US 3622497 A
Description (OCR text may contain errors)
United States Patent 11 1 3,622,497
 Inventor William K. T. Gleim  References Cited Island Lake, Ill. UNITED STATES PATENTS '1 PPA- 1970 1,890,434 12/1932 Krauch et al. 208/10 ga 1971 3,074,879 1/1963 Weekman 208/176 3,161,585 12/1964 Gleim et al. 208/264 1 Asslgnee gg f z i 3,231,488 1/1966 Gatsis et al. 208/264 3,558,474 1/1971 Gleirn et al. 208/108 Primary Examiner-Delbert E. Gantz SLURRY PROCESS USING VANADIUM SULFIDE Assistant ExaminerG. E. Schmitkons FOR CONVERTING HYDROCARBONACEOUS Attorneys.lames R. Hoatson, Jr. and Robert W. Erickson BLACK OIL 7 Claims, No Drawings  U S Cl 1 208,108 ABSTRACT: A catalytic slurry process for hydrorefining a 6 hydrocarbonaceous charge Stock i i g hy b 23/117 208,215 208/25 1 L3 soluble asphaltenes. The process is effected in slurry fashion [5 I] Int. Cl Clo] 23/6, with the charge Stock being admixed with a phenolic Solution g 5 l 08 of a tetravalent vanadium salt. The slurry is reacted at condi- 0 tions including a temperature above about 50 and a p 2l525h252/4l4'439 sure greater than about 500 p.s.i.g., and in the presence of hydrogen and hydrogen sulfide.
SLURRY PROCESS USING VANADIUM SULFIDE FOR CONVERTING HYDROCARBONACEOUS BLACK OIL APPLICABILITY OF INVENTION The invention described herein is adaptable to a process for effecting the conversion of asphaltene-containing petroleum fractions into lower boiling hydrocarbon products. More specifically, the present invention is directed toward a slurrytype catalytic process for continuously converting hydrocarbonaceous material such as atmospheric tower bottoms, vacuum tower bottoms (vacuum residuum, crude oil residuals, topped crude oils, coal oil extracts, crude oils extracted from tar sand, all of which are referred to in the art as black oils." In particular, the process described herein affords a high degree of asphaltene conversion to hydrocarbon-soluble products, while simultaneously effecting a substantial degree of hydrorefining to reduce the concentration of sulfurous and nitrogenous compounds.
Hydrocarbonaceous black oils contain high molecular weight sulfurous compounds in exceedingly large quantities. In addition, the black oils contained excessive quantities of nitrogenous compounds, high molecular weight organometallic complexes principally comprising nickel and vanadium, and asphaltenic material. The asphaltenic material is generally found to be complexed or linked with sulfur and, to a certain extent, with the organometallic contaminants. An abundant supply of such hydrocarbonaceous material exists, most of which has a gravity less than 20.0 API, and which is further characterized by a boiling range indicating that 10.0 percent by volume, and generally more, has a normal boiling point above a temperature of about l,050 F.
The process of the present invention is particularly directed toward the catalytic conversion of black oils into distillable hydrocarbons. Specific examples of the black oils, illustrative of those to which the present invention is especially applicable, include a vacuum tower bottoms product having a gravity of 7.l API, containing 4.05 percent by weight of sulfur and 23.7 percent by weight of asphaltenes; and, a vacuum residuum having a gravity of 8.8 API, containing 3.0 percent by weight of sulfur, 4,300 ppm. by weight of nitrogen and having a 20.0 percent volumetric distillation temperature of 1,055 F. The principal difficulty, heretofore encountered, resides in the lack of a technique which would afiord many catalytic composites the necessary degree of sulfur stability in the presence of the asphaltenic compounds, while producing lower boiling products from this hydrocarbon-insoluble asphaltenic material. The asphaltenic fraction consists primarily of high molecular weight, nondistillable coke precursors, insoluble in light hydrocarbons such as propane, pentane, or heptane. In addition to the asphaltenes, sulfurous and nitrogenous compounds, black oils contain large quantities of metallic contaminants, generally in the range of 50 p.p.m. to as high as 1,000 p.p.m. by weight, as the elemental metal. A reduction in the concentration of the organometallic contaminants, such as metal porphyrins, is not easily achieved, and to the extent that the same no longer exert detrimental effects with respect to further processing. For example, when a hydrocarbon charge stock containing metals is subjected to catalytic cracking for the purpose of producing lower boiling compounds, the metallic contaminants become the deposited upon the catalyst employed, steadily increasing in quantity until such time as the composition of the catalytic composite is changed to the extent that undesirable results are obtained.
