Highly efficient oxidative desulfurization catalyzed by copper-based materials using hydrogen peroxide as oxidant

Abstract

The mesoporous silica SBA-15 and MOR-SBA-15 supported catalysts were successfully fabricated via a facile impregnation approach. The characterization of the synthesized materials was carried out by using X-ray diffraction (XRD), Scanning electron microscopy (SEM) with Energy-dispersive spectroscopy (EDS), ICP-OES (Inductively coupled plasma - optical emission spectrometry), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Ammonia temperature-programmed desorption (NH3-TPD), and N2 adsorption–desorption techniques. The catalytic activity of synthesized catalysts is investigated for the oxidative desulfurization of model fuel containing benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) with hydrogen peroxide as oxidant and acetonitrile as extractant. Meanwhile, Factors affecting oxidative desulfurization, including reaction temperature, reaction time, the dosage of catalyst, and the molar ratio of H2O2 to sulfur (O/S), are evaluated. The results indicated that the Cu/MOR-SBA-15 catalyst has excellent catalytic activity in the ODS process, with a removal performance of up to 99.9% for DBT under optimum reaction conditions. The reactivity of various sulfur compounds decreased in the following order: DBT > 4,6- DMDBT > BT. Furthermore, the Cu/MOR-SBA-15 catalyst demonstrated good reusability five times without considerable activity reduction. Also, the kinetic calculations indicated that the oxidation reaction on the sulfur compound containing DBT follows a pseudo-first-order kinetic model. The apparent activation energy for Cu/SBA-15 and Cu/MOR-SBA-15 catalysts was 20.93 and 43.29 kJ/mol, respectively.