A solid supported non-noble metal single atom catalyst and a preparation method thereof, and a preparation method of diisopropylaminosilane

Abstract

The present application relates to the technical field of catalyst, in particular to a kind of solid supported non-noble metal single atom catalyst and its preparation method, the preparation method of diisopropylaminosilane.The Co-N4 coordination structure in the solid supported non-noble metal single atom catalyst provided by the present application has very high catalytic activity and selectivity, can efficiently activate Si-H bond in silane molecule and N-H bond in diisopropylamine molecule, promotes the directional progress of dehydrogenation coupling reaction, significantly inhibits side reaction (such as polysubstitution, polymerization), the conversion rate of diisopropylamine is high, and the selectivity of target product is high;The small channel of microchannel continuous flow reactor can greatly increase the contact area of gas-liquid-solid three phases, accelerate the mass transfer rate, realize the "in and reverse" of silane, effectively avoid the safety hidden trouble caused by gas accumulation, and simultaneously, the catalyst is solid supported in reaction zone, without subsequent separation step, significantly simplify process flow.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a supported non-precious metal single-atom catalyst and its preparation method, and a method for preparing diisopropylaminosilane. Background Technology

[0002] Electronic-grade diisopropylaminosilane (DIPAS) is a key precursor in advanced atomic layer deposition (ALD) processes, used for low-temperature deposition of high-quality silicon oxide and silicon nitride thin films in the manufacture of memory and logic chips at 20nm and below. As the feature size of integrated circuits continues to shrink, more stringent requirements are being placed on the purity of precursors (especially the content of metal ions, halogens, and particulate matter).

[0003] Currently, the industrial preparation of DIPAS mainly relies on two technical routes: the halosilane method and the noble metal catalytic dehydrogenation coupling method.

[0004] The halosilane method involves a substitution reaction between halosilanes and diisopropylamine, generating a large amount of diisopropylammonium halide as a byproduct. These ammonium salts exhibit strong adsorption properties, leading to lengthy filtration and separation processes, and they readily leave chloride ions in the product, which are difficult to remove to semiconductor-grade trace levels using conventional purification methods. Furthermore, using metal hydrides for reduction introduces additional risks of metal ion contamination, making overall impurity control extremely challenging.

[0005] The noble metal catalytic dehydrogenation coupling method uses silane gas containing Si-H bonds and diisopropylamine as raw materials. The dehydrogenation coupling reaction occurs under the action of a catalyst, with hydrogen as the only byproduct, thus avoiding the introduction of halogen atoms at the source. This route typically uses supported noble metals (such as ruthenium, rhodium, and platinum) as catalysts. However, these noble metal catalysts are extremely expensive, and separating the catalyst from the reaction liquid after the reaction is difficult, the recovery process is cumbersome, and the activity decays significantly with repeated use, resulting in high catalyst consumption costs. More importantly, this reaction uses gases with low auto-ignition points and wide explosion limits, such as silane, as the silicon source. Traditional processes operating in batch reactors pose serious safety hazards in the gas feeding and pressure control stages.

[0006] Of the two routes mentioned above, the noble metal catalytic dehydrogenation coupling method, which involves catalytic reactions, has fundamental advantages such as high atom economy and no halogen introduction. However, the existing catalyst systems have revealed the following common defects in large-scale applications: on the one hand, the noble metal catalysts used are expensive and difficult to separate and recover, which significantly increases production costs; on the other hand, the dispersion state and activity stability of the catalyst in the reaction system are poor, which directly affects the conversion rate of diisopropylamine and the selectivity of the target product, making it difficult to meet the dual standards of yield and purity for electronic-grade products. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide a supported non-precious metal single-atom catalyst and its preparation method, as well as a method for preparing diisopropylaminosilane. The supported non-precious metal single-atom catalyst provided by this invention enables the continuous, low-cost, highly selective, and high-purity preparation of diisopropylaminosilane.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a supported non-noble metal single-atom catalyst for the preparation of diisopropylaminosilane, comprising a porous carbon substrate and cobalt atoms, wherein the cobalt atoms are anchored on the porous carbon substrate in an isolated Co-N4 coordination structure; the mass fraction of cobalt atoms in the supported non-noble metal single-atom catalyst is 0.5-3.5%; the specific surface area of ​​the supported non-noble metal single-atom catalyst is 500-1500 m². 2 / g, with a pore size of 2~50nm.

