Direct dehydrogenation of ethylbenzene over C60–Ni/SiO2 catalysts: mechanistic insight into C60 as a molecular promoter

Abstract

Extensive research in heterogeneous catalysis has highlighted the potential of non-noble metal catalysts for efficient alkane dehydrogenation. Although Ni species are widely employed for activating C–H bonds, their utilization as active catalysts for alkane dehydrogenation is limited by thermal sintering, coke deposition, and undesired side reactions that compromise the stability and selectivity of the catalyst. This work reports the synthesis of a C₆₀-modified nickel-based catalyst (C₆₀–Ni/SiO₂), which was employed for the direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). Owing to its tailored electronic structure, the C₆₀–Ni/SiO₂ catalyst reached an ST formation rate of 2.7 mmol g⁻¹ h⁻¹ while maintaining a selectivity exceeding 99.0%. XRD, Raman, TEM, and XPS characterization revealed that the C₆₀ served as an electronic promoter, which decreased the electron density of Ni species without disturbing its crystalline structure. Such modulation of the electronic structure of Ni centers effectively suppresses the cracking side reactions and coke formation, thereby improving both selectivity and stability of the catalyst during EB DDH. The present work introduces a promising Ni-based catalyst for EB dehydrogenation, potentially offering prospects for developing advanced non-noble metal catalysts for alkene production via the DDH process.