JP7707777B2 - Chemical Reactors - Google Patents

Description

The present invention relates to a chemical reaction device.

A chemical reaction device is disclosed in which a reduction reaction electrode and an oxidation reaction electrode are placed facing each other at a distance in a container, and an electrolyte is passed between the reduction reaction electrode and the oxidation reaction electrode, thereby causing a chemical reaction of a substance (reaction substrate) contained in the electrolyte (Patent Document 1). Also disclosed is a configuration in which multiple photoelectrochemical reaction cell units are connected in series and in parallel (Patent Document 2).

In order to improve the reaction efficiency in a chemical reaction device, it is necessary to prevent the electrolyte from flowing back between the opposing electrodes for the reduction reaction and the oxidation reaction, and to make the electrolyte flow as uniform as possible. In order to make the electrolyte flow uniform in such a chemical reaction device, a configuration has been disclosed in which an exhaust port is provided for discharging gas generated by the reaction from the container, and an overflow port is provided separately from the exhaust port for discharging liquid from the container, and the overflow port is disposed at a lower position than the exhaust port in the vertical direction (Patent Document 3).

JP 2018-087074 A JP 2017-048442 A JP 2021-062339 A

However, the prior art did not provide a configuration that fully considered the effect of the number and arrangement of electrolyte outlets on the electrolyte flow. Therefore, there is a need to make the flow uniform by providing multiple outlets in appropriate positions.

In addition, as the number of electrolyte outlets increases, the number of peripheral parts such as pipes connected to each outlet also increases, increasing the manufacturing cost of the chemical reaction device, so it is preferable to keep the number of outlets as small as possible.

Furthermore, in order to increase the reaction area of the reduction reaction electrode and the oxidation reaction electrode, it is necessary to ensure a sufficient height for the chemical reaction device, but making the height greater than necessary leads to an increase in the size of the device. In order to avoid an increase in the size of the chemical reaction device, it is preferable to place the electrolyte outlet close to the upper ends of the reduction reaction electrode and the oxidation reaction electrode. However, in conventional technology, the effect of the number and arrangement of electrolyte outlets on the flow of electrolyte was not fully considered, and the extent to which the electrolyte outlet could be brought close to the upper ends of the reduction reaction electrode and the oxidation reaction electrode was not optimized.

One aspect of the present invention is a chemical reaction device that supplies a liquid between electrodes arranged in a container and reacts substances contained in the liquid, the container is provided with one or more outlets for discharging the liquid in addition to an exhaust port for discharging gas generated by the reaction, the outlets are provided at a position lower than the exhaust port in the vertical direction, the liquid level of the liquid is at a position lower than the exhaust port, a straightening plate is provided to straighten the flow of the liquid on the reaction surface of the electrode, the maximum value of the angle formed by a line connecting each point on the upper end of the reaction surface in the vertical direction to the edge of the outlet at the shortest distance from each point and a line along the vertical direction is 30° to 84°, and the height from the upper end of the reaction surface to the edge of the outlet is equal to or greater than the diameter of the outlet.

Another aspect of the present invention is a chemical reaction device that supplies a liquid between electrodes arranged in a container and reacts a substance contained in the liquid, the container is provided with one or more outlets for discharging the liquid in addition to an exhaust port for discharging gas generated by the reaction, the outlets are provided at a position lower than the exhaust port in the vertical direction, the liquid level of the liquid is at a position lower than the exhaust port, a straightening plate is provided to straighten the flow of the liquid on the reaction surface of the electrode, the maximum value of the angle between each point on the upper end of the reaction surface in the vertical direction and the edge of the outlet at the shortest distance from each point and a line along the vertical direction is 30° to 70°, and the height from the upper end of the reaction surface to the edge of the outlet is 1.6 times or more the diameter of the outlet.

Here, the electrodes are a reduction reaction electrode and an oxidation reaction electrode, and it is preferable that the reduction reaction electrode and the oxidation reaction electrode are arranged in opposing positions with a distance between them.

