Precious metal-Ni coexistence supported catalyst prepared based on Ni-MOF metal node partial reduction, preparation method and application

Abstract

The invention discloses a noble metal-Ni coexistence supported catalyst prepared on the basis of Ni-MOF metal node part reduction, a preparation method and application, a carrier of the catalyst is Ni-MOF, the Ni-MOF is a porous metal organic framework material constructed by combining Ni ions with an organic ligand, the organic ligand is an organic molecule containing carboxyl and hydroxyl, and the noble metal-Ni coexistence supported catalyst is a noble metal-Ni coexistence supported catalyst prepared on the basis of Ni-MOF metal node part reduction. The carrier is loaded with at least one kind of noble metal nano particles coexisting with Ni nano particles, and the noble metal nano particles are noble metal nano particles with hydrogenation activity. The preparation method comprises the following steps: by taking a porous material Ni-MOF as a catalyst carrier, introducing a noble metal nanoparticle precursor into a pore channel of the Ni-MOF carrier through a solution impregnation method, then removing a solvent of an impregnation system, carrying out vacuum drying, and reducing the noble metal precursor in the pore channel of the Ni-MOF into the noble metal nanoparticles under a high-temperature hydrogen condition. The catalyst provided by the invention shows excellent carbon-carbon double bond hydrogenation activity and selectivity in a heterogeneous selective hydrogenation reaction of unsaturated aldehyde ketone.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a supported metal nanocatalyst with a metal-organic framework (MOF) as a carrier, and in particular to a noble metal-Ni coexisting supported catalyst prepared based on partial reduction of Ni-MOF metal nodes, a preparation method and application thereof. Background Art

[0002] Selective hydrogenation of organic compounds containing multiple unsaturated bonds (containing two or more unsaturated bonds such as C=C, C=O, C≡C, C≡N, NO2, etc.) using supported noble metal catalysts has always been a fascinating but challenging topic, not only because organic compounds containing multiple unsaturated bonds are ideal models for studying the "structure-activity relationship" of catalysts to develop better catalysts, but also because their semi-hydrogenated products are extremely important in the actual production of fine chemicals (such as pharmaceutical intermediates, flavors, perfumes, etc.). The activity and selectivity of supported noble metal catalysts are closely related to the surface electronic / geometric structure of noble metal nanoparticles. Currently, a variety of strategies have been developed to regulate the surface structure of supported noble metal nanoparticles, such as adjusting their morphology and particle size, incorporating heteroatoms, strengthening metal-support interactions, and partially covering the surface of noble metal nanoparticles with organic ligands or pores or cages of porous materials. Although the above strategies have been successfully used in the design and preparation of selective hydrogenation catalysts, the current efficient development of supported precious metal catalysts still faces a dilemma, namely, how to improve the selectivity of semi-hydrogenated target products without inhibiting the catalytic hydrogenation activity.

[0003] There are different types of active sites on the surface of metal nanoparticles, such as edges, faces, corners, steps, metal-support interfaces, etc. Different active sites have different hydrogenation activities for different unsaturated bonds. The reaction pathway that the catalytic hydrogenation process goes through mainly depends on the adsorption mode of the reaction substrate on the surface of the supported precious metal nanoparticles. Accurately controlling the adsorption mode of the reaction substrate and guiding its adsorption and activation on a specific metal surface is conducive to improving the selectivity of the target product without sacrificing catalytic activity. Therefore, how to accurately control the adsorption mode of the reaction substrate on the metal particles is extremely important but extremely challenging. For example, our research group has reported that the phosphine ligand modified in mesoporous silica can produce a weak interaction with the carboxylic acid group of benzoic acid, thereby directly inducing the aromatic ring to preferentially adsorb on the surface of ruthenium nanoparticles, thereby improving the hydrogenation activity of benzoic acid.

