System and process for purifying impurity gas in disilane product synthesized from silane

Abstract

The invention discloses a system for purifying impurity gas in a disilane product synthesized from silane. The system comprises a membrane separation device, a fan, a first rectifying tower and a second rectifying tower which are communicated in sequence, the invention further relates to a process for purifying the impurity gas in the product of synthesizing the disilane from the silane, high-content hydrogen and other light components in the product gas of synthesizing the disilane from the silane are primarily separated from the silane, the disilane and the trisilane by adopting a membrane separation mode, then rectification separation is carried out, the purity of the recovered disilane is up to 99.995% or above, the purity of the recovered disilane is up to 99.995% or above, the purity of the recovered disilane is up to 99.995% or above, and the purity of the recovered disilane is up to 99.995% or above. The process is efficient, simple and low in energy consumption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fine chemical industry, and particularly relates to a system and process for purifying impurity gases in a product of synthesis of disilane from silane. BACKGROUND

[0002] Disilane is a silicon-based electronic special gas widely used in the integrated circuit and solar cell related industries. Due to its fast film formation rate, high film formation density, high quality and suitable process conditions, it is widely used in silicon wafer epitaxial growth, amorphous silicon thin film deposition and other processes. However, these applications require high purity disilane. The current industrial disilane synthesis process mainly includes magnesium silicide reacting with halogenated ammonia or hydrochloric acid, and silane cracking to synthesize disilane. The direct synthesis of silane is relatively simple, and involves fewer by-products and impurities, so it has been widely used in industry. Depending on the external energy, the silane cracking method includes thermal cracking, discharge cracking and photolysis. Generally, hydrogen, helium or argon is used as a diluent gas, and high-order silane polymers are also produced during the silane cracking process, which poses a challenge to the efficient removal of light and heavy components and other impurities in the product.

[0003] CN112663074B discloses a system for electrocatalytic synthesis of high-purity disilane, which includes an electrocatalytic reactor, a buffer tank, a gas compression device, a hydrogen separation device and a disilane separation and purification device. The reaction process produces a mixture of monosilane, hydrogen, disilane and high silane. The light component gases such as hydrogen are removed by compression and gas-liquid separation, while the heavy components such as high silane are removed by distillation separation. Similarly, CN115477305A uses rectification or distillation to remove hydrogen and high-order silane impurities in the reaction product by using the difference in boiling points.

[0004] The above-mentioned patents all show that for the mixture of monosilane, hydrogen, disilane and high silane produced by silane reaction, the commonly used method is to use the difference in boiling points of the components, to separate them by gas-liquid separation, rectification or distillation under pressure or cryogenic conditions. This method requires the use of compressors and cryogenic conditions, which consumes a lot of energy and requires a large investment in equipment. Especially for the separation of light components such as hydrogen and heavy components such as high silane, the content of light components is high, the condensation consumes a lot of energy, and the condensation effect is poor, so the energy consumption and equipment investment are also large. SUMMARY

[0005] The present application aims to provide a system and process for purifying impurity gases in a product of synthesis of disilane from silane, which consumes less energy and has low equipment investment.

[0006] The technical solution of the present application is as follows:

[0007] A system for purifying impurity gas in silane synthesis disilane product, comprising membrane separation device, fan, first rectifying column and second rectifying column connected in sequence;

[0008] The membrane separation device comprises first and second membrane separation devices connected in parallel; the fan comprises first and second fans connected in parallel; the first and second membrane separation devices are standby for each other and have the same equipment and operating conditions; the first and second fans are standby for each other and have the same equipment and operating conditions.

[0009] The membrane separation device comprises a membrane separation device gas outlet and a membrane separation device gas inlet, and the membrane separation device gas outlet is connected to the fan; the first rectifying column comprises a first rectifying column gas inlet, a first rectifying column top gas outlet and a first rectifying column bottom discharge outlet; the second rectifying column comprises a second rectifying column feed inlet, a second rectifying column top gas outlet and a second rectifying column bottom discharge outlet;

[0010] The first rectifying column bottom discharge outlet is connected to the second rectifying column feed inlet.

