Modeling and optimization of Fischer–Tropsch products hydrocracking

The hydrocracking behavior the product of a Fischer–Tropsch synthesis consisting of a C4–C30 mixture of paraffins and olefins on a platinum/amorphous silica–alumina catalyst has been analyzed and optimized. The influence of temperature on the selectiveness of the hydrocracking has been investigated. Time and temperature optimization was performed in order to obtain the best operating conditions for the enhancement of gasoline and diesel cuts. This work presents a mathematical model of the tubular reactor used in hydrocracking the heavy hydrocarbon fraction produced by the Fischer–Tropsch synthesis. The system was studied to optimize the operating conditions as to produce the highest amounts of diesel and/or gasoline. The hydrocarbon product distribution changes during hydrocracking were modeled considering a commercial bifunctional catalyst. The model was validated with data reported in the literature and has presented a satisfactory fitting to the experimental data with a confidence level of 95%. The production of specific cuts such as diesel and gasoline was optimized after the model has been validated. The results showed that lower temperatures (550 K) favor the cracking of heavy hydrocarbons chains into diesel and higher temperatures (650 K) favor a more effective cracking generating higher amounts of gasoline.