Heavy oils, contg. asphaltenes and possibly high concns. of metals, are converted to fuel and petrochemical-precursors by donor-solvent-hydrovisbreaking (DSV) followed by fixed- bed catalytic hydrotreatment of one or more distillate fractions of the DSV prod. In the process claimed, distn. residue (II) from 18V prod., and donor solvent oil (III) from hydrotreater prod. are recycled to join fresh feedstock (I) as DSV feed. For treatment of crude oil, shale oil, coal tar, tar sands tar, bitumen, etc. Unlike processes including liq. phase hydrotreatment, a catalyst regeneration process is not needed, and there is no yield loss as on discharging a once-through catalyst. Demetallisation occurs (by distn.) with min. H2 consumption. The net yield of DSV residue is adjustable to requirements.
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