Alloy production method, and alloy catalyst production method

Abstract

Provided is an alloy production method comprising: a step wherein an alkaline earth metal salt is mixed with at least two metal salts capable of constituting an alloy and selected from the group consisting of transition metals in periods 4 to 6 and groups 3 to 12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides in the presence of a solvent to obtain a mixed solution; a step wherein the mixed solution is dried and heated to obtain an oxide precursor; a step wherein the oxide precursor, a molten salt of an alkali metal salt or an alkaline earth metal salt, and a reducing agent selected from alkaline earth metals, hydrides of alkaline earth metals, and hydrides of alkali metals are heated and reduced in the presence of an inert gas to obtain a product; and a step wherein the product is washed to obtain an alloy. Also provided is a method for producing a catalyst of said alloy.

Description

Alloy manufacturing method, alloy catalyst manufacturing method

[0001] The present disclosure relates to a method for producing an alloy and a method for producing an alloy catalyst, and more particularly to a method for producing nano-sized alloy fine particles and a method for producing an alloy fine particle catalyst.

[0002] Intermetallic compounds as alloy materials have a unique regular crystal structure that differs from the original metals, and elements with significantly different electronic states are regularly arranged. Therefore, they are attracting attention as next-generation structural and functional materials that take advantage of functional and mechanical properties that metal materials do not have. For example, their main applications include shape memory alloys (TiNi) for medical devices and structural materials, as well as hydrogen storage (LaNi) ５ ), superconducting (Nb ３ Sn), and has been applied to new fields such as 3D metal printers, as well as in the purification of automobile exhaust gases, petroleum refining, fine chemistry, and as a solid catalyst in fuel cells.

[0003] Here, since metal reserves are limited, reducing the amount of metal used is an important issue. For example, it is known that in solid catalysts, reactions proceed only on the surfaces of nanometer-order (approximately 1-100 nm) particles. By increasing the specific surface area and enhancing reactivity through alloy refinement, the amount of metal used in the alloy can be reduced. Methods for producing such nano-sized alloy particles (alloy nanoparticles) include physical methods using evaporation or sputtering to produce them from raw metals, and chemical methods using molten metal decomposition or liquid-phase reduction.

[0004] One example of such physical methods is a method for producing metal powder by atomizing molten metal and then cooling the molten metal with a nanofluid containing nanoparticles (Patent Document 1). Another disclosed chemical molten metal decomposition method involves preparing a precursor alloy of each element, melting it by arc melting to mix the components, and cutting a thin plate-shaped precursor from the solidified alloy. The precursor is then immersed in a metal bath containing a specific metal to obtain a porous alloy (Patent Document 2). In a chemical liquid-phase reduction method, alloy nanoparticles are obtained by subjecting a solution containing the metals that make up the alloy to an appropriate reduction treatment. For example, a method for producing alloy nanoparticles has been disclosed in which a dendrimer solution (Patent Document 3) or a base compound (Patent Document 4) is added to a solution containing multiple metals and then subjected to a reduction treatment. Another method for producing nanoparticles by externally irradiating a laser (Patent Document 5) to promote the reduction reaction has also been disclosed. The present inventors have also reported the production of nanoparticles by subjecting a CaH ２ has been used as a reducing agent to successfully synthesize intermetallic compounds from metal precursor compounds (Non-Patent Document 1).

[0005] Japanese Patent Application Laid-Open No. 2020-105593 International Publication No. 2011 / 092909 Japanese Patent Application Laid-Open No. 2021-066709 Japanese Patent Application Laid-Open No. 2016-138324 Japanese Patent Application Laid-Open No. 2018-193582

[0006] Yasukazu Kobayashi, et. al, Journal of Japan Petroleum Institute, 2020, 63, 6, pp.380-387

[0007] The physical methods described above use expensive pure metals as raw materials and require expensive equipment capable of withstanding high temperatures, resulting in problems such as increased workload and costs. The chemical methods described above require expensive additives, special equipment for external reduction promotion, and adjustment of synthesis conditions appropriate for the alloy composition. In the reduction process, the higher the temperature conditions (e.g., 300°C or higher), the larger the size of the resulting alloy, such as alloy nanoparticles, or the particles aggregate, resulting in a reduced specific surface area. Therefore, synthesis at lower temperatures is desirable, but in this case, the alloying rate slows down, potentially resulting in the formation of phase-separated alloys.

[0008] Such alloys are expected to be used in a variety of applications as next-generation structural and functional materials, and alloys with larger specific surface areas are desirable for improving the functionality of the materials. In particular, expanded use as various catalytic materials is also desirable. The present disclosure has been made to solve the above-mentioned problems, and aims to provide a method for producing an alloy and a method for producing an alloy catalyst that can produce an alloy with a large specific surface area simply and at low cost.

[0009] The present inventors have discovered that alloys such as alloy powders, particularly alloy nanoparticles, can be produced by preparing an oxide precursor by mixing an alkaline earth metal salt with a salt of each metal element and then reducing the oxide precursor using a molten salt as a solvent. This reduction process, performed at high temperatures sufficient to dissolve the molten salt, results in a rapid reduction rate and highly crystalline alloy nanoparticles. Furthermore, the alkaline earth metal in the alkaline earth metal salt mixed into the raw material inhibits metal particle size increase and aggregation. This alkaline earth metal is easily removed by washing or other methods, acting as a template within the oxide precursor, resulting in alloy nanoparticles with a high specific surface area. Furthermore, the alkali metal salt or alkaline earth metal salt used as the molten salt, and the alkaline earth metal hydride or alkaline earth metal used as the reducing agent, are composed only of common elements, allowing for the easy production of alloy nanoparticles using relatively inexpensive reagents.

