Use of Type I DES for Deep Desulfurization of Diesel: Insights from Molecular Dynamics Simulations

With ever-increasing environmental sulfur regulations, the development of alternative desulfurisation techniques, beyonds the industrially practiced hydrodesulfurisation is essential. The current legislative requirements of sulfur content in transportation fuels is less than 10 ppm. Among the recent desulfurisation techniques, extractive desulfurisation is highly promising.The use of Deep Eutectic Solvents (DES) in the extraction of sulfur content is a new and effective alternative to the previously used solvents. Amongst several DESs, type I DES have been shown effective in almost 100% removal of refractory sulfur compounds such as: thiophenes, benzothiophenes and dibenzothiophens. In this work tetrabutylammonium chloride (TBAC), PEG, in combination with FeCl₃, at a ratio of 4:1:0.05 is investigated as a DES, while dodecane, and benzothiophene with dibenzothiophene were used to simulate the diesel and sulfur-based compounds, respectively. Molecular dynamics simulation is used in order to investigate the interactions between DESs, diesel, and sulfur content at different temperatures and loadings. In addition, the simulations are also performed without PEG, in order to observe the role of the polymer in the process. The results show strong interactions between DESs and sulfur based compounds in comparison with the model diesel. Moreover it is also observed that interactions are stronger with the use of PEG, however further investigation is being carried on. In summary, this study sheds light on designing efficient solvents for desulfurisation based on molecular dynamics simulation.