Intensification of oxidative-extractive desulfurization of real diesel fuel using ionic liquid in a miniaturized fluidic contactor under ultrasound irradiation

This study investigates the ultrasound-assisted oxidative-extractive desulfurization of real diesel fuel using N-Octyl-3-methylpyridinium tetrafluoroborate as an ionic liquid in a microchannel contactor. Initially, oxidation of diesel fuel in a batch setup achieved 27 % sulfur removal, reducing the sulfur content from 1690 to 1234 ppmw. Subsequent extractive desulfurization in the microchannel at a solvent-to-fuel volume ratio of 1:1 resulted in a maximum sulfur removal of 82.2 %. Increasing the residence time from 12 to 301 s enhanced the sulfur removal from 52.3 % to 82.2 % under silent conditions, while ultrasound irradiation further improved the sulfur removal to 89.3 %. The application of four-stage extraction process led to a cumulative sulfur removal of 94.9 %, reducing the sulfur content of treated fuel to 86 ppmw. Regenerated ionic liquid showed negligible performance loss over two cycles. These results demonstrate the effectiveness of integrating ionic liquids, ultrasound, and microchannel contactors for high-efficiency desulfurization to meet stringent environmental regulations.