Method for producing metal-carbon catalyst

Abstract

A method for producing a metal-carbon catalyst, the method comprising: step 1 for mixing a solution, which contains nitric acid or a nitrate and at least one metal (M) selected from the group consisting of nickel and cobalt, with 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 for separating the catalyst precursor from the solution and then firing the catalyst precursor.

Description

Method for producing metal-carbon catalyst

[0001] The present invention relates to a method for producing a metal-carbon catalyst.

[0002] In various chemical reactions, catalysts play important roles, such as promoting reactions and suppressing side reactions. In particular, precious metal catalysts, such as platinum, are widely used. Hydrogen production by water electrolysis has a very low environmental impact and is an important technology for a recycling-oriented society. The biggest challenge in water electrolysis is the high cost of hydrogen production. In this regard, the catalytic material is one of the key factors that significantly affect the overall cost. Platinum (Pt)-based catalysts for the hydrogen evolution reaction (HER) have high catalytic activity and are excellent, 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 or cobalt, including active catalytic species, and vanadium species, and the catalytic metal species and vanadium species are incorporated into the catalyst.

[0003] Hydrogenation reactions are 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.

[0004] Special Publication No. 2022-508971

[0005] As described 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, preparing a HER catalyst that combines multiple metals, as in Patent Document 1, requires a complex manufacturing process and is therefore not suitable for large-scale hydrogen production. Meanwhile, the aforementioned Raney nickel, which is particularly used as a hydrogenation catalyst, is susceptible to heat generation and fire in a dry state, requiring careful handling. Therefore, there is a need for a hydrogenation catalyst that exhibits inexpensive, highly active hydrogenation catalytic performance while also being highly safe. As described above, there is a need for a catalyst that has high activity as a HER catalyst and is inexpensive and easy to manufacture, which can also be used as a chemical reaction catalyst (e.g., a hydrogenation catalyst). Therefore, an objective of the present invention is to provide a method for manufacturing a metal-carbon catalyst that can produce an inexpensive catalyst with high catalytic activity, and a metal-carbon catalyst that is inexpensive and has high catalytic activity.

[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 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 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.

[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.

[0009] 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.

[0010] [Method for Producing Metal-Carbon Catalyst] 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 a first 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) A 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. Examples of the solvent include water and lower alcohols, preferably lower alcohols. Use of a lower alcohol can reduce the amount of amine (A) used. The lower alcohol is preferably an aliphatic alcohol having 1 to 4 carbon atoms, more preferably an aliphatic alcohol having 1 to 3 carbon atoms. Specifically, methanol, ethanol, and isopropyl alcohol are preferred, with methanol being more preferred. The solvent is preferably at least one selected from the group consisting of water and methanol, 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, more preferably a mixture of nickel and cobalt. Furthermore, from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde, the metal (M) is preferably cobalt. 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 terms of molar ratio. The metal (M) is preferably contained in the solution as a metal ion. 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 ion contained in the solution is more preferably at least one selected from the group consisting of nickel ions and a mixture of nickel ions and cobalt ions, and even more preferably a mixture of nickel ions and cobalt ions.Furthermore, from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde, the metal ion contained in the solution is more preferably cobalt ion. Furthermore, from the viewpoint of HER catalytic performance, the metal ion contained in the solution is more preferably at least one selected from the group consisting of nickel ion and a mixture of nickel ion and cobalt ion, and even more preferably nickel ion. 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 ion. The solution contains nitric acid or a nitrate salt, and preferably contains nitric acid. Even when nitric acid is contained, it is preferably contained as nitrate ion. Note that when the solvent is a lower alcohol and does not contain any water, it is possible that nitrate ion is not free. Even in such cases, it is preferable that nitrate ion is contained as a nitrate salt. The nitrate salt 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 even 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 reacted with nitric acid in advance. The use of nickel and cobalt nitrates is simple and preferred. Nickel nitrate is particularly 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 a solution that has been mixed and reacted in advance can be used. Specifically, the following combinations are possible: a method of mixing nickel hydroxide with an aqueous nitric acid solution as a solution in which nitric acid and a solvent are mixed in advance, and a method of mixing a metal nitrate salt containing the metal (M) (ion) and nitric acid (ion) with methanol as a solution in which nitric acid and a metal are reacted in advance.

