Zhuo Ou, Yang Lijun, Gao Fujie, Xu Bolian, Wu Qiang, Fan Yining, Zhang Yu, Jiang Yufei, Huang Runsheng, Wang Xizhang, Hu Zheng
Key Laboratory of Mesoscopic Chemistry of MOE , School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China . Email:
School of Physics , Nanjing University , Nanjing 210093 , China.
Chem Sci. 2019 May 20;10(24):6083-6090. doi: 10.1039/c9sc01210a. eCollection 2019 Jun 28.
Fischer-Tropsch synthesis of lower olefins (FTO) is a classical yet modern topic of great significance in which the supported Fe-based nanoparticles are the most promising catalysts. The performance deterioration of catalysts is a big challenge due to the instability of the nanosized active phase of iron carbides. Herein, by mass spectrometry, theoretical analysis, and atmospheric- and high-pressure experimental examinations, we revealed the Ostwald-ripening-like growth mechanism of the active phase of iron carbides in FTO, which involves the cyclic formation-decomposition of iron carbonyl intermediates to transport iron species from small particles to large ones. Accordingly, by suppressing the formation of iron carbonyl species with a high-N-content carbon support, the size and structure of the active phase were regulated and stabilized, and durable iron-based catalysts were conveniently obtained with the highest selectivity for lower olefins up to 54.1%. This study provides a practical strategy for exploring advanced FTO catalysts.
费托合成低碳烯烃（FTO）是一个经典而又具有重大意义的现代课题，其中负载型铁基纳米颗粒是最具潜力的催化剂。由于碳化铁纳米活性相的不稳定性，催化剂性能恶化是一个巨大挑战。在此，通过质谱分析、理论分析以及常压和高压实验研究，我们揭示了FTO中碳化铁活性相的类奥斯特瓦尔德熟化生长机制，该机制涉及羰基铁中间体的循环形成 - 分解，以将铁物种从小颗粒传输到大颗粒。因此，通过用高氮含量的碳载体抑制羰基铁物种的形成，活性相的尺寸和结构得以调控和稳定，从而方便地获得了耐久性铁基催化剂，其对低碳烯烃的最高选择性可达54.1%。本研究为探索先进的FTO催化剂提供了一种实用策略。
