Preparation method of high-activity palladium-carbon catalyst and application of high-activity palladium-carbon catalyst in preparation of monosilane
By performing hydrogen peroxide treatment on biochar materials and self-assembly of specific substances, a highly active palladium carbon catalyst was prepared, which solved the problems of low efficiency and high cost in the prior art, and achieved high purity preparation of silane and the recyclability of the catalyst.
Patent Information
- Application Number
- CN202411648623.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-03-04
AI Technical Summary
The prior art catalysts are low in efficiency, high cost, and harsh in the reaction conditions, making it difficult to achieve industrial production. In addition, there are too many liquid by-products produced by the catalyst after the reaction, which affects purification and recycling.
By performing hydrogen peroxide treatment on biochar materials, self-assembly of specific substances and palladium salt loading, a highly active palladium carbon catalyst is prepared, which improves the activity and purity of the catalyst, reduces costs, and makes the catalyst recyclable.
It significantly improves the product purity of silane, reduces production costs, and makes the catalyst have good recycling performance, which is suitable for industrial production.
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Figure CN119549176A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of palladium-carbon catalysts, and in particular relates to a preparation method of a high-activity palladium-carbon catalyst and application of the catalyst in preparing monosilane. Background Art
[0002] Monosilane is a colorless gas with a foul odor at room temperature and pressure. Its boiling point is -112°C. When heated to above 900°C, it decomposes to produce high-purity silicon and hydrogen. As a gas source that can provide silicon components, monosilane stands out among many special gases due to its high purity and the ability to achieve fine control. It has become an important existence that cannot be replaced by many other silicon sources. It is widely used in many different fields, including the manufacture of large-scale integrated circuits and chips, photovoltaic cells, flat panel displays, semiconductors, glass, automobiles, and construction.
[0003] At present, there are mainly the following methods for preparing monosilane: the first is the reaction of magnesium silicide and hydrochloric acid, but the yield of this method is low, and the impurity disilane exists in the product; the second is the reduction of silicon halide, but due to the use of silicon halide, halogen element impurities may be introduced, which increases the cost and difficulty of subsequent impurity removal; the third is through the disproportionation of triethoxysilane. The raw materials used in this method do not contain halogen elements, and the purity of the product is higher than that obtained by the first two methods. The range of reaction catalysts for disproportionation decomposition reactions is very wide. Hydroxyl metal salts, alkali metal trialkoxysilanes, alkaline earth metal and aluminum tetraalkoxysilanes can often be used as catalysts. However, many types of catalysts reported in the literature meet the requirements of not easily producing pollutants and not increasing the difficulty of purifying monosilane to a certain extent, but catalysts such as activated alumina and activated carbon generally have the problem of low catalytic efficiency, so the catalyzed reaction is not worth industrial production. In addition, there are some catalysts that have extremely harsh reaction conditions and need to be carried out under high temperature and high pressure, which puts very strict requirements on production equipment, and also consumes a lot of energy, greatly increasing the economic cost of the product. Moreover, for the catalyst, the types and output of liquid by-products after the catalytic reaction should be reduced as much as possible, because if there are too many by-products, it will be detrimental to the purification, recovery and recycling of the by-products. Summary of the invention
[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention treats the biochar material with hydrogen peroxide, self-assembles specific substances, loads palladium salts and other operations, thereby realizing the preparation of a highly active palladium-carbon catalyst, effectively improving the product purity and reducing the cost in the process of catalyzing the reaction of triethoxysilane, and making the catalyst recyclable.
