Preparation and application method of amino hybrid SiO2 aerogel for purifying propylene in poly-3-hydroxybutyrate pyrolysis gas

Abstract

The application provides a preparation and application method of an amino hybrid SiO2 aerogel for purifying propylene in poly-3-hydroxybutyrate pyrolysis gas. In view of the problems that the existing amino adsorption material has poor selectivity in a complex biomass pyrolysis gas environment, the adsorption capacity is not optimized for specific components, and there is a lack of special technical scheme for carbon capture in the resourceization process of PHB waste, the amino hybrid SiO2 aerogel with a specific hierarchical porous structure is prepared by an in-situ polymerization method, and is specially used for treating specific component flue gas generated by high-temperature pyrolysis of PHB. The method fully utilizes the strong structural stability of the amino hybrid aerogel, the high selectivity of the amino active site, and the promotion effect of water vapor in the flue gas on the amino adsorption of CO2, and realizes high-capacity and high-selectivity capture of CO2 in the presence of propylene and other interfering gases. The application provides an efficient carbon capture solution for the resourceization treatment of biobased plastic waste.

Description

Technical Field

[0001] This invention discloses an amino-hybridized SiO2 aerogel for purifying propylene in the pyrolysis gas of poly(3-hydroxybutyrate), belonging to the field of waste gas treatment and carbon capture technology.

[0002] To address the shortcomings of existing amino adsorbent materials, such as insufficient selectivity in complex biomass pyrolysis gas environments, lack of optimized adsorption capacity for specific components, and absence of dedicated carbon capture technologies for PHB waste resource recovery, this invention prepares an amino-hybrid SiO2 aerogel with a specific hierarchical porous structure through in-situ polymerization. This aerogel is then specifically designed to treat specific components (CO2, C3H6, H2O) in the flue gas generated from the high-temperature pyrolysis of PHB. This method fully utilizes the strong structural stability of the amino-hybrid aerogel, the high selectivity of its amino active sites, the low polarity of the material surface, and the promoting effect of water vapor in the flue gas on the adsorption of CO2 by amino groups. This achieves high-capacity, highly selective capture of CO2 and adsorption of small amounts of water vapor even in the presence of interfering gases such as propylene. This invention provides an efficient solution for the resource recovery of bio-based plastic waste. Background Technology

[0003] Poly(3-hydroxybutyrate) (PHB), as an important class of biosynthetic biodegradable plastics, requires careful waste treatment and high-value recycling after large-scale application for resource utilization. Compared to traditional landfilling, composting, or energy recovery, converting waste PHB into high-value-added basic chemicals through thermochemical conversion is one of the most promising pathways to achieve material closed-loop and carbon resource recycling.

[0004] PHB pyrolysis efficiently generates a mixed gas with propylene as the main component. Propylene is a basic chemical raw material in huge demand; recovering propylene from waste PHB can significantly improve the economic efficiency of the resource utilization process and reduce dependence on fossil fuels. However, the crude propylene gas produced by PHB pyrolysis, in addition to the main component propylene, usually contains CO2 and a small amount of water vapor. The presence of these impurity gases severely restricts the subsequent utilization value of propylene. Therefore, developing a pretreatment technology that can simultaneously remove CO2 and a small amount of water vapor is key to the efficient recovery of propylene from PHB pyrolysis gas.

[0005] Therefore, for the specific application scenario of PHB resource utilization, it is necessary to develop a highly efficient and integrated gas purification material and technology that maintains high activity in the adsorption environment with water vapor, exhibits high adsorption capacity and high selectivity for CO2, and has a certain removal effect on water vapor, thereby achieving the purification of propylene. At the same time, the material needs to have good physicochemical stability to adapt to the process characteristics of pyrolysis gas, and have low regeneration energy consumption to match the economic requirements of the overall resource utilization process.

