Method and system for synthesizing electronic-grade trimethylsilane

Abstract

The invention provides a synthesis method of electronic-grade trimethylsilane. The synthesis method comprises the following steps: (1) removing water from a solvent: removing water from the solvent by adopting a molecular sieve; (2) hydrogenation reduction reaction: adding the dewatered solvent and the reducing agent into trimethylchlorosilane, carrying out hydrogenation reduction reaction on trimethylchlorosilane, and controlling the stirring rate and the reaction temperature of a reactor to generate trimethylsilane; and (3) rectification and purification: cooling the trimethylsilane generated by the reaction, collecting the trimethylsilane, and removing light and heavy component impurities to obtain the electronic-grade trimethylsilane. The electronic-grade trimethylsilane synthesis system comprises a solvent tank, a solid feeder, a reactor, a collecting tank, a settling tank and a purifying tower. The trimethylsilane reaction conversion rate reaches 82% or above, and the rectification purity reaches 99.99% or above.

Description

Technical Field

[0001] The present application belongs to the technical field of electronic special gases, and relates to a method for preparing trimethylsilane, and specifically to a method and system for synthesizing electronic-grade trimethylsilane. Background Art

[0002] In recent years, trimethylsilane ((CH3)3SiH) is used as a film-forming raw material between semiconductor layers. It is mainly used as a silicon source gas for chemical vapor deposition when manufacturing thin-film dielectrics of semiconductor devices. It can deposit silicon carbide, silicon oxide or silicon nitride on thin-film dielectrics. It is an important raw material for the plasma enhanced chemical vapor deposition (PECVD) industry. It is commonly used in PECVD protective coatings and PECVD processes for low-K dielectric layers and barrier layers in inlay metallization applications. Chemicals used in the semiconductor field have very high requirements for their purity. The organic purity must reach 99.99%, and the inorganic purity is as high as 7N (99.99999%), so it is called electronic grade trimethylsilane. At present, there is no production in China, and the demand relies heavily on imports.

[0003] There are very few reports on the preparation of trimethylsilane. According to patent reports, trimethylsilane is generally prepared by reducing trimethylchlorosilane with a suitable hydrogenating agent, such as a synthesis method of rearranging the reaction of trimethylchlorosilane and lithium aluminum hydride in ethylene glycol dimethyl ether (DME) solvent. As a common raw material in these synthesis methods, trimethylchlorosilane is usually contaminated by impurities such as SiCl4. When these impurities react with the hydrogenating agent, the corresponding silane, methyltrichlorosilane, dimethyldichlorosilane, and dimethylsilane are generated. The contamination of trimethylsilane by these silane series impurities greatly increases the difficulty of subsequent purification.

[0004] In recent years, the demand for high-purity film-forming raw materials for semiconductors has been increasing, and the use of synthetic trimethylsilane as a semiconductor precursor material must reduce the content of these impurities. As a method for removing these impurities, distillation operations are generally used for refining. In the case of using the most commonly used distillation apparatus, it is necessary to provide a distillation tower with a large number of stages to completely remove dimethylsilane, which has a boiling point relatively close to trimethylsilane, resulting in increased costs. In addition, when trying to completely remove a small amount of impurities with a boiling point close to trimethylsilane by distillation, the loss of the product increases, resulting in a decrease in yield. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for synthesizing electronic grade trimethylsilane. The method and system utilize the reaction of trimethylchlorosilane, purify and refine trimethylsilane through secondary distillation, and achieve continuous reaction through solvent recovery. The reaction conversion rate reaches 82%, and the distillation purity reaches more than 99.99%.

[0006] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0007] A method for synthesizing electronic grade trimethylsilane comprises the following steps:

[0008] (1) Solvent dehydration: The molecular sieve used is used to dehydrate the solvent;

[0009] (2) hydrogenation reduction reaction: adding the dehydrated solvent and the reducing agent to trimethylchlorosilane to carry out a hydrogenation reduction reaction of the trimethylchlorosilane, controlling the stirring rate and the reaction temperature of the reactor to generate trimethylsilane;

[0010] (3) Distillation and purification: The trimethylsilane generated by the reaction is cooled and collected, and then the light and heavy impurities are removed to obtain electronic grade trimethylsilane.

