Bulk copper catalyst and electrochemical reaction device

Abstract

The present invention provides a bulk copper catalyst having a roughly plate-like shape and including pore sections (11) that communicate in the thickness direction and skeleton sections (12) that are made of copper or a copper alloy, said catalyst being characterized in that: the number of the pore sections in a plane orthogonal to the thickness direction exceeds 500 in a range of 1 inch × 1 inch; the width of each skeleton section is 1 μm or more; the thickness t (mm) and the area S (mm2) of the plane orthogonal to the thickness direction have the relationship t2 / S × 103 < 5; and the volumetric ratio of the pore sections is in a range of 5% to 80%.

Description

Copper bulk catalyst and electrochemical reactor

[0001] This invention is CO ２ This invention relates to a copper alloy catalyst and electrochemical reactor used in the production of organic compounds such as ethylene, ethanol, and methane by the electrochemical reduction of carbon dioxide. This application claims priority based on Japanese Patent Application No. 2025-013739, filed in Japan on January 30, 2025, the contents of which are incorporated herein by reference.

[0002] In the current climate of accelerating global warming, CO2 in the atmosphere is a particular concern. ２ Reducing GHG emissions, such as natural gases, is a global challenge. In recent years, the development of CCU (Carbon Dioxide Capture and Utilization) technology, which uses atmospheric carbon dioxide as a raw material for useful chemical products, has been accelerating. Carbon dioxide is a very stable compound with a carbon oxidation state of +4, the highest oxidation state, and a standard Gibbs free energy of formation of approximately 400 kJ / mol. Converting carbon dioxide into useful chemical products requires reducing the carbon using a large amount of energy. There is a need to develop technologies that can reduce carbon dioxide energy efficiently.

[0003] In recent years, co-electrolysis methods using electrolytic cells composed of polymeric ion-exchange membranes have attracted attention (see, for example, Patent Documents 1 and 2). Co-electrolysis is a technique in which electrolysis by oxidation reaction is performed at the anode and electrolysis by reduction reaction is performed at the cathode simultaneously in an electrochemical cell. For example, water at the anode and KHCO3 at the cathode. ３ Aqueous solutions and CO ２ By using gas as a raw material, H ２ Using protons produced from the electrolysis of O, CO ２ CO can be reduced. Here, when Cu is used as a catalyst, CO can be reduced with high Faraday efficiency. ２ Organic compounds such as ethanol, ethylene, and methane can be obtained from this.

[0004] In the case of copper catalysts, since the production efficiency of organic compounds is low in bulk materials, they have conventionally been provided as powders or sputtered thin films. Further, in Non-Patent Document 1, it has been reported that in a copper catalyst composed of a sputtered thin film, by forming a polymer film on the surface to enhance water repellency, organic compounds can be generated from CO ２ with a higher Faraday efficiency.

[0005] Japanese Patent Application Laid-Open No. 2022-049861 (A), Japanese Patent Application Laid-Open No. 2022-040803 (A)

[0006] Yan Lin et. al., Nature Communications, (2023) 14:3575

[0007] By the way, although conventional sputtered thin films and powdered copper catalysts can achieve high catalytic performance, they are not preferable from an industrial perspective. Further, it is difficult to uniformly mix additive elements, and it has been difficult to control catalytic characteristics. Therefore, a bulk copper catalyst with low production cost and easy handling is preferable, but the bulk copper catalyst has poor reactivity and low production efficiency of organic compounds.

[0008] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a copper bulk catalyst capable of easily handling and generating organic compounds from CO ２ with high Faraday efficiency, and an electrochemical reaction device.

[0009] In order to solve such problems and achieve the above object, as a result of intensive studies by the present inventors, the following findings were obtained. In order to improve the production efficiency of organic compounds such as ethanol, ethylene, and methane by decomposing CO ２ it has been clarified that it is important to control the macroscopic structure of copper and copper alloy bulk catalysts.

[0010] The copper bulk catalyst of embodiment 1 of the present invention is generally plate-shaped and has voids communicating in the thickness direction and a skeleton made of copper or a copper alloy, the number of voids in a plane perpendicular to the thickness direction exceeds 500 in a 1 inch x 1 inch area, the width of the skeleton is 1 μm or more, and the thickness t (mm) and the area S (mm) of the plane perpendicular to the thickness direction ２ ) but, t ２ / S x 10 ３ It has a relationship of <5 and is characterized in that the volume ratio of the void portion is within the range of 5% to 80%.

[0011] According to the copper bulk catalyst of embodiment 1 of the present invention, it is generally plate-shaped and has voids communicating in the thickness direction and a skeleton made of copper or a copper alloy, and the number of voids in a plane perpendicular to the thickness direction exceeds 500 in a 1 inch x 1 inch area, so CO2 from the raw material passes through the voids of the copper bulk catalyst ２ The gas and the skeletal part made of copper or copper alloy are in sufficient contact, CO ２ This technology allows for efficient reduction of gases and improves the efficiency of producing organic compounds such as ethanol, ethylene, and methane.

[0012] Furthermore, the width of the skeletal part is 1 μm or more, and the thickness t (mm) and the area S (mm²) of the plane perpendicular to the thickness direction are... ２ ) but, t ２ / S x 10 ３ <Since it has a relationship with 5, manufacturing costs can be kept low and it is easy to handle. Furthermore, since the volume ratio of the void is within the range of 5% to 80%, raw material CO can be placed in the void. ２ This design allows for good gas passage while ensuring strength and ease of handling.

[0013] The copper bulk catalyst of embodiment 2 of the present invention is obtained by the EBSD method in the copper bulk catalyst of embodiment 1 of the present invention, with a thickness of 1400 μm. ２The above measurement area is measured at a measurement interval of 0.08 μm steps, and excluding measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less, those containing two or more measurement points are considered crystal grains, and when an orientation difference of 5° or more is defined as a grain boundary, the average value of the LOS (Local Orientation Spread) is 0.3° or more.

[0014] According to the copper bulk catalyst of embodiment 2 of the present invention, the average value of the LOS defined above is high at 0.3° or more, which means that local strain exists in the copper or copper alloy of the framework, and the parts with high strain energy become reaction sites, so the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0015] The copper bulk catalyst of embodiment 3 of the present invention is characterized in that, in the copper bulk catalyst of embodiment 1 or embodiment 2 of the present invention, the average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane, as measured by X-ray diffraction using a copper tube, is 0.10° or more.

