Method for producing silane gas by combining fixed bed reactor with reactive distillation column and silane gas production system

Abstract

The application provides a method for producing silane gas by combining a fixed bed reactor with a reaction rectifying tower and a silane gas production system, and relates to the technical field of silane gas production. The method for producing silane gas by combining the fixed bed reactor with the reaction rectifying tower comprises the following steps: S10, performing a DCS disproportionation reaction in the fixed bed reactor by using a DCS raw material to obtain a one-step disproportionation product; S20, performing rectifying separation on the one-step disproportionation product in a primary separation tower, collecting crude SiH4 at the top of the tower, and collecting a chlorosilane mixture at the bottom of the tower; S30, performing rectifying separation on the chlorosilane mixture in a secondary separation tower, and collecting a TCS mixture at the bottom of the tower; and S40, performing a TCS disproportionation reaction in a reaction rectifying tower by using a TCS raw material and the TCS mixture collected at the bottom of the tower in S30, and performing rectifying separation to collect crude SiH4 at the top of the tower. The silane gas production system comprises a fixed bed reactor, a primary separation tower, a secondary separation tower and a reaction rectifying tower. The application can not only improve the conversion rate of the total DCS reaction process, but also improve the silane gas production capacity and reduce the operation energy consumption.

Description

Technical Field

[0001] This invention relates to the field of silane gas production technology, specifically to a method and system for producing silane gas by combining a fixed-bed reactor with a reactive distillation column. Background Technology

[0002] Silanes are compounds of silicon and hydrogen, a general term encompassing a series of compounds including (SiH4), (Si2H6), and some more advanced silicon-hydrogen compounds, with the general formula SinH2n+2. Silanes can be used to perform a variety of flexible chemical reactions to produce high-purity, high-precision (down to the atomic scale) silicon materials.

[0003] Silane, also known as silicon tetrahydrode, with the chemical formula SiH4, is the most common type of silane, sometimes simply referred to as silane. Silane can be used to manufacture high-purity polycrystalline silicon, monocrystalline silicon, microcrystalline silicon, amorphous silicon, silicon nitride, silicon oxide, heterosilicon, and various metal silicides. Due to its high purity and ease of precise control, it has become the most important special gas in semiconductor microelectronics technology, irreplaceable by other silicon sources. Silane is widely used in the microelectronics and optoelectronics industries for manufacturing solar cells, flat panel displays, glass, and other fields, and is currently the intermediate product for the large-scale production of granular silicon worldwide.

[0004] The manufacturing processes of silane can be mainly divided into three types: magnesium silicide method, lithium aluminum hydride method, and chlorosilane disproportionation method.

[0005] 1) The magnesium silicide method was the first industrial method for synthesizing SiH4 developed abroad. It contains relatively low levels of metals, and the crude silane is purified by distillation or adsorption, complexation, absorption, and other processes. Its advantages are simple and mature process, wide availability of raw materials, and low cost. Its disadvantages are high energy consumption for separating and recovering liquid ammonia, but the SiH4 yield is relatively low (average yield is 80%).

[0006] 2) The lithium aluminum hydride method uses the strong reducing agent LiAlH4 in a solvent of dimethyl ether tetrahydrofuran to generate SiH4 gas through the reduction reaction SiCl4 + LiAlH4 → SiH4 + LiCl + AlCl3. The raw materials LiAlH4 and SiCl4 are readily generated, but they are chemically highly reactive, resulting in a violent reaction, high risk, and difficulty in controlling the production process.

[0007] 3) The chlorosilane disproportionation method (i.e., the modified Siemens process) involves hydrogenating chlorosilanes with industrial silicon powder under the action of a catalyst to obtain chlorosilanes, followed by a secondary disproportionation reaction to prepare silanes. This is simply referred to as a "two-step" disproportionation process; the first step has a lower conversion rate, while the second step has a higher conversion rate. Main reactions:

[0008] SiCl4 + H2 + Si → SiHCl3 (hydrogenation reaction)

[0009] SiHCl3 → SiH2Cl2 + SiCl4 (First disproportionation reaction)

[0010] SiH₂Cl₂ → SiH₄ + SiHCl₃. (Second disproportionation reaction)

[0011] The modified Siemens process is a widely used industrial production process with an annual output of up to 100,000 tons. It is also an ideal method for producing several silicon source gases (SiH4, SiH2Cl2, and SiHCl3), all of which can be widely used in optoelectronics, microelectronics, and fiber optic manufacturing. The production process is mature, can be continuous, and can be adjusted according to the amount of silicon used in various products, resulting in low-cost silane production. Each step in the SiHCl3→SiH2Cl2→SiH4 production chain includes purification and separation, resulting in high-purity products. Therefore, this method is widely used in large-scale silane production. It is used to prepare various microelectronic thin films and a series of silicon-containing materials such as single-crystal silicon, polycrystalline silicon, amorphous silicon, metal silicides, silicon nitride, silicon carbide, and silicon oxide.

[0012] In the modified Siemens process, the main raw materials, intermediates, and products include: monochlorosilane, dichlorosilane, trichlorosilane, silicon chloride, and silane. Monochlorosilane (MCS) is an inorganic silicon compound with the chemical formula SiH3Cl, commonly abbreviated as MCS. Currently, monochlorosilane is primarily used as an intermediate in the synthesis of compounds such as TSA, and is widely used in the semiconductor chip and solar energy industries. Dichlorosilane (DCS) is an inorganic silicon compound with the chemical formula SiH2Cl2, commonly abbreviated as DCS. DCS has a wide range of applications and is one of the commonly used specialty gases in the integrated circuit industry and semiconductor chips. Trichlorosilane (TCS) is an inorganic silicon compound with the chemical formula SiHCl3, commonly abbreviated as TCS, primarily used in the manufacture of compounds. Silicon chloride (STC), also known as tetrachlorosilane, is an inorganic silicon compound with the chemical formula SiCl4. It is commonly abbreviated as STC and is mainly used to produce pure silicon, ethyl silicate, and other products, as well as smoke agents.

