A novel high-efficiency In-based catalyst for ethylbenzene dehydrogenation with CO2

A series of binary In₂O₃/S (S = Al₂O₃, SiO₂, and MgO) catalysts were fabricated by an incipient-wetness impregnation method, which were firstly applied in the ethylbenzene dehydrogenation under the presence of CO₂ (EBDH-CO₂). The synthesized catalysts were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption–desorption isotherm, temperature-programmed desorption of NH₃ and CO₂ (NH₃/CO₂-TPD), temperature-programmed reduction of H₂ (H₂-TPR), and X-ray photoelectron spectroscopy (XPS). It is found that the support can strongly impact on the crystalline phase, the dispersity, and the reduction properties of In₂O₃. The catalytic tests during the EBDH-CO₂ show that as compared to In₂O₃/MgO and In₂O₃/SiO₂ with the merely existence of bulk In₂O₃ particles, the In₂O₃/Al₂O₃ catalyst gives the highest catalytic activity and good stability, which can be principally ascribed to the synergistic effect of the bulk In₂O₃ and in situ metallic In formed by the reduction of the well-dispersed In₂O₃ on the Al₂O₃ surface. It therefore affirms that attaining an appropriate support to disperse the active phase In₂O₃ becomes the decisive factor to achieve both superior catalytic activity and satisfied selectivity towards styrene.