Aerobic Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid over Holey 2 D Mn ₂ O ₃ Nanoflakes from a Mn‐based MOF

The aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), a promising renewable monomer to produce bio-based polymers such as polyethylene furanoate (PEF), has recently emerged as the subject of increasing interest. Here, holey 2 D Mn2 O3 nanoflakes were obtained by a facile thermal treatment of a Mn-based metal-organic framework (MOF) precursor. The structural and morphological properties of the nanoflakes were characterized by powder XRD, FTIR, SEM and TEM to explore the formation process. It was inferred that the linker loss in the MOF precursor and the oxidation of the Mn cation induced by the heat-treatment in air were responsible for the formation of holey 2 D Mn2 O3 nanoflakes. The specific morphology and redox cycle of the Mn cation on the surface endowed the synthesized nanoflakes with promising performance on the selective oxidation. The obtained nanoflakes calcined at 400 °C (M400) afforded over 99.5 % yield of FDCA at complete conversion of HMF, which is superior to the catalytic activity of commercial Mn2 O3 and activated MnO2 . To our knowledge, Mn2 O3 exhibiting such a high performance on the aerobic oxidation of HMF to FDCA has not yet been reported. Based on the investigation of the experimental parameters, a plausible reaction mechanism was proposed.