[0011] Further, a process for purifying impurity gas in silane synthesis disilane product, comprising the following steps:

[0012] Step S1: Silane synthesis disilane product gas passes through the membrane separation device, the operating pressure is normal pressure and the temperature is normal temperature; the light components obtained by membrane separation are treated as tail gas, and the remaining gas of the silane synthesis disilane product gas after removal of the light components is enriched on the other side of the membrane; the preferred temperature of normal temperature is 18-25℃, and the normal pressure refers to one standard atmosphere, and the temperature is 0℃ and the pressure is 101KPa.

[0013] Step S2: The remaining gas of the enriched silane synthesis disilane product gas after removal of the light components enters the first rectifying column through the fan;

[0014] Step S3: After rectification by the first rectifying column, the gas distilled out of the first rectifying column top gas outlet is recycled, and the column bottom material enters the second rectifying column feed inlet through the first rectifying column bottom discharge outlet;

[0015] Step S4: The column bottom material of the first rectifying column is combined into the second rectifying column, and after rectification and separation, the gas distilled out of the second rectifying column top gas outlet is recycled, and the column bottom material of the second rectifying column is treated.

[0016] Preferably, in step S1, the volume content of hydrogen in the silane synthesis disilane product gas is 70%-90%, the volume content of silane is 8%-25%, and the rest is disilane and trisilane.

[0017] Preferably, the material of the membrane in the membrane separation device in step S1 is hollow fiber membrane, microporous silica membrane or porous carbon molecular sieve membrane.

[0018] Preferably, the material of the membrane in step S1 is polysulfone PSF, polyimide PI, polycarbonate PC or cellulose acetate.

[0019] Preferably, the light components in step S1 include hydrogen; the remaining gas after removing the light components from the silane synthesis disilane product gas includes silane, disilane and trisilane.

[0020] Preferably, the operating pressure of the first rectifying column is 0.05-0.08 MPa; the operating pressure of the second rectifying column is 0.04-0.07 MPa; and the operating temperature of the first and second rectifying columns is 18-25℃.

[0021] Preferably, the first and second rectifying columns use structured packing or random packing.

[0022] Preferably, the distillation gas at the top outlet of the first rectifying column is silane gas, the distillation gas at the top outlet of the second rectifying column is disilane gas, and the material at the bottom of the second rectifying column is trisilane.

[0023] Preferably, the specific surface area of the structured packing is 250m 2 / m 3 The above is the wire mesh corrugated structured packing or hole plate corrugated structured packing; and the random packing is Ceta ring, Bauer ring or ladder ring.

[0024] The product gas contains a large amount of hydrogen and other light component impurities and a small amount of propylsilane impurities when silane is synthesized by using silane. For the product gas with such a composition, if distillation or rectification is used to separate the gas-liquid two phases by using the boiling point difference, a large amount of energy will be consumed. Because the content of the light component impurities in the product is high, the heat transfer effect of the product gas is poor, a large amount of cold energy or high pressure compression is required to liquefy, and this method also causes a high loss of the product gas ethylsilane. The product gas can be effectively separated by using the membrane separation technology according to the difference in molecular diameters. The hollow fiber membranes of polysulfone (PSF), polyimide (PI), polycarbonate (PC), cellulose acetate, microporous silica membranes and porous carbon molecular sieve membranes are used as the membrane separation materials. Different components have different permeation rates through the membrane under the driving of pressure; the components with high transfer rates are enriched on the permeation side, and the components with low transfer rates are enriched on the raw material side, so that the purpose of separating the mixed gas is achieved. The separation membrane used is a hydrogen permeation membrane type, the hydrogen molecule has the smallest kinetic diameter and the highest diffusion rate, and is easy to permeate through the membrane. The silane, ethylsilane and propylsilane and other large-diameter molecules are intercepted and enriched on the inlet side. Thus, the preliminary separation of silane, ethylsilane and propylsilane and the light components such as hydrogen in the product gas is completed, and the energy consumption of rectification can be greatly reduced.

