Operando high-pressure combined soft XAS/XPS of Iron nanoparticle catalysts during Fischer-Tropsch Synthesis

Iron-based catalysts are promising for Fischer–Tropsch Synthesis (FTS) because they are inexpensive, abundant, and can process syngas feeds with low H₂/CO ratios through the water–gas shift reaction. However, the identity of the active phases in Fe-based FTS remains debated. Iron undergoes dynamic changes among oxides, metallic Fe, and carbides under reaction conditions, but it is unclear which carbide is most active and how nanoparticle size influences stability and selectivity.

We propose to investigate these questions using operando high-pressure soft X-ray absorption spectroscopy (sXAS) and X-ray photoelectron spectroscopy (XPS) at the BL24 CIRCE beamline. Size-selected Fe nanoparticles (4, 8, and 12 nm) will be studied under H₂/CO mixtures at 1 and 4 bar to follow the oxide–metal–carbide transformation in real time. The high brilliance and tunable energy of synchrotron radiation are essential to probe these systems on suspended graphene membranes. The results will clarify the role of nanoparticle size in determining the active carbide phases and will support the rational design of more active and selective iron-based catalysts for sustainable fuel production.