[0006] Existing commonly used solid adsorbent materials are mostly used to remove CO2 from flue gas. Their main components are CO2 and N2. When dealing with gas mixtures containing propylene, the following key issues exist:

[0007] First, common physical adsorbents (such as activated carbon and zeolite) have low separation factors for CO2 and propylene. Second, for chemisorption, existing amino-functionalized adsorbents, in pursuit of high CO2 adsorption capacity, often focus on developing supports with high microporosity. However, because propylene molecules are larger than N2 molecules, strong physical adsorption causes propylene molecules to remain and accumulate at the pore openings or channels, forming diffusion barriers and severely hindering subsequent CO2 molecules from reaching the internal amino active sites. Furthermore, unlike N2, propylene has high polarizability, making it easily induced to generate instantaneous dipole moments when near any porous material surface, resulting in strong induced interactions with the support surface. The strength of this interaction is far greater than that of physical adsorption generated by N2, so this is a serious problem that does not exist in flue gas environments. These materials have not been designed for stability and performance verification under the condition of "propylene presence." Finally, it is known that water vapor can promote the adsorption of CO2 by amino groups, but most existing systems treat water vapor as an interference that needs to be removed beforehand, failing to actively utilize the water vapor inherent in the pyrolysis gas to improve system efficiency and adsorption capacity.

[0008] Currently, technical literature on PHB treatment mainly focuses on how to pyrolyze it into high-value-added chemicals (such as propylene and aromatic hydrocarbons). However, CO2 and water vapor in the pyrolysis gas are byproducts that need to be avoided. Amino hybrid aerogels can effectively adsorb specific components such as CO2 and water vapor, which has a meaningful impact on the resource utilization of PHB. Summary of the Invention

[0009] In order to remove water and CO2 in PHB treatment, purify propylene in pyrolysis gas, and realize the recyclability of adsorption materials, this invention provides a method for preparing an amino-hybridized SiO2 aerogel for purifying propylene in poly(3-hydroxybutyrate) pyrolysis gas, which is prepared by hydrolysis and condensation of silicon source precursor and organic amine precursor.

[0010] The silicon source precursor is tetraethyl orthosilicate; the organic amine precursor is one of 3-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

[0011] Preferably, the preparation method includes the following steps:

[0012] Step 1: Dissolve the silicon source precursor and the organic amine precursor in an organic solvent and stir at room temperature to obtain a homogeneous and stable solution.

[0013] Step 2: While continuously stirring, add deionized water dropwise to the solution, controlling the dropping rate to avoid localized and violent hydrolysis-condensation reactions;

[0014] Step 3: After stirring the solution obtained in Step 2, let it stand at room temperature to obtain a uniform, jelly-like white gel.

[0015] Step 4: Add the aging agent to the jelly-like white gel for aging treatment, so that the unreacted hydroxyl groups can react further to increase the cross-linking degree of the network and make the gel skeleton more robust.

[0016] Step 5: Place the gel treated in Step 4 into the replacement solution and shake to replace it. Then wash it with the replacement solution to remove unreacted solution and other impurities to obtain a wet gel.

[0017] Step 6: Dry the wet gel to obtain the SiO2 aerogel.

[0018] Preferably, in step six, the drying process involves drying the product to a constant weight in a forced-air drying oven at 80°C under normal pressure.

[0019] Preferably, in step one, the organic solvent is anhydrous ethanol.

[0020] Preferably, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol and deionized water added in step one is 1:8:2; the molar ratio of tetraethyl orthosilicate and organic amine in step one is in the range of 1:1 to 1:5.

[0021] Preferably, in step three, the stirring time is 5 minutes.

[0022] Preferably, in step four, the aging agent is anhydrous ethanol, and the aging treatment time is 24 hours. Ethanol is produced by the condensation reaction of the silicon source precursor and the organic amine precursor; using anhydrous ethanol as the aging solution will not introduce new impurities.

[0023] Preferably, in step five, the replacement solution is n-hexane, and the washing is performed twice. n-Hexane has low surface tension, which can reduce capillary forces and prevent the collapse of numerous pores under normal pressure drying.

[0024] The present invention also provides an amino-hybridized SiO2 aerogel for purifying propylene in the pyrolysis gas of poly(3-hydroxybutyrate) prepared by the above preparation method, which is prepared by in-situ polymerization and hydrolysis condensation of silicon source precursor and organic amine precursor; the amino group provided by the organic amine is chemically bonded and embedded into the adsorption matrix and becomes part of the three-dimensional network framework of the adsorption matrix to improve the structural stability of the adsorption matrix.

