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

Highlights: • Simultaneous removal of NO and Hg⁰ over the novel modified commercial SCR catalysts. • 7% Ce-1% Cu/SCR catalyst exhibited excellent activity of NO conversion and Hg⁰ oxidation. • 7% Ce-1% Cu/SCR catalyst showed higher resistance to SO₂ and H₂O than other catalysts. • The synergistic interaction between Ce and Cu in the catalyst improved the activity greatly. - 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.