Noble metal-Ni co-existing supported catalyst prepared by partial reduction of Ni-MOF metal nodes, preparation method and application

Abstract

The present invention discloses a noble metal-Ni co-existing supported catalyst prepared by partial reduction of the metal nodes of Ni-MOF, a preparation method and an application thereof. The carrier of the catalyst is Ni-MOF, and the Ni-MOF is a porous metal-organic framework material constructed by binding Ni ions with organic ligands. The organic ligand is an organic molecule containing carboxyl and hydroxyl groups. At least one kind of noble metal nanoparticles co-exist with Ni nanoparticles on the carrier, and the noble metal nanoparticles are noble metal nanoparticles with hydrogenation activity. The preparation method uses the porous material Ni-MOF as the catalyst carrier, introduces the noble metal nanoparticle precursor into the pores of the Ni-MOF carrier by the solution impregnation method, then removes the solvent of the impregnation system, dries it under vacuum, and reduces the noble metal precursor in the pores of the Ni-MOF to noble metal nanoparticles under high-temperature hydrogen conditions. The catalyst of the present invention exhibits excellent carbon-carbon double bond hydrogenation activity and selectivity in the heterogeneous selective hydrogenation reaction of unsaturated aldehydes and ketones.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a supported metal nanocatalyst with a metal-organic framework (Metal-Organic Framework, MOF) as a carrier, and particularly relates to a noble metal-Ni co-existing supported catalyst prepared by partial reduction of a Ni-MOF metal node, a preparation method thereof, and an application thereof. Background Art

[0002] The use of supported noble metal catalysts for the selective hydrogenation reaction of organic compounds containing multiple unsaturated bonds simultaneously (two or more of C=C, C=O, C≡C, C≡N, NO 2 etc. unsaturated bonds) has always been an attractive but extremely challenging topic. This is 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-hydrogenation products are of extremely important significance in the actual production of the fine chemical industry (such as pharmaceutical intermediates, fragrances, perfumes, etc.). The activity and selectivity of supported noble metal catalysts are closely related to the surface electron / 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, doping heteroatoms, strengthening the metal-support interaction, and partially covering the surface of noble metal nanoparticles with organic ligands or the pores or cages of porous materials. Although the above strategies have been successfully used in the design and preparation of selective hydrogenation catalysts, the efficient development of current supported noble metal catalysts still faces a dilemma, that is, how to improve the selectivity of semi-hydrogenation 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 experienced during the catalytic hydrogenation process mainly depends on the adsorption mode of the reaction substrate on the surface of supported noble metal nanoparticles. Precisely regulating the adsorption mode of the reaction substrate and guiding its adsorption and activation on a specific metal surface is beneficial to improving the selectivity of the target product without sacrificing the catalytic activity. Therefore, how to precisely control the adsorption mode of the reaction substrate on metal particles is extremely important but extremely challenging. For example, our research group has reported that phosphine ligands modified in mesoporous silica can have a weak interaction with the carboxylic acid group of benzoic acid, and then directly induce 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 class of emerging porous crystalline materials, which form an ordered framework structure by connecting metal nodes with polydentate organic ligands through strong coordination bonds. The metal nodes of MOFs play a crucial role in the directional adsorption and interaction with reaction substrates or products. Therefore, the hydrogenation selectivity can be improved by regulating the metal nodes. For example, Tang and his collaborators achieved highly selective hydrogenation of cinnamaldehyde molecules through Pt encapsulated in the sandwich structure MIL-101(Cr)@Pt@MIL-101(Fe). The ultra-high hydrogenation selectivity of the C=O bond stems from the fact that the MOF metal nodes preferentially interact with the C=O bond rather than the C=C bond, making the hydrogenation of the former by the embedded Pt nanoparticles a thermodynamically favorable reaction, thereby significantly improving its catalytic selectivity (Nature, 2016, Vol. 539, pp. 76-80). However, it should not be ignored that the acquisition of the above high selectivity is based on the sacrifice of hydrogenation activity. Inspired by this, rationally regulating the valence state of MOF metal nodes to achieve the synergistic regulation of the adsorption mode of reaction substrates and the hydrogen dissociation ability by noble metal nanoparticles and metal nodes is beneficial to improving the hydrogenation selectivity of target products without inhibiting their activity. However, there are few reports on the precise regulation of the valence state of the carrier metal nodes of MOF-based supported noble metal catalysts, especially the work in which the MOF carrier metal nodes are partially reduced to metal nanoparticles and participate in the catalytic reaction. Summary of the Invention

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

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

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

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

[0009] In one embodiment of the present invention, the noble metal nanoparticle is 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 group capable of coordinating with metal ions is carboxyl, hydroxyl, phosphonic acid group, or nitrogen-containing heterocycle.

