Multistage-pore molecular sieve supported cu-based bifunctional catalyst, and preparation method and application thereof
By constructing a Cu-based catalyst supported on a hierarchical porous molecular sieve, the problems of traditional microporous molecular sieves limiting the catalytic conversion of macromolecules and being prone to carbon deposition and deactivation were solved, thus improving the catalytic performance of the efficient synthesis of diphenylmethane from benzene and benzyl alcohol, making it suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGCHUN GOLD RES INST
- Filing Date
- 2024-12-16
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, the reaction of benzene with benzyl chloride to produce diphenylmethane generates HCl gas, which is costly to treat and environmentally unfriendly. Furthermore, the method for synthesizing diphenylmethane from benzene and benzyl alcohol is inefficient, limiting its industrial application. The pore structure of traditional microporous molecular sieves restricts the catalytic conversion of macromolecules and is prone to carbon deposition and deactivation; single-site acid catalytic efficiency is also low.
Multi-level porous molecular sieves are constructed by alkali treatment and ball milling, and Cu precursors are introduced to form Cu-based catalysts supported on multi-level porous molecular sieves. This achieves intracrystalline mesoporous and intercrystalline pore structures, shortens the distance between Cu sites and acid sites, and improves reactant diffusion rate and catalytic efficiency.
The catalyst exhibits improved catalytic performance in the benzylation reaction of benzene and benzyl alcohol, enhanced diffusion efficiency, and simple operation, making it suitable for large-scale industrial applications.
Smart Images
Figure CN119680626B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation and application technology, and in particular to a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve, its preparation method and application. Background Technology
[0002] Diphenylmethane is an important fine chemical. Currently, diphenylmethane is mainly produced by the reaction of benzene and benzyl chloride. This reaction generates HCl gas, which is costly to handle, requires sophisticated reaction equipment, and has adverse environmental impacts. In contrast, the reaction system for synthesizing diphenylmethane from benzene and benzyl alcohol produces water as a byproduct instead of HCl, making it more environmentally friendly. However, this method has lower synthesis efficiency than the benzene-benzyl chloride reaction, severely limiting its industrial application. Therefore, there is an urgent need to develop a highly efficient catalyst for the benzylation reaction of benzene and benzyl alcohol.
[0003] Molecular sieve-based catalysts are important catalytic materials in modern chemical industry. Their large-scale application originated in traditional petrochemical processes and has gradually played a crucial role in the generation of basic and fine chemicals. For traditional microporous molecular sieves, their narrow pore structure restricts the catalytic conversion of macromolecules, and the catalyst is prone to carbon deposition and deactivation during rapid carbonization. Preparing hierarchical porous molecular sieves can alleviate these problems. However, the catalytic efficiency of a single molecular sieve acid site is relatively low, necessitating metal modification of the molecular sieve to further improve its catalytic efficiency. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve. This method first uses an alkaline medium to trim the pores of a microporous molecular sieve, constructing a permeable hierarchical porous molecular sieve as a substrate for supporting Cu sites. Then, ball milling is performed, and under mechanical force, the Si-O-Si and Si-O-Al sections of the molecular sieve break down, generating intercrystalline pores and defect sites. Simultaneously, a Cu-containing precursor is introduced during ball milling. The interaction between the Cu precursor and the defect sites of the molecular sieve enables the one-step creation of the Cu-based catalyst supported on the hierarchical porous molecular sieve. The mechanical force facilitates the dispersion of the Cu precursor, and the introduced intracrystalline and intercrystalline pores significantly shorten the distance between Cu sites and acid sites, fully leveraging their synergistic effect. Furthermore, the permeable hierarchical porous structure significantly improves the diffusion rate of reactants and products. The resulting Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve exhibits high catalytic performance in the catalytic reaction of benzene and benzyl alcohol.
[0005] The catalyst preparation method provided by this invention is simple, the pore structure is adjustable, and it is suitable for industrial production.
