焙烧温度对乙苯脱氢催化剂Fe2O3-K2O性能的影响

Effect of Calcination Temperature on Properties of Fe_2O_3-K_2O Catalyst for Dehydrogenation of Ethylbenzene

用混合法制备了Fe2O3-K2O乙苯脱氢催化剂,并用压汞法、X射线衍射、穆斯堡尔谱、程序升温还原和热重-差热分析等表征手段,考察了焙烧温度对催化剂的催化活性、比表面积、体相结构和还原性能的影响.结果表明,随着焙烧温度的升高,催化剂的比表面积逐渐减小,平均孔径逐渐增大;尖晶石K2Fe22O34中正四面体Fe3+的含量逐渐减少,正八面体Fe3+的含量逐渐增多,催化剂逐渐变得容易被还原;催化剂的催化活性差别不大,但达到平稳时所需的诱导期逐渐缩短.过高的焙烧温度不利于催化剂的稳定性.

The Fe2O3-K2O catalyst for ethylbenzene dehydrogenation was prepared by a mixing method. The structure and reduction properties of the catalyst calcined at different temperatures were characterized by X-ray diffraction, Mossbauer spectroscopy, mercury intrusion porosimetry, temperature-programmed reduction, and thermogravimetric analysis-differential thermal analysis. The results showed that, with the increase of calcination temperature, the specific surface area of the catalyst was decreased, but its average pore diameter increased. The calcination temperature also had effect on the structure of K2Fe22O34, the precursor of active phase of the catalyst, leading to the decrease in the content of Fe^3＋ on tetrahedral site and the increase in the content of Fe^3＋ on octahedral site, and the catalyst became more reducible. The induction period for the catalyst stationary activity was decreased with the increase in calcination temperature and too high calcination temperature would deteriorate the catalyst stability