Ammonia as an energy carrier

Ping Chen

Dalian Institute of Chemical Physics, Chinese Academy of Sciences 

Abstract: With a high hydrogen content (17.6 wt.%), high energy density (4 kWh kg-1), facile storage and transportation, NH3 has been regarded as a potential energy carrier. The key issue for NH3 synthesis and decomposition is the development of non-noble metal based, highly active and stable catalysts that can be operated under mild condition. This would require a catalyst to have strong activation (small Eact) to N2 but relatively weak binding (small adsorption energy DE) to -NHx (x = 0-3) intermediates. Unfortunately, such a scenario can hardly be attained in transition metal (TM) catalyzed processes.

With the understanding of interactions of hydrides/imides of alkali and alkaline earth metals (AM for short) with 3d metals and their nitrides, the catalyst systems, i. e., AMNH-3d transition metals for NH3 decomposition and AMH-3d transition metals for NH3 synthesis, were developed. The unique chemistry among transition metals, alkali/alkaline earth, N and H creates an energy-favorable pathway allowing NH3 synthesis/decomposition under mild conditions, i.e., detectable NH3 formation rate was obtained at 150 °C over the Mn-, Fe- and Co-LiH composite catalysts, respectively.The characterization of intermediate phases and surface clusters of catalysts provides interesting information that helps the elucidation of the step-wise reaction pathway and the interpretation of catalytic mechanism.

Biography: Professor and division head of Hydrogen Energy and Advanced Materials, Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences (China). Chen received BS, MS and PhD degrees in Chemistry in 1991, 1994 and 1997, respectively, from Xiamen University, China. She was a faculty member of Science Faculty, National University of Singapore before she joined DICP in 2008.Her primary research interests include the materials development for hydrogen storage and heterogeneous catalysis. She pioneered the research in the amide-hydride for hydrogen storage and the alkali/alkaline earth hydride-transition metal composite catalyst system for NH3 synthesis. She has over 150 peer-reviewed journal articles, delivered ca. 70 invited /keynote speeches She is the member of Executive Committee of IEA-Hydrogen, International Advisory board of International Association for Hydrogen Energy(IAHE), the International Steering Committee of International Symposium on Metal-Hydrogen Systems (ISC-MH), the editorial board of Scientific Report and ChemSusChem, and Associate editor of Journal of Energy Chemistry etc.