Honeycomb SiO2 nano-reactor as well as preparation method and application thereof

Abstract

The invention discloses a honeycomb SiO2 nanoreactor as well as a preparation method and application thereof. The preparation method comprises the steps that metal ions are highly dispersed in micelles through the coordination complexing capacity of a surfactant, the metal ions are wrapped in SiO2 through the hydrolysis and polymerization effects of tetraethyl orthosilicate, and growth of metal particles can be effectively inhibited; the honeycomb SiO2 nanoreactor with high specific surface area and large aperture is formed through roasting, the nanoreactor comprises highly dispersed small-size metal particles, and the obtained honeycomb SiO2 nanoreactor can eliminate the influence of mass transfer in a catalytic reaction on a core-shell catalyst; effective collision between active components of the catalyst and reactants can be remarkably increased through a confinement effect, so that the catalytic reaction is accelerated; the catalyst disclosed by the invention is simple in preparation process, has the advantages of uniformity, good thermal stability and high repeatability, is easy to realize automatic production, and is suitable for large-scale popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a honeycomb SiO2 nanoreactor and a preparation method and application thereof, and in particular to a controllable preparation method of the honeycomb SiO2 nanoreactor. Background Art

[0002] Phenol is an important organic chemical raw material, which can be used to synthesize resins such as phenolic resin and bisphenol A, and can also be used as an important raw material for producing bactericides, preservatives and medicines (such as aspirin). Parachlorophenol is the main component in the wastewater of the printing and dyeing industry. If it is not effectively treated, it will seriously damage the environment and freshwater resources. Compared with traditional wastewater treatment methods, the catalytic hydrodechlorination of parachlorophenol to phenol with higher added value is one of the most promising and promising methods for treating chlorophenol in wastewater. The catalyst used in the catalytic reaction process of this method is mainly a Pd-based catalyst. Due to the generation of HCl in the reaction, the acidification of the reaction system will be caused, resulting in the loss of active components in the catalyst. Therefore, the structure and composition design of the reaction have a vital effect for reducing the loss of active components.

[0003] In the prior art, there are many types of catalytic systems applied to chlorophenol catalytic hydrodechlorination, but most of them focus on supported catalysts. However, supported catalysts often lead to deactivation of the catalyst and a large loss of reaction components due to poor thermal stability and easy loss of reaction components, resulting in secondary pollution of water bodies. Compared with supported catalysts, core-shell catalysts can effectively suppress the loss of metal active components due to the protection of the shell layer, and the presence of the confinement effect can significantly accelerate the reaction. However, most of the preparation methods of core-shell catalysts in the prior art have complex synthesis processes, excessive size of the active components of the synthetic catalyst, and too small pore size and specific surface area of ​​the catalyst, resulting in a great influence of mass transfer resistance on catalytic hydrodechlorination, thereby making the catalytic reaction inefficient.

[0004] In summary, the present invention provides a honeycomb SiO2 nanoreactor and a preparation method thereof, which have solved the technical problems existing in the core-shell catalyst in the prior art. Summary of the Invention

[0005] The purpose of the present invention is to provide a honeycomb SiO2 nanoreactor and its preparation method and application, which not only solves the technical problems of the core-shell structure catalyst in the prior art such as the small pore size and specific surface area, but also has the advantages of simple preparation process.

[0006] To achieve the aforementioned purpose of the invention, the present invention provides a method for preparing a honeycomb SiO2 nanoreactor, comprising wrapping silicon dioxide on the surface of nano-metal particles, inhibiting the growth of the nano-metal particles by over-confinement, and then forming a honeycomb porous structure on the surface of the silicon dioxide by high-temperature calcination, thereby obtaining a honeycomb SiO2 nanoreactor containing metal or metal oxide.

[0007] As one of the preferred embodiments, after the metal ions are mixed with the surfactant, the metal ions coordinate with the surfactant and are evenly dispersed in the micelles formed by the surfactant; then tetraethyl orthosilicate is added, and silica is generated by hydrolysis and polymerization, and the metal ions are simultaneously wrapped in the silica to form a coated core-shell structure.

