Preparation method of metal heterogeneous catalyst for dehydrogenation coupling reaction
By introducing a dispersant and a silica support into the catalyst, the size and dispersion of metal nanoparticles are regulated, and the problems of existing catalyst recovery difficulties and uneven dispersion are solved, and a silicon dioxide-supported copper metal nanoparticle heterogeneous catalyst that efficiently catalyzes the dehydrogenation coupling reaction is achieved.
Patent Information
- Application Number
- CN202411902744.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-05-06
AI Technical Summary
The existing homogeneous metal catalysts have problems such as difficulty in recovering and easy agglomeration in catalytic dehydrogenation coupling reactions, and the dispersion degree of heterogeneous catalysts is uneven and lyophilic, which affects the catalytic activity and rate.
By introducing a dispersant and a silica support, the nanosize and dispersion of metal nanoparticles are regulated, and a silicon dioxide-supported copper metal nanoparticles heterogeneous catalyst is prepared to improve its lyophilicity and dispersion.
The high dispersion of metal nanoparticles, high catalytic activity and easy recovery are achieved, and the catalytic performance and cycle stability of the catalyst are significantly improved.
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Figure CN119926400A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of industrial catalyst preparation and relates to a method for preparing a metal heterogeneous catalyst for catalytic dehydrogenation coupling. Background Art
[0002] Silyl ethers are a class of organosilicon compounds with silicon-oxygen bonds and alkyl oxide functional groups, and are widely used in the chemical, pharmaceutical, aerospace and other fields. The preparation of silyl ethers by catalytic dehydrogenative coupling of silane and alcohol is a green and economical preparation method. Among them, metal catalysts are currently the most commonly used catalysts for the dehydrogenative coupling reaction of silane and alcohol. However, homogeneous metal catalysts have disadvantages such as difficulty in recycling and easy agglomeration ( Inorganic Chemistry , 2019, 58, 1201-1207.). Heterogeneous catalysts have the advantage of being easy to separate and can solve the problems existing in the use of homogeneous catalysts. The nanoporous silver np-Ag catalyst developed by Professor Zhang Xiaomei of Shandong University ( Catalysis Communications , 2014, 53, 53-56.) and the nanoporous gold catalyst AuNPore(Ag) synthesized by Professor Naoki Asao ( Chemistry-A European Journal , 2018, 24 (59), 15777-15780), all showed high product yields. The supported metal nanocatalyst improves the atomic utilization of the metal due to the dispersing effect of the carrier, making the metal particle size smaller and the exposed active sites correspondingly increased, thereby having excellent dehydrogenation coupling catalytic performance. However, the metal nanoparticles are easy to agglomerate and the metal particles are easy to fall off from the carrier, affecting their activity and cyclic stability. The dispersion of the metal nanoparticles in the supported catalyst is uneven. In addition, the affinity of the multiphase supported catalyst with the reaction solution is not high, which easily hinders the adsorption and desorption process during the catalytic process, reducing the catalytic activity and rate. Professor Cao Yong of Xiamen University and his collaborators greatly improved the activity of the Pd / C catalyst by increasing the hydrophobicity of the carbon carrier, which is speculated to be related to improving the dispersion of the catalyst in the system ( ACS Catalysis , 2017, 7 (3), 1720-1727). Therefore, in the field of heterogeneous catalyst preparation for catalytic dehydrogenation coupling reactions, finding a suitable method to optimize the structure and properties of the catalyst has important research significance and application value for improving the catalytic activity and rate of the catalyst and catalyzing the dehydrogenation coupling reaction. Summary of the Invention
[0003] In response to the shortcomings of the existing technology, the present invention proposes a metal heterogeneous catalyst for catalyzing dehydrogenation coupling reactions. By introducing and modifying a dispersant and acting as a silica carrier, the lyophilicity of the heterogeneous catalyst is improved, the nanometer size and dispersion of the metal nanoparticles are regulated, and a silica-supported copper metal nanoparticle heterogeneous catalyst with high dispersion of the metal nanoparticles, high catalytic activity for the dehydrogenation coupling reaction, and easy recovery is achieved.
[0004] In order to achieve the above objectives, the present invention is implemented through the following technical solutions.
[0005] The method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction of the present invention comprises the following steps.
[0006] S1. Dissolve the metal nanoparticle precursor in ethanol, add ammonia water dropwise, and sonicate for 10-30 minutes. Then place in an ice-water bath at about 5°C and stir for 1-3 hours before use.
