Toluene oxidation on chromium- and copper-modified SiO2 and SBA-15 Original Research Article

Copper- and chromium-modified SiO2 and SBA-15 materials, prepared by a wet impregnation technique, were investigated using X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR-DTG), temperature-programmed oxidation (TPO-DTG), UV–vis diffuse reflectance EPR and FT-IR spectroscopy. Their catalytic behavior was studied in the total oxidation of toluene. The supports had decisive role on the nature and dispersion of the formed metal species. The presence of chromium and copper species, mainly in tetrahedral coordination, was observed for the modified SBA-15 samples, while a significant amount of metal oxides is registered for the modified SiO2 ones. More finely dispersed chromium and copper species were formed on the bi-component copper- and chromium-containing SBA-15 catalysts and possessed higher activity in total oxidation of toluene. The optimal metal oxide content for highly active and selective SBA-15-supported catalyst was found to be 3 wt.% chromium and 7 wt.% copper.