ZA200509230B - Process for upgrading fischer-tropsch products using dewaxing and hydrofinishing - Google Patents

Description

1 PROCESS FOR UPGRADING FISCHER-TROPSCH PRODUCTS 2 USING DEWAXING AND HYDROFINISHING 3 4 FIELD OF THE INVENTION 6 The invention relates to a process for upgrading the hydrocarbons having an 7 initial boiling point above about 120 degrees C recovered froma Fischer- 8 Tropsch plant by bulk dewaxing a Cs plus hydrocarbon Fischer-Tropsch 9 syncrude followed by hydrofinishing and recovering diesel and lubricating base oil products having improved properties. 1 12 BACKGROUND OF THE INVENTION 13 14 The market for lubricating base oils of high paraffinicity is continuing to grow due to the high viscosity index, oxidation stability, and low volatility relative to 16 viscosity of these oils. The products produced from the Fischer-Tropsch 17 process (syncrude) contain a high proportion of wax which make them ideal 18 candidates for processing into lubricating base stocks. Accordingly, the 19 hydrocarbon products recovered from the Fischer-Tropsch process have been. proposed as feedstocks for preparing high quality lubricating base oils. See, 21 for example, US Patent 6,080,301 which describes a premium lubricating 22 base oil having a high non-cyclic isoparaffin content prepared from Fischer- 23 Tropsch waxes by hydroisomerization dewaxing and solvent dewaxing. 24

High quality diesel products also may be prepared from the syncrude 26 recovered from the Fischer-Tropsch process. Fischer-Tropsch derived diesel 27 typically has a very low sulfur content and an excellent cetane number. 28 These qualities make Fischer-Tropsch derived diesel an excellent blending 29 stock for upgrading lower quality petroleum-derived diesel. 31 In general, for the purposes of this disclosure, diesel is considered as having 32 a upper boiling point of about 700 degrees F (370 degrees C) and an initial 33 boiling point of about 300 degrees F (about 150 degrees C). Lubricating base 34 oils typically will have an initial boiling point above about 600 degrees F

1 (about 315 degrees C). The syncrude fractions boiling in the range of diesel 2 and lubricating base oils as they are initially recovered from the Fischer- 3 Tropsch plant will usually contain a high proportion of waxy normal paraffins 4 and unsaturated hydrocarbons, and therefore, these fractions require upgrading to meet commercial specifications for the finished products prior to 6 their use either alone or as blending stock. During upgrading the various 7 fractions are separated according fo their respective boiling ranges. in the 8 case of those fractions boiling in the ranges of lubricating base oils and diesel, 9 upgrading steps generally are intended to lower the pour point to an acceptable temperature and to improve the oxidation and UV stability of the 11 products. In order to improve the properties of these fractions, they are 12 separated from the syncrude and separately dewaxed and hydrofinished. 13 Applicants have discovered that contrary to conventional teaching, it is 44 advantageous to bulk dewax and hydrofinish the entire Cs plus syncrude fraction prior to separation of the various fractions. 16 47 Fischer-Tropsch wax refers to a high boiling fraction from the Fischer-Tropsch 18 derived syncrude and is most often a solid at room temperature. For the : 19 purpose of this disclosure "Fischer-Tropsch wax" is contained in the higher boiling portion of the Fischer-Tropsch syncrude. Fischer-Tropsch wax 21 contains at least 10 percent by weight of C2 and higher hydrocarbonaceous 22 compounds, preferably at least 40 percent by weight of Cz and higher 23 hydrocarbonaceous compounds, and most preferably at least 70 percent by 24 weight of Cz and higher hydrocarbonaceous compounds. Fischer-Tropsch wax is important for the present invention because this fraction will contain the 26 heavier hydrocarbons which when sent to the catalytic dewaxing operation will 27 be converted to high quality lubricating base oil and diesel. 28 29 Cs plus syncrude refers to those fractions of the product from a Fischer-

Tropsch plant which are normally a liquid or solid at ambient temperature. 31 Usually hydrocarbons boiling above ambient temperature will include those 32 hydrocarbons containing 5 or more carbon atoms in the molecule. However, 33 one skilled in the art will recognize that other factors besides carbon number 34 will affect the boiling ranges of the Fischer-Tropsch syncrude fractions, such

1 as, for example, the presence of unsaturated bonds, branching, and 2 heteroatoms in the molecule.

Therefore, some hydrocarbons may be present 3 in this fraction which contain less than 5 carbon atoms.

