Facile and Efficient Two-Step Formation of a Renewable Monomer 2,5-Furandicarboxylic Acid from Carbohydrates over the NiOx Catalyst

The formation of 2,5-furandicarboxylic acid (FDCA) from carbohydrates without a cumbersome 5-(hydroxymethyl)furfural (HMF) separation/purification process remains a formidable challenge. Herein, we prepared an innovative NiO x catalyst for the efficient oxidation of HMF to FDCA by using budget NaClO as oxidant, which can afford high FDCA yields (94–97%) from both pure HMF and carbohydrate-derived crude HMF in only 30 min at 25 °C. Remarkably, an impressive FDCA formation rate of 404 μmol g –1 min –1 (13–67-fold higher than those of recently reported catalytic systems for FDCA production) could be achieved over the NiO x catalyst at 25 °C. During the catalytic oxidation process, −Ni 4+ –O– sites over the NiO x catalyst are responsible for the efficient oxidation of HMF to FDCA. Furthermore, we also demonstrated a 50 g scale production of FDCA from HMF in a high yield of 96%. Therefore, the NiO x catalyst holds great promise to produce FDCA from biomass-derived carbohydrates in an effective and cost-competitive two-step process.