Simple preparation of uniformly distributed mesoporous Cr/TiO2 microspheres for low-temperature catalytic combustion of chlorobenzene

Abstract

In this study, novel Cr/TiO2 porous microspheres (h-CrTi) with uniform distribution were successfully prepared by one-step hydrothermal method. For comparative purposes, two other Cr/TiO2 composites were prepared by means of incipient-wetness impregnation (i-CrTi) and co-precipitation (c-CrTi) methods, respectively. The obtained materials were characterized by XRD, BET, XPS, SEM, HRTEM and H2-TPR. The results revealed that h-CrTi0.4 possessed more high valent Cr species and surface-adsorbed oxygen, better crystallinity and Cr species dispersion than i-CrTi0.4 and c-CrTi0.4. These indicated strong interactions between Cr and Ti in h-CrTi0.4 due to better contact. The catalytic activities of the as-obtained materials were tested towards the catalytic combustion of chlorobenzene (CB). The h-CrTi0.4 catalyst possessed not only the best catalytic performance (r = 31.50 × 10−3 μmol·m−2·min−1 at 200 °C at GHSV 15,000 h−1) but also lowest apparent activation energy (55.12 kJ/mol). The TPSR-MS data indicated that h-CrTi0.4 has high ability for removing adsorbed Cl species. h-CrTi0.4 showed stable activity without obvious decrease in CB conversion within 1000 min, which could also degrade dichloromethane (DCM), 1,2-dichloroethane (DCE) and trichloroethylene (TCE) effectively. Therefore, Cr/TiO2 porous microspheres look promising materials for catalytic removal of chlorinated volatile organic pollutants.