N-Doped carbon nanotube encapsulated cobalt for efficient oxidative esterification of 5-hydroxymethylfurfural

Cobalt nanoparticles embedded in graphitic nitrogen-rich carbon nanotubes (Co/GCN) were prepared with a facile method and employed as an efficient catalyst for oxidative esterification of 5-hydroxymethylfurfural (HMF). The introduction of N species to carbon benefits the synergistic effects between the Co nanoparticles and nitrogen-doped carbon nanotube substrate, which modify the surface chemical state of the Co/GCN catalyst and create abundant active sites to improve the HMF conversion. The Co/GCN catalyst carbonized at 800 degrees C exhibited the best catalytic performance with a 95.8% yield of furan-2,5-dimethylcarboxylate (FDMC) at 98.6% HMF conversion under mild reaction conditions. The effect of acid-base properties of the catalyst on the HMF conversion was investigated and the reaction mechanism of the HMF oxidative esterification was proposed.