A furfural water-phase hydrogenation multilayer core-shell structure catalyst and a preparation method thereof

Abstract

The application belongs to the field of catalytic materials, and particularly discloses a furfural water-phase hydrogenation multilayer core-shell structure catalyst and a preparation method thereof. The catalyst takes the uniformly loaded NiCu-Ni3Si2O5(OH)4 in the hierarchical pore ZSM-5 molecular sieve as an inner core, and the inner core is coated with a carbon material hydrophobic layer and a porous SiO2 layer in sequence. In the inner core, the NiCu nanoparticles and the flocculent structure Ni3Si2O5(OH)4 are uniformly dispersed in the pore and surface of the hierarchical pore ZSM-5 molecular sieve. The NiCu nanoparticles are loaded on the hierarchical pore ZSM-5, and after reduction treatment, the surface is coated with a hydrophobic carbon layer and deposited with a porous SiO2 layer. The catalyst is used for the selective hydrogenation reaction of furfural in water phase, and solves the problems of large contact interface resistance between furfural and hydrogen and the catalyst active center in water phase, easy re-adsorption of the target product and excessive hydrogenation, and significantly improves the conversion rate of furfural and the selectivity of the target product.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, and specifically discloses a furfural aqueous phase hydrogenation multilayer core-shell structure catalyst and its preparation method. Background Technology

[0002] Although continuous gas-phase reactions are superior to batch liquid-phase reactions to some extent, furfural is obtained by the catalytic hydrolysis of xylitol, and the gas-phase reaction requires a large amount of energy to vaporize the furfural solution. Liquid-phase catalytic hydrogenation of furfural offers milder conditions and is more conducive to integration with upstream products. Therefore, methods for liquid-phase catalytic hydrogenation of furfural using noble metal and non-noble metal catalysts have been explored. Noble metals such as palladium, ruthenium, and platinum exhibit high inherent hydrogenation activity, but their high cost and limited reserves restrict their industrial application. Compared with single non-noble metal catalysts, NiCu alloy nanocatalysts are low-cost and have strong hydrogen activation capabilities. The design and preparation of high-performance, multifunctional NiCu alloy nanocatalysts remain an urgent need to improve their overall reaction performance.

[0003] Heterogeneous catalysis is a catalytic process that occurs at the interface between two phases. Enlarging the catalytic reaction interface and controlling the adsorption and activation of reactants on the catalyst surface are key to improving reaction efficiency. The surface hydrophobicity of heterogeneous catalysts deserves more attention in enriching their catalytic activity. To improve the hydrogenation efficiency of furfural in the aqueous phase, controlling the adsorption and desorption of reactants and products on the catalyst surface and expanding the gas-liquid-solid reaction interface is undoubtedly a highly effective method. Recently, hydrophobic modification of the catalyst surface has achieved good results in improving catalytic efficiency. However, single hydrophobic catalysts tend to aggregate in water, which undoubtedly reduces the active sites for the catalytic hydrogenation of furfural. Summary of the Invention

[0004] One objective of this invention is to address the problems of low solubility of furfural and hydrogen in water, long residence time of hydrophilic products on the catalyst surface, low product selectivity, and easy aggregation of a single hydrophobic layer on the catalyst surface in water, by providing a multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural. This catalyst can increase the adsorption of the reaction substrate, accelerate the reaction rate, improve the reaction selectivity, and also promote the dispersion of catalyst particles in aqueous reaction conditions, thereby improving catalytic activity.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a multilayer core-shell structure catalyst for the aqueous hydrogenation of furfural, wherein the catalyst is a multilayer core-shell structure sphere, denoted as (NiCu-NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2; the sphere includes a core, a hydrophobic carbon material layer covering the core, and a porous SiO2 layer covering the hydrophobic carbon material layer.

[0006] The core is a composite structure of NiCu alloy and NiCu-Ni3Si2O5(OH)4 uniformly loaded in a hierarchical ZSM-5 molecular sieve. The NiCu alloy exists in the form of nanoparticles with a particle size of 3-15 nm, and the NiCu-Ni3Si2O5(OH)4 is a flocculent structure. The NiCu alloy nanoparticles and the flocculent NiCu-Ni3Si2O5(OH)4 are uniformly dispersed in the channels and surface of the hierarchical ZSM-5 molecular sieve.

