Catalytic methane combustion over novel catalyst based on oxide-ion-conducting lanthanum silicate

Abstract

A novel PdO/La₁₀Si₆O₂₇/γ-Al₂O₃ catalyst was developed in order to decompose methane. In this catalyst, we selected the oxide-ion-conducting La₁₀Si₆O₂₇ solid with an apatite-type structure as a promoter to facilitate the supply of active oxygen to the PdO activator. For the comparison with PdO/La₂O₃/γ-Al₂O₃, where La₂O₃ is a simple rare earth sesquioxide, the catalytic activity of PdO/La₁₀Si₆O₂₇/γ-Al₂O₃ was higher than that of PdO/La₂O₃/γ-Al₂O₃, regardless of their same surface area. Since La₁₀Si₆O₂₇ exhibited two orders of magnitude higher conductivity than La₂O₃, the high oxide-ion-conducting property of La₁₀Si₆O₂₇ might facilitate the oxidation of methane by supplying active oxygen from inside the lattice.