EP0202744A2 - Procédé de déparaffinage catalytique - Google Patents

Procédé de déparaffinage catalytique Download PDF

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Publication number
EP0202744A2
EP0202744A2 EP86302486A EP86302486A EP0202744A2 EP 0202744 A2 EP0202744 A2 EP 0202744A2 EP 86302486 A EP86302486 A EP 86302486A EP 86302486 A EP86302486 A EP 86302486A EP 0202744 A2 EP0202744 A2 EP 0202744A2
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Prior art keywords
catalyst
dewaxing
reactor
temperature
zeolite
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EP0202744A3 (fr
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Nai Yuen Chen
Bruce Patrick Pelrine
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ExxonMobil Oil Corp
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Mobil Oil Corp
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
    • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
    • C10G45/60—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used
    • C10G45/64—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used containing crystalline alumino-silicates, e.g. molecular sieves

Definitions

  • This invention relates to methods for the dewaxing of heavy distillates and residual hydrocarbon liquids.
  • U. S. Patent No. Re 28,398 describes a process for catalytic dewaxing with a catalyst comprising a zeolite of the ZSM-5 type and a hydrogenation/ dehydrogenation component.
  • a process for hydrodewaxing a gas oil with a ZSM-5 type catalyst is also described in U. S. Patent No. 3,956,102.
  • a Mordenite catalyst containing a Group VI or Group VIII metal may be used to dewax a distillate from a waxy crude, as described in U. S. Patent No. 4,100,056; U. S. Patent No.
  • 3,755,138 describes a process for mild solvent dewaxing to remove high quality wax from a lube stock, which is then catalytically dewaxed to specification pour point.
  • U. S. Patent No. 4,222,855 to Pelrine et al discloses dewaxing over a ZSM-23 or a ZSM-35 type catalyst.
  • Catalytic dewaxing processes may be followed by other processing steps such as hydrodesulfurization and denitrogenation in order to improve the quality of the product.
  • U.S. Patent No. 3,668,113 describes a catalytic dewaxing process employing a Mordenite dewaxing catalyst which is followed by a catalytic hydrodesulfurization step over an alumina-based catalyst.
  • U. S. Patent No. 4,400,265 describes a catalytic dewaxing/hydrodewaxing process using a ZSM-5 type catalyst wherein gas oil is catalytically dewaxed followed by hydrodesulfurization in a cascade system.
  • the waxy components are cracked by the zeolite into lighter products including paraffins, olefins and aromatics, some of which may remain in the lube oil boiling range.
  • Olefinic products are unstable to oxidation and must be removed. They may be removed by treatments such as hydrofinishing which uses catalysts to saturate the olefins and improve the oxidation stability of .the oil.
  • the hydrofinishing catalysts generally used are mild hydrogenation catalysts, such as a GoMo/Al 2 O 3 type. The color of the oil may also be improved in this hydrofinishing.
  • U. S. Patent No. 4,428,819 to Shu et al discloses a process for hydrofinishing a catalytically dewaxed oil in which the residual wax content of the dewaxed oil is isomerized over a hydroisomerization catalyst.
  • heavier lube fractions contain waxy components comprising normal paraffins, branched paraffins and cyclo paraffins.
  • a shape-selective catalyst such as HZSM-5
  • HZSM-5 is a ZSM-5 type catalyst with only hydrogen attached to-its active sites, rather than metals.
  • lighter products also tend to be either more difficult to crack, such as low molecular weight paraffins, or easier to polymerize, such as low molecular weight olefins. They also possess a tendency to coke more readily than their heavier counterparts, so as to thereby retard the conversion of the heavier molecules to an even greater extent.
  • a catalyst which essentially constitutes a shape selective zeolite for example, a zeolite exemplified by ZSM-5 for the dewaxing of liquid petroleum or lube stocks.
  • aluminosilicate zeolite catalysts such as ZSM-5 or other zeolites having smaller pore openings, are disclosed in U. S. Patent No. 4, 222,855 to Pelrine et aI and in U. S. Reissue Patent No. Re. 28,398 to N. Y. Chen.
