Superior DeNO_x activity of V₂O₅–WO₃/TiO₂ catalysts prepared by deposition–precipitation method

V₂O₅–WO₃/TiO₂ catalysts were prepared by incipient wetness impregnation and deposition–precipitation (DP) methods. The catalysts were characterized by N₂ physisorption, X-ray powder diffraction, Fourier transform infra red spectroscopy, electron paramagnetic resonance spectroscopy, transmission electron microscopy, H₂-temperature programmed reduction and NH₃-temperature programmed desorption. The catalysts exhibited only crystalline TiO₂ phases with the active metal and promoter in highly dispersed or amorphous state. The 3 wt% V₂O₅–10 wt% WO₃/TiO₂ catalyst prepared by DP using ammonium carbamate as a precipitating agent was found to be the most active and selective to N₂. The superior activity of the catalyst can be ascribed to the altered acidic and redox properties of vanadium. The catalysts did not show increased potassium resistance with the change in preparation method or with increasing vanadium concentration. Furthermore, potassium-poisoned catalysts showed above stoichiometric loss of surface acidity. Thus, these modified formulations are suggested to be used in coal/natural gas-fired power plants where there is a demand for high selective catalytic reduction activity and selectivity to N₂.