Catalysis

Low-temperature ammonia synthesis on electron-rich [RuH6] catalytic centers

Authors

  • Jaysree Pan DTU Physics ,
  • Qianru Wang Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China. ,
  • Jianping Guo Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China. ,
  • Heine Anton Hansen DTU Energy ,
  • Ping Chen Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China. ,
  • Tejs Vegge DTU Energy

Abstract

Ammonia is a central vector in sustainable global growth, but the usage of fossil feedstocks and centralized Haber-Bosch synthesis conditions causes >1.4% of the global anthropogenic CO2 emissions. While nitrogenase enzymes convert atmospheric N2 to ammonia at ambient conditions, even the most active manmade inorganic catalysts fail due to low activity and parasitic hydrogen evolution at low temperatures. Here, we show the [RuH6] catalytic center in ternary ruthenium complex hydrides (Li4RuH6 and Ba2RuH6) activate N2 preferentially and avoid hydrogen over-saturation at low temperatures and near ambient pressure by delicately balancing H2 chemisorption and N2 activation. The active [RuH6] catalytic center is capable of achieving an unprecedented yield at low temperatures via a shift in the rate-determining reaction intermediates and transition states, where the reaction orders in hydrogen and ammonia change dramatically. Temperature-dependent atomic-scale understanding of this unique mechanism is obtained with synchronized experimental and density functional theory investigations.

Content

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Supplementary material

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SUPPORTING INFORMATION FOR A low-temperature reaction mechanism for ammonia synthesis on electron-rich [RuH6] catalytic centers
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