Trichlorosilane purification method and system
By combining light component removal towers, extractive distillation towers, heavy component removal distillation towers, and solvent removal towers, and utilizing the differences in component distribution coefficients, the problem of separating trichlorosilane and methyldichlorosilane was solved, achieving efficient and low-energy purification of trichlorosilane and improving the quality and production efficiency of polycrystalline silicon rods.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU XINHUA SEMICON TECH CO LTD
- Filing Date
- 2024-04-29
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies cannot effectively separate trichlorosilane and methyldichlorosilane, resulting in high carbon content in the produced polycrystalline silicon rods, which affects product quality and increases the size of production equipment and energy consumption.
By utilizing the difference in the partition coefficients of methyldichlorosilane in trichlorosilane and silicon tetrachloride, a combination of operations including a light-light distillation column, an extractive distillation column, a heavy-light distillation column, and a solvent removal column is used to achieve efficient purification of trichlorosilane, reducing the number of trays and energy consumption.
It improves the purity and production efficiency of trichlorosilane, reduces equipment footprint and energy consumption, reduces production costs, and meets the needs of high-end applications.
Smart Images
Figure CN118255358B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of trichlorosilane purification technology, specifically a method and system for purifying trichlorosilane. Background Technology
[0002] Currently, the production of electronic-grade polycrystalline silicon mainly employs a modified Siemens process. This method involves passing high-purity trichlorosilane into a chemical vapor deposition (CVD) reaction to deposit electronic-grade polycrystalline silicon rods. However, obtaining high-purity trichlorosilane is not easy; it needs to be separated from the chlorosilane mixture by distillation. During the synthesis of chlorosilanes, methyldichlorosilane is often produced, with a boiling point very close to that of trichlorosilane (around 38 degrees Celsius), making complete separation difficult. This results in a high carbon content in the produced silicon rods, thus affecting product quality.
[0003] Currently, to address this issue, distillation is used in the production process to separate trichlorosilane and methyldichlorosilane. However, because their boiling points are very close, this requires the column equipment to have more trays and a larger reflux ratio to achieve effective separation. This not only increases the size of the production equipment but also increases energy consumption, thereby increasing production costs.
[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0005] The first objective of this invention is to provide a method for purifying trichlorosilane, utilizing the difference in partition coefficients between methyldichlorosilane and silicon tetrachloride. This method effectively separates methyldichlorosilane from trichlorosilane, and compared to conventional distillation, it helps to reduce the number of trays and energy consumption.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for purifying trichlorosilane includes the following steps:
[0008] S01: Crude trichlorosilane is introduced into the light component removal tower to remove light components;
[0009] S02: Crude trichlorosilane after being treated by S01 is collected from the bottom of the light removal tower and enters the lower part of the extractive distillation tower, where it is extracted with the extractant introduced from the upper part of the extractive distillation tower. The pure trichlorosilane at the top of the tower and the extractant containing methyl dichlorosilane in the bottom of the tower are separated by utilizing the boiling point difference of different components.
[0010] S03: The pure trichlorosilane collected from the top of the extractive distillation column is sent to the heavy removal distillation column for further purification. After purification, high-purity trichlorosilane is output from the top of the column for use, and the bottom material is introduced into step S02 as an extractant.
[0011] S04: The extractant containing methyldichlorosilane collected from the bottom of the extractive distillation column is sent to the desolventizing column for recovery and purification. After purification, the methyldichlorosilane with higher purity is removed from the top of the column and collected as a by-product. The material collected from the bottom of the column is introduced into the upper part of the extractive distillation column as the extractant.
[0012] Furthermore, in step S01, crude trichlorosilane refers to the crude product after preliminary separation to remove silicon tetrachloride and high-boiling substances. Specifically, preliminary separation is carried out in a crude separation tower, which is used to crudely separate the materials synthesized by cold hydrogenation. The cold hydrogenated materials are degraded by the crude separation tower to remove high-boiling substances and silicon tetrachloride. Methyldichlorosilane is collected together with trichlorosilane because its boiling point is close to that of trichlorosilane.
