Preparation process of silane

Abstract

The invention provides a preparation process of silane, which comprises the following steps: carrying out primary disproportionation reaction on trichlorosilane under the action of a liquid catalyst, and simultaneously carrying out rectification separation to obtain dichlorosilane; dichlorosilane obtained through the first-stage disproportionation reaction is subjected to a second-stage disproportionation reaction under the action of a solid catalyst, and meanwhile, rectification separation is performed to obtain silane; wherein the liquid catalyst is fatty amine liquid with 12 or more carbon atoms and a tertiary amine group; the solid catalyst is ion exchange resin containing tertiary amine or quaternary amine; the problem that the solid catalyst is easy to inactivate due to high temperature in the disproportionation reaction of trichlorosilane is solved, the preparation process of the silane can be simplified, and the yield of the silane is increased.

Description

Technical Field

[0001] This invention relates to the field of silane preparation technology, and more particularly to a silane preparation process. Background Technology

[0002] Silane (SiH4) is an important silicon source material, widely used in industries such as semiconductor microelectronics ICs, photovoltaic solar cells (PV), and liquid crystal displays (LCDs).

[0003] There are three main processes for preparing silanes: 1) Sodium aluminum fluoride method: This method uses sodium aluminum hydride and silicon tetrafluoride as raw materials to synthesize silane gas. After subsequent adsorption, distillation, separation, and purification, high-purity electronic-grade silane gas with a purity of 6N or higher is obtained. Some domestic companies have introduced production lines for this process, but their operation is far from ideal. 2) Silicon-magnesium alloy method: Also known as the Komatsu method, this method uses industrial silicon powder, metallic magnesium, and ammonium chloride as raw materials. Silane is obtained through a two-step reaction, but the cost is high, and there are currently no large-scale production lines. 3) Chlorosilane disproportionation method: This method mainly uses trichlorosilane as raw material. Through multiple disproportionation reactions, silane and silicon tetrachloride are finally produced. Silicon tetrachloride can be returned to the hydrogenation process to form a closed loop, resulting in low emissions, environmental benefits, high material utilization, and no byproducts. The chlorosilane disproportionation method has become the mainstream process for preparing silanes.

[0004] Existing chlorosilane disproportionation methods generally use ion exchange resins as solid catalysts. However, these solid catalysts have poor temperature resistance, and their optimal reaction temperature for maintaining long-term activity does not exceed 60°C. When these solid catalysts are used in reactive distillation columns, their operating temperature is determined by the column pressure and composition, while the temperature of the cooling medium at the top of the column determines the column pressure. This results in a contradiction between low reflux energy consumption and high-temperature catalyst deactivation in the operation of reactive distillation columns. In other words, under current process conditions, the solid catalyst exhibits significant degradation during use, causing silane production to fall short of the design yield. Summary of the Invention

[0005] The purpose of this invention is to provide a silane preparation process to solve the technical problem that the fixed catalyst attenuation in the existing silane preparation process leads to the inability to achieve the designed yield of silane.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a silane preparation process, comprising the following steps:

[0007] Trichlorosilane was subjected to a first-stage disproportionation reaction in the presence of a liquid catalyst, and dichlorosilane was obtained by distillation.

[0008] The dichlorodihydrosilane obtained from the first-stage disproportionation reaction is subjected to a second-stage disproportionation reaction in the presence of a solid catalyst, while simultaneously being separated by distillation to obtain silane.

[0009] The liquid catalyst is an aliphatic amine liquid with 12 or more carbon atoms having a tertiary amine group; the solid catalyst is an ion exchange resin containing a tertiary amine or a quaternary amine.

[0010] As a further improvement of the present invention, the amount of liquid catalyst is 1 wt.% to 20 wt.% of the total weight of the trichlorosilane and the liquid catalyst.

[0011] As a further improved technical solution of the present invention, "carrying trichlorosilane under the action of a liquid catalyst in a first-stage disproportionation reaction, and simultaneously separating it by distillation to obtain dichlorosilane" specifically includes the following steps:

[0012] The trichlorosilane and liquid catalyst are fed into a pre-reactor for mixing and heated to a preset temperature to obtain a mixture.

[0013] The mixture is fed into the first reactive distillation column for further primary disproportionation reaction, while simultaneously undergoing distillation separation, with dichlorosilane collected from the top of the column.

