铁基费托合成催化剂相变调控及反应性能

在Fe基模型催化剂上,通过先深度还原后控制碳化的方法实现了物相结构的调控.采用X射线衍射、穆斯堡尔谱、程序升温脱附技术和激光拉曼光谱等方法表征了催化剂还原和反应前后的物化性质,并在固定床反应器中考察了不同条件活化后催化剂上费托反应性能.结果表明,H₂还原后的催化剂主要由α-Fe相组成,且随着还原温度的提高,α-Fe相的致密程度增加,平均晶粒尺寸增加,稳定性提高;再采用乙烯对H₂还原后催化剂进行碳化,可有效控制α-Fe的碳化速度,使碳化过程主要发生在Fe晶粒表层,同时改变了催化剂在反应过程中的物相变化,乃至其催化性能.与纯H₂或合成气气氛活化的催化剂相比,采用先H₂还原后乙烯碳化的预处理方法能够明显提高催化剂的活性和稳定性.

Controlling the phase transformations and performance of iron-based catalysts in the Fischer-Tropsch synthesis

The phase transformations of a series of iron-based models of the catalysts used in the Fischer-Tropsch synthesis (FTS) were controlled using a combination of deep reduction followed by partial carburization. The catalysts were pretreated under a variety of different conditions and their performance in the FTS subsequently tested in a fixed-bed reactor. The physiochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Mössbauer effect spectroscopy (MES), H₂ temperature-programmed desorption (TPD), and laser Raman spectroscopy (LRS) before and after the reaction. The results indicated that the catalysts consisted predominately of α-Fe particles following the H₂ reduction. The size of the crystals and the stability of the catalysts increased with increasing reduction temperature. The carburization process mainly occurred on the surface of the α-Fe particles, and the rate of the carburization process could be effectively controlled using C₂H₄. Compared with the catalysts activated with H₂ or syngas, the catalysts initially activated with H₂ followed by C₂H₄ exhibited better performance in the FTS.