Monosilane production system and method

Abstract

The invention relates to a monosilane production system and method.The production system comprises a reactive distillation device, an absorption device, a liquid conveying device and a crude silane refining device which are sequentially connected in the main material flow direction, the crude silane refining device is used for separating and purifying the high-pressure stream fed by the liquid conveying device and outputting an impurity stream, a high-purity monosilane product stream and a circulating stream, and the circulating stream is returned and fed into the reaction rectification device. Compared with the prior art, the method utilizes the liquid raw material to absorb the light component product, and has the advantages of low comprehensive energy consumption and equipment investment, stable operation and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of silane production, and relates to a silane production system and method. Background Art

[0002] High-purity silane can be used to manufacture polysilicon, monocrystalline silicon, microcrystalline silicon, silicon nitride, and various metal silicides, etc. It is also an important electronic special gas and is widely used in the microelectronics and optoelectronics industries. In recent years, with the rapid development of industries such as photovoltaic and display panels, the demand for silane has increased rapidly. Therefore, low-cost and high-efficiency silane production technologies have received attention.

[0003] There are dozens of methods for preparing silane. The methods with practical value and capable of industrialization mainly include the magnesium silicide method, the method of reducing trichlorosilane with lithium hydride, the method of reducing silicon tetrafluoride with sodium aluminum hydride, and the disproportionation method of trichlorosilane. Among them, the disproportionation method of trichlorosilane was first proposed by UCC Company. Using trichlorosilane as the raw material, silane and silicon tetrachloride are finally produced. It is the mainstream method for silane production at present.

[0004] UCC Company proposed in its early patent US4340574 to use chlorosilane as the raw material, and prepare high-purity silane through multiple steps of fixed-bed disproportionation reaction and rectification purification process. However, this method has a complex process and low production efficiency. Since then, patents for improving this technology have emerged continuously. For example, patent US6905576 simplified this process, and high-purity silane products can be obtained only by the combined operation of a reactive distillation column and a purification column. However, there are still problems such as low production efficiency and high energy consumption.

[0005] The reactive distillation technology utilizes the principle of "reacting while separating", which can break the thermodynamic equilibrium limitation in the process of producing silane by the disproportionation reaction of chlorosilane, and improve the raw material conversion rate and reaction efficiency. Since crude silane usually needs to be pressurized before entering the purification section, and the light components (mainly silane) of the disproportionation reaction products at the top of the reactive distillation column have a large relative volatility. When using a liquid transfer pump for pressurization, it is difficult for the overhead product to be completely condensed into a liquid phase, or there are bottlenecks such as extremely low condensation temperature and / or extremely low silane content when completely condensed into a liquid phase. When taken out in a gaseous form, an expensive gas compressor needs to be set up to achieve pressurization. Therefore, there are problems such as high operating costs and low reaction efficiency.

[0006] For example, Patent CN1774397B discloses a system and method for preparing silane. The system includes a first disproportionation reactive distillation column, a trichlorosilane hydrogenation system, a second disproportionation reactive distillation column, a crude silane distillation column, a first silane distillation column, and a second silane distillation column. The raw material chlorosilane for the disproportionation reaction enters the system from the first disproportionation reactive distillation column, and there are problems such as high operating costs and low reaction efficiency in the pressurization process of the overhead product of the disproportionation reactive distillation column. Patent CN105037409B discloses a method for preparing and purifying monosilane using reactive distillation. Using a liquid catalyst, the chlorosilane raw material enters from the first reactive distillation column, and disproportionation reactions and distillation occur in the first and second reactive distillation columns respectively. There is also a problem of high cost in the pressurization process of the intermediate disproportionation product and / or the final disproportionation product. Patent CN103241743B discloses a reactive distillation method and equipment for directly disproportionating trichlorosilane to prepare silane. The refined trichlorosilane with a purity of more than 9N is introduced into a one-step disproportionation reactive distillation column to prepare silane; the gaseous product at the top of the disproportionation reactive distillation column is taken out, and enters the silane purification column by using the pressure difference. Since the operating pressure of the disproportionation reactive distillation column is not high (0.2 - 0.5 Mpa), the operating pressure of the silane purification column is restricted. In order to achieve the purpose of silane purification, the operating temperature of the silane purification column must be extremely low (the top temperature is -90 to -60 °C), resulting in high operating costs. Patent CN106241813B discloses a system and method for producing high-purity silane from trichlorosilane. The non-condensable gas crude silane obtained by condensing the overhead product of the reaction tower through a multi-stage condenser is pressurized by a gas compressor and sent to the purification section, and there are problems such as large equipment investment and high operating costs of the gas compressor. Summary of the Invention

