JP7648073B2 - Nickel phosphide catalyst and method for producing hydrogenated organic compounds using the same - Google Patents

Description

The present invention relates to a catalyst containing nickel phosphide nanoparticles as an active ingredient, and a method for producing hydrogenated compounds and a method for producing ring-opened compounds using the catalyst.

When nickel or cobalt is used as a catalyst, it is known to use a sponge-like catalyst made of nickel or cobalt. Such a sponge-like catalyst is also known as a Raney catalyst (trademark registration number 3214822) (Patent Document 1, Non-Patent Document 1).

This sponge-like catalyst (hereafter referred to as "sponge catalyst") is made by dissolving and removing only the aluminum from an alloy of nickel, cobalt, and aluminum (also known as a Raney alloy) using an aqueous solution of sodium hydroxide.

Although such sponge catalysts can use the sponge metal itself as the catalyst, it is also known to further contain other elements such as manganese, copper, iron, chromium and molybdenum in order to improve the performance of the catalyst (Patent Document 2).

Specific reactions that use sponge catalysts include the hydrogenation of unsaturated compounds with double or triple bonds, aldehyde compounds, carbonyl compounds, nitrile compounds, nitro compounds, etc., the hydrogenation of aromatic compounds and heterocycles, dehalogenation, lactam purification, hydrogenolysis, reductive amination, and other hydrogenation of various organic compounds.

In addition, sponge catalysts using such elements are known to be very unstable in the atmosphere and to pose a risk of fire (Patent Document 3). For this reason, the preparation of the catalyst, the replacement of the solvent, and all steps of the reaction must be carried out in an anaerobic atmosphere, and exposure to air must be strictly avoided during storage, and the catalyst must be stored in water or alcohol. In industry, it is stored in the form of an alloy of a metal with catalytic activity, such as cobalt, and a metal that can be dissolved and removed with acids or alkalis that do not dissolve the metal.

Japanese Unexamined Patent Publication No. 6-121929 JP 2015-143194 A

Shigeo Nishimura, "Handbook of Heterogeneous Catalytic Hydrogenation for Organic Synthesis", pp. 261 - 263, John Wiley and Sons, New York, 2001

The objective of the present invention is to provide a new catalyst that solves the problems associated with sponge catalysts that have traditionally been used in the hydrogenation of organic compounds.

As a result of intensive research into solving the above problems, the inventors discovered that the above problems could be solved by using a catalyst containing nickel phosphide nanoparticles as an active ingredient, and thus completed the present invention.

In other words, the present invention is a catalyst characterized by having nickel phosphide nanoparticles as an active ingredient.

The present invention also relates to a method for producing a hydrogenated organic compound, which comprises hydrogenating an organic compound using the above catalyst.

Furthermore, the present invention relates to a method for producing a ring-opened compound, which is characterized by ring-opening a cyclic hetero compound using the above catalyst.

Furthermore, the present invention relates to a method for producing a hydrogenated ring-opened compound, which comprises carrying out hydrogenation and ring-opening of a cyclic hetero compound having an unsaturated bond in one step using the above catalyst.

The hydrogenation catalyst of the present invention is extremely stable even in the atmosphere and does not pose a risk of fire.

In addition, the method for producing a hydrogenated organic compound of the present invention can produce a hydrogenated organic compound with a high conversion rate and yield.

Furthermore, the method for producing a ring-opened compound of the present invention can produce a ring-opened compound with a high conversion rate and yield.

Furthermore, the method for producing a hydrogenated ring-opened compound of the present invention can carry out hydrogenation and ring-opening in a single step, and can produce the compound with a high conversion rate and yield.

This is a HAADF-STEM (High-Angle Annular Dark Field Scanning Transmission Electron Microscope) image of Example Catalyst 1. FIG. 1 is a diagram showing the results of X-ray diffraction (XRD) of Example Catalyst 1 and the Joint Committee of Powder Diffraction Standards (JCPDS) card [Ni ₂ P (03-953)]. An image of the locations of nickel and phosphorus observed by EDX (Energy Dispersive X-ray Spectrometry) line analysis is superimposed on a part of FIG. 1 is an image of Example Catalyst 1, in which nickel element was mapped by HAADF-STEM. 1 is an image of Example Catalyst 1, in which phosphorus element mapping was performed by HAADF-STEM. This is an image obtained by superimposing the images of FIG. 4 and FIG. 5 . This is a HAADF-STEM image of example catalyst 1'. FIG. 1 shows the results of X-ray diffraction and the JCPDS card [Ni ₂ P (03-953)] for Example Catalyst 1′. This is an image of nickel element mapping of example catalyst 1' by HAADF-STEM. 1 is an image of Example Catalyst 1' obtained by mapping phosphorus elements using HAADF-STEM. 1 is an image of Example Catalyst 1' in which nickel element and phosphorus element were mapped by HAADF-STEM. 1 is an Arrhenius plot of HMF hydrogenation using Example Catalyst 1' and Raney Nickel.

The catalyst of the present invention (hereinafter referred to as the "catalyst of the present invention") contains nickel _phosphide ( _NixPy ) nanoparticles as an active ingredient. In the present invention, the term "nanoparticles" refers to nanoparticles having an average particle size of the nano-order, preferably 1 to 500 nm, more preferably 10 to 300 nm. In the present invention, the average particle size refers to the average value of the observation results obtained by observing an arbitrary number of particles with an electron microscope such as a transmission electron microscope.