[0025] This invention also provides the application of the amino-hybrid SiO2 aerogel for purifying propylene in poly(3-hydroxybutyrate) pyrolysis gas, comprising: utilizing water vapor in the poly(3-hydroxybutyrate) pyrolysis gas to promote the adsorption of CO2 by the amino groups, thereby achieving the adsorption of water vapor and CO2 in the pyrolysis gas, and thus purifying the propylene in the pyrolysis gas. In the presence of water vapor, the primary and secondary amine groups in the amino-hybrid aerogel undergo a weak reaction with the water vapor, capturing an H+ ion. + It transforms itself into -NH3 + The generated OH - Due to electrostatic attraction, ammonium ions will accumulate around the positively charged ammonium ions, thus forming a localized, OH-rich environment within the nanopores of the aerogel surface. - The alkaline microenvironment thus forms "NH3" + … OH - "Electrical double layer. When CO2 is absorbed, it first dissolves in the water film on the surface of the double layer to form carbonic acid, which then rapidly ionizes, producing H+." + and OH - Combined, HCO3 - With -NH3 + They combine to form stable products such as ammonium carbamate, thereby allowing CO2 to be absorbed by the amino hybrid aerogel through a chemical reaction.

[0026] The reaction formula is as follows:

[0027]

[0028] Therefore, amino hybrid aerogels not only increase CO2 absorption in the presence of water vapor, but also consume some water vapor through participation in chemical reactions, which has a positive effect on the purification of C3H6.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] This invention prepares amino-modified aerogels through in-situ polymerization. This method ensures that amino groups are uniformly distributed on the surface and inside of the material, effectively avoiding problems such as pore blockage caused by physical impregnation methods. The increased number of amino groups in contact with CO2 greatly improves the adsorption effect.

[0031] The present invention obtains an adsorbent material with good CO2 adsorption selectivity through amino modification. In the presence of water vapor, the amino functional groups can chemically react with CO2 molecules to form chemical bonds such as ammonium carbamate salt, which makes the amino-modified aerogel highly selective for carbon dioxide and can preferentially adsorb CO2 in mixed gases.

[0032] In this invention, amino groups are embedded and become part of the three-dimensional network framework of the aerogel through chemical bonds, resulting in a material with excellent structural stability. The thermal decomposition initiation temperature of the amino groups in the material is above 380°C, which ensures its thermal stability and long-term operational reliability at conventional CO2 adsorption and regeneration temperatures (<150°C).

[0033] The mesoporous structure of the amino-hybrid SiO2 aerogel of this invention exhibits excellent connectivity, providing diffusion-free, rapid channels for CO2 and propylene molecules. This ensures rapid adsorption kinetics, making it difficult for propylene molecules to form blocking adsorption within the channels, thus guaranteeing the accessibility and stability of the CO2 active sites during long-term operation. The amino-hybrid SiO2 aerogel designed in this invention incorporates two amino hybrid agents with relatively long alkyl chains. The presence of these alkyl chains significantly reduces the interaction with propylene molecules, transforming it into a uniform and weak dispersion force, creating a low-polarity surface chemical environment. This environment makes it difficult for propylene molecules to generate effective polarization induction, thereby weakening the strong physical adsorption force generated by propylene at its source. This allows the chemical reaction between CO2 and the amine groups to proceed in an undisturbed environment, achieving highly selective and stable adsorption in the presence of propylene.

[0034] The amino modification technology used in this invention is clean and environmentally friendly. Compared with commonly used in-situ polymerization and atmospheric pressure drying methods, it is simple to operate and has lower energy consumption. While improving CO2 adsorption performance, it reduces time and preparation costs. Attached Figure Description

[0035] Figure 1 The N2 desorption curves are shown for the aerogels prepared in Examples 1 and 2.

[0036] Figure 2 The pore size distribution diagrams are shown for the aerogels prepared in Examples 1 and 2.

[0037] Figure 3 The adsorption curves at 25°C are shown for the aerogels prepared in Examples 1 and 2.

[0038] Figure 4 Thermogravimetric curves of the aerogels prepared in Examples 1 and 2 are shown. Detailed Implementation

[0039] To gain a deeper understanding of this invention, we will provide a comprehensive and detailed description.

[0040] A method for preparing an amino-hybridized SiO2 aerogel for purifying propylene in the pyrolysis gas of poly(3-hydroxybutyrate) is provided, which is prepared by hydrolysis and condensation of silicon source precursor and organic amine precursor.

[0041] The silicon source precursor is tetraethyl orthosilicate; the organic amine is one of 3-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

[0042] The preparation method specifically includes the following steps:

[0043] Step 1: Dissolve the silicon source precursor and the organic amine precursor in a solvent and stir at room temperature to obtain a homogeneous and stable reaction starting system.

