Kinetic and mechanistic studies of Fischer-Tropsch synthesis over the nano-structured iron–cobalt–manganese catalyst prepared by hydrothermal procedure

Abstract

The present research work is focused on the kinetic and mechanistic studies of the Fischer-Tropsch synthesis in a fixed bed micro reactor; over the nano-structured iron–cobalt–manganese catalyst prepared by hydrothermal procedure. Experimental conditions within the reactor were varied as follows: T=265–330°C, P=1.2–10bar, H2/CO feed ratio=0.5–2 and GHSV=4200h−1. Based on Langmuir–Hinshelwood–Hogan–Watson and Eley-Rideal adsorption theories in catalytic processes, 18 kinetic models for CO consumption were tested and interaction between dissociative adsorbed carbon monoxide and dissociative adsorbed hydrogen as the rate-determining step gave the best fitted kinetic model -rCO=kPbCOPCObH2PH221+2bCOPCO0.5+bH2PH20.56. The Levenberg–Marquardt algorithm was used to estimate the kinetic parameters and the obtained activation energy was 85.18kJ/mol for the optimal kinetic model. Characterization of catalysts was performed using XRD, FESEM, EDS, TEM and the N2 adsorption–desorption measurements such as BET and BJH methods.