Removal of elemental mercury by TiO2doped with WO3 and V2O5 for their photo- and thermo-catalytic removal mechanisms
2016
Shen, Huazhen | Ie, Iau-Ren | Yuan, Chung-Shin | Hung, Chung-Hsuang | Chen, Wei-Hsiang
The catalytic removal of Hg⁰ was investigated to ascertain whether the catalysts could simultaneously possess both thermo- and photo-catalytic reactivity. The immobilized V₂O₅/TiO₂ and WO₃/TiO₂ catalysts were synthesized by sol-gel method and then coated on the surface of glass beads for catalytic removal of Hg⁰. They were also characterized by SEM, BET, XRD, UV-visible, and XPS analysis, and their catalytic reactivity was tested under 100–160 °C under the near-UV irradiation. The results indicated that V₂O₅/TiO₂ solely possessed the thermo-catalytic reactivity while WO₃/TiO₂ only had photo-catalytic reactivity. Although the synthesis catalytic reactivity has not been found for these catalysts up to date, but compared with TiO₂, the removal efficiencies of Hg⁰ at 140 and 160 °C were enhanced; particularly, the efficiency was improved from 20 % at 160 °C by TiO₂ to nearly 90 % by WO₃/TiO₂ under the same operating conditions. The effects of doping amount of V₂O₅ and WO₃ were also investigated, and the results showed that 10 % V₂O₅ and 5 % WO₃/TiO₂ were the best immobilized catalysts for thermo- and photo-catalytic reactivity, respectively. The effect of different influent concentrations of Hg⁰ was demonstrated that the highest concentration of Hg⁰ led to the best removal efficiencies for V₂O₅/TiO₂ and WO₃/TiO₂ at 140 and 160 °C, because high Hg⁰ concentration increased the mass transfer rate of Hg⁰ toward the surface of catalysts and drove the reaction to proceed. At last, the effect of single gas component on the removal of Hg⁰ was also investigated.
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