A method for the continuous production of electronic grade orthosilicate

Abstract

The present application relates to acid ester preparation technical field, especially electronic grade orthosilicate continuous preparation method, including raw material continuous pretreatment and accurate feeding, continuous microchannel alcoholysis reaction, multistage continuous reaction rectification, deep adsorption purification and precision filtration and byproduct closed loop environmental protection treatment step, the present application is through the traditional batch operation is changed to whole process continuous operation, realizes raw material continuous feeding, reaction, purification and product extraction integration automatic control, discards the neutralization washing link of traditional process and acidic catalyst, constructs the closed loop environmental protection system of byproduct hydrogen chloride preparation high purity hydrochloric acid, unreacted alcohol full cycle reuse, this difference realizes three waste near zero emission, byproduct resources is highly valued, material loss is greatly reduced, environmental protection treatment cost is obviously reduced, avoids secondary pollution at the same time, completely meets the green chemical production requirement.

Description

Technical Field

[0001] This invention relates to the field of ester preparation technology, and in particular to a method for the continuous preparation of electronic-grade orthosilicates. Background Technology

[0002] Electronic-grade orthosilicates are key high-purity precursors in semiconductor integrated circuits, MEMS devices, and photovoltaic coatings. They are mainly used in chemical vapor deposition for preparing silica thin films, as photoresist adhesion promoters, and in the sol-gel method for preparing high-purity silica microspheres. As semiconductor manufacturing processes evolve towards 7nm and below, the purity requirements for orthosilicates are becoming increasingly stringent: metal impurities must be ≤1ppb, chloride ions ≤0.1μg / g, and moisture ≤5ppm, with an overall purity reaching the 8N~9N level.

[0003] Currently, the mainstream industrial method for preparing orthosilicates is the alcoholysis of silicon tetrachloride, which is also the closest existing technology to this invention. Conventional feedstocks typically use 98% pure industrial-grade silicon tetrachloride and anhydrous alcohols (ethanol or methanol) with a purity of over 99.5%. However, existing processes generally suffer from the following core defects: The process suffers from extremely low continuity and significant shortcomings in production efficiency. Traditional processes employ a combination of batch reactors and batch distillation, with feeding, reaction, purification, and slag removal carried out in stages. This limits the capacity of a single reactor and results in poor batch stability. Reaction heat cannot be precisely removed, and localized overheating can easily trigger side reactions, such as siloxane polymerization and chlorination byproducts, reducing product yield and purity. Each batch reaction lasts 6-12 hours, requiring numerous manual intervention steps, making it difficult to meet the high-volume, homogeneous supply demands of the semiconductor industry.

[0004] The process is extremely environmentally unfriendly, with high costs for treating waste gas, wastewater, and solid waste. Hydrogen chloride tail gas is typically absorbed by water spray to produce dilute hydrochloric acid, but the absorption is incomplete and easily escapes, causing air pollution. The reaction liquid requires alkali neutralization and water washing to remove acid, generating a large amount of high-salt wastewater. The distillation residue contains siloxane polymers, which are classified as hazardous waste, resulting in high compliance costs for treatment. The entire process fails to achieve by-product resource utilization and solvent closed-loop recycling, with a material loss rate as high as 15% to 20%.

[0005] Poor equipment adaptability makes it difficult to meet purity standards. Impurities easily precipitate and adhere to the inner walls of ordinary glass reactors and distillation columns, causing metal ion contamination. There is no dedicated integrated equipment for impurity removal, dechlorination, and dehydration, making subsequent purification processes cumbersome and difficult to consistently achieve the electronic-grade 9N purity requirements. Poor equipment sealing performance makes it easy for water vapor to be drawn in, causing product hydrolysis and gelation, leading to product failure.

[0006] The process is not safe enough and has high energy consumption. The heat release from the batch reaction is concentrated, and improper temperature control can easily lead to feed surge and boiling. The distillation process uses intermittent heating, which results in low thermal energy utilization and energy consumption per unit product that is 2 to 3 times that of the continuous process.

