Catalytic and kinetic evaluation of Fe/HZSM-5 catalyst for Fischer-Tropsch synthesis

• The Fe/HZSM-5 catalyst was stable over 72 h testing without coke formation. • Carbon monoxide conversion was greater than 50% • Selectivity of 37% was achieved to C 5 -C 8 hydrocarbons. • The first kinetic model for the Fe/HZSM-5 catalyst in FTS reaction was developed. • FTS on Fe/HZSM-5 followed a carbide mechanism with competitive CO 2 adsorption. Rising global energy and growing environmental concerns demand cleaner production methods for fuels and platform chemicals. The Fischer-Tropsch synthesis (FTS) is a promising alternative to fossil oil sources for producing valuable hydrocarbons directly from syngas (CO and H 2 ) such as light olefins and middle distillates. Due to their cost-effectiveness and bifunctional properties, Fe/HZSM-5 catalysts have gained recent interest for FTS. However, research on reaction conditions and CO consumption kinetics for this catalyst remains limited. This work addresses a comprehensive study encompassing catalyst characterization, catalytic activity evaluation, and kinetic modeling of Fe/HZSM-5 catalysts for FTS. Our data showed that Fe presented multiple reduction stages and changed the moderate acidity of the evaluated zeolites upon Fe impregnation. Fe 2 O 3 particles were also found to be transformed into iron carbides species during the catalytic reaction according to the Mössbauer spectroscopy. The catalysts were active and stable for FTS (X CO > 50 %) with a major production of hydrocarbons in C 2 -C 4 and C 5 -C 8 ranges. Pressure, temperature, feed composition and space velocity significantly influenced the CO conversion. The kinetic model for the Fe/HZSM-5 catalyst was investigated by modeling and in situ DRIFTS, aligning with the carbide mechanism considering dissociative adsorption of CO and H 2 , a two-site reaction pathway, and competitive adsorption between CO and CO 2 on the metal sites. These findings provide important insights for optimizing catalyst design and reaction conditions to enhance the efficiency of syngas-based fuel production.