The hydrogenation of benzene over supported platinum, palladium and nickel catalysts

The activity for the hydrogenation of benzene has been studied for supported platinum, palladium and nickel as a function of metal particle size and carrier. Metal crystallite sizes varied between 10 and 400 Å and silica, alumina, silica‐alumina and silica‐magnesia were used as supports. It has been found that the activity per exposed metal atom is independent of the metal crystallite size or of the support used. The hydrogenation activities per exposed metal atom at a temperature of 100°C and a hydrogen pressure of 5.6 atm are ranked as follows: kpt: kNi: kPd = 18:7:1. It is further shown that the activation energies observed experimentally for the various catalysts at a given set of conditions are predicted with a high degree of accuracy with the aid of the theory of absolute reaction rates, based on a resonable estimate of the number of exposed metal atoms per hydrogenation site.