[0011] In one embodiment of the present invention, the structural formula of the organic ligand is shown in Formulas 1-7:

[0012] ;

[0013] Among them, R 1 -R 16 are respectively H, F, Cl, Br, I, OH, OCH 3 , OCH 2 CH 3 , CN, CH 3 , CH 2 CH 3 , CHO, NH 2 , NO 2 , SH, SO 3 H, any one of them.

[0014] A preparation method of a selective hydrogenation catalyst for unsaturated aldehydes and ketones. In this preparation method, a porous material Ni-MOF is used as the catalyst support. The precious metal nanoparticle precursor is introduced into the pores of the Ni-MOF support through the solution impregnation method. Then, the solvent in the impregnation system is removed and vacuum dried. Under high temperature and hydrogen conditions, the precious metal precursor in the Ni-MOF pores is reduced to precious metal nanoparticles, and at the same time, the Ni nodes in the Ni-MOF framework are partially reduced to Ni nanoparticles, thus obtaining a heterogeneous hydrogenation catalyst in which precious metal nanoparticles and Ni nanoparticles coexist.

[0015] In one embodiment of the present invention, the preparation method can be specifically operated according to the following steps:

[0016] Step 1: Synthesis of the Ni-MOF support: A nickel salt solution and an organic ligand solution are mixed and then subjected to a solvothermal or hydrothermal reaction at a specific temperature to obtain a porous material Ni-MOF catalyst support.

[0017] Step 2: Impregnation of the precious metal precursor: The Ni-MOF support is dispersed in an appropriate amount of solvent, and the precious metal nanoparticle precursor solution is gradually dropped into the Ni-MOF dispersion. The precious metal precursor is introduced into the pores of the Ni-MOF support through the solution impregnation method.

[0018] Step 3: Desolvation and drying of the catalyst precursor: The solvent in the precious metal precursor impregnation system is removed using a rotary evaporator and vacuum dried to obtain a Ni-MOF-based catalyst precursor loaded with the precious metal precursor.

[0019] Step 4: High-temperature reduction of the catalyst: The Ni-MOF-based catalyst precursor is placed in a high-temperature hydrogen atmosphere for reduction. The precious metal precursor in the Ni-MOF pores is reduced to precious metal nanoparticles, and at the same time, the Ni nodes in the Ni-MOF framework are partially reduced to Ni nanoparticles, thus obtaining a precious metal-Ni co-loaded Ni-MOF-based catalyst.

[0020] Further, 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.

[0021] Further, in step 1, the organic ligand 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. The terminal functional group capable of coordinating with metal ions is a carboxyl group, a hydroxyl group, a phosphonic acid group, or a nitrogen-containing heterocycle. The organic ligand is one or a mixture of two or more of them.

[0022] Further, in step 1, the solvent is one or a mixture of two or more of N,N-dimethylformamide, methanol, ethanol, or water.

[0023] Further, in step 1, the solvothermal or hydrothermal reaction temperature is from room temperature 20 to 180 °C, and the reaction time is 1 - 72 h.

[0024] In one embodiment of the present invention, 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, ruthenium chloride.

[0025] 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, tetrahydrofuran.

[0026] 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 added per 0.1 g of Ni-MOF support, the amount of solvent is not 0, the impregnation time of the noble metal precursor in the Ni-MOF dispersion is 1 - 48 h, and the impregnation temperature is 20 - 50 °C.