[0013] Furthermore, in step S01, crude trichlorosilane is collected from the bottom of the light component removal tower, which contains methyl dichlorosilane. The dichlorosilane and other light component impurities collected from the top of the light component removal tower are introduced into a phosphorus removal adsorbent to remove phosphorus-containing compounds, thus avoiding adverse effects on high-end applications such as electronic-grade polysilicon, and preventing corrosion and damage to production equipment. This invention, by removing phosphorus-containing compounds, can improve the purity and quality of crude trichlorosilane, protect production equipment, extend its service life, and reduce maintenance costs.
[0014] Furthermore, in step S02, the extractive distillation column has a theoretical plate number ≥ 50, and its operating pressure is 1.2–4 bar. This helps to improve the purification efficiency of trichlorosilane while minimizing energy consumption. Selecting an operating pressure within the range of 1.2–4 bar ensures both operational safety and relatively low energy consumption. This helps reduce system operating costs and energy consumption.
[0015] Furthermore, in step S02, the extractant is silicon tetrachloride. The content of methyldichlorosilane in the extractant is less than 0.005%, ensuring effective removal of methyldichlorosilane from trichlorosilane. If the content of methyldichlorosilane in the extractant exceeds 2%, the extraction effect of silicon tetrachloride will be significantly reduced, making it difficult to effectively reduce the content of methyldichlorosilane in trichlorosilane. Moreover, methyldichlorosilane is one of the key factors affecting the purity of the final product. By controlling the content of methyldichlorosilane in the extractant, the purity of the pure trichlorosilane collected from the top of the tower can be ensured to meet the requirements of high-end applications.
[0016] Furthermore, in step S02, the extractive distillation column is a high-efficiency packed column; the theoretical number of plates in the extractive distillation column is 50 to 100, which provides more contact points and separation interfaces, thereby enhancing the mass transfer and mass separation efficiency between phases. This helps to achieve better effective separation between trichlorosilane and methyldichlorosilane within the column, improving the purity and quality of the product. Compared to traditional tray columns, high-efficiency packed columns typically have a smaller volume and a more compact structure. This means that more plates can be achieved in the same space, thereby improving the efficiency of the extractive distillation column while reducing the equipment footprint.
[0017] Furthermore, during feeding, the amount of extractant used is 0.01% to 0.1% of the crude trichlorosilane. This demonstrates that a small amount of extractant can achieve the desired effect without significantly impacting the reflux rate of the tower.
[0018] Furthermore, the pure trichlorosilane collected from the top of the extractive distillation column has a purity of over 99.9%, which is used to improve the purity of the trichlorosilane. This ensures that the prepared polycrystalline silicon product has stable quality and low impurity content, thereby improving the performance and stability of electronic devices. This invention reduces the cost of subsequent processing steps by achieving high purity during the purification stage. Compared to using low-purity raw materials and further purification in subsequent processes, directly obtaining a high-purity product saves time, manpower, and resource costs.
[0019] Furthermore, in step S03, the number of plates in the de-gravimetric distillation column is 50-100. High-efficiency plate distillation columns have high mass transfer and separation efficiencies, enabling more thorough separation of trichlorosilane from other impurities. This helps improve the purity and quality of the product, ensuring high-purity trichlorosilane collected from the top of the column.
[0020] The second objective of this invention is to provide a trichlorosilane purification system for the preparation described above. The various components of the system are connected to form a unified whole, achieving an organic combination of steps such as light component removal, extraction, heavy component removal, and solvent removal. This integrated operation makes the entire purification process more compact and efficient, reducing potential intermediate steps and resource waste. Compared to conventional distillation, it helps to reduce the number of trays and energy consumption.
