A Study of Direct-Conversion SOFC with n-Butane at Higher Fuel Utilization

The performance of solid-oxide fuel cells (SOFCs) with Cu-ceria yttria-stabilized zirconia anodes in n -butane at 973 K has been studied as a function of fuel conversion. In order to simulate the local anode environment at high fuel utilization, n -butane was oxidized with in a separate reactor before sending the fuel to a small 0.45 cm 2 cell. When n -butane oxidation was carried out over a ceria catalyst at 973 K, the main oxidation products were and By comparing the performance of the cell in the partially oxidized fuel to the performance of the cell in n -butane diluted in He, it was demonstrated that and have only minimal effect on cell performance other than to dilute the fuel. This dilution of the fuel results in a significant decrease in performance at higher fuel conversions. When n -butane oxidation was carried out over a Pd-ceria catalyst, significant amounts of were generated by steam reforming of hydrocarbons with the steam generated by hydrocarbon oxidation. As a result, the maximum power density generated by the cell increased with fuel conversions up to 30% and remained very high at fuel conversions up to at least 70%. Based on these results, it is suggested that the inclusion of a steam-reforming catalyst within the anode compartment of direct-conversion SOFC should improve their performance at high fuel utilization.