Illinois No.6 and Miike coals were extracted with carbon disulfide-N-methyl-2-pyrrolidinone mixed solvent (CS2-NMP), respectively. The extract was separated into four fractions such as WS (water-acetone soluble fraction), AS (acetone soluble fraction), PS (pyridine soluble fraction), and MS (CS2-NMP soluble fraction) along with residue. Main three samples such as AS, PS, and the residue and their acetylated samples along with original coals and their acetylated ones were analyzed by Curie-point pyrolysis and gas chromatography-mass spectrometry. The acetylation of the samples seems to result in the reduction of coke amount accompanied with pyrolysis. The plot of coke amount of each fraction versus the number of its OH group indicated that coke amounts decrease, in a way to depend upon coal employed, as the number of OH groups decrease. This suggests that the coke formation in the pyrolysis of extracts and residue of both coals has some relation with OH group content.
The pyrograms of AS, PS, and the residue were very similar in the same coal; that of Illinois No.6 coal was rich in phenol derivatives while that of Miike coal was rich in saturate compounds. In the total ion chromatograms of the pyrolysate from AS fraction of both coals, more than 130 compounds were identified. As for isomers in the total ion chromatograms of AS fractions from both coals, six ones for C3-benzene and eight ones for C4-benzene were found, while seven isomers for C2-phenol and eight isomers for C3-phenol. Taking into consideration the overlapping of some isomer peaks on gas chromatogram, all isomers of C3-benzene (8) and C2-phenol (9) seem to be contained in the pyrolysates. Relatively small numbers of isomers found as C4-benzene and C3-phenol seem to be limited to the heat history of the coals during their coalification.