[0013] Gaseous silane is also known as silane gas. Currently, the most common processes for producing silane gas include the disproportionation reaction of DCS or TCS based on the modified Siemens process. These processes are relatively simple and lack flexibility. Furthermore, in processes using DCS as a raw material, both DCS and silane gas are low-boiling-point substances, resulting in high energy consumption during separation. Additionally, DCS typically originates from byproducts and intermediates of the modified Siemens process, and the yield of DCS among these byproducts and intermediates is low. Processes using TCS as a raw material involve multiple steps and are reversible, but the single-pass conversion rate of TCS is relatively low. Summary of the Invention

[0014] This invention addresses the problems of existing silane gas production processes, which mainly involve disproportionation reactions based on modified Siemens DCS or TCS, resulting in a single process route, high energy consumption, and low conversion rate. It provides a method and system for producing silane gas by combining a fixed-bed reactor with a reactive distillation column, which not only improves the overall conversion rate of the DCS reaction process but also increases silane gas production capacity and reduces operating energy consumption.

[0015] The technical solution adopted in this invention is:

[0016] A method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column, comprising:

[0017] S10. Using DCS feedstock, a DCS disproportionation reaction is carried out in a fixed-bed reactor to obtain a one-step disproportionation product;

[0018] S20. The one-step disproportionation product obtained in S10 is separated by distillation in a primary separation column. Crude SiH4 is collected at the top of the column, and a mixture of chlorosilanes is collected at the bottom of the column.

[0019] S30. The chlorosilane mixture collected from the bottom of column S20 is separated by distillation in a secondary separation column, and the TCS mixture is collected from the bottom of the column;

[0020] S40. Using TCS feedstock and the TCS mixture collected from the bottom of column S30, a TCS disproportionation reaction is carried out together in a reactive distillation column, and the product is separated by distillation, with crude SiH4 collected at the top of the column.

[0021] Furthermore, the DCS raw material mentioned in S10 includes DCS, a byproduct of the modified Siemens process; the TCS raw material mentioned in S40 includes TCS, an intermediate product of the modified Siemens process.

[0022] Furthermore, it also includes:

[0023] S50. The crude SiH4 gaseous product collected in S20 and S40 is adsorbed and purified by an adsorption device, and then purified by distillation in a purification tower. The SiH4 product is collected from the top of the purification tower, and the liquid mixture with MCS as the main component and impurities are collected from the bottom of the purification tower.

[0024] Furthermore, it also includes:

[0025] S52. The crude liquid SiH4 product collected in S20 and S40 is purified by distillation in a purification tower. The SiH4 product is collected from the top of the purification tower, and the liquid mixture with MCS as the main component and impurities are collected from the bottom of the purification tower.

[0026] Further, S30 includes: collecting the DCS mixture at the top of the column, and the method for producing silane gas by combining the fixed-bed reactor with the reactive distillation column further includes:

[0027] S60. The liquid mixture with MCS as the main component collected from the bottom of the purification tower in S50 or S52 is returned to the secondary separation tower in S30 for further distillation and separation.

[0028] S70. The DCS mixture collected from the top of the column in S30 is returned to the fixed-bed reactor in S10 for DCS disproportionation reaction.

[0029] A silane gas production system, comprising:

[0030] A fixed-bed reactor is equipped with a DCS feed inlet, which can carry out DCS disproportionation reaction to produce one-step disproportionation products.

[0031] The primary separation tower, connected to the discharge end of the fixed-bed reactor, is capable of distilling and separating the one-step disproportionation product. The top discharge end of the primary separation tower is used to collect crude SiH4, and the bottom discharge end is used to collect a mixture of chlorosilanes.

[0032] A secondary separation column, connected to the bottom outlet of the primary separation column, is capable of distilling and separating the chlorosilane mixture, and the bottom outlet of the secondary separation column is used to collect the TCS mixture; and

[0033] The reactive distillation column is connected to the bottom outlet of the secondary separation column and is equipped with a TCS inlet. It can carry out TCS disproportionation reaction and separate the product by distillation. The top outlet of the reactive distillation column is used to collect crude SiH4.

[0034] Furthermore, it also includes a degassing tower; the feed end of the degassing tower is used to introduce DCS raw materials, and its discharge end is connected to the DCS feed port of the fixed bed reactor. The degassing tower can perform light removal and purification of DCS raw materials.

[0035] Furthermore, it also includes:

[0036] The adsorption device is connected to the gas phase pipeline at the top output of both the primary separation tower and the reactive distillation tower. The adsorption device can adsorb and remove impurities from the crude SiH4 product in the gas phase.

[0037] The purification tower is connected to the liquid phase pipeline at the top output end of the primary separation tower and the reactive distillation tower, or to the discharge end of the adsorption device. The purification tower can distill and remove heavy components and impurities containing MCS from crude SiH4.

[0038] Furthermore, the MCS discharge end of the purification tower is connected to the feed end of the secondary separation tower, so that the liquid mixture with MCS as the main component collected from the bottom of the purification tower can be returned to the secondary separation tower for further distillation and separation.

[0039] Furthermore, the top of the secondary separation tower is provided with a liquid phase pipeline at the output end for collecting the DCS mixture and connecting it to the DCS feed port of the fixed bed reactor, so that the DCS mixture collected from the top of the secondary separation tower can be returned to the fixed bed reactor for DCS disproportionation reaction.

[0040] The beneficial effects of this invention are:

[0041] 1. The production method of the present invention uses a fixed-bed reactor and a two-stage separation tower to carry out the disproportionation reaction and distillation separation of DCS. On the one hand, it takes advantage of the high conversion rate and low degree of reverse reaction of DCS disproportionation reaction, and saves energy consumption by using a fixed-bed reactor. On the other hand, based on the fact that the boiling points of DCS feedstock and product are close, the reaction space and the distillation space are set up separately, which reduces the DCS impurity content in the crude SiH4 product. At the same time, the reactive distillation tower is used to carry out the reaction and distillation of TCS simultaneously, so that the reversible reaction of TCS disproportionation can proceed in the forward direction to the maximum extent, thereby improving the conversion rate of TCS, thus improving the overall conversion rate of the reaction process, while reducing operating energy consumption, and solving the problems of high energy consumption and low conversion rate in the existing silane gas production process.

