PRODUCTION OF LOW POUR POINT LUBRICATING OILS

Abstract: Lubricating oils are prepared by a process whereby a hydrocarbonaceous feedstock is hydrocracked and subsequently dewaxed over a crystalline silicoaluminophosphate SAPO-11 containing platinum and/or palladium.

Description: PRODUCTION OF LOW POUR POINT LUBRICATING OILS BACKGROUND OF THE INVENTION This invention relates to a process for prepara¬ tion of lubricating oil stocks. In particular, it relates to a specific combination of unit processes whereby a hydrocarbonaceous feedstock is hydrocracked and subse¬ quently dewaxed using a specific crystalline silicoalumi¬ nophosphate catalyst. The lube oil stocks so produced have a relatively low pour point, and excellent viscosity and viscosity index (VI) properties. High-quality lubricating oils are critical for the machinery of modern society. Unfortunately, the supply of natural crude oils having good lubricating pro¬ perties, e.g., Pennsylvania and Arabian Light feedstocks, is not enough to meet the demand. Additionally, because of uncertainties in world crude oil supplies, it is neces¬ sary to be able to produce high-quality lubricating oils efficiently from ordinary crude feedstocks. Numerous processes have been proposed to produce lubricating oils by upgrading the ordinary and low-quality stocks which ordinarily would be converted into other products. The desirability of upgrading a crude fraction normally considered unsuitable for lubricant manufacture into one from which good yields of lubes can be obtained has long been recognized. Hydrocracking processes have been proposed to accomplish such upgrading. U.S. Patent Nos. 3,506,565, 3,637,483 and 3,790,472 teach hydrocrack¬ ing processes for producing lubricating oils. Hydrocracked lubricating oils generally have an unacceptably high pour point and require dewaxing. Sol¬ vent dewaxing is a well-known and effective process but expensive. More recently, catalytic methods for dewaxing have been proposed. U.S. Patent No. Re. 28,398 discloses dewaxing petroleum charge stocks using ZSM-5 type zeolites. U.S. Patent No. 3,755,145 discloses a process for preparing low pour point lube oils by hydrocracking a lube oil stock using a catalyst mixture comprising a con¬ ventional cracking catalyst and ZSM-5. 5 It has also been suggested that in order to improve the oxidation resistance of lubricants it is often necessary to hydrogenate or hydrofinish the oil after hydrocracking, with and without catalytic dewaxing as illustrated in U.S. Patents Nos. 4,325,805; 4,347,121; 10 4,162,962; 3,530,061; and 3,852,207. U.S. Patents Nos. 4,283,272 and 4,414,097 teach continuous processes for producing dewaxed lubricating oil base stocks includ¬ ing hydrocracking a hydrocarbon feedstock, catalytically dewaxing the hydrocrackate and hydrofinishing the dewaxed ^5 hydrocrackate. These patents teach the use of catalysts comprising zeolite ZSM-5 and ZSM-23 respectively for the dewaxing phase. All the foregoing patents indicate the state of the hydrocracking, dewaxing and stabilization art and are 2 incorporated herein by reference as background. A problem with the prior art processes for pro¬ ducing high-quality lubricating oils is the fact that the dewaxing processes used therein, such as when using dewax¬ ing catalyst ZSM-5, function by means of cracking reac- 25 tions, and therefore a number of useful products become degraded to lower molecular weight materials. For exam¬ ple, waxy paraffins may be cracked down to butane, pro¬ pane, ethane and methane and so may the lighter n-paraffins which do not, in any event, contribute to the 3Q waxy nature of the oil. Because these lighter products are generally of lower value than the higher molecular weight materials, it would obviously be desirable to limit- the degree of cracking which takes place during the cata¬ lytic dewaxing process. Also, the products obtained by 35 the process of this invention have better viscosities and viscosity indexes at a given pour point as compared to the prior art processes using alumino-silicate zeolites such as ZSM-5. 