US 3836452 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent O US. Cl. 208-108 3 Claims ABSTRACT OF THE DISCLOSURE Asphaltene-containing hydrocarbonaceous charge stocks are reacted with hydrogen in contact with a catalytic composite of at least one metal component selected from the group consisting of the borides and borohydrides of the metals from Groups IV, V and VI. A slurry-type process, which may be effected either with a metallic component being composited with a porous carrier material, or with the unsupported metallic component, and admixed with the fresh feed charge stock.
RELATED APPLICATION The present application is a Division of my copending application, Ser. No. 282,998, filed Aug. 23, 1972, now US. Pat. No. 3,796,671, all the teachings of which copending application are incorporated herein by specific reference thereto.
This application is filed to comply with a requirement for restriction in said copending application, Ser. No. 282,998.
APPLICABILITY OF INVENTION The invention herein described is adaptable to a process for the conversion of heavy, asphaltene-containing petroleum crude oils into lower-boiling hydrocarbon products. More specifically, the present invention is directed towards a catalytic process for continuously converting atmospheric tower bottoms products, vacuum tower bottoms products (vacuum residuum), crude oil residuum, topped crude oils, coal oil, 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 process affords a high degree of asphaltene conversion into hydrocarbonsoluble products, while simultaneously effecting a substantial conversion of sulfurous and nitrogenous compounds to reduce sulfur and nitrogen concentrations.
Petroleum crude oils, particularly the heavy oils extracted from tar sands and vacuum residuum, 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. These high molecular weight asphalts are 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 currently exists, most of which has a gravity less than about 20.0 API. This material characterized in that 10.0% by volume, and generally more, has a normal boiling point above a temperature of about 1050 F.
The process of the present invention is particularly directed toward the catalytic conversion of hydrocarbonaceous black oils into distillable hydrocarbon products. Specified examples of black oils, illustrative of those to is generally further 6 which the present invention is applicable, are a vacuum tower bottoms product, having a gravity of 7.l API, and containing 4.05% by weight of sulfur and 23.7% by weight of asphaltenes; and, a vacuum residuum having a gravity of 88 API, and containing about 6.0% by weight of asphaltic material. The present invention affords the conversion of the greater proportion of such matenal, heretofore having been thought to be virtually precluded. The principal difficulty resides in the lack of a technlque which affords many catalytic composites the necessary degree of sulfur stability, while simultaneously producing lower-boiling 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 catlytically active surfaces and sites of the catalyst are shielded from the material being processed.
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, a fixed-fluidized bed of catalyst particles. Although perhaps effective 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 of unconverted asphaltics suspended in a free liquid-phase oil for an extended period of time, results in polymerization and agglomeration. 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 to deactivation as a result of the deposition of coke and metallic contaminants thereon. Furthermore, such a process requires an attendant high capacity regeneration system in order to implement the process on a continuous basis. Briefly, the present invention involves a slurry-type process utilizing a catalytic composite of at least one metal component selected from the group consisting of the borides and borohydrides of the metals from Groups IV, V and VI of the Periodic Table. The asphaltic material and catalyst are maintained in a dispersed state within a principally liquid phase which is rich in hydrogen. Intimate contact is thus afforded 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.
