Relationship between SO2 poisoning effects and reaction temperature for selective catalytic reduction of NO over Mn–Ce/TiO2 catalyst

In this paper, Mn–Ce/TiO2 was prepared by sol–gel method and used for low-temperature selective catalytic reduction (SCR) of NO with NH3 in the presence of SO2 at different temperatures (100–200 °C). SO2 had a poisoning effect on NO conversion of the Mn–Ce/TiO2 catalyst and this effect was directly related with reaction temperature. The higher the reaction temperature, the more rapidly the catalyst activity decreased. The results of in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectroscopy and temperature programmed desorption (TPD) profiles indicated that the active sites of the Mn–Ce/TiO2 catalyst were seriously sulfated at 200 °C which led to an irreversible deactivation of the sample. While the formation and deposition of (NH4)2SO3 and NH4HSO4 were the main causes of catalyst deactivation when the SCR reaction was carried out at 100 °C. This kind of deactivation could be almost completely recovered after water-washing treatment.