A method for preparing a metal oxide-containing silica-based composite aerogel

Abstract

The application discloses a preparation method of a silicon-based composite aerogel containing metal oxides. The silicon-based composite aerogel is prepared by using a silicon source such as a silica sol or an ester silicate and an inorganic metal salt as a reaction raw material, an alcohol aqueous solution as a solvent, adjusting the pH value of a reaction solution to control the hydrolysis and polycondensation of the reactants, and obtaining a two-phase / multi-phase sol through one-step hydrolysis, so that the preparation process of the sol is simplified. In combination with a microwave curing process, the gel is rapidly prepared, and the obtained gel is subjected to solvent replacement and drying to obtain the silicon-based composite aerogel containing amorphous metal oxides. The silicon-based composite aerogel prepared by the method has excellent high-temperature resistance. After being treated at 1000 DEG C for 30 min, the silicon-based composite aerogel still maintains an amorphous phase structure, and the structure collapse caused by crystallization is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerogel materials, in particular to a preparation method of a silicon-based composite aerogel containing metal oxides. BACKGROUND

[0002] SiO2 aerogel is a solid material with a three-dimensional nanoporous network structure, and has the characteristics of high specific surface area, high porosity, low density and low thermal conductivity, and has a broad application prospect in the field of thermal insulation. However, the long-term use temperature of pure silicon-based aerogel is less than 650 DEG C, and the high-temperature resistance is poor, which greatly limits the application of SiO2 aerogel in the high-temperature section, and the production cycle of the existing silicon-based aerogel is long, and the production cost is high, which limits the large-scale application of aerogel in many civil fields. Therefore, it is necessary to improve the high-temperature resistance of SiO2 aerogel and reduce the production cost.

[0003] In order to improve the high-temperature resistance of aerogel, zirconia, alumina, titanium oxide and other oxides with high melting point and low thermal conductivity are also prepared as aerogel materials, which become ideal material system for high-efficiency thermal insulation materials in high-temperature section of 1000 DEG C. However, the metal source used for preparing this kind of aerogel material is usually organic metal alkoxide, and it is difficult to control the hydrolysis and polycondensation. Usually, hydrolysis inhibitors and proton scavengers are added to prepare block aerogel with three-dimensional skeleton structure. For example, CN103011280B discloses a preparation method of zirconia aerogel, which uses zirconium alkoxide as raw material and propylene oxide as gel promoter to prepare zirconia aerogel. Because organic metal alkoxide is used to prepare aerogel, it is difficult to control the hydrolysis and polycondensation, and the cost is high because of the high price of organic metal alkoxide. In addition, propylene oxide is flammable and explosive, and there is a great safety risk in the use process, so it is not suitable for large-scale production and industrial application. In addition, because zirconia, alumina and other polycrystalline oxides are used, the aerogel structure collapses, the material shrinks and the density increases at high temperature due to crystallization, phase change and grain growth. In addition, the high-temperature resistance of this kind of simple oxide aerogel is still not high enough, and the use temperature cannot break through 800 DEG C. SUMMARY

[0004] In view of the above problems in the prior art, the purpose of the present application is to provide a preparation method of a silicon-based composite aerogel containing metal oxides, which solves the problems of poor high-temperature resistance of aerogel materials prepared by the existing method, high cost of raw materials and safety risk in the preparation process.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] A preparation method of a silicon-based composite aerogel containing metal oxides, comprising the following steps:

[0007] S1, dissolving the inorganic metal salt in the alcohol aqueous solution, then adding a silicon source to the solution, and stirring until a clear and transparent mixed solution is obtained;

[0008] S2, adding an acid to the mixed solution obtained in step S1, adjusting the pH to 2-3 and controlling the hydrolysis rate, and hydrolyzing to obtain a uniform multi-phase sol;

[0009] S3, adding a basic solution to the multi-phase sol obtained in step S2, adjusting the pH to 6-7, and then placing the obtained sol in a microwave for solidification to obtain a wet gel;

[0010] S4, soaking the wet gel obtained in step S3 in an alcohol solvent for solvent replacement;

[0011] S5, drying the wet gel after solvent replacement in step S4 to obtain a silicon-based composite aerogel containing metal oxides.

