Selective Catalytic Reduction of NO by NH3 on CeO2–MOx (M = Ti, Si, and Al) Dual Composite Catalysts: Impact of Surface Acidity

A series of ceria based dual composite oxides were prepared via a co-precipitation method, and we focus on studying the relationships between the catalytic activity and physicochemical properties of ceria based catalysts. It is found that catalytic activity followed the order of CeTi > CeSi > CeAl > pure CeO2; X-ray diffraction indicates that all the ceria based dual composite oxides were the cubic fluorite-type phase of CeO2; the NH3 adsorption–desorption results reveal that the NH3 adsorption stability and amount of CeO2 were improved by modification with TiO2, SiO2, or Al2O3; and the order of surface acidity was in agreement with the order of catalytic activity. Combined with other characterizations, we suppose that surface acidity is a decisive factor in influencing the catalytic activity of ceria based catalysts in the NH3-SCR reaction.