乙苯氧化脱氢反应Fex/TiO2的催化性能研究

Oxidative dehydrogenation of ethylbenzene to styrene has been studied in this paper over a novel TiO2 supported iron catalyst (Fex/TiO2) at low temperature. Here, x stands for the mol percent of iron among the catalyst. The catalysts were prepared by isovolumetric impregnation method. The solution of Fe(NO3)3 with a fixed ratio to TiO2 was impregnated into the powder of TiO2, keeping standing for 24 h～48 h and then taking it to a dryer at 120 ℃ for drying. Before it could be used, it would be calcined at a programmed temperature and then ground to a defined size. The factors involved in the dehydrogenation reaction, such as the loading amount of active component, calcined temperature during catalyst preparation, reaction temperature, particle size etc. have been investigated. By means of X-ray diffraction (XRD), thermogravimetry analysis (TGA), physical adsorption and pore size distribution and scanning electrical microscopy (SEM) analytical techniques, the function of catalyst was discussed. The results showed that Fe7/TiO2 is the optimal catalyst for the selective oxidehydrogenation of ethylbenzene at 350 ℃, 14.6% ethylbenzene conversion and 99.0% styrene selectivity were obtained in each run. Lower calcined temperature is favored for the preparation of Fex/TiO2 catalyst, at which the microstructure of active components was well controlled. Higher reaction temperature would lead to the side-reactions happened and the decrease of styrene selectivity. The deactivation of Fex/TiO2 catalyst is due to the loss of Fe active components.