Effect of sulfur in catalytic partial oxidation of methane over Rh–Ce coated foam monoliths

A potentially important technology to convert natural gas to syngas is catalytic partial oxidation (CPO) over precious metal catalysts. However, natural gas contains small amounts of sulfur compounds which can poison the catalyst. It is therefore of interest to investigate the effect of sulfur on the performance of CPO. In this work CPO experiments have been performed over Rh–Ce coated foam monoliths with CH3SH added to methane. The result of ppm levels of sulfur is a large (∼200°C) temperature increase, along with lower methane conversion and lower hydrogen selectivity. A doubling of the sulfur level from 14 to 28 ppm does not result in significant changes, showing that the effect saturates at a few ppm. The poisoning effect has been investigated by analyzing both effluent and spatially resolved data and is shown to be due to severe hindrance of steam reforming by adsorbed sulfur.