Silicon tetrafluoride reduction method process

Abstract

The invention discloses a silicon tetrafluoride reduction process and application of sodium aluminum hydride wrapped by linear polymer resin to isolate outside air in the silicon tetrafluoride reduction process. The silicon tetrafluoride reduction process comprises the following steps: preparing a sodium aluminum hydride solution: measuring a required amount of sodium aluminum hydride which is wrapped by linear polymer resin to isolate outside air, and dissolving the sodium aluminum hydride in an organic solvent to obtain the sodium aluminum hydride solution; and reacting silicon tetrafluoride with the sodium aluminum hydride solution. The feeding safety of the sodium aluminum hydride can be guaranteed, the sodium aluminum hydride is prevented from being in contact with air to cause failure, the required sodium aluminum hydride can be accurately measured according to the designed amount, and the accuracy of the feeding ratio of the reaction raw materials in the silicon tetrafluoride reduction process is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, in particular to a silicon tetrafluoride reduction process and application of sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air in the silicon tetrafluoride reduction process. Background Art

[0002] In the silicon tetrafluoride reduction process, sodium aluminum hydride needs to be put into a solvent to react with silicon tetrafluoride. For example, the patent specification with publication number CN102491339A discloses a method for preparing silane by reacting sodium aluminum hydride with silicon tetrafluoride. For another example, the patent specification with publication number CN101531367A discloses an alkane production process, in which a sodium aluminum hydride solution passes through a first reactor and a second reactor in sequence, and gaseous silicon tetrafluoride passes through the second reactor and the first reactor in sequence, and the sodium aluminum hydride solution is a diethylene glycol dimethyl ether solution of sodium aluminum hydride; the silane production process provided by the patented technology utilizes a sodium aluminum hydride solution and silicon tetrafluoride to directly react to generate silane.

[0003] The preparation of sodium aluminum hydride solution is an important step in the silicon tetrafluoride reduction process. In actual operation, sodium aluminum hydride will be oxidized and then spontaneously combust when directly exposed to the air, which poses a great safety hazard. Therefore, in the traditional process, when sodium aluminum hydride is added to the solvent, nitrogen is usually introduced to avoid such safety hazards, but this method cannot completely isolate the sodium aluminum hydride from the air, and because the amount of sodium aluminum hydride needs to be weighed, this will increase the time that the sodium aluminum hydride is in contact with the air, thereby causing some of the sodium aluminum hydride to fail, and the weighing results are inaccurate and inconsistent with the expected amount.

[0004] Therefore, in the current silicon tetrafluoride reduction process, there are safety risks in the feeding of sodium aluminum hydride, oxidation failure of some sodium aluminum hydride, and difficulty in accurately weighing the designed amount. Summary of the invention

[0005] In view of the above technical problems and the shortcomings in the art, the present invention provides a silicon tetrafluoride reduction process and the use of sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air in the silicon tetrafluoride reduction process.

[0006] Linear polymer resin has good chemical stability, low cost, can be well isolated from air, can be formed on the surface of sodium aluminum hydride finished product by coating and other methods, and can also form a linear polymer resin protective layer in situ during the preparation of sodium aluminum hydride. And, linear polymer resin will not react with sodium aluminum hydride. In addition, linear polymer resin such as polystyrene resin and linear polyurethane can be well dissolved in a mixed solution of toluene and ethylene glycol dimethyl ether, and then can be perfectly connected and applied to the silicon tetrafluoride reduction process. Therefore, polystyrene resin / linear polyurethane and other linear polymer resins are wrapped on the surface of sodium aluminum hydride to form an air isolation layer, which can well solve the problems mentioned in the above-mentioned background technology, ensure the safety of sodium aluminum hydride feeding, avoid sodium aluminum hydride from contacting with air and losing efficacy, can accurately measure required sodium aluminum hydride according to the designed amount, and ensure the accuracy of the raw material feed ratio of the silicon tetrafluoride reduction process reaction.

