Facet-engineered Fe-Ni/CeO2 catalysts for selective CO2-assisted oxidative dehydrogenation of ethane

• The exposed crystal faces showed significant impact on the catalytic performance. • Fe 1.5 Ni 0.5 /CeO 2 –R catalyst exhibits an ethylene selectivity of more than 82.5 %. • The CeO 2 rod has higher O v density and stronger metal-support interaction. • O v and Fe 2+ -O-Ce 3+ sites promote CO 2 activation through C=O bond cleavage. The selective catalytic conversion of ethane and CO 2 into value-added products presents significant economic and environmental benefits. This study elucidates the influence of CeO 2 support crystal facets (111, 110, and 100) on CO 2 activation and ethane oxidative dehydrogenation performance. Among the catalysts investigated, Fe 1.5 Ni 0.5 supported on reduced CeO 2 (Fe 1.5 Ni 0.5 /CeO 2 -R) exhibits the highest content of Fe 3+ and metallic Ni, where the synergistic Fe 3+ -Ni 0 active sites formed by oxidized Fe 3+ and reduced Ni 0 species serve as the optimal sites for oxidative dehydrogenation of ethane. This catalyst shows lower activation energies for C 2 H 6 and CO 2 dissociation, as well as for the overall oxidative dehydrogenation reaction, compared to the oxidized counterpart (Fe 1.5 Ni 0.5 /CeO 2 -O). The Fe 1.5 Ni 0.5 /CeO 2 -R catalyst with predominantly exposed (111) facets achieves an ethylene selectivity of 82.51 % at 650 degrees Celsius. The CeO 2 (111) surface features three-coordinated oxygen and seven-coordinated cerium atoms, which enhance its surface stability. CO 2 preferentially adsorbs on CeO 2 (111) forming tridentate carbonate species with an adsorption energy of −0.74 eV. Oxygen vacancies further strengthen CO 2 adsorption and activation by increasing surface interactions, thereby promoting catalytic performance. This work provides fundamental insights into facet-dependent catalyst design and offers a strategic route for efficient CO 2 utilization coupled with selective ethylene production from light alkanes.