An apparatus and method for producing silane using silicon tetrafluoride

Abstract

A device for preparing silane by using silicon tetrafluoride, comprising a reactor, the reactor comprising a pipe cap, a main shell and a bottom shell, an exhaust port being formed on the pipe cap; a gas distribution and stirring unit comprising a porous pad layer arranged in the bottom shell in a transverse direction and a plurality of steel balls arranged on the porous pad layer, the plurality of steel balls forming a steel ball layer; a first feed pipe sealingly penetrating through the pipe cap and extending into the bottom shell; a second feed pipe sealingly penetrating through the pipe cap and extending into the bottom shell; a temperature control unit arranged outside the reactor; the device breaks the incoming silicon tetrafluoride gas into fine bubbles by arranging the gas distribution and stirring unit composed of the porous pad layer and the steel ball layer, greatly increasing the gas-liquid contact area, at the same time, the rising bubbles drive the steel ball layer to produce continuous disturbance, playing an auxiliary stirring role on the reaction liquid, effectively solving the problems of uneven gas distribution and low mass transfer efficiency in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of chemical equipment and chemical process technology, specifically an apparatus and method for preparing silanes using silicon tetrafluoride. Background Technology

[0002] The reduction reaction of silicon tetrafluoride (SiF4) (e.g., SiF4 + NaAlH4 → SiH4 + NaAlF4) is one of the important technical routes for preparing high-purity silanes. This reaction system typically involves the coexistence of three phases: a gas phase (SiF4 or H2), a liquid phase (reducing agent, organic solvent), and a solid phase (metal fluoride byproducts). In traditional batch or fixed-bed reactors, multiphase reactions easily lead to uneven gas distribution, low gas-liquid mass transfer efficiency, localized overheating, and solid product deposition and caking, which in turn clogs the reactor bottom and outlet, severely affecting reaction efficiency, operational safety, and product yield.

[0003] While existing technologies include improved solutions employing mechanical stirring, these methods require long distances along the reactor path to enhance gas distribution uniformity, and solids tend to deposit. Therefore, developing a simple, efficient, non-depositional, and safe reaction apparatus and its supporting methods is of significant industrial value.

[0004] The information disclosed in the background section of this invention is only intended to enhance the understanding of the general background of this invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide an apparatus and method for preparing silanes using silicon tetrafluoride, so as to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An apparatus for preparing silanes using silicon tetrafluoride, comprising: The reactor includes a cap, a main shell, and a bottom shell arranged sequentially from top to bottom. The cap has an exhaust port, and the bottom shell has a connecting pipe that communicates with the interior of the reactor. A gas distribution and stirring unit includes a porous pad layer arranged laterally in the bottom shell and a plurality of steel balls disposed on the porous pad layer, wherein the plurality of steel balls form a steel ball layer. A vertically arranged first conveying pipe is sealed through the pipe cap and extends into the bottom shell; the bottom end of the first conveying pipe is located inside the steel ball layer, or the first conveying pipe passes through the porous pad layer and extends below the porous pad layer. A vertically arranged second conveying pipe, which is sealed through the pipe cap and extends into the bottom shell, with the bottom end of the second conveying pipe located above the steel ball layer; The temperature control unit is located outside the reactor.

[0007] Furthermore, the porous pad is a metal porous plate or a ceramic porous plate.

[0008] Furthermore, the pore size of the porous pad is 0.5–5 mm.

[0009] Furthermore, the diameter of the steel ball is 3 to 15 mm.

[0010] Furthermore, a gas phase filter screen is provided on the inner side of the exhaust port, and a back pressure valve is provided on the outer side.

[0011] Furthermore, the bottom shell and the main shell are detachably sealed together.

[0012] Furthermore, a four-way valve is connected to the outer end of the second conveying pipe, and the other three ports of the four-way valve are respectively connected to the feed line, the discharge line and the purging line.

[0013] The present invention also provides a method for preparing silanes using silicon tetrafluoride, based on the above-described apparatus, comprising the following steps: (1) Add the reducing agent and organic solvent to the reactor; (2) Silicon tetrafluoride gas is introduced into the bottom of the bottom shell, so that it passes through the porous pad layer and the steel ball layer in sequence, is broken into micro bubbles, and drives the steel ball layer to generate disturbance, thereby assisting in stirring the reaction liquid. (3) Control the reaction temperature and pressure to carry out the reduction reaction; (4) After the reaction is complete, the liquid product and solid by-product are discharged from the second feed pipe; (5) Discharge the remaining solid byproducts under the protection of inert gas.

[0014] Furthermore, the reducing agent is sodium aluminum hydride or lithium aluminum hydride; The organic solvent is one or more of toluene, xylene, tetrahydrofuran, or ethylene glycol dimethyl ether.

