CA1282363C - Process for catalytic dewaxing of more than one refinery-derived lubricating base oil precursor - Google Patents

Abstract

A B S T R A C T

PROCESS FOR CATALYTIC DEWAXING OF MORE THAN ONE
REFINERY-DERIVED LUBRICATING BASE OIL PRECURSOR

A process for catalytic dewaxing of more than one refinery-derived lubricating base oil precursor which comprises contacting in a first reaction zone in the presence of a hydrogen-containing gas at hydrodewaxing conditions a first feed stream comprising a first refinery-derived raffinate lubricating base oil precursor which contains a first wax comprising straight-chain paraffins with a first hydrodewaxing catalyst selective for conversion of said first wax and contacting in the presence of a hydrogen-containing gas at hydrodewaxing conditions in a parallel-situated second reaction zone a second refinery-derived raffinate lubricating base oil precursor which contains a second wax containing branched and/or cyclic hydrocarbons with a second hydrodewaxing catalyst selective for conversion of said second wax, and optionally contacting in one or more further reaction zones further refinery-derived waxy raffinate lubricating base oil precursor feed streams in the presence of a hydrogen-containing gas at hydrodewaxing conditions with a hydrodewaxing catalyst, and removing at least two parallel effluent streams of refinery dewaxed lubricating base oils from said reaction zones.

Description

~2~323~3 I

PROCESS FOR CATALYTIC DEW~XING OF MDRE THAN CNE
REFINERY-DERIVED L~BRICATING ~ASE OIL PRECURSOR

The invention relates to a process for catalytic dewaxing of more than one refinery-derived lubricating base oil precursor.
In the production of lubricating base oils from different distillates or deasphalted residual oils, a problem arises in regard to removing waxy materials from the lubricating base oil precursors. m e presence of these waxy materials is very undesirable in that they inure a high pour poLnt to the ultimate lubri Qting oil and thereby reduce or totally eliminate the eff~ctiveness of the lubricating oil at low temperatures.
TWD general methods for dewaxing these petroleum distillates include solvent dewaxing and catalytic dewaxing. The former has recently lost favour in light of its relatively high capital cost and its relatively high operating cost. The latter is scmetimes referred to as hydrodewaxing and has been explored extensively.
~5 This technology has given rise to a whole new spectrum of catalysts which have been referred to by R.M. B~rrer in his work, "Hydrothermal Chemistry of Zeolites" as tectosilicate catalysts which mclude aluminosilicates, borosilicates, etc. Essentially, it is desired to employ a tectosilicate catalyst with a pore size such that the long chain paraffin materials along with other waxy materials have selective access to the interior of the tectosilicate sieve while prohibiting entry of the non-waxy materials, which, of coursP, do not necessitate hydrodewaxing.
From a crude oil feed in many cases lubricating base oil precursors can be derived which are commonly classified as (Light) HVI 80 to 100 or 80 to 150, (~edium~ HVI 250 to 300, (Heavy) ~q 500 to 600 and HVI Bright Stock raffinate (hereinafter referred to as Bright Stock~, all of which necessitate dewaxing before they can be used as lubricating base oil (components~.

.. ~

~282~63 Succinctly, there has not yet been developed a unitary tecto-silicate or aluminosilicate catalytic composition which can selec-tively convert the paraffinic or other waxy materials in all of these petroleum substrates to selectively excise the problem waxy material and still attain the quality targets demanded by the marketplace. One reason for this dilemma is that the waxy materials, which are considered contaminants, vary greatly from stream to stream and are not simply straight-chain paraffins but include branched and cyclic structures as well. Thus, one catalyst with a specific consistent pore size will simply be unable to selectively treat all of the waxy materials present in all of these lubricating base oil precursors.
In U.S. Patent 4,222,855, issued in 1980, it was determ med that a 2SM-23 or ZSM-35 catalyst possesses the ability to produ oe a dewaxed oil with a superior viscosity index relative to a ZSM-5 type catalyst. This reference failed to teach or acknowledge however, that ZSM-35 is incapable of dewaxing an oil heavier than a light neutral to a pour point target currently demanded by the marketplace. Nor did it teach or ackncwledge that this characteristic results from the special relationship between catalyst pore dimensions and the molecular structure of wax molecules intr msic to lubricating oil streams of differing viscosity ri~nges. In U.S. Patent 4,372,839 recognition is made that a Z~M-35 catalyst alone is incapable of reducing the pour point to the most desired lowest level, hcwever, this deficiency is resolved by a series flow technique of a common ch3rge stream with both types of zeolites, i.e. a first contact with a Z~M-35 aluminosilicate and then a second with a Z5M~5 aluminosiiicate.
Prior patentees have also taken cognizan oe of the fact that a feedstream to a hydrodewaxing unit may be divided and only a portion of the feedstream treated in a hydrodewaxing unit. For instance, in U.S. Patent 3,956,102, issued in 1976 to Chen et al, the patentees teach separation of a petroleum distillate whereby only one of the separated streams is treated with a ZSM~5 type . . , .