[0016] According to the copper bulk catalyst of embodiment 3 of the present invention, the average of the full width at half maximum of the {111} crystal plane and the {200} crystal plane is 0.10° or more, which means that defects are present in the copper or copper alloy of the framework, and these defects have high energy and become reaction sites, so the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0017] The copper bulk catalyst of embodiment 4 of the present invention is characterized in that, in any one of the copper bulk catalysts of embodiment 1 to 3 of the present invention, the peak position of the {111} crystal plane measured by X-ray diffraction using a copper tube is 43.2° or less.

[0018] According to the copper bulk catalyst of embodiment 4 of the present invention, the peak position of the {111} crystal plane is 43.2° or less, and in the copper alloy of the framework, the added elements are solid-dissolved in the copper matrix, causing the crystal to be distorted. The introduction of strain into the crystal increases the energy state, and the raw material CO ２This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0019] The copper bulk catalyst of embodiment 5 of the present invention is characterized in that, in any one of the copper bulk catalysts of embodiments 1 to 4 of the present invention, the framework is made of a copper alloy containing one or more elements selected from Zn, Sn, and P.

[0020] According to the copper bulk catalyst of embodiment 5 of the present invention, the framework is composed of a copper alloy containing one or more elements selected from Zn, Sn, and P. As these alloying elements solid-solve in the copper matrix, the lattice of the copper crystal is strained and becomes high-energy, thus reducing the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0021] The copper bulk catalyst of embodiment 6 of the present invention is characterized in that, in any one of the copper bulk catalysts of embodiments 1 to 5 of the present invention, the S5v of the surface layer of the skeleton is 0.4 μm or more.

[0022] According to the copper bulk catalyst of embodiment 6 of the present invention, since the S5v of the surface layer of the skeleton is 0.4 μm or more, a fine and deep shape is formed on the surface layer, and the raw material CO ２ There is a space where the gas diffuses, and CO ２ An increase in gas reaction sites promotes the production of organic compounds such as methane, ethylene, and ethanol.

[0023] The copper bulk catalyst of embodiment 7 of the present invention is characterized in that, in any one of embodiments 1 to 6 of the present invention, the ratio S / A of the surface area S to the measured surface area A of the skeletal portion is 1.20 or more.

[0024] According to the copper bulk catalyst of embodiment 7 of the present invention, the ratio of the surface area S to the measured surface area A of the skeletal portion, S / A, is set to 1.20 or more, resulting in a larger surface area and an increase in reaction sites. Furthermore, fine structures are formed on the surface, which promotes the production of organic compounds such as methane, ethylene, and ethanol.

[0025] The copper bulk catalyst of embodiment 8 of the present invention is characterized in that, in any one of embodiments 1 to 7 of the present invention, the copper bulk catalyst has a surface treatment layer on the surface of the skeletal portion.

[0026] According to the copper bulk catalyst of embodiment 8 of the present invention, since a surface treatment layer is formed on the surface of the skeleton, the S5v value and S / A value of the surface of the skeleton become larger, ensuring fluid (gas and liquid) flow paths and increasing the number of reaction sites, thereby promoting the production of organic compounds such as methane, ethylene, and ethanol.

[0027] The copper bulk catalyst of embodiment 9 of the present invention is characterized in that, in any one of the copper bulk catalysts of embodiments 1 to 8 of the present invention, the sum of the Faraday efficiencies for the production of ethylene, methane, and ethanol is 1.5% or more.

[0028] According to the copper bulk catalyst of embodiment 9 of the present invention, the combined Faraday efficiency of ethylene, methane, and ethanol production is 1.5% or more. Therefore, it has high production efficiency for high value-added ethanol, ethylene, and methane, and is expected to be applied as a catalyst for converting carbon dioxide into useful chemical products.

[0029] The electrochemical reaction apparatus of embodiment 10 of the present invention is characterized by using one of the copper bulk catalysts of embodiments 1 to 9 of the present invention.

[0030] According to the electrochemical reaction apparatus of embodiment 10 of the present invention, since one of the copper bulk catalysts from embodiments 1 to 9 of the present invention is used, CO ２ This technology allows for efficient reduction of gases and improves the efficiency of producing organic compounds such as ethanol, ethylene, and methane.

[0031] According to the present invention, CO2 is easy to handle and produced with high Faraday efficiency. ２ We can provide a copper bulk catalyst capable of producing organic compounds from it, and an electrochemical reaction apparatus.

[0032] This is an explanatory diagram showing an example of a copper bulk catalyst according to an embodiment of the present invention. This is an explanatory diagram showing an example of a copper bulk catalyst according to an embodiment of the present invention. This is a flow chart showing an example of a method for producing the copper bulk catalyst in this embodiment. This is an explanatory diagram showing an example of an electrochemical reaction apparatus using the copper bulk catalyst according to an embodiment of the present invention.

[0033] The copper bulk catalyst and electrochemical reactor, which are embodiments of the present invention, will be described below with reference to the attached drawings.

[0034] The copper bulk catalyst 10 in this embodiment is, for example, CO ２ This device is used in electrochemical reactors that electrically reduce gases to produce organic compounds such as methane, ethylene, and ethanol.

[0035] In this embodiment, the copper bulk catalyst 10 is generally flat and has void portions 11 that communicate in the thickness direction and a skeleton portion 12 made of copper or a copper alloy. In this embodiment, as shown in Figures 1A and 1B, the bulk material is generally flat. Figure 1A is a mesh material made by processing copper wire, with the copper wire forming the skeleton portion 12, and the void portions 11 being formed by the skeleton portion 12 (copper wire). Figure 1B is a perforated metal with multiple holes formed in a copper plate, with the holes forming the void portions 11, and the copper plate portion remaining between the holes forming the skeleton portion 12.

[0036] Furthermore, in the copper bulk catalyst 10 of this embodiment, the number of voids 11 in a plane perpendicular to the thickness direction exceeds 500 in a 1-inch x 1-inch area. In other words, when viewed from a direction corresponding to the plane of the roughly flat copper bulk catalyst 10, the voids 11 are arranged at a high density.

[0037] Furthermore, in this embodiment, the width of the skeletal portion 12 is set to 1 μm or more when viewed from a direction opposite to the plane. For example, in Figure 1A, the outer diameter of the copper wire constituting the skeletal portion 12 is set to 1 μm or more. Also, in Figure 1B, the width of the copper plate portion remaining between the holes constituting the skeletal portion 12 is set to 1 μm or more.

