Non-precious cobalt-bismuth binary oxide as a superior catalyst for the highly selective aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid in aqueous solvent

Developing highly effective cheap metal oxides is of great value for the 5-hydroxymethylfurfural (HMF) aerobic oxidation to 2,5-furandicarboxylic acid (FDCA) under environmentally friendly conditions. Herein, we synthesized a non-precious cobalt-bismuth binary oxide with rich oxygen vacancies by a facile malic-acid-assisted method and then employed it as a superior catalyst for the HMF aerobic oxidation to FDCA in water. Given the characterization results, the accession of Bi 2 O 3 made the (311) facet become the preferential orientation plane for Co 3 O 4 in the cobalt-bismuth binary oxide. Then, the oxygen vacancies from Co 3 O 4 will be increased due to the greater exposure of Co 2+ on the dominant exposed (311) facet, which in turn will facilitate the aerobic oxidation of HMF to FDCA. Evaluating the performance of cobalt-bismuth binary oxide in HMF oxidation reactions, an outstandingly high FDCA yield of 98.23% with nearly 100% HMF conversion could be found over CoBi-12 (Co/Bi molar ratio of 12 : 1) under 0.6 MPa O 2 pressure and 110 °C in water for 3 h. The findings of this study can contribute to the development of efficient non-precious metal-based catalysts for the aqueous-phase aerobic oxidation of biomass-derived HMF. We designed and synthesized a cheap CoBi binary oxide catalyst. Almost complete conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) was achieved on the as-prepared catalyst under mild conditions.