US3785958A - Desulfurization and conversion of black oils - Google Patents

Abstract

ASPHALTENE- AND ASH-CONTAINING HYDROCARBONACEOUS CHARGE STOCKS ARE CONVERTED INTO LOWER-BOILING, SUBSTANTIALLY DESULFURIZED HYDROCARBON PRODUCTS VIA A COMBINATION PROCESS INVOLVING DEASHING, HYDROGENATIVE CONVERSION OF ASPHALTENES IN A SLURRY-TYPE SYSTEM AND DESULFURIZATION EMPLOYING A FIXED-BED CATALYTIC COMPOSITE. THE PROCESS

AFFORDS MAXIMUM YIELD OF NORMALLY LIQUID HYDROCARBON PRODUCTS, COUPLED WITH SUBSTANTIAL DESULFURIZATION THEREOF.

Description

Jn. 15, L97@ W K, T, GLEgM ET AL 3,785,958

BLACK dus DSULFURILA.ION ANI) CONVERSAL ION mi Filed SeDt QQ.QQ\QQmm. Kubus@ QR Swish mm S Sw United States Patent O U.S. Cl. 208-87 6 Claims ABSTRACT OF THE DISCLOSURE Asphalteneand ash-containing hydrocarbonaceous charge stocks are converted into lower-boiling, substantially desulfurized hydrocarbon products via a combination process involving deashing, hydrogenative conversion of asphaltenes in a slurry-type system and desulfurization employing a iixed-bed `catalytic composite. The process aiords maximum yield of normally liquid hydrocarbon products, coupled with substantial desulfurization thereof.

APPLICABILITY OF INVENTION The invention herein described is intended to be applied to the hydrogenative conversion and desulfurization of heavy, asphaltene-containing hydrocarbonaceous charge stocks, especially those contaminated by the inclusion of finely-divided particulate ash. More specifically, the present invention is directed towards a combination process for the continuous conversion of atmospheric tower bottoms products, vacuum tower bottoms products (vacuum residuum), crude oil residuum, topped crude oils, shale oils, coal oils, and especially oils extracted from tar sands, etc., all of which are commonly referred to in the art as black oils, and which contain an appreciable quantity of asphaltenic material.

In particular, the present combination process affords a high degree of asphaltene conversion into hydrocarbonsoluble products, while simultaneously effecting substantial conversion of sulfurous and nitrogenous compounds to reduce sulfur and nitrogen concentrations. Crude petroleum oils, particularly vacuum residuum, shale oil and the heavy oils extracted from tar sands, the latter sometimes referred to a syncrude, contain high molecular weight sulfurous compounds in exceedingly large quantities, being in excess of 1.0% by weight, and often exceeding 3.0% by Weight. In addition, these black oils contain excessive quantities of nitrogenous compounds, high molecular weight organometallic complexes principally comprising nickel and vanadium, and asphaltenic material. The high molecular weight asphalts are generally Ifound to be complexed, or linked with sulfur and to a certain extent with the organometallic contaminants. An abundant supply of such material currently exists, most of which has a gravity less than about 20.0 API. Black oils are generally further characterized in that 10.0% by volume, and generally more, indicates a normal boiling point above a temperature of about 1050" F. In addition to the foregoing-described contaminating influences, many black oils such as shale oils and solubilized coal contain finely-divided particulate ash. This is especially true with respect to the oils extracted from tar sands, in which the ash content generally exceeds 1.0% by weight. The ash consists principally of aluminosilicates having nominal diameters in the range of about 1.0 to about 10.0 microns. Such iinelydivided particles have extremely sharp edges and are, therefore, excessively abrasive. Since its erosive tendencies cannot be tolerated, the ash must necessarily be removed prior to subsequent processing. Furthermore the ash will plug, in a very short time, any fixed-bed catalyst reactor.