  • U. S. Patent No. 4,357,232 to Holland et al discloses a dewaxing process which operates at a temperature not to exceed 675° to 700°F, and which pretreats a dewaxing feedstock in a zeolite sorbent bed, which is a type of guard bed, prior to dewaxing.
  • U. S. Patent No. 4,247,388 to Banta et al discloses treatment of zeolites to reduce an initially high alpha activity to within a range of 55 to 150 alpha prior to use as catalysts in a hydrodewaxing operation.
  • lube dewaxing reactors operate at a start-of-cycle temperature of 282 to 304°C (540° to 580°F), and the operating temperature is increased 1.1 to 6°C by 2 to 10.0°F) per day, depending on feed, catalyst and space velocity, to compensate for decreasing catalyst activity and produce a lube of predetermined pour point. Temperature is increased to an end-of-cycle temperature of 346 to 368°C (655° to 695°F). Then the reactor is shut down and the catalyst regenerated.
  • Dewaxing catalyst regeneration is usually accomplished by high temperature H 2 regeneration, conducted between 482 and 527°C (900 and 980°F).
  • H 2 regeneration conducted between 482 and 527°C (900 and 980°F).
  • the catalyst loses activity with each subsequent regeneration, because a residue is left on the catalyst and the residue deactivates the catalyst.
  • the residue usually contains high amounts of nitrogen, sulfur and oxygen.
  • oxygen regeneration is employed to burn the residue off the catalyst and achieve activity resembling that of fresh catalyst.
  • oxygen or halogen regeneration restores catalyst activity, they are expensive, and the high temperature of regeneration may result in catalyst sintering.
  • Catalyst regeneration is described in U. S. Patent Nos. 3,904,510; 3.986,982; and 3,418,256.
  • the present invention provides a process for dewaxing a waxy hydrocarbon feedstock by catalytically dewaxing the feedstock at elevated temperature and space velocity between 0.1 and 10 LHSV with a shape-selective crystalline zeolite dewaxing catalyst having a Constraint Index of 1-12 to produce a dewaxing product characterized by recycling to the process dewaxed product to provide a recycle to feedstock ratio of 0.5 to 20 and operating the catalytic dewaxing reaction at a temperature of 260 to 316°C.
  • the present process is applicable to feed- stocks, including lube stocks, when a low wax content is desired in the final product and, in particular, is applicable to feeds with pour points higher than 70°F (21 °C).
  • the feeds may be virgin or pretreated hydrocarbons, such as those which have undergone furfural treatment to reduce aromatics content prior to dewaxing.
  • the dewaxing unit 10 operates at a temperature of 260 to 316°C (500 to 600°F) preferably 260 to 302°C (500 to 575°F) a conventional pressure preferably between 170 to 14,000 kPa (100 to 2000 psig) a space velocity between 0.1 and 10 LHSV - (liquid hourly space velocity), preferably 0.25 to 3.0 LHSV.
  • Hydrogen is preferably provided in hydrogen stream 4, in at least 90- volumes H2/volume liquid at standard conditions, V/V, (500 SCF/bbl).
  • the product stream 26 may then pass to downstream processing, such as hydrofinishing, to produce final product.
  • the dewaxing catalyst is a shape-selective zeolite, preferably ZSM-5, and preferably has an activity measured by an alpha value between 50 and 900, most preferably between 150 and 450, based on the zeolite.
  • Unit 10 may contain one or more reactors in series or parallel.
  • the reactors are preferably downflow fixed bed reactors.
  • hydrogen addition provides 90 to 1,800 V/V (500 to 10,000 SCF/bbl).
  • the feedstock 2 may pass through a catalyst guard bed (not shown) prior to entering the unit 10.
  • the guard bed removes catalyst poisons, which include cyclic heteroatom compounds, such as phenols.
