Nitrogen-doped reduced graphene oxide-supported Mn3O4: An efficient heterogeneous catalyst for the oxidation of vanillyl alcohol to vanillin

Nitrogen-doped reduced graphene oxide-supported Mn3O4 nanoparticles (N-RGO/Mn3O4) were prepared by solvothermal method and characterized by several physical techniques such as TEM images, XRD, XPS, and N2 adsorption–desorption techniques. The as-made N-RGO/Mn3O4 catalyst was used for the oxidation of vanillyl alcohol to vanillin. Several important reaction parameters were investigated such as reaction solvent, oxygen concentration, reaction temperature, and catalyst loading. N,N-Dimethylformamide was found to be the best solvent, affording both high conversion and vanillin selectivity. 92.5 % conversion of vanillyl alcohol and 91.4 % selectivity of vanillin were achieved after 12 h at 120 °C under oxygen balloon by the use of 40 mg of the N-GO/Mn3O4 catalyst. Kinetic studies revealed that the active energy for the oxidation of vanillyl alcohol to vanillin over N-GO/Mn3O4 catalyst was 39.67 kJ.mol−1. More importantly, the catalyst was stable and could be reused for 6 times without the significant loss of its catalytic activity.