Preparation method of tetraethyl orthosilicate

Abstract

The invention provides a preparation method of tetraethyl orthosilicate, and relates to the technical field of chemical engineering. The method comprises the following steps: replacing air in a reaction kettle with inert gas; putting silicon powder, absolute ethyl alcohol, a solvent and a catalyst into a reaction kettle, and stirring and mixing; when the temperature of the reaction kettle is the reaction temperature and the pressure of the reaction kettle is the reaction pressure, absolute ethyl alcohol is introduced into the reaction kettle, the absolute ethyl alcohol reacts with the silicon powder, and the gas displacement of the reaction kettle is recorded; when the current gas displacement meets the accelerator adding set condition, adding an accelerator into the reaction kettle, and recording the gas displacement of the reaction kettle; when the current gas displacement meets the accelerator adding set condition again and the gas displacement of the reaction kettle after the accelerator is added does not rise, adding the silicon powder into the reaction kettle again, and when the gas displacement of the reaction kettle does not rise any more, stopping adding the silicon powder into the reaction kettle and discharging solid residues in the reaction kettle to obtain tetraethyl orthosilicate. The method is used for achieving the effect of increasing the yield of tetraethyl orthosilicate.

Description

Technical Field

[0001] This application relates to the field of chemical engineering technology, and particularly to a method for preparing tetraethyl orthosilicate. Background Art

[0002] In the field of chemical engineering, tetraethyl orthosilicate is an important class of organosilicon compounds, which are widely used in fields such as flexible materials, weather-resistant coatings, sealants, pharmaceuticals, pesticides, fragrances, and polymer additives. With the continuous growth of the demand for high-performance materials in various industries, there is an urgent need to develop an efficient and environmentally friendly method for preparing tetraethyl orthosilicate.

[0003] Currently, the common method for preparing tetraethyl orthosilicate is to react silicon powder with ethanol under the action of a catalyst to produce tetraethyl orthosilicate. However, this method has the following problems: the yield of tetraethyl orthosilicate is low. Summary of the Invention

[0004] This application provides a method for preparing tetraethyl orthosilicate to improve the yield of tetraethyl orthosilicate.

[0005] In a first aspect, this application provides a method for preparing tetraethyl orthosilicate, including:

[0006] Using an inert gas to displace the air in the reaction kettle;

[0007] Putting silicon powder, absolute ethanol, a solvent, and a catalyst into the reaction kettle and stirring and mixing them;

[0008] When the temperature of the reaction kettle is the reaction temperature and the pressure is the reaction pressure, passing absolute ethanol into the reaction kettle to react absolute ethanol with silicon powder, and recording the exhaust gas volume of the reaction kettle;

[0009] When the current exhaust gas volume meets the promoter addition set condition, adding a promoter to the reaction kettle and recording the exhaust gas volume of the reaction kettle;

[0010] When the current exhaust gas volume meets the promoter addition set condition again and the exhaust gas volume of the reaction kettle does not increase after adding the promoter, adding silicon powder to the reaction kettle again, and when the exhaust gas volume of the reaction kettle no longer increases, stopping adding silicon powder to the reaction kettle, discharging the solid residue in the reaction kettle, and obtaining tetraethyl orthosilicate.

[0011] In a possible implementation manner, the promoter is selected from one or a combination of multiple kinds of hard and wear-resistant inorganic materials, and the hard and wear-resistant inorganic materials include one or more of silicon carbide, silicon nitride, α-aluminum oxide, diamond powder, boron carbide, and boron nitride.

[0012] In a possible implementation manner, the particle size range of the promoter is 0.5 microns to 20 microns.

[0013] In a possible implementation, the addition amount of the promoter is 0.5% to 5% of the total weight of the silicon powder.

[0014] In a possible implementation, the reaction temperature is 80°C to 150°C.

[0015] In a possible implementation, the reaction pressure is 0.1013 MPa to 0.5 MPa.

[0016] In a possible implementation, the catalyst is selected from one or a combination of multiple of copper-based catalysts and alkali metal-based catalysts, and the copper-based catalysts are selected from one or a combination of multiple of copper catalysts and copper oxide catalysts.

[0017] In a possible implementation, the alkali metal-based catalysts are selected from one or a combination of multiple of alkali metal salt catalysts and alkali metal alkoxide catalysts.

[0018] In a possible implementation, the alkali metal alkoxide catalysts are selected from one or a combination of multiple of sodium ethoxide catalyst, potassium methoxide catalyst, sodium isopropoxide catalyst, potassium n-propoxide catalyst, potassium n-butoxide catalyst, sodium isobutoxide catalyst, potassium ethoxide catalyst, rubidium methoxide catalyst.

[0019] In a possible implementation, the alkali metal alkoxide catalyst is a catalyst prepared from an alcohol alkali metal salt having a cyclic ether structure and a hydroxyl structure, and the alcohol alkali metal salt is selected from one or a combination of multiple of 1,4-dioxane cyclohexanolate, 1,3-dioxolane cyclohexanolate, 1,3-trioxolane cyclohexanolate, 2-oxolane-1-ol cyclohexanolate, 3-oxane-1-ol cyclohexanolate, 2-oxooctane-1-ol cyclohexanolate, 2-oxononane-1-ol cyclohexanolate, 3-oxoheptane-1-ol cyclohexanolate, 4-oxane-1-ol cyclohexanolate, 1,4-dioxane heptanolate, 2-oxoheptane-1-ol cyclohexanolate.

