Silicon dioxide aerogel, preparation method thereof and composite aerogel material
By using tetraalkoxysilane and alkenyltrichlorosilane derivatives to modify the silica wet gel, the problem of the easy powder loss of traditional silica aerogels is solved, and higher structural strength and thermal insulation properties are achieved.
Patent Information
- Application Number
- CN202510150355.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-11
- Publication Date
- 2025-04-15
AI Technical Summary
Traditional silica aerogels tend to lose powder after drying, resulting in poor strength, affecting their stability and thermal insulation performance during transportation, construction and use.
Tetraalkoxysilane is used as the silicon source, and hydrophobic modification is performed with a trichlorosilane derivative with an alkenyl substituent as a modifier to form a modified wet gel, and a silica aerogel that is not easy to lose powder is obtained by drying.
It improves the hydrophobicity and structural strength of silica aerogel, reduces powder loss rate, and enhances its stability and thermal insulation performance during use.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] The present application relates to the field of aerogel materials, and in particular to a silica aerogel and a preparation method thereof, and a composite aerogel material. Background Art
[0002] Silica aerogel is a nanoporous material with high porosity, high specific surface area, low light refractive index, low sound propagation velocity, low thermal conductivity, non-flammability and high temperature resistance. Due to these characteristics, silica aerogel is widely used in high and low temperature insulation, space field, catalyst carrier and other fields.
[0003] However, the surface of wet silica gel usually has hydrophilic hydroxyl groups, which makes wet silica gel easy to combine with water, resulting in large drying stress in the process of preparing silica aerogel, which is easy to damage the skeleton structure of silica aerogel, making the particle connection of silica aerogel after drying relatively fragile. In some weakly connected areas, the particles are only composed of a small amount of silicon-oxygen bonds, the connection area is small, and it is easy to break. The above structural characteristics make the strength of traditional silica aerogel poor. During transportation, construction and use, there is a common problem of easy powder loss, which not only brings inconvenience to construction, but also may threaten the health of construction workers, and reduce the thermal insulation performance of silica aerogel, which seriously restricts the promotion and application of silica aerogel composite aerogel materials. Summary of the invention
[0004] Based on this, it is necessary to provide a silica aerogel and a preparation method thereof, and a composite aerogel material to overcome the problem that traditional silica aerogels are prone to powdering.
[0005] In a first aspect of the present application, a method for preparing a silica aerogel is provided.
[0006] A method for preparing a silica aerogel comprises the following steps:
[0007] mixing a silicon source precursor, ethanol and water to form a silica sol;
[0008] Aging and solvent replacement of the silica sol to form a silica wet gel;
[0009] Using a modifier to hydrophobically modify the silicon dioxide wet gel to form a modified wet gel;
[0010] Drying the modified wet gel;
[0011] Wherein, the silicon source precursor is tetraalkoxysilane, and the modifier includes a trichlorosilane derivative whose substituent is an alkenyl group.
[0012] In some embodiments, the tetraalkoxysilane includes one or more of methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, and isopropyl orthosilicate.
[0013] In some embodiments, the modifier includes one or more of vinyltrichlorosilane, 2-propenyltrichlorosilane, 2-butenyltrichlorosilane, 5-hexenyltrichlorosilane, and 7-octenyltrichlorosilane.
[0014] In some embodiments, the hydrophobic modification step includes placing the wet silica gel in a first solution containing the modifier.
[0015] In some embodiments, the hydrophobic modification satisfies one or more of the following conditions:
[0016] (1) The temperature of the hydrophobic modification is 25°C to 70°C;
[0017] (2) The hydrophobic modification time is 12h~72h;
[0018] (3) The mass concentration of the modifier in the first solution is 5% to 40%.
[0019] In some embodiments, the step of mixing the silicon source precursor, ethanol and water comprises:
[0020] Mixing the silicon source precursor, the ethanol and the water in a molar ratio of 1:(2-4):(9-16) to obtain a mixed solution;
[0021] Adjusting the pH of the mixed solution to 2-6 to form a prepolymer solution;
[0022] The pH of the prepolymer solution is adjusted to 7-10.
