Process for cyclic production of trichlorosilane

Abstract

The present invention provides a process for cyclic production of trichlorosilane, which relates to the technical field of fine chemical engineering. The hydrogen chloride used in the preparation of trichlorosilane in the present invention is the hydrogen chloride gas which is a by-product of the alcoholysis and esterification reaction of chlorosilane. After the by-product hydrogen chloride gas is purified by spraying, it reacts with silicon powder at a specific fluidization temperature and pressure difference. The synthesized gas after the reaction is dust-removed and condensed to obtain trichlorosilane crude product with high content and tail gas, and the hydrogen chloride content in the tail gas is low. The present invention enables the effective cyclic use of chlorine element in the production, saves energy consumption, can reduce the production cost, reduce environmental pollution and realize green production.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, and particularly relates to a process for cyclic production of trichlorosilane products. Background Art

[0002] Trichlorosilane is one of the chlorosilanes and is the most basic raw material in industries such as organosilicon and silicon materials. Trichlorosilane can be used to produce silanes. For example, trichlorosilane reacts with methanol (ethanol) to produce trimethoxy (ethoxy) silane, which is one of the raw materials for synthesizing silanes such as vinyltrimethoxy (ethoxy) silane, 3-methacryloxypropyltrimethoxy (ethoxy) silane, and 2,3-epoxypropoxypropyltrimethoxy (ethoxy) silane. Trichlorosilane can also be used as a modification material for silicone oil by addition reaction with vinyl silicone oil. Trichlorosilane can also be added to substances containing unsaturated groups such as alkenes and alkynes, such as allyl chloride and octene, to obtain other chlorosilanes, and the chlorosilanes are then reacted with methanol, ethanol, ethylene glycol monomethyl ether, etc. to produce a series of silanes. Trichlorosilane can also be used as the main raw material for producing polysilicon, a photovoltaic material.

[0003] With the rapid development of the organosilicon new material and photovoltaic industries in recent years, the market demand for trichlorosilane has been increasing. China, as the main production area of trichlorosilane, accounts for more than one-third of the global trichlorosilane production. The trichlorosilane production capacity of major Chinese manufacturers is about 600,000 tons, and there are also trichlorosilane manufacturers under construction or expansion. It is expected that by 2025, the market demand for trichlorosilane will reach 1 million tons.

[0004] There are mainly three industrial synthesis and production routes for trichlorosilane:

[0005] 1) Hydrogen chloride route: Hydrogen chloride gas directly or together with other raw materials enters a fluidized bed and reacts with silicon powder under certain conditions to produce trichlorosilane, such as in CN87100535, CN101445245, CN102030334, CN102040223, CN102530958, CN106915747, CN107619051. The trichlorosilane produced by this route is mainly used as a raw material for silane coupling agents.

[0006] 2) Silicon tetrachloride route: Silicon tetrachloride reacts with one or more of hydrogen chloride, hydrogen, silicon powder, and dichlorosilane under certain conditions to produce trichlorosilane, such as in patent documents CN101905888, CN101941702, CN102502656, CN103723733, CN105980305, CN107572534, CN113387361, CN11521534, etc. The trichlorosilane produced by this process is mostly used in the production of polysilicon.

[0007] 3) The reaction of hydrogen with hexachlorodisilane to produce trichlorosilane has low industrial value as disclosed in the synthetic route of patent document CN106882809.

[0008] Among them, there are mainly two sources of hydrogen chloride gas in the industrial synthesis of trichlorosilane by the hydrogen chloride route: one is from the reaction of chlorine and hydrogen, which has high requirements for equipment, safety and environmental protection and high costs; the other is from the desorption of saturated hydrogen chloride aqueous solution (hydrochloric acid). This method is simple, but the desorbed hydrogen chloride gas contains trace amounts of water. The water-containing hydrogen chloride not only corrodes pipelines and equipment, reduces the conversion rate of trichlorosilane from silicon powder, but also significantly reduces the service life of the equipment. Therefore, the desorbed hydrogen chloride must be dried. In industry, concentrated sulfuric acid is mostly used as a water absorbent to absorb the trace water in the hydrogen chloride gas, but this significantly increases the process difficulty, especially the used water absorbent, which is difficult to treat and has high treatment costs. Therefore, it is necessary to develop a new synthetic route for trichlorosilane. Summary of the Invention

[0009] Based on this, it is necessary to provide a process method for cyclic production of trichlorosilane products, which can effectively recycle chlorine elements in production, save energy consumption, reduce production costs, reduce environmental pollution and achieve green production.

