Preparation method of tetraethoxysilane

Abstract

The invention provides a preparation method of tetraethoxysilane, which comprises the following steps: 1) carrying out a silanization reaction on a raw material system containing silicon powder, absolute ethyl alcohol and a catalyst to obtain a first material containing crude tetraethoxysilane, hydrogen and residual silicon powder; 2) carrying out ball milling treatment on a mixed system containing the residual silicon powder and a dehydrating agent to obtain a second material; (3) carrying out reduction treatment on the second material to obtain recycled silicon powder; and returning the recovered silicon powder to participate in the silanol salinization reaction. According to the preparation method of tetraethyl orthosilicate provided by the invention, the mixed system of the residual silicon powder and the dehydrating agent is subjected to ball-milling treatment, and the second material is subjected to reduction treatment, so that the recovered silicon powder can be returned to participate in the silanol salinization reaction, and the agglomeration phenomenon of the silicon powder in the reaction process is effectively prevented; the silicon powder conversion rate and the ethyl orthosilicate selectivity are improved.

Description

Technical Field

[0001] The invention belongs to the field of synthesis technology, and in particular relates to a method for preparing ethyl orthosilicate. Background Art

[0002] Tetraethyl orthosilicate is an important class of organic silicon compounds, which is widely used in flexible materials, weather-resistant coatings, sealants, medicines, pesticides, fragrances, polymer additives and other fields. There are two mainstream preparation methods for tetraethyl orthosilicate, one is the silicon tetrachloride method and the other is the silicon powder method. The silicon tetrachloride method is to generate tetraethyl orthosilicate by reacting silicon tetrachloride and anhydrous ethanol; the silicon powder method is to generate tetraethyl orthosilicate by reacting silicon powder and ethanol under the action of a catalyst. The silicon powder method has relatively few pollutants in the preparation process, and its advantages in environmental protection are more in line with the development trend of the market.

[0003] However, in the existing silicon powder method, silicon powder is prone to agglomeration during the reaction to form larger particle agglomerates. A dense silicon dioxide film is formed on the surface of these agglomerates, which hinders the further contact of the reactants, resulting in the inability to continue the reaction, resulting in a low silicon powder conversion rate and a reduced selectivity of ethyl orthosilicate. Therefore, developing a method for preparing ethyl orthosilicate that can improve silicon powder conversion rate and ethyl orthosilicate selectivity is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing ethyl orthosilicate, which can improve the conversion rate of silicon powder and the selectivity of ethyl orthosilicate.

[0005] The present invention provides a method for preparing tetraethyl orthosilicate, comprising the following steps:

[0006] 1) subjecting a raw material system including silicon powder, anhydrous ethanol and a catalyst to a silicon alkoxide reaction to obtain a first material including crude ethyl orthosilicate, hydrogen and residual silicon powder;

[0007] 2) ball milling the mixed system including the residual silicon powder and the dehydrating agent to obtain a second material;

[0008] 3) performing reduction treatment on the second material to obtain recycled silicon powder; and returning the recycled silicon powder to participate in the silicon alkoxide reaction.

[0009] In the preparation method as described above, the mass ratio of the silicon powder, anhydrous ethanol and the catalyst is 100:300-500:1-5.

[0010] In the preparation method as described above, the reaction temperature of the silicon alkoxide reaction is 80-150° C., and the reaction pressure is 0.1-0.5 MPa.

[0011] In the preparation method as described above, the mass ratio of the residual silicon powder to the dehydrating agent is 10-100:1.

[0012] In the preparation method as described above, the rotation speed of the ball milling treatment is 200-600 rpm and the time is 2-6 hours.

[0013] The preparation method as described above, before the ball milling treatment, further comprises: washing the residual silicon powder with ethanol;

[0014] The mass ratio of the ethanol to the residual silicon powder is 1-5:1;

[0015] The stirring rate of the cleaning process is ≥300 rpm, and the cleaning time of the cleaning process is ≥1 h.

[0016] In the preparation method as described above, the temperature of the reduction treatment is 450-900° C. and the time is 3-9 hours.

[0017] The preparation method as described above further comprises: subjecting the crude ethyl orthosilicate to a rectification treatment to obtain ethyl orthosilicate.