[0023] In some embodiments, the aging step includes placing the silica sol in an aging solution.
[0024] In some embodiments, the aging solution includes one or more of water, ethanol, n-hexane, acetone and the silicon source precursor. In a second aspect of the present application, a silica aerogel is provided.
[0025] A silicon dioxide aerogel is prepared by adopting the above-mentioned method for preparing the silicon dioxide aerogel.
[0026] In a third aspect of the present application, a composite aerogel material is provided.
[0027] A composite aerogel material contains the above-mentioned silica aerogel.
[0028] The above-mentioned silica aerogel preparation method uses tetraalkoxysilane as a silicon source to prepare silica wet gel. On this basis, the silica wet gel is modified by using a trichlorosilane derivative with an alkenyl substituent as a modifier, thereby giving the modified wet gel a large number of carbon-carbon double bond functional groups, thereby effectively improving the hydrophobicity of the modified wet gel. After drying, a silica aerogel that is not easy to fall off can be obtained. DETAILED DESCRIPTION
[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.
[0030] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In this application, "at least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc.
[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.
[0032] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.
[0033] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
[0034] In this application, "above" or "below" includes the number itself. For example, "1 below" includes 1.
[0035] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.
[0036] the term
[0037] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:
[0038] "Alkenyl" refers to a group containing at least one unsaturated site, i.e., a carbon-carbon sp 2 A monovalent residue formed by a hydrogen atom of a hydrocarbon with a double bond, a secondary carbon atom, a tertiary carbon atom or a ring carbon atom. Suitable examples include, but are not limited to, vinyl (-CH=CH2), allyl (-CH2CH=CH2), cyclopentenyl (-C5H7), 5-hexenyl (-CH2CH2CH2CH2CH=CH2).
[0039] Rational use of energy and energy conservation are of great significance to the sustainable development of the economy. Using new technologies and processes to develop environmentally friendly thermal insulation materials is one of the most effective and economical measures to save energy, which can not only reduce energy consumption, but also reduce environmental burden and promote green development.
[0040] Silica aerogel is a nanoporous material with high porosity, high specific surface area, low light refractive index, low sound propagation velocity, low thermal conductivity, non-flammability and high temperature resistance. Due to these characteristics, silica aerogel is widely used in high and low temperature insulation, space field, catalyst carrier and other fields.
[0041] However, the particle connections of traditional silica aerogels are relatively fragile. In some weakly connected areas, the particles are only composed of a small amount of silicon-oxygen bonds, the connection area is small, and it is easy to break. The above structural characteristics make the strength of traditional silica aerogels poor. During transportation, construction and use, there is a common problem of easy powder loss, which not only brings inconvenience to construction, but also may threaten the health of construction workers and reduce the thermal insulation performance of silica aerogels, which seriously restricts the promotion and application of silica aerogel composite aerogel materials. Therefore, it is very necessary to develop an aerogel material that does not lose powder in order to protect the health of production personnel and users, and meet various market needs.
[0042] In view of the shortcomings of the conventional technology, one embodiment of the present application relates to a method for preparing a silica aerogel. The method for preparing a silica aerogel can be used to obtain a silica aerogel that is not prone to powdering.
[0043] The preparation method of silica aerogel comprises the following steps:
[0044] mixing a silicon source precursor, ethanol and water to form a silica sol;
[0045] The silica sol is subjected to aging and solvent replacement to form a silica wet gel;
[0046] Using a modifier to hydrophobically modify the silica wet gel to form a modified wet gel;
[0047] The modified wet gel is dried to obtain silica aerogel.
[0048] The silicon source precursor is tetraalkoxysilane. The modifier includes a trichlorosilane derivative having an alkenyl substituent. It can be understood that tetraalkoxysilane refers to a silane compound having four silicon-oxygen substituents (-OR, R is an alkyl group) connected to the silicon atom.