[0012] Further, in step S1, the silicon source is water glass, silica sol or silicate.

[0013] Further, in step S1, the inorganic metal salt is one or more of zirconium oxychloride, zirconyl nitrate, zirconium carbonate, aluminum chloride, aluminum nitrate, yttrium nitrate, yttrium chloride, and titanium tetrachloride.

[0014] Further, in step S1, the concentration of the inorganic metal salt in the obtained mixed solution is 0.05-1.5 mol / L, and the concentration of the silicon source is 0.1-2 mol / L. In this way, the problem of difficult control of the hydrogel rate caused by too high concentration of the inorganic metal salt can be effectively avoided, and the density of the aerogel can be controlled to avoid the problems of too low strength or too large density of the aerogel, thereby improving its reliability in practical applications.

[0015] Further, in step S1, the volume percentage of alcohol in the alcohol aqueous solution is 60-85%. Water acts as both a solvent and a reactant, and controlling the volume percentage of alcohol to be 60-85% can avoid the problem of too much water being added, which results in too low concentration of the metal source and the silicon source, making the prepared aerogel soft and not strong enough for practical use.

[0016] Further, in step S2, the volume ratio of the acid to the mixed solution obtained in step S1 is 1-6:100. In this way, the pH of the solution can be adjusted to meet the conditions of the hydrolysis reaction, and the reaction rate of the hydrolysis can be controlled.

[0017] Further, in step S2, the hydrolysis conditions are 50-55℃ under stirring for 1-3h. In this way, the hydrolysis rate can be better controlled to facilitate obtaining a good aerogel structure.

[0018] Further, in the step S3, the time of microwave curing is 2-10 min. In this way, the preparation time can be controlled and shortened, and the final performance is not affected.

[0019] Further, in the step S3, the alkaline solution is one or more of ammonia, sodium hydroxide solution, ammonium acetate solution or urea solution. Since ammonium acetate can better control the gelation process and avoid flocculation and sedimentation of sol, ammonium acetate is preferably used to adjust the pH value.

[0020] Further, in the step S4, the soaking temperature is 45-60 DEG C, the soaking time is 24-48 h, and the fresh solvent is replaced every 4-8 h.

[0021] Further, in the step S1, the alcohol in the alcohol aqueous solution includes methanol, ethanol, isopropanol or n-propanol.

[0022] Further, in the step S2, the acid includes one or more of acetic acid, oxalic acid, nitric acid or hydrochloric acid.

[0023] Further, in the step S4, the drying is supercritical drying, and can be CO2 supercritical drying or ethanol supercritical drying.

[0024] Reaction principle: the present application uses silica sol or silicate as a silicon source, inorganic metal salt as a reaction raw material, and alcohol aqueous solution as a solvent, controls the hydrolysis and polycondensation of the reactants by adjusting the pH value of the reaction solution, and obtains a dual-phase / multi-phase sol in one step of hydrolysis, simplifies the sol preparation process, and realizes rapid preparation of a gel by combining a microwave curing process, so that the obtained gel is replaced by a solvent, dried, and a silicon-based composite aerogel containing amorphous metal oxide is obtained. The silicon-based composite aerogel prepared by the present application has excellent high-temperature resistance, and still maintains an amorphous structure after heat treatment at 1000 DEG C for 30 min, avoiding structural collapse caused by crystallization.

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

[0026] 1. The present application uses inexpensive and readily available inorganic metal salt as a raw material to prepare a silicon-based composite aerogel containing metal oxide, avoiding the use of high-cost organic metal alkoxide, and the cost is low; and the present application controls the hydrolysis and polycondensation of the raw materials by conventional acid and alkali to obtain a gel, compared with the preparation of a gel by propylene oxide method, avoiding the addition of flammable and explosive epoxy compound with high storage condition, friendly to human body and environment; and the process is simple, and can be produced in large scale.

