Preparation method of SiO2-Al2O3 gel solution and aerogel composite material
By using inorganic silicon and aluminum sources and controlling the pH value and solute mass fraction, SiO2-Al2O3 gel solutions were prepared, solving the problems of high production cost and uneven distribution, and realizing the industrial production and performance improvement of SiO2-Al2O3 aerogel composite materials.
Patent Information
- Application Number
- CN202410655112.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-24
- Publication Date
- 2025-11-25
AI Technical Summary
The production cost of SiO2-Al2O3 aerogel composite materials is high, the preparation process is complex and not easy to scale up for industrial use, and the gel solution is unevenly distributed in the porous matrix material, which affects the material properties.
SiO2-Al2O3 gel solution was prepared by using inorganic silicon and aluminum sources and controlling pH value and solute mass fraction to avoid precipitation. The long standing time and negative pressure impregnation and alcohol solvent replacement were used to achieve uniform distribution of gel in porous matrix material.
It reduced production costs, improved the thermal insulation performance and strength of aerogel composites, and enabled large-scale industrial production and uniform distribution.
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of SiO2-Al2O3 gel preparation method, in particular to the field of SiO2-Al2O3 gel solution and aerogel composite material preparation method. BACKGROUND
[0002] SiO2-Al2O3 aerogel material has good heat insulation performance, high temperature resistance; Especially the aerogel composite material has excellent heat insulation performance, high temperature resistance, and also has good strength;
[0003] There are certain difficulties in large-scale industrial production of SiO2-Al2O3 aerogel composite material. The main reasons are: 1) the preparation process cost of SiO2-Al2O3 aerogel is too high, the use of high-priced and toxic organic aluminum source (isopropyl alcohol aluminum, sec-butyl alcohol aluminum, etc.) and organic silicon source (methyl silicate, ethyl silicate, etc.) as raw materials, and epoxide as a coagulant. These organic aluminum source, silicon source and coagulant are expensive; the supercritical drying process is used to prepare SiO2-Al2O3 aerogel, and the equipment cost of supercritical drying process is high, the process control condition is extremely strict, and it has certain danger.
[0004] 2) The speed of silicon source and aluminum source after adding coagulant is fast, which is not conducive to the control of gel time, and easy to produce sedimentation;
[0005] 3) The stable state of SiO2-Al2O3 gel solution exists for a short time, and flocculation or gel state may occur within 20 minutes, which leads to uneven distribution of gel in the porous matrix material during the impregnation of SiO2-Al2O3 gel solution on the porous matrix material, and significantly reduces the performance of SiO2-Al2O3 aerogel composite material.
[0006] Therefore, how to reduce the production cost of SiO2-Al2O3 aerogel composite material, improve the uniformity of internal aerogel distribution of SiO2-Al2O3 aerogel composite material and improve the performance has become a difficult problem to be solved in the field. SUMMARY
[0007] The purpose of the present application is to provide a SiO2-Al2O3 gel solution and aerogel composite material preparation method, which reduces the production cost of SiO2-Al2O3 aerogel composite material, improves the uniformity of internal aerogel distribution of SiO2-Al2O3 aerogel composite material, and realizes large-scale industrial production of SiO2-Al2O3 aerogel composite material.
[0008] In one aspect of the present application, a SiO2-Al2O3 gel solution preparation method is provided, comprising the following steps:
[0009] The silicon source and the aluminum source are weighed according to the mass ratio of SiO2 to Al2O3 being (30-70):(70-30);
[0010] The silicon source is an inorganic substance, and the aluminum source is an inorganic substance; the weighed silicon source is prepared into a silicon source aqueous solution, and the weighed aluminum source is prepared into an aluminum source aqueous solution;
[0011] The silicon source aqueous solution is mixed with an acidic catalyst to obtain a silica sol solution; the silica sol solution is mixed with the aluminum source aqueous solution to obtain a silica sol solution;
[0012] The pH of the silica-alumina sol solution is adjusted to obtain a SiO2-Al2O3 gel solution; the SiO2-Al2O3 gel solution is used to prepare a SiO2-Al2O3 aerogel;
[0013] The SiO2-Al2O3 gel solution is allowed to stand for a time t without solidification or precipitation, and the time t is in the range of 60min≤t≤180min.