iL282~j3 I

Succinctly, there has not yet been developed a unitary tecto-silicate or aluminosilicate catalytic composition which can selec-tively convert the paraffinic or other waxy materials in all of these petroleum substrates to selectively excise the problem waxy material and still attain the quality targets demanded by the marketplace. One reason for this dilemma is that the waxy materials, which are considered contaminants, vary greatly from stream to stream and are not simply straight-chain paraffins but include branched and cyclic structures as well. Thus, one catalyst with a specific consistent pore size will simply be unable to selectively treat all of the waxy materials present in all of these lubricating base oil precursors~
In U.S. Patent 4,222,855, issued in 1980, it was determined that a ZSM-23 or ZSM-35 catalyst possesses the ability to produ oe a dewaxed oil with a superior viscosity index relative to a ZSM-5 type catalyst. This reference failed to teach or acknowledge however, that ZSM-35 is incapable of dewaxing an oil heavier than a light neutral to a pour point target currently demanded by the marketplace. Nor did it teach or acknowledge that this characteristic results fro~ the special relationship between catalyst pore dimensions and the mo.lecular structure of wax mc)lecules intrinsic to lubricating oil streams of differing viscosity ranges. In U.S. Patent 4,372,839 recognition is made that a ZgM-35 catalyst alone is incapable of reducing the pour point to the most desired lowest level, however, this deficiency is resolved by a series flow technique of a oomman charge stream with both types of zeolites, i.e. a first contact with a Z~M-35 aluminosilicate and then a second with a Z5M~5 aluminosiiicate.
Prior patentees have also taken cognizance of the fact that a 3Q feedstream to a hydrodewaxing unit may be divided and only a portion of the feedstream treated in a hydrodewaxing unit. For instance, in U.S. Patent 3,~56,102, issued in 1976 to Chen et al, the patentees teach separation of a petroleum distillate whereby only one of the separated streams is treated with a ZSMr5 type , , ' ~ ' ` ,, ' ' ', .

