Plasma Assisted Selective Catalytic Reduction of Nitrogen Oxides

Abstract

This chapter investigates the effect of plasma pretreatment for NOx control on a Selective Catalytic Reduction (SCR) catalyst. Reduction of nitrogen oxides (NOx) is considered as a great challenge in the overall task of keeping the environment clean. Presently, various industries employ selective catalytic reduction process to control NOx emissions. The limitation of SCR process is that it cannot efficiently remove NOx from low-temperature emissions. Pretreatment of the exhaust gas by electric discharge plasma has been found to be helpful in enhancing the catalytic activity. This chapter presents a pulsed corona reactor, which has been used in combination with industry supplied SCR catalyst to control NOx from a simulated flue gas mixture. The role of plasma in the combined system at different operating temperatures is discussed, the effect of water on the combined system is studied, and the effect of plasma pretreatment for NOx control on a SCR catalyst is investigated. A wire-cylinder plasma reactor is energized by short-rising high-voltage pulses. A SCR catalytic reactor is placed ahead of the plasma reactor. The significance of the plasma reactor is found to be the conversion of NO to NO2. Plasma effect results in 35% increase in NOx removal efficiency on the catalyst at 180°C for an energy density of 47 J/l. The effect of plasma decreases with temperature.