Supporting Wilkinson's complex on gamma-Al2O3 rendered a high active cataly
st for cyclohexene to cyclohexane hydrogenation. The activity was higher th
an that of the same complex unsupported, in the presence or absence of a S-
containing poison (tetrahydrothiophene). XPS results suggested that, after
poisoning, there was an insertion of a sulfur atom into the rhodium coordin
ation sphere. Comparison of Wilkinson's complex with other palladium and ni
ckel complexes was also made. The Wilkinson's complex proved to be more act
ive and sulfur resistant than the Pd and Ni complexes in both homogeneous a
nd heterogeneous conditions. For the Pd and Ni complexes there was a change
in the coordination sphere after poisoning, as shown by the XPS results. (
C) 1999 Elsevier Science B.V. All rights reserved.