[0042] 2. The production method of the present invention also combines the process of preparing silane gas by DCS and the process of preparing silane gas by TCS, and continues to utilize the product of the DCS reaction in the TCS reaction. This makes the production method of the present invention adaptable to changes in the amount of DCS and TCS, and coordinates with the modified Siemens process, thereby enhancing the process flexibility and raw material adaptability. It solves the problem that the existing technology processes with a large amount of silane gas mainly involve the disproportionation reaction of DCS or TCS based on the modified Siemens process to prepare silane gas, resulting in a single process route.

[0043] 3. The production system of this invention uses a fixed-bed reactor and a two-stage separation tower for the disproportionation reaction and distillation separation of DCS. On the one hand, it utilizes the high conversion rate and low degree of reverse reaction of DCS disproportionation reaction, saving energy consumption through the fixed-bed reactor. On the other hand, based on the fact that the boiling points of DCS feedstock and product are close, the reaction space and distillation space are set up separately, reducing the DCS impurity content in the crude SiH4 product. At the same time, the reactive distillation tower is used to simultaneously carry out the reaction and distillation of TCS, allowing the reversible reaction of TCS disproportionation to proceed in the forward direction to the maximum extent, improving the conversion rate of TCS, thereby increasing the overall conversion rate of the reaction process and reducing operating energy consumption. The scheme of synergistic use of two disproportionation processes and the separate selection of fixed-bed reactor and reactive distillation tower solves the problems of high energy consumption and low conversion rate in the existing silane gas production process. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart of the production method according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the production system according to the third embodiment of the present invention.

[0047] Attached reference numerals: 100-Degassing tower, 101-Condenser, 103-Reboiler;

[0048] 200-First stage separation tower;

[0049] 300-Secondary Separation Tower;

[0050] 400 - Purification tower, 401 - First SiH4 discharge end, 402 - Second SiH4 discharge end, 403 - MCS discharge end;

[0051] 500 - Fixed-bed reactor, 510 - DCS feed inlet;

[0052] 600 - Reactive distillation column, 610 - TCS feed inlet, 620 - Catalyst reaction section, 630 - Rectifying section, 640 - Stripping section;

[0053] 700 - Adsorption device;

[0054] 810 - First booster pump, 820 - Second booster pump, 830 - Compressor, 840 - Third booster pump. Detailed Implementation

[0055] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0056] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention.

[0057] The embodiments of the invention will now be described in detail with reference to the accompanying drawings.

[0058] Example 1

[0059] Currently, the most common processes for producing silane gas include the disproportionation reaction of DCS or TCS based on the modified Siemens process. These processes are relatively simple and lack flexibility. Furthermore, in processes using DCS as a raw material, both DCS and silane gas are low-boiling-point substances, resulting in high energy consumption during separation. Additionally, DCS typically originates from byproducts and intermediates of the modified Siemens process, and the yield of DCS in these byproducts and intermediates is low. Processes using TCS as a raw material involve multiple steps and are reversible, but the single-pass conversion rate of TCS is relatively low.

[0060] Please see Figures 1-2 This embodiment provides a method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column. It utilizes the DCS and TCS byproducts of a modified Siemens process to produce silane gas, changing the original silane gas production mode, enhancing process flexibility and feedstock adaptability. Simultaneously, it not only improves the overall conversion rate of the DCS reaction process but also increases silane gas production capacity and reduces operating energy consumption. Figure 1 As shown, the method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column mainly includes the following steps:

[0061] S10. Using DCS feedstock, the feedstock enters the fixed-bed reactor 500 through the DCS inlet 510. A DCS disproportionation reaction is carried out in the fixed-bed reactor 500 to obtain a one-step disproportionation product. The main component of the DCS feedstock is DCS, a byproduct of the modified Siemens process. This embodiment combines a fixed-bed reactor with a reactive distillation column to produce silane gas, which can be used to treat surplus DCS byproducts from the modified Siemens process that are difficult to process. The fixed-bed reactor 500 is fed from the bottom up. The DCS inlet 510 is located at its bottom. The interior of the fixed-bed reactor 500 is filled with catalyst to form a fixed bed. The reactants can flow continuously through the fixed bed, while the catalyst in the fixed bed remains stationary for catalysis. The main reaction formula for the DCS disproportionation reaction is:

[0062] SiH2Cl2→SiH4+SiHCl3;

[0063] During the reaction, the temperature in the fixed-bed reactor 500 is preferably maintained between 30°C and 80°C, and the pressure is preferably maintained between 20 and 35 bar. The main products of the one-step disproportionation include SiH4, TCS, as well as MCS produced by the secondary reaction and unreacted DCS.

[0064] S20. The one-step disproportionation product obtained in S10 is separated by distillation in a primary separation column 200. Crude SiH4 is collected at the top of the column, and a chlorosilane mixture is collected at the bottom. The primary separation column 200 mainly performs the distillation separation of the one-step disproportionation product, primarily separating the crude SiH4 product. During the distillation process, the temperature inside the primary separation column 200 is preferably maintained between -35℃ and -15℃, and the pressure is preferably maintained between 20 and 30 bar. The crude SiH4 collected at the top of the column mainly consists of high-purity SiH4 with trace amounts of MCS. Since the disproportionation reaction takes place in the fixed-bed reactor 500, while the distillation separation takes place in the primary separation column 200, the inclusion of excessive DCS feedstock in the crude SiH4 is avoided, saving energy consumption in the distillation separation. The chlorosilane mixture collected at the bottom of the column mainly consists of MCS, DCS, TCS, and trace amounts of STC.

