Preparation method of high-purity silane suitable for small experimental device

Abstract

The invention discloses a preparation method of high-purity silane suitable for a small experimental device, which comprises the following steps: sequentially connecting and arranging a main reactor, a second reactor, a condenser, a silane buffer tank, a booster pump and a silane steel cylinder, and injecting hydrogen, nitrogen and silicon tetrafluoride materials into the main reactor after passing through the same mass flow controller; then the material enters a second reactor through a gas phase outlet pipeline at the top of the main reactor, a gas phase outlet at the top of the second reactor is connected with an inlet at the bottom of a condenser, an outlet of the condenser is connected with a silane buffer tank, and an outlet pipeline is arranged at the top of the silane buffer tank; materials enter the booster pump through the outlet pipeline, are pressurized in the booster pump and then are fed into the silane steel cylinder to be stored, so that the complexity of the reaction device is simplified, the energy consumption is reduced, and the problems of huge device size, complex process conditions and the like are solved.

Description

Technical Field

[0001] This invention belongs to the field of silane preparation technology, and specifically relates to a method for preparing high-purity silane suitable for small-scale experimental devices. Background Technology

[0002] Silanes have a wide range of applications. Ordinary silanes, with a purity of 3N to 4N, are mainly used in the glass and coating industries. Products with a purity of 6N and above are called electronic-grade silanes, which are mainly used in the semiconductor, LCD, and fiber optic communication industries. Some special silanes, such as those made from silicon isotopes, have significant material advantages. However, these silanes often have limited raw materials, limited production, and high value, thus requiring high recovery rates. This necessitates small-sized chemical production equipment with high purity and high recovery rates.

[0003] Currently, the main silane production methods used in large-scale chemical production equipment include the magnesium silicide method, the sodium aluminum hydride reduction method, and the disproportionation method. The magnesium silicide method (also known as the Komatsu method) was pioneered in China by Zhejiang University in the 1970s. It involves mixing magnesium silicide and ammonium chloride in a liquid ammonia environment to produce silane and ammonia gas. The ammonia and silane are then separated using technical means to obtain high-purity silane. The sodium aluminum hydride reduction method involves mixing sodium aluminum hydride with an ether solvent and then reacting it with silicon tetrafluoride or silicon tetrachloride to produce high-purity silane. The core of the disproportionation method is to utilize the different chemical equilibria of silicon halides at different temperatures to disproportionate trichlorosilane to produce different products, including silane, which are then distilled to obtain high-purity silane.

[0004] From a process perspective, the magnesium silicide method has a relatively simple reaction process, but it involves separating ammonia from silane, an operation that requires distillation. Introducing a distillation section presents two challenges: firstly, the pressure is high, and silane gas is flammable and explosive, posing a safety hazard; secondly, it may negatively impact product yield. In the sodium aluminum hydride reduction method, the commonly used process involves mixing dimethoxyethane with sodium aluminum hydride, then introducing silicon tetrafluoride for reaction, followed by product purification through distillation. The difficulties of this method are the same as those of the first aforementioned approach.

