US3583902A - Two-stage conversion process - Google Patents

Abstract

HIGH PRESSURE TO HYDROCRACKING IN THE PRESENCE OF HYDROGEN AND A CATALYST, TO PRODUCE A HYDROCRACKED PRODUCT AND THEN SUBJECTING THE HYDROCRACKED PLRODUCT TO HYDRODESULFURIZATION AT A HIGH TEMPERATURE AND HIGH PRESSURE IN THE PRESENCE OF HYDROGEN AND A HIGHLY ACTIVE CATALYST AND RECOVERING THE PRODUCTS THUS PRODUCED.

THIS INVENTION RELATES TO A TWO-STAGE PROCESS FOR TREATING A PETROLEUM MATERIAL CONTAINING A RESIDUUM FRACTION IN ORDER TO REMOVE SULFUR AND METAL COMPOUNDS CONTAINED THEREIN AND TO PRODUCE A NAPHTHA FRACTION SUITABLE FOR USE AS AN ETHYLENE CHARGE STOCK, A LOW SULFUR CONTENT FURNACE OIL AND A LOW SULFUR CONTENT FUEL OIL COMPRISING SUBJECTING SAID PETROLEUM MATERIAL AT A HIGH TEMPERATURE AND

Description

June s, 1911 Filed May 6,

Hydrogen-rich Recycle Gas l 4 Recyle Gas v J4 Compressor TWO-'STAGE CONVERS ION PROCESS 2 Sheets-Sheet l INVI'INTORS HARRY E. JACOBS GEURGE P. MASULUGTES PAUL. J. WHITE ATTORNEY June 8, 197iv G. P. MAsoLoGn-Es ETAL 3,583,902.

Two-STAGE CONVERSION PRocEss Filed May 6, 1969 f2 sheets-sheet 2 United States Patent O U.S. Cl. 208-59 9 Claims ABSTRACT OF .THE DSCLOSUR This invention relates to a two-stage process for treating a petroleum material containing a residuum fraction in order to re'move sulfur and metal compounds contained therein and to produce a naphtha fraction suitable for use as an ethylene charge stock, a low sulfur content furnace oil and a low sulfur content fuel oil comprising subjecting said petroleum material ata high temperature and high pressure to hydrocracking in the presence of hydrogen and a catalyst, to produce a hydrocracked product and then subjecting the hydrocracked product to hydrodesulfurization at a high temperature and high pressure in the presence of hydrogen and a highly active catalyst and recovering the products thus produced.

RELATED APPLICATION This application is a continuation-in-part of our earlier filed application, Ser. lNo. 633,453 for Two-Stage Conversion Process, tiled Apr. 25, 1967, now abandoned.

BACKGROUND OF INVENTION This invention relates to the treatment of petroleum materials containing residuum fractions. Particularly, this invention relates to a two-stage process for the treatment of said petroleum materials containing appreciable quantities of sulfur, nitrogen and metal containing compounds. More particularly, this invention relates to a twostage process for-the treatment of said. petroleum materials in order to produce more valuable products, such as naphtha suitable for use as an ethylene charge stock, and low sulfur content furnace oiland heavy fuel oil. The naphtha produced in the method of our invention has the desirable features of an ethylene charge stock in that it will approximate a virgin naphtha from the standpoint of cyclic content and low isoto normal ratio of parains. Further, the furnace oil and the heavy fuel oil each has a sulfur content less than 0.5 weight percent.

It has been known for sometime that petroleum materials containing residuum fractions contain significant quantities of metallic impurities, e.g., vanadium, nickel, sodium, iron, copper and zinc. These impurities may be in the form of insoluble compounds suspended in the oil or oil-soluble metallo-organic compounds. When petroleum materials containing residuum fractions are subjected to desulfurization, metallo-organic compounds present in such fractions tend to form a layer or ash on the surfaces of the catalyst, thus blocking or otherwise adversely affecting the activity of the catalyst and often permanently poisoning it in terms of both activity and selectivity. This is quite different from the ordinary inactivation of the catalyst by coke formation which is alleviated by regeneration, e.g., burning off of the carbonaceous deposits formed during the reaction. While metallic impurities present in such fractions in the formof suspended solid particles may be removed by relatively simple physical means like filtration, oil-soluble metallo-organic compounds present a more difficult problem of elimination.

