Process for hydrotreating heavy hydrocarbons

A process for the hydrodemetallation and hydrodesulfurization of hydrocarbon feedstock containing asphaltenes and metals, said feedstock comprising at least one member selected from the group consisting of crude oil, topped crude oil, petroleum hydrocarbon residua, oils obtained from tar sands, and residua derived from tar sands oil, which process comprises contacting said hydrocarbon feedstock with hydrogen and a bimodal catalyst consisting essentially of at least one active original hydrogenation metal selected from Group VIB deposited on a support comprising alumina, said Group VIB metal being in at least one form selected from the group consisting of the elemental form, the oxide, and the sulfide, said catalyst having a surface area within the range of about 140 to about 300 m.sup.2 /gm, a total pore volume based upon measurement by mercury penetration within the range of about 0.4 cc/gm to about 1.0 cc/gm, and comprising about 60% to about 95% of its micropore volume in micropores having diameters within the range of about 50 A to about 200 A, 0% to about 15% of its micropore volume in pores having diameters within the range of about 200 A to about 600 A and about 3% to about 30% of said total pore volume in macropores having diameters of 600 A or greater.