The shape of the nanoparticles is not particularly limited, but examples include spherical, elongated oval, and worm-like nanoparticles (NW).

The nickel to phosphorus ratio of the nickel phosphide ( _NixPy ) nanoparticles is preferably 1:0.3 to 1, that is, the molar ratio of phosphorus to nickel is preferably 1 or _less , and more preferably 0.8 or less. _{Nickel phosphide (NixPy ) includes Ni3P , Ni5P2 , Ni12P5} , _Ni2P , _Ni5P4 , _etc. , _{with Ni2P} and _Ni5P4 being particularly preferred.

Nickel phosphide as described above can be obtained by known methods, for example, as a precipitate from a mixed solution of a nickel compound solution and a phosphorus compound solution.

A method for obtaining such a precipitate is also described in detail in the literature (Junfeng Liu and Andreu Cabot et al, J. Mater. Chem. A, 2018, 6, 11453-11462). This method involves heating and holding a nickel salt, a component that suppresses the growth of particle size during reduction of the nickel salt, a solvent, and a phosphorus compound that is easily soluble in the solvent in an inert gas atmosphere.

The nickel salt used in the above method is not particularly limited, but is preferably one that is easy to handle. Examples of such nickel salts include _NiCl2 , Ni(acac) ₂ , and Ni( _NO3 ) ₂ .

The component that suppresses the growth of particle size when reducing the nickel salt used in the above method includes, for example, one or more capping components selected from the group consisting of compounds having an amine group, such as propylamine, butylamine, octylamine, decylamine, dodecylamine, hexadecylamine, and oleylamine, which are known to suppress the growth of metallic nickel (JP Patent Publication No. 2014-514451). At first glance, it may seem that the action of such capping components that suppress the growth of metallic nickel is different from that of nickel phosphide, since they can also suppress the particle growth of nickel phosphide, but as described below, according to the inventors' verification, it has been confirmed that the electronic state of nickel in nickel phosphide is the same as that of metallic nickel with a valence of zero, and it is believed that the particle growth during generation is suppressed by the same action as the above-mentioned suppression of the growth of metallic nickel.

The solvent used in the above method is not particularly limited, but is preferably a polar solvent with a high boiling point. Examples of such solvents include 1-octadecene.

The phosphorus compound that is easily soluble in the solvent used in the above method is not particularly limited, but is preferably one that is easy to handle. Examples of such phosphorus compounds include tertiary phosphites such as triphenyl phosphite, and tertiary phosphines such as trioctyl phosphine and triphenyl phosphine. Here, the term "easily soluble" refers to a combination of the raw material phosphorus compound and the solvent that is preferably capable of completely dissolving the raw material phosphorus compound at a heating temperature at which the Ni _x P _y precipitate is generated or lower, and for example, a combination that is capable of dissolving 14 g/L or more of the raw material phosphorus compound at 100°C is preferred.

In the above method, nickel salt, a component that inhibits the growth of particle size when the nickel salt is reduced, and a phosphorus compound that is easily soluble in the solvent are used in a molar amount of 1 to 100, preferably 10 to 50, and 1 to 100, preferably 10 to 50, of the inhibiting component and 1 to 100, preferably 10 to 50, of the phosphorus compound in a solvent, respectively, when the nickel salt is 0.1 to 10, or preferably 1 to 5, and the mixture is heated to 250 to 350°C, preferably 280 to 320°C, in an inert gas atmosphere such as argon or nitrogen, and held for about 2 to 6 hours to obtain a precipitate. This precipitate may be washed and filtered. After this washing and filtration, it may be further dried, etc.

In the above method, in order to promote the action of the catalyst of the present invention, salts of metal components such as cobalt, manganese, copper, iron, chromium, and molybdenum may be added in place of part of the nickel salt.

The catalyst of the present invention thus obtained can be used in hydrogenation and the like in place of conventional sponge catalysts. The reason for this is unclear, but it is thought that the nickel in the nickel phosphide is in the same state as metal (zero valence) and is nano-sized. There is no particular limitation on the method for obtaining the nickel phosphide of the present invention, but it can also be obtained by adjusting the amount of phosphorus compound charged as a raw material. When adjusting the amount of phosphorus compound charged in this way, the ratio [number of moles of phosphorus in the phosphorus compound/number of moles of nickel in the nickel salt] is preferably 2 to 50, more preferably 2.5 to 30, and even more preferably 5 to 25.

The catalyst of the present invention can be used not only for hydrogenation, but also for ring-opening of cyclic heterocyclic compounds. The reason for this is unclear, but it is thought that the phosphate sites on the surface of nickel phosphide promote the hydration reaction.

Furthermore, the catalyst of the present invention can simultaneously hydrogenate and open the ring of a cyclic heterocyclic compound having an unsaturated bond (this is sometimes called a "one-step reaction of hydrogenation and ring-opening"), but the reason for this is unclear.

The valence of nickel in the catalyst of the present invention can be analyzed, for example, by X-ray absorption fine structure (XAFS). Specifically, by irradiating a metal atom with high-intensity X-rays, preferably high-intensity X-rays with continuously changing energy, the inner shell electrons of the metal atom are excited to an energy level equal to or higher than the unoccupied orbital, and the excited metal atom emits a photoelectron with a kinetic energy equivalent to the difference between the excitation energy of the incident X-rays and the binding energy of the inner shell electrons. A fine structure appears near the absorption edge in the X-ray absorption spectrum of the metal atom, and the electronic state of the metal atom can be identified by analyzing this fine structure.

