Copper alloy catalyst

Abstract

A copper alloy catalyst according to the present invention is characterized by being composed of a bulk material of a copper alloy which contains one or more kinds of alloy elements that are selected from among Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and which has a Cu content of 50 atom% or more. The copper alloy catalyst is also characterized in that if a droplet of ion exchange water is dropped on the surface of the bulk material, the contact angle measured by a θ / 2 method is 95° or more.

Description

copper alloy catalyst

[0001] The present invention is ２ This application claims priority to Japanese Patent Application No. 2023-214645 filed in Japan on December 20, 2023, and Japanese Patent Application No. 2024-195796 filed in Japan on November 8, 2024, the contents of which are incorporated herein by reference.

[0002] With global warming accelerating, CO in the atmosphere ２ Reducing greenhouse gases (GHGs), such as carbon dioxide (CO), is a global challenge. In recent years, the development of carbon dioxide capture and utilization (CCU) technology, which utilizes atmospheric carbon dioxide as a raw material to produce useful chemical products, has been accelerating. Carbon dioxide has the highest oxidation state of carbon, +4, and is a very stable compound with a standard Gibbs energy of formation of approximately 400 kJ / mol. Converting carbon dioxide into useful chemical products requires the reduction of carbon using a large amount of energy. There is a need for the development of technology that can reduce carbon dioxide energy efficiently.

[0003] In recent years, attention has been drawn to a co-electrolysis method using an electrolysis cell made of a polymeric ion exchange membrane (see, for example, Patent Documents 1 and 2). The co-electrolysis method is a technique in which electrolysis by oxidation reaction at the anode and electrolysis by reduction reaction at the cathode are simultaneously carried out in an electrochemical cell. For example, water is supplied to the anode and KHCO3 is supplied to the cathode. ３ Aqueous solution and CO ２ By using gas as a raw material, H ２ Using protons generated from the electrolysis of O, CO ２ When Cu is used as a catalyst, CO can be reduced with high faradaic efficiency. ２ From this, organic compounds of C2 or more (e.g., ethanol) can be obtained.

[0004] In addition, copper catalysts have conventionally been provided as powders or sputtered thin films because bulk materials have a low efficiency of generating organic compounds of C2 or higher. Non-Patent Document 1 also states that copper catalysts made of sputtered thin films can be produced with higher Faraday efficiency by forming a polymer film on the surface to increase water repellency. ２ It has been reported that organic compounds of C2 or higher can be produced from this.

[0005] Japanese Unexamined Patent Publication No. 2022-049861 (A) Japanese Unexamined Patent Application No. 2022-040803 (A)

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

[0007] It is known that the catalytic properties of copper catalysts can be improved by adding specific alloying elements. However, in conventional powders or sputtered thin films, the alloying elements could not be uniformly mixed, and the effect of improving catalytic properties through alloying could not be fully achieved. Furthermore, copper catalysts made of powders or sputtered thin films have problems such as poor handling, high cost, and poor energy efficiency during production. Furthermore, in Non-Patent Document 1, water repellency is improved by forming a polymer film on the surface of the sputtered thin film, but this method has high process costs and stability issues.

[0008] The present invention has been made in light of the above circumstances, and provides a CO 2 gas emitting device that is made of a bulk material that is easy to handle and has high Faraday efficiency. ２ The present invention aims to provide a copper alloy catalyst capable of producing organic compounds of C2 or more from

[0009] In order to solve these problems and achieve the above-mentioned object, a copper alloy catalyst according to a first aspect of the present invention comprises a bulk material of a copper alloy containing one or more alloy elements selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and having a Cu content of 50 atomic % or more, and is characterized in that when a droplet of ion-exchanged water is dropped on the surface of the bulk material, the contact angle measured by the θ / 2 method is 95° or more.

