Furfural water phase hydro-conversion hollow structure catalyst and preparation method thereof

Abstract

The invention belongs to the technical field of catalytic materials, and particularly relates to a hollow-structure catalyst for furfural water-phase hydro-conversion and a preparation method of the hollow-structure catalyst. According to the catalyst, hollow structure SiO2 (C) with a hydrophobic carbon layer in an inner cavity is used as a carrier, and at least one of active metal components Cu, Ni and Co is preferentially loaded on the outer surface of the carrier. The structure creates unique distribution of internal hydrophobic and external enrichment active sites, and cooperates with enrichment and confinement effects of the hollow structure on reactants to construct an efficient micro-reaction environment. When the catalyst is applied to a furfural water phase hydrogenation reaction, the hydrophobic carbon layer in the inner cavity can effectively enrich hydrogen, and the active metal on the outer surface is beneficial to activation and contact of furfural molecules, so that the catalytic efficiency and selectivity are remarkably improved. The catalyst can convert furfural into high-added-value products such as furfuryl alcohol, tetrahydrofurfuryl alcohol and cyclopentanone with high activity and high selectivity, and shows excellent catalytic stability.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a hollow structure catalyst for the aqueous hydrogenation conversion of furfural and its preparation method. Background Technology

[0002] Water, as an abundant natural green solvent on Earth, participates in most biomass conversion processes. Furthermore, furfural is obtained through the catalytic hydrolysis of xylitol, and using water as a solvent for furfural hydrogenation allows for seamless integration with upstream products, avoiding costly dehydration pretreatment. Therefore, theoretically, the selective hydrogenation of furfural in an aqueous phase has industrial application potential, making it a significant reaction medium. However, the low solubility of hydrogen in water results in significant mass transfer resistance, severely reducing the efficiency of the aqueous phase reaction.

[0003] Hollow SiO2, with its internal cavity, large specific surface area and pore volume, easy surface modification, and good biocompatibility, has attracted widespread attention and research in adsorption, catalysis, and microreactors. By appropriately adjusting the microenvironment of hollow SiO2, substrate molecule aggregation can be achieved. Through targeted design of the interaction between hollow SiO2 nanostructures and metal nanoparticles, multifunctional catalytic materials can be created, serving the sustainable development of biomass green energy. Summary of the Invention

[0004] One of the objectives of this invention is to address the problems of low hydrogen solubility in water, hydrophobic modification of catalyst surfaces hindering furfural activation in the aqueous phase, and easy leaching of active components from conventional supported catalysts in aqueous environments leading to catalyst deactivation. This invention provides a hollow structure catalyst for the aqueous hydrogenation conversion of furfural, which can convert furfural into high-value-added products such as furfuryl alcohol, tetrahydrofurfuryl alcohol, and cyclopentanone with high activity and selectivity, and exhibits excellent catalytic stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a hollow structure catalyst for the aqueous hydrogenation conversion of furfural, the catalyst comprising a hollow SiO2 support, wherein the inner surface of the SiO2 support is modified with a hydrophobic carbon layer formed by chemical bonding of a silane coupling agent, and the outer surface of the SiO2 support is loaded with active metal particles; wherein the SiO2 support accounts for 70-90 wt% of the total mass of the catalyst, the active metal particles account for 5-25 wt% of the total mass of the catalyst, and the hydrophobic carbon layer accounts for 1-7 wt% of the total mass of the catalyst.

[0006] Further improvements to the hollow structure catalyst for the aqueous hydrogenation conversion of furfural: Preferably, the shell thickness of the hollow SiO2 support is 20 ~ 100 nm.

[0007] Preferably, the active metal particles have a particle size of 2 to 12 nm and are composed of one or more of Cu, Ni, and Co.

[0008] A second objective of this invention is to provide a method for preparing the above-mentioned hollow structure catalyst for the aqueous hydrogenation conversion of furfural, comprising the following steps: S1. Under vigorous stirring, the toluene solution containing the silane coupling agent is rapidly mixed with water and processed using a high-speed shear emulsifier to obtain an emulsion; S2. Add sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, and 28 wt% ammonia water to the above emulsion, then add anhydrous ethanol and tetraethyl orthosilicate. Stir the reaction under constant temperature conditions. After washing, the reaction product is dispersed in the aqueous phase to obtain hollow Si with a hydrophobic carbon layer in the inner cavity. Suspension, denoted as hollow Si (C) Suspension; S3. Add a mixed solution of metal M salt, water, and 28 wt% ammonia solution to the hollow Si. (C) After being thoroughly mixed in a suspension, a hydrothermal reaction is carried out. The reaction product is then washed, dried, calcined, and reduced to obtain the furfural aqueous phase hydrogenation conversion hollow structure catalyst M / Si. (C).

