Improved methane oxidation activity of P-doped γ-Al2O3 supported palladium catalysts by tailoring the oxygen mobility and electronic properties

Micro-mesoporous P-doped γ-Al₂O₃ with cluster morphology was obtained via an efficient ultrasound-assisted sol-gel process and taken as carrier to construct palladium catalysts for methane oxidation. It was revealed that the structure and properties of catalysts were significantly influenced by the phosphorus precursors with diverse valence and acidity. Dissimilar reducibility of surface hydroxyl and oxygen species is observed in the catalysts derived from different phosphorus sources, indicating the difference in the oxygen mobility and the capacity of the catalysts to convert intermediate CO. The behavior of charge-transfer transition and d-d transition, the transfer ability of electrons from palladium particles into the antibonding 2π* orbitals of CO, together with the surface acidity and electronic density of palladium species was likewise tailored, which demonstrated the metal-support interaction could be tuned, making palladium species behave with diverse status and electronic structures. The optimized properties cooperatively provided an enhancement in catalytic performance of P-containing catalysts.