[0005] In order to achieve the above object, the following technical scheme is adopted: In the first aspect, the present invention provides a method for preparing a high-activity palladium-carbon catalyst, comprising the following steps:
[0006] S1. Add the biochar material into 30% hydrogen peroxide by volume and let it stand for 30 minutes, then wash and dry it, add it into a tube furnace, heat it to 300-350°C at a heating rate of 10-20°C / min at a flow rate of 100-150mL / min of nitrogen, and calcine it for 1-2h to obtain an activated carbon carrier powder;
[0007] S2, dissolving 2,9,16,23-tetraaminophthalocyanine in ethanol to obtain a first solution, then adding activated carbon carrier powder, ultrasonically dispersing the activated carbon carrier powder for 10-30 minutes, and then dissolving 2,2'-bipyridine-4,4'-dicarboxaldehyde in ethanol to obtain a second solution, slowly adding the second solution to the first solution, and after the addition is completed, transferring the reaction solution to a hydrothermal reactor at 120-150° C. to react for 5 hours, cooling to room temperature, filtering, washing, and drying to obtain a surface self-assembled activated carbon carrier;
[0008] S3, dissolving palladium salt in deionized water to obtain a 2 mol / L palladium salt solution, adding the surface self-assembled activated carbon carrier thereto, ultrasonicating for 10-30 min, standing for 10-20 min, filtering, washing with deionized water, drying, and calcining at 200-250° C. for 2-5 h;
[0009] S4. Add the calcined catalyst into a polytetrafluoroethylene reactor, add deionized water, then add triethylamine and {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol, react for 10 minutes, add 1,3-propane sultone, react at 60°C for 12 hours, filter, wash and dry to obtain the highly active palladium carbon catalyst.
[0010] Furthermore, the biochar material is any one of peanut shells, walnut shells, sunflower seed shells, hazelnut shells, and almond shells, or a combination of two of them.
[0011] Furthermore, in step S1, the mass ratio of the biochar material to the hydrogen peroxide is 0.8-1:50-60.
[0012] Furthermore, the mass ratio of 2,9,16,23-tetraaminophthalocyanine to activated carbon carrier powder in the first solution is 1-1.5:75-110; the mass ratio of 2,2'-bipyridine-4,4'-dicarboxaldehyde to ethanol in the second solution is 1-2.5:80-100.
[0013] Furthermore, the mass ratio of the first solution to the second solution is 1.2-1.8:1-1.2.
[0014] Furthermore, the palladium salt is one of palladium acetate, palladium chloride and palladium nitrate.
[0015] Furthermore, in step S3, the mass ratio of the palladium salt solution to the surface self-assembled activated carbon carrier is 0.3-1:1-1.5.
[0016] Furthermore, in step S4, the mass ratio of the calcined catalyst, deionized water, triethylamine, {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone is 1-1.5:100-180:0.1-0.3:0.5-1.2:0.5-1.5.
[0017] In a second aspect, the present invention provides an application of a high-activity palladium-carbon catalyst in the preparation of monosilane, comprising the following steps:
[0018] (1) Add a highly active palladium carbon catalyst into a four-necked flask, introduce nitrogen, and check the air tightness. After the inspection, continue to introduce nitrogen to remove the air in the four-necked flask to ensure that the reaction environment is oxygen-free;
[0019] (2) Add toluene into the four-necked flask using a syringe, stir, and heat to 40-60°C;
[0020] (3) triethoxysilane is slowly pumped into the four-necked flask using a liquid metering pump while maintaining uniform and appropriate stirring. At this time, the highly active palladium-carbon catalyst plays a catalytic role in promoting the reaction;
[0021] (4) After reacting for 4-6 hours, the solvent vapor is condensed and refluxed into the flask along the condenser, and the silane vapor flows out through the distillation tube to obtain monosilane;
[0022] (5) After the reaction is completed, the residual liquid in the flask is recovered, and the solvent and the reaction product are separated by distillation to obtain tetraethoxysilane and solvent toluene.
[0023] Furthermore, the dosage of the high-activity palladium-carbon catalyst is 0.1%-0.5% of the mass of triethoxysilane.
