Post-supported metal catalyst, preparation method and application

Abstract

The invention discloses a preparation method of a post-supported metal catalyst, which comprises the following steps: firstly, preparing functional phenolic resin in advance, then forming an ordered mesoporous carbon composite titanium oxide carrier through solvent volatilization and calcination processes, then dipping a mixed metal source precursor on the carbon composite titanium oxide carrier, and carrying out hydrogen reduction process to obtain the post-supported metal catalyst. The supported monatomic palladium catalyst is formed. According to the post-supported metal catalyst, the preparation method and the application provided by the invention, titanium dioxide doped with different elements is introduced into the pore wall of ordered mesoporous carbon, so that the lattice confinement effect of an inert carbon carrier on palladium monatomic is realized, and the interaction between metal and the carrier is greatly enhanced; the problems of metal migration, agglomeration, loss and the like in the long-time reaction process are effectively avoided, meanwhile, the catalytic activity, selectivity and stability of the palladium catalyst are improved, meanwhile, the situation that unstable metal is removed through an acid pickling process can be avoided, and time and cost are saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts, in particular to a post-supported metal catalyst, a preparation method and application thereof. BACKGROUND

[0002] Ketone compounds, as an important chemical intermediate, have a wide range of applications in the fields of medicine, agriculture and material science. With the increasing demand for the development of sustainable chemical industry worldwide, the development of green and efficient ketone compound synthesis process provides key technical support for its future industrialization application. In the current research field, the catalytic hydrogenation method with resorcinol as raw material is considered as an ideal synthesis route due to its significant advantages. This process realizes high atomic economy conversion and conforms to the development concept of green chemistry, effectively avoiding the defects of multiple by-products and long steps in traditional synthesis routes.

[0003] In the field of pharmaceutical and chemical industry, supported metal catalysts in heterogeneous catalytic reactions are increasingly valued for their unique catalytic properties. Among them, the interface interaction between the active phase and the support and how the interface density affects the catalytic reaction mechanism and catalytic performance have always been the focus of attention. However, the active metal components are prone to leaching, agglomeration and poisoning, which leads to catalyst deactivation, which also limits its application range to some extent. Currently, there is a novel and promising strategy for constructing supported metal catalysts, which has shown significant advantages in the field of catalysis, especially under harsh conditions such as strong acidity, alkalinity and high temperature. The active center of the catalyst constructed by this strategy can still be stable.

[0004] The common synthesis methods of supported catalysts at present include confined growth method, in-situ deposition method, ion exchange reverse loading method, etc. For example, CN120132846A provides a polycrystalline silicon system catalyst technical field, specifically a preparation method of a polycrystalline silicon catalyst for new energy, which comprises the following steps: preparing mesoporous polystyrene microspheres; dispersing the mesoporous polystyrene microspheres in a metal salt solution for a precipitation reaction, dispersing the obtained supported polystyrene microspheres in ethanol, and then adding concentrated ammonia and tetraethyl orthosilicate for stirring reaction to obtain supported silica microspheres; and then calcining under a carbon monoxide atmosphere to obtain a polycrystalline silicon system catalyst. The invention improves the stability of the catalyst by dissolving a large amount of mesopores on the polystyrene microspheres, loading and precipitating metal salts, and then loading them by sol-gel method, and the catalyst has high efficiency and high stability in the reaction of preparing glycerol carbonate from glycerol. CN119237021A provides a supported catalyst and a preparation method thereof, which comprises the following steps: preparing a double-ligand nickel complex solution, dissolving a tertiary butyl modified bis(1-methyl imidazolyl) ethane and 1,10-phenanthroline in anhydrous ethanol, stirring, adding a nickel salt, and stirring again to obtain a double-ligand nickel complex solution; preparing an alumina-silica composite carrier, adding a caffeine solution and a lye to a mixed solution of an aluminum precursor solution and a silicon precursor solution, and having great application potential in the hydrogenation catalyst technical field. However, these synthesis methods mainly have the following two problems, firstly, the material mesopore has poor order; the pore size distribution is uneven; the channels are not connected, which easily leads to mass transfer limitation. Secondly, the metal dispersion in the carrier is poor; the metal active center structure has non-uniformity; the metal and the carrier have weak interaction force, and the metal is prone to migration, aggregation, loss and other phenomena. In addition, due to low metal utilization rate, the catalyst metal consumption is large for reaction requirements. SUMMARY

