Device and process for continuously synthesizing electronic-grade methyldiethoxysilane and co-producing hydrogen chloride
By employing a continuous synthesis process and a hydrogen chloride recovery system, the problems of achieving high purity and low pollution in the synthesis of methyldiethoxysilane have been solved, enabling the production of high-purity products and the effective recovery of hydrogen chloride.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI SINOPHORUS ELECTRONIC MATERIALS CO LTD
- Filing Date
- 2025-12-01
- Publication Date
- 2026-04-17
AI Technical Summary
Existing technologies for the synthesis of methyldiethoxysilanes are insufficient to produce high-purity electronic-grade products and fail to effectively reduce hydrogen chloride content and prevent equipment corrosion, leading to environmental pollution.
A continuous synthesis process is adopted, in which the raw materials are treated by a dehydration adsorption column, methyldichlorosilane and ethanol are mixed and reacted, followed by hydrogen chloride pre-removal, solvent removal, distillation and other steps, combined with a hydrogen chloride recovery system, to achieve the purification of high-purity methyldiethoxysilane.
We obtained high-purity methyldiethoxysilane products that meet semiconductor-grade standards, while reducing equipment corrosion and environmental pollution, improving reaction conversion rate, and recovering hydrogen chloride.
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Figure CN121869237A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the synthesis and purification of electronic-grade methyldiethoxysilane, as well as the purification and refining of byproduct hydrogen chloride, specifically to the equipment and purification process system in the production of methyldiethoxysilane. Background Technology
[0002] Methyldiethoxysilane, with the chemical formula CH3SiH(OC2H5)2, is an important organosilanes.
[0003] It is typically a colorless, transparent liquid with a characteristic pungent odor. The molecule contains both reactive Si-H bonds and a hydrolyzable ethoxy group (-OC2H5). The Si-H bonds have high reducing activity and can react with substances containing hydroxyl (-OH) groups. The ethoxy group readily hydrolyzes with water to form silanols, which then condense to form a Si-O-Si network structure. It is unstable in humid air, absorbing moisture and undergoing hydrolysis and cross-linking. Therefore, it must be strictly protected from moisture during storage and transportation. It is soluble in many organic solvents, such as alcohols, ethers, and benzene.
[0004] In semiconductor manufacturing, methyldiethoxysilane is primarily used as a key precursor in vapor deposition processes to prepare thin films rich in silicon, oxygen, and carbon. Its core applications include: Silicon dioxide (SiO2)-based thin film deposition: Through chemical vapor deposition (CVD) or plasma-enhanced chemical vapor deposition (PECVD), methyldiethoxysilane decomposes under plasma or high temperature and reacts with oxidants such as oxygen and nitrous oxide (N2O) to generate carbon-doped silicon dioxide (SiCOH) films. These films have low dielectric constants (k-values), effectively reducing capacitive delay, crosstalk, and power loss between internal metal interconnects, making them indispensable interlayer dielectric materials in advanced processes. Passivation and protective layers: The resulting SiCOH films not only possess excellent dielectric properties but also good mechanical strength, thermal stability, and density. Therefore, they are often used as the final passivation or protective layer for chips, protecting internal circuitry from environmental moisture, ion contamination, and mechanical damage. Methyldiethoxysilane, with its unique molecular structure, has become a key chemical raw material for preparing high-performance dielectric materials and protective layers in semiconductor front-end and back-end processes, playing a vital role in improving chip integration, performance and reliability.
[0005] Currently, methyldiethoxysilane is mainly produced in industrial-grade purity. Due to the special properties of the raw materials, methyldiethoxysilane only achieves 70-80% purity during synthesis. Therefore, even industrial-grade purity requires further purification. Chinese patents 2025106802377, 2022105899808, 2022117213921, 2024114182371, and 2025101474959 disclose methods for preparing and purifying dimethyldimethoxysilane, including methods for purifying electronic-grade dimethyldimethoxysilane. However, these methods do not cleverly connect batch and continuous processes in series, nor do they perform pre-concentration of hydrogen chloride to reduce chloride ion content and prevent environmental pollution and equipment corrosion. This invention avoids excessive side reactions and saves on the use of n-hexane solvent through a clever reaction process, clearly specifying that the solvent used is n-hexane. This process is carried out at atmospheric pressure during purification. To avoid the heat sensitivity of the product, the crude product undergoes deep dehydration. As long as the moisture content is below 40 ppm, the heat sensitivity of dimethyldiethoxysilane will be significantly reduced. Through experiments, the size and specifications of the dehydration adsorption column have been optimized, which can save on the use of desiccant while fully removing water.
[0006] This invention patent describes the following steps: drying with hexane solvent, drying of ethanol raw materials, dehydration treatment of a mixture of hexane and methyldichlorosilane, reaction of methyldichlorosilane and ethanol in hexane solvent, batch buffering of reaction products for pre-removal of hydrogen chloride, hydrogen chloride refining process, solvent removal treatment of crude methyldiethoxysilane, dehydration treatment of the crude product after solvent removal, removal of light and heavy components from the crude product, etc. It not only details the relevant process parameters but also allows for the recovery of hydrogen chloride, reducing equipment corrosion and environmental pollution. After a series of purification processes, qualified electronic-grade methyldiethoxysilane is finally obtained. Summary of the Invention
[0007] To obtain electronic-grade methyldiethoxysilane, this invention provides a purification device and process system for electronic-grade methyldiethoxysilane. By organically combining processes such as moisture removal, light and heavy component removal, anion and cation removal, secondary dehydration, and particle removal, the purification of electronic-grade methyldiethoxysilane is achieved.