It is also preferable that the liquid is an electrolyte, and that the gas is generated in association with a reaction at at least one of the reduction reaction electrode and the oxidation reaction electrode, and that the substance is carbon dioxide (CO ₂ ), and that the carbon dioxide (CO ₂ ) is reduced at the reduction reaction electrode and oxygen (O ₂ ) is generated at the oxidation reaction electrode.

It is also preferable that a plurality of the electrodes for the reduction reaction and a plurality of the electrodes for the oxidation reaction are stacked alternately.

The present invention provides a chemical reaction device that ensures uniform flow of electrolyte.

1 is a perspective view showing a configuration of a chemical reaction device according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a configuration of a chemical reaction device according to an embodiment of the present invention. FIG. 1 is a diagram showing a configuration of an electrode for a reduction reaction in an embodiment of the present invention. FIG. 1 is a diagram showing a configuration of an electrode for an oxidation reaction in an embodiment of the present invention. FIG. 4 is a diagram illustrating the arrangement of exhaust ports in an embodiment of the present invention. 1A and 1B are diagrams illustrating configurations and analysis results of an example and a comparative example of the present invention. FIG. 4 is a diagram showing an analysis result of a flow velocity distribution of an electrolytic solution in Example 1 of the present invention. FIG. 13 is a diagram showing the analysis results of the average standard deviation of the flow velocity/flow rate in the examples of the present invention and the comparative examples.

As shown in the perspective view of FIG. 1 and the cross-sectional view of FIG. 2, the chemical reaction device 100 according to the embodiment of the present invention includes an oxidation reaction electrode 102, a reduction reaction electrode 104, a current plate 106, an electrolyte 108, a container 110, and an orifice plate 112.

The chemical reaction device 100 is used by being positioned so that the Z direction in the figure is the vertical direction. Note that FIG. 2 shows a cross-sectional view of the chemical reaction device 100 cut along the Y-Z plane when the electrolyte 108 is supplied.

The container 110 is a member that supports the oxidation reaction electrode 102, the reduction reaction electrode 104, and the current plate 106, and also constitutes a flow path through which the electrolyte 108 flows. The container 110 is made of a material that has the mechanical strength required to configure the chemical reaction device 100 as a cell. For example, the container 110 can be made of metal, plastic, etc.

The container 110 is provided with a supply port 110a for supplying the electrolyte 108 into the container 110. Also, a discharge port 110b for discharging the electrolyte 108 from the container 110 is provided. That is, the electrolyte 108 containing the reaction substrate is supplied into the container 110 from the supply port 110a, and the electrolyte 108 is caused to flow through the reaction region between the oxidation reaction electrode 102 and the reduction reaction electrode 104, and then the electrolyte 108 is discharged from the container 110 through the discharge port 110b.

The container 110 is also provided with an exhaust port 110c for discharging gas generated by the reaction in the chemical reaction device 100 from the container 110. The supply port 110a is preferably arranged vertically below the reaction region in the container 110 in which the oxidation reaction electrode 102 and the reduction reaction electrode 104 are arranged. The exhaust port 110c is preferably arranged vertically above the reaction region in the container 110 in which the oxidation reaction electrode 102 and the reduction reaction electrode 104 are arranged.

It is preferable that the outlet 110b for the electrolyte 108 is disposed above the upper ends of the electrodes 102 for oxidation reactions and 104 for reduction reactions in the vertical direction (Z direction) so that the electrodes 102 for oxidation reactions and 104 for reduction reactions sufficiently contribute to the reaction of the electrolyte 108 supplied into the container 110. This allows the electrolyte 108 to be discharged from the outlet 110b with the electrodes 102 for oxidation reactions and 104 for reduction reactions entirely immersed in the electrolyte 108. It is preferable that the exhaust port 110c is disposed at a position higher than the outlet 110b in the vertical direction (Z direction).

