Structural Charactrization of Oils from Coal Liquids by HPLC-MS Spectroscopy
1983 Volume 62 Issue 2 Pages 106-114
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1983 Volume 62 Issue 2 Pages 106-114
n-Hexane soluble oils from hydrogenolysis of three different coals (Tenppoku coal (C: 72. 7‰); Miike coal (C: 84. 5‰) and Illinois No.6 coal (78. 7‰)) were investigated aimed to the characterization of chemical structure and its relation to the coal rank. These oils were separated into compound classes designated by Fr-P, -M, -D and-T which consisted mainly of paraffin, monoaromatics, diaromatics and tri-and tetraaromatics, respectively. The separation was carried out by means of high pressure liquid chromatography (HPLC) using a μ-Bondapak-NH2 packed column.
Fr-P was analysed by GC-MS. The ionization voltage of the MS was of 20 eV. Characteristic patterns of total ion chromatogram indicating existence of n-paraffine from C14 to C28 or C30, were observed for the three coals. Mass spectra of compounds from individual chromatogram peaks had also specific fragmentation profiles of n-paraffines.
To the aromatic fractions, Fr-M, -D and-T, low voltage mass spectra were measured and the chemical structure was elucidated as compound types as indicated by the Z values and their corresponding molecular weight distributions. From these results, the influence of the degree of coal rank in the chemical structure of the aromatic oils can be summarized as follows:
1) Species of compound types were the same regardless the different ranks of coals.
2) Relative contents of aromatic types in fractions were different with rank of parent coal. The oil from Tenppoku coal, belonging to a low rank coal, had less number of naphthenic rings attached to monoaromatic compounds. On the comparison of the Z series distribution for Fr-T of oils from the three different coals, it can be observed that there is a shift to lower ring number for the oil from Tenppoku coal. On the other hand, the high rank coal, Miike coal, had larger naphthenic monoaromatic type and larger aromatic ring compounds in Fr-T.
3) Distribution of alkyl groups substituted to aromatic and hydroaromatic rings varied with the rank of coal. For Tenppoku coal, large alkyl structures to monoaromatics were observed while less alkyl structure substituted to tri-and tetraaromatic is predominating in the higher rank coal, Miike coal.
As shown before, HPLC-MS procedure is a useful method for the routine character-ization of the chemical structure of oils from coal liquids.
