Mass transfer and electrochemical behavior of nitrate reduction to ammonia in electrocatalytic flow cell reactor

The electrochemical nitrate reduction reaction (e-NITRR) process based on plasma has become a potential technology for commercial large-scale green ammonia synthesis. This work emphasized the prominent influence of operating parameters on e-NITRR through the combination of experiments and simulations in an electrocatalytic flow cell reactor. An integrated model was developed and the non-linear functions between operating conditions and exchange current density were obtained by optimization fitting. The average relative error of experiments and simulations was <5%, which can provide solutions for the design of reactor structures and optimization of process parameters. Besides, the results also showed that the tandem steps of NO₃⁻ → NO₂⁻ and NO₂⁻ → NH₃ were, respectively, controlled by mass transfer and electrochemical kinetics at low electrolyte flow rate, and this characteristic makes the increase in electrode dimensions have the opposite effect on the formation rate of NO₂⁻ and NH₃.