VAp Catalyzed Oxidation of Furfural to Maleic Acid: Kinetic Studies

The catalytic conversion of biomass-derived furfural to maleic acid is a promising route to sustainable chemical production. In this study, vanadium-apatite (VAp) was synthesized and evaluated as a heterogeneous catalyst for the controlled oxidation of furfural using hydrogen peroxide in a γ-valerolactone–water medium. Comprehensive characterization (XPS, SEM, XRD) confirmed the incorporation of V 5+ species within a stable apatite lattice possessing hierarchical porosity. Systematic variation of reaction parameters, including temperature, oxidant-to-substrate ratio, catalyst loading, and solvent composition, demonstrated that VAp effectively promotes furfural conversion under mild conditions. An optimized H 2 O 2: furfural molar ratio of 7:1 afforded complete furfural conversion with selectivity (∼47%) toward maleic acid, while limiting deeper oxidation to other C 4 acids. The catalyst retained high activity over four consecutive cycles with slight selectivity loss, indicating good structural stability. Kinetic analysis followed a Langmuir–Hinshelwood–Hougen–Watson (LHHW) model with competitive adsorption of reactants, and the calculated activation energy (37 kcal/mol) reflects the temperature dependence of the transformation. Overall, the study establishes VAp as a robust and reusable catalyst capable of enabling controlled oxidation of furfural to maleic acid within a green and scalable reaction system.