High-throughput experimentation based kinetic modeling of selective hydrodesulfurization of gasoline model molecules catalyzed by CoMoS/Al2O3

The selective hydrodesulfurization (HDS) of fluidized catalytic cracking gasoline still represents a challenging step to minimize hydrogen overconsumption and maintain high octane numbers. To better understand the competition between desulfurization and hydrogenation reactions, a Langmuir-Hinshelwood kinetic model is established, based on high-throughput HDS experiments of a model feedstock of 3-methyl-thiophene (3MT) and 2,3-dimethyl-but-2-ene over CoMoS/Al2O3 catalysts. To reduce the model's dimensionality, some key enthalpies of adsorption are determined by density functional theory (DFT) calculations. The model takes into account 16 different reactions (hydrogenation, hydrodesulfurization, isomerization) for which rate constants and adsorption constants are determined to reproduce adequately the experimental product distribution. The model is finally used to predict and discuss the impact of operating conditions (partial pressures of key reactants and temperature) on the selectivity. The selectivity is most affected by the conversion levels of the reactants, with an optimum desulfurization selectivity at approximately 30-50% 3MT conversion. Operating at low temperature (170 degrees C) is also favorable for the HDS selectivity.

Automated summary

A Langmuir-Hinshelwood kinetic model is established to study the selective hydrodesulfurization (HDS) of fluidized catalytic cracking gasoline. The model takes into account 16 different reactions and adequately reproduces the experimental product distribution by determining rate constants and adsorption constants. The model is used to predict the impact of operating conditions on the selectivity, with an optimum desulfurization selectivity at approximately 30-50% 3MT conversion and low temperature (170 degrees C) being favorable for the HDS selectivity.