Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO9610rl~5 2 t ~ g 2 t ~ PCT/USg5/11036
~ 1
HYDROlC~ hKI~A~ION PROCESS
CROSS-P~T'~NCE TO RT'TA~ED APPLICATIONS
This application i8 related to co-pending application
Serial No. 08/01i,949 (continuation of S.N. 07/548,702)
entitled Production of High Viscosity Index Lubricants,
which describes a two-step process for producing high
Viscosity Index lubricants by hydrocracking and
hydroisomerization of petroleum-wax feeds using a low
acidity zeolite beta hydroisomerization catalyst. Serial
No. 08/017,955, also entitled Production of High Viscosity
Index Lubricants, describes a wax hydroisomerization
process using zeolite catalysts of controlled low acidity
at high pressures. The instant application is a
continuation-in-part of Serial No. 08/017,955. The instant
application is also a continuation-in-part of Serial No.
08/017,949. Serial No. 08/017,955 is incorporated by
reference in the instant application. CoLL~ ollrl;ng
European Patent No. 464,547Al, (a patent which specifies
the use of low acidity zeolite beta for wax isomerization)
is also incoL~L~ted by reference.
FITTn OF T~E TNV~NTION
This invention relates to the production of high
Viscosity Index lubricants by employing a process in which
two dewaxing catalysts operate synergistically. The feed
may be hyd.u~L-cked prior to the catalytic dewaxing
process. The effluent of the dew~YlnrJ process may also be
11YdL ~ LL ~ated.
1INI, OF ~R~ INV~NTION~
Mineral oil based lubricants are conventionally
p~uduced by a separative sequence carried out in the
petroleum refinery which comprises fractionation of a
paraffinic crude oil under ai ~ ric pressure followed by
fractionation under vacuum to produce distillate fractions
(neutral oils) and a residual fraction which, after
W096~7715 2 ~ 982 ~ 3 - PC~US9~11036
.
~P~ph~lting and severe solvent ~L_ai L may also be used
as a lubricant basestock. This refined residual fraction
i8 usually referred to as bright stock. Neutral oils,
after solvent extraction to remove low viscosity index
IV.I.) ~ntS, are conventionally subjected to
do _Ying~ either by solvent or catalytic ~ - ng
p-~e~ses, to achieve the desired pour~point. The dewaxed
lube stock may be hydrofinished to improve stability and
remove color bodies. Viscosity Index (V.I.) is a
reflection of the amount of viscosity decrease a lubricant
undergoes with an increase in temperature. The products of
solvent dewaxing are dewaxed lube oil and slack wax. Slack
wax typically contains 60% to 90% wax with the balance
being entrained oil. In some instances it is desirable to
purify the slack wax of entrained oil by subjecting the
slack wax to a deoiling step in which the slack wax is
dlluted with dewaxing solvents and filtered at a
t a~uL~ higher than that used in the filtering step
used to produce the slack wax. The purified wax is termed
deoiled wax, and contains greater than ~5% wax. The
byproduct of the second filtration typically contains 50%
wax and is termed foots oil.
Catalytic ~ Ying of lube stocks is a~ hP~ by
converting waxy molecules to light products by cracking, or
by isomerizing waxy molecules to form species which remain
in the dewaxed lube. Dewaxing catalysts ~ese,v~ high
yield primarily by having pore structures which inhibit
cracking of~cyclic and highly branched species, those
generally associated with dewaxed lube, while permitting
easier access to catalytically active sites to near-linear
molecules, of which wax is generally ~ * e~.~'. Cataiysts
which significantly reduce the acces6ibility of species on
the basis of molecular size are termed shape selective.
Increasing the shape selectivity of a dewaxing catalyst
will frequently increase the yield of dewaxed oil.
The shape selectivity of a dewaxing catalyst is
limited practically by its ability to convert waxy
molecules which have a slightly branched structure. These
.
21~'2~
WO96/07715 1'CTIUS95/11036
-3-
types of species are more commonly associated with hoavier
lube stocks, such as bright stocks. Highly shape selective
dewaxing catalysts may be unable to convert heavy, branched
wax species leadlng to a hazy lube appearance at ambient
temperature and high cloud point relative to pour point.
~ Conventional lube refining te~hn~ c rely upon the
proper 6election and use of crude stocks, usually of a
paraffinlc character, which produce lube fractions with
desired quallties ln adequate amounts. The range of
p~r~icFihle crude sources may, however, be extended by the
lube hydLoe-~cking process which is capable of utilizing
crude stocks of marginal or poor quality, usually with a
higher aromatic content than the best paraffinic crudes.
The lube hydrocracking process, which is well established
in the petroleum refining industry, generally comprises an
initial l,~lLue~cking step carried out under high pressure,
at high temperature, and in the presence of a bifunctional
catalyst which effects partial saturation and ring opening
of the aromatic ~ ~ which are present in the feed.
The L~lLv~L~cked product is then subjected to dewaxing in
order to reach the target pour point since the hydLvvL~cked
product usually contains species with relatively high pour
points. Fr~uell~ly the liquid product from the dewaxing
step is subjected to a low temperature, high ~esDuLe
I.ydLvLLeating step to reduce the aromatic content of the
lube to the desired level.
Current trends in the design of automotive engines are
associated with higher operating t~ ~LuLe8 as the
efficiency of the engines increases. These higher
operating t~ UL~C require successively higher quality
lubricants. One of the requirements is for higher
visco6ity indices (V.I.) in order to reduce the effects of
the higher operating t~ ~tules on the viscosity of the
engine lubricants. High V.I. values have conventionally
been attained by the use of V.I. ; _~ve~ e.g.
polyacrylates and poly~yLe..es. V.I. improvers tend to
undergo de~dation due to high t~ LuLes and high shear
rates encountered in the engine. The more stressing
2 1 9~2 1-3
Wo96~M15 PCT~S95/11036
conditions encountered in high~efficiency engines result in
~ven faster deyLadaLion of oils which employ significant
amounts of V.I. improvers. Thus, there is a continuing
need for automotive lubricants which are based on fluids of
high Viscosity Index and which are resistant to the high
t~ ~tUL~, high shear rate conditions encountered in
modern engines.
6ynthetic lubricants ~L~duced by the polymerization of
olefins in the presence of certain catalysts have been
shown to possess excellent V.I.~values, but they are
relatively expensive to produce. There is therefore a need
for the production of high V.I. lubricants from minerai oil
stocks which may be ~l~duced by techniques comparable to
those presently employed in petroleum refineries.
U.S. Patent No. 4,975,177 discloses a tw0-3tage
d- ~-ng process for producing lube stocks of high V.I.
from waxy feedstocks. In the first stage of this process,
the waxy feed is catalytically dewaxed by isome=rization
over zeolite beta. The product of the isomerization step
still contains waxy species and requires further d Y;ng
to meet target pour point. The second-stage ~ ~qYi ng;
employs either solvent dewqY;n~, in which case the rejected
wax may be recycled to the isomerization stage to r-Y;~mi 7e
yield, or catalytic d - Ying. Catalysts which may be used
in the second stage are ZSM-5, ZSN-22, ZSM-23, and ZSM-35.
To pL~se1v~ yield and V.I., the second stage d - ng
catalyst should have selectivity similar to solvent
d~ Y;ng. U.S. Patent 4,919,788 also teaches a two-stage
dewaxing process in which a waxy feed is partially dewaxed
by isomerization over a 5;1 iceon~ Y or beta catalyst with
the product ~hse~ ly dewaxed to desired pour point
using either solvent dewaxing or catalytic ~ ;ng.
Dewaxing catalysts with high shape selectivity, such as
ZSM-22 and ZSM-23, are preferred catalysts. These
examples, however, do not teach synergi3tic effects
involving more than one dewaxing catalyst.
Serial No. 08/017,949 d;~cln5~ a two stage
~yd~ cking and hydroisomerlzation proc s. The first
Wos6~7715 2 ~ PCT~S9~1103
-5-
stage employs a bih-n~t~onAl catalyst comprising a metal
hydLuu~d~lon L on an amorphous acidic support.
The second stage, the hydroisomerization step, is carried
out over zeolite beta. Snh~e~lrnt dewaxing is optional but
L~ '-'. Either solvent dewaxing or catalytic dewaxing
maybe used sulsr~ ly in order to obtain target V.I. and
pour point. There is no tearh; ng of catalytic synergism in
this invention.
In S.N. 08/017,955, petroleum wax feed i5 subjected to
hydroisomerization over a noble metal-containing zeolite
catalyst of low acidity. The paraffins present in the feed
are selectively converted to iso-paraffins of high V.I. but
lower pour point so that a final lube product of good
V i ~ L iC properties is produced with a minimal degree of
15 5nh~1rnt fl nq. The process, which operates under
high pL~ UL~, is well suited for upgrading waxy feeds such
as slack wax with aromatic contents greater than 15 wt.% to
high Viscosity Index lubricating oils with high single pass
yields and limited requirement for product flrWA~i ng .