The oxidation reaction electrode 102 and the reduction reaction electrode 104 are plate-shaped members extending in the X and Z directions, respectively, and are arranged side by side facing each other along the Y direction. In this embodiment, two oxidation reaction electrodes 102 with a catalyst supported on one side, three oxidation reaction electrodes 102 with a catalyst supported on both sides, and four reduction reaction electrodes 104 with a catalyst supported on both sides are arranged so that the reaction surfaces extending in the X-Z plane direction on which the oxidation catalyst and reduction catalyst are supported face each other. That is, from the left along the Y direction in FIG. 2, an oxidation reaction electrode 102 with a catalyst supported on one side, a current plate 106 and a reduction reaction electrode 104 with a catalyst supported on both sides, a current plate 106 and an oxidation reaction electrode 102 with a catalyst supported on both sides, a current plate 106 and a reduction reaction electrode 104 with a catalyst supported on both sides, a current plate 106 and an oxidation reaction electrode 102 with a catalyst supported on both sides, an oxidation reaction electrode 102 with a catalyst supported on one side, and so on are arranged. In this way, a plurality of oxidation reaction electrodes 102, a plurality of current plates 106, and a plurality of reduction reaction electrodes 104 are stacked along the Y direction.

The reduction reaction electrode 104 is an electrode used to reduce a substance by a reduction reaction. As shown in the cross-sectional view of FIG. 3, the reduction reaction electrode 104 is formed on a substrate 114. The reduction reaction electrode 104 includes a conductive layer 10 and a reduction catalyst layer 12.

The substrate 114 is a member that structurally supports the reduction reaction electrode 104. The substrate 114 is not particularly limited in material, but may be, for example, a glass substrate. The substrate 114 may also include, for example, a metal or a semiconductor. The metal used as the substrate 114 is not particularly limited, but preferably includes titanium (Ti), silver (Ag), gold (Au), copper (Cu), zinc (Zn), indium (In), cadmium (Cd), tin (Sn), palladium (Pd), and lead (Pb). The semiconductor used as the substrate 114 is not particularly limited, but preferably includes titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), silicon (Si), strontium titanate (SrTiO ₃ ), zinc oxide (ZnO), tantalum oxide (Ta ₂ O ₅ ), or the like.

When the substrate 114 is an insulator, a conductive layer 10 is provided between the substrate 114 and the reduction catalyst layer 12. The conductive layer 10 is provided to apply a voltage to the reduction catalyst layer 12 of the reduction reaction electrode 104. The conductive layer 10 is not particularly limited, but is preferably a transparent conductive layer such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), etc. In particular, it is preferable to use fluorine-doped tin oxide (FTO) in consideration of thermal and chemical stability.

The reduction catalyst layer 12 is made of a material having a reduction catalyst function. The reduction catalyst layer 12 preferably contains a complex catalyst. For example, the reduction catalyst layer 12 is preferably a ruthenium complex. Examples of the complex catalyst include [Ru{4,4'-di(1-H-1-pyrrolypropyl carbonate)-2,2'-bipyridine}(CO)(MeCN)Cl ₂ ], [Ru{4,4'-di(1-H-1-pyrrolypropyl carbonate)-2,2'-bipyridine}(CO) ₂ Cl ₂ ], [Ru{4,4'-di(1-H-1-pyrrolypropyl carbonate)-2,2'-bipyridine}(CO) ₂ ] _n , [Ru{4,4'-di(1-H-1-pyrrolypropyl carbonate)-2,2'-bipyridine}(CO) 2 ] carbonate)-2,2'-bipyridine}(CO)(CH ₃ CN)Cl ₂ ] and the like.

The modification with the complex catalyst can be made by applying a solution in which the complex is dissolved in an acetonitrile (MeCN) solution onto the conductive layer 10. The modification with the complex catalyst can also be performed by electrolytic polymerization. The electrode of the conductive layer 10 is used as the working electrode, a glass substrate coated with fluorine-containing tin oxide (FTO) is used as the counter electrode, and an Ag/Ag ⁺ electrode is used as the reference electrode. In an electrolyte solution containing the complex catalyst, a cathode current is passed so that the potential is negative relative to the Ag/Ag ⁺ electrode, and then an anode current is passed so that the potential is positive relative to the Ag/Ag ⁺ electrode, thereby modifying the surface of the conductive layer 10 with the complex catalyst. Acetonitrile (MeCN) can be used as the electrolyte solution, and tetrabutylammonium perchlorate (TBAP) can be used as the electrolyte.

