Kinetic study based on the carbide mechanism of a Co-Pt/γ-Al₂ O₃ Fischer–Tropsch catalyst tested in a laboratory-scale tubular reactor

A Co-Pt/γ-Al₂ O₃ catalyst was manufactured and tested for Fischer–Tropsch applications. Catalyst kinetic experiments were performed using a tubular fixed-bed reactor system. The operative conditions were varied between 478 and 503 K, 15 and 30 bar, H₂ /CO molar ratio 1.06 and 2.11 at a carbon monoxide conversion level of about 10%. Several kinetic models were derived, and a carbide mechanism model was chosen, taking into account an increasing value of termination energy for α-olefins with increasing carbon numbers. In order to assess catalyst suitability for the determination of reaction kinetics and comparability to similar Fischer–Tropsch Synthesis (FTS) applications, the catalyst was characterized with gas sorption analysis, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) techniques. The kinetic model developed is capable of describing the intrinsic behavior of the catalyst correctly. It accounts for the main deviations from the typical Anderson-Schulz-Flory distribution for Fischer–Tropsch products, with calculated activation energies and adsorption enthalpies in line with values available from the literature. The model suitably predicts the formation rates of methane and ethylene, as well as of the other α-olefins. Furthermore, it properly estimates high molecular weight n-paraffin formation up to carbon number C₈₀.