[0010] The present disclosure relates to the following methods for producing alloys: (1) A method for producing an alloy, comprising the steps of: mixing, in the presence of a solvent, salts of two or more alloy-constituting metals selected from the group consisting of transition metals of Periods 4-6 and Groups 3-12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides, with an alkaline earth metal salt to obtain a mixed solution; drying and heating the mixed solution to obtain an oxide precursor; heating and reducing, in the presence of an inert gas, the oxide precursor, at least one reducing agent selected from alkaline earth metals, alkaline earth metal hydrides, and alkali metal hydrides, and an alkali metal salt and / or a molten salt of an alkaline earth metal salt to obtain a product; and washing the product to obtain an alloy. (2) A method for producing an alloy according to (1), wherein a calcium salt is used as the alkaline earth metal salt in the mixed solution obtaining step. (3) The method for producing an alloy according to (1) or (2), wherein the step of obtaining the product is a step of heating at 300-800° C. (4) The method for producing an alloy according to any one of (1) to (3), wherein the step of removing the alkaline earth metal is a step of removing the alkaline earth metal by using an acidic solution on the product. (5) The method for producing an alloy according to any one of (1) to (4), wherein the metal is selected from Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, V, Cr, Mn, Nb, Mo, Ta, W, Re, Zn, Ga, Cd, In, Sn, Pb, and Bi.

[0011] The present disclosure also relates to a method for producing an alloy catalyst as described below: (6) A method for producing an alloy catalyst, comprising the steps of: mixing, in the presence of a solvent, salts of two or more metals capable of forming an alloy, the metals being selected from the group consisting of transition metals of Periods 4-6 and 3-12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanoids, with an alkaline earth metal salt to obtain a mixed solution; drying and heating the mixed solution to obtain an oxide precursor; heating and reducing, in the presence of an inert gas, the oxide precursor, at least one reducing agent selected from alkaline earth metals, alkaline earth metal hydrides, and alkali metal hydrides, and an alkali metal salt and / or a molten salt of an alkaline earth metal salt to obtain a product; and washing the product to obtain an alloy. (7) A method for producing an alloy catalyst as described in (6) above, wherein a calcium salt is used as the alkaline earth metal salt in the mixed solution obtaining step. (8) A method for producing an alloy catalyst according to claim 8 or (6) or (7), wherein the step of obtaining the product is a step of heating at 300 to 800°C. (9) A method for producing an alloy catalyst according to any one of (6) to (8), wherein the step of obtaining the alloy catalyst is a step of removing alkaline earth metals from the product using an acidic solution. (10) A method for producing an alloy catalyst according to any one of (6) to (9), wherein the metal is selected from Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, V, Cr, Mn, Nb, Mo, Ta, W, Re, Zn, Ga, Cd, In, Sn, Pb, and Bi.

[0012] According to the present disclosure, it is possible to provide a method for producing an alloy and a method for producing an alloy catalyst, which can produce an alloy with a large specific surface area simply and at low cost.

[0013] 1 is an X-ray diffraction pattern of the NiZn powder of Example 1. 2 is an SEM image of the NiZn powder of Example 1. 3 is an X-ray diffraction pattern of the NiCo powder of Example 2. 4 is an SEM image of the NiCo powder of Example 3. ３ 1 is an X-ray diffraction pattern of Fe powder. ３1 is an SEM image of Fe powder; 2 is an X-ray diffraction pattern of NiIn powder of Example 4; 3 is an SEM image of NiIn powder of Example 5; ４ 1 is an X-ray diffraction pattern of Mo powder. ４ 1 is a SEM image of Mo powder. ４ 1 is an X-ray diffraction pattern of W powder. ４ 1 is a SEM image of W powder. ３ 1 is an X-ray diffraction pattern of Cr powder. ３ 1 is a SEM image of Cr powder. ２ 1 is an X-ray diffraction pattern of FeGa powder. ２ 1 is a SEM image of FeGa powder. ２ 1 is an X-ray diffraction pattern of ZnMn powder. ２ 1 is a SEM image of ZnMn powder. ２ 1 is an X-ray diffraction pattern of FeGa powder. ２ 1 is a SEM image of FeGa powder. ２ 1 is an X-ray diffraction pattern of ZnGa powder. ２ 1 is a SEM image of ZnGa powder.

[0014] In a method for producing an alloy according to an embodiment of the present disclosure, an oxide precursor, which is a mixture of a salt of each metal element and an alkaline earth metal salt as raw materials, is reduced in a molten salt using a reducing agent, and the alkaline earth metal is then removed from the product. Note that, in this specification, when a numerical range is indicated, the upper and lower limits are included.

[0015] Specifically, the method for producing an alloy according to this embodiment includes the steps of: mixing, in the presence of a solvent, salts of two or more alloy-constituting metals selected from the group consisting of transition metals of Periods 4-6 and 3-12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides, with an alkaline earth metal salt to obtain a mixed solution; drying and heating the mixed solution to obtain an oxide precursor; heating and reducing, in the presence of an inert gas, the oxide precursor, at least one reducing agent selected from alkaline earth metals, alkaline earth metal hydrides, and alkali metal hydrides, and a molten salt of an alkali metal salt and / or an alkaline earth metal salt to obtain a product; and washing the product to obtain an alloy. The washing step for obtaining an alloy is, for example, a step of removing the alkaline earth metal of the alkaline earth metal salt used as a raw material from the product. The step of removing the alkaline earth metal from the alkaline earth metal salt used as the raw material is, for example, a step of removing the alkaline earth metal from the alkaline earth metal salt in the step of obtaining the mixed solution from the product to obtain an alloy. Specific details will be described later.

