Device and process for preparing electronic-grade silane

Abstract

The invention provides a preparation device and process of electronic-grade silane. According to the preparation device, a first disproportionation reaction is carried out on the basis of the first reactor, dichlorosilane is rectified and separated to serve as a raw material for a second disproportionation reaction, silane can be obtained on the basis of cheap trichlorosilane and a catalytic reagent, and electronic-grade silane can be obtained on the basis of traditional purification after rectification; based on heat exchange between tower top materials of the rectifying tower I and a tower kettle reboiler of the rectifying tower II, differential pressure thermal coupling integration is realized, condensing equipment and operation steps can be omitted, energy consumption is reduced, and the defects of high preparation cost and high energy consumption of a silane preparation device in the prior art are overcome.

Description

Technical Field

[0001] The invention relates to the technical field of silane preparation, in particular to a device and process for preparing electronic grade silane. Background Art

[0002] With the rapid development of semiconductor ultra-large-scale integrated circuits, OLED display devices, and solar photovoltaics, the demand for ultra-high purity silane used in the manufacturing processes in the above fields is increasing. In semiconductor manufacturing, electronic grade silane is an important precursor gas used in chemical vapor deposition processes to grow various thin films on substrates such as silicon wafers. For example, it can be used to deposit thin films such as polycrystalline silicon, amorphous silicon, and silicon nitride. These films play different roles in semiconductor devices, such as insulation, conduction, and passivation; in flat panel display technology, thin film transistors are one of the key components. Electronic grade silane can be used to manufacture semiconductor layers in TFTs through chemical vapor deposition or physical vapor deposition processes; electronic grade silane can also be used to produce polycrystalline silicon and single crystal silicon materials for solar cells. Through chemical vapor deposition or other processes, high-quality silicon crystals can be grown on silicon wafers to improve the conversion efficiency of solar cells.

[0003] There are many methods for preparing electronic-grade silane, mainly including the silicon-magnesium alloy method: using silicon powder, magnesium powder and liquid ammonia as raw materials, reacting under certain conditions to produce silane. This method has a simple process flow, but the cost is relatively high. Silicon tetrafluoride method: Silicon tetrafluoride gas is reacted with metal hydride to produce silane. This method can utilize the company's by-product fluorosilicic acid to reduce costs, but it requires the consumption of a large amount of metal hydride. Chlorosilane disproportionation method: Silane is prepared by the disproportionation reaction of chlorosilane. This method has a simple process flow and is one of the main methods for producing silane in industry, but it still has the defect of high energy consumption.

[0004] Therefore, it is necessary to propose a new device for preparing electronic-grade silane to solve the problem of high cost or energy consumption in the preparation process in the prior art. Summary of the invention

[0005] The present invention provides a device and process for preparing electronic-grade silane, which solves the problem of high cost or energy consumption in the preparation process in the prior art.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A device for preparing electronic grade silane comprises a reactor 1, a distillation tower 1, a distillation tower 2, a reactor 2 and a post-purification unit which are connected in sequence; wherein:

[0008] Reactor 1 is used for disproportionation reaction of trichlorosilane to generate dichlorosilane and silicon tetrachloride; distillation tower 1 is used for separating dichlorosilane and feeding it to distillation tower 2; distillation tower 2 is used for purifying dichlorosilane and feeding it to reactor 2; reactor 2 is used for disproportionation reaction of dichlorosilane to generate silane and silicon trichloride; post-purification unit is used for separating and purifying silane to obtain electronic grade silane;

[0009] The bottom of the second distillation tower is connected to a second reboiler for reboiling the bottom material; the top of the first distillation tower is provided with a first reflux pipe, which is connected to the top of the first distillation tower via the heat exchange medium layer of the second reboiler.

[0010] Furthermore, the reflux pipe 1 is located at the output end of the reboiler 2 and is connected to the feed end of the distillation tower 2.