Within this XAFS energy range, the fine structure that appears at about 10 eV near the absorption edge is called the X-ray absorption near edge structure (XANES). XANES is caused by excitation to unoccupied orbitals, and is a spectral structure that depends on the oxidation number and coordination structure of the metal atom. The energy of the absorption edge in a XANES spectrum varies depending on the electronic state (valence) of the metal atom.

When the catalyst of the present invention was analyzed by XANES, the absorption edge energy of Ni _x P _y nanoparticles (nanoparticles of Ni ₂ P, Ni ₅ P ₄ , NiP ₂ , and NiP) was found to be between that of metallic Ni with a valence of zero and NiO, indicating that the average oxidation state of Ni species in Ni _x P _y nanoparticles is in the range of 0 to 2.18. In particular, the absorption edge energy of Ni ₂ P nanoparticles and Ni ₅ P ₄ nanoparticles is close to that of metallic Ni, suggesting that they exhibit a metallic state in air.

On the other hand, within the XAFS energy range, the modulation structure that continues from the absorption edge to the high-energy side of about 1000 eV is called the extended X-ray absorption fine structure (EXAFS). EXAFS is a vibration structure obtained due to the interaction between excited electrons and scattered electrons from nearby atoms, and the radial distribution function obtained by Fourier transform contains information about the local structure of the metal atom (surrounding atomic species, number of coordinated atoms, and interatomic distance).

When the catalysts of the present invention were analyzed by EXAFS, the Ni ₂ P nanoparticles and the Ni ₅ P ₄ nanoparticles showed two peaks at distances of 1.7 Å and 2.3 Å, which corresponded to the Ni-P bond and the Ni-Ni bond, respectively.

When the electronic state of the surface Ni and P of the catalyst of the present invention was analyzed by X-ray photoelectron spectroscopy (XPS), the Ni 2p spectrum of the Ni _2P nanoparticles mainly showed binding energy peaks of Ni 2p3/2 and Ni 2p1/2 located at 853.1 eV and 870.1 eV, which are close to the Ni 2p3/2 (852.8 eV) and Ni 2p1/2 (870.0 eV) of metallic Ni, and were consistent with the results of the XANES described above. In addition, the P 2p spectrum showed two peaks at 129.5 eV and 134.4 eV, indicating that P of different electronic states coexist on the surface of the Ni _2P nanoparticles. 129.5 eV is close to the P ⁰ peak (130.0 eV) and is thought to be 0 to 1 valence of P, and 134.4 eV is thought to be non-reduced phosphate species PO ₄ ^3- resulting from surface oxidation.

The catalyst of the present invention can be used as a hydrogenation catalyst as it is, but it is preferable to support it on a carrier, as this makes it easier to separate the catalyst from the reaction system and may improve the durability of the catalyst, which is industrially advantageous.

The carrier capable of supporting the catalyst of the present invention is not particularly limited, and various carriers having a large specific surface area and widely used for catalytic applications can be used. Examples of such carriers include inorganic oxide fine particles and activated carbon. Among these carriers, inorganic oxide fine particles are preferable. Inorganic oxide fine particles may be metal oxide fine particles such as alumina, silica, titania, zirconia, magnesia, yttrium oxide, niobium pentoxide, and mordenite, as well as combinations of these oxides and composite oxide fine particles such as hydroxyapatite (HAP), zeolite, and hydrotalcite (HT). Note that the fine particles are not particularly limited as long as they have a particle diameter larger than nano-sized nickel phosphide, and examples of such fine particles include powders with a particle diameter of about 10 to 100 μm on a volume basis and spherical particles with a particle diameter of about 0.5 to 5 mm.

The specific surface area of the carrier is not particularly limited, but is preferably, for example, 10 to 1000 ^{m 2} /g, and more preferably 100 to 500 m ² /g.

Among the carriers capable of supporting the catalyst of the present invention described above, some have a carrier effect depending on the reaction. For example, when used in a ring-opening reaction, a basic carrier such as hydrotalcite is preferred, and when used in the hydrogenation of carbonyl groups, hydrotalcite is preferred.

Furthermore, the method of supporting the catalyst of the present invention on a carrier is not particularly limited, and examples include a method of introducing a carrier into a solution containing nickel salt and phosphorus compound used in preparing nickel phosphide, impregnating the carrier with the nickel salt and phosphorus compound, and then carrying out reduction, drying, and calcination to support nickel phosphide on the carrier, a method of impregnating a carrier with a solution in which nickel phosphide nanoparticles are dispersed, and a method of mixing a carrier with a solution in which nickel phosphide nanoparticles are dispersed.

By using the catalyst of the present invention, organic compounds can be hydrogenated to produce hydrogenated organic compounds. There are no particular limitations on the hydrogenation conditions, and it is sufficient to use the catalyst of the present invention in hydrogenation using a conventional sponge catalyst. There is no need to make large-scale modifications to conventional equipment, and general-purpose synthesis equipment such as autoclaves can be used. In addition, because the catalyst of the present invention has a small particle size of nanoparticles, the yield of hydrogenated organic compounds by hydrogenation is dramatically improved.

