Insight into Dehydrogenation of C2HX Species in Ethane Steam Reforming on Ir(100): A DFT Study

The reaction barrier and heat of formation of various dehydrogenation reactions involved in the steam reforming of ethane (SRE) are critical parameters in the understanding and improving the technology of SRE. Focusing on Ir-based catalyst, we report a comprehensive reaction network of dehydrogenation of ethane on Ir(100) based on extensive density functional theory (DFT) calculations on 10 C-H bond cleavage reactions. The geometric and electronic structures of the adsorption of C2Hx species with corresponding transition-state and product structures are reported. We found that the C-H bond in CH3C required the most energy to activate, due to the most stable four-fold hollow configuration of the adsorption site. Ethane can easily dissociate to CH3CH and CH2CH2 on Ir(100). By using the degree of dehydrogenation of the reactant species as a variable to correlate the C-H bond cleavage barrier as well as reaction energy, DFT results reveal that the Ir(100) surface to a great extent promotes ethane dehydrogenation when compared to other surfaces.