Isomerization of alkanes on epitaxially oriented (111) Pd–Cu and Pd–Ag alloy films

The reactions of neopentane and n-butane in the presence of an excess of dihydrogen have been studied on films of Pd–Cu and Pd–Ag evaporated onto mica. The characterization of films showed that they were predominantly (111) oriented. The catalytic activity for isomerization of neopentane and n-butane was higher for ca. 10 at% Cu than for pure Pd, resembling the catalytic behaviour of Pd–Au(111) films. This does not, however, confirm the existence of the ligand effect in alkane isomerization over Pd–IB metal alloys. The catalytic activity of Pd–Ag(111) alloys decreases with increasing silver content, but on the basis of the inferred surface composition of these alloys this agrees with the conclusion drawn for the Pd–Cu system, i.e. the possible absence of the ligand effect.