Method for producing metal composite particle support

Abstract

To provide a method of producing a metal composite-particle carried body that allows for sufficiently suppressing the aggregation of metal composite particles after the metal composite particles have been carried by a carrier.SOLUTION: A method of producing a metal composite-particle carried body includes: a step 1 of obtaining a first reaction liquid by mixing a solution containing a first metal compound having a first metal element as a constituent element and a solution containing a first reducer; a step 2 of obtaining a mixture liquid by mixing a first reaction liquid and a solution containing a second metal compound having a second metal element as a constituent element, the second metal element being different from the first metal element; and a step 3 of obtaining a metal composite-particle carried body by using the mixture liquid, a solution containing a second reducer and a dispersion liquid containing a carrier and allowing the carrier to carry a metal composite particle, wherein the steps 1, 2 and 3 are carried out in a micro-reactor system comprising a plurality of micro-mixers.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for producing a metal composite particle carrier and a composition.

Background Art

[0002] A method of obtaining core-shell type nanoparticles by sequentially mixing two types of metal compounds and a reducing agent solution using a micromixer is known. In Patent Document 1, a technique for suppressing aggregation of metal composite particles is proposed by setting the time from the start of supply of each solution to the first micromixer to the outflow of the dispersion from the liquid outlet of the third micromixer to 0.001 to 6 seconds. Further, it has been proposed to produce a metal composite particle carrier by collecting and mixing the produced metal composite particles in a receiving container in which the carrier is being stirred.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the production method of Patent Document 1, it is possible to reduce a protective agent unnecessary for exerting the function of the metal composite particles. On the other hand, it is difficult to support the metal composite particles on the carrier while maintaining a good dispersion state. As a factor, it is considered that the metal composite particles come into contact with each other and aggregate before the metal composite particles come into contact with the carrier. Further, in the production method of Patent Document 1, since the metal composite particles are continuously mixed with the carrier in the receiving container, the amount of the carrier supported changes over time. For this reason, there is a situation that it is difficult to continuously produce metal composite particle carriers having the same composition.

[0005] Therefore, the present disclosure provides a method for manufacturing a metal composite particle carrier capable of sufficiently suppressing aggregation of metal composite particles after the metal composite particles are supported on a carrier. Further, the present disclosure provides a composition containing a metal composite particle carrier in which aggregation of the metal composite particles supported on the carrier is sufficiently suppressed.

Means for Solving the Problems

[0006] In one aspect, the present disclosure includes Step 1 of obtaining a first reaction solution by mixing a solution containing a first metal compound having at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) as a constituent element and a solution containing a first reducing agent; Step 2 of obtaining a mixed solution by mixing the first reaction solution and a solution containing a second metal compound having at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) as a constituent element, wherein the second metal element is different from the first metal element; and Step 3 of obtaining a metal composite particle carrier by supporting metal composite particles on a carrier using the above mixed solution, a solution containing a second reducing agent, and a dispersion containing the carrier. The present disclosure provides a method for manufacturing a metal composite particle carrier, wherein Steps 1, 2, and 3 are performed in a microreactor system including a plurality of micromixers.

[0007] In the above manufacturing method, the synthesis of metal composite particles and the loading onto the carrier are carried out in a microreactor system equipped with a plurality of micromixers. Therefore, each step can be carried out continuously and rapidly, and a metal composite particle carrier can be continuously manufactured. Since such continuous production is possible, the metal composite particle carrier can be mass-produced on an industrial scale.

[0008] In step 3 of the above manufacturing method, the generation of metal composite particles and the loading onto the carrier proceed rapidly. Since the aggregation of the metal composite particles is sufficiently suppressed by loading onto the carrier, in the metal composite particle-supported body thus obtained, the metal composite particles are supported on the carrier while maintaining high dispersibility.

[0009] Step 3 includes step 3-1 of mixing the above mixed solution and a solution containing a second reducing agent to obtain a second reaction solution containing metal composite particles, and step 3-2 of mixing the second reaction solution and a dispersion containing a carrier to obtain a metal composite particle-supported body. It is preferable that the residence time from when the mixed solution and the solution containing the second reducing agent merge until the second reaction solution and the dispersion containing the carrier merge is 5.99 seconds or less. Thereby, the aggregation of the metal composite particles contained in the second reaction solution before being supported on the carrier (before merging into the dispersion) can be further suppressed. Therefore, the dispersibility of the metal composite particles after being supported on the carrier can be sufficiently maintained.

[0010] It is preferable to alternately repeat step 2 and step 3-1 one or more times by using the second reaction solution obtained in step 3-1 instead of the first reaction solution in step 2. Thereby, the number of metal species contained in the metal composite particles can be increased.

[0011] In step 3 above, it is preferable to use one micromixer to simultaneously mix the mixed solution, the solution containing the second reducing agent, and the dispersion containing the carrier to obtain a metal composite particle-supported body. With such a manufacturing method, the number of micromixers used can be reduced, and the equipment can be simplified. In addition, since the generation of metal composite particles and the loading onto the carrier can be carried out simultaneously, the aggregation of the metal composite particles can be further suppressed.

[0012] In one aspect, the present disclosure provides a method for manufacturing a metal composite particle support, including: Step 1 of obtaining a first reaction solution by mixing a solution containing a first metal compound having, as a constituent element, at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), and a solution containing a first reducing agent; Step 2A of obtaining a mixture by mixing the first reaction solution and a solution containing a second reducing agent; and Step 3A of obtaining a metal composite particle support by using the mixture, a solution containing a second metal compound having, as a constituent element, at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), where the second metal element is different from the first metal element, and a dispersion containing a carrier to support metal composite particles on the carrier. Step 1, Step 2A, and Step 3A are carried out in a microreactor system equipped with a plurality of micromixers.

[0013] In the above manufacturing method, the synthesis of metal composite particles and their loading onto the carrier are carried out in a microreactor system equipped with a plurality of micromixers. Therefore, each step can be carried out continuously and rapidly, and a metal composite particle support can be continuously manufactured. Since such continuous production is possible, the metal composite particle support can be mass-produced on an industrial scale.

[0014] In Step 3 of the above manufacturing method, the generation of metal composite particles and their loading onto the carrier proceed rapidly. Since the aggregation of metal composite particles is sufficiently suppressed by loading onto the carrier, in the metal composite particle support thus obtained, the metal composite particles are supported on the carrier while maintaining high dispersibility.

[0015] Step 3A includes Step 3A-1 of mixing the above mixed solution and a solution containing a second metal compound to obtain a second reaction solution containing metal composite particles, and Step 3A-2 of mixing the second reaction solution and a dispersion containing a carrier to obtain a metal composite particle carrier. It is preferable that the residence time from when the mixed solution and the solution containing the second metal compound merge until the second reaction solution and the dispersion containing the carrier merge is 5.99 seconds or less. Thereby, aggregation of the metal composite particles contained in the second reaction solution before being supported on the carrier (before merging into the dispersion) can be further suppressed. Therefore, the dispersibility of the metal composite particles after being supported on the carrier can be sufficiently maintained.

[0016] It is preferable to alternately repeat Step 2A and Step 3A-1 one or more times by using the second reaction solution obtained in Step 3A-1 instead of the first reaction solution in Step 2A. Thereby, the number of metal species contained in the metal composite particles can be increased.

[0017] In the above Step 3A, it is preferable to use one micromixer and simultaneously mix the above mixed solution, the solution containing the second metal compound, and the dispersion containing the carrier to obtain a metal composite particle carrier. With such a manufacturing method, the number of micromixers used can be reduced to simplify the equipment. In addition, since the generation of metal composite particles and the support on the carrier can be carried out simultaneously, aggregation of the metal composite particles can be further suppressed.

[0018] The content of the carrier in the dispersion may be 0.1 to 5% by mass. Thereby, while maintaining the fluidity of the dispersion, the contact frequency between the carrier and the metal composite particles contained in the dispersion can be maintained at a sufficiently high level.

[0019] The first reducing agent and the second reducing agent may contain at least one selected from the group consisting of hydrazine compounds, boron hydride compounds, and organic carboxylic acid compounds. Thereby, metal composite particles can be generated with a sufficiently high yield. Therefore, the amount of the metal composite particles supported on the metal composite particle carrier can be made sufficiently large.

[0020] The first metal compound and the second metal compound may each contain only one kind of the first metal element and the second metal element selected from gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re). Thereby, a metal composite particle support useful in various fields such as, for example, a catalyst can be produced.

[0021] The loading amount of the metal composite particles in the metal composite particle support is preferably 0.01 to 50% by mass. Thereby, a metal composite particle support useful in various fields such as, for example, a catalyst can be obtained.

[0022] The composition according to one aspect of the present disclosure includes a metal composite particle support obtained by any of the above-described production methods. The above composition contains a metal composite particle support in which aggregation of the metal composite particles is sufficiently suppressed. Therefore, high performance can be exhibited, for example, in applications such as a catalyst.

[0023] The composition according to one aspect of the present disclosure contains a metal composite particle support including metal composite particles having a core-shell structure in which the composition of the core portion and the shell portion are different from each other and containing two or more metals selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), and a carrier for supporting the metal composite particles, wherein the average particle diameter of the metal composite particles is 1.0 to 15 nm, and the electrochemical surface area is 105 to 200 m 2 / g-Pt, and provides a composition.

[0024] The above composition contains a metal composite particle carrier on which metal composite particles having a predetermined average particle diameter and having a core-shell structure with different compositions of the core part and the shell part are supported. Since such a composition has a sufficiently large electrochemical surface area, aggregation of the metal composite particles in the metal composite particle carrier is sufficiently suppressed. Therefore, high performance can be exhibited, for example, in applications such as catalysts.

[0025] The loading amount of the metal composite particles in the above metal composite particle carrier may be 0.01 to 50% by mass. Such a composition is useful in various fields such as, for example, catalysts.

Effects of the Invention

[0026] It is possible to provide a method for producing a metal composite particle carrier capable of sufficiently suppressing aggregation of the metal composite particles after the metal composite particles are supported on the carrier. In addition, a composition containing a metal composite particle carrier in which aggregation of the metal composite particles supported on the carrier is sufficiently suppressed can be provided.

Brief Description of the Drawings

[0027]

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Modes for Carrying Out the Invention

[0028] Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings as appropriate. However, the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following content. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant descriptions may be omitted as appropriate. Also, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the respective elements are not limited to the ratios shown in the drawings.

[0029] [Method for manufacturing metal composite particle carrier (Embodiment 1)] The method for manufacturing a metal composite particle carrier according to one embodiment includes the following steps 1, 2, and 3. In this manufacturing method, a metal composite particle carrier can be manufactured by the following procedure using a microreactor system including a plurality of micromixers. The shapes and sizes of the plurality of micromixers may be the same as each other or different from each other.

[0030] (Step 1) A first reaction solution is obtained by mixing a solution containing a first metal compound having at least one first metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) as a constituent element, and a solution containing a first reducing agent.

[0031] (Step 2) The first reaction solution obtained in Step 1 is mixed with a solution containing a second metal compound having at least one second metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) as a constituent element to obtain a mixed solution. However, the second metal element contained as a constituent element in the second metal compound is different from the first metal element contained as a constituent element in the first metal compound.

[0032] (Step 3) The mixed solution obtained in Step 2, the solution containing the second reducing agent, and the dispersion containing the carrier are mixed sequentially or simultaneously to obtain a metal composite particle-supported carrier in which the metal composite particles are supported on the carrier. When mixing sequentially, Step 3 may include Step 3-1 of mixing the mixed solution and the solution containing the second reducing agent to obtain a second reaction solution containing metal composite particles, and Step 3-2 of mixing the second reaction solution and the dispersion containing the carrier to obtain a metal composite particle-supported carrier.

