Method for producing metal-carbon catalyst

Abstract

To provide a method for producing a metal-carbon catalyst that enables production of a catalyst which is low in cost and exhibits high catalytic activity, and to provide a metal-carbon catalyst that is low in cost and exhibits high catalytic activity.SOLUTION: A method for producing a metal-carbon catalyst is provided, the method comprising: step 1 of mixing at least one metal (M) selected from the group consisting of nickel and cobalt, a solution containing nitric acid or a nitrate, and an amine (A) having one or two amino groups selected from the group consisting of a benzylamino group and an aliphatic amino group, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and step 2 of separating the catalyst precursor from the solution and calcining the catalyst precursor.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a metal-carbon catalyst. [Background technology]

[0002] In various chemical reactions, catalysts play an important role by promoting the reaction and suppressing side reactions. Among them, precious metal catalysts such as platinum are widely used. Hydrogen production by water electrolysis has a very small environmental impact and is an important technology for a recycling-oriented society. The biggest challenge with water electrolysis is the high cost of hydrogen production. In this regard, catalyst materials are one of the key factors that have a significant impact on the overall cost. Platinum (Pt)-based catalysts are excellent catalysts for the hydrogen evolution reaction (HER), with high catalytic activity, but are expensive, significantly increasing the cost of hydrogen production. Therefore, HER catalysts using inexpensive metals are being developed. For example, Patent Document 1 discloses an alternative HER catalyst based on earth-abundant transition metals, which includes catalytic metal species such as nickel and cobalt containing active catalytic species, and vanadium species, in which the catalytic metal species and vanadium species are incorporated into the catalyst.

[0003] Hydrogenation reactions are also very important chemical reactions, and hydrogenation reactions of unsaturated bonds, ketone groups, aldehyde groups, nitro groups, etc. are used in the synthesis of various chemical products. Precious metal catalysts such as Pt and palladium (Pd) are well known as hydrogenation catalysts, but they have the major problem of being expensive. Therefore, Raney nickel, which is relatively inexpensive yet exhibits high hydrogenation catalytic activity, is widely used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-508971 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, catalysts that do not use precious metals such as platinum have been developed, but catalysts with sufficient performance have not yet been obtained. Furthermore, the preparation of HER catalysts that combine multiple metals, as in Patent Document 1, requires a complicated manufacturing process and is therefore not suitable for large-scale hydrogen production. Meanwhile, the aforementioned Raney nickel, which is used as a hydrogenation catalyst in particular, has the risk of generating heat and catching fire in a dry state, and requires careful handling. Therefore, there is a demand for hydrogenation catalysts that are inexpensive, highly active, and yet highly safe. As described above, there is a demand for a catalyst that has high activity as an HER catalyst, and that can also be used as a chemical reaction catalyst (e.g., hydrogenation catalyst), is inexpensive, and is easy to produce. Therefore, an object of the present invention is to provide a method for producing a metal-carbon catalyst that can produce a catalyst that is inexpensive yet has high catalytic activity, and to provide a metal-carbon catalyst that is inexpensive yet has high catalytic activity. [Means for solving the problem]

[0006] The present inventors have found that the above problems can be solved by a production method in which a precursor obtained from a nitric acid solution of nickel or cobalt and a specific amine is calcined, and have thus completed the present invention.

[0007] That is, the present invention is a method for producing a metal-carbon catalyst, comprising: Step 1: mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M), and Step 2: separating the catalyst precursor from the solution and calcining it. The present invention also relates to a metal-carbon catalyst containing 0.5 to 70 mass % of at least one metal (M) selected from the group consisting of nickel and cobalt. [Effects of the Invention]

[0008] The present invention provides a method for producing a metal-carbon catalyst that can produce a catalyst that is inexpensive yet has high catalytic activity, and a metal-carbon catalyst that is inexpensive yet has high catalytic activity. The resulting metal-carbon catalyst is particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows examples of linear sweep voltammetry (LSV) curves in hydrogen generation tests (Test Examples 1 and 2 and Comparative Test Example 1) using the catalysts of Examples 1 and 2 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Metal-carbon catalyst manufacturing method] The method for producing a metal-carbon catalyst of the present invention includes: Step 1: mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate thereof, with an amine (A) having at least one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and Step 2: separating the catalyst precursor from the solution and calcining the catalyst precursor. The method for producing a metal-carbon catalyst of the present invention preferably includes Step 1: mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate thereof, with an amine (A) having at least one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M), and Step 2: separating the catalyst precursor from the solution, drying it, and calcining it.

[0011] According to the method for producing a metal-carbon catalyst of the present invention, it is possible to obtain a catalyst that is inexpensive yet has high catalytic activity. The specific method is shown below.

[0012] <Step 1: Step of Precipitating a Catalyst Precursor (Catalyst Precursor Precipitation Step)> The method for producing a metal-carbon catalyst of the present invention includes, as an initial step, Step 1, of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups, at least one of which is selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M).

[0013] (solution) The solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate (hereinafter simply referred to as a solution) contains the metal (M), nitric acid or a nitrate, and a solvent. Here, examples of the solvent include water and lower alcohols, and lower alcohols are preferred. By using lower alcohols, the amount of amine (A) used can be reduced. The lower alcohol is preferably an aliphatic alcohol having 1 to 4 carbon atoms, and more preferably an aliphatic alcohol having 1 to 3 carbon atoms. Specifically, methanol, ethanol, and isopropyl alcohol are preferred, and methanol is more preferred. The solvent is preferably at least one selected from the group consisting of water and methanol, and more preferably methanol. A mixture of methanol and water is also preferably used. The metal (M) is at least one selected from the group consisting of nickel and cobalt. From the viewpoint of hydrogenation catalytic performance, the metal (M) is preferably at least one selected from the group consisting of nickel and a mixture of nickel and cobalt, and more preferably a mixture of nickel and cobalt. Furthermore, the metal (M) is preferably cobalt from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde. Furthermore, from the viewpoint of HER catalytic performance, the metal (M) is preferably at least one selected from the group consisting of nickel and a mixture of nickel and cobalt, and more preferably nickel. When the metal (M) is a mixture of nickel and cobalt, the mixing ratio of nickel to cobalt (nickel / cobalt) is not particularly limited, but is preferably 0.1 to 10.0, more preferably 0.2 to 5, and even more preferably 0.25 to 4 in molar ratio. The metal (M) is preferably contained in the solution as a metal ion, and specifically, the metal ion contained in the solution is preferably at least one selected from the group consisting of nickel ions and cobalt ions. From the viewpoint of hydrogenation catalytic performance, the metal ions contained in the solution are preferably at least one selected from the group consisting of nickel ions and a mixture of nickel ions and cobalt ions, and more preferably a mixture of nickel ions and cobalt ions. Furthermore, the metal ion contained in the solution is more preferably a cobalt ion from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde. Furthermore, from the viewpoint of HER catalytic performance, the metal ions contained in the solution are more preferably at least one selected from the group consisting of nickel ions and a mixture of nickel ions and cobalt ions, and nickel ions are even more preferred. The content of the metal (M) in the solution is preferably 0.1 to 50 g / L, more preferably 0.1 to 30 g / L, even more preferably 0.2 to 25 g / L, and even more preferably 1 to 20 g / L, calculated as metal ions. The solution contains nitric acid or a nitrate, preferably nitric acid. When nitric acid is contained, it is preferably contained as nitrate ions. When the solvent is a lower alcohol and does not contain any water, nitrate ions may not be liberated. In this case, it is preferable that nitrate ions are contained as nitrate ions. The nitrate is preferably at least one selected from the group consisting of sodium nitrate, potassium nitrate, and calcium nitrate. The content of nitric acid or nitrate in the solution is preferably 0.005 to 8 mol / L, more preferably 0.008 to 6 mol / L, even more preferably 0.1 to 5 mol / L, and still more preferably 0.1 to 3 mol / L, calculated as nitrate ions. Alternatively, at least one selected from the group consisting of nickel nitrate and cobalt nitrate, which are nitrates of nickel and cobalt, may be used as the metal (M) that has been previously reacted with nitric acid, and it is preferable to use the nitrates of nickel and cobalt for convenience, with nickel nitrate being more preferred.

