Chemical Structure of Coal Liquids from Coal Hydrogenation Reaction GPC Separation and Mass Spectrometry of Aromatic Oil

Abstract

Coal liquids derived from hydrogenation of Taiheiyo coal were separated into aromatic fractions according to the size of the molecular weight by a sequence of separation procedures of solvent extraction, liquid chromatography and gel permeation chromatography.
The molecular weight of the GPC fractions measured by VPO gave good separation results indicating a gradual decrease from 390 to 210 with the increase of the fraction number (Fig.3). The mass spectral profiles measured by the low voltage-low resolution method for the respective GPC fractions shifted from the high molecular weight range for first eluted fractions to the low one for later eluted fractions. The spectral range were however considerably broad (Fig.4). Average molecular weight of each GPC fraction calculated by the mass spectra coincided fairly well with the results from VPO (Fig.5).
Compound types of aromatics in the GPC fractio ns were analysed by estimation of hydrogen deficiency (Z value) from the respective mass peaks. Distribution of molecular weight with different carbon number of alkyl substitution for each compound type was also estimated. These distributions shifted gradually from the low molecular weight range for the compound type having higher Z values to the higher range for lower' Z values, and were considerably narrow for each compound type, except for the fraction A-2 which was one of the first eluted fractions (Fig.6).
The average molecular weight of the respective compound type for each fraction showed good correlation with th6 elution volume (Fig.7). From these correlation, not only the average molecular weight but also information concerning the chemical structure of the GPC fractions were derived.
Distributions of each compound type were estimated from the intensities of individual mass peaks for all the fractions taking into account the correction of molecular ion sensitivities derived by Lumpkin (Fig.9).