[0007] The purpose of the present invention is to provide a monosilane production system and method, which utilize the function of chlorosilane raw material as an absorbent to achieve complete condensation of the overhead product of the reactive distillation column into a liquid phase under the conditions of higher temperature and / or higher monosilane content, and use a liquid transfer pump to replace the gas compressor to pressurize the material and send it to the crude silane refining device, so as to achieve the purposes of low equipment investment and operating costs, high system reaction efficiency, and stable operation.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] In the first aspect, the present invention provides a monosilane production system, which includes a reactive distillation device, an absorption device, a liquid transfer device, and a crude silane refining device connected in sequence along the main material flow direction. Among them, a chlorosilane raw material feed port is provided on the absorption device. The crude silane refining device processes the high-pressure stream sent by the liquid transfer device, and outputs a light component impurity stream, a high-purity monosilane product stream, and a recycle stream. The recycle stream is also returned and sent into the reactive distillation device.

[0010] Further, at least 40% or more of the chlorosilane raw material enters the monosilane production system through the chlorosilane raw material inlet. Further still, 80% or more or all of the chlorosilane raw material enters the monosilane production system through the chlorosilane raw material inlet. More preferably, all of the chlorosilane raw material enters the system through the absorption device. It should be noted here that when only a part of the chlorosilane raw material enters the system through the absorption device, it means that the remaining part is directly sent to the reactive distillation column.

[0011] Further, at least one section of basic solid catalyst bed is provided in the middle of the reactive distillation column. The active substances of the basic solid catalyst are organic amines, inorganic bases, inorganic salts, etc. It should be noted here that the specific composition of the basic solid catalyst bed, etc. are catalytically active components commonly used in the art for the disproportionation reaction to produce monosilane, which is not the creative protection point of the present invention and will not be elaborated here.

[0012] Further, the absorption device is a bubble absorption tower, a packed absorption tower, a spray absorption tower or a bubble absorption tank.

[0013] Further, the liquid conveying device is in the form of a diaphragm pump, a canned motor pump, a centrifugal pump, a gear pump, a screw pump, etc.

[0014] Further, the crude silane refining device includes one set of distillation columns or two sets of distillation columns. Preferably, the crude silane refining device includes a crude silane preliminary separation column and a product column. Among them, the crude silane preliminary separation column is a light component removal column or a heavy component removal column, and the product column is used to purify the material preliminarily separated by the crude silane preliminary separation column and generate the high-purity monosilane product stream and the recycle stream.

[0015] In a second aspect, the present invention provides a method for producing monosilane, which is based on the monosilane production system described in the first aspect above. The method includes the following steps:

[0016] S1. Chlorosilane absorption:

[0017] The chlorosilane raw material is sent to the absorption device and mixed with the light component product containing monosilane from the reactive distillation column. After the combined liquid single-phase stream is pressurized by the liquid conveying device, a high-pressure stream containing monosilane is obtained and sent to the crude silane refining device;

[0018] S2. Monosilane purification:

[0019] The high-pressure stream containing monosilane is separated and purified in the crude silane refining device to obtain light component impurities. The high-purity monosilane product is sent out of the system boundary, and the heavy component material is returned to the reactive distillation column as a recycle stream;

[0020] S3. The circulating stream from the crude silane refining unit undergoes a disproportionation reaction under the action of a catalyst in the reactive distillation unit. The obtained light component product is sent into the absorption unit, and the obtained heavy component product is sent out of the system boundary.

[0021] Further, the content of impurities with a relative volatility greater than that of trichlorosilane in the chlorosilane raw material is less than 100 ppm, preferably less than 1 ppm, and more preferably less than 1 ppb. It should be noted here that the chlorosilane raw material refers to the chlorosilane for preparing silane, specifically dichlorosilane or trichlorosilane.

[0022] Further, the temperature of the light component product is below 40°C, preferably below 20°C, more preferably below 0°C, still more preferably below -20°C, and even more preferably below -40°C.

