NEW APPROACH TO SKELETAL NICKEL-CATALYSTS - CATALYTIC PROPERTIES OF THE NICKEL-CHROMIUM SYSTEM

A series of chromium doped Raney nickel was prepared from Ni2-xCrxAl3 precursor alloy (x=0.07 and 0.11) which were either crystalline or microcrystalline. These catalysts were studied during the hydrogenation of carbonyl or ethylenic groups (acetophenone, cyclohexene, crotonaldehyde, and 1,2,3,6-tetrahydrobenzaldehyde). Modification of the activity depended principally on the amount of chromium present and, to a minor degree, on the homogeneity or on the state of crystallization of the starting alloy. The correlation obtained between the catalytic properties and the amount of CrIII on the surface allowed us to propose a promoting effect for specific amounts of chromium oxide. Residual metallic aluminum would seem to play an inhibiting role, but this has yet to be confirmed.