Effect of heating rate on normal and catalytic fixed-bed hydropyrolysis of coals

Fixed-bed hydropyrolysis tests have been conducted on a UK bituminous coal (Gedling), the Wyodak Argonne Premium coal sample and the high-sulfur Mequinenza lignite at a pressure of 15 MPa with heating rates of 5 and 300 K min(-1). The tar yields and overall conversions increased markedly by similar to 5-20 wt% daf coal as the heating rate was decreased from 300 to 5 K min(-1) for final temperatures of 520 and 600 degrees C, both with and without a sulfided molybdenum catalyst. Conversions of >90 wt% were achieved with slow heating in catalytic hydropyrolysis for all three coals. The small increases in gas yield indicated that tar-forming as opposed to hydrogasification reactions are promoted by slow heating. These results demonstrate the value of slow heating for analytical applications of hydropyrolysis, which include the determination of organic sulfur forms and the covalently bound biomarker hydrocarbons in coals and petroleum source rocks. Copyright (C) 1996 Elsevier Science Ltd.