  • the dewaxing temperature is a critical parameter for increasing cycle length. Dewaxing at low temperature, less than 316°C (600°F). preferably less than 302°C (575°F), favors low aging rates. At dewaxing temperatures above 316°C, aging rates are high, 1.1 to 6°C, (2°-10°F/day). Although an explanation for these observations is not obvious, there may be two competing reactions taking place: dewaxing and poisoning. The aging process is related to diffusion of the poisons into the zeolite and the elimination of active sites and/or bulky poisons on the surface of the zeolite react to become smaller and thus penetrate the pore and poison the active sites. Of course, the dewaxing reaction is still taking place, but at an unfavorable rate.
  • catalyst activity is measured by the alpha test described below.
  • the alpha of the catalyst or zeolite portion of the catalyst may be measured, wherein catalyst alpha equals zeolite alpha multiplied by weight fraction of zeolite on catalyst. Therefore, combining low temperature and high alpha value reduces the aging rate and increases cycle time.
  • Fig. 2 shows the invention in which a feedstock 2 is combined with a hydrogen stream 4 and passes into a dewaxing unit 10 under the operating conditions described above.
  • the dewaxing unit 10 produces a dewaxed reactor effluent 12 which passes to a separation unit 20 to form a vapor stream 22 and a liquid stream 24.
  • the liquid stream 24 is separated into a product stream 26 and a recycle stream 28.
  • Recycle stream 28 is then combined with the feedstock 2 and recycled to the catalytic dewaxing unit 10.
  • the recycle ratio of recycle stream 28 to feedstock 2 ranges from about 0.5 to about 20, preferably 1 to 10 and most preferably from 1 to 3.
  • Fig. 3 shows a dewaxing unit 10 comprising a series of catalytic dewaxing reactors 30, 50, 70, with separation units 40, 60 located between the reactors.
  • the feedstock 2 enters dewaxing reactor 30, a portion of the feedstock 2 is cracked to lighter products described below.
  • a first effluent stream 32 from the first reactor 30 passes to the first separation unit 40 to form a first vapor stream 42 and a first liquid stream 44.
  • the first liquid stream 44 then passes to a second catalytic dewaxing reactor 50 to crack a second portion of the first liquid stream 44 to lighter products, described below.
  • the first effluent stream 32 preferably has a desired intermediate pour point between -7° and 38°C (20° to 100°F).
  • the pour points of the first effluent stream 32 and the first liquid stream 44 are within 5.5°C (10°F) of one another.
  • a second effluent stream 52 passes from the second reactor 50 to a second separation unit 60 to produce a second vapor stream 62 and a second liquid stream 64.
  • the second liquid stream 64 then passes to a third catalytic dewaxing reactor 70, wherein a third portion of hydrocarbons from the second liquid stream 64 are cracked to lighter products.
  • the lighter products include C 3 - gases and paraffinic and olefinic fragments, some of which remain in the lube oil boiling range, but most of which are in the 204°C (400°F-) b.p. range.
  • the third reactor 70 produces a third effluent stream 72, which forms the lube product stream 26 which is passed to downstream processing, such as hydrofinishing into final product.
  • the lube product stream 26 typically has a pour point less than -1 °C (30°F), and preferably less than -7°C (20°F).
  • the second effluent stream 52 will preferably have a pour point between that of first effluent stream 32 and that of lube product stream 26.
  • Reactors 30, 50, 70 operate within the same ranges of conditions of temperature, pressure, space velocity and hydrogen feed rate as in the above embodiments and employ a shape-selective catalyst having an alpha between 50 and 900 based on zeolite, preferably between 150 and 450, as in the above embodiments.
  • the overall space velocity is between about 0.1 and about 10 LHSV, and preferably about the same in each reactor 30, 50, 70.
  • the hydrogen to hydrocarbon ratio may range from 90 to 1,800 V/V (500 to 10,000 SCF/bbl), with hydrogen introduced via lines 4, 6 and 8 if desired.
