Insight into the SO₂ poisoning of heterobimetallic FeCu-SSZ-13 zeolite in NH₃-SCR reaction

The SO2 poisoning of a heterobimetallic FeCu-SSZ-13 in selective catalytic reduction of NO with NH3 (NH3-SCR) was systematically investigated in this study. It was shown that when SO2 is involved in the feeding flue gas, the losses in the redox ability of active metals (primary contributor to deactivation) and in the number of Bronsted acid sites both inhibit the formation of NH4NO2 intermediate, resulting in the rapid deactivation of FeCu-SSZ-13. The SO2 poisoning of FeCu-SSZ-13 at low temperature is more serious than at high temperature, because of the more severe loss of redox ability of active metals. Unlike that of monometallic Cu-/Fe-CHA, the SO(2 )poisoning of the bimetallic one is saliently featured by that partial SO2 is oxidized to SO3 and partial Bronsted acid sites are destroyed due to the formation of H2SO4. This work may provide a fundamental understanding on the SO2 poisoning of heterobimetallic zeolite-based NH3-SCR catalysts.