Selective oxidation of 5-formyloxymethylfurfural to 2, 5-furandicarboxylic acid with Ru/C in water solution

2, 5-furandicarboxylic acid (FDCA) is a one of the most promising biomass-derived chemicals to substitute the non-renewable terephthalic acid as the monomer for producing polyethyleneterephthalate. At present, the oxidation of HMF is regarded as a prevalent way to prepare FDCA. Nevertheless, the isolation and storage of HMF is still a challenge. Herein, based on the higher stability of 5-formyloxymethylfurfural (FMF) than 5-hydroxymethylfurfural (HMF), we present an effective preparation route to prepare FDCA by substituting HMF with FMF as feedstock. A complete conversion of FMF and a 93.55% selectivity of FDCA were obtained in the mixed solvent of water and 1, 2-dioxane using Ru/C as catalyst and O 2 as oxidant. An improved process was developed for preparing FDCA using FMF as feedstock. The investigation of conversion pathway showed that FMF and HMF were simultaneously oxidized to 2, 5-diformylfuran (DFF) in a case of the existence of the reversible equilibrium between FMF and HMF. Then DFF was oxidized to 5-formyl-2-furancarboxylic acid (FFCA). Subsequently, FFCA was oxidized to FDCA. In this process, the oxidation of FFCA to FDCA was determined as the rate-determining step. Furthermore, appropriate alkalinity favored the selectivity of FDCA and the conversion of FMF.