Related cases primarily emphasize solvent d~ i ng
with Catalytic dewaxing as a posgible alternative or
E~onnflAry step. The advantage of solvent dewaxing the
product of the isomerization stage in that wax is rejected
and can be recycled to the isomerization catalyst to
improve the yield of high V.I. lube. However, operational
costs for solvent dewaxing are higher than for catalytic
dewaxing. Additionally, the pour point of the solvent
dewaxed lube stock is restricted by solvent refrigeration
capability to approximately -21 to -18-C. Catalytic
30 ' .. _ ' ng enables production of high V.I. lubes having pour
points significantly lower than those possihlr for solvent
dewaxing. An unexpected devrl~ L of the total catalytic
dewaxing process is that it can produce lubricants with
equivalent or higher V.I. at equivalent or lower pour
points than lubricants ~Lu~uced by solvent ~r~: ~ing.
WO96~7715 2 1 9 8 2 t 3 ~ PCT~S95/11036
-6-
8nMMARY OF T~ INVENTION
The instant application involves the proco~sing of a
waxy hydrocarbon feedstock using an integrated catalyst
~ystem for the production of high Viscosity Index (V.I.)
low aromatic content lubricant stocks with low pour point.
The feedstock is initially contacted under high plesOu-
~(hydr ~tg~n partial p~SoUL~ of at least 5617 kPa~ with low
acidity large pore zeolite catalyst into which a metal,
preferably a noble metal such as Pt, has been incorporated.
A substantial fraction of the waxy material in the feed is
selectively isomerized over this catalyst. The reaction
product is subsequently contacted with a constrained
intermediate pore crystalline material, also containing a
noble metal, which provides further isomerization and
dewaxing. The final product is a lubricant which has a
high Viscosity Index and a low pour point. A snhso~lont
~ydl~L~ating step may be included to reduce lube oil
aromatic content to the desired target point.
The catalysts used in the instant invention behave
synergistically. The yield and Viscosity Index (V.I.) of
the product of the integrated catalyst system excced the
yield and V.I. of the product from either of the two
catalysts operating alone. This synergism requires the
reactor containing the large pore zeolite to be operated so
as to convert 40 to 90~ of the wax species in the feed.
The conversion of the residual wax is AC ~ hotl in the
second d~ ; ng step. Both V.I. and yield are inversely
related to pour point below a pour point of approximately
27-C. The synergy of the process is illustrated by the
reduction in yield and V.I. with decreasing pour point
being ~igniflcAntly less than for either ~Au~ing catalyst
operating alone. The 1 ~v. ~ of yield and V.I. is not
predictable by the study of each catalyst individually.
Additionally, product appearance and cloud point are
1 _~v~d by the t~ age dewaxing system over those from
the selective dewaxing catalyst operating alone.
The proceOs of the instant invention can be used to
upgrade feeds having low wax content, such as those
.
.
WO96107715 2 1 ~ 8 2 t ~ j PCT~11~6
_ -7-
obtained by solvent extracting or l.yd~L~cking vacuum
distillates. ~owever, the synergy i8 most evident with
feedstocks which have a wax content of over 50~.
The synergy of the integrated low-acidity large pore
zeolite catalyst and the into ~ te pore catalyst permits
~ the pro~n~tion of high quality base stocks by an all-
catalytic route. Such base stocks generally have a
Viscosity Index greater than 120, more preferably greater
than 130, and contain less than 10% aromatics, more
preferably less than 1% aromatics.
CRIPTION OF ~ DRAWINGS
Figures 1, 2, 3 and 4 are plots which illustrate the
synergistic relationship of the catalysts of this
invention. Viscosity Indexes and yields obtained by using
the catalysts together and individually are plotted against
pour point. The figures are ~ ccllcced in more detail in
the Examples, infra.
nF:TATT.~n DEsQl?lpTIQ~
In the present process, ~eeds with a relatively high
wax content, such as slack wax, are converted to high V.I.
lubricants in an integrated process employing two catalysts
with synergistic properties. A hydroisomerization process
using a noble metal containing low acidity zeolite
hydroi- ization catalyst is employed first. The
int~ te product of this process is then contacted with
a noble metal containing int~ te pore crystalline
material to accomplish further del~Y;ng. Product V.I. will
vary with pour point, wax content of the feed, and whether
the feed was subjected to a pretreatment step. For heavy
neutral slack waxes which have been hydrorefined to remove
nitrogen and sulfur containing species, product VI is
typically at least 140 at -18-C pour point and usually in
the range 143 to 147. The production of base stocks with
V.I. greater than that obtained from the synergistic
catalyst system is not possible with either catalyst
operating alone to effect complete d~ _ ' ng.
-
Wo96/07715 2 ~ 9 ~ ~ 1 3 PCT~S95111036
-8-
~ The present plocebses are capable of operating with a
wide range of feeds of mineral oil origin to produce a
range of lubricant ~Ludu~LL with good performance
characteristics. Such characteristics include low pour
point, low cloud point, and high Viscosity Index. The
quality of the product and the yield in which it is
obtained i8 dep~n~nt upon the quality of the feed and its
amenability to processing by the catalysts of the instant
invention. Produsts of the highest V.I. are obtained by
using preferred wax feeds such as slack wax, foots oil,
deoiled wax or vacuum distillates derived from waxy crudes.
Waxes produced by Fischer-~Lu~us~1- processing of synthesis
gas may also be used as feedstocks. Products with lower
V.I. values may also be obtained ~rom other feeds which
contain a lower initial qyantity of waxy ~_ - ~ntS.
The feeds which may be used should have an initial
boiling point which is no lower than the initial boiling
point of the desired lubricant. A typical initial boiling
point of the feed exceeds 345 C. Feeds of this type which
~may be used include vacuum gas oils as well as other high
boiling fractions such as distillates from the vacuum
distillation of a' ~'~ric resids, raffinates from the
solvent extraction of such distillate fractions,
hydLu~L~cked vacuum distillates and waxes from the solvent
~ ng of raffinates and hydLu~L~ckates.
The feed may require preparation in order to be
treated satisfactorily in the hydroisomerization step. The
preparation steps which are generally ~c~cc~ry are those
which remove low V.I. ~ L~ such as aromatics and~
polycyclic naphthenes. Removal of these materials will
result in a feed for the hydroisomerization step which
contains higher quantities of waxy paraffins which are then
converted to high V.I., low pour point iso-paraffins.
Catalytic synergy is most dramatically illustrated for
feedstocks having a wax content of over 50~, although feeds
with lower wax contents may be used effectively.
,
'
wos6l077ls 2 ~ 3 ~ ~ PCT~Sg~11~6
~ g
Suitable pre-LL~ai L steps for preparing feed~ for
the hydrni r ization are those which remove the aromatics
and other low V.I. ~ Ls from the initial feed.
HYdLU~L~a1 ~ is an effective pL~LLeai L step,
particularly at high hydrogen pLes ULeS which are effective
- for ~romatics saturation e.g. 5617 kPa~ or higher. ~ild
hydrocracking may also be employed as pretreatment and is
preferred in the instant invention, if p.~LL~ai L is
required. Example 3, infra, ~ircl-csP~ the hydLù~Lacking
conditions employed in the instant invention in order to
prepare a feed for the dewaxing process. Pressures over
6996 kPa,~ are preferred for l,ydLu~Lacking treatment.
~ydrocracking removes nitrogen containing and sulfur-
containing species and reduces aromatics content as Table 6
below illustrates. Hydrocracking, in this example, has
also slightly altered the boiling range of the feed,
causing it to boil in a lower range. Commercially
available catalysts such as fluoride nickel-tungsten on
alumina (NiWF/Al20,) may be employed for the hydrocracking
pretreatment.
The preferred gas oil and vacuum distillate feeds are
those which have a high wax content, as determined by ASTM
D-3235, preferably over 50 weight percent. Feeds of this
type include certain South-East Asian and r-inl~n~ China
oils. Minas Gas Oil, from Tn~nPriA, is such a feed.
These feeds usually have a high paraffin content, as
det~rm;nP~ by a conventional analysis for paraffins,
naphthenes, and aromatics. The properties of typical feeds
of this type are set out in S.N. 07/017,955.
As stated previously, the wax content of the preferred
feeds is high, generally at least 50 wt% (as detprm;npd by
ASTM Test D-3235) prior to pretreatment. The wax content
before ~L~LL~al - L is more usually at least 60 to 80
weight percent with the balance being occluded oil
comprising iso-paraffins, aromatics and naphthenics. These
waxy, highly paraffinic wax stocks usually have low
viscosities because of their relatively low content of
aromatics and naphthenes although the high content of waxy
W096~7715 2 1 9 8 ~ 1 3 rcT~S95111036
. ~ ,
- -lo-
par~f~ins gives them melting points and pour points which
render them unacceptable as lubricants without further
proc~CC;ng. Wax feeds are A;ccllcc~d further in S.N.
07/017,955.
