Preparation of Nano-porous aerogels by supercritical drying

Abstract

Nano-porous silica aerogels are synthesized by two steps by the supercritical condition. By synthesized process, tetra-ethyoxysilane is used as raw material, isopropanol and H₂O which is distilled after ion exchange was used as solvent, HCl and NH₄OH are used as hydrolysis and condensation catalysts, glycerol is used as drying control chemical agent. Silica aerogels are obtained by supercritical drying condition after aging, surface modification and exchanging solvent. The effect of water, PH, temperature, and so on, are analysed at supercritical drying condition. The resulting aerogels are characterized by means of X-ray diffraction and scanning electron microscopy. It is found that the aerogels made by this method have high porosity, specific surface area and the structure is sponge with narrow particle and pore size distribution.

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