The catalyst of the present invention is a safe alternative to conventional sponge catalysts, and is expected to be effective in all catalytic reactions that can be promoted by conventional sponge catalysts. Examples of catalytic reactions include hydrogenation of unsaturated compounds with double or triple bonds, carbonyl compounds including aldehydes and ketones, nitrile compounds, nitro compounds, etc., hydrogenation of aromatic compounds and heterocycles, dehalogenation, lactam purification, hydrogenolysis, reductive amination, and other hydrogenation reactions of various organic compounds.

Examples of organic compounds preferred for the above hydrogenation reaction and hydrogenated organic compounds produced by hydrogenation include the following.
<Organic compounds><Hydrogenated organic compounds>
Nitrile compounds Primary amine compounds Nitro compounds Primary amine compounds Carbonyl compounds Alcohol compounds Unsaturated compounds Saturated compounds

Specifically, when producing an alcohol compound by hydrogenating an aldehyde compound using the catalyst of the present invention, the aldehyde compound is hydrogenated in a wet process using the catalyst of the present invention in a heated and pressurized hydrogen-containing atmosphere.

In this reaction, the catalyst of the present invention is present in the system in an amount sufficient for hydrogenating the organic compound, and the heating conditions are 20 to 200°C, preferably 60 to 180°C, and more preferably 100 to 150°C. The pressure conditions are 0.1 to 10 MPa, and preferably 0.3 to 5 MPa. The hydrogen-containing atmosphere can be hydrogen gas or a mixture of hydrogen gas and an inert gas such as argon, and hydrogen gas or a mixture of hydrogen gas and an inert gas is preferred. The solvent for the wet condition is not particularly limited, and aprotic polar solvents such as tetrahydrofuran (THF), nonpolar solvents such as toluene, various alcohols such as 2-propanol, and protic polar solvents such as water can be used. Among these solvents, protic polar solvents are particularly preferred.

The carbonyl compound is not particularly limited, and various compounds having a carbonyl group, including an aldehyde group or a ketone group, can be used.

In addition, by using the catalyst of the present invention, it is possible to produce ring-opened compounds by hydrolyzing cyclic hetero compounds. There are no particular limitations on the ring-opening conditions, and it is sufficient to use the catalyst of the present invention. There is no need to make large-scale modifications to conventional equipment, and general-purpose synthesis equipment such as autoclaves can be used. In addition, the catalyst of the present invention has a small particle size of nanoparticles, which dramatically improves the yield.

Organic compounds suitable for the ring-opening reaction may have a structure that allows hydration of the α-carbon of the heterocycle, and examples of such compounds include hexoses such as 5-hydroxymethylfurfural (HMF), 5-methylfurfuryl alcohol, glucose, sucrose, lactose, trehalose, maltose, mannose, galactose, fructose, sorbose, and tagatose, pentoses such as arabinose, xylose, ribose, xylulose, and ribulose, and monosaccharides and polysaccharides such as pentosan, xylan, saccharose, starch, and cellulose. Of these, HMF, methylfurfuryl alcohol, glucose, sucrose, lactose, trehalose, and maltose are preferred.

In this reaction, the catalyst of the present invention is present in the system in an amount sufficient for ring-opening of the organic compound, and the heating conditions are 20 to 200°C, preferably 60 to 180°C, and more preferably 100 to 150°C. The pressure conditions are 0.1 to 10 MPa, and preferably 0.3 to 5 MPa. The atmosphere can be an inert gas such as nitrogen or argon, a mixed gas of these, or air. The solvent for the wet condition is not particularly limited, and aprotic polar solvents such as tetrahydrofuran (THF), nonpolar solvents such as toluene, various alcohols such as 2-propanol, and protic polar solvents such as water can be used. Among these solvents, protic polar solvents are particularly preferred.

Furthermore, if the catalyst of the present invention is used, for example, if the cyclic hetero compound has an unsaturated bond, the above-mentioned hydrogenation reaction and ring-opening reaction can be carried out in one step. In that case, it is sufficient that hydrogen necessary for the hydrogenation reaction is present in the system.

When it is assumed that the catalyst of the present invention is used for industrial purposes, the reaction apparatus used is not particularly limited, and it can be used in various industrial equipment. Such industrial reaction apparatus can be broadly classified into batch type (also called batch type) and continuous type. Batch type reactors are often used in laboratory facilities, where the steps of introducing the substrate and catalyst, reaction, and separation and recovery of the product are carried out one by one in sequence. In contrast, continuous type reactors are widely used as industrial equipment, and can carry out each reaction step continuously and simultaneously, making them an industrially advantageous reaction apparatus suitable for mass production.

Continuous reactors can be broadly divided into two types: fluidized bed reactors and fixed bed reactors. In a fluidized bed reactor, the catalyst is mixed in a suspended state with the reactants, including the substrate, which is advantageous in terms of ease of contact between the reactant molecules and the catalytic active sites, but after the reaction, the catalyst and the product must be separated. In addition, because the catalyst must be suspended as particles, the catalyst particles used have a small particle size.

On the other hand, in a fixed bed reactor, only the reactants move as a fluid through the reactor, and the catalyst is fixed in the reactor. The reactants react as they pass through the fixed catalyst bed to obtain a product. The resulting product is discharged from the reactor separated from the catalyst. For this reason, there is no need to remove the catalyst from the reaction system after the reaction, making it suitable for continuous operation and suitable for industrial use. In a fixed bed reactor, the reactants need voids to pass through the catalyst bed at an appropriate flow rate, and the catalysts used in fixed bed reactors are often molded into granular or honeycomb shapes, or granular or honeycomb-shaped carriers on which the catalyst of the present invention is supported or impregnated.

