甲烷
激进的
溴
催化作用
化学
卤化
反应机理
甲烷厌氧氧化
X射线光电子能谱
物理化学
光化学
有机化学
化学工程
工程类
作者
Vladimir Paunović,Patrick Hemberger,Andras Bodi,Núria López,Javier Pérez‐Ramírez
出处
期刊:Nature Catalysis
[Springer Nature]
日期:2018-05-11
卷期号:1 (5): 363-370
被引量:39
标识
DOI:10.1038/s41929-018-0071-z
摘要
Unravelling the pathways of catalytic methane functionalization sets the foundations for the efficient production of valuable chemicals and fuels from this abundant feedstock. The catalytic oxybromination of methane into platform compounds bromomethane and dibromomethane constitutes a prominent example, although it displays a puzzling reaction network that has been speculated to involve free-radical intermediates. Here, photoelectron photoion coincidence spectroscopy with synchrotron radiation was used to provide evidence of the evolution of gaseous methyl and bromine radicals over (VO)2P2O7 and EuOBr catalysts and the strong correlation between the formation of methyl radicals and the production of bromomethanes. Complemented by kinetic data on methane oxybromination and non-catalytic methane bromination, these results imply the surface-catalysed generation of bromine radicals and molecular bromine followed by the gas-phase methane bromination, which is rationalized by density functional theory calculations. The findings emphasize the role of both surface and gas-phase steps in halogen-mediated C–H bond activation over heterogeneous catalysts. Catalytic oxybromination is an important strategy for the upgrade of methane. Here, Pérez-Ramírez and co-workers employ operando photoelectron photoion coincidence spectroscopy as well as kinetic analyses and molecular simulations to unravel the complex reaction mechanism.
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