A catalyst encapsulating rare alloy nanoparticles, and a preparation method and application thereof

Abstract

The application belongs to the technical field of catalysts, and discloses a catalyst for encapsulating rare alloy nanoparticles as well as a preparation method and application thereof. The catalyst uses oxygen-doped porous carbon as a carrier, and rare alloy nanoparticles are encapsulated in the carrier. The rare alloy nanoparticles include M metal and base metal Cu. The M metal is selected from at least one of Ni, Co, Zn, Fe, V and Ti. In the catalyst, the content of the M metal is 0.5-3.0 wt%. The catalyst involves a simple synthesis strategy. The trace M metal doped in the MCu rare alloy induces atomic-level metal M-Cu synergistic effect and enhanced Schottky junction, so that the synthesis of cost-effective multi-catalysts is universal. The catalyst can effectively catalyze a wide range of selective hydrogenation reduction under mild aqueous conditions, is environmentally friendly and has excellent stability, and shows great industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and specifically relates to a catalyst encapsulating rare alloy nanoparticles, its preparation method, and its application. Background Technology

[0002] Dilute alloys are assembled materials formed by adding a small amount of dissimilar monodisperse metals to a given host element. Ingenious methods to enhance structural and electronic synergy include preparing dilute bimetallic alloy clusters or nanoparticles (NPs), utilizing the Mott-Schottky effect, and functional doping of supports. Confining isolated metal atoms or clusters within crystalline porous materials can further overcome the shortcomings of traditional heterogeneous catalysis, thereby obtaining sintering-resistant catalysts with improved activity and selectivity.

[0003] In transition metal (TM) catalysts, noble metals dominate due to their high reactivity and functional group tolerance in various reactions. However, their high cost and tendency to aggregate under harsh reaction conditions limit their use. Single-atom catalysts (SACs) and single-atom alloys (SAAs) offer maximized atom utilization efficiency, minimizing the use of noble metals while exhibiting exceptional catalytic activity. In recent years, researchers both domestically and internationally have explored combinations of various metals with a few noble metals, including PdCo, ​​AuCo, PtCu, and PtFe, which significantly reduce the use of the noble metal Pd. For example, the ultrarare alloy (UDA) reported in Reference 1 (Applied Catalysis B: Environmental 2021, 284, 119737) is formed by the electrocoupled substitution of Cu atoms by Pt atoms on dispersed Cu nanoparticles. Under hydrogen pressures of 1.0-2.0 MPa, the furfural hydrogenation reaction exhibited superior catalytic performance compared to pure Cu or other bimetallic nanoparticle alloy catalysts. Reference 2 (Nature Catalysis 2022, 5, 503-512) developed a highly active oxygen reduction catalyst, namely a composite catalyst (Pt-Fe-NC) consisting of Pt-based nanoparticles and a carbon-based non-noble metal support. In constant voltage tests, Pt-Fe-NC showed excellent current stability in both oxygen and air environments, with almost no decrease in platinum mass activity after 100,000 cycles. Supporting diluted noble metal-based alloys on porous substrates represents a significant step towards the industrial application of composite catalysts. Currently, the support materials for rare metal alloys are mainly metal oxides, which can promote mass transfer and enhance the stability of the metal.

[0004] Reference 3 (Chem.Eng.J., 2018, 351, 995-1005) reports a Pd-Ag alloy catalyst supported on MCM-41. Due to the synergistic effect between the two metals, incorporating Ag into the Pd-based catalyst significantly improves its catalytic activity and selectivity for the hydrogenation of cinnamaldehyde (CAL) to phenylpropanaldehyde (HCAL) compared to catalysts without Ag. However, the preparation of this catalyst requires the consumption of a large amount of precious metals, thus limiting the universality of this preparation method.

[0005] Chinese patent CN107497488A discloses a method for preparing and applying a highly hydrogenation-selective Au-Pd single-atom alloy catalyst. This invention uses an organic ligand-linked amino group-modified MOF as a support and employs a direct reduction method with sodium borohydride to prepare a single-atom alloy catalyst in which Pd is dispersed on an Au surface. It exhibits excellent selectivity in the reductive amination reaction of nitro compounds and aldehydes. However, this catalyst uses chloroauric acid and chloropalladium acid as metal precursors, significantly consuming scarce precious metal resources, and the use of cyclohexane as a solvent in the catalytic process does not conform to the principles of green chemistry.