[0004] Metal-organic frameworks (MOFs) are a new class of porous crystalline materials that connect metal nodes with multidentate organic ligands through strong coordination bonds to form an ordered framework structure. MOF metal nodes play a crucial role in the directional adsorption and interaction with reaction substrates or products, so the hydrogenation selectivity can be improved by regulating the metal nodes. For example, Tang and his collaborators achieved highly selective hydrogenation of cinnamaldehyde molecules by encapsulating Pt in the sandwich structure MIL-101(Cr)@Pt@MIL-101(Fe). The ultra-high C=O bond hydrogenation selectivity originates from the fact that the MOF metal nodes preferentially interact with C=O bonds rather than C=C bonds, making the hydrogenation of the embedded Pt nanoparticles to the former a thermodynamically favorable reaction, thereby significantly improving its catalytic selectivity (Nature, 2016, Vol. 539, pp. 76-80). However, it cannot be ignored that the above high selectivity is achieved at the expense of hydrogenation activity. Inspired by this, rationally regulating the valence state of MOF metal nodes and realizing the synergistic regulation of the adsorption mode and hydrogen dissociation ability of the reaction substrate by precious metal nanoparticles and metal nodes is beneficial to improving the hydrogenation selectivity of the target product without inhibiting its activity. However, there are few reports on the precise regulation of the valence state of the metal nodes of MOF-based supported precious metal catalyst carriers, especially the partial reduction of the metal nodes of MOF carriers to metal nanoparticles to participate in catalytic reactions. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a noble metal-Ni coexistence supported catalyst prepared by partial reduction of Ni-MOF metal nodes, a preparation method and application, and the prepared catalyst has excellent carbon-carbon double bond hydrogenation activity and selectivity in the selective hydrogenation reaction of unsaturated aldehydes and ketones. Compared with the preparation method of the currently reported MN-Ni supported catalyst, the preparation method of the present invention is simple and efficient, has superior catalytic performance, and has better practical application prospects.

[0006] To achieve the above object, the technical solution adopted by the present invention is a catalyst for the selective hydrogenation of unsaturated aldehydes and ketones, wherein the carrier of the catalyst is Ni-MOF, which is a porous metal organic framework material constructed by Ni ions combined with organic ligands, wherein the organic ligands are organic molecules containing carboxyl, hydroxyl, phosphonic acid or nitrogen-containing heterocyclic coordination functional groups, and at least one noble metal nanoparticle coexists with Ni nanoparticles on the carrier, and the noble metal nanoparticles are noble metal nanoparticles with hydrogenation activity. The noble metal nanoparticles and Ni nanoparticles are loaded in the Ni-MOF pores.

[0007] The carrier of the catalyst of the present invention is a different type of Ni-based metal organic framework porous material. The catalyst contains Ni nanoparticles and at least one noble metal nanoparticle. The noble metal nanoparticles are at least one of Pt, Pd, Rh, Ir and Ru. The loading amount of the noble metal nanoparticles is 0.1-10 wt%. The Ni nanoparticles are derived from the partial reduction of Ni nodes in the Ni-MOF skeleton, that is, the Ni in the catalyst is derived from the partial precipitation of Ni metal nodes in the Ni-MOF. The preparation method is an induced precipitation method of high-temperature hydrogen reduction followed by impregnation.

[0008] In one embodiment of the present invention, the loading amount of the noble metal nanoparticles is 0.1-10 wt %.

[0009] In one embodiment of the present invention, the noble metal nanoparticles are Pt, Pd, Rh, Ir or Ru.

[0010] In one embodiment of the present invention, the organic ligand of the Ni-MOF is an organic molecule containing a main skeleton and at least one terminal functional group capable of coordinating with metal ions. The main skeleton is usually 1-11 conjugated rings or a hydrocarbon group containing 1-8 carbon atoms, and the main skeleton also contains one or more organic functional groups R. The terminal functional groups capable of coordinating with metal ions are carboxyl groups, hydroxyl groups, phosphonic acid groups, and nitrogen-containing heterocycles.

[0011] In one embodiment of the present invention, the organic ligand has a structural formula as shown in Formula 1-7: ; Among them, R1-R 16 It is any one of H, F, Cl, Br, I, OH, OCH3, OCH2CH3, CN, CH3, CH2CH3, CHO, NH2, NO2, SH, and SO3H.