[0014] As a further improved technical solution of the present invention, the pressure of the first reactive distillation column is atmospheric pressure to 5 barg; the top temperature of the first reactive distillation column is 5℃ to 75℃; the bottom temperature of the first reactive distillation column is 57℃ to 128℃; the reflux rate of the first reactive distillation column is 50t / h to 120t / h; and the feed rate of the first reactive distillation column is 20t / h.

[0015] As a further improvement of the present invention, the preset temperature is 20℃~120℃.

[0016] As a further improvement of the present invention, trichlorosilane is subjected to a first-stage disproportionation reaction under the action of a liquid catalyst, and distilled to obtain dichlorosilane while simultaneously yielding a mixture of silicon tetrachloride and the liquid catalyst; the preparation process further includes the following steps:

[0017] The mixture of silicon tetrachloride and liquid catalyst is separated, and the separated liquid catalyst is recycled back to the primary disproportionation reaction unit. The separated silicon tetrachloride enters the silicon tetrachloride hydrogenation system to undergo a hydrogenation reaction, generating trichlorosilane, which then enters the primary disproportionation reaction unit for further reaction.

[0018] As a further improved technical solution of the present invention, "separating the mixture of silicon tetrachloride and liquid catalyst" specifically means: sending the mixture of silicon tetrachloride and liquid catalyst into a flash tank or a kettle heat exchanger to obtain separated liquid catalyst and silicon tetrachloride.

[0019] As a further improved technical solution of the present invention, dichlorodihydrosilane undergoes a two-stage disproportionation reaction under the action of a solid catalyst, and is separated by distillation to obtain silane while unreacted dichlorodihydrosilane and trichlorosilane are also obtained. The preparation process further includes the following steps:

[0020] The unreacted dichlorosilane and trichlorosilane are fed into the primary disproportionation reaction site to continue the reaction.

[0021] As a further improved technical solution of the present invention, "the dichlorodihydrosilane obtained from the primary disproportionation reaction is subjected to a secondary disproportionation reaction under the action of a solid catalyst, and simultaneously separated by distillation to obtain silane" specifically means:

[0022] The dichlorodihydrosilane obtained from the first-stage disproportionation reaction is fed into the second reactive distillation column, where the dichlorodihydrosilane undergoes a second-stage disproportionation reaction under the action of a solid catalyst, and is simultaneously separated by distillation to obtain silane.

[0023] The pressure of the second reactive distillation column is 5 barg to 20 barg; the top temperature of the second reactive distillation column is -50℃ to 4℃; the bottom temperature of the second reactive distillation column is 143℃ to 217℃; the reflux ratio of the second reactive distillation column is 5 to 50; and the feed rate of the second reactive distillation column is 7t / h to 10t / h.

[0024] As a further improvement of the present invention, the dichlorodihydrosilane obtained by the first-stage disproportionation reaction is condensed into a liquid state and then subjected to a second-stage disproportionation reaction.

[0025] The beneficial effects of this invention are as follows: In the silane preparation process of this invention, a liquid catalyst with good high-temperature resistance is used to carry out the disproportionation reaction of trichlorosilane to generate dichlorosilane, while a solid catalyst is used to carry out the disproportionation reaction of dichlorosilane to generate silane. On the one hand, this solves the problem that solid catalysts are prone to deactivation at high temperatures in the disproportionation reaction of trichlorosilane, thereby improving catalytic efficiency and thus increasing the yield of silane. At the same time, it can appropriately increase the pressure of the distillation column where the liquid catalyst is located and reduce the required cooling temperature at the top of the distillation column. On the other hand, the solid catalyst does not need to be separated from other components, which simplifies the silane preparation process. In addition, using a solid catalyst in the disproportionation reaction of dichlorosilane can also avoid the influence of the liquid catalyst containing silicon tetrachloride on the conversion efficiency of the dichlorosilane disproportionation reaction, thereby further improving the yield of silane. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preparation system in a specific embodiment of the silane preparation process of the present invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. Please refer to the accompanying drawings for further details. Figure 1 The figures shown represent preferred embodiments of the present invention. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent modifications or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0028] The terms used to describe position and direction in this invention, such as "top" and "bottom," are all based on the silane preparation system in use. Furthermore, the terms "connection" can refer to a direct connection or an indirect connection through another structure; "direct connection" means there are no other structures between them. Additionally, the accompanying drawings in this invention are all in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the various embodiments of this invention.

