Recyclable Magnetic Fe3O4-Supported Copper Oxide as Efficient Catalyst for Oxidation of 5-Hydroxymethylfurfural to 2,5-Furanediformic Acid

The nano-metal oxide-catalyzed oxidation of 5-hydroxymethylfurfural (HMF) with sodium hypochlorite (NaClO) is an effective and mild technique for synthesizing 2,5-furanediformic acid (FDCA). However, the rapid and large-scale separation of nanocatalysts remains a major challenge. In this study, we developed a magnetic and recyclable copper oxide-based catalyst supported on the mechanochemically synthesized Fe3O4. Benefiting from the introduction of the Fe3O4 carrier and cetyltrimethylammonium bromide (CTAB) surfactant, the CuO-CTAB/Fe3O4 catalyst owns smaller CuO particle sizes, which endows it with excellent catalytic activity in the oxidation of HMF, achieving a high FDCA yield of 90.3%. Furthermore, the rapid magnetic separation of the catalyst effectively inhibits the excessive conversion of FDCA. The recovered catalyst can be reused for at least five cycles without significant loss of catalytic performance, confirming the promising application prospect of the CuO-CTAB/Fe3O4 catalyst.