Total combustion of propane in a catalytic microchannel combustor

The combustion of propane was studied on wash-coated noble metal supported catalysts in a catalytic microchannel combustor under different reaction conditions in the temperature range 250–750 °C. Pt-based catalyst was found to be more active than Pd and Rh for the same metal loading on identical support. Pt-based catalyst showed deterioration in conversion in excess of air owing to inhibition effects of the surplus oxygen. Additionally, minor undesired selectivity towards carbon monoxide was found under stoichiometric feed ratio over Pt/Al2O3 catalyst. Palladium and rhodium catalysts were less active but exclusively selective towards carbon dioxide at stoichiometric oxygen to propane ratio and deactivation was found in a short time. Catalytic activity of Pt/Al2O3 catalyst was observed to be significantly enhanced by the transition metal oxide additives, namely tungsten and molybdenum, and the promoting role of metal oxides is tentatively discussed. At 325 °C reaction temperature and at a space velocity of 300 NL/(h gcat) full propane conversion could be achieved over Pt/MoOx/Al2O3 catalyst in the slight excess of oxygen. Platinum catalyst promoted by MoOx and WOx proved to be stable for over 1000 h without any detectable degradation in performance for low and high temperature applications, respectively.