[0009] This invention also provides a method for preparing the supported non-noble metal single-atom catalyst described in the above technical solution, comprising the following steps: The ZIF-67 precursor was pyrolyzed with melamine and then acid-washed to obtain a supported non-precious metal single-atom catalyst; the mass ratio of the ZIF-67 precursor to melamine was 1:2~5.

[0010] Preferably, the pyrolysis conditions include: a heating rate of 5~10℃ / min, a holding temperature of 800~1000℃, a holding time of 2~4h, and a protective atmosphere for pyrolysis.

[0011] Preferably, the concentration of the acid solution used for pickling is 0.5~1 mol / L; and the pickling time is 2~3 hours.

[0012] Preferably, the ZIF-67 precursor is prepared from a cobalt source and dimethylimidazole.

[0013] This invention also provides a method for preparing diisopropylaminosilane, comprising the following steps: loading a catalyst into a fixed-bed reaction zone of a microchannel reactor, introducing a silane-carrier gas mixture and dried diisopropylamine, and carrying out a continuous dehydrogenation coupling reaction to obtain diisopropylaminosilane; wherein the catalyst is a supported non-precious metal single-atom catalyst as described in the above technical solution or a supported non-precious metal single-atom catalyst prepared by the preparation method described in the above technical solution.

[0014] Preferably, the packing density of the supported non-precious metal single-atom catalyst is 0.8~1.2 g / cm³. 3 .

[0015] Preferably, the volume fraction of silane in the silane-carrier gas mixture is 5-15%; The molar feed ratio of silane to dried diisopropylamine is 1.05~1.2:1; The feed flow rate of the dried diisopropylamine is 1~10 mL / min.

[0016] Preferably, the conditions for the continuous dehydrogenation coupling reaction include: a reaction temperature of 40~90℃, a reaction system pressure of 0.1~0.5MPa, and a residence time of silane-carrier gas mixture and dry diisopropylamine in a catalyst-containing fixed bed reaction zone of 15~120s.

[0017] Preferably, the continuous dehydrogenation coupling reaction further includes: gas-liquid separation of the reaction mixture obtained from the continuous dehydrogenation coupling reaction, and multi-stage molecular distillation of the obtained crude liquid to obtain diisopropylaminosilane.

[0018] The present invention has the following beneficial effects: Catalyst innovation: This invention introduces for the first time a supported non-precious metal single-atom catalyst (denoted as Co-NC SACs) into the preparation reaction system of electronic-grade diisopropylaminosilane. Cobalt atoms are anchored on a porous carbon substrate in an isolated Co-N4 coordination structure, effectively replacing traditional noble metal homogeneous catalysts, achieving low-cost, high-activity, and high-selectivity catalysis, and the catalyst immobilization does not require separation and recovery.

[0019] Process Innovation: This invention uses a microchannel continuous flow fixed-bed reactor to replace the traditional batch reactor, immobilizing the Co-NC SACs catalyst in the microchannel reaction zone to achieve a continuous dehydrogenation coupling reaction between silane and diisopropylamine, effectively solving the safety hazards caused by silane accumulation, and enabling industrial continuous scale-up production.

[0020] Significantly reduced production costs: This invention uses a supported non-precious metal single-atom catalyst to replace expensive Ru and Rh precious metal complexes, reducing the cost of catalyst raw materials by more than 80%. At the same time, the catalyst has a supported structure, eliminating the need for subsequent filtration, separation and recovery steps, which greatly reduces production energy consumption and labor costs, effectively solving the core pain points of high catalyst cost and difficult recovery in existing technologies.

[0021] Significantly improved operational safety: This invention employs a microchannel continuous flow process, in which silane gas and diisopropylamine liquid come into immediate contact and react within the microchannel, achieving "instant reaction" of silane, eliminating the risk of gas accumulation, completely eliminating the safety hazards of spontaneous combustion and explosion of silane, solving the safety problems of existing batch reactors, and enabling industrial continuous scale-up production.

