Molecular speciation of sulfur in solid oxide fuel cell anodes with X-ray absorption spectroscopy

Two sets of solid oxide fuel cell (SOFC) electrode assemblies from different manufacturers were run under different operating conditions with different sulfur exposure, and then subjected to X-ray absorption spectroscopy (XAS) at the sulfur K (1s) edge. Within the detection limits of the spectrometer, pristine fuel electrodes (anodes) show no traces of sulfur. The anodes operated with sulfur-containing natural gas and H2S doped natural gas show spectra rich in sulfur structures. Two other electrodes run with sulfur-containing natural gas, one with a sulfur filter and the other without, show an XAS spectrum with a very broad peak, covering the entire sulfur absorption range, and thus not allowing for identification of specific sulfur signatures. These appear to be the first ever reported sulfur XAS data on SOFC anodes, and the XAS technique shows promise to resolve some hitherto unsolved issues on sulfur poisoning of SOFC, particularly regarding the molecular speciation of the sulfur components.