[0010] Through a large number of investigations, the inventor team found that: silane production enterprises will generate a large amount of by-product hydrogen chloride every year. For every 1 ton of silane produced, about 0.8 tons of hydrogen chloride gas (hydrochloric acid) is generated, and most industries use falling film absorption to produce 2.4 tons of hydrochloric acid. Calculated based on the domestic silane production capacity of 1 million tons, 2.4 million tons of hydrochloric acid need to be treated. A small part of this hydrochloric acid is directly used as an industrial raw material, and most of it needs to be processed by chlor-alkali companies, which requires a large amount of energy consumption and costs and also causes certain pollution to the environment. How to effectively utilize the by-product hydrogen chloride gas in the silane production process is an urgent problem to be solved.

[0011] In addition, the process conditions for the industrial synthesis of trichlorosilane by the hydrogen chloride route are generally as follows: the fluidization temperature is 300 - 360 °C, the pressure difference between the lower and upper pressures of the fluidized bed is 32 - 38 KPa. The particle size of the pulverized powder and the hydrogen chloride content in the tail gas are not controlled. It is reported that the content of crude trichlorosilane after the fluidization reaction is 75% - 88%, and the content of industrial crude trichlorosilane is generally 83% - 86%. The other components are mainly dichlorodihydrogen silane and silicon tetrachloride. Since the raw material hydrogen chloride contains impurities such as methanol, ethanol, and chloromethane, the synthesized crude trichlorosilane also contains methyldichlorosilane, methyltrichlorosilane, ethyltrichlorosilane, etc. In this regard, it is necessary to further increase the content of trichlorosilane in the industrial crude trichlorosilane.

[0012] The present invention adopts the following technical solutions:

[0013] The present invention provides a process for cyclic production of trichlorosilane, comprising the following steps: subjecting chlorosilane A to alcoholysis esterification reaction to obtain silane and by-product hydrogen chloride gas; spraying and purifying the by-product hydrogen chloride gas with chlorosilane B to obtain the reaction material at the bottom of the spraying tower containing chlorosilane B and the hydrogen chloride gas after spraying and purification, and mixing or replacing chlorosilane A with the reaction material at the bottom of the spraying tower containing chlorosilane B for cyclic preparation of by-product hydrogen chloride gas; respectively inputting silicon powder and the hydrogen chloride gas after spraying and purification into a fluidized bed reactor for reaction to obtain synthesis gas; performing dust removal and condensation on the synthesis gas to obtain crude fluidized trichlorosilane and tail gas; and subjecting the crude fluidized trichlorosilane to rectification to obtain trichlorosilane.

[0014] Among them, the spraying and purification is used to remove trace silane, water and alcohol carried in the by-product hydrogen chloride gas.

[0015] In some embodiments, the flow rate of the hydrogen chloride gas after spraying and purification entering the fluidized bed reactor is controlled at 1800 - 2200 m 3 / h, and the particle size of the silicon powder is 50 mesh - 140 mesh. The temperature at the bottom of the fluidized bed reactor is controlled at 290°C - 295°C, and the pressure difference between the lower part and the upper part of the fluidized bed reactor is 41 KPa - 43 KPa, so that the content of trichlorosilane in the crude fluidized product is not less than 90%, and the content of hydrogen chloride in the tail gas is less than 5%.

[0016] In some embodiments, the content of trichlorosilane in the crude fluidized product is 90% - 93%.

[0017] In some embodiments, chlorosilane A and chlorosilane B are selected from at least one of trichlorosilane, tetrachlorosilane, methyldichlorosilane, methyltrichlorosilane, chloropropyltrichlorosilane, chloropropylmethyldichlorosilane, propyltrichlorosilane, propylmethyldichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, vinyltrichlorosilane.

[0018] In some embodiments, chlorosilane A and chlorosilane B are the same chlorosilane.

[0019] In some embodiments, the alcohol used in the alcoholysis esterification reaction is selected from at least one of methanol, ethanol, propanol, isopropanol.

[0020] Preferably, the outlet of the by-product hydrogen chloride gas of the alcoholysis esterification reaction equipment is directly connected to the inlet of the spraying and purification equipment.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1) The present invention realizes the effective utilization of by-product hydrogen chloride gas in the silane production process for the first time, which can not only solve the environmental protection problem, but also reduce the production cost of high-content trichlorosilane products.

