Feasibility of Liquid Fuels for SOFC with Ni-Base Anode

Abstract

Degradation and disintegration of the nickel base cermet anode is a serious problem in direct utilization of hydrocarbon fuels, especially for liquid fuels such as kerosene. Cell operation test was carried out for the SOFC with nickel – scandia stabilized zirconia (Ni-ScSZ) cermet anode by direct feeding of several liquid hydrocarbons at 1073 K at S/C = 2.0. For n-dodecane (C12H26) fuel, hydrogen produced by reforming reaction on the anode was mainly used for electrochemical oxidation reaction. In contrast, for desulfurized kerosene test, cell operation was only possible by lower current density. Furthermore, noticeable nickel particles growth occurred. This nickel sintering should be enhanced by remaining minor impurities, including sulfur, in the desulfurized kerosene. From the thermodynamic consideration, Ni-S eutectics can be stably formed under some SOFC operation conditions with 100 ppm of sulfur. Carbon deposition was observed on the nickel surface for both Ni-yttria stabilized zirconia (YSZ) and Ni-ScSZ systems, but was noticeably suppressed for Ni-gadolinia doped ceria (GDC) system.