[0027] 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. In the reducing hydrogen atmosphere, the proportion of H 2 / inert gas is H 2 with a proportion of 5% - 100%, and the inert gas is Ar or N 2 , calculated based on the total weight of the catalyst being 100%, and the loading amount of metal nanoparticles is 0.1 wt% - 10 wt%. During the reduction process, the noble metal nanoparticles induce partial reduction of the metal nodes on the Ni-MOF support to Ni nanoparticles.

[0028] In one embodiment of the present invention, the vacuum drying time is 4 - 24 h, and the drying temperature is from room temperature to 80 °C.

[0029] The application of the unsaturated aldehyde and ketone selective hydrogenation catalyst in the selective hydrogenation of unsaturated aldehydes and ketones, where the unsaturated aldehyde and ketone is a molecule containing both a C=C bond and a C=O bond. Preferably, the unsaturated aldehyde and ketone is cinnamaldehyde. The catalyst of the present invention exhibits excellent carbon-carbon double bond hydrogenation activity and selectivity in the heterogeneous selective hydrogenation reaction of unsaturated aldehydes and ketones.

[0030] The present technical solution has the following beneficial effects:

[0031] The catalyst provided by the present invention has the following advantages:

[0032] 1. The catalyst support has a high specific surface area and large pore diameter, which is beneficial to the adsorption and transfer of substrate molecules and hydrogen molecules on the support and the diffusion of product molecules;

[0033] 2. The structure, morphology, pore diameter, etc. of the Ni-MOF support are highly adjustable, which is beneficial to the shape-selective adsorption of reaction substrates on the support, thereby improving the hydrogenation selectivity of specific unsaturated bonds;

[0034] 3. Different types of functional groups contained in the MOF support are beneficial to the rational modification and regulation of the surface properties of the catalyst, thereby improving the activity and selectivity of the catalyst;

[0035] 4. There is a synergistic effect between noble metal nanoparticles and Ni nanoparticles on the catalyst, which is beneficial to realizing the inversion of the hydrogenation selectivity of different types of unsaturated functional groups;

[0036] The catalyst preparation method provided by the present invention has the following advantages:

[0037] 1. Simple method: The preparation process is simple and efficient, and the requirements for instruments and equipment are low. The noble metal precursor is introduced into the Ni-MOF pore channels by a simple solution impregnation method, and the noble metal-Ni co-existing supported Ni-MOF-based catalyst can be obtained by high-temperature hydrogen reduction;

[0038] 2. Strong designability: There are many types of organic ligands available for synthesizing Ni-MOF. Different organic ligands can be selected according to the differences in catalytic substrate molecules to synthesize Ni-MOF, obtaining a catalyst support with a specific morphology, structure, and pore size, and different functional groups can be introduced into the support by post-modification methods to expand the universality of the catalyst;

[0039] 3. Strong controllability: By changing the type of noble metal precursor, different noble metal nanoparticles can be introduced into the MOF support pore channels. By controlling the dosage of the noble metal precursor, reduction temperature, reduction time, etc., the ratio and size of noble metal nanoparticles and Ni nanoparticles can be regulated, thereby regulating the catalytic activity and selectivity;

[0040] 4. Can be prepared in large quantities: The synthesis method of the Ni-MOF support selected by the method of the present invention is simple and has a high yield. The organic ligands used are relatively cheap, suitable for large-scale industrial preparation, and have potential industrial application prospects. Description of the drawings

[0041] Figure 1 It is a schematic diagram of the application of the noble metal-Ni co-existing supported Ni-MOF-based catalyst prepared by the present invention in the selective hydrogenation reaction of unsaturated aldehydes and ketones;

[0042] Figure 2 XRD and SEM of the Pt / Ni-MOF-74 catalyst prepared in Example 1, where Figure 2In which (a) is the XRD pattern, Figure 2 and (b) in it is the SEM image;

[0043] Figure 3 is the TEM of the Pt / Ni-MOF-74 catalyst prepared in Example 1;

[0044] Figure 4 is the XPS of the Pt / Ni-MOF-74 catalyst prepared in Example 1;

[0045] Figure 5 are the XRD and SEM of the Pt / Ni-CAT-1 catalyst prepared in Example 5, where Figure 5 in which (a) is the XRD pattern, Figure 5 and (b) in it is the SEM image;