[0007] The specific technical solutions are as follows:

[0008] In a first aspect, the present invention provides a silicon tetrafluoride reduction process, comprising:

[0009] Preparation of sodium aluminum hydride solution: taking a required amount of sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air, and dissolving it in an organic solvent to obtain a sodium aluminum hydride solution;

[0010] Silicon tetrafluoride reacts with sodium aluminum hydride solution.

[0011] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution, but are merely further supplements or preferences. Under the premise that there are no technical or logical contradictions, each optional method can be combined with the above-mentioned overall solution separately, and multiple optional methods can also be combined.

[0012] The silicon tetrafluoride reduction process described in the first aspect can prepare the sodium aluminum hydride solution in a water vapor-containing environment, such as an air environment. This is an important feature of the silicon tetrafluoride reduction process of the present invention. In the sodium aluminum hydride material preparation, especially the material dissolution process, no inert gas protection such as nitrogen is required, which reduces equipment requirements and simplifies operation.

[0013] In some preferred examples, in the silicon tetrafluoride reduction process described in the first aspect, the linear polymer resin includes at least one of polyethylene resin, polypropylene resin, polyvinyl chloride resin, polystyrene resin, polymethyl methacrylate resin, polycarbonate resin, nylon resin, polyester resin, polytetrafluoroethylene resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, and linear polyurethane. The linear polymer resins listed above will not react with sodium aluminum hydride, which has strong reducing properties, and can have good bonding ability with sodium aluminum hydride, thereby firmly covering the surface of sodium aluminum hydride, and these linear polymer resins can form a compact wrapping layer to isolate the outside air from contacting the internal sodium aluminum hydride.

[0014] In the silicon tetrafluoride reduction process described in the first aspect, the degree to which the sodium aluminum hydride is wrapped by the linear polymer resin, such as the thickness of the linear polymer resin wrapping layer, the amount of the linear polymer resin wrapped, etc., is such that it can effectively isolate the outside air as the minimum requirement. In some embodiments, based on the total mass of the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air as 100%, the mass percentage of the linear polymer resin can be 20% to 25%, and the mass percentage of the sodium aluminum hydride can be 75% to 80%.

[0015] In some preferred examples, in the silicon tetrafluoride reduction process described in the first aspect, the organic solvent includes toluene and ethylene glycol dimethyl ether. The mixed solvent of toluene and ethylene glycol dimethyl ether can effectively dissolve the above-listed linear polymer resins and sodium aluminum hydride. The above-listed linear polymer resins can be fully dissolved in the mixed solvent of toluene and ethylene glycol dimethyl ether, completely releasing the internal sodium aluminum hydride, and will not cause the sodium aluminum hydride to be blocked, unable to dissolve and thus unable to react with silicon tetrafluoride. Furthermore, in the organic solvent, the volume ratio of toluene and ethylene glycol dimethyl ether can be 3:5 to 9, for example, 1:2, etc.

[0016] In some embodiments, in the process of preparing the sodium aluminum hydride solution by the silicon tetrafluoride reduction process described in the first aspect, the dissolution temperature can be 32 to 37°C. The silicon tetrafluoride reduction process of the present invention can quickly and completely dissolve the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air under mild conditions, and the operation is simple and the equipment requirements are low. For example: the protective layer formed by the polystyrene resin wrapping can be fully dissolved in a mixed solvent of toluene and ethylene glycol dimethyl ether at 37°C, and the dissolution time of the sodium aluminum hydride wrapped by the polystyrene resin to isolate the outside air can be as short as less than 4 hours; the protective layer formed by the linear polyurethane wrapping can be fully dissolved in a mixed solvent of toluene and ethylene glycol dimethyl ether at 34°C, and the dissolution time of the sodium aluminum hydride wrapped by the linear polyurethane to isolate the outside air can be as short as less than 4 hours.

[0017] As a general inventive concept, in a second aspect, the present invention also provides the use of the sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air in a silicon tetrafluoride reduction process.

