Relationship between SO 2 poisoning effects and reaction temperature for selective catalytic reduction of NO over Mn–Ce/TiO 2 catalyst

Abstract

In this paper, Mn–Ce/TiO 2 was prepared by sol–gel method and used for low-temperature selective catalytic reduction (SCR) of NO with NH 3 in the presence of SO 2 at different temperatures (100–200 °C). SO 2 had a poisoning effect on NO conversion of the Mn–Ce/TiO 2 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/TiO 2 catalyst were seriously sulfated at 200 °C which led to an irreversible deactivation of the sample. While the formation and deposition of (NH 4) 2SO 3 and NH 4HSO 4 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.