Innovative progress of thermal ammonia synthesis under mild conditions.

Ammonia is considered a clean energy carrier because of its high hydrogen content, ease of liquefaction, and low carbon emissions. It is mostly manufactured by the Haber–Bosch process. It is critical to the advancement of society and the welfare of people. However, because of the high temperatures and high pressures involved in this process—which uses iron catalysts and fossil fuels to produce hydrogen—it produces greenhouse gasses and requires a lot of energy. Although they struggle with high catalyst prices and low production rates, researchers have looked into alternative ammonia synthesis methods like electrochemical and photochemical ways to overcome this. In order to enable synthesis at lower temperatures and pressures, current efforts are concentrated on creating novel catalysts that will lower reaction conditions. Recent developments in heterogeneous catalysts, including oxides, metal hydrides, oxyhydrides, and electrides, for thermal ammonia synthesis are highlighted in this review. Due to their distinct surface characteristics or electronic structures, these materials have the ability to reduce catalyst poisoning and increase activity while facilitating the breaking of N N bonds and the storage and release of hydrogen. In order to support the development of effective catalysts for a more sustainable future, we investigate variables influencing catalyst performance and reaction processes. Our goal is to provide guidance for future catalyst design and thermal ammonia synthesis methods. [Display omitted] • A review of recent advances in thermocatalytic ammonia synthesis is discussed. • A detailed classification of heterogeneous catalyst types is presented. • The reaction mechanism of ammonia synthesis over catalysts is analyzed. • The relationship between catalyst activity and structure is explained. • Design ideas for functional support materials are provided. [ABSTRACT FROM AUTHOR]