Research progress on the in-situ characterizations of iron-based FTS catalysts pretreatment process

Fe-based Fischer-Tropsch synthesis (FTS) catalysts usually exist as the oxide precursor α-Fe₂O₃, which have different catalytic activities after being transformed to Fe_xC_y under different pretreatment conditions, so it is critical to study the pretreatment process of α-Fe₂O₃ for whole FTS reaction. However, the phases of Fe-based catalysts in such a process are highly dynamic and complex, and conventional characterizations cannot capture the accurate real-time information in the pretreatment reaction. Therefore, it is necessary and desired to apply various in-situ characterizations in this process, because they can obtain the dynamic changes of phase, morphology, surface structure and properties of the catalyst. And then a relationship between the pretreatment process and the subsequent catalytic performance of FTS will be effectively and reasonably established. This review presents a systematic summary of the experimental and data processing methods in in-situ characterizations of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy and Raman spectroscopy during the pretreatment of Fe-based FTS catalysts. These characterizations can clarify the complex structure and surface property changes of catalyst precursors and thus will facilitate the design and development of more efficient Fe-based FTS catalysts.