Selective oxidation of sulfurs and oxidation desulfurization of model oil by 12-tungstophosphoric acid on cobalt-ferrite nanoparticles as magnetically recoverable catalyst

Abstract

Silica-coated CoFe2O4 nanoparticles were prepared and used as a support for the immobilization of 12-tungstophosphoric acid, to produce a new magnetically separable catalyst. This catalyst was characterized using X-ray diffraction, wavelength-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, laser particle size analysis, and vibrating sample magnetometry. The catalyst showed high activity in the selective oxidation of thioethers and thiophenes to the corresponding sulfones under mild conditions. The catalytic activity of the nanocatalyst in the oxidative desulfurization of model oil was investigated. The effect of nitrogen-containing compounds on sulfur removal from the model oil was also evaluated. The catalyst showed high activity in the oxidative desulfurization of diesel. The catalyst can be readily isolated from the oxidation system using an external magnet and no obvious loss of activity was observed when the catalyst was reused in four consecutive runs.