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 using different solvents such as low temperature CO2 (353 K), high temperature 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 investigated. The aerogels obtained showed both large capacities for benzene adsorption and high photocatalytic activity for its decomposition in the adsorbed state. The degree of benzene removal by silica-titania aerogel seemed to depend on the crystallinity of the titania and was in the order low temperature CO2 < high temperature CO2 < ethanol = ethanol with zeolite. The amount of CO2 liberated by the photocatalytic decomposition of benzene also followed the same sequence. Titania aerogels showed the greatest efficiency in the decomposition of benzene, while the amount of CO2 evolved was lower than those of the silica-titania systems investigated. The adsorption capacity of benzene basically depended on the silica matrix and was not greatly influenced by the difference in the crystallinity of titania.