[0006] To achieve the above objectives, the present invention provides a method for preparing a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve, comprising the following steps:
[0007] S1. Immerse the microporous molecular sieve sample in an alkaline medium solution at a temperature of 60-90℃ for 15-90 min of alkali treatment; then, centrifuge or filter and wash the sample until neutral, dry it at 80-140℃ for 6-48 h, and then calcine it at 450-700℃ for 1-9 h.
[0008] S2, ammonium exchange is performed on the sample treated in step S1 using NH4NO3 or NH4Cl solution, and then calcination is performed to prepare a hierarchical porous molecular sieve.
[0009] S3. Place the multi-level porous molecular sieve obtained in step S2 into a ball mill jar, add deionized water, and ball mill at 100-500 rpm for 3-15 hours; then add a Cu-containing precursor solution and continue ball milling at 100-500 rpm for 2-15 hours.
[0010] S4. The sample after ball milling is first subjected to rotary evaporation to remove the solvent, then dried in an oven at 80-140℃ for 6-48 hours, and then placed in a muffle furnace and calcined at 450-700℃ for 1-5 hours to finally obtain a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve.
[0011] In the embodiments of this application, the present invention first introduces a mesoporous hierarchical molecular sieve as a substrate for supporting Cu through alkali treatment. Then, the molecular sieve is ball-milled to introduce an intercrystalline pore structure. Simultaneously, a copper precursor is added during the treatment process, and the preparation of a Cu-based catalyst supported on the hierarchical molecular sieve is achieved through high-temperature transformation and other methods. Under the synergistic effect of the acid sites of the molecular sieve and the active sites of the supported Cu, the alkylation reaction of benzene and benzyl alcohol can be efficiently synthesized into diphenylmethane.
[0012] Furthermore, in step S3, the Cu-containing precursor is one of copper nitrate, copper chloride, cuprous nitrate, cuprous chloride, and copper acetate.
[0013] Furthermore, in step S2, the temperature conditions for ammonium exchange are 60-90°C, the exchange time is 15-90 min, and the number of exchanges is 1-5 times.
[0014] Furthermore, in step S1, the alkaline medium solution is a mixture of one or more of NaOH, KOH, ammonia, and Na2CO3; the concentration of the alkaline medium is 0.05–0.5 mol / L, and the volume ratio of the alkaline medium solution to the mass ratio of the microporous molecular sieve is (10–50) ml: 1 g.
[0015] Furthermore, in step S4, the rotary evaporation temperature is 40–80°C.
[0016] This invention also provides a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve, prepared by the aforementioned method. The hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst comprises a hierarchical porous molecular sieve and a supported Cu component. The main component of the hierarchical porous molecular sieve is an aluminosilicate molecular sieve, which contains micropores, intracrystalline mesopores, and intercrystalline pores.
[0017] Furthermore, the topology of the Cu-based bifunctional catalyst supported on the hierarchical porous molecular sieve is MFI type or BEA type.
[0018] Furthermore, the silicon-to-aluminum atomic ratio of the Cu-based bifunctional catalyst supported on the hierarchical porous molecular sieve is Si / Al = 15 to 50.
[0019] The aforementioned hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst can be used to prepare diphenylmethane, specifically including the following steps: adding benzene and the hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst to a reactor, preheating to the reaction temperature, and then adding benzyl alcohol, where benzene and benzyl alcohol undergo a benzylation reaction to generate diphenylmethane.
[0020] Furthermore, the reaction temperature is 60-100℃, the reaction pressure is 0.1-0.5MPa, and the ratio of benzene, benzyl alcohol and catalyst is benzene:benzyl alcohol:catalyst = (20-50)ml:(0.5-1)ml:(0.1-0.5)g.
[0021] The beneficial effects of this invention are:
[0022] 1. The method for preparing a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve provided by this invention constructs intracrystalline mesoporous and intercrystalline pore structures in the molecular sieve through a bridging strategy of alkali treatment and ball milling. This improves the diffusion of reactants, intermediates, and products from the dual perspectives of reducing diffusion paths and expanding diffusion channels, particularly benefiting the diffusion efficiency of macromolecular organic compounds. Ball milling enables the simultaneous construction of intercrystalline pore structures and Cu active sites; the defect sites generated during ball milling provide an ideal environment for the loading of Cu metal, achieving efficient placement and anchoring of Cu sites; simultaneously, the introduction of hierarchical pores shortens the distance between Cu active sites and the acid sites of the molecular sieve, facilitating the synergistic effect of both, resulting in a highly efficient Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve for the benzylation reaction of benzene and benzyl alcohol.