[0049] The present application adopts a trichlorosilane derivative with an alkenyl substituent as a modifier, and obtains a modified silica wet gel containing a hydrophobic functional group by condensing the alkenyl group into the network structure of the silica wet gel through a condensation reaction with the Si-OH group remaining on the surface of the silica wet gel.
[0050] In some embodiments, the modifier includes one or more of vinyltrichlorosilane, 2-propenyltrichlorosilane, 2-butenyltrichlorosilane, 5-hexenyltrichlorosilane, and 7-octenyltrichlorosilane.
[0051] In order to reduce the influence of water on the drying process of silica wet gel, the silica wet gel needs to be hydrophobically modified. However, the surface of the silica wet gel obtained after aging is mostly hydrophilic silanol, while the alkenyl group is a hydrophobic group, resulting in poor compatibility between the modifier with hydrophobic groups and the sol particles, further resulting in a prolonged tightening reaction time, poor reaction efficiency, and ultimately resulting in fewer hydrophobic groups in the modified wet gel. For this reason, the present application uses a silane coupling agent with a chlorine group to increase the reaction rate of the hydrophobic modification, so as to increase the number and efficiency of the grafted hydrophobic groups (alkenyl groups). At the same time, considering that when selecting a silane coupling agent with multiple substituent branches, the same incompatibility problem will be faced, and the presence of steric hindrance will further hinder the reaction. To this end, the present application selects trichlorosilane derivatives with multiple chlorine-substituted groups, and utilizes the characteristics of trichlorosilane derivatives with small steric hindrance and good compatibility to introduce more hydrophobic groups into the structure of silica wet gel, thereby giving the silica wet gel better hydrophobicity, which is conducive to obtaining silica aerogel with high structural strength and not easy to fall off after drying.
[0052] In some embodiments, the tetraalkoxysilane includes one or more of methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, and isopropyl orthosilicate. Alternatively, the tetraalkoxysilane may be one or more of methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, and isopropyl orthosilicate, and may also contain other compounds with similar structures.
[0053] In some embodiments, the step of mixing the silicon source precursor, ethanol and water comprises:
[0054] Mixing a silicon source precursor, ethanol and water in a molar ratio of 1:(2-4):(9-16) to obtain a mixed solution;
[0055] Adjusting the pH of the mixed solution to 2-6 to form a prepolymer solution;
[0056] Adjust the pH of the prepolymer solution to 7~10.
[0057] Keeping the molar ratio of silicon source precursor, ethanol and water within the above range is conducive to forming a silica sol with low shrinkage and high porosity. Optionally, the molar ratio of silicon source precursor, ethanol and water can be but not limited to 1:2:9, 1:2:12, 1:2:16, 1:3:9, 1:3:12, 1:3:16, 1:4:9, 1:4:12, 1:4:16 or other ratios within the range of 1:(2~4):(9~16).
[0058] In some embodiments, after adjusting the pH of the mixed solution to 2-6, the prepolymer solution is hydrolyzed for 0.5-4 hours. Alternatively, the hydrolysis time can be 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours or other values within the range of 0.5 hours to 4 hours.
[0059] In some embodiments, after adjusting the pH of the prepolymer solution to 7-10, the prepolymer solution is polycondensed for 0.5-4 hours to form a silica sol. Optionally, the polycondensation time can be 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or other values within the range of 0.5 hours to 4 hours.
[0060] After the silicon source precursor undergoes hydrolysis and condensation, a primary gel network will be constructed to form a silica sol. At this time, only a few silicon-oxygen bonds in the gel network will be connected together, and the structural strength is low. For this reason, the silica sol needs to be aged to form a silica wet gel with higher structural strength.
[0061] In some embodiments, the aging step includes placing the silica sol in an aging solution and allowing the solution to stand.
[0062] In some embodiments, the aging solution includes one or more of water, ethanol, n-hexane, acetone, and a silicon source precursor.
