Heat treatment of anthracene oil under pressure

Abstract

The heat treatment of the anthracene fraction of coal tar under pressure is investigated. In the production of synthetic pitch, the temperature is varied in the range 400–480°C. The duration of the process is 5 h, and the pressure is 3–5 MPa. After treatment at temperatures below 480°C, the pitch produced lacks the quinoline-insoluble fraction. Chemical analysis shows that increasing the treatment temperature results in consumption of cata-condensed aromatic hydrocarbons, with simultaneous accumulation of peri-condensed aromatic hydrocarbons. NMR and IR spectroscopy indicates simultaneous increase in the aromatic index and the degree of condensation of samples with increase in the treatment temperature, as the result of dealkylation and condensation. Optical analysis shows clearly expressed mesogenic properties of the synthetic pitch. Pitch produced by low-temperature synthesis forms needle coke, with a greater anisotropy and greater real density than coke obtained from pitch produced by high-temperature synthesis. With increase in pressure in the course of coking, the anisotropy and the real density decline for low-temperature pitch, but increase for high-temperature pitch.