Illustrating the Fate of Methyl Radical in Photocatalytic Methane Oxidation over Ag-ZnO by in situ Synchrotron Radiation Photoionization Mass Spectrometry.
Angew Chem Int Ed Engl
; 62(32): e202304352, 2023 Aug 07.
Article
em En
| MEDLINE
| ID: mdl-37219500
ABSTRACT
Photocatalysis has emerged as an ideal method for the direct activation and conversion of methane under mild conditions. In this reaction, methyl radical (â
CH3 ) was deemed a key intermediate that affected the yields and selectivity of the products. However, direct observation of â
CH3 and other intermediates is still challenging. Here, a rectangular photocatalytic reactor coupled with in situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) was developed to detect reactive intermediates within several hundred microseconds during photocatalytic methane oxidation over Ag-ZnO. Gas phase â
CH3 generated by photogenerated holes (O- ) was directly observed, and its formation was demonstrated to be significantly enhanced by coadsorbed oxygen molecules. Methoxy radical (CH3 Oâ
) and formaldehyde (HCHO) were confirmed to be key C1 intermediates in photocatalytic methane overoxidation to CO2 . The gas-phase self-coupling reaction of â
CH3 contributes to the formation of ethane, which indicates the key role of â
CH3 desorption in the highly selective synthesis of ethane. Based on the observed intermediates, the reaction network initiated from â
CH3 of photocatalytic methane oxidation could be clearly illustrated, which is helpful for studying the photocatalytic methane conversion processes.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article