Boosting the Production of Light Olefins from CO<sub>2</sub> Hydrogenation over Fe–Co Bimetallic Catalysts Derived from Layered Double Hydroxide
Fei Yuan, Guanghui Zhang, Mingrui Wang, Jie Zhu, Miao Zhang, Fanshu Ding, Zening Cheng, Chunshan Song, Xinwen Guo
Abstract
CO 2 hydrogenation to light olefins (C 2 –C 4 ═ ) is especially attractive for the chemical utilization of CO 2, and currently, effective catalysts are still under development. Herein, we report a succession of Fe–Co bimetallic catalysts derived from Fe–Co–Mg layered double hydroxides (LDHs) with different Fe/Co ratios [(c(Fe 3+ ) + c(Co 2+ ))/c(Mg 2+ ) = 1] for converting CO 2 to light olefins, which were also compared to MgO-supported Fe–Co prepared by the impregnation method. The best catalyst FeCo-9:1-LDH presented a high selectivity of C 2 –C 4 ═ over 36% at a CO 2 conversion higher than 40%. With ex / in situ characterization including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Mössbauer spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), we found that the Fe–Co–Mg LDH-derived catalyst (FeCo-9:1-LDH) is easily carburized to Co-modified iron carbide (Fe 5 C 2 ), which is superior to the FeCo-9:1-I catalyst synthesized by impregnating Co and Fe onto MgO support. The former shows a higher CO 2 conversion and higher C 2 –C 4 ═ selectivity, while the latter produces more CH 4 . This work provides a series of catalysts for selective hydrogenation of CO 2 to light olefins, as well as insights into the reaction pathway, favoring the rational design of CO 2 hydrogenation catalysts.