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Specific examples of black oils, illustratiae of those to which the present invention is applicable, are a vacuum tower bottoms product, having a gravity of 7.1 API and containing 4.1% by Weight of sulfur and 23.7% by weight of asphaltenes; a vacuum residuum having a gravity of 8.8 API and containing about 5.0% by weight of asphaltic material; a shale oil having a gravity of 19.6 API, and containing 0.6% ash; a coal oil having a gravity of 10.1 API, and containing 0.5% ash; and, a tar sands oil having a gravity of about 6.9a API, and containing 10.6% by weight of insoluble asphaltics, 5.23% by weight of sulfur and about 1.8% by weight of ash. The present combination process atords the conversion of the greater proportion of such material, heretofore having been thought to be virtually precluded. The principal diiculty resides in the lack of an operating technique which aords fixed-bed catlaytic 4composites the necessary degree of sulfur stability, While simultaneously producing lowerboiling products from the hydrocarbon-insoluble asphaltic material. Asphaltic material consists primarily of high molecular weight, non-distillable coke precursors, insoluble in light hydrocarbons and which, at the conditions required to obtain acceptable desulfurization, agglomerate and polymerize to the extent that the catalytically active surfaces and sites of the catalyst are shielded from the material being processed. As hereinabove set forth, ashcontaining black oils create additional diiculties when processing is attempted in accordance with present-day techniques.

PRIOR ART Heretofore, in the area of catalytic processing of asphaltene-containing material, two principal approaches have been advanced: liquid-phase hydrogenation and vapor-phase, or mixed phase hydrocracking. In the former type of process, liquid-phase oil is passed upwardly, in admixture with hydrogen, into a. xed-uidized bed of catalyst particles. Although perhaps eEective in converting at least a portion of the oil-soluble organometallic complexes, this type process is relatively ineffective with respect to the high-boiling asphaltics. The retention ot unconverted asphaltics, suspended in a free liquid phase oil for an extended period of time, results in polymerization and agglomeration thereof. Some processes have been described which rely primarily upon cracking in the presence of hydrogen over a fixed-bed of a solid, particulate catalyst. The latter rapidly succumbs almost immediately to plugging by ash; the deposition of coke and metallic contaminants will hasten this event. Briey, the present invention involves a slurry-type process utilizing an unsupported catalytic agent of at least one metal com ponent selected from the group consisting of the metals from Groups IV, V, and VI of the Periodic Table. The asphaltic material and catalyst are thus maintained in a dispersed state within a principally liquid phase rich in hydrogen. Intimate contact is thus aforded between the asphaltic `material and the catalyst, thereby effecting reaction with hydrogen; the liquid phase is itself dispersed in a hydrogen-rich gas phase so that the dissolved hydrogen is continuously replenished.

OBJECTS AND EMBODIMENTS A principal object of the present invention is to provide a more efficient process for the hydrogenative conversion (hydroreining) of heavy hydrocarbonaceous material containing insoluble asphaltenes and particulate ash. Term hydroretining, as employed herein, connotes the catalytic treatment, in an atmosphere of hydrogen, of a hydrocarbon fraction and/or distillate for the purpose of eliminating, or reducing, the concentration of the various contaminating inliuences hereinabove set forth, accompanied by hydrogenation and significant conversion into lower-boiling hydrocarbon products. The present process affords greater yields of normally liquid hydrocarbon products which are more suitable for subsequent processing, without experiencing the difiiculties otherwise resulting from the presence of the foregoing contaminating inuences.

Therefore, in one embodiment, our invention encompasses a process for the conversion of a sulfurous, ashand asphaltene-containing hydrocarbonaceous charge stock, which process ycomprises the steps of: (a) deashing said charge stock, in contact with a selective solvent, in a solvent deashing zone to provide a solvent-lean, ash-containing phase and a solvent-rich, asphaltene-containing phase; (b) reacting at least a portion of said asphaltenecontaining phase with hydrogen, in a first reaction zone, in contact with an unsupported sulfide of a metal from Groups IV-B, V-B and VI-B; (c) separating the resulting first reaction zone efuent to recover a metal-containing sludge and a hydrocarbon phase; (d) reacting at least a portion of said hydrocarbon phase with hydrogen, in a second reaction zone, in contact with a catalytic composite of a porous carrier material and at least one metal cornponent from the metals of Groups VI-B and VIH; and, (e) recovering desulfurized, lower-boiling hydrocarbon products from the resulting second reaction zone efliuent.

