Boosting the NOx production in microwave air plasma : a synergy of chemistry and vibrational kinetics

Abstract

This study employs a quasi-1.5D multi-temperature model to investigate the mechanisms governing NO x production and energy costs in microwave plasma reactors operating at 80 mbar, focusing on the interplay of vibrational, chemical, and electron kinetics, thermodynamics, and transport processes across the discharge and afterglow. In the plasma discharge zone, non-thermal processes enhance NO x production as electrons transfer energy effectively to the vibrational mode of N 2 . However, the non-thermal enhancement is found to diminish rapidly within the central-afterglow region. The simulation results show good agreement with experimental data for both the temperature profile and energy cost. Turbulent effects facilitate radial NO diffusion into cooler regions while simultaneously enhancing cooling of the axial region. These findings highlight the potential to improve NO x synthesis efficiency by optimizing turbulence and maintaining non-thermal conditions, offering new opportunities for the advancement of plasma-based chemical processes.