[0029] This invention provides a process for preparing silanes, the process comprising the following steps:

[0030] Trichlorosilane was subjected to a first-stage disproportionation reaction in the presence of a liquid catalyst, and dichlorosilane was obtained by distillation.

[0031] The dichlorodihydrosilane obtained from the first-stage disproportionation reaction is subjected to a second-stage disproportionation reaction in the presence of a solid catalyst, while simultaneously being separated by distillation to obtain silane.

[0032] The liquid catalyst is an aliphatic amine liquid with 12 or more carbon atoms having a tertiary amine group; the solid catalyst is an ion exchange resin containing a tertiary amine or a quaternary amine.

[0033] It is known that trichlorosilane has a high boiling point and a high disproportionation reaction temperature, generally around 120℃. Dichlorosilane has a low boiling point and a low disproportionation reaction temperature, generally around 20℃ to 80℃. The optimal reaction temperature for solid catalysts is also low, generally not exceeding 60℃. Therefore, in the silane preparation process of this invention, a liquid catalyst with good high-temperature resistance is used to carry out the disproportionation reaction of trichlorosilane to generate dichlorosilane, while a solid catalyst is used to carry out the disproportionation reaction of dichlorosilane to generate silane. On the one hand, this solves the problem that solid catalysts are prone to deactivation at high temperatures in the disproportionation reaction of trichlorosilane, thereby improving catalytic efficiency and thus increasing the yield of silane. At the same time, it can appropriately increase the pressure of the distillation column where the liquid catalyst is located and reduce the cooling temperature required for the reflux at the top of the distillation column. On the other hand, when using a solid catalyst, the solid catalyst does not need to be separated from other components, which simplifies the silane preparation process. In addition, using a solid catalyst in the disproportionation reaction of dichlorosilane can also avoid the influence of the liquid catalyst containing silicon tetrachloride on the conversion efficiency of the disproportionation reaction of dichlorosilane, thereby further improving the yield of silane.

[0034] Trichlorosilane undergoes a first-stage disproportionation reaction in the presence of a liquid catalyst to produce dichlorosilane and silicon tetrachloride. In this catalytic reaction system, both the liquid catalyst and silicon tetrachloride are heavy components. During reactive distillation, the gas-liquid phase equilibrium causes the liquid catalyst to tend to mix with silicon tetrachloride, forming a mixture of silicon tetrachloride and liquid catalyst. Subsequent separation of silicon tetrachloride from the liquid catalyst is necessary for recycling the liquid catalyst. However, the strong interaction between silicon tetrachloride and the liquid catalyst makes it difficult to obtain a high-purity liquid catalyst; that is, the separated liquid catalyst will contain a small amount of silicon tetrachloride. If a liquid catalyst is also used in the disproportionation reaction of dichlorosilane, the separated liquid catalyst containing a small amount of silicon tetrachloride will participate in the disproportionation reaction of dichlorosilane, affecting the conversion efficiency of dichlorosilane to silane, and may even reverse disproportionate dichlorosilane to trichlorosilane, thus affecting the yield of silane.

[0035] Specifically, the liquid catalyst may be selected from at least one of tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-decylamine, and tri-n-dodecylamine. The solid catalyst may be selected from amino-based strong base anion exchange resins or amino-based weak base anion exchange resins, such as D66, A21, A100, and D301R, but is not limited thereto.

[0036] In some optional embodiments, the amount of liquid catalyst is 1 wt.% to 20 wt.% of the total weight of the trichlorosilane and the liquid catalyst.

[0037] In one specific embodiment, the amount of liquid catalyst used is 5 wt.% of the total weight of the trichlorosilane and the liquid catalyst, which can balance the catalytic effect and cost of the liquid catalyst.

[0038] Furthermore, the step "carrying trichlorosilane under the action of a liquid catalyst for a first-stage disproportionation reaction, while simultaneously performing distillation to obtain dichlorosilane" specifically includes the following steps:

[0039] The trichlorosilane and liquid catalyst are fed into a pre-reactor for mixing and heated to a preset temperature to obtain a mixture.

[0040] The mixture is fed into the first reactive distillation column for further primary disproportionation reaction, while simultaneously undergoing distillation separation, with dichlorosilane collected from the top of the column.

