Reforming of methane over noble metal catalysts: Catalyst deactivation induced by thiophene

This work is focused on the performance of rhodium and ruthenium catalysts for the low temperature wet catalytic partial oxidation (LTCPO) of methane in sulphur-free conditions and also at different sulphur concentrations. Catalysts characterization was conducted by X-ray diffraction (XRD), BET surface area measurements, X-ray photoelectron spectroscopy (XPS), O2 chemisorption by TGA, and transmission electron microscopy (TEM). All of the catalysts showed a high activity and selectivity towards hydrogen if sulphur-free reaction conditions were applied. The presence of small amounts of thiophene (10 ppm) in the feed decreased the activity for all the catalysts. However, at this concentration one ruthenium catalyst showed a high sulphur tolerance. For all the rhodium catalysts a strong deactivation and a higher CO2 selectivity was observed at 10 ppm of thiophene. Operation with 400 ppm of thiophene in the feed resulted in a low activity for both Rh and Ru catalysts, and only a small amount of CO2 was produced.