40 SUMMARY OF THE INVENTION In accordance with the present invention, there has been discovered a process for preparing lubricating 05 oils which comprises (a) hydrocracking in a hydrocracking zone a hydrocarbonaceous feedstock to obtain an effluent comprising a hydrocracked oil; and (b) catalytically dewaxing in a catalytic dewaxing zone the hydrocracked oil 10 of step (a) with a catalyst comprising a crystalline silicoaluminophosphate SAPO-11 and a metal selected from platinum or palladium. Another embodiment of this invention includes an additional step of stabilizing said dewaxed hydrocrackate 15 by catalytic hydrofinishing. It has been discovered that the above combina¬ tion of processing steps produces a high-quality lubricat¬ ing oil from straight run crude oils as well as from low quality hydrocarbonaceous feeds. The first step is hydro¬ 20 cracking which increases the viscosity index of the feed¬ stock by cracking and hydrogenating the aromatic compounds present in the feed. Hydrocracking also reduces the nitrogen content of the feed to a very low level. After the hydrocracking, a catalytic dewaxing step using crys- 2c talline silicoaluminophosphate SAPO-11 containing platinum or palladium or combinations thereof takes place. Combin¬ ing the first hydrocracking step with the second catalytic dewaxing step makes the dewaxing .process extremely effi¬ cient since the activity of the dewaxing catalyst appears •J Q to increase as the nitrogen level decreases. The crystalline silicoaluminophosphate SAPO-11 catalyst gives improved lube yield and VI because it reduces pour point by a different mechanism than conven¬ tional dewaxing catalyst such as ZSM-5. The crystalline silicoaluminophosphate dewaxing catalyst is shape selec¬ tive in that it appears to isomerize normal and slightly branched chain paraffins and cycloparaffins without much cracking of highly branched paraffins. While the n-paraffins, slightly branched paraffins and cyclo- Q paraffins undergo some cracking or hydrocracking, the degree of cracking which occurs is, however, limited so that the gas yield is reduced thereby preserving the eco¬ nomic value of the feedstock. Many of the prior art cata¬ lysts crack both the highly branched as well as the normal paraffins to lighter products and gases. Because these lighter products are generally of lower value than the higher molecular weight materials, it would obviously be desirable to limit the degree of cracking which takes place during the process. According to a preferred embodiment of the present invention, the first step of the process, hydro¬ cracking, is carried out to reduce the nitrogen content of the feed to less than 50, preferably less than 10, and most preferably less than about 1 ppmw. Especially good results, in terms of activity and length of catalyst cycle (period between successive regenerations or start-up and first regeneration) , are experienced when the feed con¬ tains these lower levels of organic nitrogen. Among other factors, the present invention is based on the discovery that improved lubricating oil yields may be obtained by a process comprising hydrocrack¬ ing followed by dewaxing using a catalyst comprising SAPO-11 and platinum or palladium. The main purpose of the hydrocracking step is to upgrade VI whereas the main purpose of the dewaxing step is to reduce pour point. With prior art processes, the hydrocracker must upgrade VI more than necessary to meet final product specifications. This is because conven¬ tional dewaxing catalysts, such as ZSM-5, reduce VI during dewaxing. However, SAPO-11 in combination with platinum or palladium, gives improved VI for any given hydrocracker product, i.e., it does not reduce VI of the hydrocrackate as much as the conventional dewaxing catalysts. Thus, with SAPO-11, the hydrocracking step can be operated at lower severity (less conversion) to produce a dewaxer feed of lower VI relative to conventional processing, since subsequent VI loss in the dewaxer will be less than with conventional catalysts. The lower severity for the 01 hydrocracking step improves the lube yield from that step. The improvements in this invention comes not only from increased lube yield after dewaxing but also from 05 increased lube yield after hydrocracking. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a ternary diagram showing the composi¬ tional parameters of the silicoaluminophosphates of U.S. 10 Patent No. 4,440,871 in terms of mole fractions of sili¬ con, aluminum and phosphorus. FIG. 2 is a ternary diagram showing the pre¬ ferred compositional parameters of the silicoaluminophos¬ phates of mole fractions of silicon, aluminum and phos- • c phorus. FIG. 3 is a graph showing a comparison for a crystalline silicoaluminophosphate SAPO-11 catalyst used in the dewaxing step of the process of this invention and a ZSM-5 catalyst with respect to lube yield at a given 0 pour point. FIG. 4 is a graph showing a comparison for a crystalline silicoaluminophosphate catalyst SAPO-11 used in the dewaxing step of the process of this invention and a ZSM-5 catalyst with respect to viscosity index at a _ given pour point. FIG. 5 is a graph showing a comparison for a crystalline silicoaluminophosphate catalyst SAPO-11 used in the dewaxing step of the process of this invention and a ZSM-5 catalyst with respect to viscosity at a given pour 0 point. DETAILED DESCRIPTION The hydrocarbonaceous feeds from which lube oils are made usually contain aromatic compounds as well as normal and branched paraffins of very long chain lengths. 