NO reduction by propene or CO over alkali-promoted Pd/YSZ catalysts

The catalytic activity and selectivity of Pd dispersed on 8 mol% yttria stabilized zirconia (YSZ) support for the reduction of NO by propene or CO is strongly promoted by alkalis in a wide temperature range 200-500 °C. Rate increases by up to one order of magnitude are achievable, accompanied with significant improvement in N2-selectivity for the alkali promoted catalysts. The promoting effect of alkalis on both the activity and selectivity can be understood in terms of the effect of alkali promoter on the relative adsorption strengths of reactant species. These achievements could be very useful for the formulation of modern lower cost automotive catalytic converters, capable of controlling automotive emissions more efficiently.