[0014] The beneficial effects of the present application over the prior art are that by using the silicon source as an inorganic substance and the aluminum source as an inorganic substance, the problems of high raw material cost and safety and environmental protection caused by using organic silicon source and aluminum source are avoided, and the addition of a coagulant is not required to obtain a gel solution;
[0015] By using the silicon source as an inorganic substance and the aluminum source as an inorganic substance in the preparation of a silica-alumina gel, the problems of precipitation and the presence of metal cations and anion impurities in the prepared silica-alumina gel are avoided;
[0016] By mixing the silicon source aqueous solution with an acidic catalyst to obtain a silica sol solution and mixing the silica sol solution with the aluminum source aqueous solution, the silica-alumina sol solution is obtained, and the problems of rapid hydrolysis of the silicon source and the aluminum source and precipitation in the preparation of the silica-alumina sol solution are avoided; by controlling the mass fraction of the solutes in the silicon source aqueous solution, the aluminum source aqueous solution and the acidic catalyst solution, the problems of precipitation and the like in the preparation of the silica-alumina sol solution are further avoided;
[0017] Meanwhile, by not removing the inorganic positive and negative ion impurities in the silica-alumina sol solution in the preparation of the silica-alumina gel solution, the time t for the SiO2-Al2O3 gel solution to stand without solidification or precipitation is relatively long;
[0018] Therefore, the production cost of the SiO2-Al2O3 aerogel composite material is reduced, the internal aerogel distribution uniformity of the SiO2-Al2O3 aerogel composite material is improved, and the large-scale industrial production of the SiO2-Al2O3 gel solution is realized.
[0019] Further, the preparation method of the SiO2-Al2O3 gel solution is characterized in that the silicon source comprises one of water glass, fly ash and silicon tetrachloride;
[0020] The aluminum source comprises one of aluminum nitrate, aluminum nitrate and aluminum chloride; preferably, the silicon source is water glass or fly ash.
[0021] Further, the mass fraction of the silicon source in the silicon source aqueous solution is 30%-50%;
[0022] The mass fraction of the aluminum source in the aluminum source aqueous solution is 30%-50%.
[0023] The beneficial effect of the above step is that by adjusting the mass fraction of the silicon source in the silicon source aqueous solution to 30%-50% and the mass fraction of the aluminum source in the aluminum source aqueous solution to 30%-50%, the mass fraction of the solute in the silicon source aqueous solution and the aluminum source aqueous solution is low, which is beneficial to avoid precipitation during the preparation of the silicon-aluminum sol.
[0024] Further, the preparation process of the acidic catalyst solution is to dissolve the acidic catalyst in water to obtain the acidic catalyst solution;
[0025] The mass fraction of the acidic catalyst in the acidic catalyst solution is 30-50%;
[0026] The acidic catalyst comprises one of hydrochloric acid, nitric acid, sulfuric acid, citric acid and acetic acid.
[0027] The beneficial effect of the above step is that by adjusting the mass fraction of the acidic catalyst in the acidic catalyst solution to 30-50%, the mass fraction of the acidic catalyst solution is low, which can realize the catalysis of the silicon source aqueous solution and the aluminum source aqueous solution to obtain the silicon-aluminum sol, and is beneficial to avoid precipitation.
[0028] Further, the preparation process of the silicon sol solution is to mix and stir the silicon source aqueous solution and the acidic catalyst solution, and adjust the pH of the mixed solution of the acidic catalyst solution and the silicon source aqueous solution to 2-4.