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Accordingly, the art has necessarily relied upon various systems involving extensive replacement of the catalyst. Replacement of the catalyst, however, necessitates interruption of the catalytic conversion operations or, as is more frequently the case, the provision of duplicate reactors. In any event, costs associated with replacement of the catalyst have lmade it virtually impractical to refine petroleum materials containing residuum fractions of high metal content. lFurther, these metals, and in particular vanadium, are undesirable in residual petroleum fractions because of the corrosion and pitting of metals resulting from combustion of such residual fuels.

With the increasing use of crude oils obtained from foreign sources such as the Middle East and South America, the presence of the metallic impurities in the crudes hast become a considerable problem. The amounts of such metals in domestic sources of crude oil such as Mid-Continent and East Texas crudes, are so small as to present no problem in the refining of the crudes and in the use of the petroleum fractions obtained from such crudes. For example, with two Texas crudes containing only 0.1 part per million of vanadium and 2 and 4 p.p.m. of nickel, the crudes can be processed satisfactorily in hydrogenation systems and their fractions employed in the usual way. On the other hand with a Kuwait crude containing 78 p.p.m. of vanadium and 28 p.p.m. of nickel in the long residuum, the problem does exist; while with Venezuelan crudes which contain 200 to 1000i ppm. or more of vanadium and up to p.p.m. of nickel in the long residuum, the problem is serious. -Briefly stated, the

oils with which this invention is concerned are those' which contain suicient amounts of heavy metals so as to cause catalyst contamination problems in desulfurization processes and/or corrosion problems in the use as fuel. AIt is desirable to reduce the metals content to less than 100 p.p.m. and preferably below 20 p.p.m.

It is also known in the petroleum refining art that the presence of sulfur is objectionable in furnace oils and heavy fuel oils. High sulfur content in such oils contributes significantly to air pollution problems.

SUMMA-RY OF INVENTION This invention is concerned with petroleum materials containing residuum fractions such as total crude as well as topped or reduced crude. These terms may be defined as follows:

Total crude is defined as a naturally occurring petroleum oil containing residuum fractions which has not been processed in any manner, but preferably separated from water and sediment and desalted.

Topped or reduced crude is defined as the residuum petroleum fraction resulting from removal of all or some of those straight run fractions such as gas, gasoline, kerosine, naphtha, furnace oil, gas oil, etc., which are normally removed from the above defined total crude by the process of atmospheric and/or vacuum topping or distillation. Our invention is, however, particularly suitable for the treatment of reduced crudes.

It will be understood, however, to those skilled in the art that the method of our invention will also be suitable for treating petroleum like materials obtained from shale oil, tar sands and coal, said petroleum like materials having properties which are comparable to petroleum materials containing residuum fractions as hereinabove defined.

In accordance with our invention, a petroleum material containing residuum fractions, hereinafter referred to as charge stream, is subjected to a two-stage treatment. In the first stage ofthe charge stream is subjected to hydrocracking. The total effluent from the hydrocracking stage is then subjected to hydrodesulfurization. In both stages the material treated is maintained largely in the liquid phase. The resulting hydrocracked and hydrodesulfurized material is then fractionated by conventional means to obtain naphtha, heavy fuel oil and furnace oil.

The use of the hydrocracker or the use of the desulfurizer alone cannot adequately treat a petroleum material containing a residuum fraction in order to economically and simultaneously remove sulfur and metal compounds therein and to produce in high yield a naphtha fraction suitable for use as an ethylene charge stream. We have discovered, however, that by combining the two, the first stage does an effective job of demetallizing. Its high thermal severity provides for adequate hydrocracking. The second stage, with its superior catalyst system, not only provides for improved desulfurization but also hydrogenates the unstable components of the effluent from the first stage. Without the demetallization of the first stage, the second stage would be inoperable and further, naphtha yields would be inadequate.

