A high-resilience, low-thermal-conductivity silica aerogel, preparation method and application

Abstract

This invention relates to the technical field of inorganic nanoporous material preparation, and discloses a high-resilience, low-thermal-conductivity silica aerogel, its preparation method, and its application. The aerogel is prepared by gradient loading of PEDS and nano-silica particles, followed by multi-stage hydrolysis to create a microporous (81%) to mesoporous (19%) gradient structure. This is then combined with microwave drying to achieve atmospheric pressure preparation. The resulting silica aerogel has a specific surface area of ​​716.8 m² / g, a density of 0.073 g / cm³, a hydrophobic angle of 150.1°, a thermal conductivity of 0.017 W / (m·K), and a porosity of 97.8%. It exhibits excellent resilience at a strain of 80%, and can be used as a building insulation material and an adsorbent for cyclic adsorption in oil-water separation.

Description

Technical Field

[0001] The present invention relates to a high-resilience, low-thermal-conductivity silica aerogel, a preparation method, and an application thereof. The invention belongs to the technical field of inorganic nanoporous material preparation, and specifically relates to a high-resilience, low-thermal-conductivity silica aerogel, including its preparation method and application. The aerogel can be used in industrial scenarios such as high-efficiency thermal insulation materials, oil-water separation, and adsorbents. Background Art

[0002] 1. Industrial bottleneck of aerogel materials

[0003] As a typical representative of nanoporous materials, silica aerogel is widely recognized as a key candidate for the next generation of high-performance thermal insulation materials due to its ultra-low density (0.003-0.5 g / cm³), extremely low thermal conductivity (0.005-0.1 W / (m·K)), and high specific surface area (200-1000 m² / g). However, existing technologies have three core drawbacks:

[0004] The preparation process is demanding: it relies on supercritical drying technology (which requires a high-pressure reactor, high temperature and high pressure conditions), resulting in high equipment costs and huge energy consumption.

[0005] Insufficient structural regulation capability: The existing sol-gel method is difficult to achieve precise grading of pore structure, resulting in difficulty in synergistic optimization of thermal conductivity and mechanical strength.

[0006] Single function: Existing products focus more on thermal insulation performance and lack the integration of adsorption and thermal insulation dual functions, which limits their application in complex environments (such as oil pollution treatment scenarios).

[0007] 2. Technological Improvement Attempts and Limitations

[0008] In recent years, researchers have reduced preparation costs by introducing co-precursors (such as silane coupling agents) or optimizing drying processes (such as atmospheric pressure drying). For example:

[0009] Co-precursor method: A mixed system of TMOS (tetramethoxysilane) and organosilane is used. Although this can improve the flexibility of the material, it leads to homogenization of the pore structure and a rebound in the thermal conductivity to above 0.03 W / m·K.

[0010] Atmospheric pressure drying modification: Shrinkage cracking is suppressed by surface hydrophobic treatment, but the porosity is sacrificed (the porosity drops below 80%), and the balance between adsorption performance and mechanical properties is not solved.

[0011] Establishment of multi-level pores: CN114180582A discloses a multi-level porous silica aerogel material and its preparation method. By introducing a trifunctional silicon source molecule containing a non-polar group that does not participate in hydrolysis and condensation and three alkoxy groups that can participate in hydrolysis and condensation reactions, the material has a multi-level porous structure composed of nano- and micron-pores. However, only its high hydrophobicity, high specific surface area, and high pore volume were studied, and thermal conductivity and resilience were not involved, which limits its application areas.

[0012] 3. Problems with existing technologies

[0013] The conflict between thermal conductivity control and mechanical properties. Traditional aerogels reduce thermal conductivity through high porosity, but excessive porosity significantly increases the material's brittleness. Traditional silica aerogels (92% porosity) undergo permanent deformation at just 10% compressive strain, limiting their use in load-bearing applications like building mezzanines.

[0014] The synergy of adsorption and thermal insulation functions is missing. Existing adsorption aerogels (such as carbon-based composite materials) achieve oil-water separation through surface modification, but their dense surface structure leads to increased thermal conductivity, which cannot meet the needs of high-temperature thermal insulation scenarios.