[0006] Chinese patent CN108620092A discloses an alumina-supported Pt / Cu single-atom alloy catalyst, its preparation method, and its applications. This invention patent uses a simple co-impregnation method and an atomic dilution strategy to prepare an alumina-supported Pt / Cu single-atom alloy. It exhibits high dehydrogenation activity in the dehydrogenation of low-chain alkanes to olefins, achieving a propylene selectivity of over 90%. Furthermore, it requires a small amount of Pt and has high utilization, making it cheaper than industrially pure Pt catalysts. However, the prepared catalyst has a narrow range of applications.

[0007] Based on the current state of research, it is of great significance to find a simpler method to prepare high-performance and cost-effective multifunctional catalysts and apply them to the selective catalytic reactions of various substrates under mild aqueous conditions. Summary of the Invention

[0008] This invention aims to solve at least one of the technical problems existing in the prior art. This invention provides a catalyst encapsulating rare alloy nanoparticles, its preparation method, and its application. The catalyst of this invention can use base metals as the main active component and exhibits very high activity, selectivity, and stability for the transfer hydrogenation of nitro compounds and the low-pressure selective hydrogenation of aldehyde compounds under mild aqueous conditions.

[0009] This invention utilizes the different solubilities of carbon in M ​​metal and base metal to embed diluted M in an ultrathin oxygen-doped porous carbon (OC) support. x Cu y (M is a metallic element) alloy nanocrystals can be used to obtain composite core-shell alloys of M. x Cu y @OC nanocatalyst. This catalyst makes better use of base metals as the main active component. As a highly cost-effective and efficient catalyst, it exhibits very high activity and selectivity for the transfer hydrogenation of nitro compounds and the low-pressure selective hydrogenation of aldehydes under mild aqueous conditions. Furthermore, the oxygen-doped graphene carbon shell greatly enhances its stability without affecting material and electron transfer.

[0010] This invention addresses the problems of insufficient atomic efficiency, low selectivity, and large amounts of precious metals required in current multiphase transition metal catalysts. By adjusting the interaction between trace transition metal M, the host base metal Cu, and a porous semiconductor support, the geometry and electronic structure of isolated metal species are modified, thereby endowing them with high catalytic activity and reaction versatility. The aim is to provide a highly cost-effective, multifunctional catalyst that can be widely applied under mild aqueous conditions for efficient transfer hydrogenation or low-pressure hydrogenation reactions. This catalyst uses oxygen-doped porous carbon (OC) as a support, supporting rare alloy nanoparticles composed of trace transition metal M and a host base metal such as Cu. The catalyst is simple to prepare, suitable for large-scale production, and can achieve efficient (conversion >95.6%) and directional (selectivity >92.6%) conversion of various substrates to the target product under environmentally friendly, mild aqueous conditions.

[0011] A first aspect of the present invention provides a catalyst for encapsulating rare alloy nanoparticles.

[0012] A catalyst encapsulating rare alloy nanoparticles, wherein the catalyst uses oxygen-doped porous carbon (OC) as a support, and the rare alloy nanoparticles are encapsulated in the support, wherein the rare alloy nanoparticles include metal M and base metal Cu.

[0013] The metal M is selected from at least one of Ni, Co, Zn, Fe, V, and Ti;

[0014] The content of the M metal in the catalyst is 0.5-3.0 wt%.

[0015] In the catalyst described in this invention, the content of metal M plays a very important role in the catalytic performance of the catalyst and can produce unexpected technical effects.

[0016] Preferably, the M metal may also be selected from at least one of Pd, Ir and Rh.

[0017] Preferably, the content of the M metal in the catalyst is 0.8-2.0 wt%; more preferably, the content of the M metal is 1.0-2.0 wt%.

[0018] Preferably, the Cu content in the catalyst is 56-58.5 wt%; more preferably, the Cu content is 57.5-58 wt%.

[0019] Preferably, the rare alloy nanoparticles are composed of Ni and Cu.

[0020] Preferably, the catalyst has a Cu content (or loading) of 57.50-57.99 wt% and a Ni content (or loading) of 1.71-1.82 wt%; more preferably, the catalyst has a Cu content of 57.99 wt% and a Ni content of 1.82 wt%.

[0021] Preferably, oxygen doping in the carrier refers to oxygen existing uniformly in the graphene-like carbon shell carrier in the form of hydroxyl oxygen (C-OH) or ether bond oxygen (OCO).

[0022] Preferably, the pores in the carrier are mainly mesopores (2-50nm), supplemented by micropores and macropores.