[0022] Higher product purity: Since no solid byproducts are generated during the reaction process, complex solid-liquid separation steps are unnecessary, effectively avoiding chloride ion residue. Furthermore, this invention employs a multi-stage molecular distillation purification process, combined with a raw material pretreatment step (i.e., drying of diisopropylamine), to further remove trace impurities. Ultimately, the product purity reaches above 4N, with the total impurity content consistently below 1 ppb, fully meeting the stringent application requirements of high-end silicon-based precursor materials in integrated circuit thin-film deposition processes.

[0023] Superior reaction efficiency and selectivity: The Co-N4 coordination structure of Co-NC SACs catalysts has extremely high catalytic activity and selectivity. Combined with the rapid mass transfer advantage of microchannel reactors, the conversion rate of diisopropylamine is ≥95% and the selectivity of target products is ≥99%, which is far higher than the conversion rate of existing precious metal routes (about 85%), significantly improving product yield and production efficiency.

[0024] The process is simple and highly applicable: the catalyst is immobilized in the reactor, which simplifies the process flow and can be adapted to different industrial production needs, making it highly practical and valuable for promotion.

[0025] The supported non-precious metal single-atom catalyst provided by this invention can realize the continuous, low-cost, highly selective and high-purity preparation of diisopropylaminosilane, effectively solving the problems of low reaction conversion rate, difficulty in removing metal / non-metal impurities and high cost in the existing electronic-grade diisopropylaminosilane preparation process. Attached Figure Description

[0026] Figure 1 The GC-MS spectrum of the electronic-grade DIAPS prepared in Example 1. Detailed Implementation

[0027] This invention provides a supported non-noble metal single-atom catalyst for the preparation of diisopropylaminosilane, comprising a porous carbon substrate and cobalt atoms, wherein the cobalt atoms are anchored on the porous carbon substrate in an isolated Co-N4 coordination structure; the mass fraction of cobalt atoms in the supported non-noble metal single-atom catalyst is 0.5-3.5%, which can be 1-2.5%, or 1.5-2%; the specific surface area of ​​the supported non-noble metal single-atom catalyst is 500-1500 m². 2 / g, which can be 800~1200m 2 / g; the pore size of the supported non-precious metal single-atom catalyst is 2~50nm, can be 5~45nm, can be 10~40nm, and can be further 20~30nm.

[0028] The reaction principle of the supported non-precious metal single-atom catalyst (Co-NC SACs catalyst) provided by this invention is as follows: The Co-N4 coordination structure in the Co-NC SACs catalyst has extremely high catalytic activity and selectivity, which can efficiently activate the Si-H bond in the silane molecule and the NH bond in the diisopropylamine molecule, promote the directional progress of the dehydrogenation coupling reaction, and significantly suppress side reactions (such as polysubstitution and polymerization reactions). The conversion rate of diisopropylamine is high and the selectivity of the target product is high. The microchannels of the microchannel continuous flow reactor can greatly increase the contact area of ​​the gas, liquid and solid phases, accelerate the mass transfer rate, realize the "instant reaction" of silane, effectively avoid the safety hazards caused by gas accumulation, and at the same time, the catalyst is immobilized in the reaction zone, eliminating the need for subsequent separation steps and significantly simplifying the process.

[0029] The present invention also provides a method for preparing the supported non-precious metal single-atom catalyst described in the above technical solution, comprising the following steps: pyrolyzing ZIF-67 precursor and melamine and then acid washing to obtain the supported non-precious metal single-atom catalyst; wherein the mass ratio of ZIF-67 precursor to melamine is 1:2~5.

[0030] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0031] In this invention, the mass ratio of the ZIF-67 precursor to melamine is 1:2~5, and can be 1:3~4.

[0032] In this invention, the pyrolysis conditions may include: a heating rate of 5~10℃ / min, which may be 6~9℃ / min, and may be further 7~8℃ / min; a holding temperature of 800~1000℃, which may be 850~950℃, and may specifically be 900℃; a holding time of 2~4h, which may be 2.5~3.5h, and may specifically be 3h; and a pyrolysis atmosphere of a protective atmosphere, which may specifically include helium or argon.

