Oxidation of 5–methoxymethylfurfural to 2, 5-furandicarboxylic acid over Ru/hydroxyapatite catalyst in water

Biomass-derived 2,5-furandicarboxylic acid (FDCA) is considered a viable alternative to petroleum-derived terephthalic acid as a monomer in the production of bioplastic. FDCA is currently mainly produced via a two-step process involving the conversion of fructose to 5-hydroxymethylfurfural (HMF) and the subsequent oxidation of HMF to FDCA. However, the storage stability HMF is far below the industrial expectations, further inhibiting the HMF-mediated route. Herein, we report efficient oxidation of 5-methoxymethylfurfural (MMF) to FDCA over a homemade Ru/hydroxyapatite (Ru/HAP) catalyst. A complete conversion of MMF and > 65% molar yield of FDCA could be realized under mild reaction conditions of 130 °C and 1 MPa O2 pressure. The effects of process parameters, including MMF/catalyst ratios, reaction temperature/time, and O2 pressure, were systematically studied and optimized on MMF oxidation. A plausible reaction pathway was also proposed. This study and our previously reported fructose-to-MMF work may provide a feasible MMF-intermediated route for large-scale industrial FDCA production.