Alpha, beta-unsaturated aldehyde aqueous-phase hydrogenation hollow multilayer structure catalyst and preparation method thereof

Abstract

The application relates to the technical field of catalytic materials, and discloses an alpha, beta-unsaturated aldehyde aqueous-phase hydrogenation hollow multi-layer structure catalyst and a preparation method thereof, which comprises the following preparation steps: the aqueous-phase hydrogenation hollow multi-layer structure catalyst is based on hollow porous SiO2, the inner cavity has highly dispersed active metal M1, the surface of the hollow porous SiO2 is coated with a porous carbon layer, the pores of the hollow porous SiO2 and the porous carbon layer have strongly adhered active metal M3, the outer surface is loaded with partially reduced metal oxide and a hydrophobic carbon layer formed by chemical bonding of a silane coupling agent; the design has hydrogen activation center active metals M1 and M3 and oxygen vacancies in the oxide of the alpha, beta-unsaturated aldehyde activation center, reduces the competitive adsorption of hydrogen and alpha, beta-unsaturated aldehyde at the same active site, cooperates with the enrichment effect of the hydrophobic hollow structure on hydrogen, and constructs an efficient reaction microenvironment.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials technology, specifically to a hollow multilayer structure catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes and its preparation method. Background Technology

[0002] α,β-Unsaturated alcohols are key intermediates in the production of fragrances, flavorings, pharmaceuticals, and fine chemicals, and have wide applications in organic synthesis. α,β-Unsaturated aldehyde molecules contain both C=C and C=O groups. From a thermodynamic and kinetic perspective, the hydrogenation of C=C is superior to that of C=O. This makes achieving high selectivity in the hydrogenation of C=O to unsaturated alcohols a long-standing core challenge in the field of catalysis. Traditional supported catalysts (such as noble metals like Pt and Pd supported on metal oxide supports) struggle to effectively distinguish between these two functional groups, often preferentially hydrogenating the C=C bond to form saturated aldehydes, resulting in low selectivity for the target unsaturated alcohol.

[0003] To improve the selective hydrogenation performance of C=O bonds, various strategies have been developed, including introducing a second metal promoter (such as Fe, Co, etc.) to generate electronic / geometric modification effects, and utilizing Lewis acidic sites on the support surface to preferentially adsorb and activate C=O bonds. In addition, water, as a green reaction medium, has been shown to promote C=O bond activation through polar effects and participate in the proton transfer process. However, the extremely low solubility of hydrogen in the aqueous phase limits the efficiency of aqueous hydrogenation of α,β-unsaturated aldehydes, and existing catalyst systems still need to be improved in terms of activity, selectivity, and stability.

[0004] Therefore, developing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes that is suitable for aqueous reaction conditions and possesses both high activity and high selectivity is of significant academic importance and practical value. Summary of the Invention

[0005] One of the objectives of this invention is to address the problems of low hydrogen solubility in water, competitive adsorption of reaction substrates in conventional supported catalysts, poor selectivity for target products, and easy leaching of active components under operating conditions leading to catalyst deactivation. This invention provides a hollow multilayer structure catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes. This catalyst can increase the enrichment and activation capacity of hydrogen, accelerate the reaction rate, improve reaction selectivity, and exhibit excellent catalytic stability.

[0006] The technical solution of the present invention:

[0007] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0008] S1. After adsorbing a soluble metal M1 salt solution with hollow porous SiO2, glucose and a 30% potassium hydroxide solution are coated on the surface. After sintering reduction and carbonization, the mixture is cooled to room temperature to obtain an M1@SiO2@porous carbon layer.

[0009] S2. Metal particles M3 are supported on M1@SiO2@porous carbon layers and then mixed with the M2 precursor solution. After drying, calcination and reduction, the surface is modified with a silane coupling agent to obtain an aqueous hydrogenation hollow multilayer structure catalyst.

[0010] Further, step S1 specifically involves: the soluble metal M1 salt solution is prepared by mixing soluble metal M1 salt and deionized water at a mass ratio of 1:(30-50); the hollow porous SiO2 and the soluble metal M1 salt solution are mixed and stirred at 40-50℃ for 20-30 min for adsorption; the mixture is then dried in an oven at 70℃ for 30 min to obtain a mixture; the mixture is then mixed with glucose and a 30% potassium hydroxide solution; after stirring evenly, the mixture is placed in a reaction furnace and subjected to sintering reduction and sintering carbonization; and then cooled to room temperature to obtain an M1@SiO2@porous carbon layer.

[0011] Furthermore, in the above reaction process, hollow porous SiO2 and soluble metal M1 salt solution are mixed. Hollow porous SiO2 has high adsorption performance, which allows the soluble metal M1 salt solution to enter the interior of hollow porous SiO2 to form a mixture. After the mixture is mixed with carbon precursor and activator potassium hydroxide solution, reducing gases hydrogen and nitrogen are introduced. After sintering and reduction, active metal (M1) with a particle size of 5-10 nm is attached to the inner cavity of hollow porous SiO2. Then, nitrogen is introduced and carbonized by sintering to achieve the coating of porous carbon layer on the surface of hollow porous SiO2, resulting in M1@SiO2@porous carbon layer.

[0012] The mass ratio of glucose to potassium hydroxide solution was determined to be (1.9-2.1):(1.3-1.4), so that the pore size of the porous carbon layer is 20-50 nm, forming a double-layer porous structure with the hollow porous SiO2 with a pore size of 10-15 nm.

[0013] Further, the mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:(1.9-2.1):(1.3-1.4).

[0014] Furthermore, the sintering reduction specifically involves: introducing nitrogen and hydrogen gas, raising the temperature to 400-500℃ at a rate of 2-3℃ / min, and sintering and reducing for 1-2 hours.

[0015] Furthermore, the sintering and carbonization specifically involves: introducing nitrogen gas, heating to 700-800℃ at a rate of 2-3℃ / min, and sintering and carbonizing for 1-2 hours.

