Synchrotron radiation PXRD investigation of V2O5/TiO2 catalysts for 1,2-dichlorobenzene oxidation: Implication of structure modification

V2O5/TiO2 catalysts were prepared by depositing vanadia on nano-particles of anatase TiO2 and tested for oxidation of 1,2-dichlorobenzene. Activity of the catalyst can be enhanced by adding MoO3 to the catalysts and introducing sulfur-containing compounds to the reaction system. Kinetic studies indicate that addition of MoO3 reduces the apparent activation energy slightly and increases the pre-exponential factors at reaction temperatures higher than 350 degrees C; in contrast, introduction of sulfur-containing compounds only increases the pre-exponential factors. XRD and FT-IR results indicate that MoO3 disperses vanadia species and induces formation of crystalline MoV2O8 during the reaction, whereas introduction of sulfur-containing compounds leads to no significant structure change. Based on these characterizations and analyses of the kinetic results, we suggest that increased catalyst acidity results in higher pre-exponential factors, while structure change in vanadia species leads to reduction in apparent activation energy. (C) 2011 Elsevier B.V. All rights reserved.