[0023] 2) The present invention discovers that the by-product hydrogen chloride in the alcoholysis esterification reaction of chlorosilane carries trace amounts of silane, water, and alcohol. These trace impurities directly enter the fluidized bed reactor, where they can react with silicon powder at high temperatures to form a series of by-products, seriously affecting the quality of crude trichlorosilane. At the same time, more importantly, the trace alcohol in the by-product hydrogen chloride can directly react to form water and chloroalkane. The water directly entering the fluidized bed will seriously corrode the equipment, reduce the service life of the equipment, and pose a safety hazard. Using the same esterified chlorosilane to wash and purify its by-product hydrogen chloride, the silane, water, and alcohol carried by the by-product hydrogen chloride can be washed, reacted, and adsorbed. The alcohol reacts with the esterified chlorosilane to form silane and hydrogen chloride. The silane can be directly sold as a product and can be used in industries such as coatings, rubber, and filler treatment, and can also be used as a raw material for other functional silanes. The generated hydrogen chloride by-product enters the fluidized bed as a purification raw material, improving the utilization rate of chlorine. This purification process removes substances such as alcohol, water, and silane from the by-product hydrogen chloride without generating new impurities, ensuring the quality of crude trichlorosilane. At the same time, the esterified chlorosilane used for purification can be continuously replenished and overflowed simultaneously. The liquid material overflowing from the bottom undergoes alcoholysis esterification to form silane and by-product hydrogen chloride, and the material forms a closed-loop production.

[0024] 3) The present invention preferably arranges a circulating spray tower closely following the alcoholysis esterification reaction equipment, allowing materials such as alcohol and silane entrained in the by-product hydrogen chloride generated by esterification to enter the circulating spray tower for purification in a timely manner, avoiding the reaction of the by-product hydrogen chloride generated by esterification and the entrained alcohol in the pipeline or equipment to form water and chloroalkanes. Chloroalkanes are gases that are not easily purified. After entering the fluidized bed together with the by-product hydrogen chloride, they will react with silicon powder to form alkylchlorosilanes, affecting the quality of crude trichlorosilane.

[0025] 4) The present invention preferably controls the temperature range at the bottom of the fluidized bed, which can improve the conversion rate of trichlorosilane and reduce side reactions.

[0026] 5) The present invention preferably controls the mesh number of the raw material silicon powder, which can improve the reaction efficiency, reduce the consumption of silicon powder, and lower the production cost. If the mesh number is too large, the silicon powder is easily carried into the dust removal device by the fluidized synthesis gas and enters the subsequent process for treatment. If the mesh number is too small, the reaction is incomplete, the reaction efficiency is reduced, and silicon slag will be formed, reducing the service efficiency and life of the fluidized bed.

[0027] 6) The present invention preferably controls the flow rate of inlet hydrogen chloride and the pressure difference between the lower and upper pressures of the fluidized bed reactor to ensure the fluidization time of hydrogen chloride, which can improve the production capacity and yield.

[0028] 7) The present invention preferably controls the content of hydrogen chloride in the tail gas, ensures the conversion rate of hydrogen chloride in the intake gas, reduces the load of pressure swing adsorption in the subsequent process, reduces the recycle amount of hydrogen chloride, saves energy consumption, and improves production capacity.

[0029] 8) In the present invention, it is preferred that the liquid containing chlorosilane material in the circulating spray tower is the same chlorosilane material undergoing esterification reaction, with continuous feeding and overflow, without introducing and generating new impurities, which not only ensures the purification of hydrogen chloride gas but also ensures the continuity of the purification and alcoholysis esterification processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a simplified process flow diagram for the cyclic production of trichlorosilane products with high content. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be further described in detail below in conjunction with specific embodiments, so that those skilled in the art can understand the present invention more clearly.

[0032] The following embodiments are only used to illustrate the present invention, but not to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present invention.

[0033] In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well-known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well-known to those skilled in the art.

[0034] As Figure 1 shown, a process method for cyclic production of trichlorosilane products with high content (not less than 90%) includes the following steps:

[0035] S1, Alcoholysis and esterification reaction of chlorosilane is carried out to obtain silane products and by-product hydrogen chloride gas.

[0036] In this step, the alcohol used in the alcoholysis and esterification reaction is preferably at least one of methanol, ethanol, propanol, and isopropanol. Trace amounts of silane, alcohol, water, etc. are carried in the by-product hydrogen chloride and need to be further purified.

[0037] S2, The by-product hydrogen chloride gas generated in step S1 is directly fed into a circulating spray tower (the by-product hydrogen chloride gas outlet of the alcoholysis and esterification reaction equipment is directly connected to the intake port of the spray purification equipment), and spray purification is carried out using chlorosilane to obtain the reaction material at the bottom of the chlorosilane spray tower and the spray-purified hydrogen chloride gas.

[0038] In this step, the reaction materials at the bottom of the chlorosilane spray tower are further recycled for reaction to prepare by-product hydrogen chloride gas by mixing or substituting the chlorosilane in step S1, so as to achieve recycling.

[0039] S3. Input silicon powder and the purified hydrogen chloride gas after spraying into a fluidized bed reactor for reaction to obtain synthesis gas.

[0040] In this step, preferably, the flow rate of the purified hydrogen chloride gas entering the fluidized bed reactor is controlled at 1800 - 2200 m 3 / h, and the particle size of the silicon powder is 50 - 140 mesh. The temperature at the bottom of the fluidized bed reactor is controlled at 290°C - 295°C, and the pressure difference between the lower part and the upper part of the fluidized bed reactor is 41 KPa - 43 KPa.