[0023] Further, the temperature of the chlorosilane raw material is not higher than the temperature of the light component product, preferably 5°C or more lower than the temperature of the light component product, more preferably more than 10°C lower than the temperature of the light component product, and even more preferably more than 20°C lower than the temperature of the light component product. It should be noted here that based on the basic principles of chemical engineering thermodynamics, low temperature is beneficial to improving the absorption efficiency of gaseous materials in the light component product.

[0024] Further, the operating pressure of the reactive distillation unit is 0.01 - 1.5 MpaG, preferably 0.2 - 1.0 MPaG, and more preferably 0.3 - 0.6 MPaG.

[0025] Further, the operating pressure of the crude silane refining unit is 1.0 - 4.0 MPaG, preferably 1.3 - 3.0 MPaG, and more preferably 1.5 - 2.0 MPaG.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) Part or all of the chlorosilane raw material for the disproportionation reaction to produce silane enters the silane production system via the absorption unit. Utilizing the role of the chlorosilane raw material as an absorbent, the gaseous materials in the light component product of the disproportionation reaction are absorbed to obtain a liquid single-phase stream, which is convenient for boosting pressure using a liquid conveying device, and can effectively solve the problem in the prior art that it is difficult to condense silane into a liquid state due to its large relative volatility in the product.

[0028] (2) Under the same conditions, the present invention can achieve complete condensation of the material withdrawn from the top of the reactive distillation column into a liquid phase under higher temperature and / or higher silane content conditions, so as to facilitate replacing the gas compressor with a liquid conveying pump to boost the pressure of the material, achieving the purposes of low equipment investment and operating cost, high system reaction efficiency, and stable operation. Description of the Drawings

[0029] Figure 1 System block diagram for preparing silane in the present invention;

[0030] Figure 2 Simplified schematic diagram of the system for preparing silane in Example 1;

[0031] Figure 3 Simplified diagram of the system for preparing silane in Example 2;

[0032] Figure 4 Simplified diagram of the system for preparing silane in Example 3;

[0033] Figure 5 Simplified diagram of the system for preparing silane in Comparative Example 1;

[0034] Figure 6 Simplified diagram of the system for preparing silane in Comparative Example 2;

[0035] Description of the markings in the figure:

[0036] 100 - Reactive distillation unit; 101 - Light - component product; 102 - Heavy - component product; 200 - Absorption unit; 201 - Chlorosilane raw material; 202 - Liquid single - phase stream; 300 - Liquid delivery device; 301 - High - pressure stream; 400 - Crude silane refining unit; 410 - Initial fractionation tower for crude silane; 420 - Product tower; 411 - Light - component impurities; 412 - Crude silane after light - component removal; 413 - Crude silane after heavy - component removal; 421 - High - purity silane product; 422 - Recirculation stream; 423 - Heavy - component impurities; 500 - Diaphragm gas compressor; 600 - Cryogenic cooler. Detailed implementation manners

[0037] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation procedures are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0038] In the following implementation manners, unless otherwise specified for functional components or structures, it means that they are all conventional components or conventional structures adopted in the art to achieve the corresponding functions.

[0039] To reduce equipment investment and operating costs, and improve the reaction efficiency and operating stability of the system, etc., the present invention provides a silane production system. Please refer to Figure 1As shown in the figure, it includes a reactive distillation device 100, an absorption device 200, a liquid delivery device 300 and a crude silane refining device 400 connected in sequence along the main material flow direction. Among them, a feed port 201 for chlorosilane raw material is provided on the absorption device 200. The crude silane refining device 400 processes the high-pressure stream sent through the liquid delivery device 300, and outputs a light component impurity stream, a high-purity silane product 421 stream and a recycle stream. The recycle stream is also returned and fed into the reactive distillation device 100.

[0040] In some specific embodiments, at least 40% or more of the chlorosilane raw material 201 enters the silane production system through the feed port 201 for chlorosilane raw material. Further, 80% or more or all of the chlorosilane raw material 201 enters the silane production system through the feed port 201 for chlorosilane raw material. More preferably, all of the chlorosilane raw material 201 enters the system through the absorption device 200. It should be noted here that when only a part of the chlorosilane raw material 201 enters the system through the absorption device 200, it means that the remaining part is directly fed into the reactive distillation device 100.

[0041] In some specific embodiments, at least one section of an alkaline solid catalyst bed layer is provided in the middle of the reactive distillation device 100. The active substances of the alkaline solid catalyst are organic amines, inorganic bases, inorganic salts, etc. It should be noted here that the specific composition of the alkaline solid catalyst bed layer and the like are catalytically active components commonly used in the art for the disproportionation reaction to produce silane, which is not the inventive point of the present invention and will not be elaborated here.

