Total oxidation of toluene over metal oxides supported on a natural clinoptilolite-type zeolite

Some selected (Mn2+, Co2+, Fe3+, Cu2+) oxides supported on clinoptilolite were tested in the catalytic incineration of toluene. Manganese oxide on clinoptilolite was found to be the most active and durable of all tested. The effects of ion exchanger concentration, ion exchange time, ion exchange temperature and the type of ion exchanger were also studied to screen metal oxide catalysts. The catalysts were prepared by incipient wetness impregnation of clinoptilolite in hydrogen form (HCLT). They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed reduction/oxidation (TPR/TPO) and diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy techniques. Activities of the candidate catalysts were correlated with crystallinity, surface acidity, adsorption properties and morphological parameters. 9.5% MnO2 on clinoptilolite exhibits the highest performance among the different oxides. Its higher activity was attributed to its ability to maintain its redox potential. Furthermore, this novel generation of catalysts appeared as active as conventional ZSM-5 and BETA. Finally, it was found that all four metal oxides supported on clinoptilolite led to the considerable decrease in combustion temperature.