[0041] S4. Dust-remove and condense the synthesis gas to obtain crude trichlorosilane in fluidized state and tail gas. The content of trichlorosilane in the crude trichlorosilane in fluidized state is not less than 90%; the content of hydrogen chloride in the tail gas is less than 5%.

[0042] A small amount of silicon powder will be carried into the synthesis gas, and these silicon powders must be dust-removed. First, cyclone dust removal is adopted. Most of them are recovered and used as raw materials in the fluidized bed, and a small part is treated by wet dust removal and then sent to the three wastes treatment together with high-boiling substances. Without the dust removal process, the pipeline will be blocked. The tail gas adopts PSA pressure swing adsorption technology. The main components of the tail gas include: unreacted hydrogen chloride (generally required to be less than 10%, more than 10% has a great impact on PSA pressure swing adsorption), reaction by-product hydrogen (50%) and nitrogen supplemented in the system (40%). The tail gas is treated by two-stage PSA pressure swing adsorption. After the hydrogen chloride is recovered under pressure in the first stage, it directly enters the fluidized bed to participate in the reaction again. The high-purity hydrogen (99.99%) is recovered and sold in the second stage, and the nitrogen enters the three wastes treatment.

[0043] S5. Rectify the crude trichlorosilane in fluidized state to obtain trichlorosilane product.

[0044] Among them, the synthesis principle of trichlorosilane using the hydrogen chloride route is as follows:

[0045] Si + 3HCl → HSiCl3 + H2 (main reaction)

[0046] Si + 4HCl → SiCl4 + 2H2 (side reaction)

[0047] 2HSiCl3 → SiCl4 + H2SiCl2 (side reaction)

[0048] The process method for cyclic production of high-content (not less than 90%) trichlorosilane product can realize the effective recycling of chlorine element, solve the environmental protection problem, and at the same time reduce the production costs of silane and trichlorosilane, realizing green production.

[0049] Among them, the chlorosilane can be selected from at least one of trichlorosilane, silicon tetrachloride, methyldichlorosilane, methyltrichlorosilane, chloropropyltrichlorosilane, chloropropylmethyldichlorosilane, propyltrichlorosilane, propylmethyldichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, vinyltrichlorosilane.

[0050] The trichlorosilane product can undergo an addition reaction with an alkene to generate chloropropyltrichlorosilane, silicon tetrachloride, propyltrichlorosilane, octyltrichlorosilane, and dodecyltrichlorosilane. These chlorosilanes can respectively react with an alcohol to produce silane and hydrogen chloride. These chlorosilanes are all additives with industrial uses and can be sold directly or after further processing. Part of the chlorosilane is sent to the spray tower to purify hydrogen chloride, and the purified hydrogen chloride is used as a raw material for trichlorosilane in a recycle. The purified liquid reaction material in the spray tower can enter the alcoholysis esterification reactor together with the chlorosilane for recycling.

[0051] The following is an example for illustration:

[0052] Test equipment and its capacity indicators, etc.:

[0053] Spray tower: with a diameter of 1 meter, a height of 12 meters, a design pressure of 0.1 MPa, a design temperature of -35 °C, the equipment material is 16MnDR, and it is a plate tower.

[0054] Fluidized bed reactor: 30,000 tons / year per set, with a diameter of 1.8 meters, a height of 13 meters, a design pressure of 0.5 MPa, a design temperature of 280 - 350 °C, and the equipment material is Q345R / 20.

[0055] Example 1

[0056] This example provides a process method for circularly producing a high-content trichlorosilane product, which includes the following steps:

[0057] 1) Use the trichlorosilane product to carry out an alcoholysis esterification reaction with methanol to generate silane and by-product hydrogen chloride gas (entraining trace amounts of silane, water, and methanol).

[0058] 2) Continuously feed the trichlorosilane product into the circulating spray tower from the upper part at a flow rate of 100 kg / h, continuously input the by-product hydrogen chloride gas into the bottom of the circulating spray tower for spray purification. The hydrogen chloride gas purified by trichlorosilane flows out from the top of the tower, is condensed by -35 °C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0059] 3) The liquid material at the bottom of the spray tower is the reaction material of trichlorosilane with methanol and trace water in the by-product hydrogen chloride, including: trichlorosilane, trimethoxysilane and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction of trichlorosilane with methanol together with trichlorosilane at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas of silane is produced cyclically.

[0060] 4) From the purified hydrogen chloride gas storage tank, the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1800 - 2200 m 3 / h. The temperature at the bottom of the fluidized bed reactor is controlled at 290 - 295 °C, the pressure difference between the lower pressure and the upper pressure is 41 - 43 KPa, the particle size of the input silicon powder is 50 - 140 mesh, and the fluidization reaction is carried out to obtain the synthesis gas.