[0038] Furthermore, in this embodiment, the thickness t (mm) and the area S (mm²) of the plane perpendicular to the thickness direction are defined. ２ ) but, t ２ / S x 10 ３ <It has a relationship with 5. In addition, in this embodiment, the volume ratio of the void portion 11 is set to be within the range of 5% to 80%.

[0039] In this embodiment, the copper bulk catalyst 10 is processed by the EBSD method to obtain a 1400 μm ２ When the above measurement area is measured at a measurement interval of 0.08 μm steps, and measurement points with a CI value of 0.1 or less, as analyzed by the data analysis software OIM, are excluded, and those containing two or more measurement points are considered as crystal grains, and grain boundaries are defined as orientation differences of 5° or more, it is preferable that the average value of the LOS (Local Orientation Spread) is 0.3° or more.

[0040] Furthermore, in the copper bulk catalyst 10 of this embodiment, it is preferable that the average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane, as measured by X-ray diffraction using a copper tube, is 0.10° or more. Moreover, in the copper bulk catalyst 10 of this embodiment, it is preferable that the peak position of the {111} crystal plane, as measured by X-ray diffraction using a copper tube, is 43.2° or less.

[0041] Furthermore, in the copper bulk catalyst 10 of this embodiment, it is preferable that the framework 12 is made of a copper alloy containing one or more elements selected from Zn, Sn, and P. Moreover, in the copper bulk catalyst 10 of this embodiment, it is preferable that the framework 12 is made of a copper alloy containing a total of 0.1 mass% or more of one or more elements X selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, and Ge.

[0042] Furthermore, in the copper bulk catalyst 10 of this embodiment, it is preferable that the S5v of the surface layer of the skeleton portion 12 is 0.4 μm or more. Moreover, in the copper bulk catalyst 10 of this embodiment, it is preferable that the ratio S / A of the surface area S to the measured area A of the surface layer of the skeleton portion 12 is 1.20 or more. Furthermore, in the copper bulk catalyst 10 of this embodiment, it is preferable that the surface of the skeleton portion 12 has a surface treatment layer.

[0043] Furthermore, in the copper bulk catalyst 10 of this embodiment, it is preferable that the sum of the Faraday efficiencies for the production of ethylene, methane, and ethanol is 1.5% or more.

[0044] The following explains why the various structures, the crystal structure of the framework 12, the composition of the framework 12, the surface properties of the framework 12, and the Faraday efficiency of organic compound formation in the copper bulk catalyst 10 of this embodiment are defined as described above.

[0045] (Number of voids 11 in a plane perpendicular to the thickness direction) In a copper bulk catalyst 10 that is roughly plate-shaped, if the number of voids 11 in a plane perpendicular to the thickness direction is 500 or less in a 1 inch x 1 inch area, the raw material CO ２ There is a risk that the gas cannot be efficiently reduced, and the efficiency of organic compound production cannot be improved. For this reason, in the copper bulk catalyst 10 of this embodiment, the number of voids 11 in a plane perpendicular to the thickness direction is configured to exceed 500 in a 1-inch x 1-inch area. In this embodiment, it is preferable that the number of voids 11 in a 1-inch x 1-inch area in a plane perpendicular to the thickness direction be 600 or more, and more preferably 700 or more. On the other hand, there are no particular restrictions on the number of voids 11 in a 1-inch x 1-inch area in a plane perpendicular to the thickness direction, and from the viewpoint of manufacturing cost, it is preferable that it be 500,000 or less, and more preferably 400,000 or less.

[0046] (Width of the skeleton portion 12) In the copper bulk catalyst 10 of this embodiment, if the width of the skeleton portion 12 made of copper or a copper alloy is less than 1 μm, the manufacturing cost may increase. Also, the contact resistance may increase during electrolysis, and the energy efficiency may decrease. For these reasons, in the copper bulk catalyst 10 of this embodiment, the width of the skeleton portion 12 is set to 1 μm or more. In this embodiment, the lower limit of the width of the skeleton portion 12 is preferably 5 μm or more, and more preferably 10 μm or more. On the other hand, the upper limit of the width of the skeleton portion 12 is preferably 3000 μm or less, and more preferably 2000 μm or less.

[0047] (The area S (mm²) of the plane perpendicular to the thickness direction and the thickness t (mm²) ２ (Relationship with) In the copper bulk catalyst 10 of this embodiment, the thickness t (mm) and the area S (mm²) of the plane perpendicular to the thickness direction ２ ) but, t ２ / S x 10 ３ <5 relationship ensures flatness, preventing the volume from increasing when constructing an electrolytic cell and thus suppressing an increase in manufacturing costs. In this embodiment, the above-mentioned t ２ / S x 10 ３ It is preferable that t be 4 or less, and more preferably 3 or less. On the other hand, t ２ / S x 10 ３ There is no particular restriction on the lower limit, but 10 －１０ It is preferable that the above is true, －９ It is more preferable that the above conditions are met.

[0048] (Volume fraction of void portion 11) In the copper bulk catalyst 10 of this embodiment, if the volume fraction of the void portion 11 is less than 5%, sufficient flow paths for gas and liquid cannot be secured, making it difficult for gas-liquid reactions to occur. On the other hand, if the volume fraction of the void portion 11 exceeds 80%, the number of sites where catalytic reactions occur decreases, which may reduce the efficiency of organic compound production. Also, if the volume fraction of the void portion exceeds 80%, the load on the ion exchange membrane 34 shown in Figure 3 becomes large, making the ion exchange membrane more prone to rupture. For these reasons, in this embodiment, the volume fraction of the void portion 11 is set within the range of 5% to 80%. In this embodiment, the lower limit of the volume fraction of the void portion 11 is preferably 8% or more, and more preferably 10% or more. On the other hand, the upper limit of the volume fraction of the void portion 11 is preferably 79% or less, and more preferably 78% or less.

[0049] (Average LOS) In the skeletal part 12, the LOS (Local Orientation Spread) value measured by EBSD is calculated from the angular difference between each point in the set kernel and all other points in the kernel. For example, since the shape of a pixel is a regular hexagon, if the proximity order is set to 1, there are six adjacent points to one center point. If any two points are selected from a total of seven points including the center point and the six adjacent points, there are 21 possible combinations of two points. The orientation difference between the two points in each of the 21 combinations is calculated, and the average value is taken as the LOS value. Furthermore, the average value of the calculated LOS is obtained by averaging the LOS values ​​over the measurement field of view. The LOS value is a value that corresponds to the amount of strain considering the orientation difference between pixels in the set kernel. In this embodiment, the proximity order is set to 1, and the calculation is performed for (1st) pixels with an angular difference of 5° or less. A high LOS value means that local strain exists. The presence of localized strain and areas with high strain energy can improve reactivity. For this reason, in this embodiment, it is preferable that the average value of LOS is 0.3° or higher. In this embodiment, it is more preferable that the lower limit of the average value of LOS be 0.31° or higher, and even more preferable that it be 0.32° or higher. On the other hand, there is no particular limit to the upper limit of the average value of LOS, but from the viewpoint of manufacturing cost, it is preferable that it be 3.5° or lower, and more preferable that it be 3.0° or lower.

