Photooxidative-Extractive Deep Desulfurization of Diesel using Cu-Fe/TiO2 and Eutectic Ionic Liquid

An efficient photooxidative–extractive system for deep desulfurization of model fuel and actual diesel
fuel was explored. A series of bimetallic Cu–Fe/TiO2 photocatalysts was synthesized using sol–gel
hydrothermal method and characterized using thermogravimetric analysis (TGA), X-ray diffraction
(XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray analysis
(EDX), high resolution transmission electron microscopy (HRTEM) and diffuse reflectance UV–visible
spectroscopy (DR-UV–Vis). The photocatalysts were evaluated for photooxidative–extractive deep desulfurization
of model oil (100, 300 and 500 ppm dibenzothiophene in dodecane) and actual diesel fuel.
2.0 wt% Cu–Fe/TiO2 photocatalyst was identified as the most efficient photocatalyst for the conversion
of sulfur species under mild conditions in the presence of hydrogen peroxide (H2O2:S molar ratio of 4)
as oxidant and eutectic based ionic liquid as extractant. The sulfur conversion in both model oil and
actual diesel fuel reached 100%. The removal of sulfur species from both model oil and actual diesel fuel
was done by two times extraction with a removal of 97.06% and 78.93%, respectively in the first run and
2.94% and 21.07%, respectively in the second run. The photocatalyst was able to be recycled for six cycles
with an average performance of 99.75%.