Extraction of Aromatics from Hydrocarbon Fuels Using N-Alkyl Piperazinium-Based Ionic Liquids

A total of 10 new N-alkyl piperazinium-based ionic liquids (ILs) have been prepared, and they are used as extractants for removing aromatics from three kinds of hydrocarbon fuels. A total of 3 ILs, N-methyl piperazinium lactate (MPL), N-ethyl piperazinium lactate (EPL), and N-ethyl piperazinium propionate (EPP), in the liquid state at room temperature are used directly for extraction, while the other 7 ILs in the solid state at room temperature are used with methanol as the co-solvent. Effects on the extraction efficiency of the temperature and the amounts of IL and co-solvent are investigated. The results indicate that the amounts of IL and co-solvent play very important roles in the extraction process and the efficiency is greatly influenced by the cation and anion structures in the N-alkyl piperazinium-based ILs. In comparison to 1,1,3,3-tetramethylguanidinium lactate (TMGL), the extraction capability order is EPP > EPL > MPL > TMGL. The ILs with aromatic anions are found to have better extraction capability than the others. Furthermore, recycling of ILs reflects that these ILs can be recovered simply by vacuum distillation without a significant decrease in the activity of dearomatization.