A Comparison of the Mechanisms and Activation Barriers for Ammonia Synthesis on Metal Nitrides (Ta₃N₅, Mn₆N₅, Fe₃Mo₃N, Co₃Mo₃N)

In this study we perform a comparison of the reaction mechanism and the activation barrier for the rate-determining step in various metal nitrides (Ta3N5, Mn6N5, Fe3Mo3N, Co3Mo3N) for the ammonia synthesis reaction. The reactions are explained with simplified schematics and the energy profiles for the various reaction mechanisms are given in order to screen the catalytic activity of the catalysts for the ammonia synthesis reaction. We find that the catalytic activity ranks in the following order: Co3Mo3N > Fe3Mo3N > Ta3N5 > Mn6N5. We also find that the reaction mechanism proceeds either by a Langmuir–Hinshelwood and an Eley–Rideal/Mars–van Krevelen mechanism. This is an overview of about 10 years of computational research conducted to provide an overview of the progress established in this field of study.