[0018] In some embodiments, the application described in the second aspect can be to dissolve sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air in an organic solvent to obtain a sodium aluminum hydride solution, and then react the obtained sodium aluminum hydride solution with silicon tetrafluoride. Wherein:

[0019] i) The organic solvent preferably includes toluene and ethylene glycol dimethyl ether. The mixed solvent of toluene and ethylene glycol dimethyl ether can effectively dissolve sodium aluminum hydride and the preferred linear polymer resin of the present invention. The preferred linear polymer resin of the present invention can be fully dissolved in the mixed solvent of toluene and ethylene glycol dimethyl ether, completely releasing the internal sodium aluminum hydride, and will not cause the sodium aluminum hydride to be blocked, unable to dissolve and thus unable to react with silicon tetrafluoride. Furthermore, in the organic solvent, the volume ratio of toluene and ethylene glycol dimethyl ether can be 3:5 to 9, for example, 1:2, etc.

[0020] ii) In the process of dissolving the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air in the organic solvent to obtain the sodium aluminum hydride solution, the dissolution temperature can be 32-37°C. The application of the present invention can quickly and completely dissolve the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air under mild conditions, and the operation is simple and the equipment requirements are low. For example: the protective layer formed by the polystyrene resin can be fully dissolved in a mixed solvent of toluene and ethylene glycol dimethyl ether at 37°C, and the dissolution time of the sodium aluminum hydride wrapped by the polystyrene resin to isolate the outside air can be shortened to less than 4 hours; the protective layer formed by the linear polyurethane wrapping can be fully dissolved in a mixed solvent of toluene and ethylene glycol dimethyl ether at 34°C, and the dissolution time of the sodium aluminum hydride wrapped by the linear polyurethane to isolate the outside air can be shortened to less than 4 hours.

[0021] The application described in the second aspect can be to dissolve sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air in an organic solvent in a water vapor-containing environment, such as an air environment, to obtain a sodium aluminum hydride solution. That is, the present invention uses sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air as a raw material, so that the present invention can be applied in the sodium aluminum hydride material preparation process without the need for inert gas protection such as nitrogen, thereby reducing equipment requirements and simplifying operations.

[0022] The application described in the second aspect can refer to the silicon tetrafluoride reduction process described in the first aspect to select and optimize the technical solution.

[0023] As one of the examples, in some preferred examples, in the application described in the second aspect, the linear polymer resin includes at least one of polyethylene resin, polypropylene resin, polyvinyl chloride resin, polystyrene resin, polymethyl methacrylate resin, polycarbonate resin, nylon resin, polyester resin, polytetrafluoroethylene resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, and linear polyurethane. The linear polymer resins listed above will not react with sodium aluminum hydride with strong reducing properties, and can have good bonding ability with sodium aluminum hydride, thereby firmly covering the surface of sodium aluminum hydride, and these linear polymer resins can form a compact wrapping layer to isolate the outside air from contacting the internal sodium aluminum hydride.

[0024] As another example, in some embodiments, in the application described in the second aspect, based on the total mass of the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air as 100%, the mass percentage of the linear polymer resin is 20% to 25%, and the mass percentage of the sodium aluminum hydride is 75% to 80%.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The invention uses linear polymer resin to wrap sodium aluminum hydride to isolate it from air, so that the sodium aluminum hydride raw material can be stored for a long time and transported safely, reducing the environmental requirements for storage and transportation, and the sodium aluminum hydride wrapped by the linear polymer resin can be smoothly dissolved in an organic solvent to form a sodium aluminum hydride solution, which is conveniently used in a silicon tetrafluoride reduction process.

[0027] The sodium aluminum hydride wrapped by the linear polymer resin of the present invention has stable performance and will not fail. The present invention has practical application value, is conducive to optimizing the silicon tetrafluoride reduction process, makes the material preparation process of the silicon tetrafluoride reduction process not require strict inert gas protection requirements, simplifies the operation, reduces equipment requirements and costs, and can make the sodium aluminum hydride preparation amount more accurate. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0029] The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers.

[0030] In the present invention, the preparation process of sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air can be performed with reference to the prior art (such as the patent specification with publication number CN117550553A, etc.) based on the specific conditions such as the shape and size of the sodium aluminum hydride raw material, or can be operated using the method described below.