[0007] S2. Slowly drop the dispersant dissolved in ethanol into the solution obtained in step S1, stir evenly, then slowly drop the silicon source of silica precursor, and continue stirring in an ice water bath at about 5° C. for 5-12 hours before use.
[0008] S3. Prefreeze the sodium borohydride (NaBH4) aqueous solution for 1-3 h, then slowly add it dropwise to the solution obtained in step S2 and stir to react for 12-30 h.
[0009] S4. The mixed solution in step S3 is filtered and washed with water to obtain a solid product, which is freeze-dried to obtain a metal heterogeneous catalyst.
[0010] Furthermore, the metal nano-ion precursor in step S1 includes one or more of palladium chloride, ferric chloride, copper chloride, nickel chloride and cobalt chloride, and the concentration of the metal nano-ion precursor dissolved in ethanol is 1-10 g / L.
[0011] Furthermore, the dispersant described in step S2 can be one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, sodium dodecyl sulfate and sodium dodecylbenzenesulfonate; the mass ratio of the metal nanoparticle precursor to the dispersant is 1:1~10, and the concentration of the dispersant dissolved in ethanol is 1-20 g / L.
[0012] Furthermore, the silicon source in step S3 is one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, silica sol or silicic acid; the molar ratio of the silicon source to the metal precursor is 1:0.2-3, and the volume ratio of ethyl orthosilicate to ammonia water is 1:1-5.
[0013] Furthermore, the molar ratio of the metal nanoparticle precursor and NaBH4 in step S3 is 1:1-5, and the concentration of NaBH4 dissolved in water is 1-5 g / L.
[0014] The metal heterogeneous catalyst described in the present invention is a silica-supported metal heterogeneous catalyst, including one or more metal heterogeneous catalysts selected from the group consisting of silica-supported palladium, copper, iron, nickel, cobalt and other metal nanoparticles.
[0015] The invention discloses an application of a metal heterogeneous catalyst for dehydrogenation coupling reaction in a silane-alcohol dehydrogenation coupling reaction, wherein the hydrogen-containing silane-alcohol is brought into contact with the catalyst to cause a dehydrogenation coupling reaction to produce different types of silyl ethers.
[0016] Furthermore, the alcohol in the silane-alcohol dehydrogenation coupling reaction serves as a substrate and a solvent, and the molar ratio of the hydrosilane to the alcohol in the hydrosilane-alcohol dehydrogenation coupling reaction is 1:10-50.
[0017] Furthermore, the type of the hydrosilane in the silane-alcohol dehydrogenation coupling reaction is one or more of phenylsilane, diphenylsilane, and dimethylphenylsilane; the type of the alcohol is one or more of methanol, ethanol, n-butanol, and isopropanol.
[0018] Furthermore, in the silane-alcohol dehydrogenation coupling reaction, the catalyst is in contact with the hydrosilane and the alcohol at a temperature of 30-80° C., and a stirring speed of 150-600 rpm.
[0019] The beneficial effects of the present invention are as follows: the metal heterogeneous catalyst prepared by the present invention is used to efficiently catalyze the dehydrogenative coupling of hydrosilanes and alcohols to prepare silyl ethers, using metal nanoparticles (copper, palladium, iron, nickel and cobalt, etc.) as active sites, and utilizing the effects of dispersants and carriers to change the hydrophilicity and hydrophobicity of the catalyst carrier surface and the size of the metal particles to improve atomic utilization and reaction active sites, and improve the affinity of the catalyst for alcohols. In addition, the positive charge present in the dispersant can further attract activated silane molecules, which is also an excellent method for improving the catalytic dehydrogenative coupling of silanes. The present invention simplifies the preparation process, improves catalyst performance and increases commercial potential, and has broad application prospects in the industrial catalytic dehydrogenative coupling of hydrosilanes and alcohols. Silica-supported copper metal nanoparticle heterogeneous catalyst BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a transmission electron microscope image of the silica-supported copper metal nanoparticle heterogeneous catalyst (Cu / CTAB-SiO2) with added dispersant obtained in Example 1 of the present invention.
[0021] Figure 2This is a transmission electron microscope image of the silica-supported copper metal nanoparticle heterogeneous catalyst (Cu / SiO2) obtained in Comparative Example 1 of the present invention without adding a dispersant.
[0022] Figure 3 Schematic diagram of the contact angle of the silica-supported copper metal nanoparticle heterogeneous catalyst (Cu / CTAB-SiO2) with added dispersant obtained in Example 1 of the present invention.