[0027] 2、The one-step co-hydrolysis of the present application forms an organic-inorganic dual or multi-phase sol system, without the need for separate hydrolysis, simplifying the sol preparation process, and the introduced metal oxide can improve the high-temperature resistance of aerogel, and the silicon oxide can inhibit the crystallization and grain growth of the oxide, effectively overcoming the problem of metal oxide aerogel structure collapse at high temperature, and the obtained binary or multi-component oxide silicon-based composite aerogel has significantly improved temperature resistance and can withstand 1000℃ high temperature.

[0028] 3、Compared with the alcohol-water method and the propylene oxide method gel, the present application controls the hydrolysis and polycondensation of the sol by the amount of acid and base added, and combines the microwave curing process, shortening the sol-gel time from several hours to ten minutes, without aging, significantly shortening the preparation period, and facilitating large-scale preparation.

[0029] 4、The present application is suitable for the preparation of various high-temperature-resistant aerogels and has potential application value in the field of high-temperature insulation. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Process flow chart for the preparation method of the silicon-based composite aerogel containing metal oxide of the present application;

[0031] Figure 2 X-ray diffraction pattern (XRD pattern) of the aerogel prepared in Example 1 of the present application;

[0032] Figure 3 Actual photo of the aerogel prepared in Example 1 of the present application;

[0033] Figure 4 SEM (Scanning Electron Microscope) pattern of the Al2O3-SiO2 aerogel prepared in the present application;

[0034] Figure 5 Actual photo of the aerogel prepared in Example 2 of the present application;

[0035] Figure 6 Actual photo of the aerogel prepared in Example 3 of the present application;

[0036] Figure 7 Actual photo of the aerogel prepared in Example 4 of the present application. DETAILED DESCRIPTION

[0037] The specific embodiments of the present application will be further described in detail below in combination with specific examples.

[0038] The numerical ranges in this disclosure are to be understood as being inclusive of both the upper and lower limits of the ranges. Intermediary values between any stated or intervening values and any other stated or intervening values in any stated range or intervening range are also intended to be included in the disclosure. The upper and lower limits of these intervening ranges can independently be included or excluded in the ranges.

[0039] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All documents mentioned in this specification are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails. As used herein, the terms "comprise", "comprising", "include", "including", "contain", "containing", "have" and "having" are open-ended terms that are intended to mean "including but not limited to".

[0040] The experimental methods used in the present application are conventional methods unless otherwise specified.

[0041] The materials, reagents, etc. used in the present application can be purchased or synthesized by known methods unless otherwise specified.

[0042] In the quantitative test in the present application, three repeated experiments are set, and the average value is taken.

[0043] The present application proposes an innovative method for preparing aerogel materials with high temperature stability by using inexpensive inorganic salts as precursor metal sources and a low-toxicity and low-risk gel method, which is of great significance for improving the use temperature of aerogel materials and large-scale preparation and industrial application. The method does not use propylene oxide or other hazardous chemicals, but controls the gelation process through conventional acid-base, and at the same time adopts a high-efficiency gel solidification process, so that the gelation time can be shortened and controlled within 10 minutes, without aging, directly for rapid solvent replacement and drying. The method of the present application has simple process, shorter preparation period and strong universality, and can prepare a series of bulk aerogel materials containing metal oxide-containing silicon oxide, which can break through the existing traditional silicon-based aerogel temperature resistance temperature, and the aerogel structure can still remain stable at 1000℃ or above.

[0044] The preparation process of the preparation method of the metal oxide-containing silicon-based composite aerogel according to the present application is as shown in Figure 1 The preparation process of the preparation method of the metal oxide-containing silicon-based composite aerogel according to the present application is as shown in

[0045] S1, an inorganic metal salt is added to an alcohol water solution to dissolve, then a silicon source is added, and stirred until a clear and transparent mixed solution is obtained;

[0046] S2, adding acid to the mixed solution obtained in step S1 to adjust the pH to 2-3 and control the hydrolysis rate, and hydrolyzing to obtain a uniform multi-phase sol;

[0047] S3, adding a basic solution to the multi-phase sol obtained in step S2 to adjust the pH to 6-7, and then placing the obtained sol in a microwave for solidification to obtain a wet gel;

[0048] S4, soaking the wet gel obtained in step S3 in an alcohol solvent for solvent replacement;

[0049] S5, drying the wet gel after solvent replacement in step S4 to obtain a silicon-based composite aerogel containing metal oxides.

