Purification method of bis (diethylamino) silane

Abstract

The invention discloses a purification method of di (diethylamino) silane, which comprises the following steps: S1, adding industrial-grade di (diethylamino) silane into a first rectifying tower, carrying out light component removal treatment, and leading out a light component removed product from the bottom of the tower; s2, introducing the light component-removed product into a second rectifying tower, carrying out heavy component removal treatment, and leading out the heavy component-removed product from the tower top; and S3, introducing the de-heavy product into a condenser, condensing the de-heavy product into a liquid state, introducing the liquid state into an adsorption tank, carrying out adsorption treatment, and introducing the liquid state into a finished product tank through a filter screen after the treatment is completed, so as to obtain the high-purity di (diethylamino) silane. Wherein the adsorption tank in the step S3 is filled with a composite modified adsorbent. According to the method, metal ion impurities, tri (diethylamino) silane, mono (diethylamino) silane and phosphorus-containing impurities in di (diethylamino) silane can be removed by adding a specific adsorbent, so that the purity of the obtained di (diethylamino) silane reaches 99.99 wt% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of bis(diethylamino)silane purification, and in particular relates to a method for purifying bis(diethylamino)silane. Background Art

[0002] Bis(diethylamino)silane is an important organosilicon compound with the molecular formula ((C2H5)2N)2SiH2. This compound is a colorless, transparent liquid at room temperature with a boiling point of 189-190°C (under standard atmospheric pressure). As a compound with special chemical properties, it is extremely sensitive to air and moisture, and is volatile and has a special odor. In terms of chemical properties, this compound exhibits significant hydrolysis properties and is reducible. The silicon-hydrogen bonds and amino groups in its molecules are highly chemically active and can undergo various types of chemical reactions.

[0003] Due to its unique molecular structure and chemical properties, bis(diethylamino)silane is widely used in modern industry, especially in semiconductor manufacturing, nanomaterial synthesis and surface modification. It is mainly used as a silicon source precursor in the chemical vapor deposition (CVD) process to prepare various silicon-based materials and functional coatings. In addition, it also has important applications in catalyst synthesis and the preparation of organosilicon compounds. Considering its environmentally sensitive properties, special protective measures need to be taken during use and storage, such as inert atmosphere protection and strict temperature control.

[0004] Organic aminosilane precursors can be used in various deposition processes, including but not limited to atomic layer deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition and atmospheric pressure chemical vapor deposition. Several classes of compounds can be used as precursors for silicon-containing films (for example, but not limited to, silicon oxide or silicon nitride films). Examples of these compounds suitable for use as precursors include silanes, chlorosilanes, polysilazanes, aminosilanes and azidosilanes. Inert carrier gases or diluents (for example, but not limited to, helium, hydrogen, nitrogen, etc.) are also used to transport the precursor to the reaction chamber. With the development of science and technology, the high purity demand for this compound is increasing, and its application field is also expanding, and related green synthesis method research and performance optimization work continue to advance.

[0005] Chinese patent CN108084219A discloses a method for synthesizing di(diethylamino)silane, using dichlorosilane and diethylamine as raw materials, hexane as solvent, and catalyzing di(diethylamino)silane under a temperature of 40-60°C with a kaolin catalyst, with a yield of up to 85%. Although this method improves the yield to a certain extent, the use of kaolin catalyst greatly increases the cost and causes an additional burden on environmental pollution. In addition, more organic compounds are added during the preparation of the kaolin catalyst, which may affect the purity of the final di(diethylamino)silane product.

[0006] Chinese patent application CN107406466A discloses a method for manufacturing dialkylaminosilane. In the method synthesized by the reaction of chlorosilane and dialkylamine, in addition to the target dialkylaminosilane, a large amount of dialkylamine hydrochloride is also produced as a by-product. Therefore, when obtaining the target dialkylaminosilane, it is necessary to prevent the volume efficiency from being reduced due to a large amount of solvent, thereby cheaply manufacturing in large quantities. As a solvent for reacting dialkylamine with chlorosilane, a non-proton polar solvent with high solubility for the dialkylamine hydrochloride and metal chloride produced as a by-product in the reaction, and a straight-chain hydrocarbon or branched hydrocarbon with high solubility and difficulty in dissolving halogen compounds of dialkylaminosilane are used, thereby dialkylaminosilane with low halogen content can be manufactured with high volume efficiency. Rectification is performed, and high-quality dialkylaminosilane with low halogen content (chlorine) component can be obtained.

