MIL-68 (Al) / SBA-15-COOH composite material as well as preparation method and application thereof

Abstract

The invention provides an MIL-68 (Al) / SBA-15-COOH composite material as well as a preparation method and application thereof, and belongs to the technical field of composite mesoporous materials. According to the invention, vinyl functionalized mesoporous silica SBA-15-vinyl is treated by nitric acid to prepare SBA-15-COOH, so that the stability of the structure of the composite material is improved; a functional group on the surface of the SBA-15-COOH is grafted with MIL-68 (Al), so that the problems of non-uniform dispersion and agglomeration of the MIL-68 (Al) are effectively solved, and the catalytic performance and the stability of the composite material are remarkably improved; by constructing a composite structure of silicon dioxide and MIL-68 (Al) (belonging to MOFs), the advantages of mechanical strength and chemical stability of silicon dioxide and high catalytic activity of MOFs can be integrated, and an electronic structure of an active site is regulated and controlled by virtue of an electronic synergistic effect between interfaces of the silicon dioxide and the MOFs, so that reaction activation energy is reduced, the catalytic efficiency and the cycling stability are improved, and the catalytic activity of the MOFs is improved. A new direction is provided for developing a high-performance 4-nitrophenol catalytic reduction system.

Description

Technical Field

[0001] The present invention relates to the technical field of composite mesoporous materials, and in particular to a MIL-68(Al) / SBA-15-COOH composite material and a preparation method and application thereof. Background Art

[0002] As a typical organic pollutant, 4-nitrophenol (4-NP) has become a key target for global environmental pollution control due to its high biological toxicity, environmental persistence and bioaccumulation. 4-NP is widely present in the wastewater systems of fine chemicals, pharmaceutical synthesis and printing and dyeing industries. It migrates through the soil-water medium, posing multiple threats to ecosystems and human health. In the development of technologies for 4-NP pollution control, traditional physical adsorption methods are limited by bottlenecks such as limited adsorption capacity and low regeneration efficiency, while biodegradation methods have defects such as slow reaction kinetics and poor substrate selectivity. In contrast, catalytic reduction technology has become a cutting-edge research direction in the field of environmental catalysis due to its advantages such as precise controllable reaction pathways, mild reaction conditions (operation at room temperature and pressure), and the ability to generate high-value-added products from pollutants.

[0003] Of particular note is that the 4-NP heterogeneous catalytic hydrogenation system using sodium borohydride (NaBH4) as a hydrogen source can selectively convert the target pollutant into 4-aminophenol (4-AP). This product is not only an important intermediate in the synthesis of antipyretic and analgesic drugs, but also has key application value in the fields of dye development, functional modification of polymer materials, and preparation of nanocatalytic materials. In the field of catalytic material design, silica-based composite materials are regarded as ideal supports for 4-NP catalytic reduction due to their controllable pore structure, ultra-large specific surface area, and abundant surface modification sites. However, traditional silica supports have low metal ion loading efficiency and difficulty in regulating the coordination environment due to the lack of active sites on the surface, which seriously restricts their catalytic performance. Therefore, providing a catalyst for catalyzing 4-NP reduction with a high active component loading rate and stable catalytic activity is a technical problem that needs to be solved in the prior art. Summary of the Invention

[0004] The object of the present invention is to provide a MIL-68(Al) / SBA-15-COOH composite material, a preparation method and application thereof. The MIL-68(Al) / SBA-15-COOH composite material provided by the present invention has excellent catalytic activity, uniform dispersion of active components, high and stable loading rate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a MIL-68(Al) / SBA-15-COOH composite material, comprising a carrier and an active component MIL-68(Al); the active component is grafted onto the carrier;

[0007] The carrier SBA-15-COOH is prepared from nitric acid and vinyl-functionalized mesoporous silica SBA-15-vinyl;

[0008] The SBA-15-vinyl is prepared by co-condensing a vinyl functionalization reagent and an inorganic silicon source.

[0009] Preferably, the MIL-68(Al) / SBA-15-COOH composite material is a mesoporous material with an average pore diameter of 3 to 9 nm.