[0007] Further improvements to the multilayer core-shell structure catalyst for furfural aqueous hydrogenation:

[0008] Preferably, the thickness of the porous SiO2 layer is 5 to 30 nm, and the pore size on the porous SiO2 layer is 1 to 6 nm.

[0009] Preferably, based on the total mass of the catalyst, the mass fraction of each component is as follows:

[0010] NiCu alloy: 5 ~ 20 wt%

[0011] Ni3Si2O5(OH)4: 5 ~ 10 wt%

[0012] ZSM-5 molecular sieve: 30 ~ 50 wt%

[0013] Hydrophobic layer: 1 ~ 10 wt%

[0014] SiO2 layer: 10 ~ 30 wt%.

[0015] A second objective of this invention is to provide a method for preparing the furfural aqueous hydrogenation multilayer core-shell structure catalyst described in any one of the above claims, comprising the following steps:

[0016] S1. Tetraethyl orthosilicate, deionized water, tetrapropylammonium hydroxide and ethylenediamine are mixed evenly, and then aluminum nitrate, sodium bicarbonate, sodium carbonate and sodium hydroxide are added and mixed evenly to form mixture 1; mixture 1 is placed in a hydrothermal reactor for reaction, and the product hierarchical porous ZSM-5 is washed and dispersed in deionized water to form a hierarchical porous ZSM-5 suspension.

[0017] S2. Add soluble nickel salt and soluble copper salt to a mixed solution of ammonium acetate, ammonia, and deionized water to form a solution containing [Ni(NH3)6]. 2+ and [Cu(NH3)4] 2+ A transparent solution;

[0018] S3. Mix the hierarchical porous ZSM-5 suspension from step S1 with the transparent solution from step S2 to form a mixture 2. Place the mixture 2 in a hydrothermal reactor for reaction. The product is washed, dried, calcined, and reduced to obtain NiCu-Ni3Si2O5(OH)4 / ZSM-5.

[0019] S4. NiCu-Ni3Si2O5(OH)4 / ZSM-5 was dispersed in a toluene solution containing a silane coupling agent. After stirring, washing and drying, a (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure was obtained.

[0020] S5. Mix (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure with polyvinylpyrrolidone and anhydrous ethanol until homogeneous. Add a mixed solution of deionized water and ammonia water, and add tetrabutylammonium bromide and tetraethyl orthosilicate while stirring. Mix until homogeneous to form mixture 3. Place mixture 3 in a hydrothermal reactor for reaction. After centrifugation, washing and drying, the product is obtained as a furfural aqueous phase hydrogenation multilayer core-shell structure catalyst, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2.

[0021] Further improvements were made to the preparation method of the multilayer core-shell structure catalyst for the aqueous hydrogenation of furfural:

[0022] Preferably, in step S1, the mass ratio of tetraethyl orthosilicate, deionized water, tetrapropylammonium hydroxide, ethylenediamine, aluminum nitrate, sodium bicarbonate, sodium carbonate, and sodium hydroxide is 1:(1~8):(0.1~0.5):(0.1~0.5):(0.01~0.05):(0.03~0.5):(0.03~0.5):(0.03~0.6); the mixture 1 is subjected to hydrothermal reaction at 120~220℃ for 20~48 h; and the mass ratio of hierarchical ZSM-5 dispersed in deionized water is 1:(5~80).

[0023] Preferably, in the transparent solution of step S2, the concentration of soluble nickel salt is 0.5-6 wt%, the concentration of soluble copper salt is 0.5-6 wt%, the concentration of ammonium acetate is 3-12 wt%, and the pH value of the transparent solution is 9-12.

[0024] Preferably, in step S3, the mass ratio of the multi-level porous ZSM-5 suspension to the transparent solution is 1:(0.5~4); the mixture 2 is subjected to hydrothermal reaction at 100~200 ℃ for 3~10 h; the product is dried at 50~120 ℃ for 10~48 h; the calcination conditions are calcination at 300~600 ℃ for 2~6 h; the reduction conditions are reduction at 300~600 ℃ for 1~5 h, and the reduction atmosphere is hydrogen or a mixture of hydrogen and nitrogen.

