Photocatalytic degradation of methanol on titania and titania-silica aerogels prepared by non-alkoxide sol-gel route

Abstract

Titania and titania-silica aerogels were prepared by alkoxide or non-alkoxide sol-gel route and subsequent supercritical drying with carbon dioxide at low temperature. The resulting aerogels having high surface area and mesoporosity were used as photocatalysts for gas phase methanol degradation reaction. Photocatalytic degradation reactions were carried out on titania and titania-silica aerogels, and commercial Degussa P-25 titania. The photocatalytic activities of titania and titania-silica aerogels were higher than that of the P-25. While the conversion of methanol degradation over the P-25 catalyst was only 50-60%, that for the titania aerogel was observed to be above 98% due to the higher specific surface area and the well developed mesoporous structure. In spite of lower titania contents, much higher surface area and high dispersion of titania of titania-silica aerogel gave rise to the high photocatalytic activity in comparison to those of titania aerogels. Moreover, titania-silica aerogel was also used for the photodegradation and adsorption hybrid system. It was observed that the high removal efficiency for methanol was caused by the combination of higher catalytic activity and adsorption capacity.