CHARACTERIZATION OF A POLYMER-BOUND PALLADIUM ACETATE CATALYST AND STUDIES ON THE SELECTIVE HYDROGENATION OF DIENES AND ALKYNES

Palladium(II) acetate has been anchored onto a copolymer support conta ining pyridyl and carboxyl groups. XPS studies showed the Pd 3d bindin g energies for the recovered catalyst to be less by 1 eV after being u sed in hydrogenation studies. However, x-ray studies and a chemical te st based on KCN treatment failed to reveal any palladium oxide or pall adium metal formation in the recovered catalyst. It is presumed that a n acetate ligand is lost during hydrogenation, which could be the reas on for the lowering of the palladium 3d binding energies in the recove red catalyst. Results of investigations of the hydrogenation of olefin s and selectivity of the catalyst toward the hydrogenation of dienes a nd alkynes are presented. The loss of palladium due to leaching under the reaction conditions employed was found to be very low (< 10% cycle ).