In another embodiment, the reaction with hydrogen in the first and second reaction zones is effected in the presence of about 2.0% to about 30.0% (on a mole basis) of hydrogen sulfide.

In a preferred embodiment, the unsupported metallic sulfide is admixed with said charge stock in an amount from about 1.0% to about 30.0% by weight.

SUMMARY OF INVENTION The present combination process makes use of solvent deashing, in a solvent extraction zone, to precipitate the ash in a solvent-lean bottoms phase. The solvent-rich phase, containing virgin asphaltenic compounds, is withdrawn as a solvent-rich phase and reacted in part with hydrogen in contact with an unsupported catalytic component. Following separation of a metal-containing sludge from the first reaction zone effluent, the remainder is subjected to additional reaction with hydrogen in contact with a fixed-bed catalytic composite of a porous carrier material and at least one metallic component from the metals of Groups VI-B and VIII of the Periodic Table. It must be acknowledged that the prior art is replete with a multitude of techniques for effecting solvent deasphalting of asphaltene-containing charge stocks. It is understood, therefore, that no attempt is herein made to claim solvent deasphalting other than as it is employed as an integral element of the present combination process. However, as distinguished from prior art techniques, deashing, as effected herein, connotes the removal of the ash accompanied by minimal removal of the soluble asphaltenes. This is contrary to solvent deasphalting as practiced in the prior art wherein every effort is made to remove as much of the asphaltenic fraction in addition to any ash which may be present. This constitutes one of the essential features of the present combination process. That is, the charge stock, upon being subjected to solvent extraction techniques, retains the greater proportion of the asphaltenes. 'Ihe results of the differences in these techniques are made apparent by the specific examples hereinafter set forth.

Any suitable solvent extratcion technique known in the prior art may be employed, several examples of which are hereinafter described. In the interest of brevity, no attempt will be made to delineate exhaustively the solvent extraction art. Exemplary of such prior art is U.S. Pat. No. 1,948,296 (Class 208-4) in which the separated asphaltic fraction is admixed with a suitable oil, the mixture being subjected to oxidation to obtain a particularly good road asphalt product. The described solvents, for utilization in precipitating the asphaltic fraction, include light petroleum hydrocarbons such as naphtha, casinghead gasoline, light petroleum fractions comprising propane, n-butane and isobutane, certain alcohols, ether and mixtures thereof, etc.

U.S. Pat. No. 2,914,457 (Class 208-79) describes a multiple combination process involving fractionation, vacuum distillation, solvent deasphalting, hydrogenation and catalytic reforming. Again, the suitable deasphalting solvents include liquefied normally gaseous hydrocarbons such as propane, n-butane, isobutane, as well as ethane, ethylene, propylene, n-butylene, isobutylene, pentane, isopentane, and mixtures thereof.

These prior art techniques, as well as the many others which could be specifically mentioned, are conspicuously devoid of any intent to distinguish between precipitating substantially all the asphaltenic material and precipitating ash while simultaneously recovering asphaltenes in the solvent-rich phase.

