利用动态现场原位技术研究费-托合成制烯烃铁基催化剂活性相演变机制

Fischer-Tropsch to Olefins (FTO) reaction involves complexity of products combined with interactions of elementary reactions, thus resulting in difficulties in controlling the product distribution. Moreover, the dynamic structural evolution of Fe-based catalysts, which may easily interact with reactants during the harsh reaction conditions, is hard to be accurately described. In this proposal, by combining operando spectroscopy and molecular simulation, we will reveal structure evolution and modulation mechanism of catalytic materials for FTO. Three processes are studied, including the origin, evolution and annihilation of active phase of Fe-based catalysts. As a result, the strategy of rational design and controllable preparation of catalysts will be established. Firstly, starting from reproducible and model catalysts, we make efforts on acquiring the information of catalyst performance under real reaction conditions. Secondly, the effects of temperature, pressure and atmosphere on the origin, evolution and deactivation of active phase, and corresponding structure changes on catalyst performance in realistic conditions will be studied using a serial of operando techniques and in situ techniques. In addition, coupling quantum Density Functional Theory (DFT) with molecular kinetics, the formation mechanism and dynamic process of catalyst active phase will be obtained. Finally, on the basis of accurate establishment of structure-performance relationships, the approach for the design of catalysts will be achieved by elaborately modulating the catalyst structures with the controllable preparation methods.

费-托合成制低碳烯烃（FTO）工艺副反应多，产物分布难以控制。在高温、高压反应过程中，Fe基催化剂易与反应物作用发生动态结构变化，难以准确建立真实反应条件下的构-效关系。本项目拟结合动态现场原位技术和计算机分子模拟手段，研究费-托合成制低碳烯烃反应过程中Fe基催化剂在活性相起源、演变和湮灭过程中的结构演化及调控机制，从而建立Fe基催化剂的“理性设计”和“可控制备”研究策略。首先，从可重复制备的模型催化剂出发，通过催化剂性能评价筛选高性能催化剂。然后，通过高温、高压动态现场原位光谱与各种原位技术，研究温度、压力和气氛对催化剂在活性相起源、演变和失活过程中的物理、化学结构变化影响，以及这些结构变化对催化性能的影响。此外，结合传统量子密度泛函和多尺度分子动力学，研究活性相动态形成机制以及催化反应机理。最后，在准确建立的构-效关系基础上，设计并可控制备高选择性Fe基FTO催化剂。

低碳烯烃是重要的化工原料，传统生产工艺严重依赖石油资源。依托合成气化工，直接法费托合成制低碳烯烃是非石油路线生产烯烃的新途径，也是煤炭资源洁净高效利用的重要方向。在高温、高压反应过程中，Fe基催化剂易与反应物作用发生动态结构变化，难以准确建立真实反应条件下的构-效关系。项目结合动态现场原位技术和密度泛函理论，构建了Fe基催化剂FTO反应过程构-效关系，重点聚焦反应过程中催化剂活性相的动态结构变化规律，为实现高效催化剂的理性设计提供思路。通过多种原位及非原位表征技术，建立了各种Fe基前驱体在不同活化气氛诱导下的活性结构与反应性能间的关系。此外，项目还对单组份Fe催化剂“全生命周期”构-效关系进行了研究，揭示了催化剂的失活机理及再生方法。项目发表论文11篇，申请专利2项。