[0008] An electronic-grade methyldiethoxysilane synthesis, purification, and co-production of hydrogen chloride unit includes the following equipment: n-hexane feed tank, n-hexane dehydration adsorption column A, n-hexane dehydration adsorption column B, methyldichlorosilane feed tank, primary filter, ethanol feed tank, ethanol dehydration adsorption column A, ethanol dehydration adsorption column B, primary filter, batch reactor, product buffer tank A, product buffer tank B, product buffer tank C, solvent removal tower, crude product dehydration column A, crude product dehydration column B, light component removal tower, heavy component removal tower, secondary filter, product tank A, product tank B, light component collection tank, hydrogen chloride purification tower, hydrogen chloride product tank A, hydrogen chloride product tank B, and electronic-grade product filling machine.
[0009] The lower end of the n-hexane feed tank is connected to n-hexane dehydration adsorption column A and n-hexane dehydration adsorption column B, and nitrogen gas is pressurized into the adsorption columns. The top of the n-hexane dehydration adsorption column A and n-hexane dehydration adsorption column B is connected to the methyldichlorosilane feed tank, and the lower end of the methyldichlorosilane feed tank is connected to the primary filter.
[0010] The lower end of the ethanol feed tank is connected to ethanol dehydration adsorption column A and ethanol dehydration adsorption column B. Ethanol dehydration adsorption column A and ethanol dehydration adsorption column B are connected to a primary filter. The primary filter and the secondary filter are pumped together and enter the batch reactor.
[0011] The crude hydrogen chloride gas exiting from the top of the intermittent reactor enters the light component collection tank; the light component collection tank is connected to the hydrogen chloride refining tower, and the top of the hydrogen chloride refining tower is connected to hydrogen chloride product tank A and hydrogen chloride product tank B.
[0012] The crude methyldiethoxysilane exiting the bottom of the batch reactor sequentially enters product buffer tanks A, B, and C. Product buffer tanks A, B, and C are each connected to a desolventizing tower via a pump. The desolventizing tower is connected to crude product dehydration column A and column B. Crude product dehydration column A and column B are connected to a light product removal tower. The light product removal tower is connected to a heavy product removal tower. The heavy product removal tower is connected to a tertiary filter. The secondary filter is connected to product tanks A and B. Product tanks A and B are each connected to an electronic-grade product filling machine for product filling.
[0013] The process includes hexane solvent drying, ethanol feedstock drying, hexane and methyldichlorosilane mixed dehydration treatment, reaction of methyldichlorosilane and ethanol in hexane solvent, batch buffering of reaction products for pre-removal of hydrogen chloride, hydrogen chloride purification process, crude methyldiethoxysilane desolventizing treatment, dehydration of crude product after desolventizing, removal of light and heavy components from crude product, and finally obtaining electronic grade product from the top of the de-heavy component tower for storage and filling.
[0014] This invention also provides a method for the continuous synthesis of electronic-grade methyldiethoxysilane and the co-production of hydrogen chloride, the method comprising the following steps: S1. Raw material dehydration treatment: n-hexane and ethanol raw materials are dehydrated by passing them through a dehydration adsorption column packed with activated 3A molecular sieves; S2. Raw material mixing and reaction: After mixing the dehydrated n-hexane and methyldichlorosilane, add them to the batch reactor. Under normal pressure and 35~40℃ conditions, add methyldichlorosilane and ethanol dropwise. After the addition is complete, raise the temperature to 55~65℃ and react for 5~15 minutes. S3. Product buffer and hydrogen chloride pre-removal: Transfer the liquid product after reaction into a product buffer tank, blow dry nitrogen into the bottom of the tank for 20-30 minutes, and reflux the top condenser to remove most of the dissolved hydrogen chloride. S4. Desolventizing: The product after step S3 is pumped into a desolventizing tower to remove hexane solvent and reduce water content to below 50 ppm; S5. Light component removal treatment: The dehydrated crude product is distilled in a light component removal tower to remove light component impurities; S6. Heavy component removal treatment: The product after light component removal is distilled in a heavy component removal tower to remove heavy components and metal ions; S7. Product Filtration and Filling: The refined product obtained from the top of the deweighting tower is filtered through a three-stage filter, stored in product tanks, and then filled. S8. Hydrogen chloride recovery: The light component gas generated at the top of the reactor and the desolventizing tower is collected and then passed into the hydrogen chloride purification tower. High-purity hydrogen chloride gas is separated under condensation conditions of -25~-35℃ and recovered.
[0015] In step S1, the activation conditions for the 3A molecular sieve are: baking at 350-400℃ for 4-5 hours under a nitrogen atmosphere; reducing the moisture content of n-hexane to below 60ppm and the moisture content of ethanol to below 60ppm. In step S2, the dehydrated n-hexane and the dehydrated methyldichlorosilane are mixed at a volume ratio of (2~3):5; the amount of ethanol added is equal to the volume of methyldichlorosilane, and the dropping rate is 0.8~1.2 L / 10min.
[0016] In step S4, the product processed in step S3 is pumped into a solvent removal tower to remove n-hexane solvent under the conditions of tower bottom temperature of 70~80℃ and reflux ratio of 4~6. In step S5, the dehydrated crude product is distilled in a light component removal column, with the column bottom temperature controlled at 125~130℃ and the reflux ratio at 10~20, to remove light component impurities. In step S6, the product after light component removal is distilled in a heavy component removal column, with the column bottom temperature controlled at 130~135℃ and the reflux ratio at 25~35, to remove heavy components and metal ions.
[0017] In step S4, the theoretical number of trays in the solvent removal tower is 40-50, and the feed position is the 18th-20th tray. In step S5, the theoretical number of trays in the light-weight removal tower is 65-75, and the feed position is the 28th-32nd tray; in step S6, the theoretical number of trays in the heavy-weight removal tower is 85-95, and the feed position is the 58th-62nd tray.