[0012] A method for preparing a catalyst for selective hydrogenation of unsaturated aldehydes and ketones. The method uses a porous material Ni-MOF as a catalyst carrier, introduces a noble metal nanoparticle precursor into the Ni-MOF carrier pores by a solution impregnation method, removes the solvent of the impregnation system, performs vacuum drying, and reduces the noble metal precursor in the Ni-MOF pores to noble metal nanoparticles under high temperature and hydrogen conditions, while the Ni nodes in the Ni-MOF skeleton are partially reduced to Ni nanoparticles, thereby obtaining a multiphase hydrogenation catalyst in which noble metal nanoparticles and Ni nanoparticles coexist.

[0013] In one embodiment of the present invention, the preparation method can be specifically performed according to the following steps: Step 1, synthesis of Ni-MOF carrier: after mixing nickel salt solution and organic ligand solution, perform solvothermal or hydrothermal reaction at a specific temperature to obtain porous material Ni-MOF catalyst carrier.

[0014] Step 2: Impregnation of precious metal precursor: Disperse the Ni-MOF carrier in an appropriate amount of solvent, add the precious metal nanoparticle precursor solution drop by drop into the Ni-MOF dispersion, and introduce the precious metal precursor into the pores of the Ni-MOF carrier by solution impregnation.

[0015] Step 3, desolventizing and drying the catalyst precursor: using a rotary evaporator to remove the solvent in the noble metal precursor impregnation system, and vacuum drying to obtain a Ni-MOF-based catalyst precursor loaded with the noble metal precursor.

[0016] Step 4, high-temperature reduction of the catalyst: The Ni-MOF-based catalyst precursor is placed in a high-temperature hydrogen atmosphere for reduction, and the precious metal precursor in the Ni-MOF pores is reduced to precious metal nanoparticles. At the same time, the Ni nodes in the Ni-MOF skeleton are partially reduced to Ni nanoparticles, and a precious metal-Ni coexisting loaded Ni-MOF-based catalyst can be obtained.

[0017] Furthermore, in step 1, the nickel salt is one or a mixture of two or more of nickel nitrate, nickel acetate, nickel chloride or nickel sulfate.

[0018] Furthermore, in step 1, the organic ligand is an organic molecule containing a main skeleton and at least one terminal functional group that can coordinate with metal ions. The main skeleton is usually 1-11 conjugated rings or a hydrocarbon group containing 1-8 carbon atoms, and the main skeleton also contains one or more organic functional groups. The terminal functional groups that can coordinate with metal ions are carboxyl, hydroxyl, phosphonic acid, and nitrogen-containing heterocycles. The organic ligand is one of them or a mixture of two or more thereof.

[0019] Furthermore, in step 1, the solvent is one or a mixture of two or more of N,N-dimethylformamide, methanol, ethanol or water.

[0020] Furthermore, in step 1, the solvent thermal or hydrothermal reaction temperature is room temperature 20 to 180° C., and the reaction time is 1 to 72 h.

[0021] In one embodiment of the present invention, the precious metal precursor is one or a mixture of two or more of chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, sodium chloropalladate, palladium chloride, palladium acetate, rhodium chloride, iridium acetylacetonate, and ruthenium chloride.

[0022] In one embodiment of the present invention, the solvent used in the solution impregnation method is one or a mixture of two or more of water, methanol, ethanol, n-hexane, dichloromethane, and tetrahydrofuran.

[0023] In one embodiment of the present invention, the concentration of the noble metal precursor solution is 1-5 mM, the amount of solvent is 0-50 ml of solvent per 0.1 g of Ni-MOF carrier, the amount of solvent is not 0, the immersion time of the noble metal precursor in the Ni-MOF dispersion is 1-48 h, and the immersion temperature is 20-50°C.

[0024] In one embodiment of the present invention, the noble metal precursor is reduced to metal nanoparticles under high temperature and hydrogen conditions, the hydrogen reduction temperature is 100-300°C, and the reduction time is 1-5 h. The ratio of H2 / H2 in the reducing hydrogen atmosphere is 5%-100%, the inert gas is Ar or N2, the total weight of the catalyst is 100%, and the metal nanoparticle loading is 0.1wt%-10wt%. During the reduction process, the noble metal nanoparticles induce the partial reduction of the metal nodes on the Ni-MOF carrier to Ni nanoparticles.