[0015] The scale-up barrier of the preparation process is that the investment cost of supercritical drying equipment is as high as 5-8 times that of conventional drying equipment, and the reaction cycle is long, resulting in high product costs, which seriously restricts industrial promotion. Summary of the Invention

[0016] In view of the above problems, the present invention provides a method for preparing high-resilience and low-thermal-conductivity silica aerogel, which is achieved by the following steps:

[0017] The composite silicon source precursor solution was constructed using PEDS as the long-chain silicon source, nano-silica particles as the short-chain silicon source, and boric acid as the activator. A multi-stage cross-linked network was formed through gradient hydrolysis. Sodium dodecylbenzenesulfonate was introduced as a surfactant, and the reaction was carried out at 60-70°C under nitrogen to inhibit phase separation and form a uniform Si-O-Si bond network.

[0018] Gradient loading of nano-silica particles: Use acetic acid solution to adjust the pH to 4.2-4.8 to control the step-by-step deposition of nano-silica particles, forming cross-linked clusters with PEDS segments through Si-O-Si bonds to enhance mechanical properties.

[0019] Multi-stage hydrolysis and spatial confinement: The first stage (40°C): deionized water triggers the initial hydrolysis of PEDS to form a primary sol; the second stage (60°C): VMDMS and VTMS act as co-silicon sources to induce secondary polycondensation to form a mesoporous structure; the third stage (30°C): sodium acetate is used to adjust the pH to 5.5-6.0 to promote the formation of micropores, and finally a gradient pore structure in which micropores (<2 nm) and mesopores (2-50 nm) coexist is constructed.

[0020] Hydrophobic modification pretreatment: Inject octadecyltrichlorosilane / isopropyl alcohol mixture under ultrasonic assistance to graft hydrophobic groups with a contact angle of ≥150°, laying the foundation for oil-water separation.

[0021] Microwave-assisted atmospheric pressure drying: 2.45 GHz microwave drying (power 200 W, time 4 hours) was used instead of supercritical drying to reduce energy consumption and avoid structural collapse.

[0022] The method for preparing a high-resilience and low-thermal-conductivity silica aerogel according to the present invention specifically comprises the following steps:

[0023] S1. Preparation of composite silicon source precursor liquid: Dissolve polysiloxane (PEDS) in anhydrous ethanol, add boric acid and sodium dodecylbenzene sulfonate, and stir at 30-40°C under nitrogen for 4 hours to form a preliminary activated silicon-oxygen bond network;

[0024] S2. Gradient loading of nanosilica particles: Add the nanosilica particle suspension dropwise to the system of S1 at a dropping rate of 0.5-1 mL / min. At the same time, adjust the pH to 4.2-4.8 with 0.5-1 mol / L acetic acid solution and stir the reaction for 2.5 hours to form cross-linked clusters between the nanosilica particles and the PEDS segments through Si-O-Si bonds.

[0025] S3, multi-stage hydrolysis: Introduce triethanolamine at a concentration of 0.5-1.5 wt.% into the system of S2, and regulate the hydrolysis in three stages: First stage: Add deionized water in an amount accounting for 50-75 wt.% of PEDS, stir at 40°C for 1 hour to form a primary sol; Second stage: Raise the temperature to 60°C, add dimethyldimethoxysilane (VMDMS) and vinyltrimethoxysilane (VTMS) in a volume ratio of 1:1.5, and add an amount accounting for 10-15 wt.% of PEDS, stir for 2 hours to induce secondary polycondensation; Third stage: Pass argon and cool to 30°C, add sodium acetate at a concentration of 10-20 wt.% to adjust the pH to 5.5-6.0, stir for 4 hours to complete the three-dimensional network crosslinking;

[0026] S4, hydrophobic modification pretreatment: injecting a mixed solution of 0.1-0.3 wt.% octadecyltrichlorosilane and isopropyl alcohol in a volume ratio of 1:5 into the system of S3, and treating the mixture under ultrasonic assisted treatment at a frequency of 40 kHz and a power of 200 W for 30 minutes to obtain a pre-modified precursor liquid;

[0027] S5, gelation and microwave-assisted drying: add 5-10% wt.% ammonia water to the pre-modified precursor liquid of S4 to a pH of 10, let it stand for gelation for 24 hours, then add dropwise a 20-40 wt.% sodium silicate solution, and continue aging for 4 hours; the wet gel is replaced with ethanol and acetone three times, each time for 12 hours, and finally immersed in n-hexane solution and microwave-assisted drying is performed at a frequency of 2.45 GHz, a power of 200 W, and a time of 4 hours to obtain the silica aerogel.

