Enhanced catalytic performance of CeO 2 confined inside carbon nanotubes for dehydrogenation of ethylbenzene in the presence of CO 2

Abstract

Carbon nanotubes (CNTs) filled with CeO 2 particles are prepared by wet impregnation assisted by capillary force. Compared to CeO 2 outside CNTs, these composites show superior catalytic performance of oxidative dehydrogenation (ODH) of ethylbenzene (EB) to styrene in the presence of CO 2. Transmission electron microscopy, temperature-programmed reduction, Raman and X-ray photoelectron spectroscopy are used to investigate the effect of CNT confinement on the catalytic performance of CeO 2 inside CNTs. The results indicate that CNT tubular structure results in strengthened interaction between CeO 2 and inner wall, which induces distortion and reducibility of CeO 2 lattices to promote the activation of surface lattice oxygen and the formation of oxygen vacancy. The activated surface oxygen and oxygen vacancy from CeO 2-CNT composites play an important role in two-step ODH reaction by promoting reverse water-gas shift reaction. In addition, CeO 2 filled into shorter CNTs exhibits higher catalytic activities due to decreasing the diffusion resistance of reactants and products in CNT channels. The fact that CeO 2-CNT composites exhibit excellent thermostability in the atmosphere of CO 2 provides a positive choice for enhancing catalytic efficiency at elevated temperature using CNTs as supports. © 2012 Elsevier B.V.