[0010] Preferably, the loading amount of MIL-68(Al) in the MIL-68(Al) / SBA-15-COOH composite material is 14 wt% to 23 wt%.

[0011] Preferably, the vinyl functionalization agent is vinyltrimethoxysilane, and the inorganic silicon source is ethyl orthosilicate.

[0012] The present invention also provides a method for preparing the MIL-68(Al) / SBA-15-COOH composite material described in the above technical solution, comprising the following steps:

[0013] (1) P123, water and dilute hydrochloric acid were mixed and stirred to obtain a clear solution;

[0014] Adding vinyltrimethoxysilane and tetraethyl orthosilicate to the clear solution, and sequentially performing heating and stirring, a first post-treatment, and a template removal treatment to obtain SBA-15-vinyl;

[0015] (2) mixing the SBA-15-vinyl obtained in step (1) with concentrated nitric acid, and performing a first reflux stirring and a second post-treatment to obtain SBA-15-COOH;

[0016] (3) dispersing the SBA-15-COOH obtained in step (2) in an Al(NO3)3·6H2O solution, and drying and pulverizing to obtain a solid;

[0017] (4) After the solid obtained in step (3) is mixed with water and H3BTC-ethanol solution, a second reflux stirring and a third post-treatment are performed in sequence to obtain a MIL-68(Al) / SBA-15-COOH composite material.

[0018] Preferably, the temperature of the heating and stirring in step (1) is 30 to 50° C.; and the time of the heating and stirring is 20 to 28 hours.

[0019] Preferably, the concentration of concentrated nitric acid in step (2) is 10-14 mol / L; and the ratio of the mass of SBA-15-vinyl to the volume of concentrated nitric acid is (0.5-4) g:200 mL.

[0020] Preferably, in step (3), the mass ratio of SBA-15-COOH to Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution is 4:(5-15).

[0021] Preferably, the mass ratio of SBA-15-COOH in step (3) to H3BTC in the H3BTC-ethanol solution in step (4) is 4:(0.2-0.9).

[0022] The present invention also provides an application of the MIL-68(Al) / SBA-15-COOH composite material described in the above technical solution or the MIL-68(Al) / SBA-15-COOH composite material prepared by the preparation method in catalyzing the reduction reaction of nitrophenol.

[0023] The present invention provides a MIL-68(Al) / SBA-15-COOH composite material, comprising a carrier and an active component MIL-68(Al); the active component is grafted onto the carrier; the carrier SBA-15-COOH is prepared from nitric acid and vinyl-functionalized mesoporous silica SBA-15-vinyl; and the SBA-15-vinyl is prepared by co-condensation of a vinyl-functionalized reagent and an inorganic silicon source. The present invention utilizes vinyl-functionalized mesoporous silica SBA-15-vinyl to prepare carboxyl-functionalized SBA-15, namely SBA-15-COOH, by treating the vinyl-functionalized mesoporous silica SBA-15-vinyl with nitric acid. When forming a composite material, the carboxyl groups on the surface of SBA-15-COOH participate in MIL-68(Al) through covalent bonds, thereby enhancing the interaction between the two and improving the stability of the composite material structure. The functional groups on the surface of SBA-15-COOH are grafted with MIL-68(Al), effectively solving the problems of uneven dispersion and agglomeration of MIL-68(Al), and significantly improving the catalytic performance and stability of the composite material. The present invention can integrate the mechanical strength and chemical stability of silica with the high catalytic activity advantages of MOFs by constructing a composite structure of silica and MIL-68(Al) (which belongs to MOFs), and regulates the electronic structure of the active site by means of the electronic synergistic effect between the interfaces of the two, thereby reducing the reaction activation energy, improving the catalytic efficiency and cycle stability, and providing a new direction for the development of high-performance 4-NP catalytic reduction systems. The MIL-68(Al) / SBA-15-COOH composite material of the present invention has a simple preparation process, a high reaction conversion rate, and high catalytic activity when used for catalyzing the reduction reaction of 4-nitrophenol. The obtained 4-aminophenol product has high purity, and the reaction process is clean and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a transmission electron micrograph of the MIL-68(Al) / SBA-15-COOH composite material prepared in Example 1 of the present invention;