[0007] Therefore, developing a continuous, closed-loop, environmentally friendly, high-purity, and controllable method for preparing electronic-grade orthosilicates has become a pressing technical problem to be solved in this field. Summary of the Invention

[0008] To achieve the above objectives, this invention proposes a method for the continuous preparation of electronic-grade orthosilicates, comprising the following steps: Step 1: Continuous pretreatment and precise feeding of raw materials. Industrial-grade silicon tetrachloride is subjected to multi-stage distillation pre-purification, molecular sieve dehydration, and metal ion adsorption column deep purification to obtain purified silicon tetrachloride. Anhydrous alcohols are dehydrated by molecular sieve to obtain purified alcohols. The purified silicon tetrachloride and purified alcohols are continuously and stably delivered to the microchannel reactor in stoichiometric ratio using a metering pump. Step 2: Continuous microchannel alcoholysis reaction. In a microchannel reactor, the reaction temperature, pressure and residence time are controlled to allow silicon tetrachloride to undergo an alcoholysis reaction with alcohols. During the reaction, an inert gas is introduced to purge and continuously remove the byproduct hydrogen chloride gas to obtain the reaction solution. Step 3: Multi-stage continuous reactive distillation. The reaction liquid obtained in Step 2 is continuously fed into a multi-stage series distillation column for atmospheric and vacuum series distillation to remove light and heavy components respectively. At the same time, unreacted alcohols are continuously condensed and recovered during the distillation process and recycled back to the feed end of Step 1. Step 4: Deep adsorption purification and fine filtration. The crude product obtained after distillation in step 3 is continuously fed into a multi-stage series adsorption column, which is then treated by metal ion chelating resin and nano dehydrating adsorbent in sequence to remove metal impurities and moisture. Finally, it is filtered through a precision filter to obtain electronic grade orthosilicate product. Step 5: Closed-loop environmentally friendly treatment of by-products. Collect the hydrogen chloride gas removed in Step 2, purify it, and then absorb it with high-purity deionized water to prepare high-purity hydrochloric acid. Collect the distillation residue in Step 3 and perform low-temperature pyrolysis to recover silicon components.

[0009] In one example, in step one, the purified silicon tetrachloride has a purity ≥99.999%, a moisture content ≤3ppm, a single metal impurity ≤0.5ppb, the purified anhydrous alcohol has a moisture content ≤5ppm, and the molar ratio of silicon tetrachloride to alcohol is 1:4.2~4.8.

[0010] In one example, in step two, the microchannel reactor is made of Hastelloy C276, with an inner wall roughness Ra≤0.2μm, a reaction temperature of 30~60℃, a pressure of -0.1~-0.05MPa, a residence time of 20~60min, and the inert gas is nitrogen or argon.

[0011] In one example, in step three, the reflux ratio of the distillation column is 2 to 5; when preparing tetraethyl orthosilicate, the top temperature of the column is 120 to 150°C and the bottom temperature is 150 to 180°C; when preparing methyl orthosilicate, the top temperature of the column is 55 to 85°C and the bottom temperature is 80 to 110°C; and the vacuum degree of the distillation column is -0.08 to -0.095 MPa.

[0012] In one example, after the continuous microchannel alcoholysis reaction, there is also a step of alkaline dechlorination resin adsorption for deep removal of chloride ions.

[0013] In one example, in step four, the temperature of the adsorption process is 20~30℃, the flow rate is 0.5~2 BV / h, the filter diameter of the precision filter is 0.05μm, and the material is PTFE.

[0014] In one example, the microchannel reactor in step two has a built-in spiral heat exchange channel with a heat exchange efficiency more than 50 times that of a traditional reactor. The multi-stage series distillation column in step three uses structured stainless steel packing and is equipped with a continuous residue removal device in the column bottom. The multi-stage series adsorption column in step four is a modular design that can be switched and regenerated online and is equipped with an online impurity monitoring module.

[0015] The continuous preparation method for electronic-grade orthosilicates proposed in this invention can bring the following beneficial effects: 1. This invention transforms traditional intermittent batch operation into a fully continuous process, achieving integrated automatic control of continuous raw material feeding, reaction, purification, and finished product collection. This difference significantly improves production efficiency, greatly expands the capacity of a single unit, fundamentally improves batch stability of products, significantly shortens reaction residence time, and significantly increases both raw material conversion rate and product yield, while effectively reducing production energy consumption.

