Separation of phenolic compounds from coal tar is of both economic and technological interest in the processing of coal tar. In this work, three deep eutectic solvents (DES) of betaine-glycerol, betaine-DL-lactic acid, and betaine-levulinic acid were formed and used to extract phenolic compounds from model coal tar. The effects of extraction time, temperature, initial phenol content, and mass ratio of DES to phenol on extraction were investigated. Then, the extraction and formation mechanisms of extractant were studied by the experimental and simulation methods. In addition, the neutral oil entrainment and the recycling of DES were also investigated. The results showed that phenol could be efficiently extracted in short time by three DES and the temperature had little effect on phenol extraction. Fourier transform infrared spectroscopy and deformation charge density indicated that the three DES are formed with hydrogen bonding interaction, the hydrogen bond acceptor and hydrogen bond donor of DES can form hydrogen bonding with phenol, respectively, and then synergistic extract phenol from model oil. The betaine-glycerol (Bet-Gly) was determined to be the preferable solvent with the extraction efficiency of 94.6% and 5.2% neutral oil entrainment under optimal conditions. It is an advantageous extractant in the separation of phenolic compounds from coal tar.

Decoupled the activation process into gas–solid diffusion and reaction, and revealed an evolution mechanism of pore structure during the preparation of activated carbon.

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