream end of the gas supply line 21a in the direction in which the gas mixture passes branches off to correspond to the plurality of adsorption towers 11 and is connected to each of the adsorption towers 11. In one embodiment of the present invention, the downstream end of the branched gas supply line 21a is connected to the lower end of the adsorption tower 11. Although not shown, the upstream end of the gas supply line 21a is connected to a facility (e.g., a factory or a thermal power plant) where a gas mixture containing the predetermined gas is generated.

[0058] The first supply valve 21b, the second supply valve 21c, and the third supply valve 21d are each capable of opening and closing the gas supply line 21a and are, for example, solenoid valves. The first supply valve 21b is provided at a branching portion of the gas supply line 21a connected to the first adsorption tower 11a. The second supply valve 21c is provided at a branching portion of the gas supply line 21a connected to the second adsorption tower 11b. The third supply valve 21d is provided at a branching portion of the gas supply line 21a connected to the third adsorption tower 11c.

[0059] The blower 21e is capable of sending the gas mixture passing through the gas supply line 21a toward the adsorption tower 11. The blower 21e is provided in the gas supply line 21a. The blower 21e is located upstream of the branched portion of the gas supply line 21a in the direction in which the gas mixture passes through the gas supply line 21a.

[0060] D. Exhaust section The exhaust unit 31 can discharge the gas mixture, from the adsorption towers 11 (first adsorption tower 11a, second adsorption tower 11b, and third adsorption tower 11c), from which a predetermined gas (e.g., carbon dioxide) has been removed. In one embodiment of the present invention, the exhaust unit 31 includes an exhaust line 31a, a first exhaust valve 31b, a second exhaust valve 31c, and a third exhaust valve 31d.

[0061] The exhaust line 31a is a pipe through which the gas mixture from which a predetermined gas has been removed can pass. The upstream end of the exhaust line 31a in the direction in which the gas mixture passes branches off to correspond to the plurality of adsorption towers 11 and is connected to each of the adsorption towers 11. In one embodiment of the present invention, the upstream ends of the branched exhaust lines 31a are connected to the upper ends of the adsorption towers 11. Although not shown, the downstream end of the exhaust line 31a is open to the atmosphere.

[0062] The first exhaust valve 31b, the second exhaust valve 31c, and the third exhaust valve 31d are each capable of opening and closing the exhaust line 31a and are, for example, solenoid valves. The first exhaust valve 31b is provided at a branching portion of the exhaust line 31a connected to the first adsorption tower 11a. The second exhaust valve 31c is provided at a branching portion of the exhaust line 31a connected to the second adsorption tower 11b. The third exhaust valve 31d is provided at a branching portion of the exhaust line 31a connected to the third adsorption tower 11c.

[0063] E. Gas recovery section The gas recovery unit 41 can recover a predetermined gas (e.g., carbon dioxide) that is once adsorbed in the adsorption towers 11 (first adsorption tower 11a, second adsorption tower 11b, and third adsorption tower 11c) and then released from the adsorption towers 11 (first adsorption tower 11a, second adsorption tower 11b, and third adsorption tower 11c). In one embodiment of the present invention, the gas recovery unit 41 includes a gas recovery line 41a, a first recovery valve 41b, a second recovery valve 41c, a third recovery valve 41d, and a pump 41e.

[0064] The gas recovery line 41a is a pipe through which a predetermined gas can pass. The upstream end of the gas recovery line 41a in the direction in which the predetermined gas passes branches off to correspond to the plurality of adsorption towers 11 and is connected to each of the adsorption towers 11. In one embodiment of the present invention, the upstream ends of the branched gas recovery lines 41a are connected to the lower ends of the adsorption towers 11. Although not shown, the downstream end of the gas recovery line 41a is connected to a storage facility for the predetermined gas.

[0065] The first recovery valve 41b, the second recovery valve 41c, and the third recovery valve 41d are each capable of opening and closing the gas recovery line 41a and are, for example, solenoid valves. The first recovery valve 41b is provided at a branching portion of the gas recovery line 41a connected to the first adsorption tower 11a. The second recovery valve 41c is provided at a branching portion of the gas recovery line 41a connected to the second adsorption tower 11b. The third recovery valve 41d is provided at a branching portion of the gas recovery line 41a connected to the third adsorption tower 11c.

