Oxidative dehydrogenation of ethylbenzene on mesoporous carbon catalysts: effect of the active site number on the apparent catalytic activity

Abstract

Oxidative dehydrogenation (ODH) of ethylbenzene (EB) over nanocarbon catalysts has attracted intensive attention due to its impressive dehydrogenation conversion, selectivity and low ecological carbon footprint. In this work, novel sucrose-derived mesoporous carbon (SMC-x) was synthesized via the hard template method and applied as a catalyst in the EB ODH reaction. The SMC-1000 catalyst demonstrated an EB conversion of 55.6% with a styrene (ST) selectivity of 90.9% under gentle reaction conditions, maintaining long-term stability for over 18 h, surpassing commercial nanocarbon materials. Through a correlation between reactivity and the surface composition and structural information of SMC-x catalysts, ketonic carbonyl groups have been identified as the catalytically active sites for the dehydrogenation reactions, and the apparent catalytic activity of the carbon materials is found to be directly related to the number of active sites. This finding underscores the significance of these specific functional groups in driving the catalytic activity of SMC-x. Furthermore, the fundamental reaction kinetics and mechanistic nature of SMC-x catalyzed EB ODH reactions were systematically investigated through kinetic analysis, isotope, and temperature programmed desorption experiments.