In-situ analysis of solid bitumen in coal: examples from the Bowen Basin and the Illinois Basin

Solid bitumen and associated vitrinite from selected coals from the Bowen B asin and the Illinois Basin were studied using electron microprobe and micr o-FTIR techniques. The coal studied covers a range of vitrinite reflectance from 0.59% to 1.33%. Carbon content in the bitumen is generally lower than in vitrinite in coals with vitrinite reflectance below 0.67%. In coals wit h reflectance above 0.67%, carbon content of bitumen is higher than in vitr inite, reflecting higher aromaticity due to hydrocarbon generation, Sulfur and iron content are comparable between vitrinite and bitumen. Functional g roup distribution suggests the presence of two types of bitumen in the Illi nois Basin coals. The more aliphatic variety occurring in veins and cleats is interpreted as pre-gas generation bitumen, and the more aromatic variety filling cells and voids in inertinite as post-gas generation bitumen. (C) 2000 Elsevier Science B.V. All rights reserved.