Reactions of methyl radicals with metal oxides
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It was of interest in the present study to explore the effects of O2, CO2, N2O, and CH4 on the reactions of CH3 radicals with metal oxides at oxidative coupling temperatures. In order to study these effects in a more controlled manner, CH3 radicals were generated by the pyrolysis of azomethane (CH3N=NCH3) instead of by passing CH4 and O2 over the catalyst at high temperatures. The advantage of using azomethane as a source of CH3 is that the only other product of pyrolysis is N2, which does not affect the secondary reactions. The addition of O2 or CO2 to the reagent gases had a marked effect on the CH3 radical reactivity for several selective oxidative coupling catalysts; whereas, the addition of N2O or CH4 had little effect. The sticking coefficient did not increase linearly with respect to O2 partial pressure, which suggests that CH3O2 radicals are not involved in secondary reactions at the surface. The presence of carbonate ions, derived from CO2, significantly decreased the reactivity of CH3 with a La2O3 catalyst.
American Chemical Society, Division of Petroleum Chemistry, Preprints
author list (cited authors)
Xu, M., Rosynek, M. P., & Lunsford, J. H.
complete list of authors
Xu, M||Rosynek, MP||Lunsford, JH