[0023] 2. The hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst prepared by this invention comprises a hierarchical porous molecular sieve support and supported active metal Cu sites. Through an alkali treatment-ball milling bridging strategy, the catalyst achieves a hierarchical pore structure with both intracrystalline and intercrystalline mesoporous channels. Cu active sites are simultaneously constructed while introducing the intercrystalline pore structure. The catalyst exhibits high Cu site dispersion and high catalytic performance in the benzylation reaction of benzene and benzyl alcohol. The hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst provided by this invention has simple operation steps and production equipment, low preparation cost, and is suitable for large-scale industrial application. Attached Figure Description
[0024] Figure 1 The performance results of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 for the benzylation reaction of benzene and benzyl alcohol are shown.
[0025] Figure 2 The XRD patterns of the catalysts prepared in Examples 1-2 and Comparative Examples 1-3 are shown.
[0026] Figure 3 This is a SEM image of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve prepared in Example 1.
[0027] Figure 4 This is a SEM image of the sample from Comparative Example 1. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0029] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.
[0030] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0031] The narrow pore structure of traditional microporous molecular sieves restricts the catalytic conversion process of macromolecules, and the catalyst is prone to carbon deposition and deactivation during rapid carbon deposition. The catalytic efficiency of a single molecular sieve acid site is also relatively low.
[0032] This invention provides a highly efficient hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst for the benzylation reaction of benzene and benzyl alcohol. A mesoporous hierarchical molecular sieve is introduced as a substrate for supporting Cu active sites through alkali treatment. The molecular sieve is then ball-milled, with a copper precursor added during the process. The catalyst is then prepared through high-temperature transformation. The synergistic effect of the acid sites on the molecular sieve and the supported Cu active sites enables the efficient synthesis of diphenylmethane from the alkylation reaction of benzene and benzyl alcohol.
[0033] On one hand, the present invention provides a method for preparing a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve, comprising the following steps:
[0034] S1. Immerse the microporous molecular sieve sample in an alkaline medium solution at a temperature of 60-90℃ for 15-90 min of alkali treatment; then, centrifuge or filter and wash the sample until neutral, dry it at 80-140℃ for 6-48 h, and then calcine it at 450-700℃ for 1-9 h.
[0035] The alkaline medium solution is a mixture of one or more of NaOH, KOH, ammonia, and Na2CO3. The concentration of the alkaline medium is 0.05–0.5 mol / L, and the volume ratio of the alkaline medium solution to the mass ratio of the microporous molecular sieve is (10–50) ml: 1 g.
[0036] S2, ammonium exchange is performed on the sample treated in step S1 using NH4NO3 or NH4Cl solution, and then calcination is performed to prepare a hierarchical porous molecular sieve.
[0037] The ammonium exchange temperature is 60–90℃, the exchange time is 15–90 min, and the number of exchanges is 1–5.
[0038] S3. Place the multi-level porous molecular sieve obtained in step S2 into a ball mill jar, add deionized water, and ball mill at 100-500 rpm for 3-15 hours; then add a Cu-containing precursor solution and continue ball milling at 100-500 rpm for 2-15 hours.
[0039] The Cu-containing precursor is one of copper nitrate, copper chloride, cuprous nitrate, cuprous chloride, or copper acetate.
[0040] S4. The sample after ball milling is first subjected to rotary evaporation to remove the solvent, then dried in an oven at 80-140℃ for 6-48 hours, and then placed in a muffle furnace and calcined at 450-700℃ for 1-5 hours to finally obtain a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve.
[0041] The temperature for rotary evaporation is 40–80℃.
