Production process and production system of electronic-grade tetramethyl orthosilicate

Abstract

The invention belongs to the technical field of silicon electronic special gas synthesis, and particularly relates to a production process and a production system of electronic-grade tetramethyl orthosilicate, and the production system comprises a silicon powder pretreatment and catalyst activation system, a methanol refining system, a tetramethyl orthosilicate production and refining system, and a hydrogen purification and recovery system. Compared with the prior art, the method has the advantages that the tetramethyl orthosilicate is directly synthesized from the silicon powder and the methanol, so that the process flow is simplified, the generation of byproducts is reduced, the purity of the obtained tetramethyl orthosilicate reaches 5N, the metal ion index reaches 9N, and the tetramethyl orthosilicate can be applied to the field of high-end electronic-grade semiconductors.

Description

Technical Field

[0001] The present invention relates to a production system for electronic-grade methyl orthosilicate, belonging to the technical field of silicon-based electronic special gas synthesis. Background Art

[0002] With the rapid development of the semiconductor industry, the demand for electronic special gases used in the fields of integrated circuits, discrete devices, microelectromechanical systems, etc. continues to grow. For example, electronic-grade methyl orthosilicate, electronic-grade tetraethyl orthosilicate, etc. are used to generate a silicon dioxide deposition film on the surface of electronic components through chemical vapor deposition to form a conductive layer and an insulating layer. Therefore, extremely high purity is required, otherwise serious consequences such as short circuits of circuit boards will occur.

[0003] The existing traditional process generates methyl orthosilicate and HCl gas through the esterification reaction of silicon tetrachloride and methanol. Since there are many side reactions in the preparation process of the silicon tetrachloride method, other impurities will be generated. Therefore, the purity of the prepared methyl orthosilicate is generally low, and further complexation, adsorption, and rectification purification are required, making the process more complex and increasing the purification cost. Patent CN117186138 A discloses a purification method and a purification system for high-purity tetraethyl orthosilicate. The crude tetraethyl orthosilicate is initially adsorbed through chitosan, zeolite, and fruit shell activated carbon adsorption, and then vacuum distilled and filtered to obtain high-purity tetraethyl orthosilicate. In addition, the HCl gas generated by the traditional process not only corrodes the equipment but also participates in side reactions to generate water, further causing the hydrolysis of siloxane to form polysiloxane and chlorosilane. Since the boiling points of some chlorosilanes and siloxanes are similar, they cannot be separated by rectification, making it difficult to reach the electronic grade for the product purity.

[0004] The advantage of the direct method is that the silicon powder directly reacts with the alcohol, the process is simpler, the introduction of chlorine elements is avoided, there are fewer side reactions, and the obtained product has higher purity. Patent CN 101671028 A provides a method for preparing silane gas, Patent CN 107216348 A provides a method for preparing tetramethoxysilane by the direct method, and Patent CN 117186137 A provides a method for preparing tetraethyl orthosilicate. Although the direct method for synthesizing siloxane has been published for a long time, it is still in the laboratory stage, and no cases are provided for the purification of raw materials and products, and the obtained silane does not reach the electronic level. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a production system for electronic-grade methyl orthosilicate, which includes a full-process technology for electronic-grade methyl orthosilicate, and the produced methyl orthosilicate reaches the electronic grade.

[0006] The production system of electronic-grade methyl orthosilicate provided by the present invention includes: a silicon powder pretreatment and catalyst activation system, a methanol refining system, a methyl orthosilicate production and refining system, and a hydrogen separation and recovery system. The production system includes the following steps: S1) Production and refining of methyl orthosilicate: Silicon powder and methanol react in a kettle reactor. After the reaction, the material is discharged from the bottom of the kettle. The crude methyl orthosilicate is separated through a bag filter and fed into the middle upper part of the methanol recovery tower. After removing the unreacted methanol, it is discharged from the bottom of the tower and then fed into the middle lower part of the methyl orthosilicate refining tower. Methyl orthosilicate is obtained by condensation from the top of the tower. S2) Methanol refining system: The methanol in step S1 is filtered and then sequentially undergoes light component removal and heavy component removal to obtain high-purity methanol, which is then recycled to step S1). S3) Hydrogen purification and recovery system: In step S1, the gas drawn from the top of the kettle reactor is condensed by a gas-liquid separator, and the output gas is sent to the middle lower part of the hydrogen purification tower through a hydrogen compressor and a hydrogen heat exchanger. Hydrogen is separated from the top of the tower through a gas membrane separator.

[0007] In step S1, the silicon powder is activated by mixing with a catalyst after being pickled and washed with water.

[0008] The acid in the pickling process is selected from any one of oxalic acid, acetic acid, sulfuric acid or nitric acid, and the acid concentration is 20 - 60%. The catalyst is selected from copper, copper oxide or cuprous oxide, and the mass ratio of the catalyst to the silicon powder is (1 - 5):100.

[0009] In step S1, the mass ratio of the silicon powder to the methanol is (1 - 20):100, the temperature in the reactor is 180 - 260 °C, the reaction time is 0.5 - 6 h, the temperature of the methanol recovery tower is 60 - 80 °C, the pressure is -1 - 0 MPa, the reflux ratio is 1 - 10, the temperature of the methyl orthosilicate refining tower is 100 - 120 °C, the pressure is -1 - 0 MPa, and the reflux ratio is 1 - 10.

[0010] In step S2, the temperature of the methanol light component removal tower is 63 - 65 °C, the reflux ratio is 1 - 10, the temperature of the methanol heavy component removal tower is 64 - 66 °C, and the reflux ratio is 1 - 10.

