构建石墨烯限域稳定的ε-Fe2C用于高效费-托合成反应的方法与机制研究

高效铁基费-托催化剂活性中心的精准设计与构建极大受限于碳化铁活性相在反应过程中的复杂变化。已有研究确认ε-Fe2C由于具有较好的CO解离吸附能力是超高活性相，但ε-Fe2C仅在低温活化或反应条件下（<200℃）稳定存在。本项目利用非致密石墨烯层的限域稳定及调制作用，抑制ε-Fe2C向θ-Fe3C等低活性物相的转变，构筑在贴近生产实际条件（250~340 ℃）下稳定的高活性相ε-Fe2C，从而实现较高温度下高活性和高稳定性的耦合。通过调控非致密石墨烯层的表界面结构，结合实验和理论计算，深入研究石墨烯对活性相ε-Fe2C的调控机制，阐明该材料在高效费-托合成中的CO活化与碳链增长等过程的催化作用机制。同时，综合利用各种相关的原位及离线表征手段，进一步研究石墨烯限域稳定下ε-Fe2C相的形成过程及其在反应过程中的结构演变，阐明非致密石墨烯层对铁基催化剂相转变和积碳失活的抑制作用。

The rational design of iron-based Fischer-Tropsch synthesis catalysts and active phase accurate control is challenged by the complex phase and structure transformation during activation and reaction processes. Existing research has concluded that ε-Fe2C is the super-active phase due to its high CO dissociative adsorption capacity, but ε-Fe2C is stable only at low-temperature activation and reaction conditions (＜200 ℃). This proposal will utilize confinement effect of graphene shell, preventing phase transfer from ε-Fe2C to θ-Fe3C with low activity, obtaining stable ε-Fe2C active phase under real industrial reaction conditions (250~340 ℃), coupling high activity and high stability under relatively high-temperature conditions. By modifying graphene shell structure, combining experimental and theoretical calculation, we will investigate graphene confinement effect on ε-Fe2C surface structure, illustrating its mechanism in Fischer-Tropsch synthesis such as CO activation and carbon chain building. On the other hand, we will apply various in-situ and ex-situ characterization techniques to further study the formation process of ε-Fe2C phase by graphene confinement and its structure under reaction process, clarifying why graphene confinement effect can prevent active phase transformation and catalyst deactivation by coking.