[0041] In this invention, trichlorosilane and the liquid catalyst are first mixed and heated in a pre-reactor before being fed into the first reactive distillation column, i.e., a preliminary first-stage disproportionation reaction is carried out to complete the equilibrium process of the first disproportionation reaction. Then, the resulting mixture is fed into the first reactive distillation column to continue the first-stage disproportionation reaction. This can improve the conversion rate of trichlorosilane to dichlorosilane, reduce the number of subsequent refluxes in the first reactive distillation column, reduce the reflux ratio of the first reactive distillation column, and reduce the energy consumption of the preparation process.

[0042] Specifically, the preset temperature is 20℃~120℃. The pressure of the first reactive distillation column is atmospheric pressure~5 barg; the top temperature of the first reactive distillation column is 5℃~75℃; the bottom temperature of the first reactive distillation column is 57℃~128℃; the reflux flow rate of the first reactive distillation column is 50t / h~120t / h; and the feed rate of the first reactive distillation column is 20t / h.

[0043] After the mixture is fed into the first reactive distillation column for further primary disproportionation reaction, the gas-liquid phase equilibrium during the reactive distillation process results in the generated dichlorosilane at the top of the column, while the mixture of silicon tetrachloride and liquid catalyst is located at the bottom of the column.

[0044] It should be noted that the dichlorosilane at the top of the tower may contain a small amount of unreacted trichlorosilane. Of course, this is not a limitation.

[0045] The internal structure of the first reactive distillation column can follow the existing structure of the disproportionation distillation column, and will not be described in detail here.

[0046] Further, trichlorosilane undergoes a first-stage disproportionation reaction under the action of a liquid catalyst, followed by distillation to obtain a mixture of dichlorosilane, silicon tetrachloride, and the liquid catalyst. The preparation process also includes the following steps:

[0047] The mixture of silicon tetrachloride and liquid catalyst is separated, and the separated liquid catalyst is recycled back to the primary disproportionation reaction unit. The separated silicon tetrachloride enters the silicon tetrachloride hydrogenation system to undergo a hydrogenation reaction, generating trichlorosilane, which then enters the primary disproportionation reaction unit for further reaction.

[0048] This enables closed-loop recycling of liquid catalysts with zero pollution emissions and environmental friendliness.

[0049] Specifically, the separated liquid catalyst is returned to the pre-reactor. The trichlorosilane produced from the hydrogenation reaction of the separated silicon tetrachloride is also returned to the pre-reactor.

[0050] In one specific embodiment, the separation of silicon tetrachloride and liquid catalyst is achieved by feeding the mixture of silicon tetrachloride and liquid catalyst into a single-stage flash tank or a multi-stage flash tank. Specifically, the mixture of silicon tetrachloride and liquid catalyst is passed through a single-stage flash tank or sequentially through multiple flash tanks to obtain separated silicon tetrachloride and liquid catalyst. However, this is not a limitation. In other embodiments, the mixture of silicon tetrachloride and liquid catalyst can also be separated by feeding it into a vessel heat exchanger. In this case, 6-8 barg of steam can be used as a heat source in the vessel heat exchanger, and the temperature inside the vessel heat exchanger can be controlled to be no lower than 120°C to facilitate the separation of the liquid catalyst and silicon tetrachloride. Furthermore, depending on the specific type of liquid catalyst, a demister or packing material can be added at the steam outlet of the vessel heat exchanger to further remove the liquid catalyst from the silicon tetrachloride, preventing the liquid catalyst from being entrained in the silicon tetrachloride hydrogenation system.

[0051] Furthermore, the dichlorosilane obtained from the primary disproportionation reaction is condensed into a liquid state and then subjected to a secondary disproportionation reaction. Thus, the liquid dichlorosilane can be directly pumped into the second reactive distillation column, facilitating the transport of the dichlorosilane.

[0052] Furthermore, the specific steps of "substituting dichlorodihydrosilane obtained from the primary disproportionation reaction into a secondary disproportionation reaction under the action of a solid catalyst, and simultaneously separating it by distillation to obtain silane" are as follows:

[0053] The dichlorodihydrosilane obtained from the first-stage disproportionation reaction is fed into the second reactive distillation column, where the dichlorodihydrosilane undergoes a second-stage disproportionation reaction under the action of a solid catalyst, and is simultaneously separated by distillation to obtain silane.