Furthermore, reactions using such equipment can be divided into liquid-phase and gas-phase reactions. Liquid-phase reactions are carried out by bringing a mixture of reactants or a substrate and a solvent into contact with a catalyst while still in liquid form. Liquid-phase reactions do not require vaporization of the reactants or reaction solution, which reduces the energy required for the reaction. On the other hand, in gas-phase reactions, the reactants are gaseous, which makes it easier for the molecules required for the reaction to collide with each other, resulting in superior reaction speeds.

Considering the reactor and reaction mechanism, it is preferable to use the catalyst of the present invention in a gas phase reaction using a fixed bed reactor.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, the yields in the following examples were determined by quantitative analysis using gas chromatography (GC) with an internal standard method.

Example catalyst 1
Preparation of _Ni2P nanoparticles:
Nickel chloride (NiCl ₂ ) (1 mmol), hexadecylamine (10 mmol), 1-octadecene (10 mL), and triphenyl phosphite (10 mmol) were added to a Schlenk flask and stirred in vacuum at 120°C for 1 hour. After removing impurities, moisture, and oxygen, the mixture was stirred at 300°C for 2 hours under an argon atmosphere to obtain a black colloidal solution. The mixture was then precipitated with acetone, filtered, washed several times with a mixed solvent of chloroform and acetone, and the resulting powder was dried overnight under vacuum to obtain Ni ₂ P nanoparticles. The Ni ₂ P nanoparticle catalyst prepared in this embodiment was a regular particle with an average diameter of 5.4 nm and a narrow size distribution (±1.4 nm). The HAADF-STEM image of the example catalyst 1 is shown in Figure 1. The obtained example catalyst 1 was left to dry in the air for a day, but no ignition occurred as is feared with sponge catalysts.

Example catalyst 2
Preparation of _{Ni5P4 nanoparticles} :
Ni(acac) ₂ (0.33 mmol) and oleylamine (0.5 mmol) were dissolved in n-octyl ether (4.7 mL), trioctylphosphine (11 mmol) was added, and the mixture was stirred in vacuum at 120°C for 1 hour. After removing impurities, moisture, and oxygen, the mixture was stirred in an argon atmosphere at 400°C for 20 hours to obtain a black colloidal solution. The mixture was then precipitated with acetone, filtered, washed several times with a mixed solvent of chloroform and acetone, and the obtained powder was dried overnight under vacuum to obtain _{Ni5P4 nanoparticles} .

Example catalyst 3
Preparation of _Ni2P /mordenite:
22 mg of Example Catalyst 1 obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour, mordenite (1 g) was added as a carrier, and the mixture was stirred at room temperature for 6 hours. After filtration and washing, the mixture was dried in vacuum to obtain Example Catalyst 3 of the present invention.

Example Catalyst 4
Preparation of _Ni2P / _SiO2 :
Example Catalyst 4 of the present invention was obtained in the same manner as Example Catalyst 3, except that _SiO2 was used as the carrier instead of mordenite.

Example Catalyst 5
Preparation of _Ni2P /ZSM-5:
Example Catalyst 5 of the present invention was obtained in the same manner as Example Catalyst 3, except that ZSM-5 was used as the carrier instead of mordenite.

Example Catalyst 6
Preparation of _NiP2 nanoparticles:
Ni(acac) ₂ (0.33 mmol) and oleylamine (0.5 mmol) were dissolved in n-octyl ether (2.0 mL), trioctylphosphine (16 mmol) was added, and the mixture was stirred in vacuum at 120°C for 1 hour. After removing impurities, moisture, and oxygen, the mixture was stirred in an argon atmosphere at 400°C for 20 hours to obtain a black colloidal solution. The mixture was then precipitated with acetone, filtered, washed several times with a mixed solvent of chloroform and acetone, and the obtained powder was dried overnight under vacuum to obtain _NiP2 nanoparticles.

Comparative Example Catalyst 1
_Ni2P :
Reagent Ni ₂ P was obtained from the market and used as Comparative Example Catalyst 1.

Comparative Example Catalyst 2
_Co2P nanoparticles:
Cobalt chloride (CoCl ₂ ) (1.0 mmol), hexadecylamine (10 mmol), triphenyl phosphite (10 mmol), and 1-octadecene (10.0 mL) were added to a Schlenk flask and stirred. The mixture was heated to 150°C for 1 hour under argon flow. The temperature was then raised to the solvent boiling point (about 290°C) over 20 minutes, maintained for 2 hours, cooled to 200°C, and then rapidly cooled to room temperature in a water bath to obtain a black product. The obtained black product was washed with acetone, precipitated, collected, and further washed with chloroform and acetone to obtain Comparative Example Catalyst 2.

Test Example 1
Hydrogenation reaction:
The hydrogenation reaction was carried out in an autoclave. 6 mol% _Ni2P /mordenite catalyst, 10 ml of water, and 0.1 mmol of the substrate 3-hexene-2,5-dione were added to the autoclave, and the following reaction was carried out under a hydrogen pressure atmosphere of 2 MPa and 100°C for 1 hour, resulting in a yield of 96%.

The above results confirm that the catalyst of the present invention can produce hydrogenated compounds in high yields even under low hydrogen pressure conditions.

Test Example 2
Ring-opening reaction:
The following reaction was carried out in the same manner as in Test Example 1, except that the substrate was 0.25 mmol of 5-methylfurfuryl alcohol and the hydrogen was replaced by a 1 MPa nitrogen atmosphere, and the yield was 41%.

