Methane oxidation over nanocrystalline Ce0.45Zr0.45La0.10O2-δ/Pt and Ce0.9Sm0.1O2-δ/Pt anodes

Abstract

The electrocatalytic activity of composite anodes, comprising metallic platinum and nanocrystalline Pt-modified Ce0.45Zr0.45La0.10O2-δ and Ce0.9Sm0.1O2-δ , was evaluated for the oxidation of dry methane in a solid oxide fuel cell (SOFC) – type reactor with yttria-stabilized zirconia solid electrolyte. At 923–1073 K, the total combustion is dominant, whilst above 1100 K the composite anodes exhibit significant catalytic activity towards the partial oxidation of methane (POM). At 1223 K and for a O2:CH4 ratio equal to 0.5, stoichiometric for the POM reaction, CO selectivity and CH4 conversion over Ce0.9Sm0.1O2-δ /Pt achieves 55% and 41%, respectively. Under these conditions, Ce0.45Zr0.45La0.10O2-δ /Pt anodes possess higher catalytic activity for partial oxidation, associated with the lower lattice oxygen mobility and instability of the Ce0.45Zr0.45La0.10O2-δ cubic fluorite structure, and provide 54% conversion efficiency with 73% selectivity to carbon monoxide. Further increase in CH4 conversion and CO selectivity can be achieved by packing the reactor with an additional catalyst, such as Pt-promoted Ce0.45Zr0.45La0.10O2-δ or LaNiO3-δ / Al2O3 .