Journal ArticleDOI
Catalytic cycle of the partial oxidation of methane to methanol over Cu-ZSM-5 revealed using DFT calculations.
TLDR
In this article, a density functional theory (DFT) analysis was performed to investigate the catalytic cycle of methane conversion to methanol over both [Cu2(O2)]2+ and [cu2(μ-O)]2+) active sites in the Cu-ZSM-5 catalyst.Abstract:
Density functional theory (DFT) calculations were performed to investigate the catalytic cycle of methane conversion to methanol over both [Cu2(O2)]2+ and [Cu2(μ-O)]2+ active sites in the Cu-ZSM-5 catalyst. The [Cu2(O2)]2+ site is found to be active for the partial oxidation of methane to methanol, and although it has a higher energy barrier in the methane activation step, it involves a very low energy barrier in the methanol formation step (36.3 kJ mol-1) as well as a lower methanol desorption energy (52.5 kJ mol-1). As the [Cu2(O2)]2+ active site is also thermodynamically stable, it may play an important role during methane conversion to methanol. Furthermore, the methane activation step follows the homolytic route and the heterolytic route for the [Cu2(O2)]2+ and [Cu2(μ-O)]2+ active sites, respectively, whereas the methanol formation step follows the direct radical rebound mechanism and the indirect rebound mechanism, respectively. Our calculations further indicate that the electronic properties of the reactive O atoms in the active site influence their reactivity toward methane oxidation. More specifically, the higher the spin density and the more negative the charge of the reactive O atom at the active site are, the lower the energy barrier for methane activation will be; and the more negative the charge of the hydroxyl group in the reaction intermediate during the partial oxidation of methane to methanol is, the higher energy barrier of the methanol formation step will be in the triplet state. Furthermore, we used a larger cluster model to predict the mechanism of the methane activation step and the effect of atomic charge of the O atom at the [Cu2(μ-O)]2+ and [Cu2(O2)]2+ active sites on the energy barriers of partial oxidation of methane to methanol, and the conclusions drawn employing the larger cluster model are consistent with those drawn using the smaller double-5T-ring cluster model. In addition, different from the traditional mechanism for methane activation at [Cu2(O2)]2+, which consists of two transition states, we find that the partial oxidation of methane at [Cu2(O2)]2+ can also occur via a single step by direct insertion of one of the O atoms at the active site into the C-H bond of methane.read more
Citations
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Research progress on methane conversion coupling photocatalysis and thermocatalysis
Journal ArticleDOI
Identifying the crucial role of water and chloride for efficient mild oxidation of methane to methanol over a [Cu2(μ-O)]2+-ZSM-5 catalyst
TL;DR: In this paper , a single metal [Cu2(μ-O)]2+-ZSM-5 catalyst can activate methane to methanol with superior high selectivity up to 91.3% in C1 oxygenates and 12.31 molmethanol kgcat-1h−1 by avoiding over-oxidation.
Mechanistic Insights into Direct Methane Oxidation to Methanol on Single-Atom Transition-Metal-Modified Graphyne
Lakshitha Jasin Arachchige,Lakshitha Jasin Arachchige,Ani Dong,Tianyi Wang,Tianyi Wang,Huan Li,Xiaoli Zhang,Feng Wang,Hai-Yan Su,Chenghua Sun +9 more
Journal ArticleDOI
Distinct Behaviors of Cu- And Ni-ZSM-5 Zeolites toward the Post-activation Reactions of Methane
Muhammad Haris Mahyuddin,Seiya Tanaka,Ryotaro Kitagawa,Arifin Luthfi Maulana,Adhitya Gandaryus Saputro,Mohammad Kemal Agusta,Hadi Teguh Yudistira,Hermawan Kresno Dipojono,Kazunari Yoshizawa +8 more
Journal ArticleDOI
Effect of ZSM–5 with different active centers on methane partial oxidation
Zhongzhong Xue,Panyue Liu,Ning Li,Lixia Ling,Ping Liu,Xiao-Fang Shen,Riguang Zhang,Baojun Wang +7 more
TL;DR: In this article , the authors used the density functional theory (DFT) method to find the catalysts with high activity and high selectivity to meethanol for the formation of methanol.
References
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