[0007] The purification of bis(diethylamino)silane used in existing patents and literature technologies mostly uses distillation. The purity of bis(diethylamino)silane is difficult to exceed 99.99%. In addition, the by-products tri(diethylamino)silane and mono(diethylamino)silane in bis(diethylamino)silane have similar boiling points to bis(diethylamino)silane, so it is not easy to completely remove them by distillation. Summary of the invention

[0008] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for purifying di(diethylamino)silane. The method can remove metal ion impurities, tri(diethylamino)silane, mono(diethylamino)silane and phosphorus-containing impurities in di(diethylamino)silane by adding a specific adsorbent, so that the purity of the obtained di(diethylamino)silane reaches more than 99.99wt%.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for purifying bis(diethylamino)silane comprises the following steps:

[0011] S1, adding industrial-grade di(diethylamino)silane into the first distillation tower, performing light removal treatment, and obtaining a light-removed product which is drawn out from the bottom of the tower;

[0012] S2, introducing the product after light removal into the second distillation tower, performing heavy removal treatment, and obtaining the product after heavy removal and drawing it out from the top of the tower;

[0013] S3, introducing the deweighted product into a condenser, condensing it into a liquid state and introducing it into an adsorption tank for adsorption treatment, and after the treatment is completed, passing through a filter screen into a finished product tank to obtain high-purity di(diethylamino)silane;

[0014] Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent.

[0015] Preferably, in step S1, the top pressure of the first distillation tower is 0.08-0.13 MPa, the top temperature is 175-185°C, the bottom pressure is 0.05-0.1 MPa, the bottom temperature is 190-200°C, and the theoretical plate number is 50-70.

[0016] Preferably, in step S2, the top pressure of the second distillation tower is 0.12-0.17 MPa, the top temperature is 192-197° C., the bottom pressure is 0.15-0.2 MPa, the bottom temperature is 205-215° C., and the theoretical plate number is 80-90.

[0017] Preferably, the volume of the composite modified adsorbent in step S3 accounts for 15-20% of the total volume of the adsorption tank.

[0018] Preferably, the temperature of the adsorption treatment in step S3 is 50-60° C. and the time is 1-2 h.

[0019] Preferably, the method for preparing the composite modified adsorbent in step S2 comprises the following steps:

[0020] (a) Preparation of modified molecular sieve: adding MCM-41 molecular sieve to sodium hydroxide solution for impregnation treatment, filtering, drying and calcining after the impregnation to obtain a pretreated molecular sieve; adding the pretreated molecular sieve to toluene, then adding γ-aminopropyltriethoxysilane, stirring for reaction, filtering, washing and drying after the reaction to obtain a solid product, then adding the solid product to thionyl chloride for heating reaction, filtering and drying after the reaction to obtain a modified molecular sieve;

[0021] (b) adding the biomass powder to a sodium hydroxide solution, stirring and impregnating, then adding a cerium nitrate solution, performing a hydrothermal reaction, filtering, washing, drying, and calcining after the reaction is completed to obtain biochar; adding the biochar to a nitric acid / H2O2 mixed solution, performing an impregnation treatment, filtering, washing, and drying after the treatment is completed to obtain pretreated biochar;

[0022] (c) Modified biochar: adding the pretreated biochar in step (b) to an ethanol aqueous solution, then adding vinyl triethoxysilane, stirring to react, filtering, washing, and drying after the reaction is completed to obtain vinyl biochar; then adding the vinyl biochar to toluene, then adding 4-imidazole acrylic acid and azobisisobutyronitrile, and reacting at a constant temperature, filtering, washing, and drying after the reaction is completed to obtain modified biochar;

[0023] (d) Preparation of composite modified adsorbent: The modified molecular sieve and the modified biochar are uniformly mixed to obtain the composite modified adsorbent.

[0024] Preferably, the concentration of the sodium hydroxide solution in step (a) is 0.3-0.5 mol / L, the immersion temperature is 40-50°C, the time is 1-2h, the calcination temperature is 500-550°C, and the time is 0.5-1h; the mass ratio of the pretreated molecular sieve and γ-aminopropyltriethoxysilane is 50-60:8-12, the stirring reaction temperature is 70-80°C, and the time is 2-3h; the mass ratio of the solid product and thionyl chloride is 50-60:500-600, the heating reaction temperature is 60-70°C, and the time is 3-5h.

