Preparation method of catalyst for ethyl silicate

Abstract

The invention provides a preparation method of a catalyst for ethyl silicate, which comprises the following steps: 1) carrying out first reaction on a mixed solution containing alkali metal alkoxide, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether and a solvent to obtain a first crude product; 2) performing first light component removal treatment on the first crude product to obtain a second crude product; and 3) performing second light component removal treatment on the second crude product to obtain the catalyst for ethyl silicate, the light component removal temperature of the first light component removal treatment is 50-85 DEG C, and the light component removal temperature of the second light component removal treatment is 60-110 DEG C. The preparation method not only effectively inhibits the problem that the catalyst may be inactivated, but also realizes efficient separation of the catalyst and byproducts by controlling gradient light component removal temperature through subsequent two-stage light component removal treatment, so that the ethyl silicate catalyst with the advantage of high purity is obtained, side reactions in ethyl silicate synthesis are effectively inhibited, and the yield of the ethyl silicate is improved. The catalyst effectively improves the conversion rate of ethyl silicate synthesis raw materials and the selectivity of ethyl silicate.

Description

Technical Field

[0001] This application relates to the chemical industry, and in particular to a method for preparing a catalyst for ethyl silicate. Background Technology

[0002] Tetraethyl silicate (TEOS), as an important precursor material, has shown broad application prospects in the research and preparation of novel functional materials. Its hydrolysis products can not only be used to construct the three-dimensional network structure of high-performance silica aerogels, but also serve as a reinforcing phase for inorganic materials, significantly improving their mechanical properties and thermal stability. Particularly noteworthy is that TEOS can achieve molecular-level composites with organic polymers via the sol-gel method, providing an effective route for preparing organic-inorganic hybrid materials with excellent comprehensive properties. This multifunctional characteristic makes it play a crucial role in the development of composite materials in cutting-edge fields such as aerospace, new energy, and biomedicine.

[0003] While the silicon tetrachloride process is a mature traditional technology, it suffers from serious pollution emissions. Producing one ton of ethyl silicate generates approximately 4.6 tons of highly corrosive HCl waste gas, requiring large amounts of alkali for neutralization. This results in high environmental governance costs, severely limiting the process's economic viability and sustainable development potential.

[0004] To overcome the aforementioned drawbacks, the current primary method employs the direct silicon powder method, where metallic silicon powder and ethanol are directly synthesized into tetraethyl orthosilicate under the action of a catalyst. This method not only avoids halogen contamination but also offers significant economic advantages. However, existing direct silicon powder methods still suffer from drawbacks such as low conversion rates of raw silicon powder and difficulties in purifying tetraethyl orthosilicate, resulting in high production costs and hindering the further promotion and application of this process. Summary of the Invention

[0005] This application provides a method for preparing a catalyst for ethyl silicate. Through a specific reaction system and a two-stage light-light removal process, the activity and purity of the catalyst for ethyl silicate are effectively improved, thereby promoting the effective conversion of raw materials for ethyl silicate synthesis and meeting the high purity requirements for ethyl silicate.

[0006] This application also provides a catalyst for ethyl silicate, which is obtained by the above preparation method and therefore has the advantages of high purity and high catalytic efficiency.

[0007] This application provides a method for preparing a catalyst for ethyl silicate, comprising the following steps:

[0008] 1) A mixture comprising an alkali metal alkoxide, a monoalkyl ethylene glycol ether, a dialkyl ethylene glycol ether, and a solvent is subjected to a first reaction to obtain a first crude product;

[0009] 2) The first crude product is subjected to a first light-removal treatment to obtain a second crude product;

[0010] 3) The second crude product is subjected to a second light-removal treatment to obtain a catalyst for ethyl silicate;

[0011] The removal temperature of the first light-removing treatment is 50-85℃, and the removal temperature of the second light-removing treatment is 60-110℃.

[0012] In the preparation method described above, the mass ratio of alkali metal alkoxide, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether and solvent in the mixture is 1:0.5-1.2:0.3-0.8:3-5.