[0042] In the embodiments of this application, the microporous molecular sieve is first subjected to alkali treatment to introduce mesopores, and then subjected to ammonium exchange calcination to obtain a molecular sieve containing intracrystalline mesoporous structures. Then, a one-step ball milling method is used to introduce intercrystalline pores to obtain a hierarchical porous molecular sieve, thereby simultaneously realizing the construction of intercrystalline pore structures and the construction of active sites for metallic Cu.
[0043] Secondly, the present invention also provides a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve, which is prepared by the aforementioned preparation method. The hierarchical porous molecular sieve supported Cu-based bifunctional catalyst includes a hierarchical porous molecular sieve and supported Cu active sites. The main component of the hierarchical porous molecular sieve is aluminosilicate molecular sieve, which contains micropores, intracrystalline mesopores and intercrystalline pores.
[0044] Among them, the topology of the Cu-based bifunctional catalyst supported on the hierarchical porous molecular sieve is MFI type or BEA type.
[0045] The silicon-to-aluminum atomic ratio of the Cu-based bifunctional catalyst supported on hierarchical porous molecular sieves is Si / Al = 15–50.
[0046] This invention marks the first successful preparation of a hierarchical porous molecular sieve-supported metal catalyst with both intracrystalline and intercrystalline mesopores via a ball milling-alkali treatment bridging strategy. The catalyst is characterized by a permeable hierarchical channel structure encompassing intercrystalline pores, intracrystalline mesopores, and micropores, and exhibits high catalytic performance in macromolecular catalytic conversion reactions through the synergistic effect of the supported Cu active sites and the molecular sieve acid sites.
[0047] The aforementioned hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst can be used to prepare diphenylmethane, specifically including the following steps: adding benzene and the hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst to a reactor, preheating to the reaction temperature, and then adding benzyl alcohol, where benzene and benzyl alcohol undergo a benzylation reaction to generate diphenylmethane.
[0048] The reaction temperature is 60–100℃ and the reaction pressure is 0.1–0.5 MPa.
[0049] The ratio of benzene, benzyl alcohol and catalyst is benzene:benzyl alcohol:catalyst = (20~50)ml:(0.5~1)ml:(0.1~0.5)g.
[0050] The preparation method of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve provided by the present invention will be described below with reference to specific embodiments. Unless otherwise specified, the raw materials and reagents used in the embodiments of this application were purchased commercially.
[0051] Example 1
[0052] This embodiment provides a method for preparing diphenylmethane by benzylation of benzene and benzyl alcohol, including the following steps:
[0053] 1) Prepare 0.2M sodium hydroxide, take 450ml into a polypropylene flask, place it in a water bath and heat to 70℃, then add 15g of HZSM-5 molecular sieve (Si / Al=35), stir for 30min, the solid-liquid ratio is 1 / 30; wash the reaction product with deionized water until neutral, dry at 110℃ for 12h, and calcine at 550℃ for 3h.
[0054] 2) The obtained molecular sieve was then added to a 0.6M ammonium chloride solution with a solid-liquid ratio of 1 / 20. The mixture was magnetically stirred at 80°C for 2 hours and the reaction was repeated 3 times. The reaction product was then filtered and washed with deionized water, dried at 120°C for 8 hours, and calcined at 550°C for 3 hours. This product was then recorded as a multi-level porous molecular sieve.
[0055] 3) Place 10g of multi-level porous molecular sieve, 15ml of deionized water and 50g of zirconia balls in a ball mill jar and treat at 250rpm for 6h. Then add 15ml of aqueous solution containing 4.18g of copper nitrate and continue treatment at 250rpm for 12h.
[0056] 4) The sample was transferred to a rotary evaporator to evaporate the solvent, then dried in an oven at 120°C for 8 hours, and then calcined in a muffle furnace at 550°C for 3 hours to obtain catalyst A (a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve).
[0057] 5) Take 0.15 g of the above-mentioned hierarchical porous molecular sieve catalyst into the reaction apparatus, then add 35 ml of benzene, stir at 80 °C for 1 h, and add 0.5 ml of benzyl alcohol to the reaction apparatus to start the reaction. After 2 h of reaction, take a sample for gas chromatography analysis, use an HP-5 capillary column for product separation, and use an FID detector for detection. The reaction performance results are shown in the figure. Figure 1 .