[0011] Preferably, the molecular sieve used in step (1) is 4A molecular sieve, which is activated at 200° C. for more than 48 hours and then placed in a solvent, wherein the 4A molecular sieve accounts for 20% of the volume of the added solvent;

[0012] The solvent used is one of diethylene glycol dimethyl ether, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, and methyl tert-butyl ether;

[0013] After adding 4A molecular sieve, the container containing the solvent is evacuated and filled with nitrogen for protection, and left to stand for more than 24 hours, and then pressed into the reactor with a nitrogen pressure of 0.1MPa; the nitrogen purity is not less than 99.99%, and the nitrogen water content is less than 1ppm.

[0014] Preferably, the reducing agent used in step (2) is one of lithium aluminum hydride, sodium aluminum hydride, and sodium hydride. The reducing agent is introduced into the reactor containing trimethylsilane through the dewatered solvent, and stirring is started at a stirring speed of 300-500 r / min, a reaction temperature of 40-60° C., and a reaction time of 2-4 hours; the water content in the reactor is less than 1 ppm, and the oxygen content is less than 1 ppm.

[0015] Preferably, the purity of trimethylsilyl chloride used in step (2) is 99.5-99.0%, and trimethylsilyl chloride is pumped into the trimethylsilane reactor by a metering pump at a flow rate of 200-500 g / h;

[0016] The mass ratio of the solvent, reducing agent and trimethylchlorosilane for removing water in step (2) is 50:1 to 1.25:2.

[0017] Preferably, the trimethylsilane gas generated in step (2) is cooled to 20° C. by helium bubbling and then collected, the trimethylsilane production rate is 0.12 to 0.2 g / h, and the production time is 2 to 4 h.

[0018] Preferably, the light component removal conditions in step (3) are: feed rate of 1.0 to 1.5 kg / h, refrigerant temperature of -30 to -20°C, distillation pressure of 0.25 MPa to 0.3 MPa, distillation temperature of 30°C to 45°C, and the light components removed include hydrogen, oxygen, nitrogen, silane and hydrogen chloride;

[0019] The conditions for deweighting are: feed rate of 0.8-1.2 kg / h, refrigerant temperature of -20°C--15°C, distillation pressure of 0.2 MPa-0.25 MPa, distillation temperature of 10-30°C, and the removed heavy components include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide.

[0020] Preferably, the method further comprises step (4) solvent recovery: the solid impurities in the solvent are initially separated after the solvent in the reactor enters the settling tank, and then enters the solvent purification tower for further purification and separation.

[0021] Preferably, in step (4), the residue in the reactor is transferred to a settling tank for preliminary separation of insoluble solid impurities, and the settling time is not less than 24 hours. The residue contains solvent, trimethylchlorosilane and trimethylsilane liquid impurities, and LiCl and AlCl3 insoluble solid impurities; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation.

[0022] Preferably, the further purification and separation conditions in step (4) are: a feed rate of about 1.0 kg / h, a refrigerant temperature of 50°C to 150°C, a distillation pressure of 0.1 MPa to 0.15 MPa, a distillation temperature of 80 to 160°C, light components including trimethylchlorosilane and trimethylsilane are removed from the top of the tower, the condensed reflux solvent at the top of the tower is recycled into a solvent tank, and the insoluble solid impurities of LiCl and AlCl3 are removed from the bottom of the tower.

[0023] An electronic-grade trimethylsilane synthesis system comprises a solvent tank, a solid feeder, a reactor, a collecting tank, a settling tank and a purification tower, wherein the solvent tank comprises an upper feed port of the solvent tank, a lower feed port of the solvent tank and a discharge port of the solvent tank, the solid feeder comprises a solid feeder feed port and a solid feeder discharge port, the reactor comprises a reactor feed port, a reactor top discharge port and a reactor bottom discharge port, the settling tank comprises a settling tank feed port and a settling tank discharge port, and the purification tower comprises a purification tower feed port, a purification tower top discharge port and a purification tower bottom discharge port;

[0024] The discharge port of the solvent tank is connected to the feed port of the solid feeder, the discharge port of the solid feeder is connected to the feed port of the reactor, the discharge port on the top of the reactor is connected to the collecting tank, and the collecting tank is connected to the light removal tower, the heavy removal tower and the cylinder in sequence; a shell and tube heat exchanger is arranged between the discharge port on the top of the reactor and the collecting tank, a condenser is arranged on the top of the collecting tank, and an agitator is arranged in the reactor;

[0025] The bottom discharge port of the reactor is connected to the feed port of the purification tower, and the top discharge port of the purification tower is connected to the bottom feed port of the solvent tank. A condenser is arranged between the top discharge port of the purification tower and the bottom feed port of the solvent tank.