[0025] In the present invention, the MCM-41 molecular sieve is firstly treated with alkali, which can remove impurities in the molecular sieve pores and improve the adsorption capacity, and can also increase the number of hydroxyl groups on the surface of the molecular sieve, which is conducive to the subsequent reaction; then the molecular sieve is reacted with γ-aminopropyltriethoxysilane to introduce amino functional groups and improve the active sites of the molecular sieve, and finally reacted with thionyl chloride to introduce chlorine groups, so that bifunctional amino groups and chlorine groups are introduced on the surface of the molecular sieve, and the selective adsorption capacity of the molecular sieve to polar substances is improved, thereby improving the adsorption of the composite modified adsorbent to mono(diethylamino)silane.

[0026] Preferably, the concentration of the sodium hydroxide solution in step (b) is 1-2 mol / L, the temperature of the stirring and impregnation is 50-60°C, the time is 1-2h, the mass fraction of the cerium nitrate solution is 10-15%, the mass ratio of the biomass powder, the sodium hydroxide solution, and the cerium nitrate is 100:1000-1300:50-60, the temperature of the hydrothermal reaction is 130-150°C, the time is 4-6h, the temperature of the calcination is 600-700°C, and the time is 1-2h; the volume ratio of the nitric acid solution to H2O2 in the nitric acid / H2O2 mixed solution is 1:1, the mass fraction of the nitric acid solution is 5-10%, the mass fraction of the H2O2 is 10-15%, the temperature of the impregnation treatment is 50-60°C, and the time is 1-2h.

[0027] In the present invention, the biomass is subjected to an alkali activation treatment, and then cerium nitrate is added to the biomass for a hydrothermal reaction, cerium ions are introduced into the biomass, and then calcination is performed, so that the obtained biochar has better porosity. The introduction of cerium ions can enhance the coordination capacity of the biochar.

[0028] Preferably, in step (c), the mass ratio of the pretreated biochar and vinyltriethoxysilane is 50-60:8-12, the temperature of the stirring reaction is 60-70°C, and the time is 3-4h; the mass ratio of the vinyl biochar, 4-imidazole acrylic acid, and azobisisobutyronitrile is 50-60:6-9:0.5-0.8, the temperature of the isothermal reaction is 80-90°C, and the time is 2-3h.

[0029] In the present invention, the biochar is oxidized to increase the oxygen-containing functional groups on its surface and improve the reaction activity. It is then reacted with vinyltriethoxysilane to introduce carbon-carbon double bonds on the surface of the biochar, which is beneficial to the subsequent reactions. Finally, the vinyl biochar is reacted with 4-imidazole acrylic acid to introduce imidazole groups on the biochar, thereby increasing the adsorption capacity of the biochar for metal ions and phosphorus-containing groups.

[0030] Preferably, the mass ratio of the modified molecular sieve to the modified biochar in step (d) is 5-10:5-10.

[0031] In the present invention, the modified molecular sieve is compounded with the modified biochar to synergistically adsorb mono(diethylamino)silane, tri(diethylamino)silane, metal ions and phosphorus-containing groups in di(diethylamino)silane, thereby improving the purity of the di(diethylamino)silane product.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The method for purifying di(diethylamino)silane provided by the present invention first removes impurities with lower boiling points in di(diethylamino)silane by distillation and then removes impurities with higher boiling points by distillation and finally removes impurities such as tri(diethylamino)silane and mono(diethylamino)silane with similar boiling points during the distillation process by adsorption treatment and addition of a specific composite modified adsorbent, so that the purity of the final product di(diethylamino)silane reaches more than 99.99wt%.

[0034] (2) The present invention provides a method for purifying di(diethylamino)silane. The composite modified adsorbent achieves the selective adsorption of impurities such as tri(diethylamino)silane, mono(diethylamino)silane and metal ions through the synergistic effect of two adsorbents, modified molecular sieve and modified biochar. The working principle is based on the differences in molecular size, polarity and coordination ability between di(diethylamino)silane and impurity molecules: the modified molecular sieve mainly adsorbs small molecules with small polarity through the synergistic effect of controllable pore size and surface amino and chlorine groups. Strong mono(diethylamino)silane; the modified biochar selectively adsorbs tri(diethylamino)silane with large molecular volume and strong coordination ability through multi-level pore structure and surface functional group regulation and cerium ion coordination sites; at the same time, the 4-imidazole acrylic acid introduced into the modified biochar makes the imidazole group contained in it have a strong complexing ability for metal ions, thereby removing the metal ions in di(diethylamino)silane, and can also coordinate and complex with phosphorus-containing impurities, thereby removing phosphorus-containing impurities in di(diethylamino)silane. The target product di(diethylamino)silane has relatively weak interaction with the composite modified adsorbent due to its moderate molecular size, moderate polarity, and balanced coordination ability, and will not be significantly adsorbed. The present invention uses the pore structure and chemical properties of the composite modified adsorbent surface to precisely design the molecular size matching degree with di(diethylamino)silane, and the surface interaction is moderate, thereby achieving directional separation of specific impurities, thereby improving the purity of the di(diethylamino)silane product. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the nuclear magnetic spectrum (NMR) of the di(diethylamino)silane purified in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The MCM-41 molecular sieve was purchased from Suzhou Beike Nanotechnology Co., Ltd., with an average particle size of 20 μm, an average pore size of 3.6 nm, and a specific surface area (1000 m 2 / g), pore capacity (0.7mL / g).

