Role of alkali promoter in ammonia synthesis over ruthenium catalysts-Effect on reaction mechanism

•Works on Ru catalysts with alkali promoters for NH3 synthesis are reviewed.•The concept of electron donation and nature of the adsorbed species are examined.•Kinetic analysis over Ru catalysts are performed with relating to the mechanism.•Mechanism of ammonia synthesis over ruthenium catalysts is proposed.

Previous research on ammonia synthesis over ruthenium catalysts is reviewed with a particular emphasis on the action of alkali promoters. The concept of electron donation and the nature of the adsorbed species are examined, and their relationship with electronic and structural factors related to dinitrogen activation is considered. A kinetic analysis is performed and the reaction mechanism involved in ammonia synthesis over ruthenium catalysts is investigated.

Graphical abstractDownload high-res image (146KB)