Preparation method and application of nano silicon dioxide core-shell structure catalyst

Abstract

The invention discloses a preparation method and application of a nano silicon dioxide core-shell structure catalyst. The preparation method of the Ru coated SiO2 core-shell structure catalyst comprises the following steps: adding a soluble Ru saline solution and hydrazine hydrate into a mixed solution of polyethylene glycol hexadecyl ether and cyclohexane, uniformly stirring, dropwise adding ammonia water while stirring, then dropwise adding a soluble silicon source, continuously stirring, and finally adding ethanol. After uniformly stirring, filtering, washing, drying, roasting and reducing to obtain the Ru coated SiO2 core-shell structure catalyst. The Ru-coated SiO2 catalyst prepared by the preparation method disclosed by the invention has the advantages of high target product selectivity, good anti-sintering stability and the like in a reaction for preparing organic amine through amide hydrodeoxygenation.

Description

Technical Field

[0001] The present invention belongs to the fields of heterogeneous catalysis and fine chemical engineering, and particularly relates to a preparation method and application of a nano-silica core-shell structure catalyst. Technical Background

[0002] Organic amines are one of the most important organic intermediates in the chemical industry and can be widely used in the synthesis of pesticides, dyes, surfactants, plastics, etc. Catalytic hydrogenation and deoxygenation of amides to the corresponding amines is the simplest and most direct synthetic route to obtain such important compounds. Therefore, the hydrogenation and deoxygenation reaction of amides has extremely high research value.

[0003] In the reaction of preparing organic amines by hydrogenation and deoxygenation of amides, Ru-based catalysts have excellent catalytic activity and selectivity for amines. Beamson et al. prepared a series of SiO 2 supported Ru-based catalysts for the hydrogenation and deoxygenation reaction of cyclohexanecarboxamide, and during the recycling process of the catalyst, the catalyst was deactivated due to the deposition of a large amount of amide or amine adsorbed on the catalyst surface (J. Catal. 2010, 269: 93 - 102.; Adv. Synth. Catal. 2010, 352: 869 - 883.; J. Catal. 2011, 278: 228 - 238.). During the catalyst regeneration process, although calcination treatment can remove the deposits, it inevitably brings the problem of complete deactivation of the catalyst due to the sintering of Ru nanoparticles. In addition, a large amount of by-product water is generated during the hydrogenation and deoxygenation reaction of amides. As the reaction proceeds, water accumulates continuously in the reaction system to form a hydrothermal system, which also requires the catalyst to have a certain hydrothermal stability. Therefore, designing a Ru-based catalyst with good stability in the catalytic hydrogenation and deoxygenation reaction of amides is a problem that must be considered.

[0004] Patent CN 112960676A discloses a preparation method of nano-SiO 2 core-shell structure particles. The silane coupling agent is hydrolyzed under acidic catalyst conditions, then added to orthosilicic acid, and then the mixed solution is mixed with silica sol and a basic catalyst, aged, and finally nano-SiO 2 core-shell structure particles are obtained. Patent CN 104923233A discloses a Ni@SiO 2 core-shell structure catalyst for catalytic hydrogenation and deoxygenation of guaiacol to cyclohexanol. That is, in an alcohol-water mixed solvent, nickel salt, polyvinylpyrrolidone, ammonia water, cetyltrimethylammonium bromide and a silicon source are added, and then after filtration, washing, drying, calcination and reduction, the prepared Ni@SiO 2 core-shell structure catalyst has excellent anti-sintering ability and catalytic stability. Thus, designing a catalyst with a core-shell structure is an effective means to maintain the high stability of the catalyst. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method and application of a nano-silica core-shell structure catalyst. Specifically, in a mixed solution of poly(ethylene glycol) cetyl ether and cyclohexane, a soluble Ru salt aqueous solution and hydrazine hydrate are first added, stirred evenly, and ammonia water is added dropwise while stirring. Then, a soluble silicon source is added dropwise, and stirring is continued. Finally, ethanol is added. After stirring evenly, through filtration, washing, drying, calcination, and reduction, a Ru@SiO 2 core-shell structure catalyst can be prepared. The obtained catalyst is applied to the reaction of catalytic amide hydrodeoxygenation to prepare organic amines, including the following steps:

[0006] (1) Dissolve poly(ethylene glycol) cetyl ether in cyclohexane. The mass of poly(ethylene glycol) cetyl ether is 5-50 wt.% of the total mass of the mixed solution. The dissolution of poly(ethylene glycol) cetyl ether and cyclohexane adopts the conventional operation methods in the art, including but not limited to water bath dissolution, oil bath dissolution, mechanical stirring dissolution, etc. Preferably, the mass of poly(ethylene glycol) cetyl ether is 20-35 wt.% of the total mass of the mixed solution.