[0026] In summary, the beneficial effects of the present invention are as follows:

[0027] 1. The present invention provides a method for synthesizing electronic grade trimethylsilane. The method selects one of diethylene glycol dimethyl ether, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether and methyl tert-butyl ether as a reaction solvent, and performs water removal treatment through an activated molecular sieve, thereby providing a strong polar solvent environment required for the reaction, effectively increasing the reaction rate, and avoiding the reaction of trimethylchlorosilane with water, thereby reducing the generation of side reactions.

[0028] 2. The present invention provides a method for synthesizing electronic grade trimethylsilane. The method uses trimethylchlorosilane with a purity of 95-99% as a raw material, and one of lithium aluminum hydride, sodium aluminum hydride, and sodium hydride as a reducing agent. The selection of raw materials can effectively reduce the occurrence of side reactions, thereby improving the conversion rate of trimethylsilane and reducing the generation of side reactions. In addition, the hydrogenation reduction reaction is typical and has the characteristics of high safety.

[0029] 3. The synthesis and purification process of the present invention is scientific and reasonable, safe and environmentally friendly, and has high purification efficiency. It can ultimately obtain crude trimethylsilane with a synthesis conversion rate of 82% or more. After purification, 99.99% of trimethylsilane fine products can be obtained, which fully meets the production needs of electronic gases.

[0030] 4. The present invention can realize the recovery and reuse of the solvent through the solvent recovery process, so as to achieve the purpose of continuous reaction, thereby reducing the cost of raw materials and improving the output efficiency of trimethylsilane, and has important industrial application value.

[0031] 5. The reaction conversion rate of trimethylsilane of the present invention reaches 82%, and the distillation purity reaches more than 99.99%. The present invention can effectively increase the reaction rate, and through solvent recovery, the reaction can be continuously carried out, thereby improving the output efficiency of trimethylsilane; at the same time, it avoids the reaction of trimethylchlorosilane with water, which can effectively reduce the occurrence of side reactions, thereby improving the conversion rate of trimethylsilane. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow chart of the present invention;

[0033] Explanation of the reference numerals: 1-solvent tank, 2-solid feeder, 3-reactor, 4-collecting tank, 5-sedimentation tank, 6-purification tower, 7-shell heat exchanger, 8-condenser, 9-light-removal tower, 10-heavy-removal tower, 11-steel cylinder, 12-aggregate. DETAILED DESCRIPTION

[0034] The following is combined with Figure 1 The present invention is further described with examples:

[0035] Device Embodiment

[0036] like Figure 1 As shown, an electronic grade trimethylsilane synthesis system comprises a solvent tank 1, a solid feeder 2, a reactor 3, a collecting tank 4, a settling tank 5 and a purification tower 6, wherein the solvent tank 1 comprises an upper feed port of the solvent tank, a lower feed port of the solvent tank and a discharge port of the solvent tank, the solid feeder 2 comprises a solid feeder feed port and a solid feeder discharge port, the reactor 3 comprises a reactor feed port, a reactor top discharge port and a reactor bottom discharge port, the settling tank 5 comprises a settling tank feed port and a settling tank discharge port, and the purification tower 6 comprises a purification tower feed port, a purification tower top discharge port and a purification tower bottom discharge port;

[0037] The discharge port of the solvent tank is connected to the feed port of the solid feeder, the discharge port of the solid feeder is connected to the feed port of the reactor, the discharge port at the top of the reactor is connected to the collecting tank, and the collecting tank 4 is connected to the light removal tower 9, the heavy removal tower 10 and the cylinder 11 in sequence; a shell and tube heat exchanger 7 is arranged between the discharge port at the top of the reactor and the collecting tank, a condenser 8 is arranged on the top of the collecting tank 4, and an agitator 12 is arranged in the reactor 3;

[0038] The bottom discharge port of the reactor is connected to the feed port of the purification tower, and the top discharge port of the purification tower is connected to the bottom feed port of the solvent tank. A condenser 8 is arranged between the top discharge port of the purification tower and the bottom feed port of the solvent tank.