[0013] The preparation method described above includes alkali metal alkoxides comprising compounds with the structure ROM, wherein R is selected from C1-C4 alkyl groups and M is selected from at least one of Na, K, Li, Rb, and Cs.

[0014] In the preparation method described above, the temperature of the first reaction is 40-70℃ and the pressure is 0.01-0.05 MPaG.

[0015] As described above, the first light-light removal treatment includes: performing a first distillation treatment on the first crude product, wherein the theoretical plate number of the first distillation treatment is 10-15 and the reflux ratio is 0.5-1.2; and / or, the second light-light removal treatment includes: performing a second distillation treatment on the second crude product, wherein the theoretical plate number of the second distillation treatment is 4-12 and the operating pressure is 5-15 kPaG.

[0016] In the preparation method described above, the solvent includes an azeotropic solvent, and the azeotropic temperature of the azeotropic solvent and the alcohol corresponding to the alkali metal alkoxide is 50-85°C.

[0017] In the preparation method described above, the solvent includes at least one selected from cyclohexane, toluene, benzene, chloroform, n-hexane, and diethyl ether.

[0018] The preparation method described above includes: performing an initial heat exchange treatment on the second light-weight removal process using an initial heat medium, followed by cooling the initial heat medium to become a first heat medium; performing an intermediate heat exchange treatment on the first light-weight removal process using the first heat medium, followed by cooling the first heat medium to become a second heat medium; and performing a reaction heat treatment on the first reaction using the second heat medium.

[0019] This application also provides a catalyst for ethyl silicate, obtained by any of the preparation methods described above.

[0020] This application also provides a method for preparing ethyl silicate, comprising the following steps: subjecting a mixture including silicon powder, ethanol and a catalyst to an oxidation-reduction treatment to obtain ethyl silicate; wherein the catalyst comprises the above-mentioned catalyst for ethyl silicate.

[0021] The method for preparing the ethyl silicate catalyst provided in this application constructs a dynamic coordination network from a mixture of alkali metal alkoxide, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, and solvent, effectively suppressing the potential deactivation of the catalyst. Subsequent two-stage light-light removal treatment achieves efficient separation of the catalyst and byproducts by controlling the gradient light-light removal temperature, yielding a high-purity ethyl silicate catalyst. This effectively suppresses side reactions in ethyl silicate synthesis and significantly improves the conversion rate of raw materials and the selectivity of ethyl silicate. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The current direct silica powder synthesis process suffers from low raw material conversion rates and low selectivity for ethyl silicate. The inventors analyzed this phenomenon and concluded that catalyst purity is a key influencing factor. They attempted to synthesize ethyl silicate using alkali metal alkoxides as catalysts, but these catalysts lacked sufficient ability to suppress side reactions (such as silicon-oxygen bond condensation) and were prone to deactivation due to water absorption or alcoholysis, making the problem difficult to solve. Therefore, the inventors attempted to improve the activity and purity of catalysts for ethyl silicate by addressing both the reaction and purification aspects.

[0024] Based on this, this application provides a method for preparing a catalyst for ethyl silicate, comprising the following steps:

[0025] 1) A mixture comprising an alkali metal alkoxide, a monoalkyl ethylene glycol ether, a dialkyl ethylene glycol ether, and a solvent is subjected to a first reaction to obtain a first crude product;

[0026] 2) The first crude product is subjected to a first light-removal treatment to obtain the second crude product;

[0027] 3) The second crude product is subjected to a second light-removal treatment to obtain a catalyst for ethyl silicate;

[0028] The removal temperature for the first light-weight removal treatment is 50-85℃, and the removal temperature for the second light-weight removal treatment is 60-110℃.