[0033] In this invention, the concentration of the acid solution used for pickling can be 0.5~1 mol / L, or 0.6~0.9 mol / L, or even 0.7~0.8 mol / L; the acid solution can include one or more of dilute hydrochloric acid, dilute sulfuric acid, and dilute nitric acid; the pickling time can be 2~3 hours, or 2.5~3 hours.

[0034] After the acid washing is completed, the process may further include: washing the acid-washed material with water until the washing solution is neutral, and then drying it to obtain a supported non-precious metal single-atom catalyst. In this invention, the drying temperature can be 80~100℃, specifically 90℃; the drying time can be 12~24h, specifically 15~20h; and the drying can be vacuum drying.

[0035] In this invention, the ZIF-67 precursor is prepared from a cobalt source and dimethylimidazole. Specifically, the cobalt source, dimethylimidazole, and a pure solvent are mixed and reacted to obtain the ZIF-67 precursor. In this invention, the molar ratio of the cobalt source to dimethylimidazole can be 1:4~6, or 1:4.5~5.5, specifically 1:5. In this invention, the alcohol solvent can include one or more of methanol, ethanol, and isopropanol. In this invention, the molar ratio of dimethylimidazole to the alcohol solvent can be 1g:15~35mL, or 1g:20~30mL, specifically 1g:25mL. In this invention, the reaction temperature can be room temperature (18~25℃); the reaction time can be 24~48h, or 30~40h; the reaction can be carried out under stirring conditions. After the reaction is completed, this invention may further include: solid-liquid separation of the reacted system to obtain the ZIF-67 precursor. In this invention, the solid-liquid separation may include filtration or centrifugation; the centrifugation speed may be 8000~10000 r / min, specifically 9000 r / min; the centrifugation time may be 10~15 min, specifically 12 min.

[0036] This invention also provides a method for preparing diisopropylaminosilane, comprising the following steps: loading a catalyst into a fixed-bed reaction zone of a microchannel reactor, introducing a silane-carrier gas mixture and dried diisopropylamine, and carrying out a continuous dehydrogenation coupling reaction to obtain diisopropylaminosilane; wherein the catalyst is a supported non-precious metal single-atom catalyst as described in the above technical solution or a supported non-precious metal single-atom catalyst prepared by the preparation method described in the above technical solution.

[0037] In this invention, the packing density of the supported non-noble metal single-atom catalyst can be 0.8~1.2 g / cm³. 3 It can also be 0.9~1.1 g / cm³. 3 Specifically, it can be expressed as 1g / cm 3 In this invention, the catalyst is free of voids and blockages in the fixed-bed reaction zone of the microchannel reactor, ensuring full contact between the gas, liquid, and solid phases and improving mass transfer efficiency.

[0038] In this invention, the volume fraction of silane in the silane-carrier gas mixture can be 5-15%, or 8-12%, specifically 10%. In this invention, the feed flow rate of the silane-carrier gas mixture can be 10-100 sccm, or 20-80 sccm, further 40-60 sccm, specifically 50 sccm.

[0039] In this invention, the molar feed ratio of silane to dried diisopropylamine can be 1.05~1.2:1, or even 1.1~1.15:1. In this invention, the dried diisopropylamine can be obtained by drying diisopropylamine, and the drying can be molecular sieve drying, which may include 3A molecular sieve; the water content of the dried diisopropylamine can be ≤10ppm. In this invention, the feed flow rate of the dried diisopropylamine can be 1~10mL / min, or even 2~8mL / min, or further 4~6mL / min. In this invention, the dried diisopropylamine can be stably pumped into the liquid distributor of the microchannel reactor using a high-pressure co-current pump to ensure that the dried diisopropylamine liquid is uniformly distributed in the fixed-bed reaction zone, avoiding excessively high local reaction concentrations that could lead to side reactions. In this invention, the conditions for the continuous dehydrogenation coupling reaction may include: a reaction temperature of 40-90°C, which can also be 50-80°C, further 60-70°C, and specifically 65°C; a reaction system pressure of 0.1-0.5 MPa, which can also be 0.2-0.4 MPa, and further 0.2-0.3 MPa; and a residence time of the silane-carrier gas mixture and the dry diisopropylamine in the catalyst-containing fixed-bed reaction zone (catalyst bed) of 15-120 s, which can also be 30-100 s, further 40-60 s, and specifically 45 s. In this invention, the silane-carrier gas mixture can be precisely controlled at its flow rate by a gas mass flow meter, and mixed with the dry diisopropylamine in a mixer at the microchannel inlet before being introduced into the microchannel reactor; the mixer can be a "T-type" or a "Y-type". In this invention, during the continuous dehydrogenation coupling reaction, silane gas and diisopropylamine liquid undergo a dehydrogenation coupling reaction on the surface of a supported non-precious metal single-atom catalyst in a fixed-bed reaction zone to generate diisopropylamine silane and hydrogen gas. The reaction equation is: SiH4+ (C3H7)2NH → SiH3N(C3H7)2+ H2.

