Direct conversion of CO₂ to light olefins over FeCo/XK-ϒAL₂O₃ (X = La, Mn, Zn) catalyst via hydrogenation reaction

The conversion of CO₂ to value-added products such as olefins is one of the suggested strategies in carbon dioxide utilization for tackling climate change. Although hydrogenation of CO and CO₂ to olefins has been extensively studied, still further research is required to design more active and selective catalyst for this process. In this study, we implemented a modification strategy by using multi-metallic promoters (K-X, X: La, Mn, Zn) in the Fe-Co/ϒ-Al₂O₃ network to develop more efficient catalyst formulations for olefin synthesis from CO₂ hydrogenation. X-ray diffraction, N₂-physisorption, hydrogen temperature-programmed reduction, NH₃-temperature-programmed desorption, thermogravimetric analysis and X-ray photoelectron spectroscopy were performed to study the physicochemical properties of the synthesized catalysts. The results indicate that the application of assistant promoters influences the catalyst reducibility and surface structure and also changes the product distribution. The addition of La and Mn improves slightly the electron density of iron species and suppresses H₂ adsorption and hence shifted the observed product selectivity toward olefins and suppressed methane formation. Moreover, the presence of Zn facilitates the reduction properties and increases the H₂ consumption and therefore, led to higher methane formation of 44.9% in comparison to the catalysts using La and Mn. The inclusion of assistant promoters reduced the conversion of CO₂ from 30% (FeCo-K) to 22% and enhanced the olefins selectivity. Graphical abstract: [Figure not available: see fulltext.]