A Study of Mn/Zr modification for NH3-SCR denitration mechanism of rare earth tailings

Mn and Mn/Zr modified rare earth tailings-based NH3-SCR catalysts were prepared using the sol-gel method. The catalysts were characterized using a catalyst activity evaluation system, along with H2-TPR, NH3-TPD, XRD, and DRIFT techniques, to investigate the denitration process and reaction mechanism. The results showed that the denitration activity of the Mn and Mn/Zr modified rare earth tailings catalysts was significantly enhanced, with a denitration activity of 96% achieved at 200°C for the 6%Mn1%Zr/rare earth tailings catalyst. The modified catalysts exhibited increased oxygen vacancies and acidic sites on the surface, as well as a higher adsorption capacity. The increase in reducible surface area of the catalysts contributed to the improvement of their redox performances. The reaction between NH4+ and gaseous NO2 on the acidic sites of the catalysts followed the E-R mechanism, while the reactions between NH4+ and monodentate and bidentate nitrate species followed the L-H mechanism. © 2023 Chinese Society for Environmental Sciences. All rights reserved.