[0016] 2. This invention eliminates the neutralization and washing steps and acidic catalysts required in traditional processes, constructing a closed-loop environmentally friendly system for producing high-purity hydrochloric acid from byproduct hydrogen chloride and recycling unreacted alcohols. This difference achieves near-zero emissions of waste gas, wastewater, and solid waste, maximizes the utilization of byproduct resources, significantly reduces material losses, and substantially lowers environmental governance costs, while avoiding secondary pollution and fully meeting the requirements of green chemical production.

[0017] 3. This invention uses specialized equipment that is corrosion-resistant and has low precipitation, and integrates a multi-stage adsorption deep purification unit, replacing the traditional ordinary reaction vessel and simple water washing process that are prone to pollution. This difference enables the product to stably reach the electronic grade high purity standard, eliminates metal ion pollution from the source, effectively prevents product hydrolysis and gelation, significantly improves storage stability, and realizes online real-time quality control, ensuring production safety and product consistency. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of a method for the continuous preparation of electronic-grade orthosilicates. Detailed Implementation

[0019] To more clearly illustrate the overall concept of the present invention, a detailed description will be provided below with reference to the accompanying drawings and examples.

[0020] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0024] like Figure 1 As shown, this invention proposes a method for the continuous preparation of electronic-grade orthosilicates, comprising the following steps: Example 1: Preparation of electronic grade tetraethyl orthosilicate This embodiment uses the following continuous process parameters and equipment configuration.

[0025] Step 1: Continuous Pretreatment and Precise Feeding of Raw Materials. Take 98% industrial-grade silicon tetrachloride and feed it into a silicon tetrachloride distillation pre-purification column (theoretical tray number 40, reflux ratio 3, top temperature 57.5℃) at a flow rate of 200 kg / h, collecting the top fraction. This fraction then enters a molecular sieve dehydrator (filled with 3A molecular sieve, packing volume 1.0 m³). 3 The operating temperature was 25℃, and the pressure was 0.2MPa. The outlet moisture content was measured to be 2.5ppm. Then, it entered a metal ion adsorption column (packed with Amberlite IRC748 chelating resin, volume 0.5m³). 3 (Flow rate 2 BV / h), outlet Fe, Al, and Ca levels were all <0.3 ppb. Anhydrous ethanol (initial moisture 60 ppm) was introduced into a molecular sieve dehydrator (filled with 3A molecular sieve, packing volume 1.0 m³). 3 Anhydrous ethanol with a water content of 4.0 ppm was obtained by operating at 25℃ and 0.2 MPa. Two high-precision metering pumps were used to deliver silicon tetrachloride (flow rate: 135.2 kg / h) and anhydrous ethanol (flow rate: 164.8 kg / h) at a molar ratio of 1:4.5, and the mixture was then combined and fed into a microchannel reactor.

[0026] Step Two: Continuous Microchannel Alcohololysis Reaction. The microchannel reactor is made of Hastelloy C276 material, with an equivalent channel diameter of 1.2 mm, a total length of 60 m, and an inner wall roughness Ra = 0.18 μm. The reaction temperature is controlled at 45℃, the pressure at -0.08 MPa (gauge pressure), and the residence time at 40 min. The reactor has a built-in spiral heat exchange channel, and a -5℃ refrigerant is introduced to maintain a stable reaction temperature. High-purity nitrogen gas (flow rate 10 L / min) is introduced through the inert gas inlet, and hydrogen chloride gas is continuously discharged from the gas outlet. An online gas chromatograph is set at the reactor outlet, and the conversion rate of silicon tetrachloride is measured to be 99.7%. The composition of the reaction solution is: tetraethyl orthosilicate 91.2 wt%, ethanol 6.5 wt%, low-boiling point 0.8 wt%, and high-boiling point 1.5 wt%. The reaction solution enters an alkaline dechlorination adsorption column (packed with D201 resin, volume 0.2 m³). 3 (Flow rate 1 BV / h, temperature 25℃), used for deep removal of chloride ions, with an outlet chloride ion concentration of 0.04 μg / g.