[0014] The solution can be prepared by mixing the metal (M), nitric acid or a nitrate, and the solvent. The order of mixing is not important, and pre-mixed and reacted materials may be used. Specifically, the following combinations are possible: a method of mixing nickel hydroxide with an aqueous nitric acid solution as a pre-mixed solution of nitric acid and a solvent; a method of mixing a metal (M) (ion) with a metal nitrate salt containing nitric acid (ion) and methanol as a pre-reacted solution of nitric acid and a metal;

[0015] (amine (A)) The amine (A) is an amine having one or two amino groups, at least one of which is selected from the group consisting of benzylamino groups and aliphatic amino groups, preferably an amine having one or two benzylamino groups, and more preferably an amine having two benzylamino groups. The amine (A) is preferably an amine having two amino groups, and is preferably a diamine. The amine (A) preferably has 3 to 8 carbon atoms, more preferably 4 to 8 carbon atoms, and even more preferably 6 to 8 carbon atoms. When the amine (A) has the above structure, the resulting catalyst has high activity and is particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions.

[0016] The amine having a benzylamino group includes at least one selected from the group consisting of xylylenediamine and benzylamine, and preferably xylylenediamine. The amine having an aliphatic amino group may be at least one selected from the group consisting of bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine. The amine (A) is preferably at least one selected from the group consisting of xylylenediamine, bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine, more preferably at least one selected from the group consisting of xylylenediamine and bis(aminomethyl)cyclohexane, and even more preferably xylylenediamine. Among the bis(aminomethyl)cyclohexanes, at least one selected from the group consisting of 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane is preferred, and 1,4-bis(aminomethyl)cyclohexane is more preferred. Among xylylenediamines, at least one selected from the group consisting of m-xylylenediamine (meta-xylylenediamine) and p-xylylenediamine (para-xylylenediamine) is preferred, and m-xylylenediamine is more preferred.

[0017] (Mixing solution and amine (A)) In this step, the solution is mixed with an amine (A) to precipitate a catalyst precursor containing the amine (A) and a metal (M).

[0018] In this step, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms), in terms of the ratio of the number of amine molecules to the number of metal atoms, is preferably 0.5 to 500, more preferably 1 to 400, even more preferably 1 to 300, still more preferably 2 to 200, still more preferably 2 to 100, still more preferably 2 to 80, and still more preferably 2 to 50. When the metal (M) is a mixture of nickel and cobalt, the molar amount of the metal (M) is the total amount of the molar amount of nickel and the molar amount of cobalt.

[0019] In particular, when the solvent is water, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms) is preferably 1 to 500, more preferably 2 to 400, even more preferably 5 to 300, still more preferably 10 to 200, and even more preferably 20 to 100. Furthermore, when the solvent is a lower alcohol, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms) is preferably 0.5 to 100, more preferably 1 to 50, even more preferably 1 to 30, still more preferably 2 to 20, and even more preferably 2 to 10. When the metal (M) is a mixture of nickel and cobalt, the molar amount of the metal (M) is the total amount of the molar amount of nickel and the molar amount of cobalt. In this step, the molar ratio of the amine (A) (in terms of amino groups) to the nitrate ions (amino groups of the amine (A) / nitrate ions) is preferably 1-3.

[0020] The mixing method in this step may be any method that allows the solution and amine (A) to be mixed well. The amine (A) may be added to the solution, or the solution may be added to the amine (A). To mix the whole, stirring or shaking may be performed. The mixing time (stirring time or shaking time) may be adjusted appropriately depending on the concentrations of the components of the solution, the type of solvent, the amount of amine (A), the temperature of the solution, etc., but is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. Mixing may be terminated when precipitation of a catalyst precursor containing amine (A) and metal (M) is completed. In this manner, a precipitate that serves as a catalyst precursor containing the amine (A) and the metal (M) can be obtained.

[0021] In this step, it is preferable to mix carbon black. That is, preferred step 1 is a step of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, nitric acid or a nitrate, carbon black, and an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. Note that carbon black may be contained in the solution. That is, step 1 may also be a step of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, carbon black, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. In this specification, when a catalyst precursor is obtained as a catalyst precursor composition containing carbon black, the catalyst precursor composition can be treated as having the same meaning as the catalyst precursor.

[0022] Examples of carbon black that can be used in this step include furnace black, channel black, acetylene black, and thermal black, with furnace black being preferred.

[0023] The amount of carbon black is preferably 50 to 5,000 parts by mass, more preferably 100 to 3,000 parts by mass, even more preferably 100 to 2,000 parts by mass, and still more preferably 200 to 1,000 parts by mass, relative to 100 parts by mass of the metal (M) (metal element, metal ion). When carbon black is mixed, the preferred molar ratio of the amine (A) to the metal (M) is the same as above. Furthermore, when carbon black is mixed, any mixing method may be used as long as it allows the solution, carbon black, and amine (A) to be mixed well, and any component may be added first. Preferred methods include adding carbon black to the solution and then adding amine (A), and mixing the solution and amine (A) to obtain a precipitate and then adding carbon black to the resulting dispersion. Of these, the method of adding carbon black to the solution and then adding amine (A) is more preferred. To mix the entire mixture, stirring or shaking may be used. The mixing time (stirring time or shaking time) may be adjusted appropriately depending on the concentrations of the components of the solution, the type of solvent, the amount of amine (A), the type and amount of carbon black, the temperature of the solution, etc., but is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. Mixing may be terminated when precipitation of the catalyst precursor composition containing the amine (A), carbon black, and metal (M) is completed. In this manner, a precipitate that serves as a catalyst precursor composition containing the amine (A), carbon black, and metal (M) can be obtained. A catalyst can be obtained by using a precipitate containing carbon black and calcining it as described below. The catalyst obtained in this way has excellent catalytic activity, especially hydrogenation catalytic activity. Although the reason for this is unclear, it is thought that the metal-carbon catalyst is supported on the carbon black, which prevents the catalyst from agglomerating and increases the specific surface area of ​​the catalyst.

