Role of hydride ion within Ru/LaScSi and Ru/CeTiGe catalysts for NH3 synthesis: A combination of DFT and experimental nitrogen isotopic exchange studies

The design of catalysts active for ammonia synthesis under mild conditions of temperature and pressure is a new grail for its production process based on green hydrogen and intermittent renewable energy sources. Ru/LaScSi and Ru/CeTiGe are investigated with an approach combining DFT calculations and 15N/14N homomolecular exchange experiments. Ru/LaScSi is the most active of both catalysts. It has electride-like properties which are enhanced when partially hydrogenated leading to higher activity in nitrogen equilibration reaction. Ru/CeTiGe, relatively active despite the absence of electride-like character, is proposed to produce NH3 following the associative mechanism with the assistance of absorbed H.