[0016] The constituent elements are metals selected from the group consisting of transition metals of periods 4-6 and groups 3-12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides. Although aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides are not transition metals, they share with the transition metals in that they can be constituent elements that form alloys (intermetallic compounds). Furthermore, while silicon, germanium, arsenic, selenium, antimony, and tellurium are strictly speaking semimetals, they share with the transition metals and aluminum, etc., the common property of forming alloys (intermetallic compounds) with other metal elements, and are therefore included in the metals in this specification. Note that the radioactive element technetium and liquid mercury are excluded. The metal may be selected from, for example, iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), vanadium (V), chromium (Cr), manganese (Mn), niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), rhenium (Re), zinc (Zn), gallium (Ga), cadmium (Cd), indium (In), tin (Sn), lead (Pb), bismuth (Bi), titanium (Ti), zirconium (Zr), and hafnium (Hf), as well as rare earth metals such as scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and samarium (Sm). In particular, because they have a weak affinity for oxygen and are easy to maintain a reduced state, they are preferably selected from Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, V, Cr, Mn, Nb, Mo, Ta, W, Re, Zn, Ga, Cd, In, Sn, Pb, and Bi, and more preferably selected from Ni, Zn, Fe, Co, In, W, Cr, Ga, and Mn. Furthermore, because they are inexpensive and easy to form alloys with other elements, it is more preferable that they contain at least Ni.

[0017] The number of elements to be selected is not limited to an upper limit as long as it is two or more, but since a larger number of elements makes it difficult to dissolve them in the step of obtaining a mixed solution, it is preferable to select about 2 to 4 elements. Furthermore, each constituent element may be present in an amount of up to about 90 atomic % (mol %).

[0018] As described above, according to this embodiment, the metal salts can be used as raw materials. The metal salts used as raw materials are easily available and inexpensive, which allows for cost reduction.

[0019] Metal salts include inorganic salts such as metal nitrates, sulfates, carbonates, phosphates, and chlorides, as well as organic salts such as alkoxides, acetates, and oxalates. In the case of inorganic salts, many nitrates or chlorides are soluble and inexpensively available, making them suitable. For example, when the raw material metal is nickel, Ni(NO ３ ) ２ ・6H ２ O, in the case of zinc, Zn(NO ３ ) ２ ・6H ２ O, in the case of iron, Fe(NO ３ ) ３ ・9H ２ In the case of vanadium and rhodium, the hydrates of nitrates such as VCl are available at low cost. ３ , RhCl ３ Chlorides such as these are preferred. Metal alkoxides are preferably used for Ti and Si because they are available soluble compounds. Metal alkoxides are salts that are often used in the sol-gel method. Metal alkoxides may also be used for Al. The above salts may be hydrates. Any salt may be used as long as it is an available soluble compound.

[0020] The metal salt and alkaline earth metal salt are then mixed in the presence of a solvent to obtain a mixed solution. A chelating agent may also be added to obtain the mixed solution. Examples of suitable solvents include ion-exchanged water, distilled water, glycerin, alcohol (especially ethanol), glycols (especially ethylene glycol and propylene glycol), and standard organic solvents (THF, acetone, and toluene). Among these, distilled water and ethanol are preferred due to their ease of handling and low cost. The chelating agent is an organic compound that forms a chelate complex with the metal ions in the solution. Standard, highly safe chelating agents include ethylenediaminetetraacetic acid, citric acid, phytic acid, and gluconic acid. Using a chelating agent, a uniform metal oxide powder can be obtained using a sol-gel complex polymerization method. The chelating agent should be used in a molar amount that is 1 to 1.5 times the molar amount of the metal.

[0021] The alkaline earth metal salts include inorganic salts such as nitrates, sulfates, carbonates, phosphates, and chlorides of calcium (Ca), magnesium (Mg), strontium (Sr), barium (Ba), etc., as well as organic salts such as alkoxides, acetates, and oxalates. In the case of inorganic salts, nitrates or chlorides are preferred because they are soluble and inexpensively available. Furthermore, calcium is preferred as the alkaline earth metal of the alkaline earth metal salt because it is inexpensive and easily available. For example, when the alkaline earth metal salt is a calcium salt, Ca(NO ３ ) ２ and CaCl ２ , (CH ３ COO) ２ Examples include calcium and calcium hydroxide. These calcium salts can be added in appropriate amounts. For example, in order for the added calcium to occupy a sufficient volume within the oxide precursor to function as a template, the molar ratio of calcium to the total number of moles of the metals contained in the metal salt can be set to Ca / metal = 0.1-2.0, preferably Ca / metal = 0.3-1.5. The same can be applied to salts of alkaline earth metals other than calcium.

[0022] The mixed solution containing the metal salt and alkaline earth metal salt is then dried and heated to obtain an oxide precursor. Heating may be performed in one step or multiple steps. For example, after pre-calcination at a low temperature, the calcined sample is uniformly pulverized and mixed in a mortar or the like using a pestle, and then calcined at a high temperature, which is preferable because it yields an oxide precursor in which the elements are uniformly dispersed. The heating temperature is preferably 300-800°C, but 400-600°C is preferred because it allows impurities other than the metal elements (e.g., chelating agents) to be removed by combustion or because it yields an oxide precursor in which the metal elements are uniformly dispersed. The heating time, which varies depending on the heating temperature, is preferably 0.5-10 hours, and preferably 3-6 hours.

[0023] In the process of obtaining this oxide precursor, a composite oxide of an alkaline earth oxide (e.g., CaO) and a metal (or a compound in which a metal is dispersed in CaO) is obtained by the action of an alkaline earth metal salt (e.g., a calcium salt) during firing, making it easier to obtain an oxide precursor powder. That is, in the process of drying and heating the mixed liquid to obtain the oxide precursor, at least one of the salts of two or more metals and the alkaline earth metal salt contained in the mixed liquid is oxidized. The oxide precursor is, for example, a metal oxide that is a precursor to an alloy. The metal oxide may be a composite oxide of an alkaline earth oxide and a metal, or a compound in which a metal is dispersed in an alkaline earth oxide.