The primary purpose of the present invention is to provide an efiicient and economical process for the conversion, or hydrorefining of heavy hydrocarbonaceous material containing insoluble asphaltenes, utilizing a solid, unsupported catalyst in slurry admixture with the charge stock. The term hydrorefining," as employed herein, connotes the catalytic treatment, in an atmosphere of hydrogen, of a hydrocarbon fraction or distillate for the purpose of eliminating and or reducing the concentration of the various contaminating influences previously described. The present invention involves the use of a colloidally dispersed, unsupported catalytic material in a slurry process. There is afforded a greater yield of liquid hydrocarbon product suitable for further processing without experiencing the difficulties otherwise resulting from the presence of the foregoing contaminating influences.
The unsupported catalyst, utilized in the slurry process of the present invention, is a vanadium sulfide of nonstoichiometric sulfur content. The novel concept upon which the present process is founded, resides in the manner in which the vanadium sulfide is caused to be colloidally dispersed within the charge stock.
OBJECTS AND EMBODIMENTS As hereinbefore set forth, a principal object of the present invention resides in providing a process for the conversion of petroleum black oils. A corollary object is to convert hydrocarbon-insoluble asphaltenes into hydrocarbon-soluble, lower boiling normally liquid products.
Another object is to effect removal of sulfurous and nitrogenous compounds by conversion thereof into hydrocarbons, hydrogen sulfide and ammonia. V
A specific object of my invention is to effect the continuous decontamination of asphaltenic black oils by providing a slurry process utilizing a solid, unsupported vanadium sulfide catalyst. In conjunction with this object, it is the intent to provide a commercially feasible method for dispersing the catalytic vanadium sulfide within the fresh feed charge stock.
These objects are accomplished by admixing the fresh feed charge stock with a phenolic solution of a tetravalent vanadium salt, and reacting the resulting mixture with hydrogen and hydrogen sulfide whereby the catalytic vanadium sulfide is produced in situ within the reaction zone.
Therefore, in one embodiment, my invention encompasses a process for hydrorefining a hydrocarbon charge stock which comprises admixing said charge stock with a phenolic solution of a tetravalent vanadium salt and reacting the resulting mixture, at hydrorefining conditions, with hydrogen and hydrogen sulfide.
Other embodiments of my invention reside in the utilization of particular operating conditions and techniques, various phenolic material for dissolving the tetravalent vanadium salt, concentration of reactants, etc. These, as well as other objects and embodiments will become apparent from the following detailed summary of my invention.
SUMMARY OF INVENTION The unsupported catalyst, utilized in the slurry process of the present invention, is a vanadium sulfide of nonstoichiometric sulfur content. Through the use of the term unsupported,"it is intended to designate a catalyst, or catalytic component, which is not an integral part of a composite with a refractory inorganic oxide carrier material. That is, the catalyst is a vanadium sulfide without the addition thereto of extraneous material. While the precise atomic ratio of sulfur to vanadium in the catalytic, nonstoichiometric vanadium sulfide, is not known with accuracy, the catalytic vanadium sulfide has a ratio of sulfur to vanadium not less than 0.8:1, nor greater than 1.811. This is not intended to mean that the vanadium sulfide catalyst has but a single specific sulfur/vanadium atomic ratio but rather refers to a mixture of vanadium sulfides having sulfur/vanadium atomic ratios in the aforesaid range. Although four oxidation states are known for vanadium, 2, 3, 4, and 5, Periodic Table of the Elements, E. H. Sargent and Company, 1964, only three stoichiometric vanadium sulfides are sufficiently stable for identification. These are: monovanadium sulfide, VS; sesquivanadium sulfide, V 8 and, pentavanadium sulfide, V 5 Handbook of Chemistry and Physics, Chemical Rubber Publishing Co., 42nd Edition, page 680, 1960-1961. The literature is replete with references to many identifiable nonstoichiometric vanadium sulfides and which are specific compounds in their own right, possibly the most common being the tetrasulfide,
V5,. Significantly, l have previously found that the catalytic vanadium sulfide is not identifiable as any of the stoichiometric vanadium sulfides, or as V8,. The present invention is primarily directed toward a method for producing the catalytic, nonstoichiometric vanadium sulfide in situ, which method affords a commercially feasible, economical slurrytype process.