[0033] In all of Steps 1 to 3, it is not necessary to use a protective agent having a function of maintaining the dispersed state of the metal composite particles in the solvent. However, the case of using a protective agent is not excluded. Total time T A is preferably from 0.001 second to 6 seconds.

[0034] The total time T in this embodiment A is defined as follows. When the mixed solution obtained in Step 2, the solution containing the second reducing agent, and the dispersion containing the carrier are mixed simultaneously, the total time T A is the time from when the solution containing the first metal compound and the solution containing the first reducing agent merge until the mixed solution obtained in Step 2, the solution containing the second reducing agent, and the dispersion containing the carrier merge. When the mixed solution obtained in Step 2, the solution containing the second reducing agent, and the dispersion containing the carrier are mixed sequentially, the total time T A is the time from when the solution containing the first metal compound and the solution containing the first reducing agent merge until the second reaction solution and the dispersion containing the carrier merge.

[0035] According to the number of metal species contained in the metal composite particles of the metal composite particle support to be manufactured, between step 3-1 and step 3-2, step 2 and step 3-1 may be repeated one or more times again. When performing step 2 again, the second reaction solution obtained in step 3-1 may be used instead of the first reaction solution obtained in step 1. Further, in the second step 2, a solution containing a third metal compound having at least one third metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) as a constituent element may be mixed with the second reaction solution obtained in step 3-1 to obtain a mixed solution. The third step 2 can be performed in the same manner.

[0036] Each term in this embodiment will be described below. The meaning content of each term is applicable not only to this embodiment but also to other embodiments and each modification.

[0037] <Metal composite particles> Metal composite particles are metal nanoparticles that contain multiple types of metals in one particle and the multiple types of metals are complexed at the nanolevel. The multiple types of metals are the metal species in the first metal compound and the second metal compound described later. Note that in the present disclosure, metal particles and metal nanoparticles include both cases where they are composed of multiple metals and cases where they are composed of a single metal.

[0038] Nanoparticles (metal nanoparticles) refer to particles with a particle diameter of 0.1 nm or more and less than 1000 nm, and the substance constituting the nanoparticles is not limited to a single type and may be a composite composed of multiple compounds, for example, multiple metal compounds.

[0039] <First metal compound, second metal compound> The first metal compound used in Step 1 and the second metal compound used in Step 2 are each a compound containing, as a constituent element, at least one metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re).

[0040] The metal compounds used in Step 1 and Step 2 may contain two or more metals as long as it is possible to mix a metal-containing solution and a reducing agent before the nanoparticles aggregate.

[0041] There is no particular limitation on the Au compound. For example, inorganic Au compounds such as gold iodide, gold bromide, gold chloride, gold hydroxide, gold oxide, sodium chloroaurate, tetrachloroauric acid or its hydrate, ammonium tetrachloroaurate or its hydrate, lithium tetrachloroaurate or its hydrate; organic Au compounds such as gold cyanide, potassium gold cyanide, gold acetate, etc. Among these, gold chloride, tetrachloroauric acid hydrate, lithium tetrachloroaurate hydrate, etc. are preferable. The above Au compounds may be used alone or in combination of two or more.

[0042] There is no particular limitation on the Ag compound. For example, inorganic Ag compounds such as silver iodide, silver bromide, silver chloride, silver sulfite, silver phosphate, silver oxide, silver chromate, silver dichromate, disilver(I) tungstate, silver chlorite, silver nitrate, silver bromate, silver sulfate; organic Ag compounds such as silver thiocyanate, silver carbonate, etc. The above Ag compounds may be used alone or in combination of two or more.

[0043] The Cu compound is not particularly limited, and examples thereof include inorganic Cu compounds such as cuprous chloride, cuprous bromide, cuprous iodide, cupric chloride, cupric bromide, copper(II) sulfate, copper(II) nitrate, tetraamminecopper(II) sulfate, etc.; and organic Cu compounds such as cuprous cyanide, copper acetylacetonate, cupric acetate, copper oleate, etc. Among these, cupric chloride, copper(II) sulfate, copper(II) nitrate, etc. are preferable. The above-mentioned Cu compounds may be used alone or in combination of two or more.

[0044] The Pt compound is not particularly limited, and examples thereof include inorganic Pt compounds such as platinum oxide, platinum chloride, platinum bromide, platinum iodide, dihydrogen hexachloroplatinate(IV), sodium hexachloroplatinate(IV), potassium hexachloroplatinate(IV), sodium tetrachloroplatinate(II), potassium tetrachloroplatinate(II), ammonium hexabromoplatinate(IV), potassium tetrabromoplatinate(II), potassium hexaiodoplatinate(IV), ammonium tetrachloroplatinate(II), dihydrogen hexahydroxyplatinate(IV), sodium hexahydroxyplatinate(IV), tetraammineplatinum(II) hydroxide, potassium hexacyanoplatinate(IV), etc.; and organic Pt compounds such as complexes of chloroplatinic acid and olefins such as ethylene. Among these, dihydrogen hexachloroplatinate(IV), potassium hexachloroplatinate(IV), potassium tetrachloroplatinate(II) are preferable. The above-mentioned Pt compounds may be used alone or in combination of two or more.

[0045] The Ir compound is not particularly limited, and examples thereof include inorganic Ir compounds such as iridium chloride, iridium bromide, iridium iodide, (NH4)2IrCl6, IrCl3, H2IrCl6, etc.; and organic Ir compounds such as [Ir(CO)2Cl2]2, Li[Ir(CO)2I2], [Ir(CO)2I]2, IrCl(CO)(PPh3)2, [Ir(cod)Cl]2, iridium(II) acetate, dicarbonylacetylacetonatoiridium, etc. The above-mentioned Ir compounds may be used alone or in combination of two or more.

[0046] There are no particular restrictions on the Os compound. For example, inorganic Os compounds such as osmium chloride and osmium bromide; organic Os compounds such as osmium acetate and the like can be mentioned. Only one kind of the above-mentioned Os compound may be used, or two or more kinds may be used in combination.

[0047] There are no particular restrictions on the Pd compound. For example, palladium complexes such as palladium(II) acetylacetonate, palladium(II) hexafluoroacetylacetonate, tetraamminepalladium(II) chloride, bis(triphenylphosphine)palladium(II) dichloride, bis(benzonitrile)palladium(II) chloride; palladium halides such as palladium(II) chloride, palladium(II) bromide, palladium(II) iodide; carboxylic acid palladiums such as palladium(II) acetate, palladium(II) trifluoroacetate, palladium(II) propionate, palladium(II) pivalate, palladium(II) stearate, palladium(II) benzoate, palladium(II) carbonate, palladium(II) nitrate, palladium(II) sulfate, ammonium tetrachloropalladate(II), sodium tetrachloropalladate(II), potassium tetrachloropalladate(II) and other palladium inorganic salts can be mentioned. Among these, ammonium tetrachloropalladate(II), sodium tetrachloropalladate(II), and potassium tetrachloropalladate(II) are particularly preferred, and sodium tetrachloropalladate(II) and potassium tetrachloropalladate(II) are more preferred. Only one kind of the above-mentioned palladium compound may be used, or two or more kinds may be used in combination.

[0048] There are no particular restrictions on the Rh compound. For example, inorganic Rh compounds such as rhodium chloride, rhodium bromide, and rhodium iodide; organic Rh compounds such as [Rh(CO)2Cl2]2, Li[Rh(CO)2I2], [Rh(CO)2I]2, RhCl(CO)(PPh3)2, [Rh(cod)Cl]2, rhodium(II) acetate, and dicarbonylacetylacetonatorhodium can be mentioned. Only one of the above Rh compounds may be used, or two or more thereof may be used in combination.

[0049] There are no particular restrictions on the Ru compound. For example, inorganic Ru compounds such as ruthenium chloride, ruthenium bromide, and ruthenium iodide; organic Ru compounds such as RuCl2(DMSO)4, [Ru(cod)Cl2]n, [Ru(nbd)Cl2]n, (cod)Ru(2-methallyl)2, [Ru(benzene)Cl2]2, [Ru(benzene)Br2]2, [Ru(benzene)I2]2, [Ru(p-cymene)Cl2]2, [Ru(p-cymene)Br2]2, [Ru(p-cymene)I2]2, [Ru(mesitylene)Cl2]2, [Ru(mesitylene)Br2]2, [Ru(mesitylene)I2]2, [Ru(hexamethylbenzene)Cl2]2, [Ru(hexamethylbenzene)Br2]2, [Ru(hexamethylbenzene)I2]2, RuCl2(PPh3)3, RuBr2(PPh3)3, RuI2(PPh3)3, RuH4(PPh3)3, RuClH(PPh3)3, RuH(OAc)(PPh3)3, and RuH2(PPh3)4 can be mentioned. In the examples, DMSO represents dimethyl sulfoxide, cod represents 1,5-cyclooctadiene, nbd represents norbornadiene, and Ph represents a phenyl group, respectively. Only one of the above Ru compounds may be used, or two or more thereof may be used in combination.

[0050] The Fe compound is not particularly limited. For example, inorganic Fe compounds such as ferrous oxide, ferric oxide, magnetite, iron(II) chloride, iron(III) chloride, iron(II) sulfate, iron(III) sulfate, iron selenide, iron(III) tungstate oxide, iron titanate trioxide, diiron titanate pentoxide, iron nitride, iron disulfide, iron(II) vanadate, iron boride, diiron boride, iron iodide, iron phosphide, diiron phosphide, potassium ferrocyanide, potassium ferricyanide, etc.; iron alkoxides such as iron(II) methoxide, iron(III) methoxide, iron(III) ethoxide, iron(II) propoxide, iron pentacarbonyl, iron(II) acetate, iron(III) stearate, iron(III) laurate, iron(II) acetylacetonate, iron(III) acetylacetonate, iron(II) 2-ethylhexanoate, etc. Among these, iron(III) chloride, iron(II) sulfate, and iron(III) sulfate are preferred. The above-mentioned Fe compounds may be used alone or in combination of two or more.

[0051] The Co compound is not particularly limited. For example, inorganic Co compounds such as cobalt(II) acetate, cobalt(II) chloride, cobalt(II) bromide, cobalt(II) iodide, cobalt(II) fluoride, cobalt(III) fluoride, cobalt(II) carbonate, cobalt(II) cyanide, and their hydrates; organic Co compounds such as sodium tris(carbonato)cobaltate(III), cobalt(II) acetylacetonate hydrate, cobalt(III) acetylacetonate, etc. The above-mentioned Co compounds may be used alone or in combination of two or more.

[0052] The Ni compound is not particularly limited. For example, inorganic Ni compounds such as nickel dichloride (nickel(II) chloride), nickel dibromide (nickel(II) bromide), nickel(II) carbonate, etc.; organic Ni compounds such as nickel acetate(II), etc. The above-mentioned Ni compounds may be used alone or in combination of two or more.

[0053] The Cr compound is not particularly limited, and examples thereof include inorganic Cr compounds such as chromium chloride, chromium bromide, chromium sulfate, and chromium oxide; and organic Cr compounds such as chromium acetate, chromium propionate, chromium 2-ethylhexanoate, chromium acrylate, chromium methacrylate, and chromium acetylacetonate. Only one of the above-mentioned Cr compounds may be used, or two or more thereof may be used in combination.

[0054] The Zn compound is not particularly limited, and examples thereof include inorganic Zn compounds such as zinc oxide, zinc sulfide, zinc chloride, zinc bromide, zinc sulfate, and zinc nitrate; and organic Zn compounds such as zinc acetate, zinc formate, and zinc acetylacetonate. Only one of the above-mentioned Zn compounds may be used, or two or more thereof may be used in combination.