[0050] In specific implementation, the silicon source can be water glass, silica sol or silicate.

[0051] Embodiment 1

[0052] The embodiment provides a preparation method of an Al2O3-SiO2 composite aerogel, and the preparation steps include:

[0053] S1, preparing a sol by dissolving 22 g of aluminum chloride in a mixed solution of 908 mL of water and ethanol, and then adding 138 g of silica sol, and stirring at room temperature for 30 min to obtain a clear and transparent mixed solution; wherein the volume ratio of ethanol in the mixed solution of water and ethanol is 83%; and the concentration of the obtained clear and transparent mixed solution is 0.72 mol / L;

[0054] S2, adding acetic acid to the clear and transparent mixed solution obtained in step S1 to adjust the pH to 3 and control the hydrolysis rate; and hydrolyzing at 55°C for 2 h to obtain a uniform two-phase sol; the volume ratio of the acetic acid to the clear and transparent mixed solution obtained in step S1 is 4:100;

[0055] S3, adding an ammonia solution to the two-phase sol obtained in step S2 to adjust the pH to 6; and after uniform stirring, microwave solidification is performed for 7 min to obtain a wet gel block with a certain strength;

[0056] S4, soaking the wet gel block obtained in step S3 in anhydrous methanol for solvent replacement, the soaking temperature is 55°C, the soaking time is 24 h, and the fresh solvent is replaced every 8 h; the volume of the anhydrous methanol is 1.5 times the volume of the wet gel block;

[0057] S5, performing CO2 supercritical drying on the wet gel after solvent replacement in step S4 to obtain an intact block-shaped Al2O3-SiO2 aerogel.

[0058] The Al2O3-SiO2 aerogel prepared in this embodiment has a density of 42 kg / m³. 3 The specific surface area at multiple points is 600 m². 2 / g, after heat treatment at 1000℃ for 30 min, the specific surface area is 219 m². 2 / g, it can be seen that the Al2O3-SiO2 aerogel prepared by the present invention still has a large specific surface area after high-temperature heat treatment at 1000℃, maintains the porous structure of the aerogel, and has high-temperature resistance at 1000℃.

[0059] The XRD patterns of the Al2O3-SiO2 aerogel prepared in this embodiment before and after heat treatment are as follows: Figure 2 As shown, from Figure 2 It can be seen that the obtained aerogel has an amorphous structure, thus avoiding structural collapse caused by crystallization.

[0060] The actual image of the Al2O3-SiO2 aerogel prepared in this embodiment is shown below. Figure 3 As shown, by Figure 3 It can be seen that the Al2O3-SiO2 aerogel prepared by the present invention is a structurally complete aerogel block without cracks.

[0061] In practice, with other conditions remaining constant, by adjusting the proportion of the aluminum source, when the mass ratio of the aluminum source to the silicon source is 12%, the specific surface area of ​​the resulting Al2O3-SiO2 aerogel is 844 m². 2 / g, its SEM is as follows Figure 4 As shown, from Figure 4 It can be seen that the obtained Al2O3-SiO2 aerogel has the porous structure of an aerogel.

[0062] Example 2

[0063] This embodiment provides a method for preparing Y2O3-SiO2 composite aerogel, the preparation steps of which include:

[0064] S1: Sol preparation: 110g of yttrium nitrate was dissolved in a mixed solution of 825mL of water and ethanol, and then 133g of methyl orthosilicate was added. The mixture was stirred at room temperature for 30 min to obtain a clear and transparent mixed solution. The volume percentage of ethanol in the mixed solution of water and ethanol was 78%. The concentration of the clear and transparent mixed solution was 1.2mol / L.

[0065] S2: Add acetic acid to the clear and transparent mixed solution obtained in step S1, adjust the pH to 3 and control the hydrolysis rate; stir at 50°C for 2 h to carry out hydrolysis, and obtain a uniform biphase sol after hydrolysis; the volume ratio of the acetic acid to the clear and transparent mixed solution obtained in step S1 is 5:100.