[0066] The pump 41e can send the predetermined gas passing through the gas recovery line 41a toward the storage facility. The pump 41e is, for example, a vacuum pump. The pump 41e is provided in the gas recovery line 41a. The pump 41e is located downstream of the branched portion of the gas recovery line 41a in the direction in which the predetermined gas passes through the gas recovery line 41a.

[0067] F. First connection part The first connection part 61 is capable of supplying the gas mixture (first adsorption tower passing gas) that has passed through the first adsorption tower 11a to the second adsorption tower 11b. In one embodiment of the present invention, the first connection part 61 includes a first connection line 61a and a first connection valve 61b.

[0068] The first connection line 61a is a pipe through which the gas mixture that has passed through the first adsorption tower 11a can pass. The first connection line 61a connects the first adsorption tower 11a and the second adsorption tower 11b. In one embodiment of the present invention, the upstream end of the first connection line 61a in the direction of passage of the first adsorption tower passing gas is connected to the upper end of the first adsorption tower 11a. The downstream end of the first connection line 61a in the direction of passage of the first adsorption tower passing gas is connected to the lower end of the second adsorption tower 11b.

[0069] The first connection valve 61b is capable of opening and closing the first connection line 61a and is, for example, a solenoid valve. The first connection valve 61b is provided on the first connection line 61a.

[0070] G. Second connection part The second connection part 71 is capable of supplying the gas mixture (second adsorption tower passing gas) that has passed through the second adsorption tower 11b to the third adsorption tower 11c. In one embodiment of the present invention, the second connection part 71 includes a second connection line 71a and a second connection valve 71b.

[0071] The second connection line 71a is a pipe through which the gas mixture that has passed through the second adsorption tower 11b can pass. The second connection line 71a connects the second adsorption tower 11b and the third adsorption tower 11c. In one embodiment of the present invention, the upstream end of the second connection line 71a in the direction of passage of the gas passing through the second adsorption tower is connected to the upper end of the second adsorption tower 11b. The downstream end of the second connection line 71a in the direction of passage of the gas passing through the second adsorption tower is connected to the lower end of the third adsorption tower 11c.

[0072] The second connection valve 71b is capable of opening and closing the second connection line 71a and is, for example, a solenoid valve. The second connection valve 71b is provided on the second connection line 71a.

[0073] H. Third connection part The third connection part 81 is capable of supplying the gas mixture (third adsorption tower passing gas) that has passed through the third adsorption tower 11c to the first adsorption tower 11a. In one embodiment of the present invention, the third connection part 81 includes a third connection line 81a and a third connection valve 81b.

[0074] The third connection line 81a is a pipe through which the gas mixture that has passed through the third adsorption tower 11c can pass. The third connection line 81a connects the third adsorption tower 11c and the first adsorption tower 11a. In one embodiment of the present invention, the upstream end of the third connection line 81a in the direction of passage of the gas passing through the third adsorption tower is connected to the upper end of the third adsorption tower 11c. The downstream end of the third connection line 81a in the direction of passage of the gas passing through the third adsorption tower is connected to the lower end of the first adsorption tower 11a.

[0075] The third connection valve 81b is capable of opening and closing the third connection line 81a and is, for example, a solenoid valve. The third connection valve 81b is provided on the third connection line 81a.

[0076] I. Control Unit The control unit 51 can control the operation of the gas adsorption system 110. The control unit 51 includes, for example, a central processing unit (CPU), a ROM, and a RAM. In one embodiment of the present invention, the control unit 51 is electrically connected to the first supply valve 21b, the second supply valve 21c, the third supply valve 21d, the first exhaust valve 31b, the second exhaust valve 31c, the third exhaust valve 31d, the first recovery valve 41b, the second recovery valve 41c, the third recovery valve 41d, the first connection valve 61b, the second connection valve 71b, the third connection valve 81b, the blower 21e, and the pump 41e. Although not shown, the control unit 51 is also electrically connected to a power supply device connected to the functional electrode 50 and the counter electrode 60.

