Removal of SO2 from Gas Streams by Oxidation using Plasma-Generated Hydroxyl Radicals

Abstract

The key problem for the removal of SO2 by electrical discharge methods is how to obtain the hydroxyl radicals at high concentration and large production rates. With the micro-gap discharge method, O2 and H2O in simulated gas streams (N2/O2/H2O/SO2) are ionized into a large number of OH. radicals to oxidize SO2 into SO3 which reacts with H2O forming H2SO4 droplets at 120 °C in the absence of any catalyst or absorbent. The droplets are captured with an electrostatic precipitator. As a result, conversion of SO2 to primarily H2SO4 is limited by the generation of OH. radicals. By increasing the reduced field and concentrations of O2 and H2O, the amount of OH. radicals increase resulting in more removal of SO2 from gas streams. The removal efficiency of SO2 reaches 100% when the residence time is only 0.74 s. Therefore, a new gas-phase oxidation method for removal of SO2 without NH3 additive is found.