In addition to the hydrocarbon-insoluble asphaltenes, sulfurous and nitrogenous compounds, black oils contain greater quantities of metallic contaminants than are generally found in lighter hydrocarbon fractions. A reduction in the concentration of the organometallic contaminants, such as the metal porphyrins, is not easily achieved, and to the extent that the same no longer exert detrimental effects with respect to subsequent fixed-bed catalytic processing. When a metal-contaminated hydrocarbon charge stock is subjected to a hydrocracking process, for example, to produce lower-boiling hydrocarbons, the metals become deposited upon the catalyst, 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 principal object of the present invention is to provide a more efficient process for the hydrorefining conversion of heavy hydrocarbonaceous material containing insoluble asphaltenes. 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 hereinabove set forth, accompanied by hydrogenation and significant conversion into lower-boiling hydrocarbon products. As previously stated, metallic contaminants are generally removed from hydrocarbon charge stocks by deposition of the same onto the catalytic composite employed. This increases the amount of catalyst, effectively shields the catalytically active surfaces and centers from the material being processed, and thereby generally precludes the eflicient utilization of fixed-bed system. The present invention involves the use of a colloidally dispersed catalytic agent in a slurry-type process, and affords greater yields of a normally liquid hydrocarbon product, which is more suitable for subsequent processing, I
One object of the present invention is to provide a more efficient process for the conversion of asphaltene-containing hydrocarbonaceous charge stocks. A corollary objective is to provide a novel conversion catalyst.
Therefore, in one embodiment, the present invention is directed toward a process for the conversion of a sulfurous, asphaltene-containing hydrocarbonaceous charge stock, which process comprises reacting said charge stock with hydrogen and in contact with a catalytic composite of at least one metallic component selected from the group consisting of the borides and borohydrides of the metals from Groups IV, V and VI, and recovering desulfurized, lower-boiling hydrocarbon products. In another embodiment, the charge stock is reacted with hydrogen in the presence of about 2.0% to about 30.0 (on a mole basis) of hydrogen sulfide.
In a preferred embodiment, the selected metal boride, or metal borohydride, is unsupported, and is admixed with said charge stock in an amount from about 1.0% to about 30.0% by weight.
SUMMARY OF INVENTION From the foregoing embodiments, it is readily ascertained that the process of the present invention involves the preparation of a colloidally dispersed catalytically active metallic component within the hydrocarbon charge stock from which the contaminating influences are intended to be removed. The colloidally dispersed catalytic component is a metallic compound selected from the group consisting of the borides and borohydrides of the metals from Groups IV, V and VI. Thus, in accordance with the Periodic Table of The Elements, E. H. Sargent and Co., 1964, suitable catalytic metallic components are the borides and borohydrides of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and/or tungsten. These compounds are solids, and may be employed in admixture with the charge stock in and of themselves, or in combination with a suitable refractory inorganic oxide. While any of the well-known refractory inorganic oxides may be utilized in combination with the metallic boride, or borohydride, the use of alumina is preferred. A particularly preferred porous carrier material is a composite of alumina and from about 10.0% to about 90.0% by weight of silica. When utilizing a porous carrier material, the catalytic composite is conveniently prepared by commingling the metallic boride, or borohydride, and finely-divided carrier material under reducing conditions and subjecting the resulting mixture to a pilling, or co-extrusion technique under a reducing gas atmosphere. The catalytic agent, whether supported, or unsupported, is employed in an amount in the range of about 1.0% to about 30.0%, based upon the weight of the black oil charge stock.
Brie-fly, the 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 suitable reaction chamber maintained at a temperature within 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 from about 1,000 to about 30,000 scf./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 effected as a batch-type operation, or in a continuous manner in either upward flow, or downward flow. 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 metal-containing sludge is a viscous fluid consisting of the catalytically active metallic component, unconverted asphaltic material, soluble hydrocarbons, porphyrinic material containing nickel, vanadium and other metallic contaminants, coke and heavy carbonaceous material, etc. Following the separation of the normally liquid hydrocarbons from the metal-containing sludge, the latter is treated with a suitable organic solvent for the purpose of dissolving residual hydrocarbon-soluble material resulting from the conversion of the insoluble asphaltenic compounds. Any well-known organic solvent may be employed for the dissolution of the organic-soluble material in the sludge, and the resulting solution may be subjected to further reaction with hydrogen by recycling the same to combine with fresh hydrocarbon charge stock. The remaining portion of the sludge, containing the catalytically active agent, is combined with fresh hydrocarbon charge stock and again reacted with hydrogen as aforesaid. 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 metals recovery system.