[0016] Furthermore, the mass ratio of the hollow porous SiO2 to the soluble metal M1 salt solution is 1:(40-42).

[0017] Furthermore, the volume ratio of nitrogen to hydrogen is 1:(8-10).

[0018] Furthermore, the soluble metal M1 salt is selected from any one of platinum nitrate, palladium nitrate, ruthenium nitrate, rhodium chloride, copper chloride, nickel nitrate, and cobalt nitrate.

[0019] Furthermore, step S2 specifically includes:

[0020] A1. The soluble metal M3 salt solution is prepared by mixing soluble metal M3 salt and deionized water at a mass ratio of 1:(30-50). The M1@SiO2@porous carbon layer and the soluble metal M3 salt solution are mixed and stirred at 40-50℃ for 20-30 min for adsorption. The mixture is then placed in a reactor, and nitrogen and hydrogen are introduced. The temperature is increased to 400-500℃ at a rate of 2-3℃ / min. The mixture is then sintered at a constant temperature for 4-5 h and cooled to room temperature to obtain M1@SiO2@porous carbon layer@M3.

[0021] A2. The precursor solution of M2 is prepared by mixing M2 and deionized water at a mass ratio of (0.3-0.4):(20-30). M1@SiO2@porous carbon layer@M3 and the precursor solution of M2 are mixed, and 36% ammonia water is added to adjust the pH to 8-10. The mixture is stirred at room temperature for 30 min, placed in a reactor, and stirred at 280-320℃ for 5-6 h. Nitrogen and hydrogen are introduced, and the temperature is increased to 280-320℃ at a rate of 2-3℃ / min. The mixture is then reduced and sintered for 4-5 h to obtain M1@SiO2@porous carbon layer@oxide-M3.

[0022] A3. Mix M1@SiO2@porous carbon layer@oxide-M3, silane coupling agent, ethanol and deionized water, stir evenly, add 0.1mol / L hydrochloric acid to adjust the pH to 4-5, stir at 50-60℃ for 1-2h, filter, wash 3 times with deionized water, and dry in an oven at 50℃ for 10h to obtain an aqueous phase hydrogenation hollow multilayer structure catalyst.

[0023] Furthermore, in the A1 reaction process described above, the M1@SiO2@porous carbon layer and the soluble metal M3 salt solution are mixed. The surface of the M1@SiO2@porous carbon layer contains abundant porous structures, which can adsorb the soluble metal M3 salt into the pores and surface of the porous carbon. Nitrogen and hydrogen are introduced, and the mixture is sintered at a constant temperature of 400-500℃ for 4-5 hours to form active metal M3 in the pores and surface of the M1@SiO2@porous carbon layer, thus obtaining the M1@SiO2@porous carbon layer@M3.

[0024] Furthermore, in the above A2 reaction process, the M1@SiO2@porous carbon layer@M3 and M2 precursor solutions are mixed, and ammonia water is added to adjust the pH to 8-10. The hydroxide of M2 can be deposited on the surface of M1@SiO2@porous carbon layer@M3. The reaction is stirred at 280-320℃ for 5-6 hours. The hydroxide decomposes upon heating to form oxides, thus forming partially reducible oxides on the surface of M1@SiO2@porous carbon layer@M3, resulting in M1@SiO2@porous carbon layer@oxide-M3.

[0025] Furthermore, during the A3 reaction described above, the silanol groups generated by the hydrolysis of the silane coupling agent can chemically bond with the hydroxyl groups on the surface of M1@SiO2@porous carbon layer@oxide-M3, thereby forming a hydrophobic layer on the surface of M1@SiO2@porous carbon layer@oxide-M3 and obtaining a hollow multilayer structure catalyst for aqueous hydrogenation.

[0026] Further, in step A1, the mass ratio of the M1@SiO2@porous carbon layer to the soluble metal M3 salt solution is 1:(40-42).

[0027] Furthermore, in step A1, the soluble metal M3 salt is selected from any one of nickel nitrate, cobalt nitrate, and copper nitrate.

[0028] Further, in step A2, the mass ratio of the precursor solutions M1@SiO2@porous carbon layer@M3 and M2 is 1:(30-32).

[0029] Furthermore, in step A2, M2 is selected from any one of cerium nitrate, indium nitrate, and ammonium metavanadate.

[0030] Further, in step A3, the mass ratio of M1@SiO2@porous carbon layer@oxide-M3, silane coupling agent, ethanol and deionized water is 1:(0.05-0.1):(15-20):(4-5).

[0031] Further, in step A3, the silane coupling agent is selected from any one of methyltrimethoxysilane, octyltrimethoxysilane, and isobutyltriethoxysilane.

[0032] The present invention has the following beneficial effects:

[0033] (1) In the technical solution of the present invention, the aqueous phase hydrogenation hollow multilayer structure catalyst is based on hollow porous SiO2, with highly dispersed active metal M1 in the inner cavity, a porous carbon layer coated on the surface of the hollow porous SiO2, and active metal M3 strongly attached in the channels of the hollow porous SiO2 and the porous carbon layer. The outer surface is loaded with partially reducible metal oxides and a hydrophobic carbon layer formed by chemical bonding of silane coupling agent. This design has hydrogen activation center active metals M1 and M3 and oxygen vacancies in α,β-unsaturated aldehyde activation center oxides. This reduces the competitive adsorption of hydrogen and α,β-unsaturated aldehydes at the same active site, and the synergistic effect of the hydrophobic hollow structure on hydrogen enrichment creates a highly efficient reaction microenvironment. When used for the aqueous hydrogenation of α,β-unsaturated aldehydes, the hydrophobic layer effectively enriches hydrogen within the hollow porous SiO2, where it is activated by M1 and M3. Oxygen vacancies in the oxide further facilitate the activation of α,β-unsaturated aldehydes, thus significantly improving catalytic conversion and selectivity. Furthermore, the hydrophobic layer inhibits metal leaching in the aqueous phase, enhancing the catalyst's stability in the aqueous phase.

