Catalytic Activity of Alumina Supported Platinum-Nickel Alloys

Well defined alumina-supported Pt-Ni alloys have been prepared. X-ray diffraction, X-ray small angle scattering and magnetism show that they are homogeneous in the bulk. Little segregation of the nickel on the surface of alloys is detected by XPS. A strong maximum of the turnover for the isomerisation of neopentane to isopentane, is observed in the composition range (Pt 80, 90 -Ni 20,10 ). Similarly, for the hydrogenolysis of neopentane, the rate is increased by two order of magnitude for the composition Ni 90 Pt 10 . This synergetic effect is attributed to modifications of the electronic properties of both metals for the two critical compositions. This conclusion is supported by studies of the platinum L III edge which undergoes deep modifications.