Ca2MnO4-layered perovskite modified by NaNO3 for chemical looping oxidative dehydrogenation of ethane to ethylene

Chemical looping oxidative dehydrogenation (CL-ODH) is a process designed for the conversion of alkanes into olefins through cyclic redox reactions, eliminating the need for gaseous O2. In this work, we investigated the use of Ca2MnO4-layered perovskites modified with NaNO3 dopants, serving as redox catalysts (also known as oxygen carriers), for the CL-ODH of ethane within a temperature range of 700 °C to 780 °C. Our findings revealed that the incorporation of NaNO3 as a modifier significantly enhanced the selectivity for ethylene generation from Ca2MnO4. At 750 °C and a Gas Hourly Space Velocity (GHSV) of 1300 h–1, we achieved an ethane conversion up to 68.17%, accompanied by a corresponding ethylene yield of 57.39%. X-ray Photoelectron Spectroscopy (XPS) analysis unveiled that the doping NaNO3 onto Ca2MnO4 not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst. Furthermore, formation of NaNO3 shell on the surface of Ca2MnO4 led to a reduction in the concentration of manganese sites and modulated the oxygen releasing behavior in a step-wise manner. This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO3-doped Ca2MnO4 catalyst. These findings provide compelling evidence for the potential of Ca2MnO4-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.