[0066] S3: adding ammonia solution to the biphasic sol obtained in step S2 to adjust the pH to 6; after stirring uniformly, a wet gel block with certain strength is obtained by microwave curing for 6 min;

[0067] S4: soaking the wet gel block obtained in step S3 in anhydrous ethanol for solvent replacement, the soaking temperature is 55℃, the soaking time is 32h, and the fresh solvent is replaced every 8h; the volume of anhydrous ethanol is 1.5 times the volume of the wet gel block;

[0068] S5: performing CO2 supercritical drying on the wet gel block after solvent replacement in step S4 to obtain a complete block-shaped Y2O3-SiO2 aerogel.

[0069] The density of the Y2O3-SiO2 aerogel prepared in this embodiment is 100 kg / m 3 , the specific surface area of multiple points is 606 m 2 / g, and the specific surface area after heat treatment at 1000℃ is 320 m 2 / g. It can be seen that the Y2O3-SiO2 aerogel prepared by the present application still has a large specific surface area after high-temperature heat treatment at 1000℃, maintains the porous structure of the aerogel, and has 1000℃ high-temperature resistance.

[0070] The actual picture of the Y2O3-SiO2 aerogel prepared in this embodiment is shown in Figure 5 , as can be seen from Figure 5 , the Y2O3-SiO2 aerogel prepared by the present application has a complete structure and no cracks.

[0071] Example 3

[0072] The present embodiment provides a preparation method of ZrO2-SiO2 composite aerogel, and the preparation steps include:

[0073] S1: Sol preparation: 38 g of zirconium oxide nitrate is dissolved in a mixed solution of 790 mL of water and ethanol, followed by adding 137 g of tetraethyl orthosilicate, stirring at room temperature for 30 min to obtain a clear and transparent mixed solution; wherein the volume ratio of ethanol in the mixed solution of water and ethanol is 80%; the concentration of the obtained clear and transparent mixed solution is 0.8 mol / L;

[0074] S2: adding acetic acid and 1 M nitric acid to the clear and transparent mixed solution obtained in step S1 to adjust the pH to 2 and control the hydrolysis rate, stirring at 55℃ for 2 h for hydrolysis, and obtaining a uniform biphasic sol after hydrolysis; the volume ratio of acetic acid, nitric acid and the clear and transparent mixed solution obtained in step S1 is 1.3:1.5:100;

[0075] S3: ammonium acetate solution was added to the biphasic sol obtained in step S2 to adjust the pH to 7; after uniform stirring, the wet gel block with certain strength was obtained by microwave curing for 6 min;

[0076] S4: the wet gel block obtained in step S3 was soaked in anhydrous ethanol for solvent replacement, the soaking temperature was 55℃, the soaking time was 48h, and the fresh solvent was replaced every 8h; the volume of anhydrous ethanol was 2 times the volume of the wet gel block;

[0077] S5: the wet gel after solvent replacement in step S4 was subjected to CO2 supercritical drying to prepare a complete block-shaped ZrO2-SiO2 aerogel.

[0078] The density of the ZrO2-SiO2 aerogel prepared in this embodiment was 60 kg / m 3 , the specific surface area of multiple points was 883 m 2 / g, and the specific surface area was 244 m 2 / g after heat treatment at 1000℃ for 30 min. It can be seen that the ZrO2-SiO2 aerogel prepared by the present application still has a large specific surface area after high-temperature heat treatment at 1000℃, maintains the porous structure of the aerogel, and has 1000℃ high-temperature resistance.

[0079] The actual picture of the ZrO2-SiO2 aerogel prepared in this embodiment is shown in Figure 6 , as can be seen from Figure 6 , the ZrO2-SiO2 aerogel prepared by the present application has a complete structure and no cracks.