[0034] (2) In the technical solution of the present invention, an active metal M1 is attached to the inner cavity of hollow porous SiO2; then, nitrogen gas is introduced and carbonized by sintering to achieve the coating of a porous carbon layer on the surface of hollow porous SiO2, resulting in M1@SiO2@porous carbon layer. On the one hand, the formed porous carbon layer has a high adsorption capacity and porous structure, which can attach a large amount of active metal M3 in the pores of hollow porous SiO2 and porous carbon layer. Moreover, the adsorption performance of hollow porous SiO2 and porous carbon layer can enhance the hydrogen enrichment capacity and obtain a higher reaction rate and stability. On the other hand, by utilizing the adsorption performance of porous carbon layer, the active metals M1 and M3 in the inner cavity and pores of hollow porous SiO2 can be fixed, avoiding the active metals M1 and M3 from falling off during the use of the catalyst and affecting the catalytic performance.

[0035] (3) In the technical solution of the present invention, an active metal M3 is formed in the pores of the M1@SiO2@porous carbon layer. The active metal M1 in the hollow porous SiO2 cavity and the active metal M3 in the pores of the hollow porous SiO2 and porous carbon layer form a bimetallic series connection, which can increase the hydrogen activation sites, improve the reaction rate and catalyst stability; a partially reducible oxide is formed on the surface of the M1@SiO2@porous carbon layer@M3. The oxygen vacancies contained in the formed oxide serve as activation centers for α,β-unsaturated aldehydes, preferentially undergoing strong coordination with the C=O double bonds in the α,β-unsaturated aldehydes, thus making The C=O double bond is close to the catalyst, enabling selective hydrogenation of α,β-unsaturated aldehydes to form unsaturated alcohols. The silane coupling agent forms a hydrophobic layer on the surface of M1@SiO2@porous carbon layer@oxide-M3, which can effectively enrich hydrogen in the hollow multilayer structure of the catalyst cavity and channels in aqueous hydrogenation. It is activated by the active metals M1 and M3, avoiding the extremely low solubility of hydrogen in water, which would limit the contact between the reactants and the catalyst in the aqueous phase and affect the yield of the hydrogenation product unsaturated alcohol. In addition, the hydrophobic carbon layer can effectively inhibit the leaching of active metals in the aqueous phase and improve the stability of the catalyst in the aqueous phase. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the working principle of the aqueous phase hydrogenation hollow multilayer structure catalyst of the present invention.

[0037] Figure 2 This is a SEM image of the hollow multilayer structure catalyst for aqueous hydrogenation of the present invention. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0040] Hollow porous SiO2 is spherical with a diameter of 100-500 nm, a pore size of 10-15 nm, and a thickness of 20-100 nm.

[0041] Hollow porous SiO2 is prepared by the following steps:

[0042] Mix 0.15g citric acid, 15mL deionized water, and 10mL ethanol, and stir until completely dissolved. Adjust the pH to 10 with 25% ammonia solution. Add 0.2g resorcinol and 0.3g formaldehyde (37% by mass), and stir for 10h. Add 0.8g tetraethyl orthosilicate, 0.6mL ammonia solution (36% by mass), and 30mL ethanol, and continue stirring for 10h. Collect the solid by centrifugation. Wash the solid four times with hydrochloric acid (pH 1), and wash with deionized water until the pH of the washing solution is neutral. Dry in a 70℃ oven for 10min to obtain hollow porous SiO2.

[0043] The soluble metal salt M1 is platinum nitrate, the soluble metal salt M3 is nickel nitrate, and M2 is cerium nitrate.

[0044] The silane coupling agent is octyltrimethoxysilane.

[0045] The metal precursor is nickel nitrate.

[0046] Example 1

[0047] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0048] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0049] The platinum@SiO2@porous carbon layer is specifically as follows:

[0050] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:30. Hollow porous SiO2 and platinum nitrate solution were mixed and stirred at 40℃ for 20 min for adsorption. The mixture was then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture was then mixed with glucose and a 30% potassium hydroxide solution and stirred until homogeneous. The mixture was placed in a reactor and nitrogen and hydrogen were introduced. The temperature was increased to 400℃ at a rate of 2℃ / min. After sintering and reduction for 1 h, nitrogen was introduced and the temperature was increased to 700℃ at a rate of 2℃ / min. The mixture was then sintered and carbonized for 1 h. After cooling to room temperature, a platinum@SiO2@porous carbon layer was obtained.

[0051] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:40;

[0052] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:1.9:1.3.

[0053] The volume ratio of nitrogen to hydrogen is 1:8;

[0054] S2. Platinum@SiO2@porous carbon layer supported nickel metal particles are mixed with cerium nitrate precursor solution, dried, calcined and reduced, and then modified with silane coupling agent to obtain aqueous hydrogenation hollow multilayer structure catalyst.

[0055] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0056] A1. The nickel nitrate solution was prepared by mixing nickel nitrate and deionized water at a mass ratio of 1:30. Platinum@SiO2@porous carbon layer and nickel nitrate solution were mixed and stirred at 40℃ for 20 min for adsorption. The mixture was placed in a reaction furnace, nitrogen and hydrogen were introduced, and the temperature was raised to 400℃ at a rate of 2℃ / min. The mixture was sintered at a constant temperature for 4 h and then cooled to room temperature to obtain platinum@SiO2@porous carbon layer@nickel.

[0057] The mass ratio of platinum@SiO2@porous carbon layer to nickel nitrate solution is 1:40;

[0058] A2. The cerium nitrate precursor solution was prepared by mixing cerium nitrate and deionized water at a mass ratio of 0.3:20. Platinum@SiO2@porous carbon layer@nickel was mixed with the cerium nitrate precursor solution, and 36% ammonia water was added to adjust the pH to 8. The mixture was stirred at room temperature for 30 min, placed in a reactor, and stirred at 280℃ for 5 h. Nitrogen and hydrogen were introduced, and the temperature was increased to 280℃ at a rate of 2℃ / min. The mixture was then reduced and sintered for 4 h to obtain platinum@SiO2@porous carbon layer@cerium oxide-nickel.

