Effect of active oxygen on the performance of Pt/CeO2 catalysts for CO oxidation

Abstract

This study was focused on the influence of active oxygen on the performance of Pt/CeO2 catalysts for CO oxidation. A series of CeO2 supports with different contents of active oxygen were obtained by adding surfactant at different synthesis steps. 0.25 wt% Pt was loaded on these CeO2 supports by incipient-wetness impregnation methods. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), H2 temperature-programmed reduction (H2-TPR), dynamic oxygen storage capacity (DOSC) and in-situ DRIFTS technologies. For S-f supports, the surfactant was added into the solution before spray-drying in the synthesis process, which facilitates more active oxygen formation on the surface of CeO2. After loading Pt, the more active oxygen on CeO2 contributes to dispersing Pt species and enhancing the CO oxidation activity. As for the aged samples, Pt-R-h shows the highest activity above 190 °C because of the presence of more partly oxidized Ptδ+ species. Thus the activity is also influenced by the states of Pt and the Ptδ+ species may contribute to the high activity at elevated temperature.