Impact of support on the catalytic behavior of Mo/γ-Al2O3 and Mo/MgO catalysts on the desulfurization reaction

• DBT desulfurization reaction was studied on Mo/MgO and Mo/γ-Al2O3 catalysts.
• Two catalysts respond differently to the variations of the reaction parameters.
• The temperature causes a change in reaction mechanism on Mo/MgO catalyst.
• Temperature has no marked influence on prevailing reaction mechanism on Mo/γ-Al2O3.
• Some hydrogen containing functional groups on catalysts influence the reaction.

This study uses the Taguchi method to evaluate the impact of support on the catalytic behavior of Mo/MgO and Mo/γ-Al2O3 catalysts through the parametric effects on the kinetics of dibenzothiophene desulfurization reaction. The parameters studied were contact time, temperature, activation temperature, reaction gas type, sulfur concentration, pressure, and nitrogen concentration. Some discrepancies existed in the order of significance of the reaction parameters between the two catalysts. The compensation phenomena revealed a change in the reaction mechanism with temperature for Mo/MgO catalyst that approximates that of Mo/γ-Al2O3 catalyst at higher temperatures. Transition state theory showed that for the Mo/MgO catalyst, the tight activation transition state mode is replaced with a loose mode at higher temperatures, whereas for the Mo/γ-Al2O3catalyst, the loose mode prevails across the entire temperature range studied. Furthermore, some temperature-dependent concentrations of SH and OH functional groups were detected at the catalyst surface, profoundly influencing the adsorption of the reactants and the inhibition effect of pyridine.

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