Fabrication of Fe2C Embedded in Hollow Carbon Spheres: a High‐Performance and Stable Catalyst for Fischer‐Tropsch Synthesis

Abstract

AbstractThe Fischer−Tropsch synthesis (FTS) is a non‐petroleum‐based alternative route, which directly produces fuels and value‐added chemicals (e. g. lower olefins) from coal‐, biomass‐ or natural gas‐derived syngas. The ϵ‐iron carbide, such as Fe2C, has been predicted to be active but not stable under high‐temperature FTS conditions. In this work, we have fabricated a novel catalyst with Fe2C embedded in hollow carbon spheres (HCS) by pyrolyzing the coated polymer and Fe(NO3)3 on silica spheres and then etching the hard template. XRD, XPS, TEM and N2 physical adsorption were employed to characterize the evolution and properties of as‐prepared catalysts, which significantly depend on pyrolysis temperature. Under FTS conditions, the obtained catalysts exhibit good dispersion, robustness of geometric construction, and resistance to sintering. More importantly, Fe2C was confirmed as the dominant and stable iron carbide species. The unique chemical surrounding and confinement effect provided by carbon matrix contribute to these peculiarities that are responsible for superior activity and stability in FTS. Furthermore, we found that the products distribution could be manipulated by changing the geometric diameters of HCS, due to the tunable CO/H2 ratio.