“…The earlier work was mainly done in connection with the development of coal hydrogenation processes (Gordon, 1935(Gordon, , 1946(Gordon, , 1947Kronig, 1949;Pier, 1949), where a two-stage process was used in which coal was liquefied in the first stage, and the resulting heavy oil was hydrocracked in a subsequent stage to gasoline. In recent years, dual-functional catalysts containing both hydrogenation and cracking activities were developed for the hydrocracking of petroleum fractions (Larson et al, 1962;Myers et al, 1962). In recent years, dual-functional catalysts containing both hydrogenation and cracking activities were developed for the hydrocracking of petroleum fractions (Larson et al, 1962;Myers et al, 1962).…”