The most preferred type of wax feeds are the slack
waxes, (see Table 2, infra). These are the waxy ~1UdU~L
obtained directly from a solvent dewaxing process, e.g. an
MEK or propane dewaxing process. The slack wax, which is a
solid to semi-solid product, comprising primarily highly
waxy paraffins (mostly n- and mono-methyl paraffins)
together with occluded oil, may be used as such or it may
be subjected to an initial ~oil ing step of a conventional
character in order to remove the occluded oil.~ Removal of
the oil results in a harder, more highly paraffinic wax
which may then be used as the ~eed. The byproduct of the
A~oi 1 i ng step is termed foots oil and may also be used as
feed to the process. The Foots Oil contains most of the
aromatics present in the original slack wax and with these
aromatics, most of the heteroatoms. Slack wax and foots
oil typically require ~L~L~a~lent prior to catalytic
~t Ying. The oil content of deoiled waxes may be quite
low and for this purpose, mea~u~ ~ of the oil content by
the t~hni ~1~ of AST~ D721 may be required for
l_~Luducibility, since the D-3235 test referred to above
tends to be less reliable at oil contents below 15 weight
percent. At oil contents below 10 percent, however, the
advantage of the present catalysts may not be as marked as
with oil contents of from 10 to 50 weight percent and for
this reason, wax feeds conforming to this requirement will
normally be employed.
The compositions of some typical waxes are given in
Table 1 below.
'~ :
.
W096~77l5 2 1 9 8 2 t ~ PCT~S9YIl036
--11--
" Table 1
"9~ C9mposition - A~ab Liqht Crude
A B C
Paraffins, wt. pct. 94.2 81.8 70.551.4
Mono-naphthenes, wt. pct. 2.6 11.0 6.316.5
Poly-naphthenes, wt. pct. 2.2 3.2 7.9 9.9
Aromatics, wt. pct. 1.0 4.0 15.322.2
A typical slack wax feed has the composition shown in
Table 2 below. This slack wax is obtained from the solvent
('.~EK) dewaxing of 65 cSt at 40 C neutral oil obtained from
an Arab Light crude.
WO9610771S 2 1 9 8 ~ 1 3 PCT~S9S/11036
'
- 2- =
= Table 2
Slar~ WaY P~o~erties
API 39
Hydrogen, wt. pct. 15.14
Sulfur, wt. pct. 0.18
Nitrogen, ppmw 11
~elting point, ~C 57
KV at lOO-C, cSt 5.168
PNA, wt pct:
Paraffins 70.3
Naphthenes 13.6
Aromatics 16.3
Simulated Distillation:
~: C = ~
375
10 413
30 440
50 460
70 482
500
95 507
Another slack wax suitable for use in the present
proceSs has the properties set out in Table 6 infra as part
of Example 3. This wax is prepared by the solvent ~ew IYi ng
of a heavy neutral furfural raffinate. As discussed
previously, llydLu~cking may be employed to prepare the
slack wax for hydroisomerization.
Hvflrocrar~;na Proce8s (O~tiûnal~
If hydLo~L~cking is employed as a pretreatment step an
amorphous bifunctional catalyst i5 preferably used to
promote the saturation and ring opening of the low quality
aromatic ~ ~ Ls in the feed to produce hydLuuL~cked
pludu~Ls which are relatively more paraffinic.
Hydrocracking i5 carried out under high pressure to favor
aromatics saturation but the boiling range conversion is
maintained at a relatively low level in order to minimize
cracking of the saturated components of the feed and of the
pIudu~Ls obtained from the saturation and ring opening of
the aromatic materials. Consistent with these process
objectives, the hydlug~ L~5~UL~ in the hydLuuL~cking
W096107715 2 1 ~ PCT/USgSJII036
~ --13--
~tage i8 at least 5617 kPa.~ and usually is in the range of
6696 to 20786 kPa~. Normally, hydrogen partial p~=s~u~e5
of at least 10444 kPa~ are best in order to obtain a high
level of aromatic saturation. Hydrogen circulation rates
of at least 180 n.l.l , preferably in the range of 900 to
1800 n.l.l' are suitable.
In the hydLv~acking process, the conversion of the
feed to products boiling below the lube boiling range,
typically to 345'C- products is limited to no more than 50
weight percent of the feed and will usually be not more
than 30 weight percent of the feed in order to maintain the
desired high single pass yields which are characteristic of
the process. The actual conversion is dependent on the
quality of the feed with slack wax feeds requiring a lower
conversion than petrolatum where it is np~c~lry to remove
more low quality polycyclic ~nts. For slack wax
feeds derived from the dewaxing of neutral stocks, the
conversion to 345-C- products will, for all practical
purposes not be greater than 10 to 20 weight percent, with
5-15 weight percent being typical for most slack waxes.
Higher conversions may be encountered with petrolatum feeds
because they typically contain more low quality ~ ---nts.
With petrolatum feeds, the hydrocracking conversion will
typically be in the range of 15 to 25 weight percent to
produce high VI products. ~he conversion may be maintained
at the desired value by control of the temperature in the
hyd~ cking stage which will normally be in the range
315' to 430-C and more usually in the range of 345- to
400-C). Space velocity variations may also be used to
control severity although this will be less common in
practice in view of mechanical constraints on the system.
Generally, the space velocity will be in the range of 0.25
to 2 LHSV, hr. and usually in the range of 0.5 to 1.5
LHSV.
A characteristic feature of the hydl~Lacking operation
is the use of a bifunctional catalyst. In general terms,
these catalysts include a metal ---nt for promoting the
desired aromatics saturation reactions and usually a
_ _ _ _ _ , . , . , .. _ _ _
W096/07715 2 1 q 8 2 PCT~S95/11036
combination of base metals i5 used, with one metal from the
iron group tGroup VIII) in combination with a metal of
Group VIB. Thus, the base metal such as nickel or cobalt
i5 used in combination with molybdenum or tungsten. The
preferred combination i6 nickel/tungsten since it has been
found to be highly effective for promoting the desired
aromatics i-yd~L~cking reaction. Noble metals such as
platinum or palladium may be used since they have good
l~ydL~yellation activity in the absence of sulfur but they
will normally not be preferred. The amounts of the metals
present on the catalyst are conventional for lube
hydrocracking catalysts o~ this type and generally will
range from l to l0 weight percent of the Group VIII metal
and l0 to 30 weigh~ percent of the Group VI metal, based on
the totàl weight of the catalyst. If~a noble metal
~nt such as platinum or palladium is used instead of
a base metal such as nickel or cobalt, relatively lower
amounts are in order in view of the higher hydrogenation
activities of these noble metals, typically from 0.5 to 5
weight percent being sufficient. The metals may be
in~oL~La~ed by any suitable method including ; ~--ation
onto the porous support after it is formed into particles
of the desired size or by addition to a gel of the support
materials prior to calcination. Addition to the gel is a
preferred technigue when relatively high amounts of the
metal ~ ~5 are to be added e.g. above l0 weight
percent of the Group VIII metal and above 20 weight percent
of the Group VI metal. These techniques are conventional
in character and are employed for the production of lube
hydLo~L~cking catalysts.
The metal c -~t of the catalyst is generally
supported on a poroùs, amorphous metal oxide support and
alumina is preferred for this purpose although silica-
alumina may also be employed. Other metal oxide - ~nts
may also be present in the support although their presence
is less desirable. Consistent with the requirements of a
lube hydL~L _king catalyst, the support should have a pore
size and distribution which is adequate to permit the
2 1 9~2 1 3
WO96107715 P~/US9~11036
--lS--
relatively bulky r - of the high boiling feeds to
enter the interior pore sLLu~Lur~ of the catalyst where the
desired l-ydLv~L~cking reactions occur. To this extent, the
catalyst will normally have a minimum pore size of 50 A i . e
with no less than 5 percent of the pores having a pore size
less than 50 A pore size, with the majority of the pores
having a pore size in the range of 50-400 A (no more than 5
percent having a pore size above 400 A), preferably with no
more than 30 percent having pore sizes in the range of 200-
400 A. Preferred catalysts for the first stage have atleast 60 percent of the pores in the 50-200 A range. The
pore size distribution and other properties of some typical
lube hydLu~L~cking (LHDC) catalysts suitable for use in the
l.ydLuv.~cking are shown in Table 3 below:
Table 3
T.~nr Ca~Alvst Pro~erties
Form 1.5mm cyl. 1.5 mm. tri. 1.5 mm.cyl.
Pore Volume, cc~gm0.331 0.453 0.426
Surface Area, m /gm 131 170 116
Nickel, wt. pct. 4.8 4.6 5.6
Tungsten, wt. pct. 22.3 23.8 17.25
Fluorine, wt. pct. - - 3.35
siO~Al,0, binder - - 62.3
Real Density, gm/cc4.229 4.238 4.023
Particle Density, gm/cc 1.744 1.451 1.483
Packing Density, gm/cc1.2 0.85 0.94
If n~c~aaAry in order to obtain the desired conversion,
the catalyst may be promoted with fluorine, either by
inaor~vLating fluorine into the catalyst during its
preparation or by operating the hydLvu~cking in the
pL6e_nce of a fluorine _ __ ' which is added to the feed.
Fluorine c~n~in;ng ' may be incoL~uL~Led into the
catalyst by i -sy-.ation during its preparation with a
suitable fluorine r __ -' such as ill~ fluoride (NH4F)
or ammonium bifluoride (NH4F-HF~ of which the latter is
preferred. The amount of fluorine used in catalysts which
contain this element is preferably from 1 to 10 weight
percent, based on the total weight of the catalyst, usually
from 2 to 6 weight percent. The fluorine may be
SUBSTITUTE St1EET (RULE 26)
WO96/07715 2 ~ PCT~S95111036
-i6- ;
incu, uu~ ated by adding the fluorine , _ ' to a gel of
the metal oxide support during the preparation of the
catalyst or by im.pregnation after the particles of the
catalyst have been formed by drying or ~Alcining the gel.