[0011] Furthermore, a reflux pipe 2 is provided on the top of the second distillation tower and is connected to the second reactor, and the output end of the second reactor is connected to the feed end of the post-purification unit.

[0012] Furthermore, the reactor 1 and / or the reactor 2 is filled with weakly basic anion exchange resin.

[0013] Furthermore, the post-purification unit includes a distillation tower three, a distillation tower four, and a distillation tower five which are connected in sequence; the discharge end of the reactor two is connected to the feed end of the distillation tower three, and the top of the distillation tower three is provided with a reflux pipe three, and the reflux pipe three is connected to the feed end of the distillation tower four; the bottom of the distillation tower four is provided with a production pipeline connected to the feed end of the distillation tower five; the top of the distillation tower five is used to produce electronic grade silane.

[0014] Preferably, the post-purification unit also includes a compressor, a compressed air pipe is provided at the compressor outlet, and a condensation return water main pipe is provided at the inlet; the tower bottoms of the distillation tower three, distillation tower four, and distillation tower five are respectively provided with reboiler three, reboiler four, and reboiler five for reboiling circulation of the tower bottom materials, and the tower tops are respectively provided with condenser two, condenser three, and condenser four for condensation and reflux of the materials; the compressed air pipe passes through the heating medium layer of reboiler three, reboiler four, and reboiler five and is collected to the condensation main pipe, and the condensation main pipe passes through the condensation medium layer of condenser two, condenser three, and condenser four and is collected to the condensation return water main pipe.

[0015] Preferably, the return water ends of the reboiler three, the reboiler four and the reboiler five are respectively connected to the storage tank four, and the lower part of the storage tank four is connected to the condensation main pipe.

[0016] Preferably, the third tower kettle of the distillation tower is provided with a circulation pipe 2 which is connected to the feed port of the second distillation tower.

[0017] Furthermore, the second reactor of the distillation tower is provided with a circulation pipe 1 connected to the reactor 1.

[0018] Another object of the present invention is to provide a process for preparing electronic grade silane, comprising the steps of:

[0019] S1. Trichlorosilane undergoes a disproportionation reaction under the action of a catalyst to obtain dichlorosilane and silicon tetrachloride;

[0020] S2. The product obtained in step S1 is subjected to a first distillation to remove silicon tetrachloride, and a second distillation to remove trichlorosilane to obtain dichlorosilane;

[0021] S3. Dichlorosilane undergoes a disproportionation reaction under the action of catalyst 2 to produce silane and trichlorosilane;

[0022] S4. The product obtained in step S3 is subjected to the third, fourth and fifth distillations in sequence to obtain electronic grade silane; the third distillation is used to preliminarily remove trichlorosilane and dichlorosilane; the fourth distillation is used to remove light component impurities; and the fifth distillation is used to remove heavy component impurities.

[0023] Furthermore, the catalyst one and / or catalyst two is a cross-linked polystyrene type weakly basic anion exchange resin.

[0024] Further, in step S4, the light component impurities include at least one of hydrogen, nitrogen, oxygen, argon, carbon monoxide, and methane;

[0025] And / or, the heavy component includes at least one of monochlorotrihydrogensilane, dichlorodihydrogensilane and trichlorosilane.

[0026] Furthermore, in step S4, the third, fourth and fifth distillation tower bottoms are all provided with reboilers, and the tower tops are all provided with condensers; a compressor is set to compress and heat each reboiler, and the return water of the reboiler is used for heat exchange with the tower top condenser, and the return water of the condenser enters the compressor for feeding the heat exchange medium.

[0027] Furthermore, the reaction temperature of the disproportionation reaction 1 is 40-70° C., and the reaction pressure is 0.2-1.5 MPa; the conditions of the disproportionation reaction 2 are the temperature of 40-70° C., and the reaction pressure is 0.5-3.0 MPa.