[0024] <Step 2: Step of separating the catalyst precursor from the solution and calcining it (catalyst precursor recovery step and calcination step)> The method for producing a metal-carbon catalyst of the present invention includes step 2, in which the catalyst precursor is separated from the solution and calcined, following step 1. Step 2 is preferably a step, in which the catalyst precursor is separated from the solution, dried, and calcined, following step 1.

[0025] In this step, first, the catalyst precursor is separated from the solution. When carbon black is used in the previous step, a catalyst precursor composition containing carbon black is separated from the solution. In this case, step 2 is a step following step 1 in which the catalyst precursor composition is separated from the solution and calcined. The method for separating the catalyst precursor or catalyst precursor composition from the solution is not particularly limited, and various solid-liquid separation methods can be used, such as filtration and centrifugation. Next, the obtained precipitate (catalyst precursor or catalyst precursor composition) is preferably dried. Drying is preferably carried out before calcination. There are no limitations on the drying method.

[0026] The catalyst precursor or catalyst precursor composition is then calcined to obtain a metal-carbon catalyst. In step 2, the firing temperature is preferably 250 to 1000°C, more preferably 300 to 1000°C, even more preferably 300 to 900°C, still more preferably 400 to 900°C, even more preferably 450 to 850°C, and still more preferably 450 to 800°C. The firing time may be changed as appropriate depending on the firing temperature and the like, but is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours, and even more preferably 15 minutes to 2 hours. The calcination is preferably carried out in the presence of an inert gas, more preferably nitrogen. By calcining under the above conditions, the catalytic activity of the resulting catalyst can be increased.

[0027] [Catalyst precursor and method for producing catalyst precursor] The catalyst precursor of the present invention is a catalyst precursor comprising at least one metal (M) selected from the group consisting of nickel and cobalt, and an amine (A) having one or two amino groups, at least one of which is selected from the group consisting of benzylamino groups and aliphatic amino groups. The catalyst can be obtained by calcining the catalyst precursor.

[0028] The metal (M) contained in the catalyst precursor is at least one selected from the group consisting of nickel and cobalt. From the viewpoint of hydrogenation catalytic performance, the metal (M) is preferably at least one selected from the group consisting of nickel and a mixture of nickel and cobalt, and more preferably a mixture of nickel and cobalt. Furthermore, the metal (M) is preferably cobalt from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde. Furthermore, from the viewpoint of HER catalytic performance, the metal (M) is preferably at least one selected from the group consisting of nickel and a mixture of nickel and cobalt, and more preferably nickel. When the metal (M) contained in the catalyst precursor is a mixture of nickel and cobalt, the mixing ratio of nickel to cobalt (nickel / cobalt) is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.25 to 4, in molar ratio. The content of the metal (M) may be adjusted appropriately depending on the types of metal and amine used as raw materials, but is preferably 3 to 40 mass %, more preferably 5 to 35 mass %, even more preferably 5 to 25 mass %, and still more preferably 5 to 20 mass % in the catalyst precursor. When the catalyst precursor is obtained as a catalyst precursor composition containing carbon black, the content of the metal (M) may be adjusted appropriately depending on the types of metal and amine used as raw materials, but is preferably 0.1 to 20 mass %, more preferably 0.3 to 15 mass %, even more preferably 0.5 to 10 mass %, and still more preferably 1 to 7 mass % in the catalyst precursor composition.

[0029] The amine (A) having one or two at least one amino group selected from the group consisting of benzylamino groups and aliphatic amino groups, which is contained in the catalyst precursor or catalyst precursor composition, is an amine having one or two at least one amino group selected from the group consisting of benzylamino groups and aliphatic amino groups, preferably an amine having one or two benzylamino groups, more preferably an amine having two benzylamino groups. The amine (A) is preferably an amine having two amino groups, and is preferably a diamine. The amine (A) preferably has 3 to 8 carbon atoms, more preferably 4 to 8 carbon atoms, and even more preferably 6 to 8 carbon atoms. When the amine (A) has the above structure, a catalyst obtained using the catalyst precursor or catalyst precursor composition has high activity and is excellent particularly as a catalyst for hydrogen generation reactions and hydrogenation reactions.

[0030] The amine having a benzylamino group includes at least one selected from the group consisting of xylylenediamine and benzylamine, and preferably xylylenediamine. The amine having an aliphatic amino group may be at least one selected from the group consisting of bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine. The amine (A) is preferably at least one selected from the group consisting of xylylenediamine, bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine, more preferably at least one selected from the group consisting of xylylenediamine and bis(aminomethyl)cyclohexane, and even more preferably xylylenediamine. Among the bis(aminomethyl)cyclohexanes, at least one selected from the group consisting of 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane is preferred, and 1,4-bis(aminomethyl)cyclohexane is more preferred. Among xylylenediamines, at least one selected from the group consisting of m-xylylenediamine (meta-xylylenediamine) and p-xylylenediamine (para-xylylenediamine) is preferred, and m-xylylenediamine is more preferred.

[0031] The molar ratio of the metal (M) to the amine (A) contained in the catalyst precursor (metal (M) / amine (A)) is preferably 5 / 0.2 to 0.2 / 5, more preferably 3 / 0.5 to 0.5 / 3, and even more preferably 2 / 1 to 1 / 2. More specifically, the molar ratio (metal (M) / amine (A)) varies depending on the type of metal (M) and amine (A). For example, the molar ratio of nickel to xylylenediamine (nickel / xylylenediamine) is preferably about 1 / 2, the molar ratio of nickel to bis(aminomethyl)cyclohexane (nickel / bis(aminomethyl)cyclohexane) is preferably about 1 / 2, the molar ratio of cobalt to xylylenediamine (cobalt / xylylenediamine) is preferably about 2 / 1, the molar ratio of cobalt to benzylamine (cobalt / benzylamine) is preferably about 1 / 1, and the molar ratio of cobalt to 2-ethylhexylamine (cobalt / 2-ethylhexylamine) is preferably about 1 / 1. Furthermore, when the metal (M) is a mixture of nickel and cobalt, the molar ratio of nickel-cobalt to xylylenediamine (nickel-cobalt / xylylenediamine) is preferably about 1 / 1.

