Co-N-C catalyst with single atom active sites for base-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under mild conditions

The production of 2,5-furandicarboxylic acid (FDCA), a promising biodegradable alternative to fossil-based terephthalic acid (PTA), from biomass-derived 5-hydroxymethylfurfural (HMF) is of significant importance. A major challenge is to develop an effective non-precious metal catalyst system that does not require a homogeneous base. In this study, we present a noble-metal-free Co-N-C catalyst, derived from the pyrolysis of cobalt-phenanthroline complexes on a carbon support. This catalyst demonstrates exceptional performance, achieving a FDCA yield of 99.9 % and maintaining reusability for up to five catalytic cycles in the base-free oxidation of HMF to FDCA under mild conditions. Through controlled experiments and comprehensive characterizations, we propose that the active sites in the Co-N-C catalyst are Co single atoms bonded to nitrogen within graphitic sheets. This approach provides valuable insights into the exact nature of the active sites in such noble-metal-free M-N-C catalysts designed for biomass conversion