[0018] Step S6 further includes online detection of the light component content. If the light component content is higher than 0.001%, the material is returned to step S5 for dehydration treatment again. Step S7 further includes online detection of the heavy component content. If the heavy component content is higher than 0.008%, the reflux ratio is increased to 32-38 and the material is re-distilled, or returned to step S5.
[0019] The final electronic-grade methyldiethoxysilane product meets the following specifications: organic purity ≥ 99.9%, total metal ion content < 50 ppb, moisture content < 50 ppm, chloride ion content < 20 ppb, and particulate matter content meets semiconductor-grade standards.
[0020] In some preferred embodiments, the hexane feedstock is discharged from the hexane dehydration adsorption column and then mixed in the methyl dichlorosilane feedstock. The ethanol feedstock is discharged from the ethanol dehydration adsorption column and then mixed with methyl dichlorosilane and hexane in a certain proportion in a batch reactor. The reaction is carried out under certain temperature and pressure. The crude products after the reaction are respectively sent to product buffer tanks. The gas at the top of the reactor enters the light component collection tank and is then purified by hydrogen chloride purification tower.
[0021] The product is discharged from the bottom of the product buffer tank and pumped into the desolventizing tower to remove the hexane solvent. Then, it is discharged from the middle of the tower into the crude product dehydration column. After passing through the dehydration column, the crude product enters the light component removal tower. After light component removal, the product is discharged from the tower. If the light component content is qualified, it enters the heavy component removal tower. If the light component content is too high, it enters the pipeline after the desolventizing tower for re-dehydration and then light component removal. The heavy component is discharged from the middle of the heavy component removal tower. If the heavy component content is qualified, it directly passes through the secondary filter into the product tank. If the heavy component content exceeds the standard, it enters the pipeline after the desolventizing tower for re-dehydration, then light component removal, and then heavy component removal.
[0022] This process system not only purifies the synthesized methyldiethoxysilane by removing solvents, moisture, anions, cations, and particulate impurities to produce an electronic-grade product, but also incorporates a hydrogen chloride recovery system. This process significantly improves the reaction conversion rate and recovers and reuses hydrogen chloride, reducing its corrosive effects on equipment and environmental pollution.
[0023] The purity of n-hexane is tested to be above 99%, with a moisture content of less than 300 ppm. Nitrogen gas is used to press the n-hexane from the bottom of the feed tank into a n-hexane dehydration adsorption column. The adsorption column is 3 meters long and 4 centimeters in inner diameter. The column is filled with activated 3A molecular sieves, which are activated by baking at 400°C for 4 hours in a nitrogen atmosphere. The molecular sieves need to be replaced every 500 liters of n-hexane. Two dehydration adsorption columns are used alternately to ensure that the moisture content of the dried n-hexane meets the required standard of less than 60 ppm.
[0024] The ethanol is tested to have a purity of over 99% and a moisture content of less than 200 ppm. Nitrogen gas is used to press n-hexane from the bottom of the ethanol feed tank into an ethanol dehydration adsorption column. The adsorption column is 3.5 meters long and has an inner diameter of 4.5 centimeters. The column is filled with activated 3A molecular sieves, which are activated by baking at 400°C for 4 hours in a nitrogen atmosphere. The molecular sieves need to be replaced every 600 liters of ethanol. Two dehydration adsorption columns are used alternately to ensure that the moisture content of the dried ethanol meets the required standard of less than 60 ppm.
[0025] The dried n-hexane is directly fed into the methyldichlorosilane container (the container is empty). After the n-hexane feeding is finished, liquid methyldichlorosilane is then fed into the container. During the feeding process, pay attention to whether there is smoke generated in the container. If no smoke is generated, it is normal. The ratio of methyldichlorosilane to n-hexane in this container is 5:2. When the ultra-dry n-hexane is mixed with methyldichlorosilane, the moisture content inside the methyldichlorosilane will be further reduced, thereby improving the reaction yield.
[0026] The reaction mixture of n-hexane and methyldichlorosilane is first fed into a batch reactor. A condenser coil is connected to the top opening of the reactor, maintaining a condensation temperature of -20°C to prevent product evaporation and waste, while allowing the gases to escape normally. The n-hexane and methyldichlorosilane mixture is heated to 35°C under normal pressure, and then dried ethanol is slowly added at a rate of one part methyldichlorosilane to one part ethanol (by volume), at a rate of 1 liter of ethanol added every 10 minutes. Immediately after the ethanol addition is complete, the reactor is heated to 60°C and allowed to react for 10 minutes to stop the reaction. The reaction solution is then transferred to a buffer tank. A vacuum pump is installed between the rear end of the top tube of this reactor and the light component collection tank to promptly extract and temporarily store the reacted gases in the light component collection tank.
[0027] The reactor is a batch reactor, while the distillation unit is a continuous unit. Therefore, to continuously feed the distillation unit, three product buffer tanks are needed for alternating supply. Because the crude product still contains a large amount of hydrogen chloride after the reaction, to avoid corrosion of subsequent units and damage to the product, a portion needs to be separated beforehand. The reactants are transferred to product buffer tank A, and dry nitrogen gas is blown into the bottom of this tank to purge the hydrogen chloride along with the nitrogen. Each product buffer tank has a condenser at the top, allowing the hydrogen chloride to escape while the product is condensed, preventing waste. Each buffer tank needs to be purged for 10-20 minutes. After purging, the hydrogen chloride content in the reaction liquid is reduced to one-sixth of its original level, greatly reducing the harmful effects of hydrogen chloride. The partially dehydrochlorinated reactants are pumped into a desolvation tower. Meanwhile, the next batch of reactants from the reactor enters product buffer tank B for pre-removal of hydrogen chloride gas. This process is repeated sequentially, continuously supplying feed to the distillation tower. Therefore, designing three buffer tanks not only connects the batch reaction with continuous distillation but also removes hydrogen chloride, achieving two goals at once.
