LAUSR

Abstract The different poisoning mechanisms of Cl and P on Mn/TiO 2 catalyst for selective catalytic reduction of NO x with NH 3 were investigated in this study. It was found that the poisoning effect of P was stronger than that of Cl, and the poisoning effect of Cl was very weak when the reaction temperature was over 250 °C. And the presence of Cl or P would weaken the poisoning effect of SO 2 and H 2 O. From the characterization results of temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS), the loading of P and Cl would lead to the decrease of reducible species and the loss of Mn 4+ and chemisorbed oxygen species, as a result, inhibiting the oxidation of NO to NO 2 .The results of temperature programmed desorption (TPD) study indicated that the presence of Cl only had a weak inhibition effect on the adsorption of NH 3 and NO x species over Mn/TiO 2 catalyst, while the addition of P on Mn/TiO 2 catalyst would greatly suppress the adsorption of NH 3 and NO x species. From the results of in situ DRIFT study, it could be found that the NH 3 –SCR reaction over Mn/TiO 2 catalyst was mainly controlled by L–H mechanism at lower temperature range (≤ 200 °C) and E–R mechanism at higher temperature range (≥ 250 °C). For Mn/TiO 2 Cl, the deactivation was mainly caused by the prohibited NO oxidation; while for Mn/TiO 2 P, the deactivation was mainly due to the seriously suppressed NO oxidation and NH 3 adsorption.