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

17 September 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

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.

Keywords

low temperature NH3 synthesize
N2 reduction on Li4RuH6
N2 to NH3 catalysis
N2 reduction to NH3
low temperature mechanism of N2 to NH3 catalysis

Supplementary materials

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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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Additional information related to the manuscript "A low-temperature reaction mechanism for ammonia synthesis on electron-rich [RuH6] catalytic centres"
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