[0020] The preparation method of tetraethyl orthosilicate provided by this application includes: replacing the air in the reaction kettle with an inert gas; putting silicon powder, absolute ethanol, a solvent, and a catalyst into the reaction kettle and stirring and mixing them; when the temperature of the reaction kettle is the reaction temperature and the pressure is the reaction pressure, introducing absolute ethanol into the reaction kettle to react absolute ethanol with silicon powder, and recording the exhaust volume of the reaction kettle; when the current exhaust volume meets the set conditions for adding a promoter, adding the promoter to the reaction kettle and recording the exhaust volume of the reaction kettle; when the current exhaust volume meets the set conditions for adding a promoter again and the exhaust volume of the reaction kettle does not increase after adding the promoter, adding silicon powder to the reaction kettle again, and stopping adding silicon powder to the reaction kettle when the exhaust volume of the reaction kettle no longer increases, discharging the solid residue in the reaction kettle to obtain tetraethyl orthosilicate. By reacting absolute ethanol with silicon powder under the conditions of reaction temperature and reaction pressure in this application, it is beneficial to reduce the energy consumption required for the reaction; adding the promoter in batches during the reaction of absolute ethanol and silicon powder, and using the promoter to mechanically grind the silicon powder particles to break the silicon powder agglomeration, so as to ensure continuous silicon powder conversion and reaction efficiency, and achieve the effect of increasing the output of tetraethyl orthosilicate. Detailed implementation manners

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0022] Tetraethyl orthosilicate is an important class of organosilicon compounds and is widely used in fields such as flexible materials, weather-resistant coatings, sealants, pharmaceuticals, pesticides, fragrances, and polymer additives.

[0023] Currently, there are two mainstream preparation methods for tetraethyl orthosilicate:

[0024] The first is the silicon tetrachloride method: reacting silicon tetrachloride with absolute ethanol to produce ethyl orthosilicate, which is the method adopted by most domestic manufacturers;

[0025] The second is the silicon powder method: reacting silicon powder with ethanol under the action of a catalyst to produce tetraethyl orthosilicate, which is a route with simple processes, low cost, and easy industrial scale-up.

[0026] For example, patents CN114292288A, CN102489299B, KR1020150097319A and other patents disclose methods for preparing alkyl silicate using silicon powder, which are aimed at improving yield and reducing cost, while also taking into account certain environmental protection and sustainability. Among them, some patents use catalysts or special process conditions to improve the efficiency and product quality of the preparation process.

[0027] By studying the existing tetraethyl orthosilicate preparation method, it is found that silicon powder is prone to agglomeration during the reaction process to form larger particle agglomerates. These agglomerates hinder the further contact between the reactants and the catalyst, resulting in the inability to continue the reaction, resulting in a low silicon powder conversion rate, making the preparation method costly and affecting the effective implementation and promotion of the technology. Therefore, how to effectively improve the conversion rate of silicon powder has become a technical problem that needs to be solved urgently.

[0028] In view of the above problems, the present application provides a method for preparing tetraethyl orthosilicate, wherein particles of a substance having a special microscopic morphology and a higher hardness than silicon powder and not participating in the reaction are added as a promoter during the reaction process. These substances prevent the silicon powder from agglomerating during the reaction, allowing the silicon powder to fully react and improving the overall conversion rate of the silicon powder.

[0029] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below.

[0030] An embodiment of the present application provides a method for preparing tetraethyl orthosilicate. The preparation method includes: displacing the air in the reaction kettle with an inert gas; putting silicon powder, absolute ethanol, a solvent, and a catalyst into the reaction kettle and stirring and mixing them; when the temperature of the reaction kettle is the reaction temperature and the pressure is the reaction pressure, introducing absolute ethanol into the reaction kettle to react absolute ethanol with silicon powder, and recording the exhaust gas volume of the reaction kettle; when the current exhaust gas volume meets the set conditions for adding a promoter, adding the promoter to the reaction kettle and recording the exhaust gas volume of the reaction kettle; when the current exhaust gas volume meets the set conditions for adding a promoter again and the exhaust gas volume of the reaction kettle does not increase after adding the promoter, adding silicon powder to the reaction kettle again, and stopping adding silicon powder to the reaction kettle when the exhaust gas volume of the reaction kettle no longer increases, discharging the solid residue in the reaction kettle to obtain tetraethyl orthosilicate. Among them, the weight of the initial silicon powder is 100 parts by weight, the weight of absolute ethanol is 300 to 500 parts by weight, preferably 400 parts by weight, the weight of the catalyst is 1 to 5 parts by weight, preferably 3 parts by weight, the weight of the solvent is 80 - 150 parts by weight, and the solvent is selected from one or a combination of more of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate.

[0031] The reaction equation for the reaction of absolute ethanol with silicon powder to produce tetraethyl orthosilicate is:

[0032]

[0033] The inert atmosphere includes one or a combination of more of nitrogen, argon, and helium. Displacing the air in the reaction kettle with an inert gas is to ensure that there is no moisture and CO 2 in the reaction kettle to ensure that the reaction proceeds in an inert atmosphere. Among them, the specific displacement method can select various methods commonly used in the current industry.

[0034] After discharging the solid residue in the reaction kettle, it is necessary to treat the discharged solid residue: soak and dissolve the residual silicon powder and other solid impurities with an acid solution of a certain concentration, filter and separate the promoter, and reuse it after drying, roasting, and crushing and screening.

[0035] Further, the set conditions for adding the promoter can be set according to the actual situation. For example, the set conditions for adding the promoter are set such that the current exhaust gas volume in the reaction kettle is less than the exhaust gas volume in the reaction kettle at the previous moment.

[0036] In the embodiment of the present application, reacting absolute ethanol with silicon powder under the reaction temperature and reaction pressure is beneficial to reducing the energy consumption required for the reaction; adding the promoter in batches during the reaction of absolute ethanol with silicon powder, and using the promoter to mechanically grind the silicon powder particles to break the silicon powder agglomeration, thereby ensuring continuous silicon powder conversion and reaction efficiency, and achieving the effect of increasing the output of tetraethyl orthosilicate.

[0037] In some embodiments, the promoter is selected from one or more combinations of hard and wear-resistant inorganic materials, and the hard and wear-resistant inorganic materials include one or more of silicon carbide, silicon nitride, α-aluminum oxide, diamond powder, boron carbide, and boron nitride.

