Issue 19, 2022

Green chemical pathway of plasma synthesis of ammonia from nitrogen and water: a comparative kinetic study with a N2/H2 system

Abstract

Sustainable ammonia synthesis under mild conditions that relies on renewable energy sources and feedstocks is globally sought to replace the current Haber–Bosch process. Electricity-driven plasma catalysis is receiving increasing attention as a sustainable technology for the efficient synthesis of ammonia. However, the current implementation of nonthermal plasma technology still faces several hurdles, particularly the extensive usage of energy-intensive H2, low energy efficiency and the lack of understanding of the underlying mechanisms of the plasma catalysis process. Here we propose a green chemical pathway of plasma catalysis from nitrogen and water for sustainable ammonia production. In order to understand the different characteristics of the N2/H2O plasma system and seek further improvements in ammonia synthesis, detailed plasma kinetics modelling is presented in comparison with the N2/H2 system at atmospheric pressure. The model includes both electron and vibrational kinetics and updated surface reactions adapted from DFT calculation results on the SiO2 surface. The facile dissociative adsorption of H2O and the Eley–Rideal mechanisms are demonstrated to be important to enable efficient NH3 production as the experimental observation. The model reproduced the measured trends of ammonia production on the different concentrations of H2O input and power density with reasonable accuracy and provided an explanation of the critical influence of temperature and catalyst packing in the N2/H2O system in comparison to the N2/H2 system in relation to the quenching effect of H2O by vibrational–translational relaxation.

Graphical abstract: Green chemical pathway of plasma synthesis of ammonia from nitrogen and water: a comparative kinetic study with a N2/H2 system

Supplementary files

Article information

Article type
Paper
Submitted
17 jun 2022
Accepted
01 set 2022
First published
03 set 2022

Green Chem., 2022,24, 7458-7468

Green chemical pathway of plasma synthesis of ammonia from nitrogen and water: a comparative kinetic study with a N2/H2 system

J. Hong, T. Zhang, R. Zhou, L. Dou, S. Zhang, R. Zhou, B. Ashford, T. Shao, A. B. Murphy, K. (. Ostrikov and P. J. Cullen, Green Chem., 2022, 24, 7458 DOI: 10.1039/D2GC02299K

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