[0065] S30. The chlorosilane mixture collected from the bottom of column S20 is further separated by distillation in secondary separation column 300. A DCS mixture is collected at the top of the column, and a TCS mixture is collected at the bottom. The secondary separation column 300 primarily performs the distillation separation of the chlorosilane mixture, mainly to separate the TCS mixture, which is then added to the subsequent TCS disproportionation reaction. During the distillation process, the temperature inside the secondary separation column 300 is preferably maintained between 40°C and 70°C, and the pressure is preferably maintained between 5 and 10 bar. The DCS mixture collected at the top mainly consists of DCS and MCS, while the chlorosilane mixture collected at the bottom mainly consists of TCS and trace amounts of STC.

[0066] S40. Using TCS feedstock and the TCS mixture collected from the bottom of column S30, the mixture enters reactive distillation column 600 through TCS inlet 610. The TCS disproportionation reaction takes place together in reactive distillation column 600, and the products are separated by distillation. Crude SiH4 is collected at the top of the column, and STC by-product is collected at the bottom. The main component of the TCS feedstock is TCS, an intermediate product of the modified Siemens process, providing a new pathway for the production of silane gas using TCS as an intermediate product of the modified Siemens process. The TCS mixture is derived from the by-product of S30, ensuring full utilization of this by-product. Simultaneously, a catalyst reaction section 620 is provided inside the reactive distillation column 600. The catalyst packed in the catalyst reaction section 620 promotes the disproportionation reaction and also serves as packing material in the distillation column, providing a site for mass and heat transfer between the gas and liquid phases, achieving component separation. The main reaction formula for the TCS disproportionation reaction is:

[0067] SiHCl3 → SiH2Cl2 + SiCl4 (First disproportionation reaction)

[0068] SiH₂Cl₂ → SiH₄ + SiHCl₃. (Second disproportionation reaction)

[0069] During the reaction, the temperature inside the reactive distillation column 600 is preferably maintained between -100℃ and -50℃, and the pressure is preferably maintained between 1 and 7 bar. The two-step disproportionation products mainly include SiH4, STC, and MCS produced by secondary reactions. After component separation, crude SiH4 is collected at the top of the column. The main component of the crude SiH4 product is also high-purity SiH4, with trace amounts of MCS. The STC byproduct is collected at the bottom of the column and can be returned to the modified Siemens process production system as a feedstock for chlorosilane production. Furthermore, the collection from the top and bottom of the reactive distillation column 600 occurs simultaneously during the reaction process, allowing the SiH4 and STC products from the reaction process to be removed from the system in a timely manner. This facilitates the forward progress of the TCS disproportionation reaction, thereby improving its conversion rate.

[0070] In summary, in this embodiment, the method of producing silane gas by combining a fixed-bed reactor and a reactive distillation column uses a fixed-bed reactor 500 and a two-stage separation column to perform the disproportionation reaction and distillation separation of DCS. On the one hand, it utilizes the high conversion rate and low degree of reverse reaction of DCS disproportionation reaction, saving energy consumption through the fixed-bed reactor 500. On the other hand, based on the fact that the boiling points of DCS feedstock and product are close, the reaction space and distillation space are set up separately, reducing the DCS impurity content in the crude SiH4 product. At the same time, the reactive distillation column 600 is used to simultaneously carry out the reaction and distillation of TCS, so that the reversible reaction of TCS disproportionation can proceed in the forward direction to the maximum extent, improving the conversion rate of TCS, thereby increasing the overall conversion rate of the reaction process, while reducing operating energy consumption, solving the problems of high energy consumption and low conversion rate in the existing silane gas production process.

[0071] Meanwhile, this embodiment also combines the process of preparing silane gas by DCS and the process of preparing silane gas by TCS, so that the products of the DCS reaction can be reused in the TCS reaction. This makes the production method of this embodiment adaptable to changes in the amount of DCS and TCS, and coordinates with the modified Siemens process, which enhances the process flexibility and raw material adaptability. It solves the problem that the existing technology processes with a large amount of silane gas mainly involve the disproportionation reaction of DCS or TCS based on the modified Siemens process to prepare silane gas, and the process route is too simple.

[0072] like Figure 1 As shown, to reduce the amount of hydrogen and light component impurities easily carried in the DCS feedstock, step S10 of this embodiment further includes: before the DCS feedstock enters the fixed-bed reactor 500, it is first introduced into a degassing tower 100 to desorb the dissolved hydrogen, remove light component impurities and hydrogen, and finally the degassing tower is collected from the bottom of the tower and enters the fixed-bed reactor 500. Specifically, the degassing tower 100 desorbs the dissolved hydrogen inside the feedstock, whose main component is DCS, and removes light component impurities and hydrogen through distillation separation. The hydrogen is discharged as non-condensable gas from the gas phase pipe of the condenser 101 at the top of the tower. The purified feedstock, whose main component is DCS, is collected from the bottom of the tower as liquid and then enters the subsequent catalytic disproportionation reaction, thereby avoiding contamination of the catalytic disproportionation reaction products by light component impurities and hydrogen, which would affect product quality. Furthermore, in step S10, the temperature for removing light components and impurities in the degassing tower 100 is preferably maintained between 15°C and 50°C, and the pressure is preferably maintained between 2 and 7 bar.

[0073] Meanwhile, in this embodiment, the crude SiH4 product collected in steps S20 and S40 can be collected in the gas phase through the gas phase pipeline at the top of the primary separation tower 200 and the reactive distillation tower 600; alternatively, it can be collected in the liquid phase after being condensed by the condenser 101 through the liquid phase pipeline at the top of the primary separation tower 200 and the reactive distillation tower 600. To reduce impurities and improve the purity of the crude SiH4 product, the method for producing silane gas in this embodiment also includes the following steps:

[0074] S50. The crude SiH4 gaseous product containing a small amount of MCS collected in S20 and S40 is adsorbed and purified by adsorption in adsorption unit 700, and then purified by distillation in purification tower 400. High-purity SiH4 gaseous or liquid product is collected from the top of purification tower 400, and a liquid mixture mainly composed of MCS and impurities is collected from the bottom of purification tower 400. The adsorption unit 700 is filled with an adsorbent (adsorption resin or activated carbon, etc.) to remove B, P, and metallic impurities. Purification tower 400 is used to remove heavy components and impurities containing MCS from the crude SiH4 gaseous product. In step S50, the distillation purification temperature is preferably maintained between -50°C and -15°C, and the pressure is preferably maintained between 20 and 30 bar.