[0011] In step S3, the hydrogen compressor pressurizes the gas to 1 - 3 MPa, the hydrogen heat exchanger reduces the gas temperature to 10 - 20 °C, the temperature of the hydrogen purification tower is -20 - 0 °C, the pressure is 1 - 3 MPa, and the reflux ratio is 1 - 5.

[0012] Another technical solution of the present invention is directed to the production system adopted for the production process, including a methyl orthosilicate production and refining system, an alcohol refining system, and a hydrogen purification and recovery system; The methyl orthosilicate production and purification system includes: a kettle reactor, a methyl orthosilicate bag filter, a crude methyl orthosilicate storage tank, a methanol recovery tower, a methyl orthosilicate purification tower, a by-product storage tank, and a high-purity methyl orthosilicate storage tank; the mixing bin and the high-purity alcohol storage tank are connected to the kettle reactor, the bottom of the kettle reactor is connected to the methyl orthosilicate bag filter, the methyl orthosilicate bag filter is connected to the crude methyl orthosilicate storage tank, the crude methyl orthosilicate storage tank is connected to the methanol recovery tower, the bottom of the methanol recovery tower is connected to the methyl orthosilicate purification tower, the bottom of the methyl orthosilicate purification tower is connected to the by-product storage tank, and the top of the methyl orthosilicate purification tower is connected to the high-purity methyl orthosilicate storage tank; The alcohol purification system includes: a methanol buffer tank, a methanol bag filter, a methanol light component removal tower, a methanol heavy component removal tower, a methanol recovery storage tank, and a high-purity methanol storage tank. The methanol buffer tank is connected to the methanol bag filter, the methanol bag filter is connected to the methanol light component removal tower, the bottom of the methanol light component removal tower is connected to the methanol heavy component removal tower, the top of the methanol heavy component removal tower is connected to the high-purity methanol storage tank, and the top of the methanol light component removal tower and the bottom of the methanol heavy component removal tower are connected to the methanol recovery storage tank.

[0013] The hydrogen purification and recovery system includes: a gas-liquid separator, a hydrogen heat exchanger, a hydrogen purification tower, a methanol recovery storage tank, and a gas membrane separator. The top of the kettle reactor is connected to the hydrogen heat exchanger through the gas-liquid separator, the hydrogen heat exchanger is connected to the hydrogen purification tower, the bottom of the hydrogen purification tower is connected to the methanol recovery storage tank, and the top of the hydrogen purification tower is connected to the gas membrane separator.

[0014] The production system also includes a silicon powder pretreatment and catalyst activation system, which includes: a ball mill, a cyclone separator, a silicon powder pickling tank, a silicon powder washing tank, a silicon powder dryer, a silicon powder bin, a catalyst bin, and a mixing bin. The ball mill is connected to the cyclone separator, the cyclone separator is connected to the silicon powder pickling tank and the catalyst bin, the silicon powder pickling tank is connected to the silicon powder washing tank, the silicon powder washing tank is connected to the silicon powder dryer, the silicon powder dryer is connected to the silicon powder bin, and the silicon powder bin is connected to the catalyst bin and communicates with the mixing bin.

[0015] The methyl orthosilicate bag filter is connected to the cyclone separator, and the top of the methanol recovery tower is connected to the methanol buffer tank.

[0016] The present invention provides a production system for electronic-grade methyl orthosilicate, comprising: a silicon powder pretreatment and catalyst activation system, a methanol refining system, a methyl orthosilicate production and refining system, and a hydrogen purification and recovery system. Compared with the prior art, the advantages and positive effects of the present invention are as follows: Methyl orthosilicate is directly synthesized from silicon powder and methanol. While ensuring the conversion rate of silicon powder and the yield of methyl orthosilicate, there are fewer side reactions, the process route is simpler, and the direct method does not produce HCl gas. After the reaction, high-purity methyl orthosilicate is obtained, and the by-product is cleaner hydrogen. By purifying the raw material methanol, the introduction of moisture and metal impurities is avoided, and the purification steps of the product methyl orthosilicate are optimized. Electronic-grade methyl orthosilicate is obtained through two-stage distillation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a process flow diagram of the production system for electronic-grade methyl orthosilicate provided by the present invention.

[0018] Figure 2 FIG. is a regional division diagram of the production system for electronic-grade methyl orthosilicate provided by the present invention.

[0019] Among them, 1 is a ball mill, 2 is a cyclone separator, 3 is a silicon powder pickling tank, 4 is a silicon powder washing tank, 5 is a silicon powder dryer, 6 is a silicon powder bin, 7 is a catalyst bin, 8 is a mixing bin, 9 is a methanol buffer tank, 10 is a methanol bag filter, 11 is a methanol light removal tower, 12 is a methanol heavy removal tower, 13 is a methanol recovery storage tank, 14 is a high-purity methanol storage tank, 15 is a kettle reactor, 16 is a methyl orthosilicate bag filter, 17 is a crude methyl orthosilicate storage tank, 18 is a methanol recovery tower, 19 is a methyl orthosilicate refining tower, 20 is a by-product storage tank, 21 is a high-purity methyl orthosilicate storage tank, 22 is a hydrogen purification tower, 23 is a gas film separator, 24 is a silicon powder feed blower, 25 is a methanol light removal tower feed pump, 26 is a methanol light removal tower top condenser, 27 is a methanol light removal tower bottom reboiler, 28 is a methanol light removal tower discharge pump, 29 is a methanol heavy removal tower top condenser, 30 is a methanol heavy removal tower bottom reboiler, 31 is a methanol heavy removal tower discharge pump, 32 is a reactor feed pump, 33 is a gas-liquid separator, 34 is a hydrogen compressor, 35 is a silicon powder recovery blower, 36 is a reactor discharge pump, 37 is a methanol recovery tower feed pump, 38 is a methanol recovery tower top condenser, 39 is a methanol recovery tower bottom reboiler, 40 is a methanol recovery tower discharge pump, 41 is a methyl orthosilicate refining tower top condenser, 42 is a methyl orthosilicate refining tower bottom reboiler, 43 is a methyl orthosilicate refining tower discharge pump, 44 is a hydrogen heat exchanger, 45 is a hydrogen purification tower feed blower, 46 is a hydrogen purification tower top condenser, 47 is a hydrogen purification tower bottom reboiler, 48 is a hydrogen purification tower discharge pump.