The results of Test Example 2 confirmed that the catalyst of the present invention can be useful in the ring-opening reaction of cyclic hetero compounds.

Test Example 3
One-step hydrogenation and ring-opening reaction:
The following reaction was carried out in the same manner as in Test Example 2, except that the nitrogen was replaced by a 2 MPa hydrogen atmosphere, and the yield was 79%.

The results of Test Example 3 demonstrated that the catalyst of the present invention can efficiently carry out the hydrogenation and ring-opening reaction of cyclic hetero compounds having unsaturated bonds in a single step.

Test Example 4
Substrate diversity:
The following reaction was carried out in the same manner as in Test Example 3 except that the substrate was changed to HMF (5-hydroxymethylfurfural), and the yield was 84%.

Test Example 5
Catalysts and diverse supports:
The following reaction was carried out in the same manner as in Test Example 3, except that the substrate was 5-methylfurfural, the reaction temperature was 130° C., and the reaction time and catalyst were changed as shown in Table 1. The results are shown in Table 1.

From Table 1, it was found that the reaction hardly proceeded with powdered Ni ₂ P or Co ₂ P nanoparticles, whereas the reaction proceeded with the Ni _x P _y nanoparticle catalyst and the catalyst in which Ni _x P _y nanoparticles were supported on a carrier, and showed high conversion and yield. It was also found that the performance of the catalyst was high when the molar ratio of phosphorus in the Ni _x P _y nanoparticles to nickel was 1 or less, preferably 0.8 or less.

Test Example 6
Catalyst durability:
In order to evaluate the durability of the catalyst of the present invention, the catalyst used in the reaction of Example 4 in Table 1 was filtered, and then the same reaction as that in the above-mentioned catalyst comparison was repeated to verify the durability of the catalyst of the present invention. The results are shown in Table 2.

The results in Table 2 show that the catalyst of the present invention has excellent durability.

In addition, structural analysis was performed on the catalyst of the present invention. The results are shown in FIG. 2. FIG. 2 shows the results of X-ray diffraction for Example Catalyst 1 and the JCPDS card [Ni ₂ P (03-953)]. The vertical bar graph in FIG. 2 shows the Ni ₂ P peaks listed on the JCPDS card. In Example Catalyst 1 of the present invention, a characteristic peak of Ni ₂ P powder was confirmed. This shows that Example Catalyst 1 contains Ni ₂ P. Similarly, the structures of Example Catalysts 2 and 6 were identified from the results of X-ray diffraction and the JCPDS card, and it was confirmed that they contain Ni ₅ P ₄ and NiP ₂ , respectively.

Figure 3 is an image of part of Figure 1 superimposed with an image of the locations of Ni and P observed by EDX (Energy Dispersive X-ray Spectrometry) line analysis. From this result, it was found that Ni and P elements are uniformly distributed in one nanoparticle of Example Catalyst 1.

Figures 4 and 5 are images of element mapping performed by HAADF-STEM. Figure 4 is an image showing the distribution of Ni elements, Figure 5 is an image showing the distribution of P elements, and the image on the right of Figure 6 is a combined image of the Ni element distribution and the P element distribution. From these results, it was found that Ni elements and P elements are distributed roughly uniformly without bias in Example Catalyst 1.

The results of analysis by XRD and HAADF-STEM showed that the example catalyst 1 had a nano-sized crystal structure with Ni ₂ P as a constituent element and a regular shape.

Example catalyst 1'
Preparation of _Ni2P NWs (worm-like nanoparticles):
Nickel acetylacetonate (Ni(acac) ₂ ) (1 mmol), hexadecylamine (10 mmol), and triphenyl phosphite (10 mmol) were added to a Schlenk flask and stirred at 120°C in vacuum for 1 hour. After removing impurities, moisture, and oxygen, the mixture was stirred at 315°C for 2 hours under an argon atmosphere to obtain a black colloidal solution. The resulting mixture was then cooled to room temperature, acetone was added, the resulting precipitate was filtered, and the powder was washed several times with a mixed solvent of chloroform and acetone (1:1) and dried overnight under vacuum to obtain Ni ₂ P NW. The Ni ₂ P NW catalyst prepared in this embodiment had a unique worm-like nanostructure with a length of 25 nm and a width of 3 nm that was regularly formed. The HAADF-STEM image of Example Catalyst 1' is shown in FIG. 7. The obtained Example Catalyst 1 was left to dry in the air for one day, but no ignition occurred as is feared with sponge catalysts.

In addition, structural analysis was performed on Example Catalyst 1'. The results are shown in Figure 8. Figure 8 is a diagram showing the results of X-ray diffraction for Example Catalyst 1' and the JCPDS card [Ni ₂ P (03-953)]. The vertical bar graph in Figure 8 shows the Ni ₂ P peaks listed on the JCPDS card. A peak characteristic of Ni ₂ P powder was confirmed in Example Catalyst 1' of the present invention. This shows that Example Catalyst 1' contains Ni ₂ P.

Figures 9, 10, and 11 are images of element mapping performed by HAADF-STEM. Figure 9 is an image showing the distribution of Ni elements, Figure 10 is an image showing the distribution of P elements, and Figure 11 is an image combining the Ni element distribution and the P element distribution. From these results, it was found that Ni elements and P elements are distributed roughly uniformly without bias in Example Catalyst 1.

