Identifying the surface active sites of FeOx-modified Pt/Nb2O5 catalysts in CO and propane oxidation

A comparative study on FeOx-modified Pt/Nb2O5 catalyzing CO and propane oxidation has been conducted to differentiate the surface active sites demanded for these two important reactions. Pt-Fe/Nb2O5 displays improved activity for CO oxidation but decreased activity for propane oxidation compared to Pt/Nb2O5. Detailed characterizations reveal the alteration of the geometrical and electronic states of Pt species and surface acidity induced upon the addition of FeOx, thus clarifying the divergent catalytic responses in CO and propane oxidation. Pt-FeOx interface sites promotes oxygen activation that is a crucial step in CO oxidation, thereby accelerating the CO oxidation. However, the rate-determining step in propane oxidation is propane activation that requires the synergistic catalysis of acid sites and Pt0, the critical active sites for propane oxidation. The inferior activity of Pt-Fe/Nb2O5 in propane oxidation is explained by the coverage of acid sites and Pt species.