[0025] Figure 2 Wide-angle XRD patterns of the MIL-68(Al) / SBA-15-COOH composite material and MIL-68(Al) prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a MIL-68(Al) / SBA-15-COOH composite material, comprising a carrier and an active component MIL-68(Al); the active component is grafted onto the carrier;

[0027] The carrier SBA-15-COOH is prepared from nitric acid and vinyl-functionalized mesoporous silica SBA-15-vinyl;

[0028] The SBA-15-vinyl is prepared by co-condensing a vinyl functionalization reagent and an inorganic silicon source.

[0029] In the present invention, unless otherwise specified, the raw materials used are conventional commercial products in the field.

[0030] In the present invention, the MIL-68(Al) / SBA-15-COOH composite material is preferably a mesoporous material; the average pore diameter of the MIL-68(Al) / SBA-15-COOH composite material is preferably 3 to 9 nm, more preferably 5 to 7 nm. Controlling the average pore diameter of the MIL-68(Al) / SBA-15-COOH composite material within this range allows for better loading of the MIL-68(Al) active component, facilitates rapid diffusion of reactant molecules within the pores, and improves the mechanical strength of the support.

[0031] In the present invention, the MIL-68(Al) loading in the MIL-68(Al) / SBA-15-COOH composite material is preferably 14 wt% to 23 wt%, more preferably 16 wt% to 20 wt%. The MIL-68(Al) loading in the MIL-68(Al) / SBA-15-COOH composite material of the present invention is within this range to provide sufficient active sites, improve the dispersion of the MIL-68(Al) active component, and avoid pore clogging, thereby achieving high catalytic activity.

[0032] In the present invention, the vinyl functionalization agent is preferably vinyltrimethoxysilane, and the inorganic silicon source is preferably ethyl orthosilicate.

[0033] The present invention also provides a method for preparing the MIL-68(Al) / SBA-15-COOH composite material described in the above technical solution, comprising the following steps:

[0034] (1) P123, water and dilute hydrochloric acid were mixed and stirred to obtain a clear solution;

[0035] Adding vinyltrimethoxysilane and tetraethyl orthosilicate to the clear solution, and sequentially performing heating and stirring, a first post-treatment, and a template removal treatment to obtain SBA-15-vinyl;

[0036] (2) mixing the SBA-15-vinyl obtained in step (1) with concentrated nitric acid, and performing a first reflux stirring and a second post-treatment to obtain SBA-15-COOH;

[0037] (3) dispersing the SBA-15-COOH obtained in step (2) in an Al(NO3)3·6H2O solution, and drying and pulverizing to obtain a solid;

[0038] (4) After the solid obtained in step (3) is mixed with water and H3BTC-ethanol solution, a second reflux stirring and a third post-treatment are performed in sequence to obtain a MIL-68(Al) / SBA-15-COOH composite material.

[0039] The present invention mixes P123, water and dilute hydrochloric acid, and stirs to obtain a clear solution.

[0040] In the present invention, the concentration of the dilute hydrochloric acid is preferably 2M; the ratio of the mass of the P123 to the volume of the dilute hydrochloric acid is preferably 2g:(40-100)mL. The present invention has no particular limitation on the stirring method, as long as the P123 is completely dissolved.

[0041] After obtaining a clear solution, the present invention adds vinyltrimethoxysilane and tetraethyl orthosilicate to the clear solution, and sequentially performs heating and stirring, a first post-treatment, and a template removal treatment to obtain SBA-15-vinyl.

[0042] In the present invention, the mass ratio of vinyltrimethoxysilane and tetraethyl orthosilicate is preferably 0.82:(2.5-5.5). In the present invention, the temperature of the heating and stirring is preferably 30-50°C; the time of the heating and stirring is preferably 20-28h. The present invention controls the temperature and time of heating and stirring within the above ranges to obtain SBA-15-vinyl with ordered pores. In the present invention, the first post-treatment is preferably: after the heated and stirred product is naturally cooled, it is filtered, washed with distilled water, washed with ethanol, filtered and dried under vacuum conditions at 60°C for 10h. In the present invention, the template removal treatment is preferably performed by Soxhlet extraction, more preferably: the product of the first post-treatment is placed in a Soxhlet extractor, anhydrous ethanol is added at the same time, and treated at 80°C for 12h to obtain SBA-15-vinyl.