[0061] 5) The synthesis gas in step S4 is dust-removed (the dust removal amount is 25 kg / h) and condensed to obtain the crude trichlorosilane product from fluidization (the content of trichlorosilane is 91.2%) and the tail gas (the content of hydrogen chloride is 2%).

[0062] 6) The crude trichlorosilane product from fluidization is rectified to obtain the trichlorosilane product.

[0063] Example 2

[0064] This example provides a process method for cyclically producing a high-content trichlorosilane product, including the following steps:

[0065] 1) An alcoholysis esterification reaction is carried out between the trichlorosilane product and ethanol to generate silane and the by-product hydrogen chloride gas (entraining trace amounts of silane, water and ethanol).

[0066] 2) The trichlorosilane product is continuously pumped into the circulating spray tower from the upper part at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas is continuously input into the bottom of the circulating spray tower for spray purification. The hydrogen chloride gas purified by trichlorosilane flows out from the top of the tower, is condensed by -35 °C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0067] 3) The liquid material at the bottom of the spray tower is the reaction material of trichlorosilane with ethanol and trace water in the by-product hydrogen chloride, including: trichlorosilane, triethoxysilane and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction of trichlorosilane with ethanol together with trichlorosilane at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas of silane is produced cyclically.

[0068] 4) From the purified hydrogen chloride gas storage tank, the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1800 - 2200 m 3The gas with a flow rate of / h enters the fluidized bed reactor. The temperature at the bottom of the fluidized bed reactor is controlled at 290 - 295 °C, the pressure difference between the lower pressure and the upper pressure is 41 - 43 KPa, and the particle size of the input silicon powder is 50 - 140 mesh. Then a fluidization reaction is carried out to obtain synthesis gas.

[0069] 5) Dust removal and condensation are carried out on the synthesis gas in step S4 to obtain a crude trichlorosilane product in fluidization (the content of trichlorosilane is 92.4%) and tail gas (the content of hydrogen chloride is 3%).

[0070] 6) The crude trichlorosilane product in fluidization is rectified to obtain a trichlorosilane product.

[0071] Example 3

[0072] This example provides a process method for cyclic production of a high-content trichlorosilane product, including the following steps:

[0073] 1) Alcoholysis esterification reaction is carried out between chloropropyltrichlorosilane and ethanol to generate silane and by-product hydrogen chloride gas (entraining trace amounts of silane, water, and ethanol).

[0074] 2) Chloropropyltrichlorosilane is continuously fed into the circulating spray tower from the upper part at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas is continuously input into the bottom of the circulating spray tower for spray purification. The hydrogen chloride gas purified by chloropropyltrichlorosilane flows out from the top of the tower, is condensed by -35 °C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0075] 3) The liquid material at the bottom of the spray tower is the reaction material of ethanol and trace water in chloropropyltrichlorosilane and the by-product hydrogen chloride, including: chloropropyltrichlorosilane, chloropropyltriethoxysilane, and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction between chloropropyltrichlorosilane and ethanol at a flow rate of 100 kg / h to cyclically produce silane and by-product hydrogen chloride gas.

[0076] 4) From the purified hydrogen chloride gas storage tank, the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1800 - 2200 m 3 / h. The temperature at the bottom of the fluidized bed reactor is controlled at 290 - 295 °C, the pressure difference between the lower pressure and the upper pressure is 41 - 43 KPa, and the particle size of the input silicon powder is 50 - 140 mesh. Then a fluidization reaction is carried out to obtain synthesis gas.

[0077] 5) Dust removal and condensation are carried out on the synthesis gas in step S4 to obtain a crude trichlorosilane product in fluidization (the content of trichlorosilane is 92.1%) and tail gas (the content of hydrogen chloride is 3%).

[0078] 6) The crude trichlorosilane product in fluidization is rectified to obtain a trichlorosilane product.

[0079] Example 4

[0080] This example provides a process method for cyclically producing high-content trichlorosilane products, including the following steps:

[0081] 1) Alcoholysis esterification reaction is carried out between tetrachlorosilane and ethanol to generate silane and by-product hydrogen chloride gas (entraining trace amounts of silane, water, and ethanol).

[0082] 2) Tetrachlorosilane is continuously fed into the circulating spray tower from the upper part at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas is continuously input into the bottom of the circulating spray tower for spray purification. The hydrogen chloride gas purified by tetrachlorosilane flows out from the top of the tower, is condensed by -35°C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0083] 3) The liquid material at the bottom of the spray tower is the reaction material of tetrachlorosilane with ethanol and trace water in the by-product hydrogen chloride, including: trichlorosilane, tetraethoxysilane, and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction of tetrachlorosilane and ethanol at a flow rate of 100 kg / h to cyclically produce silane and by-product hydrogen chloride gas.