[0032] The method for producing a catalyst precursor of the present invention is preferably a method for producing a catalyst precursor comprising: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and Step 3 of performing solid-liquid separation of the catalyst precursor.The method for producing a catalyst precursor of the present invention is more preferably a method for producing a catalyst precursor comprising: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M), Step 3 of performing solid-liquid separation of the catalyst precursor, and Step 4 of drying.

[0033] Step 1 of the method for producing a catalyst precursor of the present invention is the same as <Step 1: Step of precipitating a catalyst precursor (catalyst precursor precipitation step)> in the above [Method for producing a metal-carbon catalyst], and the preferred conditions are also the same. Specific conditions are shown below.

[0034] The solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate (hereinafter simply referred to as a solution) contains the metal (M), nitric acid or a nitrate, and a solvent. Here, examples of the solvent include water and lower alcohols, and lower alcohols are preferred. By using lower alcohols, the amount of amine (A) used can be reduced. The lower alcohol is preferably an aliphatic alcohol having 1 to 4 carbon atoms, and more preferably an aliphatic alcohol having 1 to 3 carbon atoms. Specifically, methanol, ethanol, and isopropyl alcohol are preferred, and methanol is more preferred. The solvent is preferably at least one selected from the group consisting of water and methanol, and more preferably methanol. A mixture of methanol and water is also preferably used. The metal (M) is at least one selected from the group consisting of nickel and cobalt. From the viewpoint of hydrogenation catalytic performance, the metal (M) is preferably at least one selected from the group consisting of nickel and a mixture of nickel and cobalt, and more preferably a mixture of nickel and cobalt. Furthermore, the metal (M) is preferably cobalt from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde. Furthermore, from the viewpoint of HER catalytic performance, the metal (M) is preferably at least one selected from the group consisting of nickel and a mixture of nickel and cobalt, and more preferably nickel. When the metal (M) is a mixture of nickel and cobalt, the mixing ratio of nickel to cobalt (nickel / cobalt) is not particularly limited, but is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.25 to 4 in molar ratio. The metal (M) is preferably contained in the solution as a metal ion, and specifically, the metal ion contained in the solution is preferably at least one selected from the group consisting of nickel ions and cobalt ions. From the viewpoint of hydrogenation catalytic performance, the metal ions contained in the solution are preferably at least one selected from the group consisting of nickel ions and a mixture of nickel ions and cobalt ions, and more preferably a mixture of nickel ions and cobalt ions. Furthermore, the metal ion contained in the solution is more preferably a cobalt ion from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde. Furthermore, from the viewpoint of HER catalytic performance, the metal ions contained in the solution are more preferably at least one selected from the group consisting of nickel ions and a mixture of nickel ions and cobalt ions, and nickel ions are even more preferred. The content of the metal (M) in the solution is preferably 0.1 to 50 g / L, more preferably 0.1 to 30 g / L, even more preferably 0.2 to 25 g / L, and even more preferably 1 to 20 g / L, calculated as metal ions. The solution contains nitric acid or a nitrate, preferably nitric acid. When nitric acid is contained, it is preferably contained as nitrate ions. When the solvent is a lower alcohol and does not contain any water, nitrate ions may not be liberated. In this case, it is preferable that nitrate ions are contained as nitrate ions. The nitrate is preferably at least one selected from the group consisting of sodium nitrate, potassium nitrate, and calcium nitrate. The content of nitric acid or nitrate in the solution is preferably 0.005 to 8 mol / L, more preferably 0.008 to 6 mol / L, even more preferably 0.1 to 5 mol / L, and still more preferably 0.1 to 3 mol / L, calculated as nitrate ions. Alternatively, at least one selected from the group consisting of nickel nitrate and cobalt nitrate, which are nitrates of nickel and cobalt, may be used as the metal (M) that has been previously reacted with nitric acid, and it is preferable to use the nitrates of nickel and cobalt for convenience, with nickel nitrate being more preferred.

[0035] The solution can be prepared by mixing the metal (M), nitric acid or a nitrate, and the solvent. The order of mixing is not important, and pre-mixed and reacted materials may be used. Specifically, the following combinations are possible: a method of mixing nickel hydroxide with an aqueous nitric acid solution as a pre-mixed solution of nitric acid and a solvent; a method of mixing a metal (M) (ion) with a metal nitrate salt containing nitric acid (ion) and methanol as a pre-reacted solution of nitric acid and a metal;

[0036] (amine (A)) The amine (A) is an amine having one or two amino groups, at least one of which is selected from the group consisting of benzylamino groups and aliphatic amino groups, preferably an amine having one or two benzylamino groups, and more preferably an amine having two benzylamino groups. The amine (A) is preferably an amine having two amino groups, and is preferably a diamine. The amine (A) preferably has 3 to 8 carbon atoms, more preferably 4 to 8 carbon atoms, and even more preferably 6 to 8 carbon atoms. When the amine (A) has the above structure, the resulting catalyst has high activity and is particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions.

[0037] The amine having a benzylamino group includes at least one selected from the group consisting of xylylenediamine and benzylamine, and preferably xylylenediamine. The amine having an aliphatic amino group may be at least one selected from the group consisting of bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine. The amine (A) is preferably at least one selected from the group consisting of xylylenediamine, bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine, more preferably at least one selected from the group consisting of xylylenediamine and bis(aminomethyl)cyclohexane, and even more preferably xylylenediamine. Among the bis(aminomethyl)cyclohexanes, at least one selected from the group consisting of 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane is preferred, and 1,4-bis(aminomethyl)cyclohexane is more preferred. Among xylylenediamines, at least one selected from the group consisting of m-xylylenediamine (meta-xylylenediamine) and p-xylylenediamine (para-xylylenediamine) is preferred, and m-xylylenediamine is more preferred.

[0038] (Mixing solution and amine (A)) In this step, the solution is mixed with an amine (A) to precipitate a catalyst precursor containing the amine (A) and a metal (M).

[0039] In this step, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms), expressed as the ratio of the number of amine molecules to the number of metal atoms, is preferably 0.5 to 500, more preferably 1 to 400, even more preferably 1 to 300, still more preferably 2 to 200, and even more preferably 2 to 100. That is, in step 1, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms) is preferably 0.5 to 500, more preferably 1 to 400, even more preferably 1 to 300, still more preferably 2 to 200, still more preferably 2 to 100, still more preferably 2 to 80, and even more preferably 2 to 50. When the metal (M) is a mixture of nickel and cobalt, the molar amount of the metal (M) is the total amount of the molar amount of nickel and the molar amount of cobalt.

[0040] In particular, when the solvent is water, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms) is preferably 1 to 500, more preferably 2 to 400, even more preferably 5 to 300, still more preferably 10 to 200, and even more preferably 20 to 100. Furthermore, when the solvent is a lower alcohol, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms) is preferably 0.5 to 100, more preferably 1 to 50, even more preferably 1 to 30, still more preferably 2 to 20, and even more preferably 2 to 10. When the metal (M) is a mixture of nickel and cobalt, the molar amount of the metal (M) is the total amount of the molar amount of nickel and the molar amount of cobalt. In this step, the molar ratio of the amine (A) (in terms of amino groups) to the nitrate ions (amino groups of the amine (A) / nitrate ions) is preferably 1-3.