[0024] Then, the oxide precursor, the reducing agent, and the molten salt source are mixed and reduced by heating in the presence of an inert gas (nitrogen, argon, helium, etc.). In this reduction process, the alkaline earth metal of the alkaline earth metal salt is present between the metal particles in the oxide precursor, thereby increasing the size of the metal particles and suppressing aggregation of the metal particles. After reduction, the alkaline earth metal of the alkaline earth metal salt forms a product as NH ４The alkaline earth metal can be removed by washing with a washing solution such as a Cl aqueous solution. As a result, the alkaline earth metal acts as a template, resulting in alloy nanoparticles with a large specific surface area. That is, the alloy manufacturing method includes a step of washing the product obtained in the step of obtaining the product to obtain an alloy. In this step of obtaining an alloy, the alkaline earth metal of the alkaline earth metal salt obtained in the step of obtaining the mixed solution is removed from the product obtained in the step of obtaining the product, thereby obtaining an alloy. The washing solution may be a general acidic solution capable of removing alkaline earth metals, such as NH ４ Weakly acidic solutions such as Cl solution, phosphoric acid solution, and acetic acid solution, and strongly acidic solutions such as perchloric acid solution, sulfuric acid solution, nitric acid solution, and hydrochloric acid solution can be used. Furthermore, solutions using organic solvents other than aqueous solutions may be used, and mixed solutions of aqueous solutions and organic solvents may also be used. The acidic solution preferably has a pH in the range of 3-6, and more preferably about pH 4 (e.g., pH 3.5 to 4.5). High acidity makes the alloy more susceptible to decomposition, so for example, NH ４ It is preferable to use a weak acid solution such as a Cl solution, a phosphoric acid solution, or an acetic acid solution. ２ , CaH ２ , CaO, etc.) can also be removed.

[0025] The heating temperature during reduction varies depending on the type of molten salt. However, it is preferably a temperature above the melting temperature, i.e., 300-1000°C, preferably 300-800°C, and more preferably 360-600°C, from the viewpoint that the reduction rate is sufficiently fast and a high specific surface area can be easily obtained by using relatively low temperatures. Alternatively, the molten salt source may be heated first, and the oxide precursor and reducing agent may be added to the molten salt source in its molten state, i.e., in the molten salt state. Alternatively, the molten salt source and the oxide precursor or reducing agent may be mixed and heated, and then the remaining reducing agent or oxide precursor may be added. When the molten salt is a mixed molten salt, its melting point is lower than that of a single molten salt, and it melts even at temperatures below 600°C, for example. The molten salt acts as a solvent, and the oxide precursor is reduced by the reducing agent in the molten salt. By using this molten salt reduction method, alloys can be obtained easily and at low cost. The heating time, depending on the heating temperature, is preferably 0.5-10 hours, preferably 2-6 hours. If the heating temperature is low (for example, about 550°C), the heating time may need to be extended (for example, about 10 hours), but if the heating temperature is high (for example, 700-800°C), the heating time can be shortened (for example, about 2 hours).

[0026] The reducing agent may be at least one selected from alkaline earth metals, alkaline earth metal hydrides, and alkali metal hydrides. Examples include elemental metals such as Mg, Ca, Sr, and Ba, hydrides thereof, and hydrides of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Calcium hydride, metallic calcium, magnesium hydride, metallic magnesium, and lithium hydride are preferred because they are relatively inexpensive, have good chemical stability, and are easy to handle. These reducing agents exhibit strong reducing properties in the molten salt. The reducing agents may be used alone or in combination. When using multiple reducing agents, they may be mixed in advance or added separately when mixing the oxide precursor and the molten salt. In particular, CaH ２ is a stable powder under room temperature and atmospheric conditions, and is therefore relatively safe to handle. ２ When used as a reducing agent, CaH ２reacts with oxygen contained in the oxide precursor to form CaO or Ca(OH) ２ By utilizing this, the number of moles of CaH ２ Preferably, the reducing agent is used in an amount of about 0.1 to 4 times, more preferably about 1 to 2 times, by weight relative to the oxide precursor.

[0027] The molten salt may be an alkali metal halide, an alkaline earth metal halide, or a mixture thereof. Examples of the alkali metal halide include compounds such as LiF, NaF, KF, RbF, CsF, LiCl, NaCl, KCl, RbCl, CsCl, LiBr, NaBr, KBr, RbBr, CsBr, LiI, NaI, KI, RbI, and CsI. Examples of the alkaline earth metal halide include MgF. ２ , CaF ２ , SrF ２ , BaF ２ , MgCl ２ , CaCl ２ , SrCl ２ , BaCl ２ , MgBr ２ , CaBr ２ , SrBr ２ , BaBr ２ , MgI ２ , CaI ２ , SrI ２ , BaI ２ Compounds such as the following can be used.

[0028] The above compounds can be used alone or in combination of two or more. The combination of these compounds, the number of compounds to be combined, the mixing ratio, etc. are not limited, and can be appropriately selected depending on whether they are stable in the atmosphere, easy to handle, or inexpensively available. In addition, AlCl ３ , ZnCl ２ Even halides of relatively less noble metals such as fluorine, fluorine, thiamin ...

[0029] In particular, the molten salt used in this embodiment is LiCl, CaCl ２A single molten salt such as LiCl and KCl, a mixed molten salt of LiCl and CaCl ２ It is preferable to use a mixed molten salt of the above. Furthermore, since the melting point of the mixed molten salt is lower than that of a single molten salt, the reaction can occur at a low temperature. Therefore, when the temperature at which the alloy is formed is low (for example, when the raw material contains an oxide that is easily reduced, such as a transition metal oxide), it is preferable to use a mixed molten salt. For example, since the melting point of a mixed molten salt of LiCl and KCl is 350°C, the reaction can occur even at a low temperature of about 360°C (for example, 355 to 365°C).