As previously set forth, it has been found that colloidally dispersed, nonstoichiometric vanadium sulfides are capable of effecting the hydrorefining of a wide variety of petroleum black oils. Furthennore, it has previously been shown that these catalytic vanadium sulfides must necessarily be produced in situ in order to yield the more advantageous results. In accordance with the present invention, the production of the finely divided catalytic vanadium sulfide is accomplished by initially dissolving tetravalent vanadium salts in the fresh feed charge stock. Heretofore, this has been accomplished by dissolving organic complexes of tetravalent vanadium in the charge stock. However, the high cost of the complexing agent, for example acetyl acetone, or methyl naphthalene, prohibit their use in a commercially scaled process where the daily fresh feed charge rate may be as high as 40,000 barrels. l have now found that it is possible to prepare a phenolic solution of tetravalent vanadium salts which, under the conditions of the operation are converted to the catalytic vanadium sulfide. The use of a solution of tetravalent vanadium compound is advantageous in that the resulting vanadium sulfide is more finely and thoroughly dispersed within the charge stock being processed.
Among the multitude of suitable tetravalent vanadium salts are vanadium tetraoxide, vanadium tetrafluoride, vanadium tetrachloride,,vanadyl difluoride, vanadyl dichloride, vanadyl sulfate, vanadyl dibromide, various ammonium vanadyl oxalates, vanadium xanthates, etc.; the halides will not be as practical as the other salts because they form the corrosive halogen acids as byproducts. The tetravalent vanadium salt is employed in an amount such that the concentration of the catalytic vanadium sulfide, following decompositions within the charge stock, is at least about 1.5 percent by weight thereof. Excessive concentrations do not appear to enhance the results, even with extremely contaminated charge stocks having an exceedingly high asphaltene content. Therefore, the practical upper limit of the catalytic vanadium sulfide is about 25.0 percent by weight, calculated as elemental vanadium.
Suitable phenols include phenol, orthocresol, metacresol, paracresol, alpha-naphthol, beta-naphthol, catechol, resorcinol, hydroquinone, etc. A distinct advantage, resulting from the use of phenolic material, resides in the fact that the phenols do not have to be pure. As a matter of fact mixtures of phenols are more efficient solvents. Therefore, phenolic coal tar cuts, or acid oil fractions from petroleum can be suitably employed informing the phenolic solution of tetravalent vanadium salts. Wood tar, and preferably fractions thereof boiling above about 250 C., constitutes a more economical oil solublizer for tetravalent vanadium salts in view of the fact that it contains large amounts of catechol and various pyrogallol derivatives, the latter being far more efficient for dissolving the tetravalent vanadium salt. Furthermore, these phenolic coal tar cuts, wood tar, etc., will be converted during the course of the reaction into more valuable lower boiling hydrocarbon products.
The charge stock/phenolic solution mixture is comingled with hydrogen in an amount of from 5,000 to about 100,000 s.c.f./bbl. Following suitable heat exchange with various hot effluent streams, the temperature of the mixture is further increased to the level desired at. the inlet to the reaction zone. Since the reactions being effected are principally exothermic, the temperature of the effluent from the reaction chamber will be higher than the inlet temperature. The inlet temperature is generally controlled at a minimum level about 225 C., and at higher levels such that the outlet temperature does not exceed about 500 C. Excellent results are generally attainable when the temperature gradient across the reaction chamber is about 380 C. to about 450 C. The reaction zone is maintained under an imposed pressure greater than about 500 p.s.i.g., and preferably at a level of from 1,500 to about 5,000 p.s.i.g.
Although the present process may be effected in an elongated reaction zone with the mixture being introduced thereto in the upper portion thereof, the effluent being removed from a lower portion, an upflow system offers numerous advantages. A principal advantage resides in the fact that the ex tremely heavy portion of the charge stock has an appreciably longer residence time within the reaction zone, with the result that a greater degree of conversion is attainable, and incoming hydrogen will effectively strip lower boiling products therefrom. Also, the heavy, unconverted asphaltic material can be withdrawn from the bottom of the reaction chamber along with particles of vanadium sulfide.
The liquid product effluent, containing distillable hydrocarbons, along with hydrogen, hydrogen-sulfide, ammonium, and normally gaseous hydrocarbons, principally methane, ethane, and propane, are removed from the upper portion of the reaction chamber. A hot flash system functioning at essentially the same pressure as the reaction chamber in a first stage, and at a substantially reduced pressure in a second stage, serves to separate the overhead product effluent into a principally vaporous phase, the principal portion of which boils below about 800 F. and a principally liquid phase boiling above about 800 F. The latter may be recycled to combine with the fresh charge stock, thereby serving as a diluent, or it may conveniently be employed to facilitate the introduction of the phenolic solution of a tetravalent vanadium salt to the reaction zone.