[0054] Specifically, the pressure of the second reactive distillation column is 5 barg to 20 barg; the top temperature of the second reactive distillation column is -50℃ to 4℃; the bottom temperature of the second reactive distillation column is 143℃ to 217℃; the reflux ratio of the second reactive distillation column is 5 to 50; and the feed rate of the second reactive distillation column is 7t / h to 10t / h.

[0055] The reflux ratio of the second reactive distillation column mentioned above refers to the ratio of the reflux flow rate to the outflow rate of the second reactive distillation column.

[0056] The internal structure of the second reactive distillation column can follow the existing internal structure of the disproportionation reactive distillation column, and will not be described in detail here.

[0057] Dichlorodihydrosilane undergoes a secondary disproportionation reaction under the action of a solid catalyst in the second reactive distillation column. During the reactive distillation process, the gas-liquid phase equilibrium results in the formation of light components such as silane and a small amount of monochlorotrihydrosilane at the top of the second reactive distillation column, while the unreacted dichlorodihydrosilane and trichlorosilane, as heavy components, are located at the bottom of the second reactive distillation column.

[0058] Furthermore, after dichlorosilane undergoes a secondary disproportionation reaction in the presence of a solid catalyst, the preparation process further includes the following steps:

[0059] The unreacted dichlorosilane and trichlorosilane are fed into the primary disproportionation reaction site to continue the reaction.

[0060] Specifically, feeding the unreacted dichlorosilane and trichlorosilane into the pre-reactor can improve the conversion rate of the trichlorosilane, thereby increasing the yield of silane.

[0061] Correspondingly, combined Figure 1 The diagram illustrates a preparation system 10 in a specific embodiment of the silane preparation process described in this invention. The preparation system 10 includes at least a pre-reactor 1, a first reactive distillation column 2, and a second reactive distillation column 3. The pre-reactor 1 is connected to the first reactive distillation column 2, and the first reactive distillation column 2 is connected to the second reactive distillation column 3. The pre-reactor 1 is used to mix trichlorosilane and the aforementioned liquid catalyst to form a mixture, i.e., to undergo a preliminary first-stage disproportionation reaction, completing the equilibrium process of the first disproportionation reaction to improve the conversion rate of trichlorosilane in the preparation system 10. After the pre-reactor 1 is heated to a preset temperature, the mixture enters the first reactive distillation column 2 to continue the first-stage disproportionation reaction. The dichlorosilane generated from the first-stage disproportionation reaction enters the second reactive distillation column 3, where it undergoes a second-stage disproportionation reaction under the action of a solid catalyst to generate silane.

[0062] The preparation system 10 of this invention, by separately setting up a first reactive distillation column 2 for the disproportionation reaction of trichlorosilane with a liquid catalyst and a second reactive distillation column 3 for the disproportionation reaction of dichlorosilane with a solid catalyst, solves the problem of high temperature and easy deactivation of solid catalysts in the disproportionation reaction of trichlorosilane, thereby improving catalytic efficiency and thus increasing silane yield. At the same time, it can appropriately increase the column pressure of the first reactive distillation column 2 and reduce the cooling temperature required for the reflux at the top of the first reactive distillation column 2. On the other hand, when using a solid catalyst, the solid catalyst does not need to be separated from other components, which simplifies the preparation process of silane. In addition, using a solid catalyst in the disproportionation reaction of dichlorosilane can also avoid the influence of liquid catalysts containing silicon tetrachloride on the conversion efficiency of the disproportionation reaction of dichlorosilane, thereby further improving the yield of silane.

[0063] Specifically, the pre-reactor 1 includes a pre-reaction inlet 11 and a pre-reaction outlet 12, and the pre-reactor 1 has a mixing component and a heating component. After the trichlorosilane and liquid catalyst enter the pre-reactor 1 through the pre-reaction inlet 11, the trichlorosilane and liquid catalyst are first thoroughly mixed by the mixing component, and then heated to a preset temperature by the heating component before being discharged from the pre-reaction outlet 12. The preset temperature is 20℃~120℃.

[0064] The first reactive distillation column 2 includes a first inlet 21 and a dichlorosilane outlet 22. The first inlet 21 is connected to the pre-reaction outlet 12 so that the mixture in the pre-reactor 1 enters the first reactive distillation column 2 for a primary disproportionation reaction. The dichlorosilane outlet 22 is connected to the second reactive distillation column 3 so that the dichlorosilane enters the second reactive distillation column 3 for a secondary disproportionation reaction to generate silane.