[0043] After obtaining SBA-15-vinyl, the present invention mixes the SBA-15-vinyl with concentrated nitric acid, performs a first reflux stirring and a second post-treatment, and obtains SBA-15-COOH.

[0044] In the present invention, the concentration of the concentrated nitric acid is preferably 10-14 mol / L; the ratio of the mass of the SBA-15-vinyl to the volume of the concentrated nitric acid is preferably (0.5-4) g:200 mL.

[0045] In the present invention, the temperature of the first reflux stirring is preferably 60-100°C, more preferably 79-90°C; the duration of the first reflux stirring is preferably 20-28 hours, more preferably 22-26 hours; and the first reflux stirring is performed in an air atmosphere. In the present invention, the temperature and duration of the first reflux stirring are controlled within the above ranges to obtain SBA-15-COOH with more uniform pores.

[0046] In the present invention, the second post-treatment is preferably: cooling the product of the first reflux stirring to room temperature, washing with distilled water, washing with ethanol and vacuum drying at 60° C. for 10 h to obtain SBA-15-COOH.

[0047] After obtaining SBA-15-COOH, the present invention disperses the SBA-15-COOH in an Al(NO3)3·6H2O solution, and obtains a solid through drying and pulverization.

[0048] In the present invention, the mass ratio of the SBA-15-COOH to the Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution is preferably 4:(7-10), more preferably 4:9. The present invention controls the mass ratio of the SBA-15-COOH to the Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution within the above range to control the loading amount of the active component MIL-68(Al).

[0049] In the present invention, the drying temperature is preferably 80-100° C. and the drying time is preferably 6-10 hours. The present invention has no particular limitation on the pulverization method, as long as a powdered solid is obtained.

[0050] After obtaining the solid, the present invention mixes the solid with water and H3BTC-ethanol solution, and then sequentially performs a second reflux stirring and a third post-treatment to obtain a MIL-68(Al) / SBA-15-COOH composite material.

[0051] In the present invention, the method for preparing the H3BTC-ethanol solution preferably comprises: dissolving H3BTC in ethanol and additionally adding deionized water.

[0052] In the present invention, the mass ratio of the SBA-15-COOH to the H3BTC in the H3BTC-ethanol solution is preferably 4:(0.2-0.9), more preferably 4:(0.3-0.8). The present invention controls the mass ratio of SBA-15-COOH to the H3BTC in the H3BTC-ethanol solution within the above range to control the ratio of the carrier SBA-15-COOH to the active component MIL-68(Al) in the composite material.

[0053] In the present invention, the temperature of the second reflux stirring is preferably 110 to 150°C, more preferably 120 to 145°C; the time of the first reflux stirring is preferably 20 to 28 hours, more preferably 22 to 26 hours; the second reflux stirring is carried out in an air atmosphere. The present invention controls the temperature and time of the second reflux stirring within the above range to form an active component MIL-68 (Al) with a better crystal form. In the present invention, the third post-treatment is preferably: cooling the product of the second reflux stirring to room temperature, centrifuging, washing with DMF, washing with methanol, and drying under vacuum conditions at 80°C for 2 hours to obtain a MIL-68 (Al) / SBA-15-COOH composite material.

[0054] The present invention constructs a composite structure of silica and MIL-68(Al), which can integrate the mechanical strength and chemical stability of silica with the high catalytic activity advantages of MIL-68(Al), and uses the electronic synergistic effect between the interfaces of the two to regulate the electronic structure of the active site, thereby reducing the reaction activation energy, improving the catalytic efficiency and cycle stability, and providing a new direction for the development of high-performance 4-NP catalytic reduction systems; and the present invention adopts an in-situ synthesis method combined with a heating synthesis technology in a solution to prepare an ethylene-functionalized silica-loaded MIL-68(Al) composite material, namely, a MIL-68(Al) / SBA-15-COOH composite material, which effectively solves the problems of uneven dispersion and agglomeration of MIL-68(Al), and significantly improves the catalytic performance and stability of the composite material.

