US3801494A - Combination hydrodesulfurization and reforming process - Google Patents

Abstract

THE PROCESS COMPRISES CONTACTING A DESULFURIZED NAPHTHA IN A REFORMING ZONE IN THE PRESENCE OF A HYDROGENCONTAINING GAS WITH A REFORMING CATALYST COMPRISING A GROUP VIII NOBLE METAL, A SMALL AMOUNT OF A METAL PROMOTER, AND A COMBINED HALOGEN ON A CATALYTICALLY ACTIVE ALUMINA AT A PRESSURE OF ABOUT 50 P.S.I.G. TO ABOUT 250 P.S.I.G. AND AN INLET TEMPERATURE OF AT LEAST 970* F. TO PROVIDE A REFORMED EFFLUENT CONTAINING INCREASED AMOUNTS OF HYDROGEN AND GASOLINE BOILING COMPONENTS; SEPARATING THE HYROGEN-CONTAINING GAS FROM THE GASOLINE BOILING COMPONENTS AND PASSING THE HYDROGEN-CONTAINING GAS SEQUENTIALLY THROUGH A NAPHTHA-HYDRODESULFURIZATION ZONE, A GASOIL-HYDRODESULFURIZATION ZONE, AND A HEAVY DISTILLATE-HYDRODESULFURIZATION ZONE. THE NAPHTHA BEING HYDRODESULFURIZED IN THE NAPHTHA-HYDRODESULFURIZATION ZONE IS THE DESULFURIZED NAPHTHA THAT IS EMPLOYED IN THE REFORMING ZONE THE PREFERRED METAL PROMOTER OF THE REFORMING CATALYST IS RHENIUM.

Description

T. M. MOORE ETAL Apnl 2, 1974 GUMBLNAIION HYDI'{ODESULFURIZA.ION AND REFORMING PROCESS 5 Sheets-Sheet l Filed Sept MQW 4G34 n Ni ...wh Q lk QQ QMS.

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COMBINATION HYDRODESULFURIZA'UION AND REFORMING VPROCESS Filed Sept. l5, 1972 5 Sheets-Sheet 4 Y jt m I Qn 5 N A E u Q 64S ou April 2, 1974' T. M. MOORE ETAL COMBINATION HYDRODESULFURIZA". ION AND REFORMING PROCESS 5 sheets-sheet s Filed Sept. l5, 1972 @QN WN QQQQQG, QN @QN NQN NWN Y QQN BIV/Wb LONI United States Patent Olhcer 3,801,494 Patented Apr. 2, 1974 U.S. Cl. 208-79 14 Claims ABSTRACT oF THE DISCLOSURE The process comprises contacting a desulfurized naphtha in a reforming zone in the presence of a hydrogencontaining gas with a reforming catalyst comprising a Group VIII noble metal, a small amount of a metal promoter, and a combined halogen on a catalytically active alumina at a pressure of about 50 p.s.i.g. to about 250 p.s.i.g. and an inlet temperature of at least 970 F. to provide a reformed efuent containing increased amounts of hydrogen and gasoline boiling components; sep-arating the hydrogen-containing gas from the gasoline boiling components and passing the hydrogen-containing gas sequentially through a naphtha-hydrodesulfurization zone, a gasoil-hydrodesulfurization zone, and a heavy distillate-hydrodesulfurization zone. The naphtha being hydrodesulfurized in the naphtha-hydrodesulfurization zone is the desulfurized naphtha that is employed in the reforming zone. The preferred metal promoter of the reforming catalyst is rhenium.

BACKGROUND OF THE INVENTION Processes for the hydrodesulfurization of petroleum hydrocarbons and processes for reforming naphthas and hydrocarbons boiling in the gasoline boiling range are important petroleum refining processes that are employed extensively in todays petroleum refinery.

A hydrodesulfurization process may be employed to desulfurize a petroleum naphtha or a petroleum hydrocarbon fraction boiling in the gasoline boiling range. In addition, a hydrodesulfurization process may be used to treat either a light distillate, such as a light gas oil, or a heavy distillate such as a lubricating oil base stock. In any event, each of these hydrodesulfurization processes requires hydrogen in its operation. Ordinarily, the hydrodesulfurization process, whether it is used to treat a light distillate, a heavy distillate, or a naphtha, employs a hydrodesulfurization catalyst comprising a hydrogenation, component and a catalytic support having little or no cracking activity.

Processes for the reforming of a petroleum hydrocarbon stream provide high-octane-number hydrocarbon blending components for gasoline. In the typical reforming process, various reactions take place. These reactions include dehydrogenation reactions, isomerization reactions, and hydrocracking reactions. Examples of the dehydrogenation reactions are the dehydrogenation of cyclohexanes to aromatics, the dehydroisomerization of alkyl cyclopentanes to aromatics, the dehydrogenation of parains to olefins, and the dehydrocyclization of parafins and olefns to aromatics. Examples of the isomerization reactions are the isomerization of normal parains to isoparafns, the hydroisomerization of oleiins to isoparains, the isome-rization of alkyl cyclopentanes to cyclohexanes, and the isomerization of substituted aromatics. Examples of hydrocracking reactions are hydrodesulfurization and the hydrocracking of paraflns. Adequate discussions of the reactions that occur in a reforming reaction zone are presented in Petroleum Processing, R. J. Hengstebeck, McGraw-Hill Book Co., Inc., 1959, pp. 179- 184, and in Catalysis, vol. VI, P. H. Emmett, editor, Reinhold Publishing Corp., 1958, pp. 497-498.

Various catalysts may be employed to reform petroleum naphthas and hydrocarbon streams that boil in the gasoline boiling range. Among these are molybdenumoXides-on-alumina catalysts, chromium-oxides-on-alumina catalysts, platinum-halogen-on-alumina catalysts, and platinum-aluminosilicate-material-alumina catalysts. Generally, those catalysts that contain platinum as a hydrogenation component are the catalysts that are used today in the reforming processes of the petroleum refining industry. Many of these platinum-containing reforming catalysts may be promoted by a small amount of another metal, such as rhenium, as taught in U.S. Pat. 3,415,737 and in U.S. Pat. 3,434,960. Prior to the use of such bi-metallic catalysts, reforming processes employing a catalyst containing platinum as a hydrogenation-dehydrogenation component were operated at a pressure that was generally in excess of 300 p.s.i.g. and, sometimes, was as high as 700 p.s.i.g. Such high pressures were employed to control advantageously catalyst deactivation and coke deposition. If a reforming process employing a catalyst comprising platinum, halogen, and alumina were conducted at a pressure below 350 p.s.i.g., for example, at a pressure below 250 p.s.i.g., the catalyst would become rapidly fouled by the coke deposited thereon and would need very frequent reactivation. It has been found recently that the bimetallic catalysts provide extended catalyst life and reduced deactivation when employed in a low-pressure reforming operation.

Until this time, those reforming processes that have employed a catalysts containing platinum and a second metal, such as rhenium, have been either a non-regenerative process or a semi-regenerative process. Typically, the non-regenerative reforming process employs a reforming catalyst over an extended period of time until that catalyst has become deactivated. Then the catalyst is removed from the unit and either replaced by fresh catalyst or returned to the unit after it has been reactivated. In a semiregenerative reforming process, the catalyst is employed for reforming over an extended period of time. When the catalyst has become deactivated, the reforming operation is stopped and the total amount of catalyst in the reforming unit is regenerated in situ.

Recently, there has been developed an improved reforming process. This improved process employs a bimetallic catalyst, is operated at low pressures and relatively high temperatures, and employs a cyclic or regenerative operation. Such bi-metallic catalyst may be a platinum-rhenium catalyst or a catalyst having similar characteristics, such as a platinum-iridium catalyst. A cyclic or regenerative reforming process is one which employs a swing reactor that is used to replace one of the reactors in the reforming system while the catalyst in the latter reactor is being reactivated. In this way, the reforming of the petroleum hydrocarbon is not interrupted, while the catalyst is being regenerated. Upon regeneration of the catalyst in the reactor, that reactor is returned to the reforming system and either the swing reactor may be used to replace another reactor in the system or the catalyst in the swing reactor may be regenerated. The regenerative reforming process operates continuously to provide maximum performance, while the catalyst in each of the various reactors is periodically regenerated. Such regenerative process employing a catalyst comprising a platinum group metal and a small amount of rhenium, when operated at low pressure and high temperature, provides a. relatively large amount of hydrogen having greater purity and provides maximum yields of gasoline blending components.

