[0001] The invention relates to a process for catalytic dewaxing of more than one refinery-derived
lubricating base oil precursor.
[0002] 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. The presence of these waxy materials is very undesirable in that
they inure a high pour point to the ultimate lubricating oil and thereby reduce or
totally eliminate the effectiveness of the lubricating oil at low temperatures.
[0003] Two 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 sometimes
referred to as hydrodewaxing and has been explored extensively. This technology has
given rise to a whole new spectrum of catalysts which have been referred to by R.M.
Barrer in his work, "Hydrothermal Chemistry of Zeolites" as tectosilicate catalysts
which include 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 course, do not necessitate hydrodewaxing.
[0004] 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, (Medium) HVI
250 to 300, (Heavy) HVI 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).
[0005] Succinctly, there has not yet been developed a unitary tectosilicate or aluminosilicate
catalytic composition which can selectively 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.
[0006] 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 produce 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 from the special relationship between
catalyst pore dimensions and the molecular structure of wax molecules intrinsic to
lubricating oil streams of differing viscosity ranges. In U.S. Patent 4,372,839 recognition
is made that a ZSM-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 common charge stream with both types of zeolites, i.e. a first contact with a
ZSM-35 aluminosilicate and then a second with a ZSM-5 aluminosilicate.
[0007] Prior patentees have also taken cognizance 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 catalyst while the untreated stream is subsequently combined
with the hydrodewaxed product to yield a net production of hydrogen.
[0008] An object of the invention is to provide a viable refinery dewaxing process flow
scheme to selectively treat more than one refinery-derived lubricating base oil precursor
in parallel flow in contrast to providing different catalysts in admixture in a single
reactor which are respectively insufficient to treat one type of lubricating base
oil precursor but highly efficient to treat another type of lubricating base oil precursor.
Accordingly, a multiple number of dewaxed lubricating base oils having excellent pour
points and viscosity indices can be obtained.
[0009] The invention therefore relates to 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.
[0010] 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, a ZSM-5 type molecular sieve is disclosed in U.S. Patent 3,702,886 and taught
for hydrodewaxing applications. Also, in U.S. Patent 4,343,692, a synthetic 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.
[0011] The process according to the invention suitably comprises three or more parallel
operated catalytic hydrodewaxing zones.
[0012] One embodiment of the invention resides in a process for the preparation of four
or more dewaxed lubricating base oils from a crude oil feed stream which comprises:
charging said crude oil feed stream to an atmospheric distillation column maintained
at a pressure between 1.7 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, comprising heavy gas oil and lighter hydrocarbons and
a bottoms stream, which is removed from said distillation unit, comprising heavier
than heavy gas oil hydrocarbons; withdrawing said heavy gas oil and lighter hydrocarbons
and passing the same to another refinery unit for further processing; charging the
bottoms effluent from said atmospheric distillation column containing heavier than
heavy 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 0.13 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 comprising:
i. a Light Vacuum Gas Oil overhead stream,
ii. a High Viscosity Index 80-100 or 80-150 distillate,
iii. a High Viscosity Index 250 to 300 distillate,
iv. a High Viscosity Index 500 to 600 heavy distillate, and
v. a bottoms stream containing residual distillate; and then passing said bottoms
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)
from said deasphalting unit; individually passing said HVI 80-100 or 80-150 distillate,
HVI 250 to 300 distillate, HVI 500-600 distillate and said DAO hydrocarbon streams
through a solvent extraction step wherein said solvent extraction step is performed
separate and apart for each stream and passing the respective acquired 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 converted 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 comprising 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 to arrive at a substantially dewaxed
HVI 80 to 100 or 80 to 150 stream having a pour point of below -4 °C, passing said
solvent extracted HVI 250 to 300 waxy raffinate stream through a second 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 VIII metals of the Periodic Table in association
with a crystalline aluminosilicate zeolite having a composition in terms of mole ratios
of, as follows:
0.9 ± 0.2 M
2/nO : Al₂O₃ : 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 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 VIII metals of the Periodic Table in association
with a crystalline aluminosilicate zeolite having a composition, in terms of mole
ratios, of as follows:
0.9 ± 0.2 M
2/nO : Al₂O₃ : 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 500 to 600 lubricating oil having a pour point of below -4 °C; passing said Bright
Stock waxy raffinate stream through a fourth aluminosilicate zeolite having a composition,
in terms of mole ratios, of as follows:
0.9 ± 0.2 M
2/nO : Al₂O₃ : 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.