5 These feeds usually boil in the gas oil range. Preferred feedstocks are vacuum gas oils with normal boiling ranges in the range of 350°C to 600°C, and deasphalted residual oils having normal boiling ranges from about 480°C to 650°C. Reduced topped crude oils, shale oils, liquified 0 coal, coke distillates, flask or thermally cracked oils, at ospheric residua, and other heavy oils can also be used. The first step in the processing scheme is hydrocracking. In commercial operations, hydrocracking can take place as a single step process, or as a multi- step process using initial denitrification or desulfuri- zation steps, all of which are well known. Typically, hydrocracking process conditions include temperatures in the range of 250°C to 500°C, pres¬ sures in the range of about 425 to 3000 psig, or more, a hydrogen recycle rate of 400 to 15,000 SCF/bbl, and a LHSV (v/v/hr) of 0.1 to 50. During the hydrocracking step there are conver¬ sions of at least 10% to products boiling below 350°C. Catalysts employed in the hydrocracking zone or zones include those having hydrogenation-dehydrogenation activity, and active cracking supports. The support is often a refractory inorganic oxide such as silica-alumina, silica- alumina-zirconia and silica-alumina-titania composites, acid-treated clays, crystalline alu inosilicate zeolitic molecular sieves (such as Zeolite A, faujasite. Zeolite X and Zeolite Y) , and combinations of the above. Hydrogenation-dehydrogenation components of the hydrocracking catalyst usually comprise metals selected from Group VIII and Group VIB of the Periodic Table, and compounds including them. Preferred Group VIII components include cobalt, nickel, platinum and palladium, particu¬ larly the oxides and sulfides of cobalt and nickel. Pre¬ ferred Group VIB components are the oxides and sulfides of molybdenum and tungsten. Thus, examples of hydrocracking catalysts which are preferred for use in the hydrocracking step are the combinations nickel-tungsten-silica-alumina and nickel-molybdenum-silica-alumina. A particularly preferred hydrocracking catalyst for use in the present process is nickel sulfide/tungsten sulfide on a silica-alumina base which contains discrete metal phosphate particles (described in U.S. Patent No. 3,493,517, incorporated herein by reference). Hydrocracking catalysts can vary in their activities for hydrogenation and cracking and in their 05 ability to sustain high activity during long periods of use depending upon their compositions and methods of pre¬ paration. There are any number of catalysts which are known to the art and which can be selected for use in the hydrocracking step based on operating conditions and feeds 10 to optimize the hydrocracking operation. The hydrocracking process step is performed to yield a hydrocrackate having a total nitrogen content preferably of less than about 50 ppm (w/w) . Standard hydrocracking procedures can easily achieve this nitrogen ^ - level, especially where the feed is subject to an initial partial denitrification process. Preferably, the nitrogen content of the hydrocrackate is as low as is consistent with economical refinery operations, but is preferably less than 10 ppm and more preferably less than about 1 ppm (w/w) . 20 The hydrocracking step yields two significant benefits. First, by lowering the nitrogen content, it dramatically increases the efficiency and ease of the catalytic dewaxing step. Second, the viscosity index is greatly increased as the aromatic compounds present in the 2 feed, especially the polycyclic aromatics, are opened and hydrogenated. In the hydrocracking step, increases of at least 10 VI units will occur in the lube oil fraction, i.e., that fraction boiling above 230°C and more prefer¬ ably above 315°C. - - The hydrocrackate is preferably distilled by conventional means to remove those products boiling below 230°C, and more preferably below 315°C to yield one or more lube oil boiling range streams. Depending upon the particular lube oil desired, for example a light, medium, ■■ '- ■ or heavy lube oil, the raw hydrocrackate may be fraction- ably