Now there has been found a combination process for the refining of various petroleum hydrocarbon streams,

which combination process couples the advantages of a regenerative, low-pressure, bimetallic-catalyst reforming process with the maximum utilization of the high-purity hydrogen produced by said reforming process as the hydrogen feed to several hydrodesulfurization processes.

SUMMARY OF THE INVENTION Broadly, according to the process of the present invention, there is provided a petroleum hydrocarbon conversion process for the hyrodesulfurization of a naphtha in a naphtha-hydrosulfurization zone, a gas oil in a gas-oilhydrodesulfurization zone, and a heavy distillate in a heavy-distillate-hydrodesulfurization zone to obtain a desulfurized naphtha, a desulfurized gas oil, and a desulfurized heavy distillate, respectively, and for the regenerative reforming of said desulfurized naphtha in a regenerative reforming zone to provide increased amounts of hydrogen and vgasoline blending components. This process produces hydrogen having very high purity and provides an improved utilization of such hydrogen for the hydrodesulfurization of said naphtha, said gas oil, and said heavy distillate by employing that hydrogen on a oncethrough basis as the feed hydrogen for the three different hydrodesulfurization zones. This process comprises: contacting in said reforming zone said desulfurized naphtha in the presence of a hydrogen-containing reactant gas with a reforming catalyst comprising a Group VIII noble metal, a small amount of a metal promoter, and a combined halogen on a catalytically active alumina at a pressure of about 50 p.s.i.g. to about 250 p.s.i.g. and an inlet temperature of at least 970 F. to provide a reformed efuent containing said increased amounts of hydrogen and gasoline blending components; separating said reformed efliuent into a first hydrogen-containing product gas and said gasoline blending components; dividing said first hydrogen-containing product gas into a iirst hydrogen-containing gas and a second hydrogen-containing gas; sending said first hydrogen-containing gas to said reforming zone to be used as said hydrogen-containing reactant gas; sending said second hydrogen-containing gas to said naphtha-hydrodesulfurization zone to be mixed with said naphtha and contacted in said naphtha hydrodesulfurization zone with a iirst hydrodesulfurization catalyst to provide a desulfurized naphtha eiiluent, said desulfurized naphtha eiiiuent bein-g lseparated into said desulfurized naphtha. to be sent to said reforming zone and a second hydrogen-containing product gas; sending said second hydrogen-containing product gas to said gas-oil hydrodesulfurization zone to be mixed with said gas oil and contacted in said gas-oil-hydrodesulfurization zone with a second hydrodesulfurization catalyst to provide a desulfurized gas-oil eliluent, Isaid desulfurized gas-oil effluent being separated into said desulfurized gas oil and a third hydrogen-containing product gas; sending said third hydrogen-containing product gas to said heavydistillate-hydrodesulfurization zone to be mixed with said heavy-distillate and contacted in Isaid heavy-distillate hydrodesulfurization zone with a third hydrodesulfurization catalyst to provide a desulfurized heavy-distillate effluent, said desulfurized heavy-distillate efiiuent being separated into said desulfurized heavy distillate and a fourth hydrogen-containing product gas, said rst hydrodesulfurization catalyst, said second hydrodesulfurization catalyst, and said third hydrodesulfurization catalyst each comprising a hydrogenation component on a refractory inorganic oxide support.

The preferred Group VIII noble metal in the reforming catalyst is platinum, which may be present in an amount of about 0.01 to about 2 weight percent, based on the weight of the catalyst. The preferred metal promoter is rhenium and may be present in an amount of about 0.05 to about 2.5 weight percent, based on the weight of the catalyst. The combined halogen, preferably chlorine, may be present in an amount of about 0.01 to about 2 weight percent, based on the weight of the catalyst. A preferred hydrogenation component for each of the hydrodesulfurization catalysts comprises one or more members of the group consisting of a Group VI-B metal of the Periodic Table of Elements, a Group VIII metal of the Periodic Table, their suliides, their oxides, and mixtures thereof.

DESCRIPTION OF THE DRAWINGS An embodiment of the process of the present invention is presented in the accompanying iive figures.

FIG. 1 is a very simplified block diagram of the selected embodiment of the process of the present invention.

FIG. 2 is a simplified schematic ow diagram of the naphtha-hydrodesulfurization zone of the embodiment of the process of the present invention.

FIG. 3 is a simplified schematic ow diagram of the reforming zone of the embodiment of the process of the present invention.

FIG. 4 is a simplified schematic iiow diagram of the gas-oil-hydrodesulfurization zone of the embodiment of the process of the present invention.

FIG. 5 is a simplified schematic flow diagram of the heavy-distillate-hydrodesulfurization zone of the embodiment of the process of the present invention.

In each of these simplified schematic iiow diagrams of the various zones of the embodiment of the process of the present invention, certain pieces of auxiliary equipment, such as pumps, compressors, heat exchangers, and some valves are not shown. The use and location of such pieces of auxiliary equipment are well known to those skilled in the art and, therefore, these certain pieces of auxiliary equipment are not necessary in the drawings depicting the process.

DESCRIPTION AND PREFERRED EMBODIMENT The process of the present invention is a combination process wherein a naphtha or a hydrocarbon stream boiling in the gasoline boiling range is hydrodesulfurized in a naphtha-hydrodesulfurization zone to reduce the sulfur contained therein to a level that does not exceed 5 parts per million sulfur. The resulting desulfurized effluent is reformed in a regenerative or cyclic reforming process, which is operated at low pressure and high temperature and which employs a catalyst comprising a Group VIII noble metal, a small amount of a metal promoter, such as rhenium, and a combined halogen on a refractory inorganic oxide support and which employs a `temperature that is at least 970 F. to provide increased yields of highoctane gasoline blending components and large quantities of a hydrogen-containing gas. At least a portion of the hydrogen-containing gas obtained from the reforming process is employed as the hydrogen-containing gas that is sent sequentially to and through said naphtha hydrodesulfurization zone, a gas-oil-hydrodesulfurization zone, and a heavy-distillate-hydrodesulfurization zone. Since the amount of flow of hydrogen to each of these process zones is sufi'icient to obtain products of the desired quality, no provision need be made for recycling of any of the hydrogen rich gas in any of these hydrodesulfurizaton zones. In -vieW of this, at least two recycle-gas compressors and one amine scrubber can be eliminated from such a process scheme. The amine scrubber would have been required for the removal of hydrogen sulfide, if recycling of the hydrogen-rich gas were employed in the gas-oilhydrodesulfurization zone. In view of the above, the combination process of the present invention provides maximum yields of gasoline-boiling-range hydrocarbons and increased yields of high-purity hydrogen, while employing minimum utilities and minimum amounts of catalyst.

Broadly, according to the process of the present invention, there is provided a combination process for producing increased amounts of a gas stream of high-purity hydrogen and high-octane gasoline blending components. It is a petroleum hydrocarbon conversion process for the hydrodesulfurization of a hydrocarbon stream boiling in the gasoline boiling range, such as a naphtha, in a naphthahydrodesulfurization zone, the hydrodesulfurization of a light distillate, such as a gas oil, in a gas-oil-hydrodesulfurization zone and the hydrodesulfurization of a heavy distillate, such as a lubricating oil base stock, in a heavydistillate-hydrodesulfurization zone and for the regenerative reforming of said desulfurized naphtha in a regenerative reforming zone. This process provides maximum utilization of the hydrogen produced therein for the hydrodesulfurization of the various hydrocarbon streams. This process comprises: contacting in said reforming zone said desulfurized naphtha in the presence of a hydrogen-containing reactant gas with a reforming catalyst comprising a Group VIII noble metal, a small amount of a metal promoter, and a combined halogen on a catalytically active alumina at a pressure of about 50 p.s.i.g. to about 250 p.s.i.g. and an inlet temperature of at least 970 F. to provide a reformed effluent containing increased amounts of hydrogen and gasoline blending components; separating said reformed effluent into a first hydrogencontaining product gas and said gasoline blending components; dividing said first hydrogen-containing product gas into a first hydrogen-containing gas and a second hydrogen-containing gas; sending said rst hydrogen-containing gas to said reforming zone to be used as said hydrogen-containing reactant gas; sending said second hydrogen-containing gas to said naphtha-hydrodesulfurization zone to be mixed with said naphtha and contacted in said naphtha-hydrodesulfurization zone with a first hydrodesulfurization catalyst to provide a desulfurized naphtha effluent, said desulfurized naphtha effluent being separated into said desulfurized naphtha to be sent t said reforming zone and a second hydrogen-containing product gas; sending said second hydrogen-containing product gas to said gas-oil-hydrodesulfurizaton zone to be mixed with said gas oil and contacted in said gas-oil hydrodesulfurization zone with a second hydrodesulfurization catalyst to provide a desulfurized gas-oil effluent, said desulfurized gas-oil eiiiuent being separated into said desulfurized gasoil and a third hydrogen-containing product gas; sending said third hydrogen-containing product gas to said heavydistillate-hydrodesulfurization zone to be mixed with said heavy distillatae and contacted in said heavy-distillatehydrodesulfurization zone with a third hydrodesulfurization catalyst to provide a desulfurized heavy-distillate effluent, said desulfurized heavy-distillate effluent being separated into said desulfurized heavy distillate and a fourth hydrogen-containing product gas, said first hydrodesulfurization catalyst, said second hydrodesulfurization catalyst, and said third hydrodesulfurization catalyst each comprising a hydrogenation component on a refractory inorganic oxide suppor-t.

