Isolated dual-active Fe-Co sites efficiently promote CO2 hydrogenation upgrading

• Published in: Fuel (Guildford) 2024-05, Vol.364, p.131054, Article 131054
• Main Authors: Wang, Xianbiao, Guo, Lisheng, Ai, Peipei, Wu, Hao, Lu, Zixuan, Huang, Jie, Tong, Jiancheng, Zheng, Liru, Sun, Song
• Format: Article
• Language: English
• Subjects: CO2 hydrogenation; Dual active sites; Fischer-Tropsch synthesis; Heavy hydrocarbon; Hydrothermal synthesis
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2024.131054

•Wall-protection isolated dual-active sites of Fe-Co catalysts were fabricated.•A controllable distribution of active Fe and Co sites in 3D structure was realized.•Catalyst with wall-protection could increase the specific surface area apparently.•The ordered distribution sequence of Fe and Co favored the formation of C5+. Carbon dioxide hydrogenation into valuable chemicals is an attractive strategy for CO2 fixation. Constructing bimetallic Fe-Co catalysts achieves high selectivity of heavy hydrocarbons instead of undesired methane is challenging, owing to the high methanation of cobalt. Herein, we develop an isolated dual-active sites of Fe-Co catalyst that separates Fe and Co via a carbon shell by multi-step impregnation combination with hydrothermal synthesis strategy. Fe-Co catalyst (C/FeCo3) with an intimate contact presents a high CH4 selectivity and low selectivity of C5+ hydrocarbon. However, C5+ hydrocarbon selectivity climbs from 19.8 % to 39.7 % over the cleverly designed wall-protection isolated dual-active sites of Fe-Co catalyst (C/Co3@C/Fe). The designed isolated structure between different active sites is conducive to chain propagation reaction by suppressing methanation reaction. As verified by in situ DRIFTS, more –CH2– species is enriched in the structure of C/Co3@C/Fe catalyst, which is considered as intermediate ingredient in the chain growth process. The designed structure catalyst strengthens the cascade reaction process of reverse water gas reaction and chain growth, and its combination with bimetallic catalysts may be a very potential measure for the preparation of bimetallic catalysts in the future.