Supported RuxIr1-xO2 Mixed Oxides Catalysts for Propane Combustion: Resistance Against Water Poisoning

Abstract

Mixed oxide catalysts RuxIr1-xO2 with varying composition x (x=0, 0.25, 0.5, 0.75, 1.0) supported on CeO2, γ-Al2O3 or ZrO2 are successfully prepared and tested in the catalytic propane combustion in terms of activity and stability. Pure IrO2 reveals a significantly lower activity than RuxIr1-xO2 with x≥0.25. For low conversion, pure RuO2 on CeO2 turns out to be the most active catalyst, while at higher conversion, Ru0.75Ir0.25O2 on ZrO2 is found to be more active than RuO2, pointing towards synergism of Ru and Ir sites. Long-term stability and also the resistance against water poisoning are highest for ZrO2-supported catalysts. The higher the Ir concentration in the active component RuxIr1-xO2 the more susceptible is the catalyst to water poisoning. Water poisoning is shown to be reversible, consistent with a blocking of catalytically active sites by water adsorption.