Calcium-Modified Ni-SDC Anodes in Solid Oxide Fuel Cells for Direct Dry Reforming of Methane

Direct internal reforming is one of the promising methods of utilizing hydrocarbon fuels in solid oxide fuel cells (SOFCs). Among direct internal reforming technologies, dry reforming of methane (DRM) is attracting attention as an alternative to steam reforming of methane. In this study, a cermet material composed of nickel and samarium-doped ceria (Ni-SDC) was investigated as an SOFC anode for the direct internal DRM operation. Compared to a conventional nickel-yttria-stabilized zirconia (Ni-YSZ) anode, the Ni-SDC anode showed superior current-voltage characteristics. However, poor carbon balances were recorded in anode outlet gas analysis, indicating coke formation on the Ni-SDC anode. The addition of calcium to the Ni-SDC anode was also tested. Measured anode outlet gas compositions suggested that the calcium addition suppressed coke formation, while the power generation performance of the pristine Ni-SDC anode was maintained. Microscopic observations showed that a certain part of the calcium additive existed as CaO particles on the anode surface, which could be responsible for the improved coking resistance.