distilled into light, medium or heavy oil fractions. Among the lower boiling products removed are light nitro¬ gen containing compounds such as NH-,. This yields a lube oil stream with a reduced nitrogen level, so that the 0 crystalline silicoaluminophosphate SAPO-11 in the dewaxing catalyst achieves maximum activity in the dewaxing step. Lubricating oils of different boiling ranges can be pre¬ pared by the process of this invention. These would include light neutral, medium neutral, heavy neutral and bright stock, where the neutral oils are prepared from distillate fractions and bright stock from residual fractions. The great efficiency of the present invention comes in part from the combination of hydrocracking to produce a very low nitrogen, high viscosity index stock which is then extremely efficiently dewaxed to achieve a very low pour point and improved viscosity and viscosity index. It can be appreciated that the higher the activity of the dewaxing catalyst, the lower the reactor tempera¬ ture necessary to achieve a particular degree of dewaxing. A significant benefit is, therefore, the greater energy savings from using the enhanced efficiency catalyst and usually longer cycle life. Additionally, since the crys¬ talline silicoaluminophosphate SAPO-11 dewaxing catalyst is shape-selective it reacts preferentially with the waxy components of the feedstock responsible for high pour points, i.e., the normal paraffins as well as the slightly branched paraffins and alkyl substituted cycloparaffins which comprise the so-called microcrystalline wax. As mentioned above, the process combines ele¬ ments of hydrocracking and dewaxing. The catalyst used in the dewaxing step of the process has an acidic component, and a platinum and/or palladium hydrogenation component. The acidic component comprises a SAPO-11 crystalline sili¬ coaluminophosphate, which is described in U.S. Patent No. 4,440,871 and reference is made to this patent for details of this molecular sieve and its preparation, which patent is incorporated totally herein by reference. The SAPO-11 silicoaluminophosphate molecular sieve (SAPO) suitable for use in the instant process com¬ prises a molecular framework of corner-sharing [Siθ2l tetrahedra, [Al0 2 ] tetrahedra and [P0 2 1 tetrahedra, [i.e., (Si χ l y P)θ2 tetrahedral units] , and which functions when combined with a platinum or palladium hydrogenation component to convert at effective process conditions the waxy components to produce a lubricating oil having 05 excellent yield, pour point, viscosity and viscosity index. More specifically, SAPO-11, as referred to here¬ in, comprises a silicoaluminophosphate material having a three-dimensional microporous crystal framework structure of [P0 2 1 , [A10 2 ] and [Siθ2] tetrahedral units whose unit 10 empirical formula on an anhydrous basis is: mR:(Si χ Al y P z )0 2 (1) wherein "R" represents at least one organic templating ,c agent present in the intracrystalline pore system; "m" represents the moles of "R" present per mole of (Si χ Al P z )o 2 and has a value from zero to about 0.3, "x", "y" and "z" represent respectively, the mole fractions of silicon, aluminum and phosphorus, said mole fractions Q being within the compositional area bounded by points A, B, C, D and E on the ternary diagram which is FIG. 1 or preferably within the area bounded by points a, b, c, d and e on the ternary diagram which is FIG. 2, and said silicoaluminophosphate having a characteristic X-ray pow- der diffraction pattern which contains at least the d-spacings (as-synthesized and calcined) set forth below in Table I. When SAPO-11 is in the as-synthesized form "m" preferably has a value of from 0.02 to 0.3. 0 2Θ 9.4-9.65 20.3-20.6 21.0-21.3 5 22.1-22.35 4.02-3.99 m 22.5-22.9 (doublet) 3.95-3.92 m 23.15-23.35 3.84-3.81 m-s All of the as-synthesized SAPO-11 compositions for which X-ray powder diffraction data have been obtained to date 0 have patterns which are within the generalized pattern of the Table II below. TABLE II 2Θ 100 x I/I 0 8.05-8.3 10.98-10.65 20-42 9.4-9.65 9.41-9.17 36-58 13.1-13.4 6.76-6.61 12-16 15.6-15.85 5.68-5.59 23-38 16.2-16.4 5.47-5.40 3-5 18.95-19.2 4.68-4.62 5-6 20.3-20.6 4.37-4.31 36-49 21.0-21.3 4.23-4.17 100 22.1-22.35 4.02-3.99 47-59 22.5-22.9 (doublet) 3.95-3.92 55-60 23.15-23.35 3.84-3.81 64-74 24.5-24.9 (doublet) 3.63-3.58 7-10 26.4-26.8 (doublet) 3.38-3.33 11-19 27.2-27.3 3.28-3.27 0-1 28.3-28.5 (shoulder) 3.15-3.13 11-17 28.6-28.85 3.121-3.094 29.0-29.2 3.079-3.058 0-3 29.45-29.65 3.033-3.013 5-7 31.45-31.7 2.846-2.823 7-9 32.8-33.1 2.730-2.706 11-14 