Heteroatom induced synthesis of FeO-Fe3C confined within F-doped graphene shell for efficient CO2 hydrogenation to light olefins

The non-metal elements (B, P, F, and Se) were introduced to construct mesoporous carbon confined FeO-Fe3C active sites, which were applied for CO2 hydrogenation to light olefins reaction successfully. The evolution of Fe species was extensively studied using in-situ XRD technology and the TGA (Thermogravimetric Analysis) method, revealing that the introduction of F not only triggers the formation of FeF2, which can be easily reduced to Fe0, but also elevates the O vacancy density in FeO, which promotes the adsorption and dissociation of CO2 molecular. The formation of Fe3C active sites within mesoporous carbon channels requires a collaborative effort from various components (such as PTFE (Polytetrafluoroethylene), F127 (Soft template), and PR (Phenolic Resin)). The addition of the K promoter reconstructed the electron-rich active sites, thus playing a crucial role in enhancing the yield of light olefins. The 0.8Fe@0.28F-MC + 0.02K exhibited exceptional activity and stability, resulting in a remarkable CO2 conversion of 42.6 % and a light olefin selectivity of 53.4 %. Furthermore, the catalyst maintained stability over a prolonged period of 100 h. This work sheds deep insight into the synthesis mechanism of the Fe3C active site, providing a simple and efficient preparation strategy of Fe3C confined in F -doped graphene shell that catalytic CO2 hydrogenation to light olefins efficiently.