[0055] The present invention also provides an application of the MIL-68(Al) / SBA-15-COOH composite material described in the above technical solution or the MIL-68(Al) / SBA-15-COOH composite material prepared by the preparation method in catalyzing the reduction reaction of nitrophenol.

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0057] Example 1

[0058] A MIL-68(Al) / SBA-15-COOH composite material is a mesoporous material with an average pore diameter of 5 to 7 nm, comprising a carrier and an active component MIL-68(Al); the active component is grafted onto the carrier;

[0059] The carrier SBA-15-COOH is prepared from nitric acid and vinyl-functionalized mesoporous silica SBA-15-vinyl;

[0060] The SBA-15-vinyl is prepared by co-condensation of a vinyl functionalization reagent and an inorganic silicon source;

[0061] The loading amount of MIL-68(Al) in the MIL-68(Al) / SBA-15-COOH composite material is 18.16 wt %.

[0062] The preparation method of the above-mentioned MIL-68(Al) / SBA-15-COOH composite material comprises the following steps:

[0063] (1) Dissolve 2 g of P123 in 7.5 mL of H2O and 60 mL of 2 M HCl solution. Stir continuously until the template P123 is completely dissolved to obtain a clear solution.

[0064] The ratio of the mass of P123 to the volume of dilute hydrochloric acid is 2 g:60 mL;

[0065] To the clear solution, 0.83 g of vinyltrimethoxysilane (VTMO) and 4.0 g of tetraethyl orthosilicate were added, and the mixture was heated and stirred at 40° C. for 24 h. After natural cooling, the reaction product was separated by filtration, washed repeatedly with distilled water and ethanol, filtered, and dried under vacuum at 60° C. for 10 h to obtain a white powder. The template was then removed by Soxhlet extraction to obtain a white powdery solid SBA-15-vinyl;

[0066] The mass ratio of vinyltrimethoxysilane to tetraethyl orthosilicate is 0.82:4;

[0067] The template removal treatment adopts Soxhlet extraction method, and the steps are as follows: 2 g of sample is placed in a Soxhlet extractor, 400 ml of anhydrous ethanol solution is added, and the mixture is treated at 80° C. for 12 hours to obtain SBA-15-vinyl;

[0068] (2) dissolving the white powdery SBA-15-vinyl obtained in step (1) in concentrated nitric acid (200 mL; 12 mol / L), and then subjecting the mixture to a first reflux stirring in air at 80° C. for 13 h. The resulting product was washed with distilled water and ethanol, and then vacuum dried at 60° C. for 10 h to obtain a white powdery solid, SBA-15-COOH.

[0069] The ratio of the mass of the SBA-15-vinyl to the volume of concentrated nitric acid is 2 g:200 mL;

[0070] (3) 0.4 g of the SBA-15-COOH obtained in step (3) was dispersed in 0.9 g of Al(NO3)3·6H2O solution, dried at 90°C for 8 h, and pulverized to obtain a solid;

[0071] The mass ratio of the SBA-15-COOH to the Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution is 4:9;

[0072] (4) The solid obtained in step (3) was mixed with 20 mL of deionized water and 10 mL of an H3BTC-ethanol solution containing 0.053 g of H3BTC, and the mixture was transferred to a round-bottom flask. The mixture was stirred under a second reflux in an air environment at 135° C. for 24 h. The product of the second reflux was slowly cooled to room temperature and centrifuged for 15 min to collect a white solid. Subsequently, the solid was washed with DMF and methanol for multiple times, respectively. The solid was dried under vacuum at 80° C. for 2 h to obtain a white powder MIL-68(Al) / SBA-15-COOH composite material.

[0073] The H3BTC-ethanol solution was prepared by dissolving 0.053 g of H3BTC in 10 mL of ethanol and adding 10 mL of deionized water.

[0074] The mass ratio of the SBA-15-COOH to the H3BTC in the H3BTC-ethanol solution is 4:0.53.

