Simultaneous removal of NO and Hg0 over Ce-Cu modified V2O5/TiO2 based commercial SCR catalysts

Abstract

A series of novel Ce-Cu modified V2O5/TiO2 based commercial SCR catalysts were prepared via ultrasonic-assisted impregnation method for simultaneous removal of NO and elemental mercury (Hg0). Nitrogen adsorption, X-ray diffraction (XRD), temperature programmed reduction of H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. 7% Ce-1% Cu/SCR catalyst exhibited the highest NO conversion efficiency (>97%) at 200–400°C, as well as the best Hg0 oxidation activity (>75%) at 150–350°C among all the catalysts. The XPS and H2-TPR results indicated that 7% Ce-1% Cu/SCR possess abundant chemisorbed oxygen and good redox ability, which was due to the strong synergy between Ce and Cu in the catalyst. The existence of the redox cycle of Ce4++Cu1+↔Ce3++Cu2+ could greatly improve the catalytic activity. 7% Ce-1% Cu/SCR showed higher resistance to SO2 and H2O than other catalysts. NO has a promoting effect on Hg0 oxidation. The Hg0 oxidation activity was inhibited by the injection of NH3, which was due to the competitive adsorption and oxidized mercury could be reduced by ammonia at temperatures greater than 325°C. Therefore, Hg0 oxidation could easily occurred at the outlet of SCR catalyst layer due to the consumption of NH3.