[0027] Step 3: Multi-stage continuous reactive distillation. The reaction solution for removing chloride ions enters the first distillation column (atmospheric pressure, 400mm diameter, structured stainless steel packing, 6m packing height, 35 theoretical plates) at a rate of 300L / h, with a reflux ratio of 3, a top temperature of 82℃, and a bottom temperature of 138℃. Ethanol (99.8% purity, 0.1% water content) is recovered from the top of the column and returned to the feed alcohol storage tank at a rate of 150L / h. Then, the bottom liquid (approximately 150L / h) enters the second distillation column (reduced pressure, vacuum degree -0.09MPa, 300mm diameter, 5m packing height, 30 theoretical plates), with a reflux ratio of 2.5, a top temperature of 135℃, and a bottom temperature of 168℃. Crude tetraethyl orthosilicate (purity 99.6%, chloride ion 0.8 μg / g, total metals 5 ppb, moisture 25 ppm) is collected from the top of the column at a rate of approximately 140 L / h. Heavy components (approximately 10 L / h), mainly siloxane polymers, are discharged from the bottom of the column through a continuous residue discharge device.

[0028] Step 4: Deep adsorption purification and fine filtration. The sample is fed into a metal ion chelation adsorption column (packed with Purolite S930, volume 0.15 mL). 3 (Flow rate 1 BV / h), total metal ion concentration at outlet 0.09 ppb (Fe 0.05 ppb, Al 0.03 ppb, Na 0.01 ppb); finally enters a nano-dehydration adsorption column (packed with 3A molecular sieve + nano Al2O3, volume 0.15 m³). 3 (Flow rate 1 BV / h), outlet moisture 2.8 ppm. After passing the online impurity monitoring module, it enters a 0.05 μm PTFE precision filter to obtain the finished product, tetraethyl orthosilicate.

[0029] Step 5: Closed-loop environmental treatment of by-products. The hydrogen chloride gas discharged in Step 2 (approximately 30 kg / h, containing a small amount of siloxane) is condensed and purified in a low-temperature condenser (-5℃), and then passed through an activated carbon adsorber (filled with 0.1 m³ of coal-based activated carbon). 3 The purified solution enters a high-purity hydrochloric acid absorption tower and is absorbed by deionized water (resistivity 18.2 MΩ·cm) to obtain 32% high-purity hydrochloric acid (metal impurities <0.5 ppb). The heavy components discharged in step three (10 L / h) enter the pyrolysis recovery unit and are pyrolyzed at 250℃. Approximately 8 L / h of liquid siloxane monomers are recovered and returned to the distillation unit, and the remaining solid residue of 2 L / h is solidified and then landfilled.

[0030] Product test results: Purity 99.9999999% (9N), Fe impurity 0.08 ppb, Al impurity 0.06 ppb, Cl - 0.04 μg / g, moisture 2.8 ppm, yield 96.2%. No hydrolysis products were detected after the product was stored in a sealed container for 20 months.

[0031] Example 2: Preparation of electronic-grade methyl orthosilicate This embodiment is basically the same as Embodiment 1, with the following differences in parameters: Step 1: The raw material is changed to anhydrous methanol (industrial grade, moisture 80ppm), which is then dehydrated using a molecular sieve dehydrator (filled with 3A molecular sieves, packing volume 1.0m³, operating temperature 25℃, pressure 0.2MPa) to reduce the moisture content to 4.5ppm. The molar ratio of silicon tetrachloride to methanol is 1:4.3, the silicon tetrachloride flow rate is 135.2kg / h, and the methanol flow rate is 114.8kg / h.

[0032] Step 2: Microchannel reaction temperature 35℃, pressure -0.09MPa, residence time 30min. Conversion rate 99.8%.

[0033] Step 3: The first distillation column (atmospheric pressure) has a top temperature of 65℃ and a bottom temperature of 88℃, recovering methanol; the second distillation column (reduced pressure -0.092MPa) has a top temperature of 65℃ and a bottom temperature of 105℃, with a reflux ratio of 2.5. The crude product purity is 99.5%.

[0034] Step 4: Flow rate 1.2 BV / h.

