Hybrid photocatalysts for the degradation of trichloroethylene in air

Hybrid photocatalysts based on an adsorbent SiMgOx and a photocatalyst TiO2 were developed in a plate shape. The ceramic surface was coated with TiO2 by the slip-casting technique. The effect of the support in the photocatalytic degradation of trichloroethylene (TCE) was analyzed by modifying TiO2 loading and the layer thickness. Photocatalysts were characterised by N2 adsorption–desorption, mercury intrusion porosimetry, SEM, UV–vis spectroscopy and XRD. A direct relationship between the TiO2 content and the photocatalytic activity was observed up to three layers of TiO2 (0.66 wt.%). Our results indicate that intermediate species generated on the TiO2 layer can migrate through relatively long distances to react with the OH− surface groups of the support. By increasing the TiO2 loading of the photocatalyst two effects were observed: trichloroethylene conversion is enhanced, while the efficiency of the oxidation process is decreased at expenses of increasing the selectivity to COCl2 and dichloroacetylchloride (DCAC). The results are discussed in terms of the layer thickness, TiO2 amount, TCE conversion and CO2, and COCl2 selectivity.