[0028] As a further improvement of the present invention, in step S1, the mass ratio of PEDS to anhydrous ethanol is 1:2-3, the mass ratio of PEDS to boric acid is 1:0.2-0.5, and the mass ratio of PEDS to sodium dodecylbenzenesulfonate is 1:0.02-0.05.

[0029] As a further improvement of the present invention, the concentration of boric acid is 0.1-0.12 mol / L, and the concentration of sodium dodecylbenzenesulfonate is 0.01-0.03 wt.%.

[0030] As a further improvement of the present invention, in step S2, the mass ratio of PEDS to the nano-silica particle suspension is 1:0.08-0.12, the particle size of the nano-silica particle suspension is 10-30 nm, the specific surface area is ≥200 m² / g, and the solid content is 30-40%.

[0031] As a further improvement of the present invention, in step S3, the amount of triethanolamine added is 0.8-1.2 wt.% of the mass of PEDS.

[0032] As a further improvement of the present invention, in step S5, the amount of sodium silicate added is 10-15 wt.% of the mass of PEDS, and the addition rate is 0.05-0.1 g / min.

[0033] As a further improvement of the present invention, the high-resilience and low-thermal-conductivity silica aerogel is characterized in that its density is 0.06-0.08 g / cm³, its thermal conductivity is ≤0.017W / W / (m·K), and its compression rebound rate is ≥80%.

[0034] As a further improvement of the present invention, the high-resilience and low-thermal-conductivity silica aerogel is characterized in that its specific surface area is 600-900 m² / g and its porosity is ≥95%.

[0035] As a further improvement of the present invention, the high-resilience and low-thermal-conductivity silica aerogel is characterized in that the water contact angle is ≥150° and is suitable for oil-water separation.

[0036] As a further improvement of the present invention, the high-resilience and low-thermal-conductivity silica aerogel is characterized in that the aerogel is used for building insulation, pipeline insulation or marine oil spill adsorption, wherein the oil-water separation can be cyclically adsorbed.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] Synergistic optimization of performance: low thermal conductivity and high rebound: The gradient pore structure (micropores account for 75%-85%) reduces the thermal conductivity to 0.016-0.018 W / (m·K), and the cross-linked network of PEDS long chains and nano-silica clusters gives a compression rebound rate of ≥80%;

[0039] Hydrophobic-adsorption synergistic optimization: After hydrophobic modification, the surface contact angle is ≥150°, and oil-water separation can be cyclically adsorbed.

[0040] Process innovation: Microwave drying replaces supercritical fluid, reducing equipment costs and shortening production cycles.

[0041] Green atmospheric pressure process: Solvent replacement only requires three stages of replacement with ethanol, acetone, and n-hexane, with no toxic solvent residue.

[0042] Functional integration breakthrough: thermal insulation-adsorption integration: Through graded pores and surface hydrophobic modification, the material can be cross-applied in high-temperature thermal insulation and oil adsorption scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart for preparing a high-resilience and low-thermal-conductivity silica aerogel according to the present invention;

[0044] Figure 2 This is a physical picture of the silica aerogel prepared in Example 1;

[0045] Figure 3 Scanning electron micrographs of the silica aerogels prepared in Example 1 (a, a1) and Comparative Example 1 (b, b1).

[0046] Figure 4 TEM image of nano-silica particles;

[0047] Figure 5Schematic diagram of water contact angle of silica aerogel prepared in Example 1 and Comparative Examples 1 to 3

[0048] Figure 6 The apparent density and thermal conductivity test graph of the silica aerogel prepared in Example 1 and Comparative Examples 1 to 3;

[0049] Figure 7 The porosity test graph of silica aerogel prepared in Example 1 and Comparative Examples 1 to 3

[0050] Figure 8 Thermal analysis test diagram of silica aerogel prepared in Example 1 and Comparative Examples 1 to 3;

[0051] Figure 9 Infrared thermal imaging test images of silica aerogels prepared in Example 1 and Comparative Examples 1 to 3;

[0052] Figure 10 Nitrogen adsorption and desorption curves (a) of the silica aerogel prepared in Example 1 and the pore size distribution curves (b) of the silica aerogel prepared in Example 1 and Comparative Example 1;

[0053] Figure 11 Figure 1 is a graph showing the pore size ratios of the silica aerogels prepared in Example 1 and Comparative Example 1;

[0054] Figure 12 Compression rebound test diagram of the silica aerogel prepared in Example 1 at 80% strain;

[0055] Figure 13 Infrared spectrum of the silica aerogel prepared in Example 1;

[0056] Figure 14 This is the test of the prepared silica aerogel in oil-water separation. (a) to (c) are adsorption operation diagrams, (d) to (h) are adsorption test diagrams for toluene, n-hexane, DMF, n-heptane, and pump oil, respectively, and (i) is the ten-cycle adsorption diagram of Example 1.

