Thulium oxides supported on MnCeTiO_X catalysts for low-temperature NH₃-SCR of NO_X

Abstract

In this work, the MnCeTiOX catalyst was prepared by sol-gel method and doped with thulium (Tm), which improved its low-temperature selective catalytic reduction (SCR) activity and resistance to SO2 poisoning. In this paper, the surface properties of Tm-doped MnCeTiOX catalysts were studied and analysed by means of BET, XRD, SEM, NH3-TPD, H2-TPR and XPS. The catalyst performance was tested by using simulated flue gas. The results show that Tm doping can effectively inhibit the crystallization degree of TiO2, increase the catalyst specific surface area, and make the elements distribute more uniformly on the catalyst surface. Meanwhile, the amount of Brønsted acid sites could be increased by Tm doping. It also increased the concentration of surface adsorbed oxygen and the ratio of Mn4+/Mn and Ce3+/Ce. Therefore, the activity of the catalyst was improved by Tm doping in the temperature range of 90 °C to 270 °C, the catalyst activity remained above 97% in the temperature range of 180 °C to 270 °C. And the catalyst activity remained above 88% after a 10 h-SO2 poisoning test. Tm doping could effectively inhibit SO2 poisoning of the catalyst and reduce the adsorption of SO2 on the catalyst surface.