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Illinois No. 6 and Wyodak coals were coprocessed with Lloydminster and Hondo residua. The reactions were carried out in argon or in dideuterium with and without a catalyst at 400 °C for 1 h. The coal conversions under these mild conditions ranged from 40 to 56 %. Wyodak coal and Lloydminster residuum provided the highest coal conversion in uncatalyzed reactions. Spectroscopic evidence indicated that coal fragments appeared in the oil fraction at short reaction times but that they were much more abundant in the asphaltene fraction. An analysis of the results implies that coprocessing is essentially a stepwise process in which coals are degraded to asphaltenes and then to oils via hydrogen atom transfer and carbon-carbon bond fragmentation processes as well as deoxygenation reactions. Adduction reactions of the aliphatic residua and the aromatic coal occur simultaneously. The reactivity of the coal, in particular its capacity to initiate free-radical chain reactions and to donate hydrogen atoms, appears to play a key role in this chemistry. © 1991, American Chemical Society. All rights reserved. |
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