Lotus leaves-derived MnOx/biochar as an efficient catalyst for low-temperature NH3-SCR removal of NOx: effects of modification methods of biochar

In this reported work, lotus leaves-derived biochar (LBC) was modified using various chemical methods. LBC prepared by different modification methods was used as the carrier for the development of low-temperature selective catalytic reduction (SCR) catalysts. A comparative study of low-temperature SCR manganese catalysts based on LBC chemically modified using NaOH, HNO3 and hexadecylcetyltrimethylammonium bromide (CTAB) was performed, revealing different deNO(x) performance of these catalysts. For the supported catalysts, the 25%Mn/LBC-OH catalyst appeared to be optimum since it exhibited over 95% NOx conversion at 225 degrees C with a space velocity of 37 500 h(-1). The microstructure, phase composition, redox properties and surface acidity were determined using field emission scanning electron microscopy, Brunauer-Emmett-Teller surface area, X-ray diffraction, H-2-temperature-programmed reduction, NH3-temperature-programmed desorption, and so forth. The results showed that the excellent SCR performance of 25%Mn/LBC-OH was closely related to its abundant high valence Mn, suitable surface acidity and high redox capability. More importantly, highly dispersed MnOx easily formed on the surface of the LBC-OH support, which was the key factor in the excellent catalytic activity of 25%Mn/LBC-OH catalyst. Furthermore, the highly dispersed 25%Mn/LBC-OH catalyst also exhibited improved tolerance to SO2 and H2O, making this catalyst a good candidate for reducing the NOx emission from coal-fired power plants. (c) 2022 Society of Chemical Industry (SCI).

Automated summary

In this study, lotus leaves-derived biochar (LBC) was modified using various chemical methods and employed as a carrier for low-temperature selective catalytic reduction (SCR) catalysts. A comparative analysis of low-temperature SCR manganese catalysts based on LBC chemically modified with NaOH, HNO3, and CTAB was conducted, revealing different deNO(x) performance. The 25%Mn/LBC-OH catalyst exhibited the best performance with over 95% NOx conversion. The excellent SCR activity of 25%Mn/LBC-OH was attributed to its abundant high valence Mn, suitable surface acidity, and high redox capability. Additionally, the high dispersion of MnOx on the LBC-OH support played a key role in the catalyst's outstanding catalytic activity. Moreover, the 25%Mn/LBC-OH catalyst also displayed improved tolerance to SO2 and H2O, making it a promising candidate for reducing NOx emissions from coal-fired power plants.