[0059] The mass ratio of platinum@SiO2@porous carbon layer@nickel and cerium nitrate precursor solution is 1:30;

[0060] A3. Platinum@SiO2@porous carbon layer@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water were mixed and stirred until homogeneous. The pH was adjusted to 4 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 50°C for 1 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 50°C for 10 h to obtain an aqueous phase hydrogenation hollow multilayer catalyst. The mass ratio of platinum@SiO2@porous carbon layer@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water was 1:0.05:15:4.

[0061] Example 2

[0062] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0063] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0064] The platinum@SiO2@porous carbon layer is specifically as follows:

[0065] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:40. Hollow porous SiO2 and platinum nitrate solution were mixed and stirred at 45℃ for 25 min for adsorption. The mixture was then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture was then mixed with glucose and a 30% potassium hydroxide solution and stirred until homogeneous. The mixture was then placed in a reactor, and nitrogen and hydrogen were introduced. The temperature was increased to 450℃ at a rate of 2.5℃ / min. After sintering and reduction for 1.5 h, nitrogen was introduced and the temperature was increased to 750℃ at a rate of 2.5℃ / min. The mixture was then sintered and carbonized for 1.5 h. After cooling to room temperature, a platinum@SiO2@porous carbon layer was obtained.

[0066] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:41;

[0067] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:2:1.35;

[0068] The volume ratio of nitrogen to hydrogen is 1:9;

[0069] S2. Platinum@SiO2@porous carbon layer supported nickel metal particles are mixed with cerium nitrate precursor solution, dried, calcined and reduced, and then modified with silane coupling agent to obtain aqueous hydrogenation hollow multilayer structure catalyst.

[0070] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0071] A1. The nickel nitrate solution was prepared by mixing nickel nitrate and deionized water in a mass ratio of 1:(30-50). Platinum@SiO2@porous carbon layer and nickel nitrate solution were mixed and stirred at 45℃ for 25 min for adsorption. The mixture was then placed in a reactor, and nitrogen and hydrogen were introduced. The temperature was increased to 450℃ at a rate of 2.5℃ / min, and sintered at a constant temperature for 4.5 h. After cooling to room temperature, platinum@SiO2@porous carbon layer@nickel was obtained.

[0072] The mass ratio of platinum@SiO2@porous carbon layer to nickel nitrate solution is 1:(40-42);

[0073] A2. The cerium nitrate precursor solution was prepared by mixing cerium nitrate and deionized water at a mass ratio of 0.35:25. Platinum@SiO2@porous carbon layer@nickel was mixed with the cerium nitrate precursor solution, and 36% ammonia was added to adjust the pH to 9. The mixture was stirred at room temperature for 30 min, placed in a reactor, and stirred at 300℃ for 5.5 h. Nitrogen and hydrogen were introduced, and the temperature was increased to 300℃ at a rate of 2.5℃ / min. The mixture was then reduced and sintered for 4.5 h to obtain platinum@SiO2@porous carbon layer@cerium oxide-nickel.

[0074] The mass ratio of platinum@SiO2@porous carbon layer@nickel and cerium nitrate precursor solution is 1:(30-32);

[0075] A3. Platinum@SiO2@porous carbon layer@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water were mixed and stirred until homogeneous. The pH was adjusted to 4.5 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 55℃ for 1.5 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 50℃ for 10 h to obtain an aqueous phase hydrogenation hollow multilayer catalyst. The mass ratio of platinum@SiO2@porous carbon layer@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water was 1:0.08:18:4.5.

[0076] Example 3

[0077] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0078] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0079] The platinum@SiO2@porous carbon layer is specifically as follows:

[0080] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:50. Hollow porous SiO2 and platinum nitrate solution were mixed and stirred at 50℃ for 30 min for adsorption. The mixture was then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture was then mixed with glucose and a 30% potassium hydroxide solution and stirred until homogeneous. The mixture was placed in a reactor and nitrogen and hydrogen were introduced. The temperature was increased to 500℃ at a rate of 3℃ / min. After sintering and reduction for 2 h, nitrogen was introduced and the temperature was increased to 800℃ at a rate of 3℃ / min. The mixture was then sintered and carbonized for 2 h. After cooling to room temperature, a platinum@SiO2@porous carbon layer was obtained.

[0081] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:42;

[0082] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:2.1:1.4.

[0083] The volume ratio of nitrogen to hydrogen is 1:10;

[0084] S2. Platinum@SiO2@porous carbon layer supported nickel metal particles are mixed with cerium nitrate precursor solution, dried, calcined and reduced, and then modified with silane coupling agent to obtain aqueous hydrogenation hollow multilayer structure catalyst.

[0085] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0086] A1. The nickel nitrate solution was prepared by mixing nickel nitrate and deionized water at a mass ratio of 1:50. Platinum@SiO2@porous carbon layer and nickel nitrate solution were mixed and stirred at 50°C for 30 min for adsorption. The mixture was then placed in a reactor, and nitrogen and hydrogen were introduced. The temperature was increased to 500°C at a rate of 3°C / min, and sintered at a constant temperature for 5 h. After cooling to room temperature, platinum@SiO2@porous carbon layer@nickel was obtained.

[0087] The mass ratio of platinum@SiO2@porous carbon layer to nickel nitrate solution is 1:42;

[0088] A2. The cerium nitrate precursor solution was prepared by mixing cerium nitrate and deionized water at a mass ratio of 0.4:30. Platinum@SiO2@porous carbon layer@nickel was mixed with the cerium nitrate precursor solution, and 36% ammonia was added to adjust the pH to 10. The mixture was stirred at room temperature for 30 min, placed in a reactor, and stirred at 320℃ for 6 h. Nitrogen and hydrogen were introduced, and the temperature was increased to 320℃ at a rate of 3℃ / min. The mixture was then reduced and sintered for 5 h to obtain platinum@SiO2@porous carbon layer@cerium oxide-nickel.