[0028] The reacted reagent contains a certain amount of n-hexane. Since the boiling points of n-hexane and methyldiethoxysilane differ significantly, distillation can completely remove the n-hexane. Because some hydrogen chloride dissolves in the n-hexane, the top of the desolventizing column needs to be directly pumped into a light component collection tank for hydrogen chloride enrichment. The desolventizing column is lined with PTFE for corrosion protection and uses PTFE corrugated structured packing. The theoretical number of trays is 45, with the feed point on tray 19. The reboiler temperature is 75°C, and the reflux ratio is 5. Under these distillation conditions, n-hexane and the remaining hydrogen chloride can be completely removed. The product from tray 40 is directed to the crude product dehydration column, and a small amount is slowly discharged from tray 45 to remove some metals and heavy components.
[0029] Light components from the reactor, product buffer tank, and desolventizing tower are collected in a light component collection tank, and then pumped into the hydrogen chloride refining tower for the recovery of hydrogen chloride and n-hexane. The hydrogen chloride refining tower has a simple internal structure, lined with PTFE for corrosion protection. The upper two-thirds of the tower is filled with condenser coils, with a condensation temperature of -30°C. The tower is 8 meters high and 0.4 meters in diameter. The upper section is narrow due to the condenser coils, which facilitates the rapid cooling of non-hydrogen chloride substances to the bottom of the tower. Hydrogen dichloride gas, which cannot be condensed, overflows from the top of the tower and is compressed into the hydrogen chloride product tank. The enriched hydrogen chloride has a purity of over 99% and contains almost no moisture.
[0030] The methyldiethoxysilane purified in this invention has a purity of over 99.9%. Under normal pressure distillation, it needs to be heated to 120°C. If the moisture content is too high, it will trigger a reaction with the methyldiethoxysilane, thus failing to meet product specifications. Therefore, dehydration of the crude product is necessary. A crude product dehydration column with a length of 2.5 meters and an inner diameter of 1.5 centimeters is used. The column is filled with activated 3A molecular sieves. The molecular sieve activation process involves baking at 400°C for 4 hours in a nitrogen atmosphere. The molecular sieve needs to be replaced every 200 liters of crude product. Two dehydration adsorption columns are used alternately. This ensures that the moisture content in the dried crude product meets the required standard of less than 30 ppm.
[0031] The crude product after dehydration contains light component impurities, which need to be removed by a light component removal column. This column is made of 316L stainless steel. All parts of the distillation equipment in contact with the material are made of stainless steel, and the stainless steel is mechanically or electrolytically polished with a roughness ≤0.2µm. The interior uses stainless steel wire mesh packed with a theoretical number of trays of 70. The feed point is at tray 30, and the bottom outlet is at tray 65. The 70th tray discharges a slow, low-flow-rate feed to remove some heavy metals and heavy impurities. The reflux ratio of this column is controlled at 15, and the reboiler temperature is controlled at 128℃. The discharge from tray 65 is divided into two streams. If the light component content of the distilled product is less than 0.001%, the product goes to the heavy component removal column for further heavy component removal. If the light component content is greater than 0.001%, the product goes to the crude product dehydration column after the solvent removal column for further water removal. Under normal operation, the light component impurities after distillation are 0.0005%, and the water content is 22ppm.
[0032] The qualified product after light component removal enters the heavy component removal tower to remove heavy component impurities and metal ion impurities. The heavy component removal tower is made of 316L stainless steel. All parts of the distillation equipment that come into contact with the material are made of stainless steel, and the stainless steel is mechanically or electrolytically polished with a roughness ≤0.2um. The internal structure uses stainless steel wire mesh packing. The theoretical number of trays is 90, and the feed position is at tray 60. The reflux ratio of this tower is controlled at 30, and the reboiler temperature is controlled at 132℃. The top product is divided into two streams. If the heavy component content of the product after distillation is less than 0.008%, the product goes to the product tank. If the heavy component content of the product is greater than 0.008%, the product goes to the heavy component removal tower for redistillation, and the reflux ratio of the heavy component removal tower is increased to 35. Generally speaking, it is extremely rare for the heavy component content of the product to exceed 0.008%, unless there is instability in the utility system, which would cause the heavy component content to exceed the standard. The purified methyldiethoxysilane has an organic content of over 99.93%, a total metal ion content of less than 50 ppb, a moisture content of less than 50 ppm, and a chloride ion content of less than 20 ppb. After filtration, the product has less than 40 pcs / ml of 0.2μm particles, less than 50 pcs / ml of 0.1μm particles, and less than 100 pcs / ml of 0.05μm particles, fully meeting the standards for chip-level use. Attached Figure Description
[0033] To more clearly illustrate the process solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. The following drawings only show some embodiments of the present application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0034] Figure 1 This is a diagram of the apparatus for the synthesis, purification, and byproduct hydrogen chloride production of electronic-grade methyldiethoxysilane in this invention.
[0035] Explanation of markings in the diagram: 1. Hexane feed tank; 2. Hexane dehydration adsorption column A; 3. Hexane dehydration adsorption column B; 4. Methyldichlorosilane feed tank; 5. Primary filter; 6. Ethanol feed tank; 7. Ethanol dehydration adsorption column A; 8. Ethanol dehydration adsorption column B; 9. Secondary filter; 10. Batch reactor; 11. Product buffer tank A; 12. Product buffer tank B; 13. Product buffer tank C; 14. Solvent removal tower; 15. Crude product dehydration column A; 16. Crude product dehydration column B; 17. Light component removal tower; 18. Heavy component removal tower; 19. Tertiary filter; 20. Product tank A; 21. Product tank B; 22. Light component collection tank; 23. Hydrogen chloride refining tower; 24. Hydrogen chloride product A tank; 25. Hydrogen chloride product B tank; 26. Electronic grade product filling machine. Detailed Implementation
[0036] The present invention will be further illustrated below through embodiments. It is worth noting that the given embodiments should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention should still fall within the scope of protection of the present invention.
