Removal of Hg0, NO, and SO2 by the surface dielectric barrier discharge coupled with Mn/Ce/Ti-based catalyst.

Abstract

In this study, power parameters (power, frequency, and voltage), initial Hg0 concentration, and residence time are investigated for the removal of the increased Hg0 concentration via surface dielectric barrier discharge (SDBD). The synergistic effect of a Mn/Ce/Ti catalyst with SDBD is verified with a mixture of flue gas (Hg0, NO, and SO2). Results show that Hg0 oxidation efficiency has an optimal frequency, which declines as the input voltage increases. The amplification of the Hg0 removal efficiency decreases as voltage increases. The effect of the initial Hg0 concentration gradually decreases as the peak voltage increases. The residence time slightly affects the Hg0 removal efficiency at a high peak voltage. The cooling water temperature behaves differently on Hg0 oxidation under high and low voltages. X-ray photoelectron spectroscopy (XPS) reveals the relative atomic concentrations of Mn2+ and Mn3+ in the Mn-TiO2 and Mn-Ce-TiO2 catalysts are 66.84% and 65.80%, respectively, which indicate that Ce addition will not affect surface Mn. Mn has a limited catalytic action on the removal of flue gas with and without SDBD. Nevertheless, SDBD can stimulate the oxygen storage capacity of Mn to increase the NO2 conversion rate. Mn-Ce-TiO2 greatly improves the removal efficiencies of NO and SO2 because of the existence of the redox pairs of Mn4+/Mn3+, Ce4+/Ce3+, and Ti4+/Ti3+. However, the three catalysts slightly differ on Hg0 removal when combined with SDBD, indicating that the effect of the catalyst was weakened after SDBD was added.