Characteristics of denitrification and mercury removal by Mo-Mn/TiO2 catalysts
HU Peng, DUAN Yu-feng, CHEN Ya-nan, ZHOU Qiang, ZHU Chun, DING Wei-ke, LI Chun-feng, LIU Meng, WANG Shuang-qun
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China
Mo/Mn-TiO2 catalysts were prepared by impregnation method, the effects of reaction temperature, HCl and SO2 on denitrification and mercury removal from simulated flue gas being studied. The studies showed that, too high reaction temperature was not conducive to the removal of mercury, and too low temperature inhibited the denitrification reaction, but the best efficiency of denitrification and mercury removal can be obtained at 200℃. The addition of HCl can promote the oxidation of mercury, but significantly decrease the rate of NO conversion. The presence of SO2 in the flue gas played an inhibitory role in the process of denitrification and mercury removal. The catalysts, which before and after the reaction of sulfur poisoning, were studied by XRD, H2-TPR and XPS. The results showed that the continuous deposition of sulfate on the catalyst surface and the consumption of active component Mn4+ and chemical oxygen Oα were the main reasons for the deactivation of the catalyst. In addition, the competitive adsorption of SO2 with NH3 and Hg0 on the surface active sites of the catalyst also severely inhibited the denitration and mercury removal. The denitration process of Mo-Mn/TiO2 was accomplished by the conversion of Mn valence states, among which both Mo and O2 were the assistant for the conversion. The removal of mercury by Mo-Mn/TiO2 was mainly catalytic oxidation, the lattice oxygen in the metal oxide transforms Hg0 into HgO and was removed.
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