[0007] (2) Add a soluble Ru salt aqueous solution dropwise to the mixed solution in step (1). The mass of the metal component Ru in the aqueous solution is 0.01-10 wt.% of the total mass of the catalyst. The soluble Ru salt used is one of Ru chloride, ammonia complex, and acetylacetone compound. Preferably, the mass of the metal component Ru in the aqueous solution is 0.1-5.0 wt.% of the total mass of the catalyst. Stir at 20-80 °C for 1-24 h. The mass concentration of Ru in the Ru salt aqueous solution is 0.01-0.5 g / mL. The volume ratio of the Ru salt aqueous solution to cyclohexane is 0.02-0.1.

[0008] (3) Add a hydrazine hydrate solution to the solution obtained in step (2) and stir for 1-6 h. The molar ratio of hydrazine hydrate to the metal component Ru is 1:1-10:1. Preferably, the molar ratio of hydrazine hydrate to the metal component Ru is 2:1-5:1. Preferably, the mass fraction of hydrazine hydrate in the hydrazine hydrate solution is 80 wt.%. Preferably, the stirring time is 4-6 h.

[0009] (4) Add ammonia water and a soluble silicon source to the solution obtained in step (3). The volume ratio of ammonia water to the silicon source is 1:1-10:1. Preferably, the volume ratio is 2:1-5:1. Preferably, the mass fraction of ammonia in the ammonia water is 25 wt.%. Preferably, the soluble silicon source is one of tetramethyl orthosilicate or tetraethyl orthosilicate.

[0010] (5) After adding ethanol, stir for 2-4 h. The volume ratio of ethanol to the silicon source is 1:1-10:1. Preferably, the volume ratio is 2:1-5:1.

[0011] (6) Filtration: Wash the filter cake with isopropanol, and dry the obtained filter cake at 60 - 120 °C for 2 - 6 h; After that, conduct grinding, and calcine at 200 - 600 °C for 2 - 4 h; Finally, reduce at 400 - 600 °C for 2 - 4 h to obtain the core - shell structure catalyst;

[0012] (7) In a batch reactor, load the catalyst with the molar ratio of active metal Ru to amide raw material being 1 - 5 mol%. After loading the organic solvent, heat it to the reaction temperature and pressurize it to the reaction pressure under a hydrogen atmosphere for reaction, and analyze the product by gas chromatography. Reaction conditions: reaction temperature 100 - 200 °C, reaction pressure 1 - 10 MPa, reaction time 0.5 - 12 h, and the organic solvent is one of cyclopentyl methyl ether, ethylene glycol dimethyl ether, n - hexane, cyclohexane, dioxane, and tetrahydrofuran.

[0013] The beneficial effects of the present invention are as follows: The Ru@SiO catalyst prepared by the preparation method of the present invention 2 has the advantages of high selectivity for the target product and good anti - sintering stability of the catalyst in the reaction of amide hydrodeoxygenation to prepare organic amines. Description of the Drawings

[0014] Figure 1 is the transmission electron microscope photograph of the core - shell structure catalyst obtained in Example 1.

[0015] Figure 2 is the transmission electron microscope photograph of the core - shell structure catalyst obtained in Example 2.

[0016] Figure 3 is the transmission electron microscope photograph of the core - shell structure catalyst obtained in Example 3.

[0017] Figure 4 is the transmission electron microscope photograph of the catalyst obtained in Comparative Example 1.

[0018] Figure 5 is the transmission electron microscope photograph of the catalyst obtained in Comparative Example 2.

[0019] Figure 6 is the transmission electron microscope photograph of the catalyst obtained in Comparative Example 3.

[0020] Figure 7 is the test result of the cyclic use of the core - shell structure catalyst obtained in Example 1. Detailed Embodiments

[0021] The following embodiments will further illustrate the present invention, but the present invention is not limited to the following embodiments. At the same time, the embodiments only give some of the conditions to achieve this purpose, and it does not mean that these conditions must be met to achieve this purpose.

[0022] Example 1

[0023] Weigh 20 g of cetyl polyethyleneglycol ether and measure 60 mL of cyclohexane. Stir and dissolve them in an oil bath at 50 °C.