[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 a benzylamino group and an aliphatic amino group, and is 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 number of carbon atoms in the amine (A) is preferably 3 to 8, more preferably 4 to 8, and even more preferably 6 to 8. When the amine (A) has the above structure, the resulting catalyst has high activity and is excellent, particularly 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 includes 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, preferably at least one selected from the group consisting of 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane, and more preferably 1,4-bis(aminomethyl)cyclohexane. 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 of Solution and Amine (A)) In this step, the solution is mixed with the amine (A) to precipitate a catalyst precursor containing the amine (A) and the 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 sum 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 sum of the molar amounts of nickel and cobalt. In this step, the molar ratio of the amine (A) (in terms of amino groups) to nitrate ions (amino groups of the amine (A) / nitrate ions) is preferably 1 to 3.

[0020] The mixing method in this step may be any method that allows for good mixing of the solution and the amine (A). The amine (A) may be added to the solution, or the solution may be added to the amine (A). The entire mixture may be stirred or shaken. The mixing time (stirring time or shaking time) may be adjusted appropriately depending on the concentration 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 the catalyst precursor containing the amine (A) and the metal (M) is complete. In this manner, a precipitate that will serve as a catalyst precursor containing the amine (A) and the metal (M) can be obtained.

[0021] In addition, it is preferable to mix carbon black in this step. That is, a 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, with carbon black and an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, thereby precipitating 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, thereby precipitating a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. Note that, 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 even more preferably 200 to 1,000 parts by mass, per 100 parts by mass of the metal (M) (metal element, metal ion). When carbon black is mixed, the preferred molar ratio of amine (A) to metal (M) is as described above. When carbon black is mixed, any method may be used as long as it allows the solution, carbon black, and amine (A) to be mixed well, and either component may be added first. Preferred methods include adding carbon black to the solution and then adding the 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 the 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 as appropriate depending on the concentration 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 upon completion of precipitation of the catalyst precursor composition containing the amine (A), carbon black, and metal (M). In this manner, a precipitate that serves as the catalyst precursor composition containing the amine (A), carbon black, and metal (M) can be obtained. A catalyst can be obtained by using the precipitate containing carbon black and calcining it as described below. The catalyst obtained in this manner has excellent catalytic activity, particularly excellent hydrogenation catalytic activity. While the reason for this is unclear, it is thought that the metal-carbon catalyst is supported on the carbon black, suppressing catalyst aggregation and increasing 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 of separating the catalyst precursor from the solution and calcining it, following step 1. Step 2 is preferably a step of separating the catalyst precursor from the solution, drying it, and calcining it, 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. There are no particular limitations on the method for separating the catalyst precursor or catalyst precursor composition from the solution, and various solid-liquid separation methods can be used. Examples include filtration and centrifugation. Next, it is preferable to dry the obtained precipitate (catalyst precursor or catalyst precursor composition). Drying is preferably performed before calcination. There are no limitations on the drying method.

[0026] Next, the catalyst precursor or catalyst precursor composition is calcined to obtain a metal-carbon catalyst. In step 2, the calcination 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 even more preferably 450 to 800°C. The calcination time may be appropriately changed depending on the calcination temperature, etc., but is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours, and even more preferably 15 minutes to 2 hours. Calcination is preferably carried out in the presence of an inert gas. Nitrogen is more preferred as the inert gas. Calcination under the above conditions can enhance the catalytic activity of the resulting catalyst.