The principally vaporous phase passes into a cold, highpressure separator (about 60 F. to F.), wherein a hydrogen-rich gaseous phase is recovered and recycled, along with makeup hydrogen required to supplant that consumed within the reaction chamber. The normally liquid phase from the cold separator, containing some butanes, is generally subjected to fractionation to prepare a charge stock suitable for further processing. The hot flash system may also function to remove all distillable hydrocarbons boiling below any other desired temperature such as 750 F 950 F., l,050 F etc.
With respect to the bottom stream from the hot flash system, it may be totally recycled to combine with the fresh hydrocarbonaceous charge stock. However, it is a preferred operating technique to withdraw a drag stream therefrom containing at least about 10.0 percent by weight of the catalytic vanadium sulfide. Any suitable means may be utilized to separate the solid catalyst and unreacted asphaltenic material from the liquid phase hydrocarbons, including filtration, settling tanks, a series of centrifuges, etc. A like quantity of fresh tetravalent vanadium salt is then added in order to maintain the selected catalyst content of the slurry.
The catalyst withdrawn with the drag stream is separated, for example, by a series of filtration and methyl naphthalene washing techniques. Methyl naphthalene is employed to remove residual, soluble hydrocarbons from the catalyst-containing sludge. The remainder of the catalyst sludge may then be burned in air to produce vanadium pentoxide which is reduced with sulfur dioxide, in aqueous sulfuric acid to produce vanadyl sulfate which is subsequently reused by being dissolved in a phenolic solution.
In a preferred embodiment, the hydrogen stream entering the reaction chamber contains from 1.0 mol percent to about 15.0 mol percent of hydrogen sulfide. The incorporation of hydrogen sulfide facilitates the formation of the catalytic vanadium sulfide during the decomposition of the tetravalent vanadium salt in the phenolic solution.
DESCRIPTION OF A PREFERRED EMBODIMENT The fresh feed charge stock in this illustrative embodiment is a vacuum tower bottoms having a gravity of 9.8 API, and having a 30.0 percent volumetric distillation temperature of about l,050 F. Contaminating influences include about 5.2
percent by weight of heptane insolubles, 3.06 percent by weight of sulfur, 4,030 p.p.m. by weight of hydrogen and a total metals concentration of about I00 p.p.m. Vanadium pentoxide is reduced with sulfur dioxide, in aqueous sulfuric acid to prepare vanadyl sulfate. The vanadyl sulfate is dissolved in a phenol-rich wood tar fraction boiling above a temperature of about 250 C., the solution being admixed with the fresh feed charge stock in an amount calculated to provide about 3.0 percent by weight of vanadium with respect to the charge stock. The reaction zone is pressured to a level of about 3,000 p.s.i.g., utilizing compressive hydrogen recycle in an amount of about 15,000 s.c.f./bbl.; the hydrogen recycle stream contains about 10.0 mol percent hydrogen sulfide.
The vacuum tower bottoms-phenolic solution-hydrogen mixture is circulated through a block heater at a temperature of about 250 C. for a period of about 1 hour. The temperature of the block heater is increased to a level such that the temperature gradient, as measured from the reaction zone inlet to the outlet, is controlled at about 350 C. to about 400 C. The fresh feed charge rate is about l ml./hr., and makeup hydrogen is added in an amount of about 7.15 s.c.f./hr.
After a line'out period, analyses of the normally liquid product effluent from about an 8-hour period indicate greater than about 97.5 percent heptane-insoluble conversion, less than about 15.0 p.p.m. of organometallic complexes and a gravity of about API.
1 claim as my invention:
1. A process for hydrorefining a hydrocarbon charge stock which comprises admixing said charge stock with a phenolic solution of a tetravalent vanadium salt and reacting the resulting mixture, at hydrorefining conditions, with hydrogen and hydrogen sulfide.
2. The process of claim 1 further characterized in that said phenolic solution comprises phenol.
3. The process of claim 1 further characterized in that said phenolic solution comprises a cresol.
4. The process of claim 1 further characterized in that said phenolic solution comprises a naphthol.
5. The process of claim 1 further characterized in that said phenolic solution comprises catechol.
6. The process of claim 1 further characterized in that said hydrorefining conditions include a temperature of from 225 C. to about 500 C. and a pressure in the range of 500 p.s.i.g. to about 5,000 p.s.i.g.
7. The process of claim 1 further characterized in that said phenolic solution comprises crude coal tar.