Formulation of KMoFe/CNTs catalyst for production of light olefins and liquid hydrocarbons via Fischer-Tropsch synthesis: Fixed-bed reactor simulation

[Display omitted] •FTS performance of promoted iron catalysts supported on CNTs were investigated.•Hydrophobicity of catalysts was compared by the water contact angle measurement.•The carburization degree of catalysts was compared by XPS and XAS spectra.•COMSOL Multiphysics was used to simulate the FTS fixed-bed reactor. Light olefins and C5+ are strategically important products of Fischer-Tropsch synthesis (FTS) over Fe catalysts. In the present work, FTS performance of 0.5K5Mo10Fe/CNTs (DOE 2) and 2 K0.5Mo30Fe/CNTs (DOE 5) catalysts was assessed in terms of CO conversion, C5+ selectivity, and C2-C4 selectivity under industrially relevant FTS conditions (H2/CO = 1.0; GHSV = 2000 h−1; T = 280 ℃; P = 4.13 MPa). The C2-C4 selectivity increased in DOE 2 catalyst to 51.2% with respect to DOE 5 catalyst (2.9%). Meanwhile, the selectivity toward C5+ hydrocarbons decreased from 93.1% in DOE 5 to 8.3% for DOE 2 catalyst. DOE 5 catalyst was more hydrophobic than DOE 2 as confirmed by the water contact angle measurement, lowering CO2 selectivity and water gas shift rate. H2-TPR and CO2-TPD indicated an increase in reducibility and basicity of DOE 5 compared with DOE 2 catalyst, which enhanced iron carbide formation and chain growth probability. The highest amount of metallic Fe in DOE 5 calcined and spent catalysts obtained by XPS and XAS spectra also suggested higher degree of carburization in DOE 5. Additionally, COMSOL Multiphysics software package was employed to provide a 2-dimensional simulation of the FTS fixed-bed reactor. Simulation results were validated using the experimental data for FTS over DOE 2 and DOE 5 catalysts. Effects of temperature on CO conversion as well as distribution of H2, CO, and ethylene were discussed. The simulation illustrated the effects of the fixed-bed reactor wall on both velocity and temperature profiles.