[0025] The present application has the following beneficial effects:

[0026] 1. The present application preliminarily separates the high content of hydrogen and other light components from silane, ethylsilane and propylsilane in the product gas of silane synthesis by using the membrane separation method. Compared with the condensation gas-liquid separation method, the energy consumption of the purification process and the loss of ethylsilane product can be significantly reduced.

[0027] 2. The present application uses membrane separation combined with rectification purification process, and compared with other purification processes, the process is more simple, and the operation is more continuous and automatic.

[0028] 3. After the purification of the present application, the purity of ethylsilane is as high as 99.995% or above, the process is efficient and simple, and the energy consumption is low. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The process flow chart of the present application is shown in the figure.

[0030] In the figure, 1 is a first membrane separation device, 2 is a second membrane separation device, 3 is a first fan, 4 is a second fan, 5 is a first rectification column, and 6 is a second rectification column. DETAILED DESCRIPTION

[0031] The present application will be described in detail below with reference to the accompanying drawings and examples.

[0032] Device examples

[0033] Reference Figure 1 A system for purifying impurity gas in silane synthesis disilane product, comprising membrane separation device, fan, first rectifying column 5 and second rectifying column 6 connected in sequence; the membrane separation device comprises first membrane separation device 1 and second membrane separation device 2 connected in parallel; the fan comprises first fan 3 and second fan 4 connected in parallel; the membrane separation device comprises membrane separation device gas outlet and membrane separation device gas inlet, and the membrane separation device gas outlet is connected with the fan; the first rectifying column 5 comprises first rectifying column gas inlet, first rectifying column top gas outlet and first rectifying column bottom discharge port; the second rectifying column 6 comprises second rectifying column feed port, second rectifying column top gas outlet and second rectifying column bottom discharge port; the first rectifying column bottom discharge port is connected with the second rectifying column feed port.

[0034] Method embodiment

[0035] A process for purifying impurity gas in silane synthesis disilane product, using the system of device embodiment, comprising the following steps:

[0036] Step S1: The silane synthesis disilane product gas passes through the membrane separation device, the volume content of hydrogen in the silane synthesis disilane product gas is 70% to 90%, the volume content of silane is 8% to 25%, and the rest is disilane and trisilane; the operating pressure is normal pressure, and the temperature is normal temperature; the material of the membrane is polysulfone PSF, polyimide PI, polycarbonate PC or cellulose acetate; the hydrogen component obtained by membrane separation is treated as tail gas, and the remaining gas is enriched on the other side of the membrane;

[0037] Step S2: The enriched remaining gas enters the first rectifying column through the fan; the operating pressure of the first rectifying column 5 is 0.05 MPa to 0.08 MPa; the operating temperature of the first rectifying column 5 is 18 to 25°C.

[0038] Step S3: After rectification by the first rectifying column, the silane gas is distilled out of the first rectifying column top gas outlet and is recycled; the tower bottom material enters the second rectifying column feed port through the first rectifying column bottom discharge port; the operating pressure of the second rectifying column 6 is 0.04 MPa to 0.07 MPa; the operating temperature of the second rectifying column 6 is 18 to 25°C.

[0039] Step S4: The tower bottom material of the first rectifying column 5 is combined into the second rectifying column 6 and is separated by rectification; the disilane gas is distilled out of the second rectifying column top gas outlet; the trisilane material at the bottom of the second rectifying column 6 is recycled and treated.

[0040] Embodiment 1

[0041] Step 1: Silane synthesis disilane product gas, in which the hydrogen content is 70%, the silane content is 27%, and the balance is disilane and trisilane. The first membrane separation device 1 or the second membrane separation device 2 is used, the operating pressure is normal pressure, and the temperature is 18°C. The light components such as hydrogen pass through the membrane into the tail gas treatment system, and most of the silane, disilane, and trisilane in the silane synthesis disilane reaction gas are enriched on the other side of the membrane.