The hydrocarbon feed stock that is to be sent to the naphtha-hydrodesulfurization zone of the process of the present invention may be a feedstock comprising a virgin naphtha, a cracked naphtha, or mixtures thereof, boiling in the range of about 70 F. to about 500 F., and preferably within the range of about 180 F. to about 400 F. Such a feedstock may contain sulfur in an amount greater than 10 p.p.m., and, therefore, is hydrodesulfurized to reduce this sulfur level to a value that is less than p.p.m., advantageously, less than 2 p.p.m., and preferably, less than 1 p.p.m. sulfur. This hydrodesulfurization is accomplished by mixing the hydrocarbon stream to be hydrodesulfurized with a hydrogen-rich gas to form a mixture of the gas and the hydrocarbon stream and contacting said mixture in the naphtha-hydrodesulfurization zone with a suitable hydrodesulfurization catalyst at a temperature of about 500 F. to about 725 F., a hydrogen partial pressure of about 75 p.s.i.a. to about 400 p.s.i.a., a liquid hourly space velocity (LHSV) of about 2 to about l0 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.

Any suitable hydrodesulfurization catalyst may be employed in the naphtha-hydrodesulfurization zone as the first hydrodesulfurization catalyst of the process of the present invention. A suitable catalyst comprises a hydrogenation component supported on a refractory inorganic oxide support having little or no cracking activity. The hydrogenation component may comprise a Group VI-B metal and/ or a Group VIII metal of the Periodic Table of Elements shown on p. 628 of Websters Seventh New Collegiate Dictionary, G. and C. Merriam Company, Springfield, Mass., U.S.A. (1963). Typical Group VLB metals are molybdenum and tungsten; typical Group VIII metals are cobalt and nickel. A preferred hydrogenation component comprises one or more members of the group consisting of cobalt and molybdenum, nickel and molybdenum, nickel and tungsten, their oxides, their sullides, and mixtures thereof. Any suitable refractory inorganic oxide, being neutral or weakly acidic, may be employed as a support for this hydrodesulfurization catalyst, such as silica gel, alumina, and silica-stabilized alumina. A typical support is a catalytically active lumina, which may be either a gamma-alumina, or an eta-alumina, or both. It should have an average pore diameter of about 70 A. to about 200 A., or larger. The alumina should have a surface area of at least square meters per gram. Suitably, the surface area should be within the range of about 200 to about 800 square meters per gram, or larger.

This first hydrodesulfurization catalyst may be prepared by adding a suitable compound of each metal of the hydrogenation component to a sol or gel of the refractory inorganic oxide. This composition may be thoroughly blended and the sol or gel mixture may be co-gelled subsequently by the addition of dilute ammonia. Then the resulting co-gelled material may be dried and calcined. Alternately, the refractory inorganic oxide may be gelled, dried, pelleted, calcined, and cooled. The resulting material may then be impregnated with a solution or solutions containing the metal or metals of the hydrogenation component. Suitable calcination conditions cornprise a temperature in the range of about 900 F. to about 1,lOO F. and a calcination time of about 1 to about 20 hours. Suitable drying conditions comprise a temperature of about 200 F. to about 400 F. and a drying time of about 3 hours to about 30 hours. Preferably, drying conditions comprise a temperature of about 250 F. for about 8 hours to about 16 hours and calcination conditions comprise a temperature of about 1,000 F. for about 2 hours to about 6 hours.

After long periods of use, the catalyst employed in the naphtha-hydrodesulfurization zone becomes deactivated and may be regenerated by burning the carbonaceous deposits therefrom with an oxygen-containing gas pursuant to typical catalyst regeneration techniques well known to those skilled in the art.

The effluent from the reactor in the naphtha-hydrodesulfurization zone is cooled and separated into a hydrogen-containing gas and a liquid product. The hydrogencontaining gas is sent to the gas-oil-hydrodesulfurization zone. The liqud product is flashed in a low-pressure separator and the liquid material is debutanized and subsequently separated into a light naphtha stream, a heavy naphtha stream, and an intermediate fraction, which is employed as the hydrocarbon material for reforming in the regenerative reforming zone of the process of the present invention.

The intermediate naphtha stream is sent to the reforming zone of the process of the present invention. Prior to its introduction into the reforming zone, this intermediate naphtha stream is mixed with a hydrogen-rich gas stream that is recycled from the reforming zone of the process of the present invention. Broadly, according to the process of the present invention, there is provided a low-pressure, high-temperature regenerative reforming process to provide a gasoline blending stock that has an unleaded research octane number within the range of about 96 to about 106. This reforming process is conducted in the reforming zone of the process of the present invention, which reforming zone employs a plurality of reaction zones or reactors through which the petroleum hydrocarbon stream that is being reformed is passed sequentially. The first reaction zone has an inlet temperature of at least 970 F. Each subsequent reaction zone has an inlet temperature of at least 985 Each reactor or reforming zone contains a catalyst comprising a Group VIII nobel metal, a small amount of a metal promoter, and a combined halogen on a support comprising a refractory inorganic oxide. The preferred Group VIII noble metal is platinum and is present in an amount of about 0.01 to about 2 weight percent. While platinum is the preferred Group VIII noble metal, other Group VIII noble metals, such as ruthenium, rhodium, palladium, osmium, and iridium, may be employed. It is contemplated that the metal promoter may be rhenium, iridium, tungsten, or gallium. The preferred metal promoter is rhenium and is present in an amount of about 0.05 weight percent to about 2.5 weight percent. Preferably, the catalyst contains a combined halogen, such as chlorine or fluorine. The halogen may be present in an amount of about 0.01 weight percent to about 2 weight percent. The preferred halogen is chlorine. The preferred support s a catalytically active alumina. The catalytically active alumina that is employed as the support material for the reforming catalyst may be any catalytically active alumina, as described hereinabove.

The reforming catalyst that is employed in the process of the present invention may be prepared in various ways. For example, a suitable compound of the hydrogenation metal and a suitable compound of the metal promoter may be added to a sol or gel of the catalytically active alumina. This composition may be thoroughly blended and the sol or gel mixture may be co-gelled subsequently by the addition of dilute ammonia. The resulting co-gelled material may then be dried and calcined. In another method of preparation, the catalytically active alumina is gelled, dried, pelleted, calcined, and cooled, and the resulting composition is then impregnated with a solution of the Group VIII noble metal and/or a solution of the metal promoter. Suitable drying and calcination conditions are described hereinabove. The halogen may be incorporated into the catalytic composition as a halide of the hydrogenation metal, or as a halogen acid, or as a halide salt.

The reforming zone of the process of the present invention comprises a plurality of reaction zones or reactors through which the petroleum hydrocarbon stream that iS to be reformed is passed sequentially. This plurality f reactors comprises a first reactor, at least one intermedate reactor, and a `final reactor. In addition, there is an alternate reactor, called a swing reactor. The inlet temperature of the rst reactor is at least 970 F., while the inlet temperatures of the intermedaite reactor or reactors and the final reactor are at least 985 F. The inlet temperatures to the reaction zones may be as high as 1,100 F. Other reforming operating conditions comprise a pressure of about 50 p.s.i.g. to about 250 p.s.i.g.; a hydrogen-containing recycle gas rate of about 1,000 s.c.f.b. to about 5,000 s.c.f.b.; and a weight hourly space velocity (WHSV) of about 2 to about 10 weight units of hydrocarbon per hour per weight unit of catalyst. The preferred operating conditions for the reforming zone comprise inlet temperatures that range from about 980 F. to about 1,050 F.; a pressure of about 125 p.s.i.g. to about 175 p.s.i.g.; a hydrogen-containing recycle gas rate of about 1,500 s.c.f.b. to about 3,000 s.c.f.b.; and a WHSV of about 2 to about 5 weight units of hydrocarbon per hour per weight unit of catalyst.