[0024] Add 1.6 mL of an aqueous solution of RuCl with a concentration of 0.05 g / mL, and stir in an oil bath at 50 °C for 24 h. 3 Add 1 mL of hydrazine hydrate solution (hydrazine hydrate concentration 80 wt.%), and stir in an oil bath at 50 °C for 6 h.

[0025] While stirring, add 14 mL of concentrated ammonia water (concentrated ammonia water concentration 25 wt.%) and 7 mL of tetraethyl orthosilicate drop by drop, and stir in an oil bath at 50 °C for 2 h.

[0026] Add 15 mL of ethanol, and stir in an oil bath at 50 °C for 2 h.

[0027] Filter, wash the filter cake with isopropanol, dry the obtained filter cake at 120 °C for 2 h; after completion, grind it, calcine it at 500 °C in an air atmosphere for 4 h; finally, reduce it at 400 °C in a hydrogen atmosphere for 2 h to obtain the core-shell structured catalyst containing.

[0028] Ru@SiO

[0029] The transmission electron micrograph of the catalyst is as 2 shown. The catalyst consists of a spherical SiO shell with a diameter of 20 - 30 nm and Ru nanoparticles with a particle size of 2 - 4 nm. There is a Ru nanoparticle at the center of each spherical SiO, and the mass fraction of Ru in the catalyst is 4 wt.%. Figure 1 shell and Ru nanoparticles with a particle size of 2 - 4 nm. There is a Ru nanoparticle at the center of each spherical SiO, and the mass fraction of Ru in the catalyst is 4 wt.%. 2 shell and Ru nanoparticles with a particle size of 2 - 4 nm. There is a Ru nanoparticle at the center of each spherical SiO, and the mass fraction of Ru in the catalyst is 4 wt.%. 2 shell and Ru nanoparticles with a particle size of 2 - 4 nm. There is a Ru nanoparticle at the center of each spherical SiO, and the mass fraction of Ru in the catalyst is 4 wt.%.

[0030] Example 2

[0031] Weigh 25 g of cetyl polyethyleneglycol ether and measure 60 mL of cyclohexane. Stir and dissolve them in an oil bath at 50 °C.

[0032] Add 1.6 mL of an aqueous solution of RuCl with a concentration of 0.05 g / mL, and stir in an oil bath at 50 °C for 24 h. 3 Add 1 mL of hydrazine hydrate solution (hydrazine hydrate concentration 80 wt.%), and stir in an oil bath at 50 °C for 4 h.

[0033] Add 14 mL of concentrated ammonia water (concentrated ammonia water concentration 25 wt.%) and 3.5 mL of tetraethyl orthosilicate, and stir in an oil bath at 50 °C for 2 h.

[0034] Add 15 mL of ethanol, and stir in an oil bath at 50 °C for 2 h.

[0035] Add 15 mL of ethanol, and stir in an oil bath at 50 °C for 2 h.

[0036] Filter, wash the filter cake with isopropanol, and dry the obtained filter cake at 120 °C for 2 h; after that, grind it and calcine it at 500 °C for 4 h in an air atmosphere; finally, reduce it at 400 °C for 2 h in a hydrogen atmosphere to obtain the core-shell structured catalyst.

[0037] Ru@SiO 2 The transmission electron micrograph of the catalyst is as Figure 2 shown. The catalyst consists of spherical SiO with a diameter of 20 - 35 nm 2 shells and Ru nanoparticles with a particle size of 2 - 4 nm. There is a Ru nanoparticle at the center of each spherical SiO 2 shell, and the mass fraction of Ru in the catalyst is 4 wt.%.

[0038] Example 3

[0039] Weigh 20 g of cetyl polyglycol ether, measure 60 mL of cyclohexane, and stir and dissolve them in an oil bath at 50 °C.

[0040] Add 1.6 mL of an aqueous solution of RuCl 3 with a concentration of 0.05 g / mL, and stir in an oil bath at 50 °C for 24 h.

[0041] Add 1 mL of hydrazine hydrate solution (hydrazine hydrate concentration 80 wt.%), and stir in an oil bath at 50 °C for 1 h.

[0042] Add 35 mL of concentrated ammonia water (concentrated ammonia water concentration 25 wt.%) and 7 mL of tetraethyl orthosilicate, and stir in an oil bath at 50 °C for 2 h.