The results of the analysis using HAADF-STEM showed that the example catalyst 1 had a nano-sized crystal structure with Ni ₂ P as a constituent element and a regular shape.

Example Catalyst 7
Preparation of _Ni2P /HT:
30 mg of Example Catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour, hydrotalcite (AD-500NS: 1 g, manufactured by Tomita Pharmaceutical Co., Ltd.) was added as a carrier, the mixture was stirred at room temperature for 6 hours, filtered and washed, and then vacuum dried to obtain Example Catalyst 7 of the present invention.

Example Catalyst 8
Preparation of _Ni2P / _TiO2 :
30 mg of Example Catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour, _TiO2 (JRC TIO-4: 1 g, manufactured by Fuji Silysia Chemical Ltd.) was added as a carrier, the mixture was stirred at room temperature for 6 hours, filtered and washed, and then vacuum dried to obtain Example Catalyst 8 of the present invention.

Example Catalyst 9
Preparation _{of Ni2P} / _Y2O3 :
30 mg of the example catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour. Then, 1 _g of _Y2O3 (manufactured by Wako Pure Chemical Industries, Ltd.) was added as a carrier, and the mixture was stirred at room temperature for 6 hours. The mixture was filtered, washed, and then vacuum dried to obtain an example catalyst X of the present invention.

Example Catalyst 10
Preparation of _Ni2P / _ZrO2 :
30 mg of the example catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour. _ZrO2 (JRC ZRO-6: 1 g, manufactured by Fuji Silysia Chemical Ltd.) was added as a carrier, and the mixture was stirred at room temperature for 6 hours. After filtration and washing, the mixture was dried in vacuum to obtain example catalyst 10 of the present invention.

Example Catalyst 11
Preparation _{of Ni2P} / _Al2O3 :
30 mg of Example Catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour. Al ₂ O ₃ (AKP-G015: 1 g, manufactured by Sumitomo Chemical Co., Ltd.) was added as a carrier, and the mixture was stirred at room temperature for 6 hours. The mixture was filtered, washed, and then vacuum dried to obtain Example Catalyst 11 of the present invention.

Example Catalyst 12
Preparation _{of Ni2P} / _Nb2O5 :
30 mg of the example catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour. Nb ₂ O ₅ (manufactured by Wako Pure Chemical Industries, Ltd.: 1 g) was added as a carrier, the mixture was stirred at room temperature for 6 hours, filtered and washed, and then vacuum dried to obtain example catalyst 12 of the present invention.

Example Catalyst 13
Preparation of _Ni2P / _SiO2 :
30 mg of Example Catalyst 1' obtained by the above procedure was added to hexane (50 mL) and subjected to ultrasonic treatment for 1 hour, _SiO2 (1 g) was added as a carrier, the mixture was stirred at room temperature for 6 hours, filtered and washed, and then vacuum dried to obtain Example Catalyst 13 of the present invention.

Test Example 7
Hydrogenation of carbonyl groups (support effect):
The hydrogenation reaction of the carbonyl group was carried out in an autoclave. 10 mol% of each catalyst, 3 mL of water, and 0.5 mmol of the substrate were added to a 50 mL stainless steel autoclave, and the reaction was carried out at 100°C for 1 hour under a pressurized hydrogen atmosphere of 2 MPa. The results are shown in Table 3.

Test Example 8
Catalyst durability:
After the Ni ₂ P/HT reaction in Table 3 (yield 93%), the catalyst was separated by centrifugation, washed with deionized water, and the reaction was repeated. The yields were 93% in the first run, 94% in the second run, 92% in the third run, 93% in the fourth run, and 90% in the fifth run.

Test Example 9
Hydrogenation of carbonyl groups:
The hydrogenation reaction of the carbonyl group was carried out in an autoclave using Example Catalyst 7 ( _Ni2P /HT catalyst). 1.5 mol% (41.8 mg), 6 mol% (167 mg), or 12 mol% (333 mg) of _Ni2P /HT catalyst, 3 mL of water, and 0.1 mmol of substrate were added to a 50 mL stainless steel autoclave, and the reaction was then carried out under the conditions shown in the table below in a pressurized hydrogen atmosphere. The results are shown in Table 4.

In addition, the catalyst turnover frequency in the hydrogenation of HMF in Example 30 (60° C., H ₂ 5 MPa, water 1 mL) was 14.4 for Ni ₂ P/HT of Example Catalyst 7, while it was 0.64 for the Raney nickel catalyst, which was 22 times higher.

The Arrhenius plots for the hydrogenation of HMF are shown in Figure 12. From the slopes of the Arrhenius plots, the activation energies were calculated to be 37.9 kJ/mol for Ni ₂ P/HT and 53.7 kJ/mol for Raney nickel.

Test Example 10
Hydrogenation of the nitrile group:
The hydrogenation reaction of the nitrile group was carried out in an autoclave. 5 mol % (7.4 mg) of _Ni2P NW catalyst, 3 mL of ammonia water (NH3 _aq .), and 0.5 mmol of substrate were added to a 50 mL stainless steel autoclave, and the reaction was then carried out under the conditions shown in the table below in a pressurized hydrogen atmosphere. The results are shown in Table 5.

