SELECTIVE CATALYTIC REDUCTION OF NO OVER PTMO CATALYSTS WITH ALKALINEOR ALKALINE-EARTH METAL UNDER LEAN STATIC CONDITIONS

The selective reduction of NO on various PtMoX-catalysts (X: Li, Na, K , Mg and Ca) loaded on metal oxides such as SiO2, Al2O3, TiO2, ZSM-5 a nd silicallite was studied in an oxygen-rich synthetic mixture simulat ed exhaust from an automotive lean-burn engine, and compared with that on PtMo/SiO2, PtNa/SiO2, and Pt/SiO2 catalysts. The temperature windo w for the selective reduction of NOx on the PtMoLi-, PtMoNa- and PtMoK -catalysts was found to be remarkably wider and to shift to a higher t emperature than that on the other catalysts under lean static conditio ns.