[0058] Example 2
[0059] Example 2 provides a method for preparing diphenylmethane by benzylation of benzene and benzyl alcohol, comprising the following steps:
[0060] 1) Prepare 0.3M sodium hydroxide by taking 450ml into a polypropylene flask and heating it to 70℃ in a water bath. Then add 15g of HZSM-5 molecular sieve (Si / Al=35), stir for 30min, and the solid-liquid ratio is 1 / 30. Wash the reaction product with deionized water until neutral, dry at 110℃ for 12h, and calcine at 550℃ for 3h.
[0061] 2) The obtained molecular sieve was then added to a 0.8M ammonium chloride solution with a solid-liquid ratio of 1 / 20. The mixture was magnetically stirred at 80°C for 2 hours and the reaction was repeated twice. The reaction product was then filtered and washed with deionized water, dried at 120°C for 8 hours, and calcined at 550°C for 3 hours. This product was then recorded as a multi-level porous molecular sieve.
[0062] 3) Place 10g of multi-level porous molecular sieve, 15ml of deionized water and 50g of zirconia balls in a ball mill jar and treat at 230rpm for 5h. Then add 15ml of aqueous solution containing 4.18g of copper nitrate and continue to treat at 230rpm for 15h.
[0063] 4) The sample was transferred to a rotary evaporator to evaporate the solvent, then dried in an oven at 110°C for 8 hours, and then calcined in a muffle furnace at 550°C for 3 hours to obtain catalyst B.
[0064] 5) Take 0.15 g of the above-mentioned hierarchical porous molecular sieve catalyst into the reaction apparatus, then add 35 ml of benzene, stir at 80 °C for 1 h, and add 0.5 ml of benzyl alcohol to the reaction apparatus to start the reaction. After 2 h of reaction, take a sample for gas chromatography analysis, use an HP-5 capillary column for product separation, and use an FID detector for detection. The reaction performance results are shown in the figure. Figure 1 .
[0065] Example 3
[0066] Example 3 provides a method for preparing diphenylmethane by benzylation of benzene and benzyl alcohol, comprising the following steps:
[0067] 1) Prepare 0.2M sodium hydroxide by taking 450ml into a polypropylene flask and heating it to 70℃ in a water bath. Then add 15g of HZSM-5 molecular sieve (Si / Al=27.5) and stir for 30min. The solid-liquid ratio is 1 / 30. Wash the reaction product with deionized water until neutral, dry it at 110℃ for 12h, and calcine it at 550℃ for 3h.
[0068] 2) The obtained molecular sieve was then added to a 0.6M ammonium chloride solution with a solid-liquid ratio of 1 / 20. The mixture was magnetically stirred at 80°C for 2 hours and the reaction was repeated twice. The reaction product was then filtered and washed with deionized water, dried at 100°C for 8 hours, and calcined at 550°C for 3 hours. This product was then recorded as a multi-level porous molecular sieve.
[0069] 3) Place 10g of multi-level porous molecular sieve, 15ml of deionized water and 50g of zirconia balls in a ball mill jar and treat at 200rpm for 5h. Then add 15ml of aqueous solution containing 4.18g of copper nitrate and continue to treat at 200rpm for 5h.
[0070] 4) Transfer the sample to a rotary evaporator to evaporate the solvent, then dry it in an oven at 100°C for 8 hours, and then calcine it in a muffle furnace at 550°C for 3 hours to obtain catalyst C.
[0071] 5) Take 0.15 g of the above-mentioned hierarchical porous molecular sieve catalyst into the reaction apparatus, then add 35 ml of benzene, stir at 80 °C for 1 h, and add 0.5 ml of benzyl alcohol to the reaction apparatus to start the reaction. After 2 h of reaction, take a sample for gas chromatography analysis, use an HP-5 capillary column for product separation, and use an FID detector for detection. The reaction performance results are shown in the figure. Figure 1 .
