Effects of SO2 poisoning and regeneration on spinel containing CH4 oxidation catalysts

Methane oxidation under periodic conditions and the oxygen storage capacity of a bilayer Pt/Pd/Al2O3 over a Mn0.5Fe2.5O4 spinel catalyst were studied before and after SO2 exposure, and after simulated regeneration conditions. Prior to sulfur exposure, improvement in CH4 oxidation conversion under periodic conditions compared to steady-state conditions was observed. After sulfur exposure at 100 °C, there was a loss in CH4 oxidation performance and a loss of oxygen storage capacity of the spinel material. The extent of regeneration from sulfur poisoning depends on the ability to induce the decomposition of sulfate species, and while all regeneration methods tested in this study did improve CH4 conversion, regeneration methods under periodic conditions induced greater sulfur species desorption from the catalyst surface leading to improved CH4 conversion. Key regeneration parameters – temperature, feed composition, modulation amplitude and frequency – were optimized to induce S species decomposition and correlated to CH4 oxidation activity recovery.