Activation of ethane in Zn-exchanged zeolites: a theoretical study

文献情報

出版日 2000-01-21

DOI 10.1039/A909426A

インパクトファクター 3.676

著者

Maxim V. Frash, Rutger A. van Santen

原文を見る

要旨

A theoretical study of the mechanism of ethane dehydrogenation catalysed by Zn-doped zeolites was undertaken. The catalyst was modelled by the ring cluster [Al2Si2O4H8]2− coordinated with the Zn2+ ion. The results obtained indicate that the reaction proceeds via a mechanism starting from the ‘‘alkyl’’ rupture of the ethane C–H bond (C2H5δ−–Hδ+), and the zinc cation acts as an acceptor of the alkyl group. The catalytic cycle for the ‘‘alkyl’’ activation consists of three elementary steps: (i) rupture of ethane C–H bond on the Znδ+–Oδ− pair; (ii) formation of ethene from the alkyl group bound to Zn; and (iii) formation of dihydrogen from the Brønsted proton and hydrogen bound to Zn. The computed activation energies for these three steps are 18.4, 53.4 and 20.5 kcal mol−1, respectively. The alternative mechanism starting from the ‘‘carbenium ’’ activation (C2H5δ+–Hδ−), with the zinc cation abstracting the hydride ion, is unfavourable because of the high activation barrier for the first step (67.6 kcal mol−1).

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

Physical Chemistry Chemical Physics (PCCP) is an international journal co-owned by 19 physical chemistry and physics societies from around the world. This journal publishes original, cutting-edge research in physical chemistry, chemical physics and biophysical chemistry. To be suitable for publication in PCCP, articles must include significant innovation and/or insight into physical chemistry; this is the most important criterion that reviewers and Editors will judge against when evaluating submissions. The journal has a broad scope and welcomes contributions spanning experiment, theory, computation and data science. Topical coverage includes spectroscopy, dynamics, kinetics, statistical mechanics, thermodynamics, electrochemistry, catalysis, surface science, quantum mechanics, quantum computing and machine learning. Interdisciplinary research areas such as polymers and soft matter, materials, nanoscience, energy, surfaces/interfaces, and biophysical chemistry are welcomed if they demonstrate significant innovation and/or insight into physical chemistry. Joined experimental/theoretical studies are particularly appreciated when complementary and based on up-to-date approaches.