Nitrogen Fixation as NOx Enabled by a Three-Level Coupled Rotating Electrodes Air Plasma at Atmospheric Pressure

• Published in: Plasma chemistry and plasma processing Vol. 42; no. 1; pp. 211 - 227
• Main Authors: Lei, XinYu, Cheng, He, Nie, LanLan, Lu, XinPei
• Format: Journal Article
• Language: English
• Published: New York Springer US 2022; Springer Nature B.V
• Subjects: Air flow; Air plasma; Atmospheric pressure; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Classical Mechanics; Emission; Energy; Energy costs; Flow velocity; Fluid flow; Inorganic Chemistry; Mechanical Engineering; Nitrogenation; Original Paper; Plasma; Rotating plasmas; Rotation; Nitrogen fixation; NO; Rotating electrodes; Energy cost; Air plasma; production rate
• ISSN: 0272-4324; 1572-8986
• DOI: 10.1007/s11090-021-10222-2

In this paper, a three-level coupled rotating electrodes air plasma at atmospheric pressure is developed for evaluation of nitrogen fixation. Factors influencing the NO x production rate and energy cost, including airflow rate, the input H 2 O concentration, blade numbers at each rotating electrode and rotating speed, are examined. Air flow rates prove to have no effect on the rotational temperature of N 2 337.1 nm and the emission intensities of N 2 + and N 2 , but specific energy input (SEI) and species’ residence time can be shorter with higher air flow rates, resulting in lower NO x concentration and energy cost. The addition of H 2 O also has a positive effect on both NO x concentration and energy cost. Optical emission spectrum (OES) shows that air + H 2 O plasma has stronger 336 nm (NH) and 309 nm (OH) emission lines than air plasma, suggests NH and OH are the key species in NO x enhancement. The most energy efficient conditions are found at airflow rate of 15 l min −1 , 12% H 2 O concentration, with 4 blades on each rotating speed. Under these conditions, the lowest energy cost is observed to be 165 GJ/tN.