Insights into propane combustion over MoO3 promoted Pt/ZrO2 catalysts: The generation of Pt-MoO3 interface and its promotional role on catalytic activity

Abstract

The addition of MoO3 in Pt/ZrO2 catalysts significantly improves the activities for propane combustion. The highest activity (a reaction rate of 845.4 mol s-1gPt-1 and a turnover frequency (TOF) of 0.688 s−1 at 200 °C) was obtained on a Pt-1Mo/ZrO2 catalyst (with 1 wt% Mo content), which is much higher than that on the bare Pt/ZrO2 (a reaction rate of 42.4 mol s-1gPt-1 and a TOF of 0.0186 s−1 at 200 °C). Such improvement is due to the generation of the Pt-MoO3 interfacial sites, on which the cleavage of C-H bond and decomposition of the surface carbonates were accelerated. Moreover, the intrinsic activities of active Pt sites (TOFPt) and Pt-MoO3 interfacial sites (TOFPt-MoO3) were clearly differentiated, namely, the interfacial sites possess ca. 40-fold higher activity than the Pt surface atoms (with TOFPt-MoO3 of 0.731 s−1 at 200 °C versus TOFPt of 0.0186 s−1) for Pt-1Mo/ZrO2 catalyst.