[0005] In view of the above defects of the prior art, the technical problems to be solved by the present application are that the existing supported metal catalyst and its preparation method have problems such as uncontrollable porous structure, poor metal dispersion, poor metal stability, difficult to control active center structure, large amount of metal, etc. The present application provides a post-supported metal catalyst, a preparation method and an application, which realizes the stable effect of the carrier on single-atom palladium through the lattice confinement of titanium dioxide on the surface of ordered mesoporous carbon composite titanium oxide carrier, enhances the interaction between the metal and the carrier, effectively avoids the problem of metal elution in a long reaction process, improves the catalytic activity, selectivity and stability of the palladium catalyst, reduces the amount of noble metal, and can avoid the acid washing process to remove unstable metal, saving time and cost.

[0006] To achieve the above object, the application provides a preparation method of a post-loaded metal catalyst, first, a series of ligands containing different elements are introduced to pre-functionalize the phenolic aldehyde resin, then the solvent evaporation and calcination process is performed to form an ordered mesoporous carbon composite titanium oxide carrier, then the mixed metal precursor is impregnated on the carrier, and through the hydrogen reduction process, a supported monatomic palladium catalyst with 100% metal utilization rate is formed.

[0007] Further, the phenolic aldehyde resin is pre-functionalized by introducing a series of ligands containing different elements, specifically including selecting a carbon source and an auxiliary agent to be uniformly dispersed in an organic solution of an alkaline catalyst; the low molecular weight polymer of phenol and formaldehyde is obtained by fully stirring at 50-80 ℃, and the low molecular weight phenolic aldehyde resin polymer is obtained by adjusting the pH value.

[0008] Further, the carbon source includes one or more of phenol, m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene and formaldehyde; the mass content of the carbon source is 5-30%.

[0009] Further, the ligand precursor solution includes one or more of triphenyl borate, triphenyl phosphite, mercapto malic acid and urea.

[0010] Further, the ordered mesoporous carbon composite titanium oxide carrier is prepared, specifically including placing titanium tetrachloride solvent, phenolic aldehyde resin and template agent in an aqueous solution to adjust the concentration of the phenolic aldehyde resin, allowing the phenolic aldehyde resin and the template agent to form a resin-template single beam through hydrogen bonding force, then placing the resin-template single beam on a clean surface dish after reacting for 1 h under constant temperature conditions of 45 ℃, and baking in an oven for 48 h at 105 ℃, so that the resin-template single beam is further crosslinked to form a low-energy cubic closed packing mesostructure; after the assembly is completed, calcination is performed at 350 ℃, and finally the ordered mesoporous carbon composite titanium oxide carrier is obtained by washing with deionized water and drying.

[0011] Further, the metal palladium monatomic atom is impregnated on the ordered mesoporous carbon composite titanium oxide carrier, specifically including pre-mixing a plurality of metal solutions including palladium chloride ethanol solution, palladium nitrate aqueous solution and palladium acetylacetone tetrahydrofuran solution into a metal precursor solution, then immersing the ordered mesoporous carbon composite titanium oxide carrier in the metal source precursor solution, uniformly dispersing the metal source precursor solution on the ordered mesoporous carbon composite titanium oxide carrier through ultrasonic, and finally forming a supported monatomic palladium catalyst in situ through hydrogen hot reduction.

[0012] Further, the metal precursor solution includes one or two of palladium chloride, palladium nitrate and palladium acetylacetone.

[0013] Further, the hydrogen concentration during the in-situ hydrogen hot reduction stage is maintained between 5-15%, and the hot reduction temperature is maintained between 300-700 ℃.

[0014] In a preferred embodiment of the present application, a post-supported metal catalyst is provided, which is obtained by the above preparation method.

[0015] Further, the application provides a use of the post-supported monatomic palladium catalyst in a reaction of preparing cyclohexanone by hydrogenation of phenol and a reaction of preparing cyclohexanedione by hydrogenation of resorcinol.