[0025] Preferably, in step S4, the mass ratio of NiCu-Ni3Si2O5(OH)4 / ZSM-5, silane coupling agent and toluene is 1:(0.5~5):(30~180); the stirring conditions are stirring at 350~600 rpm at room temperature for 3~8h; and the drying conditions are drying at 30~60℃ for 8~12h.

[0026] Preferably, the silane coupling agent is selected from one or more combinations of methyltrimethoxysilane, ethyltrimethoxysilane, octyltrimethoxysilane, aminopropyltriethoxysilane, vinyltriethoxysilane, isobutyltriethoxysilane, methyltrichlorosilane, trimethylchlorosilane, and vinyldimethylchlorosilane.

[0027] Preferably, in step S5, the mass ratio of (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C, polyvinylpyrrolidone, anhydrous ethanol, deionized water, 28 wt% ammonia, tetrabutylammonium bromide, and tetraethyl orthosilicate is 1:(0.1~2):(6~45):(6~60):(0.5~9):(0.05~1.2):(0.3~4); the mixture 3 is hydrothermally reacted at 100~180℃ for 8~16 h; the centrifugation conditions are centrifugation at 5000~8000 rpm for 1~5 min; and the drying conditions are drying at 60~120℃ for 4~12 h.

[0028] The advantages of this invention compared to the prior art are as follows:

[0029] (1) This invention provides a multilayer core-shell structure catalyst for the aqueous hydrogenation of furfural. The multilayer structure (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2 catalyst uses porous ZSM as a support, which has a large specific surface area and high dispersion of active components. At the same time, the formation of Ni3Si2O5(OH)4 further enhances the interaction between the metal active components and the support. The hydrophobic layer of the catalyst can effectively enhance the adsorption capacity of the catalyst for furfural and hydrogen, overcome the interfacial resistance of the reaction substrate in contact with the active center of the catalyst in the aqueous phase, and can also promote the rapid desorption of reaction products, reduce the residence time of the target product on the catalyst surface, and prevent the re-adsorption of the target product. The SiO2 layer ensures the good dispersion of catalyst particles in the aqueous reaction conditions. The catalyst can increase the adsorption of reaction substrate, accelerate the reaction rate, improve the reaction selectivity, and promote the dispersion of catalyst particles in the aqueous reaction conditions, thereby improving the catalytic activity. The catalyst preparation method is simple, the raw materials are cheap and readily available, and it is conducive to large-scale production.

[0030] (2) This invention provides a method for preparing a multilayer core-shell structure catalyst for the aqueous hydrogenation of furfural. In the process of synthesizing ZSM-5, the method utilizes ethylenediamine, sodium bicarbonate and sodium carbonate buffer solution to maintain the stability of the reaction pH, and utilizes the solubility of silicon atoms in ZSM-5 under alkaline conditions and the effect of ammonia on Ni 2+ and Cu 2+ The complexing property allows silicon atoms in ZSM-5 to dissolve and form silicate ions, while simultaneously reacting with [Ni(NH3)6]. 2+ and [Cu(NH3)4] 2+ Released Ni 2+ and Cu 2+ The reaction; the presence of ammonia and ammonium acetate buffer solution not only ensures Ni 2+ and Cu 2+ It does not precipitate immediately under alkaline conditions, and also stabilizes the pH of the solution, ensuring Ni 2+ and Cu 2+ Simultaneously precipitated; the surface hydroxyl groups of ZSM-5 react with a silane coupling agent to form a hydrophobic layer; polyvinylpyrrolidone stabilizes (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C, and then tetrabutylammonium bromide is used to directionally hydrolyze tetraethyl orthosilicate in a suspension containing polyvinylpyrrolidone stabilized (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C to form a SiO2 layer. After washing and drying, the multilayer structure catalyst of furfural aqueous selective hydrogenation conversion (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2 is obtained. Attached Figure Description

[0031] Figure 1This is a schematic diagram illustrating the working principle of the furfural aqueous phase hydrogenation multilayer core-shell structure catalyst (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2 of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing a multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural, comprising the following steps:

[0035] S1. Mix 3.9 g tetraethyl orthosilicate, 12 mL deionized water, 0.9 g tetrapropylammonium hydroxide and 1.1 g ethylenediamine evenly, add 0.07 g aluminum nitrate, 0.6 g sodium bicarbonate, 0.6 g sodium carbonate and 0.8 g sodium hydroxide, and mix evenly to form mixture 1; place mixture 1 in a hydrothermal reactor and react at 180 ℃ for 24 h. After washing the product, take 0.9 g and disperse it in 30 mL of water to form a hierarchical porous ZSM-5 suspension.