  • the separation units 40, 60 operate by lowering the pressure and flashing the first effluent stream 32 and second effluent stream 52 or by distilling the effluent streams 32, 52.
  • the separation removes those by-product -materials boiling below 204°C (400°F), and preferably those boiling below 316°C (600°F).
  • the compositions of the liquid streams 44, 64 and of the vapor streams 42, 62 may be adjusted, depending upon the final product specification required, by adjusting the temperature and pressure in each of the respective separation units 40, 60.
  • the vapor streams 42, 62 may be sent to downstream processing, such as distillation or hydrotreating.
  • Fig. 3 includes a three-reactor system with inter-reactor separation, two reactors may be adequate.
  • the choice of temperature policy in the reactors may be tailored to achieve a desired product pour point.
  • the temperature of the first reactor may be increased to reduce the first effluent pour point, and thus allow the temperature of the second reactor (or third) to be relatively lower to meet target pour point.
  • space velocity distribution among the reactors may be tailored to achieve a desired product pour point.
  • the advantage of a multiple reactor system with inter-reactor separation includes quick removal of the light by-products of the cracking of hydrocarbon ' waxes. It was found that the light by-products inhibit the cracking of remaining uncracked stock. It is theorized that the light by-products react with the remaining uncracked stock because the light reaction by-products are often olefins which may cyclize and/or alkylate to heavier components in the stock.
  • the light by-products such as light hydrocarbons, especially at 204°C (400°F-) b.p., inhibit the reaction of the heavier uncracked stock because they are more rapidly absorbed into the catalyst volume, thus in effect accelerating the measured rate of catalyst aging for dewaxing to the desired product.
  • the application of the temperature, space velocity and catalyst activity ranges of the invention results in additional benefits when employed in a series of reactors as in the third embodiment.
  • the series of reactors with inter-reactor separation has been found to achieve the same pour point reduction, at lower temperatures and lower catalyst aging rates, as a single reactor without product separation and recycle or multiple reactors without inter-reactor separation. Therefore, multiple reactors with inter-reactor separation may operate longer within the desired ranges of temperature, space velocity and catalyst activity than a single reactor or multiple reactors without inter-reactor separation.
  • the invention is effective for improving the dewaxing performance of -intermediate- pore zeolites, which are described below, because the temperature limitation of the invention reduces catalyst poisoning which forms residues after hydrogen regeneration. The residues are believed to inhibit the dewaxing activity of most dewaxing catalysts.
  • the catalysts employed in the dewaxing units disclosed above may be the same type or different. However, they will possess shape-selective paraffin cracking ability and have high alpha activity of 50 to 900, preferably 150 to 450, based on zeolite. Catalysts that have shape-selective qualities include crystalline zeolite catalysts. These materials may be bound in a variety of matrices, such as those containing silica and alumina or silica or alumina alone. The catalysts may contain up to 15% metals that are known to possess a hydrogenation ability.
  • the preferred hydrogenation components are the noble metals of Group VIII, especially platinum and palladium, but other noble metals, such as iridium, ruthenium or rhodium, may also be used.
  • noble metals such as platinum and palladium
  • other noble metals such as iridium, ruthenium or rhodium
  • non-noble metals such as nickel, rhenium, tungsten, chromium and molybdenum
  • Base metal hydrogenation components may also be used, especially nickel, cobalt, molybdenum, tungsten, copper or zinc.
  • the metal may be incorporated into the catalyst by any suitable method such as impregnation or exchange onto the zeolite.
  • the metal may be incorporated in the form of a cationic, anionic or a neutral complex, such as Pt(NH 3 ) 4 2+ , and cationic complexes of this type are found convenient for exchanging metals onto a zeolite.
  • Anionic complexes are also useful for impregnating metals into the zeolites.
  • a portion of the novel class of zeolites useful for dewaxing are termed medium or intermediate pore size zeolites and are characterized by an effective pore size of generally less than about 7 Angstroms, and/or pore windows in a crystal formed by 10-membered rings.