In accordance with the present invention, the ashcontaining, asphaltenic charge stock is introduced into an upper portion of a solvent extraction zone, wherein it countercurrently contacts a suitable selective solvent introduced into a lower portion of the extraction zone. The extraction zone will function at a temperature in the range of about 50 F. to about 500 F., and preferably from about F. to about 300 F.; the pressure will be maintained Within the range of about 100 to about 1,000 p.s.i.g., and preferably from about 200 to about 600 p.s.i.g. The precise operating conditions will generally depend upon the physical characteristics of thel charge stock as well as the selective solvent, in order to recover the greater proportion of the asphaltenes in the solventrich phase. Suitable solvents include those hereinbefore described with respect to prior art deasphalting techniques. Thus, it is contemplated that the solvent will be selected from the group of light hydrocarbons such as ethane, methane, propane, butane, isobutane, pentane, isopentane, neopentane, hexane, isohexane, heptane, isoheptane, the mono-olefinic counterparts thereof, various mixtures, etc. Furthermore, the solvent may be a normally liquid naphtha fraction containing hydrocarbons having from about 5 to about 14 carbon atoms per molecule, preferably a naphtha fraction having an end boiling point below about 200 F. The asphaltene-containing, solvent-rich normally liquid phase is introduced into a suitable solvent recovery system, the design and techniques of which are thoroughly described in the prior art.

Following the removal of the solvent, the deashed oil is admixed with an unsupported catalytic component and `reacted with hydrogen in a slurry-type system. The catalytically active component utilized in slurry admixture with the charge stock is selected from the sulfdes of the metals from Groups IV-B, V-B and VI-B of the Periodic Table as indicated in the Periodic Table of The Elements, E. H. Sargent and Co., 1964. Thus, the catalytic component is selected from titanium sulfide, vanadium sulfide, chromium sulfide, zirconium sulfide, niobium sulfide, molybdenum sulfide, hafnium sulfide, tantalum sulfide and tungsten sulfide. Of these, tungsten sulfide, titanium sulfide and vanadium sulfide are preferred, with non-stoichiometric vanadium sulfide apparently producing the most advantageous result. Non-stoichiometric vanadium sulfide, the method of its preparation and its use in the conversion of asphaltenic material is detailed in U.S. Pat. No. 3,558,474 (Class 208-108).

The slurry process is effected by initially admixing the desired quantity of the catalytic agent with the charge stock. The resulting colloidal suspension is then passed into a reaction chamber maintained at a temperature in the range of about 225 C. to about 500 C. and a pressure of about 500 to about 5,000 p.s.i.g.; the hydrogen concentration is based upon the quantity of charge stock, and is in the range of about 1,000 to about 30,000 s.c.f./ bbl. It appears that the presence of hydrogen sulfide in the hydrogen atmosphere enhances catalytic activity and produces more favorable results; therefore, hydrogen sulfide will be present in an amount within the range of about 2.0% to about 30.0%. The process may be elected as a batch-type operation, or in a continuous manner in either upward flow, or downward iiow. A preferred technique utilizes an elongated reaction chamber through which the reactants are passed in upward flow. The normally liquid hydrocarbons are separated from the total reaction zone product efiiuent by any suitable means, the remaining metal-containing sludge being treated as hereinafter set forth.

The sludge is a viscous fluid containing the catalytic component and substantially all the metallic components originally present in the black oil feed stock-Le. the hydrocarbon product contains less than 10.0 p.p.m. by weight of metallic contaminants. In addition, the sludge contains some soluble hydrocarbons, other heavy carbonaceous material and the catalytically active agent. The metal-containing sludge is combined with fresh hydrocarbon charge stock. :In order to prevent a build-up of coke, unconverted -asphaltenic material and other carbonaceous residue, a controlled portion of the sludge will be withdrawn from the process and sent to a suitable metal recovery system. When utilizing non-stoichiometric vanadium sulfide as the catalytic agent in the slurry-type system, the withdrawn sludge may be subjected to the regeneration technique described in U.S. Pat. No. 3,645,912 (Class 252-411).