[0015] Furthermore, the reaction temperature is 40–120°C, the reaction pressure is 0.1–1.0 MPa, and the reaction time is 2–12 h.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention only sets a gas distribution and stirring unit consisting of a porous pad and a steel ball layer at the bottom of the reactor, without the need to set it over a long distance along the reactor path. It can effectively utilize the physical properties of the reaction gas source silicon tetrafluoride (SiF4) to break the reaction gas source SiF4 multiple times, improve the uniformity of gas distribution, and at the same time reduce the rising rate of the reaction gas source SiF4, increase the contact reaction time, thereby improving the raw material utilization rate and product purity. Furthermore, due to the impact force of the SiF4 reaction gas source passing upward through the porous pad and the disturbance of the steel balls, the problem of solid byproducts generated in the reaction depositing and caking at the bottom of the reactor can be effectively solved.

[0017] 2. The gas distribution and stirring unit composed of the porous pad layer and the steel ball layer set in this invention breaks the introduced silicon tetrafluoride gas into microbubbles, which greatly increases the gas-liquid contact area. At the same time, the rising bubbles drive the steel ball layer to generate continuous disturbance, which plays an auxiliary mechanical stirring role for the reaction liquid, realizing gas-driven self-stirring. This effectively solves the problems of uneven gas distribution and low gas-liquid mass transfer efficiency in the prior art, and there is no risk of dynamic sealing.

[0018] 3. By setting up a porous pad and a steel ball layer, when the first feed pipe extends into the steel ball layer and is above the porous pad, the silicon tetrafluoride gas transported by the first feed pipe is sprayed onto the porous pad and will be broken up by the porous pad for the first time. After passing through the porous pad, the broken gas will be deflected back by buoyancy and pass through the porous pad again, where it will be broken up a second time. Then it will pass through the steel ball layer and rise. When the silicon tetrafluoride gas rises through the steel ball layer, the steel balls in the steel ball layer will be disturbed, and the gaps between the steel balls will form several constantly changing tortuous channels. When the silicon tetrafluoride gas passes through the tortuous channels formed by the disturbance of the steel ball layer, it will be broken up again by the steel ball layer. Moreover, the tortuous channels will slow down the rise of the gas, increase the gas-liquid contact time, and improve the reaction efficiency.

[0019] 4. This invention utilizes the disturbance effect of the steel ball layer. The steel balls are lifted by the bubbles and then fall onto the porous pad layer. At the same time, the bubbles also lift the solid by-products, which can reduce the risk of solid by-products generated in the reaction depositing and caking at the bottom of the reactor, reduce the risk of clogging the discharge port, and ensure the continuous and stable progress of the reaction.

[0020] 5. By setting a detachable sealed connection between the main shell and the bottom shell and providing a connecting pipe, the present invention allows for the input of protective gas during the cleaning of solid by-products, thereby improving operational safety by enabling the cleaning of solid by-products under the protection of the protective gas. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the apparatus used to prepare silanes using silicon tetrafluoride in this embodiment; In the diagram: 1. Pipe cap; 2. Main shell; 3. Bottom shell; 4. Temperature control unit; 5. Steel ball layer; 6. Porous pad layer; 7. First feed pipe; 8. Second feed pipe; 9. Exhaust port; 10. Connecting pipe. Detailed Implementation

[0022] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.

[0023] In the description of this application, it should be understood that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the prepositions "first," "second," and "third," etc., are only used for the purpose of distinguishing the modified objects, and should not be construed as indicating or implying relative importance.

[0024] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] It should also be further understood that the term "and / or" as used in this application specification and the corresponding claims refers to any combination of one or more of the listed items and all possible combinations.

[0026] like Figure 1 As shown, this embodiment provides an apparatus for preparing silanes using silicon tetrafluoride. This apparatus is specifically designed to handle multiphase reactions involving gas, liquid, and solid phases, particularly the chemical reaction process in which silicon tetrafluoride is reduced by metal hydrides to prepare silanes. The core design of the apparatus lies in its ability to achieve efficient gas-liquid mass transfer, prevent the deposition of solid byproducts, and safely and conveniently discharge solid materials under an inert atmosphere.

[0027] This embodiment provides an apparatus for preparing silane using silicon tetrafluoride, comprising a reactor, a gas distribution and stirring unit, a vertically arranged first feed pipe 7, a vertically arranged second feed pipe 8, and a temperature control unit 4.