[0024] The beneficial effects of the present invention are:
[0025] (1) In the preparation process of the present invention, the biochar material is treated with hydrogen peroxide to effectively destroy the original structure of the biochar material and partially dissolve it. Then, 2,9,16,23-tetraaminophthalocyanine and 2,2'-bipyridine-4,4'-dicarboxaldehyde are used to self-assemble in the biochar material. The π electrons on the pyrrole ring and the benzene ring in the phthalocyanine molecule have a strong conjugated effect, and 2,2'-bipyridine-4,4'-dicarboxaldehyde also has a conjugated structure. The interaction between the two can greatly enhance the stability of the self-assembled structure, self-assemble to form a Schiff base structure, further stabilize the self-assembled membrane structure, and successfully construct a porous network structure on the surface of the activated carbon carrier during the self-assembly process. The structure not only significantly increases the specific surface area, providing more contact space for the reaction, but also provides a rich source of N. After subsequent calcination, the specific surface area of the activated carbon is further increased, and the number of active sites increases, making its adsorption capacity and chemical reaction activity stronger. The introduction of N atoms changes the distribution of electron cloud density on the surface of activated carbon, making it able to adsorb substances more powerfully, and N atoms can coordinate with palladium ions as active sites, greatly improving the dispersion and stability of palladium ions on the surface of activated carbon. At the same time, the porous network structure provides a convenient channel and sufficient storage space for the diffusion and adsorption of gas molecules, which is conducive to the adsorption of gas molecules on the catalyst surface and participation in the reaction, further improving the performance and efficiency of the catalyst.
[0026] (2) The present invention makes the palladium carbon catalyst amphiphilic through the action of {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone, which plays a key role in the preparation of monosilane. The catalyst can effectively reduce the interfacial tension, adjust the interfacial behavior between steam and liquid, prevent the product and the solvent from forming an emulsion or excessive mixing, ensure that the product and the solvent remain in a relatively independent state, thereby promoting the separation of the product and the solvent, and making the prepared product have a higher purity. The catalyst has high activity and can be recycled, thereby reducing the use and production costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 The effects of the palladium-carbon catalysts of the embodiments and comparative examples of the present invention on the decomposition rate of methoxysilane and the yield of monosilane;
[0028] Figure 2 The results of evaluating the recycling performance of palladium-carbon catalysts of various embodiments and comparative examples of the present invention are as follows;
[0029] Figure 3 The purity test results of tetramethoxysilane catalyzed by palladium-carbon catalysts of various embodiments and comparative examples of the present invention are as follows;
[0030] Figure 4 The microscopic morphology and structure observation results of the palladium-carbon catalyst of each embodiment 3 and comparative example 1 of the present invention.
[0031] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION
[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0033] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.
[0034] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.
[0035] Example 1
[0036] A method for preparing a high-activity palladium-carbon catalyst comprises the following steps:
[0037] S1. Add the biochar material into 30% hydrogen peroxide by volume and let it stand for 30 minutes, then wash and dry it, add it into a tube furnace, heat it to 300°C at a heating rate of 10°C / min under a nitrogen flow rate of 100 mL / min, and calcine it for 1 hour to obtain an activated carbon carrier powder;
[0038] S2, dissolving 2,9,16,23-tetraaminophthalocyanine in ethanol to obtain a first solution, then adding activated carbon carrier powder, ultrasonically dispersing the activated carbon carrier powder for 10 minutes, and then dissolving 2,2'-bipyridine-4,4'-dicarboxaldehyde in ethanol to obtain a second solution, slowly adding the second solution to the first solution, and after the addition is completed, transferring the reaction solution to a hydrothermal reactor to react at 120° C. for 5 hours, cooling to room temperature, filtering, washing, and drying to obtain a surface self-assembled activated carbon carrier;
[0039] S3, dissolving palladium salt in deionized water to obtain a 2 mol / L palladium salt solution, adding the surface self-assembled activated carbon support thereto, ultrasonicating for 10 min, standing for 10 min, filtering, washing with deionized water, drying, and calcining at 200° C. for 2 h;
[0040] S4, adding the calcined catalyst to a polytetrafluoroethylene reactor, adding deionized water, then adding triethylamine and {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol, reacting for 10 minutes, adding 1,3-propane sultone, reacting at 60°C for 12 hours, filtering, washing, and drying to obtain the highly active palladium carbon catalyst; the biochar material is peanut shell; the mass ratio of the biochar material to the hydrogen peroxide in step S1 is 0.8:50; the mass ratio of 2,9,16,23-tetraaminophthalocyanine to the activated carbon carrier powder in the first solution is 0.8:50; is 1:75; the mass ratio of 2,2'-bipyridine-4,4'-dicarboxaldehyde and ethanol in the second solution is 1:80; the mass ratio of the first solution to the second solution is 1.2:1; the palladium salt is palladium acetate; the mass ratio of the palladium salt solution and the surface self-assembled activated carbon carrier in the step S3 is 0.3:1; the mass ratio of the calcined catalyst, deionized water, triethylamine, {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone in the step S4 is 1:100:0.1:0.5:0.5.
