Synthesis of NO by rotating sliding arc discharge reactor with conical-spiral electrodes

The present work investigates the potential applications of nitrogen oxides (NO_x), particularly nitric oxide (NO) and nitrogen dioxide (NO₂), generated through discharge plasma in diverse sectors such as medicine, nitrogen fixation, energy, and environmental protection. In this study, a rotating sliding arc discharge reactor was initially employed to produce high concentrations of gaseous NO_x, followed by the utilization of a molybdenum wire redox reactor for NO₂-to-NO conversion. The outcomes reveal that the discharge states and generations of NO_x are affected by varying parameters, including the applied energies, frequencies and airflow states (1.3–2.6 m/s are the laminar flow, 2.6–5.2 m/s are the transition state, 5.2–6.5 m/s are the turbulent flow), and the concentrations of NO_x within the arc discharge are higher than that in the spark discharge. Moreover, the concentrations of NO, NO₂ and NO_x gradually increased, and the concentration ratios of NO/NO₂ and NO_x/NO₂ decreased with increasing the applied energy for one cycle from 14.8 mJ to 24.3 mJ. Meanwhile, the concentrations of NO, NO₂ and NO_x gradually decreased, and the concentration ratios of NO/NO₂ and NO_x/NO₂ first decreased and then increased with increasing the applied frequencies from 5.0 kHz to 9.0 kHz. Further, the concentrations of NO, NO₂ and NO_x gradually decreased, and the concentration ratios of NO/NO₂ and NO_x/NO₂ first increased and then decreased with increasing the air flow speeds from 1.3 m/s to 6.5 m/s. Lastly, the concentrations of NO increased and NO₂ decreased with increasing temperature from 25 °C to 400 °C using molybdenum converted. These findings provide experimental support for the application of plasma in the fields of medicine, nitrogen fixation, energy and environmental protection.