Activation of oxygen on (NH3-Cu-NH3)+ in NH3-SCR over Cu-CHA
Activation of oxygen on (NH3-Cu-NH3)+ in NH3-SCR over Cu-CHA
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DOI：
10.1016/j.jcat.2017.12.009
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发表时间：
2018-02-01
影响因子：
7.3
通讯作者：
Gronbeck, Henrik
中科院分区：
文献类型：
--
作者：
Chen, Lin;Falsig, Hanne;Gronbeck, Henrik
Cu-CHA材料是氧过量条件下NH3-SCR还原NOx的有效催化剂。反应中的一个关键步骤是氧(O-2)的活化，这一点目前还不清楚。本文采用密度泛函理论计算，结合从头算热力学和分子动力学，研究了在NH3-SCR条件下存在的Cu(NH3)(2)(+)物种上O-2的离解反应。O-2在一对铜(NH3)(2)(+)络合物上容易直接解离，而在单一的铜(NH3)(2)(+)络合物上由于较高的活化能而不容易解离。NO的存在促进了铜(NH3)(2)(+)络合物的氧离解。亚硝酸盐和硝酸盐很容易形成O-2解离，而NO在硝酸盐上的吸附导致NO2的容易形成。这些结果强调了配体稳定的铜物种在NH3-SCR催化剂中的重要性。2017爱思唯尔公司版权所有。
Cu-CHA materials are efficient catalysts for NH3-SCR of NOx in oxygen excess. A crucial step in the reaction is oxygen (O-2) activation, which still is not well understood. Density functional theory calculations in combination with ab initio thermodynamics and molecular dynamics are here used to study O-2 dissociation on Cu(NH3)(2)(+) species, which are present under NH3-SCR conditions. Direct dissociation of O-2 is found to be facile over a pair of Cu(NH3)(2)(+) complexes whereas dissociation on a single Cu(NH3)(2)(+) species is unlikely due to a high activation energy. The presence of NO promotes oxygen dissociation on both single and pairs of Cu(NH3)(2)(+) complexes. Nitrites and nitrates are easily formed as O-2 dissociates, and NO adsorption over nitrates leads to facile formation of NO2. The results stress the importance of ligand-stabilized Cu species in Cu-CHA catalysts for NH3-SCR. 2017 Elsevier Inc. All rights reserved.