[0039] Examples 1 to 5 all adopt the system in the equipment example.

[0040] Example 1

[0041] (1) 6.25 kg of 4A molecular sieve was activated at a high temperature of 200° C. for more than 48 hours and then placed in a solvent tank;

[0042] (2) Add 25 kg of diethylene glycol dimethyl ether to a solvent tank, evacuate the tank, fill it with nitrogen for protection, and let it stand for more than 24 hours to remove a small amount of water in the diethylene glycol dimethyl ether; add lithium aluminum hydride to a solid feeder, with a water content of less than 1 ppm and an oxygen content of less than 1 ppm, and add 0.20 kg of lithium aluminum hydride;

[0043] (3) The dissolving tank is filled with nitrogen to 0.1 MPa, and the diethylene glycol dimethyl ether with water removed is used to bring the reducing agent in the solid feeder into the trimethylsilane reactor by pressure, and stirring is started. The solvent dosage is 10 kg;

[0044] (4) 0.20 kg of trimethylchlorosilane was pumped into the trimethylsilane reactor through a metering pump, the flow rate was controlled at 200 g / h, the reactor was stirred at 300 r / min, the reaction temperature was 60° C., and the reaction was carried out for 2 hours;

[0045] (5) The generated trimethylsilane gas is taken out by helium bubbling, cooled to 20°C by a shell-and-tube heat exchanger, and then enters a collection tank with a condenser. The trimethylsilane production rate is 0.12 g / h, and the reaction time is 2 h;

[0046] (6) The trimethylsilane in the collection tank is fed into a light-removal tower through a pipeline. The light-removal conditions are as follows: a feed rate of 1.0 kg / h, a refrigerant temperature of -25°C, a distillation pressure of 0.25 MPa, and a distillation temperature of 30 to 35°C. The light components removed include hydrogen, oxygen, nitrogen, silane, and hydrogen chloride.

[0047] (7) After the light components are removed, the trimethylsilane is then fed into a de-weighting tower. The heavy components removed include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide. The feed rate is 1.0 kg / h, the refrigerant temperature is -20°C, the distillation pressure is 0.2 MPa, and the distillation temperature is 10-20°C. After the de-weighting is completed, the product is loaded into a steel cylinder. The purity of trimethylsilane is tested to be 99.99%, and the conversion rate of the synthesis reaction of trimethylsilane is 85%.

[0048] (8) After the reaction is completed, the residue in the reactor is transferred to a sedimentation tank for a sedimentation time of not less than 24 hours, mainly to remove insoluble solid impurities such as LiCl and AlCl3; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation. The purification conditions are: feed rate of about 1.0 kg / h, refrigerant temperature of 50°C to 150°C, distillation pressure of 0.1 MPa to 0.15 MPa, and distillation temperature of 80 to 160°C; the light components removed from the top of the tower include a small amount of trimethylchlorosilane and trimethylsilane, and the heavy components removed from the bottom of the tower include a small amount of LiCl and AlCl3. The condensed reflux solvent at the top of the tower enters the solvent tank for recycling and reuse.

[0049] Example 2

[0050] (1) 5.0 kg of 4A molecular sieve was activated at a high temperature of 200° C. for more than 48 hours and then placed in a solvent tank;

[0051] (2) Add 20 kg of 2-methyltetrahydrofuran to a solvent tank, evacuate the tank, fill it with nitrogen for protection, and let it stand for more than 24 hours to remove a small amount of water in the 2-methyltetrahydrofuran; add lithium aluminum hydride to a solid feeder, with a water content of less than 1 ppm and an oxygen content of less than 1 ppm, and add 0.25 kg of lithium aluminum hydride;

[0052] (3) The dissolving tank is filled with nitrogen to 0.1 MPa, and the 2-methyltetrahydrofuran with water removed is used to bring the reducing agent in the solid feeder into the trimethylsilane reactor by pressure, and stirring is started. The solvent dosage is 10 kg;

