System and method for purifying trimethylsilane containing dichlorosilane impurity

Abstract

The invention discloses a system for purifying trimethylsilane containing dichlorosilane impurities, which comprises a reactive distillation column and a purification distillation column, and also discloses a method for purifying trimethylsilane containing dichlorosilane impurities, which comprises the following steps of: feeding trimethylsilane gas containing dichlorosilane impurities into the reactive distillation column; trimethylsilane gas containing dichlorosilane impurities enters the reaction section to react, the dichlorosilane impurities react to generate silane gas and a material containing tetrachlorosilane impurities, the silane gas is discharged from an exhaust port in the top of the reactive distillation tower, and the material containing tetrachlorosilane impurities enters the purification distillation tower from a discharge port in the bottom of the reactive distillation tower; according to the method disclosed by the invention, dichlorosilane is taken as a raw material, the dichlorosilane is taken as a raw material, the dichlorosilane is rectified in a purification rectifying tower and is collected at a tower top collecting port to obtain the high-purity trimethylsilane, the dichlorosilane impurity in the trimethylsilane can be effectively removed through the method disclosed by the invention, the high-purity trimethylsilane with the purity of 99.99% or above is obtained, the yield is greater than 85%, the process is simple, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and in particular relates to a system and method for purifying trimethylsilane containing dichlorosilane impurities. Background Art

[0002] Trimethylsilane (3MS) is an organosilicon compound with the chemical formula (CH3)3SiH. It is a colorless, volatile, somewhat irritating gas with special chemical properties and application areas. Trimethylsilane is widely used in chemical synthesis, surface treatment, coatings and inks, medicine and other fields. It is most widely used in the semiconductor manufacturing industry. It is used as a precursor material in the chemical vapor deposition (CVD) and physical vapor deposition (PVD) processes to manufacture high-purity silicon films and other thin film materials. With the rapid development of the semiconductor manufacturing industry and related industries, the demand for 3MS continues to increase.

[0003] However, 3MS used in semiconductor processes requires a higher purity, otherwise it will have a serious impact on the quality of thin film materials. The purity of electronic-grade 3MS for semiconductors needs to reach more than 99.99%. Due to different preparation methods, the obtained trimethylsilane products contain different impurities, among which a large part of the impurities can be removed by distillation, adsorption and other methods. CN116082380A discloses a 3MS preparation method that essentially eliminates the production of silane series impurities such as silane, methyltrichlorosilane, dimethyldichlorosilane, and dimethylsilane, and uses a distillation method to remove impurities such as trimethylchlorosilane. CN104136447A discloses a method for purifying trimethylsilane, which uses activated carbon adsorption to efficiently remove impurities such as dimethylsilane. However, in addition to this, trimethylsilane preparation process will contain dichlorosilane impurities, dichlorosilane impurities have a boiling point close to 3MS, and form an azeotropic reaction with 3MS. It is difficult to effectively remove them by conventional distillation, which seriously affects the purity of the product. Summary of the invention

[0004] In view of the defects of the prior art, the present invention discloses a system and method for purifying trimethylsilane containing dichlorosilane impurities; the present invention adopts a reaction and distillation coupling method to effectively remove the dichlorosilane impurity in trimethylsilane, and obtain high-purity trimethylsilane with a purity of more than 99.99%; the process of the present invention not only solves the problem that conventional distillation cannot remove the dichlorosilane impurity, but also the process is simple and efficient, greatly reducing the production cost.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A trimethylsilane purification system containing dichlorosilane impurities comprises a reaction distillation tower and a purification distillation tower, wherein the reaction distillation tower is provided with a reaction distillation tower air inlet, a tower top exhaust port and a reaction distillation tower bottom discharge port, the reaction distillation tower is divided into a distillation section, a reaction section and a stripping section from top to bottom, the reaction distillation tower air inlet is arranged on the reaction section, the purification distillation tower comprises a purification distillation tower feed inlet, a tower top collecting port and a purification distillation tower bottom discharge port, and the reaction distillation tower bottom discharge port is connected to the purification distillation tower feed inlet.