[0042] Step 2: The enriched most of the silane, disilane, and trisilane gas enters the first rectifying tower 5 through the first fan 3 or the second fan 4. The packing of the first rectifying tower 5 is a wire mesh wave regular packing with a specific surface area of 250 m 2 / m 3 ;

[0043] Step 3: The operating pressure of the first rectifying tower 5 is 0.08 MPa, and the operating temperature is 18°C. The silane gas is obtained through the rectifying separation tower top, enters the recovery system for recycling, and the tower bottom material enters the second rectifying tower 6. The packing of the second rectifying tower 6 is a Westinghouse ring;

[0044] Step 4: The tower bottom material of the first rectifying tower 5 is combined into the second rectifying tower 6, the operating pressure of the second rectifying tower 6 is 0.06 MPa, and the operating temperature is 18°C. The disilane gas is obtained through the rectifying separation tower top, the disilane recovery rate is 98%, the purity reaches 99.995%, and the tower bottom contains trisilane and other materials for recycling treatment.

[0045] Example 2

[0046] Step 1: Silane synthesis disilane product gas, in which the hydrogen content is 80%, the silane content is 18%, and the balance is disilane and trisilane. The first membrane separation device 1 or the second membrane separation device 2 is used, the operating pressure is normal pressure, and the temperature is normal temperature 25°C. The light components such as hydrogen pass through the membrane into the tail gas treatment system, and most of the silane, disilane, and trisilane in the silane synthesis disilane reaction gas are enriched on the other side of the membrane.

[0047] Step 2: The enriched most of the silane, disilane, and trisilane gas enters the first rectifying tower 5 through the first fan 3 or the second fan 4. The packing of the first rectifying tower 5 is a hole plate wave regular packing with a specific surface area of 250 m 2 / m 3 ;

[0048] Step 3: The operating pressure of the first rectifying tower 5 is 0.07 MPa, and the operating temperature is 25°C. The silane gas is obtained through the rectifying separation tower top, enters the recovery system for recycling, and the tower bottom material enters the second rectifying tower 6. The packing of the second rectifying tower 6 is a Paul ring;

[0049] Step 4: The bottom material of the first rectification tower 5 is combined into the second rectification tower 6, and the second rectification tower 6 is operated at a pressure of 0.05 MPa and a temperature of 20℃. The product disilane gas is obtained at the top of the rectification tower, and the disilane recovery rate is 96%, and the purity reaches 99.996%. The bottom material containing silane and the like is recovered and treated.

[0050] Example 3

[0051] Step 1: The silane synthesis disilane product gas contains 70% hydrogen, 16% silane, and the rest is disilane and trisilane. The first membrane separation device 1 or the second membrane separation device 2 is operated at a normal pressure and a temperature of 20℃. The light components such as hydrogen are separated into the tail gas treatment system through the membrane, and most of the silane, disilane and trisilane in the silane synthesis disilane reaction gas are enriched on the other side of the membrane.

[0052] Step 2: The enriched most of the silane, disilane and trisilane gas is introduced into the first rectification tower 5 through the first fan 3 or the second fan 4. The packing of the first rectification tower 5 is a wire mesh corrugated regular packing with a specific surface area of 280 m 2 / m 3 ;

[0053] Step 3: The first rectification tower 5 is operated at a pressure of 0.08 MPa and a temperature of 22℃, and the silane gas is obtained at the top of the rectification tower and introduced into the recovery system for recycling. The bottom material is introduced into the second rectification tower 6. The packing of the second rectification tower 6 is a stepped ring.

[0054] Step 4: The bottom material of the first rectification tower 5 is combined into the second rectification tower 6, and the second rectification tower 6 is operated at a pressure of 0.05 MPa and a temperature of 20℃. The product disilane gas is obtained at the top of the rectification tower, and the disilane recovery rate is 96%, and the purity reaches 99.996%. The bottom material containing silane and the like is recovered and treated.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that the membrane separation process is not used, and other process parameters are the same. The final disilane recovery rate is 81%, and the purity reaches 99.95%.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 1 is that the packing of the first rectification tower 5 is a Raschig ring random packing, and other process parameters are the same. The final disilane recovery rate is 91%, and the purity reaches 99.98%.