[0044] Step 2: Add deionized water dropwise while continuously stirring to avoid localized, violent hydrolysis and condensation reactions.

[0045] Step 3: After stirring the solution, let it stand at room temperature to obtain a uniform, jelly-like white gel in a undisturbed static environment;

[0046] Step 4: Add the aging agent to the gel for aging treatment. The unreacted hydroxyl groups react further to increase the cross-linking degree of the network and make the gel skeleton more robust.

[0047] Step 5: Place the above gel into the replacement solution and shake to replace it, then wash with the replacement solution to remove unreacted solution and other impurities;

[0048] Step 6: Dry the wet gel to obtain the CO2 adsorbent material.

[0049] In step six, the drying process involves drying the product to a constant weight in a forced-air drying oven at 80°C under normal pressure.

[0050] In step one, the silicon source precursor is tetraethyl orthosilicate, the organic amine precursor is one of 3-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and the solvent is anhydrous ethanol.

[0051] In the solvent, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol, and water is 1:8:2; the molar ratio of tetraethyl orthosilicate and organic amine in the solvent ranges from 1:1 to 1:5.

[0052] In step three, the stirring time is 5 minutes.

[0053] In step four, the aging solution used in the aging treatment is anhydrous ethanol, and the aging time is 24 hours. Ethanol is produced by the condensation reaction of silicon source precursor and organic amine precursor. Using anhydrous ethanol as the aging solution will not introduce new impurities.

[0054] In step five, the displacement washing process uses n-hexane as the displacement solution, and the displacement washing process is performed twice. n-Hexane has a low surface tension, which can reduce capillary forces and prevent the collapse of numerous pores under normal pressure drying.

[0055] The carbon dioxide adsorption material provided by the present invention is prepared by hydrolysis and condensation of a silicon source precursor and an organic amine precursor. The organic amine includes primary amino or secondary amino groups.

[0056] Example 1

[0057] A CO2 adsorbent material and its preparation method, comprising the following steps:

[0058] 13g of TEOS, 50.52g of AEAPTES, and 23g of anhydrous ethanol were mixed on a magnetic stirrer. Then, 2.25g of water was added, and stirring continued for 5 minutes. The mixture was allowed to stand at room temperature until the solution solidified and could not flow when the container was tilted at 45°, yielding a gel. The gel was then immersed in excess anhydrous ethanol for 24 hours for aging treatment. The gel was then vacuum filtered and washed with n-hexane, repeating the filtration process twice. After treatment, the gel was dried in a forced-air oven at 80°C to constant weight, yielding an amino-modified aerogel, denoted as AEAPTES-3.

[0059] CO2 adsorption experiments were conducted using a surface area and pore size analyzer. The sample was first degassed in a vacuum environment at 120℃ for 6 hours, then placed in the surface area and pore size analyzer, and CO2 gas was introduced. The CO2 pressure was changed at a constant temperature of 25℃ to obtain the CO2 adsorption curve.

[0060] Example 2

[0061] A CO2 adsorbent material and its preparation method, comprising the following steps:

[0062] 13g of TEOS, 41.44g of APTES, and 23g of anhydrous ethanol were mixed on a magnetic stirrer. Then, 2.25g of water was added, and stirring continued for 5 minutes. The mixture was allowed to stand at room temperature until the solution solidified and could not flow when the container was tilted at 45°, yielding a gel. The gel was then immersed in excess anhydrous ethanol for 24 hours for aging treatment. The gel was then vacuum filtered and washed with n-hexane, repeating the filtration process twice. After treatment, the gel was dried in a forced-air oven at 80°C to constant weight, yielding an amino-modified aerogel, denoted as APTES-3.

[0063] CO2 adsorption experiments were conducted using a surface area and pore size analyzer. The sample was first degassed in a vacuum environment at 120℃ for 6 hours, then placed in the surface area and pore size analyzer, and CO2 gas was introduced. The CO2 pressure was changed at a constant temperature of 25℃ to obtain the CO2 adsorption curve.