-- 3a - 63293-2734 zones Eurther refinery-derived waxy raf:Einate lubricating base oil precursor feed streams in the presence of a hydrogen-conta.ining gas at hydrodewaxing conditions with a hydrodewaxing catalyst, and removing at least two parallel effluent streams of refinery dewaxed lubricating base oils from said reaction zones.
Both of the types of catalyst utilized in the instant selective parallel passage hydrodewaxing process are existent in the prior art as known dewaxing catalysts. For instance r a ZSM-S
type molecular sieve is disclosed in U.S. Patent 3,702,886 and taught for hydrodewaxing applications. Alsor in U.S. Patent 4,343 r 692 r a synthetic ~28X~363 ferrierite zeolite is disclosed having incorporated therewith at least one metal selected from the group consisting of Group VIB, Group VIIB and Group VIIIB metals. However, it has heretofore gone unrecognized that molecular sieves with pore dimensions similar to those of ferrierite are unable to dewax certain types of feed material to the specifications required by the marketplace but yet are surprisingly and unexpectedly effective in their conjunct interaction for selective parallel flow dewaxing of particular types of feed material when coupled into a process employing a dewaxing catalyst with pore dimensions similar to or larger than ZSM-5.
The process according to the invention suitably comprises three or more parallel operated catalytic hydrodewaxing zones.
One emkodiment of the invention resides in a process for ~he preparation of four or more dewaxed lubricating base oils fram a crude oil feed stream which comprises: charging said crude oil feed stream to an atmospheric distillation column maintained at a pressure between l.7 and 6.7 bar abs., at a bottoms temperature between 232 C and 399 C, and an overhead temperature of 204 C to 316 C to separate said crude oil feed stream into at least a light overhead stream, which is withdrawn from said atmospheric distillation unit, camprising heavy gas oil and lighter hydrocarbons and a bottsms stream, which is rem~ved from said distillation unit, ccmprising heavier than heavy gas oil hydrocarbons; withdrawing said heavy gas oil and lighter hydrocarbons and passing the same to an~ther refinery unit for further processing; charging the bottoms effluent from said atmospheric distillation column containing heavi~r than heavv gas oil to a vacuum distillation column maintained at an overhead pressure between 0.02 and 0.09 bar abs. and at an overhead temperature from 38 C to 93 C and at a bottoms pressure from 0~l3 bar abs. to 0.33 bar abs. and at a bottoms temperature between 316 C and 399 C to derive at least four raw lubricating oil process effluent streams co~prising:
i. a Light Vacuum Gas Oil overhead stream, ii. a High Viscosity Index 80-l00 or 30-l50 distillate, 9~823G3 iii. a High Viscosity Index 250 to 300 distillate, iv. a High Viscosity Index 500 to 600 heavy distillate, and v. a bottQms stream containing residual distillate; and then passing said bottams stream residual distillate to a deasphalting unit wherein said residual distillate is contacted with a solvent to deasphalt said residual distillate to form an asphalt-rich stream and a deasphalted lubricating oil ~DAO) stream; removing said asphalt-rich stream from said deasphalting unit; withdrawing said deasphalted lubricating oil ~DAO) frcm said deasphalting unit;
individually passing said HVI 80-100 or 80-150 distillate, HVI 250 to 300 distillate, HNI 500-600 distillate and said n~o hydrocarbon streams through a solvent extraction step wherein said solvent extraction step is per~ormed separate and apart for each stream and passing the respective aoquired solvent extracted HVI 80 to 100 or 80 to 150 waxy raffinate, HVI 250 to 300 waxy raffinate, HVI 500 to 600 waxy raffinate and wherein said DAO stream is con~erted to a Bright Stock waxy raffinate passed to a selective catalytic dewaxing step comprising: passing said HVI 80 to 100 or 80 to 150 waxy raffinate stream through a first catalytic dewaxing unit containing a catalyst camprising a synthetic ferrierite zeolite having incor-porated therein at least one metal selected from the group consisting of Group VIB, Group VIIB and Group VIII metals of the Periodic Table to arrive at a substantially dewaxed HVl 80 to 100 or 80 t~
150 stream having a pour point of below -4 C, passing said solvent extracted HVI 250 to 300 waxy raffinate stream thr~ugh a second catalytic dewaxing zone having therein a catalyst comprising an admuxture of a synthetic ferrierite zeolite having incorporated therein at least one metal selected from the group consisting of Group VIB, Group VIIB and Group VIII metals of the Periodic Table in association with a crystalline aluminosilicate zeolite having a oomposition in terms of mole ratios of, as follows:
M2/n A123 : 5-100 SiO2 0_40 H2O
wherein M is a cation, n is the valence of said cation and wherein said pore size of said zeolite is between 0.5 nm and 0~9 nm to arrive at a substantially dewaxed HVI 250 to 300 lubricating oil ~8'~363 having a pour point of below -4 C; passing said solvent extracted HVI 500 to 600 waxy raffinate stream through a third catalytic dewaxing zone having therein a catalyst comprising an admixture of a synthetic ferrierite zeolite having incorporated therein at least one metal selected from the group consisting of Group VIB, Group VIIB
and Group V1II metals of the Periodic Table in association with a crystalllne aluminosilicate zeolite having a composition, in terms of mole ratios, of as follows:

2/n : A12O3 : 5~100 SiO2 : 0-40 H2O
where m M is a cation, n is the valence of said cation and wherein said pore size of said zeolite is between 0~5 nm and 0.9 nm to arrive at a substantially dewaxed HVI 500 to 600 lubricating oil having a pour point of below -4 C; passing said Bright Stock ~axy raffinate stream through a fourth alu~unosilicate zeolite having a oamposition, in terms of mole ratios, of as follaws:
2/n A123 : 5-100 SiO2 : 0-40 H2O
wherein M is a cation, n is the valence of said cation and wherein said pore size of said zeolite is between 0.5 nm and 0,9 nm to derive a substantially dewaxed Bright Stock raffinate lubricating oil having a pour point of below -4 C.
All of the ~forementioned four respective lubricating base oil precursor streams contain different waxy contamunants, i.e. waxy co0Fonents which elevate the pour point to a degree such that the oils are less attractive for their intended use. These streams differ in their molecular character and viscosity~ It is also possible that but two streams are attained that necessitate dewaxing, usually (1) a light stream HVI 80 to 100 or 80 to 15a and ~2) a heavy Bright Stock stream. It is also possible that three or more streams of different viscosities are derivable from such separatory systems. This invention pertains to treating in order to substantially dewax any two or m~re such streams in parallel flow arrangement.
In treating any of these streams various tectosilicate catalysts have been employed. One family of these tectosilicates are ncmenclated as ZSM-5 alum mosilicate oo~positions which have been characterized by their X-ray diffraction pattern as set forth in Table 1 of U.S.
Patent 3,852,189, Chen et al.

~L2~3X363 Other catalysts are also contemplated as one of the catalytic compositions of matter useful in this invention. For instance, mordenites, crystalline borosilicates and silicalites may also be used. The mordenite may be modified by cation exchange including but not restricted to mordenites m~dified by cation exchange with H, Be, Mg, Tl, Ce, Nd, Pb, Thr Nb, Rh, Ba, Sr, La, and Ca. It also includes but is not restricted to mordenite modified by vapour deposition techniques employing co~pounds such as metal chlorides.
m e second family of tectosilicate catalysts are those which selectively dewax relatively light lubricating oils such as an HVI
80 to l00 or 80 to 150 waxy raffinate in contrast to the above aluminosilicates which selectively dewax the heavier lubricating oils. One example of such catalyst is exemplified by the disclosure of Winquist U.S. Patent 4,343,692. Other such catalysts are ZSM-35, ZSM-23, ZS~1~38, ZSM-21 and natural ferrierite, treated or untreated, with or without the presence of catal~tic metals thereon.
It is also conceivable that both such catalysts are disposed on the same ~support and vary by the metals incorporated thereon, the strength of the acid sites, or by the cations incorporated into the support such that one catalyst will selectively react with the wax species characteristic of light lube stocks while the other catalyst selectively reacts with the wax species characteristic of heavier lube stocks.
While both of the aforementioned types of dewaxing catalysts have been known to adequately dewax certain feed materials, there has been no recognition that these two types of catalysts, used in conjunct simultaneous intexaction, provide an unexpectedly m~re viable dewaxing process where a refiner is confronted with the dilemma of dewaxing a whole spectrum of differing lubricating oils.
Two catalysts~ one with pore dimensions similar to ferrierite and the other with pore dimensio~s equal to or greater than ZSM-5, will solve this dilemma because the wax species intrinsic to light lubricating oils is different form the wax species intrinsic to heavier l~ricating oils.
The dewaxing step or steps of this invention are undertaken in .

.

the presence of hydrogen, preferably at a hydrogen circulation rate of between 350 and 2670 l(S.T.P.) H2/1 oil feed. The expression "S.T.P." indicates Standard Temperature (of 0 C) and Pressure (of 1 bar abs.). The reaction conditions are usually maintained at a temperature of between 150 C and 500 C and a pressure between 2 and 200 bar abs., preferably between 2 and 20 bar abs. The liquid hourly space ~elocity (LHSV) preferably will be frcm 0.1 to 10 and more preferably between 0.5 and 5Ø
The raw lubricating oils contemplated herein to be treated in parallel flcw generally contain in the range of frcm 0.1 to 50% by weight of waxy hydrocarbons (by this latter term it is meant normally solid hydrocarbons at 3 C below pour point temperatures~.
Pour point is defined on the basis of the ASIM D-97 Test Method.
Example pour points for finished oils are -18 C for HVI 80 to 100 or 80 to 150 and -7 C for HVI Brights Stock. It is critical to the operation of this invention to properly select the particular feed material for the particular dewaxing catalyst. First inquiry must be made as to the type of undesired waxy hydro arbons existent in the lubricating base oil precursor because it has been discovered that the t~pe of waxy material present in the HVI 80 to 100 or 80 to 150 type of waxy raffinate lubricating base oil precursor is different from the waxy material m dig~nous to the HVI 250 to 300, ~1 500 to 600 or Bright Stock waxy raffinates. In fact, it oomes as a surprise that those waxes intrinsic to raw lubricating oils heavier than HVI 80 to 100 or 80 to 150, contain a greater proportion of branched and cyclic struc~ures than does HVI 80 to 100 or 80 to 150. It is indeed this discovery which accounts for the heretofore unrecognized problem with catalysts which have pore dimensions similar to ferrierite, i.e. they are unable to remove cyclic wax structures and, therefore, are incapable of dewaxing lube oil streams heavier than HVI 150 to the pour point demanded by the marketplace.
It is believed that the waxy materials present in HVI 80 to 100 or 80 to 150 lubricating oil have an average car~on number o~
23 although the individual constituents of this stream are kncwn to encompass a range of hydrocarbon components including minute .. . . ~ . . ~ ~ . ... . .. .

