US 3487005 A
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United States Patent US. Cl. 208-59 6 Claims ABSTRACT OF THE DISCLOSURE A process for the production of low pour point lubricating oils, without recourse to physical wax separation, from a high pour point, nonasphaltic waxy oil containing organic nitrogen and sulfur compounds and boiling mostly above 800 F. which comprises first subjecting the waxy oil to catalytic hydrocracking denitrification under specified conditions, removing NH and H 5 from the reacted material, and then subjecting at least the higher boiling components of the reacted material to catalytic isomerization-hydrocracking under specified conditions in the presence of an nnsulfided naphtha reforming catalyst having no more than moderate acidity, and finally separating from the isomerized material an 800 F.+ bottoms fraction having a pour point at least 30 F. below the pour point of the Waxy oil feed.
CROSS-REFERENCE TO THE RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 477,597, filed Aug. 5, 1965 and now abandoned.
BACKGROUND OF THE INVENTION This invention relates to processes for lowering the pour point of hydrocarbon oils and to processes involving treating lubricating oils with hydrogen in the presence of catalysts.
Hydrocarbon oils to be suitable for use as lubricants are generally required to be sufliciently high boiling to have low volatility and a high flash point. Superior lubricating properties are obtained if the oil is composed primarily of saturated hydrocarbons comprising parafiins and cycloparaflins, with a minimum content of aromatics. The oils are required to flow freely and thus generally must have a pour point not in excess of about +35 F., and more usually pour points of '+15 F., H-5 F., or 0 F. or lower are specified. Many other oil products not designed for use as lubricants, spray oils for example, desirably have these same properties of low volatility, high flash point, high paraffin content, and low pour point.
Normal parafiins and waxes present in virtually all high boiling portions of crude petroleum impart a high pour point to the oil fractions as obtainable directly by distillation, and accordingly the oils must be subjected to a dewaxing step to meet the low pour point specifications. The dewaxing procedures heretofore used have all required at least one step of physically separating Wax from the oil, though a variety of procedures have been developed. Thus the oil may be cooled to a low temperature sufi'icient to crystallize out hard normal paraflin wax, and the wax can then be physically separated by filtration, centrifugation, or like methods. More commonly, solvent dewaxing is employed wherein a solvent, such as a mixture of methylethylketone and benzene is added, which preferentially dissolves the nonwaxy hydrocarbons and lowers the oil viscosity without appreciably 3,487,005 Patented Dec. 30, 1969 lowering the crystallization temperature of the wax, but the Wax must still be separated physically as before. In addition, it is frequently necessary to use mechanically complicated, internally scraped, heat exchangers in the chilling procedures. Other methods have been devised involving forming complexes with the wax molecules, such as in the urea adduction process; but again a physical separation of the wax or wax addu-ct or complex is needed.
The dewaxing methods heretofore used are quite costly to build and to operate because of the large amount of equipment needed for the mechanical handling, which must be done at low throughputs to accomplish the physical wax separation. Thus in a typical process for producing lubricating oils comprising several steps including, for example, solvent extraction, acid treating, hydrofining, clay contacting, and solvent dewaxing, the dewaxing step is more costly than all of the other treating steps combined. Therefore, it would be highly desirable to be able to minimize or eliminate completely the need for dewaxing by physical separation of wax, Which would require that some other means be found for lowering the pour points of the available oils.
SUMMARY The present invention provides a process for lowering the pour point of waxy oils without recourse to any step involving physically separating wax.
The process of the present invention essentially comprises hydrocracking a high pour point waxy oil feed boiling at least partly above 700 F. and substantially free of asphaltic constituents in at least two stages, comprising a hydrocracking-denitrification stage followed by a hydrocracking-isomerization stage, and distilling the hydrocracked oil into fractions including a bottoms fraction having a pour point which is at least 30 F. lower than the pour point of said feed. This is a process for producing lubricating oils having low pour point, without recourse to physical wax separation, from a high pour point waxy oil feed substantially free of asphaltic constituents, containing organic nitrogen and sulfur compounds and boiling mostly above 800 F., which comprises contacting said high pour point waxy oil feed and hydrogen in a first reaction zone with a sulfactive hydrocracking-denitrification catalyst at hydrocracking-denitrification conditions of elevated pressure above 1,000 p.s.i.g.
