Washing oil is one of the important fractions in the process of coal tar distillation, by distilling the various fractions of coal tar, the distillate of 230~300℃ is mainly washing oil, which is the 6.5-10% of coal tar and is a complex mixture, which is rich in quinoline, quinoline, indole, α-methyl naphthalene, beta-methyl tea, biphenyl, two-methyl cha, acenaphthene, The precious organic chemical raw materials such as FMOC and Fmoc, 149 components were separated by capillary gas chromatography, and 60 kinds of nitrogen-containing salts were found in wash oil fractions by chromatography, mass spectrometry and spectral analysis, including quinoline and its homologous compounds, indole and its homologous products. The phenolic compounds of wash oil fractions accounted for about 50%, such as three methyl phenol, α-naphthol, beta-naphthol and so on. In addition, sulfide is also included in the wash oil fractions, such as thiophene, sulfur ether, sulfur impurity indanone, methyl sulfur indanone and organic disulfide.
Washing oil is used as absorbent for absorbing benzene hydrocarbon in gas, in the process of recycling, the molecular weight is increased, the viscosity is increased and the absorption rate is decreased. The study shows that the main factors that cause the above phenomenon are the presence of Acenaphthene, ℃ and Fmoc, which have boiling point above 270 in the washing oil.