[0008] As one of the preferred embodiments, the method for preparing the honeycomb SiO2 nanoreactor comprises the following steps:

[0009] Step 1: Dissolve the surfactant in the aqueous phase under stirring at room temperature, add an alkaline metal salt solution, and disperse the metal ions in the micelles formed by the surfactant;

[0010] Step 2: After the metal salt is evenly dispersed, tetraethyl orthosilicate is added, and tetraethyl orthosilicate undergoes hydrolysis and polymerization reaction, and the reaction product covers the metal ions to form a core-shell structure;

[0011] Step 3: After the reaction is completed, the product is post-treated and then calcined and reduced at high temperature to obtain a honeycomb SiO2 nanoreactor containing metal or metal oxide.

[0012] As one of the preferred embodiments, in step 1, the surfactants are sodium hexadecylbenzenesulfonate and dodecylamine.

[0013] Preferably, the mass ratio of sodium hexadecylbenzenesulfonate to dodecylamine is 10:1-5.

[0014] The above technical solution has good controllability over both the honeycomb pore size and the metal size. In the surfactant, the amount of dodecylamine added is controlled at 10-40 mg for every 100 g of sodium hexadecylbenzenesulfonate. At this time, the honeycomb pores can be effectively adjusted to the range of 0.5-4 nm. When the amount of dodecylamine added is less than 10 mg, the material will form a solid structure, and when it is higher than 40 mg, the material structure will break.

[0015] At the same time, the present invention controls the ratio of tetraethyl silicate to metal salt in the range of 30:1-360:1. When it is lower than 30:1, silica balls cannot be formed. When it is higher than 360:1, a honeycomb structure cannot be formed and only a sheet-like structure material can be obtained.

[0016] As one of the preferred embodiments, the alkaline metal salt solution is a mixed solution of metal salt and alkali solution.

[0017] As one of the preferred embodiments, the metal salt solution is a metal chlorate or nitrate solution.

[0018] As one of the preferred embodiments, the alkali solution is one of ammonia water or sodium hydroxide.

[0019] As one of the preferred embodiments, the molar ratio of the metal salt to dodecylamine is 0:1 to 1:1.

[0020] As one of the preferred embodiments, in step 2, the molar ratio (or mass ratio) of tetraethyl silicate to metal salt is 30:1 to 360:1.

[0021] The reaction time of hydrolysis and polymerization of tetraethyl silicate is 1 to 3 hours.

[0022] As one of the preferred embodiments, in step 3, the post-treatment includes centrifugally washing the catalyst with deionized water and ethanol and then drying it, and the drying temperature is 60-80°C.

[0023] As one of the preferred implementations, the high-temperature calcination is carried out at a temperature of 300 to 400° C. and for a time of 3 to 6 hours.

[0024] As one of the preferred implementations, the reduction temperature is 200-300° C., and the time is 3-6 hours.

[0025] As the second purpose of the invention, the present invention also provides a honeycomb SiO2 nanoreactor, which is prepared by the preparation method described above.

[0026] As the third object of the invention, the present invention also provides a honeycomb SiO2 nanoreactor prepared by the preparation method as described above, or the use of the honeycomb SiO2 nanoreactor as described above in catalytic hydrodechlorination to produce phenol.

[0027] Compared with the prior art, the advantages of the present invention include:

[0028] 1. The nanoreactor provided by the technical solution of the present invention has a shell structure wrapped with SiO2, which can obtain highly dispersed small-sized metal particles, effectively inhibiting the growth of metal particles. At the same time, the size of the metal particles can be controlled by adjusting the addition amount of SiO2 and metal particles, thereby realizing the controllable preparation of the nanoreactor; at the same time, after removing the surfactant by high-temperature calcination, a honeycomb-shaped shell structure with a high specific surface area and large pore size can be obtained, which can eliminate the influence of mass transfer on the core-shell catalyst in the catalytic reaction, and due to the formation of the honeycomb porous structure, the effective collision between the active components of the catalyst and the reactants can be significantly increased through the confinement effect, thereby accelerating the catalytic reaction.