[0023] A second aspect of the present invention provides a method for preparing a catalyst encapsulating rare alloy nanoparticles.

[0024] A method for preparing a catalyst encapsulating rare alloy nanoparticles includes the following steps:

[0025] 1) The metal precursor, oxygen-containing ligand, alkali and solvent are stirred and crystallized, and then separated to obtain the metal compound;

[0026] 2) The metal compound obtained in step 1) is subjected to heat treatment to obtain the catalyst.

[0027] Preferably, step 1) involves stirring and crystallizing at room temperature.

[0028] Preferably, in step 1), the separation includes centrifugation and vacuum drying.

[0029] Preferably, in step 1), the metal precursor is a mixture of M metal salt and copper salt.

[0030] Preferably, the M metal salt is selected from at least one of nickel nitrate, iron nitrate, cobalt nitrate, zinc nitrate, metavanadate, tetraethyl titanate, and their hydrates.

[0031] Preferably, the M metal salt may further include any one of palladium nitrate, palladium chloride, iridium dicarbonylacetylacetone, or rhodium dicarbonylacetylacetone.

[0032] Preferably, the copper salt is at least one of copper nitrate or its hydrate.

[0033] Preferably, the metal salt M, the oxygen-containing ligand, the base, and the solvent are mixed to obtain solution A. Then, the copper salt is fused with the solvent to obtain solution B. Nitrogen gas is bubbled into solution A and stirred. Then, solution B is added dropwise to solution A and the reaction is maintained at room temperature for 4.0-6.0 hours. The precipitate is obtained by centrifugation, washed 3-10 times, and then dried in a vacuum furnace to obtain the metal compound. Specifically, the metal salt M and the copper salt are added stepwise.

[0034] Preferably, in step 1), the oxygen-containing ligand is selected from at least one of benzoic acid, terephthalic acid, pyromellitic acid, and 2-amino-1,3,5-benzenetriacic acid.

[0035] Preferably, in step 1), the alkali is selected from at least one of CH4N2O, NaOH, KOH, NH3·H2O, and Na2CO3.

[0036] Preferably, in step 1), the solvent is selected from at least one of ethanol, methanol, isopropanol, acetonitrile, and water.

[0037] The aforementioned metal precursors, oxygen-containing ligands, and bases can also be prepared into solutions before crystallization by stirring with the solvent.

[0038] Preferably, in step 1), the stirring and crystallization time is 70-720 min, more preferably 90-720 min.

[0039] Preferably, in step 2), the temperature of the heat treatment is 380-700℃, more preferably 400-700℃.

[0040] Preferably, in step 2), the heat treatment employs programmed heating with a heating rate of 1-7℃ / min, preferably 1-6℃ / min.

[0041] Preferably, in step 2), the heat treatment is performed under a protective atmosphere.

[0042] Preferably, the protective atmosphere is selected from at least one of nitrogen, argon, or a hydrogen-argon mixture.

[0043] A third aspect of the present invention provides an application of a catalyst encapsulating rare alloy nanoparticles.

[0044] The above catalysts are used in the transfer hydrogenation reaction of nitro compounds using hydrazine hydrate or sodium borohydride as the hydrogen source.

[0045] Preferably, the application includes the following steps:

[0046] Under atmospheric pressure, the catalyst, nitro compound, reducing agent, and deionized water are mixed and then heated in an oil bath. Samples are taken at intervals and qualitatively and quantitatively analyzed for the target product and its yield using gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and ultraviolet-visible spectrophotometer (UV-2550). The reducing agent is any one of hydrazine hydrate, formic acid, potassium formate, and sodium borohydride.

[0047] Preferably, during the heating reaction, the molar ratio of the substrate to the active component in the catalyst is (150-1050):1.

[0048] Preferably, the amount of deionized water used is 5-15 mL.

[0049] Preferably, the oil bath temperature is 25-60℃.

[0050] The application of the above catalyst in the directed hydrogenation reaction of aldehydes using H2 as the hydrogen source.

[0051] Preferably, the application includes the following steps:

[0052] Deionized water was added to a high-pressure reactor as the reaction solvent, followed by a certain amount of substrate and catalyst. The preferred molar ratio of substrate to catalyst was (100-550):1. The high-pressure reactor was charged with 0.2-1.5 MPa H2. The reaction system was stirred at 25-100℃ for 90-360 min. After the reaction system cooled to room temperature, the catalyst was separated by centrifugation, and the reaction solution was analyzed by GC and GC-MS.

