Molten Salt‐Assisted Synthesis of Co/N‐Doped Carbon Hybrids for Aqueous‐Phase Aerobic Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid

A resource-efficient and facile method of synthesizing 2,5-furandicarboxylic acid (FDCA) from biomass-derived platform chemical 5-hydroxymethylfurfural (HMF) was explored using cobalt and nitrogen-doped carbon catalysts (Co/N-C). A molten salts-assisted method proved to be effective in improving the surface area of the catalysts as well as uniformity and dispersibility of the Co species. Detailed investigation of different combinations of precursors revealed that the formation of Co-Nx species was imperative for high FDCA selectivity, and the nitrogen-doped carbon matrix enhanced the catalytic activity by providing good electron mobility. A significant observation was made regarding the change in reaction mechanism with the heating rate of Co/N-C. High HMF conversion of 99 % with 68 % FDCA yield was achieved at 120 °C in water at 24 h. This study shows an eco-friendly and cost-effective method of FDCA production with high yield that overcomes the use of precious metal-based catalysts, organic solvents, and severe reaction conditions.