[0041] Example 2
[0042] A method for preparing a high-activity palladium-carbon catalyst comprises the following steps:
[0043] S1. Add the biochar material into 30% hydrogen peroxide by volume and let it stand for 30 minutes, then wash and dry it, add it into a tube furnace, heat it to 350°C at a nitrogen flow rate of 150mL / min and heat it at a rate of 20°C / min for 2 hours to obtain an activated carbon carrier powder;
[0044] S2, dissolving 2,9,16,23-tetraaminophthalocyanine in ethanol to obtain a first solution, then adding activated carbon carrier powder, ultrasonically dispersing the activated carbon carrier powder for 30 minutes, and then dissolving 2,2'-bipyridine-4,4'-dicarboxaldehyde in ethanol to obtain a second solution, slowly adding the second solution to the first solution, and after the addition is completed, transferring the reaction solution to a hydrothermal reactor to react at 150° C. for 5 hours, cooling to room temperature, filtering, washing, and drying to obtain a surface self-assembled activated carbon carrier;
[0045] S3, dissolving palladium salt in deionized water to obtain a 2 mol / L palladium salt solution, adding the surface self-assembled activated carbon support thereto, ultrasonicating for 30 min, standing for 20 min, filtering, washing with deionized water, drying, and calcining at 250° C. for 5 h;
[0046] S4. Add the calcined catalyst into a polytetrafluoroethylene reactor, add deionized water, then add triethylamine and {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol, react for 10 minutes, add 1,3-propane sultone, react at 60°C for 12 hours, filter, wash and dry to obtain the highly active palladium carbon catalyst.
[0047] The biochar material is sunflower seed shell; in the step S1, the mass ratio of the biochar material to the hydrogen peroxide is 1:60; in the first solution, the mass ratio of 2,9,16,23-tetraaminophthalocyanine to the activated carbon carrier powder is 1.5:110; in the second solution, the mass ratio of 2,2'-bipyridine-4,4'-dicarboxaldehyde to ethanol is 2.5:100; the mass ratio of the first solution to the second solution is 1.8:1.2; the palladium salt is palladium nitrate; in the step S3, the mass ratio of the palladium salt solution to the surface self-assembled activated carbon carrier is 1:1.5; in the step S4, the mass ratio of the calcined catalyst, deionized water, triethylamine, {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone is 1.5:180:0.3:1.2:1.5.
[0048] Example 3
[0049] A method for preparing a high-activity palladium-carbon catalyst comprises the following steps:
[0050] S1. Add the biochar material into 30% hydrogen peroxide by volume and let it stand for 30 minutes, then wash and dry it, add it into a tube furnace, heat it to 320°C at a nitrogen flow rate of 120 mL / min and calcine it at a heating rate of 15°C / min for 1.5 hours to obtain an activated carbon carrier powder;
[0051] S2, dissolving 2,9,16,23-tetraaminophthalocyanine in ethanol to obtain a first solution, then adding activated carbon carrier powder, ultrasonically dispersing the activated carbon carrier powder for 20 minutes, and then dissolving 2,2'-bipyridine-4,4'-dicarboxaldehyde in ethanol to obtain a second solution, slowly adding the second solution to the first solution, and after the addition is completed, transferring the reaction solution to a hydrothermal reactor to react at 130° C. for 5 hours, cooling to room temperature, filtering, washing, and drying to obtain a surface self-assembled activated carbon carrier;
[0052] S3, dissolving palladium salt in deionized water to obtain a 2 mol / L palladium salt solution, adding the surface self-assembled activated carbon support thereto, ultrasonicating for 20 min, standing for 15 min, filtering, washing with deionized water, drying, and calcining at 130° C. for 3 h;
[0053] S4. Add the calcined catalyst into a polytetrafluoroethylene reactor, add deionized water, then add triethylamine and {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol, react for 10 minutes, add 1,3-propane sultone, react at 60°C for 12 hours, filter, wash and dry to obtain the highly active palladium carbon catalyst.
