XPS Evidence of Alloying in Pd/ZnO Catalysts

The main objective of the present note is to provide XPS evidence for alloying taking place during the reduction of a Pd/ZnO catalyst. For this purpose a Pd/ZnO catalyst was reduced at two different temperatures: first at 420 K, which is high enough to reduce Pd completely but at which the formation of the Pd hydride phase as well as that of a Pd-Zn alloy can be avoided; second, at 880 K in order to make the alloy formation complete and to have crystallites large enough for XRD detection. For the sake of comparison pure ZnO and the Pd/ZnO catalyst in [open quotes]as-prepared[close quotes] states were also investigated by XPS. 22 refs., 2 figs., 1 tab.