A new nickel-ceria composite for direct-methane solid oxide fuel cells

Various Ni-La_xCe_1-xO_y composites were synthesized and their catalytic activity, catalytic stability and carbon deposition properties for steam reforming of methane were investigated. Among the catalysts, Ni-La_0.1Ce_0.9O_y showed the highest catalytic performance and also the best coking resistance. The Ni-La_xCe_1-xO_y catalysts with a higher Ni content were further sintered at 1400 °C and investigated as anodes of solid oxide fuel cells for operating on methane fuel. The Ni-La_0.1Ce _0.9O_y anode presented the best catalytic activity and coking resistance in the various Ni-La_xCe_1-xO_y catalysts with different ceria contents. In addition, the Ni-La _0.1Ce_0.9O_y also showed improved coking resistance over a Ni-SDC cermet anode due to its improved surface acidity. A fuel cell with a Ni-La_0.1Ce_0.9O_y anode and a catalyst yielded a peak power density of 850 mW cm^-2 at 650 °C while operating on a CH₄-H₂O gas mixture, which was only slightly lower than that obtained while operating on hydrogen fuel. No obvious carbon deposition or nickel aggregation was observed on the Ni-La _0.1Ce_0.9O_y anode after the operation on methane. Such remarkable performances suggest that nickel and La-doped CeO ₂ composites are attractive anodes for direct hydrocarbon SOFCs and might also be used as catalysts for the steam reforming of hydrocarbons.