[0054] The biochar material is almond shell; the mass ratio of the biochar material to hydrogen peroxide in step S1 is 0.9:53; the mass ratio of 2,9,16,23-tetraaminophthalocyanine to activated carbon carrier powder in the first solution is 1.2:100; the mass ratio of 2,2'-bipyridine-4,4'-dicarboxaldehyde to ethanol in the second solution is 1.5:90; the mass ratio of the first solution to the second solution is 1.5:1.1. The palladium salt is palladium nitrate; the mass ratio of the palladium salt solution to the surface self-assembled activated carbon carrier in step S3 is 0.5:1.2; the mass ratio of the calcined catalyst, deionized water, triethylamine, {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone in step S4 is 1.2:150:0.2:1:1.2.
[0055] Example 4
[0056] A method for preparing monosilane using a high-activity palladium-carbon catalyst comprises the following steps:
[0057] (1) Add a highly active palladium carbon catalyst into a four-necked flask, introduce nitrogen, and check the air tightness. After the inspection, continue to introduce nitrogen to remove the air in the four-necked flask to ensure that the reaction environment is oxygen-free;
[0058] (2) Add toluene into the four-necked flask using a syringe, stir, and heat to 50°C;
[0059] (3) triethoxysilane is slowly pumped into the four-necked flask using a liquid metering pump while maintaining uniform and appropriate stirring. At this time, the highly active palladium-carbon catalyst plays a catalytic role in promoting the reaction;
[0060] (4) After reacting for 5 hours, the solvent vapor is condensed along the condenser and refluxed into the flask, and the silane vapor flows out through the distillation tube to obtain monosilane;
[0061] (5) After the reaction is completed, the residual liquid in the flask is recovered, and the solvent and the reaction product are separated by distillation to obtain tetraethoxysilane and solvent toluene.
[0062] The dosage of the high-activity palladium carbon catalyst is 0.3% of the mass of triethoxysilane.
[0063] Comparative Example 1
[0064] The difference between this comparative example and Example 3 is that the components do not contain 2,2'-bipyridine-4,4'-dicarboxaldehyde, and the rest is the same as Example 3.
[0065] Comparative Example 2
[0066] The difference between this comparative example and Example 3 is that an equal amount of heptanedialdehyde is used to replace 2,2'-bipyridine-4,4'-dicarboxaldehyde, and the rest is the same as Example 3.
[0067] Comparative Example 3
[0068] The difference between this comparative example and Example 3 is that the preparation process does not include step S4, that is, the palladium carbon catalyst is obtained without modification of {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone, and the rest is the same as Example 3.
[0069] Results Analysis
[0070] Test Example 1
[0071] Decomposition rate of trimethoxysilane and yield of monosilane
[0072] The trimethoxysilane decomposition rate and monosilane yield of the palladium-carbon catalyst prepared in each embodiment and comparative example when catalyzing trimethoxysilane are calculated. The results are shown in Figure 1 .
[0073] Depend on Figure 1It can be seen that in the embodiments of the present invention, the biochar material is first treated with hydrogen peroxide to destroy its original structure and partially dissolve it. Subsequently, after multiple steps of self-assembly, calcination and other operations, a porous network structure is successfully constructed, the specific surface area is increased, a rich N source is provided, and N atoms can coordinate with palladium ions, thereby improving the dispersion and stability of palladium ions on the surface of activated carbon. These factors combined make the catalyst have good activity and selectivity in the reaction of preparing monosilane, and can more effectively promote the decomposition of trimethoxysilane, thereby obtaining a higher monosilane yield. Comparative Example 1 does not contain 2,2'-bipyridine-4,4'-dicarboxaldehyde in the components, lacks the 2,9,16,23-tetraaminobenzene. Phthalocyanine is a key component that interacts with each other to form a stable self-assembled structure. The self-assembly process is affected, resulting in the inability to successfully construct an ideal porous network structure, the specific surface area does not increase significantly, and the active sites are relatively few, which in turn affects the catalytic decomposition effect on trimethoxysilane, making the monosilane yield lower than that in the embodiment. Comparative Example 2 uses an equal amount of heptanedialdehyde to replace 2,2'-bipyridine-4,4'-dicarboxaldehyde. Although it has a similar aldehyde structure, it may not be able to form a stable and effective interaction with phthalocyanine molecules like 2,2'-bipyridine-4,4'-dicarboxaldehyde, which will also affect the stability of the self-assembled structure and the formation of a porous network structure, ultimately resulting in the trimethoxysilane decomposition rate and monosilane yield being not as ideal as in the embodiment.
