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

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 diss...

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Bibliographic Details
Published in:Nature communications 2015-03, Vol.6 (1), p.6731-6731, Article 6731
Main Authors: Kitano, Masaaki, Kanbara, Shinji, Inoue, Yasunori, Kuganathan, Navaratnarajah, Sushko, Peter V., Yokoyama, Toshiharu, Hara, Michikazu, Hosono, Hideo
Format: Article
Language:English
Subjects:
639/638/263/406/77
639/638/549
Ammonia
Catalysis
Catalysts
Chemical bonds
Chemical synthesis
Desorption
Humanities and Social Sciences
Hydrogen
Hydrogen atoms
Hydrogen isotopes
Hydrogen storage
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Kinetics
multidisciplinary
Nitrogen
Pressure
Reaction kinetics
Ruthenium
Science
Science (multidisciplinary)
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Summary: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·7Al 2 O 3 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–H n 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. Development of catalysts that enhance dissociation of the nitrogen–nitrogen triple bond will reduce costs of ammonia production. Here, the authors study ammonia synthesis over a ruthenium loaded electride catalyst and show that the rate-determining step is shifted to nitrogen–hydrogen bond formation.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms7731