Products recovered 4 from the Fischer-Tropsch synthesis which are normally in the gaseous phase at ambient temperature are referred to as C4 minus product in this disclosure. 6 LPG which is primarily a mixture of propane and butane is an example of a C4 7 minus product. 8 | : 0 Fractions boiling in the range of diesel may also be referred to as Cio to Cio hydrocarbons.

Likewise, Fischer-Tropsch wax preferably is comprised 11 predominantly of "Coo plus product’ which refers to a product comprising 12 primarily hydrocarbons having more than 20 carbon atoms in the backbone of 13 the molecule and having an initial boiling point at the upper end of the boiling 14 range for diesel. it should be noted that the upper end of the boiling range for diesel and the lower end of the boiling range for Fischer-Tropsch wax have 16 considerable overlap.

The term "naphtha" when used in this disclosure refers 17 to a liquid product having between about Cs to about Cg carbon atoms in the 18 backbone and will have a boiling range generally below that of diesel but 19 wherein the upper end of the boiling range will overlap that of the initial boiling point of diesel.

C1o plus hydrocarbons generally boil-above the range of 21 naphtha, i.e., the fractions boiling within the range of diesel and lubricating 22 base oils or above about 150 degrees C.

The precise cut-point selected for 23 each of the products in carrying out the distillation operation will be 24 determined by the product specifications and yields desired.

26 The dewaxing and hydrofinishing of C20 plus hydrocarbons, including Fischer- 27 Tropsch-derived syncrude is discussed in US Patent 5,135,838. The 28 isomerization of lighter feeds boiling in the range of naphtha and diesel by 29 contacting the feed with a catalyst containing a silicoaluminophosphate molecular sieve (SAPO) is discussed in US Patent 4,859,311. 31 32 As used in this disclosure the words "comprises" or "comprising" is intended 33 as an open-ended transition meaning the inclusion of the named elements, 34 but not necessarily excluding other unnamed elements.

The phrase "consists

1 essentially of" or "consisting essentially of" is intended to mean the exclusion 2 of other elements of any essential significance to the composition. The 3 phrases "consisting of" or "consists of" are intended as a transition meaning 4 the exclusion of all but the recited elements with the exception of only minor ~ § traces of impurities. 6 7 SUMMARY OF THE INVENTION 8 : _ 9 Broadly, the present invention is directed to a process for producing low pour point hydrocarbon products having an initial boiling point above about 150 11 degrees C from a Fischer-Tropsch plant which comprises (a) recovering a 12 feedstock comprising Cs plus syncrude from a Fischer-Tropsch plant; (b) 13 dewaxing the Cs plus syncrude feedstock in a catalytic dewaxing zone by 14 contacting the Cs plus syncrude feedstock with a dewaxing catalyst under dewaxing conditions, whereby a Cs plus intermediate is produced having a 16 lowered pour point relative to the Cs plus syncrude feedstock; (c) 17 hydrofinishing the Cs plus intermediate in a hydrofinishing zone under 18 hydrofinishing conditions, whereby a UV stabilized Cs plus product is 19 produced; and (d) separately collecting from the UV stabilized Cs plus product alow pour point product having an initial boiling point above about 150 21 degrees C. The low pour point product of step (d) will generally consist of . 22 diesel and lubricating base oil products, although depending on how the 23 operation is run the proportional yields of the products may vary over a 24 considerable range. 26 Inone embodiment of the invention, the preferred dewaxing catalyst is a 27 hydroisomerization catalyst, such as, for example, a catalyst comprising a 28 silicoaluminophosphate molecular sieve, commonly referred to as a SAPO, in 29 combination with a hydrogenation component comprising an active metal.

The SAPO is preferably an intermediate pore SAPO, such as, for example, 31 SAPO-11, SAPO-31, and SAPO-41, with SAPO-11 being especially preferred. 32 Other aluminophosphates besides SAPQ's can be used (broad category of 33 "non-zeolitic molecular sieves") and are taught in US Patent 5,135,638, col. 34 10, lines 24-31. A more complete description is in US Patent 5,883,837, col.