[0065] Furthermore, the first reactive distillation column 2 has a reaction layer 23 for trichlorosilane to undergo a primary disproportionation reaction under the action of a liquid catalyst, a chlorosilane fractionation section located below the reaction layer 23, and a dichlorosilane distillation section located above the reaction layer 23.

[0066] Specifically, the first reactive distillation column 2 is equipped with a first condenser 24 at its top. After condensation at the top of the column, a portion of the dichlorosilane doped with a small amount of trichlorosilane is refluxed back into the first reactive distillation column 2, while the other portion enters the second reactive distillation column 3 for a secondary disproportionation reaction. The reboiler of the first reactive distillation column 2 is equipped with a first reboiler 25, which can be heated by steam, hot water, a heat transfer medium, or electricity to maintain the reboiler temperature between 57°C and 128°C.

[0067] Specifically, the dichlorosilane outlet 22 is connected to the inlet of the first condenser 24.

[0068] Furthermore, the bottom of the first reactive distillation column 2 has a first outlet 26, through which the mixture of heavy component silicon tetrachloride and liquid catalyst is discharged from the first reactive distillation column 2.

[0069] Furthermore, the preparation system 10 also includes a separator 4 connected to the first outlet 26, through which the mixture of silicon tetrachloride and liquid catalyst is separated.

[0070] The separator 4 has a silicon tetrachloride outlet 41 and a catalyst outlet 42. The catalyst outlet 42 is connected to the inlet of the pre-reactor 1. The separated liquid catalyst is discharged into the pre-reactor 1 for recycling through the catalyst outlet 42. The separated silicon tetrachloride is discharged through the silicon tetrachloride outlet 41.

[0071] In one specific embodiment, the separator 4 is a single-stage flash tank or a multi-stage flash tank. Of course, this is not a limitation; in other embodiments, the separator 4 may also be a kettle heat exchanger.

[0072] Furthermore, the preparation system 10 also includes a silicon tetrachloride hydrogenation system 5 connected to the silicon tetrachloride outlet 41, and the outlet of the silicon tetrachloride hydrogenation system 5 is connected to the pre-reactor 1. Silicon tetrachloride discharged from the silicon tetrachloride outlet 41 enters the silicon tetrachloride hydrogenation system 5 and undergoes a hydrogenation reaction to generate trichlorosilane. The generated trichlorosilane is returned to the pre-reactor 1 to continue the reaction. Thus, a closed-loop recycling of the liquid catalyst is achieved, with no pollution emissions and environmental friendliness.

[0073] Specifically, the second reactive distillation column 3 has a second inlet 31, a silane outlet 32, and a second outlet 33 connected to the outlet of the first condenser 24. The second outlet 33 is connected to the pre-reaction inlet 11 of the pre-reactor 1. The dichlorosilane generated in the first reactive distillation column 2 is condensed by the first condenser 24 and then enters the second reactive distillation column 3 through the second inlet 31 for a secondary disproportionation reaction. The generated silane is discharged from the second reactive distillation column 3 through the silane outlet 32, and the unreacted dichlorosilane and trichlorosilane are returned to the pre-reactor 1 through the second outlet 33 to continue the reaction.

[0074] Specifically, the second reactive distillation column 3 is provided with a solid catalyst layer 34 and a chlorosilane fractionation section located below the solid catalyst layer 34.

[0075] Specifically, the second reactive distillation column 3 is equipped with a second condenser 35 at the top. The generated silane is condensed by the second condenser 35 at the top of the column, and part of it is refluxed back into the second reactive distillation column 3, while the other part is discharged for subsequent separation and purification processes. The bottom of the second reactive distillation column 3 is equipped with a second reboiler 36, which can be heated by steam, hot water, a heat transfer medium, or electricity.

[0076] Specifically, the silane outlet 32 ​​is connected to the inlet of the second condenser 35, so that the generated silane can enter the second condenser 35, be condensed first, and then partially refluxed back to the second reactive distillation column 3, while the rest is discharged for subsequent silane separation and purification processes.

[0077] The silane separation, purification, and supply processes described above in this invention can be achieved using existing crude silane purification equipment and processes, which will not be elaborated upon here.

