Extraction of Aromatic Hydrocarbons from Aromatic/Aliphatic Mixtures Using Chloroaluminate Room-Temperature Ionic Liquids as Extractants

Abstract

The extraction of aromatic hydrocarbons from aromatic/aliphatic mixtures was investigated using chloroaluminate ionic liquids as extractants. Three types of chloroaluminate ionic liquids, i.e., 1-butyl-3-methylimidazolium chloride−aluminum chloride (BMIC/AlCl3), trimethylamine hydrochloride− aluminum chloride (Me3NHCl/AlCl3), and triethylamine hydrochloride−aluminum chloride (Et3NHCl/AlCl3), were prepared and used to extract aromatic hydrocarbons. Chloroaluminate ionic liquids have strong aromatic hydrocarbon solvent capacities, small solvent capacities for n-heptane, and good extractive performances. BMIC−2.0AlCl3 exhibits better extractive performance than Me3NHCl−2.0AlCl3 and Et3NHCl−2.0AlCl3. Both the benzene distribution coefficient and aromatic/n-heptane selectivity increase with an increasing ratio of AlCl3/organic salt (Et3NHCl) in ionic liquids. The steric effect of substituent groups on the benzene ring lowers the aromatic extractive performance. The π complextion between aromatic molecules with...