[0029] 2. The technical solution of the present invention does not require complicated equipment and has a simple preparation process. It only requires mixing the metal ions dispersed in the micelles with the silica precursor to synthesize a catalyst material with a core-shell structure. A honeycomb porous structure can be obtained by high-temperature calcination. Therefore, the synthesized catalyst has the characteristics of uniformity and high repeatability, and it is easy to realize the automated production of catalyst preparation. The synthesized catalyst has good thermal stability and high reusability, and is suitable for large-scale promotion and production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1a and Figure 1b They are TEM and magnified images of the honeycomb SiO2 nanoreactor prepared in Example 1 of the present invention.

[0032] Figure 2 This is the XRD pattern of the honeycomb SiO2 nanoreactor prepared in Example 1 of the present invention.

[0033] Figure 3a and Figure 3b They are respectively the BET diagram and pore size distribution diagram of the honeycomb SiO2 nanoreactor prepared in Example 1 of the present invention.

[0034] Figure 4 This is a TEM image of the honeycomb SiO2 nanoreactor prepared in Example 2 of the present invention.

[0035] Figure 5 This is the XRD pattern of the honeycomb SiO2 nanoreactor prepared in Example 2 of the present invention.

[0036] Figure 6a and Figure 6b They are respectively the BET diagram and pore size distribution diagram of the honeycomb SiO2 nanoreactor prepared in Example 2 of the present invention.

[0037] Figure 7 This is a TEM image of the honeycomb SiO2 nanoreactor prepared in Example 3 of the present invention.

[0038] Figure 8 This is a TEM image of the honeycomb SiO2 nanoreactor prepared in Example 4 of the present invention.

[0039] Figure 9 It is a TEM image of the supported catalyst prepared in Comparative Example 1 of the present invention.

[0040] Figure 10 It is the XRD pattern of the supported catalyst prepared in Comparative Example 1 of the present invention.

[0041] Figure 11 It is a TEM image of the material of Comparative Example 2 of the present invention.

[0042] Figure 12 This is a TEM image of the material of Comparative Example 3 of the present invention.

[0043] Figure 13a and Figure 13b Comparison charts of multiple catalytic cycle stability tests of the catalysts of Example 1 and Comparative Example 1, respectively. DETAILED DESCRIPTION

[0044] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. The main purpose is to provide a honeycomb SiO2 nanoreactor and a preparation method thereof. The metal ions are highly dispersed by micelles formed by surfactants, and then the metal ions are encapsulated in silica to form a core-shell structure through hydrolysis and polymerization reactions. At the same time, the confining effect of the coating can effectively inhibit the growth of metal particles and realize the control of the size of the metal particles; then, through high-temperature calcination and reduction, the surfactant is removed to obtain a porous structure with a honeycomb shape.

[0045] The technical solution, its implementation process and principles are further explained below.

[0046] As one aspect of the technical solution of the present invention, the present invention provides a method for preparing a honeycomb SiO2 nanoreactor with large pore size, high specific surface area and metal dispersion, the specific steps comprising:

[0047] Step 1: Dissolve the surfactant in the aqueous phase under stirring at room temperature, add the required metal salt solution, stir evenly, then add tetraethyl orthosilicate to carry out hydrolysis and polymerization reaction, so that the metal ions are coated in the silicic acid (silicon dioxide) generated by the hydrolysis and polymerization reaction;

[0048] Step 2: After the reaction is completed, the product is post-treated, and then calcined and reduced at high temperature to obtain a honeycomb SiO2 nanoreactor containing metal or metal oxide.

[0049] In some specific embodiments, the surfactant includes a combination of sodium hexadecylbenzenesulfonate and dodecylamine.

[0050] In some specific embodiments, the mass ratio of sodium hexadecylbenzenesulfonate to dodecylamine is 10:1-5.

[0051] In some specific embodiments, the pH of the surfactant is 9-10.

[0052] In some specific embodiments, the reaction time of the hydrolysis polymerization is 1 to 3 hours.

[0053] In some specific embodiments, the molar ratio of the metal salt to dodecylamine is 0:1 to 1:1.

[0054] In some specific embodiments, the molar ratio of tetraethyl silicate to metal salt is 30:1 to 360:1.

[0055] More preferably, when the mass of sodium hexadecylbenzenesulfonate is 100 mg, the added volume of tetraethyl orthosilicate is 750 μL.

