When copper is not enough: Advantages and drawbacks of using copper in de-NOx reactions over lanthanum manganite perovskite structures.

Using a Cu-doped lanthanum manganite perovskite structure (LaCu 0.5 Mn 0.5 O 3- δ), we show how Pd addition following different synthesis approaches (sol-gel vs. impregnation) allows to overcome the oxidation limitation of Cu in realistic de-NO x reaction mixtures involving NO, CO, O 2 and water. The beneficial interplay of Cu with the oxygen-deficient perovskite resulting from in situ exsolution during humid de-NO x treatments is strongly connected with the metallic Cu state enhancing the N 2 O chemistry. The beneficial catalytic properties of metallic Cu can be preserved by adjustment of the Pd amount, as evidenced by combined in situ X-ray photoelectron spectroscopy and catalytic experiments following the main reactions of the de-NOx reaction network, including water-gas shift reaction and CO oxidation. The concept of impregnation with a noble metal and simultaneous exsolution with Cu yields a reactive Cu(Pd)/perovskite interface and provides a first step towards the economization of the noble metal content at the surface in future works. [Display omitted] • Metallic Cu state enhances N 2 O chemistry upon dry deNOx treatment. • Under humid conditions the Cu remains mainly oxidized. • Effect of the Pd alloying on deNO x reactivity in the presence of H 2 O. • Beneficial combined concept of Cu exsolution and noble metal impreganation. [ABSTRACT FROM AUTHOR]