Preparation of oxygen reactivity-tuned FeOx/BN catalyst for selectively oxidative dehydrogenation of ethylbenzene to styrene

Abstract

Oxidative dehydrogenation of ethylbenzene to styrene is considered to be an eco-friendly process, but suffering from overoxidation of the product to carbon oxides due to uncontrollable oxygen reactivity of the catalysts. Here, we report a boron nitride-supported FeOx (FeOx/BN) catalyst, over which an industrially acceptable styrene selectivity (94%) and productivity (0.9 gST gcat−1 h−1) at the conversion of 60% can be attained under oxygen-rich conditions. Based on the investigation of kinetics, CH3OH-TPD, H2-TPR, and O2 pulse reaction, BN support is found to mitigate the oxygen reactivity of FeOx via the strong interaction between the FeOx clusters and the BOx species stemmed from the BN support, which suppresses the overoxidation of ethylbenzene and styrene to carbon oxides. The catalytic tests and structural characterizations reveal that the redox FeOx species initiate the dehydrogenation and then quinone/carbonyl sites on the newly formed coke deposition over FeOx/BN catalyst leads to the increase of activity during the induction period. With the aid of the FeOx and BOx species, the balance between coke deposition and its gasification rates was achieved under oxygen-rich conditions, guaranteeing stable styrene selectivity and productivity.