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Method for preparing silicon dioxide aerogel by using acidic silica sol

A technology of acidic silica sol and silicon dioxide, which is applied in the production of silicon dioxide, silicon oxide, bulk chemicals, etc., can solve problems such as increasing airtightness, explosion-proof anti-static, increasing risk, cumbersome process, etc., to achieve effective Conducive to the control of wet gel structure, improving work efficiency and simple process

Active Publication Date: 2012-08-22
纳诺科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method prepares alcohol gel by adding ethanol to silica sol, but after gelation, it is still necessary to soak the obtained gel with ethanol solutions of different concentrations. For industrial production, the process is cumbersome, and organic Solvents increase the airtightness, explosion-proof and anti-static requirements of the equipment, which not only increases the cost but also increases the danger of production

Method used

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  • Method for preparing silicon dioxide aerogel by using acidic silica sol

Examples

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Embodiment 1

[0034] Take 100ml of acidic silica sol with a silica content of 30% (wt) and put it in a 1000ml beaker, measure 300ml of water and add it to the beaker to dilute the acidic silica sol. into the prepared silica sol aqueous solution, and stir while adding dropwise until the pH value of the silica sol aqueous solution reaches 11.0, and then with 2mol / L H 2 SO 4 Solution titration of silica sol aqueous solution, stirring while adding dropwise, until the pH value reaches 7.0, put the dropwise added solution in a 70°C water bath, after 3.5h, the solution forms a hydrogel, continue to age in a 60°C water bath atmosphere for 2h, put The gel was taken out and replaced in 95% (wt) ethanol. The volume ratio of ethanol to hydrogel was 5:1, the replacement temperature was 60°C, and the replacement time was 3 hours. A total of 3 replacements were performed to obtain the alcohol gel. Supercritical drying of carbon dioxide to obtain hydrophilic SiO 2 airgel.

Embodiment 2

[0036] Take 100ml of acidic silica sol with a silica content of 30% (wt) in a 1000ml beaker, measure 200ml of water and add it to the beaker to dilute the acidic silica sol. Slowly drop the sodium solution into the prepared silica sol aqueous solution, and stir while adding, until the pH value of the silica sol aqueous solution reaches 10.8, then titrate the silica sol aqueous solution with 2mol / L HCl solution, and stir while dropping, until the pH value When it reaches 7.05, put the dropwise solution in a 60°C water bath. After 1min, the solution forms a hydrogel, and continues to age in a 60°C water bath for 2 hours. Take out the gel and replace it with 95% (wt) ethanol. The volume ratio to the hydrogel is 5:1, the replacement temperature is 60°C, the replacement time is 3h, and the replacement is 2 times. The gel is taken out and placed in a trimethylchlorosilane solution for surface methylation treatment, soaked at 60°C for 3h , by supercritical drying of ethanol to obtain...

Embodiment 3

[0038] Take 50ml of acidic silica sol with a silica content of 30% (wt) in a 1000ml beaker, measure 200ml of water and add it to the beaker to dilute the acidic silica sol. The sodium solution was slowly dropped into the prepared aqueous silica sol solution, and stirred while adding dropwise until the pH value of the aqueous silica sol solution reached 9.7, and then added with 3mol / L H 2 SO 4 Solution titration of silica sol aqueous solution, stirring while adding dropwise, until the pH value reaches 6.15, put the dropwise added solution in a 60°C water bath, after 12 minutes, the solution forms a hydrogel, continue to age in a 60°C water bath atmosphere for 2.5h, put The gel was taken out and replaced in 95% (wt) ethanol. The volume ratio of ethanol to hydrogel was 5:1, the replacement temperature was 60°C, and the replacement time was 3 hours. Methyl chlorosilane solution was subjected to surface methylation treatment, soaked at 60°C for 3h, and then dried under normal pres...

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Abstract

The invention discloses a method for preparing silicon dioxide aerogel by using acidic silica sol and belongs to the field of preparation of inorganic heat-insulating materials. The method comprises the following steps of: directly forming gel under actions of acid and alkali catalysts by using acidic silica sol as a raw material, wherein the process for preparing the gel does not involve organic solvent so as to improve the security of production; and preparing SiO2 aerogel through supercritical or constant pressure drying after the gel is subjected to solvent replacement and surface silylation. According to the method, the process for preparing the sol by using organic silicon as raw material and a complicated process for removing salt in water glass are avoided; and because the acidic silica sol with low cost and stable performance is used as the raw material, the method has the advantages that the process is simple, the production cycle is short, the reaction process is controlled, and the requirement and investment of the equipment are low, so that the industrial production of SiO2 aerogel can be realized.

Description

Technical field: [0001] The invention belongs to the field of preparation of inorganic thermal insulation materials, and in particular relates to a method for preparing nanoporous silica airgel by using acidic silica sol as a raw material. Background technique: [0002] Silicon dioxide (SiO 2 ) Airgel is a lightweight porous material, NASA scientists developed a density of only 3kg / m 3 Airgel, as the world's lightest solid, has been selected into the Guinness Book of World Records. Its unique three-dimensional network structure, gas dispersion medium, and nanoscale solid phase and pore structure make it have unique physical and chemical properties, such as: it has the lowest density and the smallest thermal conductivity in solid materials (the thermal conductivity in vacuum at room temperature can be reduced to 0.001W / m K), the sound transmission velocity is the lowest, the porosity is the highest (up to 99.8%), and the specific surface area is high (up to 1000m 2 / g), ...

Claims

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Application Information

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IPC IPC(8): C01B33/16
CPCY02P20/54
Inventor 姜法兴林芬张蓉艳余盛锦
Owner 纳诺科技有限公司
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