[0084] 4) From the purified hydrogen chloride gas storage tank, the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1800 - 2200 m 3 / h. The temperature at the bottom of the fluidized bed reactor is controlled at 290 - 295°C, the pressure difference between the lower pressure and the upper pressure is 41 - 43 KPa, and the particle size of the input silicon powder is 50 - 140 mesh for fluidized reaction to obtain synthesis gas.

[0085] 5) The synthesis gas in step S4 is dust-removed and condensed to obtain crude trichlorosilane in the fluidized state (the content of trichlorosilane is 91.6%) and tail gas (the content of hydrogen chloride is 4%)

[0086] 6) The crude trichlorosilane in the fluidized state is rectified to obtain trichlorosilane products.

[0087] Example 5

[0088] This example provides a process method for cyclically producing high-content trichlorosilane products, including the following steps:

[0089] 1) Alcoholysis esterification reaction is carried out between chloropropylmethyldichlorosilane and methanol to generate silane and by-product hydrogen chloride gas (entraining trace amounts of silane, water, and methanol).

[0090] 2) Continuously feed chloropropylmethyldichlorosilane into the circulating spray tower from the upper part at a flow rate of 100 kg / h, continuously input the by-product hydrogen chloride gas into the bottom of the circulating spray tower for spray purification. The hydrogen chloride gas purified by chloropropylmethyldichlorosilane flows out from the top of the tower, is condensed by -35°C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0091] 3) The liquid material at the bottom of the spray tower is the reaction material of chloropropylmethyldichlorosilane with methanol and trace water in the by-product hydrogen chloride, including: chloropropylmethyldichlorosilane, chloropropylmethyldimethoxysilane and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction of chloropropylmethyldichlorosilane with methanol at a flow rate of 100 kg / h together with chloropropylmethyldichlorosilane to recycle and produce by-product hydrogen chloride gas of silane.

[0092] 4) From the purified hydrogen chloride gas storage tank, feed the purified hydrogen chloride gas into the fluidized bed reactor at a flow rate of 1800 - 2200 m3 / h, control the temperature at the bottom of the fluidized bed reactor to be 290 - 295°C, the pressure difference between the lower pressure and the upper pressure to be 41 - 43 KPa, and the particle size of the input silicon powder to be 50 - 140 mesh for fluidized reaction to obtain synthesis gas.

[0093] 5) Dust removal and condensation are carried out on the synthesis gas in step S4 to obtain trichlorosilane fluidized crude product (the content of trichlorosilane is 92.3%) and tail gas (the content of hydrogen chloride is 2%).

[0094] 6) Rectify the trichlorosilane fluidized crude product to obtain trichlorosilane product.

[0095] Example 6

[0096] This example provides a process method for recycling and producing high-content trichlorosilane product, including the following steps:

[0097] 1) Carry out alcoholysis esterification reaction on vinyltrichlorosilane and ethanol to generate silane and by-product hydrogen chloride gas (entraining trace silane, a small amount of water and ethanol).

[0098] 2) Continuously feed vinyltrichlorosilane into the circulating spray tower from the upper part at a flow rate of 100 kg / h, continuously input the by-product hydrogen chloride gas into the bottom of the circulating spray tower for spray purification. The hydrogen chloride gas purified by vinyltrichlorosilane flows out from the top of the tower, is condensed by -35°C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0099] 3) The liquid material at the bottom of the spray tower is the reaction material of vinyltrichlorosilane with ethanol and trace water in the by-product hydrogen chloride, including: vinyltrichlorosilane, vinyltriethoxysilane and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction of chloropropylmethyldichlorosilane with ethanol together with vinyltrichlorosilane at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas of silane is produced cyclically.

[0100] 4) From the purified hydrogen chloride gas storage tank, the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1800 - 2200 m 3 / h. Control the temperature at the bottom of the fluidized bed reactor to 290 - 295 °C, the pressure difference between the lower pressure and the upper pressure is 41 - 43 KPa, and the particle size of the input silicon powder is 50 - 140 mesh, and carry out a fluidization reaction to obtain a synthesis gas.

[0101] 5) Dust removal and condensation are carried out on the synthesis gas in step S4 to obtain a crude product of fluidized trichlorosilane (the content of trichlorosilane is 92.6%) and tail gas (the content of hydrogen chloride is 2%).

[0102] 6) Rectify the crude product of fluidized trichlorosilane to obtain a trichlorosilane product.

[0103] Example 7

[0104] This example provides a process method for cyclically producing a high-content trichlorosilane product, including the following steps:

[0105] 1) Carry out an alcoholysis esterification reaction of dodecyltrichlorosilane with methanol to generate silane and by-product hydrogen chloride gas (entraining trace silane, a small amount of water and methanol).

