Regulating surface reactive oxygen species to promote ·CH3 generation on Er2O3 catalysts

Abstract

Methyl radicals (·CH₃) are crucial intermediates in the oxidative coupling of methane (OCM) reaction mechanism, involving both heterogeneous and homogeneous processes. We quantitatively determined the concentrations of desorbed ·CH₃ from meticulously synthesized Er₂O₃ catalysts using in situ synchrotron-based vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Our findings corroborate that the generation capacity of ·CH₃ serves as a robust metric for describing the catalytic performance of OCM. This investigation revealed that the modulation of reactive oxygen species (O^- and O₂^-) on the surface of various Er₂O₃ catalysts significantly influences the generation capability of ·CH₃ radicals. Notably, the ratio of these reactive oxygen species demonstrates a positive correlation with both the concentration of ·CH₃ radicals and the C₂ yield. Consequently, the generation potential of ·CH₃ serves as a critical linkage between the reaction performance of OCM and the surface structure of the catalyst, thereby enriching our comprehension of the intrinsic relationship between structure and performance in catalysts based on metal oxide during the OCM reaction.