Effect of CO2 Co-Feeding on the Stabilization of Atomically Dispersed Iron Species over MgAl2O4 During Ethane Dehydrogenation Reactions

Ethane dehydrogenation provides an opportunity for the effective utilization of shale gas and production of ethene. Up to now, it is still a great challenge to acquire a stable ethane dehydrogenation catalyst operated under high temperature and reductive atmospheres. In this study, we prepared an Fe-based catalyst supported on MgAl2O4 with atomically dispersed iron species even after 6 reaction–regeneration cycles. Sheet-like morphology and spinel structure of MgAl2O4 is beneficial for the high dispersion of Fe species. The iron species undergoes reduction, sintering, and detachment during the ethane dehydrogenation reaction, as evidenced by in situ High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy and quasi-in situ 57Fe Mössbauer spectroscopy. By contrast, the introduction of CO2 leads to a slow deactivation, where only the partial reduction of isolated Fe3+ species to isolated Fe2+ species was observed. And the activity could be restored by a simple O2 treatment. The current work sheds light on the design of high-efficient dehydrogenation catalysts.