1 8, lines 5-17. Accordingly, this embodiment of the invention may be described 2 as a process for producing low pour point syncrude products having an initial 3 boiling point above about 150 degrees C froma Fischer-Tropsch plant which 4 comprises (a) recovering a feedstock comprising Cs plus syncrude from a

Fischer-Tropsch plant; (b) dewaxing the Cs plus syncrude feedstock in a 6 hydroisomerization zone by contacting the Cs plus syncrude feedstock with a 7 hydroisomerization catalyst under hydroisomerization conditions, whereby an : 8 isomerized:Cs plus intermediate is produced having a lowered pour point 9 relative to the Cs plus syncrude feedstock; (c) hydrofinishing the isomerized

Cs plus intermediate in a hydrofinishing zone under hydrofinishing conditions, 11 whereby a UV stabilized Cs plus product is produced; and (d) separately 12 collecting from the UV stabilized hydrocarbon product a low pour point diesel 13 product and a lubricating base oil product. Hydroisomerization catalysts 14 comprising SAPO-11 in association with a hydrogenation component are 16 particularly preferred. The hydrogenation component usually comprises an 16 active metal, such as molybdenum, nickel, vanadium, cobalt, tungsten, zinc, 17 platinum, and palladium. The metals platinum and palladium are especially 18 preferred as the active metals. Those SAPOs in which the metals have been : 19 added by means of non-aqueous addition as taught in US Patent 5,939,349 are especially preferred. 21 22 Ultra high VI base oil products, i.e., products having a Vi of greater than 140,’ 23 can be obtained by using a dewaxing catalyst comprising a intermediate pore 24 zeolite, usually in association with an active metal having hydrogenation activity. Suitable intermediate pore size zeolites include SSZ-32, ZSM-22, 26 2SM-23, ZSM-35, and ZSM-48. The zeolites SSZ-32, ZSM-22, and ZSM-23 27 are particularly preferred. The active metal component is as already : 28 described above. This embodiment of the present invention may be 29 described as a process for producing an ultra high Vt, low pour point lubricating base oil product from a Fischer-Tropsch plant which comprises (a) 31 recovering a feedstock comprising Cs plus syncrude from a Fischer-Tropsch 32 plant; (b) dewaxing the Cs plus syncrude feedstock in a catalytic 33 hydrodewaxing zone by contacting the Cs plus hydrocarbon feedstock with 34 hydroisomerization dewaxing catalyst comprising an intermediate pore size

1 zeolite and at least one metal having hydrogenation activity, said dewaxing 2 being carried out under hydrodewaxing conditions selected to produce an Cs 3 plus intermediate having a lowered pour point relative to the Cs plus syncrude 4 feedstock; (c) hydrofinishing the Cs plus intermediate in a hydrofinishing zone under hydrofinishing conditions, whereby a UV stabilized Cs plus product is 6 produced; and (d) separately collecting from the UV stabilized Cs plus product 7 an ultra high VI, low pour point lubricating base oil product. The term 8 “intermediate pore size" when referring to either a zeolite or a SAPO in this 9 disclosure means an inorganic molecular sieve having an effective pore aperture in the range of from about 5.3 to about 6.5 Angstrom when the 11 porous inorganic oxide is in the calcined form. The most preferred zeolites for 12 producing ultra high VI products are somewhat more restricted having an 13 effective pore aperture of between about 5.0 to about 5.5 Angstrom. 14 16 In conventional processes for upgrading Fischer-Tropsch product into diesel 16 and lubricating base oils, the various fractions usually are separated prior to 17 upgrading. During dewaxing of that Fisher—Tropsch fraction boiling above 18 about 315 degrees C some wax cracking will occur which will yield lower 19 molecular products such as diesel, naphtha, and Cs minus hydrocarbons.

When one of the preferred SAPO catalysts having high diesel selectivity, such 21 as SAPO-11, is used to dewax the fraction boiling in the lubricating base oil 22 range, diesel is preferentially produced as opposed to less valuable products 23 such as naphtha and Cs minus hydrocarbons. In a conventional operation, a 24 second separation will generally be necessary following the dewaxing operation, since considerable additional high value diesel is produced. Inthe 26 present invention only a single separation step is necessary to collect all of 27 the diesel which results in a significant cost saving. In addition, with the 28 present invention, the diesel fraction recovered from the dewaxing operation 29 will have an especially low pour point, preferably below about —20 degrees Cc and more preferably below about —30 degrees C. The low pour point of the 31 diesel allows the end point to be extended which also increases the yield of 32 diesel in the overall product slate. 33 34