[0063] In some embodiments, the aging solution may be an ethanol solution of ethyl orthosilicate having a mass concentration of 1% to 20%.
[0064] In some embodiments, during aging, the standing time is 6 hours to 72 hours. The standing aging time can be but is not limited to 6 hours, 12 hours, 18 hours, 24 hours, 30 hours, 36 hours, 42 hours, 48 hours, 54 hours, 60 hours, 66 hours, 72 hours or other values within the range of 6 hours to 72 hours.
[0065] In some embodiments, during aging, the static temperature is maintained at 25° C. to 70° C. The static aging temperature can be, but is not limited to, 25° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C. or other values within the range of 25° C. to 70° C.
[0066] During aging, when the system temperature is low, the molecular kinetic energy in the system is relatively low, the molecular motion is relatively stable, the hydrolysis and polycondensation reactions slow down, and the degree of crosslinking of the obtained silica wet gel is low. When the temperature is too high, the hydrolysis and condensation reaction rates will be too fast, which will easily lead to the volume shrinkage of the wet gel. In the temperature range of 25℃~70℃, it is conducive to obtaining silica wet gel with high structural strength.
[0067] The structure of the aged silica wet gel preform contains a large amount of water. The surface tension of water is large, and the stress during drying is large, which can easily affect the skeleton structure of the silica aerogel. Therefore, it is necessary to use a solvent with low surface tension to perform solvent replacement to remove the residual water inside the gel.
[0068] In some embodiments, the step of solvent replacement comprises:
[0069] immersing the silicon dioxide wet gel preform in a replacement solvent and allowing it to stand or stir;
[0070] Repeat the above steps 0 to 6 times.
[0071] Wherein, the replacement solvent includes one or more of n-hexane, cyclohexane, n-heptane and acetone.
[0072] During the solvent replacement, the water in the wet silica gel will be exchanged with the organic solvent. It can be understood that repeating the above operation means: repeating the steps of immersing the wet silica gel in the organic solvent and letting it stand. When the number of repeated operations is 0, it means that no repeated operation is performed.
[0073] In some embodiments, during solvent replacement, the volume ratio of the wet silica gel to the replacement solvent is 1:1 to 1:4. The volume ratio of the wet silica gel to the organic solvent can be, but is not limited to, 1:1, 1:2, 1:3, 1:4 or other values within the range of 1:1 to 1:4.
[0074] In some embodiments, the temperature of the solvent replacement is 25° C. to 60° C. The temperature of the solvent replacement can be, but is not limited to, 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C. or other values within the range of 25° C. to 60° C.
[0075] In some embodiments, the standing time of the solvent replacement is 1 h to 12 h. The standing time can be but is not limited to 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h or other values within the range of 1 h to 12 h.
[0076] In some embodiments, the step of hydrophobically modifying the silicon dioxide wet gel using a modifying agent comprises: placing the wet gel in a first solution containing the modifying agent.
[0077] In some embodiments, the solvent of the first solution includes one or more of toluene, dichloromethane, n-hexane and n-heptane.
[0078] In some embodiments, the temperature of hydrophobic modification is 25° C. to 70° C. The heating temperature of hydrophobic modification can be, but is not limited to, 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C. or other values within the range of 25° C. to 70° C.
[0079] In some embodiments, the hydrophobic modification time is 12 hours to 72 hours. The stirring time of the hydrophobic modification can be but is not limited to 12 hours, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours or other values within the range of 12 hours to 72 hours.
[0080] In some embodiments, in the first solution, the mass concentration of the modifier is 5% to 40%. The mass concentration of the modifier includes but is not limited to 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or other values within the range of 5% to 40%.
[0081] In some embodiments, the first solution is continuously stirred during the hydrophobic modification process.
[0082] In some embodiments, the drying method includes drying at normal pressure. Through the drying step, the liquid phase inside the modified wet gel can be replaced by a gas phase to obtain a silica aerogel.
