Deep eutectic solvents based highly efficient extractive desulfurization of fuels - Eco-friendly approach

The developed process is based on alternative, green and cheap solvents for efficient desulfurization of fuels. Several deep eutectic solvents (DESs) were successfully synthesized and studied as extraction solvents for desulfurization of model fuel containing thiophene (T), benzothiophene (BT) and dibenzothiophene (DBT). The most important extraction parameters (i.e. kind of DES, DES: fuel volume ratio, hydrogen bond acceptor: hydrogen bond donor mole ratio, time of extraction and temperature) were optimized using central composite design model. Furthermore, the mutual solubility of DES and model fuel and influence of multistage extraction, reusability, regeneration of DES and content of aromatic groups in fuel are discussed followed by explanation of desulfurization mechanism, by means of density functional theory (DFT) as well as FT-IR analysis. The studies revealed high desulfurization effectiveness resulting in 91.5%, 95.4% and 99.2% removal of T, BT and DBT respectively in a single stage extraction. A three stage desulfurization provide >99.99% removal of T, BT and DBT. The research on the desulfurization mechanism revealed that pi-pi- interaction is the main driving force for desulfurization process based on DES. (C) 2019 The Authors. Published by Elsevier B.V.