The catalytic fission of the carbon-nitrogen bond I. The reactions of methylamine and hydrogen on evaporated metal films

Abstract

A study of the catalytic fission of the C—N bond was begun by following the reactions of methylamine in the presence of hydrogen by means of a mass spectrometer. On evaporated films of nickel, iron, palladium, platinum and tungsten, the expected products, ammonia and methane, were accompanied by the formation of higher amines and carbon was also lost to the catalyst. The nature of this carbon association with the catalyst was further examined by X-ray diffraction analysis. On a given catalyst the activation energies for methylamine decomposition and for formation of the various products, including carbon-loss, were closely similar. The common, rate-determining step, thus indicated, can be identified with the fission of the C—N bond. Surface mechanisms, in agreement with the observed reactions, are postulated in terms of skeletal units, C1N1, C2N1, etc., of unspecified state of hydrogenation. Differential equations developed on the basis of these postulates yielded a set of theoretical curves in agreement with the experimental points from a test experiment on a palladium catalyst. Various aspects of the variation in catalytic activity between the metals used are also discussed.