[0018] In the preparation method as described above, the hydrogen used in the reduction treatment comes from the first material.

[0019] The preparation method as described above further comprises: distilling the ethanol cleaning liquid after the cleaning treatment to obtain anhydrous ethanol;

[0020] The anhydrous ethanol is returned to participate in the siliconization reaction.

[0021] The method for preparing tetraethyl orthosilicate provided by the present invention can make the recovered silicon powder return to participate in the silicon alkoxide reaction by ball milling the mixed system of residual silicon powder and dehydrating agent and reducing the second material, thereby effectively preventing the silicon powder from agglomerating during the reaction and improving the silicon powder conversion rate and tetraethyl orthosilicate selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present invention or related technologies. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 The present invention provides a schematic flow chart of a method for preparing ethyl orthosilicate. DETAILED DESCRIPTION

[0024] In order to make the purpose, 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 combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0025] The present invention provides a method for preparing tetraethyl orthosilicate, comprising the following steps:

[0026] 1) performing a silicon alkoxide reaction on a raw material system including silicon powder, anhydrous ethanol and a catalyst to obtain a first material including crude ethyl orthosilicate, hydrogen and residual silicon powder;

[0027] 2) ball milling the mixed system including the residual silicon powder and the dehydrating agent to obtain a second material;

[0028] 3) performing reduction treatment on the second material to obtain recycled silicon powder; and returning the recycled silicon powder to participate in the silicon alkoxide reaction.

[0029] like Figure 1 As shown, the present invention performs siliconization reaction on the raw material, then mixes the residual silicon powder with a dehydrating agent and performs ball milling treatment, and then performs reduction treatment on the second material, so that the obtained recycled silicon powder is returned to participate in the siliconization reaction.

[0030] Specifically, in step 1), a raw material system including silicon powder, anhydrous ethanol and a catalyst is subjected to a silicon alcohol salt reaction, so that the silicon powder reacts with the anhydrous ethanol to generate ethyl orthosilicate and hydrogen, as well as unreacted anhydrous ethanol, residual silicon powder that cannot continue to react, and other by-products, such as triethoxysilane and oligomeric polysiloxane. Among them, the time of the silicon alcohol salt reaction is determined according to the amount of hydrogen generated, that is, the generation rate of hydrogen is monitored by a gas flow meter. When the generation rate of hydrogen decreases significantly and tends to be stable, it is considered that the reaction is basically completed. The catalyst used in the silicon alcohol salt reaction includes but is not limited to copper catalysts and alkali metal catalysts, wherein the copper catalysts include but are not limited to copper, copper oxides, etc.; the alkali metal catalysts include but are not limited to alkali metal salts, alkali metal alkoxides, etc., wherein the alkali metal includes but is not limited to sodium, potassium, lithium, rubidium, cesium, etc. Among them, the preferred catalyst is an alkali metal alkoxide, including but not limited to sodium ethoxide, potassium methoxide, sodium isopropoxide, potassium n-propoxide, potassium n-butoxide, sodium isobutoxide, potassium ethoxide, rubidium methoxide, etc., among which more preferred is an alkali metal alkoxide having both a cyclic ether structure and -OH, and the alkoxide includes but not limited to 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-oxocanane-1-ol salt, 2-oxonanane-1-ol salt, 3-oxepane-1-ol salt, 4-oxanol-1-ol salt, 1,4-dioxepane salt and 2-oxepane-1-ol salt.

[0031] In step 2), after the residual silicon powder is separated from other materials, it is mixed with a dehydrating agent, and the obtained mixed system is subjected to ball milling treatment to uniformly mix the dehydrating agent with the residual silicon powder, and to make the particle size fine, so as to prevent the silicon powder from agglomerating during the reaction, and to prevent the subsequent silicon powder from being reused. Water is generated while forming silicon dioxide, which deactivates the catalyst or hydrolyzes ethyl orthosilicate. When the residual silicon powder is combined with the dehydrating agent, the dehydrating agent can absorb the generated water. The separation of the residual silicon powder from other materials can be carried out by any equipment that effectively separates solid and liquid substances, preferably a centrifuge, whose speed range can be between 3000-5000rpm, and the processing time is not less than 20 minutes. The dehydrating agent can be at least one of phosphorus pentoxide, molecular sieves, calcium oxide, sodium sulfate and calcium chloride.