[0075] Figure 1 This is a transmission electron microscope image of the MIL-68(Al) / SBA-15-COOH composite material prepared in Example 1. Figure 1 It can be seen that the image shows regular and orderly light and dark pores, indicating that the composite material has an ordered two-dimensional hexagonal structure.

[0076] Figure 2 The wide-angle XRD patterns of the MIL-68(Al) / SBA-15-COOH composite material and MIL-68(Al) prepared in Example 1 are shown in FIG. Figure 2 It can be seen that the characteristic peaks of the composite material at 2θ = 9.28, 10.0, 15.52, 17.8 and 21.16° are similar to the characteristic peaks of pure MIL-68(Al), indicating that MIL-68(Al) is successfully loaded into the composite material.

[0077] Example 2

[0078] A MIL-68(Al) / SBA-15-COOH composite material was prepared according to the method of Example 1, except that the mass ratio of SBA-15-COOH to Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution was 4:7.

[0079] Example 3

[0080] A MIL-68(Al) / SBA-15-COOH composite material was prepared according to the method of Example 1, except that the mass ratio of SBA-15-COOH to Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution was 4:8.

[0081] Example 4

[0082] A MIL-68(Al) / SBA-15-COOH composite material was prepared according to the method of Example 1, except that the mass ratio of SBA-15-COOH to Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution was 4:10.

[0083] Comparative Example 1

[0084] A composite material was prepared according to the method of Example 1, except that the mass ratio of vinyltrimethoxysilane to tetraethyl orthosilicate was 0.82:2.

[0085] Comparative Example 2

[0086] A composite material was prepared according to the method of Example 1, except that the mass ratio of vinyltrimethoxysilane to tetraethyl orthosilicate was 0.82:6.

[0087] Comparative Example 3

[0088] A MIL-68(Al) / SBA-15 composite material was prepared using mesoporous silica SBA-15 with a particle size of 6-11 nm purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. as a carrier; the preparation steps of the MIL-68(Al) / SBA-15 composite material were as follows:

[0089] (1) 0.4 g of the purchased SBA-15 was dispersed in Al(NO3)3·6H2O solution, dried at 90°C for 8 h, and pulverized to obtain a solid;

[0090] The mass ratio of the SBA-15 to the Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution is 4:9;

[0091] (2) The solid obtained in step (1) was mixed with 20 mL of deionized water and 10 mL of an H3BTC-ethanol solution containing 0.053 g of H3BTC, and the mixture was transferred to a round-bottom flask. The mixture was stirred under a second reflux in an air environment at 135° C. for 24 h. The product of the second reflux was slowly cooled to room temperature and centrifuged for 15 min to collect a white solid. Subsequently, the solid was washed with DMF and methanol for multiple times, respectively. The solid was dried under vacuum at 80° C. for 2 h to obtain a white powder MIL-68(Al) / SBA-15 composite material.

[0092] The H3BTC-ethanol solution was prepared by dissolving 0.053 g of H3BTC in 10 mL of ethanol and adding 10 mL of deionized water.

[0093] The mass ratio of the SBA-15 to the H3BTC in the H3BTC-ethanol solution is 4:0.53.

[0094] The corresponding composite materials in Examples 1 to 4 and Comparative Examples 1 to 3 were used as catalysts to catalyze the reduction of p-nitrophenol to prepare 4-aminophenol. The steps were as follows: 22.5 mL of a 0.09 mM 4-NP solution was mixed with 5 mL of a 0.03 M NaBH4 solution, at which point the solution color changed from light yellow to dark yellow. Subsequently, 20 mg of the catalyst and 12 mL of distilled water were added to the reaction system. During the reaction, samples were taken regularly and monitored using a UV-visible spectrophotometer (wavelength range 250-500 nm) until the solution color faded to colorless, indicating that the 4-NP had been completely reduced to 4-aminophenol (4-AP). The conversion efficiency of 4-NP was calculated based on the relationship between the reaction time and the intensity of the UV absorption peak (usually located at 400 nm).

