Abstract:
A series of MnO
x modified TiO
2 based sorbents were synthesized using wet impregnation method and its performance on elemental mercury (Hg
0) removal was studied. The effects of loading amount, calcination temperature, reaction temperature, and flue gas compositions on mercury removal efficiency were investigated. The sorbents were characterized by TGA, N
2 adsorption-desorption, XRD, FT-IR, XPS and Hg-TPD. It was shown that the optimum MnO
x loading value was 12%, and the optimal calcination and reaction temperature were 450 and 300 ℃, respectively. The highest mercury removal efficiency of MnO
x-TiO
2 sorbent was 98.46%. O
2 and HCl in flue gas played a positive role in mercury removal. SO
2 had a strong inhibitory effect on mercury removal, which may be due to the competition adsorption between SO
2 and Hg
0. At the same time, the manganese sulfate produced during the reaction covered the surface of the active site, resulting in the decrease in mercury removal efficiency. CO
2 and NO in flue gas also slightly inhibited mercury removal. Mn
4+ participated in oxidizing Hg
0 to Hg
2+, accompanied with its reduction to Mn
3+. The adsorption and oxidation process of Hg
0 over MnO
x-TiO
2 basically conformed to the Mars-Maessen mechanism and Langmuir-Hinshelwood mechanism.