Insight into the improvement effect of the Ce doping into the SnO2 catalyst for the catalytic combustion of methane

Abstract

Herein, we report the performance of the catalytic combustion of methane over the Ce-doped SnO2 catalysts. Doping with Ce increases the surface areas, decreases the crystallite sizes, and activates both the surface metal cations and surface oxygen species. Upon methane combustion, the surface Sn4+ cations are active sites, and the surface lattice oxygen plays an important role, as well. Kinetics results suggest that the activation energy (Ea) and pre-exponential factor (A) are determined by the reducibility and the area-specific quantity of the surface Sn4+ cations, respectively. The Sn0.7Ce0.3O2 catalyst exhibits the highest area-specific rate because of its lowest Ea and relatively bigger A values. Its turnover frequency is five times higher, as compared with the SnO2. The reaction pathways upon the Sn-rich catalysts (SnO2 phase) follow the Mars–van Krevelen model, while they become more complex upon the Ce-rich ones (CeO2 phase). Additionally, these SnO2-based catalysts display the high water resistance.