[0005] The invention disclosed in CN102491339A is a silicon tetrafluoride reduction process and the application of sodium aluminum hydride coated with linear polymer resin to isolate it from the outside air in the silicon tetrafluoride reduction process. The silicon tetrafluoride reduction process includes preparing a sodium aluminum hydride solution: measuring the required amount of sodium aluminum hydride coated with linear polymer resin to isolate it from the outside air, dissolving it in an organic solvent to obtain a sodium aluminum hydride solution; the reaction between silicon tetrafluoride and sodium aluminum hydride solution can ensure the safety of sodium aluminum hydride feeding and prevent sodium aluminum hydride from contacting air and becoming ineffective; however, its reaction temperature is high, reaching 200℃, which is also not conducive to small-scale production; the disproportionation method not only includes multiple distillation systems but also multiple return systems, so its system structure is more complex and not suitable for micro-chemical plants. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a method for preparing high-purity silanes suitable for small-scale experimental setups, simplifying the complexity of the reaction apparatus and reducing energy consumption.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing high-purity silane suitable for small-scale experimental devices includes a preparation apparatus. The preparation apparatus comprises a main reactor, a second reactor, a condenser, a silane buffer tank, a booster pump, and a silane cylinder, which are connected in sequence. Hydrogen, nitrogen, and silicon tetrafluoride are injected into the main reactor after passing through the same mass flow controller. Subsequently, the material enters the second reactor through the gas phase outlet pipeline at the top of the main reactor. The gas phase outlet at the top of the second reactor is connected to the bottom inlet of the condenser. The outlet of the condenser is connected to the silane buffer tank. The top of the silane buffer tank is equipped with an outlet pipe. The material enters the booster pump through the outlet pipe and is pressurized in the booster pump before being sent to the silane cylinder for storage. The preparation method includes the following steps: (1) Device replacement First, inert gas is introduced into the main reactor, the second reactor and the silane buffer tank. After the pressure rises to the set pressure, the booster pump is started, and at the same time the vent valve at the outlet of the booster pump is opened to reduce the pressure of each reaction vessel to atmospheric pressure. Hydrogen gas is then introduced into the main reactor, the second reactor, and the silane buffer tank. Once the pressure reaches the set pressure, the booster pump is started, and the vent valve at the outlet of the booster pump is opened to reduce the pressure of each reaction vessel to atmospheric pressure. (2) Material input The main reactor and the second reactor are isolated, and nitrogen is continuously introduced into the two reactors for purging. Then, the main reactor and the second reactor are fed with tetrahydrofuran and lithium aluminum hydride, and the stirring devices installed on the top of the main reactor and the second reactor are started to mix the raw materials evenly. (3) Displacement after stirring The main reactor and the second reactor are isolated, and the contents of both reactors are replaced with hydrogen gas. (4) Introduce silicon tetrafluoride Open the silicon tetrafluoride feed valve and introduce silicon tetrafluoride into the main reactor; (5) Silane condensation After silicon tetrafluoride is introduced, silane is generated in the main reactor. The silane, mixed with organic matter, is introduced into the second reactor. The organic matter in the main reactor is condensed down, while the unreacted silicon tetrafluoride in the main reactor will react further. The organic matter generated in the second reactor continues to be condensed by the condenser and flows back to the second reactor through the reflux pipe. (6) Silane collection The silane exiting the condenser enters the silane buffer tube. When the pressure inside the silane buffer tank rises, it is drawn by the booster pump and sent into the silane cylinder.

[0008] The main reactor and the second reactor are connected in series. The silicon tetrafluoride feed line of the main reactor is an insertion pipe, and the silane outlet line of the main reactor is a gas phase pipe. The silane feed line of the second reactor is an insertion pipe, and the silane outlet line of the second reactor is a gas phase pipe.

[0009] The condenser is cooled by an external refrigeration device, and the temperature range is -55℃ to -110℃.

[0010] In step (1), the inert gas is nitrogen, helium, or argon.

[0011] In step (2), the volume of feed is 60% to 80% of the reactor liquid level, and the concentration of lithium aluminum hydride is 10% to 15%.

[0012] The mixing device is a paddle mixer, an anchor mixer, or a frame mixer.

[0013] Both the main reactor and the second reactor are equipped with jackets at the bottom through which cooling medium flows.

[0014] The beneficial effects of this invention are: (1) This invention discloses a method for preparing high-purity silane suitable for small experimental devices. The method involves sequentially connecting a main reactor, a second reactor, a condenser, a silane buffer tank, a booster pump, and a silane cylinder. Hydrogen, nitrogen, and silicon tetrafluoride are injected into the main reactor after passing through the same mass flow controller. The material then enters the second reactor through the gas phase outlet pipeline at the top of the main reactor. The gas phase outlet at the top of the second reactor is connected to the inlet at the bottom of the condenser. The outlet of the condenser is connected to the silane buffer tank. The top of the silane buffer tank is equipped with an outlet pipe. The material enters the booster pump through the outlet pipe and is pressurized in the booster pump before being sent to the silane cylinder for storage. This method simplifies the complexity of the reaction device, reduces energy consumption, and solves problems such as large device size and complex process conditions.