[0056] As one of the most preferred embodiments, the present invention uses sodium hexadecylbenzenesulfonate and dodecylamine as co-surfactants. The coordination and complexing ability of the amino group in dodecylamine allows the metal ions to be highly dispersed in micelles. The metal ions are then encapsulated in SiO2 through hydrolysis and polymerization of tetraethyl orthosilicate. The surfactant is then removed by calcination to form a honeycomb-shaped SiO2 nanoreactor. Due to the SiO2 encapsulation, the nanoreactor can produce highly dispersed small-sized metal particles, effectively inhibiting the growth of the metal particles. After high-temperature calcination to remove the surfactant, the material has a high specific surface area and large pore size, which can eliminate the influence of mass transfer on the core-shell catalyst during the catalytic reaction. At the same time, the formation of the honeycomb porous structure can significantly increase the effective collision between the active components of the catalyst and the reactants through the confinement effect, thereby accelerating the catalytic reaction.

[0057] The catalyst preparation process of the present invention is simple, the synthesized catalyst is uniform and highly repeatable, and the automated production of catalyst preparation is easy to realize; the synthesized catalyst has good thermal stability and high reusability.

[0058] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods in the following examples where specific conditions are not specified are generally based on conventional conditions or the conditions recommended by the manufacturer.

[0059] Example 1

[0060] This embodiment provides a method for preparing a honeycomb SiO2 nanoreactor with large pore size, high specific surface area and metal dispersion. Specifically, the preparation steps include:

[0061] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 10.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution forms. 5.8 mg of potassium tetrachloropalladate and 100 μL of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 750 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to react for 2.0 h at a stirring speed of 500 rpm.

[0062] (2) After the reaction is completed, stirring is stopped, the reaction liquid is collected by centrifugation, and washed with deionized water and ethanol three times each, and placed in an oven to dry overnight at 60°C, and then calcined in a muffle furnace at 300°C and reduced in a tubular furnace at 250°C to obtain a highly dispersed Pd honeycomb SiO2 nanoreactor.

[0063] like Figure 1a and Figure 1b The figure shows the TEM image of the SiO2 nanoreactor obtained in this example. It can be seen from the figure that the prepared SiO2 nanoreactor has a honeycomb structure with a honeycomb pore size of 0.5 to 1 nm. There are a large number of porous structures, and Pd metal nanoparticles are highly dispersed in the nanoreactor, providing sufficient reaction channels for subsequent catalytic reactions as a catalyst.

[0064] Figure 2 2 is the XRD pattern of this embodiment. It can be seen from the figure that the diffraction peaks of the product correspond to the SiO2 and Pd standard card patterns (JCPDS29-0085; JCPDS 460-1043), and no other impurity peaks appear.

[0065] Figure 3a and Figure 3b 1 and 2 are the BET diagram and pore size distribution of this embodiment respectively. It can be seen from the figure that the SiO2 nanoreactor has abundant micropores and large-pore mesoporous structure.

[0066] Example 2

[0067] This embodiment provides a method for preparing a honeycomb SiO2 nanoreactor with large pore size, high specific surface area, and high metal dispersion, specifically including the effect of the amount of dodecylamine added on the honeycomb structure of the material. The preparation steps include:

[0068] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 40.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution is obtained. 5.8 mg of potassium tetrachloropalladate and 100 μL of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 750 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to proceed for 2.0 h at a stirring speed of 500 rpm.

[0069] (2) After the reaction is completed, stirring is stopped, the reaction solution is collected by centrifugation, and washed with deionized water and ethanol three times each, and placed in an oven to dry overnight at 60°C, and then calcined in a muffle furnace at 300°C and reduced in a tubular furnace at 250°C to obtain a highly dispersed Pd-containing honeycomb SiO2 nanoreactor.

[0070] Figure 4 This is the TEM image of the Pd honeycomb SiO2 nanoreactor obtained in this example. It can be seen from the figure that the prepared catalyst has a honeycomb structure with a honeycomb pore size of 3-4nm. There are a large number of porous structures, and the Pd metal nanoparticles are highly dispersed in the nanoreactor, providing sufficient reaction channels for subsequent catalytic reactions.

