New High-Selectivity Hydrogenation Catalysts Prepared from Bimetallic Acetate Complexes

The catalytic properties of new Pd-Zn/Al2O3 catalysts in selective acetylene hydrogenation in an acetylene-ethylene mixture at 30-120 degrees C and atmospheric pressure are reported. The catalysts prepared from the bimetallic complex Pd-Zn(OOCMe)(4)(OH2) are much more selective than the catalysts prepared by simultaneously supporting the homonuclear complexes Pd-3(OOCMe)(6) and Zn(OOCMe)(2) center dot 2H(2)O. It is demonstrated by diffuse reflectance IR spectroscopy of adsorbed CO that the heat treatment of the supported bimetallic complex at 250 degrees C in flowing H-2 yields a Pd-Zn alloy on the surface. It is this alloy that ensures the high selectivity of the Pd-Zn/Al2O3 catalysts.