Effects of zeolite framework topology on Cu(I) oxidation and Cu(II) reduction kinetics of NOx selective catalytic reduction with NH3
Effects of zeolite framework topology on Cu(I) oxidation and Cu(II) reduction kinetics of NOx selective catalytic reduction with NH3
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DOI：
10.1016/j.checat.2023.100726
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发表时间：
2023-09-21
期刊：
影响因子：
--
通讯作者：
Gounder，Rajamani
中科院分区：
文献类型：
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作者：
Deluca，Mykela;Jones，Casey B.;Gounder，Rajamani
氮氧化物的低温(<；523K)选择性催化还原(SCR)是在铜沸石上进行的。铜阳离子被NH3溶剂化，与骨架铝中心相连，并在微孔内部分移动，影响了铜离子在空穴内配对的能力，从而关闭了SCR氧化半周期。沸石骨架的拓扑特征对配伍性和铜归一化SCR反应活性的影响还不是很清楚。我们结合稳态动力学和分子筛上的过氧键和瞬时X射线吸收(XAS)测量，探讨了孔结构和维度对SCR活性铜中心的SCR速率常数和分数的影响，并结合统计模拟和从头算动力学模拟，表明3D笼窗分子筛中孔大小和形状的变化对铜离子配对和SCR反应活性有微妙的影响，但孔维度降低到2D或1D网络对铜离子配对和SCR反应活性施加了更严格的限制。
The low-temperature (<523 K) selective catalytic reduction (SCR) of nitrogen oxides proceeds on Cu-zeolites. Cu cations are NH3solvated, ionically tethered to framework Al centers, and partially mobile within microporous voids, influencing the ability of Cu ions to pair within voids to close the SCR oxidation half-cycle. The influence of zeolite framework topological features on pairability and Cu-normalized SCR reactivity is not well understood. We combine steady-state kinetics andoperandoand transient X-ray absorption (XAS) measurements on Cu-zeolites chosen to probe the influence of pore structure and dimensionality on SCR rate constants and fractions of SCR-active Cu sites, together with statistical simulations andab initiodynamics simulations, to show that changes in pore size and shape among 3D cage-window zeolites have subtle effects on Cu ion pairability and SCR reactivity but that decreasing pore dimensionality to 2D or 1D networks imposes more severe restrictions on Cu ion pairability and SCR reactivity.