US3859199A - Hydrodesulfurization of asphaltene-containing black oil - Google Patents

Abstract

A combination process for the desulfurization of asphaltenecontaining black oils. The charge stock in admixture with hydrogen and a recycle stream containing a high percentage of asphaltenes is subjected to a first-stage catalytic desulfurization zone. The effluent from the first stage is deasphalted to produce a deasphalted oil stream and a residuum stream. The deasphalted oil stream in admixture with hydrogen is subjected to a second-stage catalytic desulfurization zone and at least a portion of the residuum stream is recycled to the first stage catalytic desulfurization zone.

Description

Gatsis Jan. 7, 1975 HYDRODESULFURIZATION OF ASPHALTENE-CONTAINING BLACK OIL John G. Gatsis, Des Plaines, lll.

Universal Oil Products Company, Des Plaines, lll.

Filed: July 5, 1973 Appl. No; 376,506

Inventor:

Assignee:

U.S. Cl 208/97, 208/210, 208/218,

- 208/307 Int. Cl Cl0g 37/06 Field of Search 208/210, 218, 309

References Cited UNITED STATES PATENTS 7/l973 Watkins 208/210 Primary Examiner-C. Davis Attorney, Agent, or Firm-James R. Hoatson, Jr.; Thomas K. McBride; William H. Page, ll

[ 57] ABSTRACT A combination process for the desulturization of asphaltene-containing black oils. The charge stock in admixture with hydrogen and a recycle stream containing a high percentage of asphaltenes is subjected to a first-stage catalytic desulfurization zone. The effluent from the first stage is deasphalted to produce a deasphalted oil stream and a residuum stream. The deasphalted oil stream in admixture with hydrogen is subjected to a second-stage catalytic desulfurization zone and at least a portion of the residuum stream is recycled to the first stage catalytic desulfurization zone.

8 Claims, 1 Drawing Figure l Hydrag en Hydrogen Salve/1f Ca/a/yr/c Rana/ion -4 Daaspha/far- /'Zane 5 Deaspha//ed Low Sulfur Cafa/yf/c Rene/ion Zone HYDRODESULFURIZATION F ASPHALTENE-CONTAINING BLACK OIL The combination process described herein is adaptable to the desulfurization of petroleum crude oil. More specificially, the present invention is directed toward a process for effecting a reduction in the sulfur content of atmospheric tower bottoms products, vacuum tower bottoms products, crude oil residuum, topped crude oils, the crude oils extracted from tar sands and shale, all of which are sometimes referred to as black oils and which contain a significant quantity of asphaltenic material.

Petroleum crude oils, particularly heavy oils extracted from tar sands, and topped or reduced crudes, contain high molecular weight sulfurous compounds in exceedingly large quantities. In addition, such crude, or

black oils contain excessive quantities of nitrogenous compounds, high molecular weight organo-metallic complexes consisting principally of nickel and vanadium, and asphaltenic material. The latter is generally found to be complexed, or linked with sulfur and, to a certain extent, with the organo-metallic contaminants. The utilization of these highly contaminated black oils, as a source of more valuable liquid hydrocarbon products, is precluded unless the sulfur and asphaltene content is sharply reduced, and such a reduction is not easily achieved by preferred techniques involving fixedbed catalytic processing.

A black oil can be generally characterized as a heavy hydrocarbonaceous material of which more than 10.0 percent (by volume) boils above a temperature of 1,050F. (referred to as non-distillable), and having a gravity, A?! at 60F., of less than 20. Sulfur concentrations are exceedingly high, most often greater than 2.0 percent by weight, and may range as high as 5.0 percent by weight. Conradson Carbon Residue factors exceed 1.0 weight percent, and a great proportion of black oils exhibit a Conradson Carbon Residue factor above 10.0. An abundant supply of such hydrocarbonaceous material currently exists, most of which has a gravity less than l0.0APl, and which is characterized by a boiling range indicating that 30.0 percent or more boils above a temperature of 1,050F