[0053] In the above reactions, the substrate conversion rate was above 95.6%, and the selectivity of the target product was greater than 92.6%.

[0054] The catalyst described in this invention has a wide catalytic range and is widely applicable in the hydrogenation reactions of various nitro compounds and aldehydes. It exhibits excellent catalytic activity, high selectivity for target products, and good stability.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] 1) The catalyst of the present invention uses transition metal salt as the precursor and oxygen-doped hierarchical porous carbon generated in situ through heat treatment as the support. The preparation process only involves conventional pretreatment steps such as one-pot stirring crystallization, centrifugation, drying and heat treatment, which can yield a highly efficient catalyst rich in rare alloy nanoparticles. The process is extremely simple and suitable for large-scale mass production.

[0057] 2) This invention relates to a simple synthesis strategy. The atomic-level metal-Cu synergistic effect and enhanced Schottky junction induced by trace M metal doping in MCu rare-earth alloys make the synthesis of cost-effective multifunctional catalysts universal. MCu@OC can effectively catalyze a wide range of selective hydrogenation reduction under mild aqueous conditions, is environmentally friendly and has excellent stability, showing great promise for industrial applications.

[0058] 3) The catalyst described in this invention has excellent catalytic performance and can reduce p-chloronitrobenzene to p-chloroaniline with high conversion rate (over 97%, for example 97.9%) and high yield (over 97%, for example 97.3%) in water, at normal pressure and temperature and under environmentally friendly conditions. It has good stability and can be recycled more than 11 times, for example 12 times, without significant decrease in catalytic performance. It has extremely high industrial value and important application significance.

[0059] 4) The catalyst described in this invention has good substrate versatility. When the substrate is any one of various nitro compounds or aldehyde compounds, the catalyst also exhibits excellent catalytic activity and high yield of the target product. Attached Figure Description

[0060] Figure 1 The X-ray diffraction (XRD) patterns of the catalysts prepared in Examples 1-6 are shown.

[0061] Figure 2 Raman scattering patterns of the catalysts prepared in Examples 1-3 and Example 5;

[0062] Figure 3 The N2 adsorption-desorption isotherms and pore size distribution curves of the catalysts prepared in Examples 1-3 and Example 5 are shown.

[0063] Figure 4 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Example 1.

[0064] Figure 5 This is a schematic diagram of the structure of the oxygen-doped hierarchical porous carbon support in the catalyst prepared in Example 1;

[0065] Figure 6 Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and particle size distribution images of the catalysts prepared in Examples 1 and 5.

[0066] Figure 7 High-angle annular dark field image (HAADF) and elemental line scans of the corresponding representative particles (NPs) of the catalysts prepared in Examples 1 and 5, and corresponding elemental mapping diagrams;

[0067] Figure 8 The images show the in-situ infrared adsorption of CO molecules on the catalysts prepared in Examples 1 and 5.

[0068] Figure 9 The UV-Vis diffuse reflectance spectra (UV-vis DRS) of the catalysts prepared in Examples 1-3 and Example 5 are shown.

[0069] Figure 10The above are X-ray photoelectron spectroscopy (XPS) spectra of the catalysts prepared in Examples 1-3 and Example 5.

[0070] Figure 11 The Auger electron spectrum (CuL3VV) of the catalysts prepared in Examples 1-2 with respect to Cu is shown.

[0071] Figure 12 The above are the temperature-programmed reduction (H2-TPR) graphs of the catalysts prepared in Examples 1-3 and Example 5 with respect to H2.

[0072] Figure 13 The graph shows the temperature-programmed desorption (H2-TPD) of the catalysts prepared in Examples 1-2 with respect to H2.

[0073] Figure 14 Synchrotron radiation fine absorption spectroscopy (XAS) analysis of the catalyst prepared in Example 1 with respect to the Cu K- absorption edge;

[0074] Figure 15 Synchrotron radiation fine absorption spectroscopy (XAS) analysis of the catalyst prepared in Example 1 with respect to the Ni K- absorption edge;

[0075] Figure 16 This is a comparison chart showing the performance of the catalysts prepared in Examples 1-3 and Example 5 in the transfer hydrogenation reaction of p-chloronitrobenzene.

