All the spent Fe-based catalysts presented distinct diffraction peaks of Fe5C2 species and relatively weak diffraction peaks of Fe3O4 species, which were the active phases for the RWGS and FTS reactions, respectively . Besides, MnCO3 species formed during the reaction due to the presence of CO2 under reaction conditions (Fig. ) . In addition, high-resolution transmission electron microscopy showed the lattice spacing of 2.41 and 2.76 Å attributed to the (226) and (216) plane of Fe3O4, and 2.08 Å attributed to the (021) plane of Fe5C2, respectively. Z5 was highly crystalline and appeared to be cuboid crystals ranged from 200 to 400 nm (Fig. ). The (101) crystalline surface lattice attributed to the ZSM-5 species could be observed by the HR-TEM image. At the same time, Z5 was proved to have moderate acidic sites by NH3-TPD (Fig. ), which could catalyze oligomerization, isomerization and aromatization of light olefins.