[0028] Furthermore, the optimal operating conditions of the distillation towers T1 to T5 are as follows:

[0029] The operating pressure of the distillation tower T1 is 0.2-0.8 MPa, and the operating temperature is 35-180°C;

[0030] The operating pressure of the second distillation tower T2 is 0.1-0.6 MPa, and the operating temperature is 30-120°C; the operating pressure of the first distillation tower T1 is higher than that of the second distillation tower T2, ensuring that the top temperature of the first distillation tower T1 is higher than the bottom temperature of the second distillation tower T2, preferably 0.2 MPa higher, to achieve differential pressure thermal coupling distillation;

[0031] The operating pressure of the distillation tower T3 is 1.0~2.0MPa, and the operating temperature is -50~100℃;

[0032] The operating pressure of distillation tower 4 T4 is 1.5~3.0MPa, and the operating temperature is -50~-10℃;

[0033] The operating pressure of distillation tower five T5 is 1.2~2.8MPa, and the operating temperature is -65~-10℃.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The electronic-grade silane preparation device of the present invention is based on the first disproportionation reaction in the reactor, and dichlorodihydrosilane is separated by distillation as the raw material for the second disproportionation reaction. Silane can be obtained based on cheap trichlorosilane and a catalytic reagent, and electronic-grade silane can be obtained based on traditional distillation and purification; and heat exchange is performed between the top material of the distillation tower one and the tower bottom reboiler of the distillation tower two, thereby realizing differential pressure thermal coupling integration, and at the same time, condensation equipment and operation steps can be omitted, thereby reducing energy consumption, and overcoming the defects of high preparation cost and high energy consumption of the silane preparation device in the prior art.

[0036] The silane post-purification process of the present invention adopts a three-stage distillation tower integral heat pump distillation technology, which not only realizes the function of the heat pump distillation technology to provide both a heat source and a cold source in the distillation process, but also solves the problem of needing steam (hot water) and low-temperature refrigerated water in the distillation process. At the same time, the high efficiency of compression heat exchange is utilized to greatly reduce the energy consumption of the entire process, saving about 65% of energy compared with traditional distillation. In addition, three independent heat pump distillations are integrated into a universal system through the optimization and integration of process parameters, which greatly saves heat pump system equipment, reduces operation complexity and control difficulty, and saves system investment costs.

[0037] The silane preparation of the present invention uses a weakly alkaline polymer resin (cross-linked polystyrene type) with a special molecular weight distribution based on a two-stage disproportionation reaction, and can accurately control the proportion of functional groups (tertiary amino groups) in the molecular weight to achieve the effect of improving the catalytic efficiency, so that the primary disproportionation reaction can reach a one-time conversion rate of 28% to 32%, and the secondary disproportionation reaction can reach a one-time conversion rate of 45% to 60%, which is more than 20% higher than that of ordinary catalysts, greatly reducing the circulation amount of chlorosilane in the system and reducing process energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is a schematic diagram of the device for preparing the electronic-grade silane of the present invention.

[0040] Figure 1 The accompanying drawings are denoted as follows:

[0041] 10. Feed pipe one; 11. Reflux pipe one; 12. Feed pipe two; 21. Reflux pipe two; 22. Feed pipe three; 23. Circulation pipe one; 31. Reflux pipe three; 32. Feed pipe four; 33. Circulation pipe two; 41. Reflux pipe four; 42. Feed pipe five; 100. Compressed air pipe; 101. Return water pipe one; 102. Return water pipe two; 103. Return water pipe three; 200. Condensation main pipe; 300. Condensation return water main pipe. C1, condenser one; C2, condenser two; C3, condenser three; C4, condenser four; H1, reboiler one; H2, reboiler two; H3, reboiler three; H4, reboiler four; H5, reboiler five; R1, reactor one; R2, reactor two; S1, compressor; T1, distillation tower one; T2, distillation tower two; T3, distillation tower three; T4, distillation tower four; T5, distillation tower five; V1, storage tank one; V2, storage tank two; V3, storage tank three; V4, storage tank four. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Reference Figure 1 In one embodiment, a device for preparing electronic-grade silane is provided, comprising a reactor R1, a distillation tower T1, a distillation tower T2, a reactor R2 and a post-purification unit connected in sequence; wherein: the reactor R1 is provided with a feed pipe 10 for disproportionating trichlorosilane to generate dichlorosilane and silicon tetrachloride; the distillation tower T1 is used to separate dichlorosilane and feed it to the distillation tower T2; the distillation tower T2 is used to purify dichlorosilane and feed it to the reactor R2; the reactor R2 is used to disproportionately react dichlorosilane to generate silane and silicon trichloride; the post-purification unit is used to separate and purify silane to obtain electronic-grade silane;

