Effect of different doping elements on performance of Ce–Mn/TiO2 catalyst for low temperature denitration

Abstract

Sm and Ho were doped in Ce–Mn/TiO2 catalyst respectively to enhance its denitration performance at low temperature. X-ray diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques were used to analyze the structure and performance of catalysts. The results demonstrate that Ho doping increases the amount of acid sites and improves low temperature redox property of Ce–Mn/TiO2, which lead to excellent DeNOx performance of Ho-Ce-Mn/TiO2 in the whole reaction temperature range. Sm doping results in decline of redox property, but it is beneficial to increasing the acid sites of Ce–Mn/TiO2. The increased surface acid sites and moderate oxidative ability impart Sm-Ce-Mn/TiO2 higher denitration activity and N2 selectivity at temperature above 150 °C. Lewis acid sites and redox property are the main factors affecting the activity of catalysts. Doping of Ho and Sm both improves sulfur resistance performance of Ce–Mn/TiO2 by inhibiting the adsorption of SO2 and formation of sulfate. Ce–Mn/TiO2 modified by Ho shows better sulfur resistance than that doped with Sm because of its more surface acid sites.