[0038] In this embodiment, it can be considered that the promoter is a solid promoter. The solid promoter is selected from one or more combinations of hard and wear-resistant inorganic materials. The hard and wear-resistant inorganic materials are solid particles with a Mohs hardness exceeding that of silicon, being chemically inert, and having a particle size within a certain range. The hard and wear-resistant inorganic materials include one or more of silicon carbide, silicon nitride, α-aluminum oxide, diamond powder, boron carbide, and boron nitride.

[0039] Furthermore, the above-mentioned solid promoter should maintain good physical contact with the silicon powder during the reaction process, while not chemically reacting with silicon or the reaction medium.

[0040] Even further, the mechanism by which the solid promoter can achieve the promoting reaction effect is as follows:

[0041] 1) Mechanical grinding effect: The role of the solid promoter is to friction and collide with the unreacted silicon powder particles through its high hardness and appropriate particle size. Since the silicon powder is prone to agglomeration or formation of larger particles during the reaction, a by-product layer such as silicon dioxide is formed on its surface, hindering the continuation of the reaction. After adding the solid promoter with a higher hardness, the promoter particles generate a grinding effect on the silicon powder through the mechanical force of stirring, breaking or peeling off the silicon dioxide layer on the surface of the silicon powder, exposing a new silicon surface, and promoting the contact and further reaction of the silicon powder with the reaction medium (such as ethanol);

[0042] 2) Improving the reaction contact efficiency: The presence of agglomerated silicon powder will reduce the effective contact area between the silicon powder and the reaction medium, affecting the reaction rate. The addition of the solid promoter can, through collision and friction with the agglomerated silicon powder, break the agglomeration structure, make the silicon powder more evenly dispersed, increase the contact surface area with the reaction medium, and thus improve the reaction rate. In addition, the particles of the solid promoter continuously impact and stir the silicon powder particles during the stirring process, further reducing the mass transfer resistance and enhancing the uniformity of the reaction;

[0043] 3) Physical mixing effect: The stirring in the reaction kettle drives the relative movement of the solid promoter and the silicon powder particles, promoting the uniform distribution of the materials in the reaction kettle. The addition of the solid promoter helps to bring larger particles or agglomerated silicon powder from local areas into the reaction medium. Through the physical mixing effect during the stirring process, these unreacted silicon powders are more fully contacted with the reaction medium, improving the uniformity of the reaction and the conversion rate of the silicon powder;

[0044] 4) Enhancement of Turbulence and Shear: In the stirred reactor, the solid promoter not only grinds the silicon powder but also introduces more turbulence and shear forces into the reaction system. These forces enable more thorough mixing of the reaction materials and simultaneously break the agglomeration of the silicon powder. The enhanced turbulence and shear further reduce the aggregation between silicon powder particles, making the particle distribution more uniform and improving the reaction efficiency.

[0045] Through the combined action of the above several mechanisms, after adding the solid promoter, the agglomerated silicon powder or larger particle silicon powder in the reactor can further react under the action of mechanical force, manifested as an increase in the reaction exhaust gas volume until the reaction reaches a new equilibrium state or the maximum reaction rate.

[0046] In summary, in the embodiments of the present application, by adding the solid promoter, the agglomerated structure of the silicon powder is destroyed, the contact area between the silicon powder and the reaction medium is increased, the mass transfer resistance is reduced, and the uniformity of the reaction is enhanced, thereby improving the conversion rate of the silicon powder and achieving the effect of increasing the yield of tetraethyl orthosilicate.

[0047] In some embodiments, the particle size range of the promoter is 0.5 μm to 20 μm. Controlling the particle size range of the promoter within 0.5 to 20 μm can ensure that the promoter can effectively promote the reaction without affecting the fluidity and mass transfer efficiency of the reaction system.

[0048] In some embodiments, the addition amount of the promoter is 0.5% to 5% of the total weight of the silicon powder. If the addition amount of the promoter is too much, it will promote some unnecessary side reactions, generate impurities, and reduce the purity of tetraethyl orthosilicate. In addition, adding too much promoter will increase the production cost and easily cause waste of resources; if the addition amount of the promoter is too little, the silicon powder cannot fully react with the reactants, resulting in a decrease in the yield of tetraethyl orthosilicate.

[0049] In some embodiments, the reaction temperature is 80°C to 150°C, preferably, the reaction temperature is 120°C. When the reaction temperature is too high, the generated tetraethyl orthosilicate will decompose, deteriorate or polymerize, etc., affecting the purity of the generated tetraethyl orthosilicate; when the reaction temperature is too low, the silicon powder cannot be completely converted into tetraethyl orthosilicate, thereby reducing the conversion rate of the silicon powder.

[0050] In some embodiments, the reaction pressure is 0.1013 MPa to 0.5 MPa, preferably, the reaction pressure is 0.1013 MPa, i.e., atmospheric pressure. Too high reaction pressure will promote the occurrence of some side reactions and change the reaction path, thereby affecting the selectivity of tetraethyl orthosilicate; too low reaction pressure will inhibit the reaction rate of absolute ethanol and silicon powder.

[0051] In some embodiments, the catalyst is selected from one or more combinations of copper-based catalysts and alkali metal-based catalysts. The copper-based catalysts are selected from one or more combinations of copper catalysts and copper oxide catalysts. The copper catalyst helps break the silicon-oxygen bonds on the surface of silicon powder through an electron transfer mechanism, making it easier for the silicon powder to react with absolute ethanol to form tetraethyl orthosilicate; the alkali metal-based catalyst can remove impurities and the inert layer on the surface of silicon powder, making the surface of silicon powder cleaner and improving the reaction activity of silicon powder, thereby increasing the utilization rate of silicon powder.

