Although it is generally acknowledged that iron carbides are the active phase in Fischer-Tropsch synthesis (FTS), adjusting the formation of active phase and catalytic performance via the initial crystal structure of iron oxides has never been studied. Herein, we take one-dimensional pure phase α-Fe₂O₃ and γ-Fe₂O₃ nonporous nanorods to explore the effects of initial crystal phase of Fe₂O₃ on both formation of active phase and corresponding catalytic performance, in which the influence of diffusion limitation on selectivity can be ignored. In situ characterizations uncovered that the formation of iron carbides with high selectivity of light olefins strongly depends on the initial crystal phase of iron oxide and its induced metal-promoter interaction. Responding to the morphology effect and crystallographic phase effect, Mn located on surface of γ-Fe₂O₃ nanorods exhibit a low oxidation state due to a strong Fe-Mn interaction. This interaction was beneficial to the formation of C-poor iron carbide species at the metal-promoter interface during carburization. Hence, outstanding selectivity for light olefins (61.2%) was achieved on 0.5 Mn/γ-Fe₂O₃ nanorods catalyst at a CO conversion of 55.1% under industrially relevant conditions (320 °C, 1 MPa, H₂/CO ratio of 1, and W/F = 5 g_cat h mol⁻¹). This finding enriches the fundamental understanding of active phase evolution and promoter effect in STO process and may guide the design of a catalyst with high selectivity.

尽管通常公认碳化铁是费-托合成（FTS）中的活性相，但从未研究过通过氧化铁的初始晶体结构调节活性相的形成和催化性能的问题。这里，我们取一维纯相的α-Fe ₂ ö ₃和γ-的Fe _2个ö ₃无孔纳米棒探索的Fe的初始晶相的影响₂ ö ₃上都形成活性相和对应的催化性能，其中扩散限制对选择性的影响可以忽略。原位表征表明，具有轻烯烃高选择性的碳化铁的形成在很大程度上取决于氧化铁的初始晶体相及其诱导的金属-促进剂相互作用。响应形态的影响和结晶相的效果，锰位于γ -铁的表面₂ ö _3个纳米棒表现出低氧化态由于强铁-锰交互。这种相互作用有利于在渗碳过程中在金属-促进剂界面形成C贫碳化铁物种。因此，对于轻烯烃（61.2％）优秀选择性为0.5上实现的Mn /γ-的Fe _2个ö _3个以55.1％工业相关的条件（320℃，1MPa下，H下CO转化催化剂纳米棒₂/ CO比为1，W / F = 5 g _cat h mol ^-1）。这一发现丰富了对STO过程中活性相演化和助催化剂作用的基本理解，并可以指导高选择性催化剂的设计。