Industrial ammonia production is currently dominated by large, natural-gas-fueled Haber-Bosch plants, which can be difficult to electrify and produce large amounts of CO₂. Small, distributed ammonia plants running on local renewable energy could be game-changers for a future with reduced CO₂ emissions.

Johan A. Martens, KU Leuven, Belgium, and colleagues have developed a new process that is suitable for such a distributed, small-scale production of ammonia. The process, called PNOCRA (Plasma Nitrogen Oxidation and Catalytic Reduction to Ammonia), combines nitrogen oxidation using plasma technology with exhaust-gas purification technology from the automobile sector. Plasma converts N₂ and O₂ molecules from air into nitrogen oxides (NO_x), which are collected by adsorption and periodically reduced to ammonia using “green” hydrogen (overall process pictured below).

 

The energy requirement of PNOCRA is significantly lower than for the state-of-the-art plasma-based NH₃ production directly from N₂ and H₂. The PNOCRA process is an example for the rapidly evolving field of plasma catalysis and is particularly attractive for the local production of nitrogen fertilizers for agriculture.

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• A new route towards green ammonia synthesis through plasma‐driven nitrogen oxidation and catalytic reduction,
  Lander Hollevoet, Fatme Jardali, Yury Gorbanev, James Creel, Annemie Bogaerts, Johan A Martens,
  Angew. Chem. Int. Ed. 2020.
  https://doi.org/10.1002/anie.202011676