[0052] In some embodiments, the alkali metal-based catalyst is selected from one or more combinations of alkali metal salt catalysts and alkali metal alkoxide catalysts. Among them, alkali metals have strong electron supply capabilities, which can increase the electron density on the surface of silicon powder, making it easier for silicon powder to react with ethanol and thus accelerating the reaction rate; the alkoxy groups in the alkali metal alkoxide catalyst can react with ethanol to form alkoxyethanol, and alkoxyethanol can serve as a reaction intermediate to promote the reaction between silicon powder and ethanol, thereby increasing the reaction rate.

[0053] In some embodiments, the alkali metal alkoxide catalyst is selected from one or more combinations of sodium ethoxide catalyst, potassium methoxide catalyst, sodium isopropoxide catalyst, potassium n-propoxide catalyst, potassium n-butoxide catalyst, sodium isobutoxide catalyst, potassium ethoxide catalyst, rubidium methoxide catalyst.

[0054] In some embodiments, the alkali metal alkoxide catalyst is a catalyst prepared from an alcohol alkali metal salt having a cyclic ether structure and a hydroxyl structure. The alcohol alkali metal salt is selected from one or more combinations of 1,4-dioxane cyclohexanol salt, 1,3-dioxolane cyclohexanol salt, 1,3-trioxolane cyclohexanol salt, 2-oxolane-1-ol salt, 3-oxane-1-ol salt, 2-oxooctane-1-ol salt, 2-oxononane-1-ol salt, 3-oxoheptane-1-ol salt, 4-oxane-1-ol salt, 1,4-dioxane heptanol salt, 2-oxoheptane-1-ol salt.

[0055] Among them, the catalyst prepared from the alcohol alkali metal salt having a cyclic ether structure usually has good solubility and dispersibility, which can help uniformly disperse silicon powder and improve the contact efficiency of the reaction; the catalyst prepared from the alcohol alkali metal salt having a hydroxyl structure can react with the silicon-oxygen bonds on the surface of silicon powder to promote the dissolution and transformation of silicon powder.

[0056] It can be seen that the catalyst prepared from the alcohol alkali metal salt having a cyclic ether structure and a hydroxyl structure can promote the dissolution and transformation of silicon powder, thereby increasing the yield of tetraethyl orthosilicate.

[0057] Hereinafter, a method for preparing tetraethyl orthosilicate provided by the present application will be further introduced in combination with specific embodiments.

[0058] In the following examples, unless otherwise specified, the experimental methods used can all adopt conventional methods in the art.

[0059] In the following examples, unless otherwise specified, all raw materials can be obtained through commercial purchase or conventional methods.

[0060] Example 1:

[0061] Raw material ratio:

[0062] Silicon powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, sodium ethoxide is selected; solid promoter: silicon carbide, with a particle size of 5 microns, and the addition amount is 2% of the amount of silicon powder; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0063] Process conditions: Reaction temperature: 120 °C; Reaction pressure: atmospheric pressure;

[0064] Operation steps:

[0065] 1. Replace the inside of the reaction kettle with nitrogen to ensure that there is no moisture and CO 2 in the reaction kettle, and ensure that the reaction is carried out in an inert atmosphere;

[0066] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of absolute ethanol, and 3 parts by weight of sodium ethoxide catalyst to the reaction kettle and stir evenly;

[0067] 3. Heat the reaction kettle to 120 °C and keep the reaction pressure of the reaction kettle at atmospheric pressure;

[0068] 4. Introduce absolute ethanol and monitor the exhaust gas volume of the reaction kettle through a flow meter during the reaction;

[0069] 5. When the exhaust gas volume significantly decreases compared to the previous moment, add silicon carbide solid promoter with a particle size of 5 microns, and the addition amount is 2% of the weight of silicon powder. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0070] 6. Continue to stir and react until the exhaust gas volume returns to the original level.

[0071] 7. When the exhaust gas volume significantly decreases again compared to the previous moment and the exhaust gas volume does not increase after adding the silicon carbide solid promoter, add the next batch of silicon powder and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0072] Example 2:

[0073] Raw material ratio:

[0074] Silica powder: 100 parts by weight; absolute ethanol: 300 parts by weight; catalyst: 3 parts by weight, potassium methoxide is selected; solid promoter: silicon nitride, particle size is 10 microns, addition amount is 3% of the silica powder amount; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0075] Process conditions: reaction temperature: 100 °C; reaction pressure: 0.2 MPa;

[0076] Operating steps:

[0077] 1. Replace the inside of the reaction kettle with argon to ensure that there is no moisture and CO in the reaction kettle 2 ;

[0078] 2. Add 100 parts by weight of silica powder, 300 parts by weight of absolute ethanol and 3 parts by weight of potassium methoxide catalyst into the reaction kettle and stir evenly;

[0079] 3. Heat the reaction kettle to 100 °C and keep the reaction pressure of the reaction kettle at 0.2 MPa;

[0080] 4. Pass in absolute ethanol and monitor the change of the exhaust gas volume of the reaction kettle in real time through the flow meter at the exhaust outlet;

[0081] 5. When the exhaust gas volume drops significantly compared with the previous moment, add silicon nitride solid promoter with a particle size of 10 microns, and the addition amount is 3% of the silica powder weight. Here, the so-called significant drop means that the exhaust gas volume drops by more than 30% compared with the exhaust gas volume during the previous stable reaction;

[0082] 6. Continue to stir, and the exhaust gas volume of the reaction kettle rises to the original level.

[0083] 7. When the exhaust gas volume drops significantly again compared with the previous moment and the exhaust gas volume does not rise after adding the promoter, add the next batch of silica powder and repeat steps 2 to 6. Here, the so-called significant drop means that the exhaust gas volume drops by more than 30% compared with the exhaust gas volume during the previous stable reaction.