[0095] The yields of 4-aminophenol and the conversion rates of p-nitrophenol prepared using the corresponding composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 as catalysts were measured by UV-visible spectrophotometer and the results are shown in Table 1.

[0096] The corresponding composite materials of Examples 1 to 4 and Comparative Examples 1 to 3 after the above reaction were recovered and recycled as catalysts. After recycling for 5 times, the yield of 4-aminophenol and the conversion rate of p-nitrophenol prepared are shown in Table 1.

[0097] Table 1 Catalytic performance of corresponding composite materials of Examples 1 to 4 and Comparative Examples 1 to 3

[0098]

[0099] As shown in Table 1, the composite material of Example 1 exhibits good catalytic activity in the reduction reaction of 4-nitrophenol, and its apparent reaction rate (kinetic) constant reaches 0.04 min -1 After five consecutive cycles of experiments, the catalytic performance of the composite material remained stable. This characteristic may be attributed to the strong interaction between MIL-68(Al) and SBA-15-COOH, which effectively inhibited the dissolution or structural collapse of MIL-68(Al) during the reaction.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A MIL-68(Al) / SBA-15-COOH composite material, characterized in that: It comprises a carrier and an active component MIL-68 (Al); the carrier is grafted with the active component; The carrier SBA-15-COOH is prepared from nitric acid and vinyl-functionalized mesoporous silica SBA-15-vinyl; The SBA-15-vinyl is prepared by co-condensing a vinyl functionalization reagent and an inorganic silicon source.

2. The MIL-68(Al) / SBA-15-COOH composite material according to claim 1, characterized in that The MIL-68(Al) / SBA-15-COOH composite material is a mesoporous material with an average pore diameter of 3 to 9 nm.

3. The MIL-68(Al) / SBA-15-COOH composite material according to claim 1, characterized in that The loading amount of MIL-68(Al) in the MIL-68(Al) / SBA-15-COOH composite material is 14 wt% to 23 wt%.

4. The MIL-68(Al) / SBA-15-COOH composite material according to claim 1, characterized in that The vinyl functionalization agent is vinyltrimethoxysilane, and the inorganic silicon source is ethyl orthosilicate.

5. A method for preparing the MIL-68(Al) / SBA-15-COOH composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) mixing polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer P123, water, and dilute hydrochloric acid, and stirring to obtain a clear solution; Adding vinyltrimethoxysilane and tetraethyl orthosilicate to the clear solution, and sequentially performing heating and stirring, a first post-treatment, and a template removal treatment to obtain SBA-15-vinyl; (2) mixing the SBA-15-vinyl obtained in step (1) with concentrated nitric acid, and performing a first reflux stirring and a second post-treatment to obtain SBA-15-COOH; (3) dispersing the SBA-15-COOH obtained in step (2) in an Al(NO3)3·6H2O solution, and drying and pulverizing to obtain a solid; (4) After the solid obtained in step (3) is mixed with water and H3BTC-ethanol solution, a second reflux stirring and a third post-treatment are performed in sequence to obtain a MIL-68(Al) / SBA-15-COOH composite material.

6. The preparation method according to claim 5, characterized in that The temperature of the heating and stirring in the step (1) is 30 to 50° C.; the time of the heating and stirring is 20 to 28 hours.

7. The preparation method according to claim 5, characterized in that The concentration of concentrated nitric acid in step (2) is 10-14 mol / L; the ratio of the mass of SBA-15-vinyl to the volume of concentrated nitric acid is (0.5-4) g:200 mL.

8. The preparation method according to claim 5, characterized in that The mass ratio of SBA-15-COOH to Al(NO3)3·6H2O in the Al(NO3)3·6H2O solution in step (3) is 4:(5-15).

9. The preparation method according to claim 5, characterized in that The mass ratio of SBA-15-COOH in the step (3) to H3BTC in the H3BTC-ethanol solution in the step (4) is 4:(0.2-0.9).

10. Use of the MIL-68(Al) / SBA-15-COOH composite material according to any one of claims 1 to 4 or the MIL-68(Al) / SBA-15-COOH composite material prepared by the preparation method according to any one of claims 5 to 9 in catalyzing the reduction reaction of nitrophenol.

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