[0074] Test Example 2
[0075] Evaluation of the recycling performance of palladium-carbon catalyst
[0076] The yield of monosilane after 10 cycles of palladium-carbon catalysts prepared in each embodiment and comparative example was calculated. Figure 2 .
[0077] Depend on Figure 2It can be seen that the high-activity palladium-carbon catalyst in the embodiment is structurally stable, and the Schiff base structure formed by self-assembly further stabilizes the self-assembled membrane structure, and subsequent treatments such as calcination further increase the specific surface area of the activated carbon and increase the number of active sites. At the same time, during the preparation process, through the action of {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone, the palladium-carbon catalyst has amphiphilicity, which can effectively reduce the interfacial tension, regulate the interfacial behavior between steam and liquid, prevent the product and solvent from forming an emulsion or excessive mixing, and ensure that the product and solvent remain relatively independent. This series of characteristics enables the catalyst to be used in a recycling process. The activity of the catalyst can be well maintained, and even after 10 cycles, a relatively high silane yield can be maintained. However, the specific surface area of comparative example 1 does not increase significantly, and the active sites are relatively few. Comparative example 2 lacks the stability of the self-assembled structure and the formation of a porous network structure. Comparative example 3 has not been modified by {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone, and the catalyst lacks the important characteristic of amphiphilicity. Therefore, during the cyclic use of the comparative examples of the present invention, it is more likely that the product and the solvent are mixed and difficult to separate, resulting in contamination or blockage of the active sites of the catalyst, thereby gradually reducing its activity and reducing the cyclic catalytic performance.
[0078] Test Example 3
[0079] Purity test of product tetramethoxysilane
[0080] The purity of the product tetramethoxysilane catalyzed by the palladium carbon catalyst prepared in each embodiment and comparative example was detected by ICP elemental analyzer. Figure 3 .
[0081] Depend on Figure 3 It can be seen that the high-activity palladium-carbon catalyst prepared in the embodiment of the present invention has an amphiphilic property that can effectively prevent the product and the solvent from forming an emulsion or excessive mixing, ensuring that the product and the solvent remain relatively independent, which is critical for improving the purity of the product tetramethoxysilane. Therefore, during the reaction process, the catalyst prepared in the embodiment of the present invention can accurately catalyze the reaction, so that the generated tetramethoxysilane can be separated relatively purely, so the impurity content is relatively lower than that of the comparative examples.
[0082] Test Example 4
[0083] Microstructure Observation of Palladium-Carbon Catalyst
[0084] The microstructures of Example 3 and Comparative Example 1 were observed by scanning electron microscopy. Figure 4 .
[0085] Depend on Figure 4It can be seen that in Example 3, a porous network structure is successfully constructed, which increases the specific surface area of the activated carbon, increases the number of active sites, and the microscopic morphology shows that the voids are complete and developed. This good microstructure provides a basis for the high performance of the catalyst, which can better adsorb reactants and promote the reaction. However, since the comparative example lacks the key component 2,2'-bipyridine-4,4'-dicarboxaldehyde) in the self-assembly link, the self-assembly process is disturbed and a complete and stable self-assembly structure as in Example 3 cannot be formed, and the microscopic morphology shows that the voids collapse, which affects the performance of the catalyst and therefore cannot fully play its role in the reaction.
[0086] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
[0087] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.