[0084] Example 3:

[0085] Raw material ratio:

[0086] Silica powder: 100 parts by weight; absolute ethanol: 500 parts by weight; catalyst: 5 parts by weight, potassium isopropoxide is selected; solid promoter: α-aluminum oxide, particle size is 0.5 microns, addition amount is 1% of the silica powder amount; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0087] Process conditions: reaction temperature: 150 °C; reaction pressure: atmospheric pressure;

[0088] Operating steps:

[0089] 1. Replace the reactor with nitrogen to ensure that there is no moisture and CO in the reactor 2 ;

[0090] 2. Put 100 parts by weight of silicon powder, 500 parts by weight of absolute ethanol and 5 parts by weight of potassium isopropoxide catalyst into the reactor and stir to mix;

[0091] 3. Heat the reactor to 150 °C and keep the reaction pressure of the reactor at atmospheric pressure;

[0092] 4. Introduce absolute ethanol and monitor the change of the exhaust gas volume of the reactor in real time through the flowmeter at the exhaust outlet;

[0093] 5. When the exhaust gas volume drops significantly compared with the previous moment, add α-aluminum oxide solid promoter with a particle size of 0.5 microns, and the addition amount is 1% of the weight of the silicon powder. The so-called significant drop means that the drop amplitude of the exhaust gas volume is more than 30% compared with the exhaust gas volume during the previous stable reaction;

[0094] 6. Continue to stir and the exhaust gas volume of the reactor rises to the original level.

[0095] 7. When the exhaust gas volume drops significantly again compared with the previous moment and the exhaust gas volume does not rise after adding the promoter, add the next batch of silicon powder and repeat steps 2 to 6. The so-called significant drop means that the drop amplitude of the exhaust gas volume is more than 30% compared with the exhaust gas volume during the previous stable reaction.

[0096] Example 4:

[0097] Raw material ratio:

[0098] Silicon powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, potassium ethanolate is selected; solid promoter: diamond powder, particle size of 20 microns, addition amount is 0.5% of the amount of silicon powder; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0099] Process conditions: reaction temperature: 80 °C; reaction pressure: 0.5 MPa;

[0100] Operation steps:

[0101] 1. Replace the inside of the reactor with nitrogen to ensure that the moisture and CO in the reactor 2 are completely removed;

[0102] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of absolute ethanol and 3 parts by weight of potassium ethanolate catalyst into the reactor and stir evenly;

[0103] 3. Heat the reactor to 80 °C and keep the reaction pressure of the reactor at 0.5 MPa;

[0104] 4. Introduce absolute ethanol and monitor the change in the exhaust gas volume of the reaction kettle in real time through the flowmeter at the exhaust outlet;

[0105] 5. When the exhaust gas volume significantly decreases compared to the previous moment, add a solid accelerator of diamond powder with a particle size of 20 microns, and the addition amount is 0.5% of the weight of the silicon powder. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0106] 6. Continue stirring until the exhaust gas volume of the reaction kettle rises to the original level.

[0107] 7. When the exhaust gas volume significantly decreases again compared to the previous moment and the exhaust gas volume does not rise after adding the accelerator, add the next batch of silicon powder and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0108] Example 5:

[0109] Raw material ratio:

[0110] Silicon powder: 100 parts by weight; absolute ethanol: 500 parts by weight; catalyst: 4 parts by weight, potassium propoxide is selected; solid accelerator: silicon carbide, with a particle size of 2 microns, and the addition amount is 1% of the silicon powder amount; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0111] Process conditions: reaction temperature: 100 °C; reaction pressure: atmospheric pressure;

[0112] Operating steps:

[0113] 1. Use nitrogen to displace the reaction kettle to ensure that the moisture and CO 2 in it are completely removed;

[0114] 2. Add 100 parts by weight of silicon powder, 500 parts by weight of absolute ethanol and 4 parts by weight of potassium propoxide catalyst to the reaction kettle and stir to mix evenly;

[0115] 3. Heat the reaction kettle to 100 °C and keep the reaction pressure of the reaction kettle at atmospheric pressure;

[0116] 4. Introduce absolute ethanol and monitor the change in the exhaust gas volume of the reaction kettle in real time through the flowmeter at the exhaust outlet;

[0117] 5. When the exhaust gas volume significantly decreases compared to the previous moment, add a solid accelerator of silicon carbide with a particle size of 2 microns, and the addition amount is 1%. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0118] 6. Continue stirring until the exhaust gas volume of the reaction kettle rises to the original level.

[0119] 7. When the exhaust gas volume significantly decreases again relative to the previous moment and does not increase after adding the promoter, add the next batch of silicon powder, and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0120] Example 6:

[0121] Raw material ratio:

[0122] Silicon powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 2 parts by weight, sodium methoxide is selected; solid promoter: silicon nitride, particle size 8 microns, addition amount is 1.5% of the amount of silicon powder; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0123] Process conditions: reaction temperature: 120 °C; reaction pressure: 0.3 MPa;

[0124] Operation steps:

[0125] 1. Replace the reaction kettle with argon to ensure that the moisture and CO 2 are completely removed;

[0126] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of absolute ethanol and 2 parts by weight of sodium methoxide catalyst to the reaction kettle and stir evenly;

[0127] 3. Heat the reaction kettle to 120 °C and keep the reaction pressure of the reaction kettle at 0.3 MPa;

[0128] 4. Introduce absolute ethanol and monitor the change of the exhaust gas volume of the reaction kettle in real time through the flowmeter at the exhaust outlet;

[0129] 5. When the exhaust gas volume significantly decreases relative to the previous moment, add silicon nitride solid promoter with a particle size of 8 microns, and the addition amount is 1.5%. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0130] 6. Continue stirring until the exhaust gas volume of the reaction kettle rises to the original level.

