Effect of synthesis methods on activity of V2O5/CeO2/WO3-TiO2 catalyst for selective catalytic reduction of NOx with NH3

The effect of synthesis methods on the activity of V/Ce/WTi catalysts was investigated for the selective catalytic reduction (SCR) of NOx by NH3. V/Ce/WTi-DP (deposition precipitation) catalyst showed excellent NH3-SCR performance, especially the better medium-temperature activity and the less N2O formation than V/Ce/WTi-IMP (impregnation). These catalysts were characterized by X-ray diffraction (XRD), Brumauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (H-2-TPR), and in situ DRIFTS techniques. The XPS and H-2-TPR results revealed that V/Ce/WTi-DP exhibited more surface Ce species, higher level of O-alpha and higher reducibility of Ce species. Reflected by in situ DRIFTS results, the deposition precipitation method (DP) contributed to a greater amount of weakly adsorbed NO2, monodentate nitrate and NH3 species with better reactive activity. Meanwhile, the cis-N2O22- species, an intermediate for N2O formation, was very limited. As a result, these advantages brought about the superior SCR activity and N-2 selectivity for V/Ce/WTi-DP.