Gulf Research & Development Company

Harry C Stauffer

James A Frayer

Stephen J Yanik

Joel D McKinney

Raynor T Sebulsky

Harry C Murphy, Jr

Joseph A Bludis

David Lyzinski

Francis Edmund Wynne, Jr

James R Murphy

Millard C Bryson

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.+ (566.degree. C.+) residual components in the cracking feedstock is diminished whereby the amount of 1050.degree. F.+ (566.degree. C.+) residuals vaporized per barrel of feedstock during the subsequent cracking step is increased. The present method provides an interdependent advantage in the hydrodesulfurization operation since it reduces hydrogen consumption during hydrodesulfurization.

Combination residual oil hydrodesulfurization and catalytic cracking

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. Modifying the aliquot distribution of distillate and residual components in this manner provides an interdependent effect in the combination process since the distillate-enriched cracking feedstock not only provides both an improved ethylene yield and a greater steam economy in the thermal cracking operation but it also reduces hydrogen consumption in the hydrodesulfurization operation. Further interdependence between the hydrodesulfurization and thermal cracking operations is obtained by utilizing the residual oil which is selectively removed during the hydrodesulfurization step as fuel in the solids regenerator of the cracking unit, thereby making the more valuable, highly aromatic black oil produced in the thermal cracking process available for conversion to needle coke and carbon black.

Combination residual oil hydrodesulfurization and thermal cracking

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. A portion of the intermediate stage effluent stream is split out of the process as product fuel oil and the remaining portion of the intermediate stage effluent stream is passed to a downstream hydrodesulfurization stage together with the light distillate feed fraction and hydrogen. The downstream stage effluent stream constitutes the final and highest grade product of the process. Because of the combination of segmented feed addition and segmented product removal, not only are residue-containing streams removed from the process at the earliest possible time to avoid overtreating relative to their intended use, but also the removed streams are diluted with a reduced amount of low boiling distillate oil, conserving as much of the low boiling distillate oil as possible for inclusion in the product of the final stage. This method conserves distillate feed oil for the final and highest grade product and allows each hydrodesulfurization stage to be provided with a non-aliquot distillate-residual oil stream which is richer in low boiling distillate oil than its predecessor hydrodesulfurization stage.

Multistage residual oil hydrodesulfurization process employing segmented

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. The interstage diminution of the residual oil fraction provides a non-aliquot distillate-residual oil second stage feed stream which is relatively enriched in distillate oil. Since the sulfur in distillate oil is considerably less refractory than the sulfur in residual oil, the resulting dilution of the residual content of the downstream stage feed stream reduces hydrogen consumption by diminishing the depth of residual oil hydrodesulfurization required in the downstream stage to produce a low sulfur product.

Multistage residual oil hydrodesulfurization process

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. Since the sulfur in distillate oil is less refractory than the sulfur in residual oil, removal of a portion of the concentrated residual oil fraction provides a nonaliquot distillate-residual oil downstream stage feed stream which is easier to desulfurize to a low sulfur level than an aliquot distillate-residual oil stream. The dilution of the high sulfur residue in the downstream stage diminishes the depth of hydrodesulfurization required for residual components in the downstream stage, thereby reducing the level of hydrogen consumption required to produce a product having a low sulfur level.

Multistage residual oil hydrodesulfurization process with an interstage

A process for the production of lubricating oils from petroleum stocks containing significant quantities of sulfur and lubricating oil components boiling above about 650.degree. F. (343.degree. C.) by subjecting such stocks to a series of steps comprising hydrodesulfurization, fractionation, and solvent extraction. The residual fraction obtained from the fractionation step may be deasphalted prior to solvent extraction.

Process of hydrodesulfurization and separate solvent extraction of

A process for hydrodenitrogenation of shale oil comprising fractionating the shale oil into relatively light and heavy fractions, passing the relatively light fraction through a zone containing a catalyst comprising supported molybdenum and Group VIII metal and passing the relatively heavy fraction through a zone containing a catalyst comprising supported tungsten and Group VIII metal.

Hydrodenitrogenation of shale oil using two catalysts in parallel

A process for hydrodenitrogenation of shale oil to convert it to a feed oil for zeolitic riser cracking comprising passing the shale oil through two catalyst stages in series, the catalyst in the first stage comprising supported molybdenum and Group VIII metal and the catalyst in the second stage comprising supported tungsten and Group VIII metal.

Hydrodenitrogenation of shale oil using two catalysts in series reactors

A process for the production of lubricating oil in order to obtain lower viscosity lubricating oils of increased viscosity index by separating a crude lubricating oil into a residual fraction and a distillate fraction and thereafter subjecting the residual fraction to hydrotreating and separately subjecting the distillate fraction to hydrotreating under more severe conditions than employed in hydrotreating the residual fraction.

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Cheswick, PA, United States of America

Harry C Stauffer