Specific examples of the crude, or black oils to which the present scheme is uniquely adaptable, include a sour Wyoming, full boiling range crude oil having a gravity of 23.2 API, and containing 2.8 percent by weight of sulfur and about 8.3 percent by weight of insoluble asphaltenes. A more difficult black oil is a vacuum tower bottoms product having a gravity of 7.1APl, and containing 4.05 percent by weight of sulfur and 23.7 percent by weight of asphaltenes. A topped Middle-East Kuwait crude oil having a gravity of 11 API, and containing 10.1 percent by weight of asphaltenes and 5.2 percent by weight of sulfur will, through the applicationof the present invention, experience a reduction of 80 percent of the asphaltenes and more than 90 percent reduction in sulfur concentration. Such results have heretofore been considered virtually impossible to achieve on an economically feasible basis utilizing the generally preferred fixedbed catalytic processing technique. The principal difficulty resides in the lack of sulfur stability of the catalytic composite employed and arises primarily from the presence of asphaltenic material. This asphaltenic material comprises high molecular weight, non-distillable, oilinsoluble coke precursors, which can be complexed with nitrogen, metals and especially sulfur. Generally, the asphaltenic material is found to be colloidally dispersed within the crude oil, and, when subjected to heat, as in a vacuum distillation process, has the tendency to flocculate and polymerize whereby the conversion thereof to more valuable oil-soluble products becomes extremely difficult. Thus, in the heavy bottoms from a crude oil vacuum distillation column the polymerized asphaltenes exist as solid material useful only as road asphalt, or as an extremely low grade fuel when out with distillable hydrocarbons such as kerosene, light gas oil, etc.

The necessity for the removal of the foregoing contaminating influences is well known to those cognizant of petroleum refining processes and techniques. Heretofore, in the field of catalytic hydrorefining to principal approaches have been advanced: liquid-phase hydrogenation and vapor-phase hydrocracking. In the former type of process, the oil is passed upwardly in liquid phase, and in admixture with hydrogen, into a fixed-bed or slurry of subdivided catalyst; although perhaps effective in removing at least a portion of the organo-metallic complexes, this type process is relatively ineffective with respect to oil-insoluble asphaltenes which are colloidally dispersed within the charge, with the consequence that the probability of effecting simultaneous contact between the catalyst particle and asphaltenic molecule is remote. Furthermore, since the hydrogenation reaction zone is generally maintained at an elevated temperature of at least about 500C. (932F.), the retention of unconverted asphaltenes, suspended in a free liquid phase oil for an extended period of time, will result in flocculation making conversion thereof substantially more difficult. The rate of diffusion of the oil-insoluble asphaltenes is substantially lower than of dissolved molecules of the same molecular size; for this reason, fixed-bed catalytic processes, in which the oil and hydrogen are passed through the catalyst, have been thought to be virtually precluded. The asphaltenes, being neither volatile nor dissolved in the crude, are unable to move to the catalytically active sites, the latter being obviously immovable. Furthermore, the efficiency of hydrogen to oil contact obtainable by bubbling hydrogen through an extensive liquid body is relatively low. On the other hand, vapor-phase hydrocracking is carried out either with a fixed-bed or expanded-bed system at temperatures substantially above about 950F.; while this technique obviates to a certain extent the drawbacks of liquid-phase hydrogenation, it is not suited to treating crude and heavy hydrocarbon fractions due to the non-voltility of the asphaltenes which favors a high production of coke and carbonaceous material, with the result that the catalytic composite succumbs to relatively rapid deactivation; this requires high capacity catalyst regeneration equipment in order to implement the process on a continuous basis.

As hereinafter indicated in greater detail, the use of the present invention avoids these difficulties in a manner which provides economic feasibility to the desulfurization of crude oil.