[0037] Example 1 An apparatus for the continuous synthesis of electronic-grade methyldiethoxysilane and the co-production of hydrogen chloride, the system comprising: The outlet of n-hexane feedstock tank 1 is connected to the inlet of methyldichlorosilane feedstock tank 4 via a pipeline; The outlet of the methyldichlorosilane feed tank 4 is connected to the first feed inlet of the batch reactor 10; The outlet of the ethanol feedstock tank 6 is connected to the second feed port of the batch reactor 10 via a pipeline; The gas phase outlet of the batch reactor 10 is connected to the inlet of the light component collection tank 22 via a pipeline; The liquid phase outlet of the batch reactor 10 is connected to the feed inlet of the desolventizing tower 14 via a pipeline; The outlet of the solvent removal tower 14 is connected to the feed inlet of the light component removal tower 17 via a pipeline; The outlet of the light-weight removal tower 17 is connected to the inlet of the heavy-weight removal tower 18; The top outlet of the deweight removal tower 18 is connected to an electronic-grade methyldiethoxysilane product tank. The outlet of the light component collection tank 22 is connected to the inlet of the hydrogen chloride refining tower 23; The gas phase outlet of the hydrogen chloride refining tower 23 is connected to the hydrogen chloride product tank.
[0038] The outlet of n-hexane feed tank 1 is connected to the inlet of the n-hexane dehydration and adsorption unit via a pipeline; The outlet of the n-hexane dehydration adsorption unit is connected to the inlet of the methyldichlorosilane raw material tank 4; The outlet of the methyldichlorosilane feed tank 4 is connected to the first feed inlet of the batch reactor 10 through a primary filter 5; The hexane dehydration adsorption unit includes a combined adsorption unit formed by hexane dehydration adsorption column A2 and hexane dehydration adsorption column B3, wherein the hexane dehydration adsorption column A2 and hexane dehydration adsorption column B3 are filled with activated 3A molecular sieve. The outlet of the ethanol raw material tank (6) is connected to the inlet of the ethanol dehydration adsorption unit via a pipeline; The outlet of the ethanol dehydration adsorption unit is connected to the second inlet of the batch reactor 10 through another stage filter 9; The ethanol dehydration adsorption unit includes a combined adsorption unit formed by ethanol dehydration adsorption column A7 and ethanol dehydration adsorption column B8, wherein the ethanol dehydration adsorption column A7 and ethanol dehydration adsorption column B8 are filled with activated 3A molecular sieve.
[0039] The liquid phase outlet of the batch reactor 10 is connected to the inlet of the product buffer tank via a pipeline. The outlet of the product buffer tank is connected to the inlet of the desolventizing tower 14 via a pump; The product buffer tank includes a combined unit consisting of product buffer tank A 11, product buffer tank B 12, and product buffer tank C 13. Each buffer tank is equipped with a nitrogen purging port at the bottom and a condensation reflux device at the top.
[0040] The outlet of the solvent removal tower 14 is connected to the inlet of the crude product dehydration unit via a pipeline; The outlet of the crude product dewatering unit is connected to the inlet of the light product removal tower 17; The crude product dehydration unit comprises a combined unit consisting of crude product dehydration column A 15 and crude product dehydration column B 16. The top outlet of the light component removal tower 17 is connected to the feed inlet of the solvent removal tower 14 via a pipeline. The top outlet of the deweight removal tower 18 is connected to the electronic grade methyldiethoxysilane product tank through a three-stage filter 19, and the bottom outlet of the deweight removal tower 18 is connected to the feed inlet of the desolventizing tower 14 through a pipeline.
[0041] The solvent removal tower 14, light solvent removal tower 17, and heavy solvent removal tower 18 are all distillation towers, wherein the parts in contact with the materials are made of corrosion-resistant materials or 316L stainless steel, and the surface roughness is ≤0.2μm; the hydrogen chloride purification tower 23 is equipped with a condenser coil, which is distributed in the upper two-thirds of the tower space.
[0042] An electronic-grade methyldiethoxysilane synthesis, purification, and by-product hydrogen chloride apparatus: Hexane feedstock passes through a hexane dehydration adsorption column and then into a methyldichlorosilane feedstock for mixing. Ethanol feedstock passes through an ethanol dehydration adsorption column and then, along with methyldichlorosilane and hexane, enters a batch reactor in a specific ratio. The reaction is carried out under certain temperature and pressure. The crude products from the reaction are then fed into product buffer tanks. Gas from the top of the reactor enters a light component collection tank and is then purified into hydrogen chloride via a hydrogen chloride purification tower. The product is discharged from the bottom of the product buffer tank and pumped into the desolventizing tower to remove the hexane solvent. Then, it is discharged from the middle of the tower and enters the crude product dehydration column. After passing through the dehydration column, the crude product enters the light component removal tower. After light component removal, the product is discharged from the tower. If the light component content is qualified, it enters the heavy component removal tower. If the light component content is too high, it enters the pipeline after the desolventizing tower for re-dehydration and then light component removal. The heavy component is discharged from the middle of the heavy component removal tower. If the heavy component content is qualified, it directly passes through the secondary filter and enters the product tank. If the heavy component content exceeds the standard, it enters the pipeline after the desolventizing tower for re-dehydration, then light component removal, and then heavy component removal.
[0043] Example 2 The process apparatus of Example 1 was used to synthesize, purify, and produce hydrogen chloride as a byproduct of electronic-grade methyldiethoxysilane.