[0029] Alkali metal alkoxides, as organic basic catalysts, can form homogeneous reaction systems with ethylene glycol monoalkyl ethers and ethylene glycol dialkyl ethers. The alkali metal cations present in the system can form dynamic coordination networks with ether oxygen bonds, thereby effectively suppressing the phenomenon of catalyst disproportionation and deactivation, yielding a first crude product including the catalyst for ethyl silicate, solvent, and byproducts. In the process, alcohol compounds corresponding to the alkali metal alkoxides are also generated. For example, when the alkali metal alkoxide is sodium methoxide, the corresponding alcohol compound is methanol.

[0030] The purpose of the light component removal process is to separate the heavy components, including the ethyl silicate catalyst, from the light components in the crude product. Specifically, the first light component removal process removes the solvent and generated alcohols from the first crude product, yielding a second crude product containing the catalyst and byproducts. The second light component removal process removes the byproducts from the second crude product. Through this two-stage gradient light component removal process, components with different boiling points in the crude product can be efficiently separated.

[0031] Therefore, by matching the first reaction with the two-stage light-weight removal process, a high-activity and high-purity ethyl silicate catalyst can be obtained, which can be directly used in the synthesis reaction of ethyl silicate without additional regeneration treatment, effectively improving the conversion rate of ethyl silicate raw materials and the selectivity of ethyl silicate.

[0032] It is worth mentioning that the solvent separated by the first light-weight removal treatment can be recycled and reused, and the by-product separated by the second light-weight removal treatment can be sold, thereby further improving the economic benefits of the preparation method of this application.

[0033] In one specific embodiment, the mass ratio of alkali metal alkoxide, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether and solvent in the mixture is 1:0.5-1.2:0.3-0.8:3-5.

[0034] In detail, when the mass ratio of alkali metal alkoxide, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, and solvent is controlled within the above range, it is more beneficial to reduce the impurity content in the catalyst for ethyl silicate and ensure the full progress of the reaction.

[0035] In one specific embodiment, the alkali metal alkoxide includes a compound with the structure ROM, wherein R is selected from C1-C4 alkyl groups and M is selected from at least one of Na, K, Li, Rb, and Cs.

[0036] In detail, when the alkali metal alkoxide has the above-mentioned structural composition, the risk of side reactions occurring in the first reaction is further reduced, which is beneficial to improving the purity of the catalyst used for ethyl silicate.

[0037] Furthermore, side reactions are further reduced when M is selected from at least one of K and Na.

[0038] In one specific implementation, the temperature of the first reaction is 40-70°C and the pressure is 0.01-0.05 MPaG.

[0039] In detail, the reaction efficiency is higher when the temperature and pressure of the first reaction are within the above-mentioned range, with a specific reaction time of 2-7 hours. Furthermore, the reaction efficiency is further improved when the temperature of the first reaction is 45-55°C.

[0040] In one specific embodiment, the first light-removal treatment includes: performing a first distillation treatment on the first crude product, wherein the theoretical number of plates in the first distillation treatment is 10-15, and the reflux ratio is 0.5-1.2.

[0041] In detail, when the theoretical plate number and reflux ratio of the first distillation process are within the above range, the separation efficiency of the solvent and the generated alcohol compounds in the first crude product is further improved.

[0042] In one specific embodiment, the second light-removal treatment includes: subjecting the second crude product to a second distillation treatment, wherein the theoretical number of plates for the second distillation treatment is 4-12, and the operating pressure is 5-15 kPaG.

[0043] In detail, when the theoretical plate number and operating pressure of the second distillation process are within the above range, the separation efficiency of by-products in the second crude product is further improved.

[0044] In one specific embodiment, the solvent includes an azeotropic solvent, and the azeotropic temperature of the azeotropic solvent and the alcohol corresponding to the alkali metal alkoxide is 50-85°C.

[0045] In detail, the azeotropic temperature in this application refers to the azeotropic temperature under normal pressure. When an azeotropic solvent with an azeotropic temperature of 50-85°C is selected, the solvent can form a more effective low azeotrope with the generated alcohol compounds, thereby effectively separating the alcohol compounds from the first crude product and further reducing the impurity content in the catalyst for ethyl silicate.