[0055] The Re compound includes inorganic Re compounds such as rhenium chloride, rhenium bromide, oxyhalogenated rhenium, rhenate, and perrhenate; and organic Re compounds such as rhenium acetate. Only one of the above-mentioned Re compounds may be used, or two or more thereof may be used in combination.

[0056] Furthermore, the first metal compound and the second metal compound are not particularly limited as long as they are compounds having the above metal elements as constituent elements. From the viewpoint of efficiently producing metal composite particles, the first metal compound and the second metal compound are preferably metal salts or metal complexes. Specifically, as the metal salt, halides such as chlorides, bromides, and iodides, hydroxides, sulfides, sulfates, nitrates, carbonates, acetates, potassium composite oxides, ammonium composite oxides, sodium composite oxides, and other composite oxides are preferably used. As the complex of the above noble metal, ammine complexes, cyano complexes, halogeno complexes, hydroxy complexes, etc. are preferably used. Among them, halides, sulfates, and nitrates are preferably used because they are easily available industrially and have high solubility in water.

[0057] As the first metal compound, preferably, it is a metal compound having at least one metal element selected from the group consisting of gold, silver, copper, platinum, palladium, iron, cobalt, and nickel as constituent elements. More preferably, it is a metal compound having at least one metal element selected from the group consisting of gold, copper, platinum, palladium, iron, and nickel as constituent elements. Even more preferably, it is a metal compound having at least one metal element selected from the group consisting of gold, copper, platinum, palladium, and iron as constituent elements. Even more preferably, it is a metal compound having at least one metal element selected from the group consisting of gold, platinum, and palladium as constituent elements. Particularly preferably, it is a palladium compound having palladium as a constituent element.

[0058] As the second metal compound, preferably, it is a metal compound having at least one metal element selected from the group consisting of palladium, gold, silver, copper, platinum, iridium, osmium, rhodium, ruthenium, cobalt, nickel, chromium, zinc, and rhenium as constituent elements. More preferably, it is a metal compound having at least one metal element selected from the group consisting of palladium, gold, silver, copper, platinum, iridium, osmium, rhodium, ruthenium, chromium, zinc, and rhenium as constituent elements. Even more preferably, it is a metal compound having at least one metal element selected from the group consisting of palladium, gold, and platinum as constituent elements. Even more preferably, it is a metal compound having at least one metal element selected from the group consisting of palladium and platinum as constituent elements. Particularly preferably, it is a platinum compound having platinum as a constituent element. However, the second metal compound contains a metal element different from that of the first metal compound as a constituent element. The second metal compound preferably does not contain a metal element common to the first metal compound.

[0059] The first metal compound and the second metal compound may each be a mixture of a plurality of metal compounds.

[0060] From the above, as suitable first metal compounds, potassium tetrachloropalladate (K2PdCl4), chloroauric(III) acid (HAuCl4) or its hydrate, copper(II) sulfate (CuSO4), iron(II) sulfate (FeSO4) can be mentioned. As suitable second metal compounds, chloroauric(III) acid (HAuCl4) or its hydrate, hydrogen hexachloroplatinate(IV) (H2PtCl6) can be mentioned.

[0061] The solvent used for the solution containing each metal compound is not particularly limited as long as it does not inhibit the production of the metal composite particle carrier. From the viewpoint of improving the solubility of each metal compound and the stability of the metal compound in each solution, water, aliphatic alcohols, and ethers are preferable.

[0062] <Reducing agent> As the reducing agent (the first reducing agent and the second reducing agent), as long as the above first metal compound and second metal compound can be reduced to the 0-valent metal respectively, the type thereof is not particularly limited, and a known reducing agent can be used. The first reducing agent and the second reducing agent may be the same or different from each other.

[0063] For example, hydrazine compounds (e.g., hydrazine, hydrazine hydrochloride, hydrazine sulfate, hydrazine hydrate, phenylhydrazine), boron hydride compounds (e.g., tetrabutylammonium borohydride (TBAB), tetraethylammonium borohydride (TEAB), sodium borohydride, potassium borohydride, lithium borohydride, sodium triethylborohydride, potassium triethylborohydride, lithium triethylborohydride, sodium cyanoborohydride), borane complexes (e.g., borane·tert-butylamine complex, borane·tetrahydrofuran complex), organic carboxylic acid compounds (citric acid, trisodium citrate dihydrate, oxalic acid, sodium oxalate, sodium acetate), triethylsilane, sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium nitrite, sodium hyponitrite, phosphorous acid, sodium phosphite, hypophosphorous acid, sodium hypophosphite, aldehydes, alcohols, amines, saccharides, etc. can be mentioned. From the viewpoint of industrially preferably reducing the metal compound, it is preferable that both the first metal compound and the second metal compound contain at least one selected from the group consisting of hydrazine compounds, boron hydride compounds, and organic carboxylic acid compounds. These reducing agents may be used alone or in combination of two or more kinds.

[0064] Specifically, as the reducing agent, it is preferable to use at least one selected from the group consisting of hydrazine, sodium borohydride, potassium borohydride, and citric acid, and it is more preferable to use at least one selected from the group consisting of hydrazine and sodium borohydride.

[0065] Note that among these reducing agents, some have too high reactivity with water. Therefore, a solvent other than water (for example, an aprotic polar solvent such as tetrahydrofuran, diglyme, N,N-dimethylformamide, dimethyl sulfoxide, etc.) may be used as a solvent and used as a solution. By using such a solvent, decomposition of the reducing agent can be suppressed. Further, for the purpose of reducing the amount of the solvent used and reducing the amounts of water and the solvent used, the reducing agent may be dissolved in the above-mentioned aprotic polar solvent in advance before Step 1 and mixed with water immediately before the reaction. The mixing may be a microflow process using a micromixer (microreactor) or a batch process.

[0066] The amount of the reducing agent used is not particularly limited. In terms of allowing the reduction to proceed sufficiently and obtaining metal composite particles with a smaller primary particle diameter, it may be 100 mol% to 800 mol%, and may also be 150 mol% to 400 mol% with respect to the molar amounts of the first metal compound and the second metal compound to be reduced, respectively.

[0067] <Protecting agent> It is not necessary to use a protective agent for suppressing aggregation of the metal composite particles. Here, the protective agent is a substance that adsorbs on the surface of the metal nanoparticles, suppresses aggregation between the metal nanoparticles, and functions as a dispersant capable of maintaining the dispersed state in a solvent. When using a protective agent, specific examples of the protective agent include known ones described below. For example, low molecular weight dispersants such as alkylamines, alkanethiols, and alkanediols, and polymer-type dispersants having various functional groups can be mentioned. As the polymer-type dispersant, for example, styrene-based resins (styrene-(meth)acrylic acid copolymers, styrene-maleic anhydride copolymers, etc.), acrylic-based resins ((meth)acrylic acid methyl-(meth)acrylic acid copolymers, (meth)acrylic acid-based resins such as poly(meth)acrylic acid, etc.), water-soluble urethane resins, water-soluble acrylic urethane resins, water-soluble epoxy resins, water-soluble polyester-based resins, cellulose derivatives (nitrocellulose; alkyl celluloses such as ethyl cellulose, alkyl-hydroxyalkyl celluloses such as ethyl hydroxyethyl cellulose, hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose, carboxyalkyl celluloses such as carboxymethyl cellulose, etc., such as cellulose ethers), polyvinyl alcohol, polyalkylene glycols (liquid polyethylene glycol, polypropylene glycol, etc.), natural polymers (polysaccharides such as gelatin, dextrin, gum arabic, casein, etc.), polyethylene sulfonic acid or its salts, polystyrene sulfonic acid or its salts, formalin condensates of naphthalene sulfonic acid, nitrogen atom-containing polymer compounds [for example, polyalkyleneimines (such as polyethyleneimine), polyvinylpyrrolidone, polyallylamine, polyether polyamines (such as polyoxyethylene polyamine, etc.), etc., polymer compounds having amino groups], etc. can be mentioned, and polyvinylpyrrolidone, etc. may be preferably used.

[0068] <Carrier> The carrier used when obtaining the metal composite particle support is not particularly limited as long as it is generally used as a carrier for solid catalysts. For example, it may be either an inorganic compound or an organic compound. Examples of the carrier include metal oxides such as nickel oxide, zinc oxide, iron oxide, cobalt oxide, manganese dioxide, copper oxide, silicon oxide, tin oxide, aluminum oxide (α-Al2O3, γ-Al2O3), barium oxide, titanium oxide, vanadium oxide, tungsten oxide, molybdenum oxide, niobium oxide, tantalum oxide, cerium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, magnesium oxide, beryllium oxide, chromium oxide, scandium oxide, cadmium oxide, and indium oxide, or composite oxides combining these metal oxides; activated carbon; carbon black; organic polymers; zeolites; mesoporous silicates; clays; diatomaceous earth; pumice, etc. The carrier preferably has a high specific surface area in order to support the high dispersion of the metal composite particles. When a carrier with a high specific surface area is used, the catalyst life tends to be prolonged or the reaction rate tends to increase. These carriers may be used alone or in combination of two or more. Among the above carriers, aluminum oxide, titanium oxide, zirconium oxide, silica gel, and activated carbon are preferred, more preferably activated carbon, γ-Al2O3, α-Al2O3, and silica gel, and even more preferably activated carbon. Note that a carrier supporting metal composite particles may be used for the purpose of adjusting the loading amount within the range described below.

[0069] The loading amount of the metal composite particles on the above carrier is preferably 0.01 to 50% by mass, more preferably 0.1 to 15% by mass, and even more preferably 1 to 10% by mass with respect to the entire metal composite particle support. By setting the loading amount of the metal composite particles within the above range, aggregation of the metal composite particles can be suppressed, and a metal composite particle support having a monodisperse particle size distribution can be produced.

[0070] In order to make the loading amount of the metal composite particles within the above range, for the total amount of the mass in terms of metal in the first metal compound and the mass in terms of metal in the second metal compound used in Steps 1 to 3, the carrier is preferably used in an amount of 1.7 g to 100,000 g, more preferably 2.5 g to 10,000 g, and still more preferably 10 g to 100 g, per 1 g of the total amount.

[0071] <Solvent of the dispersion liquid> The solvent used for the dispersion liquid of the carrier is not particularly limited as long as it does not inhibit the production of the metal composite particle carrier. Examples include water, alcohols (e.g., methanol, ethanol, isopropyl alcohol, t-butyl alcohol, ethylene glycol, triethylene glycol, etc.), ketones (e.g., acetone, butanone, cyclohexanone), aliphatic hydrocarbons (e.g., n-pentane, n-hexane, n-heptane, cyclohexane, etc.), ethers (e.g., diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, 1,2-methylenedioxybenzene, etc.), aromatic hydrocarbons (e.g., benzene, toluene, xylene, etc.), halogenated aromatic hydrocarbons (e.g., chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, etc.), nitrated aromatic hydrocarbons (e.g., nitrobenzene, etc.), halogenated hydrocarbons (e.g., methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, etc.), carboxylic acid esters (e.g., methyl formate, ethyl acetate, propyl acetate, butyl acetate, etc.). These solvents may be used alone or in a mixture of two or more.

[0072] Among these, water, aliphatic alcohols, and ethers are preferred in order to improve the dispersibility of the carrier, etc.

[0073] Among the aliphatic alcohols, aliphatic alcohols having a hydroxyl group of 1 to 3 valences are more preferred, and aliphatic alcohols having 1 to 4 carbon atoms are still more preferred. Specifically, methanol, ethylene glycol, glycerin, 2-methoxyethanol, and diethylene glycol can be mentioned.

