Phenolic compounds

such as phenol

cresol and dimethyl phenol

are important substances and intermediates in industry. They are mainly derived from coal liquefaction oil and coal tar. At present

the traditional method to separate phenols from oil is aqueous alkali solution extraction

which consumes large amounts of NaOH and H2SO4 and produces a huge amount of phenol-contained waste water. This method results in high cost of separation and pollution controlling

which limits the recovery and application of phenolic compounds from coal liquefaction oil and coal tar. Therefore

it is necessary to develop a new method to use nonaqueous solution as extractant and to avoid using alkali aqueous solution. In this work

it is found that imidazolium based ionic liquids (ILs) are efficient media to extract phenols from toluene as simulated oil. [Bmim]Cl is better among different structure imidazolium based ILs

resulting from strong molecular interaction between IL and phenol. A small amount of [Bmim]Cl

equimolar to that of phenol in toluene

was enough to extract phenol from toluene with high extraction efficiency. The extraction was not sensitive to temperature and could be performed at room temperature. The extracted phenol in ILs could be recovered by vacuum evaporation at high temperatures

and the regenerated ILs could be reused for several cycles with almost same phenol extraction efficiency. [Bmim]Cl was also used to extract real coal liquefaction oil distillate with high extraction efficiency up to 92.5%

which has a potential application.