In situ DRIFTS investigation on CeO2/TiO2–ZrO2–SO 4 2− catalyst for NH3–SCR: the influence of surface acidity and reducibility

A series of CeO2-modified TiO2–ZrO2–SO 4 2− catalysts were employed to the selective catalytic reduction (SCR) of NOx by NH3. The obtained results indicated that the interaction between CeO2 and TiO2–ZrO2–SO 4 2− contributed to the increased reducibility and decreased surface acidity with the augment of CeO2. The in situ DRIFTS results suggested that suitable surface acidity and reducibility could be offered by increasing the ceria loadings from 24 to 40 wt%. The amount of adsorbed NH3 species, amide species (–NH2) and activated nitrate was increased with the augment of ceria. Excessive addition of CeO2 (80 wt%) resulted in the lacking of surface acid sites and induced the inert nitrate species generation on the catalysts surface.