[0041] The mixing method in this step may be any method that allows the solution and amine (A) to be mixed well. The amine (A) may be added to the solution, or the solution may be added to the amine (A). To mix the whole, stirring or shaking may be performed. The mixing time (stirring time or shaking time) may be adjusted appropriately depending on the concentrations of the components of the solution, the type of solvent, the amount of amine (A), the temperature of the solution, etc., but is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. Mixing may be terminated when precipitation of a catalyst precursor containing amine (A) and metal (M) is completed. In this manner, a precipitate that serves as a catalyst precursor containing the amine (A) and the metal (M) can be obtained.

[0042] In this step, it is preferable to mix carbon black. That is, preferred step 1 is a step of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, nitric acid or a nitrate, carbon black, and an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. Note that carbon black may be contained in the solution. That is, step 1 may also be a step of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, carbon black, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. In this specification, the catalyst precursor does not include carbon black. When carbon black is included, the catalyst precursor is referred to as a catalyst precursor composition containing the catalyst precursor and carbon black.

[0043] Examples of carbon black that can be used in this step include furnace black, channel black, acetylene black, and thermal black, with furnace black being preferred.

[0044] The amount of carbon black is preferably 50 to 5,000 parts by mass, more preferably 100 to 3,000 parts by mass, even more preferably 100 to 2,000 parts by mass, and still more preferably 200 to 1,000 parts by mass, relative to 100 parts by mass of the metal (M) (metal element, metal ion). When carbon black is mixed, the preferred molar ratio of the amine (A) to the metal (M) is the same as above. Furthermore, when carbon black is mixed, any mixing method may be used as long as it allows the solution, carbon black, and amine (A) to be mixed well, and any component may be added first. Preferred methods include adding carbon black to the solution and then adding amine (A), and mixing the solution and amine (A) to obtain a precipitate and then adding carbon black to the resulting dispersion. Of these, the method of adding carbon black to the solution and then adding amine (A) is more preferred. To mix the entire mixture, stirring or shaking may be used. The mixing time (stirring time or shaking time) may be adjusted appropriately depending on the concentrations of the components of the solution, the type of solvent, the amount of amine (A), the type and amount of carbon black, the temperature of the solution, etc., but is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. Mixing may be terminated when precipitation of the catalyst precursor composition containing the amine (A), carbon black, and metal (M) is completed. In this manner, a precipitate that serves as a catalyst precursor composition containing the amine (A), carbon black, and metal (M) can be obtained.

[0045] The method for producing a catalyst precursor of the present invention includes, following step 1, step 3 of separating the catalyst precursor from the solution.

[0046] In this step, first, the catalyst precursor is separated from the solution. When carbon black is used in the previous step, a catalyst precursor composition containing carbon black is separated from the solution. In this case, step 3 is a step following step 1 in which the catalyst precursor composition is separated from the solution. The method for separating the catalyst precursor or catalyst precursor composition from the solution is not particularly limited, and various solid-liquid separation methods can be used, such as filtration and centrifugation. Next, an optional step 4 may be carried out. Step 4 is a drying step in which the obtained precipitate (catalyst precursor or catalyst precursor composition) is dried. Drying is preferably carried out before calcination to obtain a catalyst. There are no limitations on the drying method. In this manner, a catalyst precursor or a catalyst precursor composition can be obtained.

[0047] [Metal-carbon catalyst] The metal-carbon catalyst of the present invention is a metal-carbon catalyst containing at least one metal (M) selected from the group consisting of nickel and cobalt in an amount of 0.5 to 80 mass%, preferably 1 to 80 mass%, more preferably 10 to 80 mass%, even more preferably 15 to 80 mass%, still more preferably 20 to 80 mass%, even more preferably 30 to 80 mass%, and still more preferably 40 to 75 mass%. When the metal-carbon catalyst of the present invention contains carbon black, it is a metal-carbon catalyst that contains at least one metal (M) selected from the group consisting of nickel and cobalt in an amount of preferably 0.5 to 60 mass%, more preferably 1 to 60 mass%, even more preferably 5 to 50 mass%, still more preferably 5 to 40 mass%, still more preferably 5 to 35 mass%, and still more preferably 5 to 30 mass%. By having the above structure, the catalyst has high catalytic activity despite being inexpensive, and is particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions. The content of the metal (M) in the metal-carbon catalyst is preferably 0.5 to 80 mass %, more preferably 0.5 to 70 mass %, and even more preferably 1 to 60 mass %. The metal-carbon catalyst of the present invention has a metal-carbon bond. Therefore, the metal-carbon catalyst of the present invention is a metal-carbon catalyst that contains 0.5 to 80 mass % of at least one metal (M) selected from the group consisting of nickel and cobalt and has a bond between the at least one metal (M) selected from the group consisting of nickel and cobalt and carbon (metal (M)-carbon bond).

[0048] The metal-carbon catalyst of the present invention is preferably obtained by the above-mentioned [Method for Producing a Metal-Carbon Catalyst]. That is, the metal-carbon catalyst of the present invention is preferably a metal-carbon catalyst obtained by a production method including: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and Step 2 of subjecting the catalyst precursor to solid-liquid separation and calcining the catalyst precursor. Furthermore, it is preferable to use carbon black in Step 1. When carbon black is used, the metal-carbon catalyst of the present invention is preferably a metal-carbon catalyst obtained by a production method including: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate thereof, with carbon black and an amine (A) having one or two amino groups, at least one of which is selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black; and Step 2 of subjecting the catalyst precursor composition to solid-liquid separation and calcining the composition. [Example]

[0049] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

[0050] [Production of metal-carbon catalysts] Example 1 (Preparation of nickel-carbon catalyst) <Step 1: Catalyst Precursor Precipitation Step> Metaxylylenediamine was added to a methanol solution containing nickel nitrate at a concentration of 10 g / L in an amount twice the amount of nickel (mol / mol).The solution was then shaken at 25°C for 1 hour to obtain a precipitate. <Step 2-1: Catalyst precursor recovery step> The resulting precipitate and the solution were subjected to solid-liquid separation by filtration, and the resulting solid was dried under reduced pressure to obtain a catalyst precursor as a pale blue powder. <Step 2-2: Firing step> 0.1 g of the catalyst precursor was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Co., Ltd.) and calcined at a calcination temperature of 900°C for 15 minutes while flowing nitrogen at a rate of 100 to 200 mL / min, to obtain a nickel-carbon catalyst as a black powder.

[0051] Example 2 (Preparation of nickel-carbon catalyst) A nickel-carbon catalyst was obtained in the same manner as in Example 1, except that metaxylylenediamine in <Step 1: catalyst precursor precipitation step> of Example 1 was changed to 1,4-bis(aminomethyl)cyclohexane.