[0043] Add 35 mL of ethanol, and stir in an oil bath at 50 °C for 2 h.

[0044] Filter, wash the filter cake with isopropanol, and dry the obtained filter cake at 120 °C for 2 h; after that, grind it and calcine it at 500 °C for 4 h in an air atmosphere; finally, reduce it at 400 °C for 2 h in a hydrogen atmosphere to obtain the core-shell structured catalyst.

[0045] Ru@SiO 2 The transmission electron micrograph of the catalyst is as Figure 3 shown. The catalyst consists of spherical SiO with a diameter of 20 - 40 nm 2 shells and Ru nanoparticles with a particle size of 2 - 4 nm. There is a Ru nanoparticle at the center of each spherical SiO 2 shell, and the mass fraction of Ru in the catalyst is 4 wt.%.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 1 lies in the reagent addition order.

[0048] Weigh 20 g of polyethylene glycol cetyl ether, measure 60 mL of cyclohexane, and stir to dissolve in an oil bath at 50 °C.

[0049] Add 14 mL of concentrated ammonia water (concentration of concentrated ammonia water is 25 wt.%) and 7 mL of tetraethyl orthosilicate, and stir in an oil bath at 50 °C for 2 h.

[0050] Add 15 mL of ethanol, and stir in an oil bath at 50 °C for 2 h.

[0051] Add 1.6 mL of an aqueous solution of RuCl with a concentration of 0.05 g / mL, and stir in an oil bath at 50 °C for 24 h. 3 Add 1 mL of hydrazine hydrate solution (concentration of hydrazine hydrate is 80 wt.%), and stir in an oil bath at 50 °C for 6 h.

[0052] Filter, wash the filter cake with isopropanol, dry the obtained filter cake at 120 °C for 2 h; after completion, grind it, calcine it at 500 °C in an air atmosphere for 4 h; finally, reduce it at 400 °C in a hydrogen atmosphere for 2 h to obtain the catalyst.

[0053] The transmission electron micrograph of the catalyst is as

[0054] shown. The catalyst is composed of spherical SiO particles with a diameter of 20 - 30 nm and Ru nanoparticles with a particle size of 2 - 8 nm. The Ru nanoparticles are distributed on the surface of the spherical SiO. The mass fraction of Ru in the catalyst is 4 wt.%. Figure 4 shown, the catalyst consists of spherical SiO particles with a diameter of 20 - 30 nm and Ru nanoparticles with a particle size of 2 - 8 nm, and the Ru nanoparticles are distributed on the surface of the spherical SiO. The mass fraction of Ru in the catalyst is 4 wt.%. 2 particles and Ru nanoparticles with a particle size of 2 - 8 nm. The Ru nanoparticles are distributed on the surface of the spherical SiO. 2 The mass fraction of Ru in the catalyst is 4 wt.%.

[0055] Comparative Example 2

[0056] Weigh 20 g of polyethylene glycol cetyl ether, measure 60 mL of cyclohexane, and stir to dissolve in an oil bath at 50 °C.

[0057] Add 1.6 mL of an aqueous solution of RuCl with a concentration of 0.05 g / mL, and stir in an oil bath at 50 °C for 24 h. 3 Add 1 mL of hydrazine hydrate solution (concentration of hydrazine hydrate is 80 wt.%), and stir in an oil bath at 50 °C for 0.5 h.

[0058] Add 35 mL of concentrated ammonia water (concentration of concentrated ammonia water is 25 wt.%) and 7 mL of tetraethyl orthosilicate, and stir in an oil bath at 50 °C for 2 h.

[0059] Add 35 mL of ethanol, and stir in an oil bath at 50 °C for 2 h.

[0060] Filter, wash the filter cake with isopropanol, dry the obtained filter cake at 120 °C for 2 h; after completion, grind it, calcine it at 500 °C in an air atmosphere for 4 h; finally, reduce it at 400 °C in a hydrogen atmosphere for 2 h to obtain the catalyst described above.

[0061] Filter, wash the filter cake with isopropanol, dry the obtained filter cake at 120 °C for 2 h; after completion, grind it, calcine it at 500 °C in an air atmosphere for 4 h; finally, reduce it at 400 °C in a hydrogen atmosphere for 2 h to obtain the said catalyst.

[0062] The transmission electron microscope image of the catalyst is as Figure 5 shown. The catalyst is composed of spherical SiO with a diameter of 20 - 40 nm 2 and Ru nanoparticles with a particle size of 2 - 8 nm. There are aggregated Ru nanoparticles, and the mass fraction of Ru in the catalyst is 4 wt.%.