[0074] As the aliphatic ethers, alkyl ethers having 1 to 8 carbon atoms are preferred. Specifically, diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran and the like can be mentioned.

[0075] Among the above solvents, water, methanol, ethylene glycol, diethyl ether, tetrahydrofuran, and methyl formate are preferred, and ethanol is more preferred.

[0076] <Microreactor system> There is no particular limitation on the structure of the microreactor system used in the production method of the present disclosure. It preferably has a plurality of fluid introduction channels having a fine cross-sectional shape for introducing at least five kinds of fluids, a plurality of micromixers having a fine cross-sectional shape connected to the fluid introduction channels for mixing and reacting the five kinds of introduced fluids with each other, and a plurality of fluid discharge channels having a fine cross-sectional shape for discharging the reaction product liquid from these micromixers. The number of fluid introduction channels, the number of micromixers, and the number of fluid discharge channels are appropriately adjusted according to the types of metal compounds and reducing agents to be mixed.

[0077] In the above micromixer, a plurality of kinds of fluids are mixed. The liquid is temperature-controlled to a desired temperature in the micromixer and the liquid discharge channel.

[0078] In the manufacturing method of the present disclosure, all of the continuously performed steps 1 to 3 are performed using a microreactor system equipped with a micromixer, and the fluid outlet channel of the micromixer in the upstream step and the fluid inlet channel of the micromixer in the subsequent downstream step are preferably connected to each other by a capillary connecting tube. By doing so, in the micromixer, the mixture mixed with each other is temperature-controlled to a desired temperature in the micromixer and in the fluid outlet channel. In the micromixer, the fluid outlet channel, and the capillary tube, a desired reaction proceeds to completion. The capillary connecting tube is preferably provided with means for adjusting the temperature of the fluid flowing through it to a desired value, such as a thermostatic bath, a temperature control jacket, or the like.

[0079] In the microreactor system used in the manufacturing method of the present disclosure, the areas of the cross-sections (radial cross-sections) of the fluid inlet channel, the micromixer, and the fluid outlet channel are preferably all 0.7 μm 2 ~10 mm 2 and more preferably 0.08 mm 2 ~2 mm 2 The aspect ratio of the major axis / minor axis of the cross-section may be 1 or more. The major axis and minor axis in each cross-section are preferably in the range of 1 μm to 4 mm, and more preferably 25 μm to 2 mm.

[0080] <Example of the manufacturing method of the metal composite particle support> FIG. 1 is a diagram for explaining an example of a method for manufacturing metal composite particles. This manufacturing method has steps 1, 2, 3-1, and 3-2. It is not necessary to use a protective agent for the purpose of preventing aggregation of metal composite particles in all steps.

[0081] FIG. 2 is a schematic diagram showing an example of a microreactor system used in the manufacturing method of the metal composite particle support of FIG. 1. The microreactor system 100 in FIG. 2 includes a first micromixer 13a, a second micromixer 13b, a third micromixer 13c, and a fourth micromixer 13d in this order from the upstream side to the downstream side.

[0082] The first micromixer 13a is connected with channels 16a and 16b for introducing liquid A (a solution containing a first metal compound) and liquid B (a solution containing a first reducing agent), and a channel 14a for discharging the first reaction liquid.

[0083] The second micromixer 13b is connected with channels 14a and 17a for introducing the first reaction liquid and liquid C (a solution containing a second metal compound), and a channel 14b for discharging the mixed liquid.

[0084] The third micromixer 13c is connected with channels 14b and 17b for introducing the mixed liquid and liquid D (a solution containing a second reducing agent), and a channel 14c for discharging the second reaction liquid containing metal composite particles.

[0085] The fourth micromixer 13d is connected with channels 14c and 18 for introducing the second reaction liquid and liquid E (a dispersion containing a carrier), and a channel 14d for discharging the fluid containing the metal composite particle carrier.

[0086] The first micromixer 13a has fluid inlets 1 and 2 and a fluid outlet 3. The second micromixer 13b has fluid inlets 4 and 5 and a fluid outlet 6. The third micromixer 13c has fluid inlets 7 and 8 and a fluid outlet 9. The fourth micromixer 13d has fluid inlets 10 and 11 and a fluid outlet 12. The fluid (dispersion) containing the metal composite particle carrier flows out from the tip 19 of the channel 14d into the receiving container 15.

[0087] In the present disclosure, as long as the above five types of liquids can be mixed, the configuration of the microreactor system used is not particularly limited, and a known microreactor (micromixer) can be used.

[0088] Examples of commercially available microreactors (micromixers) include, for example, Advanced-Flow (registered trademark) Reactor (manufactured by Corning Inc.); Modular Micro Reaction System, FlowPlate (registered trademark), ART (registered trademark), and Miprowa (registered trademark) (manufactured by Ehrfeld Mikrotechnik GmbH); GRAMFLOW (registered trademark), KILOFLOW (registered trademark), PROTRIX (registered trademark), and PLANTRIX (registered trademark) (manufactured by Chemtrix); HTM (registered trademark), MR-LAB (registered trademark), MRPILOT (registered trademark), and XXL (registered trademark) SERIES (manufactured by Little Things Factory); KeyChem (registered trademark) (manufactured by YMC); α-type mixer, β-type mixer, and DH-type mixer (manufactured by MiChS), etc. Any microreactor (micromixer) can be used in the manufacturing method of the present embodiment.

[0089] In addition, in the microreactor system used in the manufacturing method of the present disclosure, the flow rate of the fluid derived from each micromixer is preferably defined such that two types of fluids mixed in the microreactor can react with a desired mixing efficiency and a desired residence time.

[0090] The microreactor system used in the manufacturing method of the present embodiment may include two or more liquid supply means in addition to the micromixer. Further, as the micromixer, a reactor having one produced liquid derivation means (for example, a T-joint type reactor, a Y-joint, or a cross-joint, etc.) may be provided. It is preferable that the microreactor system is provided with a temperature adjustment means, a fluid flow rate adjustment means, and the like.

[0091] The case of performing the manufacturing method of the metal composite particle carrier of FIG. 1 using the microreactor system 100 of FIG. 2 will be described below as an example. In this example, it is not necessary to use a protective agent for the purpose of preventing aggregation of the metal composite particles. The total time T A may be from 0.001 second to 6 seconds. The total time T of this example Ais the time from when the solution containing the first metal compound introduced from the fluid inlet 1 and the solution containing the first reducing agent introduced from the fluid inlet 2 merge in the first micromixer 13a until the dispersion containing the metal composite particles and the dispersion containing the carrier merge in the fourth micromixer 13d.

[0092] In this example, by performing step 2 and step 3-1 one or more times each and mixing and reducing a plurality of metals, a metal composite particle carrier can be produced. When step 2 and step 3-1 are repeated, the total time T A is the sum of the times required from when the solution containing the first metal compound and the first reducing agent merge in step 1 until, after repeating step 2 and step 3-1, the second reaction solution obtained in step 3-1 and the carrier dispersion merge in the last step 3-2.

[0093] The residence time T3 from when the mixed solution obtained in step 2 and the solution containing the second reducing agent merge until the second reaction solution and the dispersion containing the carrier merge may be 5.99 seconds or less, preferably 5.5 seconds or less, more preferably 3.5 seconds or less, still more preferably 1.5 seconds or less, even more preferably 1 second or less, and particularly preferably 0.05 to 1 second. When the mixed solution obtained in step 2, the solution containing the second reducing agent, and the dispersion containing the carrier are mixed simultaneously, the residence time T3 is 0 seconds. Such simultaneous mixing can be performed using a cross-shaped micromixer.

[0094] From the perspective of reducing the variation in the particle size of the monodisperse metal composite particles, suppressing the formation of metal particles composed of a single metal, and suppressing the aggregation of the metal composite particles, the total time T A is preferably from 0.001 seconds to 6 seconds, more preferably from 0.001 to 4 seconds, still more preferably from 0.001 seconds to 2 seconds, and even more preferably from 0.01 seconds to 1.3 seconds.

[0095] Each step will be described in detail with reference to FIG. 2.

[0096] (Process 1) In this process, a solution containing a first metal compound having at least one metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn) and rhenium (Re) as a constituent element is mixed with a solution containing a reducing agent (first reducing agent) to obtain a first reaction solution.

[0097] The mixing temperature is preferably 10°C to 90°C, more preferably 20°C to 50°C. The gauge pressure in this process is preferably 0 to 20 MPa, more preferably 0.1 MPa to 5 MPa.

[0098] The flow rates of the solution containing the first metal compound and the solution containing the reducing agent are appropriately adjusted according to the residence time T1, the concentration of the solution, the length of the flow path, the capacity of the mixer, etc. In an example of the production apparatus, it is preferably 0.1 mL / min to 100 mL / min, more preferably 1 mL / min to 20 mL / min.

[0099] The reaction atmosphere in this process is not particularly limited as long as the reaction by the reducing agent is not inhibited. For example, inert gases such as nitrogen, helium, and argon; oxidizing gases such as oxygen and ozone can be mentioned, and these gases may be mixed and used. In this process, it is preferably carried out in air or an inert gas.

[0100] The same solvent as above is used in Process 1, and the concentration of the first metal compound is preferably prepared using 20 g to 60000 g, more preferably 200 g to 3000 g of the solvent per 1 g of the first metal compound. Similarly, the concentration of the first reducing agent is preferably prepared using 100 g to 50000 g, more preferably 500 g to 10000 g of the solvent per 1 g of the first reducing agent. The first reaction solution contains, for example, a solvent and metal particles composed of one kind of metal dispersed in the solvent.

[0101] (Step 2) In this step, using the second micromixer 13b, the first reaction solution in Step 1 or the second reaction solution in Step 3-1 is mixed with a solution containing at least one second metal compound selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re). However, the second metal compound is composed of a metal species different from that of the first metal compound. However, when this step is repeated, as long as different metal species are used at least once, the same metal species as the first metal compound may be used for the rest.

[0102] The residence time T1 required from the confluence of the solution containing the first metal compound and the solution containing the first reducing agent in Step 1 until the confluence of the first reaction solution and the solution containing the second metal compound in Step 2 can be set as appropriate. The residence time T1 is preferably from 0.001 second to 5 seconds, more preferably from 0.005 second to 1 second, even more preferably from 0.005 second to 0.7 second, and even more preferably from 0.005 second to 0.5 second.

[0103] The mixing temperature in Step 2 is preferably from 10°C to 90°C, more preferably from 20°C to 50°C.

[0104] The flow rate of the solution containing the second metal compound is appropriately adjusted according to the above residence time, solution concentration, flow path length, capacity of the micromixer, etc. In one example of the microreactor system, it is preferably from 0.1 mL / min to 200 mL / min, and even more preferably from 1 mL / min to 40 mL / min.

[0105] The pressure and reaction atmosphere in this step are the same as those in Step 1. The same solvent as above is used in Step 2, and the concentration of the second metal compound is preferably prepared using 20 g to 60000 g, more preferably 200 g to 3000 g of the solvent per 1 g of the second metal compound.

[0106] (Step 3-1) This step involves using the third micromixer 13c to mix the mixed solution obtained in Step 2 with a solution containing a reducing agent (the second reducing agent) to obtain a second reaction solution containing metal composite particles.

[0107] The residence time T2 required from when the first reaction solution and the solution containing the second metal compound merge in Step 2 until the mixed solution obtained in Step 2 and the solution containing the second reducing agent merge is preferably 0.001 seconds to 5 seconds, more preferably 0.005 seconds to 0.7 seconds, and even more preferably 0.005 seconds to 0.5 seconds.