[0025] In one embodiment of the present invention, the vacuum drying time is 4-24 h, and the drying temperature is room temperature to 80°C.

[0026] The use of the unsaturated aldehydes and ketones selective hydrogenation catalyst in the selective hydrogenation of unsaturated aldehydes and ketones, wherein the unsaturated aldehydes and ketones are molecules containing both a C=C bond and a C=O bond. Preferably, the unsaturated aldehydes and ketones are cinnamaldehyde. The catalyst of the present invention exhibits excellent carbon-carbon double bond hydrogenation activity and selectivity in the multiphase selective hydrogenation reaction of unsaturated aldehydes and ketones.

[0027] This technical solution has the following beneficial effects: The catalyst provided by the present invention has the following advantages: 1. The catalyst carrier has a high specific surface area and a large pore size, which is conducive to the adsorption and transfer of substrate molecules and hydrogen molecules on the carrier and the diffusion of product molecules; 2. The structure, morphology, pore size, etc. of the Ni-MOF carrier are highly adjustable, which is conducive to the shape-selective adsorption of the reaction substrate on the carrier, thereby improving the hydrogenation selectivity of specific unsaturated bonds; 3. The different types of functional groups contained in MOF carriers are conducive to the rational modification and regulation of catalyst surface properties, thereby improving catalyst activity and selectivity; 4. The noble metal nanoparticles and Ni nanoparticles on the catalyst have a synergistic effect, which is conducive to the reversal of the hydrogenation selectivity of different types of unsaturated functional groups; The catalyst preparation method provided by the present invention has the following advantages: 1. Simple method: The preparation process is simple and efficient, with low requirements for instruments and equipment. The noble metal precursor is introduced into the Ni-MOF pores by a simple solution impregnation method, and high-temperature hydrogen reduction can obtain the noble metal-Ni coexisting supported Ni-MOF-based catalyst; 2. Strong designability: There are many types of organic ligands available for synthesizing Ni-MOF. Different organic ligands can be selected to synthesize Ni-MOF according to the differences in catalytic substrate molecules to obtain catalyst carriers with specific morphology, structure and pore size. Different functional groups can be introduced into the carrier by post-modification methods to expand the universality of the catalyst. 3. Strong controllability: By adjusting the type of precious metal precursor, different precious metal nanoparticles can be introduced into the pores of the MOF carrier. By adjusting the amount of precious metal precursor, reduction temperature, reduction time, etc., the ratio and size of precious metal nanoparticles and Ni nanoparticles can be adjusted, thereby adjusting the catalytic activity and selectivity. 4. Large-scale preparation is possible: The Ni-MOF carrier synthesis method used in the method of the present invention is simple and has a high yield. The organic ligand used is relatively cheap, which is suitable for large-scale industrial preparation and has potential industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the application of the noble metal-Ni coexistence supported Ni-MOF-based catalyst prepared by the present invention in the selective hydrogenation reaction of unsaturated aldehydes and ketones; Figure 2 The XRD and SEM of the Pt / Ni-MOF-74 catalyst prepared in Example 1 are shown in FIG. Figure 2 (a) is the XRD pattern. Figure 2 (b) is the SEM image; Figure 3 TEM of the Pt / Ni-MOF-74 catalyst prepared in Example 1; Figure 4 This is the XPS of the Pt / Ni-MOF-74 catalyst prepared in Example 1; Figure 5 The XRD and SEM of the Pt / Ni-CAT-1 catalyst prepared in Example 5 are shown in FIG. Figure 5 (a) is the XRD pattern. Figure 5 (b) is the SEM image; Figure 6 The Pt / Ni-MOF-74 catalyst prepared in Example 1 with different Pt loadings was used for the selective hydrogenation performance test of the C=C bond of cinnamaldehyde; Figure 7 The Pt / Ni-CAT-1 catalyst prepared in Example 5 was used for the selective hydrogenation performance test of the C=C bond of cinnamaldehyde; Figure 8 The Pt / Ni-MOF-74 catalyst prepared in Example 1 was used to test the selective hydrogenation performance of C=C bonds of other unsaturated aldehydes and ketones. DETAILED DESCRIPTION

[0029] Below is a combination of the embodiments and Figures 1 to 8 The present invention is further described.