Without the second stage, petroleum materials containing residuum fractions cannot be adequately desulfurized.

It is therefore an object of our invention to provide an improved method for the treatment of petroleum materials containing residuum fractions, i.e., fractions which cannot be practically distilled.

Another object of our invention is to provide an improved two-stage method for the treatment of petroleum materials containing residuum fractions to maximize the production of a naphtha fraction suitable for use as an ethylene charge stock.

Still another object of our invention is to provide an improved two-stage treatment process for the removal of sulfur and metal compounds contained in petroleum materials containing residuum fractions.

Yet another object of our invention is to provide an improved method for obtaining a furnace oil and a heavy fuel oil having a low sulfur content.

Other objects, advantages and features of our invention will be apparent to those skilled in the art without departing from the spirit and scope of our invention, and it should be understood that the latter is not necessarily limited to the accompanying discussion and drawings.

In a broad aspect, our invention relates to a process for removing sulfur and metallic compounds from a petroleum material containing a residuum fraction comprising` cracking said petroleum material while substantially in the liquid phase in the presence of hydrogen and a catalyst and thereafter reacting the thus cracked oil while substantially in the liquid phase with hydrogen in the presence of a catalyst comprising essentially a minor amount of a member of the group consisting of oxides and sulfides of metals of Group VI left-hand column of the Periodic System and of iron group metals composited with a major amount of an activated alumina prepared by drying and calcining a substance which is predominantly composed of an aluminum hydroxide containing from 1.2 to 2.6 mols of water of hydration.

DESCRIPTION OF DRAWINGS the hydrogen-rich recycle gas passing through line 35 is combined with hydrogen-rich make-up gas passing through line 36. The hydrogen-rich gas is then combined with the feed passing through line 13. The mixture of the charge and the hydrogen-rich gas passes through line into the hydrocracker 16. The euent from the hydrocracker passes by means of line 19, cooler and line 21 into the 4 hydrodesulfurizer 22. The desulfurized product leaves the desulfurizer 22 by means of line 25, cooler 26, and line 27 and passes into the high pressure separator 28. The desulfurized liquid product is withdrawn from the separator by means of line 29.

Gases from the high pressure separator are withdrawn through line 31. A first portion of the gas ows from line 31 through line 32 to conventional gas recovery facilities. A second portion of the gas flows through line 33 and is compressed by compressor 34. The gas then passes through line 35 and is admixed with make-up hydrogen from line 36. This hydrogen-rich gas is preheated separately or in admixture with the charge stream in heater 14. The admixture then iiows through line 15 as previously described.

The embodiment illustrated in FIG. 2 is similar to that illustrated in FIG. 1 and identical items in both figures have been identified with a prime beside the numbers in FIG. 2. FIG. 2 differs from FIG. 1 in that the efiiuent from the hydrodesulfurizer is heated and then subjected to flash vaporization in a first separator. All or at least a portion of the liquid bottoms emerging from the first separator is then recycled back to the hydrocracker. The portion which is not recycled can be combined with the product of line 29. In accordance with FIG. 2, the desulfurized product leaves the hydrodesulfurizer 22' by means of line 25. This material is then heated in the heater 42 and passed through line 43 to a fiash vaporization separator 44. The liquid bottoms emerging from the separator 44 passes through line 45 to the inlet of pump and is then recirculated to the hydrocracker by means of line 41. The vapor emerging from the separator 44 is passed through line 46, cooler 26 and line 27' to separator 28.