[0075] In addition, in order to make full use of the by-products of the production method of this embodiment, the method for producing silane gas of this embodiment also includes the following steps:

[0076] S60. The liquid mixture, mainly composed of MCS, collected from the bottom of column S50 is returned to the secondary separation column 300 in S30 for further distillation. After returning, the liquid mixture can continue to undergo distillation and subsequent processes according to the production process flow, thereby fully utilizing the MCS in the by-product for disproportionation reaction to produce silane gas. Alternatively, if S60 is not reintroduced, or in case of an emergency or malfunction in the production system, the liquid mixture mainly composed of MCS collected from S50 can be sent to a flare for combustion to eliminate safety hazards.

[0077] S70. The DCS mixture, mainly composed of DCS and MCS, collected from the top of the column in S30, is returned to the fixed-bed reactor 500 in S10 for DCS disproportionation reaction. After returning, the DCS mixture can continue to participate in the disproportionation reaction and subsequent processes according to the production process flow, thereby making full use of the DCS and MCS in the by-products and intermediate products for disproportionation reaction to produce silane gas.

[0078] Example 2

[0079] In the above embodiments, the crude SiH4 product obtained in steps S20 and S40 can be extracted in the gas phase through the gas phase pipeline at the top of the primary separation tower 200 and the reactive distillation tower 600; or it can be extracted in the liquid phase after being condensed by the liquid phase pipeline of the condenser 101 at the top of the primary separation tower 200 and the reactive distillation tower 600. In order to reduce impurities and improve the purity of the crude SiH4 product, another production method is proposed in the second embodiment.

[0080] Please see Figure 1 , Figure 2 The difference between the second embodiment and the first embodiment is that the crude SiH4 products of SiH4 and MCS collected in S20 and S40 are liquid products after condensation and liquefaction. The method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column in the second embodiment uses the following steps instead of step S50 in the above embodiments:

[0081] S52. The crude SiH4 liquid product collected in S20 and S40 is purified by distillation, and a high-purity SiH4 gaseous or liquid product is collected from the top of the purification tower 400, and a liquid mixture with MCS as the main component is collected from the bottom of the purification tower 400. This step can directly perform distillation purification to collect a high-purity SiH4 gaseous or liquid product, as well as a liquid mixture with MCS as the main component.

[0082] Example 3

[0083] Please see Figure 2 Based on the production methods described in the above embodiments, the third embodiment provides a silane gas production system based on these methods. This silane gas production system can simultaneously utilize the DCS and TCS byproducts of the modified Siemens process to produce silane gas, changing the original silane gas production mode, enhancing process flexibility and feedstock adaptability, and improving the overall conversion rate while reducing operating energy consumption. This silane gas production system mainly includes: a fixed-bed reactor 500, a primary separation tower 200, a secondary separation tower 300, and a reactive distillation tower 600, etc.

[0084] like Figure 2As shown, the fixed-bed reactor 500 is a reaction device for DCS feedstock, equipped with a DCS inlet 510, which allows DCS feedstock to be introduced for DCS disproportionation reaction to produce a one-step disproportionation product. The main component of the DCS feedstock is DCS, a byproduct of the modified Siemens process, enabling the silane gas production system of this embodiment to handle surplus DCS that is difficult to process in the modified Siemens process. The fixed-bed reactor 500 uses a bottom-in, top-out feeding method, with the DCS inlet 510 located at its bottom. The fixed-bed reactor 500 is filled with catalyst to form a fixed bed. Reactants can flow continuously through the fixed bed, while the catalyst in the fixed bed remains stationary for catalysis. The main reaction formula for the DCS disproportionation reaction is:

[0085] SiH2Cl2→SiH4+SiHCl3;

[0086] During the reaction, the temperature in the fixed-bed reactor 500 is preferably maintained between 30°C and 80°C, and the pressure is preferably maintained between 20 and 35 bar. The main products of the one-step disproportionation reaction include SiH4, TCS, and MCS and DCS produced by secondary reactions.

[0087] The primary separation column 200 is a device for separating the one-step disproportionation products. Connected to the outlet of the fixed-bed reactor 500, it can perform distillation separation of the one-step disproportionation products. The top outlet of the primary separation column 200 is used to collect crude SiH4, while the bottom outlet is used to collect the chlorosilane mixture. The primary separation column 200 mainly separates the crude SiH4 product. During distillation, the temperature inside the primary separation column 200 is preferably maintained between -35°C and -15°C, and the pressure is preferably maintained between 20 and 30 bar. The crude SiH4 collected from the top of the column mainly consists of high-purity SiH4 with trace amounts of MCS. Because the disproportionation reaction takes place in the fixed-bed reactor 500, while the distillation separation takes place in the primary separation column 200, the inclusion of excessive DCS feedstock in the crude SiH4 is avoided, saving energy consumption in the distillation separation. The chlorosilane mixture collected from the bottom of the column mainly consists of MCS, DCS, TCS, and trace amounts of STC. Furthermore, a condenser 101 is installed at the top of the primary separation tower 200. The top outlet of the condenser 101 is divided into a gas phase pipeline and a liquid phase pipeline. The gas phase pipeline connects to the top of the primary separation tower 200 and is used to collect the crude SiH4 gas phase. The liquid phase pipeline connects to the condenser 101 at the top of the primary separation tower 200 and is used to collect the crude SiH4 liquid phase. The remaining liquid phase in the condenser 101 flows back into the top of the tower, achieving the fractional distillation separation of the components and achieving the desired separation effect. Simultaneously, a reboiler 103 is installed below the bottom of the primary separation tower 200. The reboiler 103 provides a heat source for the primary separation tower 200. The liquid phase material in the bottom of the tower enters the reboiler 103, is heated and vaporized, and returns to the bottom of the tower, providing sufficient gas phase flow to the tower, thereby achieving the fractional distillation separation of the components.

