Non-thermal plasma-assisted ammonia production: A review

As a hydrogen carrier molecule, ammonia is a clean, sustainable fuel source and efficient energy storage medium that has been extensively investigated. Currently, the industrial method for ammonia synthesis is the Haber-Bosch process, which requires large amounts of fossil fuels, high temperature and pressure, and significant capital investment. Plasma technology is a promising alternative method for ammonia synthesis, and non-thermal plasma has been widely used due to the high selectivity in chemical reactions, mild reaction conditions, and no need for quenching. In this review, we present an extensive and in-depth examination of the advancements in non-thermal plasma-assisted ammonia synthesis under conditions characterized by low temperature and low pressure. It encompasses various aspects, including plasma pretreatment of ammonia synthesis catalysts and plasma-activated air-assisted ammonia synthesis, as well as the analysis of the influence of different hydrogen sources and plasma sources. Subsequently, an evaluation framework for non-thermal plasma-assisted ammonia synthesis is proposed, followed by a comparative analysis of different ammonia synthesis methods, elucidating the auxiliary role of non-thermal plasma in the ammonia synthesis process. Finally, we conclude with an outlook and recommendations for non-thermal plasma-assisted ammonia production.