Lube oils of improved viscosity index are produced by subjecting a crude lubricating oil to hydrocracking, selectively fractionating the hydrocracked product to yield a product having the desired flash point and viscosity and recycling the fractionator bottoms to the hydrocracking zone.
Coleman, Richard L. (Port Arthur, TX)
Cummins, Billy H. (Nederland, TX)
Startz, Ambrose J. (Groves, TX)
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Texaco, Inc. (New York, NY)
C10G67/04; C10G67/14; (IPC1-7): C10G13/04
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US Patent References:
3562149N/A1971-02-09Bryson et al.
3308055Hydrocracking process producing lubricating oil1967-03-07Kozlowski
3285848Preparing dissimilar oils by hydrocracking1966-11-15Donaldson et al.
3242068Production of lubricating oil1966-03-22Peterson
3142635Production of lubricating oils1964-07-28Coonradt et al.
3142634Preparation of multi-grade lubricating oil1964-07-28Ireland et al.
2787582Production of lubricating oils1957-04-02Watkins et al.
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Whaley, Ries Knox Robert T. H. C. G.
1. A course of for the production of a lubricating oil of specified flash point and viscosity which comprises subjecting a crude lubricating oil to catalytic hydrocracking, distilling the hydrocracked product to remove material boiling as much as about 600°F., subjecting the hydrocracked fraction boiling above about 600°F. to extra distillation to acquire a lubricating oil having a predetermined flash point, distilling mentioned lubricating oil of predetermined flash point until a heart minimize is obtained having considerably the identical viscosity as mentioned fraction boiling above about 600°F., returning the remainder of the hydrocracked fraction boiling above mentioned coronary heart minimize to the hydrocracking zone and dewaxing stated coronary heart reduce.
2. The technique of declare 1 through which the guts minimize is subjected to solvent extraction for the removal of aromatic hydrocarbons previous to being dewaxed.
Three. The technique of declare 1 through which the crude lubricating oil is a wax distillate.
4. The means of declare 1 in which the crude lubricating oil is a deasphalted residuum.
5. The strategy of claim 1 by which the hydrocracking catalyst comprises a bunch VIII steel or compound thereof supported on an amorphous inorganic oxide having a floor area of at least 250 m2 /g and a pore volume of at the very least 0.5 cc/g.
6. The means of claim 5 during which the amorphous inorganic oxide includes a mixture of silica and alumina.
7. The technique of claim 6 in which the mixture of amorphous inorganic oxide includes between 2 and 15 wt. % silica.
Eight. The strategy of claim 2 wherein the solvent is furfural.
9. The means of claim 2 through which the solvent is N-methyl-2-pyrrolidone.
This invention relates to the manufacturing of improved petroleum oils. Extra particularly it is worried with the manufacturing of base oils of high viscosity index suitable for mixing into multigrade lubricating oils, automated transmission fluids and different specialty oils requiring high viscosity index. In one in all its more specific features, it is worried with the production of high viscosity index lubricating oils in good yield from lubricating oil charge stocks utilizing a course of sequence which includes in a preferred embodiment hydrocracking, selective fractionation and dewaxing.
Various steps for the refining of lubricating oils such as distillation, solvent refining, solvent dewaxing, acid treating and clay contacting are well-known. When residual sort oils are being processed, a preliminary step of deasphalting can be usually required.
Within the processing steps listed above, distillation is employed as a technique of separating a crude oil into fractions of varied viscosities, solvent refining with, for example, furfural, sulfur dioxide or N-methyl-2-pyrrolidone is ordinarily used as a technique of eradicating aromatic compounds and thereby improving the viscosity index, solvent dewaxing using for instance a mixture of methyl ethyl ketone and toluene is used to improve low temperature properties by decreasing the pour level of the oil and clay contacting is used typically as a final step to further enhance the coloration and to neutralize the oil, after it has been acid handled to enhance coloration, oxidation and heat stability.
