Competitive adsorption and reaction mechanism on simultaneous catalytic removal of SO2, NO and Hg0 over CuO: Experimental and theoretical studies

Abstract

In this work, experimental and theoretical methods were used to investigate the role of CuO surface on competitive adsorption and reaction mechanism for simultaneous catalytic removal of SO2, NO and Hg0. SO2 preferentially adsorbed on the CuO-O (100) surface, NO and Hg0 preferentially adsorbed on the CuO (110) surface. The optimum reaction temperatures of SO2, NO and Hg0 were 250 °C, 275 °C and 225 °C respectively. It proved the demand of reaction energy and the existence of selective adsorption effect on the CuO surface. The optimum reaction routes for SO2, NO and Hg0 removal were stepwise oxidation process, simultaneous SCR process and (HgO)2 formation process respectively. The generation and consumption of free O atom promoted the oxidation of SO2. (HgO)2 was the key intermediate for the oxidation of Hg0. The formation of NH2NO and the migration of H atom determined the selective reduction of NO. The experimental result was consistent with the theoretical result. Meanwhile, the synergistic effect of CuO-O (100) and CuO (110) surfaces played the key role on simultaneous catalytic removal of SO2, NO and Hg0.