[0040] This invention helps the reaction proceed fully without side reactions by controlling feed parameters (volume fraction of silane in the silane-carrier gas mixture, silane / diisopropylamine molar ratio, and diisopropylamine feed flow rate) and reaction conditions (reaction temperature, pressure, and residence time in the catalyst bed), and effectively balances reaction efficiency and safety.

[0041] After completing the continuous dehydrogenation coupling reaction, the present invention may further include: performing gas-liquid separation on the reaction mixture obtained from the continuous dehydrogenation coupling reaction, and performing multi-stage molecular distillation on the resulting crude liquid to obtain diisopropylaminosilane. In the present invention, the reaction mixture includes crude diisopropylaminosilane, hydrogen, unreacted silane, and carrier gas. In the present invention, the gas-liquid separation can be carried out in a gas-liquid separator, and the conditions for gas-liquid separation may include: a pressure of 0.1~0.2 MPa and a cooling temperature of 0~5°C; the present invention uses pressure regulation and cooling to vent hydrogen, unreacted silane, and carrier gas, wherein the unreacted silane can be recycled after being processed by a recovery device. In this invention, the multi-stage molecular distillation can be carried out in a scraped-film multi-stage molecular distillation apparatus. The conditions for the multi-stage molecular distillation can include: a distillation temperature of 80~120℃, or 90~110℃, specifically 100℃; a vacuum degree of 1~10Pa, or 2~8Pa, further 4~6Pa, specifically 5Pa; and 2~3 distillation stages. This invention removes trace amounts of combined and ionic impurities through multi-stage molecular distillation to obtain electronic-grade diisopropylaminosilane. This invention ensures the stability, repeatability, and controllability of product purity in the continuous dehydrogenation coupling reaction by controlling key process parameters such as the cobalt atomic mass fraction (0.5~3.5%) of the Co-NC SACs catalyst, the reaction temperature (40~90℃), the reaction pressure (0.1~0.5MPa), and the feed molar ratio (1.05~1.2:1).

[0042] This invention deeply integrates cutting-edge single-atom catalysis technology with continuous flow chemical processes, constructing a highly efficient combined system centered on immobilized non-precious metal single-atom catalysts (Co-NC SACs) and a microchannel continuous flow fixed-bed reactor for the dehydrogenation coupling reaction of silane and diisopropylamine. This method utilizes low-cost non-precious metal single-atom catalysts for immobilization, eliminating cumbersome catalyst separation and recovery steps, significantly reducing production costs, and achieving a diisopropylamine conversion rate of ≥95% and a target product selectivity of ≥99%. Simultaneously, the microchannel continuous flow process enables the "instant reaction" of hazardous silane gas, completely eliminating the safety hazard of large-scale gas accumulation at the source. Furthermore, this process avoids the generation of solid byproducts and chloride ion residues at the reaction source, and coupled with raw material pretreatment steps (drying of diisopropylamine) and multi-stage molecular distillation purification processes, it can stably improve product purity to above 4N, keeping the total impurities below 1 ppb. This balances the economics of large-scale production with the practicality of electronic-grade products, meeting the stringent application requirements of integrated circuits for high-end silicon-based precursor materials. By systematically optimizing reaction parameters and purification processes, this invention ensures the stability, repeatability, and controllability of product purity, ultimately meeting the stringent application requirements of integrated circuits for high-end silicon-based precursor materials with high conversion rate, high selectivity, and high purity.

