Selectivity regulation of olefin production via CO2 hydrogenation over iron-based catalysts with high manganese content

The hydrogenation of carbon dioxide to value-added olefins remains challenging due to the limited CO 2 adsorption capacity and poor high-temperature stability of conventional iron-based catalysts, which restrict olefin selectivity. Herein, a series of x Mn y Fe catalysts with high Mn content are synthesized, and 3 wt% potassium is introduced as promoter. The results show that an appropriate Mn incorporation promotes the formation of the active Fe 5 C 2 phase, enhances CO 2 adsorption, and improves catalyst thermal stability. Meanwhile, K promoter increases surface basicity, effectively suppressing methane formation and significantly enhancing light olefin selectivity. Among the catalysts studied, 3K30Mn70Fe exhibits the optimal performance, achieving CO 2 conversion of 41.7% and a total olefin selectivity of 66.0%, with light olefins (C2-C4 = ) accounting for 41.1%. Furthermore, increasing the weight hourly space velocity (WHSV) further improves the total olefin selectivity, reaching 72.4% at a WHSV of 7200 mL g −1 h −1 . These findings demonstrate the synergistic roles of Mn and K in regulating the structure and catalytic behavior of iron-based catalysts, providing valuable insights for the rational design of efficient catalysts for CO 2 hydrogenation to olefins.