This Review summarizes the different technical routes for plasma-assisted ammonia synthesis in recent years and the key points: mixed-phase, synergistic processes and mechanisms. The advantages and existing problems of the different routes are also discussed. Finally, we make an outlook on the future direction of plasma-assisted ammonia synthesis.

Abstract

Ammonia plays a crucial role in industry and agriculture worldwide, but traditional industrial ammonia production methods are energy-intensive and negatively impact the environment. Ammonia synthesis using low-temperature plasma technology has gained traction in the pursuit of environment-benign and cost-effective methods for producing green ammonia. This Review discusses the recent advances in low-temperature plasma-assisted ammonia synthesis, focusing on three main routes: N₂+H₂ plasma-only, N₂+H₂O plasma-only, and plasma coupled with other technologies. The reaction pathways involved in the plasma-assisted ammonia synthesis, as well as the process parameters, including the optimum catalyst types and discharge schemes, are examined. Building upon the current research status, the challenges and research opportunities in the plasma-assisted ammonia synthesis processes are outlined. The article concludes with the outlook for the future development of the plasma-assisted ammonia synthesis technology in real-life industrial applications.