Promoting effect of Rh on the activity and stability of Pt-based methane combustion catalyst in microreactors

For the combustion of methane, a partial replacement of platinum by rhodium leads to a significantly improved light-off behavior of the corresponding mixed Pt-Rh/g-Al2O3 catalysts compared to a catalyst containing only Pt supported on g-Al2O3. For all Pt-Rh/g-Al2O3 catalysts, mixed Ptsingle bondRh crystals of low particle size were found. At 600 °C, the stability of catalysts, was found to increase with increasing rhodium content. The crystal size was determined by HR-TEM for spent catalyst samples after 40 h stability test. The samples containing higher amounts of rhodium showed smaller crystal size suggesting this as the origin of the increased catalyst stability.