[0021] To achieve the above objectives, the present invention provides the following technical solution:
[0022] A trichlorosilane purification system, employing the above-mentioned trichlorosilane purification method, includes:
[0023] Light component removal tower is used to remove light components from crude trichlorosilane;
[0024] The extractive distillation column has a first feed inlet at the bottom that connects to the output end of the light component removal column, a second feed inlet at the top for the extractant to enter, and a first outlet and a second outlet at the top and bottom of the column, respectively.
[0025] The heavy removal distillation column is equipped with a third feed inlet, which is connected to the first discharge outlet.
[0026] The solvent removal tower is equipped with a fourth inlet connected to the second outlet, and the bottom of the solvent removal tower is connected to the second inlet.
[0027] The control center is electrically connected to the light-light residue removal column, extractive distillation column, heavy-weight residue removal distillation column, and solvent removal column. It performs quality control and real-time monitoring of these columns. This helps to promptly identify potential problems and anomalies, allowing for appropriate adjustments and corrections to ensure the stable operation of the entire system and the consistency of product quality.
[0028] Furthermore, a phosphorus adsorber is connected to the top output of the light precipitator to prevent phosphorus from accumulating in the system and affecting the quality of polysilicon products.
[0029] Compared with the prior art, the beneficial effects of the present invention are:
[0030] (1) In this invention, the material (silicon tetrachloride) in its own system is used as the extractant to extract the organic carbon (mainly methyl dichlorosilane) in trichlorosilane. The organic carbon in trichlorosilane can be enriched in the bottom of the tower to obtain relatively pure trichlorosilane. Moreover, the boiling points of methyl dichlorosilane and silicon tetrachloride are quite different, so they can be separated better. In addition, methyl dichlorosilane with high purity can be obtained, which can be used as a raw material in the organosilicon industry and helps to reduce production costs.
[0031] (2) Compared with traditional adsorption techniques for removing organosilicon, this invention eliminates the need to purchase additional adsorbents, thus saving on raw material costs. Furthermore, since the adsorbent does not need to be replaced, it avoids generating large quantities of used adsorbent, reducing solid waste. This helps reduce environmental pollution risks and aligns with the requirements of sustainable development.
[0032] (3) Because this invention achieves efficient separation of methyldichlorosilane and trichlorosilane, it helps to reduce the number of trays and the energy consumption of the distillation column compared with conventional distillation. This helps to improve production efficiency, reduce energy consumption, and thus reduce production costs. Attached Figure Description
[0033] Figure 1 This is an overall flowchart of the present invention;
[0034] Figure 2This is a schematic diagram illustrating the influence of the raw material feed location on Example 1 of the present invention;
[0035] Figure 3 This is a schematic diagram illustrating the influence of the extractant feed location on Example 1 of the present invention;
[0036] Figure 4 This is a schematic diagram illustrating the influence of the raw material feed location on Example 2 of the present invention;
[0037] Figure 5 This is a schematic diagram illustrating the influence of the extractant feed location on Example 2 of the present invention;
[0038] Figure 6 This is a schematic diagram illustrating the influence of the raw material feed location on Example 3 of the present invention;
[0039] Figure 7 This is a schematic diagram illustrating the influence of the extractant feed location on the analysis of Example 3 of this invention;
[0040] Figure 8 This is a schematic diagram illustrating the effect of the reflux ratio in Example 4 of the present invention;
[0041] Figure reference numerals: 1. Light weight removal column; 2. Extractive distillation column; 21. First feed inlet; 22. Second feed inlet; 23. First discharge outlet; 24. Second discharge outlet; 3. Heavy weight removal distillation column; 31. Third feed inlet; 4. Solvent removal column; 41. Fourth feed inlet; 5. Phosphorus removal adsorber; 01. Trichlorosilane; 02. Extractant. Detailed Implementation
[0042] Please see Figure 1-8 This invention provides a technical solution that utilizes the difference in partition coefficients between methyldichlorosilane and trichlorosilane and silicon tetrachloride. This effectively separates methyldichlorosilane from trichlorosilane, helping to reduce the number of trays and energy consumption compared to conventional distillation.