[0023] Figure 4 Schematic diagram of the contact angle of the silica-supported copper metal nanoparticle heterogeneous catalyst (Cu / SiO2) obtained in Comparative Example 1 of the present invention without adding a dispersant. DETAILED DESCRIPTION
[0024] The present invention will be further described below with reference to specific examples. It should be understood that the examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Example 1
[0025] A method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction comprises the following steps.
[0026] S1. Dissolve 0.1 g of copper chloride dihydrate in 60 mL of ethanol, add 0.2 mL of ammonia water dropwise, sonicate for 10 minutes, and place in an ice-water bath and stir for 1 hour.
[0027] S2. Dissolve 0.3 g of hexadecyltrimethylammonium bromide (CTAB) in 30 mL of ethanol and slowly add it dropwise to the above mixed solution.
[0028] S3. Slowly add 0.43 mL of ethyl orthosilicate to the mixed solution in S2, and finally continue stirring in an ice-water bath for 5 h.
[0029] S4. Prefreeze 20 mL (2.5 mg / mL) of NaBH4 solution for 1 h, then slowly add it dropwise to the above mixed solution and stir for 12 h.
[0030] S5. The mixed solution was washed three times with deionized water and then filtered, placed in a refrigerator for 5 h, and finally placed in a freeze dryer for 20 h to obtain a dried silica-supported copper metal nanoparticles heterogeneous catalyst (Cu / CTAB-SiO2). Example 2
[0031] A method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction comprises the following steps.
[0032] S1. Dissolve 0.15 g of copper chloride dihydrate in 80 mL of ethanol, add 0.3 mL of ammonia water dropwise, sonicate for 10 minutes, and place in an ice-water bath and stir for 1 hour.
[0033] S2. Dissolve 0.5 g of CTAB in 30 mL of ethanol and slowly add it dropwise to the above mixed solution.
[0034] S3. Slowly add 0.6 mL of ethyl orthosilicate to the mixed solution in S2, and finally continue stirring in an ice-water bath for 6 h.
[0035] S4. Prefreeze 20 mL (2.5 mg / mL) of NaBH4 solution for 1 h, then slowly add it dropwise to the above mixed solution and stir for 12 h.
[0036] S5. The mixed solution was washed three times with deionized water and then filtered, placed in a refrigerator for 5 h, and finally placed in a freeze dryer for 20 h to obtain a dried silica-supported copper metal nanoparticle heterogeneous catalyst (Cu / CTAB-SiO2). Example 3
[0037] A method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction comprises the following steps.
[0038] S1. Dissolve 0.2 g of copper chloride dihydrate in 100 mL of ethanol, add 0.4 mL of ammonia water dropwise, sonicate for 10 minutes, and then place in an ice-water bath and stir for 1 hour.
[0039] S2. Dissolve 0.8 g of CTAB in 50 mL of ethanol and slowly add it dropwise to the above mixed solution.
[0040] S3. Slowly add 0.8 mL of ethyl orthosilicate to the mixed solution in S2, and finally continue stirring in an ice-water bath for 6 h.
[0041] S4. Prefreeze 20 mL (3 mg / mL) NaBH4 solution for 1 h, then slowly add it dropwise to the above mixed solution and stir for 12 h.
[0042] S5. The mixed solution was washed three times with deionized water and then filtered, placed in a refrigerator for 5 h, and finally placed in a freeze dryer for 20 h to obtain a dried silica-supported copper metal nanoparticle heterogeneous catalyst (Cu / CTAB-SiO2).
[0043] In order to test the morphology and structure of the catalyst, the present invention adopts transmission electron microscopy technology to observe and analyze its structure.
[0044] In order to test the hydrophilicity and hydrophobicity of the catalyst, water was used as the test solvent and the contact angle was measured using a contact angle meter.
[0045] In order to test the catalytic performance of the catalyst in the catalytic experiment of dehydrogenative coupling of silane and alcohol, the present invention uses diphenylsilane and methanol as catalytic templates for reaction testing (1.25 mmol of diphenylsilane, 0.5 mmol of dodecane, 2 mL of methanol, 60°C). The reaction products include the intermediate product II diphenylmethoxysilane with one Si-H replaced and the target product III diphenyldimethoxysilane with two Si-H replaced. The reaction diagram is as follows: .
[0046] To minimize costs and pollution, the reaction was conducted using a vial with a small amount of substrate. The catalyst, solvent, and substrate were added first, and finally, dodecane was added as an internal standard for subsequent gas phase analysis. The reaction was stirred at a constant temperature and then tested for conversion and selectivity in replacing two Si-H residues after varying reaction times.