[0028] The reactor provides the enclosed space required for the chemical reaction. The reactor comprises, from top to bottom, a cap 1, a main shell 2, and a bottom shell 3. The cap 1 and the main shell 2 are sealed together by flanges or welding, while the main shell 2 and the bottom shell 3 are detachably sealed together by flanges or snap-fit ​​connections, thus forming a pressure-resistant, sealed container. The cap 1 has an exhaust port 9, which is used to discharge gases from the system during or after the reaction. In a preferred embodiment, a gas-phase filter screen is installed on the inner side of the exhaust port 9 (i.e., the side inside the reactor) to separate entrained droplets and prevent liquid from being carried out by the gas; a back pressure valve is installed on the outer side of the exhaust port 9 (i.e., the side outside the reactor) to precisely control the pressure within the reaction system. The bottom shell 3 has a connecting pipe 10 at its bottom, which communicates with the interior of the reactor. The connecting pipe 10 can be used to discharge solid byproducts generated in the reaction (such as sodium aluminum fluoride) or to introduce protective gas into the reactor. The main housing 2 is usually a vertically arranged cylindrical corrosion-resistant cavity, and its material can be stainless steel, Hastelloy, or other materials that can withstand the corrosion of silicon tetrafluoride and reactive solvents.

[0029] Temperature control unit 4 is located outside the reactor and is used to control the temperature during the reaction process. Temperature control unit 4 can be a jacket that wraps around the outer wall of the main shell 2. The jacket is provided with a heat transfer medium inlet and a heat transfer medium outlet. There can be multiple heat transfer medium inlets and outlets. The heat transfer medium can be a heating medium or a cooling medium. By introducing a heating medium (such as heat transfer oil or steam) or a cooling medium (such as cooling water) into the jacket, the temperature inside the reactor can be precisely regulated and maintained within the required reaction temperature range.

[0030] The gas distribution and stirring unit is located within the bottom shell 3, and includes a porous pad 6 and a steel ball layer 5 arranged sequentially from bottom to top. The porous pad 6 is laid laterally within the bottom shell 3, and its function is to initially distribute the gas introduced from the bottom of the reactor and to accommodate the steel ball layer 5. The porous pad 6 is a plate-like structure with numerous micropores. For example, the porous pad 6 can be a metal porous plate, such as one sintered from stainless steel powder, which has excellent mechanical strength and corrosion resistance; or, the porous pad 6 can be a ceramic sintered porous plate, utilizing the high-temperature resistance and corrosion resistance of ceramics. The pore size of the porous pad 6 is a key parameter affecting the gas fragmentation effect. Preferably, its pore size ranges from 0.5 to 5 mm. If the pore size is less than 0.5 mm, it will increase the resistance to gas passage, leading to increased energy consumption; if the pore size is greater than 5 mm, the initial gas fragmentation effect will be insufficient, and enough fine bubbles cannot be formed. In one exemplary structure, the porous pad 6 is placed directly inside the bottom shell 3, which may be funnel-shaped.

[0031] Above the porous pad 6, a steel ball layer 5 is laid. The steel ball layer 5 is composed of a large number of discrete, corrosion-resistant metal balls. The diameter of these steel balls is a crucial factor affecting the stirring effect and anti-deposition capability; preferably, the diameter of the steel balls is 3 to 15 millimeters. If the steel ball diameter is too small, its weight is too light, and it may be washed out of the steel ball layer 5 by rising airflow or liquid, resulting in limited disturbance; if the steel ball diameter is too large, it is difficult to be driven by gas to generate effective disturbance, and it will occupy too much bottom space. Exemplarily, these steel balls can be spherical 316L stainless steel balls, or nickel-based alloy balls with higher corrosion resistance and wear resistance. The steel ball layer 5 is typically laid on the porous pad 6 at a certain thickness, forming a loosely packed bed. During operation, silicon tetrafluoride gas introduced into the bottom of the reactor is sprayed downwards onto the porous pad 6. Some of the silicon tetrafluoride gas passes through the porous pad 6 downwards and then upwards again, passing through the steel ball layer 5. Some of the silicon tetrafluoride gas is blocked by the porous pad 6 and then passes through the steel ball layer 5 in the opposite direction. As the silicon tetrafluoride gas passes through the porous pad 6, it is initially divided into many fine gas streams. These fine gas streams then enter the steel ball layer 5, where they are further sheared and broken into extremely fine bubbles as they pass through the complex and tortuous channels between the steel balls. Simultaneously, these rapidly rising microbubbles impact and disturb the surrounding steel balls, causing the steel ball layer 5 to exhibit a slightly fluidized or disturbed state similar to a fluidized bed. The irregular movement of the steel balls driven by bubbles continuously shears and stirs the reaction liquid above, thus playing a role in assisting mechanical stirring and greatly enhancing the mixing and mass transfer between the gas-liquid-solid three phases. In this embodiment, in order to limit the range of the rising steel balls, a limiting net can also be set above the steel ball layer 5 to intercept steel balls that rise too high.