In a typical operation, a crude oil is topped under atmospheric pressure to supply light distillates similar to naphtha, kerosene and atmospheric gas oils and an atmospheric diminished crude which is then vacuum distilled to produce lube oil distillates with the residue from the vacuum distillation being deasphalted to yield residual lubricating stocks. Conventionally, the various lube oil fractions are then additional processed by solvent refining and dewaxing. With the advent of mild hydrogenation, acid treating and clay contacting have kind of fallen into disuse.
Due to the increasing demand for the lighter grade lubricating oils it has been found advantageous to convert the heavier oils to the extra helpful lighter merchandise by hydrocracking, or extreme hydrotreating. Not solely does this end in a rise in yield of desired lube oil fractions however because of the excessive hydrogen pressures concerned which lead to a reduction within the aromatic content of the oil, hydrocracking and hydrotreating have been proposed as replacements for solvent refining.
Conventionally, when a crude lubricating oil is hydrocracked, the effluent from the hydrocracking zone is handed by means of a high strain separator for elimination of a hydrogen-wealthy gas then via a low strain separator for removal of low molecular weight usually gaseous hydrocarbons. The balance of the effluent is then sent to a fractionator where, to obtain a hydrocracked lube oil having a passable flash point, the material boiling below about 600°F. is removed. The 600°F+ materials is then considered as product. One drawback to this technique of operation is that whether it is desired to vary the product viscosity it is critical to vary the reaction situations or to make use of a charge inventory from a unique source or each. Nevertheless, a change within the response situations additionally produces change in the product viscosity index.
It is an object of the present invention to produce lubricating oils of specified flash level and viscosity with out changing the hydrocracking response situations or conversely, to vary the hydrocracking response situations while continuing to produce a product of constant specifications.
In keeping with our invention a crude petroleum lubricating oil is subjected to hydrocracking to enhance its viscosity index, the hydrocracked product is subjected to selective fractionation, the specified fraction is dewaxed and that portion boiling above the specified fraction is recycled to the hydrocracking zone.
The process of the invention may be utilized to a wide range of petroleum feedstocks. For instance, the feed could also be obtained by subjecting a vacuum residuum to deasphalting with a low molecular weight hydrocarbon such as propane or butane. The deasphalted residuum can then be hydrocracked. It is usually doable to use a wax distillate as feed to the hydrocracking stage. The feed whether or not obtained by distillation or by deasphalting a vacuum residuum may be subjected to hydrocracking. It’s also potential to make use of as the feed a lubricating oil fraction which has been obtained from a residuum similar to an atmospheric residuum or vacuum residuum by a simultaneous deasphalting-solvent refining process by which the residuum is treated not with the conventional low molecular weight hydrocarbon deasphalting brokers however with a solvent akin to furfural or N-methyl-2-pyrrolidone and the raffinate of diminished aromatic and asphalt content is charged to the hydrocracking zone.
The reaction situations for the hydrocracking may be assorted depending on the product desired and on the cost stock. Typical reaction conditions include a temperature of about 700°-900°F., preferably 750°-850°F. The hydrogen partial pressure may vary between about 500 and 5000 psig, a most popular range being from 1500 to 3000 psig. Space velocities may fluctuate between about zero.1 and 3.Zero v/v/hr. with a most well-liked vary being 0.2-1.0 Hydrogen rates of from a thousand-10,000 SCFB have been discovered passable though charges of 3000-7000 SCFB are most well-liked.
Hydrogen from any suitable supply equivalent to electrolytic hydrogen, hydrogen obtained from the partial combustion of hydrocarbonaceous materials followed by shift conversion and purification or catalytic reformer by-product hydrogen may be used. The hydrogen ought to have a purity of between about 50 and 100% with hydrogen purities of at the very least sixty five quantity % being most well-liked, a very preferred range being 70-95% purity.
The oil and hydrogen ordinarily are preheated and brought into contact with a particulate catalyst. The catalyst may be in the type of a fixed bed, a moving mattress, a fluidized bed or may be slurried with the oil. Within the case of a set bed, hydrogen stream could also be upward or downward by way of the reactor as stands out as the stream of the oil. In a selected embodiment, both the oil and a portion of the hydrogen are launched at the top of a reactor containing a set bed of the catalyst, the steadiness of the hydrogen being launched at intermediate factors in the reactor for cooling purposes.