The principal object of this invention is to provide an economically feasbile catalytic crude oil desulfurization process in which the catalytic composite exhibits an excellent degree of stability. The present process produces a crude oil product containing less than 10 percent by weight of sulfur originally present in the crude oil, and simultaneously decreases the asphaltenic content by at least 80 percent.

Another object is to convert heavy hydrocarbon charge stocks, a significant amount of which exhibits a boiling range above a temperature of 1,050F. i.e., at least about percent boils above this temperature, and often more than 30 percent into lower boiling distillable hydrocarbons, having a sulfur concentration less than about 0.5 weight percent by preferably less than 0.2 weight percent.

Another object of my invention is to provide a process for desulfurizing blacks oils having a gravity, APl at 60F., less than about 20.

Another object is to effect the desulfurization of black oils with minimum yield loss to light normally gaseous hydrocarbons, while producing high yields of fuel oil containing less than 0.2 percent by weight of sulfur.

In one embodiment, therefore, the present invention encompasses a combination process for the desulfurization of a sulfurous, asphaltene-containing hydrocarbonaceous charge stock, of which at least about 10 percent boils above a temperature of 1,050F., which process comprises the steps of: (a) contacting a mixture of said charge stock, hydrogen and at least a portion of the asphaltic residuum resulting from Step (c) in a first catalytic desulfurization reaction zone to partially convert the asphaltenes present in said charge stock; (b) deasphalting at least a portion of the resulting desulfurized producteffluent in a deasphalting zone to provide a deasphalted oil, essentially free of asphaltenes, and an asphaltic residuum containing asphaltenes; (c) recycling at least a portion of said asphaltic residuum in admixture with said charge stock; ((1) contacting said deasphalted oil and hydrogen in a second catalytic desulfurization reaction zone; and, (e) recovering a low sulfur hydrocarbonaceous oil.

Other objects'and embodiments of our invention will be evident from the following, more detailed description of the present combination process.

As hereinbefore set forth, the principal function of the present invention resides in the production of maximum quantities of fuel oil containing less than 0.2 percent by weight of sulfur. This is accomplished through the utilization of my combination process in a relatively simple manner, in a highly economically attractive fashion and while avoiding the difficulties of currently known schemes. No known catalyst has permitted the single stage desulfurization of hydrocarbonaceous black oils to a residual sulfur level of less than 0.2 weight percent without severe and rapid catalyst deactivation due to the coking of the asphaltenes upon the catalytically active sites.

I have discovered a combination process whereby the asphaltenes are converted in a first catalytic reaction zone with severity selected to reduce the concentration of both sulfur and asphaltenes while precluding the premature coking of the desulfurization catalyst. The resulting effluent is then charged to a solvent deasphalting section from which is recovered a deasphalted oil (DAO) which is substantially free from asphaltenes and an asphaltic residuum. The above-mentioned deasphalted oil is charged to a second catalytic reaction zone which is maintained at operating conditions sufficient to reduce the residual sulfur in the refined black oil to less than 0.2 weight percent without the concern of prematurely deactivating the catalyst by the conversion of asphaltenes into coke. At least a portion of the asphaltic residuum from the deasphalter is recycled to said first catalytic reaction zone to further reduce the concentration of asphaltenes.

The severity of operating conditions imposed upon the catalytic reaction zones depends on the particular characteristics of the feed stock selected for processing. The operating conditions are intended to include reaction zone temperatures ranging from about 600 to about 900F., measured at the inlet to the catalyst bed. Since the bulk of the reactions are exothermic, the reaction zone effluent will be at a higher temperature than the inlet. In order that catalyst stability be preserved, it is preferred that the effluent temperature does not exceed about 900F. Hydrogen is commingled with the charge stock to each reaction zone in an amount generally less than about 10,000 s.c.f./bbl. at the selected operating pressure, and preferably in an mount of from about 1,500 to about 6,000 s.c.f./bbl. The operating pressure will be greater than 1,000 psig., and generally in the range of about 1,500 psig. to about 4,000 psig. The black oil passes through the catalyst at a liquid hourly space velocity defined as volumes of liquid hydrocarbon charge per hour, measured at F per volume of catalyst disposed in the reaction zone, of from about 0.1 to about 10 and preferably from about 0.25 to about 2.0.