[0042] In some specific embodiments, the absorption device 200 is a bubble-type absorption tower, a packed absorption tower, a spray-type absorption tower or a bubble absorption tank.

[0043] In some specific embodiments, the liquid delivery device 300 is in the form of a diaphragm pump, a canned motor pump, a centrifugal pump, a gear pump, a screw pump, etc.

[0044] In some specific embodiments, the crude silane refining device 400 includes one set of distillation columns or two sets of distillation columns. Preferably, it includes a crude silane preliminary separation column 410 and a product column 420. Among them, the crude silane preliminary separation column 410 is used to perform light component removal on the high-pressure stream and output the light component impurity stream at the top of the column. The product column 420 is used to further purify the light component-removed crude silane stream sent from the bottom of the crude silane preliminary separation column 410 and output the high-purity silane product 421 stream at the top of the column, and output the recycle stream at the bottom of the column.

[0045] In addition, based on the above silane production system, the present invention also provides a silane production method, which includes the following steps:

[0046] S1. Chlorosilane absorption:

[0047] The chlorosilane raw material 201 is fed into the absorption device 200 and mixed with the light component product containing silane from the reactive distillation device 100. After the combined liquid single-phase stream is pressurized by the liquid conveying device 300, a high-pressure stream containing silane is obtained and fed into the crude silane refining device 400;

[0048] S2. Silane purification:

[0049] The high-pressure stream containing silane is separated and purified in the crude silane refining device 400. The light component impurities and the high-purity silane product 421 are sent out of the system boundary, and the heavy component material is returned to the reactive distillation device 100 as a recycle stream;

[0050] S3. The recycle stream from the crude silane refining device 400 undergoes a disproportionation reaction under the action of a catalyst in the reactive distillation device 100. The obtained light component product is fed into the absorption device 200, and the obtained heavy component product is sent out of the system boundary.

[0051] In some specific embodiments, the content of impurities with a relative volatility greater than trichlorosilane in the chlorosilane raw material 201 is less than 100 ppm, preferably less than 1 ppm, and more preferably less than 1 ppb.

[0052] In some specific embodiments, the temperature of the light component product is below 40°C, preferably below 20°C, more preferably below 0°C, even more preferably below -20°C, and still more preferably below -40°C.

[0053] In some specific embodiments, the temperature of the chlorosilane raw material 201 is not higher than the temperature of the light component product, preferably 5°C or more lower than the temperature of the light component product, more preferably more than 10°C lower than the temperature of the light component product, and even more preferably more than 20°C lower than the temperature of the light component product.

[0054] In some specific embodiments, the operating pressure of the reactive distillation device 100 is 0.01 - 1.5 MpaG, preferably 0.2 - 1.0 MPaG, and more preferably 0.3 - 0.6 MPaG.

[0055] In some specific embodiments, the operating pressure of the crude silane refining device 400 is 1.0 - 4.0 MPaG, preferably 1.3 - 3.0 MPaG, and more preferably 1.5 - 2.0 MPaG.

[0056] Each of the above embodiments can be implemented alone, or any two or more of them can be combined arbitrarily.

[0057] The above embodiments will be described in more detail below in conjunction with specific embodiments.

[0058] Example 1:

[0059] This example provides a system and method for preparing silane. As Figure 2 shown, in addition to the reactive distillation unit 100, the absorption unit 200, and the liquid delivery unit 300, the crude silane refining unit 400 includes two towers, namely the crude silane preliminary separation tower 410 and the product tower 420. All of the chlorosilane raw material 201 enters the production system via the absorption unit 200 and is mixed with the light component product 101 from the reactive distillation unit 100 within the absorption unit 200. The formed liquid single-phase stream 202 is pressurized by the liquid delivery unit 300, and the obtained high-pressure stream 301 is sent to the crude silane preliminary separation tower 410. This tower is a light component removal tower, and the light component impurities 411 obtained at the top of the tower are sent outside the system boundary. The crude silane 412 after light component removal is sent to the product tower 420 under the action of pressure difference. The high-purity silane product 421 is obtained at the top of the tower, and the bottom heavy components are sent to the reactive distillation unit 100 via the recycle stream 422 under the action of pressure difference to carry out a disproportionation reaction under the action of a catalyst to generate silane and other by-products. The light component product 101 containing silane is sent to the absorption unit 200 under the action of pressure difference, and the heavy component product 102 is sent outside the system boundary.