[0032] The first feed pipe 7 passes through the cap 1 in a sealed manner and extends downwards to the bottom shell 3, with its end outlet extending into the steel ball layer 5. This design allows silicon tetrafluoride gas to be directly delivered to the lowest point of the reactor, ensuring it passes through the porous pad 6 and the steel ball layer 5 as much as possible, thereby achieving optimal distribution and stirring. The upper end of the first feed pipe 7 serves as the inlet and outlet for the gaseous feed material, used to connect to a silicon tetrafluoride gas source or a recovery gas pipeline. In this embodiment, the flow rate of the gaseous feed material can be monitored by a flow meter and controlled by a valve. When the flow rate is too high, the flow rate can be reduced by the valve; when the flow rate is too low to disturb the steel ball layer 5, the flow rate can be increased by the valve. In the final stage of the reaction, inert gas can also be mixed into the gaseous feed material to increase the flow rate and assist in disturbing the steel ball layer 5.

[0033] In this embodiment, the first feed pipe 7 can also pass through the porous pad 6 and extend below the porous pad 6. When configured in this way, the gas transported through the first feed pipe 7 can be transported entirely below the porous pad 6 and pass through the porous pad 6 once, being broken up once by the porous pad 6. During the reaction, solid by-products will be generated, and some solid by-products will accumulate on the porous pad 6. Although the agitated steel balls can prevent the solid by-products from caking, during a long reaction, the pores on the porous pad 6 may be partially blocked by the solid by-products. Transporting gas below the porous pad 6 through the first feed pipe 7 is also equivalent to pressurizing the area below the porous pad 6. The gas transported below the porous pad 6 can prevent the solid by-products from blocking the porous pad 6. When the pores of the porous pad 6 are blocked, it can also help to unclog the pores on the porous pad 6.

[0034] The second feed pipe 8 is also sealed through the cap 1 and extends downward to the bottom shell 3. Its end opening is typically located above the steel ball layer 5 and is used to add liquid raw materials (such as an organic solution of a reducing agent) into the reactor, or to extract the liquid product from the reactor after the reaction. The outer end of the second feed pipe 8 is a multi-functional interface. In a highly preferred embodiment, this interface is connected to a four-way valve. The other three ports of this four-way valve are connected to the feed line, the discharge line, and the purge line, respectively. By switching the different paths of the four-way valve, three different operating modes can be achieved: First mode, connecting the feed line to the second feed pipe 8 to pump fresh reducing agent solution into the reactor; second mode, connecting the discharge line to the second feed pipe 8 to extract the reacted liquid product from the reactor using a pump or nitrogen pressurization; third mode, connecting the purge line to the second feed pipe 8 to purge the inside of the second feed pipe 8 with high-pressure nitrogen or inert gas to prevent solid material from accumulating and clogging the pipe. This integrated design greatly simplifies the piping system and improves ease of operation and cleanliness.

[0035] Regarding the discharge of solid materials, the solid phase produced by the reduction reaction of silicon tetrafluoride (SiF4), i.e., the metal fluoride byproduct, consists of tiny particles that can be suspended in the liquid phase and discharged along with it. After the liquid phase is discharged, a small amount of solid material may remain in the reactor. The bottom shell 3 and the main shell 2 are detachably sealed together, allowing the residual solid material to be cleaned by disassembling the bottom shell 3 from the main shell 2. For example, the bottom shell 3 can be connected to the flange at the bottom of the main shell 2 via a flange and bolts, supplemented by a sealing gasket to achieve a high-pressure seal; alternatively, a quick-release buckle connection with a clamp can be used for rapid disassembly. The bottom shell 3 is equipped with a connecting pipe 10 that communicates with the inside of the reactor. Before disassembling the bottom shell 3 to clean up the residual solid by-products, an inert gas (such as high-purity argon or nitrogen) is first introduced into the reactor through the connecting pipe 10 to replace the residual reactive gas inside the reactor. During the discharge process, the connecting pipe 10 also continues to introduce inert gas into the bottom shell 3, thereby forming an outward micro-positive pressure airflow to ensure the safety of the operation process and the purity of the product.

[0036] This embodiment also provides a method for preparing silanes using silicon tetrafluoride, including the following steps: Step (1): Loading. The reducing agent and organic solvent are added to the reactor through the second feed pipe 8 on the cap 1. The reducing agent is a substance used to provide a hydrogen source to reduce silicon tetrafluoride, preferably sodium aluminum hydride or lithium aluminum hydride, as these metal hydrides have extremely strong reducing properties. The organic solvent is used to dissolve the reducing agent and serves as the reaction medium; it must be able to dissolve the reducing agent and be inert to the reaction system. Exemplarily, the organic solvent can be one or more of toluene, xylene, tetrahydrofuran, or ethylene glycol dimethyl ether. These solvents have good solubility and chemical stability.