  • the medium or intermediate pore size zeolites are represented by those zeolites having the structure of ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and TMA - (tetra methyl ammonium) Offretite.
  • intermediate pore size an effective pore aperture probably in the range of about 5 to 6.5 Angstroms when the zeolite is in the H-form.
  • Zeolites having pore apertures in this range tend to have unique zeolite characteristics and to be particularly useful in dewaxing.
  • small pore size zeolites such as erionite and chabazite
  • they will allow hydrocarbons having some branching into the zeolite void spaces.
  • larger pore size zeolites such as the faujasites, they can differentiate between n-alkanes and slightly branched alkanes having, for example, quaternary carbon atoms.
  • the effective pore size of zeolites can be measured using standard adsorption techniques and compounds of known minimum kinetic diameters.
  • the preferred effective pore size range is from about 5.3 to 6.2 Angstroms. See Breck, Zeolite Molecular Sieves, 1974 (especially Chapter 8),and Anderson et al, J. Catalysis 58, 114 (1979), both of which are incorporated herein by reference.
  • the acid cracking activity of zeolite catalysts is conveniently defined by the alpha scale described in an article published in Journal of Cataivsis. Vol. 6, pp. 278-287 (1966).
  • the zeolite catalyst is contacted with hexane under conditions prescribed in the publication, and the amount of hexane which is cracked is measured. From this measurement is computed an "alpha" value which characterizes the catalyst for its cracking activity for hexane.
  • alpha which characterizes the catalyst for its cracking activity for hexane.
  • the alpha scale so described will be used herein to define activity levels for cracking n-hexane.
  • a catalyst with an alpha value less than 1.0, and preferably less than 0.5, will be considered to have substantially no activity for cracking hexane.
  • High alpha catalysts can be made from compositions having a low silica-to-alumina ratio, preferably in the range from 25 to 40.
  • High alpha catalysts may also be made by steaming a zeolite catalyst. Steaming will increase alpha values to some extent, but excess steaming will decrease alpha values.
  • a combination of low silica-to-alumina ratios and steaming would be employed to achieve alphas as high as 900 to 1000 based on zeolite.
  • ZSM-5 is described in U. S. Patent No. 3,702,886 and Re. 29, 948.
  • ZSM-11 is described in U. S. Patent No. 3,709,976.
  • ZSM-35 is described in U. S. Patent No. 4,016,245.
  • the catalysts preferred for use herein include crystalline alumina silicate zeolites having a silica-to-alumina ratio of at least 12, preferably 25 to 40, a Constraint Index of 1 to 12 and acid cracking activity (alpha value) of 50 to 900, preferably 150 to 450, based on zeolite.
  • a suitable shape selective catalyst for a fixed bed reactor is an HZSM-5 zeolite with alumina binder in the form of cylindrical extrudates of about 1 to 5 millimeters.
  • HZSM-5 is a ZSM-5 type catalyst with only hydrogen on the active catalyst sites and no metals on those sites.
  • Zeolites characterized by such Constraint Indices induce profound transformation of aliphatic hydrocarbons to aromatic hydrocarbons in commercially desirable yields and are generally highly effective in conversion reactions involving aromatic hydrocarbons.
  • These zeolites retain a degree of crystallinity for long periods in spite of the presence of steam at high temperature, which induces irreversible collapse of the framework of other zeolites, e.g., of the X and A type.
  • carbonaceous deposits, when formed, may be removed by burning at higher than usual temperatures to restore activity.
  • the zeolites of this class exhibit very low coke forming capability, conducive to very long times on stream between burning regenerations.
  • the silica-to-alumina ratio referred to may be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the ratio in the rigid anionic framework of the zeolite crystal and to exclude aluminum in the binder or in cationic or other forms within the channels. Such zeolites, after activation, acquire an intracrystalline sorption capacity for normal hexane which is greater than that for water, i.e., they exhibit "hydrophobic" properties. It is believed that this hydrophobic character is advantageous in the present invention.
