Montmorillonite-assisted synthesis of cobalt-nitrogen-doped carbon nanosheets for high-performance selective oxidation of alkyl aromatics

Abstract

Two-dimensional carbon nanomaterials have been widely applied in the field of catalysis due to their unique structure and properties. In this work, the cobalt and nitrogen co-doped two-dimensional carbon nanomaterials with graphene-like and porous structure were synthesized via template method. Here, rhodamine B acted as the carbon source was intercalated into the CTAB-pillared montmorillonite. And the cobalt porphyrin was used as the cobalt and nitrogen precursors that made a great contribution to generate highly dispersed active sites due to their unique CoN4 structure. The characterization techniques such as HAADF-STEM, XPS, XRD, and Nitrogen adsorption-desorption were used to investigate the surface composites and structures of the CoNC catalysts. In addition, the as-prepared catalysts with relatively high specific surface area, large pore volume, and well-dispersed active sites were further evaluated for the selective oxidation of ethylbenzene using tert-butyl hydroperoxide as oxidant. The CoN/CsH catalyst synthesized via impregnation method presented an ethylbenzene conversion of 96% and selectivity of 99% to acetophenone, which was the highest catalytic activity among the investigated catalysts. The superior catalytic performance could be ascribed to the unique two-dimensional porous graphene-like structure, highly dispersed active sites, and the synergistic effect between the CoOx and CoNx.