[0010] According to the copper alloy catalyst of the first aspect of the present invention, the catalyst is composed of a bulk material of copper alloy containing one or more alloying elements selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and containing 50 atomic % or more of Cu, and therefore the catalyst is easy to handle and can fully utilize the effect of improving catalytic properties by alloying. Furthermore, when a drop of ion-exchanged water is dropped on the surface of the bulk material, the contact angle measured by the θ / 2 method is 95° or more, and therefore the catalyst has high water repellency and can produce CO with high Faraday efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0011] The copper alloy catalyst of Aspect 2 of the present invention is characterized in that, in the copper alloy catalyst of Aspect 1 of the present invention, the developed surface area ratio Sdr of the surface of the bulk material is 1% or more. According to the copper alloy catalyst of Aspect 2 of the present invention, the developed surface area ratio Sdr of the surface of the bulk material is 1% or more, and fine irregularities are formed on the surface layer, which can improve reactivity, increase water repellency, and further produce CO with high Faraday efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0012] The copper alloy catalyst of the third aspect of the present invention is the copper alloy catalyst of the first or second aspect of the present invention, which has a particle size of 5000 μm or less by the EBSD method. ２ The above measurement areas are measured at measurement intervals of 0.1 μm, and the average KAM value is 0.30° or more when excluding measurement points where the CI value is 0.1 or less as analyzed by data analysis software OIM. According to the copper alloy catalyst of aspect 3 of the present invention, since the average KAM value is 0.30° or more, strain energy is accumulated, making it possible to improve reactivity.

[0013] The copper alloy catalyst of aspect 4 of the present invention is characterized in that, in the copper alloy catalyst of any one of aspects 1 to 3 of the present invention, it contains 2 atomic % or more of one or more alloying elements selected from Zn, Al, Ca, and Mg, and the surface layer of the bulk material is a surface-treated layer treated with an acid or basic solution. According to the copper alloy catalyst of aspect 4 of the present invention, since it contains 2 atomic % or more of one or more alloying elements selected from Zn, Al, Ca, and Mg, and the surface layer of the bulk material is a surface-treated layer treated with an acid or basic solution, Zn, Al, Ca, and Mg, which are metals less noble than copper, are preferentially dissolved, a fine structure is formed in the surface layer, water repellency is improved, and CO is produced with a high Faraday efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0014] The copper alloy catalyst of Aspect 5 of the present invention is characterized in that the Faradaic efficiency of ethanol production is 0.8% or more in the copper alloy catalyst of any one of Aspects 1 to 4 of the present invention. The copper alloy catalyst of Aspect 5 of the present invention has a high Faradaic efficiency of ethanol production of 0.8% or more, making it possible to efficiently produce ethanol.

[0015] The electrochemical reaction device of the sixth aspect of the present invention is characterized by using the copper alloy catalyst of any one of the first to fifth aspects of the present invention. According to the electrochemical reaction device of the sixth aspect of the present invention, since the copper alloy catalyst of any one of the first to fifth aspects of the present invention is used, CO is produced with high faradaic efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0016] According to the present invention, a CO 2 -emitting element is made of a bulk material that is easy to handle and has high Faraday efficiency. ２ It is possible to provide a copper alloy catalyst capable of producing organic compounds of C2 or more from

[0017] Fig. 1 is an explanatory diagram showing an example of a copper alloy catalyst according to an embodiment of the present invention, in which the copper alloy catalyst is a mesh material obtained by processing a copper alloy wire; Fig. 2 is an explanatory diagram showing an example of a copper alloy catalyst according to an embodiment of the present invention, in which the copper alloy catalyst is a punched metal having a plurality of holes formed in a copper alloy plate; Fig. 3 is a flow chart showing an example of a method for producing the copper alloy catalyst according to the present embodiment; Fig. 4 is an explanatory diagram showing an example of an electrochemical reaction device using the copper alloy catalyst according to an embodiment of the present invention;

[0018] Hereinafter, a copper alloy catalyst and an electrochemical reaction device according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0019] The copper alloy catalyst 10 of this embodiment is, for example, ２ It is used in an electrochemical reaction device that electrolytically reduces gas to produce organic compounds of C2 or more (organic compounds with two or more carbon atoms).

[0020] 1A and 1B, the copper alloy catalyst 10 of this embodiment is a bulk material having a generally rectangular shape. Fig. 1A shows a mesh material formed by processing copper alloy wire, and Fig. 1B shows a punched metal formed by forming a plurality of holes in a copper alloy plate. The copper alloy catalyst 10 of this embodiment is made of a copper alloy containing one or more alloying elements selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and containing 50 atomic % or more of Cu.

