Facilitating mechanisms of activity and SO2/H2O tolerance on ZrVOx catalysts for selective catalytic reduction of NOx removal with NH3

Abstract

Sulfur oxides originated from high sulfur content in heavy fuel oil, which deleteriously impacting the catalysts during the NH₃-SCR under low temperatures conditions. In this study, a ZrVO_x catalyst with good low-temperature performance and resistance to SO₂/H₂O was synthesized via hydrothermal method for NH₃-SCR. With the introduction of SO₂ and H₂O at 230 °C, the NO_x conversion rate remained stable at 94 %. After characterization analysis, it was ascertained that the ZrVO_x catalyst possessed a finely porous structure, expansive specific surface area, and strong low-temperature redox capability. Simultaneously, SO₂ had minimal impact on the efficient adsorption of reactants., and deposited sulfate gradually decomposed with increasing temperature, mitigating the catalytic inhibition of SO₂. The addition of H₂O enhanced the concentration of surface active oxygen species (ROS) over the catalyst surface, increasing the surface hydroxyl groups and counteracted the negative impact of SO₂ poisoning. Moreover, the in situ DRIFTs results confirmed that the catalytic reactions on ZrVO_x primarily followed the Eley-Rideal (E-R) mechanism.