Promotion of MgO addition on SO2 tolerance of Ag/Al2O3 for selective catalytic reduction of NOx with methane at low temperature

The effect of MgO addition on SO2 tolerance of Ag/Al2O3 for the CH4-SCR was investigated. MgO addition significantly decreases the active temperature window of NOx conversion, and promotes the SO2 resistance of Ag/Al2O3 at low temperature range of 573–673 K. Silver oxide particles are well dispersed and large silver crystals are present in Ag/MgAl2O4 catalyst. The slight decrease in catalytic activity over Ag/MgAl2O4 exposure to SO2 is attributed to the partially deactivation of alumina sites poisoned by SO2. MgO may effectively inhibit the competitive adsorption between NOx and SO2 in alumina sites, and enhance SO2 adsorption on the magnesia surface.