Decoding the Role of Metal-Oxide Interactions in Hydrogen Optimization through Oxidative Steam Reforming of Ethanol (OSRE)

This study explores the influence of metal-oxidic matrix interactions in hydrotalcite-type structures, achieved through the isomorphic substitution of NiCo, to enhance catalytic performance in the oxidative steam reforming of ethanol (OSRE). By modulating key properties: i) crystalline structure, ii) bimetallic phase dispersion, iii) basic site density, and iv) reducibility, a correlation with catalytic activity is established. Prereduction at 600 °C revealed that increasing NiCo content promotes partial reduction, which intensifies as metal-matrix interactions weaken, at the expense of basic sites. CO chemisorption experiments confirmed the presence of both semi-oxidized (Mⁿ⁺) and reduced (M⁰) metal states, with smaller active-phase loadings favoring highly dispersed particles rich in Mⁿ⁺. These particles exhibited strong interfacial interactions that resisted full metal reduction. Optimal catalytic performance is achieved with 20–30 wt.% NiCo, with an optimal amount of M⁰/Mⁿ⁺, yielding complete ethanol conversion and 60% selectivity to H₂ at 400 °C, as validated by DRIFT and GC analyses. Post-reaction characterizations highlighted the formation of carbonaceous deposits, which are mitigated by small particle sizes and a high O_II/O_I ratio, as determined by XPS. These findings provide a roadmap for tailoring catalytic systems to maximize efficiency in OSRE applications.