Boosting resistance to H2O and SO2 in low-temperature NH3-SCR denitrification reaction by W addition in Cu0.1-mWmTiOx (m=0.05-0.09) due to modulating the synergistic effect of oxidation property and acidity

It remains a challenge to obtain competitive low-temperature NH3-SCR denitrification catalyst with excellent resistance to H2O and SO2. Herein, Cu0.1-mWmTiOx (m = 0.05, 0.06, 0.07, 0.08, 0.09) catalysts for application in NH3-SCR denitrification were synthesized by the sol-gel technology. These catalysts were characterized by XRD, separate NO/NH3 oxidation, NH3-TPD, NO-TPD, SO2-TPD, N2 physical adsorption, H2-TPR, TEM, XPS and in-situ DRIFTS to analyze the impact of W introduction on NH3-SCR of NO reaction. The results demonstrate that the Cu0.1-mWmTiOx catalysts have higher catalytic activity and N2 selectivity than Cu0.1TiOx without adding W, in which the Cu0.03W0.07TiOx catalyst exhibits significantly improved the H2O/SO2 resistance and a wide window of activity at 210-420 degrees C, having a 100% NO conversion and >90 % N2 selectivity. By comparison with the Cu0.1TiOx catalyst, the oxidation capability of the Cu0.1-mWmTiOx catalysts decreases with the addition of W, but the acidity is enhanced. The better NH3-SCR activity of Cu0.03W0.07TiOx may be linked with the synergistic effect of the moderate oxidation property and the enhanced surface acidity of the catalyst. Especially, in-situ DRIFTS under various conditions was used to analyze to the good H2O/SO2 tolerance at low temperature after the W addition in the Cu0.03W0.07TiOx catalyst, which shows the W addition effectively suppresses the SO2 oxidation to form sulfate with copper of the catalyst, prevent the competitive adsorption of H2O and NOx, and does not affect NH3 adsorption. In addition, the possible SCR reaction process was proposed on Cu0.03W0.07TiOx catalyst based on various characterizations.