[0043] A method for purifying trichlorosilane includes the following steps:
[0044] S01: Crude trichlorosilane 01 is introduced into the light component removal tower 1 to remove light components;
[0045] S02: Crude trichlorosilane 01 after processing in step S01 is collected from the bottom of the light removal tower 1 and enters the lower part of the extractive distillation tower 2, where it azeotropically reacts with the extractant 02 introduced from the upper part of the extractive distillation tower 2. By utilizing the boiling point difference of different components, the pure trichlorosilane 01 at the top of the tower and the extractant containing methyl dichlorosilane at the bottom of the tower are separated.
[0046] S03: The pure trichlorosilane 01 collected from the top of the extractive distillation column 2 is sent to the heavy removal distillation column 3 for further purification. After purification, high-purity trichlorosilane 01 is output from the top of the column for use, and the bottom material is introduced into step S02 as extractant 02.
[0047] S04: The extractant containing methyldichlorosilane collected from the bottom of the extractive distillation column 2 is sent to the desolventizing column 4 for recovery and purification. After purification, the methyldichlorosilane with higher purity is removed from the top of the column and collected as a by-product. The material collected from the bottom of the column is introduced into the upper part of the extractive distillation column 2 as extractant O2.
[0048] Furthermore, in step S01, crude trichlorosilane 01 refers to the crude product after preliminary separation to remove silicon tetrachloride and high-boiling substances. Specifically, preliminary separation is carried out in a crude separation column, which is used to crudely separate the materials synthesized by cold hydrogenation. Silicon tetrachloride is collected from the side stream of the crude separation column, a mixture of crude trichlorosilane 01 and methyl dichlorosilane is collected from the top of the column, and high-boiling substances are collected from the bottom of the column. Crude trichlorosilane 01 is separated to the top of the crude separation column, and methyl dichlorosilane is separated to the bottom of the column. The high-boiling substances have a high boiling point and are not separated, remaining in the bottom of the column. The crude trichlorosilane 01 from the top of the column, the methyl dichlorosilane from the bottom of the column, and the high-boiling substances are all returned to the crude separation column to improve the purity of crude trichlorosilane 01.
[0049] Preferably, in step S01, crude trichlorosilane 01 is collected from the bottom of the light component removal tower 1, which contains methyl dichlorosilane. The dichlorosilane and other light component impurities collected from the top of the light component removal tower 1 are introduced into the phosphorus removal adsorber 5 to remove phosphorus-containing compounds, thus avoiding adverse effects on high-end applications such as electronic-grade polysilicon.
[0050] Preferably, in step S02, the number of theoretical plates in the extractive distillation column 2 is ≥50, and the operating pressure of the extractive distillation column 2 is 1.2–4 bar. This helps to improve the purification efficiency of trichlorosilane 01 while minimizing energy consumption. Selecting an operating pressure within the range of 1.2–4 bar ensures both operational safety and relatively low energy consumption. This helps reduce system operating costs and energy consumption.
[0051] Preferably, in step S02, the content of methyldichlorosilane in extractant 02 is less than 0.005%. This ensures effective removal of methyldichlorosilane from trichlorosilane 01. If the content of methyldichlorosilane exceeds 2%, the extraction effect of silicon tetrachloride will be significantly reduced, making it difficult to effectively reduce the content of methyldichlorosilane in trichlorosilane 01. Furthermore, methyldichlorosilane is one of the key factors affecting the purity of the final product. By controlling the content of methyldichlorosilane in extractant 02, the purity of the pure trichlorosilane 01 collected from the top of the tower can be ensured to meet the requirements of high-end applications.
