Experimental influence of operating variables on the performances of MCFCs under SO₂ poisoning

Molten Carbonate Fuel Cells have reached the status of commercialization and are now ready for the challenge of market penetration. Nevertheless, new innovative applications such as the use of non-conventional fuels and their possible implementation in a Carbon Capture and Storage system, have given new importance to research activities. In particular, the gas feedings used in these applications contain impurities that can damage MCFCs and, of these, sulphur compounds seem to be the most harmful, even at low concentrations. The aim of this work is to test the effect of SO₂ on the role of the operating variables governing the electrochemical kinetics of MCFCs, investigate the relationships and advance additional data necessary for the reading of the complex interaction phenomena taking place in these conditions. The current work is therefore not intended to probe into the fundamental electrochemical mechanisms, but more to validate the window of viable operating conditions that can be expected in real applications. In particular, an experimental campaign was performed, feeding 2 ppm of SO₂ to the cathode of MCFC single-cells at different operating temperature and gas partial pressures (H₂, CO₂, O₂), taking into account possible chemical, electrochemical and physical poisoning mechanisms. The experimental tests were performed at the Fuel Cell Research Centre laboratories of KIST (South Korea) and a preliminary theoretical analysis was also proposed to suggest operating strategies.