[0131] 7. When the exhaust gas volume significantly decreases again relative to the previous moment and does not increase after adding the promoter, add the next batch of silicon powder, and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0132] Example 7:

[0133] Raw material ratio:

[0134] Silica powder: 100 parts by weight; absolute ethanol: 300 parts by weight; catalyst: 3 parts by weight, potassium isobutoxide is selected; solid promoter: α-aluminum oxide, particle size is 1 μm, addition amount is 2.5% of the silica powder amount; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0135] Process conditions: reaction temperature: 90 °C; reaction pressure: atmospheric pressure;

[0136] Operation steps:

[0137] 1. Use nitrogen to displace the reaction kettle to ensure that the moisture and CO 2 in the reaction kettle are completely removed;

[0138] 2. Add 100 parts by weight of silica powder, 300 parts by weight of ethanol and 3 parts by weight of potassium isobutoxide catalyst into the reaction kettle and stir evenly;

[0139] 3. Heat the reaction kettle to 90 °C and keep the reaction pressure of the reaction kettle at atmospheric pressure;

[0140] 4. Introduce absolute ethanol and monitor the change of the exhaust gas volume of the reaction kettle in real time through the flowmeter at the exhaust outlet;

[0141] 5. When the exhaust gas volume significantly decreases compared with the previous moment, add α-aluminum oxide solid promoter with a particle size of 1 μm, and the addition amount is 2.5%. The so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% compared with the exhaust gas volume during the previous stable reaction;

[0142] 6. Continue to stir until the exhaust gas volume of the reaction kettle rises to the original level.

[0143] 7. When the exhaust gas volume significantly decreases again compared with the previous moment and the exhaust gas volume does not rise after adding the promoter, add the next batch of silica powder and repeat steps 2 to 6. The so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% compared with the exhaust gas volume during the previous stable reaction.

[0144] Example 8:

[0145] Raw material ratio:

[0146] Silica powder: 100 parts by weight; absolute ethanol: 350 parts by weight; catalyst: 4 parts by weight, potassium n-butoxide is selected; solid promoter: diamond powder, particle size is 15 μm, addition amount is 0.8% of the silica powder amount; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0147] Process conditions: reaction temperature: 130 °C; reaction pressure: 0.4 MPa;

[0148] Operation steps:

[0149] 1. Replace the reactor with nitrogen to ensure that the moisture and CO in the reactor are completely removed; 2 are completely excluded;

[0150] 2. Add 100 parts by weight of silicon powder, 350 parts by weight of ethanol and 4 parts by weight of potassium butoxide catalyst to the reactor and stir evenly;

[0151] 3. Heat the reactor to 130 °C and maintain the reaction pressure of the reactor at 0.4 MPa;

[0152] 4. Introduce anhydrous ethanol and monitor the change in the exhaust gas volume of the reactor in real time through the flow meter at the exhaust outlet;

[0153] 5. When the exhaust gas volume decreases significantly compared to the previous moment, add a diamond powder solid promoter with a particle size of 15 microns, and the addition amount is 0.8%. Here, the so-called significant decrease means that the decrease rate of the exhaust gas volume is more than 30% compared to the exhaust gas volume during the previous stable reaction;

[0154] 6. Continue to stir until the exhaust gas volume of the reactor rises to the original level.

[0155] 7. When the exhaust gas volume decreases significantly again compared to the previous moment and the exhaust gas volume does not rise after adding the promoter, add the next batch of silicon powder and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease rate of the exhaust gas volume is more than 30% compared to the exhaust gas volume during the previous stable reaction.

[0156] Example 9:

[0157] Raw material ratio:

[0158] Silicon powder: 100 parts by weight; Anhydrous ethanol: 450 parts by weight; Catalyst: 3 parts by weight, sodium ethoxide is selected; Solid promoter: boron carbide, particle size is 3 microns, addition amount is 2% of the amount of silicon powder; Solvent: tetraethyl orthosilicate, 120 parts by weight;

[0159] Process conditions: Reaction temperature: 110 °C; Reaction pressure: atmospheric pressure;

[0160] Operating steps:

[0161] 1. Replace the reactor with argon to ensure that the moisture and CO in the reactor are completely removed; 2 are completely excluded;

[0162] 2. Add 100 parts by weight of silicon powder, 450 parts by weight of ethanol and 3 parts by weight of sodium ethoxide to the reactor and stir evenly;

[0163] 3. Heat the reactor to 110 °C and maintain the reaction pressure of the reactor at atmospheric pressure;

[0164] 4. Introduce anhydrous ethanol and monitor the change in the exhaust gas volume of the reactor in real time through the flowmeter at the exhaust outlet;

[0165] 5. When the exhaust gas volume significantly decreases compared to the previous moment, add boron carbide solid promoter with a particle size of 3 microns, and the addition amount is 2%. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0166] 6. Continue stirring until the exhaust gas volume of the reactor rises to the original level.

[0167] 7. When the exhaust gas volume significantly decreases again compared to the previous moment and the exhaust gas volume does not rise after adding the promoter, add the next batch of silicon powder and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0168] Example 10:

[0169] Raw material ratio:

[0170] Silicon powder: 100 parts by weight; anhydrous ethanol: 400 parts by weight; catalyst: 2 parts by weight, sodium methoxide is selected; solid promoter: boron nitride, particle size of 7 microns, addition amount is 1% of the amount of silicon powder; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0171] Process conditions: reaction temperature: 115 °C; reaction pressure: 0.5 MPa;

[0172] Operation steps:

[0173] 1. Replace the reactor with nitrogen to ensure that the moisture and CO 2 in the reactor are completely removed;

[0174] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of ethanol and 2 parts by weight of sodium methoxide catalyst to the reactor and stir evenly;

[0175] 3. Heat the reactor to 115 °C and maintain the reaction pressure of the reactor at 0.5 MPa;

[0176] 4. Introduce anhydrous ethanol and monitor the change in the exhaust gas volume of the reactor in real time through the flowmeter at the exhaust outlet;

[0177] 5. When the exhaust gas volume significantly decreases compared to the previous moment, add boron nitride solid promoter with a particle size of 7 microns, and the addition amount is 1%. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0178] 6. Continue stirring until the exhaust gas volume of the reactor rises to the original level.