[0030] The alloys produced by the above method are alloy nanoparticles with a large specific surface area. Nanoparticles are finely divided particles on the nanometer order (approximately 1-100 nm), with an average particle size of approximately several nanometers (approximately 2-3 nm) to several tens of nanometers (approximately 10-60 nm), i.e., particles of 2 nm to 30 nm, and particularly particles of 2 nm to 10 nm. Here, the average particle size is the particle size calculated from the metal density and BET specific surface area, as described below. As described above, the alloys produced by the above method are also alloy powders. Therefore, the above-described alloy manufacturing method can be used as a manufacturing method for alloy powders. Such alloy nanoparticles are expected to be used in a variety of applications, including medical devices and structural materials, as well as electronic materials and catalytic materials. Furthermore, they contribute to improving functionality, such as catalytic properties, electrode properties, gas storage properties, and sensing properties, in fields such as electronic components for electrical devices, electrode materials, magnetic materials, ink materials, medical devices, automobile exhaust gas purification, petroleum refining, fine chemistry, and fuel cells.

[0031] For example, when used in medical devices or structural materials, the extremely small particle size allows for its use as a raw material for microfabricated products. Furthermore, because this alloy has a large specific surface area, it is particularly suitable as a catalytic material. That is, the alloy can be used as an alloy catalyst. Therefore, the above-described alloy manufacturing method can be used as a manufacturing method for an alloy catalyst. Furthermore, alloy catalysts, such as alloys of Ni, Zn, Fe, Co, In, W, Cr, Ga, and Mn, can be used primarily as hydrogenation catalysts or electrode catalysts. Furthermore, these alloys may function as catalysts themselves (with or without being supported on a carrier), or they may be used as catalyst carriers. For example, in the case of hydrogenation catalysts, the average particle size of the particles is preferably 50 nm or less, and more preferably 10 nm or less. According to this embodiment, such alloy nanoparticles can also be produced.

[0032] For example, Ni alloys are mainly used as catalysts for hydrogenation reactions in the liquid phase. The reactions are shown below. (A) Conversion of alkenes (double bonds) and alkynes (triple bonds) to alkanes. (B) Deprotection of benzyl groups (a compound of alcohol and the protecting benzyl group is hydrogenated to remove the benzyl group and obtain an alcohol). (C) Hydrogenation of nitro groups or imines to obtain amines. (D) Dehalogenation reaction by hydrogenation of aromatic halogens. (E) Synthesis of alcohols or methylene by hydrogenation of aldehydes or ketones. In particular, in organic synthesis, hydrogenation of nitro groups (C) is a common reaction and has a highly versatile application. For example, there is the hydrogenation reaction from p-nitrophenol to p-aminophenol, and NaBH is used as the reducing agent. ４ , hydrogen gas, LiAlH ４ etc. are used.

[0033] Furthermore, by supporting a metal catalyst for hydrogenation such as a Ni alloy, the catalyst can be applied to the synthesis of hydrocarbons or oxygen-containing hydrocarbons by hydrogenation of carbon monoxide or carbon dioxide, in addition to the above-mentioned liquid phase hydrogenation reaction, for example, methane synthesis by hydrogenation of carbon monoxide.

[0034] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0035] (Example 1) (Preparation of NiZn powder) Ni(NO) was dissolved in distilled water as a salt of the alloy metal. ３ ) ２ ・6H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 98%) and Zn(NO ３ ) ２ ・6H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 99%), Ca(NO ３ ) ２ ・4H ２ NiO (manufactured by Fuji Wako Pure Chemical Industries, Ltd., purity 98.5%) and citric acid (manufactured by Fuji Wako Pure Chemical Industries, Ltd.) were dissolved in a molar ratio of Ni / Zn / Ca / citric acid = 0.5 / 0.5 / y / (1 + y) × 1.2, and evaporated to dryness on a hot plate. Note that y was selected from 0.1, 0.3, 0.5, 1.0, and 1.5, and the salts of the constituent metals of the alloy were adjusted so that the total molar ratio was 1. Here, the molar ratio of metals refers to the molar ratio of metal atoms. The mixture was then pre-fired at 250°C for 2 hours. The fired sample was crushed and mixed in a mortar and pestle to form a powder with a nearly uniform particle size, and then fired again at 500°C for 2 hours to obtain an oxide precursor.

[0036] The obtained oxide precursor and CaH ２ LiCl-KCl (manufactured by Nacalai Tesque, Inc.) and LiCl-KCl (manufactured by Fuji Wako Pure Chemical Industries, Ltd., molar ratio 60:40) were mixed in a weight ratio of 2 / 6 / 3, and the mixture was heated in an SUS cylindrical container (similar to other examples) under an argon atmosphere at 360°C for 2 hours to perform molten salt reduction. The mixed molten salt source of LiCl and KCl was prepared by mixing in a mortar with a pestle. Finally, 0.1 M NH ４ The impurities (LiCl, KCl, CaH) were removed by washing the product with aqueous Cl solution and distilled water. ２ , CaO, etc.) were removed to obtain NiZn powder. ３ ) ２ ・4H ２NiZn powder was obtained under the same conditions as in Example 1, except that O (alkaline earth metal salt) was not added.

[0037] The prepared NiZn powder was subjected to X-ray diffraction pattern measurement, SEM image measurement, elemental analysis, nitrogen adsorption experiments, etc. Figure 1 shows the X-ray diffraction pattern of NiZn powder (Ca addition molar ratio 0.5), and Figure 2 shows an SEM image of the NiZn powder. The X-ray diffraction pattern was measured using an X-ray diffractometer (SmartLab (registered trademark), manufactured by Rigaku Corporation) under the following conditions: X-ray source: CuKα, output: 40 kV, 40 mA. Note that the reference data in the figure was referenced from the PDF (Powder Diffraction File) database by the ICDD (International Centre for Diffraction Data). The same applies to the following examples. The SEM image was measured using a scanning electron microscope (JEOL Ltd., JSM-7800F). For elemental analysis, the sample powder was placed in a dedicated sample holder and measured under vacuum using an X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku Corporation) with an X-ray tube (3 kW) and a Rh target. For nitrogen adsorption experiments, the sample was dried at 150°C for 60 minutes under an inert gas flow, and then the amount of nitrogen adsorption (BET specific surface area) was measured at liquid nitrogen temperature. The average particle size was calculated based on the alloy density listed in the Materials Project database (URL: https: / / materialsproject.org / ) and the measured BET specific surface area, assuming that the sample powder is composed of spherical particles.

