SO2 Poisoning Behaviors of Ca-Mn/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

The sulfur tolerance of Ca modified MnOx/TiO2 catalysts in low-temperature SCR process was investigated. Experimental results revealed that the durability of developed catalysts in the presence of SO2 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 SO2 trap by preferentially reacting with SO2 to form bulk-like CaSO4, inhibiting the sulfation of active phase. Furthermore, the introduction of SO2 had also preserved part of Lewis sites over the MnOx. Both of these are conducive to NH3 adsorption and activation at low temperature, hence improving the sulfur tolerance of Ca doped catalysts.