[0009] Further improvements to the preparation method of hollow structure catalysts for the aqueous hydrogenation conversion of furfural: Preferably, the silane coupling agent comprises one or more combinations of methyltrimethoxysilane, ethyltrimethoxysilane, octyltrimethoxysilane, aminopropyltriethoxysilane, vinyltriethoxysilane, isobutyltriethoxysilane, methyltrichlorosilane, trimethylchlorosilane, and vinyldimethylchlorosilane.

[0010] Preferably, in step S1, the concentration of the silane coupling agent in the toluene solution containing the silane coupling agent is 0.5~2.5 wt%; the toluene solution containing the silane coupling agent is mixed with water at a mass ratio of 1:(2~7); the speed of the high-speed shear emulsifier is 5000~15000 rpm, and the processing time is 2~5 min.

[0011] Preferably, in step S2, the mass ratio of sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, 28 wt% ammonia, anhydrous ethanol, tetraethyl orthosilicate, and the emulsion obtained in step S1 is 1:(6~12):(6~12):(60~120):(8~30):(600~1500); the stirring speed is 300~800 rpm, and the reaction time is 1~8 h; the washed reaction product is dispersed in deionized water at a mass ratio of 1:(10~40) to obtain hollow Si (C) Suspension.

[0012] Preferably, in step S3, the mixed solution and the hollow Si (C) The mass ratio of the suspension is (0.3 ~ 3):1; in the mixed solution, the mass ratio of metal M salt, water and 28 wt% ammonia water is 1:(10 ~ 30):(10 ~ 30).

[0013] Preferably, in step S3, the hydrothermal reaction temperature is 120 ~ 200 ℃ and the reaction time is 4 ~ 8 h; the drying temperature is 60 ~ 100 ℃ and the time is 10 ~ 20 h; the calcination temperature is 400 ~ 600 ℃ and the time is 2 ~ 5 h.

[0014] Preferably, in step S3, the reduction treatment is carried out in a mixed atmosphere of nitrogen and hydrogen, the reduction temperature is 300~600 ℃, and the reduction time is 1~4 h, wherein the volume ratio of hydrogen to nitrogen in the mixed atmosphere is 1:(0.1~10).

[0015] The advantages of this invention compared to the prior art are as follows: (1) This invention provides a hollow structure catalyst for the aqueous hydrogenation conversion of furfural. The catalyst uses hollow SiO2(C) as a support, with a hydrophobic carbon layer formed by chemical bonding of a silane coupling agent on the inner surface of the support, and active metal particles loaded on the outer surface of the support. This design achieves an active site distribution pattern of "internal hydrophobicity and external enrichment". The hollow structure can enrich and confine reactant molecules, and the hydrophobic carbon layer in the inner cavity preferentially enriches hydrogen, increasing the local concentration. At the same time, the active sites located on the outer surface efficiently activate furfural molecules. The two work together to construct a highly efficient micro-reaction environment, which greatly improves the catalytic efficiency. In the aqueous hydrogenation reaction of furfural, this catalyst can generate high-value-added products such as furfuryl alcohol, tetrahydrofurfuryl alcohol, and cyclopentanone with high activity and high selectivity, and exhibits excellent catalytic stability.

[0016] (2) The present invention provides a method for preparing a hollow structure catalyst for the aqueous hydrogenation conversion of furfural. The method firstly forms an O / W type emulsion with a toluene solution containing a silane coupling agent and an aqueous phase. Sodium dodecylbenzenesulfonate and polyvinylpyrrolidone are used to directionally hydrolyze tetraethyl orthosilicate at the O / W type emulsion interface to form a hollow structure SiO2. At the same time, the silane coupling agent in the toluene solution containing the silane coupling agent inside the emulsion is used to hydrophobically modify the interior of the hollow structure SiO2 to form SiO2(C) with a hydrophobic carbon layer in the cavity. The solubility of silicon atoms in SiO2(C) under alkaline conditions and the complexing properties of ammonia water on Ni, Cu, and Co are used to dissolve silicon atoms to form silicate ions and react with metal ions released by the ammonia complex. After drying, calcination, and reduction, the hollow structure catalyst for the aqueous hydrogenation conversion of furfural is obtained. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the working principle of the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to the present invention. Detailed Implementation

[0018] 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.