1 BRIEF DESCRIPTION OF THE DRAWING 3 The figure is a schematic diagram of one embodiment of the invention. 4

DETAILED DESCRIPTION OF THE INVENTION

6 7 The present invention will be more clearly illustrated by reference to the 8 figure. Synthesis gas or syngas comprised primarily of carbon monoxide and 9 hydrogen is sent to the Fischer-Tropsch reactor 4 via inlet 2. The Fischer- Tropsch syncrude comprised primarily of Cs plus hydrocarbons is carried by 11 line 6 to the dewaxing unit 8 where the pour point of the syncrude, especially 12 of those fractions of the syncrude boiling in the range of diesel and lubricating 13 base oils is lowered. The Cs plus intermediate that is collected from the 14 dewaxing unit is carried by line 10 to the hydrofinishing unit 12 where any . remaining unsaturated carbon-to-carbon double bonds are saturated and the 16 UV stability of the hydrocarbons is improved. The UV stabilized Cs plus 17 product is collected by line 14 and sent to the distillation column 16 where the 18 various fractions are separated. Inthe figure the products shown as being 19 separately collected are C4 minus product 18, naphtha 20, diese! 22, and lubricating base oil 24, respectively.

C21 22 FISCHER-TROPSCH SYNTHESIS 23 24 In the Fischer-Tropsch synthesis process, liquid and gaseous hydrocarbons are formed by contacting a synthesis gas (syngas) comprising a mixture of 26 hydrogen and carbon monoxide with a Fischer-Tropsch catalyst under 27 suitable temperature and pressure reactive conditions. The Fischer-Tropsch 28 reaction is typically conducted at temperatures of from about 300 F to about 29 700 degrees F (about 150 degrees C to about 370 degrees C) preferably from about 400 degrees F to about 550 degrees F (204 degrees C to 228 degrees 31 CC); pressures of from about 10 to about 600 psia, (0.7 bar to 41 bars) 32 preferably 30 psia to 300 psia, (2 bars to 21 bars) and catalyst space 33 velocities of from about 100 cc/g/r to about 10,000 cc/g/hr., preferably 300 to 34 3,000 cc/ghr.

2 The products may range from C1 to Cao plus hydrocarbons with a majority in 3 the Csto Co plus range. The reaction can be conducted in a variety of 4 reactor types, for example, fixed bed reactors containing one or more catalyst beds, slurry reactors, fluidized bed reactors, or a combination of different type 6 reactors. Such reaction processes and reactors are well known and 7 documented in the literature. Slurry Fischer-Tropsch processes, which is a 8 preferred process in the practice of the present invention, utilize superior heat 9 (and mass) transfer characteristics for the strongly exothermic synthesis reaction and are able to produce relatively high molecular weight, paraffinic 11 hydrocarbons when using a cobalt catalyst. In a slurry process, a syngas 12 comprising a mixture of hydrogen and carbon monoxide is bubbled up as a 13 third phase through a slurry in a reactor which comprises a particulate 14 Fischer-Tropsch type hydrocarbon synthesis catalyst dispersed and suspended in a slurry liquid comprising hydrocarbon products of the synthesis 16 reaction which are liquid at the reaction conditions. The mole ratio of the 17 hydrogen to the carbon monoxide may broadly range from about 0.5 to about 18 4, but is more typically within the range of from about 0.7 to about 2.75 and 19 preferably from about 0.7 to about 2.5. A particularly preferred Fischer- Tropsch process is taught in EP0809079, which is completely incorporated 21 herein by reference for all purposes. 22 Suitable Fischer-Tropsch catalysts comprise one or more Group VIiIl catalytic 23 metals such as Fe, Ni, Co, Ru and Re, with cobalt being preferred. 24 Additionally, a suitable catalyst may contain a promoter. Thus, a preferred

Fischer-Tropsch catalyst comprises effective amounts of cobalt and one or 26 more of Re, Ru, Pt, Fe, Ni, Th, Zr, Hf, U, Mg and La on a suitable inorganic 27 support material, preferably one which comprises one or more refractory 28 metal oxides. In general, the amount of cobalt present in the catalyst is 20 between about 1 and about 50 weight percent of the total catalyst composition. The catalysts can also contain basic oxide promoters such as 31 ThO,, La;03, MgO, and TiO, promoters such as ZrO, noble metals (Pt, Pd, 32 Ru, Rh, Os, In), coinage metals (Cu, Ag, Au), and other transition metals such 33 as Fe, Mn, Ni, and Re. Suitable support materials include alumina, silica,

1 magnesia and titania or mixtures thereof.

Preferred supports for cobalt 2 containing catalysts comprise titania.

Useful catalysts and their preparation 3 are known and illustrated in U.S.

Patent 4,568,663, which is intended to be 4 illustrative but non-limiting relative to catalyst selection.

6 CATALYTIC DEWAXING 7 = 8 Although not shown in the figure, it may be desirable to include a pretreatment 9 step for the syncrude prior to its introduction into the dewaxing unit, since raw syncrude typically contains a number of contaminants which act as catalyst 11 poisons, most notably nitrogen and oxygen compounds.