[0071] Figure 5 This is the XRD pattern of the Pd honeycomb SiO2 nanoreactor obtained in this example. It can be seen from the figure that the diffraction peaks of the product correspond to the SiO2 and Pd standard card patterns (JCPDS29-0085; JCPDS 460-1043), and no other impurity peaks appear.

[0072] Figure 6a and Figure 6b 1 and 2 are the BET diagram and pore size distribution of the Pd honeycomb SiO2 nanoreactor obtained in this embodiment, respectively. It can be seen from the diagram that the material has a mesoporous structure with abundant micropores and large pores.

[0073] Example 3

[0074] This example provides the effect of the ratio of tetraethyl silicate to metal ions on the material structure. Specifically, the preparation steps include:

[0075] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 10.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution forms. 5.8 mg of potassium tetrachloropalladate and 100 μL of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 187.5 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to proceed for 2.0 h at a stirring speed of 500 rpm.

[0076] (2) After the reaction is completed, stirring is stopped, the reaction solution is collected by centrifugation, and washed with deionized water and ethanol three times each, and placed in an oven to dry overnight at 60°C, and then calcined in a muffle furnace at 300°C and reduced in a tubular furnace at 250°C to obtain a highly dispersed Pd-containing honeycomb SiO2 nanoreactor.

[0077] Figure 7 This is the TEM image of the Pd honeycomb SiO2 nanoreactor obtained in this example. It can be seen from the figure that the prepared catalyst has a honeycomb structure with a honeycomb pore size of 0.5-1nm, a large number of porous structures, and the size of the Pd metal nanoparticles becomes larger.

[0078] Example 4

[0079] This embodiment provides the effect of calcination temperature on the structure of the synthetic material. Specifically, the preparation steps include:

[0080] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 10.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution is obtained. 5.8 mg of potassium tetrachloropalladate and 100 L of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 750 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to proceed for 2.0 h at a stirring rate of 500 rpm.

[0081] (2) After the reaction is completed, stirring is stopped, the reaction solution is collected by centrifugation, and washed with deionized water and ethanol three times each, and placed in an oven to dry overnight at 60-80°C, and then calcined in a muffle furnace at 500°C and reduced in a tubular furnace at 250°C to obtain a highly dispersed Pd-containing honeycomb SiO2 nanoreactor.

[0082] Figure 8 This is the TEM image of the Pd honeycomb SiO2 nanoreactor obtained in this example. It can be seen from the figure that the prepared catalyst has a honeycomb structure with a honeycomb pore size of 0.5-1nm. There are a large number of porous structures, but the Pd metal nanoparticles show agglomeration and migration.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing a supported catalyst. Specifically, the preparation steps include:

[0085] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 10.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution is obtained. 5.8 mg of potassium tetrachloropalladate and 100 μL of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 750 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to react for 2.0 h at a stirring speed of 500 rpm. After the reaction is complete, stirring is stopped, and the reaction solution is collected by centrifugation, washed three times with deionized water and three times with ethanol, and dried in an oven at 60°C overnight.

[0086] (2) At 160°C and 700 rpm, 20 mL of octadecene was added to a three-necked flask, and 3 mL of oleylamine solution containing 5.8 mg of potassium tetrachloropalladate was added. The mixture was heated and stirred for 3 h. Under nitrogen protection, the water in the solvent was removed, and 2 mL of n-butyl lithium solution was pipetted into the above solution to form a black Pd nanoparticle solution. The mixture was stirred for 3 h. After the reaction, the reaction solution was centrifuged and washed with acetone three times. Pd was dissolved in ethanol for later use. The powder from step 1 was added to a three-necked flask, and the Pd solution dissolved in ethanol was added. Under nitrogen protection at 70°C, the ethanol in the reaction flask was blown dry, the powder was dried in an oven at 60°C, and then calcined in a muffle furnace at 300°C. The catalyst was reduced in a tube furnace at 250°C to obtain a comparative supported catalyst.

[0087] Figure 9 This is a TEM image of the sample obtained in Comparative Example 1. It can be seen from the figure that the size of Pd in ​​the prepared catalyst is similar to that in Example 1.

