The effect of Cl- on CeO2-WO3/TiO2 catalyst for selective catalytic reduction of NO with NH3

The 30CeO(2)-4WO(3)/TiO2 catalyst was prepared utilizing cost-effective cerium chloride instead of the traditional cerium nitrate as the cerium source in this paper. The structure, physical and chemical properties, catalytic performance were characterized. The catalytic performance and N-2 selectivity of the 30CeO(2)-4WO(3)/TiO2 catalyst significantly deteriorate with increased the content of Cl-. Specifically, denitration efficiency of 30CeO(2)-4WO(3)/TiO2-0.007 % exceeding 80 % and 90 % were 225 similar to 520 degrees C and 241 similar to 504 degrees C, respectively, whereas the maximum denitration efficiency of the 30CeO(2)-4WO(3)/TiO2-0.161 % sample was only 79.83 %. The effect mechanism of Cl- on catalytic performance was discussed. (1) XRD and BET results show that Cl- can cause the expansion of the lattice of TiO2 and CeO2, thereby increasing its crystallinity and decreasing the specific surface area. (2) Cl- interacts with NH4+ to form NH4Cl, which subsequently reacts with CeO2 to produce CeOCl, leading to the obstruction of the catalyst's micropores. (3) XPS, NH3-TPD, and H-2-TPR analyses reveal that Cl- would occupy the oxygen vacancies, impeding oxygen migration and diminishing active surface centers. (4) In-situ DRIFTs analysis demonstrates that elevated Cl- concentrations diminish NH3 adsorption capacity and facilitate nitrate species formation. The accumulation of nitrates was a primary cause of the decline in catalyst activity.