Low-temperature selective catalytic reduction of NO with NH3over Mn-Ce-Ox/TiO2: a comparison between catalyst preparation methods

Three Mn-Ce-O-x/TiO(2)mixed oxides (MCT) were prepared by sol-gel (SG), citric acid complexing (CA), and co-precipitation (CP) methods and used as catalysts for selective catalytic reduction of NO with NH3(NH3-SCR) at low temperatures (75-200 degrees C). The physicochemical properties of the prepared catalysts were investigated by N(2)adsorption, X-ray diffraction (XRD), temperature-programmed reduction by H-2(H-2-TPR), adsorption of NH(3)and NO followed by temperature-programmed desorption (NH3/NO-TPD), X-ray photoelectron spectroscopy (XPS), and in situ diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy. The results show that both the low-temperature de-NO(x)activity and the resistance to SO(2)poisoning of the Mn-Ce-O-x/TiO(2)catalyst decrease in the order of MCT-CP > MCT-SG > MCT-CA. These disparities can be mainly attributed to the difference in specific surface area, fractions of Mn4+(Mn4+/(Mn2++Mn3++Mn4+)) and surface adsorbed oxygen (surface adsorbed oxygen/(surface adsorbed oxygen + lattice oxygen)) species, and the adsorption capacity for NH(3)and NO of the different catalysts. The effect of preparation methods (sol-gel, citric acid complexing, and co-precipitation) on the performance of Mn-Ce-O-x/TiO(2)catalyst was investigated. The catalyst prepared by co-precipitation exhibits higher low-temperature activity and better SO(2)resistance than the counterparts prepared by the other two methods.