[0027] [Catalyst precursor and method for producing catalyst precursor] The catalyst precursor of the present invention is a catalyst precursor containing 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. A 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, from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde, the metal (M) is preferably cobalt. 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, 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 number of carbon atoms in the amine (A) is preferably 3 to 8, more preferably 4 to 8, and even more preferably 6 to 8. 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 includes 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, preferably at least one selected from the group consisting of 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane, and more preferably 1,4-bis(aminomethyl)cyclohexane. 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 types 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 thereof, 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 thereof, 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 the solution) contains the metal (M), nitric acid or a nitrate, and a solvent. Examples of the solvent include water and lower alcohols, preferably lower alcohols. Use of a lower alcohol can reduce the amount of amine (A) used. The lower alcohol is preferably an aliphatic alcohol having 1 to 4 carbon atoms, more preferably an aliphatic alcohol having 1 to 3 carbon atoms. Specifically, methanol, ethanol, and isopropyl alcohol are preferred, with methanol being more preferred. The solvent is preferably at least one selected from the group consisting of water and methanol, 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, more preferably a mixture of nickel and cobalt. Furthermore, from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde, the metal (M) is preferably cobalt. 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 terms of molar ratio. The metal (M) is preferably contained in the solution as a metal ion. 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 ion contained in the solution is more preferably at least one selected from the group consisting of nickel ions and a mixture of nickel ions and cobalt ions, and even more preferably a mixture of nickel ions and cobalt ions.Furthermore, from the viewpoint of selectively obtaining an unsaturated alcohol by hydrogenating an unsaturated aldehyde, the metal ion contained in the solution is more preferably cobalt ion. Furthermore, from the viewpoint of HER catalytic performance, the metal ion contained in the solution is more preferably at least one selected from the group consisting of nickel ion and a mixture of nickel ion and cobalt ion, and even more preferably nickel ion. 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 ion. The solution contains nitric acid or a nitrate salt, and preferably contains nitric acid. Even when nitric acid is contained, it is preferably contained as nitrate ion. Note that when the solvent is a lower alcohol and does not contain any water, it is possible that nitrate ion is not free. Even in such cases, it is preferable that nitrate ion is contained as a nitrate salt. The nitrate salt 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 even 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 reacted with nitric acid in advance. The use of nickel and cobalt nitrates is simple and preferred. Nickel nitrate is particularly 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 a solution that has been mixed and reacted in advance can be used. Specifically, the following combinations are possible: a method of mixing nickel hydroxide with an aqueous nitric acid solution as a solution in which nitric acid and a solvent are mixed in advance, and a method of mixing a metal nitrate salt containing the metal (M) (ion) and nitric acid (ion) with methanol as a solution in which nitric acid and a metal are reacted in advance.

[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 a benzylamino group and an aliphatic amino group, and is 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 number of carbon atoms in the amine (A) is preferably 3 to 8, more preferably 4 to 8, and even more preferably 6 to 8. When the amine (A) has the above structure, the resulting catalyst has high activity and is excellent, particularly 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 includes 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, preferably at least one selected from the group consisting of 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane, and more preferably 1,4-bis(aminomethyl)cyclohexane. 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 of Solution and Amine (A)) In this step, the solution is mixed with the amine (A) to precipitate a catalyst precursor containing the amine (A) and the 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 sum 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 sum of the molar amounts of nickel and cobalt. In this step, the molar ratio of the amine (A) (in terms of amino groups) to nitrate ions (amino groups of the amine (A) / nitrate ions) is preferably 1 to 3.

[0041] The mixing method in this step may be any method that allows for good mixing of the solution and the amine (A). The amine (A) may be added to the solution, or the solution may be added to the amine (A). The entire mixture may be stirred or shaken. The mixing time (stirring time or shaking time) may be adjusted appropriately depending on the concentration 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 the catalyst precursor containing the amine (A) and the metal (M) is complete. In this manner, a precipitate that will serve 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, a 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, with carbon black and an amine (A) having one or two amino groups selected from the group consisting of benzylamino groups and aliphatic amino groups, thereby precipitating a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. Carbon black may also be included 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, thereby precipitating a catalyst precursor composition containing the amine (A), the metal (M), and the carbon black. In this specification, the term "catalyst precursor" does not include carbon black. When carbon black is included, the term "catalyst precursor composition" is referred to as a catalyst precursor composition containing 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 even more preferably 200 to 1,000 parts by mass, per 100 parts by mass of the metal (M) (metal element, metal ion). When carbon black is mixed, the preferred molar ratio of amine (A) to metal (M) is as described above. When carbon black is mixed, any method may be used as long as it allows the solution, carbon black, and amine (A) to be mixed well, and either component may be added first. Preferred methods include adding carbon black to the solution and then adding the 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 the 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 as appropriate 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 upon completion of precipitation of the catalyst precursor composition containing the amine (A), carbon black, and metal (M). In this manner, a precipitate that will become the 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 of separating the catalyst precursor composition from the solution following step 1. There are no particular limitations on the method for separating the catalyst precursor or catalyst precursor composition from the solution, and various solid-liquid separation methods can be used. For example, filtration or centrifugation can be used. Next, an optional step, step 4, may be performed. Step 4 is a drying step, in which the obtained precipitate (catalyst precursor or catalyst precursor composition) is dried. Drying is preferably performed before calcination to obtain the catalyst. There are no limitations on the drying method. In this manner, a catalyst precursor or 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 containing 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%, even more preferably 5 to 35 mass%, and still more preferably 5 to 30 mass%. By having the above-described 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 one 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.

