Dynamic behaviour of supercritical fluid extractions of a crude oil and its vacuum residue

Dynamic extraction of a crude oil and its vacuum residue was carried out with supercritical carbon dioxide and propane to understand the nature of the extraction and partitioning processes as a function of pressure and temperature. The overall extraction performance of a solvent was governed by a complex interplay between extraction efficiency and feedstock volatility (heaviness). The extraction efficiency and extractive power of the solvent were linked to the solvent density, which increases with pressure. Enhanced solvating power of the solvent near the critical temperature of the pure solvent was evident when the extraction yields with respect to temperature were evaluated. Composition variations during an extraction sequence were determined by simulated distillation analysis of extracted samples. The results showed that the earlier extracts contained lighter compounds and the later extracts progressively heavier compounds. Differences in composition between extracted samples assessed by g.c.-m.s. provided evidence of composition variations. Copyright (C) 1996 Elsevier Science Ltd.