[0063] Comparative Example 3

[0064] Weigh 1 g of cetyl polyoxyethylene ether and measure 60 mL of cyclohexane, and stir and dissolve them in an oil bath at 50 °C.

[0065] Add 1.6 mL of an aqueous solution of RuCl at 0.05 g / mL 3 and stir in an oil bath at 50 °C for 24 h.

[0066] Add 1 mL of hydrazine hydrate solution (hydrazine hydrate concentration 80 wt.%) and stir in an oil bath at 50 °C for 6 h.

[0067] Add 35 mL of concentrated ammonia water (concentrated ammonia water concentration 25 wt.%) and 7 mL of tetraethyl orthosilicate, and stir in an oil bath at 50 °C for 2 h.

[0068] Add 35 mL of ethanol and stir in an oil bath at 50 °C for 2 h.

[0069] Filter, wash the filter cake with isopropanol, dry the obtained filter cake at 120 °C for 2 h; after completion, grind it, calcine it at 500 °C in an air atmosphere for 4 h; finally, reduce it at 400 °C in a hydrogen atmosphere for 2 h to obtain the described catalyst.

[0070] The transmission electron microscope image of the catalyst is as Figure 6 shown. The catalyst is composed of spherical SiO with a diameter of 20 - 40 nm 2 and Ru nanoparticles with a particle size of 2 - 20 nm. There are aggregated Ru nanoparticles, and the mass fraction of Ru in the catalyst is 4 wt.%.

[0071] Example 4

[0072] In a batch reactor, load the catalyst of Example 1. The molar ratio of the active metal Ru in the catalyst to the butyramide raw material is 5 mol%. After loading cyclopentyl methyl ether, heat it to the reaction temperature of 150 °C and pressurize it to the reaction pressure of 5 MPa in a hydrogen atmosphere for reaction for 4 h, and the product is analyzed by gas chromatography.

[0073] Example 5

[0074] In a batch reactor, the catalyst of Example 2 was loaded, and the molar ratio of the active metal Ru to the butyramide raw material in the catalyst was 5 mol%. After loading cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0075] Example 6

[0076] In a batch reactor, the catalyst of Example 3 was loaded, and the molar ratio of the active metal Ru to the butyramide raw material in the catalyst was 5 mol%. After loading cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0077] Comparative Example 4

[0078] In a batch reactor, the catalyst of the comparative example was loaded, and the molar ratio of the active metal Ru to the butyramide raw material in the catalyst was 5 mol%. After loading cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0079] Comparative Example 5

[0080] In a batch reactor, the catalyst of Comparative Example 2 was loaded, and the molar ratio of the active metal Ru to the butyramide raw material in the catalyst was 5 mol%. After loading cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0081] Comparative Example 6

[0082] In a batch reactor, the catalyst of Comparative Example 3 was loaded, and the molar ratio of the active metal Ru to the butyramide raw material in the catalyst was 5 mol%. After loading cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0083] Example 7

[0084] In a batch reactor, the catalyst of Example 1 was loaded, and the molar ratio of the active metal Ru to the N,N-dimethylhexanamide raw material in the catalyst was 5 mol%. After loading cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0085] Example 8

[0086] In a batch reactor, the catalyst of Example 1 was charged. The molar ratio of the active metal Ru to the caprolactam raw material in the catalyst was 5 mol%. After charging cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0087] Example 9

[0088] In a batch reactor, the catalyst of Example 1 was charged. The molar ratio of the active metal Ru to the benzamide raw material in the catalyst was 5 mol%. After charging cyclopentyl methyl ether, the temperature was raised to the reaction temperature of 150 °C under a hydrogen atmosphere and the pressure was increased to the reaction pressure of 5 MPa for reaction for 4 h. The product was analyzed by gas chromatography.

[0089] Table 1 Catalyst reaction evaluation results in Examples and Comparative Examples

[0090]

[0091]

[0092] The catalyst in Example 4 was filtered and recovered, and reused (the process and conditions were the same as those in the catalytic performance test) 4 times. Then the recovered catalyst was calcined in a muffle furnace at 500 °C in an air atmosphere for 4 h, reduced at 400 °C in a hydrogen atmosphere for 2 h, and then the 5th catalyst performance test was carried out (the process and conditions were the same as those in the catalytic performance test). The obtained reuse performance is as Figure 7 shown.

