Investigation of Cs–Cu/ZrO2 systems for simultaneous NOx reduction and carbonaceous particles oxidation

The effect of Cs and Cu contents in Cs–Cu/ZrO2 catalysts has been studied in the simultaneous abatement of NOx and carbon black (CB), used as a model of soot. Cu/ZrO2 and Cs–Cu/ZrO2 catalysts with a low Cs content are moderately active but show a beneficial role of NOx in CB elimination. Cs–Cu/ZrO2 catalysts with high amount of cesium are the more active systems towards both CB oxidation and NOx reduction. The increase in the amount of Cs leads to the formation of a higher proportion of CuO crystallites which are active for CB oxidation. Cesium in Cs–Cu/ZrO2 also acts as a promoter favouring the contact between reactants: on the first hand it increases the exchange surface between CB and the catalyst surface and on the other hand, it enhances the NOx adsorption capacity of Cs–Cu/ZrO2 and the further NOx reduction.