Transient surface processes of storage and conversion of NOx species on Pt-Me/Al2O3 catalysts (Me = Ba, Ce, Cu)

The transient reactivity and surface phenomena of storage and conversion of NOx species on Pt(1%)-Me/Al2O3 catalysts, where Me = Ba, Ce and Cu, were studied by the RWF (rectangular wavefront) method. The Me component has a relevant influence on the processes of surface storage and transformation. The reduction of NOx by propene in the presence of oxygen is promoted by adding Cu to a Pt/Al2O3 catalyst, while cerium promotes transient conversion of NO in the absence of propene, but inhibits the reduction of NOx in the presence of propene. Copper is suggested to be a promising element to add together with Ba for new NOx storage-reduction catalysts due to its capacity to act both as a storage element and as promoter for NOx reduction.