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

摘要

Various Ni-La_xCe_(1_x)O_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_(0.1)Ce_(0.9)O_y showed the highest catalytic performance and also the best coking resistance. The Ni-La_xCe_(1-x)O_y catalysts with a higher Ni content were further sintered at 1400 ℃ and investigated as anodes of solid oxide fuel cells for operating on methane fuel. The Ni-La_(0.1)Ce_(0.9)O_y anode presented the best catalytic activity and coking resistance in the various Ni-La_xCe_(1-x)O_y catalysts with different ceria contents. In addition, the Ni-La_(0.1)Ce_(0.9)O_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_(0.1)Ce_(0.96)O_y anode and a catalyst yielded a peak power density of 850 mW cm~2 at 650 ℃ while operating on a CH_4-H_2O 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_(0.1)Ce_(0.9)O_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.