Note: Descriptions are shown in the official language in which they were submitted.
~2~323~3
I
K 7551
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
-- 2 -
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
-- 2 --
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
, , ' ~ ' ` ,, ' ' ', .
-
363
- 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
-- 4 --
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
-- 5 --
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
-- 6 --
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
.
.
363
-- 8 --
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
-- 10 --
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
- 12 --
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
- 13 -
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
- 14 -
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.
3X363
- 15 -
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.