In the reforming zone of the process of the present invention, the process comprises contacting a mixture of the hydrocarbon stream to be reformed and a hydrogen-containing reactant gas with a reforming catalyst comprising a Group VIII noble metal, a small amount of a meal promoter, and a combined halogen on a catalytically active alumina in a rst reaction zone having an inlet temperature of at least 970 F. to obtain a iirst reformate; contacting said rst reformate with reforming catalyst in at least one intermediate reaction zone having an inlet temperature of at least 985 F. to obtain an intermediate reformate; and contacting said intermediate reformate with reforming catalyst in a iinal reaction zone having an inlet temperature of at least 985 F. to obtain a nal reformate, said process employing a pressure within the range of about 50 p.s.i.g. to about 250 p.s.i.g.; separating said final reformate into a rst hydrogen-containing product gas and high-octane blending components; dividing said hydrogen-containing product gas into a first hydrogencontaining gas and a second hydrogen-containing gas; sending said rst hydrogen-containing gas to said reforming zone to be used as said hydrogen-containing reactant gas; and sending said second hydrogen-containing gas to said naphtha-hydrodesulfurization zone.

The catalyst in each of the reforming reactors or reaction zones is regenerated periodically by typical catalyst regeneration techniques well-known to those skilled in the art. When the catalyst in any of the reactors becomes deactivated and must be regenerated, that reactor is removed from the reforming system and is replaced individually by the alternate reactor or swing reactor. Hence, the alternate reactor takes the place of the reactor that is removed from the reforming system and permits the reforming operation to be performed continuously. The catalyst in the reactor that has been taken from the reforming system is regenerated by burning carbonaceous deposits therefrom with a gas containing at least a small amount of oxygen. If the halogen that has been removed from the catalyst is to be replaced, it may be incorporated onto the catalyst during this regeneration procedure by methods well known to those skilled in the art. Advantageously, each of the reactors in the system is periodically replaced by the swing reactor so that the catalyst in that particular reactor may be reactivated. Regeneration of the catalyst in a single reactor may be accomplished in 12 to 24 hours. A definite schedule of which reactor in the system is to be regenerated may be maintained. In this way, the overall catalyst in the reforming zone is maintained with a maximum activity, which results in improved performance for producing high-octane blending components and larger amounts of hydrogen-rich gas.

The hydrogen-rich gas that is obtained from the naphtha-hydrodesulfurization zone of the process of the present invention is sent to the gas-oil-hydrodesulfurization zone of the process of the present invention. Typical feedstocks that may -be hydrodesulfurized in the gas-oil-hydrodesulfurization zone are distillates boiling from about 350 F. to about 1,000 F., preferably having a maximum boiling point of about 800 F. That portion of the process of the present invention which occurs in the gas-oil-hydrodesulfurization zone comprises mixing a gas oil with the hydrogen-containing gas obtained from the naphthahydrodesulfurization zone to form a mixture of said gas oil and said hydrogen-containing gas; contacting said mixture in the gas-oil-hydrodesulfurization zone with a second hydrodesulfurization catalyst at a temperature of about 600 F. to about 725 F.; a hydrogen partial pressure of about p.s.i.a. to about 375 p.s.i.a.; a LHSV of about 1.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst; and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b. to obtain a desulfurized gas-oil eliluent; and separating said desulfurized gas-oil effluent into a hydrogen-containing gas and a desulfurized gas oil.

The catalyst that is employed in the gas-oil-hydrodesulfurization zone of the process of the present invention may be any suitable hydrodesulfurization catalyst, e.g., such as those described hereinabove for the catalyst employed in the naphtha-hydrodesulfurization zone of the process of the present invention. Preferably, the hydrogenation component comprises one or more members of the group consisting of nickel and molybdenum, cobalt and molybdenum, nickel and tungsten, their oxides, their sulfides, and mixtures thereof. After extended periods of use, the catalyst employed in the gas-oil-hydrodesulfurization zone may be regenerated, as is done for the catalyst in the naphtha-hydrodesulfurization zone.

The hydrogen-rich gas obtained from the gas-oil-hydrodesulfurization zone of the process of the present invention is sent to the heavy-distillate-hydrodesulfurization zone of the process. However, it should be treated to remove therefrom the hydrogen sulfide contained therein. 'Ihis may be suitably done by passing the gas through an amine scrubber and a gas washer or any other means of hydrogen sulfide removal known to those having ordinary skill in the art.

ln the heavy-distillate-hydrodesulfurization zone of the process of the present invention, the process comprises mixing a heavy distillate, such as a lubricating oil base stock, with the hydrogen-rich gas stream obtained from the `gas-oil-hydrodesulfurization zone to obtain a mixture of said heavy distillate and said hydrogen-rich gas; contacting said mixture in said heavy-distillate-hydrodesulfurization zone with a suitable hydrodesulfurization catalyst at a temperature of about 600 F. to about 800 F.; a hydrogen partial pressure of about 500 p.s.i.a. to about 1,500 p.s.i.a.; a LHSV of about 0.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst; and a hydrogen-to-hydrocarbon ratio of about 500 s.c.f.b. to about 2,000 s.c.f.b. to obtain a desulfurized heavy-distillate effluent; and separating said desulfurized heavy-distillate efiiuent into a hydrogen-containing gas and a desulfurized heavy distillate. The hydrocarbon feedstock to the heavy-distillate hydrodesulfurization zone may be a dewaxed rafiinate or an unfinished lube oil base stock having a viscosity of 3 to 40 centistokes at 100 C., preferably, 5 to 36 centistrokes at 100 C., and is solvent-extracted to a viscosity index of 80 to 105 and is dewaxed to a pour point of 5 C. to -20 C.

The hydrogen-containing gas from the heavy-distillatehydrodesulfurization zone, which gas contains up to approximately 80% hydrogen, is sent to a hydrogen-sulfide scrubber to remove the hydrogen sulfide therefrom while the desulfurized heavy distillate is sent to storage.

Any suitable hydrodesulfurization catalyst may be employed in the heavy-distillate hydrodesulfurization zone. Typical hydrodesulfurization catalysts such as those described hereinabove, may be employed inthe heavy-distillate hydrodesulfurization zone. A preferred hydrogenating component comprises one or more members selected from the group consisting of cobalt and molybdenum, nickel and molybdenum, nickel and tungsten, their oxides, their sullides, and mixtures thereof. When this catalyst becomes deactivated, it may be regenerated similarly to those in the naphtha-hydrodesulfurization zone and the gas-oil-hydrodesulfurization zone.

The desulfurized heavy distillate is stripped of any remaining hydrogen sulfide and then is dried under a vacu um. The overhead removed from the stripper comprises a small amount of light naphtha.

The reforming zone of the process of the present invention is operated at low pressures and high inlet temperatures for each of the reactors in the zone. It provides improved yields of hydrogen and high-octane blending components. Since the reforming zone need not be shut down for catalyst regeneration, it provides a high-on-stream operating factor. While the bi-metallic catalyst is capable of being poisoned by either nitrogen or sulfur, or the like, it can be reactivated promptly. Such capabilities permit somewhat higher levels of such poisons in the feedstock. Ordinarily, a reforming process employing a catalyst containing a Group VIII noble metal as the hydrogenation component should see feedstocks which contain less than l p.p.m. of sulfur. However, feedstocks having a sulfur level up to about 5 p.p.m. can be tolerated. The reforming zone of the process of the present invention is capable of recovering from a process upset, such as might result from a power failure. In addition, since this reforming zone can be operated at relatively low recycle gas rates, the operating costs related to the movement of gases is reduced.

As pointed out above, the reforming zone of the process of the present invention employs at least three reactors that are connected in series and an alternate or swing reactor. This alternate or swing reactor may be used to replace any of the serially-connected reactors. Such a reforming system is exemplified by the system employed in the Ultraforming process, as presented in U.S. Pat. 2,773,014. The Ultraforming process is described also in Petroleum Engineer, vol. XXVI, No. 4, April 1954, at p. C-35 and in Oil and Gas Journal, Dec. 20, 1971, pp. 58-60.

A preferred embodiment of the combination process of the present invention is described hereinafter and is represented in the accompanying five figures. FIG. 1 presents a very simplified block diagram of the embodiment in toto, while the subsequent figures provide simplified schematic iiow diagrams of each of the processing zones. It is to be understood that such embodiment is for purposes of illustration only and is not intended to limit the scope of the invention. Numerous modifications and equivalents will be apparent to those skilled in the art from the foregoing description as well as from the embodiment presented hereinafter, and such modifications and equivalents are deemed to be within the scope of the present invention.