The hydrocarbon products from the slurry system, in admixture with the soluble material removed from the metal-containing sludge, is reacted with hydrogen in a fixed-bed catalytic reaction zone. The catalytic composites can be characterized as comprising a metallic component having hydrogenation activity, which component is composited with a porous carrier material of either synthetic, or natural origin. 'Ihe precise composition and method of manufacturing the carrier material is not considered essential to the present process, although alumina, containing from about 10.0% to about 90.0% by weight of silica is preferredi.e. 88.0% alumina and 12.0% silica. Suitable metallic components .are those selected from the group consisting of metals of Groups VI-B and VIII of the Periodic Table, and include one or more metallic components from the group of molybdenum, tungsten, chromium, iron, cobalt, nickel, platinum, palladium, iridium, osmium, rhodium, ruthenium, and mixtures thereof. The concentration of the active metallic component, or components, is primarily dependent upon the particular metal as well as the characteristics of the charge stocks. For example, the metallic components of Groups VI-B are preferably present in an amount within the range of about 4.0% to about 35.0% by weight, the iron-group metals in an amount within the range of about 0.2% to about 10.0% by weight, Whereas the platinum-group metals are preferably present in an amount of about 0.1% to about 5.0% by weight, all of which are calculated as if the components existed within the finished catalytic composite as the elemental metal.

The porous carrier material may comprise alumina, silica, zirconia, magnesia, titania, boria, strontia, hafm'a, and mixtures of two or more. A particularly preferred carrier material is that described in U.S. Pat. No. 3,640,817, and is a mixture of alumina and silica containing from about 5.0% to about 30.0% by weight of brown phosphate. Another preferred catalyst is that disclosed in U.S. Pat. No. 3,525,684.

Catalytic activity within the fixed-bed reaction zone, and especially catalyst stability with respect to the operating severity level, appears to be enhanced by the incorporation of sulfur within the catalytic composite. Therefore, it is Within the scope of the present invention to incorporate from about 0.1% to about 10.0% by weight of sulfur therein. Many such catalyst sulfiding techniques are known, no particular one of which constitutes an essential feature of our invention.

The operating conditions imposed upon the fixed-bed reaction zone are primarily dependent upon the physical and chemical properties of the charge as Well as the desired end result. However, these conditions will generally include a maximum catalyst bed temperature in the range of about 600 F. to about 900 F. Other operating variables include a pressure from about 500 to about 5,000 p.s.i.g., a liquid hourly space velocity (defined as volumes of fresh feed charge stock per hour, per volume of catalyst disclosed within the reaction zone) of about 0.1 to about 5.0 and a hydrogen concentration of about 1,000 to about 50,000 s.c.f./bbl. In View of the fact that the reactions are exothermic in nature, an increasing temperature gradient will be experienced as the hydrogen and feed stock traverse the catalyst bed. Judicious operating techniques generally dictate that the temperature gradient be limited to a maximum of about F., and, in order to insure that the temperature does not exceed the maximum allowed, conventional quench streams, either normally liquid or normally gaseous may be introduced into one or more intermediate loci of the catalyst bed. A portion of the normally liquid product eliiuent from the fixed-bed catalytic reaction zone may be recycled as a diluent to combine with the fresh feed charge stock. In this situation, the combined liquid feed ratio to the catalytic reaction zone will generally be in the range of about 1.1 to about 6.0.

DESCRIPTION OF DRAWING One embodiment of the present combination process is illustrated in the accompanying drawing which is presented as a simplifiedl ow diagram in which miscellaneous appurtenances, not believed necessary for a clear understanding of the invention, have been eliminated. The use of details such as pumps, compressors, instrumentation and controls, heat-recovery circuits, miscellaneous valving, start-up lines and similar hardware, etc., is well within the purview of one skilled in the art. Likewise, with respect to flow of materials throughout the system, only those major streams required to illustrate the interconnection and interaction of the various zones are presented. Thus, various recycle lines., vent gas streams, etc., have also been eliminated.

