Comparison of Five Structural Analysis methods on Pitches

Abstract

Coal tar pitch, naphtha cracking pitch, oil produced from coal hydrogenolysis and two kinds of petroleum residual oil, which have the wide range of H/C value (0.6-1.7) and C% (93.5-84.4%), were analysed by IR-, n-d-, 1H-NMR-, 13C-NMR- and computer-method. The structural parameters were compared each other and the problems discussed.The pitches which are rich in aromatic part have good coincidence in all methods, so it was recomended to use computer method which gave the greatest numbers of the structural parameters.For the samples which are rich in aliphatic part, the values of x (y) or εar/εal gave big influence on the structural parameters in IR and 1H-NMR method. They are able to be obtained experimentally from 1H-NMR and 13C-NMR measurement. 13C-NMR method is the one which utilizes the results of both 1H-NMR and 13C-NMR and thought to be the most reliable method. Computer method coincides well with 13C-NMR method. No utilization of costful 13C-NMR and to be able to get more structural parameters than others are its superiority, but for the sample rich in aliphatic part there are many of the possibility of the set of structural parmeters which coincide to the practical data. In these cases the increase of the precision of experimental data must be required.Finally the structural models of each sample were proposed on the bases of struc-tural parameters obtained by computer method. The calculated x values of these model structure well coincide with those obtained from experimental values.