THE HETEROGENEOUS AND HOMOGENEOUS THERMAL DECOMPOSITIONS OF NICKEL CARBONYL

Abstract

The homogeneous thermal decomposition of Ni(CO)4 between 35 °C and 80 °C and over a pressure range of 15 mm to 80 mm of Hg has been distinguished from the heterogeneous reaction occurring on the freshly deposited nickel surface. The activation energy of the homogeneous reaction was found to be 19.1 kcal mole−1 and of the heterogeneous reaction, 14.3 kcal mole−1. The activated complex for the heterogeneous reaction is Ni(CO)4, which is physically adsorbed. The heat of adsorption of Ni(CO)4 is 7.4 kcal mole−1. Carbon monoxide is also adsorbed upon the same sites with a heat of adsorption of 13.3 kcal mole−1, which is much greater than its latent heat of vaporization. The homogeneous reaction may be inhibited by a surface of sodium chloride. Nickel deposited upon rutile behaves in the same way catalytically as nickel deposited upon glass wool.