Pressurized fluid extraction of coal

Three Argonne Premium Coals (Upper-Freeport, Pittsburgh #8, and Lewiston-St ockton) were extracted with benzene in both Soxhlet and pressurized fluid e xtraction (PFE) systems. The extracts were compared on the basis of dry mas s yield and hydrocarbon profiles as obtained by gas chromatography/mass spe ctrometry. The dry mass yields (wt%, daf) indicated no difference by either method for the Upper-Freeport coal, but statistically different yields wer e obtained for the Pittsburgh #8 and Lewiston-Stockton coals. In this study , PFE required similar to 90 vol.% less solvent compared to Soxhlet extract ion. The gas chromatograms obtained from the Soxhlet extracts contained sol vent contaminant peaks as dominant peaks, which were not observed in chroma tograms of the PFE extracts. No thermal degradation, as indicated by excess phenolic compound concentrations, was noted in any of the PFE extracts. (C ) 2000 Elsevier Science Ltd. All rights reserved.