If the catalyst contains a relatively high amount of
fluorlne as well as high amounts of the metals, as noted
above, it is preferred to in~u~uLate the metals and the
fluorine , JUlid lnto the metal oxide gel prior to drying
and calcining the gel to form the finished catalyst
particles.
The catalyst activity may also be maintained at the
desired level by Ln situ fluoriding in which a fluorine
compound is added to the stream which passes over the
catalyst in this stage of the operation. The fluorine
~ ' may be added continuously or intermittently to the
feed or, alternatively, an initial activation step may be
carried out in which the fluorine ' is passed over
the catalyst in the absence of the feed e.g. in a stream of
hydLuy~ in order to increase the fluorine content of the
catalyst prior to initiation of the actual hyd~u~acking.
situ fluoriding of the catalyst in this way is
preferably carried out to induce a fluorine content of l to
lO percent fluorine prior to operation, after which the
fluorine can be reduced to maintenance levels sufficlent to
maintain the desired activity. Suitable c -c for ir
9i~g fluoriding are orthofluorotoluene and difluoroethane.
The metals p~resent on the catalyst are preferably used
in their sulfide form and to this purpose pre-sulfiding of
the catalyst should be carried out prior to initiation of
the 1-yd-uu.acking. Sulfiding is an established ti-i~hni~li~
and it is typically carried out by contàcting the catalyst
with a sulfur-c~ntAining gas, usualiy in~the p~sence of
hyd-uge-l. The mixture of 11y~Luy~n and 1~yd~uyel~ sulfide,
carbon c.isulfide or a ~a~all such as bùtol mercaptan is
conventional for this purpose. Presulfiding may also be
carried out by contacting the catalyst with hydLuy~1 and a
sulfuL--ull~aining hydrocarbon oil such as a sour kerosene
or gas oil.
SU~STITUTE Sll.'ET (RULE 26)
~ , . .
WO9~07715 2 1 ~ 8 2 1 3 PCT~S95/11~36
-17-
Svner~istic Catnlvst Process
The paraf~inic c _ present in the original wax
feed possess good V.I. characteristics but have relatively
high pour points as a result of their paraffinic nature.
The objective of the synergistic catalyst process of the
lnvention is, therefore, to effect a selective conversion
Or waxy species while minimi 7ing conversion of more
branched species characteristic of lube components. The
conversion of wax occurs preferentially by isomerization to
form more br~nched species which have lower pour points and
cloud points. Some degree of cracking a~ ~n i ~
isomerization and cracking is re~uired to produce very low
pour point lube oils. The selectivity of the process is
~Yimi 7~ by the use of a two-catalyst system in which the
first catalyst selectively converts waxy species by
isomerization and the second catalyst converts the residual
wax by isomerization and cracking. The pore ~LLu~LuLe of
the first catalyst is significantly less restricted than
that of the second allowing for the conversion of bulky wax
molecules and reducing cloud point and hazy appearance
below that which would be achieved with the use of the
second dewaxing catalyst alone.
Hv~ro; r 7~tion Cat~lvst
The catalyst used in the hydroisomerization step is one
which has a high selectivity for the isomerization of waxy,
linear or near linear paraffins to less waxy, isoparaffinic
products. Catalysts of this type are bifunctional in
character, comprising a metal ~ ~t on a large pore
size, porous support of relatively low acidity. The
acidity is maintained at a low level in order to reduce
conversion to ~- ud~L- boiling outside the lube boiling
range during this stage of the operation. In general
terms, the catalyst should have an alpha value below 30
prior to metals addition, with ~efe,Led values below 20.
(See Example l)
Thê alpha value is an approximate indication of the
catalytic cracking activity of the catalyst compared to a
SUBSTITUTE SHET iRULE 26)
,
_ _ _ _ _ ~ _ _ . . . . . , . _ _ _ _ _ _ _ _
WO96/07715 2 1 ~ ~ 2 ~ 3 PCT~S9~l1036
-18-
~tandard catalyst. The alpha test gives the relative rate
constant (rate of normal hexane converslon per volume Or
catalyst per unit time) of the test catalyst relative to
the standard catalyst which is taken as an alpha of l (Rate
Constant ~ 0.016 sec l). The alpha test is described in
U.S. Patent 3,354,078 and in J. Catalvsis, 4, 527 (1965);
5, 278 (1966); and 61, 395 (1980), to which reference is
made for a description of the test. The experimentai
conditions of the test used to determine the alpha values
referred to in this specification include a constant
temperature of 538-C and a variable flow rate as described
in detail in J. Cat~lysis 61, 395 (1980).
The hydroisomerization catalyst comprises a large pore
zeolite metal. The large pore zeolite is supported by a
porous binder. Large pore zeolites usually have at least
one pore channel consisting of twelve - ~red oxygen
rings. Large pore zeolites usually have at least one pore
channel with a major di -i~n greater than 7A. Zeolites
beta, Y and mordenites are examples of large pore zeolites.
The preferred hydroisomerlzation catalyst~employs
zeolite beta since this zeolite has been shown to pos6ess
outstanding activity for paraffin isomerization in the
presence of aromatics, as disclosed in U.S. 4,419,220. The
low acidity forms of zeolite beta may be obtained by
synthesis of a highly siliceous form of the zeolite e.g
with a silica-alumina ratio above 500:1 or, more readily,
by steaming zeolites of lower silica-alumina ratio to the
requisite acidity level. They may also be obtained by
extraction with acids such as dir~rh~ylic acid, as
disclosed in U.S. Patent No. 5,200,168. U.S. Patent No.
5,164,169 discloses the preparation of highly siliceous
zeolite beta employing a chelating agent such as tertiary
alkenolamines in the synthesis mixture.
The most preferred zeolites are severely steamed and
possess a fL_ ~Lk silica-alumina ratio above 200:1.
Preferably the silica-alumina ratio is above 400:1 and more
preferably the silica-alumina ratio is greater than 600:1.
SU8STtTUTE SHEET (RULE 26)
WO96l0771s 2 1 982 1 3 PCT~s9~/11036
-19-
The steaming conditions should be adjusted in order to
attain the desired alpha value in the final catalyst and
typically utilize ai - ,'~res of 100 percent steam, at
t~ ~I~LULeS of from 427- to 595-C. Normally, the steaming
will be carried out at t~ _ ~LUL~S above 538-C, for 12 to
120 hours, typically 96 hours, in order to obtain the
desired r~dnr~ inn in acidity.
Another method is by r~pl ~r L of a portion of the
r1 ..JLk aluminum of the zeolite with another trivalent
element such as boron which results in a lower intrinsic
level of acid activity in the zeolite. The preferred
zeolites of this type are those which contain framework
boron. Boron is usually added to the zeolite framework
prior to the addition of other metals. In zeolites of this
type, the framework consists prinrir~lly of silicon
tetrahedral coordinated and inteL~ le~Led with oxygen
bridges. The minor amount of an element (alumina in the
case of alumino-silicate zeolite beta) is also coordinated
and forms part of the LL JLk. The zeolite also contains
material in the pores of the ~LLU~LU1~ although these do
not form part of the LL JLh constituting the
characteristic ~LLu~LuL~ of the zeolite. The term
~rL ~Lk~l boron is used here to distinguish between
material in the rL JL~ of the zeolite which is evidenced
by contributing ion ~Yrh~nge capacity to the zeolite, from
material which is present in the pores and which has no
effect on the total ion exchange capacity of the zeolite.
Zeolite beta po~s~c~ a constraint index between 0.60 and
2.0 at t- _ ~LUL_S between 316-C and 399-C although
Constraint Indexes less than 1 are preferred.
Methods for preparing high silica content zeolites
containing rL .L~ boron are known and are described, for
example, in U.S. Patents Nos. 4,269,813. A method for
preparing zeolite beta containing rL JLk boron is
~i~rlos~d in U.S. Patent No. 4,672,049. As noted there,
the amount of boron contained in the zeolite may be varied
by in~uL~uL~Ling different amounts of borate ion in the
zeolite forming solution e.g. by the use of varying amounts
SU8ST~TUTE SHEET (RULE 26)
W096/07715 2 1 982 1 3 PCI/IJS95/11036
--20--
Or boric acid relative to the forces of silica and alumina.
Reference is made to these ~ lo~l~nes for a description of
the methods by which these zeolites may be made.
The low acidity zeolite beta catalyst should contain at
least 0.1 weight percent LL ..~L~ boron, preferably at
least 0.5 weight percent boron. Boron may be added to the
~L. JL~ prior to the addition of other metals. Normally,
the maximum amount of boron will be 5 weight percent of the
zeolite and in most cases not more than 2 weight percent of
the zeolite. The framework will normally include some
alumina. The silica:alumina ratio will usually be at least
30:1, in the conditions of the zeolite as synthesized. A
preferred buLu~ b~Lituted zeolite beta catalyst is made
by steaming an initial boron-containing zeolite containing
at least 1 weight percent boron (as B203) to result in an
ultimate alpha value no greater than 20 and preferably no
greater than 10. -
Pro~erties
Acidity may be reduced by the introduction of
nitrogen '-, e.g. NH, or organic nitrogen ~ '-,
with the feed to the hydroisomerization catalyst. However,
the total nitrogen content of the feed should not exceed
100 ppm and should be preferably less than 20 ppm. me
catalyst may also contain metals which reduce the number of
strong acid sites of the catalyst and improve the
~electivity of isomerization rPA~ti~n~ to cracking
reactions. Netals which are preferred for this purpose are
those belong to the class of Group IIA metals such as
calcium and magnesium.
