Solid-phase impregnation promotes Ce doping in TiO2 for boosted denitration of CeO2/TiO2 catalysts

CeO2/TiO2 (denoted as CeTi) catalysts obtained by solid-phase impregnation behaved better in low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR) than that by conventional wet impregnation. To explore the main factors for activity distinction, the texture property, CeO2 dispersion and structure changes of TiO2 were comprehensively analyzed. It was found that surface changes of TiO2 had a significant impact on the improved activity. From results of inductively coupled plasma atomic emission spectrometer (ICP-AES), diffuse reflectance UV–vis spectroscopy (UV–vis-DRS) and Raman, it was inferred that Ce ions were partially incorporated into TiO2 lattice, accompanied with the formation of defects and vacancies during solid-phase impregnation. Accordingly, CeTi catalysts from solid-phase impregnation exhibited superiority in adsorption and activation of reactants. Further result from monitoring the preparation process indicated that the evolved NO played an important role in promoting Ce doping through depriving oxygen atoms on TiO2 surface. The interaction between Ce and Ti was enhanced. The catalyst performed better in NH3-SCR, especially at low temperature, which testified the solid-phase impregnation could be an effective method to modulate interface structure for designing efficient catalyst.