When conducted as a continuous process, it is particularly preferred to introduce the mixture into the vessel in such a manner that the same passes through the vessel in downward flow. The internals of the vessel may be constructed in any suitable manner capable of providing the required intimate contact between the liquid charge stock, the gaseous mixture and the catalyst. in some instances it may be desirable to provide the reaction zone with a packed bed or beds of inert material such as particles of granite, porcelain, berl saddles, sand, aluminum or other metal turnings, etc., to facilitate distribution of the charge or to employ perforated trays or special mechanical means for this purpose.

As hereinbefore set forth, hydrogen is employed in admixture with the charge stock, and preferably in an amount of from about 3,000 to about 6,000 s.c.f./bbl. The hydrogen-containing gas stream, herein sometimes designated as recycle hydrogen, since it is conveniently recycled externally of the hydrorefining zone, fulfills, a number of various functions: it serves as a hydrogenating agent, a heat carrier, and particularly a means for stripping converted material from the catalytic composite, thereby creating still more available catalytically active sites for the incoming, unconverted hydrocarbon charge stock. Since some hydrogenation will be effected, there will be a net consumption of hydrogen; to supplement this, make-up hydrogen is added to the system from any suitable external source.

The catalytic composite disposed within the reaction zone can be characterized as comprising a metallic component having hydrogenation activity, which component is composited with a refractory inorganic oxide carrier material of either synthetic or natural origin. The precise composition and method of manufacturing the carrier material is not considered essential to the present process, although a siliceous carrier, such as 88.0 percent alumina and 12.0 percent silica, or 63.0 percent alumina and 37.0 percent silica, are generally preferred. Suitable metallic components having hydrogenation activity are those selected from the group consisting of the metals of Group Vl-B and VIII of the Periodic Table, as indicated in the Periodic Chart of the Elements, Fisher Scientific Company, (1953). Thus, the catalytic composite may comprise one or more metallic components from the group of molybdenum, tungsten, chromium, iron, cobalt, nickel, platinum, palladium, iridium, sosium, rhodium, ruthenium, and mixtures thereof. The concentration of the catalytically active metallic component, or components, is primarily dependent upon the particular metal as well as the characteristics of the charge stock. For example, the metallic components of Group VI-B are preferably present in an amount within the range of the about 1.0 percent to about 20.0 percent by weight, the irongroup metals in an amount within the range of about 0.2 percent to about 10.0 percent by weight, whereas the platinum-group metals are preferably present in an amount within the range of about 0.1 percent about 5.0 percent by weight, all of which are calculated as if the components existed within the finished catalytic composite as the elemental metal.

The refractory inorganic oxide carrier material may comprise alumina, silica, zirconia, magnesia, titania, boria, strontia, hafnia, and mixtures of the two or more including silica-alumina, alumina-silica-boron phosphate, silica-zirconia, silica-magnesia, silica-titania, alumina-zirconia, alumina-magnesia, alumina-titania, magnesia-zirconia, titania-zirconia, magnesia-titania, silica-alumina-zirconia, silica-alumina-magnesia, silicaalumina-titania, silica-magnesia-zirconia, silicaalumina-boria, etc. It is preferred to utilize a carrier material containing at least a portion of silica, and preferably a composite of alumina and silica with alumina being in the greater proportion.