[0007] Preferably, the number of plates in the reactive distillation tower is 80 to 150; the number of plates in the distillation section accounts for 50% to 60%, the number of plates in the reaction section accounts for 10% to 20%, and the remainder is the number of plates in the stripping section.

[0008] Preferably, the number of plates in the purification distillation tower is 80 to 150.

[0009] A method for purifying trimethylsilane containing dichlorosilane impurities, the steps are as follows:

[0010] The trimethylsilane gas containing dichlorosilane impurities enters the reaction distillation tower, and the trimethylsilane gas containing dichlorosilane impurities enters the reaction section for reaction. The dichlorosilane impurities react to generate silane gas and materials containing tetrachlorosilane impurities, wherein the boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane gas is discharged from the top exhaust port of the reaction distillation tower, and the materials containing tetrachlorosilane impurities enter the purification distillation tower from the bottom discharge port of the reaction distillation tower;

[0011] After distillation in a purification distillation tower, high-purity trimethylsilane with a purity of more than 99.99% is collected at the collection port on the top of the tower, and the high-boiling-point impurity material of tetrachlorosilane obtained by the reaction is collected at the discharge port at the bottom of the purification distillation tower.

[0012] Preferably, the reaction distillation tower has a pressure of 0.1-0.15 MPa and a temperature of 15-40°C.

[0013] Preferably, the pressure of the purification distillation tower is 0.02-0.1 MPa and the temperature is 5-25°C.

[0014] Preferably, the content of dichlorosilane in the trimethylsilane gas containing dichlorosilane impurities is 100 to 10000 ppm.

[0015] Preferably, the mass ratio of the silane gas discharged from the exhaust port at the top of the reactive distillation tower to the trimethylsilane gas containing dichlorosilane impurities is 3% to 6%.

[0016] Preferably, the mass ratio of the tetrachlorosilane high-boiling point impurity material obtained by the reaction collected at the bottom discharge port of the purification distillation tower to the trimethylsilane gas containing dichlorosilane impurities is 3% to 5%.

[0017] The beneficial effects of the present invention are:

[0018] The inlet gas of the present invention is subjected to reactive distillation and purification distillation to prepare high-purity trimethylsilane with a purity greater than 99.99%, wherein the trimethylsilane product yield is ≥85%.

[0019] 1. The reaction distillation and purification distillation are combined to remove dichlorosilane impurities with a boiling point close to that of trimethylsilane, and the process continuity is good.

[0020] 2. By optimizing parameters such as pressure and temperature during the purification process, lower heating and cooling energy consumption can be used to achieve efficient removal of impurities.

[0021] 3. The process requires fewer equipment and auxiliary materials, and the resulting product yield is higher, significantly reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of a method for purifying trimethylsilane containing dichlorosilane impurities according to the present invention;

[0023] Figure 2 This is a gas chromatogram of the high-purity trimethylsilane product of Example 1 of the present invention;

[0024] Figure 3 This is a gas chromatogram of the high-purity trimethylsilane product of Example 2 of the present invention;

[0025] Figure 4 This is a gas chromatogram of the high-purity trimethylsilane product of Example 3 of the present invention;

[0026] Figure 5 This is the gas chromatogram of trimethylsilane product of Comparative Example 1 of the present invention;

[0027] Figure 6 This is the gas chromatogram of trimethylsilane product of Comparative Example 2 of the present invention;

[0028] Figure 7 This is the gas chromatogram of trimethylsilane product of Comparative Example 3 of the present invention.