[0108] The mixing temperature is preferably 10°C to 90°C, and more preferably 20°C to 50°C.

[0109] The flow rate of the solution containing the reducing agent is appropriately adjusted according to the residence time, the concentration of the solution, the length of the flow path, the capacity of the mixer, etc. In one example of the manufacturing apparatus, it is preferably 0.1 mL / min to 400 mL / min, and more preferably 1 mL / min to 80 mL / min.

[0110] The pressure and reaction atmosphere of this step are the same as those in Step 1. The same solvent as above is used in Step 3, and the concentration of the reducing agent is prepared using preferably 100 g to 50000 g, more preferably 500 g to 10000 g of the solvent per 1 g of the reducing agent.

[0111] In Step 3-1, a second reaction solution (dispersion) containing the solvent and metal composite particles dispersed in the solvent is obtained. The metal composite particles may be particles in which two types of metals are nanocomposited.

[0112] (Step 3-2) This step involves using the fourth micromixer 13d to mix the second reaction solution obtained in Step 3-1 with a dispersion containing a carrier after the mixing in Step 3-1, and supporting the metal composite particles on the carrier to obtain a metal composite particle support.

[0113] After the mixed liquid and the solution containing the second reducing agent merge in Step 3-1 and until the second reaction liquid obtained in Step 3-1 and the dispersion liquid containing the carrier merge, the residence time T3 may be 5.99 seconds or less, preferably 5.5 seconds or less, more preferably 3.5 seconds or less, still more preferably 1.5 seconds or less, even more preferably 1 second or less, and particularly preferably 0.05 to 1 second.

[0114] The mixing temperature in Step 3-2 is preferably 10°C to 90°C, and more preferably 20°C to 50°C.

[0115] The flow rate of the dispersion liquid in which the carrier is dispersed in the solvent is appropriately adjusted according to the above residence time, the concentration of the solution, the length of the flow path, the capacity of the mixer, etc. In one example of the production apparatus, it is preferably 0.1 mL / min to 400 mL / min, and more preferably 1 mL / min to 80 mL / min.

[0116] The content of the carrier in the dispersion liquid is preferably 0.1 to 5% by mass, more preferably 0.2 to 4% by mass, and still more preferably 0.3 to 3% by mass. If the content of the carrier becomes too high, the fluidity decreases and the dispersion liquid tends to clog in the fourth micromixer 13d and the upstream side thereof. On the other hand, if the content of the carrier becomes too low, the contact frequency between the carrier contained in the dispersion liquid and the metal composite particles contained in the second reaction liquid tends to decrease.

[0117] In order to make the loading amount of the metal composite particles within the range described below, the usage amount of the second reaction liquid obtained in Step 3-1 may be appropriately adjusted.

[0118] (Implementation of Step 2a and Step 3a) According to the number of metal species contained in the metal composite particle support to be produced, the following Steps 2a and 3a may be performed as the repetition of Step 2 and Step 3-1 between Step 3-1 and Step 3-2. Step 2a and Step 3a may be performed once each, or may be repeated two or more times.

[0119] (Step 2a) In the fifth micromixer, after Step 3-1, the second reaction solution obtained in Step 3-1 is mixed with a solution containing a third metal compound having at least one third metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) as a constituent element to obtain a mixed solution. The third metal element may be different from the first metal element and the second metal element, or may be the same as either one of them. The third metal compound may be different from the first metal compound and the second metal compound, or may be the same as either one of them.

[0120] (Step 3a) In the sixth micromixer, the mixed solution obtained in Step 2a is mixed with a solution containing a reducing agent (third reducing agent) to obtain a reaction solution (third reaction solution). The third reducing agent may be the same as or different from the first reducing agent and the second reducing agent. When Steps 2a and 3a are repeated, in the seventh micromixer, this third reaction solution is mixed with the solution containing the second metal compound to obtain a mixed solution. Then, Step 2a may be performed again using another micromixer. In Step 3-2 after the last Step 3a, the reaction solution (nth reaction solution, where n is an integer of 3 or more) obtained in the last Step 3a is mixed with a dispersion containing a carrier to obtain a metal composite particle carrier. The fifth micromixer, the sixth micromixer, and the seventh micromixer may be arranged in this order from the upstream side to the downstream side between the third micromixer and the fourth micromixer.

[0121] In such a case, the residence time T3 is the time required from when the mixed solution and the solution containing the nth reducing agent (n is an integer of 3 or more) merge in the last Step 3a until the reaction solution obtained in the last Step 3a and the dispersion containing the carrier merge in Step 3-2. Also, the total time T AThis refers to the total time required from the time when the solution containing the first metal compound and the solution containing the first reducing agent are joined in step 1, through steps 2 and 3-1, to the time when steps 2a and 3a are repeated the required number of times, and then, in step 3-2, the reaction solution obtained in the final step 3a is joined with the dispersion containing the carrier.

[0122] The total time T A The number of steps may be further increased within the range of 0.001 to 6 seconds. In this case, the definitions of each residence time and the total time are the same as those described above.

[0123] <Modification> 3 is a diagram illustrating a modified example of the method for producing a metal composite particle support. This production method includes steps 1, 2, and 3. This modified example differs from the above-mentioned example in that it includes step 3 in which the mixed liquid, the solution containing the second reducing agent, and the dispersion liquid containing the carrier are simultaneously mixed to obtain a metal composite particle support. The above description can be applied to other points.

[0124] Fig. 4 is a schematic diagram showing an example of a microreactor system used in the method for producing a metal composite particle support of Fig. 3. The microreactor system 102 of Fig. 4 includes, from the upstream side to the downstream side, a first micromixer 13a, a second micromixer 13b, and an eighth micromixer 13e in this order.

[0125] The configurations of the first micromixer 13a and the second micromixer 13b and the channels connected thereto are the same as those in Fig. 2. The eighth micromixer 13e is connected to a channel 14b for introducing the mixed liquid, a channel 17b for introducing liquid D (a solution containing a second reducing agent), and a channel 18 for introducing liquid E (a dispersion containing a carrier). In addition, the eighth micromixer 13e is connected to a channel 14d for discharging a fluid containing a metal composite particle carrier.

[0126] The eighth micromixer 13e has fluid inlets 21, 22, 23 and a fluid outlet 24. The solution containing the metal composite particle carrier flows out from the tip 19 of the channel 14d into the receiving vessel 15. In step 3 of this modification, three fluids are simultaneously mixed in the eighth micromixer 13e. As a result, the production of metal composite particles and the loading of the produced metal composite particles onto the carrier can be carried out in one step. Therefore, the number of micromixers can be reduced compared to the example of FIG. 2.

[0127] [Method for Producing Metal Composite Particle Carrier (Embodiment 2)] The method for producing a metal composite particle carrier according to an embodiment has the following steps 1, 2A, and 3A. In this production method, a metal composite particle carrier can be produced by the following procedure using a microreactor system including a plurality of micromixers. The shapes and sizes of the plurality of micromixers may be the same as each other or different from each other. Step 1 may be the same as in Embodiment 1. In the production method of this Embodiment 2, the order of mixing the solution containing the second reducing agent and the solution containing the second metal compound is reversed from that in Embodiment 1. Other configurations are the same as in Embodiment 1, and the description of Embodiment 1 is applicable. Steps 2A and 3A will be described below.

[0128] (Step 2A) The first reaction solution obtained in step 1 and the solution containing the second reducing agent are mixed to obtain a mixed solution. The residence time T2 required from the confluence of the first reaction solution and the solution containing the second reducing agent in step 2A until the confluence of the mixed solution obtained in step 2A and the solution containing the second metal compound is preferably from 0.001 second to 5 seconds, more preferably from 0.005 second to 0.7 second, and even more preferably from 0.005 second to 0.5 second.

[0129] (Step 3A) The mixed solution obtained in Step 2A, a solution containing a second metal compound having, as a constituent element, at least one second metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), and a dispersion containing a carrier are mixed sequentially or simultaneously to obtain a metal composite particle-supported carrier in which metal composite particles are supported on the carrier. When mixing sequentially, Step 3A may include Step 3A-1 of mixing the mixed solution and the solution containing the second metal compound to obtain a second reaction solution containing metal composite particles, and Step 3A-2 of mixing the second reaction solution and the dispersion containing the carrier to obtain a metal composite particle-supported carrier.

[0130] In all steps of Step 1, Step 2A, and Step 3A, it is not necessary to use a protective agent having a function of maintaining the dispersed state of the metal composite particles in the solvent. However, the case of using a protective agent is not excluded. The total time T A is preferably from 0.001 second to 6 seconds.

[0131] The total time T in the present embodiment A is defined as follows. When the mixed solution obtained in Step 2A, the solution containing the second metal compound, and the dispersion containing the carrier are mixed sequentially, the total time T A is the time from when the solution containing the first metal compound and the solution containing the first reducing agent merge until the second reaction solution obtained in Step 3A-1 and the dispersion containing the carrier merge. When the mixed solution obtained in Step 2A, the solution containing the second metal compound, and the dispersion containing the carrier are mixed simultaneously, the total time T A is the time from when the solution containing the first metal compound and the solution containing the first reducing agent merge until the mixed solution obtained in Step 2A, the solution containing the second metal compound, and the dispersion containing the carrier merge.

[0132] <Example of method for producing metal composite particle-supported carrier> Fig. 5 is a diagram illustrating an example of a method for producing a metal composite particle support. This production method includes step 1, step 2A, and the following steps 3A-1 and 3A-2. This example differs from the example of Fig. 3 in that it includes steps 3A-1 and 3A-2 instead of steps 3-1 and 3-2. In other respects, the description of Fig. 3 can be applied.

[0133] Fig. 6 is a schematic diagram showing an example of a microreactor system used in the manufacturing method of a metal composite particle support of Fig. 5. The microreactor system 104 of Fig. 2 includes a first micromixer 13a, a second micromixer 13b, a third micromixer 13c, and a fourth micromixer 13d in this order from the upstream side to the downstream side.

[0134] The first micromixer 13a is connected to channels 16a and 16b for introducing liquid A (a solution containing a first metal compound) and liquid B (a solution containing a first reducing agent), and a channel 14a for discharging the first reaction liquid.

[0135] The second micromixer 13b is connected to channels 14a and 17a for introducing the first reaction liquid and liquid D (a solution containing a second reducing agent), and channel 14b for discharging the mixed liquid.

[0136] The third micromixer 13c is connected to channels 14b and 17b for introducing the mixed solution and solution C (a solution containing a second metal compound), and channel 14c for discharging the second reaction solution containing metal composite particles.

[0137] The fourth micromixer 13d is connected to channels 14c and 18 for introducing the second reaction liquid and liquid E (a dispersion liquid containing a carrier), and channel 14d for discharging a fluid containing a metal composite particle support.

[0138] The first micromixer 13a has fluid inlets 1, 2 and a fluid outlet 3. The second micromixer 13b has fluid inlets 4, 5 and a fluid outlet 6. The third micromixer 13c has fluid inlets 7, 8 and a fluid outlet 9. The fourth micromixer 13d has fluid inlets 10, 11 and a fluid outlet 12. A fluid (dispersion) containing the metal composite particle carrier flows out from the tip 19 of the channel 14d into the receiving vessel 15.

[0139] In the above-described microreactor system 104, the order of mixing the C liquid and the D liquid is different from that of the microreactor system 100 in FIG. 2. Since other points are the same as those of the microreactor system 100, based on the content of the microreactor system 100 and an example of the manufacturing method using the same, the manufacturing method of this example can be carried out.

