Reduction of nitrogen oxide using ammonia radicals prepared by intermittent dielectric barrier discharge

Abstract

Summary form only given. Non-thermal plasma processes have attracted attention to de-NOx because of their high removal efficiency and cost effective process, where the plasma-induced radicals efficiently convert NOx into harmless gases such as N/sub 2/, O/sub 2/, and H/sub 2/O and useful matters. In the present study, a method of radical injection was used, where the ammonia radicals were externally generated by a dielectric barrier discharge (DBD) in a separate chamber of a small volume, and were injected into NOx gas stream field to reduce NOx molecules. NO in N/sub 2/ gas was reduced by the ammonia radicals. The plasma is generated at a gap with a coaxial electrode configuration using one-cycle sinusoidal (OCS)-wave power source to accomplish high removal and energy efficiencies. The repetition rate of plasma generation was 5-50 kHz and the output peak-to peak voltage of the power supply was 2-20 kV. The dependence on the discharge power was measured by varying the repetition rate and applied voltage. The maximum energy efficiency, 140 g/kWh, was obtained at small values of the NH/sub 3/ concentration and the discharge power. It was found that the both NO removal rate and energy efficiency were correlated by the product of excited power per unit volume and ammonia residence time in the plasma reactor. Experiments were also made to obtain higher energy efficiency for various gap lengths of DBD source on optimal gas flow rate and applied voltage for de-NOx.