[0043] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] In this invention, unless otherwise specified, the operating temperature is the ambient temperature.

[0045] Example 1 (1) Catalyst preparation: 1.2 g of cobalt nitrate hexahydrate and 2.5 g of dimethylimidazole were dissolved in 50 mL of anhydrous methanol and magnetically stirred at room temperature for 36 h. The ZIF-67 precursor was obtained by centrifugation at 9000 r / min for 12 min. The ZIF-67 precursor was mixed with 5 g of melamine and placed in a tube furnace. Under an argon protective atmosphere, the temperature was increased to 900 °C at a heating rate of 8 °C / min and pyrolyzed at a constant temperature for 3 h. The pyrolysis product was washed with 0.8 mol / L dilute hydrochloric acid for 2.5 h, filtered, and washed with deionized water until the filtrate was neutral. The product was then vacuum dried at 80 °C for 20 h to obtain the Co-NC SACs catalyst, in which the mass fraction of cobalt atoms was 1.8% and the specific surface area was 1200 m². 2 / g, cobalt atoms are uniformly dispersed in a Co-N4 coordination structure. The catalytic activity of the catalyst was then verified.

[0046] (2) Catalyst packing: Take 50g of the above Co-NC SACs catalyst and pack it evenly into the fixed bed reaction zone of the stainless steel microchannel reactor (channel diameter 2mm, fixed bed reaction zone length 50cm), with a packing density of 1.0g / cm³. 3 .

[0047] (3) Raw material pretreatment: High-purity diisopropylamine (purity 99.9%) was passed into a 3A molecular sieve dehydration device and the water content was found to be 8 ppm. The pretreated diisopropylamine was then pumped into the liquid distributor of the microchannel reactor at a flow rate of 5 mL / min using a high-pressure horizontal flow pump.

[0048] (4) Continuous dehydrogenation coupling reaction: Silane gas (purity 99.99%) and argon gas (purity 99.999%) are mixed to prepare a mixed gas of 10 vol% SiH4 and 90 vol% Ar. The total gas flow rate is controlled by a gas mass flow meter to ensure that the molar ratio of silane to diisopropylamine is 1.1:1. The mixed gas is introduced into a microchannel reactor, and the reaction temperature is precisely controlled to 65°C by a heating device. The pressure of the reaction system is controlled to 0.2 MPa by a back pressure valve. The residence time of the gas-liquid mixture in the catalyst bed is 45 seconds, and the dehydrogenation coupling reaction occurs on the surface of the Co-NC SACs catalyst.

[0049] (5) Gas-liquid separation and purification: The reaction mixture flows continuously from the microchannel reactor and enters the gas-liquid separator. After being regulated by 0.15 MPa and cooled at 3 °C, hydrogen, unreacted silane and argon are vented. The crude liquid obtained is passed into a two-stage molecular distillation apparatus. The first stage distillation temperature is 90 °C and the vacuum degree is 5 Pa. The second stage distillation temperature is 100 °C and the vacuum degree is 2 Pa to obtain electronic grade diisopropylaminosilane.

[0050] (6) Detection results of electronic-grade diisopropylaminosilane: GC-MS and ICP-MS were used for detection. The GC-MS spectrum is shown in [reference needed]. Figure 1 The diisopropylamine conversion rate reached 98.5%, the diisopropylaminosilane selectivity was 99.2%, the product purity was 99.992%, and the total impurity content was 0.85 ppb, which can meet the quality requirements of integrated circuit electronic-grade DIPAS products.

[0051] Example 2 (Catalyst Parameter Change) The only difference from Example 1 is that the amount of cobalt nitrate hexahydrate used is 0.5 g, and the mass fraction of cobalt atoms in the Co-NC SACs catalyst is 0.8%. The test results for electronic-grade diisopropylaminosilane are as follows: diisopropylamine conversion rate is 95.2%, diisopropylaminosilane selectivity is 99.0%, product purity is 99.994%, and total impurities are 0.76 ppb, meeting the requirements for electronic-grade products and verifying the effectiveness of the catalyst parameters within the preferred range.

