Function of molybdenum catalyst in formation of ammonia under ambient conditions
Advance in development of next-generation nitrogen fixation system
Graduate School of Engineering / Faculty of Engineering
Nitrogen is an important element contained in nucleic acids, amino acids, proteins and essential for the maintenance of life, and used in pharmaceutical products, artificial fibers and fertilizers. Most nitrogen is used in the form of ammonia industrially synthesized by the Haber-Bosch process from nitrogen gas and hydrogen gas in the presence of an iron-based catalyst. However, because this process is carried out under high temperature and high pressure conditions (400-600 centigrade, 200-400 atmospheres), a method for synthesizing ammonia from nitrogen under milder conditions has long been desired.
In 2010, the research group of Associate Professor Yoshiaki Nishibayasi of the University of Tokyo’s Graduate School of Engineering, Institute of Engineering Innovation, developed a method for synthesis of ammonia using a dinitrogen-bridged dimolybdenum complex as catalyst and under very mild conditions of room temperature and at atmospheric pressure. However, the reaction mechanism of this new method was unclear.
In this latest research, the University of Tokyo research group, working with researchers from Kyushu University, successfully developed and isolated the intermediate material that holds the key of the new method of ammonia synthesis and elucidated the reaction mechanism. In the ammonia synthesis process, electron transfer was taking place between two molybdenum atoms linked by a nitrogen molecule.
This result is an important step forward in the development of next-generation methods of nitrogen fixation to replace the current Haber-Bosch process for ammonia synthesis, and may lead to the development of future environmentally-friendly means of ammonia synthesis and the achievement of significant cost-reductions.
This research has been published in the online early edition of the British scientific journal Nature Communications on April 28, 2014.
Hiromasa Tanaka, Kazuya Arashiba, Shogo Kuriyama, Akira Sasada, Kazunari Nakajima, Kazunari Yoshizawa, Yoshiaki Nishibayashi,
“Unique Behaviour of Dinitrogen-Bridged Dimolybdenum Complexes Bearing Pincer Ligand towards Catalytic Formation of Ammonia”,
Nature Communications, vol. 5, 3737, 2014, doi: 10.1038/ncomms4737