In situ synthesis of highly dispersed Fe/C catalysts with pomelo peel as carbon source in CO2 hydrogenation to light olefins

Abstract

Although considerable progress has been made in the hydrogenation of CO2 to light olefins through the modified Fischer-Tropsch synthesis route (CO2-FTS), the design of catalysts with high selectivity and stability is still a challenge. Herein, a simple, highly dispersed and scalable Fe/C-400 catalyst was prepared by in-situ pyrolysis using pomelo peel (PP) as carbon source, and was first used in CO2 hydrogenation to light olefins. This catalyst exhibited a high space time yield of light olefins (48.3 μmolCO2·gFe−1·s−1), and the light olefins selectivity and O/P were 63.0% and 9.0, respectively. More surprisingly, no obvious deactivation was observed within 200 h. A series of characterization techniques such as TEM, TG-MS, FTIR, XPS, H2-TPR and 57Fe Mössbauer spectrum showed that the naturally abundant oxygen-containing functional groups in PP support could impart metal-support interactions that enhance the dispersion of iron species. The modulation of the catalyst phase composition was achieved by simply varying the residual amount of oxygen-containing functional groups to impart different metal-support interactions. The catalysts prepared at lower pyrolysis temperatures retained more oxygen-containing functional groups and therefore had stronger metal-support interactions, which facilitated the formation of more active phases. Overall, this newly developed catalyst realized the high activity and high stability production of CO2 hydrogenation to light olefins, providing a cost-effective and sustainable way for its industrial application.