Flower-like Al2O3-supported iron oxides as an efficient catalyst for oxidative dehydrogenation of ethlybenzene with CO2

- The surface of flower-like Al2O3 was rich in O2− anions.
- The surface O2− anions favored the formation of small FexOy clusters.
- The catalytic efficiency of iron oxide species was significantly enhanced.

An Al2O3 support with flower-like morphology was used as the support of iron oxide catalyst for oxidative dehydrogenation of ethylbenzene with CO2. A commercial Al2O3 was also used for comparison. These catalyst materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 physisorption, H2 temperature programmed reduction (H2-TPR), cyclic voltammetry (CV), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and CO2 temperature programmed desorption (CO2-TPD) techniques. It was found that the concentration of O2− anions on the flower-like Al2O3 surface was significantly higher than that on the commercial Al2O3 surface, leading to large amounts of highly dispersed FexOy clusters on flower-like Al2O3 in contrast with large Fe2O3 particles mainly present on commercial Al2O3. A possible formation mechanism of the small FexOy clusters was proposed. The catalytic results indicated that the highly dispersed FexOy clusters possessed an excellent catalytic activity, since the ethylbenzene conversion over Fe2O3/flower-like Al2O3 was 1.6 times higher than that over Fe2O3/commercial Al2O3. This work provides a new route for designing supported iron catalysts that are widely used, and flower-like Al2O3 is expected to be a promising catalyst support for oxidative dehydrogenation of ethylbenzene with CO2.