For the purposes of illustration, the`drawing will be described in conjunction with the processing of a tar sands oil having a gravity of 69 API and containing about 1.8% by weight of sulfated ash. The charge stock is introduced into deashing zone 2 by way of line 1, wherein it contacts a n-heptane solvent introduced by way of line 3. Deashing zone 2 is maintained at a temperature of about 30 F., a pressure of about 250 p.s.i.g. and a solvent to charge stock volumetric ratio of about 3.0 to 1.0. At these conditions, approximately 6.0% by weight of the charge Stock is removed as an ash-containing concentrate by way of line 4. As hereinbefore stated, the ash-containing concentrate may be treated With a suitable solvent to remove hydrocarbon products. The solvent-rich asphaltene-containing stream is removed by Way of line 5, and continues therethrough, after removal of the solvent, in adrnixture with :about 15,000 s.c.f./bbl. of hydrogen from line 6, into reactor 8. Non-stoichiometric vanadium sulfide in an amount of about 20.0% by weight, is admixed with the hydrocarbon/hydrogen mixture by way of line 7. Reactor 8 is maintained under a pressure of about 2,000 p.s.i.g., an inlet temperature of about 380 C. and an outlet temperature of about 420 C. The product eiiluent is Withdrawn by way of line 9 and enters catalyst recovery zone 10.

A metal-containing sludge, following removal therefrom of hydrocarbon-soluble products, is Withdrawn by way of line 11, and recycled to reactor 8 by way of line 7. In order to prevent a build-up of metallic components resulting from the hydrogenative destruction of the metal porphyrins in the charge stock, from about 5.0% to about 20.0% by weight of the metal-containing sludge will continue through line 11 to a metals recovery system.

The asphaltene-free product from the catalyst recovery zone 10 passes by Way of line 12, in admixture with a hydrogen-rich recycle gas from line 13 into fixedbed reactor 14. Reactor 14 contains a catalytic composite of 2.0% by weight of nickel, 16.0% by weight of molybdenum, 8.8% by weight of silica and 73.2% by weight of alumina. Reactor 14 is maintained at a pressure of 2,000 p.s.i.g. and a maximum catalyst bed temperature of about 750 F., the reactants traverse the catalyst bed at a liquid hourly space velocity of about 1.0. The product effluent in line 15, following utilization as a heat-exchange medium and further cooling to a temperature of about 80 F., is introduced into cold separator 16. A hydrogen-rich gaseous phase is withdrawn by way of line 6 to be combined with the deashed oil in line 5, and introduced thereby into reactor 8. Approximately 10,000 s.c.f./bbl. are diverted through line 6 by way of line 13 to be introduced into reaction zone 14. The normally liquid product efiiuent is withdrawn from cold separator 16 by way of line 17 for separation into the desired product slate. The total sulfur concentration of the normally liquid hydrocarbons, including pentanes, is less than about 0.1% by weight.

EXAMPLES The following examples are presented to further illustrate the method of the present invention and the benefits to be afforded through the utilization thereof. A comparison is made wherein the charge stock is (1) deashed and deasphalted to reject approximately 15.0% by weight and (2) deashed to the extent of rejecting only about 5.5% by weight, retaining the greater proportion of the asphaltenes in the solvent-rich phase. The charge stock was the previously described tar sands oil having a gravity of 6.9 API. The sulfur concentration is 5.23% by Weight, the nitrogen concentration is 4,500 p.p.m. by weight, the total metals content is 238 p.p.m. and the sulfated ash is present in an amount of about 1.8% by weight.

Example I The fresh feed charge stock was deashed and deasphalted at a pressure of about 250 p.s.i.g. and a temperature of about 250 F., utilizing n-pentane at a solvent to charge volumetric ratio of about 5.0 to 1.0. The resulting deasphalted material had a gravity of about 12.8 API, and contained 4.62% by weight of sulfur, 2.25% by weight of insoluble asphaltenes and about 195 p.p.m. yby weight of metals.

The deasphalted oil was processed over a fixed-bed of a catalytic composite of 64.7% by weight alumina, 8.8% by weight of silica, 16.0% by weight of molybdenum and 2.0% by weight of nickel. The operating conditions ineluded a liquid hourly space Velocity of about 1.0, a maximum catalyst bed temperature of 800 F., a pressure of about 2,500 p.s.i.g., and a hydrogen concentration of about 10,000 s.c.f./bbl. Product analyses indicated a gravity of about 22.9 API, a sulfur concentration of about 0.25% by Weight and an asphaltene concentration of about 0.4% by weight.

