An Effective Approach for Separating Carbazole and Its Derivates from Coal-Tar-Derived Anthracene Oil Using Ionic Liquids

Abstract

Carbazole and its derivates are important value-added chemicals (VACs) in anthracene oil (AO), which is one of the coal tar fractions. In this work, imidazolium-based ionic liquids (ILs) were used as novel extractants to extract carbazole from AO and the effects of anionic substituents and cationic structures on carbazole extraction were investigated. The results show that the recovery and purity of carbazole reached up to 96.2 and 98.0%, respectively, by extracting AO-related model oil with the ILs. The hydrogen-bond force existing between 1-butyl-3-methylimidazolium dicyanamide (IL a ) and carbazole was revealed by Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance and further confirmed by density functional theory simulation. π−π interactions and hydrogen bonds formed between ILs and carbazole play crucial roles in effectively separating carbazole from AO. Simultaneously, the stability test shows that IL a is easily recyclable and highly stable for carbazole separation. Moreover, the recovery and purity of carbazole extracted from AO are 66.6 and 90.2%, respectively, with IL a as the extractant by flash chromatography. This study provides a green and effective approach for separating VACs from coal tar and its derived fractions.

Separation of phenolic compounds from oil mixtures by betaine‐based deep eutectic solvents

“…FT‐IR is considered to reflect the vibration state changes of chemical bonds 31 and was used to explore the mechanisms in this work. The FT‐IR spectra of three DES and their mixtures with phenol are shown in Figures 6–9.…”

Overview: Effective Separation of Oxygen-, Nitrogen-, and Sulfur-Containing Aromatics in High-Temperature Coal Tar by Ionic Liquids and Deep Eutectic Solvents: Experimental and Computational

“…Additionally, CC/trifluoroacetic acid (TFA) was screened to separate phenol and pyridine with extraction yields of 93.47% and 90.97%, respectively, at a DES/oil volume ratio of 1:3 and 35 °C for 80 min from a model coal tar using toluene as neutral oil . Although hydrogen bonds dominate DESs to selectively extract NCAs, − the acidic DESs used will inevitably produce acid–base interaction with pyridine, which can effectively facilitate the separation of BNCAs from HTCT. Interestingly, pyrrole can also be isolated from toluene through 1-ethyl-3-methylimidazolium phenolate by hydrogen bond between a H atom in pyrrole and an O atom in phenolate anion …”

Intermolecular Interaction and Extraction Explorations for Separation of High-Boiling Neutral Nitrogen Compounds Using Biodegradable Ionic Liquids

“…Because of the complex composition of anthracene and wash oil, , it is difficult to test the extraction ability of the biodegradable TMG-based ILs with real anthracene and wash oil. From the literature, − carbazole and indole were selected as the typical HBNNC, and n -heptane and toluene were used to prepare a solvent. Hence, in this work, for preparation of the representative oil, 1.50 g of carbazole and 5.00 g of indole were dissolved in 100 g of the solvent, which was prepared using n -heptane and toluene with a mass ratio of 1:1 .…”