Simultaneous removal of SO2, NO and Hg0 from flue gas using vaporized oxidant catalyzed by Fe/ZSM-5

Abstract

A catalytic oxidation/absorption method consisting of prepared nano-sized iron loaded ZSM-5 zeolite (Fe/ZSM-5), vaporized H2O2 and Na2S2O8, and Ca(OH)2 solution was established to simultaneously remove SO2, NO and Hg0 from flue gas, achieving the efficiencies of 99.8% for SO2, 95.5% for NO and 90.8% for Hg0. The performance evaluation experiments determined the optimal conditions: the mass fractions of H2O2 and Na2S2O8 were 10% and 0.5%, catalyst dosage was 0.3 g, gas flow rate was 1.5 L/min and reaction temperature was 140℃. Hydroxyl radical (OH) and sulfate radical (SO4−) were confirmed as the major species to oxidize SO2, NO and Hg0 into SO42−, NO3– and Hg2+, the morphology, composition and magnetic properties of fresh and spent catalysts were characterized by several techniques, and the removal products in spent Ca(OH)2 solution were analyzed. By which, the simultaneous removal mechanism under gas-like phase was preliminarily speculated.