Referring to FIG. l, a naphtha having the properties shown in Table I is obtained from source 11.

TABLE I.FEEDSTOCK PROPERTIES About 22,500 barrels per stream day (b.p.s.d.) of this naphtha are sent through line 12 to naphtha-hydrodesulfurization zone 13. The naphtha is mixed with a hydrogencontaining gas obtained from line 14 and the mixed hydrogen-hydrocarbon stream is passed into and through naphtha-hydrodesulfurization zone 13. The hydrogen-containing gas contains approximately 70 mol percent whydrogen and is employed at the rate of l6.2 106 standard cubic feet of gas per day (s.c.f.d.). The eliluent obtained from naphtha-hydrodesulfurization zone 13 is separated into a hydrogen-containing gas stream and a liquid product which is fractionated into a light naphtha, a reformer-naphtha charge, and a heavy naphtha. The light naphtha is sent to gasoline-blending facilities by way of line 15; the reformer-naphtha charge, to a subsequent reforming zone by way of line 16; and the heavy naphtha, to jet fuel blending facilities by way of line 17. The hydrogen-containing gas obtained from the naphtha-hydrodesulfurization zione is withdrawn via line 18 in an amount of 13.80. l0 s.c.f.d. This hydrogen-containing gas contains approximately mol percent hydrogen. Approximately 4.97X106 s.c.f.d. of this gas may be sent via line 19 to an off-battery-limits hydrogen-sulfide scrubber to be purified and used subsequently in other processes, if desired. The light naphtha is obtained at a rate of 3,400 b.p.s.d.; the reformer naphtha charge, at a rate of 11,600 b.p.s.d.; and ythe heavy naphtha, at a rate of 8,000 b.p.s.d.

A hydrogen-containing gas obtained from line 20 is added to the reformer naphtha charge and the resulting mixture is sent into regenerative reforming zone 21. The hydrogen-containing gas is added to the reformer-naphtha charge in an amount of 23.2 106 s.c.f.d. 'Ihe reformed eiuent is separated into a hydrogen-containing gas and and a reformate, the hydrogen-containing gas being withdrawn through line 22 and the reformate being sent through line 23 to be used for gasoline blending purposes. The hydrogen-containing gas is withdrawn at the rate of 39.46 106 s.c.f.d., while the reformate is obtained at the rate of 8,600 b.p.s.d. The hydrogen-containing gas in line 22 is divided into two streams. An amount of 23.20 106 s.c.f.d. is sent through line 20 to ibe returned to the reforming zone 21 while 16.26 106 s.c.f.d. is sent through line 14 to be used in the naphtha-hydrodesulfurization zone 13.

A gas-oil fraction having the properties shown in Table I is obtained from source 24 and, at the rate of 11,700 b.p.s.d., is passed through line 25 into gas-oil hydrodesulfurization zone 26. The gas oil is mixed with 8.83 X106 s.c.f.d. of hydrogen-containing gas from line 18. As reported hereinabove, this gas contains approximately 80 mol percent hydrogen. The desulfurized gas-oil etfluent is separated into a hydrogen-containing gas and a desulfurized liquid, which liquid is withdrawn by way of line 27 to be sent to gas-oil storage. This desulfurized gas oil is obtained at the rate of 11,700 b.p.s.d. A stream of approximately 38 b.p.s.d. of light naphtha is withdrawn from gas-oil-hydrodesulfurization zone by way of line 28 to be sent to storage. The hydrogen-containing gas is withdrawn via line 29 at the rate of 6.7 106 s.c.f.d. and is sent through an amine scrubber 30 and line 31 to a heavydistillate-hydrodesulfurization zone 32. The hydrogen-containing gas contains 83 mol percent hydrogen. Approximately 0.7 106 s.c.f.d. of sour gas is withdrawn from gas-oil-hydrodesulfurization zone 26 via line 33 to be sent to an ot-battery-limits hydrogen-sulfide scrubber. This sour gas contains approximately mol percent hydrogen.

A lubricating oil base stock, a heavy distillate, is obtained from source 34 and is sent via line 35 to heavydistillate-hydrodesulfurization zone 32. This heavy distillate having the properties listed in Table II hereinbelow is employed in an amount of 5,715 ib.p.s.d. It is mixed with the hydrogen-containing gas from line 31 and is desulfurized in heavy-distillate-hydrodesulfurization zone 32.

TABLE II Properties of heavy distillate Feed type SAE 30 Specic gravity at 68 F. 0.883 Kinematie viscosities, centistokes:

100 F. 98.6-128 v 212 F. 10-12 Viscosity index (ASTM D2270-64) 95 Pour point, F. (ASTM D97-66) 'rl-14 Maximum color (ASTM D1500-64) 3.5 Flash point, F., min. (PN 65/C-04008) 446 Oxidation viscosity, ratio max. (IP 48/ 62) 1.5

Desulfurized heavy-distillate etliuent is obtained from heavy-distillate-hydrodesulfurization zone 32 in an amount of about 5,705 b.p.s.d. and is sent by way of line 36 to storage. The hydrogen-containing gas that is separated from this heavy-distillate product is sent to an off-batterylimits hydrogen-sulfide scrubber by way of line 37. This gas, containing approximately 80 mol percent hydrogen, is obtained at the rate of 5.88 106 s.c.f.d.

The naphtha-hydrodesulfurization zone of the integrated process of the present invention is represented diagrammatically in the simplified schematic flow diagram presented in FIG. 2. A naphtha having the properties shown hereinabove in Table I is obtained from source 38 and is employed at the rate of 22,500 b.p.s.d. This naphtha is passed through line 39 and is joined by a hydrogen-rich gas being introduced into line 39 by way of line 40.

The hydrogen-rich gas, being employed at the rate of 16.26 l06 s.c.f.d. and containing approximately 70 mol percent hydrogen, is mixed with the naphtha in line 39 and the resulting mixture is then passed through line 39 to furnace 41 to be heated to a temperature of approximately 650 F. The heated mixture is then passed through line 42 into the top of reactor 43. IReactor 43 is operated at a pressure of approximately 325 p.s.i.g. and contains 37,200 pounds of a desulfurization catalyst comprising cobalt and molybdenum, their oxides, and their suliides on a support of catalytically active alumina. The catalyst contains about 2 weight percent to about 5 Weight percent cobalt, calculated as CoO, and about 10 weight percent to about 20 Weight percent molybdenum, calculated as M003. The desulfurized naphtha is withdrawn from reactor 43 through line 44 to be cooled by cooling means 45.

The cooled efiiuent is then passed through line 46 into high-pressure separator 47, which is operated at a pressure of approximately 270 p;s.i.g. and a temperature of approximately 100 F. A hydrogen-rich gas, containing approximately mol percent hydrogen, is separated from the cooled eluent and is withdrawn through line 48 at the rate of approximately l3.80 166 s.c.f.d., to be sent to a gas-oil-hydrodesulfurization zone.

The liquid eluent is withdrawn from high-pressure separator 47 through line 49, to be sent to a low-pressure separator 50. Low-pressure separator 50 is operated at a pressure of p.s.i.g. and a temperature of 100 F. Approximately 13,050 standard cubic feet of gas per hour are separated in this low-pressure separator and are withdrawn through line 51, to be sent to a hydrogen-sulde scrubber. The liquid efliuent from low-pressure separator 50 is sent through line 52 to naphtha debutanizer 53. From naphtha debutanizer 53, the light gases are withdrawn via line 54, to be sent to a hydrogen-sulfide scrubber.

The debutanized naphtha is Withdrawn via line 55 and is sent to prefractionator 56 where it is separated into a light naphtha fraction, a reformer-naphtha charge, and a heafvy naphtha fraction. Approximately 3,400 b.p.s.d. of light naphtha are Withdrawn through line 57; 11,600 b.p.s.d. of reformer-naphtha charge are Withdrawn through stripper 58 and line 59, to be sent to a regenerative reforming zone; and 8,000 b.p.s.d. of heavy naphtha are Withdrawn through line 60. Both the light naphtha and the heavy naphtha are sent outside the battery limits for use in other processes.

The naphtha reforming stage of the integrated process of the present invention is represented diagrammatically in the simplified ilow diagram presented in FIG. 3.