The reduction catalyst layer 12 can also be configured to include a conductor containing a carbon material (C). It is preferable that the size of the single unit of the carbon material structure is 1 nm or more and 1 μm or less. The carbon material preferably includes at least one of carbon nanotubes, graphene, and graphite, for example. In the case of graphene and graphite, it is preferable that the size is 1 nm or more and 1 μm or less. In the case of carbon nanotubes, it is preferable that the diameter is 1 nm or more and 40 nm or less. The conductor can be formed by spraying and heating a carbon material mixed with a liquid such as ethanol. Instead of spraying, it may be applied by spin coating. It is also possible to apply the solution by directly dripping it and drying it without using spin coating.

The reduction catalyst can be supported in the reduction catalyst layer 12 by, for example, applying a solution (e.g., Ru complex polymer solution) in which a metal complex (catalyst) is dissolved in an acetonitrile (MeCN) solution onto a carbon-based material such as carbon paper or carbon cloth, and drying the solution. The reduction catalyst can also be supported by electrolytic polymerization. For example, a carbon-based material electrode is used as the working electrode, a glass substrate coated with fluorine-containing tin oxide (FTO) is used as the counter electrode, and an Ag/Ag ⁺ electrode is used as the reference electrode. In an electrolyte solution containing the reduction catalyst, a cathode current is passed so that the potential is negative relative to the Ag/Ag ⁺ electrode, and then an anode current is passed so that the potential is positive relative to the Ag/Ag ⁺ electrode, thereby supporting the reduction catalyst on the carbon-based material. For example, acetonitrile (MeCN) can be used as the electrolyte solution, and tetrabutylammonium perchlorate (TBAP) can be used as the electrolyte.

Note that, although FIG. 3 shows an example in which the conductive layer 10 and the reduction catalyst layer 12 are formed on only one side of the substrate 114, the conductive layer 10 and the reduction catalyst layer 12 may be formed on both sides of the substrate 114.

The oxidation reaction electrode 102 is an electrode used to oxidize a substance by an oxidation reaction. As shown in the cross-sectional view of FIG. 4, the oxidation reaction electrode 102 is formed on a substrate 116. The oxidation reaction electrode 102 includes a conductive layer 14 and an oxidation catalyst layer 16.

The substrate 116 is a member that structurally supports the oxidation reaction electrode 102. The substrate 116 can be made of the same material as the substrate 114 used in the reduction reaction electrode 104.

The conductive layer 14 is provided to effectively collect electricity at the oxidation reaction electrode 102. The conductive layer 14 is not particularly limited, but is preferably made of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), or the like. In particular, it is preferable to use fluorine-doped tin oxide (FTO) in consideration of thermal and chemical stability.

The oxidation catalyst layer 16 is composed of a material having an oxidation catalyst function. The material having an oxidation catalyst function can be, for example, a material containing iridium oxide (IrOx). The iridium oxide can be supported on the surface of the conductive layer 14 as a nanocolloid solution (T.Arai et.al, Energy Environ. Sci 8, 1998 (2015)).