[0077] The method of operating the gas adsorption system will now be described.

[0078] J. Gas Adsorption System Operation Method A method for operating a gas adsorption system according to one embodiment of the present invention is a method for operating the above-described gas adsorption system 110. Figure 9 is a process flow diagram illustrating the method for operating a gas adsorption system according to one embodiment of the present invention.

[0079] A method for operating a gas adsorption system according to one embodiment of the present invention includes a first adsorption step (S1) in which a predetermined gas (e.g., carbon dioxide) is supplied to a first adsorption tower 11a and the gas that has passed through the first adsorption tower 11a is supplied to a second adsorption tower 11b, thereby causing the first adsorption tower 11a and the second adsorption tower 11b to adsorb the predetermined gas; and a second adsorption step (S2) in which the supply of the predetermined gas to the first adsorption tower 11a is stopped and the predetermined gas is supplied to the second adsorption tower 11b, and the gas that has passed through the second adsorption tower 11b is supplied to a third adsorption tower 11c, thereby causing the second adsorption tower 11b and the third adsorption tower 11c to adsorb the predetermined gas. According to this method, in the first adsorption step, the predetermined gas can be sequentially adsorbed by the first adsorption tower 11a and the second adsorption tower 11b. Therefore, even if the predetermined gas slips from the first adsorption tower 11a, the slipped predetermined gas can be adsorbed by the second adsorption tower 11b. Furthermore, in the second adsorption step, the third adsorption tower 11c is used instead of the first adsorption tower 11a, and the predetermined gas can be sequentially adsorbed in the second adsorption tower 11b and the third adsorption tower 11c. Therefore, even if the predetermined gas slips from the second adsorption tower 11b, the predetermined gas slipping from the second adsorption tower 11b can be adsorbed in the third adsorption tower 11c. As a result, the inlet sections of the gas adsorption regions of the first adsorption tower 11a and the second adsorption tower 11b can be shortened, allowing the gas adsorption capacities of the first adsorption tower 11a and the second adsorption tower 11b to be efficiently utilized. Furthermore, the gas adsorption capacities of the first adsorption tower 11a and the second adsorption tower 11b can be fully utilized without providing inlet sections in the gas adsorption regions of the first adsorption tower 11a and the second adsorption tower 11b. As a result, the predetermined gas can be efficiently separated and recovered from the gas mixture. When the gas adsorption system 110 includes three or more adsorption towers 11, the gas mixture containing a predetermined gas can be passed through three or more adsorption towers 11 in sequence to perform the adsorption process in three or more adsorption towers 11. However, from the viewpoint of pressure loss, it is preferable to perform the adsorption process in two adsorption towers 11, as in the above-described method.

[0080] Furthermore, a method for operating a gas adsorption system according to one embodiment of the present invention further includes a first release step of releasing the predetermined gas adsorbed in the first adsorption tower 11a from the first adsorption tower 11a after the completion of the first adsorption step and before the completion of the second adsorption step; and a third adsorption step (S3) of stopping the supply of the predetermined gas to the second adsorption tower 11b and supplying the predetermined gas to the third adsorption tower 11c, supplying the gas that has passed through the third adsorption tower 11c to the first adsorption tower 11a, and adsorbing the predetermined gas in the first adsorption tower 11a and the third adsorption tower 11c. According to this method, the predetermined gas adsorbed in the first adsorption tower 11a is released from the first adsorption tower 11a after the completion of the first adsorption step and before the completion of the second adsorption step. Therefore, the first adsorption tower 11a can be used in the third adsorption step, and the predetermined gas can be adsorbed in the third adsorption tower 11c and the first adsorption tower 11a in sequence. As a result, even if a predetermined gas slips from the third adsorption tower 11c, the slipped predetermined gas can be adsorbed in the first adsorption tower 11a. This shortens the inlet section of each gas adsorption region of the first adsorption tower 11a, the second adsorption tower 11b, and the third adsorption tower 11c, allowing for efficient use of the gas adsorption capacity of each of the first adsorption tower 11a, the second adsorption tower 11b, and the third adsorption tower 11c. Furthermore, the gas adsorption capacity of the first adsorption tower 11a, the second adsorption tower 11b, and the third adsorption tower 11c can be fully utilized without providing an inlet section in each gas adsorption region of the first adsorption tower 11a, the second adsorption tower 11b, and the third adsorption tower 11c. As a result, the predetermined gas can be efficiently separated and recovered from the gas mixture.