[0052] Examples 3 and 4 (Preparation of Nickel-Carbon Catalyst) A nickel-carbon catalyst was obtained in the same manner as in Example 1, except that the calcination temperature in <Step 2-2: Calcination Step> of Example 1 was changed from 900° C. to the temperatures shown in Table 2.

[0053] Example 5 (Preparation of nickel-carbon catalyst using carbon black) <Step 1: Catalyst Precursor Composition Precipitation Step> To 30 mL of a methanol solution containing 1 g / L of nickel nitrate, 50 mg of carbon black (Vulcan XC-72, manufactured by Cabot Corporation) was added, and a solution of meta-xylylenediamine (3 moles per mole) dissolved in 2 mL of methanol was added. The mixture was then shaken at 25°C for 15 minutes to obtain a precipitate. <Step 2-1: Catalyst Precursor Composition Recovery Step> The resulting precipitate and solution were subjected to solid-liquid separation by filtration, and the resulting solid was dried under reduced pressure to obtain a catalyst precursor composition as a black powder. <Step 2-2: Firing step> 0.1 g of the catalyst precursor composition was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Co., Ltd.) and calcined at a calcination temperature of 500°C for 15 minutes while flowing nitrogen at a rate of 100 to 200 mL / min, to obtain a nickel-carbon catalyst as a black powder.

[0054] Example 6 (Preparation of cobalt-carbon catalyst) <Step 1: Catalyst Precursor Precipitation Step> Metaxylylenediamine was added to a methanol solution containing 10 g / L of cobalt nitrate in an amount twice the amount of cobalt (mol / mol).The solution was then shaken at 25°C for 1 hour to obtain a precipitate. <Step 2-1: Catalyst precursor recovery step> The resulting precipitate and the solution were subjected to solid-liquid separation by filtration, and the resulting solid was dried under reduced pressure to obtain a catalyst precursor as a pale pink powder. <Step 2-2: Firing step> 0.1 g of the catalyst precursor was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Co., Ltd.) and calcined at a calcination temperature of 500°C for 15 minutes while flowing nitrogen at a rate of 100 to 200 mL / min, to obtain a cobalt-carbon catalyst as a black powder.

[0055] Example 7 (Preparation of nickel-cobalt-carbon catalyst) <Step 1: Catalyst Precursor Precipitation Step> To a methanol solution containing nickel nitrate and cobalt nitrate at concentrations of 5 g / L each, metaxylylenediamine was added in an amount (mol / mol) twice the total amount of nickel and cobalt. The solution was then shaken at 25°C for 1 hour to obtain a precipitate. <Step 2-1: Catalyst precursor recovery step> The resulting precipitate and the solution were subjected to solid-liquid separation by filtration, and the resulting solid was dried under reduced pressure to obtain a catalyst precursor as a gray powder. Here, the nickel content in the filtrate after solid-liquid separation in step 2-1 was measured using a microwave plasma atomic emission spectrometer (Agilent 4210, Agilent Technologies) and the difference X (the amount of nickel in the catalyst precursor) between the amount of nickel in the methanol solution in step 1 was calculated. The cobalt content in the filtrate after solid-liquid separation in step 2-1 was measured using the same microwave plasma atomic emission spectrometer as above and the difference Y (the amount of cobalt in the catalyst precursor) between the amount of cobalt in the methanol solution in step 1 was calculated. From the calculated difference X (the amount of nickel in the catalyst precursor) and difference Y (the amount of cobalt in the catalyst precursor), the molar ratio of nickel to cobalt in the catalyst precursor was determined to be 1:1. <Step 2-2: Firing step> 0.1 g of the catalyst precursor was placed in a tubular electric furnace (FT-02VAC-03, Furutech Co., Ltd.) and calcined at 500°C for 30 minutes while flowing nitrogen at a rate of 100–200 mL / min to obtain a black powder of nickel-cobalt-carbon catalyst.

[0056] Example 8 (Preparation of cobalt-carbon catalyst) A cobalt-carbon catalyst was obtained in the same manner as in Example 6, except that the calcination temperature in <Step 2-2: Calcination Step> of Example 6 was changed from 500°C to 900°C.

[0057] Example 9 (Preparation of nickel-cobalt-carbon catalyst) A nickel-cobalt-carbon catalyst was obtained in the same manner as in Example 7, except that the calcination temperature in <Step 2-2: Calcination Step> of Example 7 was changed from 500°C to 900°C.

[0058] Comparative Example 1 (Production of Nickel Catalyst) 0.1 g of nickel hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was calcined under the same conditions as in <Step 2-2: Calcination Step> of Example 1 to obtain a nickel catalyst.

[0059] [Catalyst analysis]

[0060] (1) Amount of metal contained in catalyst precursor The amounts of metals contained in the catalyst precursors obtained in Examples 1 to 9 were determined by thermogravimetric analysis (TG). The catalyst precursors obtained in Examples 1 to 9 were heated to 800°C at a temperature increase rate of 10°C / min while flowing air at 200 mL / min in a thermogravimetric analyzer (STA7300, manufactured by Hitachi High-Tech Science Corporation). Because the residue after heating was a metal oxide, the amount of zero-valent metal was calculated from the amount of residue and compared with the amount of the original catalyst precursor to determine the amount of metal in the catalyst precursor. The metal amount (nickel amount) contained in the catalyst precursors of Examples 1, 3, and 4 was 7.5 mass%, and the metal amount (nickel amount) contained in the catalyst precursor of Example 2 was 10 mass%. The metal amount (nickel amount) contained in the catalyst precursor of Example 5 was 6 mass%, the metal amount (cobalt amount) contained in the catalyst precursors of Examples 6 and 8 was 32 mass%, and the metal amount (nickel / cobalt amount) contained in the catalyst precursors of Examples 7 and 9 was 20 mass%.

[0061] (2) Amount of metal contained in metal-carbon catalyst The amounts of metal contained in the metal-carbon catalysts obtained in Examples 1 to 9 were determined in the same manner as above, and the values ​​of the amounts of metal contained in the catalysts of Examples 1 to 9 are shown in Tables 1 to 8.

[0062] (3) The molar ratio of the metal (M) to the amine (A) contained in the catalyst precursor (metal (M) / amine (A) The catalyst precursors obtained in Examples 1 to 9 were subjected to elemental analysis (CE-440, Exeter Analytical) to determine the proportions of carbon, nitrogen, and hydrogen. The molar ratio (metal (M) / amine (A)) was calculated from the results of the elemental analysis and the amount of metal in the catalyst precursor determined above. The molar ratio (metal (M) / amine (A)) in Examples 1, 3, and 4 was 1 / 2, and the molar ratio (metal (M) / amine (A)) in Example 2 was 1 / 2. The molar ratio (metal (M) / amine (A)) in Example 5 was 1 / 2, the molar ratio (metal (M) / amine (A)) in Examples 6 and 8 was 2 / 1, and the molar ratio (metal (M) / amine (A)) in Examples 7 and 9 was 1 / 1.

