Supported Wilkinson's complex used as a high active hydrogenation catalyst

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.