LAUSR

The different forms of Ca (CaCl2 and Ca(OH)2) poisoned manganese and cerium oxides supported on TiO2 catalysts were prepared by impregnation method and used for selective catalytic reduction (SCR) of NO with NH3. The Ca poisoning effects were investigated by many characterization methods including N2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, H2-temperature programmed reduction and NH3-temperature programmed desorption techniques. The results showed that the addition of Ca led to greatly decrease of catalytic activity of catalysts and the catalytic activity was ranked in the order: CaCl2 poisoned catalyst < Ca(OH)2 poisoned catalyst < fresh catalyst, which indicated that the poisoning effect of different forms of Ca was different and the deactivation caused by CaCl2 was more serious. The characterization results demonstrated the addition of Ca greatly decreased the specific surface area of catalysts, the contents of surface active species (Mn4+ and Ce3+), the amounts of weak Brønsted acid sites and the low-temperature redox ability, especially for the CaCl2 poisoned catalyst, all of which led to the weaken of the catalytic activity of catalysts.