[0038] From FIG. 1, the generation of NiZn was confirmed. Furthermore, the results of elemental analysis showed that the purity was 96.6 (Mass%) and Ni:Zn = 54:46 (mol%). The alloy composition is not necessarily limited to 100% purity, and may contain trace amounts of impurity elements, but is generally 96-98 (Mass%) or more, which is considered to be substantially 100%. Furthermore, the raw material contains Ca(NO ３ ) ２ ・4H ２The addition of O dramatically increased the specific surface area of ​​the NiZn powder. The average particle size also decreased (see Table 1 below). Since the BET specific surface area of ​​each sample was greatest when the Ca addition amount was 0.5 (molar ratio to the metal), alloys (alloy powders) were prepared under these conditions, but with different metal elements. In the following examples, unless otherwise noted, alloys were prepared using the same methods and conditions as in Example 1. The same reagents were used for common compounds. Furthermore, X-ray diffraction patterns, SEM images, elemental analysis, specific surface area, average particle size, etc. were measured using the same equipment and under the same methods and conditions as in Example 1.

[0039] (Example 2) (Preparation of NiCo powder) Ni(NO) was dissolved in distilled water as the salt of the alloy metal. ３ ) ２ ・6H ２ O and Co(NO ３ ) ２ ・6H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 99.5%), Ca(NO ３ ) ２ ・4H ２ O and citric acid were dissolved in a molar ratio of Ni / Co / Ca / citric acid = 0.5 / 0.5 / 0.5 / (1 + 0.5) × 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals refers to the molar ratio of metal atoms. The sample was then pre-fired at 250°C for 2 hours. The fired sample was crushed and mixed in a mortar with a pestle to form a powder with a nearly uniform particle size, and then fired again at 500°C for 2 hours to obtain an oxide precursor.

[0040] The obtained oxide precursor and CaH ２and LiCl-KCl (molar ratio 75:25) were mixed in a weight ratio of 2 / 6 / 3, and heated in an SUS cylindrical container under an argon atmosphere at 500°C for 2 hours to perform molten salt reduction. The subsequent washing process was carried out under the same conditions and method as in Example 1 to produce NiCo powder. Figure 3 shows the X-ray diffraction pattern of the produced NiCo powder, and Figure 4 shows an SEM image of the NiCo powder. Figure 3 confirms the production of NiCo. Furthermore, the result of elemental analysis showed a purity of 99.5 (mass%) and Ni:Co = 51:49 (mol%). Furthermore, as a comparative example, Ca(NO ３ ) ２ ・4H ２ NiCo powder was obtained under the same conditions as in Example 2, except that O (alkaline earth metal salt) was not added.

[0041] (Example 3) (Ni ３ Preparation of Fe powder) Ni(NO) was dissolved in distilled water as the salt of the alloy's constituent metals. ３ ) ２ ・6H ２ O and Fe(NO ３ ) ３ ・9H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 99%), Ca(NO ３ ) ２ ・4H ２ NiO and citric acid were dissolved in a molar ratio of Ni / Fe / Ca / citric acid = 0.75 / 0.25 / 0.5 / (1+0.5) x 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals is the molar ratio of metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 2. ３ The Ni powder was prepared. ３ The X-ray diffraction pattern of the Fe powder is shown in FIG. ３ The SEM image of the Fe powder is shown in FIG. ３ The generation of Fe was confirmed. Furthermore, the result of elemental analysis showed that the purity was 99.2 (mass%) and Ni:Fe=73:27 (mol%). ３ ) ２ ・4H ２The conditions were the same as in Example 3 except that no O (alkaline earth metal salt) was added. ３ An Fe powder was obtained.

[0042] (Example 4) (Preparation of NiIn powder) Ni(NO) was dissolved in distilled water as the salt of the alloy metal. ３ ) ２ ・6H ２ O and In(NO ３ ) ３ ・3H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 97%), Ca(NO ３ ) ２ ・4H ２ O and citric acid were dissolved in a molar ratio of Ni / In / Ca / citric acid = 0.5 / 0.5 / 0.5 / (1+0.5) × 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals refers to the molar ratio of metal atoms. NiIn powder was then produced under the same conditions and method as in Example 2. Figure 7 shows the X-ray diffraction pattern of the produced NiIn powder, and Figure 8 shows an SEM image of the NiIn powder. Figure 7 confirms the production of NiIn. Furthermore, elemental analysis revealed a purity of 99.3 (mass%) and Ni:In = 45:55 (mol%). As a comparative example, Ca(NO ３ ) ２ ・4H ２ NiIn powder was obtained under the same conditions as in Example 4, except that O (alkaline earth metal salt) was not added.

[0043] (Example 5) (Ni ４ Preparation of Mo powder) Ni(NO) was dissolved in distilled water as the salt of the alloy metal. ３ ) ２ ・6H ２ O and (NH ４ ) ６ Mo ７ O ２４ ・4H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 99%), Ca(NO ３ ) ２ ・4H ２The molar ratio of Ni / Mo / Ca / citric acid was 0.8 / 0.2 / 0.5 / (1+0.5) x 1.2, and the solution was evaporated to dryness on a hot plate. The molar ratio of the metals is the molar ratio of the metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 2. ４ Mo powder was prepared. ４ The X-ray diffraction pattern of the Mo powder is shown in FIG. ４ 9 shows the SEM image of Mo powder. ４ The generation of Mo was confirmed. Furthermore, the result of elemental analysis showed that the purity was 99.4 (mass%) and Ni:Mo=81:19 (mol%). ３ ) ２ ・4H ２ The conditions were the same as in Example 5 except that no O (alkaline earth metal salt) was added. ４ Mo powder was obtained.