[0050] (Average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane) If the above-mentioned full width at half maximum is 0.10° or more, it means that defects are present in the copper constituting the skeleton 12. The energy is high in these defective areas, which improves reactivity and improves the efficiency of organic compound formation. For the above reasons, in this embodiment, it is preferable that the average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane is 0.10° or more. In addition, in this embodiment, it is more preferable that the lower limit of the average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane is 0.11° or more, and even more preferable that it is 0.12° or more. On the other hand, there is no particular limit on the upper limit of the average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane, but from the viewpoint of manufacturing cost, it is more preferable that it is 1.00° or less, and even more preferable that it is 0.90° or less.

[0051] (Peak position of the {111} crystal plane) If the peak position of the crystal plane described above is 43.2° or less, it means that the added elements are dissolved in the bulk copper and are straining the crystal. The introduction of strain into the crystal increases the energy state, which promotes the formation of organic compounds. For the reasons above, in this embodiment, it is preferable that the peak position of the {111} crystal plane is 43.2° or less. In addition, in this embodiment, it is more preferable that the upper limit of the peak position of the {111} crystal plane is 43.1° or less, and even more preferable that it is 43.0° or less. On the other hand, there is no particular limit to the lower limit of the peak position of the {111} crystal plane, but from the viewpoint of manufacturing cost, it is more preferable that it is 41.5° or more, and even more preferable that it is 42.0° or more.

[0052] (Copper alloy containing one or more elements selected from Zn, Sn, and P) In this embodiment, when the copper alloy constituting the skeleton 12 contains one or more elements selected from Zn, Sn, and P, the added elements dissolve in the copper matrix, causing strain on the copper crystal lattice. The increased strain energy improves the efficiency of producing organic compounds such as methane, ethylene, and ethanol. For these reasons, in this embodiment, it is preferable that the skeleton 12 is composed of a copper alloy containing one or more elements selected from Zn, Sn, and P. The total content of one or more elements selected from Zn, Sn, and P is more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. On the other hand, in order to ensure sufficient copper content, the upper limit of the total content of one or more elements selected from Zn, Sn, and P is more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[0053] (Copper alloy containing a total of 0.1 mass% or more of one or more X elements selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, Ge) In this embodiment, if the copper alloy constituting the skeleton 12 contains a total of 0.1 mass% or more of one or more X elements selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, Ge, the X elements will solid dissolve in the copper matrix, causing the copper crystal lattice to be distorted. The increased strain energy will improve the efficiency of producing organic compounds such as methane, ethylene, and ethanol. For these reasons, in this embodiment, it is preferable that the skeleton 12 is made of a copper alloy containing a total of 0.1 mass% or more of one or more X elements selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, Ge. In this embodiment, the total content of one or more X elements selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, and Ge is more preferably 0.15% by mass or more, and even more preferably 0.2% by mass or more. On the other hand, in order to ensure sufficient copper content, the upper limit of the total content of one or more X elements selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, and Ge is more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[0054] (S5v of the surface layer of the skeleton 12) S5v is the absolute value of the average depth of the five deepest valleys within the measurement range. A S5v of 0.4 μm or more on the surface layer of the skeleton 12 means that fine, deep shapes are formed on the surface. This creates space for the raw material gas to diffuse, increasing the number of gas-liquid reaction sites and improving the efficiency of the production of organic compounds such as methane, ethylene, and ethanol. For the reasons above, in this embodiment, it is preferable that the S5v of the surface layer of the skeleton 12 is 0.4 μm or more. In this embodiment, the lower limit of the S5v of the surface layer of the skeleton 12 is more preferably 0.5 μm or more, and even more preferably 0.55 μm or more. On the other hand, the upper limit of the S5v of the surface layer of the skeleton 12 is more preferably 10 μm or less, and even more preferably 8 μm or less.

[0055] (S / A of the surface layer of the skeleton 12) In this embodiment, when the S / A ratio of the surface area S to the measured area A of the surface layer of the skeleton 12 is 1.20 or more, the surface area becomes sufficiently large, and the raw material CO ２ The number of reaction sites with the skeletal portion 12 increases. Furthermore, this also means that fine structures are formed on the surface, which improves the production efficiency of organic compounds such as methane, ethylene, and ethanol. For the reasons above, in this embodiment, it is preferable that the S / A ratio of the surface layer of the skeletal portion 12 is 1.20 or higher. In this embodiment, the lower limit of the S / A ratio of the surface layer of the skeletal portion 12 is more preferably 1.22 or higher, and even more preferably 1.25 or higher. On the other hand, there is no particular upper limit to the S / A ratio of the surface layer of the skeletal portion 12, but it is more preferably 5 or lower, and even more preferably 4.5 or lower.

[0056] (Surface treatment layer) In this embodiment, a surface treatment layer is formed on the surface of the skeleton 12, which increases the S5v and S / A of the surface layer of the skeleton 12, and the CO2 of the raw material ２ The gas flow path is secured, and the raw material CO ２The reaction between the gas and the skeletal portion 12 is promoted, improving the efficiency of producing organic compounds such as methane, ethylene, and ethanol. Here, it is preferable that the surface treatment layer is treated with a treatment solution within the pH range of 7 to 14.

[0057] (Total Faraday efficiency of ethylene, methane, and ethanol production) In this embodiment, if the total Faraday efficiency of ethylene, methane, and ethanol production is 1.5% or more, CO ２ It is expected to have applications as a catalyst for converting these into useful chemical products. Furthermore, the combined Faraday efficiency of ethylene, methane, and ethanol production is more preferably 1.7% or higher, and even more preferably 2.0% or higher. A higher combined Faraday efficiency of ethylene, methane, and ethanol production is preferable. The Faraday efficiency of production indicates the proportion of input electrons used in the production of the product, with 100% being the upper limit. There is no particular upper limit to the combined Faraday efficiency of ethylene, methane, and ethanol production as long as it is 100% or less; for example, it may be 100% or less, 90% or less, 80% or less, or 40% or less.