[0013] All of the aforementioned four respective lubricating base oil precursor streams
contain different waxy contaminants, i.e. waxy components 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 150 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 more such streams in parallel flow arrangement.
[0014] In treating any of these streams various tectosilicate catalysts have been employed.
One family of these tectosilicates are nomenclated as ZSM-5 aluminosilicate compositions
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.
[0015] 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 modified by cation exchange with H, Be, Mg, Tl, Ce,
Nd, Pb, Th, Nb, Rh, Ba, Sr, La, and Ca. It also includes but is not restricted to
mordenite modified by vapour deposition techniques employing compounds such as metal
chlorides.
[0016] The second family of tectosilicate catalysts are those which selectively dewax relatively
light lubricating oils such as an HVI 80 to 100 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, ZSM-38, ZSM-21 and natural ferrierite,
treated or untreated, with or without the presence of catalytic metals thereon.
[0017] 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.
[0018] 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 interaction, provide an unexpectedly more
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 dimensions 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 lubricating oils.
[0019] 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/l 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 velocity (LHSV) preferably will be from
0.1 to 10 and more preferably between 0.5 and 5.0.
[0020] The raw lubricating oils contemplated herein to be treated in parallel flow generally
contain in the range of from 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 ASTM 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 hydrocarbons existent in the lubricating base oil precursor
because it has been discovered that the type 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 indigenous to the HVI 250 to 300, HVI 500 to 600 or Bright
Stock waxy raffinates. In fact, it comes 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 structures 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.
[0021] It is believed that the waxy materials present in HVI 80 to 100 or 80 to 150 lubricating
oil have an average carbon number of 23 although the individual constituents of this
stream are known to encompass a range of hydrocarbon components including minute 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 known to encompass a range of hydrocarbon components which include quantities
of hydrocarbons with 22 carbon atoms to 52 carbon atoms. 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 components. This 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 components
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.
[0022] The complimentary independent parallel flow simultaneous interaction of the two catalysts
for dewaxing, one with pore dimensions similar to ferrierite and the other with pore
dimensions similar or larger than ZSM-5 will result in a reduction in the design size
of particular dewaxing reactors, although more 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 greatly 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
may continue to function unimpeded. 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.
[0023] 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 reactivation of the catalyst. This hydrogen reactivation
is performed in the presence of a hydrogen-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 perform their respective catalytic function until they
too become spent and thereby necessitate reactivation.
[0024] An 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 mixtures
of oxygen with any other inert gas such as nitrogen or argon.
[0025] 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. However, 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 downstream of the overall catalytic
dewaxing process, established techniques, including clay 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 prepare any type of lubricating base oil or industrial
oil, such as an automotive engine oil, transformer oil, compressor oil, railroad oil,
refrigerator oil, hydraulic oil, gear oil, or any other lubricant necessitating specific
qualities of pour point at a certain temperature.
[0026] The invention also relates to catalytically dewaxed lubricating base oils whenever
prepared by a process as described hereinbefore.
[0027] In the Figure a flow scheme is depicted which is exemplary 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.
[0028] The instant flow scheme is given without regard to miscellaneous auxilliary equipment
necessary to perform the process flow such as various pumps, condensors, receivers
and so forth. The 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 1 is
charged to fractionation column 3 wherein a light product stream is withdrawn through
conduit 5, either overhead or as a sidecut stream or both, and is removed from the
process and passed along for further processing to recover other hydrocarbon minerals.
The bottoms stream from fractionation column 3 is withdrawn through conduit 7 and
passed to vacuum distillation 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 11 having an initial boiling point
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 distillation unit
as sidecut streams HVI 80 to 100 or 80 to 150, HVI 250 to 300 and HVI 500 to 600 raw
undewaxed distillates containing waxy material which result in a pour point of such
a magnitude to vitiate target projection of the open lubricating oil marketplace.
An HVI 80 to 100 or 80 to 150 distillate stream is withdrawn via conduit 13, an HVI
250 to 300 distillate stream is withdrawn via conduit 15 and an HVI 500 to 600 distillate
stream is withdrawn via conduit 17. A fifth stream, withdrawn from 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 nomenclated as (DAO) also has indigenous undesirable waxy
material which raises the pour point of the lubricating oil to a degree to render
same unsuitable for most commercial use.
