Insight into the roles of Pd state and CeO2 property in C3H8 catalytic oxidation on Pd/CeO2

Abstract

Propane oxidation is a key reaction in the three-way catalytic reaction. The dispersion state of Pd species and property of CeO2 have significant impacts on the C3H8 oxidation over Pd/CeO2 catalyst via altering the activation pathways of C3H8. Herein, Pd/CeO2 catalysts with highly dispersed Pd species (Pd/CeO2-IWI) and uniform PdO nanoparticles (4.3 ± 0.3 nm) (Pd/CeO2-EG) were prepared, respectively. The highly dispersed Pd species on Pd/CeO2-IWI promoted Pd entering the lattice to form PdxCe1-xO2-σ solid solution through strong Pd-CeO2 interaction, while PdO nanoparticles were the main existing form on Pd/CeO2-EG. The results showed that C3H8 was adsorbed and activated to form acrylate on PdxCe1-xO2-σ, while C3H8 preferred to generate acetone on PdO. However, the main surface intermediates were converted to acetate and formate at the elevated reaction temperature. Compared with PdxCe1-xO2-σ, PdO was more favorable for the rapid oxidative decomposition of acetate to formate, which facilitated the C3H8 oxidation activity. Meanwhile, the property of CeO2 could also influence the C3H8 oxidation activity through the accumulation of formate and carbonate. In which, Pd/CeO2(1000)-EG with the most PdO species and the lowest accumulation of surface formate/carbonate performed the highest C3H8 oxidation activity.