[0078] The specific preparation process for preparing silane using the preparation system 10 of the present invention is as follows:

[0079] The liquid catalyst and the trichlorosilane produced by the silicon tetrachloride hydrogenation system 5 or the raw material trichlorosilane are introduced into the pre-reactor 1 and thoroughly mixed. Then, the temperature of the pre-reactor 1 is controlled to rise to 20°C.

[0080] A mixture was obtained at ~120℃;

[0081] After the pre-reactor 1 is heated to 20℃~120℃, the mixture is fed into the first reactive distillation column 2 to continue the first-stage disproportionation reaction and is then distilled to obtain a mixture of dichlorosilane (possibly containing a small amount of trichlorosilane), silicon tetrachloride and liquid catalyst. The pressure of the first reactive distillation column 2 is atmospheric pressure~5 barg, the top temperature is 5℃~75℃, the bottom temperature is 57℃~128℃, the reflux flow rate is 50~120 t / h, and the feed rate is 20 t / h.

[0082] The dichlorosilane obtained from distillation is cooled by the first condenser 24 at the top of the first reactive distillation column 2. Part of it is refluxed back into the first reactive distillation column 2, while the rest enters the second reactive distillation column 3 for a secondary disproportionation reaction to produce silane (which may contain a small amount of monochlorotrihydrosilane). The pressure of the second reactive distillation column 3 is 5 barg to 20 barg, the top temperature is -50℃ to 4℃, the bottom temperature is 143℃ to 217℃, the reflux ratio is 5 to 50, and the feed rate is 7t / h to 10t / h. At the same time, the mixture of silicon tetrachloride and liquid catalyst enters the separator 4 to form phase-separated silicon tetrachloride and liquid catalyst.

[0083] After the primary silane is obtained by cooling it in the second condenser 35 at the top of the second reactive distillation column 3, part of it is refluxed back into the second reactive distillation column 3 according to the set reflux ratio, and the other part enters the subsequent silane purification process.

[0084] The separated liquid catalyst is discharged into the pre-reactor 1 for recycling, while the separated silicon tetrachloride enters the silicon tetrachloride hydrogenation system 5 to undergo a hydrogenation reaction to generate trichlorosilane. The generated trichlorosilane is then returned to the pre-reactor 1 for further reaction. Thus, a closed-loop recycling of the liquid catalyst is achieved, with no pollution emissions and environmental friendliness.

[0085] Compared with existing technologies, the silane preparation process of this invention uses a liquid catalyst with good high-temperature resistance to carry out the disproportionation reaction of trichlorosilane to generate dichlorosilane, while using a solid catalyst to carry out the disproportionation reaction of dichlorosilane to generate silane. On the one hand, this solves the problem of the solid catalyst being easily deactivated at high temperatures in the disproportionation reaction of trichlorosilane, thereby improving catalytic efficiency and thus increasing the yield of silane. At the same time, it can appropriately increase the pressure of the distillation column where the liquid catalyst is located and reduce the required cooling temperature at the top of the distillation column. On the other hand, when using a solid catalyst, the solid catalyst does not need to be separated from other components, which simplifies the silane preparation process. In addition, using a solid catalyst in the disproportionation reaction of dichlorosilane can also avoid the influence of the liquid catalyst containing silicon tetrachloride on the conversion efficiency of the disproportionation reaction of dichlorosilane, thereby further improving the yield of silane.

[0086] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0087] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the preparation of silanes, characterized in that: The preparation process comprises the following steps: The trichlorosilane is subjected to a primary disproportionation reaction under the action of a liquid catalyst, and is subjected to rectification separation to obtain dichlorodisilane; The dichlorodisilane obtained by the primary disproportionation reaction is subjected to a secondary disproportionation reaction under the action of a solid catalyst, and is subjected to rectification separation to obtain silane; The liquid catalyst is a fatty amine liquid with a tertiary amine group and 12 or more carbon atoms; and the solid catalyst is an ion exchange resin containing a tertiary amine or a quaternary amine.

2. The process for preparing silane as claimed in claim 1, wherein: The amount of the liquid catalyst is 1 wt.% to 20 wt.% of the total weight of the trichlorosilane and the liquid catalyst.

