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The Role of Heterogeneous Catalysts in the Plasma-catalytic Ammonia Synthesis

Patil, Bhaskar S; Cherkasov, Nikolay; Srinath, Nadadur Veeraraghavan; Lang, Juergen; Ibhadon, Alex O; Wang, Qi; Volker Hessel

Authors

Bhaskar S Patil patilbhaskars@gmail.com

Nikolay Cherkasov

Nadadur Veeraraghavan Srinath

Juergen Lang

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Dr Alex Ibhadon A.O.Ibhadon@hull.ac.uk
Reader in Catalysis and Reactor Engineering

Qi Wang

Volker Hessel



Contributors

Abstract

Ammonia, being the second largest produced industrial chemical, is used as a raw material for many chemicals. Besides, there is a growing interest in the applications of ammonia as electrical energy storage chemical, as fuel, and in selective catalytic reduction of NOx. These applications demand on-site distributed ammonia production under mild process conditions. In this paper, we investigated 16 different transition metal and oxide catalysts supported on γ-Al2O3 for plasma-catalytic ammonia production in a dielectric barrier discharge (DBD) reactor. This paper discusses the influence of the feed ratio (N2/H2), specific energy input, reaction temperature, metal loading, and gas flow rates on the yield and energy efficiency of ammonia production. The optimum N2/H2 feed flow ratio was either 1 or 2 depending on the catalyst-substantially above ammonia stoichiometry of 0.33. The concentration of ammonia formed was proportional to the specific energy input. Increasing the reaction temperature or decreasing gas flow rates resulted in a lower specific production due to ammonia decomposition. The most efficient catalysts were found to be 2 wt% Rh/Al2O3 among platinum-group metals and 5 wt% Ni/Al2O3 among transitional metals. With the 2 wt% Rh catalyst, 1.43 vol% ammonia was produced with an energy efficiency of 0.94 g kWh-1. The observed behaviour was explained by a combination of gas phase and catalytic ammonia formation reactions with plasma-activated nitrogen species. Plasma catalysts provide a synergetic effect by activation of hydrogen on the surface requiring lower-energy nitrogen species.

Journal Article Type Article
Journal Catalysis today
Print ISSN 0920-5861
Publisher Elsevier
Peer Reviewed Peer Reviewed
APA6 Citation Patil, B. S., Cherkasov, N., Srinath, N. V., Lang, J., Ibhadon, A. O., Wang, Q., & Volker Hessel, . (in press). The Role of Heterogeneous Catalysts in the Plasma-catalytic Ammonia Synthesis. Catalysis Today, https://doi.org/10.1016/j.cattod.2020.06.074
DOI https://doi.org/10.1016/j.cattod.2020.06.074
Keywords Plasma catalysis; Ammonia production; Catalytic DBD reactor; Supported transition metal oxides; Energy efficiency; Haber-Bosch
Publisher URL https://www.sciencedirect.com/science/article/abs/pii/S0920586120304661?via%3Dihub
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