Low-cost method for preparing aerogel by means of atmospheric pressure drying

A technology of normal pressure drying and airgel, applied in chemical instruments and methods, silica, inorganic chemistry, etc., can solve the problems of high cost of solvent replacement and easy pollution, and achieve the effect of improving surface tension and reducing costs

Inactive Publication Date: 2017-05-24
CHENDU NEW KELI CHEM SCI CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Aiming at the problems of high cost and easy pollution caused by direct evaporation of silica skeleton, cavity collapse and solvent replacement, the present invention proposes a method using u

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] (1) Add a certain amount of acid to sodium silicate to adjust the pH, so that the solution is acidic and hydrolyzed to form a silica wet gel;

[0031] (2) Add alkali catalyst urea to the silica wet gel obtained in step (1), place it in a water bath at 30-50°C, let it stand for aging, and form silica gel; the amount of urea added is wet 1% of gel mass;

[0032] (3) Wash the silica gel obtained in step (2) with deionized water several times to remove acid, alkali and impurity ions in the gel;

[0033] (4) Drain the silica gel obtained in step (3) naturally until no more water drips, then immerse in a low-concentration solution prepared by the surfactant tetradecyltrimethylammonium chloride, soak for more than 24 hours, and naturally Drain;

[0034] (5) Place the naturally drained silica gel in step (4) in a drying oven equipped with ultrasonic waves. The silica gel is placed on the overhead layer. The lower part is a carbon dioxide gas heat source at a temperature of 90...

Embodiment 2

[0037] (1) Add a certain amount of acid to the water glass to adjust the pH, so that the solution is acidic and hydrolyzed to form a silica wet gel;

[0038] (2) Add alkali catalyst ammonia water to the silica wet gel obtained in step (1), place it in a water bath at 30-50°C, let it stand for aging, and form silica gel;

[0039] (3) Wash the silica gel obtained in step (2) with deionized water several times to remove acid, alkali and impurity ions in the gel;

[0040] (4) Drain the silica gel obtained by cleaning in step (3) naturally until no more water drips, then immerse in a low-concentration solution prepared by a surfactant, soak for more than 24 hours, and drain naturally;

[0041](5) Place the silica gel drained naturally in step (4) in a drying oven equipped with ultrasonic waves. The silica gel is placed on the overhead layer. The lower part is a 60°C nitrogen heat source, and the upper part is an outlet for volatile matter. Ultrasonic waves are generated by two ult...

Embodiment 3

[0044] (1) Add a certain amount of acid to adjust the pH of tetraethyl orthosilicate, so that the solution is acidic and hydrolyzed to form a silica wet gel;

[0045] (2) Add alkali catalyst sodium hydroxide to the silica wet gel obtained in step (1), place it in a water bath at 30-50°C, let it stand, and age to form silica gel;

[0046] (3) Wash the silica gel obtained in step (2) with deionized water several times to remove acid, alkali and impurity ions in the gel;

[0047] (4) Drain the silica gel obtained by cleaning in step (3) naturally until no more water drips, then immerse in a low-concentration solution prepared by a surfactant, soak for more than 24 hours, and drain naturally;

[0048] (5) Place the silica gel drained naturally in step (4) in a drying oven equipped with ultrasonic waves. The silica gel is placed in the overhead layer, the lower part is a stable gas heat source, and the upper part is the volatile matter outlet. Ultrasonic waves are generated by 5 u...

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Abstract

The invention provides a low-cost method for preparing aerogel by means of atmospheric pressure drying. The method is characterized by comprising the steps of mixing a silicon source (comprising organosilicone and inorganic silicate) with water, adjusting the pH of a mixture system to a gel environment by using acid, and gelatinizing the mixture system to form hydrogel; then, washing the obtained hydrogel with tap water, and naturally draining off so as to reduce the salinity in the hydrogel; washing the hydrogel with a water solution prepared from a surface active agent and then naturally draining off, sending the hydrogel into an atmospheric pressure drying oven, wherein an ultrasonic generator is arranged in the drying oven, directly heating and drying under the assistance of ultrasonic wave so as to obtain the aerogel. The method greatly reduces the structural shrinkage, caused by a surface tension effect, of the hydrogel in a drying process by means of the assistance of ultrasonic wave, thus realizing low-cost atmospheric pressure drying preparation of the aerogel.

Description

technical field [0001] The invention relates to the preparation of silicon dioxide airgel, in particular to a method for preparing silicon dioxide airgel by adopting ultrasonic-assisted heating and drying under normal pressure. Background technique [0002] Aerogel is a light, porous solid material with a particle size between 1 and 100nm. It is a typical nanomaterial, and its porosity can reach 80 to 99.8%. Due to the specific porous nano-network structure of airgel, it has incomparable excellent performance of other solid materials, and its density can reach as low as 3kg / m 3 , the specific surface area can reach 1000m 2 / g or more, the thermal conductivity is extremely low, and the room temperature vacuum thermal conductivity can even reach 0.00lw m -1 ·K -1 , These excellent properties of airgel make it widely used in heat insulation, sound insulation, environmental protection, catalysis, adsorption and high-performance capacitors. However, due to its expensive man...

Claims

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Application Information

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IPC IPC(8): C01B33/16
CPCC01B33/16C01B33/163C01P2006/12
Inventor 陈庆曾军堂王镭迪
Owner CHENDU NEW KELI CHEM SCI CO LTD
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