[0044] The hexane feedstock tank is filled with nitrogen gas at a pressure of 80 kPa, which forces the hexane from the bottom of the tank into the hexane dehydration adsorption column. The adsorption column is 3 meters long and 4 centimeters in inner diameter. The adsorption column is filled with activated 3A molecular sieve. The molecular sieve activation process involves baking at 400°C for 4 hours in a nitrogen atmosphere. The molecular sieve needs to be replaced every 500 liters of hexane. The two dehydration adsorption columns are used alternately. In this way, the moisture content in the dried hexane can reach the corresponding index, which is less than 60 ppm.
[0045] The ethanol feedstock tank is filled with nitrogen gas at a pressure of 80 kPa, which forces n-hexane from the bottom of the tank into the ethanol dehydration adsorption column. The adsorption column is 3.5 meters long and has an inner diameter of 4.5 centimeters. The adsorption column is filled with activated 3A molecular sieves. The molecular sieve activation process is the same as above. The molecular sieves need to be replaced every 600 liters of ethanol. The two dehydration adsorption columns are used alternately. In this way, the water content in the dried ethanol can reach the corresponding index, which is less than 60 ppm.
[0046] The dried n-hexane is directly fed into the methyldichlorosilane tank (the tank is empty). After the n-hexane feeding is finished, liquid methyldichlorosilane is then fed into the tank. The ratio of methyldichlorosilane to n-hexane in the methyldichlorosilane tank is 5:2. When the ultra-dry n-hexane is mixed with methyldichlorosilane, the moisture content inside the methyldichlorosilane will be further reduced, thereby increasing the reaction yield.
[0047] First, the mixed hexane and methyldichlorosilane are fed into a batch reactor. A condenser coil is connected to the top opening of the reactor, and the condensation temperature is kept at -20°C to prevent product evaporation and waste, while allowing the gas to escape normally. The mixed hexane and methyldichlorosilane are heated to 35°C under normal pressure, and then dried ethanol is slowly added. The amount added is one part methyldichlorosilane to one part ethanol (by volume), and the ethanol is added dropwise at a rate of 1 liter every 10 minutes. After the ethanol is added, the reactor is immediately heated to 60°C and allowed to react for 10 minutes before the reaction is stopped. The purity of the methyldiethoxysilane after the reaction is above 68%. The reaction solution is then transferred to one of the buffer tanks.
[0048] A vacuum pump is installed between the rear end of the top pipe of the reaction vessel and the light component collection tank to promptly extract the reacted gas and temporarily store it in the light component collection tank. To prevent the internal hydrogen chloride from corroding subsequent equipment and damaging the product, a portion of it needs to be separated beforehand. After the reactants are transferred to product buffer tank A, dry nitrogen gas is blown into the bottom of the tank to blow out the hydrogen chloride along with the nitrogen. Each product buffer tank has a condenser at the top, so that the hydrogen chloride is blown out while the product is condensed to avoid waste. Each buffer tank needs to be purged for 20 minutes. After purging, the hydrogen chloride content in the reaction liquid is reduced to one-sixth of the original, greatly reducing the harm of hydrogen chloride. The hydrogen chloride-removed reagent is pumped into the desolventizing tower, while the next batch of reagents that has finished reacting in the reactor enters product buffer tank B for pre-removal of hydrogen chloride gas. This process is repeated sequentially to continuously provide raw materials for the first distillation column.
[0049] The reactants contain a certain amount of n-hexane. Since the boiling points of n-hexane and methyldiethoxysilane differ significantly, distillation can completely remove the n-hexane. Because some hydrogen chloride dissolves in the n-hexane, the top discharge from the desolventizing column needs to be directly pumped into the light component collection tank for hydrogen chloride enrichment. The desolventizing column is lined with PTFE for corrosion protection and uses PTFE corrugated structured packing. The theoretical number of trays is 45, with the feed point at tray 19. The reboiler temperature is 75°C, and the reflux ratio is 5. Under these distillation conditions, n-hexane and the remaining hydrogen chloride can be completely removed. The discharge from tray 40 leads to the crude product dehydration column, while a small amount is discharged slowly from tray 45 to remove some metals and heavy components. The light components from the reactor, product buffer tank, and desolventizing column are collected in the light component collection tank and then pumped into the hydrogen chloride purification column for hydrogen chloride and n-hexane recovery.
[0050] The hydrogen chloride refining tower has a simple internal structure, with a PTFE lining for corrosion protection. The upper two-thirds of the tower is filled with condenser coils, with a condensation temperature of -30°C. The tower is 8 meters high and 0.4 meters in diameter. The upper section is narrow due to the condenser coils, which facilitates the rapid cooling of non-hydrogen chloride substances to the bottom of the tower. Hydrogen chloride gas, unable to condense, overflows from the top and is compressed into the hydrogen chloride product tank. Tests show that the enriched hydrogen chloride has a purity of over 99% and contains almost no moisture. The methyldiethoxysilane to be purified needs to have a purity of over 99.9%. Under normal pressure distillation, it needs to be heated to 120°C. If the moisture content is too high, it will trigger a reaction with the methyldiethoxysilane, thus failing to meet product specifications. Therefore, dehydration of the crude product is necessary. A crude product dehydration column with a length of 2.5 meters and an inner diameter of 1.5 centimeters is used. The column is filled with activated 3A molecular sieves. The molecular sieve activation process involves baking at 400°C for 4 hours in a nitrogen atmosphere. The molecular sieve needs to be replaced every 200 liters of crude product. Two dehydration adsorption columns are used alternately. Only in this way can the moisture content of the dried crude product meet the corresponding specification, which is less than 30 ppm.
