Study on the mechanism of a manganese-based catalyst for catalytic NOX flue gas denitration

摘要

Manganese-based bimetallic catalysts were prepared with self-made pyrolysis coke as carrier and its denitration performance of low-temperature SCR (selective catalyst reduction) was studied. The effects of different metal species, calcination temperature, calcination time and the metal load quantity on the denitration performance of the catalyst were studied by orthogonal test. The denitration mechanism of the catalyst was analyzed by XRD (X-ray diffraction), SEM (scanning electron microscope), BET test and transient test. The experiments show that: ① The denitration efficiency of Mn-based bimetallic catalysts mainly relates to the metal type, the metal load quantity and the catalyst adjuvant type. ② The optimal catalyst preparation conditions are as follows: the load quantity of monometallic MnO₂ is 10%, calcined at 300°C for 4h, and then loaded with 8% CeO₂, calcined at 350°Cfor 3h. ③ The denitration mechanism of manganese-based bimetallic oxide catalysts is stated as: NH₃ is firstly adsorbed by B acid center Mn-OH which nears Mn4+==O to form NH4+, NH4+ was then attacked by the gas phase NO to form N₂, H₂O and Mn3+-OH. Finally, Mn3+-OH was oxidized by O₂ to regenerate Mn4+.