[0044] The bottom of the distillation tower T2 is connected to a reboiler H2 for reboiling the bottom material; the top of the distillation tower T1 is provided with a reflux pipe 11, which is connected to the top of the distillation tower T1 via the heat exchange medium layer of the reboiler H2.

[0045] In the above embodiment, the preparation device generates tetrachlorosilane and dichlorosilane through a first disproportionation reaction of trichlorosilane, and separates dichlorosilane by distillation as a raw material for a second disproportionation reaction. Silane can be obtained based on cheap trichlorosilane and a catalytic agent, and electronic-grade silane can be obtained based on traditional distillation and purification. Moreover, since the first distillation tower needs to separate silicon tetrachloride and dichlorosilane, its distillation operating pressure and temperature are higher than those of the second distillation tower. Heat exchange can be carried out between the top material of the first distillation tower and the bottom reboiler of the second distillation tower, thereby realizing differential pressure thermal coupling integration, while eliminating condensation equipment and operating steps, thereby reducing energy consumption.

[0046] In a preferred embodiment, the bottom of the distillation tower T1 is provided with a reboiler H1 for reboiling the bottom of the tower to improve the distillation efficiency; the reflux pipe 11 is located at the output end of the reboiler H2 and is connected to the feed end of the distillation tower T2. The top of the distillation tower T2 is provided with a reflux pipe 21 connected to the reactor R2, and the output end of the reactor R2 is connected to the feed end of the post-purification unit. The above method realizes the continuous feeding of the separated fractions or products and improves the production efficiency.

[0047] In a preferred embodiment, the reactor 1 R1 and the reactor 2 R2 are respectively filled with weakly basic anion exchange resins, such as common cross-linked polystyrene weakly basic anion resins, vinyl cyclic tertiary amine polymer resins, etc., and the same or different catalysts can be adaptively selected.

[0048] In some embodiments, in order to obtain electronic-grade silane, the post-purification unit may be provided with multiple distillation towers in parallel. Specifically, the post-purification unit includes distillation tower three T3, distillation tower four T4, and distillation tower five T5 connected in sequence; the discharge end of the reactor two R2 is connected to the feed end of distillation tower three T3, and the top of distillation tower three T3 is provided with a reflux pipe three 31, which is connected to the feed end of distillation tower four T4; the bottom of distillation tower four T4 is provided with an extraction pipeline connected to the feed end of distillation tower five T5; the top of distillation tower five T5 is used to extract electronic-grade silane.

[0049] In the above embodiment, in the post-purification unit, the distillation tower three T3 is used to separate the unconverted trichlorosilane and dichlorosilane from the bottom of the tower, and silane is separated from the top of the tower to obtain a crude product; the distillation tower four T4 mainly removes trace light component impurities such as hydrogen, nitrogen, oxygen, argon, carbon monoxide, methane, etc. in silane from the top of the tower, and the purified silane is produced from the bottom of the tower; the distillation tower five T5 removes trace heavy component impurities such as monochlorotrisilane, dichlorosilane, trichlorosilane, etc. in silane from the bottom of the tower and then produces electronic grade silane from the top of the tower.