and temperatures maintained in the range 650-950 F. to convert the organic nitrogen compounds and organic sulfur compounds in said feed to ammonia and hydrogen sulfide respectively and to convert at least 20 percent of said feed to products boiling lower than said feed, removing ammonia and hydrogen sulfide from the first reaction zone effiuent, contacting the substantially nitrogenand sulfur-free product comprising at least the higher boiling components of the efiluent of said first reaction zone and hydrogen in a second reaction zone with an unsulfided naphtha reforming catalyst having no more than moderate acidity under isomerization-hydrocracking conditions of elevate-d pressure above 500 p.s.i.g. and temperatures maintained in the range of 700900 F., with consumption of hydrogen, to convert at least 10 percent to lower boiling materials and separating the effluent from said second reaction zone into fractions including at least a bottoms fraction boiling above 800 F. and Within the boiling range of said waxy oil feed and having a pour point at least 30 F. below the pour point of said high pour point Waxy oil feed. To illustrate the capabilities of the present invention, a bright stock having a pour point of 60 F. can be produced in good yield from a deasphalted waxy residual oil derived from parafiinic crude and having a pour point above F. without at any time subjecting the residual oil to a physical wax separation step in the course of manufacturing the bright stock. It is a characteristic of the process that the highest boiling portion of the hydrocracked oil produced in accordance with the invention has the lowest pour point, and accordingly the invention is ideally suited to the production of low pour point bright stocks from deasphalted residua.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The number and variety of catalytic treatments with hydrogen which have been applied to or proposed for use in treating lubricating oils are legion. Catalytic treat ments with hydrogen have been used or proposed for improving color, color stabiliy, oxidation stability, viscosity, viscosity index, and other properties, as a .substitute for or in addition to the well-known chemical treatments of solvent extraction of aromatics, acid treating, and clay contacting. Suffice it to say, however, that the known processes have all either been applied to oils which had already been subjected to a physical wax separation step or else the product produced from the catalytic hydrogen treating required dewaxing by physical wax separation treatment. The present invention is capable of achieving many of the improvements in oil properties attributed to the prior art catalytic hydrogen treating processes while at the same time achieving the primary objective heretofore not accomplished, namely, obviating the need for any physical wax separation step.
Feedstocks which may be successfully treated in accordance with the invention include high pour point heavy oils, which must boil at least partly above 700 F. More desirably, the oil feed boils mostly above 800 F, and at least partly above 900 F. A preferred feed is at least as heavy as a straight-run vacuum gas oil, and the most preferred feed is a deasphalted residual oil. The oil is required to he nonasphaltic because the asphaltenes, being polynuclear aromatic-type compounds, interfere with the conversion of paraffins in the process of the invention and also tend to rapidly deactivate the catalysts used. The deasphalting treatment applied in preparing the preferred feed may be the type of deasphalting used in preparing heavy catalytic cracker feedstocks; i.e., treatment with a light hydrocarbon solvent, such as propane, butane, pentane, or mixtures thereof, at near the critical point of the solvent. The treatment may be such as to recover as feed the entire so-called maltene fraction, comprising oil and resins, rejecting only the asphaltenes. The deasphalted oil feeds treated in accordance with the invention will have high pour points of above +35 F., and more usually of at least +50 F. Thus a deasphalted oil feed will contain suflicient high melting parafiins such that at least about 10 weight percent of the feed would have to be separated as wax to obtain a pour point of F. by prior art solvent dewaxing methods. Best results are obtained with paraffinic oil feed as contrasted to aromatic oils.
