Enhancing the oxidation efficiency of elemental mercury in the presence of NO and SO2 by using Cu(II)O doped TiO2 photothermal catalysts: Kinetics and mechanisms.

[Display omitted] • Cu(II)O/TiO 2 as photothermal catalysts with were explored to remove Hg. • 5%Cu(II)O/TiO 2 has the greatest Hg0 oxidation performance. • NO and SO 2 could chemisorb on the surface of catalysts. • The influence of SO 2 and NO in the Hg0 oxidation reaction was clarified by DFT. This study aimed to apply sol–gel synthesized Cu(II)O doped TiO 2 to enhance the oxidation of gaseous elemental mercury (Hg0) in the flue gases containing NO and SO 2 at the temperatures of 120-180℃ under the irradiation of near-ultraviolet (near-UV). The influences of SO 2 and NO on the oxidation efficiency of Hg0 were investigated by in-situ diffuse reflection infrared spectroscopy (DRIFT) and density functional theory (DFT). Experimental results showed that an optimal 5 %Cu(II)O/TiO 2 had the oxidation efficiencies of Hg0 from 40 to 100 % at 120-180℃. The oxidation efficiencies of Hg0 were 85 and 70 % at 120℃, and 40 and 5 % at 180 °C, in the presence of solely SO 2 and NO, respectively. Surface characterization showed that Cu(II)O was evenly dispersed over the surface of TiO 2 catalysts. NO could inhibit the oxidation of Hg0 since it consumed the chemisorbed oxygen (O α) and compete with Hg0 at the surface active sites. In contrast, SO 2 could promote the oxidation efficiency of Hg0 due to the formation of HgSO 4 on the surface of Cu(II)O/TiO 2 catalysts. In the exposure of NO/SO 2 , NO and SO 2 can be adsorbed on the catalyst surface reacting with ̇OH. The photothermal oxidation reactivity of Hg0 was inhibited due to the competitive adsorption between NO/SO 2 and Hg0. The Langmuir-Hinshelwood (L-H) kinetic model successfully simulated the oxidation rate of Hg0. Moreover, DFT was further applied to estimate the binding energies of different gas molecules confirming the competence for active sites on the surface of Cu(II)O/TiO 2 between NO/SO 2 and Hg0. [ABSTRACT FROM AUTHOR]