[0046] In one specific embodiment, the solvent includes at least one selected from cyclohexane, toluene, benzene, chloroform, n-hexane, and diethyl ether.

[0047] In detail, when the solvent is selected as described above, the azeotropic efficiency between the solvent and the alcohol compound is higher, which further reduces the solvent impurity content of the ethyl silicate catalyst, achieving a solvent impurity content of less than 0.05 wt% in the ethyl silicate catalyst.

[0048] In one specific embodiment, the preparation method includes: performing an initial heat exchange treatment on the second light-weight removal process using an initial heat medium, and then cooling the initial heat medium to become a first heat medium; performing an intermediate heat exchange treatment on the first light-weight removal process using the first heat medium, and then cooling the first heat medium to become a second heat medium; and performing a reaction heat treatment on the first reaction using the second heat medium.

[0049] In detail, the heat medium can provide the necessary heat for the first reaction, the first light-weight component removal process, and the second light-weight component removal process through heat exchange. Specifically, it can be water, steam, or heat transfer oil. The initial heat exchange process heats the second light-weight component removal process, and the initial heat medium subsequently cools down to become the first heat medium. The intermediate heat exchange process heats the first light-weight component removal process, and the first heat medium cools down again to become the second heat medium. The reaction heat treatment heats the first reaction. This process reduces heat loss through heat recovery and reuse, further effectively reducing the energy consumption of the catalyst production process.

[0050] This application also provides a catalyst for ethyl silicate, obtained by the aforementioned preparation method. This catalyst exhibits higher catalytic activity and purity, effectively improving the conversion rate and selectivity of ethyl silicate feedstock.

[0051] This application also provides a method for preparing ethyl silicate, comprising the following steps: subjecting a mixture including silicon powder, ethanol and a catalyst to an oxidation-reduction treatment to obtain ethyl silicate; the catalyst includes the aforementioned catalyst for ethyl silicate.

[0052] In detail, silica powder and ethanol can undergo a redox reaction under the highly efficient catalysis of the aforementioned catalyst to produce tetraethyl orthosilicate. This preparation method has advantages in conversion rate and selectivity compared to the catalyst used for tetraethyl orthosilicate. In one specific embodiment, the redox process can be carried out at 120-180°C.

[0053] The preparation method of the ethyl silicate catalyst provided in this application will be described in detail below through specific embodiments.

[0054] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0055] Example 1

[0056] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0057] 1) Add alkali metal alkoxide (potassium ethoxide), ethylene glycol monoalkyl ether (ethylene glycol monoethyl ether), ethylene glycol dialkyl ether (ethylene glycol diethyl ether) and solvent (cyclohexane) in a mass ratio of 1:0.8:0.5:4 to the reactor, and stir at 55°C and 0.02 MPaG for 4 h.

[0058] 2) The reaction liquid is sent to the first distillation column (13 theoretical plates, reflux ratio 0.8) for the first light removal treatment. The temperature at the top of the column is controlled at 65-70℃ to collect the solvent and alcohol (ethanol). The azeotropic temperature of cyclohexane and ethanol is 62℃.

[0059] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 6, operating pressure 10 kPaG) for the second light product removal treatment. The by-products are separated at the top temperature of 85-90℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0060] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0061] Example 2

[0062] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0063] 1) Add alkali metal alkoxide (sodium ethoxide), ethylene glycol monoalkyl ether (ethylene glycol monomethyl ether), ethylene glycol dialkyl ether (ethylene glycol dimethyl ether) and solvent (toluene) in a mass ratio of 1:0.6:0.7:3.5 to the reactor, and stir the mixture at 55°C and 0.05 MPaG for 5 h.

[0064] 2) The reaction solution is sent to the first distillation column (12 theoretical plates, reflux ratio 0.7) for the first light component removal treatment. The temperature at the top of the column is controlled at 78-83℃ to collect the solvent and alcohol (ethanol). The azeotropic temperature of toluene and ethanol is 76.7℃.