[0021] In the copper alloy catalyst 10 of this embodiment, it is preferable that the developed surface area ratio Sdr of the bulk material surface is 1% or more. ２ The above measurement area is measured at measurement intervals of 0.1 μm, and the average KAM value is preferably 0.30° or more when excluding measurement points where the CI value analyzed by data analysis software OIM is 0.1 or less.

[0022] In addition, the copper alloy catalyst 10 of this embodiment preferably contains 2 atomic % or more of one or more alloy elements selected from Zn, Al, Ca, and Mg, and the surface layer of the bulk material is preferably a surface-treated layer treated with an acid or basic solution.Furthermore, in the copper alloy catalyst 10 of this embodiment, it is preferable that the Faraday efficiency of ethanol production is 0.8% or more.

[0023] The reasons for specifying the composition, water contact angle, average KAM, surface treatment layer, Faradaic efficiency of ethanol production, and ratio of the Faradaic efficiency of formic acid production to the Faradaic efficiency of ethanol production as described above for the copper alloy catalyst 10 of this embodiment will be explained below.

[0024] (Alloying element: one or more selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, Sn) In the copper alloy catalyst 10 made of a copper alloy containing the above-mentioned alloying elements, CO generated on the surface ２ The decomposition reaction and the ethanol production reaction are promoted, and the ethanol production efficiency is improved. In this embodiment, since the copper alloy catalyst 10 is a bulk material, the alloying elements are uniformly dispersed, resulting in stable catalytic properties. The total content of the above-mentioned alloying elements is preferably 0.03 atomic % or more, and more preferably 1.00 atomic % or more.

[0025] (Cu Content: 50 Atm% or More) As described above, the inclusion of alloying elements improves the ethanol production efficiency, but if the Cu content is less than 50 atm%, the catalytic properties of the Cu itself may not be obtained. For this reason, in this embodiment, the Cu content is specified to be 50 atm% or more. The Cu content is preferably 52 atm% or more, and more preferably 55 atm% or more.

[0026] (Water contact angle: 95° or more) When a droplet of ion-exchanged water is dropped onto the surface of the copper alloy catalyst 10 made of a bulk material, if the contact angle measured by the θ / 2 method is 95° or more, the catalyst has sufficient water repellency, gas-liquid reaction sites are secured, the reaction can be promoted, and the efficiency of ethanol production is improved. The water contact angle is preferably 97° or more, and more preferably 100° or more. The water contact angle may be, for example, 175° or less, or 170° or less.

[0027] (Surface developed area ratio Sdr: 1% or more) The developed area ratio Sdr is a value indicating the increase in the developed area of ​​the measurement area relative to the area of ​​the measurement area. The Sdr of a completely flat surface is 0, and the larger the Sdr, the larger the surface area of ​​the material. When Sdr is 1% or more, CO ２ The surface area where the decomposition reaction occurs is increased, thereby improving reactivity. Furthermore, a large development area ratio Sdr of 1% or more means that fine features are formed on the surface layer, which improves water repellency and thereby improves the production efficiency of high-value-added C2 or higher organic compounds. Sdr may be, for example, 200% or less, or 190% or less. The development area ratio Sdr of the surface of the copper alloy catalyst 10 made of bulk material is more preferably 1.5% or more, and even more preferably 2.0% or more.

[0028] (KAM Average Value: 0.30° or More) The KAM (Kernel Average Misorientation) value measured by EBSD is calculated by averaging the misorientation between one pixel and its surrounding pixels. Because the pixel shape is a regular hexagon, when the proximity order is set to 1, the average misorientation between six adjacent pixels is calculated as the KAM value. Using this KAM value, local misorientation, i.e., strain distribution, can be visualized. By setting the KAM average value to 0.30° or more, strain energy is accumulated on the material surface, improving reactivity. Furthermore, as described below, when the surface layer of a bulk material is treated with a basic or acidic solution, a microstructure is more likely to be formed, improving water repellency. The KAM average value is more preferably 0.35° or more, and even more preferably 0.40° or more. The average value of KAM may be 3.0° or less, or 2.50° or less.