[0038] Example 1

[0039] A method for purifying bis(diethylamino)silane comprises the following steps:

[0040] S1, adding industrial-grade di(diethylamino)silane to the first distillation tower for light removal treatment, the top pressure of the distillation tower is 0.1MPa, the top temperature is 180°C, the bottom pressure is 0.08MPa, the bottom temperature is 195°C, the theoretical plate number is 60, and the product after light removal is drawn out from the bottom of the tower;

[0041] S2, the product after light removal is introduced into the second distillation tower for heavy removal treatment, the top pressure of the distillation tower is 0.15MPa, the top temperature is 195°C, the bottom pressure is 0.18MPa, the bottom temperature is 210°C, the theoretical plate number is 85, and the product after heavy removal is drawn out from the top of the tower;

[0042] S3, introducing the deweighted product into a condenser, condensing it into a liquid state and introducing it into an adsorption tank for adsorption treatment. The temperature of the adsorption treatment is 55° C. and the time is 1.5 h. After the treatment is completed, it passes through a filter screen and enters a finished product tank to obtain high-purity di(diethylamino)silane; Figure 1 Shown is the NMR spectrum of the high-purity bis(diethylamino)silane of this example.

[0043] Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent, and the volume of the composite modified adsorbent accounts for 18% of the total volume of the adsorption tank.

[0044] The method for preparing the composite modified adsorbent in step S3 comprises the following steps:

[0045] (a) Preparation of modified molecular sieve: MCM-41 molecular sieve was added to a sodium hydroxide solution with a concentration of 0.4 mol / L, and impregnated at 45°C for 1.5 h. After impregnation, the mixture was filtered and dried, and then calcined at 530°C for 1 h to obtain a pretreated molecular sieve; 55 g of the pretreated molecular sieve was added to 800 mL of toluene, followed by the addition of 10 g of γ-aminopropyltriethoxysilane, and stirred at 75°C for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain a solid product. Subsequently, 55 g of the solid product was added to 550 g of thionyl chloride, and reacted at 65°C for 4 h. After the reaction was completed, the mixture was filtered and dried to obtain a modified molecular sieve;

[0046] (b) adding 100 g corn straw powder to 1200 g sodium hydroxide solution with a mass fraction of 13%, stirring and impregnating at 55° C. for 1.5 h, then adding 55 g cerium nitrate solution with a mass fraction of 13%, hydrothermally reacting at 140° C. for 5 h, filtering, washing, and drying after the reaction is completed, and calcining at 650° C. for 1.5 h to obtain biochar; adding 55 g biochar to 500 mL nitric acid / H2O2 mixed solution (the volume ratio of nitric acid solution to H2O2 is 1:1, the mass fraction of the nitric acid solution is 10%, and the mass fraction of the H2O2 is 10%), impregnating at 55° C. for 1.5 h, filtering, washing, and drying after the treatment is completed to obtain pretreated biochar;

[0047] (c) Modified biochar: 55 g of the pretreated biochar in step (b) was added to 900 mL of ethanol aqueous solution (the volume fraction of ethanol was 75%), followed by the addition of 10 g of vinyl triethoxysilane, and the mixture was stirred at 65°C for 3.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain vinyl biochar; 55 g of the vinyl biochar was then added to 1 L of toluene, followed by the addition of 8 g of 4-imidazole acrylic acid and 0.5-0.8 g of azobisisobutyronitrile, and the mixture was kept at 85°C for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified biochar;

[0048] (d) Preparation of composite modified adsorbent: 80 g of modified molecular sieve and 70 g of modified biochar were uniformly mixed to obtain the composite modified adsorbent.

