Structure and catalytic activity of alumina supported platinum-cobalt bimetallic catalysts. 3. Effect of treatment on the interface layer

The structure of the interface between metal and alumina in a series of Pt 1-x Co x /Al 2 O 3 bimetallic samples has been investigated by X-ray photoelectron spectroscopy (XPS) after calcination in oxygen at 770 K with subsequent in situ reduction in hydrogen in H 2 at 770 K. On all calcined samples platinum was found int he Pt(4+) valence state as an oxide species. Subsequent treatment in H 2 at 770 K resulted only in a partial reduction of ionic platinium into the zerovalent state