[0015] (2) A small reaction device was adopted, which reduced the size of the large reaction device, reduced the dead volume, and achieved a fine and stable reaction, which effectively improved the reaction yield. In addition, the preparation method reduced the reaction temperature, reduced energy consumption, simplified the complexity of the reaction device, and reduced production costs.

[0016] (3) Using lithium aluminum hydride and tetrahydrofuran as the reactor slurry has the advantages of high reaction rate and low product impurity compared with slurry composed of sodium aluminum hydride and other ether solvents. It provides a small-scale high-purity silane preparation process route and equipment with high value, small batch, high purity and high yield. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0018] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0019] This invention provides a method for preparing high-purity silane suitable for small-scale experimental setups, such as... Figure 1 As shown.

[0020] A method for preparing high-purity silane suitable for small-scale experimental devices includes a preparation apparatus comprising a main reactor 1, a second reactor 2, a condenser 3, a silane buffer tank 4, a booster pump 5, and a silane cylinder 6, which are sequentially connected. Hydrogen, nitrogen, and silicon tetrafluoride are injected into the main reactor after passing through the same mass flow controller. Subsequently, the material enters the second reactor through the gas phase outlet pipeline at the top of the main reactor. The gas phase outlet at the top of the second reactor is connected to the bottom inlet of the condenser. The outlet of the condenser 3 is connected to the silane buffer tank 4. The top of the silane buffer tank is equipped with an outlet pipeline. The material enters the booster pump 5 through the outlet pipeline, is pressurized in the booster pump, and is then sent to the silane cylinder 6 for storage. The preparation method includes the following steps: (1) Device replacement First, inert gas is introduced into the main reactor, the second reactor, and the silane buffer tank. After the pressure rises to the set pressure, the booster pump is started, and the vent valve at the outlet of the booster pump is opened to reduce the pressure of each reaction vessel to atmospheric pressure. The inert gas can be nitrogen, helium, or argon. In this embodiment, nitrogen is selected to ensure production safety. The pressure control range of the device during purging is 0~200 kPa.

[0021] Secondly, hydrogen gas 7 is introduced into the main reactor, the second reactor and the silane buffer tank. After the pressure rises to the set pressure, the booster pump is started, and the vent valve at the outlet of the booster pump is opened to reduce the pressure of each reaction vessel to atmospheric pressure. Nitrogen or helium can also be used, as long as the gas does not affect the quality of the product, i.e., silane. The pressure control range of the device during replacement is 0~200 kPa.

[0022] (2) Material input The main reactor and the second reactor are isolated, and nitrogen is continuously introduced into each reactor for purging. Then, the main reactor and the second reactor are fed with tetrahydrofuran and lithium aluminum hydride. The stirring devices installed on the top of the main reactor and the second reactor are started to mix the raw materials evenly. The amount of feed depends on the size of the reactor. The reactor liquid level is controlled at 60% to 80%, and the concentration of lithium aluminum hydride is kept within the range of 10% to 15%.

[0023] (3) Displacement after stirring The main reactor and the second reactor are isolated, and the contents of both reactors are replaced with hydrogen gas. (4) Introduce silicon tetrafluoride Open the silicon tetrafluoride 8 feed valve and introduce silicon tetrafluoride into the main reactor 1; (5) Silane condensation After silicon tetrafluoride 8 is introduced, silane will be generated in the main reactor. The silane, mixed with some organic matter, will be introduced into the second reactor. The organic matter in the main reactor will be condensed down, while the unreacted silicon tetrafluoride in the main reactor will react further. The organic matter generated in the second reactor will continue to be condensed by the condenser and flow back to the second reactor through the reflux pipe.

[0024] High-purity silicon tetrafluoride (5N) is used. The feed rate depends on the size and depth of the insertion tube of the reaction device, the type of reactor stirring, and the stirring speed of the reactor. The feed rate is 500g / h to 3kg / h, and this value is controlled by a mass flow controller.

[0025] (6) Silane collection The silane exiting the condenser enters the silane buffer tube. When the pressure inside the silane buffer tank rises to a certain level, it is drawn by the booster pump and sent into the silane cylinder.