Referring to FIG. 3, the reformer naphtha charge is passed through line 59. A hydrogen-rich gas is introduced into line 59 by way of line 61 at a rate of 232x106 s.c.f.d. The hydrogen-rich gas and the naphtha are thoroughly mixed in line 59 and the mixture is sent to furnace 62. The heated mixture is passed through lines 63 and 64 and valve 65 to the top of reactor 66. Valve 67 in line 64 and valve 68 in connecting line 69 are closed. The inlet temperature of reactor 66 is at least 970 F. and the pressure is p.s.i.g. The reactor contains 6,200 pounds of a reforming catalyst, Which catalyst comprises 0.3 weight percent platinum, 0.3 weight percent rhenium, and `0.8 weight percent combined chlorine on a catalytically active alumina.

The effluent from reactor 66 is passed through line 70, valve 71, and line 72 to furnace 73. Valve 74 in line 70 and valve 75 in connecting line 76 are closed. The material heated in furnace 73 is passed through line 77, line 78, and valve 79 to the top of reactor 80. Valve 81 in line 78 and valve 82 in connecting line 83 are closed. The inlet temperature to reactor 80 is at least 985 F. Reactor 80 contains 10,400 pounds of catalyst, which is the same type of catalyst as that described for reactor 66. The efuent from reactor 80 is passed through line 13 84, valve 85, and line 86 to furnace 87. Valve 88 in line 84 and valve 89 in connecting line 90 are closed.

The material heated in furnace 87 is passedy through line 91, line 92, and valve 93 to the top of reactor 94. Valve 95 in line 92 and valve 96 in connecting line 97 are closed. The inlet temperature of reactor 94 is at least 985 F. Reactor 94 contains 10,400 pounds of reforming catalyst, which is the same type of catalyst as that described in reactors 66 and 80.

The e'iuent from reactor 94 is passed through line 98, valve 99, and line 100 to furnace 101. Valve 102 in line 98 and valve 103 iu connecting line 104 are closed. The heated stream is then passed through line 105, line 106, and valve 107 to the top of reactor 108. Valve 109 in line 106 and valve 110 in connecting line 111 are closed. The inlet temperature of reactor 108 is at least 985 F. Reactor 108 contains 10,400 pounds of reforming catalyst, which is the same type of catalyst as that described in reactors 66, 80, and 94. The exit temperature of reactor 108 is about 965 F. and the exit pressure is approximately 130 p.s.i.g. The efliuent from reactor 108 passes through line 112 to separator 113. Valve 114 in connecting line 115 and valve 116 in connecting line 117 are closed.

In separator 113, a hydrogen-containing gas is separated from the liquid products. 'I'he temperature in separator 113 is 100 F. and the pressure is 90 p.s.i.g. The hydrogen-containing gas is withdrawn from separator 113 by way of line 118 to be sent to recontactor 119. The liquid product removed in separator 113 passes via line 120 to line 118, where it contacts and mixes with the hydrogen-containing gas in line 118. The resulting mixture passes from line 118 into recontactor 119, which is operated at a pressure of about 375 p.s.i.g. and a temperature of 100 F. In recontactor 119, liquid is again separated from hydrogen-containing gas. The hydrogen-containing gas is withdrawn from( recontactor 119 by way of line 121 to be sent to either line 61, where it is employed as the hydrogen-containing gas that is mixed with the reformer naphtha charge to be reformed, or to line 40, where it is sent to the associated naphtha-hydrodesulfurization zone. The liquid product removed in recontactor 119 passes Ivia line 122 to the reformate debutanizer 123. The C3 and C., components are separated from the liquid euent in reformate debutanizer 123 and are withdrawn by way of line 124. The debutanized reformate is withdrawn from debutanizer 123 by way of line 125 and sent to gasoline blending facilities.

The reformate is obtained at the rate of 8,600 b.p.s.d. The hydrogen-containing gas obtained from recontactor 119 and passed via line 121 is produced at the rate of 39.46Xl06 s.c.f.d. As reported hereinabove, this hydro- -gen-containing gas passing through line 121 is divided into two streams. One of these streams passes through line 61 at the rate of 23.2.)(10e s.c.f.d., while the other stream! passes through line 40 to the naphtha-hydrodesulfurization zone at the rate of 16.26 106 s.c.f.d. and, as reported above, is made up of approximately 70 mol percent hydrogen.

The reforming zone of the combination process of the present invention employs a regenerative reforming process, sometimes referred to as cyclic reforming process. This type of refonming process reforms petroleum hydrocarbons continuously. This continuous reforming is accomplished by employing an additional reactor as a swing reactor. This additional reactor is identified in FIG. 3 as reactor 126 and contains 10,400 pounds of catalyst, which is the same type of catalyst as that described for the previous reactors. Swing reactor 126 may be used to replace any of the other four reactors described hereinabove, reactors 66, 80, 94, and 108, by operating the appropriate valves. The reactor to be replaced can be removed from the reforming system and replaced by swing reactor 126. The catalyst that is in the reactor 14 that is removed from the reforming system is then regenerated. A regeneration system, such as that described in U.S. Pat. 2,773,014, can be used to -supply the oxygencontaining gas needed for the regeneration. This regeneration system will not be described herein but will be identified only as regeneration system 127.

If the catalyst in reactor 66 were to a regenerated, reactor 66 would be removed from the reforming system by closing valves 65 and 71. Valves 67, 68, 74, 75, 131, and 134 would be opened. Regeneration gas would be furnished from regeneration system 127 by way of lines 128 and 76 through valve 75 into line 70. The gas would pass upwardly through the catalyst in reactor 66 to line 64. Since valve 65 would be closed, the line gas being emitted from reactor 66 through line 64 would pass through line 69, valve 68, and line 128a, to be returned to regeneration system 127. Since the valves 129, 89, 103, 116, 82, 96, and 136, which are in lines 130, 90, 104, 117, 83, 97, 111, and 135, respectively, are closed, the regeneration gas circulates from the regeneration system 127 through the reactor 66 and back to the regeneration system.

Each of the reactors described hereinabove must be removed periodically from the reforming system so that the catalyst contained therein may be regenerated. How often the catalyst in each reactor must be regenerated is determined by the severity of operation and the type of naphtha that is being employed is the process of this invention. For this particular embodiment, one reactor is removed every 24 hours from the system and the catalyst in that reactor is regenerated.

Referring to FIG. 4, which diagrammatically depicts the gas-oil-hydrodesulfurization zone of the combination process of the present invention, gas oil is obtained from source 137 at the rate of 11,700 b.p.s.d. The properties of this gas oil are presented in Table I hereinabove. Gas oil is charged by way of line 138 to furnace 139. Gas oil is sent through line 138, to be joined by hydrogen-containing gas from line 48. As reported hereinabove, the hydrogen-rich gas from line 48 contains approximately 80 mol percent hydrogen and is used at the rate of 8.83 X 106 s.c.f.d. This hydrogen-rich gas is obtained from the naphtha-hydrodesulfurization zone described hereinabove.

The hydrogen-rich gas and the gas oil are mixed in line 138, and the resulting mixture is heated in furnace 139. The heated mixture is then passed by way of line 140 to the top of reactor 141. Reactor 141 contains 57,620 pounds of a second desulfurization catalyst comprising cobalt and molybdenum, their oxides, and their sulfides supported on a catalytically active alumina. Generally, the catalyst contains about 2 weight percent to about 5 weight percent cobalt, calculated as CoO and based on the weight of the catalyst, and about 10 weight percent to about 20 weight percent molybdenum, calculated as M003 and based on the weight of the catalyst. The reactor is operated at a hydrogen partial pressure of about 100 p.s.i.a. to about 375 p.s.i.a., an average catalyst temperature of about 600 F. to about 725 F., a LHSV of about 0.5 t0 about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.

The eiiuent from reactor 141 is passed through line 142, cooler 143, and line 144 to high-pressure separator 145. High-pressure separator 145 is operated at a temperature of 100 F. and a pressure of 370 p.s.i.g. Hydrogenrich gas is iiashed off from high-pressure separator 145 and sent by way of line 146 to the heavy-distillate-hydrodesulfurization zone described hereinbelow. Approximately 6.7 106 s.c.f.d. is sent through line 146. This gas contains about 83 mol percent hydrogen.

