Separation of coal-derived liquids by gel permeation chromatography

Coal-derived liquids, obtained from pilot plants and bench-scale reactors, have been separated by gel permeation chromatography into aromatic, phenolic, and asphaltenic fractions, where asphaltenes and long-chain hydrocarbons are in the same fraction. The Chromatographie system uses 10 nm μStyragel columns and solvents such as tetrahydrofuran (THF) and toluene. The separation is reasonably clean and almost devoid of overlapping. The saturated hydrocarbons are separated from the asphaltenes by vacuum distillation. Aromatic, phenolic and aliphatic fractions are characterized by high-resolution gas chromatography—mass spectrometry. The phenolic fraction contains alkylated phenols, indanols, and naphthols. The aromatic fraction is composed of alkylated benzenes, indans, naphthalenes and small amounts of multi-ring aromatics such as alkylated fluorenes and pyrenes. Most of the long-chain hydrocarbon fraction is of straight-chain alkanes ranging from tetradecane to tetratetracontane. Some branched alkanes, such as pristane and phytane, are also present. If olefins are present in the sample they also separate with the long-chain hydrocarbon fraction. Although various analytical data such as i.r., n.m.r., molecular size distribution and elemental composition of asphaltenes have been obtained, the chemical characterization is not complete. The gel permeation Chromatographie separation technique, as discussed in this paper, is very useful for fast analysis of any coal-derived liquid.