[0020] The present invention will be further described below in conjunction with the drawings and specific embodiments, but the protection scope of the present invention is not limited to the following embodiments. Detailed implementation mode

[0021] The technical solution of the present invention will be described in detail below.

[0022] The present invention provides a production system for electronic-grade methyl orthosilicate, including: a silicon powder pretreatment and catalyst activation system, a methanol refining system, a methyl orthosilicate production and refining system, and a hydrogen purification and recovery system.

[0023] The present invention has no restrictive requirements on the raw materials used in the whole process of the process, and they can be commercially available or self-made.

[0024] In the present invention, the silicon powder pretreatment and catalyst activation system is implemented according to the following steps: industrial silicon blocks are ball-milled, crushed and ground, and then sequentially pass through an acid washing tank, a water washing tank, and after drying, are mixed with a catalyst in a mixing bin in proportion; the industrial silicon blocks are silicon metals prepared by the high-temperature carbothermal reduction method, and the purity is generally above 99%; the ball milling is wet milling; the particle size of the ball-milled product is 40 - 500 mesh, more preferably 50 - 200 mesh; the catalyst is copper, copper oxide or cuprous oxide, preferably cuprous oxide; the acid is oxalic acid, acetic acid, sulfuric acid or nitric acid, and the concentration is 20 - 60%. Acid washing can remove most metal impurities, such as copper, manganese, iron, zinc, vanadium, etc. By pre-treating the raw materials, metal impurities are prevented from being introduced into the production system, avoiding metal ion adsorption treatment of the product methyl orthosilicate in the production system, simplifying the production steps, and the metal ion index of the obtained high-purity methyl orthosilicate reaches 9N; the mass ratio of cuprous oxide to silicon powder in the mixture is (1 - 5):100; the mixing bin also includes preheating the materials in the mixing bin, and the preheating temperature is 200 - 600 °C, preferably 300 - 500 °C, more preferably 400 °C; the preheating time is 0.1 - 3 h, preferably 0.5 - 2 h, more preferably 1 h; the purpose of preheating is to regenerate and activate cuprous oxide to ensure the catalytic efficiency of cuprous oxide.

[0025] In the present invention, the production and purification system of methyl orthosilicate is implemented according to the following steps: silicon powder reacts with methanol in a kettle reactor. After the reaction, the material is discharged from the bottom of the kettle, and the crude methyl orthosilicate is separated through a bag filter and sent to the crude methyl orthosilicate storage tank. The crude methyl orthosilicate is fed into the middle-upper part of the methanol recovery tower. After removing the unreacted methanol, it is discharged from the bottom of the tower, and then fed into the middle-lower part of the methyl orthosilicate purification tower. High-purity methyl orthosilicate is obtained by condensation at the top of the tower; the kettle reactor is equipped with a spiral agitator to stir the material during the reaction to prevent the silicon powder from settling; the top of the kettle reactor is also equipped with a solenoid valve, which is opened when the pressure in the kettle reaches a certain value; an air-liquid separator is also connected outside the solenoid valve to make the methanol reflux by condensation and discharge the gas; the kettle reactor is also equipped with an intake valve to introduce a protective gas to displace the air in the kettle after feeding; the protective gas is nitrogen or helium, preferably nitrogen; the mass ratio of the input silicon powder to methanol is (1-20):100; the temperature of the kettle reactor is 180-260 °C; the reaction time is 0.5-6 h; a discharge port is arranged at the bottom of the kettle reactor; the purpose of the methyl orthosilicate bag filter is to recover silicon powder and cuprous oxide; the methyl orthosilicate bag filter filters to obtain crude ethyl orthosilicate; the methanol recovery tower is a vacuum distillation tower; the temperature of the methanol recovery tower is 60-80 °C, the pressure is -1 to 0 MPa, the temperature of the bottom reboiler is 80-100 °C, the temperature of the top condenser is 10-40 °C, and the reflux ratio is 1-10; the methyl orthosilicate purification tower is a vacuum distillation tower; the temperature of the methyl orthosilicate purification tower is 100-120 °C, the pressure is -1 to 0 MPa, the temperature of the bottom reboiler is 120-150 °C, the temperature of the top condenser is 10-40 °C, and the reflux ratio is 1-10; the high-purity methyl orthosilicate obtained by the methyl orthosilicate production and purification system reaches 5N.