[0030] The schematic diagram of the application of the noble metal-Ni coexistence supported Ni-MOF-based catalyst prepared by the present invention in the selective hydrogenation reaction of unsaturated aldehydes and ketones is shown in FIG. Figure 1 Unless otherwise specified, the reagents involved in the embodiments of the present invention are all commercially available products and can be purchased through commercial channels.

[0031] Example 1

[0032] 200 mg Ni-MOF-74 (synthesis method referenced from Inorganic Chemistry, 2014, Vol. 53, pp. 5881-5883) was dispersed in 15 ml methanol, and 5 mL chloroplatinic acid methanol solution (containing 4.20 mg chloroplatinic acid) was added dropwise to the Ni-MOF-74 dispersion, and stirred at 50°C for 24 h to allow the noble metal precursor to adsorb into the MOF pores. The above sample was rotary evaporated and vacuum dried for 6 h, and then reduced at 200°C for 2 h under 100% H2 atmosphere to obtain a Pt / Ni-MOF-74 catalyst with a Pt loading of 1wt%, labeled as 1.0%Pt / Ni-MOF-74.

[0033] The supported 1.0%Pt / Ni-MOF-74 catalyst was characterized by powder X-ray diffraction (XRD). Figure 2 The results show that the XRD peak position of the catalyst is consistent with the simulated spectrum of Ni-MOF-74. Figure 1The XRD pattern showed that the catalyst still maintained the same crystal structure as the original Ni-MOF, that is, the high-temperature hydrogen reduction conditions would not cause significant damage to the Ni-MOF-74 carrier. The XRD spectrum did not show the diffraction peak of Pt nanoparticles at 39.8°, indicating that the loaded Pt nanoparticles were small in size and evenly dispersed on the Ni-MOF carrier. The XRD spectrum showed a small diffraction peak at 44.5°, corresponding to the diffraction peak of the Ni(111) crystal plane, indicating that Ni nanoparticles existed in the 1.0%Pt / Ni-MOF-74 catalyst. The size of the Ni nanoparticles was calculated to be about 7 nm using the Scherrer formula, which means that the precious metal Pt precursor was reduced to Pt nanoparticles while the Ni-MOF metal nodes were also partially reduced to Ni nanoparticles, and the partial reduction of the Ni nodes did not lead to the collapse of the overall skeleton structure of Ni-MOF. The scanning electron microscope (SEM) image results showed that ( Figure 2 In (b) above, the 1.0% Pt / Ni-MOF-74 catalyst is a nanosphere formed by the accumulation of nanosheets of about 100 nm. The size of a single nanosphere is several microns. After the catalyst is loaded with Pt and Ni nanoparticles, it still maintains the same morphology as Ni-MOF-74. The partial analysis of the metal node Ni does not destroy its intrinsic morphology.

[0034] Transmission electron microscopy (TEM) images show that ( Figure 3 ), no obvious agglomerated metal nanoparticles appeared on the catalyst surface, indicating that the Pt and Ni nanoparticles were evenly dispersed on the catalyst carrier. From the 0.226 nm lattice fringes, it was confirmed that the Pt nanoparticles with exposed (111) crystal planes existed on the Ni-MOF-74 carrier, and their size was about 2 nm. From the 0.203 nm lattice fringes, it was confirmed that the Ni nanoparticles with exposed (111) crystal planes coexisted with the Pt nanoparticles on the carrier, and the size of the Ni nanoparticles was about 7 nm, which was consistent with the particle size results calculated by XRD data and Scherrer formula. The above results all indicate that Pt nanoparticles and Ni nanoparticles exist on the Ni-MOF-74 carrier at the same time, and there is a certain distance between the two metal nanoparticles.

