Chemical Engineering Journal, Vol.283, 631-638, 2016
Ozone-free nitric oxide production using an atmospheric pressure surface discharge - A way to minimize nitrogen dioxide co-production
Effects of temperature on nitric oxide (NO) production and on byproduct nitrogen dioxide (NO2) and ozone (O-3) in a non-equilibrium sliding discharge in atmospheric pressure air are described. Heating the electrodes! dielectric surfaces in contact with the discharge plasma from 20 degrees C to 420 degrees C caused an increase in energy per pulse by more than an order of magnitude. More importantly, heating to a few hundred degrees above room temperature caused the destruction of ozone (O-3) and the reduction of nitrogen dioxide (NO2) but promoted NO formation. At 20 degrees C, 400-4500 ppm O-3 with an energy cost of 2-4 MJ/mol, and 12-180 ppm NO2 with an energy cost of 75-140 MJ/mol were generated from dry air flowing at 1 lpm. At 220 degrees C, however, NO and NO2 were produced in about equal proportion while O-3 was below detection limits. The efficiency of NO generation increased with an increase of temperature. At the maximum temperature used in this study, i.e., 420 degrees C, 160-1040 ppm NO was produced from dry air at an energy cost of 24-67 MJ/mol, with a NO/NO2 ratio of more than 4 and free of O-3. (C) 2015 Elsevier B.V. All rights reserved.