[0031] For example, sodium aluminum hydride is a cylindrical white block solid, which is not very soluble in a single toluene or ethylene glycol dimethyl ether solvent, and the required dissolution time is relatively long. In this regard, a linear polymer resin can be dissolved in a solvent at a certain temperature, and then the obtained linear polymer resin solution can be coated on the surface of sodium aluminum hydride. Among them, the certain temperature can be 30-45°C, for example: a linear polymer resin polystyrene can be smoothly dissolved in toluene at 35°C and then coated on the surface of sodium aluminum hydride to form protection; a linear polymer resin linear polyurethane can be smoothly dissolved in ethylene glycol dimethyl ether at 40°C and then coated on the surface of sodium aluminum hydride to form protection. The solvent for dissolving the linear polymer resin can be at least one of tetrahydrofuran, toluene, ethylene glycol dimethyl ether, etc. After the coating is completed, the residual solvent in the surface coating layer of sodium aluminum hydride can be removed by vacuuming, and the linear polymer resin gradually forms a protective film on the solid surface of sodium aluminum hydride.

[0032] Embodiment 1:

[0033] The amount of sodium aluminum hydride required for the reaction was calculated to be 300 g. 90 g of polystyrene resin was weighed and dissolved in 150 mL of toluene solvent at 45°C. The polystyrene resin was completely dissolved in toluene within 30 minutes. The dissolved polystyrene-toluene solution was coated on the surface of 300 g of sodium aluminum hydride cylindrical white block solid. The toluene solvent was extracted in a glove box by vacuuming for 30 minutes. Polystyrene gradually formed a protective film on the surface of the sodium aluminum hydride solid. The sodium aluminum hydride solid wrapped by polystyrene was put into a mixture of toluene and ethylene glycol dimethyl ether (wherein the volume ratio of toluene to ethylene glycol dimethyl ether was 3:5). The sodium aluminum hydride solid was fully dissolved in the mixture of toluene and ethylene glycol dimethyl ether at 37°C within 4 hours. The obtained sodium aluminum hydride solution was reacted with silicon tetrafluoride.

[0034] Embodiment 2:

[0035] Calculate the amount of sodium aluminum hydride required for the reaction to be 250 g, weigh 75 g of polystyrene resin and dissolve it in 140 mL of toluene solvent at 40°C. The polystyrene resin is completely dissolved in toluene within 25 minutes. Apply the dissolved polystyrene-toluene solution on the surface of 250 g of sodium aluminum hydride cylindrical white block solid, evacuate the glove box for 30 minutes to extract the toluene solvent, and polystyrene forms a protective film on the surface of the sodium aluminum hydride solid. Put the sodium aluminum hydride solid wrapped by polystyrene into a mixture of toluene and ethylene glycol dimethyl ether (wherein the volume ratio of toluene to ethylene glycol dimethyl ether is 1:3), and the sodium aluminum hydride solid is fully dissolved in the mixture of toluene and ethylene glycol dimethyl ether at 37°C within 3.5 hours. The obtained sodium aluminum hydride solution is reacted with silicon tetrafluoride.

[0036] Embodiment 3:

[0037] The amount of sodium aluminum hydride required for the reaction was calculated to be 280 g. 84 g of linear polyurethane was dissolved in 140 mL of ethylene glycol dimethyl ether solvent at 42°C. The linear polyurethane was completely dissolved in the ethylene glycol dimethyl ether solvent within 28 minutes. The dissolved linear polyurethane-ethylene glycol dimethyl ether solution was coated on the surface of 280 g of cylindrical white block solid of sodium aluminum hydride. The ethylene glycol dimethyl ether solvent was extracted by vacuuming in a glove box for 30 minutes. The linear polyurethane formed a protective film on the surface of the sodium aluminum hydride solid. The sodium aluminum hydride solid wrapped by the linear polyurethane was put into a mixture of toluene and ethylene glycol dimethyl ether (wherein the volume ratio of toluene to ethylene glycol dimethyl ether was 1:3). The sodium aluminum hydride solid was fully dissolved in the mixture of toluene and ethylene glycol dimethyl ether at 35°C within 3.6 hours. The obtained sodium aluminum hydride solution was reacted with silicon tetrafluoride.