~282~3 g quantities with 18 carbon atoms and 31 carbon atoms. It is believed that waxy materials present in HVI 250 to 300 have an average carbon number of 29 or 31 depending on the crude source. HVI 250 to 300 is known to encompass a range of hydrocarbon components including quantities of hydrocarbons with 24 carbons to 37 carbons. It is believed that the waxy hydrocarbons in HVI Bright Stock have an average carbon number of 38. HVI Bright Stock is kncwn to encGmpass a range of hydrocarbon oamponents which include quantities of hydrocarbons with 22 carbon atoms to 52 carbon atcms. The wax content of the first waxy raffinate (HVI 80 to 100 or 80 to 150) may have more than 45% by weight of normal paraffins in contrast to other waxy raffinate streams, such as HVI Bright Stock which may have less than 10~ by weight of normal paraffin ccmponents. m is concentration of normal paraffin wax structures is dependent on the crude oil feed charged to the unit. It was surprising to find such a large content of branched and cyclic ccmponents in the heavy oil i.e. more than 55% by weight while the light oil contained less than 55% by weight of branched and cyclic components.
The co~plimentary independent parallel flow simultaneous interaction of the two catalysts for dewaxing, one with pore dimensions similar ~o ferrierite and the other with pore dimensions similar or larger than Z5M-5 will result in a reduction in the design size of particular dewaxing reactors, although m~re reactors may be necessary. The flexibility to cease dewaxing over one type of catalyst (while the other continues to simultaneously function) and perform select reactivation prior to reaching high end-of-run temperatures will significantly and surprisingly result in a greatl~ lengthened viable life span of the large pore catalyst without the penalty of lost production. Also, by avoiding a complete shutdown of the plant as a result of catalyst reactivation the overall dewaxing plant can have a smaller design, be constructed with less offsite tankage and be designed with less catalyst inventory for each reactor. If a plant error occurs and a contaminant like sodium, for example, is allowed into one reactor, the other 323~3 may continue to function uni~peded. And if the crude oil feed of the refinery changes, the market target projections can still be maintained due to the flexibility of the complimentary catalysts.
In this parallel passage flow system a continuous operation of dewaxing is contemplated and preferred. When a certain catalyst becomes deactivated due to occlusion by trapped hydrocarbons or weakly held catalyst poisons it is a simple procedure to cease the dewaxing step and begin a hydrogen reacti~ation of the catalyst.
This hydrogen reactivation is performed in the presence of a 10hydrogen~containing gas at a temperature between 343 C and 538 C.
One dewaxing catalyst can be reactivated or regenerated while other dewaxing catalysts continue to perfonm their respective catalytic function until they too become spent and thereby necessitate reactivation.
15An oxidative regeneration of the catalyst may be undertaken in situ or more preferably the regeneration may be performed at an offsite location in a separate regeneration vessel by passage of an oxygen-containing gas thereover at a temperature form 371 C to 566 C for a period of time sufficient to remove coke deposits and thereby regenerate the dewaxing catalyst. Thereafter the regenerated catalyst is passed back to its respective dewaxing reactor vessel.
The oxygen-containing gas can be air, pure oxygen or mlxtures of oxygen with any other inert gas such as nitrogen or argon.
It is contemplated within the scope of this invention to treat at least two, and even four lubricating base oil precursor streams derived from a vacuum distillation unit as described hereinbefore.
Howe~er, these streams can be commingled within the scope of this invention as long as at least two different catalysts are applied in parallel flow reaction zones for converting the particular undesired waxy materials present therein. It is also contemplated that dcwnstream of the overall catalytic dewaxing process, estab~
lished techniques, including cla~ treating and hydrofinishing, can be used to enhance the colour and stability of the dewaxed oil. It is further contemplated that downstream of the overall catalytic dewaxing process, normal blending techniques can be utilized to 12a~,3~3 prepare any type of lubricating base oil or industrial oil, such as an automotive engine oil, transfonmer oil, compressor oil, railroad oil, refrigerator oil, hydraulic oil, gear oil, or any other lubricant necessitating specific qualities of pour point at a S certain te~perature.
m e invention also relates to catalytically dewaxed lubricating base oils whenever prepared by a process as described hereinbefore.
In the Figure a flow scheme is depicted which is exe~plary of the production of four different dewaxed lubricating base oils beginning from a crude oil feed material although the process scheme can be used with as few as two respective lubricating oil streams.
m e instant flcw scheme is given without regard to miscellaneous auxilliary equip~ent necessary to perform the process flow such as various pumps, condensors, receivers and so forth. Th process flow scheme is not to be construed as a limitation upon the instant novel parallel flow process. In the Figure a crude oil in conduit l is charged to fractionation column 3 wherain a light prcduct stream is withdrawn through conduit 5, either overhead or as a sidecut stream or both, and is removed from the procass and passed along for further processing to recover other hydrocarbon minerals. me bottoms stream from fractionation column 3 is withdrawn through conduit 7 and passed to vacuum di~til:Lation unit 9. This stream contains all of the material heavier than a heavy gas oil. In the vacuum distilLation column up to five streams are derived with the overhead stream being withdrawn in conduit ll having an initial boiling poLnt of about 238 C and a 50% boiling point of about 354 C, which also may be further processed according to known conventional processing techniques for its mineral value. Three streams are exemplified as being withdrawn from the vacuum distil-lation unit as side~ut streams ~I 80 to lO0 or 80 to lS0, HVI 250 to 300 and HVI 500 to 600 raw undawax~d distillates containing waxy material which result in a pour point of such a magnitude to vitiate target projection of the open lubricating oil markatplace.
An HNI 80 to lO0 or 80 to 150 distillate stream is withdrawn via ;, . . . . .
. .