[0052] Preferably, in step S02, the extractive distillation column 2 is a high-efficiency packed column; the theoretical number of plates in the extractive distillation column 2 is 50 to 100, which provides more contact points and separation interfaces, thereby enhancing the mass transfer and mass separation efficiency between phases. This helps to achieve better effective separation between trichlorosilane O1 and methyldichlorosilane within the column, improving the purity and quality of the product. Compared to traditional tray columns, high-efficiency packed columns typically have a smaller volume and a more compact structure. This means that more plates can be achieved in the same space, thereby improving the efficiency of the extractive distillation column 2 while reducing the equipment footprint. During feeding, the amount of extractant is 0.01% to 0.1% of the crude trichlorosilane. Preferably, it is 0.02%, which demonstrates that a small amount of extractant can achieve the desired effect without significantly affecting the column's reflux rate.
[0053] Preferably, the pure trichlorosilane 01 collected from the top of the extractive distillation column 2 has a mass content of 99.9% or higher, which is used to improve the purity of the pure trichlorosilane 01. This ensures that the prepared polycrystalline silicon product has stable quality and low impurity content, thereby improving the performance and stability of electronic devices. This invention reduces the cost of subsequent processing steps by achieving high purity during the purification stage. Compared to using low-purity raw materials and further purification in subsequent processes, directly obtaining a high-purity product saves time, manpower, and resource costs.
[0054] Preferably, in step S03, the number of plates in the de-gravity distillation column 3 is 50-100. High-efficiency plate distillation columns have high mass transfer and separation efficiencies, enabling more thorough separation of trichlorosilane O1 from other impurities. This helps improve the purity and quality of the product, ensuring high-purity trichlorosilane O1 collected from the top of the column.
[0055] This invention also provides a trichlorosilane purification system for the preparation described above. The various components of the system are connected to form a unified whole, achieving an organic combination of steps such as light component removal, extraction, heavy component removal, and solvent removal. This integrated operation makes the entire purification process more compact and efficient, reducing potential intermediate steps and resource waste. Compared with conventional distillation, it helps to reduce the number of trays and energy consumption.
[0056] Specifically, such as Figure 1 As shown, a trichlorosilane purification system, employing the above-mentioned purification method for trichlorosilane 01, includes:
[0057] Light component removal tower 1 is used to remove light components from crude trichlorosilane 01;
[0058] Extractive distillation column 2 has a first feed port 21 at its lower part that is connected to the output end of the reboiler of light removal column 1, and a second feed port 22 at its upper part for the extractant O2 to enter. The top and reboiler of extractive distillation column 2 are respectively provided with a first outlet 23 and a second outlet 24.
[0059] The heavy distillation column 3 is equipped with a third feed inlet 31, which is connected to the first discharge outlet 23.
[0060] The solvent removal tower 4 is provided with a fourth feed port 41 connected to the second discharge port 24, and the bottom of the solvent removal tower 4 is connected to the second feed port 22.
[0061] The control center is electrically connected to the light-light residue removal column 1, extractive distillation column 2, heavy-weight residue removal distillation column 3, and solvent removal column 4, and performs quality control and real-time monitoring of these components. This facilitates the timely detection of potential problems and anomalies, allowing for appropriate adjustments and corrections to ensure the stable operation of the entire system and the consistency of product quality. The various components in the system operate collaboratively through a rational connection method, achieving a continuous and efficient trichlorosilane O1 purification process. The real-time monitoring and quality control functions of the control center help optimize operating parameters, improving production efficiency and product quality. This invention, by achieving integrated operation, real-time monitoring, and quality control, helps improve production efficiency, reduce costs, and ensure product quality.
[0062] Furthermore, the top output of the light emission removal tower 1 is also connected to a phosphorus adsorber 5 to prevent phosphorus from accumulating in the system and affecting the product quality of polycrystalline silicon.