Both the nitrogen 12 and oxygen compounds may be removed by hydrotreating.

Preferably the 13 nitrogen in the feed stock to the dewaxing reactor should be below 50 ppm 14 and more preferably below 10 ppm.

Alternatively, the alcohols may be dehydrated to remove water prior to dewaxing.

Other methods for removing 16 contaminants include adsorption and extraction. 17 18 Catalytic dewaxing consists of three main classes, conventional 19 hydrodewaxing, complete hydroisomerization dewaxing, and partial hydroisomerization dewaxing.

All three classes involve passing a mixture of a 21 waxy hydrocarbon stream and hydrogen over a catalyst that contains an 22 acidic component to convert the normal and slightly branched iso-paraffins in 23 the feed to other non-waxy species, such as lubricating oil base stocks with : 24 acceptable pour points.

Typical conditions for all classes involve temperatures from about 400 degrees F to about 800 degrees F (200 degrees 26 C to 425 degrees C), pressures from about 200 psig to 3000 psig, and space 27 velocities from about 0.2 to 5 hr-1. The method selected for dewaxing a feed 28 typically depends on the product quality, and the wax content of the feed, with 29 conventional hydrodewaxing often preferred for low wax content feeds.

The method for dewaxing can be effected by the choice of the catalyst.

The 31 general subject is reviewed by Avilino Sequeira, in Lubricant Base Stock and 32 Wax Processing, Marcel Dekker, Inc. pages 194-223. The determination , 33 between conventional hydrodewaxing, complete hydroisomerization

1 dewaxing, and partial hydroisomerization dewaxing can be made by using the 2 n-hexadecane isomerization test as described in U.S. Patent No. 5,282,958. 3 When measured at 96 percent, n-hexadecane conversion using conventional 4 hydrodewaxing catalysts will exhibit a selectivity to isomerized hexadecanes ofless than 10 percent, partial hydroisomerization dewaxing catalysts will 6 exhibit a selectivity to isomerized hexadecanes of greater than 10 percent to 7 less than 40 percent, and complete hydroisomerization dewaxing catalysts will 8 exhipit a selectivity to isomerized hexadecanes of greater than or equal to 40 9 percent, preferably greater than 60 percent, and most preferably greater than 80 percent. 11 12 In conventional hydrodewaxing, the pour point is lowered by selectively 13 cracking the wax molecules mostly to smaller paraffins using a conventional 14 hydrodewaxing catalyst, such as, for example ZSM-5. Metals may be added to the catalyst, primarily to reduce fouling. In the present invention : 16 conventional hydrodewaxing may be used to increase the yield of lower 17 molecular weight products in the final product slate by cracking the Fischer- 18 Tropsch wax molecules. 19

Complete hydroisomerization dewaxing typically achieves high conversion 21 levels of wax by isomerization to non-waxy iso-paraffins while at the same 29 time minimizing the conversion by cracking. Since wax conversion can be 23 complete, or at least very high, this process typically does not need to be 24 combined with additional dewaxing processes to produce a lubricating oil pase stock with an acceptable pour point. Complete hydroisomerization 26 dewaxing uses a dual-functional catalyst consisting of an acidic component 27 and an active metal component having hydrogenation activity. Both 28 components are required to conduct the isomerization reaction. The acidic 20 component of the catalysts-used in complete hydroisomerization preferably include an intermediate pore SAPO, such as SAPO-11, SAPO-31, and SAPO- 31 41, with SAPO-11 being particularly preferred. intermediate pore zeolites, 32 such as ZSM-22, ZSM-23, SSZ-32, ZSM-35, and ZSM-48, also may be used 33 in carrying out complete hydroisomerization dewaxing. Typical active metals 34 include molybdenum, nickel, vanadium, cobalt, tungsten, zinc, platinum, and

1 palladium.

The metals platinum and palladium are especially preferred as the 2 active metals, with platinum most commonly used. 3 } 4 In partial hydroisomerization dewaxing a portion of the wax is isomerized to iso-paraffins using catalysts that can isomerize paraffins selectively, but only if 6 the conversion of wax is kept to relatively low values (typically below 50 7 percent). At higher conversions, wax conversion by cracking becomes 8 significant, and yield losses of lubricating base stock becomes uneconomical. 9 Like complete hydroisomerization dewaxing, the catalysts used in partial hydroisomerization dewaxing include both an acidic component and a 11 hydrogenation component.