~ ~23~i3 conduit 13, an HVI 250 to 300 distillate stream is withdrawn via conduit 15 and an HVI 500 to 600 distillate stream is withdr~wn via conduit 17. A fifth stream, withdrawn fram the bottom of vacuum distillation unit 9 via conduit 19, contains heavy materials, such as asphalt and residua. This stream is passed to deasphalting unit 21 wherein an asphalt-rich product is withdrawn in conduit 23 concomitant with the deasphalted oil withdrawn in conduit 25. This stream commonly ncmenclated as (DAO) also has indigenous undesirable waxy material which raises the pour point of the lubricatin~ oil to a degree to render same unsuitable for most commercial use.
It is optional in this invention to utilize a preliminary solvent extraction system to treat the waxy lubricating oil distil-lates. The solvent is any conventional extraction ~olvent such as phenol, N-methyl-2-pyrrolidone, furfural, etc. These solvent streams are added to respective batch extraction units 27, 29, 31 and 33 through conduits 35, 37, 39, and 41. A slip stream or bottom contanll~Lnt stream is withdrawn containing extracted aromatics, nitrogen and sulphur ccmpounds in streams 43, 45, 47 and 49, which may likewise be treated in a distillation column (not shown herein) for return of the solvent to the solvent extraction system(s)O This is also true for a portion or the entirety of streams 51, 53, 55 and 57. It is i~portant to note that this solvent extraction system can be perfonmed in a batch type method in a multitude of zones or the same can be performed in one zone, one-at-a-time, with only one respective particular waxy raffinate stream derived frcm the vacuun distillation col~nn being solvent extracted at one time. The respective effluent streams from the solvent extraction zone in conduits 51, 53, 55 and 57 are passed into optional hydrotreating systems 5~, 61, 63 and 65 which have ingress of hydrogen through conduits 67, 69, 71 and 73. While these hydrotreaters are shown as different units, they may physically be one integrated vessel use~ul for treating a multitude of streams. It is also contemplated that the hydrotreating be performed before the solvent extraction.
Ei~her way, the pre-dewaxing hydrotreating zon~ is purely optional and its presence or placement does not form an integral process ~8Z3~;3 parameter of the instant flow scheme contemplating the dual bed parallel passage flGw of lubricating base oil precursors to different hydrodewaxing catalysts.
The function of the hydrotreater is to excise additional arcmatic compcunds, sulphur compounds, nitrogen compounds and convert complex aromatic ccmpounds to simpler arcmatic compounds which renders the catalytic dewaxing processing more feasible.
Hydrotreating is performed at mild hydrotreating conditions, which include a temperature of from 260 C to 454 C and a pressure from 74 bar abs. to 107 bar abs. The hydrogen may be present concamitant with an inert gas or the same may be present in its pure form. It is also contemplated that a refinery stream such as a reformer gas stream may be utilized as the source of hydrogen. Once again, however, it should be pointed out that this pre-dewaxing hydro-treatment step is optional, and need not be performed to accamplish the goals of this invention. The solvent extracted, or if desired, hydrotreated effluent streams, are