[0047] The catalyst and substrate were scaled up fivefold, reacted at 60°C for 6 hours, then filtered and washed, and the next reaction was continued to explore the catalyst's stability. Six more reactions were repeated under the conditions of the first complete reaction to explore the catalyst's cyclic stability under multiple reactions.
[0048] The catalytic activity test results of the silica-supported copper metal nanoparticles heterogeneous catalyst (Cu / CTAB-SiO2) are listed in Table 1.
[0049] The cycling stability test results of the silica-supported copper metal nanoparticles heterogeneous catalyst (Cu / CTAB-SiO2) are listed in Table 2.
[0050] The following is a comparative explanation of the embodiment with reference to the comparative example, as follows.
[0051] Comparative Example 1.
[0052] The processing steps of the silica-supported copper metal nanoparticles heterogeneous catalyst (Cu / SiO2) without the addition of dispersant are as follows.
[0053] S1. Dissolve 0.1 g of copper chloride dihydrate in 60 mL of ethanol, add 0.2 mL of ammonia water dropwise, sonicate for 10 minutes, and place in an ice-water bath and stir for 1 hour.
[0054] S2. Slowly add 0.43 mL of ethyl orthosilicate to the mixed solution in S1, and finally continue stirring in an ice-water bath for 5 h.
[0055] S3. Prefreeze 20 mL (2.5 mg / mL) of NaBH4 solution for 1 h, then slowly add it dropwise to the above mixed solution and stir for 12 h.
[0056] S4. The mixed solution was washed three times with deionized water and then filtered, placed in a refrigerator for 5 h, and finally placed in a freeze dryer for 20 h to obtain a dried silica-supported copper metal nanoparticle heterogeneous catalyst without adding a dispersant.
[0057] The performance test was the same as in Example 1, and the test results are listed in Table 1.
[0058] Comparative Example 2.
[0059] The processing steps of the silica-supported copper metal nanoparticles heterogeneous catalyst (Cu / SiO2) without the addition of dispersant are as follows.
[0060] S1. Dissolve 0.12 g of copper chloride dihydrate in 80 mL of ethanol, add 0.3 mL of ammonia water dropwise, sonicate for 10 minutes, and place in an ice-water bath and stir for 1 hour.
[0061] S2. Slowly add 0.6 mL of ethyl orthosilicate to the S2 mixed solution, and finally continue stirring in an ice-water bath for 6 h.
[0062] S3. Prefreeze 20 mL (2.5 mg / mL) of NaBH4 solution for 1 h, then slowly add it dropwise to the above mixed solution and stir for 12 h.
[0063] S4. The mixed solution was washed three times with deionized water and then filtered. The mixed solution was placed in a refrigerator for 5 h and finally placed in a freeze dryer for 20 h to obtain a dried silica-supported non-precious metal nanoparticle heterogeneous catalyst.
[0064] The performance test was the same as in Example 1, and the test results are listed in Table 1.
[0065] Comparative Example 3.
[0066] The processing steps of the silica-supported copper metal nanoparticles heterogeneous catalyst (Cu / SiO2) without the addition of dispersant are as follows.
[0067] S1. Dissolve 0.08 g of copper chloride dihydrate in 100 mL of ethanol, add 0.4 mL of ammonia water dropwise, sonicate for 10 minutes, and then place in an ice-water bath and stir for 1 hour.
[0068] S2. Slowly add 0.8 mL of ethyl orthosilicate to the S2 mixed solution, and finally continue stirring in an ice-water bath for 6 h.
[0069] S3. Prefreeze 20 mL (3 mg / mL) NaBH4 solution for 1 h, then slowly add it dropwise to the above mixed solution and stir for 12 h.
[0070] S4. The mixed solution was washed three times with deionized water and then filtered. The mixed solution was placed in a refrigerator for 5 h and finally placed in a freeze dryer for 20 h to obtain a dried silica-supported non-precious metal nanoparticle heterogeneous catalyst.
[0071] The performance test was the same as in Example 1, and the test results are listed in Table 1.
[0072] Table 1 .
[0073] Table 2 .