[0036] S2. Add 1.2 g Ni(NO3)2 and 0.9 g Cu(NO3)2 to a mixed solution of 1.9 g ammonium acetate, 30 mL ammonia water (concentration 28wt%), and 30 mL deionized water to form a solution containing [Ni(NH3)6]. 2+ and [Cu(NH3)4] 2+ A transparent solution with a pH of 10;

[0037] S3. Mix the hierarchical porous ZSM-5 suspension obtained in step S1 with the transparent solution obtained in step S2 to form a mixture 2. Place the mixture 2 in a hydrothermal reactor and react at 160 °C for 6 h. The product is washed, dried at 80 °C for 12 h, calcined at 500 °C for 2 h, and reduced at 500 °C for 2 h to obtain NiCu-Ni3Si2O5(OH)4 / ZSM-5.

[0038] S4. Disperse 1 g of NiCu-Ni3Si2O5(OH)4 / ZSM-5 obtained in step S3 in 100 mL of toluene solution containing 2.5 mL of octyltrimethoxysilane. Stir at 400 rpm for 4 h, wash, and dry at 50 °C for 10 h to obtain (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure.

[0039] S5. 1 g of the (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure obtained in step S4 was mixed evenly with 0.7 g of polyvinylpyrrolidone and 30 mL of anhydrous ethanol. Then, a mixed solution of 30 mL of deionized water and 3 mL of ammonia (concentration 28 wt%) was added. During stirring, 0.3 g of tetrabutylammonium bromide and 2.6 g of tetraethyl orthosilicate were added and mixed evenly to form mixture 3. Mixture 3 was placed in a hydrothermal reactor and reacted at 120 ℃ for 10 h. The product was centrifuged at 6000 rpm for 2 min, washed, and dried at 120 ℃ for 10 h to obtain a furfural aqueous phase hydrogenation multilayer core-shell structure catalyst, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2.

[0040] The furfural aqueous hydrogenation multilayer core-shell structure catalyst prepared in this embodiment was used for the selective catalytic hydrogenation of furfural in the aqueous phase to prepare furfuryl alcohol. The specific reaction conditions and activity test results are as follows: The furfural aqueous hydrogenation multilayer core-shell structure catalyst was placed in a 250 mL high-pressure reactor for evaluation of its catalytic hydrogenation activity. The reaction system consisted of 0.6 g catalyst, 1 mL furfural, and 80 mL deionized water. The reaction was carried out at 90 °C, 1.0 MPa hydrogen pressure, and 950 rpm stirring speed for 6 h. After the reaction, the mixture was centrifuged, and the reaction product was collected. The product was detected by gas chromatography, and the furfural conversion rate was found to be 97.6%, the furfuryl alcohol selectivity was 90.7%, and the yield was 88.5%.

[0041] Figure 1This is a schematic diagram illustrating the working principle of the furfural aqueous hydrogenation multilayer core-shell structure catalyst (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2 of the present invention. Due to the low solubility of furfural and hydrogen in the aqueous phase, and the lower the product's selectivity as the residence time on the catalyst surface increases, hydrophobic modification of the catalyst surface is necessary to effectively increase the adsorption of furfural and hydrogen on the catalyst surface and the rapid desorption of the product. This hydrophobic layer effectively increases the adsorption of furfural and hydrogen, reduces the product's residence time on the catalyst surface, prevents product re-adsorption, inhibits excessive hydrogenation, and improves the yield of the target product. However, a single hydrophobic catalyst surface tends to aggregate in water, which undoubtedly reduces the active sites for furfural hydrogenation. The hydrolysis of tetraethyl silicate readily forms a SiO2 protective layer. This hydrophilic outer shell ensures good dispersion of the solid catalyst in the aqueous phase, while the hydrophobic core enhances the catalyst's adsorption capacity for the organic substrate furfural and hydrogen, effectively overcoming the interfacial resistance between the organic substrate and the catalyst's active site in the aqueous phase. It also promotes rapid desorption of reaction products, preventing further hydrogenation. The increased reaction interface, enhanced substrate effect, and rapid product desorption caused by the hydrophobic core and hydrophilic shell improve both the efficiency and product selectivity of furfural aqueous hydrogenation.