[0140] (Step 1) This step can be carried out in the same manner as in the examples of FIGS. 1 and 2 of the first embodiment. Here, overlapping descriptions are omitted.

[0141] (Step 2A) In this step, using the second micromixer 13b, the first reaction liquid in Step 1 and a solution containing a reducing agent (second reducing agent) are mixed to obtain a mixed liquid. The reducing agent used here may be the same as or different from the reducing agent (first reducing agent) used in Step 1. The residence time T required from when the solution containing the first metal compound and the solution containing the first reducing agent merge in Step 1 until the first reaction liquid and the solution containing the second reducing agent merge in Step 2A 1A can be set as appropriate. The residence time T 1A is preferably from 0.001 second to 5 seconds, more preferably from 0.005 second to 1 second, still more preferably from 0.005 second to 0.7 second, and even more preferably from 0.005 second to 0.5 second. The mixing temperature in Step 2A is preferably from 10°C to 90°C, and more preferably from 20°C to 50°C.

[0142] (Step 3A-1) This step involves using the third micromixer 13c to mix the mixed solution obtained in step 2A with the solution containing the second metal compound to obtain a second reaction solution containing metal composite particles. The second metal compound is the same as in the above example.

[0143] The residence time T required from when the first reaction solution and the solution containing the second reducing agent merge in step 2A until the mixed solution obtained in step 2A and the solution containing the second metal compound merge 2A is preferably from 0.001 second to 5 seconds, more preferably from 0.005 second to 0.7 second, and even more preferably from 0.005 second to 0.5 second. The mixing temperature is preferably from 10°C to 90°C, and more preferably from 20°C to 50°C.

[0144] In step 3A-1, a second reaction solution (dispersion) containing a solvent and metal composite particles dispersed in the solvent is obtained. The metal composite particles may be particles in which two types of metals are compounded at the nano level. The pressure and reaction atmosphere in step 3A-1 may be the same as in step 1.

[0145] (Step 3A-2) This step involves using the fourth micromixer 13d to mix the second reaction solution obtained in step 3A-1 with the dispersion containing the carrier after the mixing in step 3A-1, and supporting the metal composite particles on the carrier to obtain a metal composite particle support.

[0146] The residence time T from when the mixed solution and the solution containing the second metal compound merge in step 3A-1 until the second reaction solution obtained in step 3A-1 and the dispersion containing the carrier merge 3A may be 5.99 seconds or less, preferably 5.5 seconds or less, more preferably 3.5 seconds or less, even more preferably 1.5 seconds or less, even more preferably 1 second or less, and particularly preferably from 0.05 to 1 second. The mixing temperature in step 3A-2 is preferably from 10°C to 90°C, and more preferably from 20°C to 50°C. The dispersion containing the carrier is the same as in the example of the first embodiment above.

[0147] In a modification of this embodiment, similar to the modification of the first embodiment, instead of the third micromixer 13c and the fourth micromixer 13d in FIG. 6, a mixer similar to the eighth micromixer 13e shown in FIG. 4 may be used to simultaneously mix the mixed solution obtained in step 2A, a solution containing a second metal compound, and a dispersion containing a carrier to obtain a metal composite particle carrier. Thereby, the generation of metal composite particles and the loading of the generated metal composite particles onto the carrier can be performed in one step. Therefore, the number of micromixers can be reduced compared to the example in FIG. 6.

[0148] <Post-treatment> In the production method of each example in the above-described embodiments, the fluid (liquid composition) collected in the receiving vessel 15 contains the metal composite support. This liquid composition may be filtered to obtain a metal composite particle support. For example, the supernatant containing impurities can be separated by centrifugation and recovered as a precipitate. Further, it may be recovered only by filtration without centrifugation.

[0149] During filtration, it is preferable to wash the obtained solid with the above solvent. By washing, inorganic substances generated from a reducing agent or the like attached to the surface of the metal composite particle support can be removed. By drying the solid obtained by filtration or the like, a solid composition containing the metal composite support can be obtained. The drying temperature may be appropriately adjusted according to the boiling point of the solvent used. When water is used as the solvent, the drying temperature is preferably 80°C to 120°C, and more preferably 90°C to 110°C. When drying is performed under reduced pressure, drying may be performed at a lower temperature.

[0150] In the manufacturing method of each of the above embodiments, in each step, a plurality of fluids are mixed using different micromixers. Therefore, each step can be performed continuously and rapidly, and a metal composite particle carrier can be continuously manufactured. Since such continuous manufacturing is possible, the metal composite particle carrier can be mass-produced on an industrial scale. And in the metal composite particle carrier obtained by Step 1, Step 2 (Step 2A), and Step 3 (Step 3A), or Step 3-1 (Step 3A-1) and Step 3-2 (Step 3A-2) of the manufacturing method of each embodiment, aggregation of the metal composite particles is sufficiently suppressed by loading on the carrier, so that the metal composite particles are loaded on the carrier while maintaining high dispersibility. Note that in Step 3 or Step 3A (or Step 3-2 or Step 3A-2), a composition containing the metal composite particle carrier is obtained. Therefore, the manufacturing method of each of the above embodiments can also be referred to as a manufacturing method of a composition containing a metal composite particle carrier.

[0151] According to the manufacturing method of each of the above embodiments, a metal composite particle carrier can be manufactured by an industrially suitable method without using a protective agent for suppressing aggregation of the metal composite particles. For example, the amount of the protective agent used may be 1.5 mol or less per 1 mol of the first metal element. In addition, a metal composite particle carrier having a monodisperse particle size distribution can be manufactured. Furthermore, generation of metal particles composed of single metals can be suppressed, and the utilization efficiency of metal atoms can be increased.

[0152] [Composition] An embodiment of the composition of the present disclosure will be described. The composition includes one or more metal composite particle carriers. The metal composite particle carrier includes a carrier and metal composite particles supported on the carrier. The metal composite particles contain a plurality of types of metals in one particle. Such metal composite particle carriers can be manufactured by the above-described manufacturing method. The loading amount of the metal composite particles in the metal composite particle carrier is preferably 0.01 to 50% by mass, more preferably 0.1 to 15% by mass, and still more preferably 1 to 10% by mass. By being in such a range, the activity as a catalyst can be made sufficiently high. It is sufficient that at least a part of the plurality of metal composite particles contained in the composition is supported on the carrier. The composition may include metal composite particles not supported on the carrier.

[0153] The composition may be a solid (powder) or may be dispersed in a solvent to form a dispersion. That is, it may be a particulate composition or a slurry composition. The metal composite particles have a core-shell structure in which the concentration distributions of the first metal element and the second metal element are different between the outer shell portion and the central portion.

[0154] Metal composite particles having a core-shell structure in which the compositions of the core part and the shell part are different from each other can be obtained by the above-described manufacturing methods. Having a core-shell structure can be confirmed by STEM-EDS mapping analysis. For example, it can be analyzed under the following analysis conditions.

[0155] <Device name> JEOL JEM-ARM200F Atomic Resolution Analytical Electron Microscope manufactured by JEOL Ltd. and Silicon Drift Detector manufactured by JEOL Ltd. <Measurement conditions> Acceleration voltage 120 kV

[0156] When a region of only the second metal element exists in the outer shell portion of the metal composite particles by STEM-EDS mapping, the metal composite particles have a core-shell structure. Note that STEM refers to scanning transmission electron microscopy, and ESD refers to energy dispersive fluorescent X-ray analysis.

[0157] The particle size can be measured by TEM, STEM, SEM, etc. The particle size of the metal composite particles contained in the particle composition is appropriately adjusted according to the concentration of the metal compound, residence time, etc. For example, when using the metal composite particles as a catalyst, from the viewpoint of improving the catalytic activity, the average particle size of the metal composite particles contained in the particle composition is preferably 1.0 to 15 nm, more preferably 2.0 to 10 nm, and even more preferably 3.0 to 5.0 nm. Note that TEM refers to a transmission electron microscope, and the above STEM is a type of TEM. Also, SEM refers to a scanning electron microscope.

[0158] The standard deviation calculated from the particle size distribution of the particle size of the metal composite particles supported on the metal composite particle support measured using TEM is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.8 or less. Thus, the metal composite particles of the metal composite particle support contained in the composition have a sufficiently small variation in particle size. Note that the standard deviation may be 0.1 or more.

[0159] The maximum particle size of the metal composite particles measured using TEM is preferably 25 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less. Note that the maximum particle size may be 1.0 nm or more.

[0160] By reducing the particle size, the surface area per unit mass of the metal composite particles increases. Also, by reducing the variation in particle size, the differences in various properties such as the electronic state due to the difference in particle size can be reduced. Therefore, the activity as a catalyst is improved and it can be used in various catalytic reactions. Also, the reaction can be carried out with good reproducibility. The above composition can also be referred to as a catalyst composition.

[0161] The methods for calculating the average particle diameter, standard deviation, and coefficient of variation of the metal composite particles are as follows. Photographs of images magnified 1,000,000 to 1,500,000 times are taken of the metal composite particles using a transmission electron microscope (TEM). The diameter of a perfect circle (equivalent circle diameter) having the same area as the projected area of the metal composite particles on a plane (i.e., the area in the photograph) is regarded as the particle diameter. The measurement of the particle diameter using such a dark-field STEM photograph is performed for about 90 to 170 particles of the same type arbitrarily extracted, and the arithmetic mean value of the particle diameters of these particles is taken as the average particle diameter. Also, the standard deviation is obtained using this average particle diameter. Furthermore, the coefficient of variation is obtained by dividing the standard deviation of the particle diameter by the average value of the particle diameter (average particle diameter).

[0162] From the viewpoint of calculating more accurate average particle diameter, standard deviation, and coefficient of variation, it is preferable to use the measured values of the particle diameters of 90 or more particles.

[0163] The maximum value among the particle diameters for which the equivalent circle diameter was determined to calculate this average particle diameter is the maximum particle diameter of the particles measured by TEM. The variation in the particle diameter of the metal composite particles is preferably small and may be monodisperse. For example, the coefficient of variation may be 0.5 or less, preferably 0.4 or less, and more preferably 0.25 or less. Note that the coefficient of variation may be 0.1 or more.

[0164] The metal species present in one metal composite particle can be measured by STEM-EDS mapping. By each of the above production methods, a particle composition in which all of the metal particles supported on the metal composite particle support are composed of a plurality of metal species can be obtained. In TEM measurement, the metal species present in each particle can be identified by measuring the characteristic X-rays when the electrons of the L nucleus are scattered for each metal species.

[0165] The composition containing the metal composite particle support of the present disclosure can be applied as a catalyst for oxidation reaction and reduction reaction. As an example, it can be used for the oxygen reduction reaction (ORR) as a cathode electrode catalyst in a polymer electrolyte fuel cell (PEFC).

[0166] The metal composite particles may be composed of two metals selected from gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re). Among these, it is preferably composed of one metal selected from silver and gold, and one metal selected from copper, palladium, and platinum, and more preferably composed of palladium and platinum.

[0167] The surface area of the metal composite particles can be evaluated by the electrochemically active surface area. When the average particle diameter is the same, if the aggregation of the metal composite particles in the metal composite particle carrier is suppressed, the surface area of the metal composite particles increases. Therefore, the dispersibility (degree of aggregation) of the metal composite particles supported on the carrier can be evaluated from the surface area obtained in this evaluation. Since the catalytic reaction proceeds on the surface of the metal composite particles, the larger the surface area, the easier the catalytic reaction proceeds. Therefore, when the metal composite particle carrier is applied as a catalyst for oxidation reaction, reduction reaction, etc., the larger the surface area, the higher the catalytic activity tends to be.

