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), Mossbauer effect spectroscopy (MES), H-2 temperature-programmed desorption (TPD), and laser Raman spectroscopy (LRS) before and after the reaction. The results indicated that the catalysts consisted predominately of alpha-Fe particles following the H(2)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 alpha-Fe particles, and the rate of the carburization process could be effectively controlled using C2H4. Compared with the catalysts activated with H-2 or syngas, the catalysts initially activated with H-2 followed by C2H4 exhibited better performance in the FTS. (C) 2013, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.