[0083] In some embodiments, the step of drying at normal pressure includes: drying the modified wet gel at 25° C. to 60° C. for 12 h to 48 h, heating to 100° C. to 200° C., and continuing drying for 1 h to 4 h.
[0084] In some embodiments, supercritical drying is used to dry the modified silica wet gel.
[0085] In one embodiment of the present application, a silica aerogel is provided. The silica aerogel is prepared by the above-mentioned method for preparing silica aerogel.
[0086] In another embodiment of the present application, a composite aerogel material is provided, wherein the composite aerogel material contains the above-mentioned silica aerogel.
[0087] In some embodiments, the composite aerogel material further comprises fibers. Optionally, the fibers comprise one or both of glass fibers and ceramic fibers.
[0088] The present application is further described in detail below in conjunction with specific embodiments.
[0089] In the following specific embodiments and comparative examples, the raw materials used, unless otherwise specified, are all commercially available products; the instruments used, unless otherwise specified, are all commercially available products; and the processes used, unless otherwise specified, are all routinely selected by those skilled in the art.
[0090] Example 1
[0091] This embodiment provides a silicon dioxide aerogel.
[0092] The preparation method of silica aerogel is:
[0093] Methyl orthosilicate, ethanol and water were mixed in a molar ratio of 1:4:12, and the pH was adjusted to 3 with hydrochloric acid, and hydrolyzed for 4 hours. Ammonia water was used to adjust the pH to 8, and polycondensed for 4 hours to obtain silica sol. The silica sol was placed in a 10wt% ethanol solution of ethyl orthosilicate and aged for 48 hours. The aged silica sol was placed in a n-hexane solvent, and the solvent was replaced at room temperature, and the stirring was continued for 12 hours. Repeated 4 times to obtain a wet silica gel.
[0094] At 30°C, the silicon dioxide wet gel was placed in a 25wt% vinyl trichlorosilane n-hexane solution for hydrophobic modification and continued to be immersed for 36 hours to obtain a modified wet gel. The silicon dioxide aerogel was obtained by drying at normal pressure. The drying conditions were: drying at 60°C for 24 hours and then drying at 120°C for 4 hours.
[0095] Example 2
[0096] This embodiment provides a silicon dioxide aerogel.
[0097] The preparation method of silica aerogel is:
[0098] TEOS, ethanol and water were mixed in a molar ratio of 1:5:13, and the pH was adjusted to 3 with hydrochloric acid, and hydrolyzed for 4 hours. Ammonia water was used to adjust the pH to 8, and polycondensed for 4 hours to obtain silica sol. The silica sol was placed in a 10wt% ethanol solution of TEOS and aged for 48 hours. The aged silica sol was placed in a n-hexane solvent, and the solvent was replaced at room temperature, and the stirring was continued for 12 hours. This was repeated 4 times to obtain a wet silica gel.
[0099] At 30°C, the silicon dioxide wet gel was placed in a 25wt% vinyl trichlorosilane n-hexane solution for hydrophobic modification and continued to be immersed for 36 hours to obtain a modified wet gel. The silicon dioxide aerogel was obtained by drying at normal pressure. The drying conditions were: drying at 60°C for 24 hours and then drying at 120°C for 4 hours.
[0100] Example 3
[0101] This embodiment provides a silicon dioxide aerogel.
[0102] The difference between the silica aerogel of this embodiment and that of embodiment 1 is that the wet silica gel is placed in a 5 wt % n-hexane solution of vinyltrichlorosilane for hydrophobic modification.
[0103] Example 4
[0104] This embodiment provides a silicon dioxide aerogel.
[0105] The difference between the silica aerogel of this embodiment and that of embodiment 1 is that the wet silica gel is placed in a 40 wt % n-hexane solution of vinyltrichlorosilane for hydrophobic modification.
[0106] Comparative Example 1
[0107] This comparative example provides a silica aerogel.
