Enhanced ethanol reforming with catalytic active ruthenium species derived from solid solution in lanthanum chromite

Abstract

Ethanol steam reforming (ESR) is a promising route for renewable hydrogen production, but it requires highly active and coke resistant catalysts to efficiently convert ethanol into hydrogen-rich mixtures. The ESR catalytic activity is investigated in single-phase LaCr_1−xRu_xO₃ solid solutions with 0.0 ≤ x ≤ 0.20. Highly active ruthenium species are formed at the surface of the oxide in operando during ESR at 600 °C. These species have remarkable stability for ESR with strong resistance for coke formation, resembling single-atom catalysts. Samples reduced ex situ at higher temperature (900 °C) exhibit Ru exsolved nanoparticles with lower catalytic stability than the species obtained in operando during ESR reaction. X-ray absorption spectroscopy and high-resolution transmission electron microscopy reveal that small metallic Ru species (≤2 nm) are formed under ESR reaction, whereas in samples exsolved at 900 °C such species coexist with larger exsolved Ru particles (∼5 nm), which are more likely to deactivate. The experimental results provide an innovative approach for solid solution-derived species in refractory oxide matrix that are valuable for designing robust catalysts for ESR.