[0029] The beneficial effect of the above step is that when the pH of the mixed solution of the acidic catalyst solution and the silicon source aqueous solution is 2-4, the silicon sol solution is obtained, which is beneficial to the subsequent preparation of the silicon-aluminum sol to obtain the silicon-aluminum gel solution, and is beneficial to avoid precipitation when the acidic catalyst solution and the silicon source aqueous solution are added to the aluminum source aqueous solution.
[0030] Further, the pH of the silica-alumina sol solution is adjusted to 2-6, and then the mass fraction of the silica-alumina sol in the silica-alumina sol solution is adjusted to 60-90%, to obtain the SiO2-Al2O3 gel solution.
[0031] Preferably, the pH of the silica-alumina sol solution is adjusted to 4-6 by adding an acidic catalyst solution or distilled water, and the mass fraction of the silica-alumina sol in the silica-alumina sol solution is 25-50%; then drying is performed at 25-70°C, and the mass fraction of the silica-alumina sol in the silica-alumina sol solution is adjusted to 60-90%, to obtain the SiO2-Al2O3 gel solution.
[0032] The beneficial effect of the above step is that, by adjusting the pH of the silica-alumina sol solution to 2-6, the silica-alumina sol solution is slowly gelled, and by increasing the mass fraction of the silica-alumina sol to 60-90% due to the low mass fraction of the silica-alumina sol in the silica-alumina sol solution, the SiO2-Al2O3 gel solution is obtained; at the same time, since metal cations and acid anions and other impurities exist in the silica-alumina sol solution, the phenomenon of precipitation or flocculation does not occur when the mass fraction of the silica-alumina sol is increased to 60-90%.
[0033] In another aspect of the present application, a SiO2-Al2O3 gel composite material preparation method is provided, in which the SiO2-Al2O3 gel solution prepared by the SiO2-Al2O3 gel solution preparation method is used to prepare the SiO2-Al2O3 aerogel composite material.
[0034] The beneficial effect of the present application over the prior art is that, the standing time t of the SiO2-Al2O3 gel solution prepared by the SiO2-Al2O3 gel solution preparation method is in the range of 60min≤t≤180min, so that the gel is uniformly distributed in the porous matrix material during the impregnation of the SiO2-Al2O3 gel solution on the porous matrix material, and the heat insulation performance and strength of the SiO2-Al2O3 aerogel composite material are improved; and the silicon source and aluminum source used in the preparation process are low in cost, and the use of epoxide as a coagulant is not required, which further reduces the production cost; thus, it is beneficial to realize the industrialized mass production of the SiO2-Al2O3 aerogel composite material.
[0035] However, the SiO2-Al2O3 gel solution contains metal cations and acid anion impurities, so the metal cations and acid anion impurities are removed during the aging process after the SiO2-Al2O3 gel solution is impregnated on the porous matrix material, to obtain a stable SiO2-Al2O3 aerogel composite material.
[0036] Further, the SiO2-Al2O3 gel solution is vacuum-impregnated into a porous matrix material; the porous matrix material includes one of an aluminum silicate fiber blanket, a zirconium-containing aluminum silicate fiber blanket, a high-silica fiber blanket, a mullite fiber blanket, and a quartz fiber blanket;
[0037] The porous matrix material impregnated with the SiO2-Al2O3 gel solution is aged with deionized water, and the SiO2-Al2O3 gel solution is solidified inside the porous matrix material to obtain a SiO2-Al2O3 gel composite material;
[0038] The SiO2-Al2O3 gel composite material is pretreated, and the pretreatment process includes heating the SiO2-Al2O3 gel composite material in an alcohol solvent to replace the solvent, to obtain a pretreated SiO2-Al2O3 gel composite material; the heating temperature is 100-150°C;
[0039] The pretreated SiO2-Al2O3 gel composite material is subjected to atmospheric pressure drying to obtain the SiO2-Al2O3 aerogel composite material.