3. The process for preparing silane as claimed in claim 1, wherein: The trichlorosilane is subjected to a primary disproportionation reaction under the action of a liquid catalyst, and is subjected to rectification separation to obtain dichlorodisilane; specifically comprising the following steps: The trichlorosilane and the liquid catalyst are fed into a pre-reactor for mixing and heating to a preset temperature to obtain a mixed liquid; The mixed liquid is fed into a first reaction rectification tower for continuing the primary disproportionation reaction and rectification separation, and dichlorodisilane is collected at the top of the tower.

4. The process for preparing silane as claimed in claim 3, wherein: The pressure of the first reaction rectification tower is normal pressure to 5 barg; the top temperature of the first reaction rectification tower is 5℃ to 75℃; the bottom temperature of the first reaction rectification tower is 57℃ to 128℃; the reflux amount of the first reaction rectification tower is 50 t / h to 120 t / h; and the feed rate of the first reaction rectification tower is 20 t / h.

5. The process for preparing silane as claimed in claim 3, wherein: The preset temperature is 20℃ to 120℃.

6. The process for preparing silane as claimed in claim 1, wherein: The trichlorosilane is subjected to a primary disproportionation reaction under the action of a liquid catalyst, and is subjected to rectification separation to obtain dichlorodisilane; the preparation process further comprises the following steps: The trichlorosilane and the liquid catalyst are fed into a pre-reactor for mixing and heating to a preset temperature to obtain a mixed liquid; 7. The process for preparing silane as claimed in claim 6, wherein: The mixed liquid is fed into a first reaction rectification tower for continuing the primary disproportionation reaction and rectification separation, and dichlorodisilane is collected at the top of the tower.

8. The process for preparing silane as claimed in claim 1, wherein: The pressure of the first reaction rectification tower is normal pressure to 5 barg; the top temperature of the first reaction rectification tower is 5℃ to 75℃; the bottom temperature of the first reaction rectification tower is 57℃ to 128℃; the reflux amount of the first reaction rectification tower is 50 t / h to 120 t / h; and the feed rate of the first reaction rectification tower is 20 t / h. The preset temperature is 20℃ to 120℃.

9. The process for preparing silane as claimed in claim 1, wherein: The trichlorosilane is subjected to a primary disproportionation reaction under the action of a liquid catalyst, and is subjected to rectification separation to obtain dichlorodisilane; the preparation process further comprises the following steps: The trichlorosilane and the liquid catalyst are fed into a pre-reactor for mixing and heating to a preset temperature to obtain a mixed liquid; The mixed liquid is fed into a first reaction rectification tower for continuing the primary disproportionation reaction and rectification separation, and dichlorodisilane is collected at the top of the tower. The pressure of the first reaction rectification tower is normal pressure to 5 barg; the top temperature of the first reaction rectification tower is 5℃ to 75℃; the bottom temperature of the first reaction rectification tower is 57℃ to 128℃; the reflux amount of the first reaction rectification tower is 50 t / h to 120 t / h; and the feed rate of the first reaction rectification tower is 20 t / h. The preset temperature is 20℃ to 120℃. The trichlorosilane is subjected to a primary disproportionation reaction under the action of a liquid catalyst, and is subjected to rectification separation to obtain dichlorodisilane; the preparation process further comprises the following steps: The trichlorosilane and the liquid catalyst are fed into a pre-reactor for mixing and heating to a preset temperature to obtain a mixed liquid; The mixed liquid is fed into a first reaction rectification tower for continuing the primary disproportionation reaction and rectification separation, and dichlorodisilane is collected at the top of the tower. The pressure of the first reaction rectification tower is normal pressure to 5 barg; the top temperature of the first reaction rectification tower is 5℃ to 75℃; the bottom temperature of the first reaction rectification tower is 57℃ to 128℃; the reflux amount of the first reaction rectification tower is 50 t / h to 120 t / h; and the feed rate of the first reaction rectification tower is 20 t / h. The preset temperature is 20℃ to 120℃. The pressure of the second reaction rectifying tower is 5barg-20barg; the top temperature of the second reaction rectifying tower is -50℃-4℃; the bottom temperature of the second reaction rectifying tower is 143℃-217℃; the reflux ratio of the second reaction rectifying tower is 5-50; and the feeding rate of the second reaction rectifying tower is 7t / h-10t / h.

10. The process for preparing silane as claimed in claim 1, wherein: The dichlorodihydrogen silicon obtained by the first-stage disproportionation reaction is condensed into liquid state and then subjected to the second-stage disproportionation reaction.

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