[0042] Example 2

[0043] This embodiment provides a method for preparing a multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural, comprising the following steps:

[0044] S1. Mix 2.7 g tetraethyl orthosilicate, 20 mL deionized water, 0.3 g tetrapropylammonium hydroxide and 0.4 g ethylenediamine evenly, add 0.03 g aluminum nitrate, 0.9 g sodium bicarbonate, 0.6 g sodium carbonate and 0.1 g sodium hydroxide, and mix evenly to form mixture 1; place mixture 1 in a hydrothermal reactor and react at 120 ℃ for 48 h. After washing the product, take 0.8 g and disperse it in 15 mL of water to form a hierarchical porous ZSM-5 suspension.

[0045] S2. Mix 1.9 g Ni(NO3)2 and 2.3 g Cu(NO3)2. 2加入 In a mixed solution of 4.3 g ammonium acetate, 35 mL ammonia solution (28 wt%), and 16 mL deionized water, a solution containing [Ni(NH3)6] is formed. 2+ and [Cu(NH3)4] 2+ A transparent solution with a pH of 11;

[0046] S3. Mix the hierarchical porous ZSM-5 suspension obtained in step S1 with the transparent solution obtained in step S2 to form a mixture 2. Place the mixture 2 in a hydrothermal reactor and react at 120 °C for 9 h. The product is washed, dried at 120 °C for 10 h, calcined at 400 °C for 3 h, and reduced at 350 °C for 4 h to obtain NiCu-Ni3Si2O5(OH)4 / ZSM-5.

[0047] S4. Disperse 1 g of NiCu-Ni3Si2O5(OH)4 / ZSM-5 obtained in step (3) in 70 mL of toluene solution containing 3.3 mL of isobutyltriethoxysilane. Stir at 350 rpm for 8 h, wash, and dry at 30 ℃ for 12 h to obtain (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure;

[0048] S5. Mix 1 g of the (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure obtained in step (4) with 0.3 g of polyvinylpyrrolidone and 20 mL of anhydrous ethanol. Then add a mixed solution of 43 mL of deionized water and 6 mL of ammonia (concentration 28 wt%). During stirring, add 0.7 g of tetrabutylammonium bromide and 1.6 g of tetraethyl orthosilicate and mix well to form a mixed solution 3. Place the mixed solution 3 in a hydrothermal reactor and react at 100 ℃ for 16 h. Centrifuge the product at 5000 rpm for 5 min, wash, and dry at 70 ℃ for 12 h to obtain a furfural aqueous phase hydrogenation multilayer core-shell structure catalyst, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2.

[0049] The multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural prepared in this embodiment was used for the selective catalytic hydrogenation of furfural in the aqueous phase to prepare cyclopentanone. The specific reaction conditions and activity test results are as follows:

[0050] A multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural was placed in a 250 mL high-pressure reactor to evaluate its catalytic hydrogenation activity. The reaction system consisted of 0.9 g catalyst, 0.8 mL furfural, and 70 mL deionized water. The reaction was carried out at 160 °C, 2.0 MPa hydrogen pressure, and 800 rpm for 9 h. After the reaction, the mixture was centrifuged, and the product was analyzed by gas chromatography. The furfural conversion rate was found to be 99.1%, the selectivity for cyclopentanone was 96.3%, and the yield was 95.4%.

