Getting insights into gas-phase sulfation effect on catalytic performance of praseodymium oxides in NH3-SCR of NO

Sulfation treatment has been widely used to promote the catalytic performance of ceria (CeO2) based catalysts for the selective catalytic reduction of NO by NH3 (NH3-SCR of NO). Praseodymium oxide (PrOx), another commonly used rare earth material with similar structural properties as CeO2, also shows satisfactory redox properties due to the facile redox cycle of Pr3+ ↔ Pr4+. In this work, gas phase sulfation treatment with varied duration was performed on PrOx at 200 °C, and the NH3-SCR activity of sulfated PrOx was evaluated. Based on the results of systematic characterizations (e.g., N2-physisorption, NH3 oxidation, NO oxidation, in situ diffuse Fourier transform infrared spectroscopy), it is revealed that the catalytic performance of sulfated PrOx is highly dependent on the sulfation time (or the amount of sulfate species deposited on PrOx), which has a significant impact on the competitive reaction between NH3 oxidation and NH3-SCR of NO, thus determining the NH3-SCR activity of PrOx. This work provides new insight into tuning the interaction between PrOx surface and reactants (NO, NH3) via sulfation treatment, which cam guide the design and application of PrOx based catalysts for NH3-SCR of NO in the future.