[0029] It is optional in this invention to utilize a preliminary solvent extraction system
to treat the waxy lubricating oil distillates. The solvent is any conventional extraction
solvent 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 contaminant stream is withdrawn containing
extracted aromatics, nitrogen and sulphur compounds 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). This is also true for a portion
or the entirety of streams 51, 53, 55 and 57. It is important to note that this solvent
extraction system can be performed 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 from the vacuum distillation column 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
59, 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 useful for treating a multitude of streams. It is also contemplated
that the hydrotreating be performed before the solvent extraction. Either way, the
pre-dewaxing hydrotreating zone is purely optional and its presence or placement does
not form an integral process parameter of the instant flow scheme contemplating the
dual bed parallel passage flow of lubricating base oil precursors to different hydrodewaxing
catalysts.
[0030] The function of the hydrotreater is to excise additional aromatic compounds, sulphur
compounds, nitrogen compounds and convert complex aromatic compounds to simpler aromatic
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 concomitant 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 hydrotreatment step is optional, and need not be performed
to accomplish the goals of this invention. The solvent extracted, or if desired, hydrotreated
effluent streams, are withdrawn from respective (or one single hydrotreater operating
in blocked out mode) from hydrotreaters 59, 61, 63 and 65 through conduits 75, 77,
79 and 81. They are passed directly to the respective appropriate catalytic dewaxing
steps 83, 85, 87 and 89, which are provided with hydrogen entry ports 91, 93, 95 and
97. The respective dewaxed lube oils are withdrawn from 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.
[0031] After production of these streams hydrotreating is normally undertaken to further
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 with other feed streams. Rendering this expensive
and potentially troublesome extra process step superfluous surprisingly produces an
overall process 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 within the scope of this invention
although, to do so 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 dewaxing.
[0032] Another embodiment of this invention comprises the passage of the DAO stream directly
from deasphalting unit 21 to hydrotreater 65 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 over 260 °C. Hydrotreated effluent
is passed via conduit 81 to catalytic dewaxing unit 89 for aforementioned treatment.
[0033] It is also optional in this invention to utilize a preliminary solvent dewaxing system
to treat the waxy lubricating oil raffinates, especially those requiring very low
pour points, for example below -18 °C. The solvent is any conventional dewaxing solvent
such as propane, or alkyl ketones in admixture with an aromatic component, i.e. methylethyl
ketone and toluene. These streams may be added in a batch processing manner. The solvent
may be recovered by distillation 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 from the vacuum distillation column.
[0034] The preferred catalyst in hydrogen dewaxing unit 83 is one with a pore size similar
to the pore size of synthetic ferrierite. The 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.
The latter can also be used in hydrogen dewaxing units 85 and 87 with or without accompaniment
of a smaller pore zeolite. Again, the use of the preferred ferrierite-containing catalyst
obviates post-dewaxing hydrotreatment.
[0035] The process conditions present in the fractionation column 3 or 9, deasphalting unit
21, solvent extraction units 27, 29, 31, 33 and the hydrotreating units 59, 69, 71
and 73 are well known to those of reasonable skill in the art. Hydrotreating conditions
and applicable catalysts for hydrotreating streams 101, 103, 105 or same if combined
with stream 99, are likewise well-recognized. 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 feed material is selected
for the particular catalytic composition of matter of respective units 83, 85, 87
and 89.
1. 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.
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 l(S.T.P.) H₂/l oil feed.
4. A process according to any one of the preceding claims wherein the first wax contains
less than 55% by weight of branched and cyclic hydrocarbons and wherein the second
wax contains more than 55% by weight of branched and cyclic hydrocarbons.
5. A process according to any one of the preceding claims 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.
6. A process according to claim 5 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.
7. A process according to any one of the preceding claims 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 ± 0.2 M2/nO : Al₂O₃ : 5-100 SiO₂ : 0-40 H₂O
wherein M is a cation and n is the valence of said cation.
8. A process according to any one of the preceding claims which comprises at least
three, and preferably four or more parallel-situated catalytic hydrodewaxing zones.
9. A process according to any one of the preceding claims 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.
10. A process according to claim 9 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.
11. A process according to any one of the preceding claims wherein at least two dewaxed
lubricating base oils are blended to formulate at least one lubricating oil product.
12. A process substantially as described hereinbefore with particular reference to
the Figure.
13. Catalytically dewaxed lubricating base oils whenever prepared by a process according
to any one of the preceding claims.