Feasibility of n-dodecane fuel for solid oxide fuel cell with Ni-ScSZ anode

Direct feeding of n-dodecane (C12H26), a model liquid fuel of kerosene, was carried out using a cell consisting of ScSZ electrolyte with Ni-ScSZ cermet anode and Ni mesh current collector. The influence of steam to carbon ratio (S/C) and fuel utilization on the cell performance was examined. At S/C = 1.0-2.0 and low fuel concentration (< 2%), stable operation was achieved at 127 mA/cm(2) (similar to 45% fuel utilization) with an anode potential of about -0.77 V. There was no degradation of the anode and current collector. At S/C = 0.5, a stable operation was also achieved, but the current collector was partially disintegrated. The thermal decomposition of n-dodecane into mainly C2H4 and H-2 occurred without serous carbon deposition and subsequent steam reforming reactions of C2H4 with water vapor produced hydrogen within the Ni-ScSZ anode and onto the Ni current collector. Increasing fuel utilization from 44 to 66% resulted in promoting the H-2 oxidation and the shift reaction of CO. A small amount of methane and C-2 compounds remained and, as a result, the partial pressure of hydrogen was lower than the calculated equilibrium composition. The observed lower open-circuit voltage is due to the incomplete equilibration for internal reforming reaction of n-dodecane. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.1854092] All rights reserved.