Probing The Structure Evolution of Iron‐Based Fischer–Tropsch to Produce Olefins by Operando Raman Spectroscopy

By using operando Raman spectroscopy (ORS), we investigated the panoramic structure evolution of an iron oxide (α‐Fe2O3) catalyst, which is used for the production of olefins via Fischer–Tropsch (FTO). During activation in different atmospheres and reaction at 260 °C and 3.0 MPa, α‐Fe2O3 was only partially transformed into γ‐Fe2O3 by H2 pretreatment; meanwhile, a transformation of α‐Fe2O3→γ‐Fe2O3→Fe3O4→Fe5C2 was observed in both CO and syngas (H2/CO). Combining with other techniques such as XRD, TEM, XPS and TPSR, we reveal that assembles of various iron oxides (γ‐Fe2O3, Fe3O4, Fe carbide, and their combinations) are responsible for FTO. Especially, the preliminary relationship of catalyst structure and performance relating to the production of olefins directly from syngas was established. Such a study is critical for further understanding of the FTO reaction and other catalytic reactions.