The significance of NO2 dimerization in plasma-based NOx synthesis for nitrogen fixation

Abstract

Plasma-based NOx synthesis has been considered as a sustainable alternative to the conventional Haber-Bosch process. Despite the advancements in research achieved in recent years, limited attention has been paid to the reversible dimerization reaction of NO2 to N2O4. This reaction can significantly alter the parameters considered with the process’ output, such as the concentration or volume fraction of products and the energy consumption. This work aims to investigate the significance of dimerization through theoretical analysis and experimentation. Experiments were conducted with a 2D-gliding arc reactor to evaluate the influence of dimerization in the case of plasma reactor operation. It was observed that the dimerization reaction reached equilibrium in microseconds, resulting in a maximum hypothetical NO2 equilibrium conversion of 48.8%. For plasma experiments, the dimerization could cause a maximum error of 14.1% in product detection, which needs to be carefully considered along with the influence of temperature variations on the measurement.