Vinyl chloride catalytic combustion on Pt/CeO2: Tuning Pt chemical state to promote Cl removing

Abstract

Supported Pt catalysts usually produce chlorinated byproducts during chlorinated volatile organic compounds (CVOCs) combustion, the removal of formed surface chlorine species is the key to improve the activity, selectivity and stability. In this paper, the Pt chemical state is adjusted by the interaction between Pt and CeO2 through controlling the morphology of CeO2, which further affects the catalytic performance of VC combustion. For Pt/CeO2-octahedron, the weak interaction between Pt and CeO2 results in the formation of PtO2, facilities VC adsorption and C–Cl bonds cleavage and becomes a key active site to accommodate the dissociated Cl species. While the strong interaction leads to the formation of PtxCe1-xO2-σ solid solution on Pt/CeO2-rod has relative lower ability in Cl species removal compared with PtO2. Density functional theory (DFT) calculations also confirms that the introduced Pt species reduces the concentration of Cl species on the surface as well as the chlorinated-byproducts. Hence, Pt/CeO2-octahedron outperformed Pt/CeO2-rod and Pt/CeO2-cube with 90% VC conversion at 280 °C. Furthermore, under the same VC conversion (90%), the concentration of chlorinated byproducts on Pt/CeO2-octahedron was only 4% than that of Pt/CeO2-rod.