[0064] Specific surface area and pore size were analyzed for the amino-modified aerogels of Examples 1 and 2 to characterize the BET specific surface area, average pore size, and pore volume of different samples. Furthermore, the effects of different organic amines on the physical structure of the amino-modified aerogels were analyzed. The results are shown in Table 1. APTES-3 showed a 72 m² increase in specific surface area compared to AEAPTES-3. 2 / g, pore volume increased by 0.17cm 3 / g, the average pore size of AEAPTES-3 is 6.05 nm higher than that of APTES-3. This is because AEAPTES molecules are larger and have a dual-amino structure, which reduces the specific surface area and pore volume of the material, and the longer molecular chains lead to a larger pore structure. In contrast, the small molecular size and single amino group of APTES may result in a denser pore structure. The micropore area ratio of APTES-3 is 2.6%, while that of AEAPTES-3 is 6.8%, indicating that there are fewer micropores in the material.

[0065] Table 1 shows the BET specific surface area, average pore size, and pore volume of the amino-modified aerogels in Examples 1 and 2.

[0066]

[0067] CO2 adsorption experiments were conducted on the amino-modified aerogels of Examples 1 and 2 to analyze the CO2 adsorption capacity of different organic amines on the amino-modified aerogels. At 25°C, the CO2 adsorption capacity of APTES-3 was 2.61 mmol / g, while that of AEAPTES-4 was 2.91 mmol / g. This is because AEAPTES molecules contain a double amino group, while APTES contains only a single amino group. The double amino structure not only increases the density of amino groups per unit volume but also enhances the chemisorption capacity for CO2 through a synergistic effect. Furthermore, AEAPTES-modified aerogels typically exhibit a three-dimensional mesoporous network structure and high porosity, and their specific surface area and pore size distribution are more conducive to the diffusion and adsorption of carbon dioxide.

[0068] Figure 1 The N2 desorption curves of the adsorbent materials prepared in Examples 1 and 2 are shown in the figure. It can be seen from the figure that all isotherms rise slowly in the first half, but when the relative pressure increases to about 0.8, the adsorption curves rise sharply upwards. At this point, multilayer adsorption occurs on the adsorbent surface. According to the classification of the International Union of Pure and Applied Chemistry (IUPAC), this adsorption type is type IV. Capillary condensation occurs in the higher P / P0 region, and the adsorption-desorption isotherms do not coincide, thus producing a hysteresis loop. The adsorption-desorption isotherms of the amino-hybrid SiO2 aerogel indicate that the sample contains a large number of mesopores; therefore, the amino-hybrid SiO2 aerogel belongs to the mesoporous material category.

[0069] Figure 2The figures show the pore size distribution of the adsorbent materials prepared in Examples 1 and 2. From the figures, it can be seen that the pore sizes of the APTES hybrid SiO2 aerogel are concentrated between 10 nm and 20 nm, and the pore sizes of the AEAPTES hybrid SiO2 aerogel are concentrated between 30 nm and 40 nm, both falling within the mesoporous range. Because the molecular structure of AEAPTES is larger than that of APTES and has a longer carbon chain, it hinders the formation of a dense network structure during condensation, thus resulting in larger pore sizes.

[0070] Figure 3 The adsorption curves of the adsorbent materials prepared in Examples 1 and 2 at 25℃ are shown in the figure. It can be seen from the figure that both materials have high CO2 adsorption capacities, with APTES-3 reaching 2.61 mmol / g and AEAPTES-3 reaching 2.91 mmol / g. This is because AEAPTES contains both primary and secondary amines, while APTES only contains primary amines; therefore, the AEAPTES-hybridized aerogel has a higher CO2 adsorption capacity than APTES. The CO2 adsorption capacity of both adsorbent materials increases rapidly at lower partial pressures, indicating a chemical reaction between the amine and CO2. Subsequently, the adsorption capacity gradually increases with increasing CO2 partial pressure, demonstrating the physical adsorption properties of the materials.

[0071] Figure 4 The thermogravimetric curves of the adsorbent materials prepared in Examples 1 and 2 are shown in the figures. It can be seen that both materials exhibit two major weight losses at 100-200℃ and 380-600℃. The weight loss between 100-200℃ is related to the volatilization of water and residual organic solvent, while the weight loss between 380-600℃ is attributed to the oxidation of methyl and amine groups in the amino hybrid agent. AEAPTES-3 shows a greater weight loss ratio at 380-600℃ than APTES-3 because AEAPTES has a longer carbon chain and contains a higher proportion of methyl and amino groups than APTES-3, resulting in a greater weight loss rate.