[0026] In the present invention, the methanol refining system is implemented according to the following steps: Methanol from the production process of methyl orthosilicate is first filtered to remove solid impurities, and then fed into the middle-upper part of the methanol de-light tower through a methanol feed pump. The bottom discharge is fed into the middle-lower part of the methanol de-heavy tower. The liquid condensed at the top of the methanol de-heavy tower enters a high-purity methanol storage tank, and the purity is generally above 99.5%. The liquid condensed at the top of the methanol de-light tower and the bottom residue of the methanol de-heavy tower enter a methanol recovery tank. The methanol in the production process of methyl orthosilicate entangles a small amount of impurities such as methyl orthosilicate and low-boiling by-products trimethoxysilane, ethyltrimethoxysilane, and triethylmethoxysilane. The entrained small amount of methyl orthosilicate and low-boiling by-products trimethoxysilane, ethyltrimethoxysilane, and triethylmethoxysilane are all hydrolyzable silanes, which can further contact with the water in methanol, hydrolyze to produce methanol and fumed silica, and further reduce the water content in methanol. The removed solid impurities are mainly fumed silica. The temperature of the methanol de-light tower is 63-65 °C, the temperature of the bottom reboiler is 70-90 °C, the temperature of the top condenser is 10-40 °C, and the reflux ratio of the methanol de-light tower is 1-10. The temperature of the methanol de-heavy tower is 64-66 °C, the temperature of the bottom reboiler is 70-90 °C, the temperature of the top condenser is 10-40 °C, and the reflux ratio of the methanol de-heavy tower is 1-10. The high-purity methanol obtained by the methanol refining system reaches 5N. The liquid condensed at the top of the methanol de-light tower and the bottom residue of the methanol de-heavy tower are low-boiling impurities such as formaldehyde, acetaldehyde, methyl ether, and ethyl ether.

[0027] In the present invention, the hydrogen purification and recovery system is implemented according to the following steps: The product taken out from the top of the reactor is condensed by a gas-liquid separator, and the output gas is sent to the middle-lower part of the hydrogen purification tower through a hydrogen compressor and a hydrogen heat exchanger. The product taken out from the top of the tower is separated into hydrogen by a gas membrane separator. The hydrogen compressor pressurizes the gas to 1-3 MPa. The hydrogen heat exchanger reduces the gas temperature to 10-20 °C. The temperature of the hydrogen purification tower is -20-0 °C, the pressure is 1-3 MPa, the temperature of the top condenser is -25 °C, and the reflux ratio is 1-5. The permeate gas of the gas membrane separator is hydrogen, and the non-permeate gas is nitrogen. The nitrogen continues to return to the reactor for purging air.

[0028] In order to further illustrate the present invention, the following describes in detail a production system of electronic-grade methyl orthosilicate provided by the present invention in combination with embodiments.

[0029] S1. After the industrial silicon blocks are crushed by the ball mill 1, the residue separated and recovered by the bag filter 16 of methyl orthosilicate passes through the cyclone separator 2 to separate out silicon powder and cuprous oxide. The silicon powder enters the pickling tank 3, the water washing tank 4 and the silicon powder dryer 5 and is then stored in the silicon powder bin 6, while the cuprous oxide is stored in the catalyst bin 7. The cuprous oxide and the silicon powder enter the mixing bin 8 at a mass ratio of (1 - 5):100, are preheated at 400 °C for 1 h, and then enter the autoclave reactor 15 through the 24-silicon powder feeding fan.

[0030] S2. High-purity methanol enters the autoclave reactor 15 through the reactor feed pump 32. The mass ratio of the silicon powder to the methanol feed is (1 - 20):100. After the feeding is completed, nitrogen is introduced to displace the air in the reaction kettle. The temperature of the reactor is 180 - 260 °C, and the reaction time is 0.5 - 6 h. After the reaction is completed, the temperature of the kettle body is first cooled, and then the gas in the kettle is discharged through the solenoid valve. After the gauge pressure drops to 0, the material is discharged from the bottom of the kettle and enters the bag filter 16 of methyl orthosilicate. The filtered impurities are returned to the cyclone separator 2 through the silicon powder recovery fan 35. The filtrate enters the crude methyl orthosilicate storage tank 17 through the reactor discharge pump 36, and then enters the middle and upper part of the methanol recovery tower 18 through the methanol recovery tower feed pump 37 for vacuum distillation at 60 - 80 °C under a reduced pressure of -1 - 0 MPa. The temperature of the reboiler at the bottom of the methanol recovery tower 39 is 80 - 100 °C, the temperature of the condenser at the top of the methanol recovery tower 38 is 10 - 40 °C, and the reflux ratio is 1 - 10. The unreacted methanol and low-boiling impurities are condensed and returned to the methanol buffer tank 9. The material at the bottom of the tower enters the middle and lower part of the methyl orthosilicate refining tower 19 through the methyl orthosilicate refining tower discharge pump 40 for vacuum distillation at 100 - 120 °C under a reduced pressure of -1 - 0 MPa. The temperature of the reboiler at the bottom of the methyl orthosilicate refining tower 42 is 120 - 150 °C, the temperature of the condenser at the top of the methyl orthosilicate refining tower 41 is 10 - 40 °C, and the reflux ratio is 1 - 10. The high-purity methyl orthosilicate is condensed and enters the high-purity methyl orthosilicate storage tank 21, and the high-boiling by-products at the bottom of the kettle enter the by-product storage tank 20 through the methyl orthosilicate refining tower discharge pump 43. The by-products are mainly hexamethyldisiloxane. The conversion rate of the silicon powder is greater than 90%, and the yield of methyl orthosilicate based on the silicon powder is greater than 80%.