[0037] Step (2): Gas Distribution and Self-Stirring. The temperature control unit 4 is activated to preheat the reactor to the preset reaction temperature. Then, silicon tetrafluoride gas is introduced from the bottom of the reactor through the first feed pipe 7. The gas first enters the space below the porous pad 6, and then, driven by the pressure difference, rises through the porous pad 6. The micropores of the porous pad 6 divide the gas stream into a large number of fine gas flows. These fine gas flows then enter the steel ball layer 5. As they pass through the tortuous, narrow channel formed by countless stacked steel balls, the gas flow is further sheared and broken, eventually escaping from the steel ball layer 5 in the form of tiny microbubbles and entering the reaction liquid above. Due to the extremely small diameter of the bubbles, their specific surface area is enormous, greatly increasing the contact interface between the gas and liquid phases, significantly improving the probability of silicon tetrafluoride gas dissolving into the solvent and reacting with reducing agent molecules. Simultaneously, the large number of rapidly rising microbubbles exert irregular impact forces on the steel balls within the steel ball layer 5 as they pass through it. These impact forces are sufficient to overcome part of the steel balls' gravity in the liquid, causing continuous, slight fluidization or disturbance in the steel ball layer 5. This disturbance is transmitted to the reaction liquid above, creating a gentle yet efficient liquid stirring effect that is uniform throughout the entire bottom cross-section of the reactor. This gas-driven self-stirring action can completely or partially replace traditional mechanical stirrers without the need for complex dynamic sealing structures.

[0038] Step (3): Reaction Control. While introducing silicon tetrafluoride gas, the temperature inside the reactor is precisely controlled by the temperature control unit 4, and the pressure inside the reactor is controlled by the back pressure valve on the exhaust port 9, ensuring the reaction proceeds under preset stable conditions. Preferably, the reaction temperature is controlled between 40 and 120 degrees Celsius. Too low a temperature results in a slow reaction rate and low yield; too high a temperature may lead to increased solvent evaporation or side reactions. Preferably, the reaction pressure is controlled between 0.1 and 1.0 MPa. Pressure increases the solubility of silicon tetrafluoride in the solvent, thereby accelerating the reaction rate. The reaction time depends on the set temperature and pressure, preferably between 2 and 12 hours, to ensure a relatively complete reaction. During this process, silicon tetrafluoride reacts chemically with the reducing agent to generate gaseous silane and solid metal fluoride salts (such as sodium aluminum fluoride). The generated silane gas carries some unreacted silicon tetrafluoride and solvent vapor upwards, exiting from the top exhaust port 9 and entering the post-processing system for separation and purification. The generated solid byproducts, due to their high density, will gradually settle to the bottom of the reactor.

[0039] Step (4): Discharge of liquid products and solid byproducts. After the reaction is complete, the supply of silicon tetrafluoride gas is stopped, and the temperature is appropriately reduced by the temperature control unit 4. At this time, the liquid in the reactor contains unreacted raw materials, a mixture of dissolved silanes, and suspended solid byproducts. The two-way valve at the outer end of the second feed pipe 8 is operated to switch it to the discharge line. The liquid products and solid byproducts can be forced out from the inlet of the second feed pipe 8 located at the bottom by using the pressure of the reactor itself, or by pressurizing it by introducing a small amount of high-pressure nitrogen from the top (e.g., the first feed pipe 7), and then transported to downstream separation or storage equipment via the discharge line. This bottom-discharge method can more thoroughly discharge the liquid materials and solid byproducts.

[0040] Step (5): Discharge of residual solid byproducts. After the liquid product and solid byproducts are discharged, a small amount of solid byproducts, a small amount of liquid, and steel ball layer 5 remain in the reactor. At this time, inert gas (such as argon or nitrogen) is continuously introduced into the reactor through the connecting pipe 10 to purge the internal space of the reactor and displace any flammable and explosive gases such as silane and hydrogen that may be present. Under continuous ventilation protection, the operator disassembles the bottom shell 3 and cleans the residual solid byproducts. After the bottom shell 3 is disassembled, the steel ball layer 5 and the porous pad layer 6 can also be cleaned. The entire cleaning process is carried out under the protection of the inert gas flow, which can isolate the air as much as possible and ensure the safety of the operation.

[0041] In a preferred embodiment, the method can be carried out in a semi-continuous or continuous manner. Continuous feeding and discharging of the reaction solution can be achieved by switching via a four-way valve at the outer end of the second feed pipe 8. In semi-continuous operation, the reaction can be carried out intermittently, a portion of the reaction solution can be discharged, fresh raw materials can be added, and the reaction can continue in a cycle. In continuous operation, fresh reducing agent solution is continuously added to the reactor via a feed pump, while the reaction mixture is continuously discharged through an overflow port added to the side wall of the reactor, either through the overflow port or a controlled discharge valve, thus enabling long-term uninterrupted operation of the reactor. Meanwhile, residual solid byproducts can be discharged periodically. This operating mode greatly improves production efficiency and is suitable for large-scale industrial production.

