Nitrogen fixation by rotational gliding arc plasma at surrounding conditions

Abstract

Nitrogen fixation (NF) was investigated in a rotational gliding arc plasma based on various energy inputs, flow rates, and N2:O2 ratios under atmospheric conditions. For practical application, the effect of water content in the feed, self-heating during plasma discharge, prolonged operation, and comparison between plasma and thermal process for N2 oxidation were also conducted. The comparison results reveal that NF by the gliding arc plasma is superior to the thermal process in terms of NOx yield and energy consumption at low temperatures and atmospheric pressure. Herein, energy input and flow rate are two controlled factors that significantly influence NOx production rate. Simultaneously, O2 content played a crucial role in determining NOx yield, selectivity of NO/NO2, and energy consumption. Observations during plasma discharge indicated an initial rise in gas and reactor body temperatures, coinciding with decrease in total NOx formation. Moreover, the presence of water had a negative effect on NOx yield. Accordingly, the optimized conditions for NF by gliding arc plasma for NOx formation was identified at a N2 to O2 ratio of 3:2 without water vapor in the feed gas. Furthermore, a 14-h continuous operational test validated the robustness of our reactor configuration, affirming its long-term viability. The study concludes by performing oxidation of the NOx gas followed by dissolution in water, successfully generating nitric acid. These findings underscore the potential of gliding arc plasma for efficient NF processes, offering insights into optimal operational conditions and downstream applications for nitric acid generation.