Internal reforming of hydrocarbon fuels in SOFCs with Ni-ScSZ anode

The effects of carbon number in hydrocarbon fuels, steam-to-carbon ratios (S/Cs), fuel utilization (U_f), and CeO₂ dispersion into the anode on the internal reforming operation of solid oxide fuel cells (SOFCs) with Ni-ScSZ anode were examined at 1073K using the cell containing scandia-stabilized zirconia (ScSZ) electrolyte and NirScSZ anode. The low reforming rate (20%) of methane led to a low maximum U_f (only 20%). Propane, n-octane, and n-dodecane fuels were reformed easily, and a large amount of H₂ was produced, resulting in maximum U_f of about 75, 80 and 85%, respectively. At S/C between 2 and 1 with n-dodecane fuel, stable operations at 100 mA (corresponding to about 45% U_f) were achieved for more than 120 hours with anode potential of about -0.77 V without degradation of Ni-ScSZ anode or Ni current collector. With increasing S/C, CO shift reaction was promoted but reforming reactions of hydrocarbons were not. With increasing U_f, oxidation reaction of H₂ and shift reaction of CO are promoted, and reforming reactions of hydrocarbons are slightly promoted. Dispersion of CeO₂ into the anode promoted H ₂-producing reactions such as reforming of hydrocarbons.