[0046] Figure 6 is the performance test for the selective hydrogenation of the C=C bond of cinnamaldehyde using the Pt / Ni-MOF-74 catalyst with different Pt loadings prepared in Example 1;

[0047] Figure 7 is the performance test for the selective hydrogenation of the C=C bond of cinnamaldehyde using the Pt / Ni-CAT-1 catalyst prepared in Example 5;

[0048] Figure 8 is the performance test for the selective hydrogenation of the C=C bond of other unsaturated aldehydes and ketones using the Pt / Ni-MOF-74 catalyst prepared in Example 1. Detailed implementation mode

[0049] The following combines the examples and Figures 1 to 8 further describes the present invention.

[0050] The application schematic diagram of the noble metal-Ni coexisting supported Ni-MOF-based catalyst prepared by the present invention in the selective hydrogenation reaction of unsaturated aldehydes and ketones is as shown in Figure 1 shown. Unless otherwise specified, the reagents involved in the examples of the present invention are all commercially available products and can be obtained through commercial channels.

[0051] Example 1

[0052] Disperse 200 mg of Ni-MOF-74 (the synthesis method is referenced from Inorganic Chemistry, 2014, Volume 53, Pages 5881 - 5883) into 15 ml of methanol. Dropwise add 5 mL of chloroplatinic acid methanol solution (containing 4.20 mg of chloroplatinic acid) to the Ni-MOF-74 dispersion, stir at 50 °C for 24 h to adsorb the noble metal precursor into the MOF pores. Rotate and evaporate the above sample and vacuum dry for 6 h, and then in 100% H2 Reduce it at 200 °C for 2 h under an atmosphere to obtain a Pt / Ni-MOF-74 catalyst with a Pt loading of 1 wt%, denoted as 1.0%Pt / Ni-MOF-74.

[0053] Perform powder X-ray diffraction (XRD) characterization on the supported 1.0%Pt / Ni-MOF-74 catalyst ( Figure 2 as shown in (a) of Figure 1 ). The results show that the peak positions in the XRD pattern of this catalyst are consistent with the simulated spectrum of Ni-MOF-74, indicating that this catalyst still maintains the same crystal structure as the original Ni-MOF, that is, the high-temperature hydrogen reduction conditions will not cause significant damage to the Ni-MOF-74 support. No diffraction peak of Pt nanoparticles appears at 39.8° in the XRD pattern, indicating that the loaded Pt nanoparticles are small in size and uniformly dispersed on the Ni-MOF support. A small diffraction peak appears at 44.5° in the XRD pattern, corresponding to the diffraction peak of the Ni(111) crystal plane, indicating that Ni nanoparticles exist in the 1.0%Pt / Ni-MOF-74 catalyst. It can be calculated by the Scherrer formula that the size of Ni nanoparticles is about 7 nm, which means that while the noble metal Pt precursor is reduced to Pt nanoparticles, the metal nodes of Ni-MOF are also partially reduced to Ni nanoparticles, and the partial reduction of Ni nodes does not lead to the collapse of the overall framework structure of Ni-MOF. The results of scanning electron microscope (SEM) images show ( Figure 2 as shown in (b) of

[0054] ), the 1.0%Pt / Ni-MOF-74 catalyst is in the shape of nanospheres formed by stacking nanosheets about 100 nm together, and the size of a single nanosphere is several micrometers. After the catalyst is loaded with Pt and Ni nanoparticles, it still maintains the same morphology as Ni-MOF-74, and the partial precipitation of metal node Ni does not damage its intrinsic morphology. Figure 3 ), there are no obvious agglomerated metal nanoparticles on the surface of the catalyst, indicating that Pt and Ni nanoparticles are uniformly dispersed on the catalyst support. Pt nanoparticles with exposed (111) crystal planes are confirmed to exist on the Ni-MOF-74 support from the 0.226 nm lattice fringe, and their size is about 2 nm. Ni nanoparticles with exposed (111) crystal planes are confirmed to coexist with Pt nanoparticles on the support from the 0.203 nm lattice fringe, and the size of Ni nanoparticles is about 7 nm. The size of Ni nanoparticles is consistent with the particle size results calculated by XRD data and the Scherrer formula. The above results all indicate that both Pt nanoparticles and Ni nanoparticles exist on the Ni-MOF-74 support, and there is a certain distance between the two metal nanoparticles.

