Pyrolysis of Coal Tar. (II). Functional Group Analysis for Heavy Fraction of Coal Tar.

Abstract

The hexane insoluble-chloroform soluble (HI-CFS) fractions which were obtained by the secondary pyrolysis of coal tar in a flow reactor at 700-900°C for 5-22 s were characterized by estimating the probable structure of the HI-CFS fraction and the concentrations of the functional groups on the basis of 1H-NMR and elemental analysis data using a computer. The structural pat-tern of coal tar was divided into the functional groups, i, e., condensed aromatics with one-ring to eight-ring, alkyl chain, methylene bridge, and hydroxyl and hydroaromatic group.After secon-dary pyrolysis of coal tar, the distribution of condensed aromatics which consisted in molecules in HI-CFS shifted to the big ring number side with an elapse of time and a rise in reaction temperature. However, the distribution of condensed aromatics in HI-CFS fraction of raw coal tar was from two-ring to six-ring, those of pyrolyzed coal tar changed from three-ring to seven-ring at 800 and 900°C. The maximum in the distribution of condensed aromatics changed from four-ring to five-ring at 800 and 900°C. Further, the changes in the concentrations of functional groups such as aliphatic chains, hydroxyl group and methylene bridge showed that these functional groups de-composed at initial stage of secondary pyrolysis.