Effect of metal components on NO removal performance of modified high-content iron fly ash MnCe/HIFACa

Abstract

In this paper, high-content iron fly ash (HIFA) was obtained from coal-fired solid waste fly ash by wet magnetic separation, then it was modified by hydration impregnation method. The denitration performance of modified high-content iron fly ash (MHIFA) was tested in a fixed bed evaluation system, and the effects of Ca, Fe, Mn and Ce on the NO removal ability were studied. The physical and chemical characteristics of HIFAs were analyzed by XRF, XRD, BET, FTIR, XPS, SEM and in situ DRIFTS. The results showed that the MHIFA modified by Mn and Ce (MnCe/HIFACa) has the best denitration ability with the breakthrough time of 171 min and the nitrate capacity of 11.42 mg/g. The denitration process of MnCe/HIFACa includes both chemical reaction and chemisorption, and the former plays a major role. Hydration reaction with CaO not only destroys the dense silicon-aluminum shell of HIFA but also provides active center O–H for NO removal. The interaction of Mn and Ce increases the chemisorbed oxygen (Oα) and lattice oxygen (Oβ), and enhances the oxidation capacity of iron oxide (Fe6+ to Fe3+). NO is oxidized into NO3− and nitrogen exists on the MnCe/HIFACa surface in the form of nitrate finally.