A unified mechanism for oxidative coupling and partial oxidation of methane

The oxidative coupling (OCM) and the partial catalytic oxidation (POM) of methane as well as the homogeneous oxidation of methane (HOM) differ only in the ratio CH4/O2 used and of course in the use of a catalyst. It can therefore be considered that their overall reaction mechanism should be the same...

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Bibliographic Details
Published in:Fuel (Guildford) 2021-08, Vol.297, p.120683, Article 120683
Main Authors: Simon, Yves, Marquaire, Paul-Marie
Format: Article
Language:English
Subjects:
Catalysts
Catalytic oxidation
Chemical Sciences
Coupling
High temperature
Kinetic mechanism
La2O3
Lanthanum oxides
Methane
Oxidation
Oxidative coupling
Partial oxidation
Reaction mechanisms
Surface reactions
Vapor phases
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Summary:The oxidative coupling (OCM) and the partial catalytic oxidation (POM) of methane as well as the homogeneous oxidation of methane (HOM) differ only in the ratio CH4/O2 used and of course in the use of a catalyst. It can therefore be considered that their overall reaction mechanism should be the same with elementary reactions of varying importance depending on the type of oxidation reaction studied. We have therefore tried to represent the results obtained during the experimental study of OCM and POM over La2O3 and that of the oxidation of methane in gas phase from a single mechanism. At high temperature, OCM and POM are catalytic reactions but their reaction mechanisms are very complex because the surface reactions are coupled to reactions in gas phase by the intermediary of radicals, so both homogeneous and heterogeneous mechanisms occur at the same time. In this work, the development and the validation of a hetero-homogeneous mechanism is proposed for the three reactions. This mechanism is based on elementary steps at the catalyst surface and elementary steps in gas phase for a large range of temperature (973 K–1173 K) and residence time (0.7 s–5.5 s).
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2021.120683