[0060] In this example, the reactive distillation unit 100 includes a section of solid basic catalyst bed, with a section of structured packing above the bed as the rectifying section and a section of structured packing below the bed as the stripping section. The absorption unit 200 is a bubble absorption tank. The liquid delivery pump 300 is a canned motor pump. Both the crude silane preliminary separation tower 410 and the product tower 420 are two-section structured packing type distillation towers, and the feed positions are both between the two sections of packing.

[0061] A certain chemical plant uses high-purity trichlorosilane as the raw material to prepare silane and by-product silicon tetrachloride, applying the above silane production system. The purity of the trichlorosilane raw material is 99.05%, and the content of impurities with a relative volatility greater than monochlorosilane is below 10 ppb. The active component of the solid basic catalyst used is dimethylamine ion exchange resin. The obtained light component impurities 411 are sent outside the system boundary in the form of non-condensable gas, the obtained high-purity silane product 421 is sent outside the system boundary in a liquid state, and the obtained heavy component product 102 is sent outside the system boundary in a liquid state under the action of pressure difference.

[0062] Applying the above system to prepare silane includes the following steps:

[0063] (1) Chlorosilane absorption: The chlorosilane raw material 201 is mixed with the light component product 101 containing silane from the reactive distillation unit 100 in the absorption unit 200 and absorbs the gaseous components contained therein. The combined liquid single-phase stream 202 is pressurized by the liquid transfer device 300 and then sent to the crude silane refining unit 400;

[0064] (2) Silane purification: The high-pressure stream 301 containing silane successively enters the crude silane preliminary separation column 410 and the product column 420 included in the crude silane refining unit 400. The light component impurities 411 obtained at the top of the crude silane preliminary separation column 410 are sent out of the system boundary in the form of non-condensable gas. The high-purity silane product 421 obtained at the top of the product column 420 is sent out of the system boundary in a liquid state. The heavy component material obtained at the bottom of the column is returned to the reactive distillation unit 100 through the recycle stream 422;

[0065] (3) Chlorosilane disproportionation reaction: The recycle stream 422 from the bottom of the product column 420 undergoes a disproportionation reaction in the reactive distillation unit 100 under the action of an alkaline solid catalyst. The obtained heavy component product 102 is sent out of the system boundary, and the obtained light component product 101 is sent to the absorption unit 200.

[0066] In this embodiment, the operating pressure of the reactive distillation unit 100 is 0.3 MPaG, the operating pressure of the crude silane preliminary separation column 410 is 1.9 MPaG, and the operating pressure of the product column 420 is 1.82 MPaG. The temperature of the light component product 101 obtained after the top gas phase of the reactive distillation unit 100 is cooled and condensed in multiple stages is -20 °C, and the molar fraction of silane is 22.87%. The temperature of the trichlorosilane raw material is -25 °C. The specific results are as follows:

[0067]

[0068] Example 2

[0069] This embodiment provides a system and method for preparing silane. As Figure 3As shown, in addition to the reactive distillation unit 100, the absorption unit 200, and the liquid transfer unit 300, the crude silane refining unit 400 includes two towers, namely a crude silane preliminary separation tower 410 and a product tower 420. All of the chlorosilane raw material 201 enters the production system via the absorption unit 200 and is mixed with the light component product 101 from the reactive distillation unit 100 within the absorption unit 200. The formed liquid single-phase stream 202 is pressurized by the liquid transfer unit 300, and the obtained high-pressure stream 301 is sent to the crude silane preliminary separation tower 410. This tower is a heavy component removal tower, and the heavy components obtained at the bottom of the tower are sent to the reactive distillation unit 100 under the action of pressure difference through the recycle stream 422. The crude silane 413 after heavy component removal is sent to the product tower 420 under the action of pressure difference. The light component impurities 411 obtained at the top of the tower are sent outside the system, the high-purity silane product 421 is taken out from the middle of the product tower 420, and the heavy component impurities 423 are taken out from the bottom of the tower and sent to the reactive distillation unit 100 under the action of pressure difference. The chlorosilane from the recycle stream 422 undergoes a disproportionation reaction within the reactive distillation unit 100 under the action of a catalyst to generate silane and other by-products. The light component product 101 containing silane is sent to the absorption unit 200 under the action of pressure difference, and the heavy component product 102 is sent outside the system.

