SO 2 Poisoning Behaviors of Ca-Mn / TiO 2 Catalysts for Selective Catalytic Reduction of NO with NH 3 at Low Temperature

The sulfur tolerance of Ca modified MnO x /TiO 2 catalysts in low-temperature SCR process was investigated. Experimental results revealed that the durability of developed catalysts in the presence of SO 2 could be improved by Ca modification. After being subjected to a range of analytical techniques, it was found that the surface Ca species could act as a SO 2 trap by preferentially reacting with SO 2 to form bulk-like CaSO 4 , inhibiting the sulfation of active phase. Furthermore, the introduction of SO 2 had also preserved part of Lewis sites over the MnO x . Both of these are conducive to NH 3 adsorption and activation at low temperature, hence improving the sulfur tolerance of Ca doped catalysts.