[0055] X-ray photoelectron spectroscopy (XPS) shows Ni and Pt elements in different valence states (as shown in (a) of Figure 4 and (b) of Figure 4 ). In the XPS spectrum of Ni 2p, the peak at a binding energy of 852.9 eV belongs to Ni in the 0 valence state, the peak at 856.7 eV belongs to Ni in the 2 valence state, and the two small peaks on the left are the satellite peaks of Ni in the 2 valence state. It can be seen from the spectrum that Ni metal nodes in Ni-MOF-74 are partially reduced to the 0 valence state 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 Pt in the 0 valence state, and those at 72.1 eV and 75.2 eV correspond to Pt in the 2 valence state. It shows that Pt in the 4 valence state in the Pt precursor chloroplatinic acid 4+ is completely reduced to low-valent Pt δ+ and Pt in the 0 valence state 0 under high-temperature hydrogen reduction conditions and is transformed into Pt metal nanoparticles. Consistent with the XRD and TEM results, it further confirms that Ni metal nodes in Ni-MOF-74 are partially reduced to Ni nanoparticles induced by Pt nanoparticles, and Pt nanoparticles and Ni nanoparticles coexist on the catalyst support.

[0056] Example 2

[0057] This example is basically the same as Example 1, except that the amount of the noble metal precursor chloroplatinic acid added is 2.10 mg, the noble metal Pt loading is 0.5%, and the catalyst is labeled as 0.5%Pt / Ni-MOF-74. The XRD results show that the structure of this catalyst has not changed significantly. Diffraction peaks of Ni nanoparticles appear in the XRD pattern, but the peak intensity is relatively low, indicating that while the noble metal Pt is reduced, Ni-MOF metal nodes are also partially reduced, and the reduction amount of Ni nanoparticles decreases slightly ( Figure 2 ).

[0058] Example 3

[0059] This example is basically the same as Example 1, except that the amount of the noble metal precursor chloroplatinic acid added is 6.30 mg, the noble metal Pt loading is 1.5%, and the catalyst is labeled as 1.5%Pt / Ni-MOF-74. The XRD results show that this catalyst still maintains the pore structure of the original Ni-MOF. Diffraction peaks of Ni nanoparticles also appear, and the peak intensity of Ni nanoparticles is relatively high, indicating that while the noble metal Pt is reduced, Ni-MOF metal nodes are also partially reduced, and the reduction amount of Ni nanoparticles increases slightly ( Figure 2 ).

[0060] Example 4

[0061] This example is basically the same as Example 1, except that the noble metal precursor solution added is 5 mL of sodium palladate chloride methanol solution (containing 5.53 mg of sodium palladate chloride), the noble metal Pd loading is 1.0%, and the catalyst is labeled as 1.0%Pd / Ni-MOF-74.

[0062] Example 5

[0063] The preparation process of Example 1 was adopted, except that the carrier used was another Ni-based MOF, Ni-CAT-1 (the synthesis method was referenced from Advanced Science, Volume 7, Page 1903003 in 2020), the noble metal Pt loading was 1.0%, and the catalyst was labeled as 1.0%Pt / Ni-CAT-1. As Figure 5 shown in (a) of Figure 5 and (b) of

[0064] Example 6

[0065] 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 autoclave. 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 bottle, the autoclave was sealed, and the air remaining in the reaction system was replaced with H 2 five times. The reaction was carried out at 70 °C and 2 MPa H 2 for a specific time, where undecane was only used as an internal standard. After the reaction, the solid catalyst was removed by filtration, 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 according to the gas chromatography peak area. Its performance test was as Figure 6 shown. The results showed that when the Pt loading was 1 wt%, the conversion rate was close to 100% at 64 min, and the selectivity of the carbon-carbon double bond hydrogenation product was as high as 89%, showing excellent catalytic performance.

