A trimethylsilane purification system and method containing dichlorohydrosilane impurities

Abstract

The application discloses a trimethylsilane purification system containing dichlorosilane impurities, comprising a reaction rectifying tower and a purification rectifying tower, and discloses a trimethylsilane purification method containing dichlorosilane impurities. Trimethylsilane gas containing dichlorosilane impurities enters the reaction rectifying tower, and the trimethylsilane gas containing dichlorosilane impurities enters a reaction section to react. Dichlorosilane impurities react to generate silane gas and material containing tetrachlorosilane impurities. The silane gas is discharged from a tower top exhaust port of the reaction rectifying tower, and the material containing tetrachlorosilane impurities is discharged from a tower bottom discharge port of the reaction rectifying tower and enters the purification rectifying tower. The high-purity trimethylsilane is collected in a tower top collecting port through rectification in the purification rectifying tower. The dichlorosilane impurities in the trimethylsilane can be effectively removed through the method disclosed by the application, high-purity trimethylsilane with a purity of more than 99.99% is obtained, the yield is greater than 85%, and the process is simple and low in cost.

Description

Technical Field

[0001] The present 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, and somewhat irritating gas with unique chemical properties and applications. Trimethylsilane is widely used in chemical synthesis, surface treatment, coatings and inks, pharmaceuticals, and other fields. Its most widespread application is in the semiconductor manufacturing industry. It is used as a precursor material in chemical vapor deposition (CVD) and physical vapor deposition (PVD) processes to produce high-purity silicon thin 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 the thin film material. 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, of 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, methyltrichlorosilane, dimethyldichlorosilane, dimethylsilane and other silane series impurities, 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, the trimethylsilane preparation process will contain dichlorosilane impurities. The boiling point of dichlorosilane impurities is close to that of 3MS, and it forms an azeotropic mixture 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 response to the shortcomings of the prior art, the present invention discloses a system and method for purifying trimethylsilane containing dichlorosilane as an impurity. The present invention utilizes a coupled reaction and distillation method to effectively remove the dichlorosilane impurity from trimethylsilane, thereby obtaining high-purity trimethylsilane with a purity of over 99.99%. The process of the present invention not only solves the problem that conventional distillation cannot remove the dichlorosilane impurity, but also is simple and efficient, greatly reducing production costs.

[0005] The technical solution adopted in 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, 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 provided 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 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 rectification section accounts for 50% to 60%, the number of plates in the reaction section accounts for 10% to 20%, and the balance 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, comprising the following steps:

[0010] Trimethylsilane gas containing dichlorosilane impurities enters the reactive distillation tower. The trimethylsilane gas containing dichlorosilane impurities then enters the reaction zone for reaction. The dichlorosilane impurities react to produce silane gas and a material containing tetrachlorosilane impurities. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a relatively higher boiling point. The silane gas is discharged from the top exhaust port of the reactive distillation tower, while the material containing tetrachlorosilane impurities enters the purification distillation tower from the bottom outlet of the reactive 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 top collection port of the tower, and the high-boiling-point impurity material of tetrachlorosilane obtained by the reaction is collected at the bottom discharge port 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 dichlorosilane content in the trimethylsilane gas containing dichlorosilane impurities is 100 to 10,000 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 collected from the reaction 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. A combination of reactive distillation and purification distillation is used to remove dichlorosilane impurities with a boiling point close to that of trimethylsilane, ensuring good process continuity.

[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 impurity removal.

[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 This 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 a gas chromatogram of the trimethylsilane product of Comparative Example 1 of the present invention;

[0027] Figure 6 This is a 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 accompanying drawings, 1-reaction distillation tower, 2-purification distillation tower, 11-distillation section, 12-reaction section, 13-stripping section. Specific embodiments

[0030] Device Example

[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. The reaction distillation tower bottom discharge port is connected to the purification distillation tower feed inlet.

[0032] Method Example

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

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

[0035] The reactive distillation tower operates at a pressure of 0.1-0.15 MPa and a temperature of 15-40°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. Silane gas is discharged from the top of the reactive distillation tower. The bottom of the tower, containing the tetrachlorosilane impurity, enters the purification distillation tower.

[0036] The pressure of the purification distillation tower is 0.02-0.1 MPa 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 the high-content tetrachlorosilane high-boiling point impurity material obtained by the reaction is 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] Trimethylsilane gas containing 3000ppm of 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 tower has 100 theoretical plates, 50 in the rectification section, 10 in the reaction section, and 40 in the stripping section.