withdrawn fram respective (or one single hydrotreater operating in blocked out mode) from hydro-treaters 59, 61, 63 and 65 through corlduits 75, 77, 79 and 81. Ihey are passed directly to the respective appropriate catalytic dewaxing steps 83, 85, 87 and 89, which are pr~vided with hydrogen entry ports 91, 93, 95 and 97. The respective dewaxed lube oils are withdrawn frcm respective catalytic dewaxing units ~or as few as two units) 83, 85, 87 and 89 through conduits 99, 101, 103 and 105 for further blending.
After production of these streams hydrotreating is normally undertaken to Eurther refine the finished dewaxed product. One salient advantage of this invention is that use of ferrierite catalyst in dewaxing zone 83 totally vitiates the need to hydrotreat the product in conduit 99 after blending wi~h other feed streams.
Rendering this expensive and potentially troublesome extra process step superfluous surprisingly produces an overall prvcess much more efficient and less expensive than any other type process which requires that the dewaxed light oils are to be hydrotreated. If desired, the light oil dewaxed effluent steam may be hydrotreated ' ~X8;~363 within the scope of this invention although, to do 50 iS a processing of the dewaxed oil in a non-economically rewarding sequence of steps. In summary, this process produces a light HVI 80 to 100 or 80 to 150 lubricating base oil using a more efficient catalyst without the necessity for hydrotreating, in the presence of hydrogen, the dewaxed oil concomitant with other heavy dewaxed oils which may necessitate dewax mg.
Another embodiment of this invention comprises the passage of the DAO stream d;rectly from deasphalting unit 21 to hydrotreater 65 o without need for the solvent extraction step, said pre-dewaxing hydrotreating being carried out at mild to severe hydrotreating conditions, i.e. over 74 bar abs. pressure and cver 260 C.
Hydrotreated effluent is passed via conduit 81 to catalytic dewaxing unit 89 for aforementioned treatment.
It is also optional in this invention to utilize a preliminary solvent dewaxing system to treat the waxy lubricating oil raffinates, especiallv those requiring very low pour points, for example below -18 C. m e solvent is any conventional dewaxing solvent such as propane, or alkyl ketones in admlxture with an aromatic component, i.e. methylethyl ketone and toluene. I'hese streams may be added in a batch processing manner. The solvent may be recovered by distil-lation and reused in the solvent dewaxing process. This preliminary solvent dewaxing can be performed in A multitude of zones or the same can be performed in one zone using a batch-type method one-at-a-time with each such particular waxy raffinate derived frcm the vacuum distillation column.
The preferred catalyst in hydrogen dewaxing unit 83 is one with a pore size similar to the pore size of synthetic ferrierite.
~he preferred catalyst of hydrogen dewaxing unit 89 (for the Bright Stock waxy raffinate) is a catalyst with a pore size similar or larger than the pore size of the ZSM-5 catalyst taught in U.S.
Patent 3,702,886. ~he latter can also be used in hydrogen dewaxing ur~ts 85 and 87 with or without accompaniment of a smaller pore zeolite. Again, the use of the preferred ferrierite-containing catalyst obviates post-d~waxing hydrotreatment.