For example, a nanocolloid of iridium oxide (IrOx) is synthesized. First, a yellow solution adjusted to pH 13 by adding 10 wt% sodium hydroxide (NaOH) aqueous solution to 50 ml of 2 mM potassium chloride iridate (IV) (K ₂ IrCl ₆ ) aqueous solution is heated at 90° C. for 20 minutes using a hot stirrer. The blue solution obtained is cooled in ice water for 1 hour. Then, 3M nitric acid (HNO ₃ ) is dropped into the cooled solution (20 ml) to adjust the pH to 1, and the solution is stirred for 80 minutes to obtain a nanocolloid aqueous solution of iridium oxide (IrOx). Furthermore, a 1.5 wt% NaOH aqueous solution (1-2 ml) is dropped into this solution to adjust the pH to 12. The nanocolloid aqueous solution of iridium oxide (IrOx) obtained in this way is applied to the conductive layer 14 at pH 12, and is dried by keeping it in a drying oven at 60° C. for 40 minutes. After drying, the precipitated salt is washed with ultrapure water to form the oxidation reaction electrode 102. Note that the application and drying of the nano-colloidal aqueous solution of iridium oxide (IrOx) may be repeated multiple times.

Note that, although FIG. 4 shows an example in which the conductive layer 14 and the oxidation catalyst layer 16 are formed on only one side of the substrate 116, the conductive layer 14 and the oxidation catalyst layer 16 may be formed on both sides of the substrate 116.

The straightening plate 106 is a member that divides the space between the oxidation reaction electrode 102 and the reduction reaction electrode 104 to straighten the flow of the electrolyte 108. The straightening plate 106 is a plate-shaped member that extends along the direction (Z direction) from the electrolyte supply port 110a to the discharge port 110b. A plurality of straightening plates 106 are arranged along the X direction so that the plate surface is along the Y direction. This restricts the flow of the electrolyte 108 along the direction (X direction) that intersects with the Y direction, and can straighten the flow of the electrolyte 108 in the direction (Z direction) from the supply port 110a to the discharge port 110b.

The chemical reaction device 100 functions by introducing an electrolyte 108 between the reduction reaction electrode 104 and the oxidation reaction electrode 102. That is, the reduction reaction electrode 104 and the oxidation reaction electrode 102 are stored in a container 110, and the electrolyte 108 in which the reaction substrate is dissolved is supplied to the surfaces of the reduction reaction electrode 104 and the oxidation reaction electrode 102.

The reaction substrate may be a carbon compound, for example, carbon dioxide (CO ₂ ). The electrolyte 108 is preferably an aqueous phosphate buffer solution or an aqueous borate buffer solution. In a specific configuration example, a tank of carbon dioxide (CO ₂ )-saturated phosphate buffer solution is provided, and the electrolyte 108 is supplied to the surfaces of the reduction reaction electrode 104 and the oxidation reaction electrode 102 from the supply port 110a by a pump. Formic acid (HCOOH) generated by the reduction reaction is collected together with the electrolyte 108 from the exhaust port 110b into an external fuel tank, and oxygen (O ₂ ) generated by the oxidation reaction is exhausted from the exhaust port 110c.

A bias power supply may be provided between the oxidation reaction electrode 102 and the reduction reaction electrode 104 to provide a potential difference between the oxidation reaction electrode 102 and the reduction reaction electrode 104. The bias power supply may be, for example, a solar cell. When a solar cell is used as the bias power supply, the solar cell may be disposed adjacent to the container 110. For example, a solar cell may be disposed on the back surface of the container 110, and the positive electrode of the solar cell may be connected to the oxidation reaction electrode 102 and the negative electrode may be connected to the reduction reaction electrode 104.

When synthesizing formic acid (HCOOH) from carbon dioxide (CO ₂ ), water (H ₂ O) is oxidized to supply electrons and protons to carbon dioxide (CO ₂ ). At around pH 7, the oxidation potential of water (H ₂ O) is 0.82 V and the reduction potential is -0.41 V (both NHE). In addition, the reduction potentials of carbon dioxide (CO ₂ ) to carbon monoxide (CO), formic acid (HCOOH), and methyl alcohol (CH ₃ OH) are -0.53 V, -0.61 V, and -0.38 V, respectively. Therefore, the potential difference between the oxidation potential and the reduction potential is 1.20 to 1.43 V.