[0168] The electrochemically active surface area (ECSA) of the metal composite particle carrier of this embodiment is preferably 105 to 200 m 2 / g-Pt, more preferably 105 to 180 m 2 / g-Pt, and even more preferably 110 to 140 m 2 / g-Pt. Examples of the method for measuring the electrochemically active surface area and the method for evaluating the oxygen reduction activity (cathode catalyst evaluation) will be described later, but are not limited to these methods.

[0169] The composition in this embodiment contains a metal composite particle carrier supporting metal composite particles having a core-shell structure with different compositions in the core part and the shell part. Moreover, since the electrochemical surface area is sufficiently large, aggregation of the metal composite particles in the metal composite particle carrier is sufficiently suppressed. Therefore, high performance can be exhibited, for example, in applications such as catalysts. The composition may not contain a protective agent that suppresses aggregation of the metal composite particles. Such a composition can further enhance the function as a catalyst. The content of the protective agent in the composition may be, for example, 1.5 mol or less per 1 mol of the first metal element.

[0170] As described above, one embodiment of the present disclosure has been described. However, the present disclosure is not limited to the above embodiment at all.

Examples

[0171] The content of the present disclosure will be described in more detail with reference to Examples and Comparative Examples. However, the present disclosure is not limited to the following Examples.

[0172] [Production of Metal Composite Particle Carrier] <Example 1> (Preparation of Solution A) 7.6 mg of NaBH4 (manufactured by Wako Pure Chemical Industries, Ltd.), which is a reducing agent (first reducing agent), was weighed and made up to 25 mL with an aqueous solution containing 10% by mass of diglyme (NaBH4 concentration: 8.0 mmol / L). (Preparation of Solution B) 326 mg of K2PdCl4 (manufactured by Sigma-Aldrich), which is a first metal compound, was weighed and made up to 200 mL with pure water (Pd concentration: 5 mmol / L). (Preparation of Solution C) 363 mg of H2PtCl6·6H2O (manufactured by Sigma-Aldrich), which is a second metal compound, was weighed and made up to 200 mL with pure water (Pt concentration: 3.5 mmol / L). (Preparation of Solution D) 5.3 mg of NaBH4 (manufactured by Wako Pure Chemical Industries, Ltd.), which is a reducing agent (second reducing agent), was weighed and made up to 25 mL with pure water (NaBH4 concentration: 5.6 mmol / L).

[0173] Each of the obtained solutions was filled into a syringe to about 20 mL and set on a syringe pump manufactured by HARVARD.

[0174] (Preparation of Solution E) 6400 mg of activated carbon (manufactured by Lion Specialty Chemicals Co., Ltd., trade name: Carbon ECP, specific surface area: 800 m 2 / g), which is a carrier, was weighed, 1600 ml of ethanol was added, and an activated carbon slurry (activated carbon content: 0.5 mass%) was prepared. While continuing to stir the activated carbon slurry, the activated carbon slurry (dispersion) was circulated and supplied to a slurry feed pump (manufactured by Heishin Equipment Co., Ltd., Mono Pump) using a tube pump manufactured by EYELA.

[0175] (Manufacture of Metal Composite Particle Support Using Microflow Process) The microreactor system 100 shown in FIG. 2 was fabricated in the following manner. One ends of the microtubes 16a, 16b, 17a, and 17b were each connected to a syringe pump. The other ends of the microtubes 16a and 16b were each connected to two inlets of the first micromixer 13a. The other ends of the microtubes 17a and 17b were each connected to the fluid inlet 5 of the second micromixer 13b and the fluid inlet 8 of the third micromixer 13c. The microtubes 16a, 16b, 17a, and 17b were all made of PEEK with a length of 100 cm and an inner diameter of 1 mm.

[0176] One end of the microtube 18 was connected to the slurry feed pump, and the other end of the microtube 18 was connected to the fluid inlet 11 of the fourth micromixer 13d. The microtube 18 was made of Teflon (registered trademark), with a length of 70 cm and an inner diameter of 1 mm. For the first micromixer 13a, the second micromixer 13b, and the third micromixer 13c, a three-way joint (inner diameter: 0.5 mm) made of PEEK by EYELA was used. For the fourth micromixer 13d, a tee (inner diameter: 1.5 mm) made of PEEK by EYELA was used.

[0177] The fluid outlet 3 of the first micromixer 13a and the fluid inlet 4 of the second micromixer 13b were connected by a microtube 14a. The fluid outlet 6 of the second micromixer 13b and the fluid inlet 7 of the third micromixer 13c were connected by a microtube 14b, and the fluid outlet 9 of the third micromixer 13c and the fluid inlet 10 of the fourth micromixer 13d were connected by a microtube 14c. For the microtubes 14a, 14b, and 14c, those made of PEEK with a length of 5 cm and an inner diameter of 1 mm were used. The fluid outlet 12 of the fourth micromixer 13d and the receiving container 15 were connected by a tube 14d made of Teflon (registered trademark) with a length of 21.5 cm and an inner diameter of 1.58 mm.

[0178] Using a syringe pump, liquid A was fed at 4 mL / min, liquid B was fed at 4 mL / min, liquid C was fed at 4 mL / min, liquid D was fed at 4 mL / min, and liquid E was fed at 20.5 mL / min. First, liquid A and liquid B were mixed and reacted in the first micromixer 13a to obtain a first reaction solution. Then, the first reaction solution and liquid C were mixed in the second micromixer 13b to obtain a mixed solution. The mixed solution and liquid D were mixed and reacted in the third micromixer 13c to obtain a second reaction solution. Then, the second reaction solution and liquid E were mixed in the fourth micromixer 13d to obtain a third reaction solution containing solids. The third reaction solution led out from the tip 19 of the tube 14d was collected in the container 15.

[0179] In the first micromixer 13a, the residence time T1 from the confluence of liquid A and liquid B until the confluence of the first reaction liquid and liquid C in the second micromixer 13b was 0.3 seconds. In the second micromixer 13b, the residence time T2 from the confluence of the first reaction liquid and liquid C until the confluence of the mixed liquid and liquid D in the third micromixer 13c was 0.2 seconds. Also, in the third micromixer 13c, the residence time T3 from the confluence of the mixed liquid and liquid D until the confluence of the second reaction liquid and liquid E in the fourth micromixer 13d was 0.15 seconds.

[0180] The total time T required from the confluence of liquid A and liquid B in the first micromixer 13a until the second reaction liquid flows into the fourth micromixer 13d and the second reaction liquid and liquid E containing activated carbon are confluent A was 0.65 seconds.

[0181] The solid content contained in the dispersion collected in the receiving container 15 was filtered, and dried at 40°C for 4 hours under reduced pressure. In this way, a metal composite particle support (Pd-core / Pt-shell / activated carbon) in which metal composite particles having a core-shell structure were supported on activated carbon as a support was produced. Here, in the present disclosure, "Pd-core / Pt-shell / activated carbon" means that particles having a Pd core and a Pt shell are supported on a support composed of activated carbon.

[0182] <Examples 2 to 3> By changing the length and inner diameter of the PEEK microtube 14c connecting the third micromixer 13c and the fourth micromixer 13d to the sizes described in Table 1, the residence time T3 and the total time T A were changed, and a metal composite particle support (Pd-core / Pt-shell / activated carbon) was produced in the same manner as in Example 1.

[0183] <Comparative Example 1> In the same manner as in Example 1, liquid A (NaBH4 concentration: 8.0 mmol / L), liquid B (Pd concentration: 5.0 mmol / L), liquid C (Pt concentration: 3.5 mmol / L), and liquid D (NaBH4 concentration: 5.7 mmol / L) were prepared.

[0184] (Production of Metal Composite Particle Support by Batch Process) The microreactor system 200 shown in FIG. 7 was fabricated. In the microreactor system 200, each syringe pump for feeding liquid A, liquid B, liquid C, and liquid D, the first micromixer 13a, the second micromixer 13b, and the third micromixer 13c were connected in the same manner as the microreactor system 100 of Example 1 using a microtube. The fluid outlet 9 of the third micromixer 13c and the receiving vessel 15 were connected by a PEEK microtube 20 having a length of 9 cm and an inner diameter of 0.75 mm. The receiving vessel 15 was charged with 340 mg of activated carbon (manufactured by Lion Specialty Chemicals Co., Ltd., trade name: Carbon ECP) and 85 ml of ethanol, and stirring was continuously carried out using a magnetic stirrer.

[0185] Using syringe pumps, liquid A was fed at 4 mL / min, liquid B was fed at 4 mL / min, liquid C was fed at 4 mL / min, and liquid D was fed at 4 mL / min, respectively. First, liquid A and liquid B were mixed and reacted in the first micromixer 13a to obtain a first reaction liquid. The first reaction liquid and liquid C were mixed in the second micromixer 13b to obtain a mixed liquid. The mixed liquid and liquid D were mixed and reacted in the third micromixer 13c to obtain a second reaction liquid. The second reaction liquid derived from the tip of the microtube 20 was collected in the receiving vessel 15 being stirred using a magnetic stirrer, and the activated carbon and the second reaction liquid were mixed. The mixing in the receiving vessel 15 was carried out for 15 minutes.

[0186] The residence time T1 and the residence time T2 measured in the same manner as in Example 1 were 0.3 seconds and 0.2 seconds, respectively. Also, the residence time T3 from the confluence of the mixed liquid and liquid D in the third micromixer 13c until the second reaction liquid confluenced into the dispersion containing the activated carbon in the receiving vessel 15 was 0.15 seconds. The total time T required from the start of the mixing of liquid A and liquid B in the first micromixer 13a until the second reaction liquid flowed into the receiving vessel 15 and contacted the dispersion containing the activated carbon A was 0.65 seconds.

[0187] After the second reaction solution flowed into the receiving vessel 15, stirring was continuously carried out in the receiving vessel 15 for 15 minutes. The solid contained in this dispersion was collected by filtration and dried at 40 °C under reduced pressure for 4 hours. In this way, a composition containing a metal composite particle support (Pd-core / Pt-shell / activated carbon) in which metal composite particles having a core-shell structure were supported on activated carbon as a support was obtained.

[0188] <Reference Examples 1 to 3> By changing the length and inner diameter of the PEEK microtube 14c connecting the third micromixer 13c and the fourth micromixer 13d to the sizes described in Table 3, the residence time T3 and the total time T A A metal composite particle support (Pd-core / Pt-shell / activated carbon) was produced in the same manner as in Example 1 except that the above were changed.

[0189] [Evaluation of Metal Composite Particle Support] <Catalytic Performance Evaluation> (Fabrication of Test Electrode) To evaluate the performance of the metal composite particle supports produced in each Example and Comparative Example 1 as catalysts, test electrodes were fabricated by the following procedure. 20 mg of the composition containing the metal composite particle support obtained in each Example and Comparative Example 1 was mixed with a mixed solution of 2.5 ml of 2-propanol and 2.5 ml of ultrapure water, respectively. Further, 45 μl of an aqueous solution in which 5 mass% of Nafion (registered trademark) was dispersed was added thereto to obtain a mixed solution.

[0190] The surface of a glassy carbon electrode with a diameter of 5 mm was polished smoothly using a slurry containing 1-μm diamond particles and a slurry containing 0.05-μm alumina particles in this order. After the above mixed solution was ultrasonically dispersed in ice water, 6.5 μl of this mixed solution was dropped onto the above surface of the glassy carbon electrode and dried at room temperature. In this way, the test electrodes of each Example and Comparative Example 1 were fabricated.