[0029] In the attached drawings, 1-reaction distillation tower, 2-purification distillation tower, 11-distillation section, 12-reaction section, 13-stripping section. Specific embodiments

[0030] Device Embodiment

[0031] like Figure 1As shown, a trimethylsilane purification system containing dichlorosilane impurities includes a reaction distillation tower 1 and a purification distillation tower 2, the number of plates in the reaction distillation tower 1 and the number of plates in the purification distillation tower 2 are both 80 to 150, the reaction distillation tower 1 is provided with a reaction distillation tower air inlet, a tower top exhaust port and a reaction distillation tower bottom discharge port, the reaction distillation tower 1 is divided into a distillation section 11 (the number of plates accounts for 50% to 60%), a reaction section 12 (the number of plates accounts for 10% to 20%) and a stripping section 13 from top to bottom, the reaction distillation tower air inlet is arranged on the reaction section 12, the purification distillation tower 2 includes a purification distillation tower feed inlet, a tower top collecting port and a purification distillation tower bottom discharge port, and the reaction distillation tower bottom discharge port is connected to the purification distillation tower feed inlet.

[0032] Method Embodiment

[0033] The present invention discloses a method for purifying trimethylsilane containing dichlorosilane impurities, which is implemented by using a system of an equipment embodiment and the following steps:

[0034] The trimethylsilane gas containing a certain amount of dichlorosilane impurities enters the reaction distillation tower, which is divided into a distillation section, a reaction section and a stripping section from top to bottom.

[0035] The pressure of the reaction distillation tower is 0.1-0.15MPa, and the temperature is 15-40℃. The gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. Silane gas is discharged from the top of the reaction distillation tower. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0036] The pressure of the purification distillation tower is 0.02-0.1MPa and the temperature is 5-30°C. After distillation in the purification distillation tower, high-purity trimethylsilane with a purity of more than 99.99% is obtained at the top of the tower, and high-content tetrachlorosilane high-boiling point impurity materials obtained by the reaction are separated at the bottom of the tower.

[0037] The processes in Examples 1-3 are all the same, and the present invention is not described one by one in a single example.

[0038] Example 1

[0039] The trimethylsilane gas containing 3000ppm dichlorosilane impurities enters the reactive distillation tower, which is divided into a rectification section, a reaction section and a stripping section from top to bottom. The number of theoretical plates in the tower is 100, including 50 in the rectification section, 10 in the reaction section and 40 in the stripping section.

[0040] The pressure of the reaction distillation tower is 0.1MPa, the temperature is 20-30℃, the gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane-containing gas is discharged from the top of the reaction distillation tower, and the discharge amount is 5% of the feed amount. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0041] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20℃, and the theoretical plate number is 100. After distillation in the purification distillation tower, high-purity trimethylsilane with a purity of 99.997% is obtained at the top of the tower. The chromatogram is shown in Figure 2 The high-content tetrachlorosilane high-boiling point impurity material obtained by the reaction is separated at the bottom of the tower, accounting for 4% of the feed amount.

[0042] The final trimethylsilane yield was 88%.

[0043] Example 2

[0044] The trimethylsilane gas containing 8000ppm dichlorosilane impurities enters the reactive distillation tower, which is divided into a rectification section, a reaction section and a stripping section from top to bottom. The number of theoretical plates in the tower is 150, including 80 in the rectification section, 25 in the reaction section and 45 in the stripping section.

[0045] The pressure of the reaction distillation tower is 0.15MPa, the temperature is 30-40℃, the gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane-containing gas is discharged from the top of the reaction distillation tower, and the discharge amount is 6% of the feed amount. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0046] The pressure of the purification distillation tower is 0.05MPa, the temperature is 15-25℃, and the theoretical plate number is 150. After distillation in the purification distillation tower, high-purity trimethylsilane with a purity of 99.995% is obtained at the top of the tower. The chromatogram is shown in Figure 3 The high-content tetrachlorosilane high-boiling impurity material obtained by the reaction is separated at the bottom of the tower, accounting for 5% of the feed amount.

[0047] The final trimethylsilane yield was 86%.

