Gulf Research & Development Company

Stephen J Yanik

James A Frayer

John A Paraskos

Harry C Stauffer

Robert D Christman

Jordan S Lasher

Angelo A Montagna

William S Bonnell

Joel D McKinney

Francis Edmund Wynne, Jr

Thomas C Readal

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

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.

Method for presulfiding hydrodesulfurization catalysts

An improved process for the hydrodesulfurization of hydrocarbons employing a catalyst comprising Group VI-B and Group VIII metals supported on a refractory oxide and promoted with a minor amount of titanium by contacting the refractory oxide with an aqueous solution of a titanium salt.

Hydrodesulfurization process employing a Group IV-B promoted catalyst

A shutdown procedure for residual hydrocarbon hydrodesulfurization process which employs a catalyst comprising Group VI-B and Group VIII metals, in sulfided form, supported on a refractory oxide and promoted with a minor amount of titanium.

Hydrodesulfurization shutdown method

A process for hydrodesulfurizing a residual oil by passing the oil downwardly through a catalytic reaction zone at a hydrogen pressure which is sufficiently high that demetallization occurs rapidly so that at end-of-run the upstream catalyst region is more nearly metals-saturated than the downstream catalyst region. At the end of the catalyst cycle, the more nearly metals-saturated upstream portion of the catalyst is removed from the process while the less nearly metals-saturated downstream portion of the catalyst is passed to a guard chamber where during further operation of the process it approaches metals-saturation. In this manner, no portion of catalyst is removed from the process until it has an elevated metals content.

Hydrodesulfurization process employing a guard chamber

A process and apparatus for the hydrodesulfurization of residual oil in a plurality of catalyst zones in series with the upstream reactor being removed periodically for a catalyst change. When an upstream zone is taken off-stream for a catalyst change, the fresh feed oil is passed to a succeeding downstream zone so that the downstream catalyst zone is upstaged to the status of an upstream catalyst zone. When a zone is returned to service after a catalyst change, it enters the process as a downstream reactor in the series.

Hydrodesulfurization apparatus with upstaged reactor zones

A process for the hydrodesulfurization of residual oil in a plurality of catalyst zones in series with the upstream reactor being removed periodically for a catalyst change. When an upstream zone is taken off-stream for a catalyst change, the fresh feed oil is passed to a succeeding downstream zone so that the downstream catalyst zone is upstaged to the status of an upstream catalyst zone. When a zone is returned to service after a catalyst change, it enters the process as a downstream reactor in the series.

Hydrodesulfurization process with upstaged reactor zones

A multiple stage process for hydrodesulfurizing a residual oil comprising passing the oil downwardly through a plurality of stages in series with an interstage flashing step. A portion of the fresh feed oil continuously or intermittently by-passes the first stage and flows directly to the second stage.

Multiple stage hydrodesulfurization process including partial feed oil

A multiple stage process for hydrodesulfurizing a residual oil while passing the oil downwardly through a plurality of stages in series with an interstage flashing step. After the catalyst in the downstream stage is deactivated by coke deposition, fresh feed oil is passed directly to the deactivated catalyst to obtain an extended life in the downstream catalyst.

Multiple stage hydrodesulfurization process with extended downstream

A process is described for fixed bed hydrodesulfurizing a non-asphaltic oil feed blend for a zeolitic FCC riser cracking system in which cracking occurs at a space velocity sufficiently high to prevent formation of a catalyst bed. It is shown that sulfur dioxide emissions from the zeolite catalyst regenerator associated with the riser are reduced to a lower extent than total sulfur removal from the feed oil. This indicates uneven sulfur removal in the hydrodesulfurization step whereby a smaller portion of sulfur is removed from the heavy portion of the feed from which the coke is derived than from the lighter portion of the feed. The present invention demonstrates a synergistic effect upon sulfur removal from the heavy portion of the feed by widening the boiling range of the feed and this synergistic effect is converted to practical advantage by reducing the amount of hydrodesulfurization catalyst in proportion to said synergistic effect, thereby keeping hydrocracking to a specified low level. The boiling range of the feed is widened by adding to the higher boiling portion of the feed a portion of a second stream to lower the average boiling point of the hydrodesulfurization feed whereby the sulfur content of the remaining portion of the second stream is sufficiently low that the second stream does not require desulfurization. The further discovery is demonstrated herein that the ratio of gasoline to total conversion during the subsequent riser cracking step of the hydrodesulfurizer effluent is enhanced by reducing the amount of the hydrodesulfurization catalyst as permitted by said synergistic effect.

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Valencia, PA, United States of America

Stephen J Yanik