[0058] Next, an example of a method for manufacturing the copper bulk catalyst 10, which is this embodiment, will be described with reference to the flow chart shown in Figure 2.

[0059] (Melting and Casting Process S01) First, the molten copper obtained by melting oxygen-free copper raw material is mixed with the aforementioned elements to adjust its composition and produce a molten copper alloy. Individual elements or master alloys can be used for the addition of various elements. Alternatively, raw materials containing the aforementioned elements may be melted together with the copper raw material. Here, it is preferable that each element has a purity of 99.9 mass% or higher, known as 3N, or 99.99 mass% or higher, known as 4N. In the melting process, to reduce the hydrogen concentration, H ２It is preferable to perform atmospheric melting in an inert gas atmosphere with a low vapor pressure of oxygen (e.g., Ar gas), and to minimize the holding time during melting. Then, the molten copper alloy with adjusted composition is poured into a mold to produce an ingot. When considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0060] (Hot working process S02) Hot working is performed on the obtained ingot to introduce strain and deform its shape to a predetermined size. By introducing strain through hot working, high strain can be applied to the crystals while they are still coarse, thereby improving the homogeneity of the material. The total processing rate here needs to be constant because it is necessary to break down the cast structure, and is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. The plastic processing method is not particularly limited, but rolling is preferred when the final shape is foil or strip. Extrusion or groove rolling is preferred when the shape is wire, and forging or pressing is preferred when the shape is bulk.

[0061] (Roughing Process S03) Next, roughing is performed on the obtained hot-worked material to introduce strain and deform its shape to a predetermined size. The processing method is not particularly limited, but rolling is used when the final form is foil or strip, and extrusion or groove rolling is used when the final form is rod or wire. The processing temperature is not particularly limited, but -200 to 400°C is preferred for cold or warm processing. The total processing rate is also not particularly limited, but 30% or more is preferred to improve the efficiency of roughing.

[0062] (Heat treatment process S04) For homogenization and / or solution treatment, heat treatment is performed in an Ar gas atmosphere and then water quenching is carried out. The heat treatment method is not particularly limited, but it is preferable to carry it out in a non-oxidizing or reducing atmosphere. The heat treatment temperature is not particularly limited, but if the temperature is too low, a large amount of precipitate may be formed, making the processing process difficult. In addition, there is a possibility that recovery and recrystallization will not occur sufficiently, and insufficient diffusion may cause uneven concentration of added elements, so the heat treatment temperature is preferably 300°C or higher, and if it is too high, it will exceed the melting point of the material, so the heat treatment temperature must be 1000°C or lower. The cooling method should be a method with a cooling rate of 200°C / min, such as water quenching. If the cooling rate is slow, precipitates may appear during cooling. In addition, hot working may be carried out after heat treatment to further improve the efficiency of rough processing and to homogenize the structure. The processing method is not particularly limited, but rolling is used when the final form is foil or strip, and extrusion or groove rolling is used when it is rod or wire. The rough machining process S03 and the heat treatment process S04 may be repeated.

[0063] (Cold working process S05) Next, the copper material after the heat treatment process S04 is subjected to cold working with a processing rate of 20% or more to accumulate high energy on the surface of the copper material. To prevent the release of energy due to dynamic recrystallization and recovery, the processing is carried out at -200 to 200°C. The processing method is not particularly limited, but if the final form is foil or strip, rolling is used, and if it is a wire, wire drawing is used. The final thickness and wire diameter are not particularly limited. In addition, heat treatment may be performed after cold working for tempering.

[0064] (Shape-forming process S06) Processing is performed to form a channel for flowing the raw material gas and solution necessary for the catalytic reaction. The processing method is not limited, but punching or expanded metal processing is used for foils and strips. For wires, a mesh shape can be used. As a result of this shape-forming process S06, the number of voids 11 in a plane perpendicular to the thickness direction exceeds 500 in a 1 inch x 1 inch area, and the width of the skeleton 12 becomes 1 μm or more, and the thickness t (mm) and the area S (mm) of the plane perpendicular to the thickness direction are ２ ) but, t ２ / S x 10 ３ The shape will have a relationship of <5 and the volume ratio of the void portion 11 will be within the range of 5% to 80%.

[0065] (Surface treatment step S07) Next, in order to form a three-dimensional micro-shape on the surface of the skeleton 12, the surface is treated by immersion in an acid or basic solution or by an oxidation-reduction reaction. The acid solution is not particularly limited, but nitric acid, sulfuric acid, hydrochloric acid, etc. can be used. The basic solution is not particularly limited, but sodium hydroxide, ammonia solution, etc. can be used. The oxidation-reduction atmosphere can be selected from air, oxygen, hydrogen, etc. The treatment is performed at a temperature of 200°C or lower so as not to release the energy accumulated in the bulk catalyst. In this embodiment, it is preferable to perform the surface treatment using a treatment solution with a pH of 7 to 14.

[0066] Through the processes described above, the copper bulk catalyst 10 of this embodiment is produced.

[0067] Next, Figure 3 shows a schematic diagram of the electrochemical reactor 30 using the copper bulk catalyst 10 according to this embodiment. Note that the electrochemical reactor 30 in this embodiment is a polymer electrolyte type co-electrolytic device.

[0068] As shown in Figure 3, the electrochemical reactor 30 of this embodiment includes an electrolytic cell 31 comprising an anode electrode 32 and a cathode electrode 33 arranged opposite each other, an ion exchange membrane 34 positioned between the anode electrode 32 and the cathode electrode 33, and catalyst layers 35 and 36. Here, the anode electrode 32, cathode electrode 33, ion exchange membrane 34, and catalyst layer 35 can be those used in conventional general solid polymer water electrolysis devices.

[0069] Furthermore, the catalyst layer 36 disposed on the cathode electrode 33 side is composed of the copper bulk catalyst 10 of this embodiment. In the electrochemical reactor 30 (electrolytic cell 31) described above, as shown in Figure 3, water (H) is placed on the anode electrode 32 side. ２ O) is supplied, and CO is supplied to the cathode electrode 33 side. ２A supply is provided. Then, the anode electrode 32 and the cathode electrode 33 are energized. As a result, water is electrolyzed at the anode electrode 32, and the resulting oxygen (O) is produced. ２ ) is discharged from the anode electrode 32, and hydrogen (H ２ CO moves to the cathode electrode 33. Then, at the cathode electrode 33, ２ The catalyst is reduced to produce organic compounds such as ethylene, ethanol, and methane. These organic compounds are then discharged to the outside of the electrolytic cell 31 through the pores 11 of the copper bulk catalyst 10.