[0076] Figure 17 The graph shows the recycling performance of the catalyst prepared in Example 1 in the transfer hydrogenation reaction of p-chloronitrobenzene;

[0077] Figure 18 Analysis of the surface potential of the catalyst prepared in Example 1;

[0078] Figure 19 This is a comparison chart showing the performance of the catalysts prepared in Examples 1-2 in the transfer hydrogenation reaction of p-nitrophenol;

[0079] Figure 20 This is a comparison chart showing the performance of the catalysts prepared in Examples 1-2 in the furfural hydrogenation reaction. Detailed Implementation

[0080] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0081] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0082] Example 1

[0083] A method for preparing a catalyst encapsulating rare alloy nanoparticles includes the following steps:

[0084] 1) Dissolve 0.6 mmol Ni(NO3)2·6H2O in 60 mL methanol and 100 mL ultrapure water. Add a mixed solution of 50 mmol terephthalic acid and 23 mmol NaOH dropwise with stirring until the pH value is ≈10.83, which is called solution A. Dissolve 12 mmol Cu(NO3)2·6H2O in 60 mL methanol and 100 mL ultrapure water to form solution B. Then, under nitrogen bubbling and continuous stirring, slowly add solution B to solution A. After maintaining the reaction at room temperature for 360 min, the precipitate is obtained by centrifugation, washed three times with water and methanol, and then completely dried overnight in a vacuum furnace to obtain the metal compound (also known as nanocomposite material).

[0085] 2) The metal compound obtained in step 1) is heated from room temperature to 550°C at a rate of 5°C / min in a tube furnace under an argon atmosphere, held for 120 min, and then cooled naturally to room temperature to obtain the catalyst.

[0086] The metal content in the catalyst was determined by inductively coupled plasma atomic emission spectrometry, revealing a Cu content (or loading) of 57.99 wt% and a Ni content of 1.82 wt%. The catalyst prepared in this example is labeled CuNi. 0.05 @OC or #1 catalyst.

[0087] Example 2

[0088] The catalyst was prepared using the method described in Example 1, the only difference being that the molar amount of Ni(NO3)2·6H2O was 0 in step 1). The metal content of the obtained catalyst was determined by inductively coupled plasma atomic emission spectrometry, revealing a Cu content of 58.62 wt%. The catalyst prepared in this example is labeled as Cu / OC or Catalyst #2.

[0089] Example 3

[0090] The catalyst was prepared using the method described in Example 1, except that the molar amount of Cu(NO3)2·6H2O was 0 in step 1). The metal content of the obtained catalyst was determined by inductively coupled plasma atomic emission spectrometry, revealing that the Ni content in the catalyst was 1.86 wt%. The catalyst prepared in this example was labeled as Ni@OC or 3# catalyst.

[0091] Example 4

[0092] The catalyst was prepared using the method described in Example 1, the only difference being that the molar amount of Ni(NO3)2·6H2O in step 1) was 3 mmol. The resulting catalyst was analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine its metal content, revealing a Cu content of 55.89 wt% and a Ni content of 0.39 wt%. The catalyst prepared in this example is labeled CuNi. 0.01 @OC or 4# catalyst.

[0093] Example 5

[0094] The catalyst was prepared using the method described in Example 1, the only difference being that the molar amount of Ni(NO3)2·6H2O in step 1) was 3 mmol. The resulting catalyst was analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine its metal content, revealing a Cu content of 58.93 wt% and a Ni content of 8.52 wt%. The catalyst prepared in this example was labeled CuNi. 0.25 @OC or 5# catalyst.

[0095] Example 6

[0096] The catalyst was prepared using the method described in Example 1, the only difference being that the molar amount of Ni(NO3)2·6H2O in step 1) was 7.8 mmol. The resulting catalyst was analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine its metal content, revealing a Cu content of 59.21 wt% and a Ni content of 11.91 wt%. The catalyst prepared in this example is labeled CuNi. 0.65 @OC or 6# catalyst.

[0097] Example 7

[0098] The catalyst was prepared using the method described in Example 1, with the only difference being that Ni(NO3)2·6H2O was replaced with Zn(NO3)2·6H2O in step 1). The metal content of the obtained catalyst was determined by inductively coupled plasma atomic emission spectrometry. Thus, the CuZn rare-alloy catalyst was obtained.

[0099] Example 8

[0100] The catalyst was prepared using the method described in Example 1, except that in step 1), Ni(NO3)2·6H2O was replaced with Fe(NO3)2·9H2O. The metal content of the resulting catalyst was determined by inductively coupled plasma atomic emission spectrometry.

[0101] Example 9

[0102] The catalyst was prepared using the method described in Example 1, except that in step 1), Ni(NO3)2·6H2O was replaced with Co(NO3)2·6H2O. The metal content of the resulting catalyst was determined by inductively coupled plasma atomic emission spectrometry.

