The dissolution of lignite in ionic liquids

Abstract

A Xianfeng lignite (XL) was dissolved in a series of ionic liquids (ILs) at 200 °C. It was found that the anions of the imidazolium-based ILs are one significant factor to affect the extraction yield of XL and the chemical characteristics of extracts obtained from ILs extraction. The dissolution of ILs to lignite is related to the destructive ability of ILs to hydrogen bonds widely existing in lignite. The analyses of residues by in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) indicate that the nature of ILs has a significant effect on the disruption of hydrogen bonds existing in lignite. The effective extraction of lignite results from the fracture of the hydrogen bonding network in lignite during lignite dissolving in ILs. Ionic liquid 1-butyl-3-methyl-imidazolium chloride [Bmim]Cl can dissociate significantly almost all of hydrogen bonds existing in lignite.