PRODUCT DISTRIBUTION OF FISCHER-TROPSCH SYNTHESIS IN A SLURRY BUBBLE COLUMN REACTOR BASED ON LANGMUIR-FREUNDLICH ISOTHERM

Abstract

A comprehensive kinetic model for Fischer-Tropsch synthesis was developed. The dual mechanism theory for product distribution in Fischer-Tropsch synthesis developed by Fernandes was used in this study with a newly developed reaction rate equation. That is, the Langmuir-Freundlich isotherm for Fischer-Tropsch (FT) synthesis was employed, a modification of the commonly used Langmuir isotherm. Since the Langmuir-Freundlich isotherm can predict the adsorption of gases at a solid absorbent more accurately than the Langmuir isotherm, the new Langmuir-Freundlich kinetic model was developed for FT synthesis. The new kinetic model was used for product distribution, and the parameters of the equations were obtained from optimization. A product distribution prediction resulted from the dual mechanism theory and the newly developed kinetic model shows very good agreement with the experimental data. The average absolute deviation (AAD%) in paraffin and olefin prediction is about 13.96% and 11.41% respectively, for the considered mechanism using the Raje and Davis kinetic model. Two kinetic models have been derived in this study. For the reaction rate equations based on the Langmuir-Hinshelwood isotherm instead of the Raje and Davis kinetic model, AAD% decreased to 12.27% for paraffin and 11.17% for olefin, respectively. The newly developed kinetic model, Langmuir-Freundlich, improves the results of product distribution with the value of 9.33% and 9.19% for prediction of paraffin and olefin, respectively.