[0050] In a preferred embodiment, the post-purification unit also includes a compressor S1, and the compressor S1 outlet is provided with a compressed air pipe 100, and the inlet is provided with a condensation return water main pipe 300; the tower bottoms of the distillation tower three T3, the distillation tower four T4, and the distillation tower five T5 are respectively provided with reboiler three H3, reboiler four H4, and reboiler five H5 for reboiling circulation of tower bottom materials, and the tower tops are respectively provided with condenser two C2, condenser three C3, and condenser four C4 for condensation and reflux of materials; the compressed air pipe 100 passes through the heating medium layer of reboiler three H3, reboiler four H4, and reboiler five H5 and is correspondingly collected by return water pipe one 101, return water pipe two 102, and return water pipe three 103 to the condensation main pipe 200, and the condensation main pipe 200 passes through the condensation medium layer of condenser two C2, condenser three C3, and condenser four C4 and is collected to the condensation return water main pipe 300.

[0051] In the above embodiment, the post-purification unit adopts the three-stage distillation tower integral heat pump distillation technology, which not only realizes the function of heat pump distillation technology to provide both heat source and cold source in the distillation process, but also solves the problem of needing steam (hot water) and low-temperature chilled water in the distillation process. At the same time, the high efficiency of compression heat exchange is utilized to greatly reduce the energy consumption of the whole process, saving about 65% of energy compared with traditional distillation. In addition, three independent heat pump distillations are integrated into a universal system through the optimization and integration of process parameters, which greatly saves heat pump system equipment, reduces operation complexity and control difficulty, and saves system investment costs.

[0052] In some embodiments, the medium used in the heat pump distillation system used by the post-purification unit can be ammonia, chlorofluorocarbons, R13, R14, R23, R508B, R503 or other equivalent traditional medium and low temperature refrigerants, and its compression pressure and expansion pressure can match the use temperature.

[0053] In some embodiments, to ensure feed stability and distillation efficiency, a storage tank V1 is provided between the distillation tower T1 and the distillation tower T2, and the reflux pipe 11 is further connected to the storage tank V1 after passing through the reboiler H2, and the lower reflux of the storage tank V1 is connected to the top of the distillation tower T1; a feed pipe 12 is provided on the reflux output pipeline of the storage tank V1 to connect to the middle of the distillation tower T2. To improve the utilization rate of raw materials, a circulating pipe 23 is provided in the bottom of the distillation tower T2 to connect to the reactor R1.

[0054] In some embodiments, to ensure feed stability and distillation efficiency, a condenser C1 is provided at the top of the distillation tower T1, and a reflux pipe 21 is connected to a storage tank V2 after passing through the condenser C1, and the lower part of the storage tank V2 is connected to the top reflux of the distillation tower 21; a feed pipe 3 22 is provided at the lower part of the storage tank V2 to connect to the reactor R2 and further to the middle part of the distillation tower T3. To improve the utilization rate of raw materials, a circulating pipe 2 33 is provided at the bottom of the distillation tower T3 to connect to the feed port of the distillation tower T2.

[0055] In some embodiments, in order to ensure feed stability and distillation efficiency, for the post-purification unit: the reflux pipe three 31 is connected to the storage tank three V3 after passing through the condenser two C2, and the lower part of the storage tank three V3 is refluxed and connected to the top of the distillation tower three T3; the lower part of the storage tank three V3 is provided with a feed pipe four 32 connected to the upper feed end of the distillation tower four T4. The top of the distillation tower four T4 is provided with a reflux pipe four 41 to reflux to the top of the tower through the condenser three C3, and the tower kettle of the distillation tower four T4 is provided with a feed pipe five 42 to connect to the middle part of the distillation tower five T5. The return water ends of the reboiler three H3, the reboiler four H4, and the reboiler five H5 are respectively connected to the storage tank four V4, and the lower part of the storage tank four V4 is connected to the condensation main pipe 200.

