Premium
Methane Activation by Diatomic Molybdenum Carbide Cations
Author(s) -
Li ZiYu,
Yuan Zhen,
Zhao YanXia,
He ShengGui
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201304042
Subject(s) - dehydrogenation , chemistry , oxidative coupling of methane , methane , ethylene , catalysis , carbide , molybdenum , inorganic chemistry , photochemistry , organic chemistry
Metal carbide species have been proposed as a new type of chemical entity to activate methane in both gas‐phase and condensed‐phase studies. Herein, methane activation by the diatomic cation MoC + is presented. MoC + ions have been prepared and mass‐selected by a quadrupole mass filter and then allowed to interact with methane in a hexapole reaction cell. The reactant and product ions have been detected by a reflectron time‐of‐flight mass spectrometer. Bare metal Mo + and MoC 2 H 2 + ions have been observed as products, suggesting the occurrence of ethylene elimination and dehydrogenation reactions. The branching ratio of the C 2 H 4 elimination channel is much larger than that of the dehydrogenation channel. Density functional theory calculations have been performed to explore in detail the mechanism of the reaction of MoC + with CH 4 . The computed results indicate that the ethylene elimination process involves the occurrence of spin conversions in the CC coupling (doublet→quartet) and hydrogen atom transfer (quartet→sextet) steps. The carbon atom in MoC + plays a key role in methane activation because it becomes sp 3 hybridized in the initial stages of the ethylene elimination reaction, which leads to much lower energy barriers and more stable intermediates. This study provides insights into the CH bond activation and CC coupling involved in methane transformation over molybdenum carbide‐based catalysts.