Test Example 11
Hydrogenation of the nitrile group:
The hydrogenation reaction of the nitrile group was carried out in an autoclave. 5 mol % Ni of each catalyst, 3 mL of 12.5% aqueous ammonia (NH ₃ aq.), and 0.5 mmol of the substrate were added to a 50 mL stainless steel autoclave, and the reaction was then carried out under conditions of a 4 MPa hydrogen pressure atmosphere at 130° C. for 6 hours. The results are shown in Table 6.

Test Example 12
Hydrogenation of the nitro group:
The hydrogenation reaction of the nitro group was carried out in an autoclave. 5 mol % Ni (7.4 mg) of Example Catalyst 1' (Ni ₂ P NW catalyst), 3 mL of water, and 0.5 mmol of the substrate were added to a 50 mL stainless steel autoclave, and the reaction was carried out under the conditions shown in the table below in a pressurized hydrogen atmosphere. The results are shown in Table 7.

The results in Table 7 show that the catalyst of the present invention was able to selectively hydrogenate only the nitro group, while functional groups including halogen, methoxy, amino, ester, amide, and hydroxyl groups were not hydrogenated.

Test Example 13
Ring-opening and hydrogenation reactions of monosaccharides (glucose):
The hydrogenation reaction of monosaccharides was carried out in an autoclave. 0.5 mmol of D-glucose as a substrate, 200 mg of the catalyst shown in Table 8 with an active ingredient (as Ni) of 6.6 mol % (6.6 mol %), and 3 mL of water were added to a 50 mL stainless steel autoclave, and the reaction was carried out under the conditions shown in the table below in a pressurized hydrogen atmosphere. The results are shown in Table 8.

The results in Table 8 show that the catalyst of the present invention induces ring-opening reactions (hydrolysis) and hydrogenation reactions of monosaccharides such as glucose in excellent yields, and produces very little by-products.

Test Example 14
Catalyst durability:
After the reaction (yield 99%) was carried out under the conditions of Example 84 in Table 8, the catalyst was centrifuged, and the substrate and solvent were added to the obtained catalyst and the reaction was repeated. As a result, the yield was 99% in the first run, 99% in the second run, 98% in the third run, 98% in the fourth run, and 97% in the fifth run.

The above results demonstrate that the catalyst of the present invention has excellent durability.

Test Example 15
Ring-opening and hydrogenation reaction of polysaccharide (maltose):
Hydrogenation of polysaccharides was carried out in an autoclave. 0.25 mmol of maltose as a substrate, a catalyst with an active ingredient (as Ni) of 6.6 mol% shown in Table 9, and 3 mL of water were added to a 50 mL stainless steel autoclave, and the reaction was carried out under the conditions shown in the table below in a pressurized hydrogen atmosphere. The results are shown in Table 9.

The results in Table 9 show that the catalyst of the present invention can bring about ring-opening reactions (hydrolysis) and hydrogenation reactions of monosaccharides such as glucose with excellent yields.

Test Example 16
Catalyst durability:
After the reaction was carried out under the conditions of Example 94 in Table 9, the catalyst was centrifuged, and the substrate and solvent were added to the obtained catalyst and the reaction was carried out repeatedly. As a result, the yield was 94% in the first run, 94% in the second run, 93% in the third run, 93% in the fourth run, and 94% in the fifth run.

The above results demonstrate that the catalyst of the present invention has excellent durability.

The catalyst of the present invention can be used in the hydrogenation and ring-opening reactions of organic compounds simply by replacing the conventional, dangerous sponge catalysts, without requiring large-scale modifications to conventional equipment. This makes it a valuable technology that can be easily applied industrially.

Claims (7)

A catalyst containing nickel phosphide nanoparticles as an active ingredient,
Nickel phosphide nanoparticles are supported on inorganic oxide fine particles,
the inorganic oxide fine particles are one selected from yttrium oxide, mordenite and hydrotalcite;
The molar ratio of phosphorus to nickel in the nickel phosphide nanoparticles is 1 or less;
A catalyst for hydrogenating an organic compound, comprising: A catalyst containing nickel phosphide nanoparticles as an active ingredient,
Nickel phosphide nanoparticles are supported on inorganic oxide fine particles,
the inorganic oxide fine particles are one selected from yttrium oxide, mordenite and hydrotalcite;
The molar ratio of phosphorus to nickel in the nickel phosphide nanoparticles is 1 or less;
A catalyst for ring-opening of a cyclic hetero compound, comprising: A catalyst containing nickel phosphide nanoparticles as an active ingredient,
Nickel phosphide nanoparticles are supported on inorganic oxide fine particles,
the inorganic oxide fine particles are one selected from yttrium oxide, mordenite and hydrotalcite;
The molar ratio of phosphorus to nickel in the nickel phosphide nanoparticles is 1 or less;
A catalyst for one-step reaction of hydrogenating and ring-opening a cyclic hetero compound having an unsaturated bond, characterized in that A method for producing a hydrogenated organic compound, comprising hydrogenating an organic compound using the catalyst for hydrogenating an organic compound according to claim 1. A method for producing a hydrogenated organic compound, comprising hydrogenating the organic compound using the hydrogenation catalyst according to claim 1 in a heated and pressurized hydrogen-containing atmosphere. A method for producing a ring-opened compound, comprising opening the ring of a cyclic hetero compound using the ring-opening catalyst for a cyclic hetero compound according to claim 2. A method for producing a hydrogenated ring-opened compound, comprising carrying out hydrogenation and ring-opening in one step using a catalyst for one-step hydrogenation and ring-opening of a cyclic hetero compound having an unsaturated bond as described in claim 3.

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