Revealing the Reactivity-Stability Trade-off in the Dry Reforming of Ethane over Ni Surfaces from the Microkinetic Analysis of Complex Reaction Network

Dry reforming of ethane (DRE) with carbon dioxide, a key reaction for converting shale gas into value-added products, offers an efficient route for carbon resource utilization. This process proceeds through two competing pathways: C–C bond cleavage leading to syngas formation and oxidative dehydrogenation yielding ethylene. Achieving precise control over product selectivity while maintaining catalyst stability through catalyst design remains a major challenge. In this study, we combine density functional theory (DFT) calculations with microkinetic modeling to elucidate the structure-performance relationship of DRE on Ni(111) and Ni(211) surfaces. A comprehensive reaction network comprising 52 intermediates, 139 transition states, and 141 elementary steps is constructed for the DRE reaction. The Ni(111) terraces promote sequential dehydrogenation to CH2CH2*, resulting in approximately 60% ethylene selectivity with minimal coke formation. In contrast, the Ni(211) step edges exhibit superior C–C bond activation and enhanced syngas selectivity but also strongly adsorb carbonaceous intermediates (C*, CC*, CCH*), leading to significant carbon accumulation and catalyst deactivation. Kinetic analyses reveal that the coverage-dependent balance between forward and reverse reaction rates is the primary factor governing selectivity. These findings establish a fundamental reactivity-stability trade-off in Ni-catalyzed DRE, and possible strategies to optimize catalytic activity, selectivity, and coke resistance are proposed.