[0049] Example 2

[0050] A method for purifying bis(diethylamino)silane comprises the following steps:

[0051] S1, adding industrial-grade di(diethylamino)silane to the first distillation tower for light removal treatment, the top pressure of the distillation tower is 0.08MPa, the top temperature is 175°C, the bottom pressure is 0.05MPa, the bottom temperature is 190°C, the theoretical plate number is 50, and the product after light removal is drawn out from the bottom of the tower;

[0052] S2, the product after light removal is introduced into the second distillation tower for heavy removal treatment, the top pressure of the distillation tower is 0.12MPa, the top temperature is 192°C, the bottom pressure is 0.15MPa, the bottom temperature is 205°C, the theoretical plate number is 80, and the product after heavy removal is drawn out from the top of the tower;

[0053] S3, introducing the deweighted product into a condenser, condensing it into a liquid state and introducing it into an adsorption tank for adsorption treatment, the temperature of the adsorption treatment is 50°C, the time is 2h, and after the treatment is completed, it passes through a filter screen into a finished product tank to obtain high-purity di(diethylamino)silane;

[0054] Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent, and the volume of the composite modified adsorbent accounts for 15% of the total volume of the adsorption tank.

[0055] The method for preparing the composite modified adsorbent in step S3 comprises the following steps:

[0056] (a) Preparation of modified molecular sieve: MCM-41 molecular sieve was added to a sodium hydroxide solution with a concentration of 0.3 mol / L, and impregnated at 40°C for 2 h. After impregnation, the mixture was filtered and dried, and then calcined at 500°C for 1 h to obtain a pretreated molecular sieve; 50 g of the pretreated molecular sieve was added to 800 mL of toluene, followed by 8 g of γ-aminopropyltriethoxysilane, and stirred at 70°C for 3 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain a solid product. Subsequently, 50 g of the solid product was added to 500 g of thionyl chloride, and reacted at 60°C for 5 h. After the reaction was completed, the mixture was filtered and dried to obtain a modified molecular sieve;

[0057] (b) Add 100 g corn stalk powder to 1000 g sodium hydroxide solution with a mass fraction of 15%, stir and soak at 50° C. for 2 h, then add 50 g cerium nitrate solution with a mass fraction of 15%, hydrothermally react at 130° C. for 6 h, filter, wash and dry after the reaction is completed, and calcine at 600° C. for 2 h to obtain biochar; add 50 g biochar to 500 mL nitric acid / H2O2 mixed solution (the volume ratio of nitric acid solution to H2O2 is 1:1, the mass fraction of the nitric acid solution is 5%, and the mass fraction of the H2O2 is 15%), soak at 50° C. for 1 h, filter, wash and dry after the treatment is completed to obtain pretreated biochar;

[0058] (c) Modified biochar: 50 g of the pretreated biochar in step (b) was added to 900 mL of ethanol aqueous solution (the volume fraction of ethanol was 70%), followed by the addition of 8 g of vinyl triethoxysilane, and the mixture was stirred at 60°C for 4 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain vinyl biochar; then 50 g of the vinyl biochar was added to 1 L of toluene, followed by the addition of 6 g of 4-imidazole acrylic acid and 0.5 g of azobisisobutyronitrile, and the mixture was kept at 80°C for 3 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified biochar;

[0059] (d) Preparation of composite modified adsorbent: 50 g of modified molecular sieve and 100 g of modified biochar were uniformly mixed to obtain the composite modified adsorbent.

[0060] Example 3

[0061] A method for purifying bis(diethylamino)silane comprises the following steps:

[0062] S1, adding industrial-grade di(diethylamino)silane to the first distillation tower for light removal treatment, the top pressure of the distillation tower is 0.13MPa, the top temperature is 185°C, the bottom pressure is 0.1MPa, the bottom temperature is 200°C, the theoretical plate number is 70, and the product after light removal is drawn out from the bottom of the tower;

[0063] S2, the product after light removal is introduced into the second distillation tower for heavy removal treatment, the top pressure of the distillation tower is 0.17MPa, the top temperature is 197°C, the bottom pressure is 0.2MPa, the bottom temperature is 215°C, the theoretical plate number is 90, and the product after heavy removal is drawn out from the top of the tower;

[0064] S3, introducing the deweighted product into a condenser, condensing it into a liquid and introducing it into an adsorption tank for adsorption treatment. The adsorption treatment temperature is 60° C. and the time is 1 hour. After the treatment is completed, it passes through a filter screen into a finished product tank to obtain high-purity di(diethylamino)silane;

[0065] Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent, and the volume of the composite modified adsorbent accounts for 20% of the total volume of the adsorption tank.