[0063] [Catalyst evaluation 1] Test Examples 1-2, 12-13 and Comparative Test Example 1 (Hydrogen Generation Test and Overvoltage Measurement (Evaluation as HER Catalyst)) 100 μL of a mixture of distilled water and 2-propanol (2:3) was added to 1 mg of the catalysts obtained in Examples 1 to 2, 6, and 7 and Comparative Example 1, and the mixture was dispersed by ultrasonic waves to obtain a dispersion. Next, the dispersion was dissolved in water at a concentration of 255 μg / cm in terms of metal. 2 Then, 5 μL of a 0.25 mass % Nafion (registered trademark) solution was applied and dried at 25° C. to coat the electrode, thereby obtaining an electrode for measurement. The hydrogen generation test and overpotential measurement were carried out using an electrochemical analyzer (ALS Model 600E, manufactured by BAS Co., Ltd.). Measurements were performed using a three-electrode system with 1M KOH solution. An alkaline reference electrode (Hg / HgO / 1M NaOH) was used as the reference electrode, a Pt coil as the counter electrode, and a rotating glassy carbon electrode (RDE) with a diameter of 5 mm as the working electrode. Measurements were performed after removing dissolved gases by bubbling nitrogen gas. The potential of the reversible hydrogen electrode (RHE) was determined by adding 0.950 V to the potential of the reference electrode. The hydrogen generation test was performed by linear sweep voltammetry (LSV) with a rotating electrode rotated at 1600 rpm. The overpotential measurement was performed with an iR guarantee (85%) to eliminate the resistance of the solution. In the hydrogen generation test, an LSV curve in which the current density decreases as the potential is swept to a lower potential is favorable. In particular, an LSV curve in which the current density decreases significantly near the potential of 0 V (RHE standard) indicates excellent hydrogen generation catalytic ability. The LSV curves of Example 1, Example 2, and Comparative Example 1 are shown in FIG. 1. Current density is -10mA / cm 2 The absolute value of the potential (based on RHE) when the hydrogen generation overvoltage is reached is the hydrogen generation overvoltage, and a lower overvoltage is better. An overvoltage of 300 mV or less is particularly superior. The results are shown in Table 1.

[0064] Test Examples 3 to 5 (Furfural Hydrogenation Reaction (Evaluation as a Hydrogenation Catalyst)) The hydrogenation of furfural to give furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) was charged with 2.5 mg of the catalyst of Example 1, 3 or 4 (as metal mass), 2 mL of 2-propanol, and 0.32 mmol of furfural, and the reactor was pressurized with hydrogen to 4 MPa and heated at 140°C for 2 hours to carry out the reaction. The ratio of each product in the resulting reaction products was calculated using deuterated chloroform as a solvent. 1 The reaction rate and selectivity were determined by H-NMR, and the results are shown in Table 2.

[0065] Test Example 6 and Comparative Test Example 2 (Hydrogenation Reaction of Furfural (Comparison with Raney Nickel)) The furfural hydrogenation reaction was carried out using the catalyst of Example 4 under the same conditions as in the example in which Raney nickel was used as a catalyst for the furfural hydrogenation reaction (Molecular Catalysis, 2018, 445, 52-60.), and the conversion rate and selectivity were compared. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) was charged with 12.6 mg of the catalyst of Example 4 or Comparative Example 2 in terms of metal mass, 1.8 mL of 2-propanol, and 0.66 mmol of furfural, and the reaction was carried out by pressurizing with hydrogen to 3 MPa and heating at 180°C for 1.25 hours. The ratio of each product in the resulting reaction products was calculated using deuterated chloroform as a solvent. 1 The reaction rate and selectivity were determined by H-NMR. An example using Raney nickel was used as Comparative Test Example 2. The results are shown in Table 3.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] As shown in Table 1, the nickel-carbon catalysts of Examples 1 and 2 had low hydrogen generation overpotentials, and in the hydrogen generation test, an LSV curve was obtained in which the current density decreased with the sweep to lower potentials, as shown in Figure 1. On the other hand, with the nickel catalyst of Comparative Example 1, which did not contain carbon, no decrease in current density was observed in the LSV curve in the hydrogen generation test of Comparative Test Example 1, as shown in Figure 1. Furthermore, as shown in Table 1, the cobalt-carbon catalyst of Example 8 and the nickel-cobalt-carbon catalyst of Example 9 also had low hydrogen generation overpotentials and decreased current densities. Therefore, it can be seen that the metal-carbon catalysts of the present invention are useful as HER catalysts. Furthermore, as shown in Table 2, the reaction rate was high in the hydrogenation reaction of furfural using the nickel-carbon catalysts of Examples 1, 3, and 4. Therefore, it is clear that the nickel catalysts of Examples 1, 3, and 4 are also useful as hydrogenation catalysts. Furthermore, it is clear that the nickel-carbon catalysts of Examples 1, 3, and 4 can selectively produce tetrahydrofurfuryl alcohol by hydrogenating furfural. Furthermore, as shown in Table 3, the nickel-carbon catalyst of Example 4 had a higher selectivity to tetrahydrofurfuryl alcohol than the Raney nickel catalyst (Comparative Example 2). This also shows that the metal-carbon catalyst of the present invention is safer and has better hydrogenation catalytic ability than the widely used Raney nickel catalyst. Thus, the metal-carbon catalyst obtained from the catalyst precursor of the present invention by the production method of the present invention does not use a precious metal, is inexpensive, and yet has high activity, making it particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions.Furthermore, the metal-carbon catalyst of the present invention does not use a precious metal, and yet has high activity, making it particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions.

[0070] [Catalyst evaluation 2] Test Examples 7 to 9 (Furfural Hydrogenation Reaction (Evaluation as a Hydrogenation Catalyst)) The hydrogenation of furfural to give furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) was charged with 2.5 mg of the catalyst of Example 4 or 5 (as metal mass), 2 mL of 2-propanol, and furfural, and the reactor was pressurized to 4 MPa with hydrogen and heated at 140°C for 2 hours to carry out the reaction. The reaction was carried out using two different amounts of furfural: 0.32 mmol (nickel / furfural (mass) ratio = 0.08) and 0.16 mmol (nickel / furfural (mass) ratio = 0.04). The ratio of each product in the resulting reaction products was calculated by the following method: 1 The reaction rate and selectivity were determined by H-NMR, and the results are shown in Table 4.