The catalyst for the hydrocracking step preferably comprises as a hydrogenating part a compound of a gaggle VI steel reminiscent of molybdenum, chromium or tungsten or a compound of a group VIII metal akin to cobalt, iron or nickel and mixtures thereof. Ordinarily the catalyst is charged to the reactor in oxide type although it can be anticipated that some reduction and some sulfidation take place during the course of the process in order that after being on stream for some time, the catalyst might be a mixture of the steel, the metal sulfide and perhaps the oxide. If desired, the catalyst after being charged to the reactor however previous to the establishment of the on-stream interval could also be transformed no less than partly to the sulfide type for instance by contact with a fuel comparable to a mixture of hydrogen and sulfiding agent, e.g. hydrogen sulfide, methyl mercaptan or carbon disulfide at an elevated temperature, e.g. 400°F. The group VIII metallic could also be current in an amount various from 1 to 20% by weight of the total catalyst composite, ideally 2-15% and the group VI metallic could also be current in an quantity ranging from about 5-40%, preferably 7-25%. Most popular combos are nickel-tungsten, nickel-molybdenum and cobalt-molybdenum.
The hydrogenating part is supported on a refractory inorganic oxide resembling “hydrogen type” or decationized zeolite Y, alumina, zirconia, silica or magnesia and mixtures thereof optionally promoted with an acidic materials reminiscent of boron oxide or a halogen.
Advantageously, the catalyst has a surface space of no less than 150 m2 /g, a pore volume of at the very least zero.5 cc/g a significant portion of the pore volume being made up of pores having an average pore diameter between 50 and a hundred A. The upper limit of the floor area and pore quantity is governed by the hardness and ruggedness of the catalyst. As a sensible matter, for industrial installations the place the catalyst is used in models able to processing several thousand barrels of charge per day, the surface space probably should not exceed about 600 m2 /g and the pore volume should not exceed about zero.8 cc/g.
The catalyst which could also be within the form of pellets, extrudates or spheres, could also be prepared by any of the methods well known within the art, comparable to by impregnating the support with an answer of a salt of one of the metals, filtering, drying after which if desired impregnating with an answer of a salt of one other metallic, filtering, drying and calcining in a way well-known in the artwork.
The effluent from the hydrocracking zone is cooled and, in a single embodiment of the invention, hydrogen-wealthy gas is separated therefrom and recylced to the hydrocracking zone. Optionally, the hydrogen-rich stream is treated to remove any hydrogen sulfide and ammonia contained therein or a portion thereof may be bled from the system to forestall the construct-up of hydrogen sulfide, ammonia and/or low molecular weight hydrocarbons. Hydrogen is added to the recycle stream to change that consumed by the hydrocracking and if necessary to exchange any hydrogen purged from the system. The stability of the hydrocracking zone effluent then is passed to a low pressure separator for the removal of low molecular weight hydrocarbons and then to a fractionator for removal of hydrocarbons boiling under about 600°F. The 600°F+ materials could also be sent to a second fractionator to acquire a lube oil fraction of the specified flash level and viscosity or the low stress separator bottoms may be fractionated to supply suitable flash level and viscosity material in the initial fractionator. The specified flash point is obtained by eradicating the sunshine ends and an oil of the specified viscosity could also be removed from the fractionator as a side stream or coronary heart minimize. The high viscosity bottoms might then be returned to the hydrocracking zone.
By following the process outlined above, the deficiencies of the prior artwork are overcome. In standard processing, if it were desired to regulate a lube oil hydrocracking course of to produce a product oil of higher viscosity the severity of the hydrocracking reaction conditions would be decreased leading to the upper viscosity product but the product viscosity index could be lower. However, by the process of our invention it is feasible to provide higher viscosity lube oils with out sustaining any loss in the viscosity index of the product.