[0026] The main reactor and the second reactor are connected in series. The silicon tetrafluoride feed line of the main reactor is an insertion pipe, and the silane outlet line of the main reactor is a gas phase pipe. The silane feed line of the second reactor is an insertion pipe, and the silane outlet line of the second reactor is a gas phase pipe.

[0027] The condenser is cooled by external refrigeration equipment, and the temperature range is -55℃ to -110℃. Its heat exchange area depends on factors such as the production rate of the device and the heat exchange temperature difference.

[0028] The stirring device is a paddle stirrer, anchor stirrer, or frame stirrer; the stirring motor power depends on the size of the reactor, and in this example, the motor power is 200W; the stirring time often depends on the type of device, the concentration of raw materials, and the physical structure of the raw materials (powder, tablets), and in this example, the stirring time is often 6 hours.

[0029] The following description, in conjunction with specific embodiments, provides further details: The apparatus used in this invention is as follows Figure 1 As shown, nitrogen is directly introduced via an upstream nitrogen pipeline, while hydrogen and silicon tetrafluoride are stored in 47L standard steel cylinders. All three materials—hydrogen, nitrogen, and silicon tetrafluoride—pass through the same mass flow controller. The host computer performs different calculations based on the different materials to determine the mass flow rate of each gas. The outlet of the mass flow meter is connected to the main reactor via an insertion pipe approximately 20cm deep. The material enters the second reactor via the gas phase outlet pipe at the top of the main reactor. This pipe also serves as an insertion pipe in the second reactor, approximately 15cm deep. The gas phase outlet at the top of the second reactor is connected to the bottom inlet of the condenser, also serving as the condensate return pipe. The condenser is cooled using an external refrigerant. The condenser outlet is connected to a silane buffer tank via an insertion pipe 25cm deep. A pipe at the top of the silane buffer tank serves as the material outlet pipeline. The material enters the inlet of the silane booster pump via this pipeline, where it is pressurized and then sent to a silane cylinder for storage. In addition, the reactor has a jacket at the bottom, through which a cooling medium is supplied from outside the device, controlling the temperature range of the main reactor and the second reactor between 18°C ​​and 35°C.

[0030] The preparation method includes the following steps: (1) Device replacement The apparatus was purged with nitrogen six times, with the purging pressure controlled between 0 and 120 kPa; the apparatus was purged with hydrogen six times, with the purging pressure controlled between 0 and 120 kPa. (2) Material input The main reactor and the second reactor were isolated from the silane condenser and its downstream devices. At the same time, the main reactor and the second reactor were continuously purged with nitrogen for 10 minutes. 18 L and 3 L of tetrahydrofuran and 2.3 kg and 0.6 kg of lithium aluminum hydride were added to the main reactor and the second reactor, respectively. Then the stirring motors of the main reactor and the second reactor were started and the speed was set to 100 rpm for 6 hours. (3) Displacement after stirring The stirred reactor was re-purged with hydrogen six times, the same as the hydrogen purging part in step (1).

[0031] (4) Introduce silicon tetrafluoride Open the silicon tetrafluoride feed valve, set the silicon tetrafluoride feed rate to 0.8 kg / h, and simultaneously change the stirring speed to 200 rpm.

[0032] (5) Silane condensation When silicon tetrafluoride is introduced, it generates silane in the main reactor. The silane, mixed with some organic matter, is introduced into the second reactor. The organic matter in the main reactor is condensed. The unreacted silicon tetrafluoride in the main reactor is further reacted. The organic matter generated in the second reactor is condensed by the condenser and flows back to the second reactor through the return pipe. Then it enters the condenser and exchanges heat with the refrigerant in the condenser. The refrigerant temperature is -80°C. Then it enters the silane buffer tank.

[0033] (6) Silane collection As silane slowly enters the silane buffer tank, the pressure in the silane buffer tank continues to rise. When the pressure inside the silane buffer tank rises to 150 kPa, the booster pump starts and sends the gas to the silane cylinder. When the pressure in the silane buffer tank drops below 150 kPa, the booster pump stops, thus maintaining the pressure inside the silane buffer tank at a constant 150 kPa.

