The enhancement of CuO modified V2O5-WO3/TiO2 based SCR catalyst for Hgo oxidation in simulated flue gas

CuO modified V2O5-WO3/TiO2 based SCR catalysts prepared by improved impregnation method were investigated to evaluate the catalytic activity for elemental mercury (Hg-0) oxidation in simulated flue gas at 150-400 degrees C. Nitrogen adsorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. It was found that V0.8WTi-Cu-3 catalyst exhibited the superior Hg-0 oxidation activity and wide operating temperature window at the gas hourly space velocity (GHSV) of 3 x 10(5) h(-1). The BET and XRD results showed that CuO was well loaded and highly dispersed on the catalysts surface. The XPS results suggested that the addition of CuO generated abundant chemisorbed oxygen, which was due to the synergistic effect between CuO and V2O5. The existence of the redox cycle of V4+ + Cu2+ <-> V5+ + Cu+ in V0.8WTi-Cu-3 catalyst enhanced Hg-0 oxidation activity. The effects of flue gas components (O-2, NO, SO2 and H2O) on Hg. oxidation over V0.8WTi-Cu3 catalyst were also explored. Moreover, the co-presence of NO and NH3 remarkably inhibited Hg. oxidation, which was due to the competitive adsorption and reduction effect of NH3 at SCR condition. Fortunately, this inhibiting effect was gradually scavenged with the decrease of GHSV. The mechanism of Hg. oxidation was also investigated. (C) 2017 Elsevier B.V. All rights reserved.