Comparison of supported TiO2 catalysts in the photocatalytic degradation of NOx

A comparison is made in this study of the effectiveness of various commercial catalysts in the oxidation of NO by heterogeneous photocatalysis. The following catalysts were considered: Aeroxide TiO P25, Aeroxide TiO P90, Hombikat UV-100, Kronos vlp7000, CristalACTIV PC105, CristalACTIV PC500, Kemira 650 and Anatasa Aldrich. All catalysts were deposited by a dip-coating technique onto borosilicate 3.3 glass plates. Optimization of catalyst load showed no significant enhancement of photoactivity, in general, above a deposited mass of 1.16 mg cm. Differences between photocatalyst activity were more apparent at longer illumination times. Photoactivity decreased in the presence of humidity and differences in the adsorbed products were detected. Photocatalyst activity was strongly influenced by specific surface area, with the best results obtained by the catalysts with the largest surface area, namely the PC500, Hombikat and Kronos. Photocatalyst stability was demonstrated in successive reuse cycles.We are grateful for the financial support of the Spanish Ministry of Economy and Competitiveness through the project IPT-2012-0927-420000 (HORMIFOT) and CTQ2011-24784 and thank the Spanish Ministry of Science and Innovation for the UNLP10-3E-726 infrastructure, co-financed with ERDF funds. M.J. Hernández Rodríguez and E. Pulido Melián would also like to thank the University of Las Palmas de Gran Canaria for their research training grant and postdoctoral contract, respectively