Catalytic combustion of lean methane over a core-shell structured Pd-Co₃O₄@SiO₂ catalyst

A core-shell structured Pd-Co₃O₄@SiO₂ catalyst was prepared by a simple self-assemble method and used in lean methane combustion. The results of catalytic tests indicate that the core-shell Pd-Co₃O₄@SiO₂ catalyst exhibits high activity in lean methane combustion and superior stability at high temperature. The results of TEM, XRD, and H₂-TPR characterization suggest that the high activity of Pd-Co₃O₄@SiO₂ is mainly ascribed to the strong interaction between CoO_x and PdO species inside the SiO₂ shell. Meanwhile, as the active Pd and CoO_x species in Pd-Co₃O₄@SiO₂ are enshielded in the core-shell structure, which is effective to protect the active phase from sintering at high temperature, the core-shell structured Pd-Co₃O₄@SiO₂ catalyst is thus far superior in thermal stability against high temperature to the supported Pd/Co₃O₄@SiO₂ and Pd/Co₃O₄-SiO₂ catalysts.