[0031] S3. During the reaction process, the components condensed by the top condenser 38 of the methanol recovery column 18 (mainly methanol, entraining a small amount of methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, triethylmethoxysilane, etc.) enter the methanol buffer tank 9. Methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, triethylmethoxysilane, etc. react with a small amount of water contained in industrial methanol in the buffer tank to generate fumed silica. The methanol with fumed silica coming out of the methanol buffer tank 9 passes through the methanol bag filter 10 to remove the fumed silica. The separated methanol is fed into the middle-upper part of the methanol light-end tower 11 by the methanol light-end tower 26 feed pump and undergoes atmospheric distillation at 63 - 65 °C. The temperature of the bottom reboiler of the methanol light-end tower 27 is 70 - 90 °C, the temperature of the top condenser of the methanol light-end tower 26 is 10 - 40 °C, and the reflux ratio is 1 - 10. Low-boiling impurities such as formaldehyde, acetaldehyde, methyl ether, and ethyl ether in the methanol are removed by distillation. The low-boiling impurities enter the methanol recovery storage tank 13 after condensation. The bottom product is fed into the middle-lower part of the methanol heavy-end tower 12 by the methanol light-end tower bottom product pump 28 and undergoes atmospheric distillation at 64 - 66 °C. The temperature of the bottom reboiler of the methanol heavy-end tower 30 is 70 - 90 °C, the temperature of the top condenser of the methanol heavy-end tower 29 is 10 - 40 °C, and the reflux ratio is 1 - 10. High-purity methanol is condensed and enters the high-purity methanol storage tank 14. The high-boiling impurities at the bottom of the tower enter the methanol recovery storage tank 13 through the methanol heavy-end tower bottom product pump 31. The obtained high-purity methanol is reused in S2 again, achieving a methyl orthosilicate yield greater than 90%.

[0032] S4. After the reflux of methanol from the top of the reactor through the gas-liquid separator 33, hydrogen is sent to the hydrogen heat exchanger 44 by the hydrogen compressor 34 to be cooled, pressurized to 1 - 3 MPa, and cooled to 10 - 20 °C. Then, it is fed into the middle-lower part of the hydrogen purification tower 22 by the hydrogen purification tower 45 feed fan. The temperature of the purification tower is -20 - 0 °C, and the pressure is 1 - 3 MPa. The temperature of the top condenser of the hydrogen purification tower 46 is -25 °C, and the reflux ratio is 1 - 5. The top product passes through the top condenser and enters the gas film separator 23 to separate hydrogen and nitrogen. The nitrogen is recovered for air displacement in the autoclave reactor 15. The bottom product returns to the methanol recovery storage tank 13 through the hydrogen purification tower bottom product pump 48.

[0033] Example 1 S1. After the industrial silicon blocks are crushed by a ball mill, the residue separated and recovered from the methyl orthosilicate bag filter passes through a cyclone separator to separate silicon powder and cuprous oxide. The silicon powder enters the pickling tank, the water washing tank, and the silicon powder dryer and is stored in the silicon powder bin, while the cuprous oxide is stored in the catalyst bin. The cuprous oxide and the silicon powder enter the mixing bin at a mass ratio of 5:100, are preheated at 400 °C for 1 h, and then enter the autoclave reactor through the 24 silicon powder feed fan.

[0034] S2. High-purity methanol enters the autoclave reactor through the reactor feed pump. The mass ratio of silicon powder to methanol feed is 20:100. After the feeding is completed, nitrogen is introduced to displace the air in the reaction kettle. The temperature of the reactor is 200 °C, and the reaction time is 3 h. After the reaction ends, first cool the temperature of the kettle body, and then discharge the gas in the kettle through the solenoid valve. After the gauge pressure drops to 0, discharge from the bottom of the kettle and enter the methyl orthosilicate bag filter. The filtered impurities are returned to the cyclone separator through the silicon powder recovery fan. The filtrate enters the crude methyl orthosilicate storage tank through the reactor discharge pump, and then is fed into the middle and upper part of the methanol recovery tower through the methanol recovery tower feed pump. It is rectified under reduced pressure at 80 °C, with a reduced pressure of -0.1 MPa. The temperature of the reboiler at the bottom of the methanol recovery tower is 100 °C, the temperature of the condenser at the top of the methanol recovery tower is 20 °C, and the reflux ratio is 5. The unreacted methanol and low-boiling impurities are condensed and returned to the methanol buffer tank. The bottom material of the tower is fed into the middle and lower part of the methyl orthosilicate refining tower through the methanol recovery tower discharge pump. It is rectified under reduced pressure at 120 °C, with a reduced pressure of -0.1 MPa. The temperature of the reboiler at the bottom of the methyl orthosilicate refining tower is 150 °C, the temperature of the condenser at the top of the methyl orthosilicate refining tower is 20 °C, and the reflux ratio is 5. High-purity methyl orthosilicate is condensed and enters the high-purity methyl orthosilicate storage tank. The high-boiling by-products at the bottom of the kettle enter the by-product storage tank through the methyl orthosilicate refining tower discharge pump. The by-products are mainly hexamethyldisiloxane. The conversion rate of silicon powder is 92%. Based on silicon powder, the yield of methyl orthosilicate is 83%, and the purity reaches 4N.

[0035] S3. The components condensed by the condenser at the top of the methanol recovery tower (mainly methanol, entraining a small amount of methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, triethylmethoxysilane and other impurities) enter the methanol buffer tank. Methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, triethylmethoxysilane and other impurities undergo a hydrolysis reaction with a small amount of water contained in industrial methanol in the buffer tank to generate fumed silica. The methanol with fumed silica coming out of the methanol buffer tank passes through the methanol bag filter to remove fumed silica. The separated methanol is fed into the middle and upper part of the methanol light removal tower through the methanol light removal tower feed pump. It is rectified at atmospheric pressure at 65 °C. The temperature of the reboiler at the bottom of the methanol light removal tower is 90 °C, the temperature of the condenser at the top of the methanol light removal tower is 20 °C, and the reflux ratio is 5. The low-boiling impurities such as formaldehyde, acetaldehyde, methyl ether, ethyl ether and other low-boiling impurities in methanol are removed by rectification. The low-boiling impurities are condensed and enter the methanol recovery storage tank. The bottom discharge of the tower is fed into the middle and lower part of the methanol heavy removal tower through the methanol light removal tower discharge pump. It is rectified at atmospheric pressure at 66 °C. The temperature of the reboiler at the bottom of the methanol heavy removal tower is 80 °C, the temperature of the condenser at the top of the methanol heavy removal tower is 20 °C, and the reflux ratio is 5. High-purity methanol is condensed and enters the high-purity methanol storage tank. The high-boiling impurities at the bottom of the tower enter the methanol recovery storage tank through the methanol heavy removal tower discharge pump. The obtained high-purity methanol is reused in S2 again, achieving a methyl orthosilicate yield of 95.3% and a purity reaching 5N.