[0040] The reactive distillation tower operates at a pressure of 0.1 MPa and a temperature of 20-30°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. The silane-containing gas is discharged from the top of the reactive distillation tower at a rate of 5% of the feed. The bottom of the tower, containing the tetrachlorosilane impurity, 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 FIG. 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] Trimethylsilane gas containing 8000ppm of 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 tower has 150 theoretical plates, 80 in the rectification section, 25 in the reaction section, and 45 in the stripping section.

[0045] The reactive distillation tower operates at a pressure of 0.15 MPa and a temperature of 30-40°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. The silane-containing gas is discharged from the top of the reactive distillation tower at a rate of 6% of the feed. The bottom of the tower, containing the tetrachlorosilane impurity, 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 FIG. Figure 3 The high-content tetrachlorosilane high-boiling point 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] Trimethylsilane gas containing 500ppm of 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 tower has 80 theoretical plates, 40 in the rectification section, 8 in the reaction section, and 32 in the stripping section.

[0050] The reactive distillation tower operates at a pressure of 0.12 MPa and a temperature of 25-35°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. The silane-containing gas is discharged from the top of the reactive distillation tower at a rate of 4% of the feed. The bottom of the tower, containing the tetrachlorosilane impurity, 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 FIG. Figure 4 The high-content tetrachlorosilane high-boiling point 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] Trimethylsilane gas containing 3000ppm of 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 tower has 100 theoretical plates, 58 in the rectification section, two in the reaction section, and 40 in the stripping section.

[0055] The reactive distillation tower operates at a pressure of 0.1 MPa and a temperature of 20-30°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. The silane-containing gas is discharged from the top of the reactive distillation tower at a rate of 5% of the feed. The bottom of the tower, containing the tetrachlorosilane impurity, enters the purification distillation tower.

[0056] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20℃, the theoretical plate number 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 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] Trimethylsilane gas containing 3000ppm of 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 tower has 100 theoretical plates, 30 in the rectification section, 10 in the reaction section, and 60 in the stripping section.

[0060] The reactive distillation tower operates at a pressure of 0.1 MPa and a temperature of 20-30°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. The silane-containing gas is discharged from the top of the reactive distillation tower at a rate of 5% of the feed. The bottom of the tower, containing the tetrachlorosilane impurity, enters the purification distillation tower.

[0061] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20℃, the theoretical plate number 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. See the chromatogram. Figure 6 .

[0063] Comparative Example 3

[0064] Trimethylsilane gas containing 3000ppm of 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 tower has 100 theoretical plates, 70 in the rectification section, 10 in the reaction section, and 20 in the stripping section.

[0065] The reactive distillation tower operates at a pressure of 0.1 MPa and a temperature of 20-30°C. Gas enters the reaction section of the reactive distillation tower, where it reacts with dichlorosilane impurities to produce silane and tetrachlorosilane. Silane has a lower boiling point than trimethylsilane, while tetrachlorosilane has a higher boiling point. The silane-containing gas is discharged from the top of the reactive distillation tower at a rate of 5% of the feed. The bottom of the tower, containing the tetrachlorosilane impurity, enters the purification distillation tower.

[0066] The pressure of the purification distillation tower is 0.02MPa, the temperature is 5-20℃, the theoretical plate number 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 tetrachlorosilane impurity content is still relatively high. See the chromatogram. Figure 7 .

[0068] At present, the technical solution of this application has adopted the best implementation method 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 carried out 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 method of the present invention; but the protection scope of the present invention is not limited to this; any technician familiar with this technical field within the technical scope disclosed by the present invention; according to the technical solution and its improved conception, they are equivalently replaced or changed; all should be covered within the protection scope of the present invention.

Claims

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

2. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 1, characterized in that: The pressure of the reactive distillation tower is 0.1~0.15MPa, and the temperature is 15~40℃.

3. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 1, characterized in that: The pressure of the purification distillation tower is 0.02~0.1MPa and the temperature is 5~25℃.

4. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 1, characterized in that: The dichlorosilane content in the trimethylsilane gas containing dichlorosilane impurities is 100-10000 ppm.

5. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 1, 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%.

6. The method for purifying trimethylsilane containing dichlorosilane impurities according to claim 1, 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 distillation tower to the trimethylsilane gas containing dichlorosilane impurities is 3% to 5%.

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