Remarkable N2-selectivity enhancement of practical NH3-SCR over Co0.5Mn1Fe0.25Al0.75Ox-LDO: The role of Co investigated by transient kinetic and DFT mechanistic studies

被引:87
|
作者
Chen, Sining [1 ]
Vasiliades, Michalis A. [2 ]
Yan, Qinghua [3 ]
Yang, Guangpeng [4 ]
Du, Xuesen [4 ]
Zhang, Cheng [1 ]
Li, Yuran [5 ]
Zhu, Tingyu [5 ]
Wang, Qiang [1 ]
Efstathiou, Angelos M. [2 ]
机构
[1] Beijing Forestry Univ, Coll Environm Sci & Engn, 35 Qinghua East Rd, Beijing 100083, Peoples R China
[2] Univ Cyprus, Heterogeneous Catalysis Lab, Chem Dept, 1 Univ Ave,Univ Campus, CY-2109 Nicosia, Cyprus
[3] Qingdao Agr Univ, Coll Resource & Environm, Qingdao 266109, Peoples R China
[4] Chongqing Univ, Sch Energy & Power Engn, Minist Educ, Key Lab Low Grade Energy Utilizat Technol & Syst, Chongqing 400044, Peoples R China
[5] Chinese Acad Sci, Res Ctr Proc Pollut Control, Natl Engn Lab Hydromet Cleaner Prod Technol, Inst Proc Engn, Beijing 100190, Peoples R China
基金
中国国家自然科学基金;
关键词
LDHs; NH3-SCR; MnOx-based catalyst; Co-based NH3-SCR; Transient kinetics; SELECTIVE CATALYTIC-REDUCTION; LOW-TEMPERATURE NH3-SCR; INITIO MOLECULAR-DYNAMICS; LAYERED DOUBLE HYDROXIDE; OXIDE-BASED CATALYSTS; MIXED-OXIDE; NITRIC-OXIDE; SULFUR RESISTANCE; REACTION PATHWAYS; N-2; SELECTIVITY;
D O I
10.1016/j.apcatb.2020.119186
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A Co0.5Mn1Fe0.25Al0.75Ox-LDO catalyst was developed which showed excellent performance for the low-temperature NH3-SCR. NOx conversions 100% were achieved in the whole 100-250 degrees C range, while after 10-h operation at 150 degrees C with 100 ppm SO2/5 vol% H2O in the feed, the NOx conversion was maintained at 80%. This catalyst provided a much better N-2-selectivity than the Mn1Fe0.25Al0.75Ox-LDO and Mn1Al1Ox-LDO, especially at 150-300 degrees C. It was found that Co0.5Mn1Fe0.25Al0.75Ox possessed higher surface acidity and reducibility, while XPS analyses indicated an electron transfer between Co3+/Co2+ and Mn4+/Mn3+ redox cycles, leading to a much lower N2O formation, supported by Density Functional Theory (DFT) calculations. Detailed analysis of gas responses obtained upon various step-gas switches was performed, which allowed to measure the surface concentration and reactivity of preadsorbed NOx-s and NHx-s leading to N-2 and N2O. Transient kinetic and DFT studies strongly suggested likely mechanisms of NH3-SCR and the critical role of Co for N-2-selectivity enhancement.
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页数:19
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