[0016] Technical effects

[0017] The present application provides a post-supported metal catalyst, a preparation method and a use, wherein the preparation method of the catalyst has simple synthesis steps, is suitable for preparation of various post-supported catalysts, and the catalyst has high catalytic activity and good stability. The catalyst exhibits excellent catalytic performance in a hydrogenation reaction of resorcinol, and achieves 100% conversion of resorcinol and ≥99% selectivity of 1,3-cyclohexanedione under the reaction conditions.

[0018] The concept, specific structure and technical effects of the present application will be further described below with reference to the accompanying drawings, so as to fully understand the purposes, features and effects of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image of Pd / B-TiO2-C of Example 1 of the present application;

[0020] Figure 2 is an X-ray diffraction (XRD) image of Pd / B-TiO2-C of Example 1 of the present application;

[0021] Figure 3 is a nitrogen isothermal adsorption / desorption curve of Pd / B-TiO2-C of Example 1 of the present application;

[0022] Figure 4 is an element distribution (mapping) image of Pd / B-TiO2-C of Example 1 of the present application. DETAILED DESCRIPTION

[0023] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clearly understood, the present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0024] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular procedures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0025] The present application provides a preparation method of a post-loaded monatomic palladium catalyst and its application, which comprises the following steps: first, preparing a low-order phenolic resin; then, co-assembling the low-order phenolic resin, a titanium tetrachloride precursor solution and a template agent to form a mesoporous carbon precursor solution; after drying and calcination, an ordered mesoporous carbon composite titanium oxide carrier is formed; then, impregnating a metal precursor solution on the carrier; and finally, through a hydrogen reduction process, a post-loaded metal catalyst is formed.

[0026] The specific process is as follows:

[0027] (1) The phenolic resin is pre-functionalized by introducing a series of ligands containing different elements (such as B, N, P, S), which specifically includes uniformly dispersing the carbon source and the auxiliary agent in an aqueous solution; under the condition of 50-80 o C, the low-molecular-weight polymer of phenol and formaldehyde is obtained by fully stirring, and the low-molecular-weight phenolic resin polymer is obtained by adjusting the pH value.

[0028] The carbon source includes one or more of phenol, m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene and formaldehyde; and the mass content of the carbon source is 5-30%. The auxiliary agent includes one or more of melamine, urea, boric acid, mercaptosilane and triphenyl phosphite.

[0029] (2) The phenolic resin, the template agent and the ligand solution in step (1) are placed in an aqueous solution to adjust the concentration of the phenolic resin; under the condition of low concentration, the phenolic resin and the template agent form a precursor solution through hydrogen bonding force; then, the resin-template agent is further self-assembled in a high-temperature oven at 100-130 o C for 12-24 h, and is spontaneously assembled into a low-energy cubic closed packing mesostructure; after calcination, an ordered mesoporous channel structure is formed; finally, the mesoporous carbon-titania carrier is formed by washing with deionized water and drying. The pH value of the low-concentration phenolic resin solution is 6-8; the structure-directing agent used is one or both of the amphiphilic block copolymers, triblock copolymer F127 (EO 106 PO 70 EO 106 ) and P123 (EO 20 PO 70 EO 20 ); and the reaction temperature is 40 o C, and the reaction time is 6 h.

[0030] (3) The ordered mesoporous carbon composite titanium oxide carrier in step (2) is immersed in a metal source precursor solution, and the metal precursor is uniformly dispersed on the ordered mesoporous carbon composite titanium oxide carrier through ultrasonic treatment, and finally an in-situ formed post-loaded metal catalyst is formed through hydrogen reduction. The metal source includes one of palladium chloride, palladium nitrate, palladium acetylacetone, and tin tetrachloride. The mass fraction ratio of the first metal to the second metal oxide in the metal precursor solution is 1:500 (400-600), specifically one of 1:400, 1:450, 1:500, 1:550, and 1:600.

[0031] The hydrogen concentration during the hydrogen reduction process stage is maintained between 5-15%, and the heat reduction temperature is maintained between 400-700 o C. The reduction stage includes a first high-temperature calcination stage and a second high-temperature calcination stage. The first high-temperature calcination stage is to remove the block copolymer in an inert atmosphere to obtain a bimetallic alloy-carbon polymer, and the second high-temperature calcination stage is to obtain a post-loaded metal catalyst through reduction in a hydrogen atmosphere.

