Methods that fix atmospheric nitrogen to ammonia under mild conditions could offer a more environmentally benign alternative to the Haber–Bosch process. Now, a Ru-loaded electride, [Ca24Al28O64]4+(e−)4, is reported that acts as an efficient electron donor and reversible hydrogen store, and is demonstrated to function as an efficient catalyst for ammonia synthesis.

Ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store

Water adsorption and the wetting of metal surfaces

Novel approaches to efficient ammonia synthesis at an ambient pressure are actively sought out so as to reduce the cost of ammonia production and to allow for compact production facilities. It is accepted that the key is the development of a high-performance catalyst that significantly enhances dissociation of the nitrogen-nitrogen triple bond, which is generally considered a rate-determining step. Here we examine kinetics of nitrogen and hydrogen isotope exchange and hydrogen adsorption/desorption reactions for a recently discovered efficient catalyst for ammonia synthesis--ruthenium-loaded 12CaO·7Al2O3 electride (Ru/C12A7:e(-))--and find that the rate controlling step of ammonia synthesis over Ru/C12A7:e(-) is not dissociation of the nitrogen-nitrogen triple bond but the subsequent formation of N-Hn species. A mechanism of ammonia synthesis involving reversible storage and release of hydrogen atoms on the Ru/C12A7:e(-) surface is proposed on the basis of observed hydrogen absorption/desorption kinetics.

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Electride support boosts nitrogen dissociation over ruthenium catalyst and shifts the bottleneck in ammonia synthesis

Alkali-metal-affected adsorption of molecules on metal surfaces

Electron-stimulated desorption: Principles and applications

Adsorption and thermal decomposition of ammonia on a Ni(110) surface: Isolation and identification of adsorbed NH2 and NH

A vibrational spectroscopy study on the interaction of N2 with clean and K-promoted Fe(111) surfaces: π-bonded dinitrogen as precursor for dissociation

I.C. Bassignana

Papers

Adsorption and thermal decomposition of ammonia on a Ni(110) surface: Isolation and identification of adsorbed NH2 and NH

A vibrational spectroscopy study on the interaction of N2 with clean and K-promoted Fe(111) surfaces: π-bonded dinitrogen as precursor for dissociation

A TDS and HREELS study of CO adsorbed on a potassium promoted Fe(111) surface

Coadsorption of oxygen and water at Ni(110) surfaces