Significance of Fe sub(2)O sub(3) modified SCR catalyst for gas-phase elemental mercury oxidation in coal-fired flue gas

• Published in: Fuel processing technology Vol. 149; pp. 23 - 28
• Main Authors: Huang, Wen-Jun, Xu, Hao-Miao, Qu, Zan, Zhao, Song-Jian, Chen, Wan-Miao, Yan, Nai-Qiang
• Format: Journal Article
• Language: English
• Published: 01.08.2016
• Subjects: Catalysts; Flue gases; Mercury (metal); Oxidation; Selective catalytic reduction; Simulation; X-ray photoelectron spectroscopy; X-rays
• ISSN: 0378-3820
• DOI: 10.1016/j.fuproc.2016.04.007

To improve the ability of commercial selective catalytic reduction (SCR) catalyst to catalyze the oxidation of gaseous elemental mercury, Fe sub(2)O sub(3) was introduced. Modifying with Fe sub(2)O sub(3) can significantly enhance the elemental mercury oxidation ability of SCR catalyst. Fe sub(2)O sub(3)/SCR prepared by an impregnation method was employed as mercury oxidation catalysts in the simulated flue gas, and the role of Fe sub(2)O sub(3) was investigated. The temperature window was from 150 to 450 degree C. In this study, Fe sub(2)O sub(3)/SCR (1% Fe, wt.) was found to be an optimal catalyst with a mercury oxidation efficiency of higher than 90% at 350 degree C using a simulated flue gas. The catalysts were characterized by X-ray diffraction (XRD), Brunauer Emmet Teller (BET) measurements, and X-ray photoelectron spectroscopy (XPS). The results indicated that the Fe sub(2)O sub(3) was well-dispersed on the surface of SCR. The surface areas and catalytic oxidation activity were not consistent patterns, and the diameter of the mercury atom was much smaller than the pore diameter of the Fe sub(2)O sub(3)/SCR catalysts. Loading content of Fe sub(2)O sub(3) was a very important factor for the removal of mercury. HCl was the most effective flue gas component responsible for the Hg super(0) oxidation. However, SO sub(2) had a slight inhibition effect on Hg super(0) oxidation. Furthermore, change experiment of a mercury valence state was performed. And the mechanism of Hg super(0) oxidation was also discussed.