[0074] The present invention takes metal heterogeneous nanoparticle catalyst as the research object, selects silica as the support, and modifies it with a dispersant to prepare a silica-supported metal heterogeneous catalyst for dehydrogenation coupling to produce silyl ether. The transmission electron microscopy image of the catalyst sample ( Figure 1-2 ) It can be seen that after the effect of the dispersant, the metal nanoparticles of the Cu / CTAB-SiO2 catalyst are smaller in size and more evenly distributed than those of the Cu / SiO2 catalyst, which indicates that the effect of the dispersant increases the catalytic active sites and is conducive to the improvement of catalytic activity. The contact angle test results of the samples ( Figure 3-4 8 ) shows that the contact angle of Cu / CTAB-SiO2 is 45.8 o , which is higher than 26.3 of Cu / SiO2 catalyst oThis suggests that the dispersant can enhance the catalyst's adsorption capacity for the substrate, which in turn improves catalytic efficiency. The catalytic activity results, as shown in Table 1, show that under identical reaction conditions, Cu / CTAB-SiO2 and Cu / SiO2 catalysts reacted for 20 minutes. Cu / CTAB-SiO2 exhibited significantly higher catalytic activity, reaching a conversion of 99%. The selectivity for replacing two Si-H atoms reached 55%, significantly exceeding the 78% conversion and 6% selectivity of Cu / SiO2. Furthermore, the cyclic stability of the Cu / CTAB-SiO2 catalyst was tested. As shown in Table 2, the Cu / CTAB-SiO2 catalyst was used for six cycles (in the first cycle, the mass of diphenylsilane, methanol, and catalyst was increased fivefold, and in subsequent cycles, the mass of diphenylsilane and methanol was reduced in proportion to the catalyst loss. The reaction time was 1.5 hours). After six cycles, the conversion and selectivity for replacing two Si-H atoms remained above 99%, demonstrating the high stability and activity of Cu / CTAB-SiO2. In summary, the silica-supported metal heterogeneous catalyst prepared by the present invention can efficiently catalyze the dehydrogenative coupling of silanes and alcohols to produce silyl ethers. Its metal nanoparticles are evenly dispersed, exhibit high catalytic activity, and exhibit strong stability. This catalyst has broad application prospects in the industrial catalytic dehydrogenative coupling of hydrosilanes and alcohols.
[0075] The above shows and describes the preparation process and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and description merely describe the method of the present invention. Various changes and modifications are possible without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the claimed invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction, characterized in that The following steps are involved: S1. Dissolve the metal nanoparticle precursor in ethanol, add ammonia water, perform ultrasonic treatment for 10-30 minutes, and then place in an ice water bath at about 5°C and stir for 1-3 hours for standby use; S2. Slowly drop the dispersant dissolved in ethanol into the solution obtained in step S1, stir evenly, then slowly drop the silicon source of the silicon dioxide precursor, continue stirring in an ice water bath at about 5° C. for 5-12 h, and set aside; S3, pre-freeze the sodium borohydride aqueous solution for 1-3 h, then slowly add it dropwise to the solution obtained in step S2 and stir to react for 12-30 h; S4, filtering the mixed solution obtained in step S3, washing with water to obtain a solid product, and freeze-drying to obtain a metal heterogeneous catalyst.
2. The method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction according to claim 1, characterized in that The metal nano-ion precursor comprises one or more of palladium chloride, ferric chloride, cupric chloride, nickel chloride and cobalt chloride, and the concentration of the metal nano-ion precursor dissolved in ethanol is 1-10 g / L.
3. The method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction according to claim 1, characterized in that The dispersant is one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; the mass ratio of the metal nanoparticle precursor to the dispersant is 1:1-10, and the concentration of the dispersant dissolved in ethanol is 1-20 g / L.
4. The method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction according to claim 1, characterized in that The silicon source is one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, silica sol or silicic acid; the molar ratio of the silicon source to the metal precursor is 1:0.2-3, and the volume ratio of ethyl orthosilicate to ammonia water is 1:1-5.
5. The method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction according to claim 1, characterized in that The molar ratio of the metal nanoparticle precursor to sodium borohydride is 1:1-5, and the concentration of sodium borohydride dissolved in water is 1-5 g / L.
6. Use of the metal heterogeneous catalyst prepared by the method for preparing a metal heterogeneous catalyst for dehydrogenation coupling reaction according to claim 1 in a dehydrogenation coupling reaction of a hydrogen-containing silane-alcohol.
7. The use according to claim 6, characterized in that The molar ratio of hydrosilane to alcohol in the hydrosilane-alcohol dehydrogenation coupling reaction is 1:10-50.
8. The use according to claim 6, characterized in that The hydrosilane described in the dehydrogenation coupling reaction of hydrosilane-alcohol is one or more of phenylsilane, diphenylsilane and dimethylphenylsilane; the alcohol described is one or more of methanol, ethanol, n-butanol and isopropanol.
9. The use according to claim 6, characterized in that The temperature at which the catalyst, hydrosilane and alcohol are in contact in the hydrosilane-alcohol dehydrogenation coupling reaction is 30-80° C., and the stirring speed is 150-600 rpm.