The process conditions present in the fractionation column 3 or 9, deasphalting unlt 21, solvent extraction units 27, 29, 31, 33 and the hydrotreating units 59, 69, 71 and 73 are well kncwn to those of reasonable skill in the art. Hydrotreating conditions and applicable catalysts for hydrotreating streams 101, 103, 105 or same if cGmbined with stream 99, are likewise well-recoynized. The process conditions present during the hydrodewaxing steps in reactors 83, 85, 87 and 89 are those alluded to previously above.
It will not require any type of expertise or undue experimentation for one to ascertain the most desirable conversion conditions once the ~eed material is selected for the particular catalytic composi-tion of matter of respective units 83, 35, 87 and 89.

Claims (11)

1. A process for catalytic dewaxing of more than one refinery-derived lubricating base oil precursor, which process comprises contacting in a first reaction zone in the presence of a hydrogen-containing gas at hydrodewaxing conditions a first feed stream comprising a first refinery-derived raffinate lubricating base oil precursor which contains a first wax comprising straight-chain paraffins, said first wax containing less than 55% by weight of branched and cyclic hydrocarbons, with a first hydrodewaxing catalyst selective for conversion of said first wax and contacting in the presence of a hydrogen-containing gas at hydrodewaxing conditions in a parallel-situated second reaction zone a second refinery-derived raffinate lubricating base oil precursor which contains a second wax containing more than 55% by weight of branched and/or cyclic hydrocarbons with a second hydrodewaxing catalyst selective for conversion of said second wax, and optionally contacting in one or more further reaction zones further refinery-derived waxy raffinate lubricating base oil precursor feed streams in the presence of a hydrogen-containing gas at hydrodewaxing conditions with a hydrodewaxing catalyst, and removing at least two parallel effluent streams of refinery dewaxed lubricating base oils from said reaction zones.

2. A process according to claim 1 wherein the lubricating base oil precursor feed streams are obtained by fractionating a bottoms stream of an atmospheric distillation of a hydrocarbon oil feed stream.

3. A process according to claim 1 or 2 wherein the hydrodewaxing conditions comprise a temperature between 150°C and 500°C, a pressure between 2 and 200 bar abs. and a hydrogen/ oil feed ratio between 350 and 2670 1(S.T.P) H2/1 oil feed.

4. A process according to claim 1 wherein the first hydrodewaxing catalyst comprises a synthetic ferrierite having incorporated therewith at least one metal selected from the group consisting of Group VIB, Group VIIB and Group VIII metals of the Periodic Table.

5. A process according to claim 4 wherein a first feed stream comprising an HVI 80 to 150 or 80 to 100 waxy lubricating oil precursor is hydrodewaxed in the first reaction zone from which a lubricating base oil is obtained without subsequent hydrotreating.

6. A process according to claim 1 or 2 wherein the second hydrodewaxing catalyst comprises a crystalline aluminosilicate having a pore size from 0.5 to 0.9 nm and a composition, in terms of mole ratios, as follows:

0.9 ? 0.M2/nO : Al2O3 : 5-100 SiO2 : 0-40H2O

wherein M is a cation and n is the valence of said cation.

7. A process according to claim 1 or 2 which comprises at least three, and preferably four or more parallel-situated catalytic hydrodewaxing zones.

8. A process according to claim 1 wherein each hydrodewaxing catalyst is regenerated independently of the dewaxing operation(s) in the other dewaxing reaction zone(s) in the presence of an oxygen-containing gas at a temperature from 371°C to 566°C.

9. A process according to claim 8 wherein said regeneration is followed by an inert gas purge of the regenerated catalyst and subsequent reactivation in the presence of a hydrogen-containing gas at a temperature from 343°C to 538°C.

10. A process according to claim 1 or 2 wherein at least two dewaxed lubricating base oils are blended to formulate at least one lubricating oil product.

11. Catalytically dewaxed lubricating base oils whenever prepared by a process according to claim 1 or 2.