[0108] The silica aerogel is directly obtained from the silica wet gel by CO2 supercritical drying. The preparation method of the silica wet gel is the same as that of Example 1.
[0109] Comparative Example 2
[0110] This comparative example provides a silica aerogel.
[0111] The silica aerogel in this comparative example is different from that in Example 1 in that the modifier is trimethylchlorosilane.
[0112] Comparative Example 3
[0113] This comparative example provides a silica aerogel.
[0114] The silica aerogel in this comparative example is different from that in Example 3 in that the modifier is trimethylchlorosilane.
[0115] Test Case
[0116] The performance of the silica aerogels of the above examples and comparative examples was tested, and the test results are shown in Table 1.
[0117] Powder loss rate: The silica aerogel was placed on a vibrating shaker and vibrated for 10 minutes. The relative percentage of the mass difference before and after vibration to the mass before vibration was recorded as the powder loss rate of the silica aerogel.
[0118] Thermal conductivity: The thermal conductivity of silica aerogel was tested according to the method of GB / T34336-2017.
[0119] Table 1
[0120]
[0121] As can be seen from Table 1, compared with the silica aerogel of Comparative Example 1 without hydrophobic modification, the silica aerogels of Examples 1 to 4 have a lower powder loss rate and a lower thermal conductivity, showing more excellent performance. At the same time, compared with the silica aerogels of Comparative Examples 2 to 3, the use of trichlorosilane derivatives as hydrophobic modifiers helps to obtain silica aerogels with better performance at low modifier content.
[0122] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0123] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims, and the description may be used to interpret the content of the claims.
Claims
1. A method for preparing a silica aerogel, characterized in that: The steps include: mixing a silicon source precursor, ethanol and water to form a silica sol; Aging and solvent replacement of the silica sol to form a silica wet gel; Using a modifier to hydrophobically modify the silicon dioxide wet gel to form a modified wet gel; Drying the modified wet gel; Wherein, the silicon source precursor is tetraalkoxysilane, and the modifier includes a trichlorosilane derivative whose substituent is an alkenyl group.
2. The method for preparing silica aerogel according to claim 1, characterized in that: The tetraalkoxysilane includes one or more of methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate and isopropyl orthosilicate.
3. The method for preparing the silica aerogel according to claim 1, characterized in that: The modifier includes one or more of vinyl trichlorosilane, 2-propylene trichlorosilane, 2-butenyl trichlorosilane, 5-hexenyl trichlorosilane and 7-octenyl trichlorosilane.
4. The method for preparing the silica aerogel according to any one of claims 1 to 3, characterized in that: The hydrophobic modification step comprises: placing the silicon dioxide wet gel into a first solution containing the modifier.
5. The method for preparing the silica aerogel according to claim 4, characterized in that: The hydrophobic modification satisfies one or more of the following conditions: (1) The temperature of the hydrophobic modification is 25°C to 70°C; (2) The hydrophobic modification time is 12h~72h; (3) The mass concentration of the modifier in the first solution is 5% to 40%.
6. The method for preparing the silica aerogel according to any one of claims 1 to 3, characterized in that: The step of mixing the silicon source precursor, ethanol and water comprises: Mixing the silicon source precursor, the ethanol and the water in a molar ratio of 1:(2-4):(9-16) to obtain a mixed solution; Adjusting the pH of the mixed solution to 2-6 to form a prepolymer solution; The pH of the prepolymer solution is adjusted to 7-10.
7. The method for preparing a silica aerogel according to any one of claims 1 to 3, characterized in that: The aging step comprises: placing the silica sol in an aging solution.
8. The method for preparing silica aerogel according to claim 7, characterized in that: The aging solution includes one or more of water, ethanol, n-hexane, acetone and the silicon source precursor.
9. A silica aerogel, characterized in that: The silica aerogel is prepared by the preparation method of any one of claims 1 to 8.
10. A composite aerogel material, characterized in that: The composite aerogel material comprises the silica aerogel according to claim 9.