[0032] In step 3), after the ball milling is completed, the mixture in the ball mill is separated by a sieve. The sieve aperture should be selected to a suitable size so as to effectively separate the grinding balls and the mixture. The powder mesh after separation is selected to pass through a 100-mesh sieve to obtain the second material. The purpose of reducing the second material is to reduce the presence of silicon dioxide and reduce the amount of dehydrating agent used, so that the recovered silicon powder is returned to participate in the silicon alcohol salt reaction, which can improve the conversion rate of silicon powder and the selectivity of ethyl orthosilicate. The reduction treatment can be carried out using hydrogen.

[0033] The method for preparing tetraethyl orthosilicate provided by the present invention can make the recovered silicon powder return to participate in the silicon alkoxide reaction by ball milling the mixed system of residual silicon powder and a dehydrating agent and reducing the second material, effectively prevent the silicon powder from agglomerating during the reaction, improve the silicon powder conversion rate and tetraethyl orthosilicate selectivity, reduce the amount of residue generated, reduce the cost and steps of treating the residue, and improve the economy and simplicity of the overall process.

[0034] In some embodiments of the present invention, the mass ratio of the silicon powder, anhydrous ethanol and catalyst is 100:300-500:1-5.

[0035] In the present invention, the mass ratio of silicon powder, anhydrous ethanol and catalyst is 100:300-500:1-5, preferably 100:300-500:3, within a suitable range, which can increase the reaction rate, reduce the occurrence of side reactions, improve product purity and selectivity, and reduce raw material waste.

[0036] In some embodiments of the present invention, the reaction temperature of the silicon alkoxide reaction is 80-150° C. and the reaction pressure is 0.1-0.5 MPa.

[0037] The reaction temperature of the silicon alkoxide reaction in the present invention is 80-150° C., preferably 120° C.; the reaction pressure is 0.1-0.5 MPa, preferably 0.1 MPa, which can make the reaction rate of the silicon alkoxide reaction appropriate, facilitate the formation and purification of the product, improve the silicon powder conversion rate and the selectivity of ethyl orthosilicate, and also save energy consumption and reduce production costs.

[0038] In some embodiments of the present invention, the mass ratio of the residual silicon powder to the dehydrating agent is 10-100:1.

[0039] In the present invention, the mass ratio of residual silicon powder to dehydrating agent is within an appropriate range, which can enable the dehydrating agent to fully absorb the generated water, effectively prevent the silicon powder from agglomerating during the reaction, and is conducive to recovering the silicon powder to participate in the silicon alcohol salt reaction, thereby further improving the conversion rate of silicon powder and the selectivity of ethyl orthosilicate.

[0040] In some embodiments of the present invention, the ball milling treatment is performed at a rotation speed of 200-600 rpm and for a time of 2-6 hours.

[0041] In the present invention, the rotation speed of the ball milling treatment is controlled to be 200-600rpm and the time is 2-6h, which can further make the dehydrating agent and the residual silicon powder evenly mixed, and make the material particle size finer, further improve the water absorption effect of the dehydrating agent, effectively prevent the silicon powder from agglomerating during the reaction process, and improve the conversion rate of the silicon powder and the selectivity of ethyl orthosilicate.

[0042] In some embodiments of the present invention, the ball milling process further includes: washing the residual silicon powder with ethanol;

[0043] The mass ratio of the ethanol to the residual silicon powder is 1-5:1;

[0044] The stirring rate of the cleaning process is ≥300 rpm, and the cleaning time of the cleaning process is ≥1 h.

[0045] In the present invention, before the mixed system including residual silicon powder and dehydrating agent is subjected to ball milling treatment, the residual silicon powder is washed with ethanol, and then the washed ethanol is separated from the solid residue, and the washed residual silicon powder is dried.

[0046] The ethanol washing of the residual silicon powder can be carried out in a stirred tank, with a stirring rate of ≥300rpm and a stirring washing time of ≥1 hour. The ethanol used can be fresh anhydrous ethanol or anhydrous ethanol that has not reacted in the silicon alcohol salt reaction, wherein the mass ratio of ethanol to the residual silicon powder is 1-5:1. The purpose of the ethanol washing in this step is to remove the residual reaction raw materials and by-products.