[0036] After the product withdrawn from the top of the reactor is refluxed with methanol through a gas-liquid separator, hydrogen is sent to a hydrogen heat exchanger through a hydrogen compressor for cooling, pressurized to 1 MPa, cooled to 10°C, and then fed into the middle and lower parts of a hydrogen purification tower through a hydrogen purification tower feed fan. The temperature of the purification tower is -20°C, and the pressure is 1 MPa. The temperature of the condenser at the top of the hydrogen purification tower is -25°C, the reflux ratio is 3, and the product withdrawn from the top enters a gas film separator through the condenser at the top to separate hydrogen and nitrogen. The nitrogen is recycled for air displacement in the autoclave reactor, and the product withdrawn from the bottom of the tower is returned to the methanol recovery storage tank through a hydrogen purification tower discharge pump.

[0037] Example 2 S1. After the industrial silicon blocks are crushed by a ball mill and the residue separated and recovered by a bag filter from methyl orthosilicate passes through a cyclone separator, silicon powder and cuprous oxide are separated. The silicon powder enters an acid washing tank, a water washing tank, and a silicon powder dryer and is then stored in a silicon powder bin, while the cuprous oxide is stored in a catalyst bin. The cuprous oxide and the silicon powder enter a mixing bin at a mass ratio of 4:100, are preheated at 400°C for 1 h, and then enter an autoclave reactor through a silicon powder feed fan.

[0038] S2. High-purity methanol enters the autoclave reactor through a reactor feed pump. The mass ratio of the silicon powder to the methanol feed is 15:100. After the feeding is completed, nitrogen is introduced to displace the air in the reaction kettle. The temperature of the reactor is 220°C, and the reaction time is 2 h. After the reaction is completed, the temperature of the kettle body is first cooled, and then the gas in the kettle is discharged through a solenoid valve. After the gauge pressure drops to 0, the product is discharged from the bottom of the kettle and enters a methyl orthosilicate bag filter. The impurities filtered out are returned to the cyclone separator through a silicon powder recovery fan. The filtrate enters a crude methyl orthosilicate storage tank through a reactor discharge pump and then is fed into the middle and upper parts of a methanol recovery tower through a methanol recovery tower feed pump. Vacuum distillation is carried out at 70°C under a reduced pressure of -0.2 MPa. The temperature of the reboiler at the bottom of the methanol recovery tower is 100°C, the temperature of the condenser at the top of the methanol recovery tower is 20°C, the reflux ratio is 6, and the unreacted methanol and low-boiling impurities are condensed and returned to a methanol buffer tank. The material at the bottom of the tower enters the middle and lower parts of a methyl orthosilicate refining tower through a methanol recovery tower discharge pump. Vacuum distillation is carried out at 100°C under a reduced pressure of -0.2 MPa. The temperature of the reboiler at the bottom of the methyl orthosilicate refining tower is 120°C, the temperature of the condenser at the top of the methyl orthosilicate refining tower is 20°C, the reflux ratio is 6, and high-purity methyl orthosilicate is condensed and enters a high-purity methyl orthosilicate storage tank. The high-boiling by-products at the bottom of the kettle enter a by-product storage tank through a methyl orthosilicate refining tower discharge pump. The by-products are mainly hexamethyldisiloxane. The conversion rate of the silicon powder is 95%. Based on the silicon powder, the yield of methyl orthosilicate is 89.5%, and the purity reaches 4N.

[0039] S3. The components condensed by the top condenser of the methanol recovery column (mainly methanol, entraining a small amount of methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, triethylmethoxysilane and other impurities) enter the methanol buffer tank. Methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, triethylmethoxysilane and other impurities undergo hydrolysis reaction with a small amount of water contained in industrial methanol in the buffer tank to generate fumed silica. The methanol with fumed silica coming out of the methanol buffer tank passes through a methanol bag filter to remove fumed silica. The separated methanol is fed into the middle-upper part of the methanol light-component removal column by the methanol light-component removal column feed pump and undergoes atmospheric distillation at 63°C. The temperature of the reboiler at the bottom of the methanol light-component removal column is 80°C, the temperature of the top condenser of the methanol light-component removal column is 20°C, and the reflux ratio is 6. Low-boiling impurities such as formaldehyde, acetaldehyde, methyl ether, and ethyl ether in the methanol are removed by distillation. The low-boiling impurities enter the methanol recovery storage tank after condensation. The bottom product is fed into the middle-lower part of the methanol heavy-component removal column by the methanol light-component removal column bottom product pump and undergoes atmospheric distillation at 64°C. The temperature of the reboiler at the bottom of the methanol heavy-component removal column is 80°C, the temperature of the top condenser of the methanol heavy-component removal column is 20°C, and the reflux ratio is 6. High-purity methanol enters the high-purity methanol storage tank after condensation. The high-boiling impurities at the bottom of the column enter the methanol recovery storage tank through the methanol heavy-component removal column bottom product pump. The obtained high-purity methanol is reused in S2 again, achieving a methyl orthosilicate yield of 93.4% and a purity reaching 5N.