[0052] Example 3 (Change of conditions for continuous dehydrogenation coupling reaction) The only difference from Example 1 is that the reaction temperature in step (4) is 80°C and the reaction pressure is 0.4 MPa. The test results of electronic-grade diisopropylaminosilane are as follows: the diisopropylamine conversion rate is 99.0%, the diisopropylaminosilane selectivity is 98.8%, the product purity is 99.995%, and the total impurity is 0.82 ppb, which meets the requirements of electronic-grade products and verifies the stability of the reaction conditions within the set range.

[0053] Example 4 (Change in feed molar ratio) The only difference from Example 1 is that the molar feed ratio of silane to diisopropylamine is 1.05:1 (the total flow rate of the mixed gas is adjusted to keep the diisopropylamine feed flow rate constant at 5 mL / min). The detection results for electronic-grade diisopropylamine silane are as follows: diisopropylamine conversion rate is 96.3%, diisopropylamine silane selectivity is 99.3%, product purity is 99.993%, and total impurities are 0.72 ppb, meeting the requirements for electronic-grade products and verifying the applicability of the feed parameters within the preferred range.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A supported non-noble metal single-atom catalyst for the preparation of diisopropylaminosilane, comprising a porous carbon substrate and cobalt atoms, wherein the cobalt atoms are anchored on the porous carbon substrate in an isolated Co-N4 coordination structure; the mass fraction of cobalt atoms in the supported non-noble metal single-atom catalyst is 0.5-3.5%; the specific surface area of ​​the supported non-noble metal single-atom catalyst is 500-1500 m². 2 / g, with a pore size of 2~50nm.

2. The method for preparing the supported non-noble metal single-atom catalyst according to claim 1, characterized in that, Includes the following steps: The ZIF-67 precursor was pyrolyzed with melamine and then acid-washed to obtain a supported non-precious metal single-atom catalyst; the mass ratio of the ZIF-67 precursor to melamine was 1:2~5.

3. The preparation method according to claim 2, characterized in that, The pyrolysis conditions include: a heating rate of 5~10℃ / min, a holding temperature of 800~1000℃, a holding time of 2~4h, and a protective atmosphere for pyrolysis.

4. The preparation method according to claim 2, characterized in that, The concentration of the acid solution used for pickling is 0.5~1 mol / L; the pickling time is 2~3 hours.

5. The preparation method according to claim 2, characterized in that, The ZIF-67 precursor was prepared from a cobalt source and dimethylimidazole.

6. A method for preparing diisopropylaminosilane, characterized in that, Includes the following steps: The catalyst is packed into the fixed-bed reaction zone of a microchannel reactor, and a mixture of silane-carrier gas and dry diisopropylamine is introduced to carry out a continuous dehydrogenation coupling reaction to obtain diisopropylaminosilane; the catalyst is the supported non-precious metal single-atom catalyst according to claim 1 or the supported non-precious metal single-atom catalyst prepared by the preparation method according to any one of claims 2 to 5.

7. The preparation method according to claim 6, characterized in that, The packed density of the supported non-precious metal single-atom catalyst is 0.8~1.2 g / cm³. 3 .

8. The preparation method according to claim 6, characterized in that, The volume fraction of silane in the silane-carrier gas mixture is 5-15%; The molar feed ratio of silane to dried diisopropylamine is 1.05~1.2:1; The feed flow rate of the dried diisopropylamine is 1~10 mL / min.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The conditions for the continuous dehydrogenation coupling reaction include: a reaction temperature of 40~90℃, a reaction system pressure of 0.1~0.5MPa, and a residence time of silane-carrier gas mixture and dry diisopropylamine in a catalyst-containing fixed bed reaction zone of 15~120s.

10. The preparation method according to claim 9, characterized in that, The continuous dehydrogenation coupling reaction further includes: gas-liquid separation of the reaction mixture obtained from the continuous dehydrogenation coupling reaction, and multi-stage molecular distillation of the crude liquid obtained to obtain diisopropylaminosilane.

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