[0040] The beneficial effect of the above step is that by heating the SiO2-Al2O3 gel composite material in an alcohol solvent to replace the solvent, and the heating temperature is 100-150°C, the water in the SiO2-Al2O3 gel composite material is replaced by alcohol, which is conducive to the subsequent atmospheric pressure drying to obtain the SiO2-Al2O3 aerogel composite material.
[0041] Further, the specific process for aging the porous matrix material impregnated with the SiO2-Al2O3 gel solution is to place the porous matrix material impregnated with the SiO2-Al2O3 gel solution in distilled water, and to replace the water every 8-12 hours for 2-3 times;
[0042] The temperature of the distilled water is 30-80°C.
[0043] The beneficial effect of the above step is that while achieving the solidification of the SiO2-Al2O3 gel solution in the porous matrix material, the solubility of metal cations and acid anions and other impurities is improved by controlling the temperature of the distilled water to be 30-80°C, so that the impurity ions are removed from the silica-alumina gel.
[0044] Further, in the pretreatment process of the SiO2-Al2O3 gel composite material, the water in the SiO2-Al2O3 gel is replaced by an alcohol solvent by heating to a temperature of 100-150°C; the alcohol solvent includes one of ethanol, n-butanol, isobutyl alcohol, n-pentanol, and isoamyl alcohol;
[0045] The SiO2-Al2O3 aerogel composite material is prepared by the following steps.
[0046] The beneficial effect of the above step is that, by the atmospheric drying, the water in the silica-alumina gel is removed to obtain the SiO2-Al2O3 aerogel composite material, which significantly reduces the investment cost of the industrial production equipment and the energy cost of the preparation process, and is beneficial to realize large-scale industrial production of the SiO2-Al2O3 aerogel composite material. DETAILED DESCRIPTION
[0047] In order to better understand the technical solutions of the present application, the present application will be further described below in combination with specific examples.
[0048] Example 1
[0049] The present embodiment provides a preparation method of a SiO2-Al2O3 gel solution, comprising the following steps:
[0050] The silicon source and the aluminum source are weighed according to the mass ratio of SiO2 to Al2O3 being 50:50;
[0051] The silicon source is an inorganic substance, and the aluminum source is an inorganic substance; the silicon source includes water glass; and the aluminum source includes aluminum nitrate;
[0052] The weighed silicon source is prepared into a silicon source aqueous solution, and the weighed aluminum source is prepared into an aluminum source aqueous solution; the mass fraction of the silicon source in the silicon source aqueous solution is 40%; and the mass fraction of the aluminum source in the aluminum source aqueous solution is 40%;
[0053] The acid catalyst is mixed with the silicon source aqueous solution to obtain a silica sol solution; and the silica sol solution is mixed with the aluminum source aqueous solution to obtain a silica sol solution;
[0054] The preparation process of the acid catalyst solution is that the acid catalyst is dissolved in water to obtain the acid catalyst solution;
[0055] The mass fraction of the acid catalyst in the acid catalyst solution is 40%;
[0056] The acid catalyst includes nitric acid;
[0057] The preparation process of the silica sol solution is that the silicon source aqueous solution is mixed with the acid catalyst solution and stirred to adjust the pH of the mixed solution of the acid catalyst solution and the silicon source aqueous solution to 3.0;
[0058] Adjusting the pH of the silica-alumina sol solution to obtain a SiO2-Al2O3 gel solution; the SiO2-Al2O3 gel solution is used to prepare a SiO2-Al2O3 aerogel; the pH of the silica-alumina sol solution is adjusted to 5.5 by adding an acidic catalyst solution or distilled water to the silica-alumina sol solution, and the mass fraction of the silica-alumina sol in the silica-alumina sol solution is 37%; then the silica-alumina sol solution is dried at 30°C to adjust the mass fraction of the silica-alumina sol in the silica-alumina sol solution to 75% to obtain the SiO2-Al2O3 gel solution.
[0059] The SiO2-Al2O3 gel solution is allowed to stand for 120 min without solidification or precipitation.