[0089] The mass ratio of platinum@SiO2@porous carbon layer@nickel and cerium nitrate precursor solution is 1:32;

[0090] A3. Platinum@SiO2@porous carbon layer@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water were mixed and stirred until homogeneous. The pH was adjusted to 5 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 60℃ for 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 50℃ for 10 h to obtain an aqueous phase hydrogenation hollow multilayer catalyst. The mass ratio of platinum@SiO2@porous carbon layer@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water was 1:0.1:20:5.

[0091] Comparative Example 1

[0092] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0093] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0094] Platinum@SiO2 specifically refers to:

[0095] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:50. Hollow porous SiO2 and platinum nitrate solution were mixed and adsorbed at 50℃ for 30 min, dried in an oven at 70℃ for 30 min, placed in a reaction furnace, and nitrogen and hydrogen were introduced. The temperature was increased to 500℃ at a rate of 3℃ / min. After sintering and reduction for 2 h, platinum@SiO2 was obtained.

[0096] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:42;

[0097] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:2.1:1.4.

[0098] The volume ratio of nitrogen to hydrogen is 1:10;

[0099] S2. Platinum@SiO2 is used to support nickel metal particles, which are then mixed with cerium nitrate precursor solution. After drying, calcination and reduction, the surface is modified with silane coupling agent to obtain an aqueous hydrogenation hollow multilayer structure catalyst.

[0100] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0101] A1. The nickel nitrate solution is prepared by mixing nickel nitrate and deionized water at a mass ratio of 1:50. Platinum@SiO2 and nickel nitrate solution are mixed and stirred at 50°C for 30 min for adsorption. The mixture is placed in a reaction furnace, nitrogen and hydrogen are introduced, and the temperature is raised to 500°C at a rate of 3°C / min. The mixture is sintered at a constant temperature for 5 h and then cooled to room temperature to obtain platinum@SiO2@nickel.

[0102] The mass ratio of platinum@SiO2 to nickel nitrate solution is 1:42;

[0103] A2. The cerium nitrate precursor solution was prepared by mixing cerium nitrate and deionized water at a mass ratio of 0.4:30. Platinum@SiO2@nickel and M2 precursor solution were mixed, and ammonia water with a mass fraction of 36% was added to adjust the pH to 10. The mixture was stirred at room temperature for 30 min, placed in a reactor, and stirred at 320℃ for 6 h. Nitrogen and hydrogen were introduced, and the temperature was increased to 320℃ at a rate of 3℃ / min. The mixture was then reduced and sintered for 5 h to obtain platinum@SiO2@cerium oxide-nickel.

[0104] The mass ratio of platinum@SiO2@nickel and cerium nitrate precursor solution is 1:32;

[0105] A3. Platinum@SiO2@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water were mixed and stirred until homogeneous. The pH was adjusted to 5 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 60°C for 2 hours. After filtration, the mixture was washed three times with deionized water and dried in an oven at 50°C for 10 hours to obtain an aqueous phase hydrogenation hollow multilayer catalyst. The mass ratio of platinum@SiO2@cerium oxide-nickel, octyltrimethoxysilane, ethanol, and deionized water was 1:0.1:20:5.

[0106] Comparative Example 2

[0107] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0108] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0109] The platinum@SiO2@porous carbon layer is specifically as follows:

[0110] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:50. Hollow porous SiO2 and platinum nitrate solution were mixed and stirred at 50℃ for 30 min for adsorption. The mixture was then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture was then mixed with glucose and a 30% potassium hydroxide solution and stirred until homogeneous. The mixture was placed in a reactor and nitrogen and hydrogen were introduced. The temperature was increased to 500℃ at a rate of 3℃ / min. After sintering and reduction for 2 h, nitrogen was introduced and the temperature was increased to 800℃ at a rate of 3℃ / min. The mixture was then sintered and carbonized for 2 h. After cooling to room temperature, a platinum@SiO2@porous carbon layer was obtained.

[0111] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:42;

[0112] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:2.1:1.4.

[0113] The volume ratio of nitrogen to hydrogen is 1:10;

[0114] S2. A hollow multilayer catalyst for aqueous hydrogenation was obtained by mixing a platinum@SiO2@porous carbon layer with a cerium nitrate precursor solution, followed by drying, calcination and reduction, and then surface modification with a silane coupling agent.

[0115] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0116] A1. The cerium nitrate precursor solution was prepared by mixing cerium nitrate and deionized water at a mass ratio of 0.4:30. Platinum@SiO2@porous carbon layer and cerium nitrate precursor solution were mixed, and ammonia water with a mass fraction of 36% was added to adjust the pH to 10. The mixture was stirred at room temperature for 30 min, placed in a reactor, and stirred at 320℃ for 6 h. Nitrogen and hydrogen were introduced, and the temperature was increased to 320℃ at a rate of 3℃ / min. The mixture was then reduced and sintered for 5 h to obtain platinum@SiO2@porous carbon layer@cerium oxide.

[0117] The mass ratio of platinum@SiO2@porous carbon layer to cerium nitrate precursor solution is 1:32;

[0118] A2. Platinum@SiO2@porous carbon layer@cerium oxide, octyltrimethoxysilane, ethanol, and deionized water were mixed and stirred until homogeneous. The pH was adjusted to 5 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 60℃ for 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 50℃ for 10 h to obtain an aqueous phase hydrogenation hollow multilayer catalyst. The mass ratio of platinum@SiO2@porous carbon layer@cerium oxide, octyltrimethoxysilane, ethanol, and deionized water was 1:0.1:20:5.

