INVESTIGATION OF EXTRACTS OF COAL BY SUPERCRITICAL EXTRACTION

Supercritical extraction of Leping coal was isothermally carried out w ith toluene and its co-solvent at 355-425 degrees C/ 5-10 MPa in a sem i-continuous apparatus. The results indicated that extraction conditio ns affected the elemental composition, thermogravimetric characteristi cs and group components of extracts and their fractions. The yield of extract at 380 degrees C with toluene reached a maximum 64 wt% (in daf coal) containing 31 wt% oil which included aliphatics 22 wt%, aromati cs 20 wt% and polar compounds 39 wt%. H/C atomic ratio of oil in such an extract was 1.38 and its weight loss at 300 degrees C was 30%. Anal ysis of i.r. and H-1-n.m.r. spectra was employed to characterize the c oal extract and its fractions. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.