[0051] The crude product after dehydration contains light component impurities, which need to be removed by a light component removal column. This column is made of 316L stainless steel. All parts of the distillation equipment in contact with the material are made of stainless steel, and the stainless steel is mechanically or electrolytically polished with a roughness ≤0.2µm. The interior uses stainless steel wire mesh packed with a theoretical number of trays of 70. The feed point is at tray 30, the bottom outlet is at tray 65, and the 70th tray is the outlet with a slow, low-flow rate to remove some heavy metals and heavy impurities. The reflux ratio of this column is controlled at 15, and the reboiler temperature is controlled at 128℃. Under normal operation, the light component impurities after distillation are 0.0005%, and the moisture content is 22ppm.
[0052] The qualified product after the removal of light components enters the de-heavy component tower to remove heavy component impurities and metal ion impurities. The de-heavy component tower is made of 316L stainless steel. All parts of the distillation equipment that come into contact with the material are made of stainless steel, and the stainless steel material is mechanically or electrolytically polished with a roughness of ≤0.2um. The internal structure uses stainless steel wire mesh packing. The theoretical number of trays is 90, and the feed position is at the 60th tray. The reflux ratio of the tower is controlled at 30, and the reboiler temperature is controlled at 132℃.
[0053] The purified methyldiethoxysilane has an organic content of over 99.93%, a total metal ion content (the sum of metal ions as shown in Table 1) of less than 50 ppb, a moisture content of less than 50 ppm, a chloride ion content of less than 20 ppb, and after filtration, the product has less than 40 pcs / ml of 0.2μm particles, less than 50 pcs / ml of 0.1μm particles, and less than 100 pcs / ml of 0.05μm particles, fully meeting the chip-level usage standards.
[0054] Example 3 This embodiment also uses the process system of Example 1. The difference from Example 2 is that 6% more ethanol is added in the synthesis stage. Other process details are the same as in Example 2.
[0055] Because some methyldichlorosilane in the product of the first test reaction could not be completely reacted, some ethanol was added to observe the amplified reaction results. After the reaction, the purity of methyldiethoxysilane was found to have decreased to only 53%, while other indicators remained basically unchanged, and the yield of hydrogen chloride increased by 3%.
[0056] Example 4 This embodiment also uses the process system of Embodiment 1. The difference from Embodiment 2 is that this embodiment mainly reduces the reflux ratio of the light-weight tower. Other process details are the same as those of Embodiment 2.
[0057] Because the reflux ratio of the first column was too high, it was reduced from 15 to 10. It was found that the light component in the bottom of the first column increased, while the purity at the top of the second column decreased, fluctuating around 99.91%, and the metal ion content did not change much.
[0058] Example 5 This embodiment also uses the process system of Embodiment 1. The difference from Embodiment 2 is that this embodiment mainly reduces the reflux ratio of the de-weighting tower. Other process details are the same as those of Embodiment 2.
[0059] Because the reflux ratio of the second tower was too high, the reflux ratio of the second tower was reduced from 30 to 25. It was found that the light component at the top of the second tower decreased, the heavy component at the top of the second tower increased, the purity at the top of the second tower decreased, and it fluctuated around 99.93%. The metal ion content increased to some extent, but overall the product was qualified.
[0060] The above examples illustrate that this process is highly adjustable and stable, and can consistently produce qualified products even when operating conditions fluctuate.
[0061] The above are merely some embodiments of this application and are not intended to limit the scope of protection of this application. For those skilled in the art, this application can have other forms of modifications and variations. Any modifications, synonymous substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0062] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions made by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims. Furthermore, the replacement of methyldiethoxysilane with dimethyldiethoxysilane also falls within the scope of protection of this patent.
[0063] Industrial-grade raw material data, electronic-grade product requirements, and data results from Examples 2 to 5:
[0064] Note that the crude product mentioned refers to the product inside the buffer tank.
Claims
1. An apparatus for the continuous synthesis of electronic-grade methyldiethoxysilane and the co-production of hydrogen chloride, characterized in that, The system includes: The outlet of the n-hexane feedstock tank (1) is connected to the inlet of the methyldichlorosilane feedstock tank (4) via a pipeline; The outlet of the methyldichlorosilane feed tank (4) is connected to the first feed inlet of the batch reactor (10); The outlet of the ethanol feed tank (6) is connected to the second feed port of the batch reactor (10) via a pipeline; The gas phase outlet of the batch reactor (10) is connected to the inlet of the light component collection tank (22) via a pipeline; The liquid phase outlet of the batch reactor (10) is connected to the feed inlet of the desolventizing tower (14) via a pipeline; The outlet of the solvent removal tower (14) is connected to the feed inlet of the light solvent removal tower (17) via a pipeline; The outlet of the light removal tower (17) is connected to the inlet of the heavy removal tower (18); The top outlet of the deweight removal tower (18) is connected to the electronic grade methyldiethoxysilane product tank; The outlet of the light component collection tank (22) is connected to the inlet of the hydrogen chloride refining tower (23); The gas phase outlet of the hydrogen chloride refining tower (23) is connected to the hydrogen chloride product tank.
2. The apparatus according to claim 1, characterized in that, The outlet of the n-hexane feed tank (1) is connected to the inlet of the n-hexane dehydration adsorption unit via a pipeline; The outlet of the n-hexane dehydration adsorption unit is connected to the inlet of the methyl dichlorosilane raw material tank (4); The outlet of the methyldichlorosilane feed tank (4) is connected to the first feed inlet of the batch reactor (10) through a primary filter (5); The n-hexane dehydration adsorption unit includes a combined adsorption unit formed by n-hexane dehydration adsorption column A (2) and n-hexane dehydration adsorption column B (3), wherein the n-hexane dehydration adsorption column A (2) and n-hexane dehydration adsorption column B (3) are filled with activated 3A molecular sieves. The outlet of the ethanol raw material tank (6) is connected to the inlet of the ethanol dehydration adsorption unit via a pipeline; The outlet of the ethanol dehydration adsorption unit is connected to the second inlet of the batch reactor (10) through a secondary filter (9); The ethanol dehydration adsorption unit includes a combined adsorption unit formed by ethanol dehydration adsorption column A (7) and ethanol dehydration adsorption column B (8), wherein the ethanol dehydration adsorption column A (7) and ethanol dehydration adsorption column B (8) are filled with activated 3A molecular sieve.
