(73g) Simultaneous Removal of Hg(0) and NO over Modified SCR Catalyst

Elemental mercury (Hg(0)) is an environmentally toxic heavy metal released during the combustion of coal in power plants. It is imperative that Hg(0) be removed due to its toxicity and bioaccumulation. Since oxidized mercury (Hg(2+)) is highly soluble in water and can be easily adsorbed, it is normal practice to remove mercury by oxidizing the elemental form.

In this study, heterogeneous Hg(0) oxidation kinetics over Mo-modified Selective Catalytic Reduction (SCR) catalyst was investigated using a fixed-bed system in a temperature range of 300 to 400 °C under a steady-state condition. A series of Mo-modified V-based commercial SCR catalysts were prepared by incipient impregnation method for the simultaneous removal of Hg(0) and NO. The Hg(0) oxidation performance of the modified SCR catalyst significantly changes in terms of different formulations while NO reduction performance is quite stable. We have determined optimal formulations of V, Mo, and W doped onto TiO₂ support showing the best performance of Hg(0) oxidation under typical coal combustion simulated flue gas conditions. Different preparation sequence of MoO₃ and V₂O₅ onto TiO₂ support exhibited noticeably different performances. Different characterization techniques were used to account for the Hg(0) oxidation performance differences, including TEM,XRD, H₂ TPR, Raman spectroscopy, XPS and XAFS analyses. The detailed experimental and characterization results will be presented.