Switching from Reforming to Selective Dehydrogenation for Ethane–CO2 Coconversion on CeO2-Based Catalysts via Crystal-Facet Engineering

Le résumé fourni par la source

CeO2-supported metal catalysts are highly efficient and widely employed in the ethane-CO2 coconversion reaction, offering a promising approach to natural gas utilization and greenhouse gas valorization. However, this kind of catalyst with metal-CeO2 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 CeO2 (np-CeO2) 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 Coδ+-O-Ce interfaces deliver superior selectivity to ethylene (88% on the basis of ethane) for the ethane-CO2 coconversion, whereas Co on CeO2 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 Coδ+ moderates the adsorption and activation of C-H bonds, suppresses the formation of key DRE intermediates (C2H5O*), 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 CO2 utilization in alkane-CO2 coconversion reactions.

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