[0119] Comparative Example 3

[0120] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0121] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0122] The platinum@SiO2@porous carbon layer is specifically as follows:

[0123] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:50. Hollow porous SiO2 and platinum nitrate solution were mixed and stirred at 50℃ for 30 min for adsorption. The mixture was then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture was then mixed with glucose and a 30% potassium hydroxide solution and stirred until homogeneous. The mixture was placed in a reactor and nitrogen and hydrogen were introduced. The temperature was increased to 500℃ at a rate of 3℃ / min. After sintering and reduction for 2 h, nitrogen was introduced and the temperature was increased to 800℃ at a rate of 3℃ / min. The mixture was then sintered and carbonized for 2 h. After cooling to room temperature, a platinum@SiO2@porous carbon layer was obtained.

[0124] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:42;

[0125] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:2.1:1.4.

[0126] The volume ratio of nitrogen to hydrogen is 1:10;

[0127] S2. A hollow multilayer catalyst for aqueous hydrogenation was obtained by supporting nickel metal particles on a platinum@SiO2@porous carbon layer and then modifying the surface with a silane coupling agent.

[0128] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0129] A1. The nickel nitrate solution was prepared by mixing nickel nitrate and deionized water at a mass ratio of 1:50. Platinum@SiO2@porous carbon layer and nickel nitrate solution were mixed and stirred at 50°C for 30 min for adsorption. The mixture was then placed in a reactor, and nitrogen and hydrogen were introduced. The temperature was increased to 500°C at a rate of 3°C / min, and sintered at a constant temperature for 5 h. After cooling to room temperature, platinum@SiO2@porous carbon layer@nickel was obtained.

[0130] The mass ratio of platinum@SiO2@porous carbon layer to nickel nitrate solution is 1:42;

[0131] A2. Platinum@SiO2@porous carbon layer@nickel, octyltrimethoxysilane, ethanol, and deionized water were mixed and stirred until homogeneous. The pH was adjusted to 5 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 60℃ for 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 50℃ for 10 h to obtain an aqueous phase hydrogenation hollow multilayer catalyst. The mass ratio of platinum@SiO2@porous carbon layer@nickel, octyltrimethoxysilane, ethanol, and deionized water was 1:0.1:20:5.

[0132] Comparative Example 4

[0133] A method for preparing a hollow multilayer catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes includes the following preparation steps:

[0134] S1. After adsorbing platinum nitrate solution with hollow porous SiO2, glucose and 30% potassium hydroxide solution are coated, followed by sintering reduction, sintering carbonization, and cooling to room temperature to obtain platinum@SiO2@porous carbon layer.

[0135] The platinum@SiO2@porous carbon layer is specifically as follows:

[0136] The platinum nitrate solution was prepared by mixing platinum nitrate and deionized water at a mass ratio of 1:50. Hollow porous SiO2 and platinum nitrate solution were mixed and stirred at 50℃ for 30 min for adsorption. The mixture was then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture was then mixed with glucose and a 30% potassium hydroxide solution and stirred until homogeneous. The mixture was placed in a reactor and nitrogen and hydrogen were introduced. The temperature was increased to 500℃ at a rate of 3℃ / min. After sintering and reduction for 2 h, nitrogen was introduced and the temperature was increased to 800℃ at a rate of 3℃ / min. The mixture was then sintered and carbonized for 2 h. After cooling to room temperature, a platinum@SiO2@porous carbon layer was obtained.

[0137] The mass ratio of hollow porous SiO2 to platinum nitrate solution is 1:42;

[0138] The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:2.1:1.4.

[0139] The volume ratio of nitrogen to hydrogen is 1:10;

[0140] S2. Platinum@SiO2@porous carbon layer supported nickel metal particles, then mixed with cerium nitrate precursor solution, and after drying, calcination and reduction, an aqueous phase hydrogenation hollow multilayer structure catalyst was obtained.

[0141] The hollow multilayer structure catalyst for aqueous hydrogenation is specifically:

[0142] A1. The nickel nitrate solution was prepared by mixing nickel nitrate and deionized water at a mass ratio of 1:50. Platinum@SiO2@porous carbon layer and nickel nitrate solution were mixed and stirred at 50°C for 30 min for adsorption. The mixture was then placed in a reactor, and nitrogen and hydrogen were introduced. The temperature was increased to 500°C at a rate of 3°C / min, and sintered at a constant temperature for 5 h. After cooling to room temperature, platinum@SiO2@porous carbon layer@nickel was obtained.

[0143] The mass ratio of platinum@SiO2@porous carbon layer to nickel nitrate solution is 1:42;

[0144] A2. The cerium nitrate precursor solution was prepared by mixing cerium nitrate and deionized water at a mass ratio of 0.4:30. Platinum@SiO2@porous carbon layer@nickel and M2 precursor solution were mixed, and 36% ammonia water was added to adjust the pH to 10. The mixture was stirred at room temperature for 30 min, placed in a reactor, and stirred at 320℃ for 6 h. Nitrogen and hydrogen were introduced, and the temperature was increased to 320℃ at a rate of 3℃ / min. The mixture was then reduced and sintered for 5 h to obtain platinum@SiO2@porous carbon layer@cerium oxide-nickel.

[0145] The mass ratio of platinum@SiO2@porous carbon layer@nickel and cerium nitrate precursor solution is 1:32.

[0146] The performance of the hollow multilayer structure catalysts for aqueous hydrogenation prepared in Examples 1-3 and Comparative Examples 1-4 was tested.

[0147] The aqueous-phase hydrogenation hollow multilayer catalyst prepared above was used for the aqueous-phase selective catalytic hydrogenation of citral, cinnamaldehyde, and furfural, respectively. The catalytic hydrogenation activity was evaluated in a 250 mL high-pressure reactor. The citral reaction system consisted of 0.3 g of the aqueous-phase hydrogenation hollow multilayer catalyst prepared above, 0.7 mL of citral, and 50 mL of deionized water. The reaction was carried out at 140 °C, 3 MPa hydrogen pressure, and 750 r / min stirring speed for 6 h.

