Experimental Investigation of Naphthalene Induced Degradation of Reversible Solid Oxide Cells Operated on Bio-Syngas

Abstract

The influence of the operational conditions and the electrode material on the degradation induced by the model tar naphthalene on 10 × 10 cm2 fuel-electrode supported solid oxide cells operated on artificial bio-syngas under internal reforming conditions is experimentally investigated. Two different fuel electrodes are investigated based on yttrium-stabilized zirconia (YSZ) and gadolinium-doped ceria (GDC). A parameter study of the operational temperature and the operation mode (fuel cell or electrolysis mode) is conducted with the YSZ-based fuel electrode to quantify the effects on the cell degradation. The fuel off-gas composition and electrochemical impedance spectra are used to characterize the cell prior to the experiment and monitor its performance during the poisoning process. The influence of the tar on the Ni-YSZ electrode cell is investigated for an operation at 700 °C and 800 °C in fuel cell mode, and an operation at 700 °C in electrolysis mode. The experiment at 700 °C is repeated with the Ni-GDC electrode cell. At the increased operational temperature, the Ni-YSZ cell is more robust but carbon depositions occur. The voltage degradation during electrolysis operation increases significantly compared to fuel cell operation. The Ni-GDC electrode does not show an increased robustness compared to the Ni-YSZ electrode.