  • the type zeolites described freely sorb normal hexane and have a pore dimension greater than about 5 Angstroms.
  • the structure preferably provides constrained access to larger molecules. It is sometimes possible to judge from a known crystal structure whether such constrained access exists. For example, if the only pore windows in a crystal are formed by 8-membered rings of oxygen atoms, then access by molecules of larger cross-section than normal hexane is excluded and the zeolite is not of the constrained type. Windows of 10-membered rings are preferred, although, in some instances, excessive puckering or pore blockage may render these zeolites ineffective.
  • 12-membered rings do not generally appear to offer sufficient constraint to produce the advantageous conversions, although puckered structures exist, such as TMA offretite, which is a known effective zeolite. Also, structures can be conceived, due to pore blockage or other cause, that may be operative.
  • a simple determination of the "Constraint Index" may be made by passing continuously a mixture of an equal weight of normal hexane and 3-methylpentane over a sample of zeolite at atmospheric pressure, and high temperature.
  • Constraint Index approximates the ratio of the cracking rate constants for the two hydrocarbons.
  • Preferred zeolites are those having a Constraint Index of 1 to 12.
  • Constraint Index (CI) values for some typical zeolites are:
  • Catalytically dewaxing hydrocarbons under a range of operating conditions which include a temperature between 260 to 316°C (500° to 600°F) and a space velocity from 0.1 to 10, and employs a shape-selective crystalline zeolite catalyst having an alpha value between 50 and 900 based on zeolite, will result in longer catalyst cycle length because of lowered catalyst aging rate. Cycle lengths of several months to a year may be expected. Also, by limiting the end-of-cycle reactor temperature to 316°C (600°F), fresh catalyst performance may be restored by simple hydrogen reactivation. By combining the above temperature, space velocity and alpha value range with separation of light by-products from reactor effluents, additional benefits may be achieved.
  • Fig. 2 Separating a vapor stream from a dewaxing unit effluent prior to a second pass over dewaxing catalyst removes components which inhibit further dewaxing and accelerate catalyst aging. This allows the dewaxing unit to operate within the desired temperature range for longer periods of time.
  • the embodiment of Fig. 2 employs product separation and recycle and the embodiment of Fig. 3 employs multiple reactors with inter-reactor separation.
  • the embodiments of both Figs. 2 and 3 separate light by-products to extend the time for operation within the desired temperature range.
  • the methods and apparatus of Fig. 2 is simple to put into practice.
  • the catalyst Prior to testing, the catalyst was sulfided with hydrogen sulfide according to the following - schedule at 2,900 kPa (400 psig):
  • Example 1 multiple pass dewaxing was tested.
  • Commercial lube dewaxing is a single pass multi-phase trickle bed operation. Light products from the selective cracking of waxy molecules also undergo secondary reactions, which may inhibit the rate of the dewaxing reaction.
  • the results of multiple pass dewaxing using the bright stock of Table 1 as the feed were compared with results from Example 2 for a single pass study made at various space velocities.
  • the bright stock, representing the feedstock 2 was dewaxed at 2 LHSV and 2,900 kPa (400 psig) over a catalyst of unsteamed, 0.8mm (1/32”) alumina-bound Ni-ZSM-5-extrudate containing 1 wt % nickel.
  • Hydrogen gas was co-fed at 450 VN (2500 SCF/bbl) with the feedstock 2 to a trickle bed test reactor.
  • the test reactor had an inside diameter of 1.6 cm (5/8"), contained 10 cc of catalyst and had a thermowell 0.3cm (1/8") from its bottom. Reactor temperature was fixed at 285°C - (545 F).
  • the -2°C (28°F) material was subjected to a third pass through the same catalyst at 285°C (545°F) and resulted in a lube product pour point of -13°C (8°F), which represents stream 26.
  • This multiple pass procedure simulates operation of the three reactors 30, 50, 70 in series, as in Fig. 3, and demonstrates that multiple reactors at the same temperature, with inter-reactor separation 40, 60, may yield a product with desired pour point at a temperature of only 285°C (545°F) and a low residence time of 0.67 LHSV.
