| Summary: | A series of Ce<sub>x</sub>-Mn-Ti<sub>y</sub> catalysts were synthesized using the coprecipitation method, and sodium carbonate solution was used as a precipitant. The various catalysts were assessed by selective catalytic reduction of NO<sub>x</sub> with NH<sub>3</sub>, and characterized by X-ray diffraction, Raman spectroscopy, H<sub>2</sub> temperature-programmed reduction, NH<sub>3</sub> temperature-programmed desorption, and X-ray photoelectron spectroscopy to investigate the physicochemical properties, surface acidity, and redox abilities of the Ce<sub>x</sub>-Mn-Ti<sub>y</sub> catalysts. The Ce<sub>0.1</sub>-Mn-Ti<sub>0.1</sub> catalyst exhibited the best catalytic performance (more than 90% NO<sub>x</sub> conversion in the range of 75 to 225 °C), as a result of proper redox ability, abundant acid sites, high content of Mn<sup>4+</sup> and Ce<sup>3+</sup>, and surface-adsorbed oxygen (O<sub>S</sub>). The results of in situ DRIFT spectroscopy showed that the NH<sub>3</sub>-SCR reaction followed both the E-R and L-H paths over the Ce<sub>0.1</sub>-Mn-Ti<sub>0.1</sub> catalyst, and it occurred faster and more sharply when it mainly abided by the E-R mechanism.
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