[0044] (Example 6) (Ni ４ Preparation of W powder) Ni(NO) was dissolved in distilled water as the salt of the alloy's constituent metals. ３ ) ２ ・6H ２ O and (NH ４ ) １０ W １２ O ４１ ・5H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 85%), Ca(NO ３ ) ２ ・4H ２ The molar ratio of Ni / W / Ca / citric acid was 0.8 / 0.2 / 0.5 / (1+0.5) x 1.2, and the solution was evaporated to dryness on a hot plate. The molar ratio of metals is the molar ratio of metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 2. ４ W powder was prepared. ４ The X-ray diffraction pattern of W powder is shown in FIG. ４ 11 shows the SEM image of W powder. ４The generation of W was confirmed. Furthermore, the result of elemental analysis showed that the purity was 99.6 (mass%) and Ni:W = 88:12 (mol%). ３ ) ２ ・4H ２ The conditions were the same as in Example 6 except that no O (alkaline earth metal salt) was added. ４ W powder was obtained.

[0045] (Example 7) (Ni ３ Preparation of Cr powder) Ni(NO) was dissolved in distilled water as the salt of the alloy constituent metal. ３ ) ２ ・6H ２ O and Cr(NO ３ ) ３ .9H ２ O (manufactured by Strem Chemicals, Inc., purity 99%), Ca (NO ３ ) ２ ・4H ２ O and citric acid were dissolved in a molar ratio of Ni / Cr / Ca / citric acid = 0.75 / 0.25 / 0.5 / (1 + 0.5) × 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals refers to the molar ratio of metal atoms. The sample was then pre-fired at 250°C for 2 hours. The fired sample was crushed and mixed in a mortar with a pestle to form a powder with a nearly uniform particle size, and then fired again at 500°C for 2 hours to obtain an oxide precursor.

[0046] The obtained oxide precursor and CaH ２ and LiCl were mixed in a weight ratio of 2 / 6 / 3, and heated in an SUS cylindrical container under an argon atmosphere at 600°C for 2 hours to perform molten salt reduction. The subsequent cleaning process was carried out under the same conditions and by the same method as in Example 1. ３ Cr powder was prepared. ３ 14 shows the X-ray diffraction pattern of the Cr powder, and ３ 13 shows the SEM image of the Cr powder. ３ The generation of Cr was confirmed. Furthermore, the result of elemental analysis showed that the purity was 99.8 (mass%) and Ni:Cr=74:26 (mol%). ３) ２ ・4H ２ The conditions were the same as in Example 7 except that no O (alkaline earth metal salt) was added. ３ Cr powder was obtained.

[0047] (Example 8) (Ni ２ Preparation of FeGa powder) Ni(NO) was dissolved in distilled water as a salt of the alloy constituent metal. ３ ) ２ ・6H ２ O and Fe(NO ３ ) ３ ・9H ２ O and Ga(NO ３ ) ３ ・8H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 99.9%), Ca(NO ３ ) ２ ・4H ２ NiO and citric acid were dissolved in a molar ratio of Ni / Fe / Ga / Ca / citric acid = 0.5 / 0.25 / 0.25 / 0.5 / (1+0.5) x 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals is the molar ratio of metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 2. ２ The FeGa powder was prepared. ２ The X-ray diffraction pattern of the FeGa powder is shown in FIG. ２ 15 shows the SEM image of the FeGa powder. ２ The generation of FeGa was confirmed. Furthermore, the result of elemental analysis showed that the purity was 98.2 (mass%) and Ni:Fe:Ga = 49:27:24 (mol%). ３ ) ２ ・4H ２ The conditions were the same as in Example 8 except that no O (alkaline earth metal salt) was added. ２ FeGa powder was obtained.

[0048] (Example 9) (Ni ２ Preparation of ZnMn powder) Ni(NO) was dissolved in distilled water as the salt of the alloy's constituent metals. ３ ) ２ ・6H ２ O and Zn(NO３ ) ２ ・6H ２ O and Mn(NO ３ ) ２ ・6H ２ O (Fuji Wako Pure Chemical Industries, Ltd., purity 98%), Ca(NO ３ ) ２ ・4H ２ The molar ratio of Ni / Zn / Mn / Ca / citric acid was 0.5 / 0.25 / 0.25 / 0.5 / (1+0.5) x 1.2, and the solution was evaporated to dryness on a hot plate. The molar ratio of the metals is the molar ratio of the metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 2. ２ ZnMn powder was prepared. ２ The X-ray diffraction pattern of the ZnMn powder is shown in FIG. ２ 17 shows an SEM image of ZnMn powder. In addition, in FIG. 17, Ni ２ Ni with a similar crystal structure to ZnMn ２ The data for GaMn was used. ２ The formation of ZnMn was confirmed. Furthermore, the result of elemental analysis showed that the purity was 99.1 (mass%) and Ni:Zn:Mn = 54:23:23 (mol%). ３ ) ２ ・4H ２ The conditions were the same as in Example 9 except that no O (alkaline earth metal salt) was added. ２ ZnMn powder was obtained.

[0049] (Example 10) (Co ２ Preparation of FeGa powder) Co(NO ３ ) ２ ・6H ２ O and Fe(NO ３ ) ３ ・9H ２ O and Ga(NO ３ ) ３ ・8H ２ O, Ca(NO ３ ) ２ ・4H ２Co, Fe, Ga, Ca, and citric acid were dissolved in a molar ratio of Co / Fe / Ga / Ca / citric acid = 0.5 / 0.25 / 0.25 / 0.5 / (1+0.5) x 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals is the molar ratio of metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 7. ２ The FeGa powder was prepared. ２ The X-ray diffraction pattern of the FeGa powder is shown in FIG. ２ 19 shows the SEM image of the FeGa powder. ２ The generation of FeGa was confirmed. Furthermore, the result of elemental analysis showed that the purity was 99.1 (mass%) and the Co:Fe:Ga ratio was 49:25:26 (mol%). ３ ) ２ ・4H ２ The conditions were the same as in Example 10 except that no O (alkaline earth metal salt) was added. ２ FeGa powder was obtained.