The zeolite will be composites with a matrix material
to form the finished catalyst and for this purpose
conventional very low-acidity matrix materials such as
alumina, silica-alumina and silica are suitable although
~7n~n~o such as alpha boehmite (alpha alumina - -~ydL~te)
may also be used, provided that they do not confer any
~uL~L~rlLial degree of acidic activity on the matrixed
catalyst. The zeolite is usually composites with the
SUBSTITUTE SHET (PsULE 26~
..
WO96/0771~ t ~ PCT~S9i~11036
-2l-
matrix in amounts from 80:20 to 20:80 by weight, typically
from 80:20 to 50:50 zeolite:matrix. Compositing may be
done by conventional means including mulling the materials
together followed by extrusion into the desired finished
catalyst particles. A preferred method for extruding the
zeolite with silica as a binder is disclosed in U.S.
4,582,815. If the catalyst is to be steamed in order to
achieve the desired low acidity, it is performed after the
catalyst has been formulated with the binder, as is
conventional. The preferred binder for the steamed
catalyst is alumina.
The hydroisomerization catalyst also includes a metal
_, An~ in order to promote the desired
hydroisomerization reactions which, proceP~irj through
unsaturated transitional species, require mediation by a
1-ydLuge.,ation-dehydLugenation ~nPnt. In order to
~-Yim;~e the isomerization activity of the catalyst, metals
having a strong hydLugenation function are preferred and
for this reason, platinum and the other noble metals such
as rhenium, gold, and palladium are given a preference.
The amount of the noble metal hydLogenation -nt is
typically in the range O.l to 5 weight percent of the total
catalyst, usually from O.l to 2 weight percent. The
platinum may be in~uL~uLated into the catalyst by
conventional terhn; Ciupq including ion exchange with complex
platinum cations such as platinum tetraamine or by
impregnation with solutions of soluble platinum
for example, with platinum tetraammine salts such as
platinum tetrAi- ;ne~hlnride. The catalyst may be
subjected to a final calcination under conventional
conditions in order to convert the noble metal to its
reduced form and to confer the required -- An;cAl strength
on the catalyst. Prior to use the catalyst may be
subjected to presulfiding as described above for the
hy~Luc~cking pretreatment catalyst.
SU8SlITlJTE SHEET (RULE 26)
W096/07715 2 1 ~ ~ 2 ~ 3 PCT~S95/11036
-2i-
Hy~roir 7~tion Conditions
The conditions for the hydroisomerization step (also
cnlled the isomerization step) are adjusted to achieve tne
objective of isomerizing the waxy, linear and near-linear
paraffinic - in the waxy feed to less waxy but
high V.I. isoparaffinic materials of relatively lower pour
point. This end is achieved while minimizing conversion to
non-lube boiling range products (usually 345 C- materials).
Since the catalyst used for the hydroisomerization has a
low acidity, conversion to lower boiling products is
usually at a relatively low level;and by appropriate
selection of severity, the operation of the process may be
optimized for isomerization over cracking. At conventional
space velocities of 1, using a Pt/zeolite beta catalyst
with an alpha value below 20, temperatures for the
hydroisomerization will typically be in the range of 300-
to 415-C with conversion to 3is-c- typically being from 5
to 30 weight percent, more usually 10 to 25 weight percent,
of the waxy feed. Approximately 40 to 90 percent of the
wax in the feed is converted in the isomerization step;
However, t~ --aLuL~s may be used outside this range, for
example, as low as 260-C and up to 425-C although the
higher temperatures will usually not be preferred since
they wili be associated with a lower isomerization
selectivity and the production of less stable lube p, uduuLs
as a result of the hydLu~ ation reactions being
~h- :Y~ A11Y less favored at ~uuL_ssively higher
operating t~ ~LUL~S. Space velocities~will typically be
in the range of 0.5 to 2 LHSV (hr. ). The pour point of
the effluent from the hydroisomerization step is in the
range from -1 to 43-C, preferably in the range from 5 to
39-C.
The hydroisomerization is operated at hYdLUU,~II partial
PIe~-IL~S (reactor inlet) of at least 5516 KPa~., usually
5167 to 20786 kP~ and in most cases 5517 to 17339 kPaA~.
H~dLUgeII circulation rates are usually in the range of 90
to 900 n.l.l. . Since some saturation of aromatic
_ Ls present in the original feed takes place in the
..
SU8STITUTE SHET (RUI F 26~
~, ~ . .
W096~7715 2 1 9 8 2 1 3 PcT~s9~11036
-23-
sencê of the noble metal hyd~uy~llation _1~ L on the
catalyst, h~d~uyên i6 ~U.~ ' in the hydroisomerization
even though the desired isomerization reactions are in
hydLuyel- balance; for this reason, hYdLVgén circulation
rates may need to be ad~usted in accuLdal-ce with the
aromatic content of the feed and also with the temperature
used in the hydroisomerization since higher t~ ~LuLes
will be associated with a higher level of cracking and,
rnnce~l~ntly~ with a higher level of olefin production,
some of which will be in the lube boiling range so that
product stability will need to be as6ured by saturation.
~ydrogen circulation rates of at least
180 n.l.l. will normally provide sufficient hydLugell to
-ncate for the expected hydrogen ~vn~l Lion as well as
lS to ensure a low rate of catalyst aging.
An interbed quench is desirable to maintain temperature
in the process. Cold h~dLVY~II is generally used as the
quench, but a liquid quench, usually recycled product, may
also be used.
Sha~e-selective Catalvtic r~ n~ Phase
The effluent from the isomerization phase still
contains quantities of the more waxy straight chain, n-
paraffins, together with the higher melting no1. noL~
paraffins. Because these contribute to unfavorable pour
points, and because the effluent will have a pour point
which is above the target pour point for the product, it is
n~r~c~Ary to remove these waxy L~. To do this
wlthout removing the desirable isoparaffinic - -
which contribute to high V.I. in the product, a shape-
selective ~ Ying catalyst is employed. This catalystremoves the n-paraffins toge~h~r with the waxy, slightly
branched chain paraffins, while leaving the more branched
chain iso-paraffins in the process stream. Shape-selective
catalytic dewaxing processes employ catalysts which are
more highly selective for removal of n-paraffins and
slightly branched chain paraffins than is the isomerization
catalyst, zeolite beta. This phase of the synergistic
SUBSrlTUTE SHEET (RULE 26~
. .
W09~0771~ t '3 ~CT~S9~11036
-2~-
process is therefore carried out as described in U.S.
Patent No. 4,919,788, to which reference is made for a
description of this phase. The catalytic d _- ng step in
the present process is carried out with a constrained,
shape selective d~ ng catalyst based on a constrained
int~ Ate pore crysfAlline~ material, such as an
alumino ~l,GD~ e. A constrained int~ -'iAte crystalline
material has at least one channel of 10-membered oxygen
rings with any intersecting channel having 8-membered
rings. ZSN-23 is the preferred zeolite for this purpose
although other highly shape-selective zeolites such as ZSM-
22 or the synthetic ferrierite ZSM-35 may also be used,
especially with lighter stocks. Silicoaluminophosphates
such as SAP0-11 and SAP0-41 maybe used as selective
dewaxing catalysts.
The preferred catalysts for use as the dewlY;ng
catalysts are the relatively constrained int~ -';Ate pore
size zeolites. Such preferred zeolites have a Constraint
Index in the range of 1-12, as det~rm i n~ by the method
described in U.S. Patent No. 4,016,218. These preferred
zeolites are also characterized by specific sorption
properties related to their relatively constrained
diffusion characteristics. These sorption characteristics
are those which are set out in U.S. Patent No. 4,810,357
for the zeolites such as zeolite ZSM-22, ZSM-23, ZSM-35 and
ferrierite. These zeolites have pore op~n;ngs which result
in a specific combination of sorption properties, namely,
(1) a ratio of sorption of n-hexane to o-xylene, on a
volume percent basis, of greater than 3, wherein sorption
is determin~d at a P/PO of 0.1 and at a temperature of 50-C
for n-hexane and 80-C for o-xylene and (2) by the ability
of selectively cracking 3-methylpentane (3MP) in preference
to the doubly branched 2,3-dimethylbutane (DN~3) at 538-C
and 1 ~ re pressure from a 1/1/1 weight ratio mixture
of n-hexane/3-methyl-pentane/2,3-dimethylbutane, with the
ratio of rate C~I~DLan~S k,~k~ ~t~rm;nr~ at a t~ ~tUL~
of 538-C being in excess of 2.
