Preparation of palladium supported on MOF-5 and its use as hydrogenation catalyst

A coprecipitation method has been applied successfully for the preparation of 0.5 wt.% palladium supported on MOF-5. The apparent surface area was roughly 900 m(2)/g, the specific micropore volume was 0.3 cm(3)/g, and the powder X-ray diffractograms showed good coincidence with the theoretical pattern of MOF-5. In the hydrogenation of ethyl cinnamate with molecular hydrogen the specific activity of palladium supported on MOF-5 was twice as high as that of a commercial Pd/C catalyst with the same Pd content. It was shown that true heterogeneous catalysis takes place, i.e. leached palladium does not contribute to the reaction. In repeated runs the palladium supported on MOF-5 did not show any loss in activity, but a complete loss of micro pore volume was observed. Thus, it can be assumed that the palladium is not located inside the micropores but probably bonds to the outer surface of the crystals. (C) 2007 Elsevier B.V. All rights reserved.