[0060] Another aspect of the embodiment provides a method for preparing a SiO2-Al2O3 gel composite material, wherein the SiO2-Al2O3 gel solution prepared by the method for preparing a SiO2-Al2O3 gel solution is used to prepare a SiO2-Al2O3 aerogel composite material.
[0061] The SiO2-Al2O3 gel solution is subjected to negative pressure impregnation in a porous matrix material; the porous matrix material includes one of an aluminum silicate fiber blanket, a zirconium-containing aluminum silicate fiber blanket, a high-silica fiber blanket, a mullite fiber blanket, and a quartz fiber blanket.
[0062] The porous matrix material impregnated with the SiO2-Al2O3 gel solution is subjected to aging with deionized water, and the SiO2-Al2O3 gel solution is solidified in the interior of the porous matrix material to obtain a SiO2-Al2O3 gel composite material; the specific process for aging the porous matrix material impregnated with the SiO2-Al2O3 gel solution is that the porous matrix material impregnated with the SiO2-Al2O3 gel solution is placed in distilled water, and the water is replaced once every 10 h for 2 times; the temperature of the distilled water is 65°C.
[0063] The SiO2-Al2O3 gel composite material is subjected to pretreatment, and the pretreatment process includes heating the SiO2-Al2O3 gel composite material in an alcohol solvent to replace the solvent, to obtain a pretreated SiO2-Al2O3 gel composite material; the heating temperature is 125°C.
[0064] During the pretreatment of the SiO2-Al2O3 gel composite material, the alcohol solvent and water in the SiO2-Al2O3 gel are co-boiled by heating at a temperature of 125°C, so that the water in the SiO2-Al2O3 gel is replaced by the alcohol solvent, and the alcohol solvent includes n-pentanol.
[0065] The pretreated SiO2-Al2O3 gel composite material was dried under normal pressure to obtain the SiO2-Al2O3 aerogel composite material.
[0066] The specific process of drying the pretreated SiO2-Al2O3 gel composite material under normal pressure is as follows: the pretreated SiO2-Al2O3 gel composite material is dried under normal pressure in a drying equipment at 60-120℃ for 2.5 days to obtain the SiO2-Al2O3 aerogel composite material.
[0067] Example 2:
[0068] The contents that are the same as in Example 1 will not be repeated here; the different aspects of this embodiment compared to Example 1 are as follows:
[0069] This embodiment provides a method for preparing a SiO2-Al2O3 gel solution, wherein a silicon source and an aluminum source are weighed according to a SiO2 to Al2O3 mass ratio of 35:65.
[0070] The silicon source is an inorganic material, and the aluminum source is also an inorganic material; the silicon source includes fly ash; the aluminum source includes aluminum chloride.
[0071] The silicon source aqueous solution contains 35% silicon by mass; the aluminum source aqueous solution contains 35% aluminum by mass.
[0072] The acidic catalyst solution contains 35% acidic catalyst by mass.
[0073] The acidic catalyst includes hydrochloric acid;
[0074] The preparation process of the silica sol solution is as follows: the aqueous solution of the silicon source is mixed and stirred with the acidic catalyst solution. When the pH of the mixed solution of the acidic catalyst solution and the aqueous solution of the silicon source is 2.5, the addition of the acidic catalyst solution is stopped.
[0075] The pH of the silica-alumina sol solution was adjusted to 3.5 by adding an acidic catalyst solution or distilled water, resulting in a silica-alumina sol mass fraction of 35%. The solution was then dried at 30°C to adjust the silica-alumina sol mass fraction to 70%, thus obtaining the SiO2-Al2O3 gel solution.
[0076] The SiO2-Al2O3 gel solution is allowed to stand without solidification or precipitation for a period of 170 min.
[0077] Another aspect of this embodiment provides a method for preparing SiO2-Al2O3 gel composite material. The specific process for aging the porous matrix material impregnated with the SiO2-Al2O3 gel solution involves placing the porous matrix material impregnated with the SiO2-Al2O3 gel solution in distilled water, changing the water every 8.5 hours, for a total of 3 times; the temperature of the distilled water is 38℃.
