Designing Ionic Liquids with Dual Lewis Basic Sites to Efficiently Separate Phenolic Compounds from Low-Temperature Coal Tar

Abstract

Although separation of phenolic compounds from coal tar has a good practical application value in industry, the traditional separation method can result in serious environmental problems. In the present work, three ionic liquids (ILs) with dual Lewis basic sites were designed and synthesized by neutralizating 1,1,3,3-tetramethylguanidine (TMG) and corresponding acids (L-proline, acetate acid, and tetrafluoroboric acid), which were employed to separate phenolic compounds from the model oil and coal tar. The basicity of TMG-based ILs were characterized by a probe molecule through 1H NMR and quantum chemical calculations. Moreover, the influence of factors on the separation efficiency, such as stirring time, extraction temperature, and the ratio of ILs to model oil, was investigated in detail. The results showed that [TMG]­[BF4] showed the best extraction efficiency of 98.2%, at a extraction temperature of 30 °C, stirring time of 35 min, and extraction ratio of 1.1 g/4 mL. After being separated, these ILs were recovered through back extraction. Furthermore, the separation mechanism was determined by analyzing the hydrogen bond and chemical bond for ILs and phenolic compounds via UV–vis, FT-IR, and quantum chemical calculations. Thus, TMG-based ILs can be effective in separating phenolic compounds from coal tar and as an alternative extractant in the future.

Synthesis of alcohol ester 12 in 1, 8‐diazabicyclo [5.4.0] undec‐7‐ene (DBU)‐based Self‐separation catalytic system

“…Figure shows the FT‐IR spectrum of DBILs in the range 400–4000 cm −1 .From Figure , there was an obvious peak around 1628 cm −1 in the spectrum of all DBILs, due to typical characteristic peak of C=N species in DBU ring. The peak in the range of 2857–2292 cm −1 was ascribed to the stretching vibration of saturated C‐H in alkyl chains . The peak in the range of 2853–2930 cm −1 was related to the stretching vibration of C‐H in methylene.…”

“…The peak in the range of 2857-2292 cm −1 was ascribed to the SCHEME 1 Synthesis process and molecular structure of [BDBU]Br SCHEME 2 Synthesis process and molecular structure of stretching vibration of saturated C-H in alkyl chains. [10] The peak in the range of 2853-2930 cm −1 was related to the stretching vibration of C-H in methylene. The broad peak absorption band at ca.…”

Separation of m-Cresol from Coal Tar Model Oil Using Propylamine-Based Ionic Liquids: Extraction and Interaction Mechanism Exploration

“…As shown in Figure 7 , the peak at 3497.90 cm –1 is ascribed to −OH in pure m -cresol, whereas the peaks at 3451.39 and 3445.56 cm –1 are ascribed to −NH 3 + in the pure ILs [PA][FA] and [PA][Ac], respectively. 6 When the complexes formed, the characterization peak shifted to 3438.51 cm –1 for complex 1 ([PA][FA] + m -cresol) and shifted to 3438.32 cm –1 for complex 2 ([PA][Ac] + m -cresol), which indicated that hydrogen bonds were formed between m -cresol and the ILs.…”

“…In addition, more results of separating phenolic compounds using ILs as extractants were reported in the literature. 6 , 27 − 29 To our knowledge, m -cresol has the highest content (13.41 wt %) in phenol oil from low-temperature coal tar, 30 but fewer literature studies have reported the separation of m -cresol as a representative phenolic compound from model oil since phenol or p -cresol is usually selected as the typical phenolic compound. 6 , 21 , 31 − 33 Hence, it is meaningful to explore the separation of m -cresol from LTCT by means of ionic liquids.…”

Metal Recovery from Spent Samarium–Cobalt Magnets Using a Trichloride Ionic Liquid

“…They are being applied in the fields of synthesis, separations, catalysis and electrochemistry. 12−16 ILs have also shown potential for safely storing halogens by forming trihalide or polyhalide anions, such as [Cl 3 ] − , [Br 3 ] − , [I 3 ] − or [ClBr 2 ] − . 17−20 Recently, trichloride ILs have been synthesized and used for dissolution of various metals and alloys at mild conditions.…”