[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 Catalyst] Example 1 (Production of Nickel-Carbon Catalyst) <Step 1: Catalyst Precursor Precipitation Step> Metaxylylenediamine was added in an amount (mol / mol) twice the amount of nickel relative to the amount of nickel nitrate to a methanol solution containing nickel nitrate at a concentration of 10 g / L. The mixture was then shaken at 25°C for 1 hour to obtain a precipitate. <Step 2-1: Catalyst Precursor Recovery Step> The obtained precipitate and the solution were subjected to solid-liquid separation by filtration. The obtained solid was dried under reduced pressure to obtain a bluish-white powder catalyst precursor. <Step 2-2: Calcination Step> 0.1 g of the catalyst precursor was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Corporation) 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 (Production 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> in Example 1 was changed to 1,4-bis(aminomethyl)cyclohexane.

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

[0053] Example 5 (Production of Nickel-Carbon Catalyst Using Carbon Black) <Step 1: Catalyst Precursor Composition Precipitation Step> 50 mg of carbon black (Vulcan XC-72, manufactured by Cabot Corporation) was added to 30 mL of a methanol solution containing nickel nitrate at a concentration of 1 g / L, and a solution of metaxylylenediamine dissolved in 2 mL of methanol in an amount three times the amount (mol / mol) of nickel was added thereto. The mixture was then shaken at 25°C for 15 minutes to obtain a precipitate. <Step 2-1: Catalyst Precursor Composition Recovery Step> The obtained precipitate and solution were subjected to solid-liquid separation by filtration. The obtained solid was dried under reduced pressure to obtain a black powder catalyst precursor composition. <Step 2-2: Calcination Step> 0.1 g of the catalyst precursor composition was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Corporation) and calcined for 15 minutes at a calcination temperature of 500°C while flowing nitrogen at a rate of 100 to 200 mL / min to obtain a black powder nickel-carbon catalyst.

[0054] Example 6 (Production of Cobalt-Carbon Catalyst) <Step 1: Catalyst Precursor Precipitation Step> Metaxylylenediamine was added in an amount (mol / mol) twice the amount of cobalt to a methanol solution containing cobalt nitrate at a concentration of 10 g / L. The mixture was then shaken at 25°C for 1 hour to obtain a precipitate. <Step 2-1: Catalyst Precursor Recovery Step> The obtained precipitate and the solution were subjected to solid-liquid separation by filtration. The obtained solid was dried under reduced pressure to obtain a catalyst precursor as a pale pink powder. <Step 2-2: Calcination Step> 0.1 g of the catalyst precursor was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Corporation) 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 (Production of Nickel-Cobalt-Carbon Catalyst) <Step 1: Catalyst Precursor Precipitation Step> Metaxylylenediamine was added in an amount (mol / mol) twice the total amount of nickel and cobalt to a methanol solution containing nickel nitrate and cobalt nitrate at concentrations of 5 g / L each. The mixture was then shaken at 25°C for 1 hour to obtain a precipitate. <Step 2-1: Catalyst Precursor Recovery Step> The obtained precipitate and solution were subjected to solid-liquid separation by filtration. The obtained solid was dried under reduced pressure to obtain a catalyst precursor as a gray powder. Here, the nickel in the filtrate after solid-liquid separation in step 2-1 was used as the target, and the difference X (amount of nickel in the catalyst precursor) between the amount of nickel quantified using a microwave plasma atomic emission spectrometer (Agilent 4210, manufactured by Agilent Technologies, Inc.) and the amount of nickel contained in the methanol solution in step 1 was determined. Furthermore, the cobalt in the filtrate after solid-liquid separation in step 2-1 was used as a target, and the difference Y (the amount of cobalt in the catalyst precursor) between the amount of cobalt quantified using the same microwave plasma atomic emission spectrometer as above and the amount of cobalt contained in the methanol solution in step 1 was determined. From the determined 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 found to be 1:1. <Step 2-2: Calcination Step> 0.1 g of the catalyst precursor was placed in a tubular electric furnace (FT-02VAC-03, manufactured by Furutech Corporation) and calcined at a calcination temperature of 500°C for 30 minutes while flowing nitrogen at a rate of 100 to 200 mL / min, to obtain a nickel-cobalt-carbon catalyst in the form of a black powder.

[0056] Example 8 (Production 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> in Example 6 was changed from 500°C to 900°C.