[0053] (4) 0.25 kg of trimethylsilyl chloride was pumped into the trimethylsilane reactor through a metering pump, the flow rate was controlled at 200 g / h, the reactor was stirred at 350 r / min, the reaction temperature was 50° C., and the reaction was carried out for 2 hours;

[0054] (5) The generated trimethylsilane gas is taken out by helium bubbling, cooled to 20°C by a shell-and-tube heat exchanger, and then enters a collection tank with a condenser. The trimethylsilane production rate is 0.15 g / h, and the reaction time is 2 h;

[0055] (6) The trimethylsilane in the collection tank is fed into a light-removal tower through a pipeline. The light-removal conditions are as follows: a feed rate of 1.0 kg / h, a refrigerant temperature of -25°C, a distillation pressure of 0.25 MPa, and a distillation temperature of 30 to 35°C. The light components removed include hydrogen, oxygen, nitrogen, silane, and hydrogen chloride.

[0056] (7) After the light components are removed, the trimethylsilane is then fed into a de-weighting tower. The heavy components removed include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide. The feed rate is 1.0 kg / h, the refrigerant temperature is -20°C, the distillation pressure is 0.2 MPa, and the distillation temperature is 10-20°C. After the de-weighting is completed, the product is loaded into a steel cylinder. The purity of trimethylsilane is tested to be 99.99%, and the conversion rate of the synthesis reaction of trimethylsilane is 84%.

[0057] (8) After the reaction is completed, the residue in the reactor is transferred to a sedimentation tank for a sedimentation time of not less than 24 hours, mainly to remove insoluble solid impurities such as LiCl and AlCl3; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation. The purification conditions are: feed rate of about 1.0 kg / h, refrigerant temperature of 50°C to 150°C, distillation pressure of 0.1 MPa to 0.15 MPa, and distillation temperature of 80 to 160°C; the light components removed from the top of the tower include a small amount of trimethylchlorosilane and trimethylsilane, and the heavy components removed from the bottom of the tower include a small amount of LiCl and AlCl3. The condensed reflux solvent at the top of the tower enters the solvent tank for recycling and reuse.

[0058] Example 3

[0059] (1) 5.0 kg of 4A molecular sieve was activated at a high temperature of 200° C. for more than 48 hours and then placed in a solvent tank;

[0060] (2) Add 20 kg of ethylene glycol dimethyl ether to a solvent tank, evacuate the tank, fill it with nitrogen for protection, and let it stand for more than 24 hours to remove a small amount of water in the ethylene glycol dimethyl ether; add lithium aluminum hydride to a solid feeder, with a water content of less than 1 ppm and an oxygen content of less than 1 ppm, and add 0.30 kg of lithium aluminum hydride;

[0061] (3) The dissolving tank is filled with nitrogen to 0.1 MPa, and the ethylene glycol dimethyl ether with water removed is used to bring the reducing agent in the solid feeder into the trimethylsilane reactor by pressure, and stirring is started. The solvent dosage is 10 kg;

[0062] (4) 0.20 kg of trimethylchlorosilane was pumped into the trimethylsilane reactor through a metering pump, the flow rate was controlled to 300 g / h, the reactor was stirred at 300 r / min, the reaction temperature was 45° C., and the reaction was carried out for 2.5 hours;

[0063] (5) The generated trimethylsilane gas is taken out by helium bubbling, cooled to 20°C by a shell-and-tube heat exchanger, and then enters a collection tank with a condenser. The trimethylsilane production rate is 0.15 g / h, and the reaction time is 2 h;

[0064] (6) The trimethylsilane in the collection tank is fed into a light-removal tower through a pipeline. The light-removal conditions are as follows: a feed rate of 1.0 kg / h, a refrigerant temperature of -25°C, a distillation pressure of 0.28 MPa, and a distillation temperature of 30 to 35°C. The light components removed include hydrogen, oxygen, nitrogen, silane, and hydrogen chloride.

[0065] (7) After the light components are removed, the trimethylsilane is then fed into a de-weighting tower, and the heavy components removed include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide. The feed rate is 1.0 kg / h, the refrigerant temperature is -20°C, the distillation pressure is 0.25 MPa, and the distillation temperature is 10-20°C. After the de-weighting is completed, the product is loaded into a steel cylinder. The purity of trimethylsilane is tested to be 99.99%, and the conversion rate of the synthesis reaction of trimethylsilane is 83.5%.

