Synthesis of Vanillin from Biomass-Derived Isoeugenol Using Immobilized Cobalt-Porphyrin on Hydroxyl-rich Graphene Oxide Catalyst

Synthesis of vanillin from isoeugenol by oxidation has been investigated using cobalt(II) porphyrin (CoTCPP: meso-tetrakis(4-carboxy)phenyl porphyrinato cobalt(II)) covalently linked to hydroxyl-rich graphene oxide (GOOH) as a heterogeneous catalyst. The catalyst was thoroughly characterized by various spectroscopic techniques, such as FT-IR, XRD, N2 adsorption-desorption, XPS, and SEM-EDS analytical techniques. Catalytic activity of the CoTCPP/GOOH gave an excellent yield of 75.1% in the conversion of isoeugenol to vanillin using molecular oxygen for 20 h reaction at 100 °C in 3.0 MPa oxygen pressure. The catalyst showed exceptional stability upon multiple reuses without significant loses in activity. Accordingly, the present study highlights the promise of CoTCPP/GOOH as a heterogeneous catalyst for the efficient aerobic oxidation of biomass-derived platform chemicals into valuable end-products.