Facile H₂O-Contributed O₂Activation Strategy over Mn-Based SCR Catalysts to Counteract SO₂Poisoning

Abstract

Mn-based catalysts preferred in low-temperature selective catalytic reduction (SCR) are susceptible to SO 2 poisoning. The stubborn sulfates make insufficient O 2 activation and result in deficient reactive oxygen species (ROS) for activating reaction molecules. H 2 O has long been regarded as an accomplice to SO 2, hastening catalyst deactivation. However, such a negative impression of the SCR reaction was reversed by our recent research. Here, we reported a H 2 O contribution over Mn-based SCR catalysts to counteract SO 2 poisoning through accessible O 2 activation, in which O 2 was synergistically activated with H 2 O to generate ROS for less deactivation and more expected regeneration. The resulting ROS benefited from the energetically favorable route supported by water-induced E a reduction and was actively involved in the NH 3 activation and NO oxidation process. Besides, ROS maintained high stability over the SO 2 + H 2 O-deactivated γ-MnO 2 catalyst throughout the mild thermal treatment, achieving complete regeneration of its own NO disposal ability. This strategy was proven to be universally applicable to other Mn-based catalysts.