[0038] Embodiment 4:

[0039] Calculate the amount of sodium aluminum hydride required for the reaction to be 200 g, dissolve 60 g of linear polyurethane with 120 mL of ethylene glycol dimethyl ether solvent at 40°C, and completely dissolve the linear polyurethane in the ethylene glycol dimethyl ether solvent within 25 minutes. Coat the dissolved linear polyurethane-ethylene glycol dimethyl ether solution on the surface of 200 g of cylindrical white block solid of sodium aluminum hydride, and vacuumize the glove box for 30 minutes to extract the ethylene glycol dimethyl ether solvent. The linear polyurethane forms a protective film on the surface of the sodium aluminum hydride solid. Put the sodium aluminum hydride solid wrapped by the linear polyurethane into a mixture of toluene and ethylene glycol dimethyl ether (wherein the volume ratio of toluene to ethylene glycol dimethyl ether is 1:2), and the sodium aluminum hydride solid is fully dissolved in the mixture of toluene and ethylene glycol dimethyl ether at 34°C within 3.5 hours. The obtained sodium aluminum hydride solution is reacted with silicon tetrafluoride.

[0040] In summary, the present invention can effectively isolate the air from contact with sodium aluminum hydride, reduce the problem of inaccurate amount of sodium aluminum hydride actually added due to failure of sodium aluminum hydride, and at the same time speed up the feeding speed without the need for nitrogen protection.

[0041] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A silicon tetrafluoride reduction process, characterized in that: include: Preparation of sodium aluminum hydride solution: taking a required amount of sodium aluminum hydride wrapped by a linear polymer resin to isolate the outside air, and dissolving it in an organic solvent to obtain a sodium aluminum hydride solution; Silicon tetrafluoride reacts with sodium aluminum hydride solution.

2. The silicon tetrafluoride reduction process according to claim 1, characterized in that: Prepare a sodium aluminum hydride solution in a water vapor environment such as an air environment.

3. The silicon tetrafluoride reduction process according to claim 1, characterized in that: The linear polymer resin includes at least one of polyethylene resin, polypropylene resin, polyvinyl chloride resin, polystyrene resin, polymethyl methacrylate resin, polycarbonate resin, nylon resin, polyester resin, polytetrafluoroethylene resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, and linear polyurethane.

4. The silicon tetrafluoride reduction process according to claim 1 or 3, characterized in that: Taking the total mass of the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air as 100%, the mass percentage of the linear polymer resin is 20% to 25%, and the mass percentage of the sodium aluminum hydride is 75% to 80%.

5. The silicon tetrafluoride reduction process according to claim 1, characterized in that: The organic solvent includes toluene and ethylene glycol dimethyl ether.

6. The silicon tetrafluoride reduction process according to claim 5, characterized in that: In the organic solvent, the volume ratio of toluene to ethylene glycol dimethyl ether is 3:5-9.

7. The silicon tetrafluoride reduction process according to claim 1, characterized in that: During the preparation of the sodium aluminum hydride solution, the dissolution temperature is 32-37°C.

8. Application of sodium aluminum hydride wrapped by linear polymer resin to isolate it from the outside air in the silicon tetrafluoride reduction process.

9. The use according to claim 8, characterized in that: The linear polymer resin includes at least one of polyethylene resin, polypropylene resin, polyvinyl chloride resin, polystyrene resin, polymethyl methacrylate resin, polycarbonate resin, nylon resin, polyester resin, polytetrafluoroethylene resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, and linear polyurethane.

10. The use according to claim 8 or 9, characterized in that: Taking the total mass of the sodium aluminum hydride wrapped by the linear polymer resin to isolate the outside air as 100%, the mass percentage of the linear polymer resin is 20% to 25%, and the mass percentage of the sodium aluminum hydride is 75% to 80%.