Nitrogen Fixation by an Arc Plasma at Elevated Pressure to Increase the Energy Efficiency and Production Rate of NOX

Plasma-based nitrogen fixation for fertilizer pro-duction is an attractive alternative to the fossil fuel-based industrial processes. However, many factors hinder its applicability, e.g., the commonly observed inverse correlation between energy con-sumption and production rates or the necessity to enhance the selectivity toward NO2, the desired product for a more facile formation of nitrate-based fertilizers. In this work, we investigated the use of a rotating gliding arc plasma for nitrogen fixation at elevated pressures (up to 3 barg), at different feed gas flow rates and composition. Our results demonstrate a dramatic increase in the amount of NOx produced as a function of increasing pressure, with a record-low EC of 1.8 MJ/(mol N) while yielding a high production rate of 69 g/h and a high selectivity (94%) of NO2. We ascribe this improvement to the enhanced thermal Zeldovich mechanism and an increased rate of NO oxidation compared to the back reaction of NO with atomic oxygen, due to the elevated pressure.

Automated summary

Plasma-based nitrogen fixation is a promising alternative for fertilizer production, but factors like energy consumption and selectivity towards desired products hinder its applicability. This study investigated the use of rotating gliding arc plasma under elevated pressures, different gas flow rates, and composition, showing a significant increase in NOx production with low energy consumption (1.8 MJ/(mol N)), high production rate (69 g/h), and high selectivity (94%). This improvement is attributed to the enhanced thermal Zeldovich mechanism and increased NO oxidation rate due to elevated pressure.