[0191] (Electrochemical Measurement) A beaker-type three-electrode cell was used for the electrolytic cell. A platinum electrode was used for the counter electrode, and a reversible hydrogen electrode (RHE) was used for the reference electrode. The test electrode described above was used as a rotating electrode for the working electrode. For the electrochemical measurement using the above electrolytic cell, ALS-760E (trade name) manufactured by BAS was used. The electrolytic cell was filled with a 0.1 M perchloric acid solution as the electrolyte, and argon gas was blown into the electrolyte for 30 minutes to remove the dissolved oxygen in the electrolyte. The measurement was carried out while maintaining the temperature of the electrolytic cell at 25°C. The potential scanning range was 0.05 - 1.2 V, and the scanning rate was 50 mV / sec. In order to remove the impurities on the surface of the test electrode, the measurement was started after performing a pretreatment of 20 cycles in which almost no change in the waveform was observed. As a result, a cyclic voltammetry curve was obtained.

[0192] (Calculation of Electrochemical Surface Area) Among the cyclic voltammetry curves obtained by the above-mentioned electrochemical measurement, the range from the electric double layer region to the rise of the hydrogen generation current was regarded as a hydrogen adsorption wave. On this premise, the discharge current of the electric double layer was subtracted from the measured current and integrated to obtain the hydrogen adsorption charge. The hydrogen adsorption charge Q H (C) was converted into the electrochemically active surface area (ECSA) (m 2 / g-Pt) by the following formula (1). The results were as shown in Table 1. Here, L Pt in the formula (1) is the mass (g) of platinum in the catalyst (metal composite particle support) used for the test electrode. ECSA = Q H / 2.1×L Pt ···(1)

[0193] (Evaluation of Oxygen Reduction Activity (Evaluation of Cathode Catalyst)) For the evaluation of oxygen reduction activity, the electrolytic cell used for the measurement of the electrochemical surface area was employed. The background was measured at an initial potential of 0.05 V, a final potential of 1.0 V, and a scan rate of 10 mV / sec. Subsequently, oxygen was blown in for 30 minutes to saturate it with oxygen. In this state, with an initial potential of 0.05 V, a final potential of 1.0 V, and a scan rate of 10 mV / sec, the polarization curves were measured while varying the rotation speed of the electrode to 400 rpm, 900 rpm, 1600 rpm, 2500 rpm, and 3600 rpm.

[0194] For the calculation of the activation-controlled current, the well-known Koutecky-Levich plot was used. In the following equation (2), ω 1 / 2 = 0 at the y-intercept to obtain the activation-controlled current I k (A), and the activity per platinum mass (MA) (A / g-Pt) at 0.9 V was calculated by the following equation (4). The results were as shown in Table 1.

[0195] 1 / I = 1 / I k + 1 / I L = 1 / I k + 1 / Bω 1 / 2 ···(2) In the above equation (2), B is the value calculated by the following equation (3).

[0196] B = 0.62nFAD 2 / 3 C ∞ ν -1 / 6 ω 1 / 2 (3) Each symbol in the above equation (3) has the following values. I k : Activation-controlled current I L : Diffusion-limited current n: Number of reaction electrons F: Faraday constant A: Electrochemical surface area (value obtained in the above measurement) D: Diffusion coefficient of oxygen ν: Kinematic viscosity of 0.1 M perchloric acid C ∞ : Oxygen solubility ω: Angular velocity of the rotating electrode (rad / s)

[0197] MA = I k / L Pt ···(4) L in the above formula (4) Pt is the mass (g) of platinum in the catalyst (metal composite particle support) used for the test electrode.

[0198] <Analysis of Structure> The photographs (A), (B), (C), and (D) in FIG. 8 are the results of STEM-EDS mapping analysis of the metal composite particles in the metal composite particle support obtained in Example 1. The photographs (A), (B), (C), and (D) in FIG. 9 are the results of STEM-EDS mapping analysis of the metal composite particles in the metal composite particle support obtained in Example 2. The photographs (A), (B), (C), and (D) in FIG. 10 are the results of STEM-EDS mapping analysis of the metal composite particles in the metal composite particle support obtained in Example 3. The photographs (A), (B), (C), and (D) in FIG. 11 are the results of STEM-EDS mapping analysis of the metal composite particles in the metal composite particle support obtained in Comparative Example 1.

[0199] In FIG. 8, photograph (A) shows a dark-field STEM image, photograph (B) shows an L image of palladium, and photograph (C) shows an L image of platinum. Photograph (D) is a composite of photograph (B) and photograph (C) and shows an L image of palladium and gold. The photographs (A), (B), (C), and (D) in FIGS. 9, 10, and 11 show a dark-field STEM image, an L image of palladium, an L image of platinum, and an L image of palladium and gold, respectively, in the same manner as in FIG. 8. The L image in this specification refers to an image detected by characteristic X-rays when electrons of the L nucleus in an atom are ejected. From these results, it was confirmed that the metal composite particles of Examples 1, 2, 3, and Comparative Example 1 all have a Pd-core / Pt-shell structure.

[0200] <Measurement of Particle Size Distribution> Figures 12, 13, 14, and 15 show the particle size distributions of the metal composite particles in the metal composite particle carriers of Example 1, Example 2, Example 3, and Comparative Example 1. Figures 16, 17, and 18 show the particle size distributions of the metal composite particles in the metal composite particle carriers of Reference Example 1, Reference Example 2, and Reference Example 3. These particle size distributions are the frequency distributions of the equivalent circle diameters obtained from dark-field STEM images. In Example 1, Example 2, Example 3, and Comparative Example 1, it was confirmed that metal composite particles with small variations in particle size were supported. Also in Reference Examples 1 to 3, it was confirmed that metal composite particles with small variations in particle size were supported. The average particle diameter, maximum particle diameter, standard deviation, coefficient of variation, and the number of measured metal composite particles obtained from the dark-field STEM images were as shown in Tables 2 and 4.

[0201] <Measurement of Loading Amount> ICP analysis was performed on the filtrate obtained by filtering the solid content from the dispersion collected in the receiving vessel. As a result, the first metal element and the second metal element were not detected. From this, it was confirmed that the total amounts of the first metal element and the second metal element used in the production of the metal composite particle carrier were supported on the carrier. Based on the amounts of the first metal compound and the second metal compound used in the reaction, the loading amount of the metal composite particles based on the metal composite particle carrier was determined. The results were as shown in Tables 1 and 3.

[0202]

Table 1

[0203]

Table 2

[0204] As shown in Table 1, Examples 1 to 3 had a larger electrochemical surface area than Comparative Example 1. This indicates that in Examples 1 to 3, the aggregation of the metal composite particles after being supported on the carrier was sufficiently suppressed. Therefore, Examples 1 to 3 are superior in catalytic performance to Comparative Example 1.

[0205]

Table 3

[0206]

Table 4

[0207] From Reference Examples 1 to 3, it was confirmed that even when the residence time and the total time were lengthened, metal composite particles with small variation in particle size were supported, as in Examples 1 to 3.

Industrial Applicability

[0208] According to the present disclosure, it is possible to provide a method for producing a metal composite particle support capable of sufficiently suppressing aggregation of metal composite particles after the metal composite particles are supported on a support. Further, it is possible to provide a composition containing a metal composite particle support in which aggregation of the metal composite particles supported on the support is sufficiently suppressed.

Explanation of Signs

[0209] 1, 2... fluid inlets, 4, 5... fluid inlets, 6... fluid outlet, 7, 8... fluid inlets, 9... fluid outlet, 10, 11... fluid inlets, 12... fluid outlet, 13a... first micromixer, 13b... second micromixer, 13c... third micromixer, 13d... fourth micromixer, 13e... eighth micromixer, 14a, 14b, 14c... channels (microtubes), 14d... channel (tube), 15... receiving vessel, 16a, 16b, 17a, 17b, 18... channels (microtubes), 19... tip, 20... microtube, 21, 22, 23... fluid inlets, 24... fluid outlet, 100, 102, 104, 200... microreactor systems.

Claims

1. Step 1 of obtaining a first reaction solution by mixing a solution containing a first metal compound having, as a constituent element, at least one first metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), and a solution containing a first reducing agent; Step 2 of obtaining a mixture by mixing the first reaction solution and a solution containing a second metal compound having, as a constituent element, at least one second metal element selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), wherein the second metal element is different from the first metal element; including Step 3 of obtaining a metal composite particle-supported carrier by supporting metal composite particles on the carrier using the mixture, a solution containing a second reducing agent, and a dispersion containing the carrier; Performing the step 1, the step 2, and the step 3 in a microreactor system including a plurality of micromixers to obtain the metal composite particle carrier having an electrochemical surface area of 105 to 200 m ２ / g-Pt, a method for producing a metal composite particle carrier.

2. Step 3 includes Step 3-1 of mixing the mixture and the solution containing the second reducing agent to obtain a second reaction solution containing the metal composite particles; and Step 3-2 of mixing the second reaction solution and the dispersion containing the carrier to obtain the metal composite particle-supported carrier, wherein the residence time from when the mixture and the solution containing the second reducing agent merge until the second reaction solution and the dispersion containing the carrier merge is 5.99 seconds or less. The method for producing a metal composite particle-supported carrier according to Claim 1.

3. The method for producing a metal composite particle-supported carrier according to Claim 2, wherein by using the second reaction solution obtained in Step 3-1 instead of the first reaction solution in Step 2, Step 2 and Step 3-1 are alternately repeated one or more times.

4. In Step 3, one micromixer is used to simultaneously mix the mixture, the solution containing the second reducing agent, and the dispersion containing the carrier to obtain the metal composite particle-supported carrier. The method for producing a metal composite particle-supported carrier according to Claim 1.

5. Step 1 of obtaining a first reaction solution by mixing a solution containing a first metal compound having, as a constituent element, at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), and a solution containing a first reducing agent. Step 2A of obtaining a mixed solution by mixing the first reaction solution and a solution containing a second reducing agent. Including Step 3A of obtaining a metal composite particle-supported carrier by using a solution containing a second metal compound having, as a constituent element, at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re), the second metal element being different from the first metal element, and a dispersion containing a carrier to support metal composite particles on the carrier. The step 1, the step 2A and the step 3A are carried out in a microreactor system including a plurality of micromixers to obtain the metal composite particle support having an electrochemical surface area of 105 to 200 m ２ / g-Pt. A method for producing a metal composite particle support.

6. Step 3A includes Step 3A-1 of obtaining a second reaction solution containing the metal composite particles by mixing the mixed solution and the solution containing the second metal compound. Step 3A has Step 3A-2 of obtaining the metal composite particle-supported carrier by mixing the second reaction solution and the dispersion containing the carrier. The manufacturing method of the metal composite particle-supported carrier according to Claim 5, wherein the residence time from when the mixed solution and the solution containing the second metal compound merge until the second reaction solution and the dispersion containing the carrier merge is 5.99 seconds or less.

7. The manufacturing method of the metal composite particle-supported carrier according to any one of Claims 1 to 6, wherein the content of the carrier in the dispersion is 0.1 to 5% by mass.

8. The manufacturing method of the metal composite particle-supported carrier according to any one of Claims 1 to 7, wherein the first reducing agent and the second reducing agent contain at least one selected from the group consisting of hydrazine compounds, boron hydride compounds, and organic carboxylic acid compounds.

9. In the first metal compound and the second metal compound, as the first metal element and the second metal element, respectively, only one of gold (Au), silver (Ag), copper (Cu), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), zinc (Zn), and rhenium (Re) is included. The method for producing a metal composite particle support according to any one of claims 1 to 8.

10. The method for producing a metal composite particle support according to any one of claims 1 to 9, wherein the loading amount of the metal composite particles in the metal composite particle support is 0.01 to 50% by mass.

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