[0040] S4. After the methanol is refluxed by the gas-liquid separator for the draw-off at the top of the reactor, hydrogen is sent to the hydrogen heat exchanger for cooling by the hydrogen compressor, pressurized to 2 MPa, and cooled to 20°C. Then it is fed into the middle-lower part of the hydrogen purification column by the hydrogen purification column feed blower. The temperature of the purification column is -10°C and the pressure is 2 MPa. The temperature of the top condenser of the hydrogen purification column is -25°C, and the reflux ratio is 3. The top draw-off enters the gas membrane separator through the top condenser to separate hydrogen and nitrogen. The nitrogen is recovered for air displacement in the autoclave reactor. The bottom draw-off returns to the methanol recovery storage tank through the hydrogen purification column bottom product pump.

[0041] Example 3 S1. After the industrial silicon blocks are crushed by a ball mill, the residue separated and recovered by the methyl orthosilicate bag filter passes through a cyclone separator to separate silicon powder and cuprous oxide. The silicon powder enters the pickling tank, the water washing tank and the silicon powder dryer and is stored in the silicon powder bin, while the cuprous oxide is stored in the catalyst bin. The cuprous oxide and the silicon powder enter the mixing bin at a mass ratio of 5:100, are preheated at 400°C for 1 h, and then enter the autoclave reactor through the silicon powder feed blower.

[0042] S2. High-purity methanol enters the autoclave reactor through the reactor feed pump. The mass ratio of silicon powder to methanol feed is 15:100. After the feeding is completed, nitrogen is introduced to displace the air in the reaction kettle. The temperature of the reactor is 200 °C, and the reaction time is 1 h. After the reaction ends, first cool the temperature of the kettle body, and then discharge the gas in the kettle through the solenoid valve. After the gauge pressure drops to 0, the material is discharged from the bottom of the kettle into the methyl orthosilicate bag filter. The filtered impurities are returned to the cyclone separator through the silicon powder recovery fan. The filtrate enters the crude methyl orthosilicate storage tank through the reactor discharge pump, and then is fed into the middle and upper part of the methanol recovery tower through the methanol recovery tower feed pump. It is rectified under reduced pressure at 80 °C, with a reduced pressure of -0.1 MPa. The temperature of the reboiler at the bottom of the methanol recovery tower is 100 °C, the temperature of the condenser at the top of the methanol recovery tower is 20 °C, and the reflux ratio is 5. The unreacted methanol and low-boiling impurities are condensed and returned to the methanol buffer tank. The material at the bottom of the tower is fed into the middle and lower part of the methyl orthosilicate purification tower through the methanol recovery tower discharge pump. It is rectified under reduced pressure at 120 °C, with a reduced pressure of -0.1 MPa. The temperature of the reboiler at the bottom of the methyl orthosilicate purification tower is 150 °C, the temperature of the condenser at the top of the methyl orthosilicate purification tower is 20 °C, and the reflux ratio is 5. High-purity methyl orthosilicate is condensed and enters the high-purity methyl orthosilicate storage tank. The high-boiling by-products at the bottom of the kettle enter the by-product storage tank through the methyl orthosilicate purification tower discharge pump. The by-products are mainly hexamethyldisiloxane. The conversion rate of silicon powder is 96%. Based on silicon powder, the yield of methyl orthosilicate is 88%, and the purity reaches 4N.

[0043] S3. The components condensed by the condenser at the top of the methanol recovery tower (mainly methanol, entraining a small amount of methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, and triethylmethoxysilane) enter the methanol buffer tank. Methyl orthosilicate and low-boiling by-products such as trimethoxysilane, ethyltrimethoxysilane, and triethylmethoxysilane react with the small amount of water contained in industrial methanol in the buffer tank to generate fumed silica. The methanol with fumed silica coming out of the methanol buffer tank passes through the methanol bag filter to remove fumed silica. The separated methanol is fed into the middle and upper part of the methanol light-end tower through the methanol light-end tower feed pump. It is rectified at atmospheric pressure at 64 °C. The temperature of the reboiler at the bottom of the methanol light-end tower is 70 °C, the temperature of the condenser at the top of the methanol light-end tower is 20 °C, and the reflux ratio is 5. Low-boiling impurities such as formaldehyde, acetaldehyde, methyl ether, and ethyl ether in methanol are removed by rectification. The low-boiling impurities are condensed and enter the methanol recovery storage tank. The material at the bottom of the tower is fed into the middle and lower part of the methanol heavy-end tower through the methanol light-end tower discharge pump. It is rectified at atmospheric pressure at 65 °C. The temperature of the reboiler at the bottom of the methanol heavy-end tower is 80 °C, the temperature of the condenser at the top of the methanol heavy-end tower is 20 °C, and the reflux ratio is 5. High-purity methanol is condensed and enters the high-purity methanol storage tank. The high-boiling impurities at the bottom of the tower enter the methanol recovery storage tank through the methanol heavy-end tower discharge pump. The obtained high-purity methanol is reused in S2 again, achieving a methyl orthosilicate yield of 92.8% and a purity reaching 5N.

[0044] After the product taken from the top of the reactor is refluxed with methanol through the gas-liquid separator, hydrogen is sent to the hydrogen heat exchanger through the hydrogen compressor for cooling, pressurized to 1 MPa, and cooled to 10°C. Then, it is fed into the middle and lower part of the hydrogen purification tower through the feed fan of the hydrogen purification tower. The temperature of the purification tower is -20°C, and the pressure is 1 MPa. The temperature of the top condenser of the hydrogen purification tower is -25°C, and the reflux ratio is 3. The product taken from the top enters the gas membrane separator through the top condenser to separate hydrogen and nitrogen. The nitrogen is recycled for air displacement in the autoclave reactor. The product taken from the bottom of the tower is returned to the methanol recovery storage tank through the discharge pump of the hydrogen purification tower.