[0056] As a conventional setting in the field, the above-mentioned preparation device also includes a power pump for providing material transfer, a valve for pipeline control, and instruments for monitoring working conditions, which will not be described in detail here.

[0057] In one embodiment, reference Figure 1 , a preparation process of electronic grade silane is proposed, the steps comprising:

[0058] S1. Trichlorosilane enters the reactor R1 from the feed pipe 10, and undergoes a first disproportionation reaction under the catalysis of a cross-linked polystyrene type weakly basic anion resin to obtain dichlorosilane and silicon tetrachloride;

[0059] S2. The product obtained in step S1 is successively passed through a distillation tower T1 to remove silicon tetrachloride, and the top component enters a distillation tower T2 from a feed pipe 12 to separate trichlorosilane from the bottom of the tower, and obtains dichlorosilane from the top of the tower;

[0060] S3. The dichlorosilane produced from the top of the distillation tower T2 is condensed in a condenser C1 and then enters the reactor R2 from the feed pipe 22, where a second disproportionation reaction occurs under the catalysis of a cross-linked polystyrene-type weakly basic anion resin to generate silane and trichlorosilane;

[0061] S4. The product of the reactor two R2 is successively distilled in the distillation tower three T3, the distillation tower four T4 and the distillation tower five T5 to obtain electronic grade silane; the distillation tower three T3 is used for the preliminary removal of trichlorosilane and dichlorosilane; the distillation tower four T4 is used for removing light component impurities; the distillation tower five T5 is used for removing heavy component impurities; the light component impurities removed by the fourth distillation include at least one of hydrogen, nitrogen, oxygen, argon, carbon monoxide and methane; the heavy components removed by the fifth distillation include at least one of monochlorotrihydrosilane, dichlorosilane and trichlorosilane.

[0062] In the above embodiment, the preparation process adopts two-stage disproportionation reaction with trichlorosilane as raw material, and uses a weakly alkaline cross-linked polystyrene type weakly alkaline anion exchange resin with a molecular weight distribution having a particularity, which can accurately control the ratio of the functional group (tertiary amino group) in the molecular weight to achieve the effect of improving the catalytic efficiency, so that the primary disproportionation reaction conversion rate can reach 28% to 32%, and the secondary disproportionation reaction conversion rate can reach 45 to 60%, which is more than 20% higher than the ordinary catalyst, greatly reducing the circulation amount of chlorosilane in the system, and reducing the process energy consumption. The post-purification process first removes heavy components such as trichlorosilane and dichlorodihydrosilane, and then removes impurity light components, and the residual monochlorotrihydrosilane, dichlorodihydrosilane, and trichlorosilane, the process is reasonable, and electronic grade silane is finally obtained.

[0063] In a preferred embodiment, the first disproportionation reaction conditions are: temperature 40-70°C, reaction pressure 0.2-1.5 MPa; the conversion rate of trichlorosilane can reach up to 32%; the second disproportionation reaction conditions are: temperature 40-70°C, reaction pressure 0.5-3.0 MPa, and the conversion rate of dichlorosilane can reach up to 60%.

[0064] In a preferred embodiment, the optimal operating conditions of the distillation towers T1 to T5 are as follows:

[0065] The operating pressure of the distillation tower T1 is 0.2-0.8 MPa, and the operating temperature is 35-180°C;

[0066] The operating pressure of the second distillation tower T2 is 0.1-0.6 MPa, and the operating temperature is 30-120°C; the operating pressure of the first distillation tower T1 is higher than that of the second distillation tower T2, ensuring that the top temperature of the first distillation tower T1 is higher than the bottom temperature of the second distillation tower T2, preferably 0.2 MPa higher, to achieve differential pressure thermal coupling distillation;

[0067] The operating pressure of the distillation tower T3 is 1.0~2.0MPa, and the operating temperature is -50~100℃;

[0068] The operating pressure of distillation tower 4 T4 is 1.5~3.0MPa, and the operating temperature is -50~-10℃;

[0069] The operating pressure of distillation tower five T5 is 1.2~2.8MPa, and the operating temperature is -65~-10℃.

