Efficient selective oxidation of hydrocarbons to corresponding ketones has been a significant but chal-lenging 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.