Adsorption and photocatalytic decomposition of benzene using silica-titania and titania aerogels: Effect of supercritical drying

Silica-titania and titania aerogels were prepared by supercritical drying u sing different solvents such as low temperature CO2 (353 K), high temperatu re CO2 (553 K), ethanol (553 K) and ethanol with zeolite (553 K) and their efficiencies for the removal of benzene from a synthetic air mixture were i nvestigated. The aerogels obtained showed both large capacities for benzene adsorption and high photocatalytic activity for its decomposition in the a dsorbed state. The degree of benzene removal by silica-titania aerogel seem ed to depend on the crystallinity of the titania and was in the order low t emperature CO2 < high temperature CO2 < ethanol = ethanol with zeolite. The amount of CO2 liberated by the photocatalytic decomposition of benzene als o followed the same sequence. Titania aerogels showed the greatest efficien cy in the decomposition of benzene, while the amount of CO2 evolved was low er than those of the silica-titania systems investigated. The adsorption ca pacity of benzene basically depended on the silica matrix and was not great ly influenced by the difference in the crystallinity of titania.