Oxidation efficiency and reaction mechanisms of gaseous elemental mercury by using CeO2/TiO2 and CuO/TiO2 photo-oxidation catalysts at low temperatures in multi-pollutant environments

Background :This study aimed to establish novel photothermal catalysts suitable for the reaction at temperatures of 100-200 ℃ to develop an innovative Hg0 and NO simultaneous removal technology in a lower temperature environment. To further explore the stability and sulfur resistance of 7%CeO2/TiO2 and 5%CuO/TiO2, the oxidation efficiency and reaction mechanisms of Hg0 were investigated in multi-pollutant environments at low temperatures. Methods: TiO2, CeO2/TiO2, and CuO/TiO2 used to oxidize Hg0 at low temperatures were prepared by the sol-gel method, which were localized to glass beads for each test. A self-designed photothermal catalytic reaction system consisted of a mercury generator, a mixing chamber, a catalytical reactor, and an m on-line mercury measuring instrument. Significant Findings: The oxidation efficiencies of Hg0 for different reaction temperatures were ordered as η100℃>η150℃>η200℃ in the atmosphere of N2+Hg0. In the atmosphere of N2+Hg0+NO, low concentration of NO (<300 ppm) exhibited inhibitive effect to Hg0 oxidation, while high concentration of NO (>300 ppm) enhanced Hg0 oxidation. In the atmosphere of N2+Hg0+SO2, SO2 could occupy the active sites for Hg0 oxidation and inhibited the oxidation of Hg0.