Mechanism of SO/HO enhanced rare earth tailings catalysts in NH-SCR at medium and high temperature.

Rare earth tailings (RET) NH-SCR catalysts were prepared by mechanical and microwave activation of a large amount of rare earth tailings after beneficiation of Bayan Ebo rare earth ore. The effects of SO/HO on the denitrification performance of the RET catalysts were evaluated by conducting denitrification activity tests, SO/HO tolerance tests and DRIFTs mechanistic analysis. The results showed that the denitrification activity was significantly increased in the presence of SO/HO. And DRIFTs analysis showed that in the presence of SO/HO, SO could be adsorbed as SO groups by the hydroxyl groups on the catalyst surface and react with SO to form SO species. And in the presence of NH, SO would decompose into unstable SO species and SO and continue to react cyclically to form SO species, providing the RET catalyst provides more acid sites, facilitating the SCR reaction.