34.1-34.4 2.629-2.607 7-9 35.7-36.0 2.515-2.495 0-3 36.3-36.7 2.475-2.449 3-4 37.5-38.0 (doublet) 2.398-2.368 10-13 39.3-39.55 2.292-2.279 2-3 40.3 2.238 0-2 42.2-42.4 2.141-2.132 0-2 42.8-43.1 2.113-2.099 3-6 44.8-45.2 (doublet) 2.023-2.006 3-5 45.9-46.1 1.977-1.969 0-2 46.8-47.1 1.941-1.929 0-1 48.7-49.0 1.870-1.859 2-3 50.5-50.8 1.807-1.797 3-4 54.6-54.8 1.681-1.675 2-3 55.4-55.7 1.658-1.650 0-2 When used in the present process, the silico¬ aluminophosphate is employed in admixture with at least one of the noble metals platinum, palladium and optionally other catalytically active metals such as molybdenum, nickel, vanadium, cobalt, tungsten, zinc, etc., and mix¬ tures thereof. The amount of metal ranges from about 0.01% to 10% and preferably 0.2 to 5% by weight of the 01 molecular sieve. The techniques of introducing catalyti- cally active metals to a molecular sieve are disclosed in the literature, and preexisting metal incorporation tech¬ 05 niques and treatment of the molecular sieve to form an active catalyst are suitable, e.g., ion exchange, impreg¬ nation or by occlusion during sieve preparation. See, for example, U.S. Patent Nos. 3,236,761, 3,226,339, 3,236,762, 10 3,620,960, 3,373,109, 4,202,996 and 4,440,871 which patents are incorporated totally herein by reference. The metal utilized in the process of this inven¬ tion can mean one or more of the metals in its elemental state or in some form such as the sulfide or oxide and j c mixtures thereof. As is customary in the art of cata¬ lysis, when referring to the active metal or metals it is intended to encompass the existence of such metal in the elementary state or in some form such as the oxide or sulfide as mentioned above, and regardless of the state in ,.. which the metallic component actually exists the concen¬ trations are computed as if they existed in the elemental state. The physical form of the silicoaluminophosphate catalyst depends on the type of catalytic reactor being , employed and may be in the form of a granule or powder, and is desirably compacted into a more readily usable form (e.g., larger agglomerates), usually with a silica or alumina binder for fluidized bed reaction, or pills, prills, spheres, extrudates, or other shapes of controlled Q size to accord adequate catalyst-reactant contact. The catalyst may be employed either as a fluidized catalyst, or in a fixed or moving bed, and in one or more reaction stages. The catalytic dewaxing step of this invention ^ may be conducted by contacting the feed to be dewaxed with a fixed stationary bed of catalyst, with a fixed fluidized bed, or with a transport bed, as desired. A simple and therefore preferred configuration is a trickle-bed opera¬ tion in which the feed is allowed to trickle through a Q stationary fixed bed, preferably in the presence of hydrogen. The dewaxing step may be carried out in the same reactor as the hydrocracking step but is preferably carried out in a separate reactor. The catalytic dewaxing conditions are dependent in large measure on the feed used and upon the desired pour point. Generally, the tempera¬ ture will be between about 200°C and about 475°C, prefer¬ ably between about 250°C and about 450°C. The pressure is typically between about 15 psig and about 3000 psig, pre¬ ferably between about 200 psig and 3000 psig. The liquid hourly space velocity (LHSV) preferably will be from 0.1 to 20, preferably between about 0.2 and about 10. Hydrogen is preferably present in the reaction zone during the catalytic dewaxing process. The hydrogen to feed ratio is typically between about 500 and about 30,000 SCF/bbl (standard cubic feet per barrel), prefer¬ ably about 1,000 to about 20,000 SCF/bbl. Generally, hydrogen will be separated from the product and recycled to the reaction zone. The crystalline silicoaluminophosphate catalyst used in the dewaxing step provides selective conversion of the waxy components to non-waxy components. During pro¬ cessing the waxy paraffins undergo mild cracking reactions to yield non-waxy products of higher molecular weight than compared to products obtained using the prior art zeolite catalyst. At the same time, a measure of isomerization takes place so that not only is the pour point reduced by reason of the cracking reactions described above, but in addition the waxy components become isomerized to form liquid range materials which contribute to a low vis¬ cosity, low pour point product having excellent VI proper¬ ties. Because of the selectivity of the crystalline silicoaluminophosphate catalyst used in the dewaxing step of this