Simultaneous dearomatization, desulfurization, and denitrogenation of diesel fuels using acidic deep eutectic solvents as extractive agents: A parametric study

Based on the literature, deep eutectic solvents (DESs) have been proven to be promising candidates for the separation of aromatics or heteroaromatics (“sulfur-/nitrogen- containing aromatics”) from fuels. However, most studies investigated the separation of a single fuel impurity (aromatics or heteroaromatics) from n-alkanes. Thus, to realistically represent a process that simulates the treatment of both types of aromatics, this work investigated the application of DESs in simultaneous dearomatization, desulfurization, and denitrogenation of fuels, particularly “diesel” using an arbitrary fuel model consisting of {5 wt% toluene + 5 wt% thiophene + 5 wt% pyridine + 5 wt% pyrrole + 80 wt% n-decane}. The selected DES was comprised of tetrapropylammonium bromide and acetic acid at a 1:4 M ratio. The DES performance was evaluated based on single-stage liquid–liquid extraction, the Liquid-Liquid Equilibrium (LLE) data of each impurity, multi-stage, and multi-cycle extraction of the diesel model. Furthermore, the influence of initial concentration and mixing effects of impurities were also studied. The results showed that complete removal of pyrrole and pyridine (“≈100%”) can be achieved in 2 stages only, while extraction efficiencies of 68% and 89% for toluene and thiophene, respectively, were achieved after the 5th stage. Based on the obtained results, it was concluded that acidic DESs could be considered as potential solvents for the simultaneous dearomatization, desulfurization, and denitrogenation of diesel fuels.