Thermal and catalytic conversion of asphaltenes

Asphaltenes isolated from coal liquids and tar sand bitumen have been converted thermally and with acid and/or hydrogenation catalysts. The conversions, based on solubility classes - preasphaltenes, asphaltenes and oil - have been determined for increasing reaction time. The removal of heteroatoms in each solubility class was also followed with increasing conversion. Gaseous deuterium was utilized in some studies to follow the extent of exchange reactions. There is a rapid initial conversion at each reaction temperature, and this is followed by a much slower conversion process. The deuterium distribution in the products suggest that the asphaltene decomposes to produce a stable oil molecule and a radical fragment that remains in the asphaltene solubility range. (C) 2001 Elsevier Science Ltd. All rights reserved.