Supercritical Fluid Fractionation of Petroleum- and Coal-Derived Mixtures

Abstract

A supercritical fluid chromatographic system was constructed to provide separations and fraction collection on a semipreparative scale. Columns packed with silica materials of intermediate particle sizes (30–70 μm) were used to allow dynamic pressure programming with minimum pressure drop of the CO2 mobile phase along the length of the column. A variety of complex coal- and petroleum-derived polycyclic aromatic compound mixtures were fractionated according to the number of aromatic rings using columns packed with an NH2-modifled stationary phase bonded on silica particles. The CO2 mobile phase was programmed with an alternating series of linear pressure ramps and isobaric Intervals to effect even peak spacing and near base line resolution of compounds of differing ring number in a coal tar. A solvent refined coal heavy distillate and a crude oil were similarly fractionated. Effluents were monitored with an ultraviolet spectrophotometer at 254 nm and a flame ionization detector while fractions were collected In pressurized vessels for subsequent analysis by capillary gas chromatography. Sample capacities of up to 20 mg were possible with this system. © 1986, American Chemical Society. All rights reserved.