In the first stage of the hydrocracking in accordance with the present invention, the impure high pour point oil feed and hydrogen are passed at elevated pressure above 1,000 p.s.i.g. through a reaction zone to contact therein a sulfactive hydrogenation catalyst having hydrocracking and dentrification activity at temperatures maintained in the range 650900 F. at a space velocity of 0.2l0 LHSV until organic nitrogen and sulfur compounds inherently present in the raw feed are substantially eliminated. The organic nitrogen concentration is the hydrocracked oil should be lowered at least to about p.p.m., preferably to about 1 p.p.m. or less. At the conditions required to accomplish the substantially complete conversion of organic nitrogen to ammonia, substantial hydrocracking of the oil to lower boiling distillates occurs. While it would appear desirable to minimize such hydrocracking conversion so as to maximize the yield of high boiling product, it appears that at least about 20 percent se ve i t the feed to clist l tes o er boiling n the feed is needed to obtain a high overall pour point reduction and to improve the viscosity index of the product. With residual oil feeds, conversion should be at least about 30 percent to distillates boiling below 700 F., and the most preferred conversion range appears to be from about 30 percent to about 60 percent. The conversion is accompanied by the consumption of substantial amounts of hydrogen, amounting usually to about 500 standard cubic feet or more per barrel of oil.
As mentioned, conditions used in the first stage hydrocracking include temperatures of 650-900 F., more desirably 700850 F. The pressure should be at least about 1,000 p.s.i.g. and may range upwards of 5,000 p.s.i.g., with the preferred range being 1,500-4,000 p.s.i.g. The throughput of hydrogen-rich gas, which may be recycled, should be at least 1,000 s.c.f./bbl. of feed, more usually 2,00020,000 s.c.f./bbl., with the preferred range being 4,000l0,000 s.c.f./bbl. The contact time between oil and catalyst'is sufficiently long to accomplish the desired nitrogen removal and hydrocracking, which can generally be accomplished at space velocities of 02-10 volumes of oil per hour per volume of catalyst (LHSV), preferably 0.33 LHSV.
The catalyst used in the first stage hydrocracking may be of the sulfactive hydrogenation type commonly used for desulfurization and denitrification. Suitable catalysts include combinations of the Group VI and Group VIII metals, oxides, or sulfides, associated with porous refractory oxide carriers. Most suitable metals are nickel or cobalt in combination with molybdenum or tungsten, as sulfides. The refractory oxide may be alumina, or combinations of alumina with silica, magnesia, zirconia, titania, and like materials, or combination of such other oxides, for example silica-magnesia. Such catalysts can be prepared in a variety of ways, including preparing the porous carrier first and then impregnating it with solutions of the metal compounds which are later converted to metal oxides by calcining. Particularly good catalysts for use in the first stage hydrocracking can be prepared by coprecipitation techniques wherein all of the components are initially supplied as dissolved compounds in aqueous solutions and coprecipitated together.
The conditions in the first stage hydrocracking should be such as to substantially eliminate organic sulfur compounds by conversion to H 8 in addition to substantially eliminating organic nitrogen compounds by conversion to NH Usually the nitrogen conversion is the more ditficult to accomplish; and, accordingly, if the organic nitrogen content has been reduced to satisfactory levels, the organic sulfur concentration will also have been suificiently reduced. In some rare cases, however, as where the impure oil feed has an unusually high sulfur content and unusually low nitrogen content, it may be possible to achieve a satisfactorily low nitrogen concentration without having removed sufficient sulfur. In those cases, the contacting should be continued until the sulfur concentration has been lowered to below about 50 parts per million.
Some pour point reduction may occur during the hydrocracking with the dentrification catalyst, but not sufficient to lower the pour point of the highest boiling portion of the oil feed from about +35 F. to below +l5 F. unless the conversion is continued far beyond what is needed in accordance with the present invention, thereby greatly reducing product yield. There is evidence that in the first stage hydrocracking normal paraffins are cracked and isomerized to moderately branched isoparaflins which, however, still impart a high pour point to the oil. These isoparaffins are removable by solvent dewaxing techniques and they would have to be so removed in accordance with prior art techniques to obtain an acceptable low pour point product from the oil effiuent of the first stage hydrocracking.