[0051] Example 3

[0052] This embodiment provides a method for preparing a multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural, comprising the following steps:

[0053] S1. Mix 5.2 g tetraethyl orthosilicate, 41 mL deionized water, 2.3 g tetrapropylammonium hydroxide and 1.9 g ethylenediamine evenly, add 0.2 g aluminum nitrate, 1.5 g sodium bicarbonate, 1.3 g sodium carbonate and 0.7 g sodium hydroxide, and mix evenly to form mixture 1; place mixture 1 in a hydrothermal reactor and react at 200 ℃ for 20 h. After washing the product, take 1.6 g and disperse it in 90 mL of water to form a hierarchical porous ZSM-5 suspension.

[0054] S2. Mix 0.7 g Ni(NO3)2 and 2.8 g Cu(NO3). 2加入 A mixed solution containing 7 g ammonium acetate, 24 mL ammonia solution (28 wt%), and 34 mL deionized water forms a solution containing [Ni(NH3)6]. 2+ and [Cu(NH3)4] 2+ A transparent solution with a pH of 9;

[0055] S3. Mix the hierarchical porous ZSM-5 suspension obtained in step S1 with the transparent solution obtained in step S2 to form a mixture 2. Place the mixture 2 in a hydrothermal reactor and react at 200 °C for 3 h. The product is washed, dried at 100 °C for 24 h, calcined at 600 °C for 3 h, and reduced at 400 °C for 3 h to obtain NiCu-Ni3Si2O5(OH)4 / ZSM-5.

[0056] S4. 1.8 g of NiCu-Ni3Si2O5(OH)4 / ZSM-5 obtained in step S3 was dispersed in 120 mL of toluene solution containing 4.1 mL of aminopropyltriethoxysilane. After stirring at 600 rpm for 3 h, the mixture was washed and dried at 60 °C for 8 h to obtain (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure.

[0057] S5. 1.8 g of the (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure obtained in step S4 was mixed evenly with 0.4 g of polyvinylpyrrolidone and 22 mL of anhydrous ethanol. Then, a mixed solution of 52 mL of deionized water and 6 mL of ammonia (concentration 28 wt%) was added. During stirring, 0.6 g of tetrabutylammonium bromide and 1.5 g of tetraethyl orthosilicate were added and mixed evenly to form mixture 3. Mixture 3 was placed in a hydrothermal reactor and reacted at 180 ℃ for 8 h. The product was centrifuged at 8000 rpm for 1 min, washed, and dried at 110 ℃ for 11 h to obtain a furfural aqueous phase hydrogenation multilayer core-shell structure catalyst, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2.

[0058] The multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural prepared in this embodiment was used for the selective catalytic hydrogenation of furfural in the aqueous phase to prepare tetrahydrofurfuryl alcohol. The specific reaction conditions and activity test results are as follows:

[0059] A multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural was placed in a 250 mL high-pressure reactor to evaluate its catalytic hydrogenation activity. The reaction system consisted of 1.2 g catalyst, 1.5 mL furfural, and 90 mL deionized water. The reaction was carried out at 120 °C, 1.5 MPa hydrogen pressure, and 1000 rpm for 5 h. After the reaction, the mixture was centrifuged, and the product was analyzed by gas chromatography. The furfural conversion rate was found to be 96.1%, the selectivity for tetrahydrofurfuryl alcohol was 87.9%, and the yield was 84.4%.

[0060] Example 4

[0061] This embodiment provides a method for preparing a multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural, comprising the following steps:

[0062] S1. Mix 1.9 g tetraethyl orthosilicate, 13.3 mL deionized water, 0.6 g tetrapropylammonium hydroxide and 0.2 g ethylenediamine evenly, add 0.04 g aluminum nitrate, 0.7 g sodium bicarbonate, 0.7 g sodium carbonate and 0.7 g sodium hydroxide, and mix evenly to form mixture 1; place mixture 1 in a hydrothermal reactor and react at 160 ℃ for 30 h. After washing the product, take 0.6 g and disperse it in 40 mL of water to form a hierarchical porous ZSM-5 suspension.

[0063] S2. Mix 3.1 g Ni(NO3)2 and 0.6 g Cu(NO3)2. 2加入 In a mixed solution of 4.2 g ammonium acetate, 41 mL ammonia solution (28 wt%), and 17 mL deionized water, a solution containing [Ni(NH3)6] is formed. 2+ and [Cu(NH3)4] 2+ A transparent solution with a pH of 12;

[0064] S3. Mix the hierarchical porous ZSM-5 suspension obtained in step S1 with the transparent solution obtained in step S2 to form a mixture 2. Place the mixture 2 in a hydrothermal reactor and react at 120 °C for 10 h. The product is washed, dried at 50 °C for 48 h, calcined at 570 °C for 4 h, and reduced at 600 °C for 1 h to obtain NiCu-Ni3Si2O5(OH)4 / ZSM-5.