[0066] The method for preparing the composite modified adsorbent in step S3 comprises the following steps:

[0067] (a) Preparation of modified molecular sieve: MCM-41 molecular sieve was added to a sodium hydroxide solution with a concentration of 0.5 mol / L, and impregnated at 50°C for 1 h. After impregnation, the mixture was filtered and dried, and then calcined at 550°C for 0.5 h to obtain a pretreated molecular sieve; 60 g of the pretreated molecular sieve was added to 800 mL of toluene, followed by 12 g of γ-aminopropyltriethoxysilane, and stirred at 80°C for 2 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain a solid product. Subsequently, 60 g of the solid product was added to 600 g of thionyl chloride, and reacted at 70°C for 3 h. After the reaction was completed, the mixture was filtered and dried to obtain a modified molecular sieve;

[0068] (b) Add 100 g corn straw powder to 1300 g of 10% sodium hydroxide solution, stir and soak at 60°C for 1 h, then add 60 g of 10% cerium nitrate solution, hydrothermally react at 150°C for 4 h, filter, wash and dry after the reaction, and calcine at 700°C for 1 h to obtain biochar; add 60 g of biochar to 500 mL of nitric acid / H2O2 mixed solution (the volume ratio of nitric acid solution to H2O2 is 1:1, the mass fraction of the nitric acid solution is 10%, and the mass fraction of the H2O2 is 10%), soak at 60°C for 1 h, filter, wash and dry after the treatment, and obtain pretreated biochar;

[0069] (c) Modified biochar: 60 g of the pretreated biochar in step (b) was added to 900 mL of ethanol aqueous solution (the volume fraction of ethanol was 80%), followed by the addition of 12 g of vinyl triethoxysilane, and the mixture was stirred at 70°C for 3 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain vinyl biochar; then 60 g of the vinyl biochar was added to 1 L of toluene, followed by the addition of 9 g of 4-imidazole acrylic acid and 0.8 g of azobisisobutyronitrile, and the mixture was kept at 90°C for 2 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified biochar;

[0070] (d) Preparation of composite modified adsorbent: 100 g of modified molecular sieve and 50 g of modified biochar were uniformly mixed to obtain the composite modified adsorbent.

[0071] Comparative Example 1

[0072] A method for purifying bis(diethylamino)silane comprises the following steps:

[0073] S1, adding industrial-grade di(diethylamino)silane to the first distillation tower for light removal treatment, the top pressure of the distillation tower is 0.1MPa, the top temperature is 180°C, the bottom pressure is 0.08MPa, the bottom temperature is 195°C, the theoretical plate number is 60, and the product after light removal is drawn out from the bottom of the tower;

[0074] S2, the product after light removal is introduced into the second distillation tower for heavy removal treatment, the top pressure of the distillation tower is 0.15MPa, the top temperature is 195°C, the bottom pressure is 0.18MPa, the bottom temperature is 210°C, the theoretical plate number is 85, and the product after heavy removal is drawn out from the top of the tower;

[0075] S3, introducing the deweighted product into a condenser, condensing it into a liquid state and introducing it into an adsorption tank for adsorption treatment, the temperature of the adsorption treatment is 55 ° C, the time is 1.5h, and after the treatment is completed, it passes through a filter screen into a finished product tank to obtain high-purity di(diethylamino)silane;

[0076] Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent, and the volume of the composite modified adsorbent accounts for 18% of the total volume of the adsorption tank.

[0077] The method for preparing the composite modified adsorbent in step S3 comprises the following steps:

[0078] (a) Preparation of modified molecular sieve: MCM-41 molecular sieve was added to a sodium hydroxide solution with a concentration of 0.4 mol / L, and impregnated at 45°C for 1.5 h. After impregnation, the mixture was filtered and dried, and then calcined at 530°C for 1 h to obtain a pretreated molecular sieve; 55 g of the pretreated molecular sieve was added to 800 mL of toluene, followed by the addition of 10 g of γ-aminopropyltriethoxysilane, and stirred at 75°C for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain a solid product. Subsequently, 55 g of the solid product was added to 550 g of thionyl chloride, and reacted at 65°C for 4 h. After the reaction was completed, the mixture was filtered and dried to obtain a modified molecular sieve;

[0079] (b) adding 100 g corn straw powder to 1200 g sodium hydroxide solution with a mass fraction of 13%, stirring and impregnating at 55° C. for 1.5 h, then adding 55 g cerium nitrate solution with a mass fraction of 13%, hydrothermally reacting at 140° C. for 5 h, filtering, washing, and drying after the reaction is completed, and calcining at 650° C. for 1.5 h to obtain biochar; adding 55 g biochar to 500 mL nitric acid / H2O2 mixed solution (the volume ratio of nitric acid solution to H2O2 is 1:1, the mass fraction of the nitric acid solution is 10%, and the mass fraction of the H2O2 is 10%), impregnating at 55° C. for 1.5 h, filtering, washing, and drying after the treatment is completed to obtain pretreated biochar;

[0080] (c) Preparation of composite modified adsorbent: 80 g of modified molecular sieve and 70 g of pretreated biochar were mixed evenly to obtain the composite modified adsorbent.

