Plasma Nitrogen Fixation: NO_x Synthesis in MnO_x/Al₂O₃ Packed-Bed Dielectric Barrier Discharge

The plasma nitrogen fixation for NOx synthesis from N-2 and O-2 in MnOx/Al2O3 packed-bed dielectric barrier discharge (DBD) and an enhanced effect of MnOx/Al2O3 catalyst are reported. At N-2 content of 50% and SEI of similar to 16 kJ/mol (flow rate of 800 SCCM and discharge power of similar to 9.5 W), NOx production rates are 0.28 SCCM for Al2O3 and 0.42 SCCM for MnOx/Al2O3, and improved by similar to 60% due to the enhanced effect of MnOx/Al2O3. The enhanced effect becomes more significant at lower specific energy input (SEI) or higher N-2 content (lower O-2 content). The MnOx/Al2O3-packed DBD features much more and lower-intensity micro-discharges, larger total capacitance, greater peak-to-peak charge, and higher vibrational temperature of N-2 than the Al2O3-packed DBD. The surface role of MnOx/Al2O3 catalyst in the enhanced effect was disclosed by two-step surface reaction processes and in-situ temperature programed desorption for the adsorbed species of the first step.