Conventional
catalysts are rapidly fouled with coke deposits when they are used to hydrocrack residual oils. The work reported here was part of an investigation on the removal of coke-forming compounds from residual oils prior to their contact with catalysts. Semianthracite ccal particles have been added to a reaction mixture of hydrogen and Athabasca bitumen at 13.9 MPa and 723 K, to provide a large surface area on which coke could deposit. Agglomeration of coal particles occurred during hydrogenation in the absence of bitumen, but did not occur when bitumen, coal, and hydrogen were all present together in the reaction system. A solid mass of coke formed when bitumen was hydrocracked in the absence of coal particles, but did not form when the bitumen was present with coal and hydrogen. These observations illustrate one of the advantages of processing bitumen and coal simultaneously. The solid particles from hydrocracking experiments, coal hydrogenation experiments, and experiments on coal carbonization were examined petrographically. It was found that coke formed from Athabasca bitumen has a different microstructure from that formed from semi-anthracite coal. On the basis of these studies it was concluded that semi-anthracite coal was converted to coke similar to that normally made from low-volatile bituminous coal. Simultaneously coke formed from the bitumen was deposited on the exterior of the particles.