SUBSrITUTE SHEET (flULE 26
WO96/07715 2 1 q 8 2 1 3 PCT~S95111036
-25-
The expression, "P/PO", i8 accorded its ufiual
~ignifi~n~e as described in the literature, for example,
in "The Dynamical Character of Adsorption" by J.H. deBoer,
2nd Edition, Oxford University Press (1968) and i8 the
relative pL~_nULe defined as the ratio of the partial
~L~nnUL~ of sorbate to the vapor ~L~snuL~ of sorbate at the
t~ tUL~ of sorption. The ratio of the rate constants,
k3~/k=~, is det~mmin~d from 1st order kinetics, in the
usual manner, by the following equation:
k r (l/Tc) ln (1/1-~)
where k is the rate constant for each ~nt, T~ is the
contact time and ~ is the fractional conversion of each
component.
Zeolites conforming to these sorption requirements
include the naturally occurring zeolite ferrierite as well
as the synthetic zeolites ZSM-22, ZSM-23 and ZSM-35. These
zeolites are at least partly in the acid or hydLu~en form
when they are used in the present process.
The preparation and properties of zeolite ZSM-22 are
described in U.S. Patent No. 4,810,357 (Chester) to which
reference is made for such a description.
The synthetic zeolite ZSM-23 is described in U.S.
Patent Nos. 4,076,842 and 4,104,151 to which reference is
made for a description of this zeolite, its preparation and
properties.
The int~ ';Ate pore-size synthetic crystalline
material designated ZSM-35 ("zeolite ZSM-35" or simply
"ZSM-35"), is described in U.S. patent No. 4,~16,245, to
which LefeL~ e is made for a description of this zeolite
and its ~Le~aL~Lion. The synthesis of SAPO-ll is described
in U.S. Patent Nos. 4,943,424 and 4,440,871. The synthesis
of SAPO-41 is described in U.S. Patent No. 4,440,871.
Ferrierite is a naturally-o~uuLLing mineral, described
in the literature, see, e.g., D.W. Breck, ZEOLITE MOLECULAR
SIEVES, John Wiley and Sons (1974), pages 125-127, 146, 219
and 625, to which reference is made for a description of
this zeolite.
SU8STITUTE SHEET (flULE 26
Wos~077~s PCT~S95/11036
2 ~ q8~ t 3
-26-
The dewaxing catalysts used in the shape-seleCtive
catalytic ' Yin~ include a metal hydL~yc--ation-
dehyd~yenation - L. Although it may not be strictly
~PcD~Ary to promote the selective cracking reactions, the
presence of this : _ L has been found to be desirable
to promote certain isomerization reactions which contribute
to the synergy of the two catalyst dewaxing system. The
esellce of the metal _ - L leads to product
1 ~v. L, P~p~ciAlly VI, and stability as well as
helping to retard catalyst aging. The shape-selective,
catalytic d~; Yi ng is normally carried out in the presence
of hydrogen under ~~s~uLe. The metal will be preferably
platinum or palladium. The amount of the metal '~ nt
will typically be 0.1 to 10 percent by weight. Matrix
materials and binders may be employed as n~c~qry. Table
5 illustrates the properties of a ZSM-23 catalyst
containing Pt.
Shape selective ~--qY;ng using the highly constrained,
highly shape-selective catalysts may be carried out in the
same general manner as other catalytic dewaxing processes,
such as those described above for the initial isomerization
phase. Conditions will therefore be of elevated
t~ ~~a~u~c and p~cs~uLe with hydluyelll typically at
temperatures from 250- to 500-C, more usually 300- to 450-C
and in most cases not higher than 370-C. Pressures extend
up to 20786 kPa~, and more usually up to 17339 kPa~
Space velocities extend from 0.1 to 10 hr~l (1HSV), more
usually 0.2 to 5 hr~'. Hydrogen circulation rates range
from 500 to 1000 n.l.l.~l, and more usually 200 to 400
n.1.1.~~. Reference is made to U.S. Patent 4,919,788 for a
more eytDn~d discussion of the shape-selective catalytic
dewaxing step. As indicated previously, hydr ogcll may be
used as an interbed quench in o=rder to provide maximum
t- aLuL~ control in the reactor. Example 6 and Figure
4, infra illustrate the effectiveness of employing ZSM-23
in combination with zeolite beta in an integrated catalyst
system. Pt/ZSM-23, although primarily a shape selective
catalyst, adds in~r~ tal isomerization capability.
~ .
SU8STITUTE SHET (RULE 26)
W096107715 2 I q 8 2 1 3 PCT~S95/11036
-Z7-
The degree of conversion to lower boiling species in
the d ' ng stage will vary àccording to the extent of
~ - ng desired at this point, i.e. on the difference
between the target pour point and the pour point of the
effluent from the isomerization stage. It will also depend
upon the selectivity of the shape-selective catalyst which
i8 used. At lower product pour points, and with relatively
less selective ~ ' ng catalysts, higher conversions and
coL~ ;ngly higher hydL~ge~ u.ll~tions will be
encountered. In general terms conversion to products
boiling outside the lube range, e.g. 315-C-, more typically
345-C-, will be at least 5 weight percent, and in most
cases at least 10 weight percent, with conversions of up to
30 weight percent being n~r~ccAry only to achieve the
lowest pour points with catalysts of the re~uired
selectivity. Boiling range conversion on a 345 C basis
will usually be in the range of 10-25 weight percent.
After the pour point of the oil has been reduced to the
desired value by selective ~ ~ing, the dewaxed oil may be
subjected to LL~ai - Ls such as l-ydLuLL=ating, in order to
remove color bodies and produce a lube product of the
desired characteristics. Fractionation may be employed to
remove light ends and to meet volatility specifications.
It is ~yaL~IL that the highly advantageous results
achieved with the present process in terms of lube yield,
V.I., and other product properties can be ascribed to the
synergistic functioning of the two catalytic phases. In
the first phase the large pore zeolite acts more
preferentially than conventional dewaxing catalysts on the
high le~ Ar weight waxy species in the feed, i.e. the
back end of the feed, isomerizing them with minimal
cracking. These high molecular weight waxy species, if not
removed nearly completely in the ~ -~Ying process,
contribute to high cloud point and a hazy appearance at
near-ambient t~ LUL~8. Because access to the pore
~LLu~LuLe of the large pore zeolite is less restricted than
the pore ~LLUCLULeS of conventional dewaxing catalysts, a
large pore zeolite is not able to dewax the feed to low
SU8STITUTE SHET (RULE 26~
W09Cl0171S 2 1 9 8 ~ 1 3 PCT~S9~11036
-2~-
pour point (less than -12-C) without incurring eignificAnt
yield and V.I. losses due to cracking of branched species.
However, zeolite beta is effective for selectively
converting bulky WaY molecules when operated to convert 40
to 90%, more preferably 50% to 80%, of the wax in the feed
to the L~J ~ La~ ' ng proces5. The pour point of the
product exiting the isomPrization step, on an approximate
345-C+ basis, will depend on thç nature of the feedstock
but is typically between 5-C anq 32 C. The int~ ~;Ate
pore size catalysts arç, by contrast, more effective at
removing the waxes in the front end (low boiling
- ~nts) of the feed. As Example 6 and Figure 4 infra
illustrate, intP 'iAte pore size molecular sieves such as
Pt/Z5M-23 possPqep~ in~L~ Lal isomerization capabilities
in addition to shape-selective dewaxing capabilities.
Thus, by applying these properties of the intP 'iAte pore
size molecular sieves in combination with the properties of
a large pore zeolites as described above, it has become
possible to evolve a synergistic catalytic dewaxing process
which makes the most effective use of the two types of
zeolites. A large pore zeolite is used in an initial stage
to convert waxy paraffins to less waxy iso-paraffins by
isomerization, acting preferentially on the waxy ~ .~nts
in the back end of the feed. The partly dewaxed feed is
then p~u~-e~sed over an int~ -';Ate pore size zeolite to
convert the residual waxy _ LS SO that the final
product has a low pour point and low cloud point.
Products
The products from the process are high V.I., low pour
point, and low cloud point materials which are obtained in
~Y~ pnt yield. Besides having excellent vie~ LL1C
properties they are also highly stable, both oxidatively
and ~hPrr-lly. They are also stable when eYposed to
ultraviolet light. V.I. values in the range of 130 to 150
are typically obtained with the preferred wax feeds to the
process. Values of at least 140 at-18-C pour point, are
readily achievable, with product yields at -18-C pour point
SUBSTITUTE SHET (RULE 26)
WO96/0771~ 3 PCT~S9~ 036
-2g-
of at least 50 weight percent, usually at least 60 weight
percent, based on the original wax feed. The isomerization
of the paraffins to iso-paraffins with high VI values at
low pour points permits the production of lube products
with a unique combination of low pour point and VI.
Typically the current ~Ludu~Ls have a VI in the range of
130-150 at -18-C pour and a VI of l20-145 at --40-C pour
point.
FYAmnleS
The following examples are given in order to illustrate
various aspects of the present process and are not to be
considered limiting. Examples 1 and 2, directly following,
illustrate the preparation of a low acidity Pt/zeolite beta
catalyst and Pt/ZSM-23 catalyst, respectively.
r le l
Zeolite beta with a bulk siOJAl2O3 ratio of 40 was
bound in a 65% zeolite formulation using Hisil 233
precipitated silica and LUDOX HS-40 sodium-stabilized
colloidal silica. The mixture was extruded using a 3~ NaOH
solution to form l/16" quadrulobe ~LLudates. The catalyst
was calcined in a nitrogen ai '-re at 482 C for 3 hours
and then in air at 538-C for an additional 6 hours.