[0081] Furthermore, a method for operating a gas adsorption system according to one embodiment of the present invention further includes: a second release step of sequentially repeating a first adsorption step (S1), a second adsorption step (S2), and a third adsorption step (S3), in which the predetermined gas adsorbed in the second adsorption tower 11b is released from the second adsorption tower 11b after the second adsorption step and before the third adsorption step; and a third release step of releasing the predetermined gas adsorbed in the third adsorption tower 11c from the third adsorption tower 11c after the third adsorption step and before the repeated first adsorption step. This method allows the first adsorption step (S1), the second adsorption step (S2), and the third adsorption step (S3) to be smoothly repeated using the first adsorption tower 11a, the second adsorption tower 11b, and the third adsorption tower 11c, thereby efficiently separating and recovering the predetermined gas from the gas mixture.

[0082] In a method for operating a gas adsorption system according to one embodiment of the present invention, a first adsorption step (S1) is first carried out. Fig. 10 is a process flow diagram illustrating the first adsorption step of Fig. 9.

[0083] In the first adsorption step, a gas mixture (e.g., exhaust gas) containing a predetermined gas is supplied to the first adsorption tower 11a. More specifically, after application of an adsorption voltage to the functional electrode 50 of the first adsorption tower 11a and the functional electrode 50 of the second adsorption tower 11b is initiated, supply of the gas mixture (e.g., exhaust gas) containing the predetermined gas to the first adsorption tower 11a is initiated (S1-1).

[0084] The control unit 51 controls a power supply device (not shown) to start applying an adsorption voltage to the functional electrodes 50 of the first adsorption tower 11a and the second adsorption tower 11b. In one embodiment of the present invention, the adsorption voltage applied to the functional electrode 50 of the first adsorption tower 11a is the same as the adsorption voltage applied to the functional electrode 50 of the second adsorption tower 11b, and this adsorption voltage is, for example, 1.6 V to 2.0 V. The adsorption voltage applied to the functional electrode 50 of the first adsorption tower 11a may be different from the adsorption voltage applied to the functional electrode 50 of the second adsorption tower 11b.

[0085] Next, the control unit 51 opens the first supply valve 21b, the first connection valve 61b, and the second exhaust valve 31c, closes the other valves, and drives the blower 21e. When the blower 21e is driven, a gas mixture (e.g., exhaust gas) containing a predetermined gas is supplied to the first adsorption tower 11a through the gas supply line 21a. The gas mixture supplied to the first adsorption tower 11a passes through the first adsorption tower 11a and is discharged to the first connection line 61a. As the gas mixture passes through the first adsorption tower 11a, at least a portion of the predetermined gas contained in the gas mixture is adsorbed by the functional electrode 50 provided in the first adsorption tower 11a. The gas mixture that passed through the first adsorption tower 11a (first adsorption tower passing gas) is supplied to the second adsorption tower 11b through the first connection line 61a. The gas mixture supplied to the second adsorption tower 11b passes through the second adsorption tower 11b and is discharged to the exhaust line 31a. When the gas mixture passes through the second adsorption tower 11b, a predetermined gas contained in the gas mixture is adsorbed by the functional electrode 50 included in the second adsorption tower 11b.

[0086] Next, the adsorbed gas is not completely removed from the first adsorption tower, and the current I flows through the electrochemical element of the second adsorption tower. *2 is the preset threshold current I T Until this occurs, the supply of the gas mixture to the first adsorption tower 11a is maintained, and the application of the adsorption voltage to the functional electrodes 50 included in the first adsorption tower 11a and the second adsorption tower 11b continues (no in S1-2).

