New insight into the promotion effect of Cu doped V2O5/WO3–TiO2 for low temperature NH3-SCR performance

Abstract

The promotion effect of Cu on the V/WTi catalyst for the selective catalytic reduction of NO_x by NH₃ was investigated in the temperature range of 150–400 °C. The Cu addition shows a superior NH₃-SCR performance in comparison with the V/WTi sample. The catalysts were characterized by XRD, Raman, EPR, H₂-TPR, XPS, and in situ DRIFTS techniques. The obtained results reveal that the Cu oxides in close proximity to V oxides on the surface facilitate the formation of double redox couples of V⁵⁺/V⁴⁺ and Cu²⁺/Cu⁺, which may play a critical role in the superior NH₃-SCR performance. The electronic interactions caused by the redox cycle of Cu²⁺ + V⁴⁺ ↔ V⁵⁺ + Cu⁺ could significantly improve the redox properties of the vanadium species, which is beneficial for the activation of NH₃ species bound to the vanadium species. Moreover, the redox cycle of Cu²⁺ + V⁴⁺ ↔ V⁵⁺ + Cu⁺ induces the formation of high-activity nitrate species adsorbed on Cu species. The kinetic analysis reveals that the Cu doping induces the decrease of the activation energy (E_a) of NH₃-SCR.