[0103] Example 10

[0104] The catalyst was prepared using the method described in Example 1, except that in step 1), Ni(NO3)2·6H2O was replaced with palladium nitrate solution; the metal content of the obtained catalyst was determined by inductively coupled plasma atomic emission spectrometry.

[0105] 1. The catalyst structure is characterized as follows:

[0106] Figure 1 The images show the X-ray diffraction (XRD) patterns of the catalysts prepared in Examples 1-6.

[0107] Figure 2 Raman scattering patterns of the catalysts prepared in Examples 1-3 and Example 5;

[0108] Figure 3 The N2 adsorption-desorption isotherms and pore size distribution curves of the catalysts prepared in Examples 1-3 and Example 5 are shown; from Figure 3 It can be seen that the catalysts prepared in different embodiments exhibit varying effects on N2 adsorption-desorption and different pore size distributions. This demonstrates that changing the amount of raw materials used in catalyst preparation significantly alters the structure of the resulting catalyst.

[0109] Figure 4 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Example 1.

[0110] Figure 5 This is a schematic diagram of the oxygen-doped hierarchical porous carbon support in the catalyst prepared in Example 1; that is, the support can form a carbon cage structure, which can encapsulate rare alloy nanoparticles.

[0111] Figure 6 The images show transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and particle size distribution of the catalysts prepared in Examples 1 and 5; where Figures a) and b) are CuNi 0.05 Transmission electron microscopy (TEM) images of @OC, and corresponding particle size distribution maps of the particles (NPs); Figures c) and d) show CuNi 0.05 High-resolution transmission electron microscopy (HR-TEM) images of CuNi at @OC. Figures e) and f) are CuNi 0.25 Transmission electron microscopy (TEM) images of @OC and corresponding particle size distribution maps (NPs); Figures g) and h) show CuNi 0.25 High-resolution transmission electron microscopy (HR-TEM) image from @OC.

[0112] Figure 7Figures a and b) show high-angle annular dark-field images (HAADF) and elemental line scans of the corresponding representative particles (NPs) of the catalysts prepared in Examples 1 and 5, as well as the corresponding elemental mapping diagrams; Figures a) and b) show CuNi 0.05 The high-angle annular dark-field image (HAADF) of @OC and the elemental line scans of the corresponding representative particles (NPs), and Figures c), d), e), and f) are the corresponding elemental mappings; g) and h) are CuNi 0.25 The high-angle annular dark field image (HAADF) of @OC and the elemental line scan of the corresponding representative particles (NPs), as well as the elemental mappings of i), j), k), and l).

[0113] Figure 8 Figure a) shows the in-situ infrared adsorption diagrams of the catalysts prepared in Examples 1 and 5 with respect to CO molecules; Figure a) shows the CuNi... 0.05 @OC's in-situ infrared adsorption experimental spectrum of CO; Figure b) shows CuNi 0.25 @OC shows the in-situ infrared adsorption spectra of CO. It can be seen that the catalysts prepared in Example 1 and Example 5 exhibit significantly different in-situ infrared adsorption effects for CO molecules.

[0114] Figure 9 The images show the UV-Vis diffuse reflectance spectra (UV-vis DRS) of the catalysts prepared in Examples 1-3 and Example 5.

[0115] Figure 10 The above are X-ray photoelectron spectroscopy (XPS) spectra of the catalysts prepared in Examples 1-3 and Example 5; where 1# represents CuNi 0.05 @OC, 2# indicates Cu / OC, 3# indicates Ni@OC, 5# indicates CuNi 0.25 @OC).

[0116] Figure 11 The image shows the Auger electron spectrum (CuL3VV) of the catalysts prepared in Examples 1-2 with respect to Cu.

[0117] Figure 12 The diagram shows the temperature-programmed reduction (H2-TPR) of the catalysts prepared in Examples 1-3 and Example 5 with respect to H2.

[0118] Figure 13 The diagram shows the temperature-programmed desorption (H2-TPD) of the catalysts prepared in Examples 1-2 with respect to H2.

[0119] Figure 14The following is a synchrotron radiation fine absorption spectrum (XAS) analysis of the catalyst prepared in Example 1 with respect to the Cu K-absorbing edge; wherein, Figure a) is the X-ray absorption near-edge structure (XANES) spectrum of the Cu K-absorbing edge; Figure b) is the first derivative corresponding to XANES; Figure c) is the extended X-ray absorption fine structure (EXAFS) spectrum of the corresponding k-space; Figure d) is the R-space analysis corresponding to the Cu K-absorbing edge.