[0029] (Surface Treatment Layer) In this embodiment, when the bulk material contains 2 atomic % or more of one or more alloying elements selected from Zn, Al, Ca, and Mg, and the surface layer of the bulk material is a surface treatment layer treated with an acid or basic solution, the surface treatment preferentially dissolves one or more alloying elements selected from Zn, Al, Ca, and Mg, which are less noble than copper, forming a microstructure in the surface layer of the bulk material and improving water repellency.

[0030] (Faraday efficiency of ethanol production) In this embodiment, if the faradaic efficiency of ethanol production is 0.8% or more, application to a catalyst for converting carbon dioxide into useful chemical products can be expected. The faradaic efficiency of ethanol production is more preferably 1.0% or more, and even more preferably 1.2% or more.

[0031] Next, an example of a method for producing the copper alloy catalyst of this embodiment having the above-described configuration will be described with reference to the flow chart shown in FIG.

[0032] (Melting and Casting Step S01) First, the above-mentioned elements are added to the molten copper obtained by melting an oxygen-free copper raw material to adjust the composition, thereby producing a molten copper alloy. The various elements can be added in the form of simple elements or master alloys. Alternatively, a raw material containing the above-mentioned elements may be melted together with the copper raw material. Here, each element is preferably so-called 3N copper with a purity of 99.9 mass% or more, or so-called 4N copper with a purity of 99.99 mass% or more. In the melting step, H is added to reduce the hydrogen concentration. ２ It is preferable to perform atmospheric melting in an inert gas atmosphere (e.g., Ar gas) with a low O vapor pressure, and to minimize the holding time during melting. The molten copper alloy with the adjusted composition is then poured into a mold to produce an ingot. Note that, when mass production is taken into consideration, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0033] (Hot working step S02) The obtained ingot is subjected to hot working to introduce strain and deform the shape to a predetermined size. By introducing strain through hot working, high strain can be imparted to the material while the crystals are still coarse, thereby improving the homogeneity of the material. The total working rate here must be a certain level, as it is necessary to destroy the cast structure, and is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. The plastic working method is not particularly limited, but rolling is preferably used if the final shape is a foil or a shape. In the case of wire, extrusion or groove rolling is preferably used, and in the case of bulk shapes, forging or pressing is preferably used.

[0034] (Rough processing step S03) Next, the obtained hot-processed material is subjected to rough processing to introduce strain and deform the shape to a predetermined size. Here, the processing method is not particularly limited, but rolling is used if the final form is a foil or strip, and extrusion or groove rolling is used if the final form is a rod or wire. The processing temperature is also not particularly limited, but a temperature of -200 to 400°C, which results in cold or warm processing, is preferred. The total processing rate is also not particularly limited, but is preferably 30% or more to improve the efficiency of rough processing.

[0035] (Heat Treatment Step S04) For homogenization and / or solutionization, the material is heat-treated in an Ar gas atmosphere and water-quenched. While the heat treatment method is not particularly limited, it is preferable to perform the heat treatment in a non-oxidizing or reducing atmosphere. The heat treatment temperature is not particularly limited, but a low temperature can result in the formation of large amounts of precipitates, making the processing difficult. Furthermore, a heat treatment temperature of 400°C or higher is preferable because a low temperature can lead to insufficient recovery and recrystallization, as well as insufficient diffusion, resulting in uneven concentrations of added elements. However, a high temperature exceeds the melting point of the material, so the heat treatment temperature must be 1000°C or lower. A cooling method with a cooling rate of 200°C / min, such as water quenching, is required. A slow cooling rate can result in the appearance of precipitates during cooling. Furthermore, hot working may be performed after the heat treatment to further improve the efficiency of rough processing and homogenize the structure. While the processing method is not particularly limited, rolling is used for the final form of foil or strip, while extrusion or groove rolling is used for the final form of rod or wire. The rough processing step S03 and the heat treatment step S04 may be repeatedly performed.

[0036] (Cold Working Step S05) Next, the copper material after the heat treatment step S04 is subjected to cold working at a working ratio of 50% or more, thereby accumulating high energy on the surface of the copper material. In order to prevent the release of energy due to dynamic recrystallization and recovery, working is carried out at a temperature of -200 to 200°C. The working method is not particularly limited, but rolling is used when the final form is a foil or strip, and wire drawing is used when it is a wire. The final thickness and wire diameter are not particularly limited, but thicknesses and wire diameters such as 1 mm, 0.5 mm, 0.1 mm, 0.05 mm, and 0.01 mm are applicable. In addition, heat treatment may be carried out for tempering after cold working.

