Effect of praseodymium additive on CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3

A series of praseodymium added CeO2(ZrO2)/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction (XRD), N-2-brumauer-emmett-teller (N-2-BET), NH3-temperature programmed desorption (NH3-TPD), H-2-temperature programmed reduction (H-2-TPR), PL spectra, Raman spectra, electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), respectively. Influence of preparation method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO2(ZrO2)/TiO2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO2 forming the structure of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce3+ species, which was favourable for higher catalytic activity.