The acidic catalyst components useful for partial 12 hydroisomerization dewaxing include amorphous silica aluminas, fluorided 13 alumina, and 12-ring zeolites (such as Beta, Y zeolite, L zeolite). The 14 hydrogenation component of the catalyst is the same as already discussed 16 with complete hydroisomerization dewaxing.

Because the wax conversion is 16 incomplete, partial hydroisomerization dewaxing must be supplemented with 17 an additional dewaxing technique, typically solvent dewaxing, complete 18 hydroisomerization dewaxing, or conventional hydrodewaxing in order to 19 produce a lubricating base stock with an acceptable pour point (below about +10 degrees F or -12 degrees C). 21 22 The present invention may also be used to prepare ultra-high VI lubricating 23 base oils.

Catalysts containing SAPO's, such as SAPO-11, have been used 24 to produce ultra-high VI lubricating base oils.

However, an intermediate pore zeolite with one-dimensional pores, such as, for example, SSZ-32, ZSM-23, 26 and ZSM-22 also may be used in carrying out the present invention if a 27 lubricating base oil product having ultra high Vl is desired.

The term one- 28 dimensional pores, also referred to as 1-D pores, is fully explained in us 29 Patent 5,135,638, column 6, at lines 31-41. Briefly, the term refers to a zeolite in which the intracrystalline channels are parallel and are not interconnected. 31 The production of ultra high VI lubricating base oil in this embodiment is 32 particularly surprising because with conventional petroleum-derived feeds, 33 catalysts containing SAPOs will usually produce a higher VI product than

1 those catalysts containing a zeolite.

Preferably the intermediate pore zeolite 2 is used in association with an active metal having hydrogenation activity. 3 4 In preparing those catalysts containing a non-zeolitic molecular sieve and having an hydrogenation component for use in the present invention, it is 6 usually preferred that the metal be deposited on the catalyst using a non- 7 aqueous method.

Catalysts, particularly catalysts containing SAPQO's, on > 8 which the metal has been deposited using a non-aqueous method have 9 shown greater selectivity and activity than those catalysts which have used an aqueous method to deposit the active metal.

The non-aqueous deposition of 11 active metals on non-zeolitic molecular sieves is taught in US Patent 12 5,939,349. In general, the process involves dissolving a compound of the 13 active metal in a non-aqueous, non-reactive solvent and depositing it on the 14 molecular sieve by ion exchange or impregnation.

16 HYDROFINISHING 17 18 Hydrofinishing operations are intended to improve the UV stability and color of 19 the products.

It is believed this is accomplished by saturating the double bonds present in the hydrocarbon molecule, including those found in 21 aromatics, especially polycyclic aromatics.

In the process of the present 22 invention, the Cs plus intermediate recovered from the dewaxing operation is 23 sent to a hydrofinisher.

A general description of the hydrofinishing process 24 may be found in US Patents 3,852,207 and 4,673,487. As used in this disclosure the term UV stability refers to the stability of the lubricating base oil 26 or other products when exposed to ultraviolet light and oxygen.

Instability is 27 indicated when a visible precipitate forms or darker color develops upon 28 exposure to uitraviolet light and air which results in a cloudiness or floc in the 20 product.

Lubricating base oils and diesel products prepared by the process of the present invention will require UV stabilization before they are suitable for 31 use in the manufacture of commercial lubricating oils and marketable diesel. 32 33 Typically, the total pressure in the hydrofinishing zone will be between about 34 200 psig and about 3000 psig, with pressures in the range of about 500 psig

1 and about 2000 psig being preferred.

Temperature ranges in the 2 hydrofinishing zone are usually in the range of from about 300 degrees F (150 3 degrees C) to about 700 degrees F (370 degrees C), with temperatures of 4 from about 400 degrees F (205 degrees C) to about 500 degrees F (260 - degrees C) being preferred.

The LHSV is usually within the range of from 6 about 0.2 to about 2.0, preferably 0.2 to 1 5 and most preferably from about 7 0.7 to 1.0. Hydrogen is usually supplied to the hydrofinishing zone ata rate of 8 from about 1000 to about 10,000 SCF per barrel of feed.

Typically the 9 hydrogen is fed at arate of about 3000 SCF per barrel of feed.

The hydrofinishing step may be integrated into the same gas system as the 11 dewaxing step. 12 13 Suitable hydrofinishing catalysts typically contain a Group Vill metal 14 component together with an oxide support.

Metals or compounds of the following metals are useful in hydrofinishing catalysts include nickel, . 468 ruthenium, rhodium, iridium, palladium, platinum, and osmium.