[0037] (Shaping step S06) Processing is performed to form channels for flowing raw material gases and solutions required for the catalytic reaction. There are no limitations on the processing method, but punching or expanded metal processing can be used for foils and strips. A mesh shape can be used for wires.

[0038] (Surface layer treatment step S07) Next, the surface layer is treated by immersion in an acid or basic solution. When the alloy contains 2 atomic % or more of one or more alloy elements selected from Zn, Al, Ca, and Mg, which are metals more sensitive than Cu, the metals more sensitive than Cu dissolve preferentially, forming a microstructure in the surface layer and increasing the contact angle on the surface. 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.

[0039] The copper alloy catalyst of this embodiment is produced by the above-described steps.

[0040] Next, a schematic diagram of an electrochemical reaction device 30 using the copper alloy catalyst 10 of this embodiment is shown in Figure 3. The electrochemical reaction device 30 of this embodiment is a solid polymer type co-electrolysis device.

[0041] 3 , the electrochemical reaction device 30 of this embodiment includes an electrolysis cell 31 including an anode 32 and a cathode 33 arranged opposite to each other, an ion-permeable membrane 34 arranged between the anode 32 and the cathode 33, and catalyst layers 35 and 36. Here, the anode 32, the cathode 33, the ion-permeable membrane 34, and the catalyst layer 35 may be any of those used in conventional general solid polymer water electrolysis devices.

[0042] The catalyst layer 36 disposed on the cathode 33 side is made of the copper alloy catalyst 10 of this embodiment. In the electrochemical reaction device 30 (electrolysis cell 31), as shown in FIG. 3, water (H ２ O) is supplied to the cathode 33 side, and CO ２ Then, the anode 32 and the cathode 33 are energized. Then, the water is electrolyzed at the anode 32, and the generated oxygen (O ２ ) is discharged from the anode 32, and hydrogen (H ２ ) moves to the cathode 33. At the cathode 33, CO ２is reduced to produce organic compounds of C2 or higher, such as ethanol. The produced organic compounds of C2 or higher, such as ethanol, are discharged to the outside of the electrolytic cell 31 through the pores 13 of the member body 11.

[0043] The copper alloy catalyst 10 of this embodiment, which is configured as described above, is made of a bulk material of copper alloy containing one or more alloying elements selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and containing 50 atomic % or more of Cu, and therefore has excellent handleability and can fully utilize the effect of improving catalytic properties by alloying. Furthermore, when a drop of ion-exchanged water is dropped on the surface of the bulk material, the contact angle measured by the θ / 2 method is 95° or more, so that the catalyst has high water repellency and can produce CO with high Faraday efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0044] In this embodiment, when the developed surface area ratio Sdr of the surface of the bulk material constituting the copper alloy catalyst 10 is 1% or more, fine irregularities are formed on the surface layer of the bulk material, which can improve reactivity, increase water repellency, and further increase the Faraday efficiency of CO ２ It is possible to produce organic compounds of C2 or more from

[0045] In this embodiment, 5000 μm was obtained by the EBSD method. ２ The above measurement area is measured at 0.1 μm intervals, and when the average value of KAM is 0.30° or more, excluding measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less, strain energy is accumulated inside the bulk material, which can improve reactivity and produce CO with high Faraday efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0046] In this embodiment, when the bulk material contains 2 atomic % or more of one or more alloy elements selected from Zn, Al, Ca, and Mg, and the surface layer of the bulk material is a surface-treated layer that has been treated with an acid or basic solution, Zn, Al, Ca, and Mg, which are metals less noble than copper, are preferentially dissolved, a fine structure is formed in the surface layer, water repellency is increased, and CO 2 is generated with a high Faraday efficiency. ２ It is possible to produce organic compounds of C2 or more from

[0047] In this embodiment, when the faradaic efficiency of ethanol production is 0.8% or more, it is possible to reliably produce ethanol efficiently.

[0048] According to the electrochemical reaction device 30 of this embodiment, the copper alloy catalyst 10 of this embodiment described above is used as the catalyst layer 36 disposed on the cathode 33 side, so that CO ２ It is possible to produce organic compounds of C2 or more from

[0049] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention.