[0070] In this embodiment, the reactive distillation unit 100 includes a section of solid basic catalyst bed, and there is a section of structured packing below the bed as the stripping section. The absorption unit 200 is a spray absorption tower. The liquid transfer pump 300 is a screw pump. Both the crude silane preliminary separation tower 410 and the product tower 420 are two-section structured packing type distillation towers. The former has the feed position between the two sections of packing, and the latter has the feed position at the bottom of the tower.

[0071] A certain chemical plant uses high-purity trichlorosilane as the raw material to prepare silane and by-product silicon tetrachloride, using the above silane production system. The purity of the trichlorosilane raw material is 98.12%, and the content of impurities with a relative volatility greater than that of monochlorosilane is below 5 ppb. The active component of the solid basic catalyst used is supported potassium carbonate. The light component impurities 411 obtained at the top of the product tower 420 are sent outside the system in the form of non-condensable gas, the high-purity silane product 421 obtained in the middle of the tower is sent outside the system in a liquid state, and the heavy component product 102 obtained at the bottom of the reactive distillation unit 100 is sent outside the system in a liquid state under the action of pressure difference.

[0072] Using the above system to prepare silane includes the following steps:

[0073] (1) Chlorosilane absorption: The trichlorosilane raw material (i.e., the chlorosilane raw material 201) is mixed with the light component product 101 containing silane from the reactive distillation unit 100 and absorbs the gaseous components contained therein through the absorption unit 200. The combined liquid single-phase stream 202 is pressurized by the liquid transfer unit 300 and then sent into the crude silane refining unit 400;

[0074] (2) Purification of silane: The high-pressure stream 301 containing silane successively enters the rough silane initial separation column 410 and the product column 420 included in the rough silane refining device 400. The heavy component material obtained at the bottom of the rough silane initial separation column 410 is returned to the reactive distillation device 100 through the recycle stream 422. The rough silane 413 after deweighting is sent to the product column 420 under the action of pressure difference. The light component impurities 411 obtained at the top of the column are sent outside the system boundary. The high-purity silane product 421 is withdrawn from the middle of the product column 420, and the heavy component impurities 423 are withdrawn from the bottom of the column and sent to the reactive distillation device 100 under the action of pressure difference;

[0075] (3) Disproportionation reaction of chlorosilane: The recycle stream 422 from the bottom of the rough silane initial separation column 410 and the heavy component impurities 423 from the bottom of the product column 420 undergo a disproportionation reaction in the reactive distillation device 100 under the action of an alkaline solid catalyst. The obtained heavy component product 102 is sent outside the system boundary, and the obtained light component product 101 is sent to the absorption device 200.

[0076] In this embodiment, the operating pressure of the reactive distillation device 100 is 0.4 MPaG, the operating pressure of the rough silane initial separation column 410 is 1.75 MPaG, and the operating pressure of the product column 420 is 1.70 MPaG. The temperature of the component product 101 obtained after the top gas phase of the reactive distillation device 100 is cooled and condensed in multiple stages is -40 °C, and the molar fraction of silane is 30.06%. The temperature of the trichlorosilane raw material is -40 °C.

[0077] The specific results are as follows:

[0078]

[0079]

[0080] Example 3

[0081] This embodiment provides a system and method for preparing silane. As Figure 4As shown, in addition to the reactive distillation unit 100, the absorption unit 200, and the liquid transfer unit 300, the crude silane refining unit 400 includes two towers, namely, the crude silane preliminary separation tower 410 and the product tower 420. A part of the chlorosilane raw material 201 directly enters the reactive distillation unit 100, and the rest enters the production system via the absorption unit 200 and is mixed with the light component product 101 from the reactive distillation unit 100 in the absorption unit 200. The formed liquid single-phase stream 202 is pressurized by the liquid transfer unit 300, and the obtained high-pressure stream 301 is sent to the crude silane preliminary separation tower 410. This tower is a light component removal tower. The light component impurities 411 obtained at the top of the tower are sent outside the system boundary. The crude silane 412 after light component removal is sent to the product tower 420 under the action of pressure difference. The high-purity silane product 421 is taken out from the top of the product tower 420. The heavy components obtained at the bottom of the tower are sent to the reactive distillation unit 100 under the action of pressure difference through the recycle stream 422. The chlorosilane from the recycle stream 422 undergoes a disproportionation reaction in the reactive distillation unit 100 under the action of a catalyst to generate silane and other by-products. The light component product 101 containing silane is sent to the absorption unit 200 under the action of pressure difference, and the heavy component product 102 is sent outside the system boundary.