[0057] The present invention will be further described below with reference to the embodiments. DETAILED DESCRIPTION

[0058] The present invention provides a preparation method and application of high-resilience and low-thermal-conductivity silica aerogel. In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in conjunction with specific embodiments and drawings.

[0059] Example 1

[0060] like Figure 1As shown, the preparation method of the high-resilience and low-thermal-conductivity silica aerogel of the present invention is prepared by the following steps:

[0061] Step 1: Dissolve 7.8 g of PEDS in 20 g of anhydrous ethanol, add 3 g of boric acid (concentration: 0.1 mol / L) and 0.15 g of sodium dodecylbenzenesulfonate (concentration: 0.02 wt.%), and stir at 35°C under nitrogen for 4 hours.

[0062] Step 2: Add 2 g of nano-silica particle suspension (particle size 15 nm, specific surface area 200 m² / g, solid content 40%) dropwise to the precursor solution obtained in step 1 at a dropwise addition rate of 0.5 mL / min. At the same time, adjust the pH to 4.8 with (0.5-1 mol / L) acetic acid solution and stir the reaction for 2.5 hours.

[0063] Step 3: Add 0.8 g of triethanolamine (0.7 wt.%) to the reaction mixture in Step 2. Hydrolysis was controlled in three stages: First, add 5 g of deionized water and stir at 40°C for 1 hour. Second, raise the temperature to 60°C, add 0.4 g of VMDMS and 0.6 g of VTMS, and stir for 2 hours. Third, introduce argon and cool to 30°C. Add sodium acetate (10-20 wt.%) to adjust the pH to 5.5 and stir for 4 hours.

[0064] Step 4: Add 3 g of a mixed solution of octadecyltrichlorosilane (concentration 0.2 wt.%) and isopropyl alcohol (volume ratio 1:5) to the mixture in step 3, and treat the mixture under ultrasonication (frequency 40 kHz, power 200 W) for 30 minutes to obtain a pre-modified precursor solution;

[0065] Step 5: Add ammonia water (concentration of 10 wt.%) to the pre-modified precursor liquid of step 4 to adjust the pH to 10, let it stand for gelation for 24 hours, then add 0.8 g of sodium silicate dropwise at an addition rate of 0.08 g / min and continue aging for 4 hours; the wet gel is replaced with ethanol and acetone three times (each time for 12 hours), and finally immersed in n-hexane solution and dried with microwave assisted drying (frequency 2.45 GHz, power 200 W, time 4 hours) to obtain the silica aerogel.

[0066] Comparative Example 1

[0067] Step 1: Dissolve 7.8 g of PEDS in 20 g of anhydrous ethanol, add 3 g of boric acid (concentration: 0.1 mol / L) and 0.15 g of sodium dodecylbenzenesulfonate (concentration: 0.02 wt.%), and stir at 35°C under nitrogen for 4 hours.

[0068] Step 2: Add 3 g of a mixed solution of octadecyltrichlorosilane (0.2 wt.%) and isopropyl alcohol (volume ratio 1:5) to the mixture in step 1 and treat the mixture under ultrasonication (frequency 40 kHz, power 200 W) for 30 minutes to obtain a pre-modified precursor solution;

[0069] Step 3: Add ammonia water (concentration of 10 wt.%) to the pre-modified precursor liquid of step 2 to adjust the pH to 10, let it stand for gelation for 24 hours, then add 0.8 g of sodium silicate dropwise at an addition rate of 0.08 / min and continue aging for 4 hours; the wet gel is replaced with ethanol and acetone three times (each time for 12 hours), and finally immersed in n-hexane solution and dried with microwave assisted drying (frequency 2.45 GHz, power 200 W, time 4 hours) to obtain the silica aerogel.