[0065] 3) The bottom liquid of the column enters the second distillation column (8 theoretical plates, 8 kPaG operating pressure) for the second light product removal treatment. The by-products are separated at the top temperature of 95-105℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0066] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0067] Example 3

[0068] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0069] 1) Add alkali metal alkoxides (potassium ethoxide and sodium ethoxide in a 1:1 mass ratio), ethylene glycol monoalkyl ethers (ethylene glycol monomethyl ether), ethylene glycol dialkyl ethers (ethylene glycol diethyl ether), and solvent (cyclohexane) to the reactor in a mass ratio of 1:0.8:0.4:4, and stir the mixture at 55°C and 0.05 MPaG for 5 h.

[0070] 2) The reaction solution is sent to the first distillation column (13 theoretical plates, reflux ratio 0.9) for the first light component removal treatment. The temperature at the top of the column is controlled at 69-72℃ to collect the solvent and alcohol (ethanol). The azeotropic temperature of cyclohexane and ethanol is 62℃.

[0071] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 6-8, operating pressure 5-8 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 75-82℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0072] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0073] Example 4

[0074] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0075] 1) Add alkali metal alkoxide (sodium methoxide), ethylene glycol monoalkyl ether (ethylene glycol monomethyl ether), ethylene glycol dialkyl ether (ethylene glycol dimethyl ether) and solvent (benzene) in a mass ratio of 1:0.5:0.3:3 to the reactor, and stir for 7 h at 40℃ and 0.01 MPaG.

[0076] 2) The reaction solution is sent to the first distillation column (10 theoretical plates, reflux ratio 0.5) for the first light component removal treatment. The temperature at the top of the column is controlled at 59-64℃ to collect the solvent and alcohol compounds (methanol). The azeotropic temperature of benzene and methanol is 58.3℃.

[0077] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 4, operating pressure 12 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 70-75℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0078] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0079] Example 5

[0080] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0081] 1) Add alkali metal alkoxide (potassium isopropoxide), ethylene glycol monoalkyl ether (ethylene glycol monopropyl ether), ethylene glycol dialkyl ether (ethylene glycol dipropyl ether) and solvent (chloroform) in a mass ratio of 1:1.2:0.8:5 to the reactor, and stir for 2 hours at 70°C and 0.05 MPaG.

[0082] 2) The reaction solution is sent to the first distillation column (15 theoretical plates, reflux ratio 1.2) for the first light component removal treatment. The temperature at the top of the column is controlled at 63-68℃ to collect the solvent and alcohol (isopropanol). The azeotropic temperature of chloroform and isopropanol is 62.9℃.

[0083] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 12, operating pressure 5 kPaG) for the second light product removal treatment. The by-products are separated at the top temperature of 80-85℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0084] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0085] Example 6

[0086] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0087] 1) Add alkali metal alkoxide (sodium tert-butoxide), ethylene glycol monoalkyl ether (ethylene glycol monobutyl ether), ethylene glycol dialkyl ether (ethylene glycol dibutyl ether) and solvent (n-hexane) in a mass ratio of 1:0.7:0.5:4 to the reactor, and stir for 5 h at 45℃ and 0.03 MPaG.

[0088] 2) The reaction solution is sent to the first distillation column (13 theoretical plates, reflux ratio 0.8) for the first light component removal treatment. The temperature at the top of the column is controlled at 66-71℃ to collect the solvent and alcohol (tert-butanol). The azeotropic temperature of n-hexane and tert-butanol is 65.2℃.

[0089] 3) The bottom liquid of the column enters the second distillation column (8 theoretical plates, operating pressure 15 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 90-95℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0090] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0091] Example 7

[0092] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0093] 1) Add alkali metal alkoxides (sodium ethoxide:potassium ethoxide, ethylene glycol monoalkyl ether (ethylene glycol monoethyl ether), ethylene glycol dialkyl ether (ethylene glycol diethyl ether) and solvent (cyclohexane:toluene, ethylene glycol monoalkyl ether, ethylene glycol diethyl ether) in a mass ratio of 1:0.9:0.6:3.8 to a reaction vessel, and stir for 4 h at 50 °C and 0.04 MPaG.