[0072] Comparative Example 1
[0073] Comparative Example 1 provides a method for preparing diphenylmethane by benzylation of benzene and benzyl alcohol. The main difference from Example 1 is that a microporous HZSM-5 molecular sieve (Si / Al = 35) is used. The specific process is as follows:
[0074] 0.15 g of microporous HZSM-5 molecular sieve (Si / Al = 35) was placed in the reaction apparatus, followed by the addition of 35 ml of benzene. The mixture was stirred at 80 °C for 1 h. Then, 0.5 ml of benzyl alcohol was added to the reaction apparatus to initiate the reaction. After 2 h of reaction, samples were taken for gas chromatography analysis. Product separation was performed using an HP-5 capillary column, and detection was performed using an FID detector. The reaction performance results are shown in the figure. Figure 1 .
[0075] Comparative Example 2
[0076] Comparative Example 2 provides a method for preparing diphenylmethane by benzylation of benzene and benzyl alcohol. The main difference from Example 1 is that step 3) Cu loading is not performed. The specific process is as follows:
[0077] 1) Prepare 0.2M sodium hydroxide solution. Take 450 ml of the solution into a polypropylene flask and heat it to 70℃ in a water bath. Add 15 g of HZSM-5 molecular sieve (Si / Al = 35) and stir for 30 min, with a solid-liquid ratio of 1 / 30. Wash the reaction product with deionized water until neutral, dry at 110℃ for 12 h, and calcine at 550℃ for 2 h. Then add the obtained molecular sieve to a 0.6M ammonium chloride solution, with a solid-liquid ratio of 1 / 20, and stir magnetically at 80℃ for 2 h. Repeat the exchange process 3 times. Then filter and wash the reaction product with deionized water, dry at 120℃ for 8 h, and calcine at 550℃ for 3 h.
[0078] 2) Place 15g of the above-mentioned hierarchical porous molecular sieve, 30g of deionized water and 75g of zirconia balls in a ball mill jar and treat at 300rpm for 18h. Dry the treated sample in an oven at 100℃ for 8h, and then calcine it in a muffle furnace at 550℃ for 3h. This sample is designated as hierarchical porous molecular sieve catalyst A2.
[0079] 3) Take 0.15 g of the above-mentioned hierarchical porous molecular sieve catalyst A2 into the reaction apparatus, then add 35 ml of benzene, stir at 80 °C for 1 h, and add 0.5 ml of benzyl alcohol to the reaction apparatus to start the reaction. After 2 h of reaction, take a sample for gas chromatography analysis, use an HP-5 capillary column for product separation, and use an FID detector for detection. The reaction performance results are shown in the figure. Figure 1 .
[0080] Comparative Example 3
[0081] Comparative Example 3 provides a method for preparing diphenylmethane by benzylation of benzene and benzyl alcohol. The main difference from Example 1 is that steps 1) and 2) are not performed. The specific process is as follows:
[0082] 1) Add 10g of HZSM-5 molecular sieve (Si / Al=35) to 30ml of aqueous solution containing 4.18g of copper nitrate, stir at room temperature at 250rpm for 12h, transfer the sample to a rotary evaporator to evaporate the solvent, dry it in an oven at 120℃ for 8h, and then calcine it in a muffle furnace at 550℃ for 3h to obtain catalyst A3.
[0083] 2) Take 0.15 g of the above catalyst A3 into the reaction apparatus, then add 35 ml of benzene, stir at 80 °C for 1 h, and add 0.5 ml of benzyl alcohol to the reaction apparatus to start the reaction. After 2 h of reaction, take a sample for gas chromatography analysis. Use an HP-5 capillary column for product separation and an FID detector for detection. The reaction performance results are shown in the figure. Figure 1 .
[0084] like Figure 1 As shown, comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the Cu-based catalyst supported on the hierarchical porous molecular sieve has higher catalytic performance, which is significantly higher than that of the catalysts in Comparative Examples 1-2 without metal Cu. This proves that the supported metal Cu sites are the active centers for catalyzing the benzylation reaction of benzene and benzyl alcohol.
[0085] Comparing Example 1 and Comparative Example 3, it can be seen that the catalytic performance of the catalyst is significantly reduced when the alkali treatment and ball milling steps are missing, proving that intracrystalline mesopores and intercrystalline pores are beneficial to improving the diffusion of organic matter and promoting the synergistic effect between Cu sites and molecular sieve acid sites.
