Effect of fluorine additive on CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3.

A series of CeO2(ZrO2)/TiO2 catalysts with fluorine additive were prepared by impregnation method and tested for selective catalytic reduction (SCR) of NO by NH3. These samples were characterized by XRD, N2-BET, Raman spectra, SEM, TEM, NH3-TPD, H2-TPR and XPS, respectively. Results showed that the optimal catalyst with the appropriate HF exhibited excellent performance for NH3-SCR and more than 96% NO conversion at 360°C under GHSV of 71,400h-1. It was found that the grain size of TiO2 increased and the specific surface area reduced with the modulation of HF, which was not good for the adsorption of gas molecule. However, the modulation of HF exposed the high energy (001) facets of TiO2 and increased the surface chemisorbed oxygen concentration, oxygen storage capacity and Ce3+ concentration of catalyst. In addition, the synergy of (101) and (001) facets was beneficial to the improvement of catalytic activity.