Ultra-fast and highly efficient catalytic oxidative desulfurization of dibenzothiophene at ambient temperature over low Mn loaded Co-Mo/Al2O3 and Ni-Mo/Al2O3 catalysts using NaClO as oxidant

Abstract

This study reports the ultra-fast and highly efficient oxidative desulfurization (ODS) of dibenzothiophene (DBT) at room temperature over low Mn (0.5 wt%) incorporated Co-Mo/Al2O3 and Ni-Mo/Al2O3 catalysts using NaClO as oxidant. The effect of disparate operating parameters i.e. mode of catalyst preparation, DBT initial concentration, reaction time, temperature, catalyst and oxidant dose, oxidant type and reaction pH on oxidation process was investigated. Results revealed that remarkably high and ultra-fast A DBT conversion of 100% was achieved within 5 min utilizing 15 mL sample of 2000 ppm (347 ppm sulfur), 0.1 mL of 0.138 M NaClO (O/S-6.6 mol/mol), 0.1 g Mn-Co-Mo/Al2O3 catalyst at pH 12, and 25 °C reaction temperature. A reaction mechanism for the highly efficient ODS activity of Mn promoted catalysts accredited to the synergistic effect of Mn active phase and high oxidizing power of NaClO was proposed. An overall ODS catalytic activity order of: Mn–Co–Mo/Al2O3 > Mn–Ni–Mo/Al2O3 > Co–Mo/Al2O3 > Ni-Mo/Al2O3 > Mo/Al2O3 was observed. Discernment of the surface morphology and textural properties of fresh and spent catalysts were characterized using Scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive X-Ray (EDX), and BET surface area analysis which helped in evaluating the catalytic activity results. Due to ultra-fast and highly efficacious nature, simple and safe mechanization, cost effectiveness, and operation at ambient reaction conditions, this study can be envisaged as an effective approach for the ODS of fuel oils on industrial level.