[0088] Figure 10 This is the XRD diagram of Comparative Example 1. It can be seen from the figure that the width and intensity of the Pd diffraction peak are similar to those of Example 1, indicating that the two have similar Pd particle sizes.

[0089] Comparative Example 2

[0090] This comparative example provides the effect of exceeding the dodecylamine content on material preparation. The preparation steps include:

[0091] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 50.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution forms. 5.8 mg of potassium tetrachloropalladate and 100 μL of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 750 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to react for 2.0 h at a stirring speed of 500 rpm.

[0092] (2) After the reaction is completed, stirring is stopped, the reaction solution is collected by centrifugation, and washed with deionized water and ethanol three times each, and placed in an oven to dry at 60°C overnight, and then calcined in a muffle furnace at 300°C and reduced in a tube furnace at 250°C to obtain the corresponding material.

[0093] like Figure 11 The TEM image of the material obtained in this comparative example is shown. It can be seen from the figure that the prepared catalyst has collapsed. This result shows that when the amount of dodecylamine added is too large, the structure collapses.

[0094] Comparative Example 3

[0095] This comparative example provides the effect of the ratio of tetraethyl silicate to metal ions exceeding the range on the material structure. Specifically, the preparation steps include:

[0096] (1) At room temperature, weigh 100.0 mg of sodium hexadecylbenzenesulfonate and 10.0 mg of dodecylamine, add them to 46.0 g of water, and stir until a clear solution is obtained. 5.8 mg of potassium tetrachloropalladate and 100 L of aqueous ammonia are added to the reaction solution, and the reaction solution is stirred for 0.5 h. 2500 μL of tetraethyl orthosilicate is added to the reaction solution, and the reaction is allowed to proceed for 2.0 h at a stirring speed of 500 rpm.

[0097] (2) After the reaction is completed, stirring is stopped, the reaction solution is collected by centrifugation, and washed with deionized water and ethanol three times each, and placed in an oven to dry at 60°C overnight, and then calcined in a muffle furnace at 300°C and reduced in a tube furnace at 250°C to obtain the corresponding material.

[0098] Figure 12 This is a TEM image of the material obtained in this comparative example. It can be seen from the figure that the prepared material forms a flaky structure.

[0099] Further, the catalyst obtained in the above Examples 1-2 and Comparative Example 1 was used for the catalytic hydrodechlorination of chlorophenol to prepare phenol. The specific method is as follows: 5 mg of catalyst, 100 mg of p-chlorophenol, 28 mg of NaOH and 20 mL of ethanol were added to a reaction flask. Under the conditions of magnetic stirring and hydrogen bubbling, the reaction was carried out for 0.5 h. The liquid after the reaction was measured by gas chromatography to determine the conversion rate of p-chlorophenol and the selectivity of phenol. The test results are shown in Table 1. At the same time, in order to verify the catalyst stability of the above Example 1 and Comparative Example 1, the catalyst was subjected to multiple cycle stability tests according to the above method. The test data are shown in Table 1. Figure 13a and Figure 13b As shown in the figure, it can be seen that the catalyst provided by the present invention has better catalytic stability than the supported catalyst.

[0100] Table 1 Comparison of catalytic performance of the catalysts obtained in the examples and comparative examples

[0101] sample Conversion rate of parachlorophenol / % Phenol selectivity / % Yield of phenol / % Example 1 99.8％ 100.0％ 99.8％ Example 2 70.0％ 100.0％ 70.0％ Example 3 80.0％ 90.0％ 72.0％ Example 4 60.0％ 100.0％ 60.0％ Comparative Example 1 30.0％ 80.0％ 24.0％

[0102] From the test results in Table 1, it can be seen that the Pd-containing honeycomb SiO2 nanoreactor prepared by this method (Examples 1-2) has excellent catalytic activity and selectivity in the catalytic hydrodechlorination reaction of p-chlorophenol. The activity and selectivity of Comparative Example 1 (supported catalyst) are relatively low. The main reason is that the honeycomb nanoreactor catalyst synthesized by the present invention suppresses the loss and agglomeration of metal during the reaction due to the protection of the shell; on the other hand, due to the presence of the honeycomb structure, the catalyst further accelerates the occurrence of the deep hydrogenation reaction through the confinement effect, thereby significantly improving the rate and selectivity of the catalytic reaction.

