Conditions for increasing the hydrodesulfurization of dibenzothiophene when co-feeding naphthalene, quinoline, and indole

Abstract

In this work, we report a statistically significant increase in the rates of direct C–S bond scission of dibenzothiophene when co-reactants such as naphthalene, quinoline, and indole are present during its hydrodesulfurization over a Ni–MoS2/γ-Al2O3 catalyst. The competitive adsorption of these compounds on the same active sites has usually been associated with inhibitory effects of sulfur elimination. However, we carried out statistically designed experiments at temperatures between 260 and 300 °C, concentrations of dibenzothiophene between 1.0 and 3.7 wt%, and concentrations of the co-reactants between 0.13 and 0.52 wt%, and observed that the kinetic constant of the direct desulfurization pathway can increase up to 200% when either naphthalene, indole, or quinoline is co-fed to the reaction system at 260 °C and 3.7 wt% of dibenzothiophene. Therefore, the classical paradigm that aromatics and nitrogen heterocycles always inhibit hydrodesulfurization needs reexamination.