Selective Catalytic Reduction of NO by Propane over Bifunctional Catalyst of Transition Metal Al 2 O 3 /H-USY in Excess Oxygen

Selective catalytic reduction of NO with propane in the excess of oxygen was studied on physical mixtures of transition metal/Al₂O₃ and H-USY zeolite. Experimental results on all the catalysts studied show that the NO conversion to N₂ over the physical mixture catalysts was found to be higher than that expected if these components acted independently under the condition of keeping gas hourly space velocity constant. Such synergistic effect of metal oxide and proton acid was discussed, and possible reason was proposed. High temperature makes metal ion easy to migrate into zeolitic channels, and consequently become the active site for reduction of NO with C₃H₈. Furthermore, it is possible that Br⊘sted acid on H-USY zeolite is the most important driving power. Moreover, the bifunctional interaction between metal ions and proton sites was also proved to decrease N₂O yield and remarkably increase the selectivity of propane reducing NO to the C₃H₈ + NO + O₂ system.