[0059] Comparative Example 3

[0060] The difference between the present comparative example and Example 1 is that the second rectifying column 6 uses a structured packing with a specific surface area of 125 m 2 / m 3 and other process parameters are the same, the final ethylsilane recovery is 85% and the purity reaches 99.97%.

[0061] The above description is merely preferred specific embodiments of the present application; the protection scope of the present application is not limited thereto; any skilled person in the art, within the technical scope disclosed by the present application, according to the technical solutions and improvement concepts of the present application, makes equivalent replacements or changes, which should be covered in the protection scope of the present application.

Claims

1. A system for purifying impurity gases in the product of silane synthesis of ethylsilane, characterized in that, It includes a membrane separation unit, a blower, a first distillation column (5), and a second distillation column (6) connected in sequence; The membrane separation device includes a first membrane separation device (1) and a second membrane separation device (2) connected in parallel; the blower includes a first blower (3) and a second blower (4) connected in parallel; The membrane separation device includes a membrane separation device outlet and a membrane separation device inlet, and the membrane separation device outlet is connected to a fan; the first distillation column (5) includes a first distillation column inlet, a first distillation column top outlet and a first distillation column bottom outlet; the second distillation column (6) includes a second distillation column inlet, a second distillation column top outlet and a second distillation column bottom outlet; The bottom outlet of the first distillation column is connected to the inlet of the second distillation column.

2. A process for purifying impurity gases in the silane synthesis of ethylsilane product, employing the system for purifying impurity gases in the silane synthesis of ethylsilane product as described in claim 1, characterized in that, Includes the following steps: Step S1: The gas from the silane synthesis of ethylsilane product passes through a membrane separation device at atmospheric pressure and room temperature. The light components obtained through membrane separation are treated as tail gas, and the remaining gas from the silane synthesis of ethylsilane product gas after removing the light components is enriched on the other side of the membrane. Step S2: The gas from the enriched silane to ethyl silane synthesis product, after removing light components, enters the first distillation column via a blower; Step S3: After distillation in the first distillation column (5), the gas distilled from the top outlet of the first distillation column is recycled, and the bottom material enters the feed inlet of the second distillation column through the bottom outlet of the first distillation column. Step S4: The bottom material of the first distillation column (5) is combined and enters the second distillation column (6). After distillation separation, gas is distilled out from the top outlet of the second distillation column, and the material at the bottom of the second distillation column (6) is recovered.

3. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 2, characterized in that, In step S1, the hydrogen volume content of the gas produced by the synthesis of silane from ethylsilane is 70% to 90%, the silane volume content is 8% to 25%, and the remainder is ethylsilane and propane.

4. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 2, characterized in that, The membrane material used in the membrane separation device described in step S1 is a hollow fiber membrane, a microporous silica membrane, or a porous carbon molecular sieve membrane.

5. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 4, characterized in that, The membrane used in step S1 is made of polysulfone (PSF), polyimide (PI), polycarbonate (PC), or cellulose acetate ester.

6. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 2, characterized in that, The light components mentioned in step S1 include hydrogen; the remaining gas after removing the light components from the silane synthesis product gas includes silane, silane, and propane.

7. The process for purifying impurity gases in the silane synthesis product of silane according to claim 2, characterized in that, The operating pressure of the first distillation column (5) is 0.05 MPa to 0.08 MPa; the operating pressure of the second distillation column (6) is 0.04 MPa to 0.07 MPa; and the operating temperature of the first distillation column (5) and the second distillation column (6) is 18 to 25 °C.

8. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 2, characterized in that, The first distillation column (5) and the second distillation column (6) use structured packing or random packing.

9. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 2, characterized in that, The gas distilled from the top outlet of the first distillation column is silane gas, the gas distilled from the top outlet of the second distillation column is ethyl silane gas, and the material at the bottom of the second distillation column (6) is propane silane.

10. The process for purifying impurity gases in the silane synthesis product of ethylsilane according to claim 8, characterized in that, The structured packing has a specific surface area of ​​250 m². 2 / m 3 The above-mentioned wire mesh corrugated structured packing or perforated plate corrugated structured packing; the random packing is a Sitta ring, Pall ring or stepped ring.

Images