[0066] (8) After the reaction is completed, the residue in the reactor is transferred to a sedimentation tank for a sedimentation time of not less than 24 hours, mainly to remove insoluble solid impurities such as LiCl and AlCl3; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation. The purification conditions are: feed rate of about 1.0 kg / h, refrigerant temperature of 50°C to 150°C, distillation pressure of 0.1 MPa to 0.15 MPa, and distillation temperature of 80 to 160°C; the light components removed from the top of the tower include a small amount of trimethylchlorosilane and trimethylsilane, and the heavy components removed from the bottom of the tower include a small amount of LiCl and AlCl3. The condensed reflux solvent at the top of the tower enters the solvent tank for recycling and reuse.

[0067] Example 4

[0068] (1) 6.25 kg of 4A molecular sieve was activated at a high temperature of 200° C. for more than 48 hours and then placed in a solvent tank;

[0069] (2) Add 25 kg of diethylene glycol dimethyl ether to a solvent tank, evacuate the tank, fill it with nitrogen for protection, and let it stand for more than 24 hours to remove a small amount of water in the diethylene glycol dimethyl ether; add lithium aluminum hydride to a solid feeder, with a water content of less than 1 ppm and an oxygen content of less than 1 ppm, and add 0.25 kg of lithium aluminum hydride;

[0070] (3) The dissolving tank is filled with nitrogen to 0.1 MPa, and the diethylene glycol dimethyl ether with water removed is used to bring the reducing agent in the solid feeder into the trimethylsilane reactor by pressure, and stirring is started. The solvent dosage is 10 kg;

[0071] (4) 0.20 kg of trimethylchlorosilane was pumped into the trimethylsilane reactor through a metering pump, the flow rate was controlled to 300 g / h, the reactor was stirred at 400 r / min, the reaction temperature was 60° C., and the reaction was carried out for 2 hours;

[0072] (5) The generated trimethylsilane gas is taken out by helium bubbling, cooled to 20°C by a shell-and-tube heat exchanger, and then enters a collection tank with a condenser. The trimethylsilane production rate is 0.12 g / h, and the reaction time is 2 h;

[0073] (6) The trimethylsilane in the collection tank is fed into a light-removal tower through a pipeline. The light-removal conditions are as follows: a feed rate of 1.0 kg / h, a refrigerant temperature of -25°C, a distillation pressure of 0.27 MPa, and a distillation temperature of 30 to 35°C. The light components removed include hydrogen, oxygen, nitrogen, silane, and hydrogen chloride.

[0074] (7) After the light components are removed, the trimethylsilane is then fed into a de-weighting tower. The heavy components removed include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide. The feed rate is 1.0 kg / h, the refrigerant temperature is -20°C, the distillation pressure is 0.24 MPa, and the distillation temperature is 10-20°C. After the de-weighting is completed, the product is loaded into a steel cylinder. The purity of trimethylsilane is tested to be 99.99%, and the conversion rate of the synthesis reaction of trimethylsilane is 83.6%.

[0075] (8) After the reaction is completed, the residue in the reactor is transferred to a sedimentation tank for a sedimentation time of not less than 24 hours, mainly to remove insoluble solid impurities such as LiCl and AlCl3; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation. The purification conditions are: feed rate of about 1.0 kg / h, refrigerant temperature of 50°C to 150°C, distillation pressure of 0.1 MPa to 0.15 MPa, and distillation temperature of 80 to 160°C; the light components removed from the top of the tower include a small amount of trimethylchlorosilane and trimethylsilane, and the heavy components removed from the bottom of the tower include a small amount of LiCl and AlCl3. The condensed reflux solvent at the top of the tower enters the solvent tank for recycling and reuse.