[0103] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and are not intended to limit the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0104] Throughout this disclosure, where compositions are described as having, containing, or comprising particular components, or where processes are described as having, containing, or comprising particular process steps, it is contemplated that the compositions taught by this disclosure also consist essentially of, or consist of, the recited components, and that the processes taught by this disclosure also consist essentially of, or consist of, the recited process steps.

[0105] Should be understood that, the order of each step or the order in which specific action is performed is not very important, as long as the present invention teachings remain operable.In addition, two or more steps or actions can be performed simultaneously.

[0106] Although the present invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions, and / or additions may be made and that substantial equivalents may be substituted for elements of the described embodiments without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the scope of the invention. Therefore, it is not intended that the present invention be limited to the specific embodiments disclosed for carrying out the invention, but rather that the invention will encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method for preparing a honeycomb SiO2 nanoreactor, characterized in that: Silicon dioxide is wrapped on the surface of organic micelles complexed with metal ions, and the growth of the nano-metal particles is inhibited by the confinement effect of the shell. A honeycomb porous structure is then formed on the surface of the silicon dioxide by high-temperature calcination, thereby obtaining a honeycomb SiO2 nanoreactor containing metal or metal oxide.

2. The method for preparing the honeycomb SiO2 nanoreactor according to claim 1, characterized in that: After the metal ions are mixed with the surfactant, the metal ions coordinate with the surfactant and are evenly dispersed in the micelles formed by the surfactant; then tetraethyl orthosilicate is added, and silicon dioxide is generated through hydrolysis and polymerization, and the metal ions are wrapped in the silicon dioxide to form a coated core-shell structure.

3. The method for preparing the honeycomb SiO2 nanoreactor according to claim 1, characterized in that: The following steps are involved: Step 1: Dissolve the surfactant in the aqueous phase under stirring at room temperature, add an alkaline metal salt solution, and disperse the metal ions in the micelles formed by the surfactant; Step 2: After the metal salt is evenly dispersed, tetraethyl orthosilicate is added, and tetraethyl orthosilicate undergoes hydrolysis and polymerization reaction, and the reaction product covers the metal ions to form a core-shell structure; Step 3: After the reaction is completed, the product is post-treated and then calcined and reduced at high temperature to obtain a honeycomb SiO2 nanoreactor containing metal or metal oxide.

4. The method for preparing the honeycomb SiO2 nanoreactor according to claim 3, characterized in that: In step 1, the surfactant includes sodium hexadecylbenzenesulfonate and dodecylamine; and / or, the mass ratio of sodium hexadecylbenzenesulfonate to dodecylamine is 10:1-5; And / or, the pH of the mixed solution of sodium hexadecylbenzenesulfonate and dodecylamine is 9-10.

5. The controllable preparation method of the honeycomb SiO2 nanoreactor according to claim 3, characterized in that: The alkaline metal salt solution is a mixed solution of metal salt and alkali solution; And / or, the metal salt solution is a metal chlorate or nitrate solution; And / or, the alkali solution is one of ammonia water or sodium hydroxide.

6. The method for preparing the honeycomb SiO2 nanoreactor according to claim 3, characterized in that: The molar ratio of the metal salt to dodecylamine is 0:1 to 1:

1.

7. The method for preparing a honeycomb SiO2 nanoreactor according to claim 1, characterized in that: In step 2, the molar ratio of tetraethyl silicate to metal salt is 30:1-360:

1.

8. The method for preparing a honeycomb SiO2 nanoreactor according to claim 1, characterized in that: In step 3, the post-treatment includes centrifugally washing the catalyst with deionized water and ethanol and then drying it; the drying temperature is 60-80°C; The high temperature calcination temperature is 300-400°C and the time is 3-6h; The reduction temperature is 200-300° C., and the reduction time is 3-6 hours.

9. A honeycomb SiO2 nanoreactor prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a honeycomb SiO2 nanoreactor prepared by the preparation method according to any one of claims 1 to 8, or a honeycomb SiO2 nanoreactor according to claim 9 in catalytic hydrodechlorination to produce phenol.

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