[0019] Example 1

[0020] This embodiment provides a method for preparing a hollow structure catalyst for the aqueous hydrogenation conversion of furfural, comprising the following steps: S1. Take 30 ml of toluene solution containing 0.5 g of silane coupling agent, mix it with 100 mL of water under vigorous stirring, and process it with a high-speed shear emulsifier at 5000 rpm for 5 min to obtain an emulsion; S2. Add 0.1 g sodium dodecylbenzenesulfonate, 0.6 g polyvinylpyrrolidone, and 1 mL ammonia (28 wt%) to the above emulsion. While stirring, add a mixed solution of 8 mL anhydrous ethanol and 2 mL tetraethyl orthosilicate. React at a constant temperature for 7 h under stirring at 400 rpm. After washing, take 0.5 g of the product and disperse it in 15 mL of aqueous phase to obtain hollow Si with a hydrophobic carbon layer inside. Suspension, denoted as hollow Si (C) Suspension; S3. Take 0.5 g Ni(NO3)2·6H2O, 5 mL water and 12 mL ammonia (concentration 28 wt%) mixed solution, add to the above hollow SiO2(C) suspension, mix evenly, place in a hydrothermal reactor and react at 150 ℃ for 6 h. The product is washed, dried at 80 ℃ for 12 h, calcined at 500 ℃ for 4 h, and reduced at 400 ℃ for 2 h. The reducing atmosphere is a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:1 to obtain Ni / SiO2(C).

[0021] Catalytic performance test: The hollow-structure catalyst for the aqueous hydrogenation conversion of furfural prepared in this embodiment was used to prepare tetrahydrofurfuryl alcohol from furfural in the aqueous phase. The specific reaction conditions and activity test results are as follows: The selective hydrogenation conversion catalyst of furfural was placed in a 250 mL high-pressure reactor to evaluate the catalytic hydrogenation activity of furfural. The reaction system consisted of 0.5 g catalyst, 12 mmol furfural, and 60 mL deionized water. The reaction was carried out at 120 °C, 1.0 MPa hydrogen pressure, and 1000 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 98.4%, the selectivity of tetrahydrofurfuryl alcohol was 98.7%, and the yield was 97.1%.

[0022] Example 2

[0023] This embodiment provides a method for preparing a hollow structure catalyst for the aqueous hydrogenation conversion of furfural, comprising the following steps: S1. Take 50 mL of toluene solution containing 0.8 g of silane coupling agent, mix it with 150 mL of water under vigorous stirring, and process it with a high-speed shear emulsifier at 10000 rpm for 3 min to obtain an emulsion; S2. Add 0.2 g sodium dodecylbenzenesulfonate, 1.7 g polyvinylpyrrolidone, and 2.2 mL ammonia (28 wt%) to the above emulsion. While stirring, add a mixed solution of 19 mL anhydrous ethanol and 2.7 mL tetraethyl orthosilicate. React at a constant temperature for 8 h with stirring at 300 rpm. After washing, take 0.7 g of the product and disperse it in 20 mL of aqueous phase to obtain hollow Si with a hydrophobic carbon layer inside. Suspension, denoted as hollow Si (C) Suspension; S3. Take a mixed solution of 0.3 g Ni(NO3)2·6H2O, 0.5 g Cu(NO3)2·3H2O, 13 mL water and 15 mL ammonia (concentration 28 wt%), add it to the above hollow SiO2(C) suspension, mix well, and place it in a hydrothermal reactor to react at 120 ℃ for 8 h. The product is washed, dried at 60 ℃ for 20 h, calcined at 400 ℃ for 5 h, and reduced at 300 ℃ for 4 h. The reducing atmosphere is a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:1 to obtain NiCu / SiO2(C).

[0024] Catalytic performance test: The hollow-structure catalyst for the aqueous hydrogenation conversion of furfural prepared in this embodiment was used for the aqueous hydrogenation of furfural to prepare furfuryl alcohol. The specific reaction conditions and activity test results are as follows: The furfural selective hydrogenation conversion catalyst was placed in a 250 mL high-pressure reactor for catalytic hydrogenation activity evaluation of furfural. The reaction system consisted of 0.6 g catalyst, 17 mmol furfural, and 70 mL deionized water. The reaction was carried out at 90 °C, 0.7 MPa hydrogen pressure, and 800 rpm stirring speed for 4 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 97.2%, the furfuryl alcohol selectivity was 99.3%, and the yield was 96.5%.