[0078] During the pretreatment of the SiO2-Al2O3 gel composite material, the water in the SiO2-Al2O3 gel is replaced with an alcohol solvent by heating at 138°C, and the alcohol solvent includes ethanol.
[0079] The pretreated SiO2-Al2O3 aerogel composite material was dried at atmospheric pressure in a drying device at 110°C for 2.8 days to obtain the SiO2-Al2O3 aerogel composite material.
[0080] Example 3:
[0081] The contents that are the same as in Example 1 will not be repeated here; the different aspects of this embodiment compared to Example 1 are as follows:
[0082] This embodiment provides a method for preparing a SiO2-Al2O3 gel solution, wherein a silicon source and an aluminum source are weighed according to a SiO2 to Al2O3 mass ratio of 65:35.
[0083] The silicon source is an inorganic material, and the aluminum source is an inorganic material; the aluminum source includes aluminum nitrate.
[0084] The silicon source aqueous solution contains 46% silicon by mass; the aluminum source aqueous solution contains 46% aluminum by mass.
[0085] The acidic catalyst solution contains 46% acidic catalyst by mass.
[0086] The acidic catalyst includes sulfuric acid;
[0087] The preparation process of the silica sol solution is as follows: the aqueous solution of the silicon source is mixed and stirred with the acidic catalyst solution. When the pH of the mixed solution of the acidic catalyst solution and the aqueous solution of the silicon source is 2.5, the addition of the acidic catalyst solution is stopped.
[0088] The pH of the silica-alumina sol solution was adjusted to 5.8 by adding an acidic catalyst solution or distilled water, resulting in a silica-alumina sol mass fraction of 46%. The solution was then dried at 26°C to adjust the silica-alumina sol mass fraction to 85%, thus obtaining the SiO2-Al2O3 gel solution.
[0089] The SiO2-Al2O3 gel solution is allowed to stand without solidification or precipitation for a period of 80 minutes.
[0090] Another aspect of this embodiment provides a method for preparing SiO2-Al2O3 gel composite material. The specific process for aging the porous matrix material impregnated with the SiO2-Al2O3 gel solution involves placing the porous matrix material impregnated with the SiO2-Al2O3 gel solution in distilled water, changing the water every 11 hours for a total of 3 times; the temperature of the distilled water is 42℃.
[0091] During the pretreatment of the SiO2-Al2O3 gel composite material, the alcohol solvent and the water in the SiO2-Al2O3 gel are azeotropically heated to 112°C, thereby replacing the water in the SiO2-Al2O3 gel with an alcohol solvent, including isobutanol.
[0092] The pretreated SiO2-Al2O3 aerogel composite material was dried at atmospheric pressure in a drying device at 60-120℃ for 2.2 days to obtain the SiO2-Al2O3 aerogel composite material.
[0093] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, the above-described features have similar functions to (but are not limited to) those disclosed in this application.
Claims
1. A method for preparing a SiO2-Al2O3 gel solution, characterized in that, Includes the following steps: Weigh out the silicon source and aluminum source according to the mass ratio of SiO2 to Al2O3 of (30-70):(70-30); The silicon source is an inorganic material, and the aluminum source is an inorganic material; Prepare an aqueous solution of silicon source by weighing out silicon source, and prepare an aqueous solution of aluminum source by weighing out aluminum source; A silica sol solution was prepared by mixing and stirring an aqueous solution of a silicon source with an acidic catalyst; a silica sol solution was then prepared by mixing and stirring an aqueous solution of an aluminum source. The pH of the silica-alumina sol solution was adjusted to obtain a SiO2-Al2O3 gel solution; the SiO2-Al2O3 gel solution was used to prepare SiO2-Al2O3 aerogel. The SiO2-Al2O3 gel solution does not solidify or precipitate within a time frame of 60 min ≤ t ≤ 180 min.
