Review on catalytic roles of rare earth elements in ammonia synthesis: Development and perspective

Abstract Ammonia (NH3) is mainly produced via the Haber–Bosch process. It was discovered that the performance of a wide variety of catalysts in NH3 synthesis could be considerably enhanced by the addition of rare earth elements (REEs). As a result, catalysts promoted by REEs, especially the Ru-based ones have been extensively investigated. In this review, we summarize the progress of utilizing REEs for ammonia synthesis and outline the prospects of using them in the design and development of highly efficient and stable catalysts for ammonia synthesis.