[0070] According to the copper bulk catalyst 10 of this embodiment, which has the above configuration, as shown in Figures 1A and 1B, it is generally flat and has void portions 11 that communicate in the thickness direction and a skeleton portion 12 made of copper or a copper alloy, and the number of void portions 11 that exist within a 1 inch x 1 inch area in a plane perpendicular to the thickness direction exceeds 500, so the CO of the raw material that passes through the void portions 11 ２ The gas and the skeletal part 12 made of copper or a copper alloy are in sufficient contact, CO ２ It can efficiently reduce gases and improve the efficiency of producing organic compounds such as ethanol, ethylene, and methane.

[0071] Furthermore, the width of the skeletal part 12 is set to 1 μm or more, and the thickness t (mm) and the area S (mm²) of the plane perpendicular to the thickness direction are defined. ２ ) but, t ２ / S x 10 ３ <Since it has a relationship with 5, manufacturing costs can be kept low and it is easy to handle. Furthermore, since the volume ratio of the void portion 11 is within the range of 5% to 80%, the raw material CO ２ This allows for good gas passage while ensuring the strength of the copper bulk catalyst 10, making it easy to handle.

[0072] In the copper bulk catalyst 10 of this embodiment, 1400 μm is obtained by the EBSD method. ２When the above measurement area is measured at a measurement interval of 0.08 μm steps, and measurement points with a CI value of 0.1 or less, as analyzed by the data analysis software OIM, are excluded, and measurement points containing two or more pixels are considered crystal grains, and grain boundaries are defined as orientation differences of 5° or more, if the average value of the LOS (Local Orientation Spread) is 0.3° or more, it means that local strain exists in the copper or copper alloy constituting the framework 12, and the areas with high strain energy become reaction sites, so the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0073] In the copper bulk catalyst 10 of this embodiment, if the average of the full width at half maximum of the {111} crystal plane and the {200} crystal plane, measured by X-ray diffraction using a copper tube, is 0.10° or more, it means that defects are present in the copper or copper alloy constituting the framework 12. These defects have high energy and become reaction sites, so the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0074] In the copper bulk catalyst 10 of this embodiment, if the peak position of the {111} crystal plane measured by X-ray diffraction using a copper tube is 43.2° or less, it means that in the copper alloy constituting the framework 12, the added elements are solid-dissolved in the copper matrix, causing distortion of the crystal. The introduction of distortion into the crystal increases the energy state, and the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0075] In the copper bulk catalyst 10 of this embodiment, if the framework 12 is made of a copper alloy containing one or more elements selected from Zn, Sn, and P, these alloying elements solid-solve in the copper matrix, causing strain on the copper crystal lattice and resulting in high energy, thus reducing the raw material CO ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0076] In the copper bulk catalyst 10 of this embodiment, if the S5v of the surface layer of the skeleton portion 12 is 0.4 μm or more, then a fine and deep shape is formed on the surface layer of the skeleton portion 12, and the raw material CO ２ There is a space where the gas diffuses, and CO ２ An increase in gas reaction sites promotes the production of organic compounds such as methane, ethylene, and ethanol.

[0077] In the copper bulk catalyst 10 of this embodiment, when the ratio S / A of the surface area S to the measured surface area A of the skeletal portion 12 is 1.20 or more, the surface area increases, and the number of reaction sites increases. Furthermore, fine structures are formed on the surface of the skeletal portion 12, which promotes the formation of organic compounds such as methane, ethylene, and ethanol.

[0078] In the copper bulk catalyst 10 of this embodiment, when the surface of the skeleton portion 12 has a surface treatment layer, the S5v value and S / A value of the surface of the skeleton portion 12 increase, ensuring fluid (gas and liquid) flow paths and increasing the number of reaction sites, thereby promoting the production of organic compounds such as methane, ethylene, and ethanol.

[0079] In the copper bulk catalyst 10 of this embodiment, if the combined Faraday efficiency of ethylene, methane, and ethanol production is 1.5% or more, the production efficiency of high value-added ethylene, methane, and ethanol is high, and it can be expected to be applied as a catalyst for converting carbon dioxide into useful chemical products.

[0080] In the copper bulk catalyst 10 of this embodiment, if the skeleton portion 12 contains a total of 0.1% by mass or more of one or more X elements selected from Al, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Ga, and Ge, these X elements solid-solve in the copper matrix, causing strain on the copper crystal lattice and resulting in high energy, thus reducing the CO2 in the raw material. ２ This can accelerate the reduction reaction and further increase the efficiency of organic compound formation.

[0081] According to the electrochemical reaction apparatus 30 of this embodiment, as shown in Figure 3, the copper bulk catalyst 10 of this embodiment is used, so CO ２ This technology allows for efficient reduction of gases and improves the efficiency of producing organic compounds such as ethanol, ethylene, and methane.

[0082] Although embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the technical spirit of the invention.

[0083] The results of the verification experiments conducted to confirm the effects of the present invention are described below.

[0084] Using a melting-down refining method, a raw material consisting of pure copper with a purity of 99.999% by mass or higher, along with 99.9% or higher of each additive element, was prepared. This was then charged into a high-purity graphite crucible and high-frequency melted in an atmospheric furnace with an Ar gas atmosphere. The resulting composition was adjusted to the one shown in Table 1, and the molten metal was poured into an insulating material (Isowool) mold to produce an ingot. The size of the ingot was approximately 20 mm thick x 50 mm wide x 150-200 mm long.

[0085] The obtained ingots were heated in an Ar gas atmosphere at the temperatures shown in Table 2 for 4 hours, and then hot-rolled at the processing rates shown in Table 2. The final pass temperature was confirmed by measuring the final temperature of the hot-rolling with a radiation thermometer. Next, surface grinding was performed to remove the oxide film from the hot-rolling, and the material was cut to the specified size. After that, the thickness was adjusted as needed to achieve the final thickness, and the material was cut again. Each of the hot-rolled cut samples underwent repeated rough processing and heat treatment under the conditions described in Table 1, and then cold-rolled to produce foil material with a thickness of 0.04 to 0.06 mm and a width of approximately 50 mm.

[0086] Furthermore, casting was carried out in the same manner as described above to produce ingots with a diameter of 20 mm and a length of approximately 150 to 200 mm. These ingots were subjected to hot working, heat treatment, and cold working under the conditions described in Table 2 to produce copper wire with a wire diameter of 0.03 to 0.3 mm or copper foil with a thickness of 0.04 to 0.1 mm.