[0063] The following is an analysis of the extractive distillation column:
[0064] Example 1:
[0065] The feed is crude trichlorosilane 01, containing methyl dichlorosilane at a mass content of 4 ppm. The solvent (extractant 02) is used at 0.02% of the feed. The column has 50 trays, with 10 trays for the solvent feed. The operating pressure is 1.5 bar, and the reflux ratio is 4. The relationship between the methyl dichlorosilane content at the top of the column and the feed tray content is as follows: Figure 2 and Figure 3 As shown, it can be seen that at this reflux ratio, the total number of trays is relatively small, which is not conducive to the separation of methyldichlorosilane and trichlorosilane O1.
[0066] Example 2:
[0067] The feed is crude trichlorosilane 01, containing methyl dichlorosilane at a mass content of 4 ppm. The solvent (extractant 02) is used at 0.02% of the feed. The column has 100 trays, with 10 trays for the solvent feed. The operating pressure is 1.5 bar, and the reflux ratio is 4. The relationship between the methyl dichlorosilane content at the top of the column and the feed tray content is as follows: Figure 4 and Figure 5 As shown, when there are 40 feed plates, the content of methyl dichlorosilane at the top of the column is the lowest, on the order of 10E-8. When there are 40 feed plates, changing the feed position of extractant 02, the separation effect is the best when the feed plate of extractant 02 is the 7th plate, at which time the content of methyl dichlorosilane at the top of the column is 2.9E-8.
[0068] Example 3:
[0069] The feed is crude trichlorosilane 01, containing 4 ppm methyl dichlorosilane by mass. The solvent (extractant 02) is used at 0.02% of the feed. The column has 150 trays, with 10 trays for the solvent feed. The operating pressure is 1.5 bar, and the reflux ratio is 4. The relationship between the methyl dichlorosilane content at the top of the column and the feed tray content is as follows: Figure 6 and Figure 7 As shown in the figure, it can be seen that the content of methyl dichlorosilane at the top of the column is the lowest when the raw material feed plate is located at plate 88. After that, when the raw material feed plate is located at plate 88, the feed position of extractant 02 is changed. It can be seen from the figure that the optimal feed position of extractant 02 is plate 8.
[0070] Example 4:
[0071] The feed is crude trichlorosilane 01, containing methyl dichlorosilane at a mass content of 4 ppm. The solvent (extractant 02) is used at 0.02% of the feed. The column has 150 trays, with 8 trays for solvent feed and 88 trays for feed. The reflux ratio is 4. The relationship between the methyl dichlorosilane content at the top of the column and the reflux ratio is as follows: Figure 8 As shown in the table below, increasing the reflux ratio gradually decreases the methyl dichlorosilane content at the top of the column.
[0072] reflux ratio Content at the top of the tower Top content 2 0.999994245 8.77E-07 3 0.999998356 4.15E-08 4 0.999999184 4.40E-10 5 0.999999489 1.70E-11 6 0.99999964 1.72E-12 7 0.999999728 3.23E-13 8 0.999999783 9.14E-14 9 0.999999821 3.44E-14
[0073] Comparative Example 1
[0074] The feed was crude trichlorosilane 01, containing 4 ppm of methyl dichlorosilane. It was directly separated and purified using conventional distillation. The theoretical number of plates was 150, the optimal feed plate number was 75, the operating pressure was 1.5 bar, and the reflux ratio was 4. Under these conditions, the results of this distillation column and extractive distillation are shown below:
[0075] Ordinary distillation Extractive distillation The content of methyl dichlorosilane at the top of the tower 1.76E-9 2.9E-10
[0076] As can be seen from the table above, under the same conditions, the residual amount of methyl dichlorosilane in the material collected from the top of the extractive distillation column is reduced to about 1 / 6 of the residual amount in ordinary distillation, indicating that extractive distillation has more advantages than ordinary distillation in the preparation of high purity.
[0077] Comparative Example 2 (compared to Example 4):
[0078] Methyldichlorosilane content in extractant 02 (wt.%) Methyl dichlorosilane content at the top of the tower 0.1 7.9E-8 0.05 3.96E-8 0.01 8.17E-9 0.005 4.23E-9
[0079] The table shows that the lower the content of methyldichlorosilane in the extractant, the better.