[0034] If this patent uses terms such as "first" and "second" to define components, those skilled in the art should know that the use of "first" and "second" is merely for the convenience of describing the invention and simplifying the description, and the above terms have no special meaning.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0036] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "center", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for the production of high purity silane suitable for use in small scale laboratory apparatus, characterised in that: The preparation device comprises a main reactor, a second reactor, a condenser, a silane buffer tank, a booster pump and a silane steel bottle which are sequentially connected, and hydrogen, nitrogen and silicon tetrafluoride material are injected into the main reactor after passing through the same mass flow controller, then the material enters the second reactor through the gas phase outlet pipeline at the top of the main reactor, the top gas phase outlet of the second reactor is connected with the bottom inlet of the condenser, the outlet of the condenser is connected with the silane buffer tank, an outlet pipeline is arranged at the top of the silane buffer tank, the material enters the booster pump through the outlet pipeline and is stored in the silane steel bottle after being pressurized in the booster pump; The preparation method comprises the following steps: (1) Device displacement First, inert gas is introduced into the main reactor, the second reactor and the silane buffer tank, and after the pressure rises to the set pressure, the booster pump is started, and at the same time, the outlet vent valve of the booster pump is opened, and the pressure of each reaction container is reduced to normal pressure; Then, hydrogen is introduced into the main reactor, the second reactor and the silane buffer tank, and after the pressure rises to the set pressure, the booster pump is started, and at the same time, the outlet vent valve of the booster pump is opened, and the pressure of each reaction container is reduced to normal pressure; (2) Material input Isolate the main reactor and the second reactor, and continuously introduce nitrogen into the two reactors for displacement, then input materials into the main reactor and the second reactor, respectively, which include tetrahydrofuran and lithium aluminum hydride, and start the stirring device arranged at the top of the main reactor and the second reactor to mix the raw materials uniformly; (3) Stirring and displacement Isolate the main reactor and the second reactor, and use hydrogen to displace the two reactors, respectively; (4) Introduce silicon tetrafluoride Open the silicon tetrafluoride feeding valve and introduce silicon tetrafluoride into the main reactor; (5) Silane condensation Silane is generated in the main reactor after the introduction of silicon tetrafluoride, the silane mixed with organic matter is introduced into the second reactor, the organic matter in the main reactor is condensed, the unreacted silicon tetrafluoride in the main reactor is further reacted, and the generated organic matter in the second reactor is continuously condensed by the condenser and flows back to the second reactor through the reflux pipe; (6) Silane collection The silane from the condenser enters the silane buffer tank, and when the pressure in the silane buffer tank rises, it is extracted by the booster pump and sent to the silane steel bottle.

2. The method for preparing high purity silane for small scale laboratory apparatus according to claim 1, wherein: The main reactor and the second reactor adopt a series structure, the silicon tetrafluoride feeding pipeline of the main reactor is an insertion pipe, the silane outlet pipeline of the main reactor is a gas phase pipe, the silane feeding pipeline of the second reactor is an insertion pipe, and the silane outlet pipeline of the second reactor is a gas phase pipe.

3. The method of claim 1, wherein the method is suitable for use in a small scale laboratory device. The condenser uses external refrigeration equipment for refrigeration, and the temperature range is-55℃~-110℃.

4. The method of claim 1, wherein the method is suitable for use in a small scale laboratory device. In step (1), the inert gas is nitrogen, helium or argon.

5. The method of claim 1, wherein the method is suitable for use in a small scale laboratory device. In step (2), the volume of the input material is 60%~80% of the liquid level of the reactor, and the concentration of lithium aluminum hydride is 10%~15%.

6. The method of claim 1, wherein the method is suitable for use in a small scale laboratory device. The stirring device adopts a paddle stirrer, an anchor stirrer or a frame stirrer.

7. The method of claim 1, wherein the method is suitable for use in a small scale laboratory device. The bottom of the main reactor and the second reactor is provided with a jacket through which a cooling medium passes.

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