PREPARATION OF MESOPOROUS TITANIA-SILICA AEROGELS BY CO2 SUPERCRITICAL EXTRACTION

Stable anatase is attractive because of its notable functions for photocatalysis and photon-electron transfer. TiO2-nanoparticles dispersed SiO2 wet gels were prepared by hydrolysis of Ti(OC4H9n)(4) and Si(OC2H5)(4) in a 2-propanol solution with acid catalyst. The solvent in the wet gels was supercritically extracted using CO2 at 60 degrees C and 22 Mpa in one-step. Thermal evolution of the microstructure of the extracted gels (aerogels) was evaluated by XRD measurements, TEM and N-2 adsorption measurements. The as-extracted aerogel with a large specific surface area, more than 365 m(2)g(-1), contained anatase nanoparticles, about 5 nm in diameter. The anatase phase was stable after calcinations at temperatures up to 1000 degrees C, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcinations at temperature up to 800 degrees C.