invention, the gas yield is reduced, thereby pre¬ serving the economic value of the feedstock. Hydrogen consumption during the dewaxing step of this invention is less compared to prior art processes using conventional dewaxing catalysts because isomeriza- tion does not consume hydrogen and cracking to liquid range products consumes less hydrogen than cracking to 05 gas. The silicoaluminophosphate molecular sieve cata¬ lyst can be manufactured into a wide variety of physical forms. Generally speaking, the molecular sieves can be in 10 the form of a powder, a granule, or a molded product, such as extrudate having a particle size sufficient to pass through a 2-mesh (Tyler) screen and be retained on a 40-mesh (Tyler) screen. In cases where the catalyst is molded, such as by extrusion with a binder, the silico¬ 15 aluminophosphate can be extruded before drying, or, dried or partially dried and then extruded. The molecular sieve can be composited with other material resistant to the temperatures and other condi¬ tions employed in the dewaxing process. Such matrix mate¬ 20 rials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic mate¬ rials such as clays, silica and metal oxides. The latter may be either naturally occurring or in the form of gelatinous precipitates, sols or gels including mixtures 2c of silica and metal oxides. Inactive materials suitably serve as diluents to control the amount of conversion in the dewaxing process so that products can be obtained economically without employing other means for controlling the rate of reaction. The silicoaluminophosphate may be • j O incorporated into naturally occurring clays, e.g., betonite and kaolin. These materials, i.e., clays, oxides, etc., function, in part, as binders for the cata¬ lyst. It is desirable to provide a catalyst having good crush strength, because in petroleum refining the catalyst 5 is often subjected to rough handling. This tends to break the catalyst down into powder-like materials which cause problems in processing. Naturally occurring clays which can be com¬ posited with the silicoaluminophosphate include the mont- 0 morillonite and kaolin families, which families include the sub-ben tonites , and the kaolins commonly known as Dixie, McNamee , Georgia and Florida clays or others in which the main mineral constituent is halloysite , kaolinite , dickite , nacrite or anauxite. Fibrous clays such as halloysite , sepiol ite and attapulg ite can also be used as supports . Such clays can be used in the raw state as originally mined or initially subj ected to calcination , acid treatment or chemical modification . In addition to the foregoing materials , the silicoaluminophosphate can be composited with porous matrix materials and mixtures of matrix materials such as silica , alumina, titania , magnesia, silica-alumina , silica-magnesia , silica-zirconia , silica-thoria , sil ica- beryllia , s ilica-titania, titania-zirconia as well as ternary compositions such as silica-alumi ' no-thoria , silica-alumina-titania, silica-alumina-magnesia and sil ica-magnesia-zirconia. The matrix can be in the form of a cogel. The silicoaluminophosphate catalyst used in the process of this invention can also be composited with other zeolites such as synthetic and natural faujasites, (e.g., X and Y) erionites, and mordenites. It can also be composited with purely synthetic zeolites such as those of the ZSM series. The combination of zeolites can also be composited in a porous inorganic matrix. It is often desirable to use mild hydrogenation (sometimes referred to as hydrofinishing) to produce more stable lubricating oils. The hydrofinishing step can be performed either before or after the dewaxing step, and preferably after. Hydrofinishing is typically conducted at temperatures ranging from about 190°C to about 340°C at pressures from about 400 psig to about 3000 psig at space velocities (LHSV) between about 0.1 and 20 and a hydrogen recycle rates of 400 to 1500 SCF/bbl. The hydrogenation catalyst employed must be active enough not only to hydrogenate the olefins, diolefins and color bodies within the lube oil fractions, but also to reduce the aromatic content. The hydrofinishing step is beneficial in preparing an accept¬ ably stable lubricating oil since lubricant oils prepared from hydrocracked stocks tend to be unstable to air and 05 light and tend to form sludges spontaneously and quickly. Suitable hydrogenation catalysts include conven¬ tional metallic hydrogenation catalysts, particularly the Group VIII metals such as cobalt, nickel, palladium and 10 platinum. The