In the above-mentioned deasphalting section, the first catalytic reaction zone effluent is contacted with a solvent which is capable of dissolving the oil but which does not dissolve the asphaltenes. Suitable solvents are light petroleum fractions, such as naphtha, casinghead gasoline and petroleum fractions normally vaporous at ordinary temperature and pressure. Other solvents which may be used are alcohol, ether, mixtures of alcohol and ether, acetone, etc. Preferably, the solvent is a liquefied normally gaseous hydrocarbon such as a petroleum fraction obtained by the rectification of natural gasoline. Such solvents comprise methane, ethane, propane, butane and mixtures thereof.

The solvent deasphalting operation may be a batch operation, a multiple vessel operation or a substantially continuous liquid-liquid countercurrent treating operation wherein the first reaction zone effluent is introduced into the top of a deasphalting tower and flowed therein in liquid-liquid direct countercurrent contact with any suitable deasphalting solvent as hereinbefore described. The deasphalting operation is carried out at any suitable combination of deasphalting temperature and pressure, the temperature and pressure being adjusted so as to maintain the deasphalting solvent in the liquid phase during the deasphalting operation. A deasphalting temperature in the range of about 150 to about 325F., usually not more than 50F. lower than the critical temperature of the deasphalting solvent and a pressure in the range of from about 50 to about 800 psig. usually are suitably employed depending upon the 6 composition of the deasphalting solvent and, to a minor extent, depending upon the composition of the black oil undergoing solvent deasphalting. Generally a deasphalting solvent to black oil volume ratio in the range of from about 1 to about 13 is employed within the solvent deasphalting zone. The solvent deasphalting zone may be operated isothermally or under a temperature gradient, e.g., top tower temperature greater than the bottom tower temperature by more than about 40F. Also the deasphalter may be operated so that the black oil is introduced into the actual zone at a number of points along the treating section thereof and/or the deasphalting solvent similarly introduced into the deasphalting treating section.

Following the deasphalting operation there is recovered from the solvent deasphalter a solvent deasphalted oil and an asphaltic residuum. The asphalt residuum is withdrawn from recycle to the first catalytic reaction zone. Optionally, a slipstream of the residuum may be withdrawn for other uses, e.g., the production of asphalt paving products. The solvent deasphalted oil recovered from the solvent deasphalting zone may have a gravity in the range of from about 10 to about 25 API and a Conradson Carbon Residue in the range of from about 0.5 to about 10 percent. The deasphalted oil is then introduced into the second catalytic reaction zone.

EXAMPLE In the drawing, the embodiment is presented by means of a simplified flow diagram in which details as pumps, instrumentation and controls, heat-exchange and heat-recovery circuits, valving, start-up lines and similar hardware have been omitted as being nonessential to an understanding of the techniques involved. The use of such miscellaneous appurtenances. to modify the process, are well within the purview of one skilled in the art.

For the purpose of demonstrating the illustrated embodiment, the drawing will be described in connection with the conversion of a black oil (vacuum column residuum) in a commercially sealed unit having a fresh stock charge rate of 45,000 bbl./day.

It is to be understood that the charge stock, stream compositions, operating conditions, design of fractionators, separators and the like, are exemplary only, any may be varied widely without departure from the spirit of my invention, the scope of which is defined by the appended claims.

With reference now to the drawing, 45,000 bbl./day of vacuum residuum having the properties set forth in Table I, is introduced into the process via line 1.

TABLE 1 Vacuum Residuum Charge Stock Properties Gravity, API at 60F. 15.2 Distillation, D H60, F.:

Initial boiling point 480 5.0% 562 10.0% 628 30.0% 800 50% 948 Nitrogen, p.p.m. 2500 Sulfur, wt. percent 5.0 Conradson Carbon, wt. percent 1 1.8 Heptane-insolubles, wt. percent 8.5 Metals, p.p.m. (Approx.) l()() Nickel and vanadium only After appropriate heat-exchange with various hot effluent streams, the charge stock in an amount of 45,000 bbl./day is commingled with 1000 bbl./day of recycle asphaltic residuum which is introduced via line 10 and described hereinbelow, and with a hydrogen rich gaseous phase which is introduced via line 2 and which is sufficient to provide a hydrogen circulation rate of 5000 s.c.f./bbl. The fresh charge stock, the recycle asphaltic residuum and the hydrogen rich gas are then heated to a temperature of 700F. and introduced into a first catalytic reaction zone 4 via line 3. Reaction zone 4 contains a catalytic composite of 14 percent by weight molybdenum and 2 percent by weight cobalt (computed on the basis of the element metals) impregnated on a spherical alumina carrier material, and is maintained at a pressure of 2000 psig., and a temperature, at the inlet to the catalyst bed, of 700F. Since the reactions being effected are primarily exothermic, the temperature is controlled to provide a maximum 50F. temperature rise through the reactor. The catalytic composite is employed in an amount such that the liquid hourly space velocity therethrough is 0.7.

The effluent from the first reaction zone is cooled and separated into a hydrogen rich gaseous phase, a normally liquid hydrocarbon stream in an amount of 6000 bbL/day boiling below 650F. and a normally liquid hydrocarbon stream in an amount of 41,000 bbl./day boiling above 650F. and containing 1 weight percent sulfur. The hydrogen rich gaseous phase is recycled to the first reaction zone via line 2 in combination with fresh makeup hydrogen. The hydrocarbons boiling below 650F. are utilized according to eonventional refining techniques. The hydrocarbons boiling above 650F. are transferred to solvent deasphalter 6 via line and into the top of a deasphalting tower and flowed therein in liquid-liquid direct countercurrent contact with a propane-butane solvent at a pressure of 600 psig., a temperature of 280F. and a solvent ratio of 4. An asphalt residuum, in an amount of 1,197 bbL/day, with a gravity of 10API and containing 5.5 weight percent sulfur is removed from the solvent deasphalter via line 8. One thousand barrels per day of the asphaltic residuum is recycled via line 10 to the inlet of the first catalytic reaction zone for further reduction of the asphaltenes and the remainder or 197 bbl./day is utilized according to the refiners requirements.

A deasphalted oil, in an amount of 39,817 bbl./day, with a gravity of 19 API and containing 0.9 weight percent sulfur is recovered from the solvent deasphalter and removed via line 7. The recovered deasphalted oil is indirectly heatexchanged with various hot effluent streams and commingled with a second hydrogen rich gaseous phase which is introduced via line 13 and which is sufficient to provide a hydrogen circulation rate of 5000 s.c.f./bbl. The deasphalted oil and the hydrogen rich gas are heated to a temperature of 720F. and introduced into a second catalytic reaction zone 1 1 via line 14. Reaction zone 11 contains a catalytic composite of 14 percent by weight molybdenum and 2 percent by weight cobalt, computed on the basis of the elemental metals, impregnated on a spherical alumina carrier material and is maintained at a pressure of 2,000

psig. and a temperature, at the inlet ofthe catalyst bed, of 720F. The catalyst composite is employed in an amount such that the liquid hourly space velocity therethrough is 0.6.

The effluent from the second reaction zone is cooled and separated into a hydrogen rich gaseous phase which is recycled via line 13 and a normally liquid hydrocarbon stream of 42,000 bbL/day containing 0.2 weight percent residual sulfur which hydrocarbon stream is removed via line 12. As will be apparent to those skilled in the art in the light of the foregoing disclosure many alterations, substitutions and changes are possible in the practice of this invention without departing from the spirit or scope thereof.

1 claim as my invention:

1. A combination process for the desulfurization of a sulfurous, asphaltene-containing hydrocarbonaceous charge stock, of which at least about 10 percent boils above a temperature of 1,050F., which process comprises the steps of:

a. contacting a mixture of said charge stock, hydrogen and at least a portion of the asphaltic residuum resulting from Step (c) in a first catalytic desulfurization reaction zone to partially convert the as phaltenes present in said charge stock;

b. deasphalting at least a portion of the resulting desulfurized product effluent in a deasphalting zone to provide a deasphalted oil, essentially free of asphaltenes, and an asphaltic residuum containing asphaltenes;

0. recycling at least a portion of said asphaltic residuum in admixture with said charge stock;

d. contacting said deasphalted oil and hydrogen in a second catalytic desulfurization reaction zone; and,

e. recovering a low sulfur hydrocarbonaceous oil.

