Abstract
In present research, experiments using a diffuse glow discharge, which is one of non-thermal plasma, were carried out to remove NOx. To generate diffuse glow discharge a double discharge method was used and it was consisted of two discharges, pre-discharge and main discharge. The pre-discharge produces many initial electrons around cathode and generates the main discharge easily at atmospheric pressure.
The experiments employed two kinds of sample gas, NO/N2 mixture and NO/N2/O2 mixture gas, with several different NO concentrations for removing NOx, and adjusted at 1.25 [l/min] for all measurements. Using NO/N2 mixture gas a reduction rate of NO decreased with increasing initial NO concentration. Thus the present NOx reactor can remove efficiently at the region of low NOx concentration. Nevertheless, an energy yield of NO removal improved and reached 8.82 [mg/Wh] at initial NO value of 186 [ppm] which is about 5 or 6 times comparing to conventional discharge methods. Steepness of main voltage was important factor for removing NOx. With NO/N2/O2 mixture gas the reduction rate of NO reached 100 [%] at O2 mixture rate of 20[%] because NO oxidation was accelerated drastically by generated ozone together with O atoms. The energy yield of NO removal was 21.9 [mg/Wh] which is about 2.5 times higher than one of NO/N2 mixture gas.