[0082] In this embodiment, the reactive distillation unit 100 includes two sections of solid basic catalyst beds, and there is a section of structured packing below the beds as the stripping section. The absorption unit 200 is a packed absorption tower. The liquid transfer pump 300 is a diaphragm pump. Both the crude silane preliminary separation tower 410 and the product tower 420 are two-section structured packing distillation towers. The former has the feed position at the top of the tower, and the latter has the feed position at the bottom of the tower.

[0083] A certain chemical plant uses high-purity dichlorosilane as a raw material to prepare silane and by-produce trichlorosilane, and applies a system for preparing silane as shown in Figure 2 The purity of the dichlorosilane raw material is 96.50%, and the content of impurities with a relative volatility greater than monochlorosilane is below 1 ppb. 10% of the dichlorosilane raw material feed directly enters the reactive distillation unit 100, and the remaining 90% enters the production system via the absorption unit 200. The active component of the solid basic catalyst used is dimethylamine ion exchange resin. The light component impurities 411 obtained at the top of the crude silane preliminary separation tower 410 are sent outside the system boundary in the form of non-condensable gas. The high-purity silane product 421 obtained at the top of the product tower 420 is sent outside the system boundary in the form of gas. The heavy component product 102 obtained at the bottom of the reactive distillation unit 100 is sent outside the system boundary in the liquid form under the action of pressure difference.

[0084] Applying the above system to prepare silane includes the following steps:

[0085] (1) Chlorosilane absorption: 90% of the dichlorosilane raw material (i.e., the chlorosilane raw material 201) is absorbed by the absorption device 200 and mixed with the light component product 101 containing silane from the reactive distillation device 100 to absorb the gaseous components contained therein. The combined liquid single-phase stream 202 is pressurized by the liquid transfer device 300 and then sent to the crude silane refining device 400;

[0086] (2) Silane purification: The high-pressure stream 301 containing silane successively enters the crude silane preliminary separation tower 410 and the product tower 420 included in the crude silane refining device 400. The light component impurities 411 obtained at the top of the crude silane preliminary separation tower 410 are sent out of the system boundary in the form of non-condensable gas. The high-purity silane product 421 obtained at the top of the product tower 420 is sent out of the system boundary in the gaseous form. The heavy component material obtained at the bottom is returned to the reactive distillation device 100 through the recycle stream 422;

[0087] (3) Chlorosilane disproportionation reaction: 10% of the dichlorosilane raw material 201 and the recycle stream 422 from the bottom of the product tower 420 undergo a disproportionation reaction in the reactive distillation device 100 under the action of a basic solid catalyst. The obtained heavy component product 102 is sent out of the system boundary, and the obtained light component product 101 is sent to the absorption device 200.

[0088] In this embodiment, the operating pressure of the reactive distillation device 100 is 0.6 MPaG, the operating pressure of the crude silane preliminary separation tower 410 is 2.0 MPaG, and the operating pressure of the product tower 420 is 1.95 MPaG. The temperature of the component product 101 obtained after the top gas phase of the reactive distillation device 100 is cooled and condensed in multiple stages is -30 °C, and the molar fraction of silane is 31.62%. The temperature of the dichlorosilane raw material 201 is -50 °C. The specific results are as follows:

[0089]

[0090] Comparative Example 1

[0091] Compared with the embodiment, most of them are the same, except that the absorption device 200 is cancelled and the trichlorosilane raw material 201 is directly connected to the reactive distillation 100, as Figure 5 shown. The comparison results between Comparative Example 1 and Example 1 are as follows:

[0092]

[0093]

[0094] As can be seen from the table, in this comparative example, since the absorption device 200 was not provided, the chlorosilane feed 201 was directly sent to the reactive distillation device 100. Under the condition of keeping the temperature of the light component product 101 unchanged, in order to keep it in a pure liquid phase for pressurization using the liquid transfer device 300, the content of monosilane in the light component product 101 had to be reduced from 22.87% to 10.38%, resulting in a decrease in the reaction efficiency of the process, an increase in the material circulation amount between the reactive distillation device 100 and the crude silane refining device 400, and finally an increase in the comprehensive energy consumption from 1.05 t standard oil / t monosilane to 1.47 t standard oil / t monosilane.

