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Direct Evidence on the Mechanism of Methane Conversion under Non-oxidative Conditions over Iron-modified Silica: The Role of Propargyl Radicals Unveiled.

ABSTRACT: Radical-mediated gas-phase reactions play an important role in the conversion of methane under non-oxidative conditions into olefins and aromatics over iron-modified silica catalysts. Herein, we use operando photoelectron photoion coincidence spectroscopy to disentangle the elusive C₂₊ radical intermediates participating in the complex gas-phase reaction network. Our experiments pinpoint different C₂ -C₅ radical species that allow for a stepwise growth of the hydrocarbon chains. Propargyl radicals (H₂ C-C≡C-H) are identified as essential precursors for the formation of aromatics, which then contribute to the formation of heavier hydrocarbon products via hydrogen abstraction-acetylene addition routes (HACA mechanism). These results provide comprehensive mechanistic insights that are relevant for the development of methane valorization processes.

SUBMITTER: Puente-Urbina A

PROVIDER: S-EPMC8596584 | biostudies-literature |

REPOSITORIES: biostudies-literature

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