[0045] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as the technical solution content of the present invention is not departed from, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A production process for electronic grade methyl orthosilicate, characterized in that: The following steps are involved: S1) Production and refining of methyl orthosilicate: Silicon powder reacts with methanol in a kettle reactor. After the reaction is completed, the material is discharged from the bottom of the kettle, and the crude methyl orthosilicate is separated by a bag filter and fed into the upper part of a methanol recovery tower. After the unreacted methanol is removed, the material is discharged from the kettle, and then fed into the lower part of a methyl orthosilicate refining tower, and methyl orthosilicate is obtained by condensation from the top of the tower; S2) Methanol refining system: After the methanol in step S1 is filtered, it is successively degassed and de-gassed to obtain high-purity methanol, which is then reused in step S1); S3) Hydrogen purification and recovery system: In step S1, the gas phase extracted from the top of the kettle reactor is condensed by the gas-liquid separator, and the output gas is sent to the lower part of the hydrogen purification tower after passing through the hydrogen compressor and the hydrogen heat exchanger. The hydrogen extracted from the top of the tower is separated by the gas membrane separator.

2. The production process of electronic grade methyl orthosilicate according to claim 1, characterized in that: In step S1, the silicon powder is acid-washed, water-washed, and then mixed with a catalyst to activate the silicon powder.

3. The production process of electronic grade methyl orthosilicate according to claim 2, characterized in that: The acid in the pickling process is selected from any one of oxalic acid, acetic acid, sulfuric acid or nitric acid, and the acid concentration is 20-60%; The catalyst is selected from copper, copper oxide or cuprous oxide, and the mass ratio of the catalyst to silicon powder is (1-5):

100.

4. The production process of electronic grade methyl orthosilicate according to claim 1, characterized in that: In step S1, the mass ratio of silicon powder to methanol is (1-20):100, the temperature in the reactor is 180-260° C., and the reaction time is 0.5-6 h.

5. The production process of electronic grade methyl orthosilicate according to claim 1, characterized in that: The temperature of the methanol recovery tower is 60-80°C, the pressure is -1-0 MPa, and the reflux ratio is 1-10; the temperature of the methyl orthosilicate refining tower is 100-120°C, the pressure is -1-0 MPa, and the reflux ratio is 1-10.

6. The production process of electronic grade methyl orthosilicate according to claim 1, characterized in that: In step S2, the temperature of the methanol light removal tower is 63-65° C., and the reflux ratio is 1-10; the temperature of the methanol heavy removal tower is 64-66° C., and the reflux ratio is 1-10.

7. The production process of electronic grade methyl orthosilicate according to claim 1, characterized in that: In step S3, the hydrogen compressor pressurizes the gas to 1-3 MPa, the hydrogen heat exchanger reduces the gas temperature to 10-20°C, the temperature of the hydrogen purification tower is -20-0°C, the pressure is 1-3 MPa, and the reflux ratio is 1-5.

8. The production system used in the production process according to any one of claims 1 to 7, characterized in that: Including methyl orthosilicate production and refining system, alcohol refining system, hydrogen purification and recovery system; The methyl orthosilicate production and refining system includes: a kettle reactor, a methyl orthosilicate bag filter, a crude methyl orthosilicate storage tank, a methanol recovery tower, a methyl orthosilicate refining tower, a by-product storage tank, and a high-purity methyl orthosilicate storage tank; the mixing bin and the high-purity alcohol storage tank are connected to the kettle reactor, the bottom of the kettle reactor is connected to the methyl orthosilicate bag filter, the methyl orthosilicate bag filter is connected to the crude methyl orthosilicate storage tank, the crude methyl orthosilicate storage tank is connected to the methanol recovery tower, the kettle of the methanol recovery tower is connected to the methyl orthosilicate refining tower, the kettle of the methyl orthosilicate refining tower is connected to the by-product storage tank, and the top of the methyl orthosilicate refining tower is connected to the high-purity methyl orthosilicate storage tank; The alcohol refining system includes: a methanol buffer tank, a methanol bag filter, a methanol lightness removal tower, a methanol heaviness removal tower, a methanol recovery storage tank, and a high-purity methanol storage tank. The methanol buffer tank is connected to the methanol bag filter, the methanol bag filter is connected to the methanol lightness removal tower, the methanol lightness removal tower kettle is connected to the methanol heaviness removal tower, the methanol heaviness removal tower top is connected to the high-purity methanol storage tank, and the methanol lightness removal tower top and the methanol heaviness removal tower kettle are connected to the methanol recovery storage tank. The hydrogen purification and recovery system includes: a gas-liquid separator, a hydrogen heat exchanger, a hydrogen purification tower, a methanol recovery storage tank, and a gas membrane separator. The top of the kettle reactor is connected to the hydrogen heat exchanger through the gas-liquid separator, the hydrogen heat exchanger is connected to the hydrogen purification tower, the kettle of the hydrogen purification tower is connected to the methanol recovery storage tank, and the top of the hydrogen purification tower is connected to the gas membrane separator.

9. The production system according to claim 8, characterized in that: The production system also includes a silicon powder pretreatment and catalyst activation system, which includes: a ball mill, a cyclone separator, a silicon powder pickling tank, a silicon powder water washing tank, a silicon powder dryer, a silicon powder bin, a catalyst bin, and a mixing bin. The ball mill is connected to the cyclone separator, the cyclone separator is connected to the silicon powder pickling tank and the catalyst bin, the silicon powder pickling tank is connected to the silicon powder water washing tank, the silicon powder water washing tank is connected to the silicon powder dryer, the silicon powder dryer is connected to the silicon powder bin, and the silicon powder bin and the catalyst bin are connected to the mixing bin.

10. The production system according to claim 9, characterized in that: Also includes: The methyl orthosilicate bag filter is connected to the cyclone separator, and the top of the methanol recovery tower is connected to the methanol buffer tank.

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