[0048] Example 3

[0049] The trimethylsilane gas containing 500ppm dichlorosilane impurities enters the reactive distillation tower, which is divided into a rectification section, a reaction section and a stripping section from top to bottom. The number of theoretical plates in the tower is 80, including 40 in the rectification section, 8 in the reaction section and 32 in the stripping section.

[0050] The pressure of the reaction distillation tower is 0.12MPa, the temperature is 25-35℃, the gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane-containing gas is discharged from the top of the reaction distillation tower, and the discharge amount is 4% of the feed amount. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0051] The pressure of the purification distillation tower is 0.04MPa, the temperature is 13-23℃, and the theoretical plate number is 80. After distillation in the purification distillation tower, high-purity trimethylsilane with a purity of 99.994% is obtained at the top of the tower. The chromatogram is shown in Figure 4 The high-content tetrachlorosilane high-boiling impurity material obtained by the reaction is separated at the bottom of the tower, accounting for 3% of the feed amount.

[0052] The final trimethylsilane yield was 87%.

[0053] Comparative Example 1

[0054] The trimethylsilane gas containing 3000ppm dichlorosilane impurities enters the reactive distillation tower, which is divided into a rectification section, a reaction section and a stripping section from top to bottom. The number of theoretical plates in the tower is 100, with 58 plates in the rectification section, 2 plates in the reaction section and 40 plates in the stripping section.

[0055] The pressure of the reaction distillation tower is 0.1MPa, the temperature is 20-30℃, the gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane-containing gas is discharged from the top of the reaction distillation tower, and the discharge amount is 5% of the feed amount. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0056] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20°C, the theoretical number of plates is 100, and distillation is performed in the purification distillation tower.

[0057] Since the number of plates in the reaction section is small and not within the technical requirements, the dichlorosilane in the material is not completely reacted, so that the purity of the trimethylsilane product finally obtained at the top of the tower is only 99.96%, and the impurity content of dichlorosilane is still high. See the chromatogram. Figure 5 .

[0058] Comparative Example 2

[0059] The trimethylsilane gas containing 3000ppm dichlorosilane impurities enters the reactive distillation tower, which is divided into a rectification section, a reaction section and a stripping section from top to bottom. The number of theoretical plates in the tower is 100, including 30 in the rectification section, 10 in the reaction section and 60 in the stripping section.

[0060] The pressure of the reaction distillation tower is 0.1MPa, the temperature is 20-30℃, the gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane-containing gas is discharged from the top of the reaction distillation tower, and the discharge amount is 5% of the feed amount. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0061] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20°C, the theoretical number of plates is 100, and distillation is performed in the purification distillation tower.

[0062] Since the number of distillation plates is small and not within the technical requirements, the silane in the material is not completely removed, so that the purity of the trimethylsilane product finally obtained at the top of the tower is only 99.98%, and the silane impurity content is still high. The chromatogram is shown in Figure 6 .

[0063] Comparative Example 3

[0064] The trimethylsilane gas containing 3000ppm dichlorosilane impurities enters the reactive distillation tower, which is divided into a rectification section, a reaction section and a stripping section from top to bottom. The number of theoretical plates in the tower is 100, including 70 in the rectification section, 10 in the reaction section and 20 in the stripping section.

[0065] The pressure of the reaction distillation tower is 0.1MPa, the temperature is 20-30℃, the gas enters the reaction section of the reaction distillation tower for reaction, and the dichlorosilane impurity reacts to generate silane and tetrachlorosilane. The boiling point of silane is lower than that of trimethylsilane, and the boiling point of tetrachlorosilane is relatively high. The silane-containing gas is discharged from the top of the reaction distillation tower, and the discharge amount is 5% of the feed amount. The material containing tetrachlorosilane impurities at the bottom of the tower enters the purification distillation tower.

[0066] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20°C, the theoretical number of plates is 100, and distillation is performed in the purification distillation tower.

[0067] Since the number of distillation plates is small and not within the technical requirements, the tetrachlorosilane in the material is not completely removed, so that the purity of the trimethylsilane product finally obtained at the top of the tower is only 99.97%, and the impurity content of tetrachlorosilane is still high. See the chromatogram. Figure 7 .