[0086] Figure 2 The XRD patterns of the catalysts prepared in Examples 1-2 and Comparative Examples 1-3 are shown. It can be seen that after alkali treatment, ball milling, and the introduction of Cu active sites, the diffraction peak intensities of the molecular sieves did not change significantly, indicating that the molecular sieves maintained their crystalline structure.
[0087] Figure 3The image shows an SEM image of the catalyst prepared in Example 1. It can be seen that after alkali treatment and ball milling, the catalyst has a rough surface and smaller particle size, demonstrating that alkali etching and ball milling resulted in the formation of obvious intracrystalline mesopores and intercrystalline pore structures formed by the accumulation of small particles.
[0088] Figure 4 The image shows a SEM image of the catalyst prepared in Comparative Example 1. It can be seen that the microporous molecular sieve has a smooth surface and a larger particle size, and no obvious pore structure was observed, further proving that the intracrystalline mesoporous and intercrystalline pore structures in the catalyst sample of Example 1 were constructed through an alkali treatment-ball milling bridging strategy.
[0089] Experiments show that Cu-containing precursors can also be one of copper chloride, cuprous nitrate, cuprous chloride, or copper acetate.
[0090] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims
1. The application of a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve, characterized in that, The hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst is used to prepare diphenylmethane, specifically including the following steps: adding benzene and the hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst to a reactor, preheating to the reaction temperature, and then adding benzyl alcohol; benzene and benzyl alcohol undergo a benzylation reaction to generate diphenylmethane; the preparation method of the hierarchical porous molecular sieve-supported Cu-based bifunctional catalyst includes the following steps: S1. The microporous molecular sieve sample is immersed in an alkaline medium solution at a temperature of 60-90℃ for 15-90 min for alkali treatment; then, the sample is centrifuged or filtered and washed until neutral, dried at 80-140℃ for 6-48 h, and then calcined at 450-700℃ for 1-9 h; wherein, the microporous molecular sieve is HZSM-5 molecular sieve, and the Si / Al ratio is 35 or 27.5; S2, ammonium exchange is performed on the sample treated in step S1 using NH4NO3 or NH4Cl solution, and then calcination is performed to prepare a hierarchical porous molecular sieve. S3. Place the multi-level porous molecular sieve obtained in step S2 into a ball mill jar, add deionized water, and ball mill at 100~500 rpm for 3~15 h; then add Cu-containing precursor solution and continue ball milling at 100~500 rpm for 2~15 h. S4. The sample after ball milling is first subjected to rotary evaporation to remove the solvent, then dried in an oven at 80~140℃ for 6~48 h, and then placed in a muffle furnace and calcined at 450~700℃ for 1~5 h to finally obtain a Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve.
2. The application of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve according to claim 1, characterized in that, The reaction temperature is 60-100℃, the reaction pressure is 0.1-0.5 MPa, and the ratio of benzene, benzyl alcohol and catalyst is benzene:benzyl alcohol:catalyst = (20-50) ml: (0.5-1) ml: (0.1-0.5) g.
3. The application of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve according to claim 1, characterized in that: In step S3, the Cu-containing precursor is one of copper nitrate, copper chloride, cuprous nitrate, cuprous chloride, and copper acetate.
4. The application of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve according to claim 1, characterized in that: In step S2, the temperature conditions for ammonium exchange are 60~90℃, the exchange time is 15-90min, and the number of exchanges is 1~5 times.
5. The application of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve according to claim 1, characterized in that: In step S1, the alkaline medium solution is a mixture of one or more of NaOH, KOH, ammonia, and Na2CO3; the concentration of the alkaline medium is 0.05~0.5mol / L, and the volume ratio of the alkaline medium solution to the mass ratio of the microporous molecular sieve is (10~50)ml:1g.
6. The application of the Cu-based bifunctional catalyst supported on a hierarchical porous molecular sieve according to claim 1, characterized in that: In step S4, the rotary evaporation temperature is 40~80℃.