PREPARATION AND CHARACTERIZATION OF POROUS ALUMINA-TITANIA AEROGEL VIA CO2 SUPERCRITICAL EXTRACTION

Silvester Tursiloadi (Research Center for Chemistry, Indonesian Institute of Sciences, Kawasan PUSPIPTEK, Serpong, Tangerang 15314)
Hiroaki Imai (Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-Ku, Yokohama 223-8522)
Hiroshi Hirashima (Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-Ku, Yokohama 223-8522)

Indonesian Journal of Chemistry
Vol 4, No 3 (2004)

Porous aerogel of titania-alumina were prepared by hydrolysis of metal alkoxides and supercritical extraction of the solvent.  Monolithic wet-gel of 0.2TiO2-0.8Al2O3, prepared by hydrolysis of metal alkoxides in alcoholic solutions, and the solvent in wet gel was supercritically extracted in CO2 at 60oC and 24Mpa for 2h. Thermal evolutions of the microstructure of the gel were evaluated by differential thermal analysis (TG-DTA), N2 adsorption, scanning electron microscopy and X-ray diffractometer. After calcination at 500oC, the specific surface area of the gel was more than 400m2g-1. The average pore radius of aerogel, about 8nm, was about 50% of that for alumina aerogel, but about 4 times larger than that of the xerogel.  The specific surface area of the aerogel was more than 200m2g-1 after calcination at 800oC. The pore size and pore volume of aerogel hardly decreased after calcinations at 800oC, although those values of the xerogel remarkably decreased after calcination up to 800oC. The thermal stability of the microstructure of porous titania-alumina is improved by supercritical extraction.