PREFERRED EMBODIMENT In the first stage of the method of our invention, the charge stream is subjected to liquid phase hydrocracking in the presence of a catalyst and a hydrogen-containing gas at elevated temperatures and pressures. Suitable hydrocracking temperatures fall in the range from about 700 F. to about 1000 F., preferably in the range of from about 750 F. to about 900 F. The pressure is maintained in the range of from about 500 p.s.i.g. to about 5000 p.si.g., although a pressure in the range of from about 1500 p.s.i.g. to about 3500 p.s.i.g. is preferred. Any conventional meansl for contacting the charge stream with the hydrogen-containing gas and catalyst can be used. For example, the process can be operated by using various manipulative steps, e.g., upflow, downow and horizontal flow of the liquid, concurrent and countercurrent ow of the gasiform material relative to the ow of liquid and the use of solid contact materials in the form of fixed, moving and fluidized beds. A particularly suitable means for accomplishing the purposes of our invention resides in the use of an ebullated bed. In an ebullated bed reactor, the liquid and gasiform material is concurrently passed upwardly through a vessel containing particulate catalyst,

` the mass of the catalyst being maintained in random motion in the vessel by the upflowing streams. The mass of catalyst in this state of random motion in the liquid medium is described as ebullated The motion of the catalyst makes the reactor free from pressure drop limitations prevalently obtained in fixed beds due to carbon formation, and results in a narrow temperature gradient from the top to the bottom of the reactor.

Ebullated bed reactors are now well-known to those skilled in the art.

The total eluent stream from the hydrocracker is then passed substantially in the liquid phase to a hydrodesulfurizer where it is contacted in the presence of a high activity catalyst with hydrogen-containing gas at elevated temperatures and pressures. The temperature is maintained in the range from about 600 F. to about 850 F., preferably from about 700 F. to about 825 F., and the pressure is maintained in the range from about 500 p.s.i.g., to

about 5000 p.s.i.g., preferably from about 1500 p.s.i.g. to about 3500 p.s.i.g.

The hydrogen supplied to the two-stage system need not be 100 percent pure hydrogen but may contain such other constituents as nitrogen, methane, ethane, etc. Preferably, the hydrogen-rich gas stream should contain not less than 50 volume percent hydrogen. The hydrogen-containing gas is recycled at a rate to provide at least 2500 s.c.f. of hydrogen per barrel of charge stream undergoing treatment. Preferably, hydrogen is recycled at a rate to provide about 5000 s.c.f. to about 10,000 s.c.f. per barrel of the charge stream. Hydrogen make-up is added to the system in an amount equivalent to that consumed in reactions plus losses to the recovery system.

The liquid hourly space velocity in each of the reactors is maintained in the range from about 0.25 to about 5.0, preferably, in the range from about 0.5 to 3.0.

Applicable catalysts for the first stage treatment of the charge stream include low-acidity catalysts in the form of beads, pellets, powder, extrudates or like particles. The size and shape of the catalyst employed depends on the particular conditions of the process, e.g., the density, viscosity and velocity of the liquid involved in the process.

In general, suitable catalysts include the metals of Groups VI and VIII of the Periodic Table of Elements, and their oxides or sulfides, either alone or in admixture with each other, deposited on amorphous metal oxide support wherein the metal oxide is selected from the -group consisting of silica, oxides of metals in Groups II-A, III-A and IV-B of the Periodic Table, and mixtures thereof. Examples of Group VI metals are molybdenum, tungsten and chromium, with the preferred Group VI metal being molybdenum in the form of a molybdate; examples of Group VIII metal components are cobalt and nickel; and example of the metal oxides in the amorphous support are alumina, silica, zirconia, magnesia, titania, ceria, thona, etc. Preferred catalysts for the first stage are typified by nickel sulfide-tungsten sulfide, molybdenum sulfide or oxide, combinations of metal sulfides or oxides such as ferrie oxide, cobalt oxide or sulfide and molybdenum oxide, all of which are supported on the above amorphous metal oxide supports. In particular, preferred catalysts include catalysts having from about 1 to 10, preferably 2-4 weight percent of a Group VIII metal oxide, preferably cobalt oxide; and from about 5-30, preferably -15 weight percent of a Group VI metal oxide, preferably molybdenum; supported on the amorphous metal oxide support, preferably alumina.

The first stage hydrocracking operation effectively accomplishes molecular weight reduction of the charge stream, partial removal of sulfur, and substantial removal of metal-containing compounds-thereby protecting the catalyst bed in the subsequent hydrogenation stage.