Preferably the 17 metal or metals will be platinum, palladium or mixtures of platinum and 18 palladium.

The refractory oxide support usually consists of alumina, silica, 19 silica-alumina, silica-alumina-zirconia, and the like.

The catalyst may optionally contain a zeolite component.

Typical hydrofinishing catalysts are 29 disclosed in US Patents 3,852,207; 4,1 57,294; and 4,673,487. 22 23 In carrying out the invention, the cut-point between those Fischer-Tropsch 24 fractions boiling in the range of diese! and lubricating base oil may be adjusted to either increase the yield of diesel or the yield of lubricating base 26 oil.

For example by extending the cut-point for diesel, it is possible to not only 27 maximize the yield of diesel but still also produce a diesel product having a 28 very low cloud point and pour point.

Atthe same time, the volatility of the 20 lubricating base oil cutis minimized which is major commercial selling point for lubricants. 31 32 When a SAPO, such as SAPO-11, is used as the hydroisomerization catalyst 33 in the dewaxing operation, diesel is the primary product of the wax-cracking. 34 Consequently, the actual yield for the less valuable naphtha and C4 minus gas

1 is minimized. The cut-point between the diesel product and the lubricating 2 base oil product during fractionation may aiso be adjusted to decrease or 3 increase the amount of diesel present in the final product slate. For example, 4 the cut-point selected could be as low as 600 degrees F (515 degrees C).

This would increase the amount of lubricating base oil recovered at the "6 expense of diesel. Likewise, the cut-point could be selected as high as 700 7 degrees F (370 degrees C) or more. This would increase the amount of 8 diesel recovered at the expense of the yield of lubricating base oil. However, 9 in this later case the diesel recovered will have an especially low pour point and the lubricating base oil will very low volatility. 11 42 Finally as already noted, the present process of the present invention requires 13 only a single fractionation operation instead of the two fractionation steps 14 which would be necessary using a conventional processing scheme.

Accordingly, the present invention results in a significant cost savings over 16 conventional operations. : 17 18 The following example is intended to further illustrate a specific embodiment 19 of the invention without being interpreted as a limitation thereon.

Co - 21 EXAMPLE 22 23 A Fischer-Tropsch derived feedstock having the specifications shown in 24 Table 1 was dewaxed using a hydrocracking catalyst and a hydroisomerization catalyst.

1 Table 1

Ll A CJ

Wenn 7

EL LI

Oper veh [1

Simulated Distillation, TBP (°F) . 1/5 wit%’ 152/236 10/30 2871422 50 564 70/90 718/965 95/99 1062/1275 3 4 A commercially available nickel-Tungsten silica/alumina diesel hydrocracking catalyst was comparedto a hydroisomerization catalyst containing 25 weight 6 percent SAPO-11 on alumina with platinum present as the hydrogenation 7 component. The feed was dewaxed at a total pressure of 1000 psig, a liquid 8 hourly space velocity of 1.0, and a once through gas rate of 10,000 SCF 9 Ha/bbl. The products recovered from the dewaxing operation were not hydrofinished and had the properties shown in Table 2.

1 Table 2

Commercial PUSAPO-11 fe

ECAC CC

Yields, wt% }

Ca4- 1.0 1.6

Naphtha (C5-300°F) | 13.7 17.5 - }

Diesel (300-700°F) 69.2 64.0

Base Qil (700°F+) 16.2 16.0

Diesel Properties

Cloud Pt, °C 9 -35 . Vis@40°C, cSt 21 2.1

Base Oil Properties

Pour Pt, °C +13 -12

Vis@100°C, cSt 38 4.4

Vi 133 168 3 : 4 Table 2 illustrates that the Fischer-Tropsch product may be bulk dewaxed and successfully produce satisfactory yields of diesel arid lubricating base oil 6 having excellent properties. The diesel recovered using the PSAPO catalyst 7 hada significantly lower cloud point than the diesel recovered using the 8 conventional catalyst. When the lubricating base oils derived from the 9 dewaxing operations are compared, it should be noted that the product derived using the Pt/SAPO catalyst had a significantly lower pour point and 11 higher viscosity at 100 degrees C. in addition, the lubricating base oil product. 12 had a VI of 158 which is well in excess of that required to qualify as an ultra- 13 high Vl product.