The chemical reaction device 100 is further provided with an orifice plate 112. The orifice plate 112 is a plate-shaped member provided with orifice holes, which are through holes that limit the flow of the electrolyte 108 introduced into the container 110 from the supply port 110a. The orifice plate 112 is disposed on a flow path in the container 110 that extends from the supply port 110a to the area where the oxidation reaction electrode 102 and the reduction reaction electrode 104 are provided. The orifice plate 112 is made of a material that has the necessary mechanical strength. For example, the orifice plate 112 can be made of metal, plastic, etc.

In the chemical reaction device 100, the space formed by the oxidation reaction electrode 102, the reduction reaction electrode 104, and the rectifying plate 106 becomes a flow path for the electrolyte 108 to flow. The orifice plate 112 is disposed between the supply port 110a and these flow paths. The orifice plate 112 is provided with orifice holes that connect the flow paths formed by the oxidation reaction electrode 102, the reduction reaction electrode 104, and the rectifying plate 106 to the supply port 110a. The diameter of the orifice holes may be, for example, 0.5 mm, and the interval may be, for example, 10 mm.

Therefore, the electrolyte 108 supplied from the supply port 110a is stored in the space from the supply port 110a to the orifice plate 112, and then is sprayed into the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 through the orifice hole of the orifice plate 112. When the electrolyte 108 flows into the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104, the flow path is filled with the electrolyte 108. Furthermore, the electrolyte 108 is discharged from the container 110 through the discharge port 110b.

In this embodiment, a separator may further be provided. The separator is a member that separates the oxidation reaction electrode 102 and the reduction reaction electrode 104. The separator may be made of a proton conductive film that is a porous body that can transmit protons in the electrolyte 108. The separator may be made of, for example, a rayon nonwoven fabric, a vinylon nonwoven fabric, a hydrophilized ultra-high molecular weight polyethylene porous film, a hydrophilized polypropylene mesh, or a hydrophilized ultra-high molecular weight polyethylene porous film. The separator may also be integrated with the current plate 106.

<Example>
An example of the chemical reaction device 100 according to the embodiment of the present invention will be described below. In the example, an oxidation reaction electrode 102 and a reduction reaction electrode 104 are provided, and nine rectifying plates 106 are arranged between each of the oxidation reaction electrodes 102 and the reduction reaction electrodes 104. In addition, in the chemical reaction device 100, an orifice plate 112 is provided between the supply port 110a of the electrolytic solution 108 and the oxidation reaction electrode 102 and the reduction reaction electrode 104.

The size of the oxidation reaction electrode 102 and the reduction reaction electrode 104 was 1 m square. The inside dimension W of the container 110 in the width direction (X direction) was 1078 mm, and the inside dimension T2 in the thickness direction (Y direction) was 166 mm, making it possible to install up to 14 pairs of oxidation reaction electrodes 102 and reduction reaction electrodes 104.

The electrode 102 for the oxidation reaction was a Ti plate coated with IrOx colloid and then dried. The electrode 104 for the reduction reaction was a carbon paper/multi-walled carbon nanotube carrying a Ru complex polymer, which was then attached to a titanium substrate using a carbon-based adhesive.

The oxidation reaction electrode 102 and the reduction reaction electrode 104 were placed in a container 110 with their catalyst-supported reaction surfaces facing each other. The electrolyte 108 was a 0.4 M phosphate buffer solution in which _CO2 was saturated and dissolved by bubbling in a separate container. A crystalline silicon solar cell was connected as a direct current power source to the oxidation reaction electrode 102 and the reduction reaction electrode 104, and a voltage was applied by irradiating light thereto.

Figure 5 is a diagram for explaining the arrangement of the exhaust outlet 110b in the examples. In the examples and comparative examples, the exhaust outlet 110b is circular.