[0035] X-ray photoelectron spectroscopy (XPS) shows the different valence states of Ni and Pt elements (such as Figure 4 (a) and Figure 4As shown in (b) in the XPS spectrum of Ni 2p, the peak at 852.9 eV belongs to 0-valent Ni, the peak at 856.7 eV belongs to 2-valent Ni, and the two small peaks on the left are satellite peaks of 2-valent Ni. From the spectrum, it can be seen that the 2-valent Ni metal nodes in Ni-MOF-74 are partially reduced to 0-valent under high-temperature hydrogen reduction conditions and transformed into Ni metal nanoparticles. In the XPS spectrum of Pt 4f, the binding energies at 71.5 eV and 74.8 eV correspond to 0-valent Pt, and 72.1 eV and 75.2 eV correspond to 2-valent Pt. This shows that the 4-valent Pt in the Pt precursor chloroplatinic acid 4+ Under high temperature hydrogen reduction conditions, it is completely reduced to low-valent Pt δ+ and 0-valent Pt 0 , and transformed into Pt metal nanoparticles. This is consistent with the XRD and TEM results, further confirming that the Ni metal nodes in Ni-MOF-74 are partially reduced to Ni nanoparticles by Pt nanoparticles, and Pt nanoparticles and Ni nanoparticles coexist on the catalyst support.

[0036] Example 2

[0037] This example is basically the same as Example 1, except that the amount of the precious metal precursor chloroplatinic acid added is 2.10 mg, the precious metal Pt loading is 0.5%, and the catalyst is labeled as 0.5% Pt / Ni-MOF-74. The XRD results show that the catalyst structure has not changed significantly, and the XRD spectrum shows the diffraction peak of Ni nanoparticles, but the peak intensity is relatively low, indicating that the precious metal Pt is reduced while the Ni-MOF metal node is also partially reduced, and the reduction amount of Ni nanoparticles is slightly reduced ( Figure 2 ).

[0038] Example 3

[0039] This example is basically the same as Example 1, except that the amount of the precious metal precursor chloroplatinic acid added is 6.30 mg, the precious metal Pt loading is 1.5%, and the catalyst is labeled as 1.5% Pt / Ni-MOF-74. XRD results show that the catalyst still maintains the pore structure of the original Ni-MOF, and the diffraction peak of Ni nanoparticles also appears. The peak intensity of Ni nanoparticles is relatively high, indicating that the precious metal Pt is reduced while the Ni-MOF metal nodes are also partially reduced, and the reduction amount of Ni nanoparticles is slightly increased ( Figure 2 ).

[0040] Example 4

[0041] This example is basically the same as Example 1, except that the added precious metal precursor solution is 5 mL of sodium chloropalladate methanol solution (containing 5.53 mg of sodium chloropalladate), the precious metal Pd loading is 1.0%, and the catalyst is labeled 1.0% Pd / Ni-MOF-74.

[0042] Example 5

[0043] The preparation process of Example 1 was adopted, except that the carrier used was another Ni-based MOF, Ni-CAT-1 (the synthesis method is referenced from Advanced Science, 2020, Vol. 7, p. 1903003), the precious metal Pt loading was 1.0%, and the catalyst was labeled as 1.0% Pt / Ni-CAT-1. Figure 5 (a) and Figure 5 As shown in (b), the XRD results of 1.0% Pt / Ni-CAT-1 catalyst indicate that the catalyst still maintains a pore structure consistent with the original Ni-CAT-1. The reduction of the diffraction peak originates from the influence of Pt nanoparticles in the MOF pores. Loading of precious metal precursors and high-temperature reduction will not significantly destroy the Ni-CAT-1 support structure.

