Synthesis and characterization of Ag/TiO2/composite aerogel for enhanced adsorption and photo-catalytic degradation of toluene from the gas phase

Abstract

Despite titanium dioxide has some remarkable properties as a photo-catalyst, its usage in the photo-catalysis processes is associated with several drawbacks, like high band gap energy and clumping of its particles. In this study, a composite aerogel was exploited as a support for titanium dioxide to prevent clump formation and increase the production of electron-hole pairs. The results revealed that both utilized nanoparticles, i.e. TiO2 and Ag, were uniformly dispersed on the surface of composite aerogel. The absorption region of the synthesized catalysts shifted to the visible region and, in fact, the additions of Ag to the composite aerogel reduce the band gap energy of TiO2 from 3.17 to 2.7 eV. Studies on the degradation of toluene in gas streams through a fluidized bed reactor showed that the photo-catalytic activity of TiO2 supported on the composite aerogel was much higher than that of the unsupported titanium dioxide, so that the degradation rates of toluene were 95.7% and 15%, respectively for supported and unsupported TiO2. The results indicated that the highest oxidation rate of toluene was obtained at 45% humidity. The Intermediate products formed during the degradation of toluene by the composite photo-catalyst were identified which were included formic acid, acetic acid, and benzaldehyde. Overall, the composite aerogel could be used as a useful support for the TiO2 catalyst, and the prepared photo-catalyst has a high potential to be used in the oxidation of toluene in gas-phase streams in industrial scale.