[0088] The secondary separation column 300 is a separation device for the chlorosilane mixture collected from the bottom of the primary separation column 200. The secondary separation column 300 is connected to the bottom outlet of the primary separation column 200 and can perform distillation to separate the chlorosilane mixture. The top outlet of the secondary separation column 300 is used to collect the DCS mixture, and the bottom outlet is used to collect the TCS mixture. The secondary separation column 300 is mainly used to separate the TCS mixture, which is then added to the subsequent TCS disproportionation reaction. During the distillation process, the temperature inside the secondary separation column 300 is preferably maintained between 40°C and 70°C, and the pressure is preferably maintained between 5 and 10 bar. The DCS mixture collected from the top mainly consists of DCS and MCS, while the chlorosilane mixture collected from the bottom mainly consists of TCS and trace amounts of STC. Furthermore, a condenser 101 is also installed at the top of the secondary separation tower 300, but only a liquid phase pipeline is installed at the top discharge end of the tower. The liquid phase pipeline connects to the condenser 101 at the top of the secondary separation tower 300 for collecting the liquid phase DCS mixture. Another portion of the liquid phase in the condenser 101 flows back into the top of the tower to achieve the fractional distillation separation of the components and achieve the desired separation effect. At the same time, a reboiler 103 is also installed below the bottom of the secondary separation tower 300. The reboiler 103 provides a heat source for the secondary separation tower 300. After the liquid phase material in the bottom of the tower enters the reboiler 103, it is heated and vaporized and returned to the bottom of the tower, providing sufficient gas phase stream for the tower, thereby achieving the fractional distillation separation of the components.

[0089] The reactive distillation column 600 is a device that organically combines a reactor and a distillation column, serving as both the reaction equipment and the distillation separation equipment for TCS. Simultaneously, the reactive distillation column 600 is connected to the bottom outlet of the secondary separation column 300, allowing the introduction of a TCS mixture, and is equipped with a TCS inlet 610 for introducing TCS feedstock. Furthermore, the reactive distillation column 600 can perform a TCS disproportionation reaction using TCS as feedstock and separate the products through distillation. The top outlet of the reactive distillation column 600 is used to collect crude SiH4, while the bottom outlet is used to collect STC byproducts. The main component of the TCS feedstock is TCS, an intermediate product of the modified Siemens process, enabling the silane gas production system of this embodiment to provide a new application for TCS in silane gas production. The TCS mixture originates from the output of the secondary separation column 300, ensuring the full utilization of this byproduct. Meanwhile, the reactive distillation column 600 is equipped with a catalyst reaction section 620, a rectification section 630, and a stripping section 640. The catalyst packed in the catalyst reaction section 620 can both promote the disproportionation reaction and serve as packing material in the rectification column, providing a site for mass and heat transfer between the gas and liquid phases, thus achieving component separation. The main reaction formula for the TCS disproportionation reaction is:

[0090] SiHCl3 → SiH2Cl2 + SiCl4 (First disproportionation reaction)

[0091] SiH₂Cl₂ → SiH₄ + SiHCl₃. (Second disproportionation reaction)

[0092] During the reaction, the temperature inside the reactive distillation column 600 is preferably maintained between -100℃ and -50℃, and the pressure is preferably maintained between 1 and 7 bar. The two-step disproportionation products mainly include SiH4, STC, and MCS produced by the secondary reaction. The rectification section 630 is located above the catalyst reaction section 620. The rectification section 630 contains a distillation unit (plate or packing) and, under constant pressure and temperature control, purifies and separates the gas mixture that moves upward after the reaction in the catalyst reaction section 620. The gas mixture being processed mainly consists of SiH4, but may also contain small amounts of MCS. The rectification section 630 is mainly used to remove the heavy components from SiH4, liquefying and refluxing them, while the crude SiH4 containing trace amounts of MCS enters the top of the column in the gas phase. The stripping section 640 is located below the catalyst reaction section 620. The stripping section 640 contains a stripper (plates or packing) to purify and separate the liquid mixture that moves downwards after the reaction in the catalyst reaction section 620 under constant pressure and temperature control. The main components of the liquid mixture are STC, unreacted TCS, and a small amount of DCS. The stripping section 640 is mainly used to evaporate and elevate the unreacted TCS and a small amount of DCS to the upper section of the reactive distillation column 600, allowing them to continue participating in the reaction, while STC enters the bottom of the column as a liquid phase. After component separation, crude SiH4 is collected at the top of the column. The main component of the crude SiH4 product is also high-purity SiH4, with trace amounts of MCS. The STC byproduct is collected at the bottom of the column and can be returned to the modified Siemens process production system as a feedstock for chlorosilane production. Furthermore, the top and bottom products of the reactive distillation column 600 are collected simultaneously during the reaction process. The timely removal of SiH4 and STC products from the top and bottom of the column facilitates the forward reaction of TCS disproportionation, thereby improving its conversion rate. Additionally, a condenser 101 is installed at the top of the reactive distillation column 600. Its top outlet is divided into a gas phase pipeline and a liquid phase pipeline. The gas phase pipeline connects to the top of the reactive distillation column 600 for collecting the crude SiH4 in the gas phase; the liquid phase pipeline connects to the condenser 101 at the top of the reactive distillation column 600 for collecting the crude SiH4 in the liquid phase. The remaining liquid phase in the condenser 101 flows back into the top of the column, achieving component distillation separation and obtaining the desired separation effect. Meanwhile, a reboiler 103 is also installed below the bottom of the reactive distillation column 600. The reboiler 103 provides a heat source for the reactive distillation column 600. After the liquid material in the bottom of the column enters the reboiler 103, it is heated and vaporized and returned to the bottom of the column, providing sufficient gaseous material in the column, thereby realizing the distillation separation of components.