[0066] Example 7

[0067] The selective hydrogenation performance of cinnamaldehyde was evaluated using the 0.5%Pt / Ni-MOF-74 prepared in Example 2 as the catalyst. Its performance test was as Figure 6As shown, when the noble metal Pt loading is 0.5 wt%, the conversion rate can reach over 97% in 40 min, and the selectivity is about 87%, indicating that the noble metal nanoparticle loading has a great influence on the catalytic activity and selectivity.

[0068] Example 8

[0069] Using the 1.5% Pt / Ni-MOF-74 prepared in Example 3 as the catalyst, the selective hydrogenation performance of cinnamaldehyde was evaluated. The performance test is as Figure 6 shown. When the noble metal Pt loading is 1.5 wt%, the conversion rate can reach over 98% in 130 min, and the selectivity is about 86%, further confirming that the Pt nanoparticle loading has a significant influence on the catalytic activity and selectivity.

[0070] Example 9

[0071] Using the 1.0% Pd / Ni-MOF-74 prepared in Example 4 as the catalyst, the selective hydrogenation performance of cinnamaldehyde was evaluated. The performance test results show that when using the noble metal Pd with a loading of 1 wt% as the catalyst active center, the conversion rate is 27% after 20 min of reaction, and the selectivity of the C=C hydrogenation product is as high as over 95%. It shows that loading other noble metal nanoparticles such as Pd also has excellent catalytic hydrogenation performance.

[0072] Example 10

[0073] Using the Pt / Ni-CAT-1 prepared in Example 5 as the catalyst, the selective hydrogenation performance of cinnamaldehyde was evaluated. The performance test is as Figure 7 shown. When the noble metal Pt loading is 1.0 wt%, the conversion rate can reach 100% in 135 min, and the selectivity of the carbon-carbon double bond hydrogenation product is as high as 87%, showing excellent catalytic performance. At the same time, it also shows that the change of the Ni-MOF support type will also have a significant impact on the catalytic activity and selectivity.

[0074] Example 11

[0075] Using the 1.0% Pt / Ni-MOF-74 prepared in Example 1 as the catalyst, the selective hydrogenation performance of other unsaturated aldehydes and ketones was evaluated. The catalytic reaction conditions of Example 6 were adopted, except that the unsaturated aldehydes and ketones used were other molecules containing both C=C bonds and C=O bonds, such as 4-chlorocinnamaldehyde, 4-methoxycinnamaldehyde, p-methylcinnamaldehyde, 4-fluorocinnamaldehyde, 3-methyl-2-butenal. The performance test is as Figure 8As shown, the conversion rate of 4-chlorocinnamaldehyde reached 90.6% at 65 min of reaction, and the selectivity for C=C hydrogenation reached 90.7%; the conversion rates of 4-methoxycinnamaldehyde, p-methylcinnamaldehyde, and 4-fluorocinnamaldehyde were 96.1%, 90.6%, and 97.9% respectively at 38 min 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% at 30 min of reaction. The catalytic performance results of the above unsaturated aldehydes and ketones all show that the catalyst prepared by the present invention has excellent catalytic performance and catalytic substrate universality for the selective hydrogenation of C=C bonds.

[0076] The above specific embodiments are only used to explain and illustrate the present invention, rather than limiting the present invention. Any changes and substitutions made to the present invention without creative labor within the scope of the concept and claims of the present invention fall within the protection scope of the present invention patent.

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 the carrier is loaded with at least one noble metal nanoparticle coexisting with Ni nanoparticles, wherein the Ni nanoparticles are derived from the partial reduction of Ni nodes in the Ni-MOF skeleton, and the noble metal nanoparticles are noble metal nanoparticles with hydrogenation activity, and the noble metal nanoparticles and Ni nanoparticles are both loaded in Ni-MOF pores; The catalyst is prepared according to the following method: a porous material Ni-MOF is used as a catalyst carrier, a precursor of precious metal nanoparticles is introduced into the pores of the Ni-MOF carrier by a 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, and at the same time, the Ni nodes in the Ni-MOF skeleton are partially reduced to Ni nanoparticles, so that a multiphase hydrogenation catalyst in which precious metal nanoparticles and Ni nanoparticles coexist can be obtained.

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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