3. The apparatus according to claim 1, characterized in that, The liquid phase outlet of the batch reactor (10) is connected to the inlet of the product buffer tank via a pipeline; The outlet of the product buffer tank is connected to the inlet of the desolventizing tower (14) via a pump; The product buffer tanks include a combined unit consisting of product buffer tank A (11), product buffer tank B (12), and product buffer tank C (13). Each buffer tank has a nitrogen purging port at the bottom and a condensation reflux device at the top.
4. The apparatus according to claim 1, characterized in that, The outlet of the solvent removal tower (14) is connected to the inlet of the crude product dehydration unit via a pipeline; The outlet of the crude product dewatering unit is connected to the inlet of the light product removal tower (17); The crude product dehydration unit comprises a combined unit consisting of crude product dehydration column A (15) and crude product dehydration column B (16). The top outlet of the light-light removal tower (17) is connected to the inlet of the solvent removal tower (14) via a pipeline. The top outlet of the deweight removal tower (18) is connected to the electronic grade methyldiethoxysilane product tank through a three-stage filter (19), and the bottom outlet of the deweight removal tower (18) is connected to the feed inlet of the desolventizing tower (14) through a pipeline.
5. The apparatus according to claim 1, characterized in that, The solvent removal tower (14), light component removal tower (17), and heavy component removal tower (18) are all distillation towers. The parts in contact with the materials are made of corrosion-resistant materials or stainless steel 316L, and the surface roughness is ≤0.2μm. The hydrogen chloride refining tower (23) is equipped with a condensing coil, which is distributed in the upper two-thirds of the tower space.
6. A method for the continuous synthesis of electronic-grade methyldiethoxysilane and the co-production of hydrogen chloride, using the apparatus described in any one of claims 1-5, characterized in that, The method includes the following steps: S1. Raw material dehydration treatment: n-hexane and ethanol raw materials are dehydrated by passing them through a dehydration adsorption column packed with activated 3A molecular sieves; S2. Raw material mixing and reaction: After dehydration, n-hexane and methyldichlorosilane are mixed and added to the batch reactor (10). Methyldichlorosilane ethanol is added dropwise under normal pressure and 35~40℃. After the addition is completed, the temperature is raised to 55~65℃ and the reaction is carried out for 5~15 minutes. S3. Product buffer and hydrogen chloride pre-removal: Transfer the liquid product after reaction into a product buffer tank, blow dry nitrogen into the bottom of the tank for 20-30 minutes, and reflux the top condenser to remove most of the dissolved hydrogen chloride. S4. Desolventizing: The product after step S3 is pumped into the desolventizing tower (14) to remove n-hexane solvent and remove water to below 30 ppm; S5. Light component removal treatment: The dehydrated crude product is distilled in the light component removal tower (17) to remove light component impurities; S6. Heavy component removal treatment: The product after light component removal is distilled in the heavy component removal tower (18) to remove heavy components and metal ions; S7. Product filtration and filling: The refined product obtained from the top of the deweight tower (18) is filtered through a three-stage filter (19), stored in product tanks, and then filled. S8. Hydrogen chloride recovery: The light component gas generated at the top of the reactor and the desolventizing tower is collected and passed into the hydrogen chloride purification tower (23). High-purity hydrogen chloride gas is separated under condensation conditions of -25~-35℃ and recovered.
7. The method according to claim 6, characterized in that, In step S1, the activation conditions for the 3A molecular sieve are: baking at 350-400℃ for 4-5 hours under a nitrogen atmosphere; reducing the moisture content of n-hexane to below 60ppm and the moisture content of ethanol to below 60ppm. In step S2, the dehydrated n-hexane and the dehydrated methyldichlorosilane are mixed at a volume ratio of (2~3):5; the amount of ethanol added is equal to the volume of methyldichlorosilane, and the dropping rate is 0.8~1.2 L / 10min. In step S4, the product after step S3 is pumped into the solvent removal tower (14) to remove n-hexane solvent under the conditions of tower bottom temperature of 70~80℃ and reflux ratio of 4~6. In step S5, the dehydrated crude product is distilled in a light component removal column (17), with the column bottom temperature controlled at 125~130℃ and the reflux ratio at 10~20, to remove light component impurities. In step S6, the product after light component removal is distilled in a heavy component removal tower (18), with the tower bottom temperature controlled at 130~135℃ and the reflux ratio at 25~35, to remove heavy components and metal ions.
8. The method according to claim 6, characterized in that, In step S4, the theoretical number of plates in the solvent removal tower (14) is 40 to 50, and the feed position is the 18th to 20th plate. In step S5, the theoretical number of trays of the light-weight removal tower (17) is 65-75, and the feed position is the 28th-32nd tray; in step S6, the theoretical number of trays of the heavy-weight removal tower (18) is 85-95, and the feed position is the 58th-62nd tray.
9. The method according to claim 6, characterized in that, Step S6 also includes online detection of the light component content. If the light component content is higher than 0.001%, the material is returned to step S5 for dehydration treatment again. Step S7 also includes online detection of the heavy component content. If the heavy component content is higher than 0.008%, the reflux ratio is increased to 32-38 and the material is re-distilled, or returned to step S5.
10. The method according to any one of claims 6-9, characterized in that, The final electronic-grade methyldiethoxysilane product meets the following specifications: organic purity ≥ 99.9%, total metal ion content < 50 ppb, moisture content < 50 ppm, chloride ion content < 20 ppb, and particulate matter content meets semiconductor-grade standards.