[0080] Example 4

[0081] The present embodiment provides a preparation method of ZrO2-Y2O3-SiO2 composite aerogel, and the preparation steps include:

[0082] S1: sol preparation: 53g of zirconium oxychloride and 5.5g of yttrium nitrate were dissolved in a mixed solution of 754mL of water and ethanol, then 187g of silica sol was added, and stirred at room temperature for 30min to obtain a clear and transparent mixed solution; wherein the volume ratio of ethanol in the mixed solution of water and ethanol is 80%; the concentration of the obtained clear and transparent mixed solution is 0.96mol / L;

[0083] S2: acetic acid was added to the clear and transparent mixed solution obtained in step S1 to adjust the pH to 2 and control the hydrolysis rate; hydrolysis was carried out at 50℃ for 2h with stirring, and a uniform multiphase sol was obtained after hydrolysis; the volume ratio of acetic acid to the clear and transparent mixed solution obtained in step S1 is 6:100;

[0084] S3: Add ammonia solution to the biphasic sol obtained in step S2 and adjust the pH to 7; after stirring evenly, microwave solidify for 5 minutes to obtain a wet gel block with a certain strength;

[0085] S4: Immerse the wet gel block obtained in step S3 in anhydrous ethanol for solvent replacement. The immersion temperature is 55℃ and the immersion time is 24h. Replace the solvent with fresh solvent every 4h. The volume of anhydrous ethanol is twice the volume of the wet gel block.

[0086] S5: The wet gel obtained from step S4 after solvent replacement is subjected to supercritical CO2 drying to prepare a complete block ZrO2-Y2O3-SiO2 aerogel.

[0087] The density of the ZrO2-Y2O3-SiO2 aerogel prepared in this embodiment is 63 kg / m³. 3 The specific surface area at multiple points is 773 m². 2 / g, after heat treatment at 1000℃ for 60 min, the specific surface area is 210 m². 2 / g, it can be seen that the ZrO2-Y2O3-SiO2 aerogel prepared by the present invention still has a large specific surface area after high-temperature heat treatment at 1000℃, maintains the porous structure of the aerogel, and has high-temperature resistance at 1000℃.

[0088] The physical image of the ZrO2-Y2O3-SiO2 aerogel prepared in this embodiment is shown below. Figure 7 As shown, by Figure 7 It can be seen that the ZrO2-Y2O3-SiO2 aerogel obtained by the present invention has a complete structure and is free of cracks.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a metal oxide-containing silica-based composite aerogel, characterized by, The method comprises the following steps: S1, dissolving the inorganic metal salt in the alcohol aqueous solution, then adding a silicon source to the solution, and stirring until a clear and transparent mixed solution is obtained; the inorganic metal salt is one or more of zirconium oxychloride, zirconyl nitrate, zirconium hydroxycarbonate, aluminum chloride, aluminum nitrate, and titanium tetrachloride; S2, adding an acid to the mixed solution obtained in step S1 to adjust the pH to 2-3 and control the hydrolysis rate, and hydrolyzing to obtain a uniform multi-phase sol; S3, adding a basic solution to the multi-phase sol obtained in step S2 to adjust the pH to 6-7, then placing the obtained sol in a microwave for solidification, and obtaining a wet gel; the microwave solidification time is 2-10 min; S4, placing the wet gel obtained in step S3 in an alcohol solvent for solvent replacement; S5, drying the wet gel after solvent replacement in step S4 to obtain a silicon-based composite aerogel containing metal oxides.

2. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S1, the silicon source is water glass, silica sol, or silicate.

3. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S1, the concentration of the inorganic metal salt in the obtained mixed solution is 0.05-1.5 mol / L; and the concentration of the silicon source is 0.1-2 mol / L.

4. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S1, the volume ratio of alcohol in the alcohol aqueous solution is 60-85%.

5. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S2, the volume ratio of the acid to the mixed solution obtained in step S1 is 1-6:

100.

6. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S2, the hydrolysis conditions are 50-55℃ under stirring for 1-3 h.

7. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S3, the basic solution is one or more of ammonia, sodium hydroxide solution, ammonium acetate solution, or urea solution.

8. The method of claim 1, wherein the metal oxide-containing silica-based composite aerogel is prepared by a process comprising: In step S4, the soaking temperature is 45-60℃, the soaking time is 24-48 h, and the fresh solvent is replaced every 4-8 h.

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