Catalytic transformation of light alkanes with oxidants (O2, CO2, H2O) on transition metals and oxides may involve one or more of the following reactions such as partial oxidation, combustion, reforming, dehydrogenation, and water-gas shift reactions. These reactions occur either sequentially or concomitantly within a catalytic cycle, initiating with the activation of strong C-H bonds, kinetically coupled with the activation of the co-reactants, in catalytic steps that increase the carbon oxidation state of alkanes. These reactions occur at different oxygen chemical potential ranges, but they exhibit similar kinetic characteristics and requirements. Here, I will report the mechanistic synergies across the activation of methane and ethane, specifically focusing on the connection of oxygen chemical potentials on transition metals and metal oxides to the various types of reactive oxygen intermediates and then to their selectivities during C2H6-O2, C2H6-CO2, and C2H6-H2O catalysis, comparing with those of CH4. Specific findings are the roles of reactive oxygen species in mediating the catalytic pathways, the catalytic requirements for preserving the C-C bond in ethane that leads to the formation of ethylene, and the factors that influence the catalyst stabilities on molybdenum oxide and Group VIII metal catalysts. This mechanistic knowledge provides insights on designing more stable and selective catalysts for ethane conversion.

Catalytic consequences of oxygen chemical potential on light alkane activation

2019 Spring National Meeting

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