[0050] (Example 11) (Co ２ Preparation of ZnGa powder) Co(NO ３ ) ２ ・6H ２ O and Zn(NO ３ ) ２ ・6H ２ O and Ga(NO ３ ) ３ ・8H ２ O, Ca(NO ３ ) ２ ・4H ２ Co, Zn, Ga, Ca, and citric acid were dissolved in a molar ratio of Co / Zn / Ga / Ca / citric acid = 0.5 / 0.25 / 0.25 / 0.5 / (1+0.5) x 1.2, and evaporated to dryness on a hot plate. Here, the molar ratio of metals is the molar ratio of metal atoms. The subsequent steps were carried out under the same conditions and by the same method as in Example 7. ２ ZnGa powder was prepared. ２ 22 shows the X-ray diffraction pattern of the ZnGa powder. ２21 shows an SEM image of ZnGa powder. ２ Co has a similar crystal structure to ZnGa ２ The data for VGa was used. ２ The generation of ZnGa was confirmed. Furthermore, the result of elemental analysis showed that the purity was 97.9 (mass%) and the Co:Zn:Ga ratio was 51:21:28 (mol%). ３ ) ２ ・4H ２ The conditions were the same as in Example 10 except that no O (alkaline earth metal salt) was added. ２ ZnGa powder was obtained.

[0051] Table 1 shows the results of the alloys prepared in Examples 1-11 above. From the results in Table 1, the raw material Ca(NO ３ ) ２ ・4H ２ It can be seen that the addition of O dramatically increased the specific surface area of ​​each alloy. In addition, the average particle size also decreased. Therefore, the calcium salt (Ca(NO ３ ) ２ ) resulted in an alloy with a large specific surface area. In other words, the addition of calcium salt suppressed the aggregation of the alloy by allowing calcium to act as a template during reduction. Furthermore, SEM images confirmed a microstructure consisting of fine particles ranging from several nanometers to several tens of nanometers. These results suggest that the resulting alloy is an alloy nanoparticle with a fine structure. It is preferable to select a reduction temperature high enough to facilitate alloy formation after the oxide precursor is reduced. In particular, selecting Ni as a constituent element is preferable because it allows an alloy with a large specific surface area to be obtained at a relatively low reduction temperature. Thus, the alloy of this example can be applied to structural materials and 3D metal printers that require microfabrication. It is also suitable as a catalyst material that requires a large specific surface area and nano-sized alloy fine particles.

[0052] This disclosure has the potential to be used as a shape memory alloy in a variety of fields, including medical devices, structural materials, new application areas such as 3D metal printers, and as a catalyst material.

Claims

1. A process of mixing salts of two or more metals selected from the group consisting of transition metals of periods 4-6, groups 3-12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides, which can constitute an alloy, with an alkaline earth metal salt in the presence of a solvent to obtain a mixed solution, The process involves drying and heating the aforementioned mixture to obtain an oxide precursor. A step of heating and reducing the oxide precursor, at least one reducing agent selected from alkaline earth metals, alkaline earth metal hydrides, and alkali metal hydrides, and an alkali metal salt and / or a molten alkaline earth metal salt in the presence of an inert gas to obtain a product. A step of washing the aforementioned product to obtain an alloy, A method for manufacturing an alloy that includes the following features.

2. The method for producing an alloy according to claim 1, wherein a calcium salt is used as the alkaline earth metal salt in the step of obtaining the aforementioned mixed liquid.

3. The method for producing an alloy according to claim 1 or claim 2, wherein the step of obtaining the aforementioned product is a step of heating at 300-800°C.

4. The method for producing an alloy according to claim 1 or claim 2, wherein the step of obtaining the alloy is a step of removing alkaline earth metals from the product using an acidic solution.

5. The method for producing an alloy according to claim 1 or claim 2, wherein the metal is selected from Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, V, Cr, Mn, Nb, Mo, Ta, W, Re, Zn, Ga, Cd, In, Sn, Pb, and Bi.

6. A method for manufacturing an alloy catalyst, A process of mixing salts of two or more metals selected from the group consisting of transition metals of periods 4-6, groups 3-12, aluminum, silicon, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, and lanthanides, which can constitute an alloy, with an alkaline earth metal salt in the presence of a solvent to obtain a mixed solution, The process involves drying and heating the aforementioned mixture to obtain an oxide precursor. A step of heating and reducing the oxide precursor, at least one reducing agent selected from alkaline earth metals, alkaline earth metal hydrides, and alkali metal hydrides, and an alkali metal salt and / or a molten alkaline earth metal salt in the presence of an inert gas to obtain a product. A step of washing the aforementioned product to obtain an alloy, A method for manufacturing an alloy catalyst comprising the above.

7. The method for producing an alloy catalyst according to claim 6, wherein a calcium salt is used as the alkaline earth metal salt in the step of obtaining the aforementioned mixture.

8. The method for producing an alloy catalyst according to claim 6 or claim 7, wherein the step of obtaining the aforementioned product is a step of heating at 300-800°C.

9. The method for producing an alloy catalyst according to claim 6 or claim 7, wherein the step of obtaining the alloy is a step of removing alkaline earth metals from the product using an acidic solution.

10. The method for producing an alloy catalyst according to claim 6 or claim 7, wherein the metal is selected from Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, V, Cr, Mn, Nb, Mo, Ta, W, Re, Zn, Ga, Cd, In, Sn, Pb, and Bi.