Extractive desulfurization of gasoline using binary solvent of bronsted-based ionic liquids and non-volatile organic compound

Due to the rising demands of cleaner fuels (free from sulfur), most of the oil industries are implementing the process of the desulfurization. In present work, the extractive desulfurization (EDS) efficiency of binary solvents composed as mixtures of bronsted acidic ILs ([Hnmp][HSO4] and [Hnmp][H2PO4]) and nonvolatile organic solvent known as dimethylformamide (DMF), is investigated for the model fuel oil (containing thiophene as S-compounds). The main advantages of using binary solvents are; low viscosity of extractant and reduced cost of the process. Effect of key operating parameters such as temperature, time, multiple steps, initial S-content in oil and oil:binary solvent (w/w) ratio on the S-removal efficiency is examined. Based on the obtained results, optimal 40 °C and 45 min are chosen as operating temperature and extraction time, respectively. Almost 95% of S-removal (decrease from 500 to 22 ppm and 28 ppm) is obtained through five steps extraction for both binary solvents, also these exhibited remarkable extraction performances for different initial S-content of fuel oil. The recyclability and reusability of solvents are investigated, where it is observed that binary solvent has reasonable effectiveness when reused for four times. The solvents can also be regenerated without undergoing any change in the actual structure of ILs. This study shows that EDS based on the binary solvents can be a suitable option to produce the cleaner fuel oils.