Understanding oxidative dehydrogenation of ethane on Co3O4 nanorods from density functional theory

摘要

Co3O4 is a metal oxide catalyst with weak, tunable M-O bonds promising for catalysis. Here, density functional theory (DFT) is used to study the oxidative dehydrogenation (ODH) of ethane on Co3O4 nanorods based on the preferred surface orientation (111) from the experimental electron-microscopy image. The pathway and energetics of the full catalytic cycle including the first and second C-H bond cleavages, hydroxyl clustering, water formation, and oxygen-site regeneration are determined. We find that both lattice O and Co may participate as active sites in the dehydrogenation, with the lattice-O pathway being favored. We identify the best ethane ODH pathway based on the overall energy profiles of several routes. We identify that water formation from the lattice oxygen has the highest energy barrier and is likely a ratedetermining step. This work of the complete catalytic cycle of ethane ODH will allow further study into tuning the surface chemistry of Co3O4 nanorods for high selectivity of alkane ODH reactions.