Detailed kinetics of Fischer–Tropsch synthesis on a precipitated iron catalyst

Abstract

A Langmuir–Hinshelwood–Hougen–Watson kinetic model for FTS hydrocarbon production rates is developed. The concept of dual Anderson–Schulz–Flory (ASF) distribution with two chain growth probabilities is used for developing the kinetic model. The experiments were carried out in a continuous spinning basket reactor. The iron catalyst promoted by lanthanum as a low basic promoter is used for activity evaluations. The results show that the kinetic model developed by dual ASF product distributions is more consistent with experimental results than simple ASF. The activation energy for the formation of methane, ethane and ethylene are calculated as 68, 76 and 72 kJ mol⁻¹, which can explain the lower selectivity of ethane than ethylene. The activation energy for paraffin formation with lower carbon number is 91 kJ mol⁻¹ and for paraffin formation with larger carbon number is 102 kJ mol⁻¹, which can explain the lower selectivity of heavy paraffins. Also, the activation energy of light olefin formation is 98 kJ mol⁻¹ and the activation energy of heavy olefin formation, is 148 kJ mol⁻¹.