In accordance with the invention, the hydrocracked oil effluent of the first stage is not dewaxed but instead at least a high boiling portion of the oil effluent of the hydrocracking-dentrifica ion Zo e a d hy rog n are p ss d at elevated pressure above 500 p.s.i.g. through a pour point reducing reaction zone, sometimes referred to herein as a hydrocracking-isomerization zone, to contact therein a naphtha reforming catalyst at temperatures maintained in the range 700900 F. until at least about percent of the portion so passed is converted to lower boiling distillates with a net consumption of hydrogen. The oil effluent of the pour point reducing reaction zone is distilled directly into fractions including a highest boiling portion having a low pour point which is at least 30 F. lower than the pour point of the high pour point purified oil passed from the eflluent of the hydrocracking-denitrification reaction zone to the hydrocracking-isomerization reaction zone. Conditions used in the pour point reducing reaction zone include temperatures of 700-900 F., preferably 750-850 F.; pressures of 500-5,000 p.s.i.g., more usually 1,0003,000 p.s.i.g.; hydrogen-rich gas throughput rates greater than 1,000 standard cubic feet per barrel of oil, generally 2,000-20,000 s.c.f./bbl., and preferably 4,000-10,000 s.c.f./bbl. The contact time in terms of liquid hourly space velocity is from 02-10, preferably 0.3-3 LHSV. The conditions are such that at least 10 weight percent of the oil entering this final reaction zone is hydrocracked to lower boiling distillates, and desirably at least about percent hydrocracking conversion is accomplished. The higher the percent conversion to lower boiling distillates, the greater the pour point reduction that is achieved. Particularly with residual oils it appears desirable that the conversion be at least about weight percent or higher, especially if the pour point of the hydrocracked oil recovered from the first stage and passed to the second stage is above about 90 F.
The catalyst employed in the pour point reducing hydrocracking-isomerization zone is described as a naphtha reforming catalyst having no more than moderate acidity, which typically comprises a Group VI metal oxide or a Group VIH metal hydrogenation-dehydrogenation component, desirably a noble metal, preferably platinum or palladium, associated with a porous refractory oxide carrier such as alumina. The term moderate acidity, as used in this specification and the appended claims, means that level of acidity which is possessed by a standard catalyst which comprises essentially alumina promoted with a small amount of platinum metal and 2 weight percent of fluorine. A number of methods of measuring acidity of a catalyst are known. These include titration with indicator dyes, which gives an absolute value, or measurement of degree of isomerization of a hexane sample in the presence of the catalyst, which gives relative acidity values of two or more catalysts. Thus a typical preferred catalyst comprises essentially alumina promoted with 0.7 weight percent of platinum metal and 0.7 weight percent of fluorine. This is a well-known platinum reforming catalyst, but its action is quite different at the conditions used in the pour point reducing zone. There is a net consumption of hydrogen, and instead of forming aromatics from naphthenes, the essential reaction occurring appears to be one of hydrocracking and isomerizing moderately branched isoparafiins to highly branched isoparafiins. The reforming catalyst is an active isomerization catalyst. Nitrogen and sulfur compounds may deactivate such a catalyst, and accordingly these hetero organic compounds are substantially excluded from the oil passed to the sec- 0nd stage by virtue of the desulfurization and denitrification being carried nearly to completion in the first stage. The catalyst need not have fluorine or another halide as the acidifying agent as long as the acidity of the catalyst, from whatever source, does not exceed the acidity of the standard catalys described above; i.e., the catalyst has no more than moderate acidity. Thus, instead of pure alumina or halided alumina as the carrier or support, there may be used a moderately acidic alumina-silica cogel or coprecipitate containing more alumina than silica. For example, good results have been obtained using a 2 percent palladium catalyst on 82 percent alumina-18 percent silica. Other analogous carriers and supports suitable for use will suggest themselves to those skilled in the art. The silica-alumina materials containing more silica than alumina, such as cracking catalysts, are not good supports for the catalysts because they are too strongly acidic and adversely affect selectivity for the isomerization of isoparaflins.
