Aerobic oxidation of the C–H bond under ambient conditions using highly dispersed Co over highly porous N-doped carbon

Highly dispersed Co sites in highly porous N-doped carbon (Co-NC) were synthesized by high-temperature pyrolysis of Zn/Co bimetallic zeolitic imidazolate framework-8 (CoxZn100−x-ZIF). Wide characterization indicated that the pyrolysis atmosphere and temperature play crucial roles in the metal dispersion and pore structure of the resulting materials. A hydrogen treatment at elevated temperatures is found to favour the Zn volatilization and restrict the pore shrinkage of the ZIF precursor, thus yielding efficient catalysts with highly dispersed Co, a high surface area (1090 m2 g−1) and pore volume (0.89 cm3 g−1). When used as a catalyst for aerobic oxidation of ethylbenzene (EB), Co1Zn99-ZIF-800-H2 contributes to 98.9% EB conversion and 93.1% ketone selectivity under mild conditions (60 °C, 1 atm O2), which is 41.3 times more active in comparison to the ZIF-67-derived Co catalyst. Co-NC is stable and could be reused four times without obvious deactivation. This catalyst displays good chemoselectivity to the corresponding ketones when using a broad scope of hydrocarbon compounds.