[0093] In summary, in this embodiment, the silane gas production system uses a fixed-bed reactor 500 and two-stage separation towers for DCS disproportionation and distillation separation. On one hand, it leverages the high conversion rate and low degree of reverse reaction of DCS disproportionation, saving energy through the fixed-bed reactor 500. On the other hand, considering the close boiling points of DCS feedstock and product, separating the reaction space and distillation space reduces the DCS impurity content in the crude SiH4 product. Simultaneously, the reactive distillation tower 600 performs both TCS reaction and distillation, maximizing the forward direction of the reversible TCS disproportionation reaction, thus increasing the TCS conversion rate and overall conversion rate while reducing operating energy consumption. This synergistic approach of using two disproportionation processes—a fixed-bed reactor and reactive distillation—solves the problems of high energy consumption and low conversion rate in existing silane gas production processes.

[0094] like Figure 2 As shown, in order to reduce the hydrogen and light component impurities that are easily carried in the DCS feedstock, the silane gas production system of this embodiment also includes a degassing tower 100. The feed end of the degassing tower 100 is used to introduce the DCS feedstock, and the discharge end of the degassing tower 100 is connected to the DCS feed port 510 of the fixed bed reactor 500. The degassing tower 100 is mainly used for light component purification, desorbing the hydrogen dissolved in the DCS feedstock, removing light component impurities and hydrogen, and finally collecting it from the tower bottom into the fixed bed reactor 500. Furthermore, a condenser 101 is also installed at the top of the degassing tower 100, but only a gas phase pipe is installed at the top discharge end of the tower. The gas phase pipe is connected to the condenser 101 at the top of the degassing tower 100 to discharge light component impurities in a non-condensable state. The condenser 101 mainly provides liquid phase reflux to the top of the degassing tower 100. By providing liquid phase reflux for gas-liquid contact, mass transfer, and heat transfer to the degassing tower 100, the purification and impurity removal effect of DCS raw materials is achieved. At the same time, a reboiler 103 is also installed below the bottom of the degassing tower 100. The reboiler 103 is used to provide a heat source for the degassing tower 100 and to provide gas phase flow into the tower, which facilitates the desorption of hydrogen and light component impurities dissolved in the liquid phase and ensures the quality of the material taken out of the bottom of the tower. In addition, during operation, the temperature for removing light components and impurities in the degassing tower 100 is preferably maintained between 15°C and 50°C, and the pressure is preferably maintained between 2 and 7 bar.

[0095] Meanwhile, in this embodiment, the crude SiH4 product obtained from the primary separation tower 200 and the reactive distillation tower 600 can be extracted in the gas phase through the gas phase pipeline at the top of the primary separation tower 200 and the reactive distillation tower 600; or it can be extracted in the liquid phase after condensation treatment by the liquid phase pipeline of the condenser 101 at the top of the primary separation tower 200 and the reactive distillation tower 600. In order to reduce impurities and improve the purity of SiH4 product, the silane gas production system of this embodiment also includes an adsorption device 700 and a purification tower 400, etc.

[0096] The adsorption device 700 is simultaneously connected to the gas phase pipeline at the top output end of the primary separation tower 200 and the reactive distillation tower 600, allowing crude SiH4 product in the gas phase to be introduced. The adsorption device 700 is filled with adsorbent, mainly including adsorption resin or activated carbon, which can adsorb and remove impurities from the crude SiH4 product in the gas phase, mainly including B, P and metal impurities.

[0097] The purification tower 400 is simultaneously connected to the liquid phase pipelines at the top output ends of the primary separation tower 200 and the reactive distillation tower 600, as well as the discharge end of the adsorption unit 700, for distillation removal of heavy components and impurities containing MCS from crude SiH4. Depending on product requirements, the purification tower 400 can be switched to connect directly to the liquid phase pipelines at the top output ends of the primary separation tower 200 and the reactive distillation tower 600, allowing direct introduction of liquid-phase crude SiH4; or it can be connected to the adsorption unit 700, allowing the introduction of gas-phase crude SiH4 after adsorption and impurity removal. Furthermore, the purification tower 400 has a first SiH4 discharge end 401, a second SiH4 discharge end 402, and an MCS discharge end 403, etc. The first SiH4 discharge end 401 is connected to the liquid phase pipeline of the condenser 101 at the top of the purification tower 400, and is used to collect high-purity SiH4 in liquid phase. The condenser 101 is used to liquefy the gaseous SiH4 product at the top of the tower. Through the liquid phase pipeline of the condenser 101, part of the liquid flows back to the top of the tower, and the other part is collected as liquid SiH4 product. The second SiH4 discharge end 402 is connected to the side of the purification tower 400, and can be used to collect high-purity SiH4 product in gas phase when needed. At the same time, the MCS discharge end 403 is connected to the liquid connection pipeline between the bottom of the purification tower 400 and the reboiler 103 below the bottom, and is used to collect heavy components and impurities containing MCS in liquid phase. In addition, during use, the temperature inside the purification tower 400 is preferably maintained between -50°C and -15°C, and the pressure is preferably maintained between 20 and 30 bar.

[0098] Furthermore, to fully utilize the byproducts of the production system in this embodiment, the MCS discharge end 403 of the purification tower 400 is connected to the feed end of the secondary separation tower 300 in the silane gas production system of this embodiment. The liquid mixture with MCS as its main component, collected from the bottom of the purification tower 400, can be returned to the secondary separation tower 300 for further distillation and separation. After returning, it continues to undergo distillation and separation and subsequent processes according to the production process flow, thereby fully utilizing the MCS in the byproducts for disproportionation reaction to produce silane gas. Additionally, when no reinjection is performed, or in case of an emergency malfunction in the production system, the purification tower 400 is also connected to a flare tail gas treatment device. The liquid mixture with MCS as its main component, collected from the purification tower 400, can be transported to the flare for combustion treatment to eliminate safety hazards. Simultaneously, the liquid phase pipeline at the top output of the secondary separation tower 300 is connected to the feed end of the degassing tower 100 and the DCS feed port 510 of the fixed-bed reactor 500. This allows the DCS mixture, mainly composed of DCS and MCS, collected from the top of the secondary separation tower 300, to be returned to the fixed-bed reactor 500 for DCS disproportionation. After returning, it continues to participate in the disproportionation reaction and subsequent processes according to the production process flow, thereby fully utilizing the DCS and MCS in the byproducts for disproportionation to produce silane gas.