[0050] The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0051] A raw material consisting of pure copper with a purity of 99.999% by mass or higher, refined by the zone melting refining method, and each additive element with a purity of 99.9% or higher, was prepared. This was placed in a high-purity graphite crucible and subjected to high-frequency melting in an atmospheric furnace with an Ar gas atmosphere. The composition shown in Table 1 was prepared, and the molten metal was poured into a mold made of insulating material (Isowool) to produce an ingot. The size of the ingot was approximately 15 mm thick, approximately 50 mm wide, and approximately 150-200 mm long.

[0052] The resulting ingots were heated in an Ar gas atmosphere at the temperatures shown in Table 2 for 4 hours and hot-rolled at the working ratios shown in Table 2. The final pass temperature of the hot rolling was confirmed by measuring the final temperature with a radiation thermometer. Next, the surface was ground to remove the oxide film formed during hot rolling, and the ingots were cut to a predetermined size. The thickness was then adjusted appropriately to achieve the final thickness, and the ingots were cut. Each of the cut hot-rolled samples was repeatedly subjected to rough processing and heat treatment under the conditions shown in Table 1, and then cold-rolled to produce foils with thicknesses of 0.04 to 0.06 mm and widths of approximately 50 mm.

[0053] Further, casting was carried out in the same manner as above to produce an ingot having a diameter of 15 mm and a length of approximately 150 to 200 mm. This ingot was subjected to hot working, heat treatment, and cold working under the conditions shown in Table 2 to produce a copper alloy wire having a wire diameter of 0.09 mm.

[0054] As a shaping step, the obtained copper alloy foil material was subjected to a punching process. The hole diameter was approximately 0.6 mm and the pitch was 1.5 mm. The obtained copper alloy wire material was processed into a mesh with a mesh count of 120 and an opening of 0.12 mm. The obtained punched metal and mesh material were then immersed in an acid or basic solution shown in Table 2, and surface treatment was performed under the conditions shown in Table 1.

[0055] The copper alloy catalysts obtained by the above steps were evaluated for their component composition, surface contact angle, developed area ratio Sdr, average KAM, and carbon dioxide reduction properties in the following manner. The evaluation results are shown in Table 3.

[0056] (Componential Composition) Measurement samples were taken from the obtained ingots and measured using a high-frequency induction luminescence analyzer (ICP).

[0057] (Contact Angle) Using a contact angle meter (DMo-702 manufactured by Kyowa Interface Science Co., Ltd.), 2 μL of ion-exchanged water was dropped onto a copper alloy catalyst (copper alloy foil material or mesh material), and the contact angle was measured after 1 second. The θ / 2 method was used to measure the contact angle. The measurement environment was a temperature of 23±5°C and a humidity of 65%±10%. After surface treatment, the sample was washed with ethanol, dried in the air for at least one day, and measured within 30 days. Measurement was performed five or more times, and the average value was taken as the contact angle.

[0058] (Developed Area Ratio) The developed area ratio was measured using a laser microscope (OLS5100 manufactured by Olympus). ２ The above areas were measured in three or more visual fields, and the developed area ratio Sdr was calculated. At this time, the λc filter defining the boundary between the roughness component and the waviness component was set to 25 μm, and wavelength components longer than 80 μm were removed to calculate the developed area ratio. The average value of each visual field was taken as the developed area ratio Sdr.

[0059] (Average KAM) Samples were cut out from copper alloy catalysts (copper alloy foils or meshes), and the cross sections of the foils in the direction perpendicular to the processing direction, and the cross sections of the meshes in the direction of the wire processing direction were mechanically polished using waterproof abrasive paper and diamond abrasive grains, and then finished polished using colloidal silica solution.These samples were analyzed using an EBSD measuring device (Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX / TSL (now AMETEK)) and analysis software (OIM Data Analysis ver. 8.6 manufactured by EDAX / TSL (now AMETEK)) at an electron beam acceleration voltage of 15 kV, a measurement interval of 5000 μm at 0.1 μm steps. ２ In the above measurement area, the average value was calculated from the KAM value of each pixel, excluding measurement points where the CI value was 0.1 or less.