[0047] When the residual silicon powder after cleaning is dried, the drying equipment can be any equipment capable of drying, such as a drying belt, a blast oven, etc. The drying temperature can be 50-150°C, preferably 80-100°C, and the drying time is ≥3h.

[0048] The present invention utilizes ethanol to clean the residual silicon powder, thereby removing residual reaction raw materials and by-products, improving the purity of the residual silicon powder, and improving the conversion rate of the silicon powder and the selectivity of ethyl orthosilicate when the residual silicon powder is returned to participate in the silicon alkoxide reaction.

[0049] In some embodiments of the present invention, the reduction treatment is carried out at a temperature of 450-900° C. and for a time of 3-9 hours.

[0050] The temperature of the reduction treatment in the present invention is 450-900°C, preferably 500-700°C; the time is 3-9h, preferably 4-6h, which can further achieve sufficient reduction of residual silicon powder, reduce the presence of silicon dioxide, reduce the amount of dehydrating agent used, and further improve the conversion rate of silicon powder and the selectivity of ethyl orthosilicate.

[0051] In some embodiments of the present invention, the process further comprises: subjecting the crude ethyl orthosilicate to distillation treatment to obtain ethyl orthosilicate.

[0052] In the present invention, the crude ethyl orthosilicate is subjected to rectification treatment, thereby improving the purity of the ethyl orthosilicate, reducing the presence of by-products, and enhancing its application value.

[0053] In some embodiments of the present invention, the hydrogen used in the reduction treatment comes from the first material.

[0054] In the present invention, the hydrogen in the first material is used to perform reduction treatment on the second material, which can achieve efficient utilization of resources, reduce waste of resources, and is conducive to promoting circular economy and sustainable development.

[0055] In some embodiments of the present invention, the present invention further comprises: performing a distillation treatment on the ethanol cleaning liquid after the cleaning treatment to obtain anhydrous ethanol;

[0056] The anhydrous ethanol is returned to participate in the siliconization reaction.

[0057] The present invention separates the stirred and cleaned mixture through a centrifuge to obtain residual silicon powder and ethanol cleaning liquid after cleaning. The residual silicon powder is collected in a collector of the centrifuge, and the ethanol cleaning liquid is collected as a filtrate or a supernatant. The separated ethanol cleaning liquid can be sent to a purification distillation tower for distillation treatment, and anhydrous ethanol is condensed at the top of the tower, and high-boiling impurities are obtained in the bottom of the tower. The recovered anhydrous ethanol can be returned to participate in the silicon alcohol salt reaction, which can realize the recycling of resources, reduce production costs, and meet the concepts of environmental protection and sustainable development.

[0058] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0059] Example 1

[0060] The preparation method of tetraethyl orthosilicate of the present embodiment comprises the following steps:

[0061] 1) 100 kg of initial silicon powder, 400 kg of anhydrous ethanol and 3 kg of sodium ethoxide are mixed and added to a reactor for synthesizing tetraethyl orthosilicate to carry out silicon alcoholization reaction. The reaction temperature is 120° C. and the reaction pressure is 0.1 MPa. During the reaction, the generation rate of hydrogen is monitored. When the generation rate of hydrogen decreases significantly and tends to be stable, the reaction is basically completed. The first material generated by the reaction includes crude tetraethyl orthosilicate, unreacted ethanol, residual silicon powder, hydrogen and by-products; the crude tetraethyl orthosilicate is distilled to obtain tetraethyl orthosilicate.

[0062] 2) Separate the residual silicon powder from other materials by centrifuge, control the speed to 4000rpm, and the time to 20min. Then, use the unreacted ethanol separated in step 1) to clean the residual silicon powder, the stirring rate is 300rpm, the stirring and cleaning time is 1h, and the mass ratio of ethanol to residual silicon powder is 3:1. The cleaned mixture is separated by centrifuge to obtain cleaned residual silicon powder and ethanol cleaning liquid. The ethanol cleaning liquid is sent to the alcohol distillation tower, and the purified anhydrous ethanol obtained by condensation at the top of the tower is returned to the synthesis reactor to participate in the silicon alcohol salt reaction, and the high boiling point impurities after alcohol washing are obtained in the bottom of the tower.

