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Mechanistic Insight into the Promotion of the Low-Temperature NH3–SCR Activity over NiMnFeOx LDO Catalysts: A Combined Experimental and DFT Study
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2023-11-30 , DOI: 10.1021/acs.est.3c06849 Qinghua Yan 1 , Jiewen Xiao 2 , Rongrong Gui 2 , Zhenyu Chen 1 , Yuran Li 3 , Tingyu Zhu 3 , Qiang Wang 2 , Yanjun Xin 1
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2023-11-30 , DOI: 10.1021/acs.est.3c06849 Qinghua Yan 1 , Jiewen Xiao 2 , Rongrong Gui 2 , Zhenyu Chen 1 , Yuran Li 3 , Tingyu Zhu 3 , Qiang Wang 2 , Yanjun Xin 1
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Mn-based catalysts have attracted much attention in the field of the low-temperature NH3 selective catalytic reduction (NH3–SCR) of NO. However, their poor SO2 resistance, low N2 selectivity, and narrow operation window limit the industrial application of Mn-based oxide catalysts. In this work, NiMnFeOx catalysts were prepared by the layered double hydroxide (LDH)-derived oxide method, and the optimized Ni0.5Mn0.5Fe0.5Ox catalyst had the best denitration activity, excellent N2 selectivity, a wider active temperature range (100–250 °C), higher thermal stability, and better H2O and/or SO2 resistance. A transient reaction revealed that Ni0.5Mn0.5Fe0.5Ox inhibited the NH3 + O2 + NOx pathway to generate N2O, which may be the main reason for its improved N2 selectivity. Combining experimental measurements and density functional theory (DFT) calculations, we elucidated at the atomic level that sulfated NiMnFeOx (111) induces the adjustment of the acidity/basicity of up and down spins and the ligand field reconfiguration of the Mn sites, which improves the overall reactivity of NiMnFeOx catalysts. This work provides atomic-level insights into the promotion of NH3–SCR activity by NiMnFeOx composite oxides, which are important for the practical design of future low-temperature SCR technologies.
中文翻译：
NiMnFeOx LDO 催化剂促进低温 NH3-SCR 活性的机理洞察：实验和 DFT 相结合的研究
锰基催化剂在低温NH 3选择性催化还原(NH 3 –SCR)NO领域备受关注。然而，其耐SO 2性能差、N 2选择性低、操作窗口窄限制了锰基氧化物催化剂的工业应用。本工作采用层状双氢氧化物(LDH)衍生氧化物法制备了NiMnFeO x催化剂,优化后的Ni 0.5 Mn 0.5 Fe 0.5 O x催化剂具有最佳的脱硝活性、优异的N 2选择性、更宽的活性温度范围。 (100–250 °C)，更高的热稳定性，以及更好的抗 H 2 O 和/或 SO 2性能。瞬态反应表明Ni 0.5 Mn 0.5 Fe 0.5 O x抑制NH 3 + O 2 + NO x途径生成N 2 O，这可能是其提高N 2选择性的主要原因。结合实验测量和密度泛函理论（DFT）计算，我们在原子水平上阐明了硫酸化NiMnFeO x (111)诱导了上下自旋酸碱度的调整以及Mn位点的配体场重构，从而改善了NiMnFeO x催化剂的总体反应活性。 这项工作为NiMnFeO x复合氧化物促进NH 3 –SCR 活性提供了原子级的见解，这对于未来低温SCR 技术的实际设计非常重要。
更新日期：2023-11-30
中文翻译：
NiMnFeOx LDO 催化剂促进低温 NH3-SCR 活性的机理洞察：实验和 DFT 相结合的研究
锰基催化剂在低温NH 3选择性催化还原(NH 3 –SCR)NO领域备受关注。然而，其耐SO 2性能差、N 2选择性低、操作窗口窄限制了锰基氧化物催化剂的工业应用。本工作采用层状双氢氧化物(LDH)衍生氧化物法制备了NiMnFeO x催化剂,优化后的Ni 0.5 Mn 0.5 Fe 0.5 O x催化剂具有最佳的脱硝活性、优异的N 2选择性、更宽的活性温度范围。 (100–250 °C)，更高的热稳定性，以及更好的抗 H 2 O 和/或 SO 2性能。瞬态反应表明Ni 0.5 Mn 0.5 Fe 0.5 O x抑制NH 3 + O 2 + NO x途径生成N 2 O，这可能是其提高N 2选择性的主要原因。结合实验测量和密度泛函理论（DFT）计算，我们在原子水平上阐明了硫酸化NiMnFeO x (111)诱导了上下自旋酸碱度的调整以及Mn位点的配体场重构，从而改善了NiMnFeO x催化剂的总体反应活性。 这项工作为NiMnFeO x复合氧化物促进NH 3 –SCR 活性提供了原子级的见解，这对于未来低温SCR 技术的实际设计非常重要。
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