[0076] Example 5

[0077] (1) 6.25 kg of 4A molecular sieve was activated at a high temperature of 200° C. for more than 48 hours and then placed in a solvent tank;

[0078] (2) Add 25 kg of diethylene glycol dimethyl ether to a solvent tank, evacuate the tank, fill it with nitrogen for protection, and let it stand for more than 24 hours to remove a small amount of water in the diethylene glycol dimethyl ether; add lithium aluminum hydride to a solid feeder, with a water content of less than 1 ppm and an oxygen content of less than 1 ppm, and add 0.30 kg of lithium aluminum hydride;

[0079] (3) The dissolving tank is filled with nitrogen to 0.1 MPa, and the diethylene glycol dimethyl ether with water removed is used to bring the reducing agent in the solid feeder into the trimethylsilane reactor by pressure, and stirring is started. The solvent dosage is 15 kg;

[0080] (4) 0.24 kg of trimethylchlorosilane was pumped into the trimethylsilane reactor through a metering pump, the flow rate was controlled to 300 g / h, the reactor was stirred at 400 r / min, the reaction temperature was 55° C., and the reaction was carried out for 3 hours;

[0081] (5) The generated trimethylsilane gas 5 is taken out by helium bubbling, cooled to 20° C. through a shell-and-tube heat exchanger, and then enters a collection tank with a condenser. The trimethylsilane production rate is 0.15 g / h, and the reaction time is 2 h.

[0082] (6) The trimethylsilane in the collection tank is fed into a light-removal tower through a pipeline. The light-removal conditions are as follows: a feed rate of 1.0 kg / h, a refrigerant temperature of -25°C, a distillation pressure of 0.27 MPa, and a distillation temperature of 30 to 35°C. The light components removed include hydrogen, oxygen, nitrogen, silane, and hydrogen chloride.

[0083] (7) After the light components are removed, the trimethylsilane is then fed into a de-weighting tower. The heavy components removed include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide. The feed rate is 1.0 kg / h, the refrigerant temperature is -20°C, the distillation pressure is 0.24 MPa, and the distillation temperature is 10-20°C. After the de-weighting is completed, the product is loaded into a steel cylinder. The purity of trimethylsilane is tested to be 99.99%, and the conversion rate of the synthesis reaction of trimethylsilane is 82%.

[0084] (8) After the reaction is completed, the residue in the reactor is transferred to a sedimentation tank for a sedimentation time of not less than 24 hours, mainly to remove insoluble solid impurities such as LiCl and AlCl3; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation. The purification conditions are: feed rate of about 1.0 kg / h, refrigerant temperature of 50°C to 150°C, distillation pressure of 0.1 MPa to 0.15 MPa, and distillation temperature of 80 to 160°C; the light components removed from the top of the tower include a small amount of trimethylchlorosilane and trimethylsilane, and the heavy components removed from the bottom of the tower include a small amount of LiCl and AlCl3. The condensed reflux solvent at the top of the tower enters the solvent tank for recycling and reuse.

Claims

1. A method for synthesizing electronic grade trimethylsilane, characterized in that: The following steps are involved: (1) Solvent dehydration: The molecular sieve used is used to dehydrate the solvent; (2) hydrogenation reduction reaction: adding the dehydrated solvent and the reducing agent to trimethylchlorosilane to carry out a hydrogenation reduction reaction of the trimethylchlorosilane, controlling the stirring rate and the reaction temperature of the reactor to generate trimethylsilane; (3) Distillation and purification: The trimethylsilane generated by the reaction is cooled and collected, and then the light and heavy impurities are removed to obtain electronic grade trimethylsilane.

2. A method for synthesizing electronic grade trimethylsilane as claimed in claim 1, characterized in that: The molecular sieve used in step (1) is 4A molecular sieve, which is activated at 200° C. for more than 48 hours and then placed in a solvent, wherein the 4A molecular sieve accounts for 20% of the volume of the added solvent; The solvent used is one of diethylene glycol dimethyl ether, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, and methyl tert-butyl ether; After adding 4A molecular sieve, the container containing the solvent was evacuated and filled with nitrogen for protection, and then allowed to stand for more than 24 hours, and then pressed into the reactor with a nitrogen pressure of 0.1 MPa; The purity of nitrogen is not less than 99.99%, and the water content of nitrogen is less than 1ppm.

3. The method for synthesizing electronic grade trimethylsilane according to claim 1, characterized in that: The reducing agent used in step (2) is one of lithium aluminum hydride, sodium aluminum hydride and sodium hydride. The reducing agent is introduced into the reactor containing trimethylsilane through the dewatered solvent, and stirring is started at a stirring speed of 300-500 r / min, a reaction temperature of 40-60° C., and a reaction time of 2-4 hours; the water content in the reactor is less than 1 ppm, and the oxygen content is less than 1 ppm.