[0063] 3) The residual silicon powder after cleaning is sent to a drying device for drying. The drying device adopts a blast oven, the drying temperature is 100°C, the time is 3 hours, and the dried residual silicon powder is mixed with a dehydrating agent, phosphorus pentoxide, and then ball milled. The rotation speed of the ball milling is 500 rpm, the time is 4 hours, and the mass ratio of the residual silicon powder to the dehydrating agent is 10:1. After the ball milling is completed, the mixture in the ball mill is separated through a 100-mesh screen. The screen aperture should be selected to a suitable size to effectively separate the grinding balls and the second material.

[0064] 4) The second material is fed into a converter, heated to 600° C., and subjected to hydrogen reduction treatment to obtain recovered silicon powder. The reduction time is 4 hours, and the hydrogen generated by the reaction in step 1) is used during the reduction process.

[0065] 5) Whenever the total weight of the recovered silicon powder obtained in step 4) reaches the amount of silicon powder input for a single batch of silicon alkoxide reaction, the initial silicon powder of step 1) is switched to the recovered silicon powder of step 4) and put into the reaction. The recovered silicon powder is continuously recycled according to the above steps.

[0066] Example 2

[0067] The preparation method of ethyl orthosilicate in Example 2 is basically the same as that in Example 1, except that the catalyst used is potassium 1,4-dioxanol, and its chemical structure is as follows:

[0068]

[0069] Example 3

[0070] The preparation method of tetraethyl orthosilicate in Example 3 is basically the same as that in Example 1, except that the catalyst used is sodium 3-oxacyclohexane-1-olate, and its chemical structure is as follows:

[0071]

[0072] Example 4

[0073] The preparation method of tetraethyl orthosilicate in Example 4 is basically the same as that in Example 1, except that the reaction temperature of the siliconization reaction is 130°C.

[0074] Example 5

[0075] The preparation method of ethyl orthosilicate in Example 5 is basically the same as that in Example 1, except that 4 kg of sodium ethoxide is added in step 1).

[0076] Example 6

[0077] The preparation method of ethyl orthosilicate in Example 6 is basically the same as that in Example 1, except that 350 kg of anhydrous ethanol is added in step 1).

[0078] Example 7

[0079] The preparation method of tetraethyl orthosilicate in Example 7 is basically the same as that in Example 1, except that the drying temperature in step 3) is 110°C.

[0080] Example 8

[0081] The preparation method of tetraethyl orthosilicate in Example 8 is basically the same as that in Example 1, except that the ball milling time in step 3) is 6 hours.

[0082] Example 9

[0083] The preparation method of tetraethyl orthosilicate in Example 9 is basically the same as that in Example 1, except that the reduction temperature in step 4) is 700°C.

[0084] Example 10

[0085] The preparation method of ethyl orthosilicate in Example 10 is basically the same as that in Example 1, except that calcium oxide is used as a dehydrating agent in step 3).

[0086] Embodiment 11

[0087] The preparation method of ethyl orthosilicate in Example 11 is basically the same as that in Example 1, except that sodium sulfate is used as a dehydrating agent in step 3).

[0088] Example 12

[0089] The preparation method of tetraethyl orthosilicate in Example 12 is basically the same as that in Example 1, except that calcium chloride is used as a dehydrating agent in step 3).

[0090] Example 13

[0091] The preparation method of ethyl orthosilicate in Example 13 is basically the same as that in Example 1, except that the mass ratio of residual silicon powder to dehydrating agent in step 3) is 50:1.

[0092] Embodiment 14

[0093] The preparation method of ethyl orthosilicate in Example 14 is basically the same as that in Example 1, except that the mass ratio of residual silicon powder to dehydrating agent in step 3) is 20:1.

[0094] Embodiment 15

[0095] The preparation method of ethyl orthosilicate in Example 15 is basically the same as that in Example 1, except that the mass ratio of residual silicon powder to dehydrating agent in step 3) is 100:1.

[0096] Example 16

[0097] The preparation method of tetraethyl orthosilicate in Example 16 is basically the same as that in Example 1, except that the rotation speed of the ball milling treatment in step 3) is 300 rpm.