Claims
1. A method for preparing a highly active palladium-carbon catalyst, characterized in that: The steps include: S1. Add the biochar material into 30% hydrogen peroxide by volume and let it stand for 30 minutes, then wash and dry it, add it into a tube furnace, heat it to 300-350°C at a heating rate of 10-20°C / min at a flow rate of 100-150mL / min of nitrogen, and calcine it for 1-2h to obtain an activated carbon carrier powder; S2, dissolving 2,9,16,23-tetraaminophthalocyanine in ethanol to obtain a first solution, then adding activated carbon carrier powder, ultrasonically dispersing the activated carbon carrier powder for 10-30 minutes, and then dissolving 2,2'-bipyridine-4,4'-dicarboxaldehyde in ethanol to obtain a second solution, slowly adding the second solution to the first solution, and after the addition is completed, transferring the reaction solution to a hydrothermal reactor at 120-150° C. to react for 5 hours, cooling to room temperature, filtering, washing, and drying to obtain a surface self-assembled activated carbon carrier; S3, dissolving palladium salt in deionized water to obtain a 2 mol / L palladium salt solution, adding the surface self-assembled activated carbon carrier thereto, ultrasonicating for 10-30 min, standing for 10-20 min, filtering, washing with deionized water, drying, and calcining at 200-250° C. for 2-5 h; S4. Add the calcined catalyst into a polytetrafluoroethylene reactor, add deionized water, then add triethylamine and {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol, react for 10 minutes, add 1,3-propane sultone, react at 60°C for 12 hours, filter, wash and dry to obtain the highly active palladium carbon catalyst.
2. The method for preparing a highly active palladium-carbon catalyst according to claim 1, wherein: The biochar material is any one of peanut shells, walnut shells, sunflower seed shells, hazelnut shells, and almond shells, or a combination of two of them.
3. The method for preparing a highly active palladium-carbon catalyst according to claim 2, wherein: In step S1, the mass ratio of the biochar material to the hydrogen peroxide is 0.8-1:50-60.
4. The method for preparing a highly active palladium-carbon catalyst according to claim 3, wherein: The mass ratio of 2,9,16,23-tetraaminophthalocyanine to activated carbon carrier powder in the first solution is 1-1.5:75-110; the mass ratio of 2,2'-bipyridine-4,4'-dicarboxaldehyde to ethanol in the second solution is 1-2.5:80-100.
5. The method for preparing a highly active palladium-carbon catalyst according to claim 4, wherein: The mass ratio of the first solution to the second solution is 1.2-1.8:1-1.
2.
6. A method for preparing a highly active palladium-carbon catalyst according to claim 5, characterized in that: The palladium salt is one of palladium acetate, palladium chloride and palladium nitrate.
7. The method for preparing a highly active palladium-carbon catalyst according to claim 6, wherein: In step S3, the mass ratio of the palladium salt solution to the surface self-assembled activated carbon carrier is 0.3-1:1-1.
5.
8. The method for preparing a highly active palladium-carbon catalyst according to claim 7, wherein: The mass ratio of the calcined catalyst, deionized water, triethylamine, {2-[(dimethylamino)methyl]-1,3-thiazol-4-yl}methanol and 1,3-propane sultone in step S4 is 1-1.5:100-180:0.1-0.3:0.5-1.2:0.5-1.
5.
9. Use of the high-activity palladium-carbon catalyst according to any one of claims 1 to 8 in the preparation of monosilane, characterized in that: The steps include: (1) Add a highly active palladium carbon catalyst into a four-necked flask, introduce nitrogen, and check the air tightness. After the inspection, continue to introduce nitrogen to remove the air in the four-necked flask to ensure that the reaction environment is oxygen-free; (2) Add toluene into the four-necked flask using a syringe, stir, and heat to 40-60°C; (3) triethoxysilane is slowly pumped into the four-necked flask using a liquid metering pump while maintaining uniform and appropriate stirring. At this time, the highly active palladium-carbon catalyst plays a catalytic role in promoting the reaction; (4) After reacting for 4-6 hours, the solvent vapor is condensed and refluxed into the flask along the condenser, and the silane vapor flows out through the distillation tube to obtain monosilane; (5) After the reaction is completed, the residual liquid in the flask is recovered, and the solvent and the reaction product are separated by distillation to obtain tetraethoxysilane and solvent toluene.
10. Use of the high-activity palladium-carbon catalyst according to claim 9 in the preparation of monosilane, characterized in that: The dosage of the high-activity palladium carbon catalyst is 0.1%-0.5% of the mass of triethoxysilane.