Catalytic activity of metal oxides supported on graphene oxide in oxidative desulfurization and denitrogenation

In this work, the effect of different parameters on catalyst efficiency in the catalytic oxidative desulfurization (ODS) and denitrogenation (ODN) process is studied. A series of samples with different metal compounds, including Ni, Cu, Co, Co-Ni, Co-Cu, and Cu-Ni on a reduced graphene oxide (GO) were prepared by an impregnation method. The synthesized samples were carefully characterized by Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, and X-ray powder diffraction (XRD) techniques. The potential of this methodology was illustrated by the oxidation of 84.11% carbazole (CBZ) and 88.36% dibenzothiophene (DBT) in model fuel containing 500 ppmw sulfur and nitrogen. The effect of DBT and CBZ initial concentration and oxidant type on the oxidation process was investigated. The initial concentration of 250 ppmw for DBT and 100 ppmw for CBZ showed more efficiency than other initial concentrations (1,000, 750, 500, 250 ppmw) for DBT and (500, 400, 250, 100 ppmw) for CBZ, and NaClO as an oxidant showed higher performance than H2O2, formic acid, and oxygen. The results indicated that the Co-Cu/rGO catalyst shows higher activity than other prepared catalysts in the oxidation of DBT and CBZ. Moreover, the catalyst could be regenerated three times with no discernible decrease in its catalytic activity. Lastly, the catalytic oxidation of CBZ and DBT was the proposed reaction mechanism. The proposed mechanism on the ODN and ODS.image