Optimization of Processing Parameters and Macrokinetics for Hydrodesulfurization of Coal Tar

In this work, a systematic study has been conducted to optimize the process conditions and to evaluate kinetic parameters for hydrodesulfurization of coal tar. Experiments were performed in a trickle-bed hydrogenation unit at the temperatures, hydrogen pressures, and liquid hourly space velocities of 643–683 K, 9.6–13.6 MPa, and 0.3–0.5 h^–1, respectively. Hydrogen to oil volume ratio was maintained constant at 1,200 L _N /L in all cases. Optimization for hydrodesulfurization process conditions was investigated using the Box-Behnken experimental design by response surface methodology. A mathematical model that can be used for predicting sulfur content in products after hydrotreating was statistically developed and proven with analysis of variance. Kinetic studies for hydrodesulfurization reactions were studied using a power law model. The power law model showed that hydrodesulfurization of coal tar followed second-order kinetics and the activation energy was 42.15 kJ/mol, which is lower than other petroleum fractions.