Reaction gas treatment promoting activity and stability of PdO for lean methane oxidation over phosphorus modified Pd/Al2O3 catalysts

Pretreatment under specific atmosphere is a general strategy to activate catalysts. How physicochemical properties of supports are modulated during activation process and their influence on active sites are still the ongoing topic. Herein, the effect of reaction gas treatment on performance of phosphorus modified Pd/Al2O3 catalysts in lean methane oxidation was studied. The pretreated Pd/P-doped Al2O3 catalyst exhibited a full conversion of CH4 at ∼400 °C, excellent stability under both dry and wet conditions. Characterization results reveal that the uniform and stable P species in Al2O3 enhanced the metal-support interaction and availability of oxygen in support. Under reaction gas condition, PdO-support connection was further promoted to favor generation of oxygen vacancies on support with the help of CH4, leading to weakened Pd–O bond, facile reformation and increased fraction of PdO. These facilitated formation of intermediates and surface dehydroxylation and mitigated the deactivation caused by thermodynamic decomposition of PdO.