N, P codoped hollow carbon prisms for efficient oxidative dehydrogenation reaction with both enhanced activity and selectivity

Abstract

Carbon materials have stimulated tremendous interest in oxidative dehydrogenation (ODH) of alkane to olefin molecules at low temperature. Unfortunately, its further development has been seriously hindered due to the unsatisfactory catalytic performance. To tackle these challenges, nitrogen and phosphorus codoped hollow carbon prisms (NPC) are designed with controllable surface functional groups through supramolecular pre-assembly and substitution reaction from guanine and hexachlorotriphosphazene. The resultant catalysts can achieve both high catalytic activity (63 % conversion) and styrene selectivity (90 %) in ODH of ethylbenzene, outerperforming previous reported carbon-based catalysts. Structural characterizations, kinetics measurements and theoretical results unravel that nitrogen doping can promote nucleophilicity of –CO, thus improving the catalytic activity. The phosphorus doping not only changes reaction rate-determining step from activation of O2 in N-doped carbon to activation of –C–H bond of EB in N,P-codoped carbon, but also inhibits the formation of electrophilic oxygen species, which enhances selectivity of styrene. The current work provides a facile strategy for preparation of functional NPC catalyst and physical–chemical insights on the structure–activity relationship of NPC catalysts, paving the way for further development of the highly efficient non-metallic catalytic systems.