2. The method for preparing SiO2-Al2O3 gel solution according to claim 1, characterized in that, The silicon source includes one of water glass, fly ash, and silicon tetrachloride; The aluminum source includes one of aluminum sulfate, aluminum nitrate, and aluminum chloride.
3. The method for preparing SiO2-Al2O3 gel solution according to claim 1, characterized in that, The mass fraction of silicon source in the aqueous silicon source solution is 30%-50%; The mass fraction of aluminum source in the aqueous aluminum source solution is 30%-50%.
4. The method for preparing SiO2-Al2O3 gel solution according to claim 1, characterized in that, The acidic catalyst solution is prepared by dissolving the acidic catalyst in water. The mass fraction of the acidic catalyst in the acidic catalyst solution is 30-50%. The acidic catalyst includes one of hydrochloric acid, nitric acid, sulfuric acid, citric acid, and acetic acid.
5. The method for preparing SiO2-Al2O3 gel solution according to claim 1, characterized in that, The preparation process of the silica sol solution is as follows: mixing and stirring the aqueous solution of the silicon source and the acidic catalyst solution, and adjusting the pH of the mixed solution of the acidic catalyst solution and the aqueous solution of the silicon source to 2-4.
6. The method for preparing SiO2-Al2O3 gel solution according to claim 1, characterized in that, The pH of the silica-alumina sol solution is adjusted to 2-6, and then the mass fraction of silica-alumina sol in the silica-alumina sol solution is adjusted to 60-90% to obtain the SiO2-Al2O3 gel solution.
7. A method for preparing SiO2-Al2O3 aerogel composite material, characterized in that, The SiO2-Al2O3 aerogel was prepared using the SiO2-Al2O3 gel solution described in claims 1-6.
8. The method for preparing SiO2-Al2O3 aerogel composite material according to claim 7, characterized in that, The SiO2-Al2O3 gel solution is impregnated into a porous matrix material under negative pressure; the porous matrix material includes one of the following: aluminosilicate fiber blanket, zirconium-containing aluminosilicate fiber blanket, high-silica fiber blanket, mullite fiber blanket, and quartz fiber blanket. The porous matrix material impregnated with SiO2-Al2O3 gel solution is aged with deionized water, and the SiO2-Al2O3 gel solution is solidified inside the porous matrix material to obtain SiO2-Al2O3 gel composite material. The SiO2-Al2O3 gel composite material is pretreated. The pretreatment process includes heating the SiO2-Al2O3 gel composite material in an alcohol solvent to replace the solvent, thereby obtaining the pretreated SiO2-Al2O3 gel composite material. The heating temperature is 100-150℃. The pretreated SiO2-Al2O3 gel composite material was dried under normal pressure to obtain the SiO2-Al2O3 aerogel composite material.
9. The method for preparing SiO2-Al2O3 aerogel composite material according to claim 8, characterized in that, The specific process for aging the porous matrix material impregnated with SiO2-Al2O3 gel solution is as follows: the porous matrix material impregnated with SiO2-Al2O3 gel solution is placed in distilled water, and the water is changed once every 8-12 hours, and the number of water changes is 2-3 times. The temperature of the distilled water is 30-80℃.
10. The method for preparing SiO2-Al2O3 aerogel composite material according to claim 8, characterized in that, During the pretreatment of the SiO2-Al2O3 gel composite material, the water in the SiO2-Al2O3 gel is replaced with an alcohol solvent by heating at a temperature of 100-150℃. The alcohol solvent includes one of ethanol, n-butanol, isobutanol, n-pentanol, and isopentanol. The specific process of drying the pretreated SiO2-Al2O3 gel composite material under normal pressure is as follows: the pretreated SiO2-Al2O3 gel composite material is dried under normal pressure in a drying equipment at 60-120℃ for 2-3 days to obtain the SiO2-Al2O3 aerogel composite material.