Abstract: When residual oil is cracked to gasoline in the presence of a fluidized zeolite catalyst the oil is first catalytically hydrodesulfurized so that sulfur oxide emissions from the catalyst regenerator are held to environmentally acceptable levels. The hydrodesulfurized residual oil is flash vaporized at the elevated temperature at the inlet of the cracking riser and most of the residual oil feedstock passes into the vapor state and is cracked to valuable products. However, a portion of the 1050.degree. F.+ (566.degree. C.+) residual material cannot be flash vaporized at the riser temperature and instead deposits upon the catalyst and is coked. Data are presented which show that as the proportion of the 1050.degree. F.+ (566.degree. C.+) components in a cracking feedstock decreases, the amount of these high boiling components in each barrel of cracker feedstock which are flash vaporized can actually increase. A multistage hydrodesulfurization operation is provided in which the proportion of 1050.degree. F.

Abstract: Residual oils which are thermally cracked with entrained hot solids in a low residence time riser must be hydrodesulfurized so that sulfur oxide emissions in the flue gas of the solids regenerator are maintained within environmentally acceptable limits. Of a full range residual oil thermal cracking feedstock, the lower boiling distillate feed components are capable of providing a higher ethylene yield with a lower dispersant steam requirement as compared to the high boiling residual feed components. In accordance with the present invention, the high boiling residual components of a thermal cracker feed residual oil are selectively removed during hydrodesulfurization to provide a non-aliquot distillate-residual oil hydrodesulfurization product in which the ratio of lower boiling distillate oil to high boiling residual oil is enhanced.

Abstract: In the catalytic hydrodesulfurization of residual oil the amount of hydrogen consumed per atom of sulfur removed is relatively low until the desulfurization becomes deep, whereupon the amount of hydrogen consumed per atom of sulfur removed becomes relatively high. The present invention provides a multistage process capable of producing products of low sulfur content while avoiding deep desulfurization of the heavy portion of the residual oil so that hydrogen consumption is diminished. The feed oil is fractionated to provide a residual fraction, a heavy distillate fraction and a light distillate fraction. The residual fraction and hydrogen are charged to an upstream hydrodesulfurization stage. A portion of the upstream stage residual oil effluent stream is split out of the process for use as refinery fuel and the remaining portion of the upstream stage effluent stream is charged to an intermediate hydrodesulfurization stage together with the heavy distillate feed fraction and hydrogen.

Abstract: In the hydrodesulfurization of residual oil the amount of hydrogen consumed per atom of sulfur removed is relatively low until the desulfurization becomes deep, whereupon the amount of hydrogen consumed per atom of sulfur removed becomes relatively high. The present invention provides a multistage hydrodesulfurization process capable of producing products of low sulfur level while avoiding deep desulfurization of the heavy portion of the residual oil so that hydrogen consumption is diminished. The feed oil is fractionated to provide distillate and residual fractions. The residual fraction and hydrogen are charged to an upstream catalytic hydrodesulfurization stage. A portion of the upstream stage effluent stream is diverted from the process for use as refinery fuel and the remaining portion of the upstream stage effluent stream is charged to a downstream catalytic stage together with the feed distillate oil and hydrogen.

Abstract: In the hydrodesulfurization of residual oil the amount of hydrogen consumed per atom of sulfur removed is relatively low until the desulfurization becomes deep, whereupon the amount of hydrogen consumed per atom of sulfur removed becomes relatively high. The present invention provides a multistage catalytic hydrodesulfurization process capable of producing products of low sulfur level while avoiding deep desulfurization of the heavy portion of the residual oil so that hydrogen consumption is diminished. The feed oil and hydrogen are passed through an upstream hydrodesulfurization stage and the upstream stage effluent is flashed to separate a distillate oil fraction from a concentrated residual oil fraction. A portion of the concentrated residual oil fraction is diverted from the process for use as refinery fuel and the remaining portion of the flash residue and hydrogen are charged to an upstream stage together with the flash distillate.

Abstract: A catalyst having utility as a downstream catalyst in processes for hydrodesulfurization of asphaltene-containing petroleum oils, coal liquids, shale oils or oils from tar sands which employ both upstream and downstream catalysts in series. The downstream catalyst comprises supported Group VI and Group VIII metals together with a promoting amount of a Group IV-B metal. The particles of said promoted catalyst are elongated extrudates whose surface is provided with a plurality of alternating longitudinal grooves and protrusions. In processes using this catalyst, the upstream catalyst comprises Group VI and Group VIII metals without promotion with Group IV-B metal and the particles of the upstream catalyst may or may not have similar surface grooves. The adaptation of the grooved particle configuration to the promoted catalyst composition provided the early development of a plateau-like aging curve which was not achieved by the adaptation of the grooved shape to a non-promoted catalyst.

Abstract: An improved method for presulfiding a hydrodesulfurization catalyst which comprises continuously contacting the catalyst with a sulfiding treating agent at a relatively low temperature and pressure and only until the total amount of sulfur in the treating agent contacting the catalyst is no more than 55 percent of the amount of sulfur required to sulfide the supported metals on the catalyst to their completely sulfided forms.

Abstract: An asphaltene-containing oil hydrodesulfurization process employing parallel first stages in series with a unified second stage. The second stage catalyst comprises supported Group VI and Group VIII metals together with a promoting amount of Group IV-B metal. The catalyst in the first stage comprises supported Group VI and Group VIII metals without promotion with Group IV-B metal. In the process, deactivated non-promoted catalyst is replaced at least once from at least one of the parallel first stages while continuing to operate the other of the parallel first stages to supply a reduced oil flow to the second stage during the catalyst replacement step.

Abstract: An asphaltene-containing oil hydrodesulfurization process employing stages in series with an interstage flashing step. The second stage catalyst comprises Group VI and Group VIII metals together with a promoting amount of Group IV-B metal. The coke level on the second stage catalyst is reduced by intermittent increase and decrease of the hydrogen pressure in the second stage.

Abstract: An asphaltene-containing oil hydrodesulfurization process employing a downstream catalyst and an upstream catalyst in a reactor. The downstream catalyst comprises supported Group VI and Group VIII metals together with a promoting amount of Group IV-B metal. The upstream catalyst comprises Group VI and Group VIII metals without promotion with Group IV-B metal.

Abstract: An asphaltene-containing oil hydrodesulfurization process employing stages in series with an interstage flashing step. The second stage catalyst comprises supported Group VI and Group VIII metals together with a promoting amount of Group IV-B metal. The first stage catalyst comprises supported Group VI and Group VIII metals without promotion with Group IV-B metal.

Abstract: An asphaltene-containing oil hydrodesulfurization process employing stages in series with an interstage flashing step. The second stage catalyst comprises supported Group VI and Group VIII metals together with a promoting amount of Group IV-B metal. The first stage catalyst comprises supported Group VI and Group VIII metals without promotion with Group IV-B metal. In the process, deactivated first stage catalyst is replaced at least once without replacing the promoted second stage catalyst so that the promoted second stage catalyst is onstream for at least two first stage catalyst cycles.