[0065] S4. Disperse 0.7 g of NiCu-Ni3Si2O5(OH)4 / ZSM-5 obtained in step S3 in 90 mL of toluene solution containing 1.0 mL of methyltrichlorosilane. Stir at 500 rpm for 5 h, wash, and dry at 40 ℃ for 11 h to obtain (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure.

[0066] S5. Mix 0.7 g of the (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure obtained in step S4 with 1.2 g of polyvinylpyrrolidone and 25 mL of anhydrous ethanol. Then add a mixed solution of 35 mL of deionized water and 5 mL of ammonia (concentration 28 wt%). During stirring, add 0.7 g of tetrabutylammonium bromide and 2.1 g of tetraethyl orthosilicate and mix well to form mixture 3. Place mixture 3 in a hydrothermal reactor and react at 130 ℃ for 13 h. Centrifuge the product at 7000 rpm for 3 min, wash, and dry at 100 ℃ for 9 h to obtain a furfural aqueous hydrogenation multilayer core-shell structure catalyst, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2.

[0067] The multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural prepared in this embodiment was used for the selective catalytic hydrogenation of furfural in the aqueous phase to prepare cyclopentanone. The specific reaction conditions and activity test results are as follows:

[0068] A multilayer core-shell structured catalyst for the aqueous hydrogenation of furfural was placed in a 250 mL high-pressure reactor to evaluate its catalytic hydrogenation activity. The reaction system consisted of 0.3 g catalyst, 0.5 mL furfural, and 60 mL deionized water. The reaction was carried out at 140 °C, 2.0 MPa hydrogen pressure, and 1200 rpm stirring speed for 7 h. After the reaction, the mixture was centrifuged, and the product was analyzed by gas chromatography. The furfural conversion rate was found to be 99.7%, the cyclopentanone selectivity was 93.2%, and the yield was 92.9%.

[0069] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A multilayer core-shell structure catalyst for the aqueous hydrogenation of furfural, characterized in that, The catalyst is a multi-layered core-shell structured sphere, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2; the sphere includes a core, a hydrophobic carbon material layer covering the core, and a porous SiO2 layer covering the hydrophobic carbon material layer. The core is a composite structure in which NiCu alloy and Ni3Si2O5(OH)4 are uniformly loaded in a hierarchical ZSM-5 molecular sieve. The NiCu alloy exists in the form of nanoparticles with a particle size of 3-15 nm, and the Ni3Si2O5(OH)4 has a flocculent structure. The NiCu alloy nanoparticles and flocculent Ni3Si2O5(OH)4 are uniformly dispersed in the channels and surface of the hierarchical ZSM-5 molecular sieve. The catalyst was obtained through the following preparation steps: S1. Tetraethyl orthosilicate, deionized water, tetrapropylammonium hydroxide and ethylenediamine are mixed evenly, and then aluminum nitrate, sodium bicarbonate, sodium carbonate and sodium hydroxide are added and mixed evenly to form mixture 1; mixture 1 is placed in a hydrothermal reactor for reaction, and the product hierarchical porous ZSM-5 is washed and dispersed in deionized water to form a hierarchical porous ZSM-5 suspension. S2. Add soluble nickel salt and soluble copper salt to a mixed solution of ammonium acetate, ammonia, and deionized water to form a solution containing [Ni(NH3)6]. 2+ and [Cu(NH3)4] 2+ A transparent solution; S3. Mix the hierarchical porous ZSM-5 suspension from step S1 with the transparent solution from step S2 to form a mixture 2. Place the mixture 2 in a hydrothermal reactor for reaction. The product is washed, dried, calcined, and reduced to obtain NiCu-Ni3Si2O5(OH)4 / ZSM-5. S4. NiCu-Ni3Si2O5(OH)4 / ZSM-5 was dispersed in a toluene solution containing a silane coupling agent. After stirring, washing and drying, a (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure was obtained. S5. Mix (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C core-shell structure with polyvinylpyrrolidone and anhydrous ethanol until homogeneous. Add a mixed solution of deionized water and ammonia water, and add tetrabutylammonium bromide and tetraethyl orthosilicate while stirring. Mix until homogeneous to form mixture 3. Place mixture 3 in a hydrothermal reactor for reaction. After centrifugation, washing and drying, the product is obtained as a furfural aqueous phase hydrogenation multilayer core-shell structure catalyst, denoted as (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C@SiO2.

2. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1, characterized in that, The thickness of the porous SiO2 layer is 5 ~ 30 nm, and the pore size on the porous SiO2 layer is 1 ~ 6 nm.

3. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1 or 2, characterized in that, Based on the total mass of the catalyst, the mass fraction of each component is as follows: NiCu alloy: 5 ~ 20 wt% Ni3Si2O5(OH)4: 5 ~ 10 wt% ZSM-5 molecular sieve: 30 ~ 50 wt% Hydrophobic layer: 1 ~ 10 wt% SiO2 layer: 10 ~ 30 wt%.

4. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1, characterized in that, In step S1, the mass ratio of tetraethyl orthosilicate, deionized water, tetrapropylammonium hydroxide, ethylenediamine, aluminum nitrate, sodium bicarbonate, sodium carbonate, and sodium hydroxide is 1:(1~8):(0.1~0.5):(0.1~0.5):(0.01~0.05):(0.03~0.5):(0.03~0.5):(0.03~0.6); the mixture 1 is subjected to hydrothermal reaction at 120~220 °C for 20~48 h; the mass ratio of hierarchical ZSM-5 dispersed in deionized water is 1:(5~80).

5. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1, characterized in that, In the transparent solution of step S2, the concentration of soluble nickel salt is 0.5-6 wt%, the concentration of soluble copper salt is 0.5-6 wt%, the concentration of ammonium acetate is 3-12 wt%, and the pH value of the transparent solution is 9-12.

6. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1, characterized in that, In step S3, the mass ratio of the multi-level porous ZSM-5 suspension to the transparent solution is 1:(0.5~4); the mixture 2 is subjected to hydrothermal reaction at 100~200℃ for 3~10 h; the product is dried at 50~120℃ for 10~48 h; the calcination conditions are calcination at 300~600℃ for 2~6 h; the reduction conditions are reduction at 300~600℃ for 1~5 h, and the reduction atmosphere is hydrogen or a mixture of hydrogen and nitrogen.

7. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1, characterized in that, In step S4, the mass ratio of NiCu-Ni3Si2O5(OH)4 / ZSM-5, silane coupling agent and toluene is 1:(0.5~5):(30~180); the stirring conditions are stirring at 350~600 rpm at room temperature for 3~8 h; and the drying conditions are drying at 30~60 ℃ for 8~12 h.

8. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1 or 7, characterized in that, The silane coupling agent is selected from one or more combinations of methyltrimethoxysilane, ethyltrimethoxysilane, octyltrimethoxysilane, aminopropyltriethoxysilane, vinyltriethoxysilane, isobutyltriethoxysilane, methyltrichlorosilane, trimethylchlorosilane, and vinyldimethylchlorosilane.

9. The furfural aqueous hydrogenation multilayer core-shell structure catalyst according to claim 1, characterized in that, In step S5, the mass ratio of (NiCu-Ni3Si2O5(OH)4 / ZSM-5)@C, polyvinylpyrrolidone, anhydrous ethanol, deionized water, 28 wt% ammonia, tetrabutylammonium bromide, and tetraethyl orthosilicate is 1 : (0.1 ~ 2) : (6 ~ 45) : (6 ~ 60) : (0.5 ~ 9) : (0.05 ~ 1.2) : (0.3 ~ 4); the mixture 3 is hydrothermally reacted at 100 ~ 180 ℃ for 8 ~ 16 h; the centrifugation conditions are centrifugation at 5000 ~ 8000 rpm for 1 ~ 5 min; and the drying conditions are drying at 60 ~ 120 ℃ for 4 ~ 12 h.

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