Bio-based monomers: a new route to convert 5-HMF to FDCA

Bio-based renewable resources gained significant attention as sustainable alternatives for the production of fuels and chemicals through carbon-neutral and environmentally friendly processes. Among these, 2,5-furandicarboxylic acid (FDCA) emerged as a key platform chemical for the synthesis of bio-based polymers. The present study investigated an alternative route for FDCA production from 5-hydroxymethylfurfural (5-HMF), employing a wide range of manganese-based oxidizing agents. Specifically, α-MnO2, β-MnO2, γ-MnO2, and δ-MnO2 polymorphs were synthesized, and the effects of crystal structure, reaction time, and MnO2 dosage were examined in order to optimize the oxidation process for more efficient FDCA synthesis. This study also investigated the structural properties of an industrially produced manganese-based oxidation agent, with particular emphasis on the correlation between its structure and performance during oxidation. Various reaction conditions, including different solvents, pH levels, and oxidant dosages, were explored to evaluate their impact on the overall conversion of 5-HMF. Isolation and collection of the resulting FDCA were conducted to determine the overall yield. Lastly, different regeneration paths were tested to restore the oxidant’s activity for multiple reuses, thereby contributing to a more sustainable and cost-effective process over the long term. The results revealed distinct differences between the lab-synthesized and industrial samples in terms of morphology and interaction with the substrate. Unexpectedly low initial FDCA yields prompted further investigation, which showed that surface fouling significantly inhibited FDCA recovery, a phenomenon more pronounced in the lab-synthesized samples. In contrast, the industrial oxidant exhibited greater stability, making it suitable as a reference material in subsequent experiments. This consistency enabled a controlled evaluation of solvent effects on reaction progression.