The charge streams used in this process can vary widely in metals content and also in the type of the metals. The metals are contained primarily in the asphaltene and resin components in the charge stream and under hydrocracking conditions will react readily with and be deposited on the catalyst. As the metals from the feed stream accumulate on the catalyst, they change its properties substantially and will, together with the coke deposition that takes place, reduce its activity. The principal metals to contend with are vanadium and nickel. However, the effect of the deposition of these metals is different since nickel is known to be an effective hydrogenation metal, whereas vanadium is not. Since these metals are contained in molecules that are high in molecular weight, their deposition is primarily on the surface of the catalyst particle.

Nevertheless, in accordance with another embodiment of our invention, we have discovered that advantage can be made of this mode of deposition by manufacturing extremely low cost catalyst in situ. This is accomplished by employing a base which does not have strict purity requirements but has a reasonable pore volume and surface area as the catalyst support material. Concentrations of less than 5 percent of molybdenum, cobalt, nickel, iron or mixtures thereof in such concentrations composited on such base materials provide sufficient hydrogenation activity to catalyze the in situ manufacture of catalyst by metal deposition from the charge stream when the charge stream has a metal content greater than about p.p.m.

A relatively inexpensive and preferred catalyst, containing 1 to 5 percent by weight of an active metal such as nickel deposited on a modified fluid bed coke base is particularly effective in the selective removal of metals such as vanadium. Fluid coke not only contains a desirable particle size range but is very durable. However, in order to be a suitable base or carrier for the active metal component, the fluid coke must first be subjected to careful oxidation in a fluidized bed at a temperature level of about 700 F. until the material obtains a pore volume of at least 0.2 cc./ gm. and a surface area of at least 50 square meters/gram. The active metal component is then added to the modified coke material by impregnation in known manner. When this catalyst becomes contaminated with deposits of metallic impurities, catalyst reinvention is readily effected by the method set forth in Connor et al. Pat. No. 3,123,548 (1964) and Leum et al. Pat. No. 3,041,270 (1962) which method ishereby incorporated by reference.

Well known hydrodesulfurization catalysts are not effective in the method of our invention. A highly active catalyst must be employed. We have discovered that a particularly effective catalyst for hydrodesulfurization in the present method is a catalyst which comprises a member of the group consisting of oxides and suldes of metals such as vanadium, chromium or molybdenum metals of the left-hand column of Group VI of the Periodic Table of Elements or iron, cobalt, nickel, platinum, etc. composited with a major amount of an activated alumina prepared by drying and calcining a substance which is predominantly composed of an aluminum hydroxide containing from 1.2-2.6 moles of water of hydration. The preparation of this catalyst is disclosed in Flinn et al. Pat. No. 3,222,273 (1965), which patent is hereby incorported by reference.

Superior desulfurization is obtainable with the high activity desulfurization catalyst only by use of piston flow (no back flow) through the desulfurizer, and hence a fixed bed or downflow reactor in the second (desulfurization) stage is initial to applicants process.

It should be understood that the flow sheets shownto illustrate the embodiments of the present invention are highly simplified for the purpose of clarity. Conventional means for heating and cooling, including but not limited to the use of heat exchange with feed or products streams, can be employed in place of various heating and cooling units. It will also be understood that, if desired, additional hydrogen can be added at various points within the system. Also, it may be preferable in some instances to utilize multiple reactors in series or in parallel.

In order to more fully understand the method of our invention reference is made to the following examples.

EXAMPLE -I An integrated process similar to the complete process illustrated in FIG. 1 is described in this example. As an aid to the understanding of this example, reference will be made to FIG. 1 whenever applicable. A charge stream having the following composition is fed into conduit 111 at the rate of 10,000 bbl`s./day.

Charge stream-Lagomedio long resid (47.2 vol. percent of crude) Gravity- 17.4 API Sulfur content, wt. percent-2.06

Vanadium content- 271 p.p.m.

Nickel content-24 p.p.m.