[0081] Compared with Example 1, the pretreated biochar was not modified in this comparative example.

[0082] Comparative Example 2

[0083] A method for purifying bis(diethylamino)silane comprises the following steps:

[0084] S1, adding industrial-grade di(diethylamino)silane to the first distillation tower for light removal treatment, the top pressure of the distillation tower is 0.1MPa, the top temperature is 180°C, the bottom pressure is 0.08MPa, the bottom temperature is 195°C, the theoretical plate number is 60, and the product after light removal is drawn out from the bottom of the tower;

[0085] S2, the product after light removal is introduced into the second distillation tower for heavy removal treatment, the top pressure of the distillation tower is 0.15MPa, the top temperature is 195°C, the bottom pressure is 0.18MPa, the bottom temperature is 210°C, the theoretical plate number is 85, and the product after heavy removal is drawn out from the top of the tower;

[0086] S3, introducing the deweighted product into a condenser, condensing it into a liquid state and introducing it into an adsorption tank for adsorption treatment, the temperature of the adsorption treatment is 55 ° C, the time is 1.5h, and after the treatment is completed, it passes through a filter screen into a finished product tank to obtain high-purity di(diethylamino)silane;

[0087] Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent, and the volume of the composite modified adsorbent accounts for 18% of the total volume of the adsorption tank.

[0088] The method for preparing the composite modified adsorbent in step S3 comprises the following steps:

[0089] (a) Preparation of modified molecular sieve: MCM-41 molecular sieve was added into a sodium hydroxide solution with a concentration of 0.4 mol / L, and impregnated at 45°C for 1.5 h. After impregnation, the mixture was filtered and dried, and calcined at 530°C for 1 h to obtain a pretreated molecular sieve;

[0090] (b) adding 100 g corn straw powder to 1200 g sodium hydroxide solution with a mass fraction of 13%, stirring and impregnating at 55° C. for 1.5 h, then adding 55 g cerium nitrate solution with a mass fraction of 13%, hydrothermally reacting at 140° C. for 5 h, filtering, washing, and drying after the reaction is completed, and calcining at 650° C. for 1.5 h to obtain biochar; adding 55 g biochar to 500 mL nitric acid / H2O2 mixed solution (the volume ratio of nitric acid solution to H2O2 is 1:1, the mass fraction of the nitric acid solution is 10%, and the mass fraction of the H2O2 is 10%), impregnating at 55° C. for 1.5 h, filtering, washing, and drying after the treatment is completed to obtain pretreated biochar;

[0091] (c) Modified biochar: 55 g of the pretreated biochar in step (b) was added to 900 mL of ethanol aqueous solution (the volume fraction of ethanol was 75%), followed by the addition of 10 g of vinyl triethoxysilane, and the mixture was stirred at 65°C for 3.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain vinyl biochar; 55 g of the vinyl biochar was then added to 1 L of toluene, followed by the addition of 8 g of 4-imidazole acrylic acid and 0.5-0.8 g of azobisisobutyronitrile, and the mixture was kept at 85°C for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified biochar;

[0092] (d) Preparation of composite modified adsorbent: 80 g of pretreated molecular sieve and 70 g of modified biochar were mixed evenly to obtain the composite modified adsorbent.

[0093] Compared with Example 1, the pretreated molecular sieve was not modified in this comparative example.

[0094] The purity of the di(diethylamino)silane obtained by purification in Example 1-3 and Comparative Example 1-2 and the content of its impurities are shown in Table 1 below:

[0095] Table 1

[0096]

[0097] As can be seen from Table 1 above, the method for purifying di(diethylamino)silane provided by the present invention has a purity of di(diethylamino)silane above 99.99 wt %, and has good application prospects.

[0098] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for purifying bis(diethylamino)silane, characterized in that: The following steps are involved: S1, adding industrial-grade di(diethylamino)silane into the first distillation tower, performing light removal treatment, and obtaining a light-removed product which is drawn out from the bottom of the tower; S2, introducing the product after light removal into the second distillation tower, performing heavy removal treatment, and obtaining the product after heavy removal and drawing it out from the top of the tower; S3, introducing the deweighted product into a condenser, condensing it into a liquid state and introducing it into an adsorption tank for adsorption treatment, and after the treatment is completed, passing through a filter screen into a finished product tank to obtain high-purity di(diethylamino)silane; Wherein, the adsorption tank in step S3 is filled with a composite modified adsorbent.

