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Mechanistic insights into the influence of preparation methods and Fe 3+ doping on the low-temperature performance of MnCeO x catalyst for NH 3-SCR reaction
Zhang, Xiaoxiao1,2,3; Cao, Jun1,2,3; Tian, Shihong1,2,3; Zhao, Yongchang1,2,3; Long, Lulu1,2; Yao, Xiaojiang1,2,3,4
2024-11-11
摘要Aiming to polish up the denitrification efficiency and N2 selectivity for MnCeOx catalyst at low temperature, an array of Fe3+-doped MnCeOx catalysts were synthesized through innovative approaches: the citric acid method (FeMnCeOx-CA) and CTAB-assisted template method (FeMnCeOx-ST). However, the catalysts prepared by CTABassisted template method (MnCeOx-ST and FeMnCeOx-ST catalysts) did not exhibit an excellent low-temperature activity compared with the catalysts made by citric acid method (MnCeOx-CA and FeMnCeOx-CA catalysts) below 300 degrees C. Therefore, an in-depth investigation of underlying impact of citric acid method and Fe3+ doping on MnCeOx catalyst was thoroughly implemented. We finally found that the main function of citric acid is to enhance the internal electron transfer of the catalyst by facilitating the mutual conversion between active components, particularly Mn4+/Mn3+, thereby improving the denitrification activity of FeMnCeOx-CA catalyst at low temperature. Further, the NH3-SCR performance of FeMnCeOx-CA exceed 90 % NOx conversion within 75-150 degrees C, and it can be reached 94 % NOx conversion at 125 degrees C, which was almost 10 % higher than that of MnCeOx-CA catalyst. Moreover, the N2O formation of FeMnCeOx-CA is significantly suppressed at temperatures ranging from 125-200 degrees C, exhibiting a higher N2 selectivity compared to MnCeOx-CA. Besides, solid solution structure of -Ce-O-Mn-O-Fe- formed after Fe3+ doping in MnCeOx catalyst strengthened surface acidity and redox ability over FeMnCeOx-CA catalyst, promoting NH3 adsorption and activation. On the other hand, the FeMnCeOx-CA catalyst exhibits the highest content of Ce3+ and Mn4+, facilitating oxygen vacancies formation and redox capacity, thereby promoting the key intermediates generation in the microscopic NH3-SCR reaction process. Finally, a reasonable Langmuir-Hinshelwood mechanism and detailed reaction pathways of NH3-SCR reaction existed on FeMnCeOx-CA catalyst were also proposed.
关键词MnCeOx catalyst Fe3+doping Low-temperature denitrification NH3-SCR reaction
DOI10.1016/j.seppur.2024.127519
发表期刊SEPARATION AND PURIFICATION TECHNOLOGY
ISSN1383-5866
卷号347页码:13
通讯作者Yao, Xiaojiang(yaoxj@cigit.ac.cn)
收录类别SCI
WOS记录号WOS:001233703500001
语种英语