[0032] The embodiment of the present application provides a post-loaded metal catalyst obtained by the preparation method.

[0033] The embodiment of the present application provides an application of the post-loaded metal catalyst in the directional hydrogenation reaction of resorcinol.

[0034] The embodiment of the present application provides a post-loaded metal catalyst, a preparation method and an application thereof, and a single-atom palladium catalyst doped with different elements (B, N, P, S, and C) and loaded on an ordered mesoporous carbon composite titanium oxide. First, low-order phenolic resin (PF) synthesized in the foregoing is used as a precursor, amphoteric triblock copolymer F127 is used as a template agent, ethanol is used as a solvent, titanium tetrachloride is used as a titanium source, and triphenyl borate is used as a boron source (urea is a nitrogen source, triphenyl phosphite is a phosphorus source, mercapto malic acid is a sulfur source, and low-order phenolic resin is a carbon source). A solvent evaporation induced self-assembly method is used to obtain one or more of triphenyl borate, triphenyl phosphite, mercapto malic acid, and urea doped with different elements. Then, the catalyst carrier is placed in a tube furnace for high-temperature calcination and carbonization to remove the surfactant, and an ordered mesoporous carbon composite titanium oxide carrier doped with different elements is obtained, which is sequentially named as X-TiO2-C (X=B, N, P, S). After wet impregnation and hydrogen reduction, the obtained catalyst has the characteristics of high specific surface area, high dispersion, high mass transfer, low production cost, easy separation, and good cycle stability, and has a wide application prospect in the fields of biomass conversion, medicine and fine chemical production, etc.

[0035] The following specific embodiments will illustrate the post-supported metal catalyst, its preparation method, and its application provided by the present invention.

[0036] Example 1:

[0037] (1) Preparation of ordered mesoporous carbon composite titanium dioxide support

[0038] 5 g of low-order phenolic resin, 1.5 mL of deionized water, 15 g of anhydrous ethanol, 1 mL of titanium tetrachloride solution, and a 3% (w / w) ligand precursor solution (one or more of triphenylboronic acid ester, triphenyl phosphite, mercaptomalic acid, and urea) were uniformly dispersed in a solution and heated to 45 °C. o The low molecular weight polymer of phenol and formaldehyde was obtained by thorough stirring at C. Then, block copolymer F127 was added, and after stirring for 6 h, the solution was further evenly spread on a clean petri dish and heated to 100°C. o After drying in an oven at C for 12 h, and filtering and drying, the Pd / X-TiO2-C (X=B, N, P, S) ordered mesoporous carbon composite titanium dioxide carriers doped with different elements were obtained by calcination in an inert atmosphere at 700℃.

[0039] (2) Introduction and growth of supported metals

[0040] Weigh out the palladium chloride metal precursor solution, and take 100 mg of the ordered mesoporous carbon composite titanium dioxide support Pd / X-TiO2-C (X=B, N, P, S) obtained in step (1) and immerse it in the metal precursor solution. Introduce the metal and metal oxide precursors by wet chemical method, and then reduce it in a hydrogen atmosphere at 250°C for 1 h to finally obtain the ordered mesoporous carbon composite titanium dioxide supported palladium single-atom catalyst Pd / X-TiO2-C (X=B, N, P, S) as shown. Figure 1 As shown, the Pd / B-TiO2-C catalyst in this embodiment is a boron-doped ordered mesoporous carbon composite titanium dioxide supported palladium single-atom catalyst with a highly uniform pore size distribution, as... Figure 2 As shown, the mesoporous carbon-titanium dioxide support for the catalyst in this embodiment is body-centered cubic (BCC). Im3(-) m The structure is such that the metal is highly dispersed on the carrier surface; for example... Figure 3 As shown, the calculated specific surface area of ​​the catalyst is 300 m². 2 / g, pore volume 0.25 cm³ 3 / g; such as Figure 4 As shown, Pd is uniformly distributed in the ordered mesoporous carbon composite titanium dioxide support.