[0095] Comparative Example 2

[0096] Compared with Example 3, most of them are the same, except that the absorption device 200 was cancelled, the trichlorosilane raw material 201 was directly connected to the reactive distillation device 100, the liquid transfer device 300 was changed to a diaphragm gas compressor 500, and a cryogenic cooler 600 was set at its outlet, as Figure 5 shown. The light component product 101 was taken out from the top of the reactive distillation device 100 in the form of non-condensable gas, pressurized by the diaphragm gas compressor 500 and cooled by the cryogenic cooler 600, and then sent to the crude silane preliminary separation column 410.

[0097] The comparison results between Comparative Example 2 and Example 3 are as follows:

[0098]

[0099] As can be seen from the table, in this comparative example, since the absorption device 200 was not provided, all of the chlorosilane feed 201 was sent to the reactive distillation device 100 and taken out in a gaseous form under the condition of keeping the temperature of the light component product 101 unchanged. On the one hand, it was necessary to use an expensive diaphragm gas compressor 500 to replace the liquid transfer device 300 for pressurization, which would lead to an increase in equipment investment and be much higher than that in Example 3. On the other hand, since the temperature would rise significantly after gas compression, a cryogenic cooler 600 had to be added before entering the crude silane preliminary separation column 410 for temperature reduction, which not only increased the equipment investment but also increased the refrigerant consumption and resulted in a higher total comprehensive energy consumption than that in Example 3. The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A monosilane production system, characterized in that: It comprises a reaction distillation device, an absorption device, a liquid conveying device and a crude silane refining device which are sequentially connected along the main material flow direction, wherein the absorption device is provided with a chlorosilane raw material feed port, the crude silane refining device separates and purifies the high-pressure stream fed in through the liquid conveying device, and outputs an impurity stream, a high-purity monosilane product stream and a circulating stream, and the circulating stream is also returned to the reaction distillation device.

2. A monosilane production system according to claim 1, characterized in that: At least 40% of the chlorosilane raw material enters the monosilane production system through the chlorosilane raw material feed port.

3. A monosilane production system according to claim 2, characterized in that: More than 80% or all of the chlorosilane raw materials enter the monosilane production system through the chlorosilane raw material feed port.

4. A monosilane production system according to claim 1, characterized in that: At least one alkaline solid catalyst bed is arranged in the middle of the reaction and distillation device, and the active substance of the alkaline solid catalyst is organic amine, inorganic base or inorganic salt.

5. A monosilane production system according to claim 1, characterized in that: The absorption device is a bubbling absorption tower, a packed absorption tower, a spray absorption tower or a bubbling absorption tank.

6. A monosilane production system according to claim 1, characterized in that: The liquid conveying device is a diaphragm pump, a shielded pump, a centrifugal pump, a gear pump, or a screw pump.

7. A monosilane production system according to claim 1, characterized in that: The crude silane refining device comprises a crude silane primary separation tower and a product tower, wherein the crude silane primary separation tower is a light removal tower or a heavy removal tower, and the product tower is used to purify the material preliminarily separated by the crude silane primary separation tower and produce the high-purity monosilane product stream and the circulating stream.

8. A method for producing monosilane, based on the monosilane production system according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1, Chlorosilane absorption: The chlorosilane raw material is sent to the absorption device and mixed with the light component product containing monosilane from the reactive distillation device. The combined liquid single-phase stream is pressurized by the liquid conveying device to obtain a high-pressure stream containing monosilane and sent to the crude silane refining device; S2, Silane purification: The high-pressure stream containing monosilane is separated and purified in the crude silane refining device to obtain light component impurities and high-purity monosilane products that are sent to the outside of the system, and the heavy component materials are returned to the reactive distillation device as a circulating stream; S3. The circulating stream from the crude silane refining device undergoes a disproportionation reaction under the action of a catalyst in the reactive distillation device, and the obtained light component product is sent to the absorption device, and the obtained heavy component product is sent to the outside of the system.

9. A method for producing monosilane according to claim 8, characterized in that: The content of impurities with a relative volatility greater than that of monochlorosilane in the chlorosilane raw material is less than 100 ppm.

10. A method for producing monosilane according to claim 8, characterized in that: The temperature of the light component product is below 40°C; The temperature of the chlorosilane raw material is not higher than the temperature of the light component product; The operating pressure of the reactive distillation device is 0.01-1.5MpaG.

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