Kinetic isotope effects in the catalytic synthesis of ammonia

Abstract

A reanalysis of the data of Ozaki, Taylor, and Boudart on the H D isotope effect in ammonia synthesis does not support their conclusion that the surface is covered chiefly by NH radicals. The evidence is shown to be more consistent with the presence of N atoms on the surface combined with the action of a H D kinetic isotope effect in the dissociative adsorption of nitrogen. The magnitude of this enhancement factor, about 3.8 at room temperature, is that to be expected for the participation of an adsorbed H atom in the slow step of the dissociative chemisorption of nitrogen molecules.