[0041] 0.01 g of the boron-doped ordered mesoporous carbon composite titanium dioxide supported single-atom palladium catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate were added to the reactor, and the mixture was heated to 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of the product 1,3-cyclohexanedione in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0042] Example 2:

[0043] Unlike Example 1, at 100 o Dry in a forced-air drying oven for 24 hours.

[0044] Add 0.01 g of the mesoporous carbon composite titanium dioxide supported Pd metal catalyst Pd / B-TiO2-C obtained above, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0045] Example 3:

[0046] Unlike Example 1, at 100 o Dry in a forced-air drying oven for 48 hours.

[0047] Add 0.01 g of the above-obtained supported single-atom palladium catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0048] Example 4:

[0049] Unlike Example 1, at 80 o Dry in a forced-air drying oven for 12 hours.

[0050] Add 0.01 g of the mesoporous carbon composite titanium dioxide supported Pd metal catalyst Pd / B-TiO2-C obtained above, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0051] Example 5:

[0052] Unlike Example 1, at 80 o Dry in a forced-air drying oven for 24 hours.

[0053] Add 0.01 g of the above-obtained supported single-atom palladium catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0054] Example 6:

[0055] Unlike Example 1, at 80 o Dry in a forced-air drying oven for 48 hours.

[0056] Add 0.01 g of the above-obtained supported single-atom palladium Pd catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0057] Example 7:

[0058] Unlike Example 1, at 120 o Dry in a forced-air drying oven for 12 hours.

[0059] Add 0.01 g of the above-obtained supported single-atom palladium catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. oThe reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0060] Example 8:

[0061] Unlike Example 1, at 120 o Dry in a forced-air drying oven for 24 hours.

[0062] Add 0.01 g of the above-obtained supported single-atom palladium catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0063] Example 9:

[0064] Unlike Example 1, at 120 o Dry in a forced-air drying oven for 48 hours.

[0065] Add 0.01 g of the above-obtained supported single-atom palladium catalyst Pd / B-TiO2-C, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0066] Example 10:

[0067] Unlike Example 1, a metal-metal oxide precursor solution (Pd:TiO2 = 1:400) was used.

[0068] Example 11:

[0069] Unlike Example 1, a metal-metal oxide precursor solution (Pd:TiO2 = 1:450) was used.

[0070] Example 12:

[0071] Unlike Example 1, a metal-metal oxide precursor solution (Pd:TiO2 = 1:500) was used.

[0072] Example 13:

[0073] Unlike Example 1, a metal-metal oxide precursor solution (Pd:TiO2 = 1:550) was used.

[0074] Example 14:

[0075] Unlike Example 1, a metal-metal oxide precursor solution (Pd:TiO2 = 1:600) was used.

[0076] Add the above-obtained supported single-atom palladium catalyst (Pd / B-TiO2-C) with the same metal content as in Example 1, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0077] Table 1

[0078]

[0079] Comparative Example 1:

[0080] 0.01 g of the nitrogen-doped ordered mesoporous carbon composite titanium dioxide supported single-atom palladium catalyst Pd / N-TiO2-C obtained above, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate were added to the reactor, and the mixture was heated to 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0081] Comparative Example 2:

[0082] Add 0.01 g of the sulfur-doped ordered mesoporous carbon composite titanium dioxide supported single-atom palladium catalyst (Pd / S-TiO2-C), 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0083] Comparative Example 3:

[0084] Add 0.01 g of the phosphorus-doped ordered mesoporous carbon composite titanium dioxide supported single-atom palladium catalyst (Pd / P-TiO2-C), 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0085] Comparative Example 4:

[0086] Add 0.01 g of the ordered mesoporous carbon composite titanium dioxide supported single-atom palladium catalyst Pd / TiO2-C obtained above, 5 mL of H2O, 1 mmol of resorcinol, and 1 mmol of anhydrous sodium carbonate to the reactor, and heat at 80 °C. o The reaction was heated at 2 MPa H2 for 1 h. After the reaction was completed, the solid catalyst was separated by centrifugation, and the reaction solution was extracted with 5 mL of ethyl acetate as the extractant. The content of products in the reaction was detected by gas chromatography, and the results are shown in Table 1.

