Monolithic stirrer reactor: The selective lactose oxidation in liquid phase over Au/Al2O3 nanostructured catalysts

•Metallic monoliths used as stirrer blades in a batch reactor for aqueous phase carbohydrate oxidation.•Nanostructured Au/Al2O3 on metallic monoliths is stable catalyst for the lactose oxidation.•The most active catalyst was obtained after several reaction cycles and regeneration at 400 °C.•Catalytic activity non-depending on monoliths channel size for stirring rates higher than 600 rpm.