[0044] Example 6

[0045] The performance evaluation of the prepared catalyst was illustrated by the selective hydrogenation of cinnamaldehyde, a typical unsaturated aldehyde and ketone substrate model molecule. The hydrogenation reaction was carried out in a 300 mL stainless steel reactor. 3 mg of the 1.0% Pt / Ni-MOF-74 catalyst prepared in Example 1, 40 mg of cinnamaldehyde, 40 mg of undecane, 0.3 ml of water, and 1.7 ml of isopropanol were placed in a 5 mL ampoule, and the reactor was sealed. The air remaining in the reaction system was replaced with H2 5 times, and the reaction was carried out at 70 °C and 2 MPa H2 for a specific time, wherein undecane was used only as an internal standard. After the reaction was completed, the solid catalyst was filtered out and 0.50 mL of the reaction solution was diluted to 1 mL with isopropanol solvent for gas chromatography analysis. The conversion rate and selectivity of the catalytic reaction were obtained by quantitative analysis of the substrate and product based on the gas chromatographic peak area. Its performance test is as follows Figure 6 As shown, the results show that when the Pt loading is 1 wt%, the conversion rate is close to 100% in 64 minutes, and the selectivity of carbon-carbon double bond hydrogenation products is as high as 89%, showing excellent catalytic performance.

[0046] Example 7

[0047] The 0.5% Pt / Ni-MOF-74 prepared in Example 2 was used as a catalyst to evaluate the selective hydrogenation performance of cinnamaldehyde. Figure 6As shown in the figure, when the precious metal Pt loading is 0.5 wt%, the conversion rate can reach more than 97% in 40 min, and the selectivity is about 87%, indicating that the loading amount of precious metal nanoparticles has a great influence on the catalytic activity and selectivity.

[0048] Example 8

[0049] The 1.5% Pt / Ni-MOF-74 prepared in Example 3 was used as a catalyst to evaluate the selective hydrogenation performance of cinnamaldehyde. Figure 6 As shown in the figure, when the precious metal Pt loading is 1.5 wt%, the conversion rate can reach more than 98% in 130 min, and the selectivity is about 86%, which further confirms that the loading amount of Pt nanoparticles has a significant effect on the catalytic activity and selectivity.

[0050] Example 9

[0051] The 1.0% Pd / Ni-MOF-74 prepared in Example 4 was used as a catalyst to evaluate the selective hydrogenation performance of cinnamaldehyde. The performance test results showed that when a noble metal Pd with a loading amount of 1 wt% was used as the catalyst active center, the conversion rate was 27% after 20 minutes of reaction, and the selectivity of C=C hydrogenation products was as high as more than 95%. This shows that other noble metal nanoparticles such as Pd also have excellent catalytic hydrogenation performance.

[0052] Example 10

[0053] The performance of the selective hydrogenation of cinnamaldehyde was evaluated by using the Pt / Ni-CAT-1 prepared in Example 5 as a catalyst. Figure 7 As shown in the figure, when the precious metal Pt loading is 1.0 wt%, the conversion rate can reach 100% in 135 min, and the selectivity of carbon-carbon double bond hydrogenation products is as high as 87%, showing excellent catalytic performance. It also shows that the change of Ni-MOF carrier type will also have a significant effect on catalytic activity and selectivity.

[0054] Embodiment 11

[0055] The 1.0% Pt / Ni-MOF-74 prepared in Example 1 was used as a catalyst to evaluate the performance of selective hydrogenation of other unsaturated aldehydes and ketones. The catalytic reaction conditions of Example 6 were used. The difference was that the unsaturated aldehydes and ketones used were other types of molecules containing both C=C bonds and C=O bonds, such as 4-chlorocinnamaldehyde, 4-methoxycinnamaldehyde, p-methylcinnamaldehyde, 4-fluorocinnamaldehyde, and 3-methyl-2-butenal. Its performance test is as follows Figure 8As shown, the conversion rate of 4-chlorocinnamaldehyde reached 90.6% after 65 minutes of reaction, and the C=C hydrogenation selectivity reached 90.7%; the conversion rates of 4-methoxycinnamaldehyde, p-methylcinnamaldehyde, and 4-fluorocinnamaldehyde were 96.1%, 90.6%, and 97.9% respectively after 38 minutes of reaction, and the corresponding selectivities were 89.7%, 89.0%, and 90.4% respectively; 3-methyl-2-butenal showed the highest catalytic activity, with a conversion rate of 97.4% and a selectivity of 96.4% after 30 minutes of reaction. The above unsaturated aldehyde and ketone catalytic performance results all show that the catalyst prepared by the present invention has excellent catalytic performance and catalytic substrate universality for selective hydrogenation of C=C bonds.

