Nitrogen-rich carbon nanosheets supported copper catalysts for oxidative carbonylation of ethanol

Abstract

Two-dimensional (2D) nitrogen-rich carbon nanosheets NC-x with a nitrogen content of 5.2 %-6.8 wt% were characterized by a one-step co-pyrolysis method and employed as Cu catalyst supports for oxidative carbonylation of ethanol. Carbon nanosheets with abundant nitrogen defects were achieved by tuning the dosage of ammonium oxalate, in which the Cu/NC-12 catalyst performed excellent activity. Furthermore, Cu/NC-x catalysts presented significantly superior catalytic activity than that of copper/carbon nanosheets (Cu/C) catalyst, it can be ascribed to the most suitable nitrogen doping to promote the exposure and dispersion of Cu species and pyridine nitrogen served as the main anchor sites to increase the ratio of Cu+/(Cu++Cu0). Density functional theory calculations further proved that introducing nitrogen atoms into carbon nanosheets effectively reinforced binding to Cu4 and adsorption of intermediates with NC, and a remarkable activity on Cu/NC-12 was achieved by a more favorable insertion of CO in the rate-determining step.