It will be recognized that the contacting of the. oil and hydrogen with the catalysts in the respective reaction zones maybe carried out in a variety of well-known ways, including the use of fixed beds of catalyst particles in high pressure reactors through which the hydrogen and oil flow concurrently or countercurrently. This appears to be the most practical and convenient method, but other known techniques can be used, such as those involving the use of fluidized circulating catalyst particles, catalyst slurries, and gravitating catalyst masses. The two types of catalyst may conceivably be contained as separate beds of particles within a single reactor, the sulfactive hydrogenation catalyst above the naphtha reforming catalyst where the oil flows downward through the reactor. However, since it is generally desirable to remove the lower boiling materials produced in the first stage hydrocracking and to separate out the ammonia and hydrogen sulfide formed, it is more convenient to use separate reactors with stripping and distillation of the efiluent of the first stage prior to passing the highest boiling portion thereof to the second stage. Also, liquid may be recycled in the first stage whereas this would not ordinarily be desirable in the second stage. Also, a haliding agent may be added to the oil or hydrogen passing through the second stage reaction zone whereas this would not ordinarily be desirable in the first reaction stage. The catalyst employed in the first reaction stage Will ordinarily either be presulfied or else become sulfided during use, whereas the second stage catalyst is preferably prereduced and maintained in the metallic state.
The metal hydrogenation-dehydrogenation component of the catalyst employed in the hydrocracking-isomerization stage should be used and maintained in the nonsulfided state. Noble metals of the platinum group are preferred because their sulfides are unstable, and the catalyst can accordingly tolerate a small amount of sulfur in the feed without becoming irreversibly sulfided. Nickel is less advantageous because it form a stable sulfide, and its use would require that sulfur compounds be virtually completely excluded. The nonsulfided metals appear to isomerize that highest molecular weight paraflins selec tively and more rapidly than the sulfided metals. For example, in the hydrocracking-denitrification stage wherein sulfided catalysts are used to greatest advantage, highly branched isoparaffinis are not readily formed so that an excessively high hydrocracking conversion is needed to obtain a substantial lowering of the pour point. By nuclear magnetic resonance, it has been shown that the ratio of CH;; groups to CH groups is about 30 percent greater in a low pour point oil product of the hydrocracking-isomerization stage than in a low pour point (solvent dewaxed) sample of the corresponding oil product of the hydrocracking-denitirification stage. The higher ratio shows that the isoparaffins are more highly branched. Thus further branching of both high pour point and low pour point isoparafiins is accomplished in the second stage, which could not be accomplished in the first stage with the sulfide catalyst.
The following examples illustrate the practice of the invention and bring out certain significant and characteristic features of the process.
EXAMPLE 1 From a short vacuum residum of paraflinic crude oil there was obtained by propane deasphalting a residual oil containing 830 p.p.m. organic nitrogen and having a gravity of 27.8 API, of which less than 10 percent boils below 900 F. The deasphalted residual oil is quite waxy,
as a yield of only 56.5 percent oil is obtained by solvent dewaxing to F. pour point. In accordance with the invention, the undewaxed oil was contacted with a nickel sulfide-tungsten sulfide-alumina-silica sulfactive hydrogenation catalyst at 800 F., 2,400 p.s.i.g., and 1.0 LHSV, in the presence of about 6,000 standard cubic feet of recycled hydrogen per barrel. The eflluent oil was freed of H 8 and NH and then distilled to recover a bottoms fraction boiling entirely above 800 F., obtained in a yield of 55 weight percent from the deasphalted oil. The hydrocracked oil boiling above 800 F. contained only 0.1 p.p..m. nitrogen, less than 10' p.p.m. sulfur, and had a pour point of +120 F. Other inspections of this oil are shown in the following Table I wherein there are also shown inspections for a solvent dewaxed sample of this hydrocracked oil. As indicated, a high viscosity index bright stock could be recovered at this point by solvent dewaxing in a yield of about 35 weight percent based on the deasphalted oil feed at 0 F. pour point. In accordance with the invention, instead of solvent dewaxing, the 800+ oil was contacted with a platinum-alumina halided reforming catalyst at 774 F., 1,870 p.s.i.g., 1.0 LHSV, and about 10,000 standard cubic feet of recycled hydrogen per barrel. The hydrocracked oil effluent of this contacting was distilled directly to obtain distillate fractions and a bottoms fraction boiling entirely above 800 F., which bottoms fraction had a pour point of 60 F. In another run, the contacting with the platinum-aluminahalide catalyst was carried out at a lower space velocity with a portion of the catalyst at 774 F. and another portion at 410 F., which gave a lower conversion to distillate products and a pour point in the 800+ bottoms of F. Additional inspections and data regarding these runs are shown in the following Table I.
