Industrial & Engineering Chemistry Research, Vol.58, No.51, 22763-22770, 2019
Mechanism and Kinetics Study on Low-Temperature NH3-SCR Over Manganese-Cerium Composite Oxide Catalysts
Titanium dioxide-supported manganese oxide and cerium oxide noted as MnOx/TiO2, CeO2/TiO2, and MnOx-CeO2/TiO2 were prepared by sol gel method and their low-temperature (<200 degrees C) catalytic activity toward selective catalytic reduction (SCR) of NO with NH3 were evaluated. The MnOx-CeO2/TiO2 catalyst exhibited optimal low-temperature performance that is nearly 98% of NO was abated below 200 degrees C. That is because MnOx/TiO2 combined with CeO2 improves redox ability and surface acidity of the catalyst, mainly due to the incorporation of Mn atoms into bulk CeO2 that creates active Mn-O-Ce structures. In situ Fourier transform infrared (FTIR) spectroscopy suggested that the coordinated NH3 on Lewis acid sites were favored to react with NO and the NH3-SCR over MnOx-CeO2/TiO2 catalyst mainly followed the E-R mechanism at 200 degrees C. Furthermore, the reaction rate constant and apparent activation energy of the NH3-SCR reaction on the MnOx-CeO2/TiO2 catalyst confirmed the promotional effects of Ce addition on the activity of Mn-based catalyst.