[0068] At present, the technical solution of the present application has adopted the best implementation mode of Example 1, and has been pilot-tested, that is, a small-scale experiment of the product before large-scale mass production; after the pilot-test was completed, a user usage survey was conducted in a small range, and the survey results showed that user satisfaction was high; now preparations have been made for the formal production and industrialization of the product (including intellectual property risk warning surveys); the above is only a preferred specific implementation mode of the present invention; but the protection scope of the present invention is not limited to this; any technician familiar with the technical field within the technical scope disclosed by the present invention; according to the technical solution and its improved conception of the present invention, they are equivalently replaced or changed; all should be covered within the protection scope of the present invention.

Claims

1. A trimethylsilane purification system containing dichlorosilane impurities, characterized in that: The invention comprises a reaction distillation tower and a purification distillation tower, wherein the reaction distillation tower is provided with a reaction distillation tower air inlet, a tower top exhaust port and a reaction distillation tower bottom discharge port, and the reaction distillation tower is divided into a distillation section, a reaction section and a stripping section from top to bottom, wherein the reaction distillation tower air inlet is arranged on the reaction section, and the purification distillation tower comprises a purification distillation tower feed inlet, a tower top collecting port and a purification distillation tower bottom discharge port, and the reaction distillation tower bottom discharge port is connected with the purification distillation tower feed inlet.

2. A trimethylsilane purification system containing dichlorosilane impurities according to claim 1, characterized in that: The number of plates in the reaction distillation tower is 80 to 150; the number of plates in the distillation section accounts for 50% to 60%, the number of plates in the reaction section accounts for 10% to 20%, and the remainder is the number of plates in the stripping section.

3. A trimethylsilane purification system containing dichlorosilane impurities according to claim 1, characterized in that: The number of plates in the purification distillation tower is 80 to 150.

4. A method for purifying trimethylsilane containing dichlorosilane impurities, using a trimethylsilane purification system containing dichlorosilane impurities according to any one of claims 1 to 3, characterized in that: Here are the steps: The trimethylsilane gas containing dichlorosilane impurities enters the reaction distillation tower, and the trimethylsilane gas containing dichlorosilane impurities enters the reaction section for reaction. The dichlorosilane impurities react to generate silane gas and materials containing tetrachlorosilane impurities. The silane gas is discharged from the top exhaust port of the reaction distillation tower, and the materials containing tetrachlorosilane impurities enter the purification distillation tower from the bottom discharge port of the reaction distillation tower; After distillation in a purification distillation tower, high-purity trimethylsilane with a purity of more than 99.99% is collected at the collection port on the top of the tower, and the high-boiling-point impurity material of tetrachlorosilane obtained by the reaction is collected at the discharge port at the bottom of the purification distillation tower.

5. A method for purifying trimethylsilane containing dichlorosilane impurities according to claim 4, characterized in that: The pressure of the reaction distillation tower is 0.1~0.15MPa, and the temperature is 15~40℃.

6. A method for purifying trimethylsilane containing dichlorosilane impurities according to claim 4, characterized in that: The pressure of the purification distillation tower is 0.02~0.1MPa, and the temperature is 5~25℃.

7. A method for purifying trimethylsilane containing dichlorosilane impurities according to claim 4, characterized in that: The content of dichlorosilane in the trimethylsilane gas containing dichlorosilane impurities is 100 to 10000 ppm.

8. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 4, characterized in that: The mass ratio of the silane gas discharged from the exhaust port at the top of the reactive distillation tower to the trimethylsilane gas containing dichlorosilane impurities is 3% to 6%.

9. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 4, characterized in that: The mass ratio of the tetrachlorosilane high boiling point impurity material obtained by the reaction collected at the bottom discharge port of the purification and rectification tower to the trimethylsilane gas containing dichlorosilane impurities is 3% to 5%.

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