The Impact of Toluene on the Performance of Anode-Supported Ni-YSZ SOFC Operated on Hydrogen and Biosyngas

This paper presents an experimental study of the impact of toluene on the performance of anode-supported (AS) Ni-YSZ SOFC operating at ~800 °C, 0.25 A/cm² fed with H₂ and reformed biosyngas. Toluene was added to the fuel stream and its concentration increased stepwise from tens to thousands of ppm. Each poisoning test was followed by a recovery step (no toluene in the fuel stream) for the duration of 25 hours. The main goal of this work is to define a concentration threshold of toluene as a model tar compound in the fuel stream and later to identify the degradation mechanism caused by this tar compound. Polarization behavior, current-voltage and electrochemical impedance spectroscopy (EIS) were analyzed to evaluate the cell performance. A linear degradation is observed at concentrations above 1000 ppmv for the cell which was fed with pure H₂ (cf Figure) The degradation was due to local C(s) deposition. In contrast, toluene even up to 3500 ppm did not cause a severe degradation when the cell was fed with reformed biosyngas.