[0106] 2) Continuously inject dodecyltrichlorosilane from the upper part into the circulating spray tower at a flow rate of 100 kg / h, continuously input the by-product hydrogen chloride gas into the bottom of the circulating spray tower, carry out spray purification, and the hydrogen chloride gas purified by dodecyltrichlorosilane flows out from the top of the tower, is condensed by -35 °C brine, and is pressed into the purified hydrogen chloride gas storage tank through a hydrogen chloride compressor.

[0107] 3) The liquid material at the bottom of the spray tower is the reaction material of dodecyltrichlorosilane with methanol and trace water in the by-product hydrogen chloride, including: dodecyltrichlorosilane, dodecyltrimethoxysilane and its oligomers. The material at the bottom of the spray tower continuously enters the alcoholysis esterifier for the reaction of dodecyltrichlorosilane with methanol together with dodecyltrichlorosilane at a flow rate of 100 kg / h, and the by-product hydrogen chloride gas of silane is produced cyclically.

[0108] 4) From the purified hydrogen chloride gas storage tank, the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1800 - 2200 m 3The flow rate of / h enters the fluidized bed reactor. The bottom temperature of the fluidized bed reactor is controlled at 290 - 295 °C, the pressure difference between the lower pressure and the upper pressure is 41 - 43 KPa, the particle size of the input silicon powder is 50 - 140 mesh, and a fluidization reaction is carried out to obtain synthesis gas.

[0109] 5) Dust removal and condensation are carried out on the synthesis gas in step S4 to obtain a crude trichlorosilane fluidized product (the content of trichlorosilane is 91.9%) and tail gas (the content of hydrogen chloride is 2%).

[0110] 6) The crude trichlorosilane fluidized product is rectified to obtain a trichlorosilane product.

[0111] Comparative test example 1

[0112] This example provides a process method for producing trichlorosilane products. The test steps of this example are partially the same as those of Example 1, and the only difference is that:

[0113] It does not include the step of spraying and purifying the by-product hydrogen chloride gas in step 2), but directly uses the by-product hydrogen chloride gas (entraining a small amount of silane, water, and methanol) to enter the fluidized bed reactor for synthesis at a flow rate of 1800 - 2200 m 3 / h.

[0114] Test: In the crude trichlorosilane fluidized product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 83.4%, the content of hydrogen chloride in the tail gas is 7%, and the content of methyltrichlorosilane impurities in the crude trichlorosilane fluidized product is 0.54% respectively.

[0115] Comparative test example 2

[0116] This example provides a process method for producing trichlorosilane products. The test steps of this example are the same as those of Example 1, and the only difference is that: In step 4), the bottom temperature of the fluidized bed reactor is controlled at 280 - 285 °C.

[0117] Test: In the crude trichlorosilane fluidized product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 92.7%, the content of hydrogen chloride in the tail gas is 26%, the pressure swing adsorption process is overloaded, and the compressor cannot operate normally.

[0118] Comparative test example 3

[0119] This example provides a process method for producing trichlorosilane products. The test steps of this example are the same as those of Example 1, and the only difference is that: In step 4), the bottom temperature of the fluidized bed reactor is controlled at 300 - 315 °C.

[0120] Test: In the crude trichlorosilane fluidized product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 88.4%, and the content of hydrogen chloride in the tail gas is 1%.

[0121] Comparative Test Example 4

[0122] This example provides a process for producing trichlorosilane products. The test steps are the same as those in Example 1, except that: in step 4), the temperature at the bottom of the fluidized bed reactor is controlled at 315 - 325 °C.

[0123] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 81.3%, and the content of hydrogen chloride in the tail gas is 1%.

[0124] Comparative Test Example 5

[0125] This example provides a process for producing trichlorosilane products. The test steps are the same as those in Example 1, except that: in step 4), the temperature at the bottom of the fluidized bed reactor is controlled at 325 - 335 °C.

[0126] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 75.6%, and the content of hydrogen chloride in the tail gas is 1%.

[0127] Comparative Test Example 6

[0128] This example provides a process for producing trichlorosilane products. The test steps are the same as those in Example 1, except that: in step 4), the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 1400 - 1750 m 3 / h.

[0129] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 89.3%, and the content of hydrogen chloride in the tail gas is 3%. The temperature in the fluidized bed reactor during the experiment is difficult to control, and the production capacity is small.

[0130] Comparative Test Example 7

[0131] This example provides a process for producing trichlorosilane products. The test steps are the same as those in Example 1, except that: in step 4), the purified hydrogen chloride gas enters the fluidized bed reactor at a flow rate of 2300 - 2600 m 3 / h.

[0132] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 87.7%, and the content of hydrogen chloride in the tail gas is 13%. The pressure swing adsorption process is overloaded during the experiment.