Following calcination, the extrudates were treated with 2M
oxalic acid for 6 hours at 71-C. After acid extraction,
the catalyst was c~lr;n~d in air at 538-C Platinum was
added to the catalyst by ion exchange using Pt(NH3)~Cl2.
Following platinum addition, the catalyst was dried and
c~lr-in~d in air at 349-C for 3 hours. Properties of the
catalyst are given in Table 4.
SU8STITUTE SHEET (RULE 26)
W096t077~5 2-1 9 8 2 1 3 PCT~S95111036
-30-
T~ble 4
Pro~erties of Low-Acidity Zeolite Beta
Platinum, wt% 0.6
Sodium, ppm 245
Al20" wt~ 0-4
Surface Area, m2/g 316
Pore volume, cc/g 0.978
Alpha (before Pt addition) 8
~~~~ le 2
A ZSM-23 zeolite with a bulk SiO2/Al20~ ratio of 120 was
extruded with Versal alumina into 1/16" cylindrical
extrudates. Following extrusion~the material was calcined
in a nitrogen atmosphere at 538 C for 3 hours, then cooled
to ambient temperature. It was then ; -n;nm exchanged to
lS reduce the sodium level, air calcined at 538-C for 6 hours,
then steamed at 482-C for 4 hours. After steaming, the
catalyst was cooled down to ambient temperature and then
platinum was added to the catalyst by ion ~Yrh~nqe with
Pt(NH3)~Clz. Following Pt addition, the catalyst was dried
and c~lr;n~d in air at 349-C for 3 hours. Properties of
the catalyst are given by Table 5.
-~ TabLe 5
Properties of Pt/ZSM-23
Platinum, wt~ 0.2
Sodium, ppm 92
Surface Area, m2/g 242
Pore Volume, cc/g 1.119
~lpha (before Pt addition) 31
~Y~le 3
A slack wax obtained by solvent dewaxing a heavy
neutral furfural raffinate (HNSW) was pletL~ated by
LydLo~L~cking at low boiling range conversion (9%
SU~STITUTE S!1EET (RULE 26)
2 1 982 t 3
WO96/07715 PCT~Ss~11036
-31-
conversion to 345-C or below) using a commercially
available ~luorided-NiW/Al2O~ catalyst. HydLu~L~king slack
waxes serves to lower the nitrogen content of the wax and
to upgrade the occluded oil in the wax to higher V.I.
, Ls. Conditions for the 1.ydLo~L~cking were: 1 LHSV,
393~C, 8375 kPa~, 712 n.l.l.~l circulation. Properties of
the slack wax and mildly 1.ydL~L~cked slack wax are given
by Table 6.
SUBSTITUTE Sl IEET (RULE 26)
WO96/07715 2 1 q 8 2 1 3 PCT~S95111036
-32-
Table 6
Properties of Hcavy Neutral Slack wax and Mildly
HydL~r~cked Slack Wax
Hydrocracked
Slack pT Iy ,~1 A~k Wax
API Gravity 36.0 37.2
Nitrogen, ppm 20 <5
Sulfur, ppm 1000 <5
XV at lOO-C, cSt 7.1
Wax Content, % 66 55
(on 345-C+ basis)
Com~osition. %
Paraffins 55
MnTln~Aphthenes 13
Polynaphthenes 20
Aromatics 12
S,i Tn Dist. ~C
IBP 382 186
5% Off 429 314
10% 442 391
50% 491 477
90% 544 535
FBP 586 575
r le 4
Approximately 70 cc of the Pt/zeolite beta catalyst of
Example 1 and the Pt/ZSM-23 catalyst of Example 2 were
loaded into two separate reactors. Zeolite beta was loaded
into the first reactor and ZS~-23 was loaded in to the
second reactor. The mildly hydLu~L~cked slack wax of
Example 3 was fed to the first reactor containing zeolite
beta with hydl~yen in c~n~uLL~IlL downward flow. The total
effluent from the first reactor was bypassed around the
second reactor. Conditions for the experiment were:
~HSV, hr~l: 1.0
H~, n.l.l.~l: 712 n.l.l.~
Pressure: 13891 kPa~
The total liquid product from the reaction process was
analyzed by simulated distillation and then distilled to a
nominal 345-C+ cutpoint. The distilled boltoms were
analyzed for viscosity, pour point. Figure 1 illustrates
how VI varies with pour point for Pt/zeolite beta, if used
SUB~ITUTE SHET ~RUI~ 26~
_ _ _ _ _ , _ =: _ _ _ _ = _ _ _
W096/07715 21 98 21 3 PCT~S95/11036
-33-
alone. Figures 3 shows how V.I. yield varies,
respectively, with decreasing pour point of the distilled
bottoms. Lube yield is based on the HNSW (heavy neutral
slack wax) feed to the mild hydLu~L~cking pleLL~ai
5 step.
Several of the liquid products produced from these
experiments were solvent dewaxed to -18-C pour. The
relation~hir between solvent dewaxed lube yield and wax
conversion is shown by Figure 4. Wax conversion i6 defined
by:
Wax Content of Feed - Wax Content of Reaction
Product
Wax Conversion =
Wax Content of ~eed
Low acidity Pt/zeolite beta is an effective
isomerization catalyst converting wax to lube with mineral
cracking to light products up to a wax conversion of 55-
60%. When wax conversion increases above 80%, isomerized
paraffins, which have ready access to the Pt/zeolite beta
pore structure crack more rapidly than they can be formed
by isomerizing the I~ ininq wax. The result is that yield
decreases rapidly with further increases in conversion.
Exa~mE~ e 5
The mildly hydLu~Lacked slack wax of Example 3 was
bypassed around the first reactor and fed to the second
reactor containing Pt/ZSM-23. Process conditions were
identical to those of Example 4. The total liquid product
was treated as in Example 4. Variation of V.I. and yield
with bottoms pour point are shown by Figures 1 and 3
respectively.
Flgure 1 shows that for isomerization/dewaxing over
either Pt/zeolite beta or Pt/ZSM-23, V.I. drops sharply
with decreasing pour point. The slopes of the curves
depicting the variation of V.I. with pour point are similar
at a given pour point when the reaction occurs over
SU8STITUTE SHEET (RULE 26~
_ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
W0961077l5 2 1 9 8 2 ~ i PCT~S95/11036
Pt/zeolite beta or Pt/ZSM-23 alone. Despite V.I. being
approximately 5-6 numbers higher for Pt/ZSM-23 than for
Pt/zeolite beta at a given pour point, it is not poc~;h~e
to produce a lubricant stock having a V.I. greater than 135
with the use of either Pt/zeolite beta or Pt/ZSM-23 alone
to dewax the lube to a -12-C pour point. The production of
135+ V.I. base stocks with either of these catalysts
operating alone requires operation of the catalyst to
achieve wax conversion typically less than 85~ with the
residual wax being removed from the product by solvent
Y; ng.
~1le 6
The mildly hydrocracked slack wax of Example 3 was fed
to the Pt/zeolite beta reactor and the effluent from the
Pt/zeolite beta passed over the Pt/ZSM-23. Both reactors
operated at the conditions of Example 4 (1 L~SV over each
reactor~. The zeolite beta was operated at 322-c to
convert approximately 70% of the wax in the mildly
hydLu~L~cked waxy feed where wax conversion is defined by
the equation in Example 4.
A sample of the product from the first reactor was
distilled with the 345-C bottoms found to have a pour point
of 30-C. The total effluent from the first reactor was
rA~r~d to the Pt/ZSM-23 reactor and t~ ~ ~LUL~ varied in
the second reactor to effect changes in product pour point.
Variation of V.I. and yield with bottoms pour point are
compared to the variations obtained by operating the
catalysts individually by Figures 2 and 3 respectively.
Operating the Pt/zeolite beta to a distilled bottoms
pour point of 30-C and removing the residual wax with
Pt/ZSM-23 results in a lubricant having a VI which is less
sensitive to pour point variation than a lubricant pLuduced
by either catalyst operating alone, as shown by Figure 2.
The inteqrated, synergistic catalyst system allows
production of 135+ V.I. lubricants at -12-C pour for which
either catalyst operating alone does not.
. . . :
SU8STITUTE SliEET (RULE 2~)
,i
W096/07715 2 1 9 8 2 1 3 PCT~S9S/11036
-35-
The relatively shallow slope also implies that very low
pour points can be achieved without incurring a ~Dt~l~tial
V.I. penalty.
The integrated catalyst system also offers ~iqn;f~c~nt
yield benefit over either catalyst operating alone (Figure
3). The shallow slopes of the branch emanating from the
Pt/zeolite beta curve where Pt/zeolite beta is operating at
322-C, implies that very low pour points can be achieved
without substantial yield penalty by the synergistic
catalyst system.