Claims

1. A preparation method of a nano-silica core-shell structure catalyst, characterized in that: In a mixed solution of cetyl polyethyleneglycol ether and cyclohexane, first add a soluble Ru salt aqueous solution and hydrazine hydrate, stir evenly, and gradually add ammonia water and a soluble silicon source dropwise while stirring, continue stirring, and finally add ethanol; after stirring evenly, through filtration, washing, drying, calcination and reduction, a Ru@SiO 2 core-shell structured catalyst can be prepared.

2. According to the method described in claim 1, characterized in that, comprising the following steps, (1) Dissolve cetyl polyoxyethylene ether in cyclohexane, and the mass of cetyl polyoxyethylene ether is 5-50 wt.% (preferably 20-35 wt.%) of the total mass of the mixed solution; (2) Dropwise add a soluble Ru salt aqueous solution to the mixed solution in step (1), and the mass of the metal component Ru in the aqueous solution is 0.01-10 wt.% of the total mass of the catalyst; stir at 20-80 °C for 1-24 h; (3) Add a hydrazine hydrate solution to the solution obtained in step (2), and the molar ratio of hydrazine hydrate to the metal component Ru is 1:1-10:1, stir for 1-6 h; (4) Add ammonia water and a soluble silicon source to the solution obtained in step (3), and the volume ratio of ammonia water to the silicon source is 1:1-10:1; (5) Add ethanol and stir for 2-4 h, and the volume ratio of ethanol to the silicon source is 1:1-10:1; (6) Filter, wash the filter cake with isopropanol, dry the obtained filter cake at 60-120 °C for 2-6 h; after completion, grind it, calcine it at 200-600 °C in an air atmosphere for 2-4 h; finally, reduce it at 400-600 °C in a hydrogen atmosphere for 2-4 h to obtain the core-shell structure catalyst.

3. According to the method described in claim 1 or 2, characterized in that: The soluble Ru salt used in step (2) is one or more of Ru chloride, ammonia complex, and acetylacetone compound; preferably, the mass of the metal component Ru in the aqueous solution is 0.1-5.0 wt.% of the total mass of the catalyst; preferably, the stirring temperature is 50-70 °C; the mass concentration of Ru in the Ru salt aqueous solution is 0.01-0.5 g / mL; the volume ratio of the Ru salt aqueous solution to cyclohexane is 0.02-0.

1.

4. According to the method described in claim 1 or 2, characterized in that: Preferably, the molar ratio of hydrazine hydrate to the metal component Ru in step (3) is 2:1-5:1; preferably, the mass fraction of hydrazine hydrate in the hydrazine hydrate solution is 70-90 wt.%; preferably, the stirring time is 4-6 h.

5. According to the method described in claim 1 or 2, characterized in that: Preferably, the volume ratio of ammonia water to the soluble silicon source in step (4) is 2:1-5:1; preferably, the mass fraction of ammonia in the ammonia water is 20-30 wt.%; preferably, the soluble silicon source is one or two of tetramethyl orthosilicate or tetraethyl orthosilicate.

6. According to the method described in claim 1 or 2, characterized in that: Preferably, the volume ratio of ethanol to the silicon source in step (5) is 2:1-5:

1.

7. A nano-silica core-shell structure catalyst prepared by the method described in any one of claims 1-6.

8. An application of the nano-silica core-shell structure catalyst described in claim 7 in the reaction of catalytic amide hydrodeoxygenation to prepare organic amines.

9. According to the application described in claim 8, characterized in that: In a batch reactor, the molar ratio of the active metal Ru in the loaded catalyst to the amide raw material is 1-5 mol%. After loading the organic solvent, it is heated to the reaction temperature under a hydrogen atmosphere and pressurized to the reaction pressure for reaction. Reaction conditions: reaction temperature 100-200 °C, reaction pressure 1-10 MPa, reaction time 0.5-12 h, and the organic solvent is one or more of cyclopentyl methyl ether, ethylene glycol dimethyl ether, n-hexane, cyclohexane, dioxane, and tetrahydrofuran.

10. The application according to claim 8 or 9, characterized in that: in the step (7), the preferred reaction temperature is 120-160 °C, the preferred reaction pressure is 4-8 MPa, and the preferred reaction time is 2-6 h; the amide is one or more of propionamide, butyramide, valeramide, hexanamide, benzamide, cyclohexanecarboxamide, N,N-dimethylhexanamide, and caprolactam.

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