[0133] Comparative Test Example 8

[0134] This example provides a process for producing trichlorosilane products. The test steps are the same as those in Example 1, except that: in step 4), the pressure difference between the lower pressure and the upper pressure is 35 - 40 KPa.

[0135] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 84.7%, and the content of hydrogen chloride in the tail gas is 18%. During the experiment, the pressure swing adsorption process was overloaded.

[0136] Comparative Test Example 9

[0137] This embodiment provides a process for producing trichlorosilane products. The test steps of this test are the same as those of Example 1, except that: the pressure difference between the lower pressure and the upper pressure in step 4) is 43.5 - 45 KPa.

[0138] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 91.7%, and the content of hydrogen chloride in the tail gas is 1%. During the experiment, in the subsequent dust removal and condensation process, it was overloaded, and the dust removal amount exceeded twice the dust removal amount of Example 1.

[0139] Comparative Test Example 10

[0140] This embodiment provides a process for producing trichlorosilane products. The test steps of this test are the same as those of Example 1, except that: the particle size of the silicon powder in step 4) is 10 - 30 mesh.

[0141] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 89.5%, and the content of hydrogen chloride in the tail gas is 9%. During the experiment, after continuous operation for 7 days, the content of the trichlorosilane fluidized crude product gradually decreased to 84.4%, the silicon slag at the bottom of the fluidized bed increased, and the bottom temperature was abnormal.

[0142] Comparative Test Example 11

[0143] This embodiment provides a process for producing trichlorosilane products. The test steps of this test are the same as those of Example 1, except that: the particle size of the silicon powder in step 4) is 170 - 325 mesh.

[0144] Test: In the trichlorosilane fluidized crude product obtained by dust removal and condensation of the synthesis gas, the content of trichlorosilane is 87.1%, and the content of hydrogen chloride in the tail gas is 5%. During the experiment, in the subsequent dust removal and condensation process, it was overloaded, and the dust removal amount was more than one time that of Example 1.

[0145] It is necessary to point out here that the above embodiments are only for further elaborating and explaining the technical solutions of the present invention, and do not further limit the technical solutions of the present invention. The method of the present invention is only a preferred implementation, and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for cyclic production of trichlorosilane, characterized in that, It includes the following steps: Perform alcoholysis esterification reaction on chlorosilane A to obtain silane and by-product hydrogen chloride gas; Spray and purify the by-product hydrogen chloride gas with chlorosilane B to obtain the reaction material at the bottom of the spray tower containing chlorosilane B and the hydrogen chloride gas after spray purification. The reaction material at the bottom of the spray tower containing chlorosilane B is mixed or replaces chlorosilane A for cyclic preparation of by-product hydrogen chloride gas; Input silicon powder and the hydrogen chloride gas after spray purification into a fluidized bed reactor for reaction to obtain synthesis gas; Dust and condense the synthesis gas to obtain crude trichlorosilane in fluidized state and tail gas; The flow rate of the hydrogen chloride gas after spray purification entering the fluidized bed reactor is controlled at 1800 - 2200 m 3 / h, the particle size of the silicon powder is 50 mesh - 140 mesh, the bottom temperature of the fluidized bed reactor is controlled at 290°C - 295°C, and the pressure difference between the lower pressure and the upper pressure of the fluidized bed reactor is 41 KPa - 43 KPa; The chlorosilane A and the chlorosilane B are the same kind of chlorosilane; The content of trichlorosilane in the crude product in fluidized state is not less than 90%, and the content of hydrogen chloride in the tail gas is less than 5%; 2. The process for cyclic production of trichlorosilane according to claim 1, characterized in that, The spray purification is used to remove trace amounts of silane, water and alcohol carried in the by-product hydrogen chloride gas; 3. The process for cyclic production of trichlorosilane according to claim 1, characterized in that, The content of trichlorosilane in the crude product in fluidized state is 90% - 93%; 4. The process for cyclic production of trichlorosilane according to claim 1 or 2, characterized in that, The chlorosilane A and the chlorosilane B are selected from at least one of trichlorosilane, tetrachlorosilane, methyldichlorosilane, methyltrichlorosilane, chloropropyltrichlorosilane, chloropropylmethyldichlorosilane, propyltrichlorosilane, propylmethyldichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, vinyltrichlorosilane; 5. The process for cyclic production of trichlorosilane according to claim 1 or 2, characterized in that, The alcohol used in the alcoholysis esterification reaction is selected from at least one of methanol, ethanol, propanol, isopropanol; 6. The process for cyclic production of trichlorosilane according to claim 1 or 2, characterized in that, The outlet of the by-product hydrogen chloride gas of the alcoholysis esterification reaction equipment is directly connected to the inlet of the spray purification equipment; 7. The process for cyclic production of trichlorosilane according to claim 1 or 2, characterized in that, It also includes the step of rectifying the crude trichlorosilane in fluidized state.

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