metal is typically associated with carriers such as bauxite, alumina, silica gel, silica-alumina com¬ posites, and crystalline aluminosilicate zeolites. Palla¬ dium is a particularly preferred hydrogenation metal. If desired, non-noble Group VIII metals can be used with ■ c molybdates. Metal oxides or sulfides can be used. Suit¬ able catalysts are detailed, for instance, in U.S. Patent Nos. 3,852,207; 4,157,294; 3,904,513 and 4,673,487, all of which are incorporated herein by reference. The improved process of this invention will now 20 be illustrated by examples which are not to be construed as limiting the invention as described in this specifica¬ tion including the attached claims. EXAMPLES Example 1 2 c SAPO-11 was grown according to U.S. Patent No. 4,440,871 and identified as such by X-ray diffraction analysis. Elemental analysis of the calcined sieve showed it to have the following anhydrous molar composition: 30 The seive was bound with 35% Catapal alumina and made into 1/16-inch extrudate. The extrudate was dried four hours at 250°F, calcined in air for four hours at 850°F, then impregnated with 1 weight percent Pt (as Pt(NH 3 ) 4 Cl 2 *H 2 0) by the pore-fill method. It was then 3 dried overnight at 275°F and calcined in air for eight hours at 850°F. Example 2 A 700-1000°F crude distillate (Table III) was hydrocracked at 770-777°F, 0.60 LHSV, 2200 psig, and 40 6200 SCF/bbl H 2 over a layered catalyst system of 33/62/5 LV% Catalysts A/B/C, described below. Catalyst A was a cogelled catalyst containing about 9% NiO, 21% W0 3 , 8% i0 2 r and 17% ultrastable Y zeolite in a silica-alumina matrix having an Si0 2 / l 2 03 weight ratio of 1. Catalyst B was the same as Catalyst A but contained no zeolite. Both catalysts had about 200 ppm Na. Catalysts of this type can be prepared for example by the method of U.S. Patent No. 3,401,125. Cata¬ lyst C was an impregnated catalyst of about 5% NiO and 18% M0O3 on alumina. The hydrocracked product was fractionated by distillation to produce a predominantly 700-800°F cut (Table IV) and an 800°F+ bottoms (Table V). P/N/A/S, LV% 10.5/36.6/44.5/3.3 Simulated Distillation, LV%, °F P/N/A/S, LV% 27.6/61.6/10.8/0 Simulated Distillation, LV%, °F The Pt/SAPO-11 catalyst of Example 1 was tested for dewaxing a +75°F pour point lube oil (inspections given in Table IV) at 1 LHSV, 2200 psig, and 8M SCF/bbl once-through H 2 . The pour point could be lowered to +15°F at a catalyst temperature of 640°F. Pour point reduction could be increased by raising the catalyst temperature. FIG. 3 compares the 700°F+ lube yield for the catalyst of this invention with that for a conventional ZSM-5 catalyst containing 35% Catapal binder and run at the same space velocity, pressure, and H 2 rate. Here 700°F+ lube yield is defined as: 1 - g 700°F+ (feed) - g 700°F ^ (product) χ 10Q% g 700°F+ (feed) The figure shows a marked advantage in terms of greater yield for the SAPO-11 catalyst. A large viscosity index (VI) advantage was also found (FIG. 4) as was a lower viscosity (FIG. 5). Example 4 The following catalysts were compared for dewax¬ ing a +100°F pour point lube oil (inspections given in Table V) at 1 LHSV, 2200 psig, and 8M SCF/bbl H 2 . (a) the Pt/SAPO-11 catalyst of Example 1 (b) the ZSM-5 catalyst of Example 3 (c) a ZSM-5 catalyst similar to that of Example 3 but impregnated with 0.8 wt.% Pt. Table VI shows advantages for the Pt/SAPO-11 in both yield and VI. It also shows this catalyst to produce much less C4- gas in the cracked product. 01 TABLE VI Catalyst Pt/SAPO-11 ZSM-5 Pt/ZSM-5 05 Catalyst Temper- 690 725 750 650 670 580 610 ature, °F Pour Point, °F +30 +15 +5 +30 +5 +30 +5 Viscosity, CS, 40°C 34.99 36.65 35.91 45.66 50.33 46.72 49.83 10 Viscosity, CS, 100°C 6.234 6.372 6.272 7.124 7.491 7.235 7.419 VI 128 125 125 115 111 115 111 800°F + Lube Yield, Wt% 79.0 77.5 68.0 77 69 78 71 15 P/N/A, LV% 29.3/65.3/ 14.3/78.8/ 5.4 6.9 P/N/A, ndM 77.60/22.34/ 73.21/26.79/ 0.07 0.00 Simulated Distil¬ lation, LV%, °F 20 ST/5 718/769 731/775 723/770 731/784 739/788 631/767 717/779 10/30 793/842 796/841 791/838 806/850 808/851 792/841 801/876 50 875 874 872 881 882 874 896 70/90 909/967 909/968 906/965 914/971 915/974 909/969 918/973 95/EP 995/1062 998/1064 995/1060 999/1067 1003/1064 999/1062 1003/1061 25 01 TABLE VI (Cont'd) 05 Catalyst Pt/SAPO-11 ZSM-5 Pt/ZSM-5 Catalyst Temper¬ 690 725 750 650 670 580 610 ature, °F 10 53.4 39.7 6.9 0 15 20 25 Example 5 Another batch of SAPO-11 was prepared similarly Qc to that of Example 1, except that the molar composition of the anhydrous sieve was: 0.4SiO 2 :Al 2 O 3 :P 2 O 5 . This sieve was bound with alumina and impregnated with 1 weight percent Pt as in Example 1. 