Surface Reconstruction and Catalytic Activity of Iron-Based Fischer-Tropsch Catalysts Derived from Nigerian Magnetite Ore Under In Situ Conditions

This study investigates the surface reconstruction phenomena and catalytic activity evolution of iron-based Fischer-Tropsch synthesis (FTS) catalysts derived from magnetite ore obtained from deposits in Kogi State, North Central Nigeria, under in situ reduction and reaction conditions. Fischer-Tropsch technology is a potential pathway for converting Nigerian natural gas and coal resources into liquid fuels, and the development of catalysts from locally available iron ore feedstocks would reduce dependence on imported catalyst materials. Fe3O4 magnetite concentrate is reduced under H2 and syngas atmospheres at temperatures of 300 to 600 degrees Celsius, and the structural and phase evolution during reduction and FTS activation are tracked by in situ XRD, Mossbauer spectroscopy, and environmental transmission electron microscopy (ETEM). Surface area evolution is monitored by BET analysis at synthesis gas exposure intervals. Carbon deposition and carburisation kinetics (formation of Hagg carbide, chi-Fe5C2) are characterised as a function of syngas H2/CO ratio and temperature. FTS activity and selectivity (C5+ liquid product fraction) are correlated with the degree of carburisation and iron surface area. Findings identify the carburisation rate and the stabilisation of an active Hagg carbide phase as critical determinants of catalyst activity and long-term stability. The study establishes structure-activity relationships relevant to catalyst design from Nigerian iron ore feedstocks. Keywords: Fischer-Tropsch catalyst, magnetite, iron carbide, surface reconstruction, Kogi State.