[0087] As a shaping process, the obtained copper alloy foil material was subjected to expansion and punching. The obtained copper alloy wire material was processed into a mesh. At this time, as shown in Table 3, voids and skeletal parts were formed. Then, the obtained perforated metal and mesh material were subjected to surface treatment under the conditions shown in Table 3.

[0088] The copper bulk catalyst obtained through the above process was evaluated for its component composition, volume fraction of vacancies, number of vacancies in the plane, peak position of the {111} crystal plane, average value of the full width at half maximum of the {111} and {200} crystal planes, average LOS value, S5v value, S / A value, Faraday efficiency of ethylene production, Faraday efficiency of ethane production, and Faraday efficiency of ethanol production using the following procedure.

[0089] (Component Composition) Samples were taken from expanded metal, perforated metal, and mesh material before surface treatment and measured using an inductive emission spectrometer (ICP). The evaluation results are shown in Table 1.

[0090] (Volume Ratio of Void Areas) Samples were taken from the fabricated expanded metal, perforated metal, and mesh materials, and their width, length, and thickness were measured using calipers to determine their volume. The weight of the sample whose volume was determined was measured, and the volume ratio of the void area was calculated using the following formula from the ratio of the material density to the weight calculated from the volume. The evaluation results are shown in Table 3. (Volume ratio of void area) = ((Weight calculated from material density and volume) - (Measured weight)) / (Weight calculated from material density and volume) × 100

[0091] (Number of voids in a plane) Samples were taken from the fabricated perforated metal and mesh material and observed using an optical microscope (Leica Microsystems, DM4 M). The number of voids in a plane was measured, and the number within a 1-inch x 1-inch area was calculated. The evaluation results are shown in Table 3.

[0092] (Peak position of the {111} crystal plane, and average value of the full width at half maximum of the {111} and {200} crystal planes) Diffraction profiles were measured using a copper tube X-ray diffractometer (Bruker, D2 PHASER). For the measurement, a 0.6 mm divergent slit and a 3 mm air scatter sink were used, and the diffracted waves were detected by a one-dimensional detector (Bruker, LYNX-EYE) fitted with a nickel filter. The measurement interval was set to 0.004°, and the measurement was performed under integration conditions such that the peak intensity of the target crystal plane was between 5000 counts and 15000 counts. Using the analysis software DIFFRAC plus EVA, background was removed, and then the Kα2 component was removed by setting the intensity of Kα2 to 0.5 when the intensity of Kα1 was set to 1, and the position of the highest peak intensity was defined as the peak position. The peak width at the intensity where the peak intensity was halved was defined as the full width at half maximum. The evaluation results are shown in Table 3.

[0093] (S5v value and S / A value) Using a scanning white light interference microscope (Hitachi High-Tech Corporation, R5500HML-A150-AC), measurements were taken on the foil plane for perforated metal and expanded metal, and at 600 μm centered on the wire vertices for mesh. ２ The above area measurements were performed. Measurements were taken using a 530 white light source and a 110x objective lens in Wave measurement mode. The measurement data was analyzed using VS-Viewer ver. 6.0.0.58 (Hitachi High-Tech Corporation). Fourth-order surface correction was performed on the acquired data, and then, for pixels where height data could not be obtained, the height data calculated from surrounding pixels was used to compensate. For the corrected and interpolated data, the depth of the valley bottoms was measured, and the absolute value of the average depth of the five deepest valley bottoms was taken as the S5v value. In addition, the surface area S was calculated from the surface topography information and divided by the measured area A to obtain the S / A value. Measurements were taken for three or more fields of view for each sample, and the S5v value and S / A value for each field of view were obtained, and the average value was taken as the S5v value and S / A value for that sample. The evaluation results are shown in Table 3.

[0094] (LOS average value) Samples were taken from the fabricated expanded metal, perforated metal, and mesh materials. For the foil material, cross-sectional ion milling was performed on the cross-section perpendicular to the processing direction, and for the mesh material, cross-sectional ion milling was performed on the cross-section in the wire processing direction, to process the observation surface. These samples were analyzed using an EBSD measuring device (FEI Quanta FEG 450, EDAX / TSL (now AMETEK) OIM Data Collection) and analysis software (EDAX / TSL (now AMETEK) OIM Data Analysis ver. 8.6), with an electron beam acceleration voltage of 15 kV and a measurement interval of 0.08 μm steps over 1400 μm. ２ Measurements were taken over the above measurement area, and the average LOS value was calculated after excluding measurement points with a CI value of 0.1 or less. The cross-sectional area was 1400 μm². ２ For materials with a value less than , multiple cross-sectional measurements were performed, and the average LOS value for each field of view was calculated. The average of the average LOS values ​​for each field of view was used as the average LOS value for the material. The evaluation results are shown in Table 3.

[0095] (Carbon dioxide reduction test) Equipped with an anion exchange type ion exchange membrane, 1 cm ２ The obtained example was incorporated into the cathode of a class electrochemical cell, and the current density was 100 mA / cm² using a potentiogalvanostat (BioLogic HCP-803). ２ The flow between the electrodes was controlled to achieve the desired result. A porous titanium body plated with iridium oxide was used as the anode electrode. 10 cc / min of pure water, the raw material, was flowed through the anode using a precision diaphragm pump (Takumina Smooth Flow Pump Q Series). Pure CO2 was used as the cathode. ２ The gas flow rate is controlled to 10 cc / min using a mass flow controller (manufactured by KOFLOC), and further, 0.1 M KHCO is added. ３ The aqueous solution was flowed using a precision diaphragm pump (FLOM Corporation; KP21) at a controlled rate of 1 cc / min.

[0096] (Faradaic efficiency of ethylene production, Faradaic efficiency of methane production) The solution after the reaction discharged from the cathode was separated from the gas, and the percentage of the target substance (R) contained in the obtained gas was measured with a gas chromatograph (Micro GC Fusion manufactured by INFICONO). In this experiment, there are only four types of gases that affect the measurement of the gas chromatograph. It is composed of four components: carbon dioxide (raw material & carrier gas), methane (product gas), ethylene (product gas), and hydrogen gas (product gas (side reaction gas)), and is equal to their total sum.

