Preparation method of silica aerogel

A silica and aerogel technology, applied in chemical instruments and methods, inorganic chemistry, silicon compounds, etc., can solve the problem that the distribution state is not easy to control, the group distribution is irregular, and it is difficult to obtain a monolithic bulk aerogel and other problems, to achieve the effect of reducing cost and operation risk, simple equipment and low density

Active Publication Date: 2018-10-02
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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Problems solved by technology

The disadvantage of the one-step solvent exchange-surface modification method is that the modification process is easily affecte...

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  • Preparation method of silica aerogel
  • Preparation method of silica aerogel
  • Preparation method of silica aerogel

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preparation example Construction

[0033] A preparation method of silica airgel, comprising the following steps:

[0034] 1)SiO2 2 Synthesis of Wet Gels:

[0035] a) According to the molar ratio of 1:0.3:(4~14):(6~16), add ethyl orthosilicate, methyltriethoxysilane, absolute ethanol and ultrasonic water into the beaker, add Hydrochloric acid, adjust the pH value to 2.5-3, and keep stirring in the water bath magnetic stirrer for 30-60 minutes to promote the full hydrolysis of the system;

[0036] b) adding a solution concentration of 0.5mol / L ammonia solution, adjusting the pH value to 7-7.5, promoting gel polycondensation, and standing at room temperature to form a gel;

[0037] 2) Aging and modification

[0038] a) Put the gel in an absolute ethanol solution at a temperature of 55-60° C. and let it age for 24-48 hours;

[0039] b) After aging, place the aged gel in a surface modification solution mixed with trimethylchlorosilane, absolute ethanol and n-hexane at a volume ratio of 1:1:8 for modification, an...

Embodiment 1

[0044] According to the raw materials according to the molar ratio of ethyl orthosilicate: methyltriethoxysilane: absolute ethanol: ultrasonic water = 1:0.3:6:14, 15.627g of TEOS, 4.011g of MTES, 20.73g of Mix water ethanol and 18.6g of ultrasonic water into the beaker, place it in a water bath environment at 25°C and stir. After 30 minutes, stir evenly and dropwise add hydrochloric acid solution to adjust the pH value, so that the pH value of the solution is about 2.5; after continuous stirring for 30 minutes, then Add a certain amount of ammonia solution with a concentration of 0.5mol / L to make the final pH of the system around 7.5, and let it stand to obtain SiO 2 gel. After the gel is formed, soak the gel in absolute ethanol solution for aging, the aging temperature is 55°C, and the aging time is 48h; Modified in silane (TMCS) / absolute ethanol (EtOH) / n-Hexane (n-Hexane) surface modification solution, soaked under sealed conditions for 48h. After the modification, the sam...

Embodiment 2

[0047] According to the raw material molar ratio of ethyl orthosilicate: methyltriethoxysilane: absolute ethanol: ultrasonic water = 1:0.3:4:16, 15.627g of TEOS, 4.011g of MTES, 13.87g of anhydrous Mix ethanol and 22.24g of ultrasonic water into the beaker, place it in a water bath environment at 25°C and stir it. After 35 minutes, stir evenly and add hydrochloric acid solution dropwise to adjust the pH value so that the pH value of the solution is about 3; after continuous stirring for 35 minutes, then Add a certain amount of ammonia solution with a concentration of 0.5mol / L to make the final pH of the system around 7, and let it stand to obtain SiO 2 gel. After the gel is formed, soak the gel in absolute ethanol solution for aging, the aging temperature is 60°C, and the aging time is 24h; after aging, place the gel in trimethyl chloride with a volume ratio of 1:1:8 Modified in silane (TMCS) / absolute ethanol (EtOH) / n-Hexane (n-Hexane) surface modification solution, soaked un...

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Abstract

The invention discloses a preparation method of silica aerogel. Ethyl orthosilicate serves as a silicon source, methyl triethoxysilane serves as a co-precursor, ultrasonic water serves as a reactant,absolute ethyl alcohol serves as a solvent, hydrochloric acid and ammonia water serve as catalysts, SiO2 wet gel is prepared by acid-base two-step catalysis, secondary modification and ambient pressure drying and soaked in absolute ethyl alcohol solution, a wet gel sample is subjected to surface modification in trimethylchlorosilane, absolute ethyl alcohol and n-hexane mixed solution with a certain volume ratio after standing and aging for a period of time, and finally, the SiO2 aerogel is prepared by ambient pressure drying in air atmosphere. The method for preparing the silica aerogel is simple in process and strong in controllability and has good heat conductivity coefficient, specific surface area, average pore diameters, density, porosity, contact angles and reproducibility.

Description

technical field [0001] The invention belongs to the technical field of thermal insulation materials, and relates to a preparation method of silica airgel. Background technique [0002] SiO 2 Airgel is the world's lightest nano-light porous material with the best thermal insulation, high specific surface area and porosity. Due to its unique structure, SiO 2 Airgel has great potential application value in the fields of heat insulation, catalysis, electricity, optics and medicine. [0003] Existing preparation of SiO 2 The process of wet gel includes two processes of sol-gel and post-treatment. The sol-gel process is to hydrolyze the silicon source under acidic conditions for a certain period of time, and then adjust the pH value to make the system under alkaline conditions to promote polycondensation reaction to synthesize wet gel. The post-treatment process includes aging and surface modification. Aging can promote the dissolution and polycondensation of gel particles, in...

Claims

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Application Information

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IPC IPC(8): C01B33/152C01B33/158C01B33/159
CPCC01B33/152C01B33/1585C01B33/159C01P2002/72C01P2002/82C01P2006/10C01P2006/12C01P2006/16C01P2006/17C01P2006/32C01P2006/90
Inventor 闫秋会夏卫东罗杰任
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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