Nitrides, Hydrides and Carbides as Alternative Heterogeneous Catalysts for Ammonia Synthesis: A Brief Overview

Abstract

There has been recent interest in the potential of nitrides, hydrides and carbides as novel heterogeneous catalysts for the production of ammonia in a sustainable manner on a local scale. It has been proposed that some of these materials can produce ammonia via Mars-van Krevelen based mechanistic pathways. Generally, for metal-based heterogeneous catalysts, dissociative nitrogen activation is believed to be the rate determining step in ammonia synthesis. However, associative pathways, which are more akin to enzymatic nitrogen activation, are being increasingly invoked in the literature. Such pathways may provide an opportunity for the development of novel catalysts that operate under milder reaction conditions. This brief overview provides a summary of some of the recent developments in relation to nitrides, carbides and hydrides as applied to ammonia synthesis.