Example II The tar sands oil charge stock was subjected to deashing utilizing n-heptane at a pressure of about 250i p.s.i.g. and a temperature of about 350 F. The solvent to charge volumetric ratio was about 3.0 to 1.0. The resulting deashed product had a gravity of about 8.5 API, contained 4.94% by weight of sulfur and about 9.0% by Weight of insoluble asphaltenes.

The deashed oil was then processed at 2,000 p.s.i.g. and a maximum catalyst temperature of 422 C. in the presence of about 15,000 s.c.f./bbl. of hydrogen. The operation was conducted in slurry fashion utilizing about 10.0% by weight of non-stoichiometric vanadium sulfide. The product efiluent indicated a gravity of 15.9 API, 2.78% by Weight of sulfur, 0.45% by Weight of asphaltenes and a metals concentration of 7.0y p.p.m. 4by Weight.

The normally liquid product efiiuent from the slurry operation was admixed with about 10,000 s.c.f./bbl. of hydrogen and introduced into a fixed-bed reaction zone maintained at a pressure of about 2,000 p.s.i.g. and a maximum catalyst bed temperature of about 750 F. The catalyst was a composite of 6.97% by weight of silica, 8.18% by weight of boron phosphate, 1.89% by weight of nickel, 16.0% by weight of molybdenum and 66.96% by weight of alumina, the reactants traversing the catalyst bed at a liquid hourly space velocity of about 1.0. The pentane and heavier, normally liquid portion of the product effluent indicated a gravity of 24.9 API, an asphaltene concentration of nil and a sulfur concentration of only 0.03% by weight, a degree of desulfurization of asphaltic stocks, never achieved before at such economical liquid hourly space velocities.

The foregoing specification and examples clearly indicate the method of effecting the present combination process as well as the benefits to be afforded through the utilization thereof.

We claim as our invention:

1. A process for the conversion of a sulfurous, ashand asphaltene-containing hydrocarbonaceous charge stock which comprises the steps of:

(a) deashing said charge stock, in contact with a selective solvent, in a solvent deashing zone to provide a solvent-lean, ash-containing phase and a solvent-rich, asphaltene-containing phase;

(b) reacting at least a portion of said asphaltene-containing phase with hydrogen, in a first reaction zone, in contact with an unsupported sulfide of a metal from Groups IV-B, V-B and VI-B;

(c) separating the resulting first reaction zone effluent to recover a metal-containing sludge and a hydrocarbon phase;

(d) reacting at least a portion of said hydrocarbon phase with hydrogen, in a second reaction zone, in contact with a catalytic composite of a porous carrier material and at least one metallic component from the metals of Groups VI-B and VIII; and,

(e) recovering desulfurized, lower-boiling hydrocarbon products from the resulting second reaction zone effluent.

2. The process of claim 1 further characterized in that said sulfide is titanium sulde, vanadium sulfide, or tungsten sulfide.

3. The process of claim 1 further characterized in that at least a portion of said sludge is recycled to said first reaction zone.

4. The process of claim 1 further characterized in that said catalytic composite comprises an alumina-silica carrier material and at least one metallic component from the metals of Groups VI-B and the iron-group.

5. The process of claim 1 further characterized in that said resulting second reaction zone efiiuent is separated to provide a hydrogen-rich vaporous phase, at least a portion of which is recycled to said first reaction zone.

6. The process of claim 5 further characterized in that a portion of said hydrogen-rich vaporous phase is recycled to said second reaction zone.

References Cited UNITED STATES PATENTS 2,559,285 7/1951 Douce 208-86 3,281,350 10/1966 Codet et al. 208-86 3,558,474 1/1971 Gleim et al. 208-213 3,723,294 3/1973 Gatsis et al. 208-86 HERBERT LEVINE, Primary Examiner U.S. Cl. X.R.

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