[0072] In summary, this invention utilizes SiO2 aerogel with a large specific surface area as the adsorbent carrier, and the resulting adsorbent material loaded with 3-aminopropyltriethoxysilane or N-(β-aminoethyl)-γ-aminopropyltriethoxysilane exhibits a large specific surface area, average pore size, and pore volume, thus promoting CO2 adsorption capacity from a physical adsorption perspective. The distribution of amino groups and the basicity play a decisive role in adsorption performance; the amine groups in the amino-modified adsorbent material may provide a stronger basic environment, promoting the chemisorption of CO2.

[0073] Example 3

[0074] The application of amino-hybridized SiO2 prepared in Example 1 or 2 for the purification of propylene in 3-hydroxybutyrate pyrolysis gas includes the following steps:

[0075] Step 1: In a tube furnace, PHB particles are heated to 550°C at a rate of 10°C / min under nitrogen protection and held for 30 minutes. The pyrolysis gas is collected. Gas chromatography analysis shows that its typical composition is: 65 vol% CO2, 25 vol% C3H6, and 10 vol% water vapor.

[0076] Step 2: Load 2.0g of the prepared aerogel into a fixed-bed adsorption column. Simulated pyrolysis gas is introduced into the adsorption column at 80°C and a flow rate of 50mL / min. Breakthrough is considered complete when the outlet concentration reaches 10% of the inlet concentration. The adsorption column is then regenerated by purging with N2 at 120°C for 2 hours.

[0077] Step 3: In contrast, when using the same aerogel to adsorb a dry CO2 / N2 (15 / 85 vol%) mixture under the same conditions, its adsorption capacity decreased, and its cycle stability also decreased slightly. This fully demonstrates the promoting effect of water vapor in the PHB pyrolysis gas and the excellent adaptability of this material to this specific gas system.

[0078] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An application of an amino-hybridized SiO2 aerogel for purifying propylene in the pyrolysis gas of poly(3-hydroxybutyrate) ester, characterized in that, The method for purifying propylene from poly(3-hydroxybutyrate) pyrolysis gas includes: utilizing water in the poly(3-hydroxybutyrate) pyrolysis gas to promote the adsorption of CO2 by amino groups, thereby adsorbing water and CO2 in the pyrolysis gas and purifying propylene in the pyrolysis gas; and regenerating the amino-hybridized SiO2 aerogel that has completed adsorption at a regeneration temperature not exceeding 150°C for recycling. The amino-hybridized SiO2 aerogel was prepared by hydrolysis and condensation of silicon source precursor and organic amine precursor; The silicon source precursor is tetraethyl orthosilicate; the organic amine precursor is one of 3-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane. The preparation method of the amino-hybridized SiO2 aerogel includes the following steps: Step 1: Dissolve the silicon source precursor and the organic amine precursor in an organic solvent and stir at room temperature to obtain a homogeneous and stable solution. Step 2: While continuously stirring, add deionized water dropwise to the solution, controlling the dropping rate to avoid localized and violent hydrolysis-condensation reactions; Step 3: After stirring the solution obtained in Step 2, let it stand at room temperature to obtain a uniform, jelly-like white gel. Step 4: Add the aging agent to the jelly-like white gel for aging treatment, so that the unreacted hydroxyl groups can react further to increase the cross-linking degree of the network and make the gel skeleton more robust. Step 5: Place the gel treated in Step 4 into the replacement solution and shake to replace it. Then wash it with the replacement solution to remove unreacted solution and other impurities to obtain a wet gel. Step 6: Dry the wet gel to obtain the SiO2 aerogel.

2. The application as described in claim 1, characterized in that, In step six, the drying process involves drying the product to a constant weight in a forced-air drying oven at 80°C under normal pressure.

3. The application as described in claim 1, characterized in that, In step one, the organic solvent is anhydrous ethanol.

4. The application as described in claim 1, characterized in that, The molar ratio of tetraethyl orthosilicate, anhydrous ethanol, and deionized water added in step 2 is 1:8:2; the molar ratio of tetraethyl orthosilicate and organic amine in step 1 is in the range of 1:1 to 1:

5.

5. The application as described in claim 4, characterized in that, In step three, the stirring time is 5 minutes.

6. The application as described in claim 4, characterized in that, In step four, the aging agent is anhydrous ethanol, and the aging treatment time is 24 hours.

7. The application as described in claim 6, characterized in that, In step five, the replacement solution is n-hexane, and the washing is performed twice.

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