[0087] Current I flowing through the electrochemical element in the second adsorption tower *2 The threshold current I T If this is the case (Yes in S1-2), the supply of the gas mixture to the first adsorption tower 11a is stopped (S1-3). When all of the adsorbed gas (e.g., carbon dioxide) contained in the gas mixture in the first adsorption tower 11a is adsorbed onto the functional electrode 50 of the first adsorption tower 11a, the adsorbed gas is not supplied to the second adsorption tower 11b, and therefore the reaction between the first active material and the adsorbed gas (e.g., the above formula (1)) does not occur. In this case, no current flows through the electrochemical element in the second adsorption tower. On the other hand, if the adsorbed gas (e.g., carbon dioxide) is not completely removed in the first adsorption tower 11a and slips, the adsorbed gas is supplied to the second adsorption tower 11b, and the above reaction occurs, causing a current to flow through the electrochemical element. Therefore, the current value I flowing through the electrochemical element in the second adsorption tower 11b *2 Based on this, the timing to stop the supply of the gas mixture to the first adsorption tower 11a can be determined. This completes the first adsorption step.

[0088] In one embodiment of the present invention, the first adsorption step (S1) is followed by the second adsorption step (S2). FIG. 11 is a process flow diagram illustrating the second adsorption step of FIG. 9. In the second adsorption step, the supply of a gas mixture (e.g., exhaust gas) to the first adsorption tower 11a is stopped, and the gas mixture (e.g., exhaust gas) is supplied to the second adsorption tower 11b. More specifically, after application of an adsorption voltage to the functional electrode 50 of the third adsorption tower 11c is initiated, the supply of the gas mixture (e.g., exhaust gas) to the first adsorption tower 11a is stopped (S1-3), and the supply of the gas mixture (e.g., exhaust gas) to the second adsorption tower 11b is initiated (S2-1).

[0089] The control unit 51 controls a power supply device (not shown) to start applying an adsorption voltage to the functional electrode 50 of the third adsorption tower 11c and maintain the application of the adsorption voltage to the functional electrode 50 of the second adsorption tower 11b. The control unit 51 also controls a power supply device (not shown) to stop applying an adsorption voltage to the functional electrode 50 of the first adsorption tower 11a. In one embodiment of the present invention, the adsorption voltage applied to the functional electrode 50 of the third adsorption tower 11c is the same as the adsorption voltage applied to the functional electrode 50 of the second adsorption tower 11b. The adsorption voltage applied to the functional electrode 50 of the second adsorption tower 11b may be different from the adsorption voltage applied to the functional electrode 50 of the third adsorption tower 11c.

[0090] Next, the control unit 51 closes the first supply valve 21b, the first connection valve 61b, and the second exhaust valve 31c, and opens the second supply valve 21c, the second connection valve 71b, and the third exhaust valve 31d. The blower 21e continues to be driven during the second adsorption step. Consequently, the gas mixture (e.g., exhaust gas) containing the predetermined gas is supplied to the second adsorption tower 11b through the gas supply line 21a without being supplied to the first adsorption tower 11a. The gas mixture supplied to the second adsorption tower 11b passes through the second adsorption tower 11b and is discharged to the second connection line 71a. The gas mixture that passed through the second adsorption tower 11b (second adsorption tower passing gas) is supplied to the third adsorption tower 11c through the second connection line 71a. The gas mixture supplied to the third adsorption tower 11c passes through the third adsorption tower 11c and is discharged to the exhaust line 31a. The predetermined gas contained in the gas mixture is adsorbed onto the functional electrode 50 when passing through the second adsorption tower 11b and when passing through the third adsorption tower 11c.

[0091] Next, the adsorbed gas is not completely removed in the second adsorption tower, and the current I flows through the electrochemical element in the third adsorption tower. *3 is the preset threshold current I T Until this occurs, the supply of the gas mixture (e.g., exhaust gas) to the second adsorption tower 11b is maintained, and the application of the adsorption voltage to the functional electrodes 50 of the second adsorption tower 11b and the third adsorption tower 11c continues (no in S2-2).

