Switching from Reforming to Selective Dehydrogenation for Ethane–CO ₂ Coconversion on CeO ₂ -Based Catalysts via Crystal-Facet Engineering

CeO 2 -supported metal catalysts are highly efficient and widely employed in the ethane–CO 2 coconversion reaction, offering a promising approach to natural gas utilization and greenhouse gas valorization. However, this kind of catalyst with metal–CeO 2 interfaces predominantly favors dry reforming of ethane (DRE) to syngas, while achieving selective dehydrogenation to ethylene remains challenging. Here, a crystal-facet engineering strategy was adopted to fabricate nanoporous CeO 2 (np-CeO 2 ) with exposed high-index facets (HIFs). The relatively low-coordinated O atoms on HIFs render a stronger bonding with transition metals (e.g., Co), thereby forming more electron-deficient Co species. Consequently, the unique Co δ+ –O–Ce interfaces deliver superior selectivity to ethylene (88% on the basis of ethane) for the ethane–CO 2 coconversion, whereas Co on CeO 2 samples with low-index facets (LIFs) mainly undergoes DRE with only 2% ethylene selectivity. Through combining multiple in situ characterizations and theoretical calculations, it was found that more electron-deficient Co δ+ moderates the adsorption and activation of C–H bonds, suppresses the formation of key DRE intermediates (C 2 H 5 O*), and weakens the hybridization with the π orbital of ethylene, thereby promoting product desorption and inhibiting C–C cleavage. This work provides new insights for designing catalysts that achieve high olefin selectivity and CO 2 utilization in alkane–CO 2 coconversion reactions.