[0098] Comparative Example 1

[0099] The preparation methods of ethyl orthosilicate in Comparative Example 1 and Example 1 are basically the same, except that no dehydrating agent is added before mixing with residual silicon powder and then ball milling is performed.

[0100] Comparative Example 2

[0101] The preparation methods of tetraethyl orthosilicate in Comparative Example 2 and Example 1 are basically the same, except that the dehydrating agent is added after the residual silicon powder is ball-milled, that is, the dehydrating agent does not participate in the ball-milling process.

[0102] Comparative Example 3

[0103] The preparation method of tetraethyl orthosilicate in Comparative Example 3 is basically the same as that in Example 1, except that in step 1), a dehydrating agent is added together with initial silicon powder, anhydrous ethanol and sodium ethoxide into a reactor for synthesizing tetraethyl orthosilicate to carry out silicon alkoxide reaction.

[0104] Comparative Example 4

[0105] The preparation method of ethyl orthosilicate in Comparative Example 4 is basically the same as that in Example 1, except that the second material is not subjected to reduction treatment.

[0106] Test example

[0107] 1. Silicon powder conversion rate = (1-mass of silicon element contained in solid residue / mass of silicon powder in raw material) × 100%.

[0108] 2. Selectivity of ethyl orthosilicate: Take the first material after the silicon alcohol salt reaction, separate the solid components therein by centrifugation and filtration, mix the remaining liquid with a quantitative internal standard acetone solvent, and then analyze it by gas chromatography. The concentration of ethyl orthosilicate and other by-products in the liquid is obtained by the internal standard method, and then the selectivity is calculated according to the following formula:

[0109] Selectivity of tetraethyl orthosilicate (%) = concentration of tetraethyl orthosilicate / (concentration of tetraethyl orthosilicate+concentration of by-products)×100%.

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from Table 1, compared with the comparative example, the preparation method of tetraethyl orthosilicate provided by the present invention, by ball milling the mixed system of residual silicon powder and dehydrating agent and reducing the second material, can make the recovered silicon powder return to participate in the silicon alkoxide reaction, effectively prevent the silicon powder from agglomerating during the reaction, and improve the silicon powder conversion rate and tetraethyl orthosilicate selectivity.

[0114] From the comparison between Example 1 and Comparative Examples 1-4, it can be seen that the method for preparing tetraethyl orthosilicate provided by the present invention can improve the silicon powder conversion rate and tetraethyl orthosilicate selectivity.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, 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 ethyl orthosilicate, characterized in that: The following steps are involved: 1) subjecting a raw material system including silicon powder, anhydrous ethanol and a catalyst to a silicon alkoxide reaction to obtain a first material including crude ethyl orthosilicate, hydrogen and residual silicon powder; 2) ball milling the mixed system including the residual silicon powder and the dehydrating agent to obtain a second material; 3) performing reduction treatment on the second material to obtain recycled silicon powder; and returning the recycled silicon powder to participate in the silicon alkoxide reaction.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the silicon powder, anhydrous ethanol and catalyst is 100:300-500:1-5.

3. The preparation method according to claim 1 or 2, characterized in that: The reaction temperature of the silicon alkoxide reaction is 80-150° C., and the reaction pressure is 0.1-0.5 MPa.

4. The preparation method according to any one of claims 1 to 3, characterized in that The mass ratio of the residual silicon powder to the dehydrating agent is 10-100:

1.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The ball milling process is performed at a rotation speed of 200-600 rpm and a time of 2-6 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that: Before the ball milling process, the process also includes: washing the residual silicon powder with ethanol; The mass ratio of the ethanol to the residual silicon powder is 1-5:1; The stirring rate of the cleaning process is ≥300 rpm, and the cleaning time of the cleaning process is ≥1 h.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The reduction treatment is carried out at a temperature of 450-900° C. and for a time of 3-9 hours.

8. The preparation method according to any one of claims 1 to 7, characterized in that: Also includes: The crude ethyl orthosilicate is subjected to rectification treatment to obtain ethyl orthosilicate.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The hydrogen used in the reduction treatment comes from the first material.

10. The preparation method according to claim 6, characterized in that: Also includes: The ethanol cleaning liquid after the cleaning treatment is subjected to rectification treatment to obtain anhydrous ethanol; The anhydrous ethanol is returned to participate in the siliconization reaction.

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