Sulphur tolerance of Au-modified Ni/GDC during catalytic methane steam reforming
Small traces of H2S in natural gas can cause significant degradation in the performance of solid-oxide fuel cells (SOFCs) operating under direct internal reforming conditions. This study investigates the sulphur resistance of Au-doped Ni/GDC (gadolinia-doped ceria) powders to assess their potential use as anode materials during catalytic methane steam reforming in presence of H2S. It was found that both the presence of Au and annealing at high temperatures have promoting effects on the stability of the catalytic performances. This was attributed to limited sulphur diffusion from the GDC surface to the catalytically active Ni sites. Moreover, H2S chemisorption experiments indicated that Au can limit the formation of strongly bonded sulphur compounds due the formation of Au–Ni alloys, thus demonstrating that Au-modified Ni/GDC is a promising anode material for SOFCs using natural gas as a fuel.