Desulfurization and denitrogenation of a synthesized gasoline utilizing an acidic deep eutectic solvent: Experimental and thermodynamic studies

Abstract

Deep eutectic solvents (DESs) exhibit outstanding properties for separating sulfur and nitrogen heteroatom compounds from fuels. This study investigates the application of a benign DES in desulfurization and denitrogenation of a synthetic gasoline, made up of hexane, heptane and isooctane. The utilized acidic DES was comprised of methyltriphenylphosphonium bromide and para-toluensolfonic acid, molar ratio of 3:7. It was characterized by IR analysis as well as the melting point, density, and viscosity properties. The heteroatom compounds were thiophene and pyridine as the S and N representative solutes. The liquid–liquid equilibrium of each system was properly studied at different temperatures of 298.2, 308.2, and 318.2 K. The important parameters of the solute distribution coefficient and the separation factor were found within the high levels of (0.2188–1.2082) and (11.74–662.15) for thiophene, and (6.7176–15.9950) and (8061.37–11066.20) for pyridine; revealing the high potential of the DES compared to other solvents. The NRTL and UNIQUAC thermodynamic models were employed to replicate the tie-lines and to ascertain the interaction parameters. Accordingly, an approach based on group contribution calculations was used to determine the DES thermodynamic parameters. This study highlights the importance of selecting new generation of solvents in purifying fuels.