[0056] The above specific embodiments are only used to illustrate the present invention rather than to limit the present invention. Any changes and substitutions made to the present invention without creative work within the scope of protection of the present invention and the claims shall fall within the scope of protection of the patent of the present invention.

Claims

1. A catalyst for the selective hydrogenation of unsaturated aldehydes and ketones, characterized in that: The carrier of the catalyst is Ni-MOF, which is a porous metal organic framework material constructed by Ni ions combined with organic ligands, wherein the organic ligands are organic molecules containing carboxyl, hydroxyl, phosphonic acid or nitrogen heterocyclic coordination functional groups, and at least one noble metal nanoparticle coexists with Ni nanoparticles on the carrier, wherein the noble metal nanoparticles are noble metal nanoparticles with hydrogenation activity, and both the noble metal nanoparticles and the Ni nanoparticles are loaded in Ni-MOF pores.

2. The unsaturated aldehyde and ketone selective hydrogenation catalyst according to claim 1, characterized in that The loading amount of the noble metal nanoparticles is 0.1-10 wt %.

3. The unsaturated aldehyde and ketone selective hydrogenation catalyst according to claim 1, characterized in that The noble metal nanoparticles are Pt, Pd, Rh, Ir or Ru.

4. The unsaturated aldehyde and ketone selective hydrogenation catalyst according to claim 1, characterized in that The organic ligand of the Ni-MOF is an organic molecule containing a main skeleton and at least one terminal functional group capable of coordinating with metal ions. The main skeleton is usually 1-11 conjugated rings or a hydrocarbon group containing 1-8 carbon atoms, and the main skeleton also contains one or more organic functional groups R. The terminal functional groups capable of coordinating with metal ions are carboxyl, hydroxyl, phosphonic acid, and nitrogen-containing heterocycles.

5. The unsaturated aldehyde and ketone selective hydrogenation catalyst according to claim 4, characterized in that The organic ligand structural formula is shown in Formula 1-7: ； Among them, R1-R 16 Each of them is selected from any one of H, F, Cl, Br, I, OH, OCH3, OCH2CH3, CN, CH3, CH2CH3, CHO, NH2, NO2, SH, and SO3H.

6. A method for preparing a catalyst for selective hydrogenation of unsaturated aldehydes and ketones, characterized in that: Using the porous material Ni-MOF as the catalyst carrier, the precursor of the precious metal nanoparticles is introduced into the pores of the Ni-MOF carrier by solution impregnation method, and then the solvent of the impregnation system is removed, vacuum drying is performed, and the precious metal precursor in the Ni-MOF pores is reduced to precious metal nanoparticles under high temperature and hydrogen conditions. At the same time, the Ni nodes in the Ni-MOF skeleton are partially reduced to Ni nanoparticles, and a multiphase hydrogenation catalyst in which precious metal nanoparticles and Ni nanoparticles coexist can be obtained.

7. The preparation method according to claim 6, characterized in that: The noble metal precursor is one or a mixture of two or more of chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, sodium chloropalladate, palladium chloride, palladium acetate, rhodium chloride, iridium acetylacetonate, and ruthenium chloride.

8. The preparation method according to claim 6, characterized in that: The solvent used in the solution impregnation method is one or a mixture of two or more of water, methanol, ethanol, n-hexane, dichloromethane, and tetrahydrofuran; the concentration of the noble metal precursor solution is 1-5 mM, the amount of solvent is 0-50 ml of solvent per 0.1 g of Ni-MOF carrier, and the amount of solvent is not 0; the immersion time of the noble metal precursor in the Ni-MOF dispersion is 1-48 h, and the immersion temperature is 20-50°C.

9. The preparation method according to claim 6, characterized in that: The noble metal precursor is reduced into noble metal nanoparticles under high temperature and hydrogen conditions, the hydrogen reduction temperature is 100-300°C, and the reduction time is 1-5 h.

10. Use of the unsaturated aldehyde or ketone selective hydrogenation catalyst according to any one of claims 1 to 5 in the selective hydrogenation of unsaturated aldehydes or ketones, wherein the unsaturated aldehyde or ketone is a molecule containing both a C=C bond and a C=O bond.

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