Influence of doping nitrogen on the catalytic performance of carbon nanotubes encapsulating cobalt for selective oxidation of arylalkanes

Efficient selective oxidation of hydrocarbons to corresponding ketones has been a significant but challenging work in the past decades. Here, a nitrogen-doped bamboo-like carbon nanotubes encapsulating cobalt catalyst (NCNTs-X) using citric acid, melamine and CoCl2‧6H2O as precursors was synthesized by a simple pyrolysis method. A series of characterization techniques were employed to investigate the physicochemical properties of samples. And the results show that the as-prepared catalysts achieve a high catalytic performance for selective ethylbenzene oxidation (78.3% ethylbenzene conversion) using molecular oxygen as oxidant, especially giving a high selectivity (93.8% selectivity to acetophenone). According to the investigation of the structure-activity relationship of the catalysts, it can be deduced that the Co–Nx sites have an obvious positive effect on catalytic performance thanks to the synergistic effect between metallic cobalt and pyridinic N.