期刊
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
卷 358, 期 -, 页码 134-144出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.molcata.2012.03.008
关键词
DFT; Zeolites; Cu-ZSM-5; NO decomposition; Reaction mechanism; Energetic span model
The present computational study investigates the mechanism of NO decomposition catalyzed by Cu-ZSM-5. It was considered that the active site could be of two kinds: (i) pairs of Cu+ ions located at opposite sides of the ten-membered rings of the zeolite, in the region at the intersection of the linear and sinusoidal channels; (ii) isolated Cu+ ions. DFT calculations were performed by using the B3LYP functional on cluster models suited to reproduce the geometrical constraints of the ZSM-5 structure. It was shown that both the Cu+-pair mechanism and that catalyzed by a single-Cu+ site proceed through the formation of N2O as a reaction intermediate, which further reacts with the oxygen atom of a ZCu-O-CuZ or ZCuO unit (Z = zeolite) to give O-2 + N-2. The latter step displayed a larger activation energy in the Cu+-pair mechanism, which is therefore unfavored although the pathway associated to Cu+-pairs occurs at lower energy. than that associated to a single-Cu+ site. Such a large activation energy is associated to the stability of the ZCu-O-CuZ fragment. A quantitative analysis, performed by means of the energetic span model of Kozuch and Shaik, reinforced the just outlined observations. (C) 2012 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据