[0097] Here, the gas flow rate (V) introduced into the gas chromatograph was defined as follows as the sum of the gas flow rates of the above four types of gases (V CO2 +V H2 +V CH4 +V C2H4 ). V=(V CO2 +V H2 +V CH4 +V C2H4 ) In this experiment, before introducing it into the electrochemical cell, the gas flow rate was controlled to 10 cc / min for the raw material CO ２ gas flow rate with a mass flow meter (RK1200; KOFLOC), and its actual flow rate (V 0 CO2 ) was measured with a gas mass flow meter (CMS9500, Azbil Corporation). After passing through the electrochemical cell, the CO ２ gas flow rate changes due to the following two electrochemical reactions. Item 1. Flow rate change associated with ethylene production from CO ２ Item 2. Flow rate change due to the production of liquid components such as ethanol and formic acid from CO ２

[0098] For each of the above items, V CO2 was determined by making corrections as follows. Correction method for Item 1: Using the intensity ratio of the CO ２ peak and the ethylene peak obtained by the gas chromatograph, a correction was made for the decrease in V 0 CO2 . Correction method for Item 2: Using the production rates of formic acid, ethanol, etc. calculated by the liquid chromatograph, V 0CO2 A correction was applied to the decrease in V. H2 , V CH4 , V C2H4 This was calculated using gas chromatography, specifically by utilizing the peak ratio with carbon dioxide gas.

[0099] The value R measured by gas chromatography was defined as follows using the above V. In the case of methane gas, R CH4 = V CH4 / (V CO2 +V H2 +V CH4 +V C2H4 ) In the case of ethylene gas, R C2H4 =V C2H4 / (V CO2 +V H2 +V CH4 +V C2H4 )

[0100] Using the proportions (R) of various gases calculated from experimental values ​​in the above procedure, the Faraday efficiency FE of the target gas component was calculated from the following formula. The evaluation results are shown in Table 4. FE = n × R × F × V / (I × 22.4) where, I (A): constant current flowed through the electrode during electrolysis F (As / mol): Faraday constant n: number of reaction electrons (e.g., CO ２ →In the methane production reaction, 8. In the ethylene reaction, 12) V (L / s): Gas flow rate in the experimental system R: The proportion of the target gas in the gas measured by high-performance liquid chromatography.

[0101] (Faraday efficiency of ethanol production) The post-reaction solution discharged from the cathode was separated from the gas, and the ethanol concentration in the resulting liquid was measured using a high-performance liquid chromatograph (JASCO Extreme). The ethanol concentration obtained by the high-performance liquid chromatograph was denoted as C, and the Faraday efficiency FE was calculated from the following formula. The evaluation results are shown in Table 4. FE = n × C × F / (I × t × M) where, I (A): constant current flowed through the electrode during electrolysis t (s): electrolysis time C (g / L): ethanol concentration measured by high-performance liquid chromatograph F (As / mol): Faraday constant n: number of reaction electrons (CO ２→In the ethanol production reaction, 12) M (g / mol): Molecular weight.

[0102]

[0103]

[0104]

[0105]

[0106] In Comparative Examples 1 and 2, the number of voids in a plane perpendicular to the thickness direction was 500 or less within a 1-inch x 1-inch area, and the volume fraction of the voids exceeded 80%, causing the ion exchange membrane to rupture during the carbon dioxide reduction test. As a result, it was not possible to measure the Faraday efficiencies of ethylene, methane, and ethanol. In Comparative Examples 3 and 4, the perforated metal did not have voids formed, resulting in very low Faraday efficiencies of ethylene, methane, and ethanol.

[0107] In contrast, in the present invention example 1-12, the number of voids in a plane perpendicular to the thickness direction exceeds 500 in a 1-inch x 1-inch area, and the thickness t (mm) and the area S (mm) of the plane perpendicular to the thickness direction ２ ) but, t ２ / S x 10 ３ The relationship <5 was observed, and the volume fraction of the void was within the range of 5% to 80%, resulting in sufficiently high Faraday efficiencies for ethylene, methane, and ethanol.

[0108] Based on the results of the above verification experiments, the present invention provides easy handling and high Faraday efficiency in CO2 production. ２ It was confirmed that a copper bulk catalyst capable of producing organic compounds can be provided.

[0109] According to the present invention, CO2 is easy to handle and has high Faraday efficiency. ２ This makes it possible to provide a copper bulk catalyst capable of producing organic compounds.

[0110] 10 Copper bulk catalyst 11 Cavity section 12 Skeleton section

Claims

1. It is generally flat and has a void portion communicating in the thickness direction and a skeletal portion made of copper or a copper alloy, the number of void portions in a plane perpendicular to the thickness direction exceeds 500 in a 1 inch x 1 inch area, and the width of the skeletal portion is 1 μm or more, and the thickness t (mm) and the area S (mm) of the plane perpendicular to the thickness direction ２ ) but, t ２ / S x 10 ３ A copper bulk catalyst characterized by having a relationship of <5 and having a volume fraction of the void portion within the range of 5% to 80%.

2. EBSD method to 1400 μm ２ The copper bulk catalyst according to claim 1, characterized in that, when the above measurement area is measured at a measurement interval of 0.08 μm steps, and measurement points with a CI value of 0.1 or less, as analyzed by the data analysis software OIM, are excluded, and those containing two or more measurement points are considered as crystal grains, and grain boundaries are defined as orientation differences of 5° or more, the average value of the Local Orientation Spread (LOS) is 0.3° or more.

3. The copper bulk catalyst according to claim 1, characterized in that the average value of the full width at half maximum of the {111} crystal plane and the {200} crystal plane, as measured by X-ray diffraction using a copper tube, is 0.10° or more.

4. The copper bulk catalyst according to claim 1, characterized in that the peak position of the {111} crystal plane, as measured by X-ray diffraction using a copper tube, is 43.2° or less.

5. The copper bulk catalyst according to claim 1, characterized in that the skeletal portion is made of a copper alloy containing one or more elements selected from Zn, Sn, and P.

6. The copper bulk catalyst according to claim 1, characterized in that the S5v of the surface layer of the skeletal portion is 0.4 μm or more.

7. The copper bulk catalyst according to claim 1, characterized in that the ratio S / A of the surface area S to the measured surface area A of the skeletal portion is 1.20 or more.

8. The copper bulk catalyst according to claim 1, characterized in that the surface layer of the skeletal portion has a surface treatment layer.

9. The copper bulk catalyst according to claim 1, characterized in that the sum of the Faraday efficiencies for the production of ethylene, methane, and ethanol is 1.5% or more.

10. An electrochemical reaction apparatus characterized by using a copper bulk catalyst as described in any one of claims 1 to 9.

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