At least 95 percent of the material of this resid material has a boiling point above 675 F. The charge stream is combined lwith 10,200 s.c.f. of hydrogen/bbl. of feed. The combined stream is passed through heater 14 into the hydrocracker 16. Hydrocracking in unit 16 is carried out in the presence of a cobalt molybdate catalyst containing 3 percent cobalt oxide and l2 percent molybdenum oxide by weight on an alumina support, at a pressure of approximately 2500 p.s.i.g. and at a temperature of approximately 850 F. The effluent from the hydrocracker 16 is cooled and then subjected to hydrodesulfurization in unit 22. The hydrodesulfurization is carried out at a pressure of approximately 2500 p.s.i.g. and at a temperature of approximately 775 F. The catalyst is nickel, cobalt and molybdenum (respectively, 0.5, 1.0 and 8.0 percent by weight) deposited on calcined (l000 F. for 10 hours) aluminum hydroxide containing 1.7 moles of water of hydration. The catalyst is prepared in the manner as e1t9f6o5r)th in Example I of Pat. No. 3,222,273 to Flinn et al.

iEluent from the hydrodesulfurizer 22 is then cooled to 100 F. and passed to the separator 28 where it is flashed. The combined liquid product stream (line 29) and the vapor stream (line 32) is removed at the rate as follows:

C1-C3--210,000 lbs/day C4-400o F. (naphtha fraction)-3,700 bbls./ day Furnace oil (400 F.675 F. B.P. range) (0.1 percent sulfur)-4,200 bbls./day Heavy fuel oil (B.P. 675 F.+)(0.3 percent sulfur)-2,900 bbls./day

The liquid hourly space velocity in hydrocracker 16 (ebullated bed) measured at the expanded bed condition is 1.0. The liquid hourly space velocity in hydrodesulfurizer 22 is l.

The hydrogen make-up added through line 36 is added at the rate of 2700 s.c.f./bbl. of feed entering line 11. Gases, including hydrogen sulde, ammonia and hydrogen are removed from the system by means of line 32.

The material leaving the hydrocracker 16 through line 19 has a nickel plus vanadium content of less than 100 p.p.m.

EXAMPLE II An integrated process similar to the complete process illustrated in the FIG. 2 is described in this example. As an aid to the understanding of this example, reference will be made to FIG. 2 whenever applicable. A charge stream having the same composition as the charge stream of Example I was used herein. 4 The charge stream is combined with 10,300 s.c.f. of hydrogen/ bbl. of feed passing through line 11. The combined stream is passed through heater 14 into hydrocracker 16. Hydrocracking in unit 16 is carried out n the presence of a cobalt molybdate catalyst containing 3 percent cobalt oxide and 12 percent molybdenum oxide by weight on an alumina support at a pressure of approximately 2500 p.s.i.g. and at a temperature of approximately 850 F. The effluent from the hydrocracker 16 is cooled and then subjected to hydrodesulfurization in unit 22.

Hydrodesulfurization in unit 22 is carried out at a pressure of approximately 2500 p.s.i.g. and at a temperature of approximately 775 F. The catalyst is nickel, cobalt and molybdenum (respectively, 0.5, 1.0 and 8.0 percent by weight) deposited on calcined (1000 F. for hours) aluminum hydroxide containing 1.7 moles of water of hydration. The catalyst is prepared in the manner as set forth in Example I in Pat. No. 3,222,273 to Flinn et al. (1965).

The eiiluent from the hydrodesulfurizer 22' is heated by means of heater 42 and is subjected to flash vaporization at 875 F. in separator 44. The liquid bottoms portion from separator 44 is recycled back to the hydrocracker 16 at the rate of 1200 bbl/day. The vapor portion emerging from separator 44 is then cooled by means Vset forth may be made without departing from the 8 of cooler 26 and is passed to separator 28 where it is flashed. The combined liquid product stream (line 29') and vapor stream (line 32') is removed at the rate as follows:

C1-C3-225,000 lbs./day

C4-400D F. (naphtha fraction)-4,000 bbls./ day Furnace oil (400 F.-675 F. B.P. range) (0.1 percent sulfur)-4,600 bbls./ day Heavy fuel oil (B.P. 675 F.|) (0.25 percent sulfur)-2,300 bbls./day

The liquid hourly space velocity in hydrocracker 16' (ebullated bed) measured at the expanded bed condition is 1.0. The liquid hourly space velocity in hydrodesulfurizer 22 is 1.0

The hydrogen make-up passing through line 3'6' is added at the. rate of 2900 s.c.f./bbl. of feed entering line 11. Gases, including hydrogen sulfide, ammonia and hydrogen are removed from the system by means of line 32.