[0099] In addition, in this embodiment, a first booster pump 810 is installed on the connecting pipeline between the discharge end of the degassing tower 100 and the DCS inlet 510 of the fixed bed reactor 500; a second booster pump 820 is installed on the connecting pipeline between the liquid phase pipeline at the top output end of the secondary separation tower 300 and the DCS inlet 510 of the fixed bed reactor 500; a compressor 830 is installed on the connecting pipeline between the gas phase pipeline at the top output end of the reactive distillation tower 600 and the inlet end of the adsorption device 700; and a third booster pump 840 is installed on the connecting pipeline between the liquid phase pipeline at the top output end of the reactive distillation tower 600 and the inlet end of the purification tower 400. Both the compressor and the booster pumps are used to enable the material to overcome the pressure difference and enter the high-pressure equipment from the low-pressure equipment.

[0100] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column, characterized in that, Include: S10. Using DCS feedstock, a DCS disproportionation reaction is carried out in a fixed-bed reactor (500) to obtain a one-step disproportionation product; S20. The one-step disproportionation product obtained in S10 is separated by distillation in a primary separation column (200). Crude SiH4 is collected at the top of the column, and a mixture of chlorosilanes is collected at the bottom of the column. S30. The chlorosilane mixture collected from the bottom of column S20 is separated by distillation in a secondary separation column (300), and the TCS mixture is collected from the bottom of the column; S40. Using TCS raw material and the TCS mixture collected from the bottom of column S30, a TCS disproportionation reaction is carried out together in a reactive distillation column (600), and the product is separated by distillation, and crude SiH4 is collected at the top of the column. S50. The crude SiH4 product in gas phase collected from S20 and S40 is adsorbed and purified by an adsorption device (700), and then purified by distillation in a purification tower (400). The SiH4 product is collected from the top of the purification tower (400), and the liquid mixture with MCS as the main component and impurities are collected from the bottom of the purification tower (400).

2. The method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column as described in claim 1, characterized in that, The DCS raw material mentioned in S10 includes DCS, a byproduct of the modified Siemens process; the TCS raw material mentioned in S40 includes TCS, an intermediate product of the modified Siemens process.

3. The method for producing silane gas by combining a fixed-bed reactor and a reactive distillation column as described in claim 1, characterized in that, Also includes: S52. The crude liquid SiH4 product collected in S20 and S40 is purified by distillation in a purification tower (400). The SiH4 product is collected from the top of the purification tower (400), and the liquid mixture with MCS as the main component and impurities are collected from the bottom of the purification tower (400).

4. The method for producing silane gas by combining a fixed-bed reactor with a reactive distillation column as described in claim 3, characterized in that, The S30 includes: collecting the DCS mixture at the top of the column; the method for producing silane gas by combining the fixed-bed reactor with the reactive distillation column further includes: S60. The liquid mixture with MCS as the main component collected from the bottom of the purification tower (400) in S50 or S52 is returned to the secondary separation tower (300) in S30 for further distillation and separation. S70. The DCS mixture collected from the top of the column in S30 is returned to the fixed-bed reactor (500) in S10 for DCS disproportionation reaction.

5. A silane gas production system, characterized in that, Include: The fixed-bed reactor (500) is equipped with a DCS feed inlet (510) and is capable of performing DCS disproportionation reaction to obtain a one-step disproportionation product. The primary separation tower (200) is connected to the outlet end of the fixed bed reactor (500) and can distill and separate the one-step disproportionation product. The top outlet end of the primary separation tower (200) is used to collect crude SiH4, and the bottom outlet end is used to collect a mixture of chlorosilanes. A secondary separation column (300), connected to the bottom outlet of the primary separation column (200), is capable of distilling and separating the chlorosilane mixture, and the bottom outlet of the secondary separation column (300) is used to collect the TCS mixture; and The reactive distillation column (600) is connected to the bottom outlet of the secondary separation column (300) and is equipped with a TCS inlet (610). It can carry out TCS disproportionation reaction and separate the product by distillation. The top outlet of the reactive distillation column (600) is used to collect crude SiH4. Also includes: The adsorption device (700) is connected to the gas phase pipeline at the top output end of the primary separation tower (200) and the reactive distillation tower (600). The adsorption device (700) can adsorb and remove impurities from the crude SiH4 product in the gas phase. and The purification tower (400) is connected to the liquid phase pipeline at the top output end of the primary separation tower (200) and the reactive distillation tower (600) or to the discharge end of the adsorption device (700). The purification tower (400) can distill and remove heavy components and impurities containing MCS from crude SiH4.

6. The silane gas production system as described in claim 5, characterized in that, It also includes a degassing tower (100); the feed end of the degassing tower (100) is used to introduce DCS raw materials, and its discharge end is connected to the DCS feed port (510) of the fixed bed reactor (500). The degassing tower (100) can perform delighting and purification of DCS raw materials.

7. The silane gas production system as described in claim 5, characterized in that, The MCS discharge end (403) of the purification tower (400) is connected to the feed end of the secondary separation tower (300), so that the liquid mixture with MCS as the main component collected from the bottom of the purification tower (400) can be returned to the secondary separation tower (300) for distillation and separation.

8. The silane gas production system as described in claim 5, characterized in that, The secondary separation tower (300) is equipped with a liquid phase pipeline at the top of the tower for collecting the DCS mixture and connecting it to the DCS inlet (510) of the fixed bed reactor (500). The DCS mixture collected from the top of the secondary separation tower (300) can be returned to the fixed bed reactor (500) for DCS disproportionation reaction.

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