Mitigation of carbon deposits formation in intermediate temperature solid oxide fuel cells fed with dry methane by anode doping with barium

The effect of barium doping on a fuel cell anode consisting of a Ni0.53Cu0.47 alloy and gadolinia doped ceria cermet(50:50 wt.) was investigated in an intermediate temperature solid oxide fuel cell (IT-SOFC) fed with dry methane. IT-SOFCs containing the same cathode-electrolyte configuration but equipped with different anodes were compared in terms of performance, steady state operation, and formation of carbon deposits on the anode surface. After proper cell conditioning, similar maximum power densities of 284 mW cm(-2) and 310 mW cm(-2) were obtained in dry methane fuel at 750 degrees C for the anodic compositions with and without barium, respectively. The anode containing barium did not show significant carbon deposits after a 200 h time-study in dry methane whereas the anode without barium showed the presence of carbon deposits as evidenced by X-ray diffraction (XRD). Both anode formulations showed carbon deposits when exposed to dry CH4 in ex-situ experiments. The electrochemical profile recorded during the time-study was different in the two systems. In the absence of barium, a slow and progressive increase in performance as a function of time was achieved. On the contrary, the Ba-doped anode achieved optimum performance in a short time. It is determined that the presence of barium reduces carbon deposition under fuel cell conditions and influences the electrochemical behaviour. (C) 2009 Elsevier B.V. All rights reserved.