[0071] [Table 4]

[0072] As shown in Table 4, the reaction rate was high in the hydrogenation reaction of furfural using the nickel-carbon catalysts of Examples 4 and 5. Therefore, it is clear that the nickel-carbon catalysts of Examples 4 and 5 are also useful as hydrogenation catalysts. Furthermore, it is clear that the nickel-carbon catalyst of Example 5, which used carbon black, was able to hydrogenate furfural and selectively produce tetrahydrofurfuryl alcohol, despite the small amount of metal used. Thus, the metal-carbon catalyst obtained from the catalyst precursor of the present invention by the production method of the present invention does not use a precious metal, is inexpensive, and yet has high activity, making it particularly excellent as a catalyst for hydrogenation reactions.Furthermore, the metal-carbon catalyst of the present invention does not use a precious metal, is inexpensive, and yet has high activity, making it particularly excellent as a catalyst for hydrogenation reactions.

[0073] [Catalyst Evaluation 3] Test Example 10 (Furfural Hydrogenation Reaction (Evaluation as a Hydrogenation Catalyst)) The hydrogenation of furfural to give furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) was charged with 2.5 mg of the catalyst of Example 6 (as a metal mass), 2 mL of 2-propanol, and 0.32 mmol of furfural, and the reaction was carried out by pressurizing with hydrogen to 4 MPa and heating at 140°C for 2 hours. The ratio of each product in the resulting reaction products was calculated using deuterated chloroform as a solvent. 1 The reaction rate and selectivity were determined by H-NMR, and the results are shown in Table 5.

[0074] [Table 5]

[0075] As shown in Table 5, the reaction rate of furfural hydrogenation using the cobalt-carbon catalyst of Example 6 was high. Therefore, it is clear that the cobalt-carbon catalyst of Example 6 is also useful as a hydrogenation catalyst. Furthermore, it is clear that the cobalt-carbon catalyst of Example 6 can selectively produce tetrahydrofurfuryl alcohol by hydrogenating furfural. Thus, the metal-carbon catalyst obtained from the catalyst precursor of the present invention by the production method of the present invention does not use a precious metal, is inexpensive, and yet has high activity, making it particularly excellent as a catalyst for hydrogenation reactions.Furthermore, the metal-carbon catalyst of the present invention does not use a precious metal, is inexpensive, and yet has high activity, making it particularly excellent as a catalyst for hydrogenation reactions.

[0076] [Catalyst Evaluation 4] Test Example 11 (Hydrogenation reaction of furfural (Evaluation as a hydrogenation catalyst)) The hydrogenation of furfural to give furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) was charged with 2.5 mg of the catalyst of Example 7 (as a metal mass), 2 mL of 2-propanol, and 0.32 mmol of furfural, and the reaction was carried out by pressurizing with hydrogen to 4 MPa and heating at 140°C for 2 hours. The ratio of each product in the resulting reaction products was calculated using deuterated chloroform as a solvent. 1The reaction rate and selectivity were determined by H-NMR, and the results are shown in Table 6.

[0077] JPEG2025182697000006.jpg39134

[0078] As shown in Table 6, the reaction rate of furfural hydrogenation using the nickel-cobalt-carbon catalyst of Example 7 was high. Therefore, the nickel-cobalt-carbon catalyst of Example 7 is also useful as a hydrogenation catalyst. Furthermore, the nickel-cobalt-carbon catalyst of Example 7 can selectively hydrogenate furfural to produce tetrahydrofurfuryl alcohol.

[0079] [Catalyst Evaluation 5] Test Examples 14 to 19 (Hydrogenation of Furfural (Evaluation as a Hydrogenation Catalyst for Selective Hydrogenation of Unsaturated Aldehydes)) To compare the catalytic performance of the nickel-carbon catalyst in Example 4, the cobalt-carbon catalyst in Example 6, and the nickel-cobalt-carbon catalyst in Example 7 in the selective hydrogenation of unsaturated aldehydes, we evaluated the hydrogenation of furfural at relatively low temperatures to produce furfuryl alcohol and tetrahydrofurfuryl alcohol. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) was charged with 2.5 mg of the catalyst of Example 4, 6 or 7 (metal mass), 2 mL of 2-propanol, and 0.32 mmol of furfural, and the reactor was pressurized with hydrogen to 4 MPa and heated at 100°C or 120°C for 2 hours to carry out the reaction. The ratio of each product in the resulting reaction products was calculated using deuterated chloroform as a solvent. 1 The proportion of the compound present after the reaction was determined by H-NMR, and the results are shown in Tables 7 and 8.

[0080] JPEG2025182697000007.jpg63169

[0081] JPEG2025182697000008.jpg56169

[0082] As shown in Tables 7 and 8, the cobalt-carbon catalyst of Example 6 can hydrogenate furfural and selectively produce furfuryl alcohol, compared with the nickel-carbon catalyst of Example 4 and the nickel-cobalt-carbon catalyst of Example 7, regardless of whether the reaction temperature is 100°C or 120°C.

Claims

1. A method for producing a metal-carbon catalyst, comprising: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups, each of which is at least one selected from the group consisting of a benzylamino group and an aliphatic amino group, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and Step 2 of separating the catalyst precursor from the solution and calcining it.

2. 2. The method for producing a metal-carbon catalyst according to claim 1, wherein the amine (A) is a diamine.

3. 2. The method for producing a metal-carbon catalyst according to claim 1, wherein the amine (A) has 3 to 8 carbon atoms.

4. 2. The method for producing a metal-carbon catalyst according to claim 1, wherein the amine (A) is at least one selected from the group consisting of xylylenediamine, bis(aminomethyl)cyclohexane, hexamethylenediamine, 2-ethylhexylamine, and propylamine.

5. 5. The method for producing a metal-carbon catalyst according to claim 1, wherein in step 1, the molar ratio of the amine (A) to the metal (M) (number of amine molecules / number of metal atoms) is 0.5 to 500.

6. 5. The method for producing a metal-carbon catalyst according to claim 1, wherein in step 2, the calcination temperature is 250 to 1000°C.

7. A catalyst precursor comprising at least one metal (M) selected from the group consisting of nickel and cobalt, and an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups.

8. The catalyst precursor according to claim 7, containing 3 to 40 mass% of the metal (M).

9. A method for producing a catalyst precursor according to claim 7 or 8, comprising: A method for producing a catalyst precursor, comprising: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups, each of which is at least one selected from the group consisting of a benzylamino group and an aliphatic amino group, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and Step 3 of performing solid-liquid separation of the catalyst precursor.

10. A metal-carbon catalyst containing 0.5 to 80 mass % of at least one metal (M) selected from the group consisting of nickel and cobalt.

11. 11. The metal-carbon catalyst according to claim 10, obtained by a production method including: Step 1 of mixing a solution containing at least one metal (M) selected from the group consisting of nickel and cobalt, and nitric acid or a nitrate, with an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, to precipitate a catalyst precursor containing the amine (A) and the metal (M); and Step 2 of subjecting the catalyst precursor to solid-liquid separation and calcining the catalyst precursor.

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