The material leaving the hydrocracker 16' through line 19 has a nickel and vanadium content of less than p.p.m.

Thus, a novel process is provided by the present invention for treating high metal content petrole-um materials containing residuum fractions to produce a product from which high yields of naphtha suitable for use as an ethylene charge stock and heavy fuel oil of low sulfur content can be obtained. Obviously, many modifications and variations of the present invention as hereinbefore spirit and scope thereof.

We claim:

1. A process for removing sulfurl and metallic compounds from a petroleum material having a sulfur content of over 2 percent by weight and metallic contaminants in excess of 100 p.p.m. and containing a major proportion of. a residuum fraction comprising cracking said petroleum material in a cracking zone While substantially in the liquid phase in the presence of hydrogen and a catalyst selected from the group consisting of oxides .and sulfides of cobalt, molybdenum, nickel, tungsten, and mixtures thereof supported on a carrier material, at a temperature in the rangefrom about 700 F. to about 1000 F. ata pressure in the range from about 500l p.s.i.g. to about 5000 p.s.i.g. and producing a cracked oil with less than 20 p.p.m. metallic contaminants, and thereafter reacting the thus cracked oil at a temperature in the range of from about 600 F. to about 850 F. and at a pressure lin the range from about 500 p.s.i.g. to about 5000 p.s.i.g. while substantially in the liquid phaseV with hydrogen in a fixed bed reactor in the presence'of a catalyst comprising essentially a minor amount of a member of the group consisting of oxides and suldes of metals of Group VI left-hand column of the Periodic System and of iron group metals composited Iwith a major amount of an activated alumina prepared by drying and calcining a substance which is predominantly composed of an aluminum hydroxide containing from 1.2 to 2.6 moles of water of hydration in order to produce a hydrodesulfurized fuel oil product withless than about `0.5 percent sulfur, and a hydrocarbon fraction boiling in the naphtha range which is desirable as an v ethylene charge stock from the standpoint of low cyclic content and low isoto normal paraffin ratio.

2. The process according to claim 1 rwherein the cracking of said petroleum material is performedl ata temperature in the range from about 750 F. to about 900 F. and at a pressure in the range of from about 1500 p.s.i.g. to about 3500 p.s.i.g.

3. The processV according to claim 2 wherein the metals content of the petroleum material is reduced to less than 100 p.p.m. by said cracking.

4. The process according to claim 2 wherein the reacting of the thus cracked oil is performed at a temperature in the range of from about 700 F. to about 825 F. and at a pressure in the range of from about 1500 p.s.i.g. t0 about 3500 p.s.i.g.

5. The process according to claim 1 wherein said cracking takes place in the presence of a catalyst comprising 3 weight percent cobalt oxide and 12 weight percent molybdenum oxide on an alumina support.

6. The process according to claim 1 wherein said hydrodesulfurized product is subjected to flash vaporization in order to obtain a vapor stream and a liquid stream, recycling said liquid stream to said cracking zone, and recovering a naphtha fraction, a furnace oil fraction and a heavy fuel oil fraction from said vapor stream.

7. The process according to claim 1 wherein said cracking zone is an ebullated bed cracking zone.

8. The process according to claim 1 wherein said carrier material is ud bed coke having a surface area of at UNITED STATES PATENTS 10/196'9 Masologites et al. (I). 11/1969 Masologites et al. (II).

0 DELBERT E. GANTZ, Primary Examiner R. M. BRUSKIN, Assistant Examiner U.S. Cl. X.R.

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