[0179] 7. When the exhaust gas volume significantly decreases again relative to the previous moment and does not increase after adding the accelerator, add the next batch of silicon powder, and repeat steps 2 to 6. Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0180] Comparative Example 1: Without using a solid accelerator

[0181] Raw material ratio:

[0182] Silicon powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, sodium ethoxide is selected; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0183] Process conditions: Reaction temperature: 120 °C; Reaction pressure: atmospheric pressure;

[0184] Operation steps:

[0185] 1. Replace the reaction kettle with nitrogen to ensure that the moisture and CO 2 in the reaction kettle are completely removed;

[0186] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of absolute ethanol and 3 parts by weight of sodium ethoxide catalyst to the reaction kettle and stir evenly;

[0187] 3. Heat the reaction kettle to 120 °C and keep the reaction pressure of the reaction kettle at atmospheric pressure;

[0188] 4. Pass in absolute ethanol and monitor the change of the exhaust gas volume of the reaction kettle in real time through the flowmeter at the exhaust outlet;

[0189] 5. Without adding a solid accelerator, when the reaction proceeds to the exhaust gas volume decreases, the reaction efficiency does not increase significantly.

[0190] Comparative Example 2: Using a small amount of solid accelerator

[0191] Raw material ratio:

[0192] Silicon powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, sodium methoxide is selected; solid accelerator: silicon carbide, particle size is 5 microns, addition amount is 0.1% of the silicon powder amount; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0193] Process conditions: Reaction temperature: 120 °C; Reaction pressure: atmospheric pressure;

[0194] Operation steps:

[0195] 1. Replace the reaction kettle with argon to ensure that the moisture and CO 2 in the reaction kettle are completely removed;

[0196] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of absolute ethanol, and 3 parts by weight of sodium methoxide catalyst into the reaction kettle, and stir evenly.

[0197] 3. Heat the reaction kettle to 120 °C, and keep the reaction pressure of the reaction kettle at atmospheric pressure.

[0198] 4. When the exhaust gas volume significantly decreases compared to the previous moment, add 0.1% solid promoter (silicon carbide, particle size of 5 microns). Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% compared to the exhaust gas volume during the previous stable reaction.

[0199] 5. In the later stage of the reaction, the exhaust gas volume fails to significantly recover.

[0200] Comparative Example 3: Use an inappropriate solid promoter (soft material)

[0201] Raw material ratio:

[0202] Silicon powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, select sodium ethoxide; solid promoter: talc powder, particle size of 5 microns, addition amount is 2% of the amount of silicon powder; solvent: tetraethyl orthosilicate, 120 parts by weight.

[0203] Process conditions: reaction temperature: 120 °C; reaction pressure: atmospheric pressure.

[0204] Operation steps:

[0205] 1. Use nitrogen to displace the reaction kettle to ensure that the moisture and CO in the reaction kettle 2 are completely removed;

[0206] 2. Add 100 parts by weight of silicon powder, 400 parts by weight of absolute ethanol, and 3 parts by weight of sodium ethoxide catalyst into the reaction kettle, and stir evenly.

[0207] 3. Heat the reaction kettle to 120 °C, and keep the reaction pressure of the reaction kettle at atmospheric pressure.

[0208] 4. When the exhaust gas volume decreases compared to the previous moment, add 2% solid promoter (talc powder, particle size of 5 microns). Here, the so-called significant decrease means that the decrease amplitude of the exhaust gas volume is more than 30% compared to the exhaust gas volume during the previous stable reaction.

[0209] 5. In the later stage of the reaction, the recovery amplitude of the exhaust gas volume is small, and no obvious increase is seen.

[0210] Comparative Example 4: Use a solid promoter with a large particle size

[0211] Raw material ratio:

[0212] Silica powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, potassium methoxide is selected; solid promoter: silicon carbide, particle size 100 microns, addition amount is 2% of the amount of silica powder; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0213] Process conditions: reaction temperature: 120 °C; reaction pressure: atmospheric pressure;

[0214] Operation steps:

[0215] 1. Use argon to displace the reaction kettle to ensure that the moisture and CO 2 are completely excluded;

[0216] 2. Add 100 parts by weight of silica powder, 400 parts by weight of absolute ethanol and 3 parts by weight of potassium methoxide catalyst to the reaction kettle and stir evenly;

[0217] 3. Heat the reaction kettle to 120 °C and keep the reaction pressure of the reaction kettle at atmospheric pressure;

[0218] 4. When the exhaust gas volume decreases relative to the previous moment, add 2% of the solid promoter (silicon carbide, particle size 100 microns). The so-called obvious decrease means that the decrease amplitude of the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction;

[0219] 5. In the later stage of the reaction, the exhaust gas volume does not show an obvious increase.

[0220] Comparative Example 5: Use an excessive amount of solid promoter

[0221] Raw material ratio:

[0222] Silica powder: 100 parts by weight; absolute ethanol: 400 parts by weight; catalyst: 3 parts by weight, sodium ethoxide is selected; solid promoter: silicon nitride, particle size 5 microns, addition amount is 10% of the amount of silica powder; solvent: tetraethyl orthosilicate, 120 parts by weight;

[0223] Process conditions: reaction temperature: 120 °C; reaction pressure: atmospheric pressure;

[0224] Operation steps:

[0225] 1. Use nitrogen to displace the reaction kettle to ensure that the moisture and CO 2 are completely excluded;

[0226] 2. Add 100 parts by weight of silica powder, 400 parts by weight of absolute ethanol and 3 parts by weight of sodium ethoxide catalyst to the reaction kettle and stir evenly;

[0227] 3. Heat the reaction kettle to 120 °C and keep the reaction pressure of the reaction kettle at atmospheric pressure;

[0228] 4. When the exhaust gas volume decreases relative to the previous moment, 10% of a solid promoter (silicon nitride, particle size 5 microns) is added. The so-called significant decrease means that the decrease in the exhaust gas volume is more than 30% relative to the exhaust gas volume during the previous stable reaction.

[0229] 5. In the later stage of the reaction, the fluidity in the reaction kettle becomes poor and the reaction efficiency decreases.