[0025] Example 3

[0026] This embodiment provides a method for preparing a hollow structure catalyst for the aqueous hydrogenation conversion of furfural, comprising the following steps: S1. Take 40 mL of toluene solution containing 0.8 g of silane coupling agent, mix it with 240 mL of water under vigorous stirring, and process it with a high-speed shear emulsifier at 15000 rpm for 2 min to obtain an emulsion; S2. Add 0.4 g sodium dodecylbenzenesulfonate, 3.6 g polyvinylpyrrolidone, and 3.7 mL ammonia (28 wt%) to the above emulsion. While stirring, add a mixed solution of 40 mL anhydrous ethanol and 10 mL tetraethyl orthosilicate. React at 800 rpm for 2 h at a constant temperature. After washing, take 2.8 g of the product and disperse it in 70 mL of aqueous phase to obtain hollow Si with a hydrophobic carbon layer inside. Suspension, denoted as hollow Si (C) Suspension; S3. Take a mixed solution of 0.4 g Cu(NO3)2·3H2O, 0.3 g Co(NO3)2·6H2O, 20 mL water and 16 mL ammonia (concentration 28 wt%), add it to the above hollow SiO2(C) suspension, mix well, and place it in a hydrothermal reactor to react at 180 ℃ for 5 h. The product is washed, dried at 90 ℃ for 16 h, calcined at 550 ℃ for 3 h, and reduced at 450 ℃ for 3 h. The reducing atmosphere is a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:1 to obtain CuCo / SiO2(C).

[0027] Catalytic performance test: The hollow-structure catalyst for the aqueous hydrogenation conversion of furfural prepared in this embodiment was used for the aqueous hydrogenation of furfural to prepare cyclopentanone. The specific reaction conditions and activity test results are as follows: The furfural selective hydrogenation conversion catalyst was placed in a 250 mL high-pressure reactor for catalytic hydrogenation activity evaluation. The reaction system consisted of 0.8 g catalyst, 20 mmol furfural, and 70 mL deionized water. The reaction was carried out at 160 °C, 1.5 MPa hydrogen pressure, and 700 rpm stirring speed for 7 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 98.0%, the cyclopentanone selectivity was 95.8%, and the yield was 93.9%.

[0028] Example 4

[0029] This embodiment provides a method for preparing a hollow structure catalyst for the aqueous hydrogenation conversion of furfural, comprising the following steps: S1. Take 60 mL of toluene solution containing 1.3 g of silane coupling agent, mix it with 300 mL of water under vigorous stirring, and process it with a high-speed shear emulsifier at 13000 rpm for 3 min to obtain an emulsion; S2. Add 0.5 g sodium dodecylbenzenesulfonate, 5.2 g polyvinylpyrrolidone, and 6 mL ammonia (28 wt%) to the above emulsion. While stirring, add a mixed solution of 40 mL anhydrous ethanol and 13 mL tetraethyl orthosilicate. React at a constant temperature for 5 h under stirring at 600 rpm. After washing, take 3.7 g of the product and disperse it in 70 mL of aqueous phase to obtain hollow Si with a hydrophobic carbon layer inside. Suspension, denoted as hollow Si (C) Suspension; S3. Take 1.0 g Cu(NO3)2·3H2O, 27 mL water and 24 mL ammonia (concentration 28 wt%) mixed solution, add to the above hollow SiO2(C) suspension, mix well, place in a hydrothermal reactor and react at 200 ℃ for 4 h. The product is washed, dried at 100 ℃ for 10 h, calcined at 600 ℃ for 2 h, and reduced at 350 ℃ for 3 h. The reducing atmosphere is a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:1 to obtain Cu / SiO2(C).

[0030] Catalytic performance test: The hollow-structure catalyst for the aqueous hydrogenation conversion of furfural prepared in this embodiment was used for the aqueous hydrogenation of furfural to prepare 2-methylfuran. The specific reaction conditions and activity test results are as follows: The furfural selective hydrogenation conversion catalyst was placed in a 250 mL high-pressure reactor for catalytic hydrogenation activity evaluation. The reaction system consisted of 1.0 g catalyst, 30 mmol furfural, and 80 mL deionized water. The reaction was carried out at 150 °C, 1.8 MPa hydrogen pressure, and 900 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 99.1%, the selectivity for 2-methylfuran was 94.7%, and the yield was 93.8%.

