Co-N-C catalysts synthesized by pyrolysis of Co-based deep eutectic solvents for aerobic oxidation of alcohols

Abstract

The selective oxidation of alcohols to the corresponding aldehydes and ketones is of great importance in the academic and industrial fields. A series of excellent nanostructured catalysts comprising cobalt nanoparticles supported on nitrogen-doped carbon (Co-N-C) were thus prepared by pyrolysis of a deep eutectic solvent Co(NO₃)₂·6H₂O/[Bmim]Br supported on commercial carbon. The catalytic activity of the Co-N-C materials was studied in the selective aerobic oxidation of alcohols with molecular oxygen under base-free conditions. The results indicated that the optimized Co-N-C/700 catalyst exhibited excellent catalytic performance in the selective oxidation of both aryl and alkyl alcohols, giving their corresponding aldehydes and ketones in good to excellent yields. Furthermore, the combination of the catalytic results of the control group and the different characterization methods showed that such high catalytic activity is due to the synergistic interaction between the nitrogen-doped carbon support and Co-N species in Co-N-C/700. In addition, the magnetically recoverable Co-N-C catalyst could be easily separated from the reaction system by using an external magnetic field and reused at least five times without an obvious decrease in the catalytic efficiency.