[0035] Product test results: Purity 99.9999999%, Na impurity 0.05 ppb, Ca impurity 0.07 ppb, Cl - 0.03 μg / g, moisture 2.5 ppm, yield 95.8%.

[0036] Example 3: Preparation of electronic-grade orthosilicate under high-load conditions The total feed flow rate in Example 1 was increased to 500 L / h (silicon tetrachloride + ethanol), and two sets of microchannel reactors (50 plates per set) were used in parallel. Other conditions remained unchanged, with the residence time maintained at 40 min. After continuous operation, the conversion rate was 99.6%, and the product purity remained at 9N, Fe 0.09 ppb, Cl... - The yield was 95.7% with a content of 0.045 μg / g and a moisture content of 3.0 ppm. This demonstrates that the process of this invention has good scalability.

[0037] Example 4: Preparation of electronic-grade methyl orthosilicate under low-temperature reaction conditions The microchannel reaction temperature was adjusted to 30°C, and the rest was the same as in Example 1. The results showed a conversion rate of 99.1% (slightly lower than 99.7% at 45°C), but the byproduct (siloxane polymer) decreased to 1.0% (1.5% at 45°C), the product yield was 95.3%, and the purity still reached 9N (both metal and chloride ions met the standards). This indicates that the present invention can meet the requirements for electronic-grade production within the temperature range of 30~60°C.

[0038] Example 5: Limit Test for Reducing Alcohol Usage The molar ratio of silicon tetrachloride to ethanol was changed to 1:4.2, with the rest remaining the same as in Example 1. The results showed a conversion rate of 98.5%, and the content of free chlorides (such as SiCl3(OC2H5)) in the reaction solution increased to 0.5%. After distillation and adsorption, the chloride ion content in the product could still be reduced to 0.06 μg / g, the moisture content was 2.9 ppm, and the metal impurities were within acceptable limits, with a yield of 93.8%. This indicates that although the electronic grade requirements were barely met, the preferred molar ratio should be ≥4.2, with 4.5 being optimal.

[0039] Example 6: Comparative Experiment of Raw Materials Without Deep Pretreatment This embodiment uses industrial-grade silicon tetrachloride (98% purity, 15 ppm moisture, 5 ppb Fe) and anhydrous methanol (50 ppm moisture) without deep pre-purification. The remaining process conditions are the same as in Example 2. Product test results: purity 99.9999% (6N), total metal impurities 0.5 ppb, Cl... - 0.06 μg / g, moisture 3.0 ppm, yield 95.1%. It is evident that while it reaches the 6N level, it does not reach the 9N electronic level, indicating that deep pretreatment of raw materials is necessary for high-end applications.

[0040] Based on the results of various embodiments, the optimal implementation of the present invention is as follows: Raw material pretreatment: Silicon tetrachloride is distilled with a theoretical plate number ≥35, dehydrated with 3A molecular sieve to a moisture content ≤2ppm, and demetallized with chelating resin to remove metals to a single metal content ≤0.3ppb; alcohol molecular sieve is dehydrated to a moisture content ≤5ppm.

[0041] Microchannel reaction: Hastelloy C276 material, hydraulic channel diameter 1.0~1.2mm, reaction temperature 45±2℃ (TEOS) or 35±2℃ (TMOS), pressure -0.08~-0.09MPa, residence time 40±5min, N2 purge gas-liquid volume ratio 0.2:1.

[0042] Multistage distillation: First distillation column reflux ratio 3, second distillation column reflux ratio 2.5, vacuum degree -0.09~-0.092MPa.

[0043] Deep adsorption: chelating resin (S930) → 3A molecular sieve + nano Al2O3 (4:1 volume ratio), temperature 25℃, flow rate 1 BV / h.

[0044] Byproduct treatment: HCl gas is condensed at -5℃ and adsorbed by activated carbon to produce 32% high-purity hydrochloric acid; the distillation residue is cracked at 250℃ to recover siloxanes.

[0045] Under this optimal implementation method, the product can stably reach a level of 9N or higher, with a yield of ≥96%, a continuous operating cycle of ≥1 month, and an annual operating time of ≥8000 hours.