Advantageously, if it is desired to produce a lube oil having stability to ultra violet light, the oil should be subjected to a solvent extraction therapy using a selective solvent comparable to furfural or N-methyl-2-pyrrolidone in any typical liquid-liquid contacting apparatus such as a packed column, a centrifugal contactor, a rotating disc contactor or the like. The solvent extraction is carried out at any stage of the process after the hydrocracking, preferably instantly previous to dewaxing.
The following examples are submitted for comparative and illustrative functions only.
In this example, which is representative of conventional processing, the charge is a deasphalted residuum having the next characteristics:
Desk 1 ______________________________________ Gravity, °API 22.4 Viscosity SUS, 100°F. 4205 210°F. 182.2 Viscosity Index eighty one ______________________________________
Hydrocracking of the cost oil is effected by passing it downwardly with hydrogen through a bed of catalyst pellets containing 2.3 wt. % cobalt, 10.3 wt. % molybdenum, three.9 wt. % silica and seventy nine.7 wt. % alumina having a pore volume of 0.Sixty three cc/g and a surface area of 290 m2 /g at a temperature of 805°F., a stress of 1500 psig, 5000 SCFB of 95% purity hydrogen at an hourly space velocity of 0.5 volumes of charge oil per quantity of catalyst per hour. The 600°F.+ portion of the product, obtained in sixty three.Eight quantity per cent basis cost to the hydrocracker has the next traits:
Table 2 ______________________________________ 600°F.+ dewaxed ______________________________________ Gravity, °API 30.Eight 28.Zero Viscosity, SUS, 100°F. 128.1 127.Three 210°F. 42.7 41.9 Viscosity Index 123 108 Flash pt., °F. 335 Pour level, °F. -5 ______________________________________
This instance follows the process of our invention wherein a excessive viscosity oil having considerably the identical flash point as that obtained in Example I is produced without incurring a loss in viscosity index. The circulation differs from that of Instance I in that the cost includes a recycle fraction obtained by fractionating the hydrocracked product to produce a heart minimize having an appropriate flash level and the specified (pre-dewaxed) viscosity. That is accomplished by topping the 600°F.+ hydrocracked fraction to obtain an oil of suitable flash point and slicing out an intermediate fraction which, when dewaxed can have the specified viscosity leaving still bottoms which are recycled and introduced with fresh feed to the hydrocracking zone. The fractionator is operated at a mean vacuum of 29.2 inches of mercury and a maximum temperature of 680°F. The cost, together with recycle, has the next traits:
Desk 3 ______________________________________ Gravity, °API 23.2 Viscosity, SUS, 100°F. 3034 210°F. 164.Zero Viscosity index ninety two ______________________________________
Hydrocracking circumstances, using the identical catalyst as in Instance I, are a temperature of 819°F., a pressure of 1500 psig a space velocity of zero.5 v/v/hr. and a hydrogen fee of 5000 SCFB. The 600°F.+ portion of the product, obtained in a yield of seventy two.4 vol. % has the next traits:
Desk 4 ______________________________________ Gravity, °API 31.2 Viscosity, SUS, 100°F. 162.7 210°F. Forty six.5 Viscosity Index 141 ______________________________________
The 600°F.+ portion is then fractionated, 2.Zero% of the feed to the fractionator being eliminated overhead to extend the flash level to the specified degree, a coronary heart minimize of 88 volume % of the feed to the fractionator being removed because the oil having the specified viscosity stage and the 10 quantity % bottoms being replaced to the hydrocracking zone. The heart reduce, which is obtained in 64 volume % yield foundation feed to the hydrocracking zone, has the next characteristics before and after dewaxing as tabulated under:
Table 5 ______________________________________ coronary heart lower dewaxed ______________________________________ Gravity, °API 31.7 28.1 Viscosity, SUS, 100°F. 132 149 210°F. Forty three.1 43.8 Viscosity Index 124 113 Flash level, °F. 375°F. Orifice ripple Pour level, °F.
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