The liquid stream removed from high-pressure separator 145 is passed through line 147 to product stripper 148, where a light naphtha and a hydrogen-sulfide-containing vapor are stripped therefrom. A vapor stream containing hydrogen sulfide is withdrawn from the stripper 148 at line 149 at the rate of 0.7 106 s.c.f.d. This hydrogen-sultide-containing vapor may be sent to a hydrogen-sulfide scrubber (not shown). Liquid light naphtha is removed from stripper 148 by way of line 150 at the rate of about 38 b.p.s.d. and is sent to olf-site storage. The bottoms product from stripper 148 is the desulfurized gas oil and is withdrawn by way of line 151 and cooled by cooler 152. The desulfurized gas oil is produced at the rate of approximately 11,700 b.p.s.d. and is sent t storage by way of line 153.

FIG. presents diagrammatically the heavy-distillatehydrodesulfurization zone of this embodiment of the process of the present invention. Typically, the heavy distillates that are contemplated for hydrodesulfurization in this stage of the process of the present invention may be dewaxed rainates or unfinished lubricating oil base stocks having a viscosity of about 3 to about 40 centistokes or greater, at 100 C. and being solvent extracted to a viscosity index of about 80 to 105 and dewaxed to a pour point of 5 C. to 20 C. For the purpose of this embodiment, the heavy distillate being hydrodesulfurized is a lubricating oil base stock having the properties shown in Table II hereinabove. This hydrocarbon stream is obtained from source 154 and is passed through line 155 at the rate of 5,715 b.p.s.d. Hydrogen-rich gas is obtained from the gas-oil hydrodesulfurization zone described hereinabove by way of line 146. This hydrogen-rich gas is employed at the rate of 6.7 G s.c.f.d. It is sent to amine scrubber 156. Hydrogen sulfide is removed in amine scrubber 156 and an accompanying gas washer, which is not shown in this diagram. The purified hydrogen-rich gas is then sent by way of line 157 to line 155, where it is mixed with the heavy distillate stream. The mixture of heavy distillate and hydrogen-rich gas is then sent by way of line 155 through furnace 158 and line 159 to the top of reactor 160.

The reactor 160 contains 52,310 pounds of catalyst comprising cobalt and molybdenum, their oxides, and their suldes on a catalytically active alumina. Generally, the catalyst contains about 2 weight percent to about 5 weight percent cobalt, calculated as CoO and based on the weight of the catalyst, and about 10 weight percent to about 20 weight percent molybdenum, calculated as M003 and based on the weight of the catalyst. Reactor 160 is operated at a hydrogen partial pressure of about 500 p.s.i.a. to about 1,500 p.s.i.a., an average catalyst temperature of about 600 F. to about 800 F., a LHSV of about 0.5 to about l0 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 1,000 s.c.f.b. to about 5,000 s.c.f.b.

The eluent from reactor 160 is passed by way of line 161 through cooler 162 and line 163 to separator 164. The gas that is separated from the effluent in separator 164 is passed by way of line 165 to an off-site hydrogensulfide scrubber, since this gas contains hydrogen sulfide. This gas contains about 80 mol percent hydrogen and is produced at the rate of 5.88 l06 s.c.f.d. The separator is operated at a temperature of 100 F. and a pressure of 750 p.s.i.g.

The liquid product is removed from separator 164 by way of line 166 and is sent to stripper 167. Steam from line 168 is heated in furnace 158 and is sent by way of line 169 to stripper 167. Any remaining hydrogen sulfide is stripped from the liquid product in stripper 167 andiis removed by way of line 170. The liquid product is withdrawn from stripper 167 by way of line 171 and is sent to a vacuum dryer followed by a cooler (not shown in FIG. 5). rIhe hydrodesulfurized heavy distillate is 0btained at a rate of 5,705 b.p.s.d.

This embodiment of the process of the present invention provides high yields of gasoline blending components and maximum utilization of the high-purity hydrogen produced by the reforming zone of the process.

What is claimed is:

1. A petroleum hydrocarbon conversion process for the hydrodesulfurization of a naphtha in a naphtha-hydrodesulfurization zone, the hydrodesulfurization of a gas oil in a gas-oil-hydrodesulfurization zone and the hydrodesulfurization of a heavy distillate in a heavy-distillate hydrodesulfurization zone to provide a desulfurized naphtha, a desulfurized gas oil, and a desulfurized heavy distillate, respectively, and for the regenerative reforming of said desulfurized naphtha in a regenerative reforming zone to provide increased amounts of hydrogen and gasoline blending components, which process comprises: contacting in said reforming zone said desulfurized naphtha in the presence of a hydrogen-containing reactant -gas with a reforming catalyst comprising a Group VIII noble metal, a small amount of a metal promoter, and a combined halogen on a catalytically active alumina ata pressure of about 50 p.s.i.g. to about 250 p.s.i.g. and an inlet temperature of at least 970 F. to provide a reformed efuent containing said increased amounts of hydrogen and gasoline blending components; separating said reformed effluent into a first hydrogen-containing product gas and said gasoline blending components; dividing said first hydrogencontaining product gas into a first hydrogen-containing gas and a second hydrogen-containing gas; .sending said rst hydrogen-containing gas to said reforming zone to be used as said hydrogen-containing reactant gas; sending said second hydrogen-containing gas to said naphtha-hydrodesulfurization zone to be mixed with said naphtha and contacted in said naphtha-hydrodesulfurization Zone with a first hydrodesulfurization catalyst to provide a desulfurized naphtha effluent, -said desulfurized naphtha eflluent being separated into said desulfurized naphtha to be sent to said reforming zone and a second hydrogen-containing product gas; sending said second hydrogen-containing product gas to said gas-oil-hydrodesulfurization zone to be mixed with said gas oil and contacted in -said gas-oilhydrodesulfurization Zone with a second hydrodesulfurization catalyst to provide a desulfurized gas-oil effluent, said desulfurized gas-oil effluent being separated into said desulfurized gas oil and a third hydrogen-containing product gas', sending said third hydrogen-containing product gas to said heavy-distillate-hydrodesulfurization zone to be mixed with said heavy distillate and contacted in said heavy-distillate-hydrodesulfurization zone with a third hydrodesulfurization catalyst to provide a desulfurized heavy-distillate effluent, said desulfurized heavy-distillate efuent being separated into said desulfurized heavy vdistillate and a fourth hydrogen-containing product gas, said first hydrodesulfurization catalyst, said second hydrodesulfurization catalyst, and said third hydrodesulfurization catalyst each comprising a hydrogenation component on a refractory inorganic oxide support.

2. The petroleum hydrocarbon conversion process of claim 1 wherein said metal promoter of said reforming catalyst is rhenium.

3. The petroleum hydrocarbon conversion process of claim 1 wherein said regenerative reforming of said desulfurized naphtha comprises contacting a mixture of said desulfurized naphtha and said hydrogen-containing reactant gas in the first reaction zone of a plurality of reaction zones with said reforming catalyst to produce a first reformate, said first reaction zone having an inlet temperature of at least 970 F.; contacting said first reformate with said reforming catalyst in at least one intermediate reaction zone having an inlet temperature of at least 985 F. to obtain an intermediate reformate; and contacting said intermediate reform-ate With reforming catalyst in a nal reaction zone having an inlet temperature of at least 985 F. to obtain a final reformate; said process being operated under the addition-al reforming conditions comprising a hydrogen-containing recycle gas rate of about 1,000 s.c.f.b. to about 5,000 s.c.f.b. and a WHSV of about 2 to about 10 weight units of hydrocarbon per hour per weight unit of catalyst; and each of said reaction zones being replaclzelY individu-ally and peri.

odically by an alternate reaction zone in order that said reforming process can be operated continuously while the catalyst in the replaced reaction zone is being regenerated by burning carbonaceous deposits therefrom with an oxygen-containing gas; said process producing a gasoline blending stock having an unleaded research octane number within the range of about 96 to about 106.

4. The hydrocarbon conversion process of claim 1 wherein said first hydrodesulfurization catalyst, said second hydrodesulfurization catalyst, and said third hydrodesulfurization catalyst each comprises one or more members selected from the group consisting of a Group VI metal, a Group VIII metal, their oxides, their suldes, and mixtures thereof deposited upon a catalytically active alumina.

5. The hydrocarbon conversion process of claim 1 wherein the operating conditions employed in said naptha-hydrodesulfurization zone comprise a temperature of about 500 F. to about 725 F., a hydrogen partial pressure of about 75 p.s.i.a to about 400 p.s.i.a., a LHSV of about 2 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; the operating conditions employed in said gasoil-hydrodesulfurization zone comprise a temperature of about 600 F. to about 725 F., a hydrogen partial pressure of about 100 p.s.i.a to about 375 p.s.i.a., a LHSV of about 1.5 to about volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; and the operating conditions employed in said heavy-distillate hydrodesulfurization zone comprise a temperature of about 600 F. to about 800 F., a hydrogen partial pressure of about 500 p.s.i.a. to about 1,500 p.s.i.a., a LHSV of about 0.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and Ia hydrogen-to-hydracarbon ratio of about 500 s.c.f.b. to about 2,000 s.c.f.b.