[0057] Example 9 (Production 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> in 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 amount of metal contained in the catalyst precursor obtained in Examples 1 to 9 was quantified by thermogravimetric analysis (TG). The catalyst precursor obtained in Examples 1 to 9 was heated to 800°C at a heating rate of 10°C / min while flowing air at 200 mL / min in a thermogravimetric analyzer (STA7300, manufactured by Hitachi High-Tech Science Corporation). Since 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 amount of metal (nickel amount) contained in the catalyst precursor of Examples 1, 3, and 4 was 7.5% by mass, and the amount of metal (nickel amount) contained in the catalyst precursor of Example 2 was 10% by mass. The amount of metal (nickel amount) contained in the catalyst precursor of Example 5 was 6% by mass, the amount of metal (cobalt amount) contained in the catalyst precursor of Examples 6 and 8 was 32% by mass, and the amount of metal (nickel / cobalt amount) contained in the catalyst precursor of Examples 7 and 9 was 20% by mass.

[0061] (2) Amount of Metal Included in Metal-Carbon Catalyst The amount of metal included in the metal-carbon catalysts obtained in Examples 1 to 9 was also determined in the same manner as above, and the values ​​of the amount of metal included in the catalysts of Examples 1 to 9 are shown in Tables 1 to 8.

[0062] (3) Molar ratio of metal (M) to amine (A) contained in catalyst precursor (metal (M) / amine (A)) The catalyst precursors obtained in Examples 1 to 9 were subjected to elemental analysis (CE-440, manufactured by 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 obtained here and the amount of metal in the catalyst precursor obtained 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 1-2, 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. 2The electrode was coated with 5 μL of 0.25 mass% Nafion® solution and dried at 25°C to obtain a measurement electrode. Hydrogen generation tests and overpotential measurements were performed using an electrochemical analyzer (ALS Model 600E, manufactured by BAS Corporation). Measurements were performed using a three-electrode system using 1 M KOH solution. An alkaline reference electrode (Hg / HgO / 1 M NaOH) was used as the reference electrode, a Pt coil as the counter electrode, and a 5 mm diameter glassy carbon rotating electrode (RDE) as the working electrode. Measurements were performed after removing dissolved gases by bubbling with nitrogen gas. The potential relative to the reference electrode was determined as the reversible hydrogen electrode (RHE) potential by adding 0.950 V. The hydrogen generation test was performed using a linear sweep voltammetry (LSV) test with the rotating electrode rotated at 1600 rpm. An iR guarantee (85%) was performed for overpotential measurements to eliminate solution resistance. In the hydrogen generation test, an LSV curve in which the current density decreases as the potential is swept to a lower potential is preferable. In particular, if the current density decreases significantly at a potential near 0 V (RHE standard) in the LSV curve, the hydrogen generation catalytic ability is excellent. The LSV curves of Example 1, Example 2, and Comparative Example 1 are shown in Figure 1. When the current density is -10 mA / cm ２ The absolute value of the potential (RHE standard) when the hydrogen generation overvoltage is reached is the hydrogen generation overvoltage, and a lower overvoltage is better. In particular, an overvoltage of 300 mV or less is more excellent. The results are shown in Table 1.

[0064] Test Examples 3 to 5 (Hydrogenation Reaction of Furfural (Evaluation as a Hydrogenation Catalyst)) The reaction of hydrogenating furfural to obtain furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. 2.5 mg (as metal mass) of the catalyst of Example 1, 3, or 4, 2 mL of 2-propanol, and 0.32 mmol of furfural were placed in a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industries Co., Ltd.), pressurized to 4 MPa with hydrogen, and heated at 140°C for 2 hours to carry out the reaction. The ratio of each product in the resulting reaction products was determined by the ratio of the catalyst to the catalyst in a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industries Co., Ltd.) 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 (Furfural Hydrogenation Reaction (Comparison with Raney Nickel)) A furfural hydrogenation reaction was carried out using the catalyst of Example 4 under the same conditions as in an example using Raney nickel as a catalyst for the furfural hydrogenation reaction (Molecular Catalysis, 2018, 445, 52-60.), and the conversion 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 (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 product was calculated using a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) containing deuterated chloroform as a solvent. 1 The reaction rate and selectivity were determined by H-NMR. An example using Raney nickel was designated Comparative Test Example 2. The results are shown in Table 3.