[0094] 2) The reaction solution is sent to the first distillation column (12 theoretical plates, reflux ratio 1.0) for the first light component removal treatment. The temperature at the top of the column is controlled at 72-77℃ to collect the solvent and alcohol (ethanol). The azeotropic temperature of cyclohexane, toluene and ethanol is 70℃.

[0095] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 6, operating pressure 8 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 80-85℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0096] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0097] Example 8

[0098] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0099] 1) Add alkali metal alkoxide (sodium methoxide), ethylene glycol monoalkyl ether (ethylene glycol monomethyl ether), ethylene glycol dialkyl ether (ethylene glycol dimethyl ether) and solvent (diethyl ether) in a mass ratio of 1:0.6:0.4:4.5 to the reactor, and stir for 6 h at 42℃ and 0.02 MPaG.

[0100] 2) The reaction solution is sent to the first distillation column (14 theoretical plates, reflux ratio 0.6) for the first light component removal treatment. The temperature at the top of the column is controlled at 49-54℃ to collect the solvent and alcohol (methanol). The azeotropic temperature of diethyl ether and methanol is 48.3℃.

[0101] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 10, operating pressure 10 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 68-73℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0102] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0103] Example 9

[0104] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0105] 1) Add alkali metal alkoxide (potassium ethoxide), ethylene glycol monoalkyl ether (ethylene glycol monopropyl ether), ethylene glycol dialkyl ether (ethylene glycol dipropyl ether), and solvent (toluene) in a mass ratio of 1:1.0:0.7:3.5 to the reactor, and stir for 3.5 h at 55 °C and 0.03 MPaG.

[0106] 2) The reaction solution is sent to the first distillation column (13 theoretical plates, reflux ratio 0.9) for the first light component removal treatment. The temperature at the top of the column is controlled at 80-85℃ to collect the solvent and alcohol (ethanol). The azeotropic temperature of diethyl ether and ethanol is 76.7℃.

[0107] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 7, operating pressure 12 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 75-80℃, and the catalyst for ethyl silicate is obtained at the bottom of the column.

[0108] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0109] Example 10

[0110] The preparation method of the catalyst for ethyl silicate in this embodiment includes the following steps:

[0111] 1) Add alkali metal alkoxide (potassium isobutoxide), ethylene glycol monoalkyl ether (ethylene glycol monobutyl ether), ethylene glycol dialkyl ether (ethylene glycol dibutyl ether) and solvent (toluene) in a mass ratio of 1:0.8:0.5:4 to the reactor, and stir for 3 hours at 60°C and 0.05 MPaG.

[0112] 2) The reaction liquid is sent to the first distillation column (15 theoretical plates, reflux ratio 1.1) for the first light removal treatment. The temperature at the top of the column is controlled at 90-95℃ to collect the solvent and alcohol (isobutanol). The azeotropic temperature of toluene and isobutanol is 89.7℃.

[0113] 3) The bottom liquid of the column enters the second distillation column (theoretical plate number 9, operating pressure 15 kPaG) for the second light product removal treatment. By-products are separated at the top temperature of 100-105℃, and the bottom of the column yields the catalyst for ethyl silicate.

[0114] In this process, after the initial heat medium (heat transfer oil at 150°C) is used to heat the second light-weight removal process, the temperature is reduced to the first heat medium at 110°C. Subsequently, after the first light-weight removal process is used to heat the second heat medium at 75°C, the first reaction is then heated.

[0115] Comparative Example 1

[0116] The preparation method of the catalyst for the comparative example of ethyl silicate is basically the same as that in Example 1, except that ethylene glycol monoalkyl ether is not added in 1).

[0117] Comparative Example 2

[0118] The preparation method of the catalyst for the comparative example of ethyl silicate is basically the same as that in Example 2, except that ethylene glycol dialkyl ether is not added in 1).

