Catalytic propane reforming mechanism over Zr-doped CeO2 (111)

Abstract

Elucidation of the elementary reaction processes involved in hydrocarbon oxidation on oxide catalysts can help guide active site optimization. We use density functional theory (DFT) methods to examine the reforming of propane over the Zr-doped CeO₂ (111) surface. Numerous modeling and mechanistic questions arise in modeling this multistep reaction on oxides. The surface redox and coverage state in the reaction environment impacts energetics and must be considered. Phase diagrams of Zr-doped and pure CeO₂ (111) are created based upon the partial pressure of oxygen and hydrogen, demonstrating that the surface will be reduced under operating conditions. All elementary energetics along the preferential path for propane reforming were identified, and differences in path with oxygen pressure variance were identified. The reaction path varies depending on the oxygen chemical potential as this alters at which step in the mechanism the surface will re-oxidize.