Plasma Catalysis as an Alternative Route for Ammonia Production: Status, Mechanisms, and Prospects for Progress

Plasma catalysis has drawn attention from the plasma and chemical engineering communities in the past few decades as a possible alternative to the long-established Haber Bosch process for ammonia production. The highly reactive electrons, ions, atoms, and radicals in the plasma significantly enhance the chemical kinetics, allowing ammonia to be produced at room temperature and atmospheric pressure. However, despite the promise of plasma catalysis, its performance is still well short of that of the Haber Bosch process. This is at least in part due to the lack of understanding of the complex mechanisms underlying the plasma catalyst interactions. Gaining such an understanding is a prerequisite for exploiting the potential of plasma catalysis for ammonia production. In this perspective, we discuss possible benefits and synergies of the combination of plasma and catalyst. The different regimes of plasma discharges and plasma reactor configurations are introduced and their characteristics in ammonia synthesis are compared. Based on detailed kinetic modeling work, practical ideas and suggestions to improve the energy efficiency and yield of ammonia production are presented, setting future research directions in plasma catalysis for efficient ammonia production.