Complete oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid by a novel enzyme-nanozyme hybrid catalyst

2,5-Furandicarboxylic acid (FDCA) is a well-known biobased platform chemical to produce sustainable polyethylene furanoate (PEF) and other valuable furanic chemicals. The eco-friendly enzyme cascade reactions have been adopted to synthesize FDCA using the multistep oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) based on different oxidoreductases. However, the coordination of natural oxidoreductases in cascade reactions presents challenges because of their different adaptabilities and catalytic environments. A robust and efficient catalyst herein was developed by the hybridization of a designed hemin-peptide (HP-7) complex and natural aryl-alcohol oxidase (AAO) in iron phosphate solution to achieve the cascade oxidation of HMF to FDCA. HMF is first transformed in 5-formylfurancarboxylic acid (FFCA) based on the oxidizability of AAO toward benzylic alcohol, and then the latent activity of AAO on FFCA was activated by the catalase activity of the HP7@Fe3(PO4)2 nanozyme with the in situ consumption of H2O2 initially produced by AAO. Moreover, closer inspection demonstrated the oxidizability of the HP-7@Fe3(PO4)2 nanozyme on FFCA in both the presence and absence of H2O2 for the first time. Consequently, the hybrid catalyst AAO/HP-7@Fe3(PO4)2 enabled the selfactivated and efficient oxidation of HMF by integrating multiple reaction processes. A complete conversion of HMF with excellent selectivity (100%) toward FDCA was finally observed.

Automated summary

FDCA is a platform chemical used to produce sustainable PEF, and this study developed a catalyst that enables the efficient oxidation of HMF to FDCA. The catalyst, a hybrid of HP-7 and AAO, showed self-activation and high efficiency in the oxidation process, resulting in complete conversion of HMF with excellent selectivity.