[0070] Under the above operating conditions, the distillation tower T1 mainly separates silicon tetrachloride and extracts it from the tower bottom. Its purity can reach 4N, which can be used as the main raw material for downstream optical fiber grade silicon tetrachloride, ethyl orthosilicate, and cold hydrogenation processes. The trichlorosilane (purity exceeding 99%) extracted from the tower bottom of the distillation tower T2 can be recycled back to the primary reactor as a reaction raw material to improve the comprehensive conversion rate of trichlorosilane. The trichlorosilane extracted from the tower bottom of the distillation tower T3 is added to dichlorosilane and recycled back to the distillation tower T2 as feed, realizing the original recovery of trichlorosilane and the re-disproportionation utilization of dichlorosilane by-product.

[0071] Under the above operating conditions, preferably, the differential pressure thermal coupling integration technology is used to link the distillation tower T1 and the distillation tower T2, that is, the material produced from the top of the distillation tower T1 is used to heat the reboiler of the distillation tower T2. By linking the distillation tower T1 and the distillation tower T2 through differential pressure thermal coupling, the energy consumption of the entire process can be reduced by more than 60%. It should be noted that the linkage process must be based on the working conditions of the two distillation towers. Under this process, the temperature of the material produced from the top of the distillation tower T1 is higher than the operating temperature of the distillation tower T2, which is a prerequisite for the differential pressure thermal coupling integration and cannot be used under any condition.

[0072] In the above embodiment, the process operates the two-stage disproportionation and distillation operations independently, and can accurately control the temperature and pressure of the reaction at the efficiency value with the best reaction effect. At the same time, the operating parameters of each tower are designed according to the optimal distillation separation conditions to achieve a silane product purity of 7N and a by-product silicon tetrachloride purity of 4N.

[0073] In a preferred embodiment, the tower kettles of the distillation tower three T3, the distillation tower four T4 and the distillation tower five T5 are all provided with reboilers, and the tower tops are all provided with condensers; by setting up a compressor S1 to compress and heat each reboiler, the return water of the reboiler is used to exchange heat with the tower top condenser, and the return water of the condenser enters the compressor S1 for feeding the heat exchange medium. Through heat pump distillation, the high-temperature gas coming out of the compressor S1 enters the reboilers of the distillation tower three T3, the distillation tower four T4 and the distillation tower five T5 respectively, as the heat source of the reboiler. In this process, the high-temperature gas is condensed and liquefied, and the liquefied liquid is respectively transported to the tower top condensers of the distillation tower three T3, the distillation tower four T4 and the distillation tower five T5, and after throttling expansion, it is used as a cold source to cool the material in the condenser, so that the silane in the pipe pass is liquefied and refluxed. The expanded gas returns to the compressor for compression and recycling, and this process can further reduce the energy consumption of the distillation process.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for preparing electronic grade silane, characterized in that: It includes a reactor 1 (R1), a distillation tower 1 (T1), a distillation tower 2 (T2), a reactor 2 (R2) and a post-purification unit which are connected in sequence; wherein: Reactor 1 (R1) is used to disproportionate trichlorosilane to generate dichlorosilane and silicon tetrachloride; The distillation tower 1 (T1) is used to separate dichlorosilane and feed it to the distillation tower 2 (T2); the distillation tower 2 (T2) is used to purify dichlorosilane and feed it to the reactor 2 (R2); Reactor 2 (R2) is used to disproportionately react dichlorosilane to produce silane and silicon trichloride; The post-purification unit is used to separate and purify silane to obtain electronic grade silane; The bottom of the second distillation tower (T2) is connected to a second reboiler (H2) for reboiling the bottom material; the top of the first distillation tower (T1) is provided with a first reflux pipe (11), which is connected to the top of the first distillation tower (T1) via the heat exchange medium layer of the second reboiler (H2).