[0066]

[0067]

[0068]

[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 FIG. 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 FIG. 1 . Also, 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 is clear 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 hydrogenate furfural to produce tetrahydrofurfuryl alcohol. Furthermore, as shown in Table 3, the nickel-carbon catalyst of Example 4 had a higher tetrahydrofurfuryl alcohol selectivity than the Raney nickel catalyst (Comparative Example 2). This also demonstrates that the metal-carbon catalyst of the present invention is safer and has superior hydrogenation catalytic ability than the widely used Raney nickel catalyst. As described above, the metal-carbon catalyst obtained from the catalyst precursor of the present invention by the production method of the present invention is inexpensive and highly active without using a precious metal, and is particularly excellent as a catalyst for hydrogen generation reactions and hydrogenation reactions. Furthermore, the metal-carbon catalyst of the present invention is inexpensive and highly active without using a precious metal, and is 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 reaction of hydrogenating furfural to obtain furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. 2.5 mg of the catalyst of Example 4 or 5 (metal mass), 2 mL of 2-propanol, and furfural were placed in a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industries Co., Ltd.), 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 determined by centrifugation of 0.32 mmol (nickel / furfural (mass) ratio = 0.08) and 0.16 mmol (nickel / furfural (mass) ratio = 0.04) using deuterated chloroform as a solvent. 1 The reaction rate and selectivity were determined by H-NMR, and the results are shown in Table 4.

[0071]

[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 is inexpensive and highly active without the use of precious metals, making it particularly excellent as a catalyst for hydrogenation reactions. Furthermore, the metal-carbon catalyst of the present invention is inexpensive and highly active without the use of precious metals, 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 reaction of hydrogenating furfural to obtain furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. 2.5 mg of the catalyst of Example 6 (metal mass), 2 mL of 2-propanol, and 0.32 mmol of furfural were placed in a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.), pressurized to 4 MPa with hydrogen, and heated at 140°C for 2 hours to carry out the reaction. The ratio of each product in the resulting reaction products was determined by a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industry Co., Ltd.) 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]

[0075] As shown in Table 5, the reaction rate was high in the hydrogenation reaction of furfural using the cobalt-carbon catalyst of Example 6. 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 is inexpensive and highly active without using a precious metal, making it particularly excellent as a catalyst for hydrogenation reactions. Furthermore, the metal-carbon catalyst of the present invention is inexpensive and highly active without using a precious metal, making it particularly excellent as a catalyst for hydrogenation reactions.

[0076] [Catalyst Evaluation 4] Test Example 11 (Furfural Hydrogenation Reaction (Evaluation as a Hydrogenation Catalyst)) The reaction of hydrogenating furfural to obtain furfuryl alcohol and tetrahydrofurfuryl alcohol was evaluated. 2.5 mg of the catalyst of Example 7 (metal mass), 2 mL of 2-propanol, and 0.32 mmol of furfural were placed in a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industries Co., Ltd.), pressurized to 4 MPa with hydrogen, and heated at 140°C for 2 hours to carry out the reaction. The ratio of each product in the resulting reaction products was determined by a 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Industries Co., Ltd.) 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]

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

[0079] [Catalyst Evaluation 5] Test Examples 14 to 19 (Furfural Hydrogenation Reaction (Evaluation as a Hydrogenation Catalyst Used in the Selective Hydrogenation Reaction of Unsaturated Aldehyde)) In order to compare the hydrogenation catalytic performance of the nickel-carbon catalyst of Example 4, the cobalt-carbon catalyst of Example 6, and the nickel-cobalt-carbon catalyst of Example 7 in the selective hydrogenation reaction of unsaturated aldehyde, evaluation was carried out on the reaction of hydrogenating furfural at a relatively low temperature to obtain furfuryl alcohol and tetrahydrofurfuryl alcohol. A 20 mL portable reactor (TPR2 type, manufactured by Taiatsu Glass Kogyo Co., Ltd.) was charged with 2.5 mg of the catalyst of Example 4, 6, or 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 100°C or 120°C for 2 hours. The ratio of each product in the resulting reaction products was determined by HPLC 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]

[0081]

[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, 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); and step 2 of separating the catalyst precursor from the solution and calcining it.

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

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

4. 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. The method for producing a metal-carbon catalyst according to any one of claims 1 to 4, 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. The method for producing a metal-carbon catalyst according to any one of claims 1 to 4, 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, which contains 3 to 40 mass % of the metal (M).

9. A method for producing a catalyst precursor according to claim 7 or 8, 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, 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); 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. The metal-carbon catalyst according to claim 10, obtained by a production method 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, 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); and Step 2 of subjecting the catalyst precursor to solid-liquid separation and calcining the catalyst precursor.

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