[0031] 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 hollow structure catalyst for the aqueous-phase hydrogenation conversion of furfural, characterized in that, The catalyst comprises a hollow SiO2 support, the inner surface of which is modified with a hydrophobic carbon layer formed by chemical bonding of a silane coupling agent, and the outer surface of the SiO2 support is loaded with active metal particles; wherein the SiO2 support accounts for 70 to 90 wt% of the total mass of the catalyst, the active metal particles account for 5 to 25 wt% of the total mass of the catalyst, and the hydrophobic carbon layer accounts for 1 to 7 wt% of the total mass of the catalyst.

2. The hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 1, characterized in that, The shell thickness of the hollow SiO2 support is 20 ~ 100 nm.

3. The hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 1, characterized in that, The active metal particles have a particle size of 2 to 12 nm and are composed of one or more of Cu, Ni, and Co.

4. A method for preparing a hollow structure catalyst for the aqueous hydrogenation conversion of furfural as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Under vigorous stirring, the toluene solution containing the silane coupling agent is rapidly mixed with water and processed using a high-speed shear emulsifier to obtain an emulsion; S2. Add sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, and 28 wt% ammonia water to the above emulsion, then add anhydrous ethanol and tetraethyl orthosilicate. Stir the reaction under constant temperature conditions. After washing, the reaction product is dispersed in the aqueous phase to obtain hollow Si with a hydrophobic carbon layer in the inner cavity. Suspension, denoted as hollow Si (C) Suspension; S3. Add a mixed solution of metal M salt, water, and 28 wt% ammonia solution to the hollow Si. (C) After being thoroughly mixed in a suspension, a hydrothermal reaction is carried out. The reaction product is then washed, dried, calcined, and reduced to obtain the furfural aqueous phase hydrogenation conversion hollow structure catalyst M / Si. (C).

5. The method for preparing the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 4, characterized in that, The silane coupling agent includes one or more combinations of methyltrimethoxysilane, ethyltrimethoxysilane, octyltrimethoxysilane, aminopropyltriethoxysilane, vinyltriethoxysilane, isobutyltriethoxysilane, methyltrichlorosilane, trimethylchlorosilane, and vinyldimethylchlorosilane.

6. The method for preparing the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 4, characterized in that, In step S1, the concentration of the silane coupling agent in the toluene solution containing the silane coupling agent is 0.5 ~ 2.5 wt%; the toluene solution containing the silane coupling agent is mixed with water at a mass ratio of 1:(2 ~ 7); the speed of the high-speed shear emulsifier is 5000 ~ 15000 rpm, and the processing time is 2 ~ 5 min.

7. The method for preparing the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 4, characterized in that, In step S2, the mass ratio of sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, 28 wt% ammonia, anhydrous ethanol, tetraethyl orthosilicate, and the emulsion obtained in step S1 is 1:(6~12):(6~12):(60~120):(8~30):(600~1500); the stirring speed is 300~800 rpm, and the reaction time is 1~8 h; the washed reaction product is dispersed in deionized water at a mass ratio of 1:(10~40) to obtain hollow Si (C) Suspension.

8. The method for preparing the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 4, characterized in that, In step S3, the mixed solution reacts with the hollow Si... (C) The mass ratio of the suspension is (0.3 ~ 3):1; in the mixed solution, the mass ratio of metal M salt, water and 28 wt% ammonia water is 1:(10 ~ 30):(10 ~ 30).

9. The method for preparing the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 4, characterized in that, In step S3, the hydrothermal reaction temperature is 120~200 ℃ and the reaction time is 4~8 h; the drying temperature is 60~100 ℃ and the time is 10~20 h; the calcination temperature is 400~600 ℃ and the time is 2~5 h.

10. The method for preparing the hollow structure catalyst for the aqueous hydrogenation conversion of furfural according to claim 4, characterized in that, In step S3, the reduction process is carried out in a mixed atmosphere of nitrogen and hydrogen, the reduction temperature is 300 ~ 600 ℃, and the reduction time is 1 ~ 4 h, wherein the volume ratio of nitrogen to hydrogen in the mixed atmosphere is 1: (0.1 ~ 10).

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