Unique bimetallic nickel—chromium and nickel—molybdenum catalysts for hydrogenation in the liquid phase

A series of bimetallic Ni Crx and Ni Mox catalysts were prepared by co-reduction of mixtures of dry iodides of appropriate composition with sodium naphthalene as reducing agent. Observations by transmission electron microscopy (TEM) and local analyses (scanning TEM and energy-dispersive X-ray spectrometry) showed that this procedure gave finely divided homogeneous alloys. The bimetallic powders (50–200A) developed a large BET surface area (100–170 m2g−1). Auger spectra showed that chromium was strongly segregated on the surface in an oxidized state, whereas molybdenum was metallic and no segregation was observed. The turnover number (TON) of cyclohexene hydrogenation did not depend on the nature of the promoter or on the composition (TON=0.28±0.2 s−1). For acetophenone hydrogenation, Ni Crx catalysts exhibited catalytic activity greater than commercial Raney nickel; the initial rate on Ni Cr0.12 was ten times greater. In addition to their great activity, Ni Crx catalysts showed better selectivity, the yield of 1-phenylethanol being as high as 95%. Ni Mox catalysts were approximately as reactive as commercial Raney nickel, with an increase in the rate of hydrogenolysis of the C OH bond.