Methane internal reforming in solid oxide fuel cells with anode off-gas recirculation

In this study, methane steam and dry reforming have been investigated, from the perspective of methane conversion, hydrogen yield and the formation of solid carbon. Different ratios between methane, steam and carbon dioxide were used in order to simulate the methane internal reforming in a Solid Oxide Fuel Cell (SOFC) with anode off-gas recirculation. Thermodynamic equilibrium modelling was first employed to determine the concentrations of each gas in the equilibrium state. Crushed anode substrate material of a commercial SOFC half-cell was used as catalyst in the practical experiments. The modelling results showed that at 750 °C (1023 K), above 90% of methane conversion was found in all cases and carbon was formed when the oxygen to carbon (O/C) ratio was lower than 1.2. The experimental results showed that poor methane conversion rates (around 20%) were found within the steam reforming. The performance was highly affected by the total fuel flow rate and carbon formation could still be found in cases for the O/C ratio above 1.5.