[0042] In this embodiment, there is a close and ingenious connection between the steel balls and the reaction method. The key to the steel balls' ability to prevent caking lies in their unique mode of operation within the reaction system.

[0043] During the reaction, the reaction liquid is in a constantly changing state, generating solid materials. If these solid materials are static or do not flow smoothly, they are prone to agglomeration and adhesion, eventually forming clumps. However, the steel balls in the reaction system roll and move continuously with the flow of the reaction liquid. Their presence breaks up any static areas (areas containing solid materials) in the reaction liquid, and their movement drives the flow of the surrounding reaction liquid, making it difficult for solid materials to remain and agglomerate in any one area.

[0044] The steel balls can be flexibly adjusted according to the specific reaction conditions. For example, when the reaction is more vigorous, and a large amount of solid material is generated that is prone to aggregation, the number of steel balls or the size of the steel balls can be appropriately increased to enhance their agitation effect on the reaction liquid and effectively prevent the solid material from agglomerating and caking. Conversely, when the reaction is more gradual, the number of steel balls can be reduced or smaller steel balls can be used to avoid excessive agitation from adversely affecting the reaction. This flexibility and adjustability allow the steel balls to precisely adapt to the reaction requirements at different stages, thereby better achieving the goal of preventing caking.

[0045] As for mechanical stirring, although it can theoretically agitate the reaction liquid, it presents two significant problems in this process. First, there is the safety issue. Since the product of this process is silane, which is highly flammable and explosive, the installation of mechanical stirring equipment is often complex and may compromise the reactor's seal during installation. Once the reactor's seal is compromised, silane leaks out and mixes with air. Upon encountering an ignition source such as a spark, this can easily cause a combustion or explosion, posing a significant safety hazard to the production process.

[0046] Secondly, mechanical stirring has limitations in dealing with solid materials generated during the reaction. The stirring paddle of a mechanical stirrer may create dead zones within the reactor during rotation. In these dead zones, the flow of the reaction liquid is impeded, and solid materials easily accumulate. Moreover, if the stirring effect is poor, the interaction forces between solid materials cannot be effectively broken, easily leading to agglomeration and compaction, affecting the normal progress of the reaction and product quality. In contrast, the free movement of steel balls in the reaction system can more comprehensively and evenly agitate the reaction liquid, avoiding dead zones and thus more effectively preventing the agglomeration and compaction of solid materials.

[0047] To more clearly illustrate the technical effects of the present invention, several specific embodiments are provided below for explanation.

[0048] Example 1 Adopting such Figure 1The apparatus is shown. The reactor is a 316L stainless steel cylinder with an inner diameter of 100 mm and a height of 800 mm. A sintered metal porous plate (2 mm pore size) and a layer of nickel-based alloy steel beads 5 (50 mm thick) with a diameter of 5 mm are placed sequentially at the bottom. A toluene solution containing sodium aluminum hydride (10% mass concentration) is added from the top, and the reactor is heated to 80°C. Silicon tetrafluoride gas (flow rate 0.5 L / min) is introduced through the first feed pipe 7 at the bottom, and the reaction pressure is set to 0.3 MPa through the back pressure valve at the exhaust port 9. After 6 hours of reaction, the liquid product is discharged under nitrogen pressure through the second feed pipe 8. Gas chromatography analysis shows a silane yield of 92%. After cooling to room temperature, argon gas is introduced for protection, and the bottom shell 3 is disassembled. Solid sodium aluminum fluoride is smoothly discharged with the liquid phase. No obvious caking is observed on the surface of the porous pad 6 and the steel bead layer 5 at the bottom of the reactor.

[0049] Example 2 The same apparatus as in Example 1 was used, except that the diameter of the steel balls was 10 mm, the reaction temperature was increased to 120 degrees Celsius, and the reaction time was shortened to 4 hours. After the reaction, the silane yield was measured to be 89%, and the solid product was discharged smoothly without any blockage.

[0050] Example 3 The same apparatus as in Example 1 was used. A toluene solution containing sodium aluminum hydride (10 wt%) was added at the top, heated to 40°C, and silicon tetrafluoride gas (flow rate 0.5 L / min) was introduced from the bottom. The back pressure valve was set to 0.3 MPa. After reacting for 12 hours, the liquid product was discharged under nitrogen pressure, and the silane yield was analyzed to be 85%. After cooling to room temperature, argon gas was introduced for protection, and the bottom shell 3 was disassembled. The solid sodium aluminum fluoride was smoothly discharged with the liquid phase, and there was no obvious caking at the bottom of the reactor. This example demonstrates that the apparatus of the present invention can still operate stably and achieve a high yield at a low temperature of 40°C.

