EFFECTS OF Mn-LOADING ON ACTIVATED CARBON TREATED BY HNO3 FOR SO2 REMOVAL

Using Mn(NO3)(2) as precursor, a series of Mn-based activated carbons treated by HNO3 were prepared by the excessive impregnation method, and characterized by scanning electron microscopy (SEM), nitrogen adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron (XPS) and Fourier-transform infrared spectroscopy (FUR). The desulfurization showed that different Mn loadings on activated carbons performed best SO2 removal ability, with the optimal dosage of 7 wt.% of Mn, which had the best breakthrough sulfur capacity of 211 mg/g and breakthrough time of 391 min. MnO and Mn3O4 coexist in catalysts and exhibit best SO2 removal ability, but after desulfurization, MnO2 is detected, indicating that it may be a reason of the deactivation of catalysts. Different Mn loadings could influence the surface functional groups, when loading 7 wt. % Mn on the sample, the highest SO2 adsorption capacity is mainly attributed to the highest relative content of C=O in the catalyst. After desulfurization, surface oxygen-containing functional groups are changed, which indicates that they could react with SO2 and be restructured by generated H2SO4.