Control of mesoporous structure of silica aerogel prepared from TMOS

Silica aerogels were synthesized via the sol-gel polymerization of tetramethylorthosilicate (TMOS) under basic conditions and followed by supercritical drying with carbon dioxide, As a result of characterization by nitrogen adsorption, the aerogels were mesoporous materials with high surface areas and had few micropores. The experimental results suggested that the surface area and the pore radius of the aerogel were controlled by changing the mole ratios of ammonia (NH3) to TMOS in the sol-gel polymerization, On the other hand, the mesopore volume of the aerogel was independent of the [NH3]/[TMOS] ratio. Adsorption isotherms of ethane, ethylene, propane, and propylene were measured on the aerogels. It was found that the [NH3]/[TMOS] ratio influenced the adsorption isotherms. (C) 1997 Academic Press.