[0046] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0047] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for continuous preparation of electronic-grade orthosilicates, characterized in that, Includes the following steps: Step 1: Continuous pretreatment and precise feeding of raw materials. Industrial-grade silicon tetrachloride is subjected to multi-stage distillation pre-purification, molecular sieve dehydration, and metal ion adsorption column deep purification to obtain purified silicon tetrachloride. Anhydrous alcohols are dehydrated by molecular sieve to obtain purified alcohols. The purified silicon tetrachloride and purified alcohols are continuously and stably delivered to the microchannel reactor in stoichiometric ratio using a metering pump. Step 2: Continuous microchannel alcoholysis reaction. In a microchannel reactor, the reaction temperature, pressure and residence time are controlled to allow silicon tetrachloride to undergo an alcoholysis reaction with alcohols. During the reaction, an inert gas is introduced to purge and continuously remove the byproduct hydrogen chloride gas to obtain the reaction solution. Step 3: Multi-stage continuous reactive distillation. The reaction liquid obtained in Step 2 is continuously fed into a multi-stage series distillation column for atmospheric and vacuum series distillation to remove light and heavy components respectively. At the same time, unreacted alcohols are continuously condensed and recovered during the distillation process and recycled back to the feed end of Step 1. Step 4: Deep adsorption purification and fine filtration. The crude product obtained after distillation in step 3 is continuously fed into a multi-stage series adsorption column. It is treated sequentially by metal ion chelating resin and nano dehydrating adsorbent to deeply remove metal impurities and moisture. Finally, it is filtered through a precision filter to obtain electronic grade orthosilicate product. Step 5: Closed-loop environmentally friendly treatment of by-products. Collect the hydrogen chloride gas removed in Step 2, purify it, and then absorb it with high-purity deionized water to prepare high-purity hydrochloric acid. Collect the distillation residue in Step 3 and perform low-temperature pyrolysis to recover silicon components.

2. The method for continuous preparation of electronic-grade orthosilicates according to claim 1, characterized in that: In step one, the purified silicon tetrachloride has a purity ≥99.999%, a moisture content ≤3ppm, a single metal impurity ≤0.5ppb, the purified anhydrous alcohol has a moisture content ≤5ppm, and the molar ratio of silicon tetrachloride to alcohol is 1:4.2~4.

8.

3. The method for continuous preparation of electronic-grade orthosilicates according to claim 1, characterized in that: In step two, the microchannel reactor is made of Hastelloy C276, with an inner wall roughness Ra≤0.2μm, a reaction temperature of 30~60℃, a pressure of -0.1~-0.05MPa, a residence time of 20~60min, and the inert gas is nitrogen or argon.

4. The method for continuous preparation of electronic-grade orthosilicates according to claim 1, characterized in that: In step three, the reflux ratio of the distillation column is 2-5; when preparing tetraethyl orthosilicate, the top temperature of the column is 120-150℃ and the bottom temperature is 150-180℃; when preparing methyl orthosilicate, the top temperature of the column is 55-85℃ and the bottom temperature is 80-110℃; and the vacuum degree of the distillation column is -0.08 to -0.095 MPa.

5. The method for continuous preparation of electronic-grade orthosilicates according to claim 1, characterized in that: After the continuous microchannel alcoholysis reaction, there is also a step of alkaline dechlorination resin adsorption for deep removal of chloride ions.

6. The method for continuous preparation of electronic-grade orthosilicates according to claim 1, characterized in that: In step four, the adsorption process is carried out at a temperature of 20-30°C and a flow rate of 0.5-2 BV / h. The precision filter has a filter diameter of 0.05 μm and is made of PTFE.

7. The method for continuous preparation of electronic-grade orthosilicates according to claim 1, characterized in that: The microchannel reactor in step two has a built-in spiral heat exchange channel, and its heat exchange efficiency is more than 50 times that of a traditional reactor. The multi-stage series distillation column in step three uses structured stainless steel packing and is equipped with a continuous residue removal device in the column bottom. The multi-stage series adsorption column in step four is a modular design that can be switched and regenerated online, and is equipped with an online impurity monitoring module.

Images