[0070] Comparative Example 2

[0071] Comparative Example 2 provides a method for preparing high-resilience, low-thermal-conductivity silica aerogel. Compared to Example 1, this method differs in that, in step 2, 1 g of a nanosilica particle suspension (particle size 15 nm, specific surface area 200 m² / g, solids content 40%) is added at a dropwise rate of 0.5 mL / min. Simultaneously, the pH is adjusted to 4.8 with a 0.5 mol / L acetic acid solution, and the reaction is stirred for 2.5 hours. The remaining steps are the same as in Example 1 and are not further described here.

[0072] Comparative Example 3

[0073] Comparative Example 3 provides a method for preparing high-resilience, low-thermal-conductivity silica aerogel. Compared to Example 1, this method differs in that, in step 2, 3 g of a nanosilica particle suspension (particle size 15 nm, specific surface area 200 m² / g, solids content 40%) is added at a dropwise rate of 0.5 mL / min. Simultaneously, the pH is adjusted to 4.8 with a 0.5 mol / L acetic acid solution, and the reaction is stirred for 2.5 hours. The remaining steps are the same as in Example 1 and are not further described here.

[0074] Figure 2 This is a physical picture of the silica aerogel prepared in Example 1 of the present invention.

[0075] Figure 3 Scanning electron microscopy images of silica aerogels prepared in Example 1 and Comparative Example 1. Figures (a) and (a1) show the silica aerogel prepared in Example 1, with an average particle size of approximately 100 nm. Figures (b) and (b1) show the silica aerogel prepared in Comparative Example 1 without the addition of the nano-silica particle suspension. The aerogels exhibit a "pearl string" shape with an average particle size of 2 to 2.5 μm.

[0076] Figure 4This is a TEM image of nano-silica particles, with particle size distribution between 10-30nm.

[0077] Figure 5 The hydrophobic angle test diagram of the silica aerogels prepared in Example 1 of the present invention and Comparative Examples 1 to 3 shows that the hydrophobic angles are all above 150°.

[0078] Figure 6 The apparent density and thermal conductivity test diagrams of the silica aerogels prepared in Example 1 of the present invention and Comparative Examples 1 to 3 show that the apparent density is below 0.08 g / cm³, the thermal conductivity is below 0.024 W / (m·K), and the lowest can reach 0.017 W / (m·K).

[0079] Figure 7 This is a porosity test chart of the silica aerogels prepared in Example 1 and Comparative Examples 1 to 3. The porosity of the prepared silica aerogels is all above 95%.

[0080] Figure 8 The thermal analysis test charts of the silica aerogels prepared in Example 1 and Comparative Examples 1 to 3 show that the addition of nano-silica particles can improve the thermal stability of the silica aerogels compared with the silica aerogels without nano-silica particles.

[0081] Figure 9 These are infrared thermal imaging test images of the silica aerogels prepared in Example 1 and Comparative Examples 1 to 3. The heating stage temperature is 150° C. It can be concluded that the addition of nano-silica particles can effectively improve the thermal insulation performance of the silica aerogel.

[0082] Figure 10 Automated surface area and pore size distribution tests of silica aerogels prepared in Example 1 and Comparative Examples 1-3 are shown. Figure (a) shows a nitrogen adsorption / desorption curve indicating that the silica aerogel prepared in Example 1 has a specific surface area of ​​716.8 m² / g. Figure (b) shows a pore size distribution curve demonstrating that the addition of nano-silica particles increases the micropore content of the silica aerogels.

[0083] Figure 11 The pore size ratios of the silica aerogels prepared in Example 1 and Comparative Examples 1 to 3 are shown in FIG. The addition of nano-silica particles can make the silica aerogels have 81% micropores (0-2 nm) and 19% mesopores (2-50 nm).

[0084] Figure 12 This is a compression rebound test diagram of the silica aerogel prepared in Example 1 under 80% strain. The silica aerogel prepared in Example 1 still has rebound performance under 80% strain.

[0085] Figure 13 This is the infrared spectrum of the silica aerogel prepared in Example 1, in which the characteristic peak of silica aerogel Si-O-Si appears.

[0086] Figure 14 Figure 1 shows the silica aerogel prepared in Example 1 tested for oil-water separation. Figures (a)-(c) show actual adsorption tests, (d)-(h) show adsorption tests for toluene, n-hexane, DMF, n-heptane, and pump oil, respectively. Figure (i) shows the adsorption of Example 1 after ten cycles. It can be seen that Example 1 has a higher adsorption capacity for all of the above substances than the other comparative examples, and there is no significant decrease in adsorption capacity after ten cycles.

