MgFe0.1Al1.9O4 的合成及其催化乙苯与 CO2 的氧化脱氢反应

 以柠檬酸为络合剂, 采用溶胶-凝胶法制备了具有尖晶石结构的 MgFe_0.1Al_1.9O₄ 催化剂, 并将其用于催化乙苯与 CO₂ 氧化脱氢反应. 运用 X 射线衍射、X 射线能量色散光谱分析、红外光谱、热重-差热、N₂ 吸附-脱附和 H₂ 程序升温还原等技术对催化剂进行了表征. 结果表明, 在 650 ºC 以上焙烧即可制得结构确定、组成均一的 Mg-Fe-Al-O 复合氧化物催化剂, 其中 Fe 物种主要以同晶取代的形式存在于尖晶石骨架中. 随着焙烧温度的升高, 尖晶石结晶度提高, Fe 物种还原能力下降, 催化剂晶粒度增大, 比表面积降低. 700 ºC 焙烧制备的 MgFe_0.1Al_1.9O₄ 具有较好的催化乙苯与 CO₂ 氧化脱氢反应活性和稳定性.

Preparation and Catalytic Properties of MgFe0.1Al1.9O4 in Oxidative Dehydrogenation of Ethylbenzene with CO2

The MgFe_0.1Al_1.9O₄ catalyst with spinel structure was prepared by a sol-gel method using citric acid as the gelatinizer and was tested for dehydrogenation of ethylbenzene with CO₂ at 600 ºC. The formation temperature of the spinel phase and the dispersion state of Fe species were characterized by X-ray diffraction, X-ray energy dispersive analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, N₂ adsorption-desorption, and temperature-programmed reduction. The results indicate that the ternary-composite oxide catalyst of Mg-Fe-Al-O with a well-proportioned chemical composition, in which the Fe³⁺ species exist in spinel framework, can be obtained at the temperature higher than 650 ºC. With the increase in the preparation temperature, both the crystallinity and grain size of the catalyst increase and the reduction of Fe species decreases. MgFe_0.1Al_1.9O₄ prepared by calcination at 700 ºC shows high activity and good stability for the ethylbenzene dehydrogenation with CO₂ during 20 h time on stream.