[0051] Example 4 The same apparatus as in Example 1 was used. A toluene solution containing sodium aluminum hydride (10 wt%) was added at the top, heated to 80°C, and silicon tetrafluoride gas (flow rate 0.5 L / min) was introduced from the bottom. The reaction pressure was set to 1.0 MPa through a back pressure valve. After 6 hours of reaction, the liquid product was discharged under nitrogen pressure, and the silane yield was analyzed to be 94%. After cooling to room temperature, argon gas was introduced for protection, and the bottom shell 3 was disassembled. Solid sodium aluminum fluoride was smoothly discharged with the liquid phase, and there was no obvious caking at the bottom of the reactor. This example demonstrates that the apparatus of the present invention can withstand high pressure conditions of 1.0 MPa, and that pressurization is beneficial to improving the reaction yield.

[0052] Example 5 The same apparatus as in Example 1 was used. A toluene solution containing sodium aluminum hydride (10 wt%) was added at the top, heated to 80°C, and silicon tetrafluoride gas (flow rate 0.5 L / min) was introduced from the bottom. The back pressure valve was set to 0.1 MPa. After 6 hours of reaction, the liquid product was discharged under nitrogen pressure, and the silane yield was analyzed to be 87%. After cooling to room temperature, argon gas was introduced for protection, and the bottom shell 3 was disassembled. Solid sodium aluminum fluoride was smoothly discharged with the liquid phase, and there was no obvious caking at the bottom of the reactor. This example demonstrates that the apparatus of the present invention can still operate stably under the low-pressure boundary condition of 0.1 MPa and achieve a yield of over 85%.

[0053] Example 6 The same apparatus as in Example 1 was used. A toluene solution containing sodium aluminum hydride (10 wt%) was added at the top, heated to 120°C, and silicon tetrafluoride gas (flow rate 0.5 L / min) was introduced from the bottom. The back pressure valve was set to 0.3 MPa. After 2 hours of reaction, the liquid product was discharged under nitrogen pressure, and the silane yield was analyzed to be 90%. After cooling to room temperature, argon gas was introduced for protection, and the bottom shell 3 was disassembled. Solid sodium aluminum fluoride was smoothly discharged with the liquid phase, and there was no obvious caking at the bottom of the reactor. This example shows that under the high-temperature boundary condition of 120°C, the reaction rate is significantly accelerated, and a 90% yield can be achieved in just 2 hours.

[0054] Example 7 (Semi-continuous operation) The same apparatus as in Example 1 was used, with a four-way valve connected to the outer end of the second feed pipe 8, connecting to the feed line, discharge line, and purge line. The operating procedure was as follows: initially, sodium aluminum hydride toluene solution was added to 60% of the reactor volume, and the reaction was carried out at 80°C and 0.3 MPa for 4 hours. Aeration was stopped, and the four-way valve was switched to the discharge line to purge approximately 50% of the reactants from the reactor using nitrogen. Then, the four-way valve was switched to the feed line to replenish fresh feedstock to the original level. Finally, the purge line was switched to the purge line to purge the feed and discharge lines with low-pressure nitrogen. Aeration was restarted for the next round of reaction. This cycle was repeated 5 times. Results: the average silane yield over 5 cycles was 91% (single yields were 92%, 91%, 91%, 90%, and 91%, respectively); no blockage occurred in the feed and discharge lines after each cycle's nitrogen purging; and the final bottom solid byproducts were discharged smoothly without caking. This embodiment demonstrates that the apparatus and method of the present invention are applicable to semi-continuous operation mode, thereby improving production efficiency.

[0055] Example 8 (Continuous Operation) The same apparatus as in Example 1 was used, with the following modifications: an overflow port was installed above the side wall of the main shell 2 for continuous liquid discharge; a second feed pipe 8 was connected to a continuous feed pump; and the rear end of the exhaust port 9 was connected to a condenser and a silane collection system. The operating procedure was as follows: initially, an aluminum hydride sodium toluene solution was added to 50% of the reactor volume, and the reaction was carried out at 80°C and 0.3 MPa. After the reaction stabilized, the feed pump was started to continuously replenish fresh raw materials at a rate of 5 mL / min. When the reaction liquid level rose to the overflow port, the reaction liquid was continuously discharged. The gas discharged from the exhaust port 9 was condensed by the condenser, and the silane was collected in liquid form. The system was run continuously for 24 hours, with samples taken for analysis every 4 hours. Results: The average silane yield was 90% over 24 hours, with the yield fluctuating between 89% and 91% at various time points. The pressure at the bottom of the reactor was stable, and there were no signs of blockage. This example demonstrates that the apparatus and method of the present invention can achieve long-term continuous and stable operation and has potential for industrial application.