Figure 6 shows the configuration and test results of the chemical reaction device 100 in Examples 1 to 13 and Comparative Example 1. Here, the angle θ between the line Q connecting the point P farthest from the exhaust port 110b at the upper end of the reaction surface of the oxidation reaction electrode 102 and the reduction reaction electrode 104 and the edge of the exhaust port 110b and the vertical direction (Z direction) (the maximum angle θ between the line connecting each point at the upper end of the reaction surface of the oxidation reaction electrode 102 and the reduction reaction electrode 104 and the edge of the exhaust port 110b at the shortest distance therefrom and the vertical direction (Z direction)), the diameter D of the exhaust port 110b, and the distance L from the upper end of the reaction surface of the oxidation reaction electrode 102 and the reduction reaction electrode 104 to the edge of the exhaust port 110b. In addition, the exhaust ports 110b were arranged evenly with respect to the width of the reaction surface of the oxidation reaction electrode 102 and the reduction reaction electrode 104.

For example, in Example 1, eight pairs of the oxidation reaction electrodes 102 and the reduction reaction electrodes 104 were arranged in the container 110. The total thickness (thickness T1 in FIG. 2) of the oxidation reaction electrodes 102 and the reduction reaction electrodes 104 was 94 mm. The number of outlets 110b was 10, the angle θ was 29°, and the ratio L/D of the distance L to the diameter D was 9.29.

Figure 7 shows the results of a fluid analysis of the flow velocity distribution of the electrolyte 108 for Example 1. Note that the chemical reaction device 100 shown in Figure 1 is 1 m square, and has two outlets 110b, but because it has a symmetrical structure, in Examples 1 to 13 and Comparative Example 1, a configuration was used in which one outlet 110b is provided in the upper left corner of the 50 cm square, which is divided into four, and the analysis was performed under the assumption that the flow velocity distribution is uniform at the bottom end of the 50 cm square size.

In the flow path between the stacked oxidation reaction electrode 102 and reduction reaction electrode 104, the standard deviation of the flow rate at a position 10 mm below the upper end of the reaction surface (the position of the dashed line in FIG. 7) was 2.30×10 ⁻³ L/min to 2.91×10 ⁻³ L/min. In addition, the value obtained by dividing the average of the standard deviation of the flow rate of the electrolyte 108 by the flow rate was 7.14×10 ⁻⁵ . That is, in Example 1, the flow rate of the electrolyte 108 was approximately uniform within the container 110. In addition, the phenomenon of the electrolyte 108 flowing back into the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 closest to the outlet 110b was not observed.

8, the value obtained by dividing the average standard deviation of the flow rate of the electrolyte 108 by the flow rate was on the order of ^10-5 in Examples 2 to 13. That is, the flow rate of the electrolyte 108 was approximately uniform in the container 110 in Examples 2 to 13. In addition, there was no phenomenon observed in which the electrolyte 108 flowed back into the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104, which were closest to the outlet 110b.

From the analysis results of Examples 1 to 13, if the angle θ is 30° or more and 70° or less and the distance L is 1.6 times or more the diameter D, the value obtained by dividing the average standard deviation of the flow rate of the electrolyte 108 in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 by the flow rate can be kept at 7.73×10 ⁻⁵ or less. Furthermore, in this case, no backflow of the electrolyte 108 occurs in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104.

Furthermore, from the analysis results of Examples 1 to 8, if the angle θ is 30° or more and 84° or less and the distance L is 1.0 times or more the diameter D, the value obtained by dividing the average standard deviation of the flow rate of the electrolyte 108 in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 by the flow rate can be kept at 1.03×10 ⁻⁴ or less. In this case, no backflow of the electrolyte 108 occurs in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104.

In contrast, when the angle θ was 88° and the distance L was 0.03 times the diameter D as in Comparative Example 1, the value obtained by dividing the average of the standard deviations of the flow rate of the electrolyte 108 in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 by the flow rate was 2.72×10 ⁻⁴ , which was greater than or equal to 1.03×10 ⁻⁴ . That is, in Comparative Example 1, the flow rate of the electrolyte 108 in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 was non-uniform compared to Examples 1 to 13. Furthermore, in this case, a backflow of the electrolyte 108 was observed in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104.