4. The method for synthesizing electronic grade trimethylsilane according to claim 1, characterized in that: The purity of trimethylsilyl chloride used in step (2) is 99.5-99.0%, and trimethylsilyl chloride is pumped into the trimethylsilane reactor through a metering pump at a flow rate of 200-500 g / h; The mass ratio of the solvent, reducing agent and trimethylchlorosilane for removing water in step (2) is 50:1 to 1.25:

2.

5. The method for synthesizing electronic grade trimethylsilane according to claim 1, characterized in that: The trimethylsilane gas generated in step (2) is cooled to 20° C. by helium bubbling and then collected. The trimethylsilane production rate is 0.12 to 0.2 g / h and the production time is 2 to 4 h.

6. The method for synthesizing electronic grade trimethylsilane according to claim 1, characterized in that: The light component removal conditions in step (3) are: feed rate of 1.0 to 1.5 kg / h, refrigerant temperature of -30 to -20°C, distillation pressure of 0.25 MPa to 0.3 MPa, distillation temperature of 30°C to 45°C, and the light components removed include hydrogen, oxygen, nitrogen, silane and hydrogen chloride; The conditions for deweighting are: feed rate of 0.8-1.2 kg / h, refrigerant temperature of -20°C--15°C, distillation pressure of 0.2 MPa-0.25 MPa, distillation temperature of 10-30°C, and the removed heavy components include trimethylchlorosilane, silicon tetrachloride, trichlorosilane and silicon dioxide.

7. The method for synthesizing electronic grade trimethylsilane according to claim 1, characterized in that: The method further comprises step (4) solvent recovery: the solvent in the reactor enters a settling tank, where solid impurities in the solvent are initially separated, and then enters a solvent purification tower for further purification and separation.

8. A method for synthesizing electronic grade trimethylsilane as claimed in claim 7, characterized in that: In step (4), the residue in the reactor is transferred to a settling tank for preliminary separation of insoluble solid impurities, and the settling time is not less than 24 hours. The residue contains solvent, trimethylchlorosilane and trimethylsilane liquid impurities, and LiCl and AlCl3 insoluble solid impurities; then the supernatant is pumped into a solvent purification tower through a metering pump for further purification and separation.

9. A method for synthesizing electronic grade trimethylsilane as claimed in claim 8, characterized in that: The further purification and separation conditions described in step (4) are: a feed rate of about 1.0 kg / h, a refrigerant temperature of 50°C to 150°C, a distillation pressure of 0.1 MPa to 0.15 MPa, a distillation temperature of 80 to 160°C, light components including trimethylchlorosilane and trimethylsilane are removed from the top of the tower, the condensed reflux solvent at the top of the tower is recycled into a solvent tank, and the insoluble solid impurities of LiCl and AlCl3 are removed from the bottom of the tower.

10. An electronic grade trimethylsilane synthesis system, characterized in that: It includes a solvent tank, a solid feeder, a reactor, a collecting tank, a settling tank and a purification tower, wherein the solvent tank includes an upper feed port of the solvent tank, a lower feed port of the solvent tank and a discharge port of the solvent tank, the solid feeder includes a solid feeder feed port and a solid feeder discharge port, the reactor includes a reactor feed port, a reactor top discharge port and a reactor bottom discharge port, the settling tank includes a settling tank feed port and a settling tank discharge port, and the purification tower includes a purification tower feed port, a purification tower top discharge port and a purification tower bottom discharge port; The discharge port of the solvent tank is connected to the feed port of the solid feeder, the discharge port of the solid feeder is connected to the feed port of the reactor, the discharge port on the top of the reactor is connected to the collecting tank, and the collecting tank is connected to the light removal tower, the heavy removal tower and the cylinder in sequence; a shell and tube heat exchanger is arranged between the discharge port on the top of the reactor and the collecting tank, a condenser is arranged on the top of the collecting tank, and an agitator is arranged in the reactor; The bottom discharge port of the reactor is connected to the feed port of the purification tower, and the top discharge port of the purification tower is connected to the bottom feed port of the solvent tank. A condenser is arranged between the top discharge port of the purification tower and the bottom feed port of the solvent tank.

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