2. The process of claim 1 further characterized in that said hydrogen is present in an amount of from about 1,500 to about 10,000 s.c.f./bbl.

3. The process of claim 1 further characterized in that said charge stock contacts said catalyst at a liquid hourly space velocity of from about 0.1 to about 10.

4. The process of claim 1 further characterized in that said catalytic reaction zones are maintained at a temperature from about 600 to about 900F.

5. The process of claim 1 further characterized in that said catalytic reaction zones are maintained at a pressure from about 1,000 to about 4,000 psig.

6. The process of claim 1 further characterized in that said deasphalting zone utilizes a solvent selected from propane and butane and mixtures thereof.

7. The process of claim 1 further characterized in that said catalytic desulfurization zones contain catalyst comprising at least one metal selected from Group VI-B and Group VIII of the Periodic Table.

8. The process of claim 1 further characterized in that said catalytic desulfurization zones contain catalyst comprising cobalt and molybdenum.

Claims (8)

1. A COMBINATION PROCESS FOR THE DESULFURIZATION OF A SULFUROUS, ASPHALTENE-CONTAINING HYDROCARBONACEOUS CHARGE STOCK, OF WHICH AT LEAST ABOUT 10 PERCENT BOILS ABOVE A TEMPERATURE OF 1,050*F., WHICH PROCESS COMPRISES THE STEPS OF: A. CONTACTING A MIXTURE OF SAID CHARGE STOCK, HYDROGEN AND AT LEAST A PORTION OF THE ASPHALTIC RESIDUUM RESULTING FROM STEP (C) IN A FIRST CATALYTIC DESULFURIZAION REACTION ZONE TO PARTIALLY CONVERT THE ASPHALTENES PRESENT IN SAID CHARGE STOCK; B. DEASPHALTING AT LEAST A PORTION OF THE RESULTING DESULFURIZED PRODUCT EFFLUENT IN A DEASPHALTING ZONE TO PROVIDE A DEASPHALTED OIL, ESSENTIALLY FREE OF ASPHALTENES; AND AN ASPHALTIC RESIDUUM CONTAINING ASPHALTENES; C. RECYCLING AT LEAST A PORTION OF SAID ASPHALTIC RESIDUUM IN ADMIXTURE WITH SAID CHARGE STOCK; D. CONTACTING SAID DEASPHALTED OIL AND HYDROGEN IN A SECOND CATALYTIC DESULFURIZATION REACTION ZONE; AND, E. RECOVERING A LOW SULFUR HYDROCARBONACEOUS OIL.

2. The process of claim 1 further characterized in that said hydrogen is present in an amount of from about 1,500 to about 10, 000 s.c.f./bbl.

3. The process of claim 1 further characterized in that said charge stock contacts said catalyst at a liquid hourly space velocity of from about 0.1 to about 10.

4. The process of claim 1 further characterized in that said catalytic reaction zones are maintained at a temperature from about 600* to about 900*F.

5. The process of claim 1 further characterized in that said catalytic reaction zones are maintained at a pressure frOm about 1,000 to about 4,000 psig.

6. The process of claim 1 further characterized in that said deasphalting zone utilizes a solvent selected from propane and butane and mixtures thereof.

7. The process of claim 1 further characterized in that said catalytic desulfurization zones contain catalyst comprising at least one metal selected from Group VI-B and Group VIII of the Periodic Table.

8. The process of claim 1 further characterized in that said catalytic desulfurization zones contain catalyst comprising cobalt and molybdenum.

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