As mentioned above, the analysis was performed on a 50 cm square size chemical reaction device 100 with a size of 1 m square, so in the case of a size of 1 m square, the analysis results shown in FIG. 7 can be arranged side by side and two outlets 110b can be used to obtain similar results. Furthermore, in the case of a size of 1.5 m square, the analysis results shown in FIG. 7 can be arranged further to provide three outlets 110b. In other words, if the angle θ and the distance L satisfy a predetermined condition, the flow rate of the fluid can be made uniform, so the number of outlets 110b can be selected according to the allowable range of the distance L defined by the width of the container 110 or the oxidation reaction electrode 102 and the reduction reaction electrode 104 and the size of the chemical reaction device 100. For example, if the width is narrow and the allowable value of the distance L is large, one outlet 110b can be used, and if the width is wide and the allowable range of the distance L is small, the number of outlets 110b can be increased.

As described above, according to this embodiment, the height of the container 110 in the chemical reaction device 100 can be reduced while the flow rate of the fluid in the flow path between the oxidation reaction electrode 102 and the reduction reaction electrode 104 can be made uniform.

REFERENCE SIGNS LIST 10 Conductive layer, 12 Reduction catalyst layer, 14 Conductive layer, 16 Oxidation catalyst layer, 100 Chemical reaction device, 102 Oxidation reaction electrode, 104 Reduction reaction electrode, 106 Rectifier plate, 108 Electrolyte, 110 Container, 110a Supply port, 110b Discharge port, 110c Exhaust port, 112 Orifice plate, 114 Substrate, 116 Substrate.

Claims (6)

A chemical reaction device that supplies a liquid between electrodes disposed in a container and reacts a substance contained in the liquid,
the container is provided with one or more circular exhaust ports for discharging the liquid in addition to an exhaust port for discharging gas generated by the reaction;
the exhaust port is provided at a position lower than the exhaust port in a vertical direction, and a liquid level of the liquid is at a position lower than the exhaust port,
a flow straightening plate for straightening the flow of the liquid on the reaction surface of the electrode;
the maximum angle formed by a line connecting each point on the upper end of the reaction surface in the vertical direction to the edge of the outlet that is closest to each point on the upper end of the reaction surface and a line along the vertical direction is 30° or more and 84° or less;
A chemical reaction device characterized in that the height from the upper end of said reaction surface to the edge of said outlet is equal to or greater than the diameter of said outlet. A chemical reaction device that supplies a liquid between electrodes disposed in a container and reacts a substance contained in the liquid,
the container is provided with one or more circular exhaust ports for discharging the liquid in addition to an exhaust port for discharging gas generated by the reaction;
the exhaust port is provided at a position lower than the exhaust port in a vertical direction, and a liquid level of the liquid is at a position lower than the exhaust port,
a flow straightening plate for straightening the flow of the liquid on the reaction surface of the electrode;
the maximum angle formed by a line connecting each point on the upper end of the reaction surface in the vertical direction to the edge of the outlet that is closest to each point on the upper end of the reaction surface and a line along the vertical direction is 30° or more and 70° or less;
A chemical reaction device characterized in that the height from the upper end of said reaction surface to the edge of said outlet is 1.6 times or more the diameter of said outlet. The chemical reaction device according to claim 1 or 2,
The electrodes are a reduction reaction electrode and an oxidation reaction electrode,
a reduction reaction electrode and an oxidation reaction electrode disposed at opposite positions and spaced apart from each other; The chemical reaction device according to claim 3,
the liquid is an electrolyte;
A chemical reaction device, characterized in that the gas is generated in association with a reaction in at least one of the reduction reaction electrode and the oxidation reaction electrode. The chemical reaction device according to claim 4,
the substance is carbon dioxide (CO ₂ );
A chemical reaction device, characterized in that carbon dioxide (CO ₂ ) is reduced at the reduction reaction electrode, and oxygen (O ₂ ) is generated at the oxidation reaction electrode. The chemical reaction device according to any one of claims 3 to 5,
A chemical reaction device, characterized in that a plurality of the electrodes for reduction reaction and a plurality of the electrodes for oxidation reaction are alternately stacked.