[0148] The cinnamaldehyde reaction system consisted of 1g of the aqueous hydrogenation hollow multilayer catalyst prepared above, 1mL of cinnamaldehyde and 60mL of deionized water, reacted at 80℃, 1.5MPa hydrogen pressure and 900r / min stirring speed for 3h.

[0149] The furfural reaction system consisted of 0.6 g of the aqueous hydrogenation hollow multilayer catalyst prepared above, 1 mL of furfural, and 80 mL of deionized water. The reaction was carried out at 90 °C, 0.5 MPa hydrogen pressure, and 950 r / min stirring speed for 6 h.

[0150] After the reaction was completed, the mixture was centrifuged and the reaction product was taken. The product was detected by gas chromatography, and the conversion rate, selectivity and yield were measured.

[0151] The test results are shown in Table 1 below.

[0152] Table 1 Performance testing of aqueous phase hydrogenation hollow multilayer structure catalysts prepared in Examples 1-3 and Comparative Examples 1-4

[0153] Example 1 97.6 86.8 84.7 Example 2 98.3 87.6 86.1 Example 3 96.5 85.9 82.9 Comparative Example 1 85.1 74.6 63.5 Comparative Example 2 87.3 75.9 66.3 Comparative Example 3 83.6 71.2 59.5 Comparative Example 4 80.6 69.7 56.2

[0154] Table 2 Performance testing of aqueous phase hydrogenation hollow multilayer structure catalysts prepared in Examples 1-3 and Comparative Examples 1-4

[0155] Example 1 95.6 97.1 94.8 Example 2 96.9 98.4 95.3 Example 3 94.9 96.8 93.7 Comparative Example 1 83.1 85.9 71.4 Comparative Example 2 85.1 87.9 74.8 Comparative Example 3 81.7 82.3 67.2 Comparative Example 4 78.6 80.1 63.0

[0156] Table 3 Performance testing of aqueous phase hydrogenation hollow multilayer structure catalysts prepared in Examples 1-3 and Comparative Examples 1-4

[0157] Example 1 94.7 96.3 92.7 Example 2 95.2 97.9 93.2 Example 3 93.4 95.6 91.8 Comparative Example 1 82.7 84.5 69.9 Comparative Example 2 84.6 86.7 73.3 Comparative Example 3 80.3 81.6 65.5 Comparative Example 4 77.9 78.9 61.5

[0158] As can be seen from the data in Table 1, the hollow multilayer structure catalyst for aqueous hydrogenation prepared in Examples 1-3 is based on hollow porous SiO2. The inner cavity contains a highly dispersed active metal M1, the surface of the hollow porous SiO2 is coated with a porous carbon layer, the channels of the hollow porous SiO2 and the porous carbon layer contain strongly attached active metal M3, and the outer surface is loaded with partially reducible metal oxides and a hydrophobic carbon layer formed by chemical bonding of silane coupling agents. This significantly improves the catalytic conversion rate and the selectivity of unsaturated alcohol products in the aqueous hydrogenation reaction of α,β-unsaturated aldehydes.

[0159] Comparative Example 1 shows that a hollow multilayered catalyst for aqueous hydrogenation, prepared by replacing the platinum@SiO2@porous carbon layer with platinum@SiO2, was used for the hydrogenation catalysis of α,β-unsaturated aldehydes. The yield of the hydrogenation product, unsaturated alcohol, decreased, demonstrating that coating the M1@SiO2 surface with a porous carbon layer resulted in the M1@SiO2@porous carbon layer. The formed porous carbon layer has a high adsorption capacity and porous structure, enabling the attachment of a large amount of active metal M3 in the pores of the hollow porous SiO2 and the porous carbon layer. Furthermore, the adsorption performance of the hollow porous SiO2 and the porous carbon layer enhances the hydrogen enrichment capacity, resulting in a higher reaction rate and stability. In addition, the adsorption performance of the porous carbon layer can fix the active metals M1 and M3 in the cavity and pores of the hollow porous SiO2, preventing the active metals M1 and M3 from falling off during catalyst use and affecting catalytic performance.

[0160] Comparative Example 2 shows that a hollow multilayer catalyst for aqueous hydrogenation was prepared by replacing platinum@SiO2@porous carbon layer@nickel with platinum@SiO2@porous carbon layer. This catalyst was used for the hydrogenation catalysis of α,β-unsaturated aldehydes. The yield of the hydrogenation product, unsaturated alcohol, decreased, demonstrating that an active metal M3 is formed in the pores of M1@SiO2@porous carbon layer. The active metal M1 in the hollow porous SiO2 cavity and the active metal M3 in the pores of the hollow porous SiO2 and porous carbon layer form a bimetallic series, which can increase the hydrogen activation sites, improve the reaction rate, and enhance the catalyst stability.

[0161] Comparative Example 3 used a hollow multilayer catalyst for aqueous hydrogenation prepared by replacing platinum@SiO2@porous carbon layer@cerium oxide-nickel with platinum@SiO2@porous carbon layer@nickel. This catalyst was used for the hydrogenation catalysis of α,β-unsaturated aldehydes. The yield of the hydrogenation product, unsaturated alcohol, decreased, demonstrating that a partially reducible oxide was formed on the surface of M1@SiO2@porous carbon layer@M3. The oxygen vacancies in this oxide act as activation centers for α,β-unsaturated aldehydes, preferentially coordinating strongly with the C=O double bonds in the α,β-unsaturated aldehydes. This brings the C=O double bonds close to the catalyst, achieving selective hydrogenation of α,β-unsaturated aldehydes to form unsaturated alcohols.

