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 Bi2O3 made the (311) facet become the preferential orientation plane for Co3O4 in the cobalt-bismuth binary oxide. Then, the oxygen vacancies from Co3O4 will be increased due to the greater exposure of Co2+ 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 O2 pressure and 110 degrees 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.