Characterization of asphaltenes isolated from a coal-derived liquid

Coal-derived asphaltenes were isolated from the same liquid product in quantities from 11.8 to 21.7% depending upon the details of the separation procedure employed. Extensive characterization of these asphaltenes was used to uncover the chemical factors that influence the values of the quantitative determinations. The different asphaltenes were compared according to their molecular weights, molecular size distributions, relative weight of basic subfractions, and relative content of heteroatoms. Also, a subfraction was isolated which is accounted to asphaltenes or oils according to the details of the separation method. Several grams of this asphaltene/oil were further separated by acid/base fractionation and also by sequential elution by solvent chromatography. The functional group content of this fraction is roughly comparable to that of the total asphaltene fraction on a weight basis. Its molecular weight is intermediate between those of the oils and asphaltenes. 5 figures, 4 tables.