Oxide Catalysts with Ultrastrong Resistance to SO₂ Deactivation for Removing Nitric Oxide at Low Temperature

Abstract

Nitrogen oxides are one of the major sources of air pollution. To remove these pollutants originating from combustion of fossil fuels remains challenging in steel, cement, and glass industries as the catalysts are severely deactivated by SO₂ during the low-temperature selective catalytic reduction (SCR) process. Here, a MnO_X /CeO₂ nanorod catalyst with outstanding resistance to SO₂ deactivation is reported, which is designed based on critical information obtained from in situ transmission electron microscopy (TEM) experiments under reaction conditions and theoretical calculations. The catalysts show almost no activity loss (apparent NO_X reaction rate kept unchanged at 1800 µmol g^-1 h^-1 ) for 1000 h test at 523 K in the presence of 200 ppm SO₂ . This unprecedented performance is achieved by establishing a dynamic equilibrium between sulfates formation and decomposition over the CeO₂ surface during the reactions and preventing the MnO_X cluster from the steric hindrance induced by SO₂ , which minimized the deactivation of the active sites of MnO_X /CeO₂ . This work presents the ultralong lifetime of catalysts in the presence of SO₂ , along with decent activity, marking a milestone in practical applications in low-temperature selective catalytic reduction (SCR) of NO_X .