STRUCTURAL AND ACIDIC PROPERTIES OF AEROGELS OF NIOBIA, NIOBIA SILICA, AND NIOBIA TITANIA

Aerogel synthesis is an effective way to stabilize niobia, either by itself or in combination with another oxide, from crystallization induced by thermal treatment. Aerogels of niobia, niobia/silica, and niobia/titania prepared from the respective metal alkoxides were X-ray amorphous after calcination at 773 K for two hours and had surface areas that were higher than samples prepared by precipitation. These materials were also acidic as determined by n-butylamine titration. Thermal treatment at higher temperatures led to the crystallization of niobia or compound formation and a concomitant loss in acidity.