[0087] Table 2. Experimental Results of Comparative Examples 1-4

[0088]

[0089] The post-supported metal catalyst of this invention enables the directional hydrogenation of resorcinol under mild conditions. This catalyst has the advantages of high activity, high selectivity, and green reaction.

[0090] The catalyst of this invention utilizes the confinement effect of carbon-composite titanium dioxide on single-atom palladium to enhance the strong interaction between the support and the metal. The overall synthesis steps are simple, green, and efficient, and it is suitable for the preparation of various post-supported metal catalysts. Applying the catalyst of this invention to the selective hydrogenation of resorcinol yields 100% substrate conversion and 100% selectivity in the 1,3-cyclohexanedione reaction. The reaction process is green and efficient, with high catalyst activity and good stability, showing promising application prospects.

[0091] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a post-laden metal catalyst, characterized by, First, the phenolic resin is pre-functionalized by introducing a series of ligands containing different elements, and then the ordered mesoporous carbon composite titanium oxide carrier is formed through solvent evaporation and calcination process, then the mixed metal precursor is impregnated on the carrier, and the supported monatomic palladium catalyst with 100% metal utilization rate is formed through hydrogen reduction process.

2. The method of claim 1, wherein the metal catalyst is a post-laden metal catalyst. The phenolic resin is pre-functionalized by introducing a series of ligands containing different elements, specifically including selecting a carbon source and an auxiliary agent to be uniformly dispersed in an organic solution of an alkaline catalyst; the low molecular weight polymer of phenol and formaldehyde is obtained by fully stirring at 50-80 ℃, and the functionalized phenolic resin polymer is obtained by adjusting the pH value.

3. The method of claim 2, wherein the metal catalyst is a post-laden metal catalyst. The carbon source includes one or more of phenol, m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene and formaldehyde; the mass content of the carbon source is 5-30%.

4. The method of claim 2, wherein the metal catalyst is a post-loaded metal catalyst. The ligand includes one or more of triphenyl borate, urea, triphenyl phosphite and mercapto malic acid.

5. The method for preparing a post-supported metal catalyst as described in claim 1, characterized in that, The ordered mesoporous carbon composite titanium oxide carrier is prepared, specifically including placing titanium tetrachloride solvent, phenolic resin and template agent in an aqueous solution to adjust the concentration of the phenolic resin, allowing the phenolic resin and the template agent to form resin-template single micelles through hydrogen bonding force, then placing the resin-template single micelles on a clean surface dish in a constant temperature condition of 45℃ for 1 h, and then baking in an oven at 105℃ for 48 h, so that the resin-template single micelles are further crosslinked to form a low-energy cubic closed packing mesostructure; after assembly, calcination is performed at 350℃, and finally the ordered mesoporous carbon composite titanium oxide carrier is obtained by washing with deionized water and drying.

6. A process for the preparation of a supported metal catalyst according to claim 5, characterized in that The ordered mesoporous carbon composite titanium oxide carrier is loaded with metal palladium monatomic, specifically including pre-mixing a plurality of metal solutions, including palladium chloride ethanol solution, palladium nitrate aqueous solution and palladium acetylacetone tetrahydrofuran solution, into a metal precursor solution, then immersing the ordered mesoporous carbon composite titanium oxide carrier in the metal precursor solution, uniformly dispersing the metal precursor solution on the ordered mesoporous carbon composite titanium oxide carrier through ultrasonic treatment, and finally forming a supported monatomic palladium catalyst through hydrogen reduction.

7. A process for the preparation of a post-laden metal catalyst as claimed in claim 6, wherein, The metal precursor solution includes one or two of palladium chloride, palladium nitrate and palladium acetylacetone.

8. The method of claim 6, wherein the metal catalyst is a post-laden metal catalyst. The hydrogen concentration in the hydrogen reduction stage is maintained at 5-15%, and the heat reduction temperature is maintained at 300-700℃.

9. A post-laden metal catalyst characterized in that, Obtained by the preparation method of any one of claims 1-8.

10. The use of the supported monatomic palladium catalyst of claim 9 in the reaction of phenol hydrogenation to prepare cyclohexanone and m-dihydroxybenzene hydrogenation to prepare cyclohexanedione.

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