The synergy of the system reflects the difference in
shape selectivities of the two catalysts, and their ability
to isomerize waxes. The incremental isomerization
capability of Pt/ZSM-23 is illustrated by Figure 4 which
shows solvent dewaxed oil lube as a function of wax
conversion for products generated by these experiments
having a pour point above -12-C. Above 75% wax conversion,
dewaxed oil yield decreases for Pt/zeolite beta operating
alone. However, using Pt/ZSM-23 to dewax the Pt/zeolite
beta effluent results in an increase in solvent dewaxed
lube yield implying that Pt/ZSM-23 adds ir.~L~
isomerization ability. In addition to converting some waxy
species to lube, Pt/ZSM-23 has sufficient shape selectivity
to prevent most of the isoparaffins formed over Pt/zeolite
beta from cracking and reducing lube yield.
Example 7
The mildly l.ydL~L~cked slack wax of Example 3 was fed
to the Pt/zeolite beta reactor at the conditions of Example
4. The Pt/zeolite beta reactor was operated at 329-C to
achieve approximately 88% wax conversion with wax
conversion being defined in Example 4. A sample of the
product from the first reactor was distilled and the 345-C
bottoms found to have a pour point of 16-C. The total
effluent from the first reactor was fed to the Pt/ZSM-23
reactor and temperature varied in the second reactor to
effect changes in product pour point. Variation of V.I.
and yield with bottoms pour point are shown by Figures 2
SU8STITUTE SHEET (flULE 26)
WOsC/o77l5 ~ 3 PCT~S95/11036
-36-
and 3 respectively. Lube yield is based on heavy neutral
slack wax fed to the 1Iyd~ cking reactor.
Similar to Example 6, the slopes of the VI and lube
yield curves with pour point are ~ign;f;c~ntly shallower
than for either catalyst operating alone. This ~uyy~
that the synergy of the dual catalyst system exists for a
range of Pt~zeolite beta operating conditions. Figure 3
shows that yield at low pour point, e.g. less than -12-C,
is highest for the two-catalyst system. Neither catalyst
operating alone gives a yield PY~ ;ng 55% while the two
examples of the two-catalyst system each gave ylelds at -
12-C pour of at least 60%.
Table 7 shows a yield and V.I. co~parison for Examples
4 through 7 for a lubricant of lO-F PouF point.
Table 7
Comparison of Synergistic Catalyst System
Selectivity with Stand-alone Catalystss~
Conditions: 1 LHSV Over Each Reactor, 1389 kPa~, 712
n.l.l.~l
2 o At -12~C Pour Point
- PVzeolite// PVzeolite/
PVzeolite j beta beta
/betaPt/ZSM-23 Pt/ZSM-23 P~ZSM-23
Exarnple 4 5 6 7
PV,~ Temp,~C 3i1 - 322 329
PVZSM-23 Temp,CC - 350 329 a32
345 ~C+ Product
V.l. 121 133 142 135
Yield, ~/O HNSW 38 53 iO 60
(1)1~ uldl~1 and e~dlc4~oldteld from Figures 1 and 2
SUBSTITUTE SHEET (RULE 26)
WO96/0771~ 21 98?~3 PCT~59~11036
-37-
E le 8
The mildly h~1LU~L _hed slack wax o~ Example 3 was
plucessed over Pt/zeolite beta at the conditions of Example
4 to achieve approximately 82% wax conversion. The total
reactor e~fluent was ~u~essed over Pt/ZS~-23 at a
te~mperature o~ 346-C. The reaction product was distilled
to a normal 345-C cutpoint. The distilled bottoms had the
following properties:
'
SUBSTITUTE SHEET (RULE 26)
W096/07~15 2 1 9 ~ 2 t ~ PCT~S95/11036
-38-
Table 8
Pro~erties of Distilled Bottoms
Viscosity, Rinematic at lOO-C, cSt 5.20
V.I., Viscosity Index 132
Pour Point, ~C ~37
Cloud Point, ~C -24
Simul~ted Di5tillation C
Initial Boiling Point 304
5~ Off 334
10% 356
50% 447
90% 516
Final 80iling Point 564
Aromatics (by W), % <1
This example shows that the integrated Pt/zeolite
beta/Pt/ZSM-23 catalyst system i5 capable of producing base
stocks with viscosity indices ~Y~e~;ng 135 at very low
pour points. The superior cloud point of -24 C reflects
the benefit of proc~ccing the feed over zeolite beta prior
to ZSM-23. Zeolite beta, because of its less constrained
pore nature, has the ability to convert large waxy
molecules which often lead to high pour/cloud
differentials. Int~ te pore zeolites, such as ZSM-23,
have more difficulty converting high moLecular weight waxes
fre~uently leading to low pour point base stocks with
relatively high cloud points.
W absorptivity meaauL~ Ls show the benefit of high
~LeS~ULe for producing high V.I., low aromatics base
stocks.
SURSTITUTE SHEET (RULE 26)
WO96/07715 2 1 982 1 ~ pCT~S95111036
39
r le 9
A heavy ~ L~L~ d vacuum distillate having the
properties below was dewaxed by Pt/ZSN-23 operating alone
and by the Pt/zeolite beta // Pt/ZSM-23 catalytic d Y; ng
gystem.
API Gravity 30.3
Viscosity, KV at lOO-C, cSt 9.90
Pour Point, ~C 49
Sulfur, ppm <20
Nitrogen, ppm 2
Wax Content, ~ 15
Sim Distillation, ~C
IBP 368
5~ Off 385
10% 399
50~ 485
90% 564
The data, tabulated below, show a slight synergy for
the combination catalyst system for low wax content feeds
in that yield is at least equivalent and sometimes slightly
higher at constant pour point. The less restrictive nature
of the Pt/zeolite beta catalyst enables some incremental
conversion of high boiling waxes leading to lower cloud
points for the combination catalyst system. This is an
SUBSTITUTE SltEEI (RULE 26)
W096/0771~ 2 1 98~ 1 ~ PCTN89~11036
-io- ~
~r~ri~lly critic~l benefit since highly shape selective
d - ' ng catalysts cAn give hazy products with high cloud
points when d-. Y; ng heavy feeds.
Catalvst PTIZSM-23 PVzeolite beta//
PUZSM-23
Pour Point d
345~C+ Fraction
A1tor Pt/zeolite beta
Dewaxin~,~C 18
345 C+ Frartion
Pour Point, ~C -21 -26 -37 -15 -23 -29-37
Cloud Point, ~C 3 -2 -9 1 -8 -9 -14
Dmorence
Cloud/Pour, C~ 24 24 28 16 15 20 23
Yield, wt% 94 92 88 94 92 91 90
Vl 107 104 103 -104 104 103
r le lO
A 650 SUS heavy neutral slack wax was hydLu~-~cked and
stripped to remove ammonia and HzS. A material having the
following properties was pl~du~ed.
API Gravity 37.4
Sulfur, ppm 2
Nitrogen, ppm <2
Oil Content on
650 F+ Fraction, ~C >49
Sim Dist, ~C
IBP/5% 125/255
10%/20% 330/434
50%/80% 497/S27
90%/FBP 538/S66
This LydLo~L~cked material was dewaxed to very low pour
point over the Pt/ZSN-23 catalyst of Example 2. It was
also dewaxed to very low pour point with the Pt/zeolite
beta // Pt/ZSN-23 catalyst ~ystem where the Pt/zeolite beta
temperature was maintained to convert 6S% of the wax in the
l.ydL~L~cked feed. Wax conversion is defined in Example 4.
SUBSTITIJTE SHEET (RULE 2~)
WO96/07715 PCT~S95111036
2 1 q~t ~
The Pt/ZSN-23 catalyst used in the dual catalyst system was
the same as that used in Fxample 2.
The Pt/zeolite beta was prepared by extruding beta
zeolite with Versal 250 psel~Ar'-o-~ ite alumina to form
1/16" ~LLudate. The extrudate was dried and cAlc;nPd in
nitrogen for 3 hours at 482-C, then cAl~inpd in air at 1000
for 6 hours. Following calcination, the extrudate was
steamed in 100% steam at 549-C for 96 hours. Platinum was
incoL~oL~ted on the extrudate by ion PY~hAn~e with an
aqueous solution of platinum tetraamine chloride to achieve
a loading of 0.6 wt%. ~he cataiyst was then calcined in
air at 349-C for 3 hours.
The dewaxed products were distilled to a nominal 345-C+
cutpoint and the pour point and cloud points were measured
to be:
SU8STITUTE SHET (flULE 26~
W096/0771~ 2 I q 8 2 1 3 PCTNS95/11036
-~2-
- Pt/zeolite beta//
C~ ~-V;aa Catalvsts Pt/~SM-23 PtlZSM-23
Wa~ Conversion Over PVB, ~/0 - 65
Pour Point of 650~F+
Fraction After Pt/B
Dewaxing, ~C - 29
Dewaxed Lube
Pour Point, ~C -37 -43
Cloud Point, ~C -7 -34
o Sim Dist., ~C
IBP/5%/10% 300/300/353 313/341/361
This example shows that the incre~ental conversion of
high pour point waxes over Pt/zeolite beta leads to low
product cloud point. Pt/ZSM-23~ because of its less
accessible ~Lru~Lu~ is not as effective at converting waxy
species thLuu~h~uL the feed boiling range thus leading to a
relatively high cloud points.
SU~STITUTE SHET (RllLE 26)
