Controlled separation of low temperature coal tar based on solvent extraction–column chromatography

• Separation of low temperature coal tar with silica-gel column chromatography was carried out.
• Coal tar was separated into eight fractions with a binary eluent of n-hexane and ethyl acetate.
• Pyrenol is the largest molecular weight phenols in low temperature coal tar.
• The solvent extraction–column chromatography (SECC) device has been designed.
• SECC could realize the separation of neutral oil, pitch and crude phenol from coal tar.

The heavy tar (H-tar) of low temperature coal tar was collected from a low temperature carbonization plant in Shanbei. H-tar was separated into eight fractions by silica-gel column chromatography (SGCC) with a binary eluent of n-hexane and ethyl acetate (EA). A series of alkanes (C14–C28), phenolic compounds and aromatic nitrogen species were fractionated from H-tar by SGCC and analyzed by gas chromatography–mass spectrometry (GC–MS). Most of the GC–MS detectable phenolic compounds are phenol, cresol, xylenol, C3–C4 alkyl phenols, indanols, naphthalenols, methyl naphthalenols, benzenediols, fluorenols, phenanthrols and pyrenol, among which cresol is the most abundant one and pyrenol is the largest molecular weight one. According to the change rule of phenolic compounds with the polarity of eluting solvents, the solvent extraction–column chromatography (SECC) device and crude phenol recovery processing have been designed and developed, which could realize the separation of neutral oil, pitch and crude phenol from low temperature coal tar.