[0162] Comparative Example 4: The aqueous hydrogenation hollow multilayer catalyst prepared without octyltrimethoxysilane modification was used for the hydrogenation catalysis of α,β-unsaturated aldehydes. The yield of the hydrogenation product, unsaturated alcohol, decreased, demonstrating that the silane coupling agent forms a hydrophobic layer on the surface of M1@SiO2@porous carbon layer@oxide-M3. This effectively enriches hydrogen in the cavity and channels of the aqueous hydrogenation hollow multilayer catalyst, where it is activated by the active metals M1 and M3. This avoids the extremely low solubility of hydrogen in water, which limits the contact between the reactants and the catalyst in the aqueous phase and affects the yield of the hydrogenation product, unsaturated alcohol. Furthermore, the hydrophobic carbon layer effectively inhibits the leaching of the active metals in the aqueous phase, improving the stability of the catalyst in the aqueous phase.

[0163] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0164] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing a hollow multilayer structure catalyst for the aqueous hydrogenation of α,β-unsaturated aldehydes, characterized in that, The preparation steps include the following: S1. After adsorbing a soluble metal M1 salt solution with hollow porous SiO2, glucose and a 30% potassium hydroxide solution are coated on the surface. After sintering reduction and carbonization, the mixture is cooled to room temperature to obtain an M1@SiO2@porous carbon layer. The soluble metal M1 salt solution is prepared by mixing soluble metal M1 salt and deionized water at a mass ratio of 1:(30-50); The soluble metal M1 salt is selected from any one of platinum nitrate, palladium nitrate, ruthenium nitrate, rhodium chloride, copper chloride, nickel nitrate, and cobalt nitrate. S2. Metal particles M3 are supported on M1@SiO2@porous carbon layers and then mixed with the M2 precursor solution. After drying, calcination and reduction, the surface is modified with a silane coupling agent to obtain an aqueous hydrogenation hollow multilayer structure catalyst. Step S2 specifically involves: A1. The soluble metal M3 salt solution is prepared by mixing soluble metal M3 salt and deionized water at a mass ratio of 1:(30-50). The M1@SiO2@porous carbon layer and the soluble metal M3 salt solution are mixed and stirred at 40-50℃ for 20-30 min for adsorption. The mixture is then placed in a reactor, and nitrogen and hydrogen are introduced. The temperature is increased to 400-500℃ at a rate of 2-3℃ / min. The mixture is then sintered at a constant temperature for 4-5 h and cooled to room temperature to obtain M1@SiO2@porous carbon layer@M3. A2. Mix the M1@SiO2@porous carbon layer@M3 and M2 precursor solutions, add 36% ammonia water to adjust the pH to 8-10, stir at room temperature for 30 min, place in a reactor, stir and react at 280-320℃ for 5-6 h, introduce nitrogen and hydrogen, raise the temperature to 280-320℃ at a rate of 2-3℃ / min, reduce and sinter for 4-5 h to obtain M1@SiO2@porous carbon layer@oxide-M3; A3. Mix M1@SiO2@porous carbon layer@oxide-M3, silane coupling agent, ethanol and deionized water, stir evenly, add 0.1mol / L hydrochloric acid to adjust the pH to 4-5, stir at 50-60℃ for 1-2h, filter, wash 3 times with deionized water, and dry in an oven at 50℃ for 10h to obtain an aqueous phase hydrogenation hollow multilayer structure catalyst. M2 is selected from any one of cerium nitrate, indium nitrate, and ammonium metavanadate. The soluble metal M3 salt is selected from any one of nickel nitrate, cobalt nitrate, and copper nitrate.

2. The method for preparing an α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to claim 1, characterized in that, Step S1 specifically involves: The soluble metal M1 salt solution is prepared by mixing soluble metal M1 salt and deionized water at a mass ratio of 1:(30-50). Hollow porous SiO2 and the soluble metal M1 salt solution are mixed and stirred at 40-50℃ for 20-30 min for adsorption. The mixture is then dried in an oven at 70℃ for 30 min to obtain a mixture. The mixture is then mixed with glucose and a 30% potassium hydroxide solution and stirred evenly. The mixture is then placed in a reaction furnace and subjected to sintering reduction and sintering carbonization. After cooling to room temperature, an M1@SiO2@porous carbon layer is obtained.

3. The method for preparing an α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to claim 2, characterized in that, The sintering reduction specifically involves: introducing nitrogen and hydrogen gas, raising the temperature to 400-500℃ at a rate of 2-3℃ / min, and sintering and reducing for 1-2 hours; The sintering and carbonization process specifically involves: introducing nitrogen gas, heating to 700-800℃ at a rate of 2-3℃ / min, and sintering and carbonizing for 1-2 hours.

4. The method for preparing an α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to claim 3, characterized in that, The mass ratio of the hollow porous SiO2 to the soluble metal M1 salt solution is 1:(40-42); The volume ratio of nitrogen to hydrogen is 1:(8-10); The mass ratio of the mixture, glucose, and potassium hydroxide solution is 1:(1.9-2.1):(1.3-1.4).

5. The method for preparing an α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to claim 1, characterized in that, In step A1, the mass ratio of the M1@SiO2@porous carbon layer to the soluble metal M3 salt solution is 1:(40-42).

6. The method for preparing an α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to claim 1, characterized in that, In step A2, the mass ratio of the precursor solutions M1@SiO2@porous carbon layer@M3 and M2 is 1:(30-32).

7. The method for preparing an α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to claim 1, characterized in that, In step A3, the mass ratio of M1@SiO2@porous carbon layer@oxide-M3, silane coupling agent, ethanol and deionized water is 1:(0.05-0.1):(15-20):(4-5); In step A3, the silane coupling agent is selected from any one of methyltrimethoxysilane, octyltrimethoxysilane, and isobutyltriethoxysilane.

8. An aqueous phase hydrogenation hollow multilayer structure catalyst prepared by the method for preparing the α,β-unsaturated aldehyde aqueous phase hydrogenation hollow multilayer structure catalyst according to any one of claims 1-7.

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