[0230] Furthermore, the conversion rate of silicon powder is calculated as follows:

[0231] Silicon powder conversion rate = (1 - mass of silicon element contained in solid residue / mass of treated silicon powder added) × 100%.

[0232] When analyzing the selectivity of tetraethyl orthosilicate, the material after the reaction needs to be taken, the solid components are separated by centrifugation and filtration, the remaining liquid is mixed with a quantitative internal standard acetone solvent, and then analyzed by gas chromatography. The concentrations of ethyl silicate and other by-products in the liquid are obtained by the internal standard method, and then the selectivity is calculated according to the following formula:

[0233] Selectivity of ethyl silicate (%) = C TEOS / (C TEOS +C 副产物 )×100%

[0234] where C TEOS = concentration of tetraethyl orthosilicate; C 副产物 = concentration of by-products;

[0235] Furthermore, the experimental results of the above examples and comparative examples are shown in Table 1.

[0236] Table 1: Experimental results of examples and comparative examples

[0237] Example Conversion rate of silicon powder Selectivity of tetraethyl orthosilicate Example 1 92.3 96.3 Example 2 98.6 98.8 Example 3 90.3 95.6 Example 4 94.9 96.7 Example 5 93.1 94.7 Example 6 97.6 97.2 Example 7 89.3 92.9 Example 8 96.4 96.7 Example 9 91 93.4 Example 10 65.7 60.1 Comparative Example 1 70.8 75.2 Comparative Example 2 68.3 65.9 Comparative Example 3 72.5 70.2 Comparative Example 4 60.5 58.6 Comparative Example 5 92.3 96.3

[0238] As can be seen from the data in the table, in Comparative Example 1 without using a solid promoter, the silicon powder is prone to agglomeration in the later stage of the reaction, the reaction rate decreases and is difficult to recover, resulting in a low product yield and poor reaction efficiency.

[0239] In Comparative Example 2 with a small amount of solid promoter used, due to the too small addition amount of the solid promoter, it is unable to effectively break the agglomeration of the silicon powder and fails to significantly improve the reaction efficiency, and the reaction rate is still low.

[0240] In Comparative Example 3 with an inappropriate solid promoter used, since the hardness of talcum powder is lower than that of silicon, it cannot produce an effective mechanical grinding effect, resulting in an insignificant promotion effect, a slow rise in the exhaust gas volume, and low reaction efficiency.

[0241] Comparative Example 4 using a solid promoter with a large particle size. Due to the excessively large particle size of the solid promoter, it could not effectively contact and break the agglomeration of silicon powder, resulting in the failure to significantly increase the reaction rate and an insignificant effect of the exhaust gas volume recovery.

[0242] Comparative Example 5 using an excessive amount of solid promoter. Due to the excessive amount of solid promoter, the fluidity of the reaction system became poor, increasing the mass transfer resistance and reducing the reaction rate, resulting in an unsatisfactory overall reaction efficiency.

[0243] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing tetraethyl orthosilicate, characterized in that: The preparation method comprises: Use inert gas to replace the air in the reactor; Put silicon powder, anhydrous ethanol, solvent and catalyst into the reaction kettle and stir and mix; When the temperature of the reactor is the reaction temperature and the pressure is the reaction pressure, anhydrous ethanol is introduced into the reactor to react with the silicon powder, and the exhaust volume of the reactor is recorded; When the current exhaust volume meets the setting condition for adding the accelerator, adding the accelerator to the reactor and recording the exhaust volume of the reactor; When the current exhaust volume meets the set conditions for adding the accelerator again and the exhaust volume of the reactor does not increase after adding the accelerator, silicon powder is added to the reactor again, and when the exhaust volume of the reactor no longer increases, the addition of silicon powder to the reactor is stopped, and the solid residue in the reactor is discharged to obtain tetraethyl orthosilicate.

2. The preparation method according to claim 1, characterized in that: The accelerator is selected from one or more combinations of hard wear-resistant inorganic materials, and the hard wear-resistant inorganic materials include one or more of silicon carbide, silicon nitride, α-aluminum oxide, diamond powder, boron carbide, and boron nitride.

3. The preparation method according to claim 2, characterized in that: The particle size of the accelerator ranges from 0.5 microns to 20 microns.

4. The preparation method according to claim 2, characterized in that: The amount of the accelerator added is 0.5% to 5% of the total weight of the silicon powder.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The reaction temperature is 80°C to 150°C.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The reaction pressure is 0.1013MPa~0.5MPa.

7. The preparation method according to any one of claims 1 to 4, characterized in that The catalyst is selected from a combination of one or more of a copper-based catalyst and an alkali metal-based catalyst, and the copper-based catalyst is selected from a combination of one or more of a copper catalyst and a copper oxide catalyst.

8. The preparation method according to claim 7, characterized in that: The alkali metal catalyst is selected from a combination of one or more of an alkali metal salt catalyst and an alkali metal alkoxide catalyst.

9. The preparation method according to claim 8, characterized in that: The alkali metal alkoxide catalyst is selected from a combination of one or more of a sodium ethoxide catalyst, a potassium methoxide catalyst, a sodium isopropoxide catalyst, a potassium n-propoxide catalyst, a potassium n-butoxide catalyst, a sodium isobutoxide catalyst, a potassium ethoxide catalyst, and a rubidium methoxide catalyst.

10. The preparation method according to claim 8, characterized in that: The alkali metal alkoxide catalyst is a catalyst made from an alkali metal alkoxide having a cyclic ether structure and a hydroxyl structure, and the alkali metal alkoxide is selected from a combination of one or more of 1,4-dioxanol salt, 1,3-dioxolane salt, 1,3-trioxolane salt, 2-oxolane-1-ol salt, 3-oxanol-1-ol salt, 2-oxocanol-1-ol salt, 2-oxonanol-1-ol salt, 3-oxepane-1-ol salt, 4-oxanol-1-ol salt, 1,4-dioxepane salt, and 2-oxepane-1-ol salt.