6. The hydrocarbon conversion process of claim 2 wherein said reforming catalyst comprises 0.01 Weight percent to about 2 weight percent platinum, 0.05 weight percent to about 2.5 weight percent rhenium, and 0.01 weight percent to about 2.0 weight percent halogen, each value being based upon the total weight of said reforming catalyst and said halogen preferably being chlorine.

7. The petroleum hydrocarbon conversion process of claim 3 wherein said metal promoter of said reforming catalyst is rhenium,

8. The hydrocarbon conversion process of claim 4 wherein the operating conditions employed in said naphtha hydrodesulfurization zone comprise a temperature of about 500 F. to about 725 F., a hydrogen partial pressure of about 75 p.s.i.a. to about 400 p.s.i.a., a LHSV of about 2 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; the operating conditions employed in said gasoil-hydrodesulfurization zone comprise a temperature of about 600 F. to about 725 F., a hydrogen partial pressure of about 100 p.s.i.a. to about 375 p.s.i.a., a LHSV of about 1.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; and the operating conditions employed in said heavydistillate-hydrodesulfurization zone comprise a temperature of about `600 F. to about 800 F., a hydrogen partial pressure of about 500 p.s.i.a. to about 1,500 p.s.i.a., a LHSV of about 0.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 500 s.c.f.b. to about 2,000 s.c.f.b.

9. The hydrocarbon conversion process of claim 6 wherein said first hydrodesulfurization catalyst, said second hydrodesulfurization catalyst, and said third hydrodesulfurization catalyst each comprises one or more members selected from the group consisting of a Group VI 18 metal, Ia Group VIII metal, their oxides, their suliides, and mixtures thereof deposited upon a catalytically active alumina.

10. The petroleum hydrocarbon conversion process of claim 6 wherein said regenerative reforming of said desulfurized naphtha comprises contacting a mixture of `said desulfurized naphtha and said hydrogen-containing reactant gas in the rst reaction zone of a plurality of reaction zones with said reforming catalyst to produce a first reformate, said rst reaction zone having an inlet temperature of at least 970 F.; contacting said first reformate with said reforming catalyst in at least one intermediate reaction zone having an inlet temperature of at least 985 F. to obtain an intermediate reformate; and contacting said intermediate reformate with reforming catalyst in a final reaction zone having an inlet ternperature of at least 985 F. to obtain a final reformate; said process being operated under the additional reforming conditions comprising a hydrogen-containing recycle gas rate of about 1,000 s.c.f.b. to about 5,000 s.c.f.b. and a WHSV of about 2 to about 10 weight units of hydrocarbon per hour per weight unit of catalyst; and each of said reaction zones being replaced individually and periodically by an alternate reaction zone in order that said reforming process can be operated continuously while the catalyst in the replaced reaction zone is being regenerated by burning carbonaceous deposits therefrom with an oxygen-containing gas; said process producing a gasoline blending stock having an unleaded research octane number within the range of about 96 to about 106.

11` The hydrocarbon conversion process of claim 6 wherein the operating conditions employed in said naphtha-hydrodesulfurization zone comprise a temperature of about 500 F. to about 725 F., a hydrogen partial pressure of about 75 p.s.i.a. to about 400 p.s.i.a., a LHSV of about 2 to about 1'0 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; the operating conditions employed in said gasoil-hydrodesulfurization zone comprise a temperature of about 600 F. to about 725 F., a hydrogen partial pressure of about 100 p.s.i.a. to about 375 p.s.i.a., a LHSV of about 1.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; and the operating conditions employed in said heavy-distillate hydrodesulfurization zone comprise a temperature of about 600 F. to about 800 F., a hydrogen partial pressure of about 500 p.s.i.a. to about 1,500 p.s.i.a., a LHSV of about 0.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 500 s.c.f.b. to about 2,000 s.c.f.b.

12. The hydrocarbon conversion process of claim 9 wherein the operating conditions employed in said naphtha-hydrodesulfurization zone comprise a temperature of about 500 F. to about 725 F., a hydrogen partial pressure of about 75 p.s.i.a. to about 400 p.s.i.a., a LHSV of about 2 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; the operating conditions employed in said gas-oil-hydrodesulfurization zone comprise a temperature of about 600 F. to about 725 F., a hydrogen partial pressure of about 100 p.s.i.a. to about 375 p.s.i.a., a LHSV of about 1.5 t0 about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 300 s.c.f.b. to about 1,000 s.c.f.b.; and the operating conditions employed in said heavy-distillate hydrodesulfurization zone comprise a temperature of about 600 F. to about 800 F., a hydrogen partial pressure of about 500 p.s.i.a to about 1,500 p.s.i.a., a LHSV of about 0.5 to about 10 volumes of hydrocarbon per hour per volume of catalyst, and a hydrogen-to-hydrocarbon ratio of about 500 s.c.f.b. to about 2,000 s.c.f.b.

13. The petroleum hydrocarbon conversion process of claim 9 wherein said regenerative reforming of said desulfurized naphtha comprises contacting a mixture of said desulfurized naphtha and said hydrogen-containing reactant gas in the first reaction zone of a plurality of reaction zones with said reforming catalyst to produce a first reformate, said first reaction zone having an inlet temperature of at least 970 F.; contacting said first reformate with said reforming catalyst in at least one intermediate reaction zone having an inlet temperature of at least 985 F. to obtain an intermediate reformate; and contacting said intermediate reformate with reforming catalyst in a final reaction zone having an inlet temperature of at least 985 F. to obtain a final reformate; said process being operated under the additional reforming conditions comprising a hydrogen-containing recycle gas rate of about 1,000 `s.c.f.b. to about 5,000 s.c.f.b. and a WHSV of about 2 to about 10 weight units of hydrocarbon per hour per weight unit of catalyst; and each of said` reaction zones being replaced individually and periodically by an alternate reaction zone in order that said reforming process can be operated continuously while the catalyst in the replaced reaction zone is being regenerated by burning carbonaceous deposits therefrom with an oxygencontaining gas; said process producing a gasoline blending stock having an unleaded research octane number within the range of about 96 to about 106.

14. The petroleum hydrocarbon conversion process of said intermediate reformate with reforming catalyst in a final reaction zone having an inlet temperature of at least 985 F. to obtain a final'reformate. said process being operated under the additional reforming conditions cornprising a hydrogen-containing recycle gas rate of about 1,000 s.c.f.b. to about 5,000 s.c.f.b. and a WHSV of about 2 to about 10 weight units of hydrocarbon per hour per Weight unit of catalyst; and each of said reaction zones being replaced individually and periodically by an alternate reaction zone in order that said reforming process can be operated continuously while the catalyst in the replaced reaction zone is being regenerated by burning carbonaceous deposits therefrom with an oxygen-containing gas; said process producing a gasoline blending stock having an unleaded research octane number within the range of about 96 to about 106.

References Cited UNITED STATES PATENTS 3,415,737 12/1968 Kluksdahl 208-139 3,431,195 3/ 1969 Storch et al 208-101 3,434,960 3/1969 Jacobson et al 208-136 3,444,072 5 1969 Lehman 208-102 3,520,800 7/1970 Forbes 208-101 3,691,059 7/ 1972 Hallman 208-80 3,706,655 12/1972 Weith 208-82 3,706,656 12/1972 Weith 20S-82 2,800,428 7/ 1957 Hengstebeck 208-65 2,834,718 5/1958 Stanford et al. 20S-89 3,066,093 11/1962 Ruef et al 208-212 3,317,419 2/1967 Portman 208-97 DELBERT E. GANTZ, Primary Examiner o G. E. SCHMITKONS, Assistant Examiner U.S. Cl.' X.R.

DATED Column [SEAL] PATENT NO,

|N\/ENTOR(S) i 3,80l,t9r

April 2,197@

Moore, Thomas M.,

et al It is certified that error appears in the above-identified patent and that said Letters Patent lr, llt,

line 2,

are hereby corrected as shown below:

"meal" should be metal "X 166" Should be X 1o6 "reformate." should be reformate;

Signed and Sealed this second Day Of September 1975 A nest:

RUTH C. MASON Alieni/1g Off/'Cer C. MARSHALL DANN (Vmzmissimrcr trl/'Patellis and Trademarks

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