Synergistic roles of Pt0 and Pt2+ species in propane combustion over high-performance Pt/AlF3 catalysts

Catalytic propane combustion was performed on a series of supported N/AlF3 catalysts. These catalysts are very active and stable in the reaction, and the 0.2Pt/AlF3 catalyst gives the highest specific reaction rate of 207.3 mu mol g(pt)(-1) s(-1) at 220 degrees C. The 1Pt/AlF3 is much more active than the reference Pt/Al2O3 catalyst, due to its higher content of metallic N species than that in the Pt/AL(2)O(3). Furthermore, turnover frequency (TOF) based on N dispersion increases with the surface concentration of metallic Pt-0 in the catalyst, suggesting these species might be the active sites. Furthermore, synergistic roles of metallic and oxidized N species are found, as the TOFs calculated based on surface Pt-0 concentration reaches a maximum at the Pt-0/Pt2+ molar ratio of about 1. Such optimal Pt-0/Pt2+ ratio implies the requirement of Pt-0- Pt2+ pair in the reaction, probably due to the activation and cleavage of C-H bond on metallic N atom and the sequential oxidation on the oxidized N atoms.