  • Table 2 shows the product yields, pour points, viscosities and viscosity indices for this multi-pass test. Fig.
  • Example 4 shows the results of Example 1 for the multi-pass tests with respect to time-on-stream in days and product pour points. It is noted that during the second and third passes, the pour points of daily samples declined with time-on-stream, suggesting that the catalyst was being reactivated by the removal of adsorbed poisons. During the line-out period and the second and third passes, the LHSV was maintained at 2 LHSV per pass. This means that the equivalent LHSV- after the second and third passes was approximately 1 and 0.67 LHSV, respectively.
  • Example 2 tests simulate single pass dewax- ings as in the embodiment of Fig. 1. To determine the extent of the inhibitory effect of light by-products discussed in Example 1, the results of Example 1 for multiple pass dewaxing using the bright stock of Table 1 as the feed were then compared with results from Example 2 for single pass study made at various space velocities. At the end of the multiple pass study of Example 1, single pass tests were conducted, in the same reactor over the same catalyst, in which the space velocity was varied between 2 and 0.67, and temperature and pressure held constant at the values of Example 1. Table 2 compares product yields, pour points, viscosities and viscosity indices for both the single and multi-pass tests at corresponding LHSV's. Yields for the multiple pass products are comparable to single pass when based upon cumulative yields. Viscosities and viscosity indices, at near target point, are the same as those found for single pass products.
  • Example 3 tests simulated a recycle process, as shown by Fig. 2. by blending two parts - (by weight) of the third pass product of Example 1 to represent recycle stream 28, with -13°C ((8°F) pour point, with one part of bright stock feed to represent feedstock 2.
  • This blend with a pour point of 20°C (68°F) was processed in the same reactor over the same catalyst as Example 1, still operating at 285°C (545°F), at 2 LHSV based upon the blend, and 0.67 LHSV based upon the raw bright stock.
  • This blend was processed for 3 days and resulted in an average product pour point of -7°C - (19°F).
  • Table 2 lists the average product yield, pour point, viscosity and viscosity index for one of these processing days and compares the data with data for single pass operation without recycle. Thus, recycle under these conditions is more effective for reducing pour point of the blended feed and allows better catalyst activity at lower temperatures than single pass without recycle.
  • Example 4 it is shown that operating the test reactor under much milder conditions than would be required to produce the -7°C (20°F) pour product 26 results in an extremely low catalyst deactivation rate.
  • the same test reactor was operated using the same catalyst type and feed as in Example 1, at a space velocity of 2 LHSV and target pour point of -7°C (20°F) to simulate the embodiment of Fig. 1.
  • a first cycle length of 16 days-resulted, and the aging rate was 2.6°C (4.7°F) per day to a- temperature of 327°C (620°F).
  • the test reactor simulated the first reactor of the multi-reactor system of Fig. 3 by keeping the space velocity constant and lowering the temperature to set the target pour point at 21°C (70°F).
  • Example 5 the bright stock representing feedstock 2 was dewaxed in a reactor to simulate a fixed bed, single stage process, as shown in Fig. 1.
  • the catalyst is 20 cc of the same type Ni-ZSM-5 as in the above examples.
  • the bright stock of Table 1 was dewaxed at 2,900 kPa (400 psig), at a start-of-cycle temperature from 260°C (500°F) to an end-of-cycle temperature of 288°C (550°F), and a hydrogen addition rate of 450 V/V (2500 SCF/bbl) to obtain a target pour point of -7°C - (20°F).
  • the reactor was operated at low temperature, as opposed to conventional operation with a start-of-cycle temperature 33°C (60°F) higher and end-of-cycle of typically 357°C (675°F).
  • the space velocity was 0.5 LHSV, as opposed to the space velocity of 2 LHSV employed in Example 4.