[0092] Current I flowing through the electrochemical element in the third adsorption tower *3 The threshold current I T If this is the case (Yes in S2-2), the supply of the gas mixture (for example, exhaust gas) to the second adsorption tower 11b is stopped (S2-3), thereby completing the second adsorption step.

[0093] In one embodiment of the present invention, a first release step is performed after the first adsorption step and before the second adsorption step. In the first release step, a predetermined gas (e.g., carbon dioxide) adsorbed in the first adsorption tower 11a is released from the first adsorption tower 11a. More specifically, the controller 51 opens the first recovery valve 41b and controls a power supply (not shown) to apply a release voltage of opposite polarity to the adsorption voltage to the functional electrode 50 of the first adsorption tower 11a. This allows the predetermined gas (e.g., carbon dioxide) captured in the functional electrode 50 to be released from the functional electrode 50. The controller 51 also drives the pump 41e. The predetermined gas (e.g., carbon dioxide) released from the functional electrode 50 passes through the gas recovery line 41a and is sent to a storage facility (not shown). The controller 51 then stops driving the pump 41e.

[0094] In one embodiment of the present invention, the second adsorption step (S2) is followed by the third adsorption step (S3). FIG. 12 is a process flow diagram illustrating the third adsorption step of FIG. 9. In the third adsorption step, the supply of the gas mixture (e.g., exhaust gas) to the second adsorption tower 11b is stopped, and the gas mixture (e.g., exhaust gas) is supplied to the third adsorption tower 11c. More specifically, after application of an adsorption voltage to the functional electrode 50 of the first adsorption tower 11a is initiated, the supply of the gas mixture (e.g., exhaust gas) to the second adsorption tower 11b is stopped (S2-3), and the supply of the gas mixture (e.g., exhaust gas) to the third adsorption tower 11c is initiated (S3-1).

[0095] The control unit 51 controls a power supply device (not shown) to start applying an adsorption voltage to the functional electrode 50 of the first adsorption tower 11a and maintain application of the adsorption voltage to the functional electrode 50 of the third adsorption tower 11c. The control unit 51 also controls a power supply device (not shown) to stop application of the adsorption voltage to the functional electrode 50 of the second adsorption tower 11b. In one embodiment of the present invention, the adsorption voltage applied to the functional electrode 50 of the first adsorption tower 11a is the same as the adsorption voltage applied to the functional electrode 50 of the third adsorption tower 11c. The adsorption voltage applied to the functional electrode 50 of the first adsorption tower 11a may be different from the adsorption voltage applied to the functional electrode 50 of the third adsorption tower 11c.

[0096] Next, the control unit 51 closes the second supply valve 21c, the second connection valve 71b, and the third exhaust valve 31d, and opens the third supply valve 21d, the third connection valve 81b, and the first exhaust valve 31b. The blower 21e continues to be driven during the third adsorption step. The gas mixture (e.g., exhaust gas) containing the predetermined gas is supplied to the third adsorption tower 11c through the gas supply line 21a without being supplied to the first adsorption tower 11a or the second adsorption tower 11b. The gas mixture supplied to the third adsorption tower 11c passes through the third adsorption tower 11c and is discharged to the third connection line 81a. The gas mixture passed through the third adsorption tower 11c (third adsorption tower passing gas) is supplied to the first adsorption tower 11a through the third connection line 81a. The gas mixture supplied to the first adsorption tower 11a passes through the first adsorption tower 11a and is discharged to the exhaust line 31a. The predetermined gas contained in the gas mixture is adsorbed onto the functional electrode 50 when passing through the third adsorption tower 11c and when passing through the first adsorption tower 11a.

[0097] Next, in the third adsorption tower, the adsorbed gas is not completely removed, and the current I *1 is the preset threshold current I T Until this occurs, the supply of the gas mixture (e.g., exhaust gas) to the third adsorption tower 11c is maintained, and the application of the adsorption voltage to the functional electrodes 50 of the first adsorption tower 11a and the third adsorption tower 11c continues (no in S3-2).

