The poisoning effect of sintering dust on V 2 O 5 –WO 3 /TiO 2 catalyst for NO x removal in iron ore sintering flue gas

NOx from iron ore sintering flue gas can be removed by selective catalytic reduction (SCR) over V2O5–WO3/TiO2 (VWTi) catalyst. In this work, the poisoning effects of K2SO4 and CaSO4 on the VWTi catalyst were investigated. The SCR activities and physicochemical properties of the fresh and poisoned catalysts were characterized. The results confirmed the deactivation of the poisoned catalysts, and the SCR activity decreased with increasing the concentration of the doped poisoning precursors. This reduced SCR activity could be related to the decreased reducibility of vanadium species and lower content of surface chemisorbed oxygen. Characterization of the poisoned catalysts showed migration of V 2p3/2 towards lower binding energy, reduced amount of NH3 desorption, and elimination of V=O stretching vibration bond, which could be attributed to the extension of V=O bond, consequently leading to the formation of –V–O–Ca/K bonds. A possible poisoning mechanism of the VWTi catalyst was proposed and discussed.