基于应变工程调控的Mn/Fe/FeCrAl合金纤维催化材料FTO性能研究

煤、天然气和生物质经费托合成直接制备低碳烯烃（FTO）的非石油路线符合国家能源战略需求。碱金属电子助剂K、Na与S或Mn协同改性存在水溶流失隐患和积碳现象。拟采用原位水热合成法制备Mn/Fe/FeCrAl纤维催化材料，对FeCrAl基底施加机械外力，将应变工程引入催化剂中，改变铁外层d电子结构，调控CO和H2在催化剂表面的化学吸附行为，控制C─C偶联及初级烯烃再吸附引发的二次加氢反应。应变工程不改变催化剂的组成，可解决催化剂的组成稳定性、水热稳定性和机械稳定性问题，同时该催化体系有助于以准原位手段探究活性中心结构和催化反应机理。本研究预期强化应变工程与Mn助剂的协同效应，构筑出高活性、富产低碳烯烃且稳定性优异的FTO催化剂。预研工作证明适宜的应变能显著提高铁基费托合成反应活性和低碳烯烃选择性，使本项目有望为高效稳定的FTO催化剂设计提供新策略，并推广到更多金属基加氢催化剂的开发中。

The non-petroleum and direct route of Fischer-Tropsch synthesis to lower olefins (FTO) derived from coal, natural gas and biomass meets energy strategic needs. Although the synergistic effect between alkali elements of K、Na along with S or Mn promoters can improve the lower olefins selectivity of iron-based catalysts, problems emerge from the gradual loss and carbon deposition caused by these alkali elements. An in-situ hydrothermal method is employed to synthesize Mn/Fe/FeCrAl microfibers. The strain engineering is indirectly introduced via applying mechanical stress to FeCrAl microfibers. The strain has been shown to change the electronic structure of metal d states and then modify the surface chemisorption properties of the metal. By tailoring the dissociation adsorption and hydrogenation of CO, the reaction of C─C coupling and the secondary hydrogenation of primarily formed α-olefins are controlled. Meanwhile, the unique strain-introduced system is helpful to study the structure of active phase and catalytic mechanism without changing the original composition of the iron-based catalysts, which enhances the structural stability, hydrothermal stability and mechanical stability. It is expected that the efficient FTO catalysts would be constructed by strengthening the synergistic effect of strain and Mn promoter. Our previous research has indicated that the appropriate strain introduced in iron-based catalysts could significantly increase the activity and lower olefins selectivity of Fischer-Tropsch synthesis, which suggest that the strain can in general be used as a novel strategy to design the efficient FTO catalysts and other metal catalysts for CO hydrogenation.