Extractive Deep Desulfurization of Liquid Fuels Using Lewis-Based Ionic Liquids

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of liquid fuels because of the limitation of traditional hydrodesulfurization method. In present work, eleven Lewis acid ionic liquids were synthesized and employed as promising extractants for deep desulfurization of the liquid fuel containing dibenzothiophene (DBT) to test the desulfurization efficiency. [Bmim]Cl/FeCl3 was the most promising ionic liquid and performed the best among studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the model liquid fuel in the single-stage extraction process with the maximum desulfurization efficiency of 75.6%. It was also found that [Bmim]Cl/FeCl3 may be reused without regeneration with considerable extraction efficiency of 47.3%. Huge saving on energy can be achieved if we make use of this ionic liquids behavior in process design, instead of regenerating ionic liquids after every time of extraction. 1. Introduction Due to environmental awareness and economic competition, fuel oil standards are more stringent. Sulfur present in transportation fuel leads to sulfur oxide (SOx) emissions into the atmosphere and causes many environmental problems. It also inhibits the performance of vehicles pollution control equipment. Hence, much recent interest in the deep desulfurization [1, 2] of light oil feedstock is directed. Inconsiderable attention has been given to deep desulfurization of gasoline and liquid fuels due to strict environment regulations on the sulfur limit of fuels [3]. The maximum sulfur content will be limited to 10–50？ppm in 2016, as compared to today’s permitted value of 500？ppm in most western countries [4]. In India, the present norms were decided by the Central Pollution Control Board (CPCB); the current value of total sulfur in liquid fuels is limited to 350？ppm which has to be lowered down into possible extent [5]. As a result the deep desulfurization of liquid fuels has fascinated increased attentunity worldwide. In the petroleum industry, low sulfur fuels are often obtained from hydrocracking processes [6]. In petroleum and hydrocarbon industries, various solvents such as ethers, amines, alcohols, and other volatile organic compounds have been used for the processes like extraction, absorption, azeotropic distillation, and so forth [7]. These solvents have their own limitations in terms of environmental issue, recycle ability, and so forth, which can be overcome by the use of ionic liquids as green solvent due to