[0120] Figure 15 The following is a synchrotron radiation fine absorption spectrum (XAS) analysis of the catalyst prepared in Example 1 with respect to the Ni K-absorbing edge; wherein, Figure a) is the X-ray absorption near-edge structure (XANES) spectrum of the Ni K-absorbing edge; Figure b) is the first derivative corresponding to XANES; Figure c) is the extended X-ray absorption fine structure (EXAFS) spectrum of the corresponding k-space; Figure d) is the R-space analysis corresponding to the Ni K-absorbing edge.

[0121] 2. The catalytic effect test results are as follows:

[0122] In a 50 mL round-bottom flask containing 15 mL of deionized water, 20 mg of catalysts 1#-6#, 0.5 mmol of p-chloronitrobenzene, and 1.5 mmol of hydrazine hydrate were added respectively. The reaction was carried out at 50 °C for 240 min. The reactants and products were qualitatively and quantitatively analyzed by GC and GC-MS. The results are shown in Table 1.

[0123] The structural characteristics of catalysts 1#-3# and catalyst 5# are shown in Table 2.

[0124] The thermodynamic studies on catalysts 1#-3# and catalyst 5# are shown in Table 3.

[0125] Table 1: Performance of catalysts #1-#6 in the transfer hydrogenation of p-chloronitrobenzene

[0126] Serial Number Conversion rate (%) Selectivity (%) 2#(Cu / OC) 27.7 99.3 3#(Ni@OC) 40.2 87.1 <![CDATA[4#(CuNi 0.01 @OC)]]> 56.5 96.2 <![CDATA[1#(CuNi 0.05 @OC)]]> 97.9 99.4 <![CDATA[5#(CuNi 0.25 @OC)]]> 99.8 88.7 <![CDATA[6#(CuNi 0.65 @OC)]]> 73.2 81.3

[0127] As can be seen from Table 1, the catalyst prepared in Example 1 exhibits the best catalytic effect, far superior to the catalysts prepared in other examples. This demonstrates that a Ni content of 1.82 wt% in the catalyst can achieve unexpected technical results.

[0128] Figure 16 Figure 1 shows a performance comparison of the catalysts prepared in Examples 1-3 and Example 5 for the transfer hydrogenation reaction of chloronitrobenzene; Figure 2 shows the performance of various catalysts for the transfer hydrogenation of chloronitrobenzene; Figure 3 shows the conversion frequency of various catalysts for the transfer hydrogenation of chloronitrobenzene. It can be seen from the figures that the catalyst prepared in Example 1 has the best catalytic effect.

[0129] Figure 17 The graph shows the recycling performance of the catalyst prepared in Example 1 in the transfer hydrogenation reaction of p-chloronitrobenzene; it can be seen that the catalyst prepared in Example 1 has good recycling performance in the transfer hydrogenation reaction of p-chloronitrobenzene.

[0130] Table 2: Structural characteristics of catalysts #1-#3 and catalyst #5

[0131] catalyst S represents the specific surface area (square meters per gram). V-pore volume (cubic centimeters per gram) D-pore size (nanometers) Cu / OC 55.7 0.0052 7.95 Ni@OC 232.01 0.46 8.01 <![CDATA[CuNi 0.05 @OC]]> 99.38 0.13 5.68 <![CDATA[CuNi 0.25 @OC]]> 110.61 0.071 2.41

[0132] As can be seen from Table 2, the specific surface area, pore volume, and pore size of the catalyst prepared in Example 1 are significantly different from those of the catalysts prepared in other examples. This could potentially have a significant and unpredictable impact on the catalytic performance of the catalyst.

[0133] Figure 18 The surface potential analysis of the catalyst prepared in Example 1 is shown in Figure a); Figure a) shows the CuNi... 0.05 @OC atomic force microscope images, Figure b) is the corresponding three-dimensional image, Figure c) is the height distribution of the corresponding line in Figure a), Figure d) is the potential distribution of the corresponding line in Figure (e), Figure e) is CuNi 0.05 The surface potential of the @OC catalyst, as shown in Figure f), is the corresponding three-dimensional image.

[0134] Table 3: Relevant thermodynamic parameters of catalysts #1-#3 and catalyst #5 for the hydrogenation of p-chloronitrobenzene

[0135]

[0136] In a 50 mL round-bottom flask containing 15 mL of deionized water, 20 mg of catalyst #1, 0.5 mmol of various nitro compounds, and 1.5 mmol of hydrazine hydrate were added. The mixture was reacted at 50 °C for a period of time. The reactants and products were qualitatively and quantitatively analyzed by GC and GC-MS. The results are shown in Table 4.