[0056] Comparative Example 1 (Traditional batch reactor) A conventional stirred tank reactor with mechanical stirring, lacking a bottom steel ball layer and a removable discharge shell, was used. The reaction was carried out under the same conditions as in Example 1. After 4 hours of reaction, significant solid caking appeared at the bottom of the reactor, clogging the discharge port and preventing normal discharge. The reactor needed to be shut down and disassembled for manual cleaning. The silane yield was measured to be only 76%, with poor batch-to-batch repeatability. This indicates that the present invention, through its unique gas distribution and stirring unit design, effectively solves the problems of mass transfer obstruction and clogging caused by solid deposition in traditional technologies.

[0057] In summary, the apparatus and method for preparing silanes using silicon tetrafluoride provided by this invention achieves efficient gas fragmentation and self-stirring of the reaction liquid through the synergistic effect of the porous pad layer 6 and the steel ball layer 5, significantly improving the mass transfer efficiency of the gas-liquid-solid three-phase reaction. Simultaneously, this design effectively prevents the deposition and caking of solid byproducts, and combined with the removable bottom shell 3 and inert gas protection, ensures the safe and convenient discharge of residual solid products. The apparatus has a simple structure, no complex moving parts, and is easy to maintain and scale up industrially. It exhibits excellent stability and high yield in both semi-continuous and continuous operation modes, providing a novel and efficient solution to the technical bottlenecks in the reduction of silicon tetrafluoride to prepare silanes.

[0058] It should be noted that although the present invention has been disclosed above with specific embodiments, the above embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. An apparatus for preparing silanes using silicon tetrafluoride, characterized in that, include: The reactor includes a cap, a main shell, and a bottom shell arranged sequentially from top to bottom. The cap has an exhaust port, and the bottom shell has a connecting pipe that communicates with the interior of the reactor. A gas distribution and stirring unit includes a porous pad layer arranged laterally in the bottom shell and a plurality of steel balls disposed on the porous pad layer, wherein the plurality of steel balls form a steel ball layer. A vertically arranged first conveying pipe is sealed through the pipe cap and extends into the bottom shell; the bottom end of the first conveying pipe is located inside the steel ball layer, or the first conveying pipe passes through the porous pad layer and extends below the porous pad layer. A vertically arranged second conveying pipe, which is sealed through the pipe cap and extends into the bottom shell, with the bottom end of the second conveying pipe located above the steel ball layer; The temperature control unit is located outside the reactor.

2. The apparatus for preparing silanes using silicon tetrafluoride as described in claim 1, characterized in that, The porous pad is a metal porous plate or a ceramic porous plate.

3. The apparatus for preparing silanes using silicon tetrafluoride as described in claim 1, characterized in that, The pore size of the porous pad is 0.5 to 5 mm.

4. The apparatus for preparing silanes using silicon tetrafluoride as described in claim 1, characterized in that, The diameter of the steel ball is 3 to 15 mm.

5. The apparatus for preparing silanes using silicon tetrafluoride as described in claim 1, characterized in that, The exhaust port is equipped with a gas phase filter mesh on the inner side and a back pressure valve on the outer side.

6. The apparatus for preparing silanes using silicon tetrafluoride as described in claim 1, characterized in that, The bottom shell and the main shell are detachably sealed together.

7. The apparatus for preparing silanes using silicon tetrafluoride as described in claim 1, characterized in that, The outer end of the second conveying pipe is connected to a four-way valve, and the other three ports of the four-way valve are respectively connected to the feed line, the discharge line and the purging line.

8. A method for preparing silanes using silicon tetrafluoride, based on the apparatus of any one of claims 1-7, characterized in that, Includes the following steps: (1) Add the reducing agent and organic solvent to the reactor; (2) Silicon tetrafluoride gas is introduced into the bottom of the bottom shell, so that it passes through the porous pad layer and the steel ball layer in sequence, is broken into micro bubbles, and drives the steel ball layer to generate disturbance, thereby assisting in stirring the reaction liquid. (3) Control the reaction temperature and pressure to carry out the reduction reaction; (4) After the reaction is complete, the liquid product and solid by-product are discharged from the second feed pipe; (5) Discharge the remaining solid byproducts under the protection of inert gas.

9. The method for preparing silanes using silicon tetrafluoride as described in claim 8, characterized in that, The reducing agent is sodium aluminum hydride or lithium aluminum hydride; The organic solvent is one or more of toluene, xylene, tetrahydrofuran, or ethylene glycol dimethyl ether.

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