boiling entirely above 1,000 F. had a pour point of 30 F. Thus the highest boiling portions of the product have the lowest pour points. Mass spectrometric analysis of the product oils boiling entirely above 800 F. indicated that they were composed of between and percent paraflins, less than 5 percent aromatics, and the balance mono-, di-, and polycycloparaffins with monocycloparaffins predominating. No normal paraffins could be detected by gas chromatography; i.e., the parafiins were essentially all isoparatlins. A trace of normal paraffins could be detected in the 700800 F. distillate.
Mass spectrometric analysis of the +120 F. pour point low nitrogen content oil boiling above 800 F. indicated that it was composed 52 percent of paraffins, less than 5 percent aromatics, and the balance cycloparaffins, but essentially no normal parafiins could be detected by gas chromatography. The high pour point indicates that the tparaffins present are only slightly branched isoparaflins. These isoparafiins are apparently further cracked and isomerized to more highly branched low pour point isoparaffins in the contacting with the naphtha reforming catalyst. It is theorized that normal paraflins should desirably be substantially converted to high pour point isoparaifins in the contacting with the sulfactive hydrogenation catalyst to obtain the maximum pour point reduction with minimal yield loss in the subsequent pour point reducing stage. This is on the theory that the reforming catalyst selectively isomerizes isoparaffins more rapidly than normal paraffins. On the other hand, some feeds such a high percent conversion to lower boiling distillates may be needed in the first stage hydrocracking to substantially eliminate normal parafiins that the yield of high boiling oil for isomerization in the second stage would be so low as to reduce the overall yield below TABLE I Hydrocracked oil Isomerized Oils residue Deasphaltabove 700800 F., 800+ 700-800 F., 800+ ed oil feed 800 F. distillate residue distillate residue U dewaxed Oil:
Yield, wt. percent 55 12.0 23. 3 14. 7 20.4 Gravity, API 41. 3 38. 5 40. 0 37. 8 Viscosity, SSU at 100 F 70. 48 219. 4 73. 61 288.1 Viscosity, SSU at 210 1 36. 67 50.07 37. 24 56. 04 Viscosity index 111 122 119 125 Pour point, F +120 -25 60 +15 20 Organic nitrogen, p.p.m 830 0. 1 Solvent Dewaxed Oil: Yield, wt. percent 56. 5 Gravity, AP Viscosity, SSU at 100 4,262 Viscosity, SSU at 210 F. 192.1 Viscosity index 86 Pour point, F 0
All yields wt. percent of deasphalted oil feed.
In the above tabulation it will be noted that the pour point of the high boiling bottoms from the contacting with the platinum reforming catalyst was lower the greater the conversion to distillates boiling below 800 F. The pour point goes down at the rate of about 30 F. for each 10 percent conversion of oil to 800-distillate. Also the yield of low pour point oil obtainable corresponds very closely to the yield Which would be obtainable by solvent dewaxing the hydrocracked oil effluent of the hydrocracking-denitrification stage to the same pour point. Thus essentially the same yield can be obtained; but, instead of producing by-product slack wax as in the prior art, more valuable boiling distillates are produced as byproducts in the invention. While in some cases the wax obtainable by solvent dewaxing is hard paraflin wax, in most cases it is the less readily salable soft microcrystalline wax.