Claims

1. A method for preparing high-resilience and low-thermal-conductivity silica aerogel, characterized in that: The following steps are involved: S1. Preparation of composite silicon source precursor liquid: Dissolve polysiloxane (PEDS) in anhydrous ethanol, add boric acid and sodium dodecylbenzene sulfonate, and stir at 30-40°C under nitrogen for 4 hours to form a preliminary activated silicon-oxygen bond network; S2. Gradient loading of nanosilica particles: Add the nanosilica particle suspension dropwise to the system of S1 at a dropping rate of 0.5-1 mL / min. At the same time, adjust the pH to 4.2-4.8 with 0.5-1 mol / L acetic acid solution and stir the reaction for 2.5 hours to form cross-linked clusters between the nanosilica particles and the PEDS segments through Si-O-Si bonds. S3, multi-stage hydrolysis: Introduce triethanolamine at a concentration of 0.5-1.5 wt.% into the system of S2, and regulate the hydrolysis in three stages: First stage: add deionized water in an amount accounting for 50-75 wt.% of PEDS, and stir at 40°C for 1 hour to form a primary sol; Second stage: raise the temperature to 60°C, add dimethyldimethoxysilane and vinyltrimethoxysilane in a volume ratio of 1:1.5, and the amount added accounts for 10-15 wt.% of PEDS, and stir for 2 hours to induce secondary polycondensation; Third stage: introduce argon and cool to 30°C, add sodium acetate at a concentration of 10-20 wt.% to adjust the pH to 5.5-6.0, and stir for 4 hours to complete the three-dimensional network crosslinking; S4, hydrophobic modification pretreatment: injecting a mixed solution of 0.1-0.3 wt.% octadecyltrichlorosilane and isopropyl alcohol in a volume ratio of 1:5 into the system of S3, and treating the mixture under ultrasonic assisted treatment at a frequency of 40 kHz and a power of 200 W for 30 minutes to obtain a pre-modified precursor liquid; S5, gel and microwave-assisted drying: add 5-10% wt.% ammonia water to the pre-modified precursor liquid of S4 to pH 10, let it stand for gelation for 24 hours, then add 20-40 wt.% sodium silicate solution dropwise, and continue aging for 4 hours; the wet gel is replaced with ethanol and acetone three times, each time for 12 hours, and finally immersed in n-hexane solution and microwave-assisted drying is used at a frequency of 2.45 GHz, a power of 200 W, and a time of 4 hours to obtain the silica aerogel.

2. The method according to claim 1, characterized in that In step S1, the mass ratio of PEDS to anhydrous ethanol is 1:2-3, the mass ratio of PEDS to boric acid is 1:0.2-0.5, and the mass ratio of PEDS to sodium dodecylbenzenesulfonate is 1:0.02-0.

05.

3. The method according to claim 2, characterized in that The concentration of boric acid is 0.1-0.12 mol / L, and the concentration of sodium dodecylbenzenesulfonate is 0.01-0.03 wt.%.

4. The method according to claim 1, wherein In step S2, the mass ratio of PEDS to the nano-silica particle suspension is 1:0.1-0.5, the particle size of the nano-silica particle suspension is 10-30 nm, and the specific surface area is ≥200 m 2 / g, solid content is 30-40%.

5. The method according to claim 1, wherein The amount of triethanolamine added in step S3 is 0.8-1.2 wt.% of the mass of PEDS.

6. The method according to claim 1, wherein The amount of sodium silicate added in step S5 is 10-15 wt.% of the mass of PEDS, and the addition rate is 0.05-0.1 g / min.

7. A high-resilience, low-thermal-conductivity silica aerogel prepared according to the method of any one of claims 1 to 6, characterized in that: Its density is 0.06-0.08g / cm 3 , thermal conductivity ≤ 0.017W / (m·K), compression rebound rate ≥ 80%.

8. The aerogel according to claim 7, characterized in that Its specific surface area is 600-900m 2 / g, porosity ≥95%.

9. The aerogel according to claim 7, characterized in that Water contact angle ≥150°, suitable for oil-water separation.

10. Use of the aerogel according to any one of claims 7 to 9, characterized in that: The aerogel is used for building thermal insulation, pipeline thermal insulation or marine oil spill absorption.

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