Ru-Catalyzed Steam Methane Reforming: Mechanistic Study from First Principles Calculations

Elucidating the reaction mechanism of steam methane reforming (SMR) is imperative for the rational design of catalysts for efficient hydrogen production. In this paper, we provide mechanistic insights into SMR on Ru surface using first principles calculations based on dispersion-corrected density functional theory. Methane activation (i.e., C–H bond cleavage) was found to proceed via a thermodynamically exothermic dissociative adsorption process, resulting in (CH<sub><i>y</i></sub> + <i>z</i>H)* species (“*” denotes a surface-bound state, and <i>y</i> + <i>z</i> = 4), with C* and CH* being the most stable adsorbates. The calculation of activation barriers suggests that the conversion of C* into O-containing species via C–O bond formation is kinetically slow, indicating that the surface reaction of carbon intermediates with oxygen is a possible rate-determining step. The results suggest the importance of subsequent elementary reactions following methane activation in determining the formation of stable carbon structures on the surface that deactivates the catalyst or the conversion of carbon into O-containing species.