The oil produced in the above example having a pour point of -20 F. was further distilled into fraction and the pour points of the respective fractions determined. It was found that the oil boiling between 800 and 900 F. had a pour point of +20 F.; that boiling between 900 and 1,000 F. had a pour point of -10 F.; and that EXAMPLE 2 From propane-butane deasphalting of vacuum residua of mixed crudes there was obtained a residual oil containing 7,400 ppm. nitrogen and 1.06 weight percent sulfur with a pour point of +115 F. Over 90 percent of the oil boiled above 800 F., and over 75 percent boiled above 900 F. This oil was hydrocracked severly to 67 percent conversion to distillates boiling below 750 F. by contacting with a nickel sulfide-molybdenum sulfide-alumina-silica catalyst at 800 F., 2,400 p.s.i.g., 0.5 LHSV, with about 6,000 s.c.f. H /bbl. The efiluent oil was freed of NH and H S and distilled to recover the 33 percent bottoms boiling above 750 F., which had a pour point of F. and contained 1.3 ppm. organic nitrogen. The bottoms fraction was contacted With a 9 halided platinum-alumina reforming catalyst at about 810 F., 2,300 p.s.i.g., 1.0 LHSV, and 10,000 s.c.f. H /bbl. The oil eflluent of this contacting was distilled into fractions including a bottoms fraction boiling entirely above 750 F. which had a pour point of +15 F.
of asphaltic constituents, containing organic nitrogen and sulfur compounds and boiling mostly above 800 R, which comprises contacting said high pour point waxy oil feed and hydrogen in a first reaction zone with a sulfactive hydrocracking-denitrification catalyst at "hydrocracking- At a slightly higher temperature and lower space veloc- 5 denitrification conditions of elevated pressure above 1,000 ity, the pour point was lowered to 20 F. Additional p.s.i.g. and temperatures maintained in the range 650- inspections and data are shown in the following Table II. 950 F. to convert the organic nitrogen compounds and TABLE II Hydrocracked oil Isomerized Oils residue Deasphaltabove 700-s F., 800+ 700-s00 F., 800+ ed oil feed 750 F. distillate residue distillate residue Undewaxed 011: 0
Yield, wt. percent 100 33 5. 16, 5 8. 2 7 Gravity, API 16.1 32. 4 35. 9 37. 5 35.9 Viscosity, SSU at 100 F 70.06 207. 0 89.57 265.0 327. 4 30. 56 49. 67 3s. 74 53. 4s
Viscosity, SSU at 210 F... Viscosity index. Four point, f F Organic nitrogen, Solvent Dewaxed Oil:
, iscosity, SSU at 100 F iscosity, SSU at 210 F Viscosity index Pour point, F
All yields wt. percent of deasphalted oil feed.
The lower yield of low pour point residual lube oil and the greater difiiculty in obtaining an extremely low pou r point, in the above Example 2 as compared to Example 1, may be attributed to the more refractory nature of the deasphalted residual oil feed, the more aromatic character of the original mixed crudes, and the higher nitrogen and sulfur contents. The deasphalted oil was very difiicult to denitri-fy, and residual organic nitrogen and sulfur in the oil passed to the hydrocrackingisomerization zone may have played a part in reducing selectivity therein, as the pour point was lowered only 12-18 F. for each percent conversion in the final stage as compared to 30 F. per 10 percent conversion in Example 1.
EXAMPLE 3 A straight-run gas oil distillate of Arabian crude boiling from 470 F. to 800 F., 32.5" API, aniline point 170.2 F., and +50 F. pour point, was hydrofined at 720 F., 1.0 LHSV, 2,100 p.s.i.g. Conversion to distillates boiling below 450 F. was 21 percent, and the 79 percent yield of 450+ bottoms contained 1 p.p.m. sulfur, 0.1 ppm. nitrogen, was 41.5 API gravity, and had a pour point of +40 F. It is estimated that the pour point could be lowered to +10 F. by continued severe hydrofinihg until the yield of 450+ bottoms would be less than 45 percent. In accordance with the invention, the +40 F. pour point oil was contacted with the platinum reforming catalyst at 1.0 LHSV, 783 F., 1,780 p.s.i.g., and 10,000 s.c.f. H /bbl. The overall yield of 450+ bottoms on distilling the effluent was 62 percent, and the pour point was F.
The economics of producing low pour point bright stock from the parafiinic deasphalted residual oil feed of Example 1 have been evaluated. For a large installation, the best prior art procedure available required that most of the money be invested in a large-scale solvent dewaxing plant. The desired low pour point product could be obtained in only slightly lower yield by means of the process of the present invention for less than half the investment cost.
