Glycerol steam reforming on Ru catalysts supported on core-shell metal-ceramic microcomposites developed by a microwave-induced hydrothermal method

Glycerol steam reforming on Ru catalysts supported on core-shell metal-ceramic microcomposites, MgAl₂O₄@Al and Al₂O₃@Al consisting of Al metal core encapsulated by high surface area porous metal oxide shell, is studied. The support structures were prepared by microwave-induced hydrothermal surface oxidation (MW-HTO) of Al metal particles at low temperatures and atmospheric pressure. The type and concentration of Mg precursor for MW-HTO had significant effects on morphological and physicochemical properties of the resulting core-shell microstructures. Ru/MgAl₂O₄@Al and Ru/Al₂O₃@Al catalysts exhibited 2-3-folds higher glycerol conversion turnover rates than conventional Ru/MgAl₂O₄ and Ru/Al₂O₃ counterparts at similar Ru dispersions, most likely due to facilitation of heat transport through these multifunctional catalyst support structures. The structures and properties of the catalysts were characterized by SEM, TEM, XRD, EDX, N₂ adsorption, and CO chemisorption. The core-shell structures were stable for an extended time of glycerol steam reforming reactions (823 K and 24 h), indicating that the metal oxide shells were persistent on the surface and at the metal/oxide interface. These composite structures may provide opportunity for the catalytic reactions requiring high intensity of heat flux such as endothermic fuel reforming for hydrogen production in microreactors for fuel cells.