Improved activity and SO2 tolerance of rare-earth elements modified CeTi catalyst for Hg0 and NO simultaneous removal from flue gas

Six rare-earth elements (including La, Sm, Pr, Dy, Y, and Nd) were modified on the surface of the CeTi samples for Hg-0 oxidation and NO oxidation. The X-CeTi catalysts significantly improved the Hg-0 oxidation, NO oxidation, and SO2 tolerance compared with the CeTi catalyst. Moreover, O-2 and NO can facilitate the activities significantly. The BET results showed that the specific surface area could be increased by doping of rare-earth elements. In addition, XRD and FT-IR experiments indicated that the rare-earth elements can facilitate the formation of the amorphous structure of CeO2. The XPS curves of Ce 3d and O 1s showed that surface oxygen species and Ce4+/Ce3+ redox couples were responsible for the catalytic performance, confirming that the SO2 tolerance was improved via the electron transfer by Ce4++Dy2+Ce3++Dy3+ reactions. The H-2-TPR results suggested that the redox capacity of X-CeTi catalysts was enhanced, which could improve the activities of the catalysts. Moreover, Dy-CeTi had the highest NO and Hg-0 oxidation among these rare-earth elements on account of the largest specific surface, more surface-active oxygen and H-2-TPR reduction peak integral area. The catalyst can maintain the conversion efficiency of elemental mercury and NO at 67% and 76% even in flue gas containing 800 ppm SO2. Such work supplied new insights into modified Ce-Ti catalysts to simultaneously remove NO and elemental mercury from the flue gas with high efficiencies, which owned a promising prospect in the practical industrial application.