[0080] Comparative Example 3 (compared to Example 4):
[0081] Amount of extractant 02 (based on feed amount) / wt.% Methyl dichlorosilane content at the top of the tower 0.01 1.04E-9 0.02 2.9E-10 0.05 2.31E-10 0.1 2.1E-10
[0082] The table shows that a good purification effect can be achieved when the amount of extractant 02 is only 0.02% of the raw material.
[0083] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, and the existence of an infinite number of specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.
Claims
1. A method for purifying trichlorosilane, characterized in that: The following steps are included: S01: Crude trichlorosilane is introduced into the light component removal tower to remove light components; S02: Crude trichlorosilane after being treated by S01 is collected from the bottom of the light-light-removal tower and enters the lower part of the extractive distillation tower for extraction with the extractant introduced from the upper part of the extractive distillation tower; and by utilizing the boiling point difference of different components, pure trichlorosilane at the top of the tower and extractant containing methyl dichlorosilane at the bottom of the tower are separated; the extractant is silicon tetrachloride. S03: The pure trichlorosilane collected from the top of the extractive distillation column is sent to the heavy removal distillation column for further purification. After purification, high-purity trichlorosilane is output from the top of the column for use, and the bottom material is introduced into step S02 as an extractant. S04: The extractant containing methyldichlorosilane collected from the bottom of the extractive distillation column is sent to the desolventizing column for recovery and purification. After purification, the methyldichlorosilane is removed from the top of the column, and the material collected from the bottom of the column is introduced into the upper part of the extractive distillation column as the extractant.
2. The method for purifying trichlorosilane according to claim 1, characterized in that: In step S01, crude trichlorosilane refers to the crude product after preliminary separation to remove silicon tetrachloride and high-boiling substances.
3. The method for purifying trichlorosilane according to claim 2, characterized in that: In step S01, the dichlorosilane and other light component impurities collected from the top of the light component removal tower are introduced into the phosphorus removal adsorber to remove phosphorus-containing compounds.
4. The method for purifying trichlorosilane according to claim 1, characterized in that: In step S02, the content of methyl dichlorosilane in the extractant is less than 2%.
5. The method for purifying trichlorosilane according to claim 1, characterized in that: In step S02, the number of theoretical plates in the extractive distillation column is ≥50, and the operating pressure of the extractive distillation column is 1.2~4 bar.
6. The method for purifying trichlorosilane according to claim 5, characterized in that: In step S02, when feeding the material, the amount of extractant used is 0.01% to 0.1% of the crude trichlorosilane.
7. The method for purifying trichlorosilane according to claim 1, characterized in that: In step S03, the number of plates in the degravation distillation column is 50-100.
8. A trichlorosilane purification system, characterized in that: The purification method for trichlorosilane according to claims 1-7 includes: Light component removal tower is used to remove light components from crude trichlorosilane; An extractive distillation column is provided with a first feed inlet at the lower part of the extractive distillation column and connected to the output end of the light-removal column. A second feed inlet for the extractant is provided at the upper part of the extractive distillation column. A first outlet and a second outlet are respectively provided at the top and bottom of the extractive distillation column. A heavy-density distillation column is provided with a third feed inlet, which is connected to the first discharge outlet. A solvent removal tower is provided with a fourth inlet connected to the second outlet, and the bottom of the solvent removal tower is connected to the second inlet; The control center is electrically connected to the light-light removal column, the extractive distillation column, the heavy-weight removal distillation column, and the solvent removal column to perform quality control and real-time monitoring of the light-light removal column, the extractive distillation column, the heavy-weight removal distillation column, and the solvent removal column.
9. A trichlorosilane purification system according to claim 8, characterized in that: The top output of the light phosphorus removal tower is also connected to a phosphorus adsorbent to prevent phosphorus from accumulating in the system.