10 Example 6 The catalyst of Example 5 was used to dewax the lube oil of Table IV. The results (Table VII) again show the advantage of Pt/SAPO-11 for obtaining high lube yield and VI, as well as low viscosity. 15 TABLE VII Dewaxing +75°F Pour Point Lube Oil at 1 LHSV, 2200 psig, and 8M SCF/bbl H 2 20 Catal st Pt/SAPO-11 (Exam le 5) ZSM-5 25 30 The catalyst of Example 5 was used to dewax the lube oil of Table V. The results are shown in Table VIII. 35 40 TABLE VIII Dewaxing +100°F Pour Point Lube Oil at 1 LHSV, 2200 psig, and 8M SCF/bbl H 2 Catalyst Pt/SAPO-11 (Example 5) ZSM-5 Catalyst Tempera¬ ture, °F 700 725 650 670 Another crude distillate similar to that of Table III was hydrocracked as described in Example 2 above and the product distilled to produce the oil of Table IX. TABLE IX +115°F Pour Point Lube Oil Gravity, °API 36.6 Sulfur, ppm 1.5 Nitrogen, ppm 0.2 Pour Point, °F +115 Viscosity, CS, 100°C 5.307 Flash Point, °F 435 P/N/A/S, LV% 37.4/57.4/5.2/0 Simulated Distillation, LV%, °F ST/5 120/716 10/30 744/803 50 849 70/90 893/953 95/EP 982/1035 Example 9 The Pt/SAPO-11 catalyst of Example 1 was used to Q 5 dewax a +115°F pour point lube oil (inspections given in Table IX) at 1 LHSV, 2200 psig, and 8M SCF/bbl H 2 . Table X compares the results versus those with the same ZSM-5 catalyst described in Example 3, again showing a major advantage for the SAPO-11 catalyst. 10 TABLE X Dewaxing +115°F Pour Point Lube Oil at 1 LHSV, 2200 psig, and 8M SCF/bbl H, 15 Catalyst Pt/SAPO-11 (Example 1) ZSM-5 Catalyst Tempera ture, °F 700 725 750 683 713 20 700°F+ Lube Yield, Wt.% 86.5 79.3 65.0 55.4 48.0 Example 10 25 SAPO-11 was grown similar to that of Example 1 having the following anhydrous molar composition: 0.31 Si0 2 :Al 2 0 3 :P 2 0 5 . The sieve was bound with 35% Catapal alumina and made into 1/16-inch extrudate. The extrudate was dried four 30 hours at 250°F and calcined in air for eight hours at 1000°F. It was then co-impregnated by the pore-fill method with 1% Ni and 3% Mo (using an aqueous solution of Ni(N0 3 ) 2 and ammonium molybdate). It was dried overnight at 250°F and calcined in air for eight hours at 1000°F. ' ^ Example 11 The catalyst of the previous Example 10 was used to dewax the 75°F pour point lube oil of Table IV. It was first presulfided in 1% H 2 S in H 2 for 40 minutes at 600°F, then run at 1 LHSV, 2200 psig, and 8M SCF/bbl once-through 0 H 2 . Inspections on the whole liquid product are shown in Table XI. TABLE XI Dewaxing +75°F Pour Point Lube Oil at 1 LHSV, 2200 psig, and 8M SCF/bbl H 2 Over Ni-Mo/SAPO-ll Catalyst Temperature, °F 725 Pour Point, °F +10 Viscosity, cS, 40°C 13.85 Viscosity, cS, 100°C 3.306 VI 108 700°F+ Lube Yield, Wt.% 91

Claims: WHAT IS CLAIMED IS: 1. A process for preparing a lubricating oil which comprises: (a) hydrocracking in a hydrocracking zone a hydrocar¬ bonaceous feedstock to obtain an effluent comprising a hydrocracked oil; and (b) catalytically dewaxing in a catalytic dewaxing zone the hydrocracked oil with a catalyst comprising a crys¬ talline silicoaluminophosphate SAPO-ll and a metal selected from platinum or palladium. 2. The process of Claim 1 wherein said metal is platinum. 3. The process of Claim 1 wherein the hydrocracked oil to be dewaxed contains less than 50 ppm by weight nitro¬ gen. 4. The process of Claim 1 wherein the hydrocracked oil to be dewaxed contains less than 10 ppm by weight of nitrogen. 5. The process of Claim 1 wherein the metal is present in the range of from 0.01% to 10% based on the weight of the molecular sieve. 6. The process of Claim 1 wherein the hydrocracking step is conducted at a temperature of from 250°C to 500°C, a pressure of about 425 psig to about 3000 psig, a liquid hourly space velocity of from about 0.1 hr. to about 50 hr. -1 , and a hydrogen circulation rate of from 400 to about 15,000 SCF/bbl. 7. The process of Claim 1 wherein the dewaxing step is conducted at a temperature of from about 200°C to 475°C, a pressure of about 15 psig to about 3000 psig, a liquid hourly space velocity of from about 0.1 hr."- 1 - to about 20 hr.~ , and a hydrogen circulation rate of from 500 to about 30,000 SCF/bbl. 8. The process of Claim 1 which further includes hydrogenating the dewaxed product over a hydrogenation cata¬ lyst under hydrogenation conditions.

Inventors: MILLER STEPHEN J, MILLER, STEPHEN, J.
Applicants: CHEVRON RES, CHEVRON RESEARCH COMPANY
Application year: 1988
Main classification: C10G65
IPC codes: C10G45, C10G47, C10G65