The examples herein have dealt primarily with the use of the invention for producing lubricating oils. It is apparent, however, that the process can be applied to a variety of oils to produce low pour point products for other uses.
1. Process for producing lubricating oils having low pour point, without recourse to physical wax separation, from a high pour point waxy oil feed substantially free organic sulfur compounds in said feed to ammonia and hydrogen sulfide, respectively, and to convert at least 20 percent of said feed to products boiling lower than said feed, removing ammonia and hydrogen sulfide from the first reaction zone efiluent, contacting the substantially nitrogenand sulfur-free product comprising at least the higher boiling components of the efiiuent of said first reaction zone and hydrogen in a second reaction zone with an unsulfided naphtha reforming catalyst comprising a platinum group component associated with alumina and containing no more than 2 weight percent halide under isomerization-hydrocracking conditions of elevated pressure above 500 p.s.i.g. and temperatures maintained in the range 700900 F. with consumption of hydrogen, to convert at least 10 percent to lower boiling materials and separating the etfiuent from said second reaction zone into fractions including at least a bottoms fraction boiling above 800 F. and within the boiling range of said waxy oil feed and having a pour point at least 30 F. below the pour point of said high pour point waxy oil feed.
2. The process of claim 1 wherein said high pour point waxy oil feed is a deasphalted residuum and the hydrocracking conditions of contact with the sulfided hydrocracking-denitrification catalysts are such as to convert at least 30 percent of such feed to lower boiling products.
3. The process of claim 1 wherein the feed to said second reaction zone (isomerization-hydrocracking) boils above 800' F.
4. The process of claim 1 wherein the efiluent from said second reaction zone (isomerization-hydrocracking)' is separated into fractions including a bottoms fraction boiling above 1,000 F. and characterized by a pour point below 0 F.
5. The process of claim 1 wherein said waxy oil feed comprises deasphalted residuum and said bottoms fraction comprises a bright stock having a pour point below 0 F.
6. Process for producing lubricating oils having pour points below 0, F. from petroleum residua without recourse to the step of physically separating wax which comprises subjecting a petroleum residuum to solvent deasphalting to sepa ate a substantially asphalt-free fraction boiling in the boiling range of the higher boiling components of said residuum, contacting said fraction and from 2,00020,000 s.c.f. of H per barrel of said fraction in a hydrocracking zone with sulfactive hydrocracking catalyst at 700850 F., a liquid hourly space velocity from about 0.3 to 3.0 and at a pressure in the range of about 1,000-5,000 p.s.i.g. in a hydrocracking zone under conditions to convert at least 30 percent of said asphalt-free fraction to lower boiling distillates and to convert organic nitrogen compounds and organic sulfur compounds to ammonia and hydrogen sulfide, respectively, removing ammonia and hydrogen sulfide from the efiluent from said hydrocracking zone, contacting at least a portion of said hydrocracking Zone efiluent comprising a part of the higher boiling components of said efiluent and from 2,000- 20,000 s.c.f. of H per barrel with an unsulfided naphtha reforming catalyst comprising a platinum group component associated with alumina and containing no more than 2 weight percent halide in an isomerization-hydrocracking zone at 750900 F., 1,0005,000 p.s.i.g. and at a liquid hourly space velocity from about 0.3 to 3.0 to convert at least 10 percent of said hydrocracking zone effluent to lower boiling distillates, and fractionally distilling the efiluent from said isomerization-hydrocracking 12 zone to separate a lubricating oil fraction boiling above 800 F. and in the boiling range of said asphalt-free fraction and characterized by a pour point below 0 F.
References Cited UNITED STATES PATENTS 2,779,713 1/1957 Cole et al. 208-57 3,125,511 3/1964 Tupman et a1. 208264 3,268,439 8/1966 Tuprnan et a1 208l12 DELBERT E. GANTZ, Primary Examiner T. H. YOUNG, Assistant Examiner US. Cl. X.R. 208-86, 89