The following examples are presented to illustrate the process of the present invention and the effectiveness thereof in converting asphaltenic material. It is not intended that the present invention be unduly limited to the method, charge stock, catalytic agent and/or operating conditions employed in these illustrations.
EXAMPLES The hydrocarbon charge stock is a vacuum tower bottoms having a gravity of 8.8 API, containing 6.0% by weight of asphaltenic material, 3.0% by weight of sulfur, and 4,300 ppm. by weight of nitrogen; the 20.0% volumetric distillation temperature is about 1055 F.
EXAMPLE I In this example, the criteria employed to indicate the degree of conversion, particularly with respect to asphaltenic material, is the color index of the product. Obviously, the lighter the color of the product, the lower the color index and the greater degree of conversion. The color index is determined by UOP Method 707-71, based upon the information found in Analytical Chemistry, Volume 34, pages 694-700, l962.
The charge stock is employed in an amount of about 200 grams, and is admixed with about 20.0 grams (10.0% by weight) of titanium borohydride. The charge stock and catalytic agent are intimately commingled in an 1,800 cc. rotating autoclave with hydrogen at a pressure of atmospheres. Upon heating to a temperature of 400 C., the pressure increases to about 200 atmospheres. These conditions are maintained for a two-hour period, after which the autoclave is cooled and depressured, and the contents separated to provide a metal-containing sludge and the normally liquid product efliuent. The latter is analyzed for color index. and gravity, and a significant improvement is observed; the gravity is increased from 88 API to about 25.4 API and the color index is decreased from about 150.0 to about 2.0.
EXAMPLE II In this example, the hydrocarbonaceous black oil is a heavy vacuum tower bottoms product having a gravity of 7.0 API and contaminated by the presence of 6,060 ppm. of nitrogen, 4.0% by weight of sulfur, more than 450 p.p.rn. of organometallic contaminants, and about 24.0% by weight of pentane-insoluble asphaltenic material. The charge stock, in an amount of about 200 grams, is admixed with 25.0 grams of unsupported vanadium borohydride, the mixture being placed in the rotating autoclave and pressured to about 100 atmospheres with hydrogen. The contents of the autoclave are heated to a temperature of about 425 C., the pressure increasing to about 215 atmospheres. The conditions are maintained for an eighthour period, after which the autoclave is depressured, cooled and the contents separated to provide a normally liquid hydrocarbon product. The latter indicates a gravity of about 33.8 API, 0.2% by weight of insoluble asphaltics, 450 p.p.m. of nitrogen and 0.88% by weight of sulfur.
The foregoing specification and examples clearly illustrate the method by which the present invention is effected and the benefits to be afforded through the utilization thereof. The normally liquid hydrocarbon product is substantially free from asphaltic material, and has been significantly decontaminated with respect to the concentration of sulfurous and nitrogenous compounds.
I claim as my invention:
1. A process for the conversion of a sulfurous, asphal tene-containing hydrocarbonaceous charge stock which comprises commingling with said charge stock hydrogen in an amount from about 1000 to about 30,000 scf./ bbl. and form about 1.0% to about 30.0% by weight of at least one compound selected from the group consisting of the borides and borohydrides of the metals from groups IVB, VB and VIB, heating the resultant mixture to a temperature of from about 225 C. to about 500 C. to react hydrogen with the charge stock, and recovering desulfurized, lower-boiling hydrocarbon products.
2. The process of claim 1 further characterized in that said compound is titanium borohydride.
3. The process of claim 1 further characterized in that said compound is vanadium borohydride.
References Cited UNITED STATES PATENTS 1,938,328 12/1933 Griffith 252432 X 1,998,626 4/1935 Koenig 252432 2,326,800 8/1943 Pier et al 252432 X 3,475,325 10/1969 Doane 208111 3,640,817 2/1972 OHara 208-59 DELBERT E. GANTZ, Primary Examiner G. E. SCHMITKONS, Assistant Examiner US. Cl. X.R.