2. The preparation device according to claim 1, characterized in that: The reflux pipe 1 (11) is located at the output end of the reboiler 2 (H2) and is connected to the feed end of the distillation tower 2 (T2); And / or, a second reflux pipe (21) is provided at the top of the second distillation tower (T2) and is connected to the second reactor (R2), and the output end of the second reactor (R2) is connected to the feed end of the post-purification unit.

3. The preparation device according to claim 1, characterized in that: The post-purification unit comprises a distillation tower three (T3), a distillation tower four (T4), and a distillation tower five (T5) which are connected in sequence; the discharge end of the reactor two (R2) is connected to the feed end of the distillation tower three (T3), the top of the distillation tower three (T3) is provided with a reflux pipe three (31), and the reflux pipe three (31) is connected to the feed end of the distillation tower four (T4); the bottom of the distillation tower four (T4) is provided with an extraction pipeline connected to the feed end of the distillation tower five (T5); the top of the distillation tower five (T5) is used to extract electronic grade silane.

4. The preparation device according to claim 3, characterized in that: The post-purification unit also includes a compressor (S1), the compressor (S1) outlet is provided with a compressed air pipe (100), and the inlet is provided with a condensation return water main pipe (300); the tower bottoms of the distillation tower three (T3), the distillation tower four (T4), and the distillation tower five (T5) are respectively provided with a reboiler three (H3), a reboiler four (H4), and a reboiler five (H5) for reboiling and circulating the tower bottom materials, and the tower tops are respectively provided with a condenser two (C2), a condenser three (C3), and a condenser four (C4) for condensing and refluxing the materials; the compressed air pipe (100) passes through the heat supply medium layers of the reboiler three (H3), the reboiler four (H4), and the reboiler five (H5) and is collected to the condensation main pipe (200), and the condensation main pipe (200) passes through the condensation medium layers of the condenser two (C2), the condenser three (C3), and the condenser four (C4) and is collected to the condensation return water main pipe (300).

5. The preparation device according to claim 3, characterized in that: The bottom of the distillation tower three (T3) is provided with a circulation pipe two (33) which is connected with the feed inlet of the distillation tower two (T2).

6. The preparation device according to claim 1, characterized in that: The bottom of the second distillation tower (T2) is provided with a circulation pipe (23) connected to the reactor (R1).

7. A process for preparing electronic grade silane, characterized in that the steps include: S1. Trichlorosilane undergoes a disproportionation reaction under the action of a catalyst to obtain dichlorosilane and silicon tetrachloride; S2. The product obtained in step S1 is subjected to a first distillation to remove silicon tetrachloride and a second distillation to remove trichlorosilane to obtain dichlorosilane; S3. Dichlorosilane undergoes a disproportionation reaction under the action of catalyst 2 to produce silane and trichlorosilane; S4. The product obtained in step S3 is subjected to the third, fourth and fifth distillations in sequence to obtain electronic grade silane; the third distillation is used to preliminarily remove trichlorosilane and dichlorosilane; the fourth distillation is used to remove light component impurities; and the fifth distillation is used to remove heavy component impurities.

8. The process according to claim 7, characterized in that The catalyst one and / or catalyst two is a cross-linked polystyrene type weakly basic anion exchange resin.

9. The process according to claim 7, characterized in that In step S4, the light component impurities include at least one of hydrogen, nitrogen, oxygen, argon, carbon monoxide, and methane; And / or, the heavy component includes at least one of monochlorotrihydrogensilane, dichlorodihydrogensilane and trichlorosilane.

10. The process according to claim 7, characterized in that In step S4, the third, fourth and fifth distillation tower bottoms are all provided with reboilers and the tower tops are all provided with condensers; compressors are set to compress and heat each reboiler, and the return water of the reboiler is used for heat exchange with the tower top condenser, and the return water of the condenser enters the compressor for feeding the heat exchange medium.

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