Units which are used in this specification and which are not in accordance with the metric system may be converted to the metric system with the aid of the following table: 1 bar = 1x10° Pa 1 degree Celsius (°C) = (°F - 32) 5/9 1 pound per square inch (psi) = 6894.757 Pa 1 pound per square inch gauge (psig) = 6894.757 Pa (g) 1 SCF/bbl = 0.178m* Hy/m® 16A :

Amended sheet 03/04/2007

Claims (17)

ev Claims:

1. A process for producing low pour point syncrude products having an initial boiling point above about 150 degrees C from a Fischer-Tropsch plant which comprises: (a) recovering a Cs plus syncrude feedstock from a Fischer-Tropsch plant comprising a mixture of hydrocarbons boiling in the range of naphtha, diesel and lubricating base oils; (b) bulk dewaxing the entire Cs plus hydrocarbon feedstock in a hydroisomerization zone by contacting the Cs plus syncrude feedstock with a hydroisomerization catalyst under hydroisomerization conditions, whereby an isomerized Cs plus intermediate is produced having a lowered pour point relative to the Cs plus syncrude feedstock; (c) hydrofinishing the isomerized Cs plus intermediate in a hydrofinishing zone under hydrofinishing conditions, whereby a UV stabilized Cs plus product is produced; and (d) separately collecting from the UV stabilized Cs plus product a low pour point diesel product and a lubricating base oil product.

2. The process of claim 1 wherein the hydroisomerization catalyst comprises an intermediate pore size SAPO and at least one hydrogenation component comprising an active metal having hydrogenation activity.

3. The process of claim 2 wherein the hydroisomerization catalyst comprises at least one SAPO selected from the group consists of SAPO-11, SAPO-31 and SAPO-41.

4. The process of claim 3 wherein the hydroisomerization catalyst comprises SAPO-11.

S. The process of claim 2 wherein at least the one of the active metals is selected from the group consisting of platinum and palladium. 17 Amended sheet 03/04/2007

6. The process of claim § wherein at least one of the active metals is platinum.

7. The process of claim 2 wherein the active metal is added to the hydroisomerization catalyst by non-aqueous addition.

8. The process of claim 1 wherein the hydrofinishing consisting of step (c) comprise a pressure of between about 200 psig (1.379 x 10° Pa(g)) to about 3000 psig (2.068 x 107 Pa(g)).

9. The process of claim 8 wherein the hydrofinishing conditions comprise a pressure of between about 500 psig (3.447 x 10° Pa(g)) and about 2000 psig

(1.379 x 10” Pa(g)).

10. The process of claim 2 wherein the cut-point for the separation of the low pour point diesel product from the lubricating base oil product is pre-selected to maximize the yield of the low pour point diesel product.

11. A process for producing ultra high VI, low pour point lubricating base oil product from a Fischer-Tropsch plant which comprises: (a) recovering a Cs plus syncrude feedstock from a Fischer-Tropsch plant comprising a mixture of hydrocarbons boiling in the range of naphtha, : a diesel and lubricating base oils; (b) bulk dewaxing the entire Cs plus syncrude feedstock in a catalytic hydrodewaxing zone by contacting the Cs plus hydrocarbon feedstock with hydroisomerization dewaxing catalyst comprising an intermediate pore size zeolite and at least one metal having hydrogenation activity, said dewaxing being carried out under hydrodewaxing conditions selected to produce an Cs plus intermediate having a lowered pour point relative to the Cs plus syncrude feedstock; (c) hydrofinishing the Cs plus intermediate in a hydrofinishing zone under hydrofinishing conditions, whereby a UV stabilized Cs plus product is produced; and 18 Amended sheet 03/04/2007

(d) separately collecting from the UV stabilized Cs plus product an uitra high VI, low pour point lubricating base oil product.

12. The process of claim 11 wherein the intermediate pore size zeolite is also characterized by having one-dimensional pores.

13. The process of claim 11 wherein the intermediate pore size zeolite having one dimensional pores comprises at least one zeolite selected from the group consisting of SSZ-32, ZSM-22 and ZSM-23.

14. The process of claim 11 wherein at least one of the active metals is selected from the group consisting of platinum and palladium.

15. The process of claim 14 wherein at least one of the active metals is platinum.

16. The process of claim 11 wherein the hydrofinishing conditions of step (c) comprise a pressure of between about 200 psig (1.379 x 10° Pa(g)) to about 3000 psig (2.068 x 107 Pa(g)).

17. The process of claim 16 wherein the hydrofinishing conditions comprise a pressure of between about 500 psig (3.447 x 10° Pa(g)) and about 2000 psig

(1.379 x 10’ Pa(g)). 19 Amended sheet 03/04/2007