2. The purification method according to claim 1, characterized in that In step S1, the top pressure of the first distillation tower is 0.08-0.13 MPa, the top temperature is 175-185°C, the bottom pressure is 0.05-0.1 MPa, the bottom temperature is 190-200°C, and the theoretical plate number is 50-70.

3. The purification method according to claim 1, characterized in that In step S2, the top pressure of the second distillation tower is 0.12-0.17 MPa, the top temperature is 192-197° C., the bottom pressure is 0.15-0.2 MPa, the bottom temperature is 205-215° C., and the theoretical plate number is 80-90.

4. The purification method according to claim 1, characterized in that The volume of the composite modified adsorbent in step S3 accounts for 15-20% of the total volume of the adsorption tank.

5. The purification method according to claim 1, characterized in that: The temperature of the adsorption treatment in step S3 is 50-60° C. and the time is 1-2 h.

6. The purification method according to claim 1, characterized in that: The method for preparing the composite modified adsorbent in step S2 comprises the following steps: (a) Preparation of modified molecular sieve: adding MCM-41 molecular sieve to sodium hydroxide solution for impregnation treatment, filtering, drying and calcining after the impregnation to obtain a pretreated molecular sieve; adding the pretreated molecular sieve to toluene, then adding γ-aminopropyltriethoxysilane, stirring for reaction, filtering, washing and drying after the reaction to obtain a solid product, then adding the solid product to thionyl chloride for heating reaction, filtering and drying after the reaction to obtain a modified molecular sieve; (b) adding the biomass powder to a sodium hydroxide solution, stirring and impregnating, then adding a cerium nitrate solution, performing a hydrothermal reaction, filtering, washing, drying, and calcining after the reaction is completed to obtain biochar; adding the biochar to a nitric acid / H2O2 mixed solution, performing an impregnation treatment, filtering, washing, and drying after the treatment is completed to obtain pretreated biochar; (c) Modified biochar: adding the pretreated biochar in step (b) to an ethanol aqueous solution, then adding vinyl triethoxysilane, stirring to react, filtering, washing, and drying after the reaction is completed to obtain vinyl biochar; then adding the vinyl biochar to toluene, then adding 4-imidazole acrylic acid and azobisisobutyronitrile, and reacting at a constant temperature, filtering, washing, and drying after the reaction is completed to obtain modified biochar; (d) Preparation of composite modified adsorbent: The modified molecular sieve and the modified biochar are uniformly mixed to obtain the composite modified adsorbent.

7. The purification method according to claim 6, characterized in that: The concentration of the sodium hydroxide solution in step (a) is 0.3-0.5 mol / L, the impregnation temperature is 40-50° C., the time is 1-2 h, the calcination temperature is 500-550° C., and the time is 0.5-1 h; the mass ratio of the pretreated molecular sieve and γ-aminopropyltriethoxysilane is 50-60:8-12, the stirring reaction temperature is 70-80° C., and the time is 2-3 h; the mass ratio of the solid product and thionyl chloride is 50-60:500-600, the heating reaction temperature is 60-70° C., and the time is 3-5 h.

8. The purification method according to claim 6, characterized in that: The concentration of the sodium hydroxide solution in step (b) is 1-2 mol / L, the temperature of the stirring and impregnating is 50-60°C, the time is 1-2h, the mass fraction of the cerium nitrate solution is 10-15%, the mass ratio of the biomass powder, the sodium hydroxide solution, and the cerium nitrate is 100:1000-1300:50-60, the temperature of the hydrothermal reaction is 130-150°C, the time is 4-6h, the temperature of the calcination is 600-700°C, and the time is 1-2h; the volume ratio of the nitric acid solution to H2O2 in the nitric acid / H2O2 mixed solution is 1:1, the mass fraction of the nitric acid solution is 5-10%, the mass fraction of the H2O2 is 10-15%, the temperature of the impregnation treatment is 50-60°C, and the time is 1-2h.

9. The purification method according to claim 6, characterized in that: In step (c), the mass ratio of the pretreated biochar and vinyl triethoxysilane is 50-60:8-12, the temperature of the stirring reaction is 60-70°C, and the time is 3-4h; the mass ratio of the vinyl biochar, 4-imidazole acrylic acid, and azobisisobutyronitrile is 50-60:6-9:0.5-0.8, the temperature of the isothermal reaction is 80-90°C, and the time is 2-3h.

10. The purification method according to claim 6, characterized in that: The mass ratio of the modified molecular sieve to the modified biochar in step (d) is 5-10:5-10.

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