  • Fig. 6 shows the results of the low temperature operation by plotting reactor temperature (°F) to obtain a -7°C (20°F) product vs. time-on-stream - (days).
  • the results indicate that combining the high alpha of 275 on zeolite space velocity of 0.5 LHSV and operating it at low temperature between 260 to 288°C (500 to 550°F) results in a catalyst aging rate of only 0.18°C (0.32°F) per day.
  • Conventional higher temperature operation would be expected to lead to higher aging rates of 2.8°C (5°F) or higher per day. This is indicated by Examples 6 and 7 below at 1 and 2 LHSV, respectively, to produce a -7°C (20°F) pour product.
  • Example 6 employs the feed of Table 1 as in the above examples, over 10 cc of a Ni-ZSM-5 type catalyst in the same reactor as Example 1. Hydrogen partial pressure was maintained at 2,900 kPa (400 psig) and hydrogen feed rate was 450 V/V (2500 SCF/bbl). Temperature was maintained to produce a -7°C (20°F) pour point product.
  • Tests were conducted at 2 LHSV in a single reactor to determine the effect of temperature on catalyst aging rate from a 293°C (560°F) start-of-cycle temperature to 316°C (600°F) and then above 316°C (600°F) to an end-of-cycle temperature of 357°C (675°F). Temperature was maintained to produce a -7°C (20°F) pour point product, while feed, catalyst, test reactor and other operating conditions were the same as in Example 6.
  • Example 8 bright stock representing feedstock 2 was dewaxed in a reactor to simulate the single dewaxing unit 10 of Fig. 1 over a range of conditions from start-of-cycle to an end-of-cycle temperature of 327°C (620°F) and compared with running bright stock under the same conditions, except now running from start-of-cycle to an end-of-cycle temperature of 357°C (675°F), as presently used in commercial practice.
  • 5 gms of Ni-ZSM-5 catalyst, which are taken at 327°C (620°F) end-of-cycle, contain the equivalent of 26 grams per 100 grams catalyst of residue before hydrogen regeneration.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Catalysts (AREA)
EP86302486A 1985-04-18 1986-04-04 Procédé de déparaffinage catalytique Withdrawn EP0202744A3 (fr)

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US72485885A 1985-04-18 1985-04-18
US724858 1985-04-18

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JP (1) JPS61243892A (fr)
AR (1) AR240056A1 (fr)
AU (1) AU5527486A (fr)
BR (1) BR8601744A (fr)
ES (1) ES8706796A1 (fr)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120004477A1 (en) * 2010-06-30 2012-01-05 Exxonmobil Research And Engineering Company Liquid phase distillate dewaxing

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0507325B1 (fr) * 1991-04-05 1996-03-20 Kao Corporation Composition pour désencrage et procédé de désencrage

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3956102A (en) * 1974-06-05 1976-05-11 Mobil Oil Corporation Hydrodewaxing
EP0181066A2 (fr) * 1984-10-29 1986-05-14 Mobil Oil Corporation Procédé pour déparaffiner des distillats lourds et des liquides résiduels

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3956102A (en) * 1974-06-05 1976-05-11 Mobil Oil Corporation Hydrodewaxing
EP0181066A2 (fr) * 1984-10-29 1986-05-14 Mobil Oil Corporation Procédé pour déparaffiner des distillats lourds et des liquides résiduels

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120004477A1 (en) * 2010-06-30 2012-01-05 Exxonmobil Research And Engineering Company Liquid phase distillate dewaxing
US9493718B2 (en) * 2010-06-30 2016-11-15 Exxonmobil Research And Engineering Company Liquid phase distillate dewaxing

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AU5527486A (en) 1986-10-23
JPS61243892A (ja) 1986-10-30
EP0202744A3 (fr) 1988-08-17
ES8706796A1 (es) 1987-07-01
BR8601744A (pt) 1986-12-23
AR240056A1 (es) 1990-01-31
ES554099A0 (es) 1987-07-01
ZA862946B (en) 1987-12-30

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