The Possibility of Using Metal-Based Ionic Liquids for Desulfurization of Diesel Fuel

Since the emission of sulphur oxide (SO_x) especially from automobile exhaust has been increasing rigorously, the removal of sulphur compounds from fuel oil has become a universal subject. Ionic liquids have been studied as the alternative solvent for desulfurization process with several reports on their reasonable success in removing sulphur compounds from model oil. Nevertheless, the ability of ionic liquids to remove sulphur compounds from real diesel fuel is very challenging due to multi-component nature of diesel fuel. Therefore, this work is carried out to study the desulfurization of real diesel fuel using several metal based ionic liquid [C₄mim][MCl_n] with M = Fe³⁺, Co²⁺, Cu²⁺, and Zn²⁺. The ionic liquids solution are prepared by mixing an equimolar amount of [C₄mim]Cl with corresponding MCl₃ salt, which are then characterized using H-NMR and Raman spectroscopies. The ionic liquid is added to model oil at equal mass before being added to diesel fuel. Total Sulphur Analyser is used to determine the sulphur concentration after mixture is at least 6 hours settled. It is observed that these ionic liquids have high ability to remove sulphur from model oil, however unexpectedly low sulphur removal from real diesel.