[0137] Table 4: Catalyst #1 (CuNi) 0.05 @OC) for the transfer hydrogenation properties of other nitro compounds

[0138]

[0139]

[0140] As can be seen from Table 4, the catalyst prepared in Example 1 has excellent transfer hydrogenation performance for different types of nitro compounds.

[0141] Figure 19This is a performance comparison chart of the catalysts prepared in Examples 1-2 in the transfer hydrogenation reaction of p-nitrophenol; Figure a) corresponds to the catalyst of Example 2 in the transfer hydrogenation reaction of p-nitrophenol, and Figure b) corresponds to the catalyst of Example 1 in the transfer hydrogenation reaction of p-nitrophenol. Figure 19 It can be seen that the catalyst prepared in Example 1 performs significantly better than the catalyst prepared in Example 2 in the transfer hydrogenation reaction of p-nitrophenol.

[0142] In a 50 mL high-pressure reactor containing 15 mL of deionized water, 20 mg of catalyst #1 and 0.75 mmol of aldehyde compound were added. After the air was purged, 1.0 MPa H2 was introduced and the reaction was carried out at 50 °C for a period of time. The product was qualitatively and quantitatively analyzed by GC and GC-MS. The results are shown in Table 5.

[0143] Table 5: Catalyst #1 (CuNi) 0.05 @OC) for selective catalysis of furfural

[0144]

[0145] As can be seen from Table 5, the catalyst prepared in Example 1 exhibits excellent selective catalytic performance for furfural.

[0146] Figure 20 Figure a) shows a performance comparison of the catalysts prepared in Examples 1-2 in the furfural hydrogenation reaction. Figure a) shows the performance of Cu / OC and CuNi catalysts. 0.05 Comparative performance diagram of @OC for low-pressure hydrogenation reaction of furfural; Figure b shows CuNi 0.05 @OC is used to illustrate the evolution of various products over time after the hydrogenation reaction of furfural.

[0147] The above description outlines the basic principles, main features, and advantages of this invention. Those skilled in the art should understand that the scope of protection of this invention is not limited to the above embodiments. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A catalyst encapsulating rare alloy nanoparticles, characterized in that, The catalyst uses oxygen-doped porous carbon as a support, and rare alloy nanoparticles are encapsulated in the support. The rare alloy nanoparticles include Ni and base metal Cu. Oxygen doping in the carrier refers to the presence of oxygen in the graphene-like carbon shell carrier in the form of hydroxyl oxygen or ether bond oxygen. The catalyst contains 57.50-57.99 wt% Cu and 1.71-1.82 wt% Ni. The method for preparing the catalyst includes the following steps: 1) The metal precursor, oxygen-containing ligand, alkali and solvent are stirred and crystallized, and then separated to obtain the metal compound; 2) The metal compound obtained in step 1) is subjected to heat treatment to obtain the catalyst; The metal precursor is a mixture of nickel and copper salts; The heat treatment temperature is 380-700℃.

2. The catalyst according to claim 1, characterized in that, The pores in the carrier are mainly mesopores, supplemented by micropores and macropores.

3. The method for preparing the catalyst according to any one of claims 1-2, characterized in that, Includes the following steps: 1) The metal precursor, oxygen-containing ligand, alkali and solvent are stirred and crystallized, and then separated to obtain the metal compound; 2) The metal compound obtained in step 1) is subjected to heat treatment to obtain the catalyst; The metal precursor is a mixture of nickel and copper salts; The heat treatment temperature is 380-700℃.

4. The preparation method according to claim 3, characterized in that, The copper salt is at least one of copper nitrate or its hydrate; in step 1), the oxygen-containing ligand is selected from at least one of benzoic acid, terephthalic acid, trimesic acid, and 2-amino-1,3,5-benzenetricarboxylic acid; in step 1), the base is selected from at least one of CH4N2O, NaOH, KOH, NH3·H2O, and Na2CO3; the nickel salt is nickel nitrate.

5. The use of the catalyst according to any one of claims 1-2 in the transfer hydrogenation reaction of nitro compounds using hydrazine hydrate or sodium borohydride as the hydrogen source.

6. The use of the catalyst according to any one of claims 1-2 in the directed hydrogenation reaction of aldehydes with H2 as the hydrogen source.

Images