[0119] Comparative Example 3

[0120] The preparation method of the catalyst for this comparative example of ethyl silicate is basically the same as that of Example 3, except that the second light removal treatment in 2) is at 50-55℃.

[0121] Experimental Example 1

[0122] The performance of the catalysts used in all examples and comparative examples of ethyl silicate was measured, and the results are shown in Table 1.

[0123] Catalytic performance: Silicon powder and catalyst were mixed at a mass ratio of 3:1, heated to 160℃, and then ethanol was added to react until no more hydrogen was produced in the system. After the reaction was completed, the reaction solution was filtered to obtain unreacted silicon powder. The conversion rate was calculated as (1 - mass of unreacted silicon powder / mass of initial silicon powder) × 100%. The filtrate was subjected to gas phase analysis, and ethyl silicate and other byproducts were quantified by comparison with standards. The selectivity was calculated as (molar amount of ethyl silicate / total molar amount of all silicon-containing products) × 100%.

[0124] Table 1

[0125]

[0126] As shown in Table 1, the ethyl silicate catalyst of this application has the advantage of high catalytic activity.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a catalyst for ethyl silicate, characterized in that, Includes the following steps: 1) A mixture comprising an alkali metal alkoxide, a monoalkyl ethylene glycol ether, a dialkyl ethylene glycol ether, and a solvent is subjected to a first reaction to obtain a first crude product; 2) The first crude product is subjected to a first light-removal treatment to obtain a second crude product; 3) The second crude product is subjected to a second light-removal treatment to obtain a catalyst for ethyl silicate; The removal temperature of the first light-removing treatment is 50-85℃, and the removal temperature of the second light-removing treatment is 60-110℃.

2. The preparation method according to claim 1, characterized in that, The mass ratio of alkali metal alkoxide, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether and solvent in the mixture is 1:0.5-1.2:0.3-0.8:3-5.

3. The preparation method according to claim 1 or 2, characterized in that, The alkali metal alkoxide includes compounds with the structure ROM, wherein R is selected from C1-C4 alkyl groups, and M is selected from at least one of Na, K, Li, Rb, and Cs.

4. The preparation method according to any one of claims 1-3, characterized in that, The temperature of the first reaction is 40-70℃ and the pressure is 0.01-0.05 MPaG.

5. The preparation method according to any one of claims 1-4, characterized in that, The first light-light removal process includes: subjecting the first crude product to a first distillation process, wherein the theoretical plate number of the first distillation process is 10-15, and the reflux ratio is 0.5-1.2; and / or, The second light-removal treatment includes: subjecting the second crude product to a second distillation process, wherein the theoretical plate number of the second distillation process is 4-12, and the operating pressure is 5-15 kPaG.

6. The preparation method according to any one of claims 1-5, characterized in that, The azeotropic temperature of the solvent and the alcohol corresponding to the alkali metal alkoxide is 50-85℃.

7. The preparation method according to any one of claims 1-6, characterized in that, The solvent includes at least one of cyclohexane, toluene, benzene, chloroform, n-hexane, and diethyl ether.

8. The preparation method according to any one of claims 1-7, characterized in that, The preparation method includes: after performing an initial heat exchange treatment on the second light-removal treatment using an initial heat medium, the initial heat medium is cooled to become a first heat medium; After the first heat medium is used to perform intermediate heat exchange treatment on the first light-weight removal process, the first heat medium is cooled down to become the second heat medium. The first reaction is subjected to heat treatment using the second heat medium.

9. A catalyst for ethyl silicate, characterized in that, It is obtained by the preparation method according to any one of claims 1-8.

10. A method for preparing ethyl silicate, characterized in that, Includes the following steps: A mixture comprising silicon powder, ethanol and a catalyst is subjected to an oxidation-reduction treatment to obtain ethyl silicate; the catalyst comprises the ethyl silicate catalyst according to claim 9.

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