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“Oxynitride trap” over N/S co-doped graphene-supported catalysts promoting low temperature NH3-SCR performance: Insight into the structure and mechanisms
Journal of Hazardous Materials ( IF 13.6 ) Pub Date : 2021-09-15 , DOI: 10.1016/j.jhazmat.2021.127187
Weijie Zheng 1 , Xiang Zhang 2 , Yuying Zheng 1 , Yuanyuan Yue 3
Affiliation  

A series of nitrogen and sulfur (N/S) co-doped graphene supported catalysts (Mn-Ce-SnOx/NSG) were synthesized using an in situ method for enhancing selective catalytic reduction of NOx with NH3 (NH3-SCR) performance. The changes in catalysts’ structure, morphology, and active sites were systematically researched to explore the promoting effect of N/S co-doped on catalytic performance. The prepared Mn-Ce-SnOx/NSG-0.3 catalyst achieves an excellent SCR activity at a low temperature, which is comparable to previous graphene-based catalysts. The Ce3+/(Ce3+ + Ce4+), Mn4+/Mn3+, and Oα/(Oα + Oβ) ratios in the catalyst are improved by N/S co-doping, which closely related to excellent SCR activity. Meanwhile, the unpaired electrons on N/S functional groups are effective in promoting the adsorption and further oxidation of gaseous NO. The ability to adsorb NH3 has also been promoted result of numerous Lewis acid sites over Mn-Ce-SnOx/NSG-0.3. In-situ DRIFTS and reaction kinetic results suggest that the Eley–Rideal mechanism should be the most significant pathway in the temperature range of ≥ 200 °C, where coordinated NH3 has higher activity than ionic NH4+. The Langmuir-Hinshelwood (L-H) mechanism is the main route of the low-temperature (L-T) (< 200 °C) SCR reaction. Particularly, the L-T SCR activity improves because the N/S functional groups act as an additional “oxynitride trap” (based on the L-H mechanism).



中文翻译:

N/S 共掺杂石墨烯负载催化剂上的“氮氧化物陷阱”促进低温 NH3-SCR 性能:深入了解结构和机制

使用原位方法合成了一系列氮和硫 (N/S) 共掺杂石墨烯负载催化剂 (Mn-Ce-SnO x /NSG) 以增强用 NH 3 (NH 3 -SCR)选择性催化还原 NO x) 表现。系统研究了催化剂结构、形貌和活性位点的变化,探讨了N/S共掺杂对催化性能的促进作用。制备的 Mn-Ce-SnO x /NSG-0.3 催化剂在低温下实现了优异的 SCR 活性,与之前的石墨烯基催化剂相当。Ce 3+ /(Ce 3+ + Ce 4+ )、Mn 4+ /Mn 3+和ON/S共掺杂提高了催化剂中的α /(O α + O β )比,这与优异的SCR活性密切相关。同时,N/S官能团上的未成对电子有效促进气态NO的吸附和进一步氧化。Mn-Ce-SnO x /NSG-0.3 上的许多路易斯酸位点也促进了吸附NH 3的能力。-原位DRIFTS和反应动力学研究结果表明,ELEY-Rideal机构应该在的温度范围内≥200℃,其中协调NH最显著通路3具有比离子NH更高的活性4 +. Langmuir-Hinshelwood (LH) 机制是低温 (LT) (< 200 °C) SCR 反应的主要途径。特别是,LT SCR 活性提高,因为 N/S 官能团充当额外的“氮氧化物陷阱”(基于 LH 机制)。

更新日期:2021-09-22
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