[0098] Current value I flowing through the electrochemical element in the first adsorption tower *1 The threshold current I T If this is the case (Yes in S3-2), the supply of the gas mixture (e.g., exhaust gas) to the third adsorption tower 11c is stopped (S3-3). This ends the third adsorption step. Note that the threshold current I T may be the same value or may be different values.

[0099] In one embodiment of the present invention, a second release step is performed after the second adsorption step and before the third adsorption step. In the second release step, the predetermined gas (e.g., carbon dioxide) adsorbed in the second adsorption tower 11b is released from the second adsorption tower 11b. More specifically, the controller 51 closes the first collection valve 41b and opens the second collection valve 41c, and controls a power supply (not shown) to apply a release voltage to the functional electrode 50 of the second adsorption tower 11b. This allows the predetermined gas (e.g., carbon dioxide) captured in the functional electrode 50 of the second adsorption tower 11b to be released from the functional electrode 50. The predetermined gas (e.g., carbon dioxide) released from the functional electrode 50 is sent to a storage facility (not shown) in the same manner as in the first release step described above.

[0100] In one embodiment of the present invention, the first adsorption step (S1), the second adsorption step (S2), and the third adsorption step (S3) are sequentially repeated until a stop signal is input to the control unit 51 (no in S4). In this case, a third release step is performed after the third adsorption step is completed but before the repeated first adsorption step is completed. In the third release step, a predetermined gas (e.g., carbon dioxide) adsorbed in the third adsorption tower 11c is released from the third adsorption tower 11c. More specifically, the control unit 51 closes the second collection valve 41c and opens the third collection valve 41d, and controls a power supply (not shown) to apply a release voltage to the functional electrode 50 of the third adsorption tower 11c. This allows the predetermined gas (e.g., carbon dioxide) captured in the functional electrode 50 of the third adsorption tower 11c to be released from the functional electrode 50. The predetermined gas (for example, carbon dioxide) released from the functional electrode 50 is sent to a storage facility (not shown) in the same manner as in the first release step described above.

[0101] Thereafter, when a stop signal is input to the control unit 51 (yes in S4), the control unit 51 stops applying voltage to the functional electrode 50 and stops driving the blower 21e. This stops the operation of the gas adsorption system 110. Note that in the above-described embodiment of the present invention, the determination (S4) of whether a stop signal has been input to the control unit 51 is performed after the third adsorption step (S3), but the determination (S4) of whether a stop signal has been input to the control unit 51 may be made between the first adsorption step (S1) and the second adsorption step (S2), or may be made between the second adsorption step (S2) and the third adsorption step (S3). [Industrial Applicability]

[0102] Gas adsorption systems and methods of operating gas adsorption systems according to embodiments of the present invention may be suitably used for separating and recovering a selected gas from a gas mixture, and in particular for carbon dioxide capture, utilization, and storage (CCUS) cycles. [Explanation of symbols]

[0103] 11 Adsorption tower 11a 1st adsorption tower 11b Second adsorption tower 11c 3rd adsorption tower 50 Functional Electrodes 60 Counter electrode 100 Electrochemical element 110 Gas Adsorption System

Claims

1. a plurality of gas adsorption units each including an electrochemical element configured to adsorb and release a predetermined gas; The plurality of gas adsorption sections include a first adsorption unit to which the predetermined gas is supplied; a second adsorption section to which the gas that has passed through the first adsorption section is supplied, The electrochemical device comprises: a gas flow path; a functional electrode including a first active material, the functional electrode being formed to surround the gas flow channel; a counter electrode comprising a second active material; a support having partition walls defining a plurality of cells; the plurality of cells includes a first cell and a second cell; the functional electrode is formed on a surface of a partition wall that defines the first cell; The counter electrode is packed inside the second cell.

2. the predetermined gas is carbon dioxide, the first active material includes anthraquinone; the second active material includes polyvinylferrocene; The gas adsorption system of claim 1 .

3. The plurality of gas adsorption sections include further comprising a third adsorption section to which the gas that has passed through the second adsorption section is supplied; 3. The gas adsorption system according to claim 1 or 2.

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