[0060] (Carbon dioxide reduction test) A 1 cm ２ The obtained example was incorporated into the cathode of a 1000-kJ electrochemical cell, and the current density was 16 mA / cm using a potentiogalvanostat (HCP-803 manufactured by BioLogic). ２The flow between the electrodes was controlled so that the anode electrode was a porous titanium body plated with iridium oxide. Pure water, the raw material, was flowed through the anode at 10 cc / min using a precision diaphragm pump (Takumina Corporation, Smoothflow Pump Q Series). Pure CO ２ The gas was controlled at 10 cc / min using a mass flow controller (manufactured by KOFLOC), and 0.1 M KHCO ３ The aqueous solution was flowed at a controlled rate of 1 cc / min using a precision diaphragm pump (FLOM KP21).

[0061] (Faraday efficiency for ethanol production) The post-reaction solution discharged from the cathode was separated from the gas, and the ethanol concentration contained in the resulting liquid was measured using a high-performance liquid chromatograph (Extrema manufactured by JASCO). The ethanol concentration obtained using the high-performance liquid chromatograph was defined as C, and the faraday efficiency FE was calculated using the following formula: FE = n × C × F / (I × t × M) where, I (A): constant current applied to the electrode during electrolysis, t (s): electrolysis time, C (g / L): ethanol concentration measured using the 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.

[0062]

[0063]

[0064]

[0065] In Comparative Example 1, the sample was made of pure copper, had a small surface contact angle of 94°, and had a low Faraday efficiency of ethanol production of 0.24%. In Comparative Example 2, the sample was made of a copper alloy containing Zn and Ni, but the Cu content was less than 50%, had a small surface contact angle of 90°, and had a low Faraday efficiency of ethanol production of 0.33%. In Comparative Example 3, the sample was made of a copper alloy containing Al and Mg, but had a small surface contact angle of 90°, and had a low Faraday efficiency of ethanol production of 0.35%.

[0066] In contrast, in Examples 1 to 20 of the present invention, the copper alloy contains one or more alloy elements selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and the Cu content is 50 atomic % or more. The contact angle on the surface is 95° or more, and the ethanol production efficiency is high at 0.86% or more. ２ It was possible to efficiently produce ethanol by reducing

[0067] From the results of the above confirmation experiments, it can be seen that the present invention is made of a bulk material that is easy to handle, and has high Faraday efficiency and can produce CO ２ It has been confirmed that it is possible to provide a copper alloy catalyst capable of producing organic compounds of C2 or more from the above.

[0068] According to the present invention, a CO 2 -emitting element is made of a bulk material that is easy to handle and has high Faraday efficiency. ２ It is possible to provide a copper alloy catalyst capable of producing organic compounds of C2 or more from

[0069] 10 Copper alloy catalyst 30 Electrochemical reaction device 31 Electrolysis cell 32 Anode electrode 33 Cathode electrode 34 Ion-permeable membrane 35, 36 Catalyst layer

Claims

1. A copper alloy catalyst comprising a bulk material of a copper alloy containing one or more alloying elements selected from Zn, Al, Ca, Mg, Ni, Si, Mn, In, Fe, Co, Ag, and Sn, and with a Cu content of 50 atomic % or more, wherein when a droplet of ion-exchanged water is dropped onto the surface of the bulk material, the contact angle measured by the θ / 2 method is 95° or more.

2. The copper alloy catalyst according to claim 1, characterized in that the developed surface area ratio Sdr of the bulk material is 1% or more.

3. 5000μm by EBSD method ２ The copper alloy catalyst according to claim 1, characterized in that the average KAM value is 0.30° or more when the above measurement areas are measured at measurement intervals of 0.1 μm and measurement points having a CI value of 0.1 or less analyzed by data analysis software OIM are excluded.

4. A copper alloy catalyst as described in claim 1, characterized in that it contains 2 atomic % or more of one or more alloying elements selected from Zn, Al, Ca, and Mg, and the surface layer of the bulk material is a surface treatment layer treated with an acid or basic solution.

5. The copper alloy catalyst according to claim 1, characterized in that the Faraday efficiency of ethanol production is 0.8% or more.

6. An electrochemical reaction device using the copper alloy catalyst according to any one of claims 1 to 5.

Images