Fuel reforming and electrical performance studies in intermediate temperature ceria-gadolinia-based SOFCs

The methane reforming and carbon deposition characteristics of two nickel/ceria-gadolinia cermet anodes have been studied over the temperature range 550-700 degrees C, for use in intermediate temperature ceria-gadolinia (CGO)-based solid oxide fuel cells (SOFCs), using conventional catalytic methods and temperature-programmed spectroscopy. The electrical performance and durability of planar CGO-based SOFCs with a 280-mu m-thick CGO electrolyte, screen printed cathode and different screen printed nickel/CGO cermet anodes have been studied over the temperature range 500-650 degrees C. Temperature-programmed reduction has been used to study the reduction characteristics of the anodes, and indicates the presence of "bulk" NiO particles and smaller NiO particles in intimate contact with the ceria. Both anodes show good activity towards methane steam reforming with methane activation occurring at temperatures as low as 210 degrees C; steady-state steam reforming of methane was observed using a methane-rich mixture at 650 degrees C, with 20% methane conversion. Post-reaction temperature-programmed oxidation has been used to determine the amount of carbon deposited during reforming and the strength of its interaction with the anode. (C) 2000 Elsevier Science S.A. All rights reserved.