Photocatalytic destruction of toluene and xylene at gas phase on a titania based monolithic catalyst

Toluene and xylene were subjected to gas-solid heterogeneous photocatalytic oxidation on a titania based monolithic catalyst, in order to investigate the potential of solar-driven detoxification as a clean and safe, method for air purification and gas phase waste destruction. Thus, gaseous streams with toluene or xylene were conducted through a monolithic catalysts based on titania dispersed on a fibrous silicate and irradiated with a Xenon lamp in the presence of air, at process temperatures from 150 to 450 degrees C. Destructions levels higher than 96% were achieved for toluene and 99% for xylene at Area Velocity values in the range of 5-8 m h(-1). A non-negligible number of undesirable sub-products (furans and benzofurans) were identified in partial oxidation conditions. The concentration of these sub-products was higher in the thermal process than with the photocatalytic system. Textural properties of the catalyst, the nature of phases and their distribution on the surface and light absorption properties were studied using techniques such as mercury intrusion porosimetry, scanning electron microscopy (SEM-EDX), X-ray diffraction and diffuse reflectance UV-Vis. spectroscopy.