U.S. patent application number 10/471039 was filed with the patent office on 2004-04-29 for automatic transmission fluid.
Invention is credited to Germaine, Gilbert Robert Bernard, Mueller, Hans Dieter, Wedlock, David John.
Application Number | 20040079675 10/471039 |
Document ID | / |
Family ID | 26077226 |
Filed Date | 2004-04-29 |
United States Patent
Application |
20040079675 |
Kind Code |
A1 |
Germaine, Gilbert Robert Bernard ;
et al. |
April 29, 2004 |
Automatic transmission fluid
Abstract
Automatic transmission fluid having a kinematic viscosity at
100.degree. C. of between more than 4 cSt and 10 cSt, a dynamic
viscosity at -40.degree. C. of less than 10000 mPas comprising an
additive package and a base oil, wherein the base oil fraction has
at least 98 wt % saturates, of which saturates fraction the content
of cyclo-paraffins is between 10 wt and 40 wt % and wherein the
pour point of the base oil is less than -25.degree. C.
Inventors: |
Germaine, Gilbert Robert
Bernard; (Petit Couronne, FR) ; Mueller, Hans
Dieter; (Hamburg, DE) ; Wedlock, David John;
(Chester, GB) |
Correspondence
Address: |
Richard F Lemuth
Shell Oil Company
Intellectual Property
PO Box 2463
Houston
TX
77252-2463
US
|
Family ID: |
26077226 |
Appl. No.: |
10/471039 |
Filed: |
September 4, 2003 |
PCT Filed: |
March 5, 2002 |
PCT NO: |
PCT/EP02/02450 |
Current U.S.
Class: |
208/19 |
Current CPC
Class: |
C10M 169/04 20130101;
C10M 2205/173 20130101; C10N 2030/12 20130101; C10G 2400/08
20130101; C10G 2400/10 20130101; C10N 2030/04 20130101; Y10S 208/95
20130101; C10N 2040/252 20200501; C10M 107/02 20130101; C10M 171/02
20130101; C10G 2400/04 20130101; C10G 2400/06 20130101; C10G
2300/1022 20130101; C10G 2/32 20130101; C10G 2300/301 20130101;
C10N 2030/02 20130101; C10G 2/30 20130101; C10G 2300/304 20130101;
C10N 2040/25 20130101; C10G 45/58 20130101; C10G 2300/4081
20130101; C10G 2300/302 20130101 |
Class at
Publication: |
208/019 |
International
Class: |
C10G 071/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 5, 2001 |
EP |
01400562.3 |
Aug 16, 2001 |
EP |
01402181.0 |
Claims
1. Automatic transmission fluid having a kinematic viscosity at
100.degree. C. of between more than 4 and 10 cSt, a dynamic
viscosity at -40.degree. C. of less than 10000 mPas comprising an
additive package and a base oil component, wherein the base oil
component comprises at least 98 wt % saturates, of which saturates
fraction the content of cyclo-paraffins is between 10 and 40 wt %
and wherein the pour point of the base oil is less than -25.degree.
C.
2. Fluid according to claim 1, wherein the pour point of the base
oil component is below -30.degree. C.
3. Fluid according to any one of claims 1-2, wherein the VI of the
base oil component is between 110 and 150.
4. Fluid according to any one of claims 1-3, wherein the content of
cyclic-paraffins is at least 12 wt %.
5. Fluid according to any one of claims 1-4, wherein the base oil
component is obtainable from a process comprising the following
steps: (a) contacting a mixture of carbon monoxide and hydrogen
with a hydrocarbon synthesis catalyst at elevated temperature and
pressure to prepare a substantially paraffinic Fischer-Tropsch
product, which product has a weight ratio of compounds having at
least 60 or more carbon atoms and compounds having at least 30
carbon atoms in the Fischer-Tropsch product of at least 0.2 and
wherein at least 30 wt % of compounds in the Fischer-Tropsch
product have at least 30 carbon atoms (b)
hydrocracking/hydroisomerisating the Fischer-Tropsch product, (c)
separating the product of step (b) into one or more gas oil
fractions, a base oil precursor fraction and a optionally a higher
boiling fraction, (d) performing a pour point reducing step to the
base oil precursor fraction obtained in step (c), and (e)
recovering the base oil component from the effluent of step
(d).
6. Fluid according to claim 5, wherein the Fischer-Tropsch product
used in step (b) has at least 50 wt % of compounds having at least
30 carbon atoms and wherein the weight ratio of compounds having at
least 60 or more carbon atoms and compounds having at least 30
carbon atoms of the Fischer-Tropsch product is at least 0.4 and
wherein the Fischer-Tropsch product comprises a C.sub.20.sup.+
fraction having an ASF-alpha value (Anderson-Schulz-Flory chain
growth factor) of at least 0.925.
7. Fluid according to claim 6, wherein at least 55 wt % of the
compounds have at least 30 carbon atoms.
Description
[0001] The invention is directed to an automatic transmission fluid
having a kinematic viscosity at 100.degree. C. of between more than
4 and 10 cSt, a dynamic viscosity at -40.degree. C. of less than
10000 mPas comprising an additive package and a base oil component,
wherein the base oil component comprises at least 98 wt %
saturates, of which saturates fraction the content of
cyclo-paraffins is between 10 and 40 wt % and wherein the pour
point of the base oil component is less than -25.degree. C.
[0002] WO-A-9941332 discloses such an automatic transmission fluid
composition. The base oil component of this composition was
obtained by hydroisomerisation of a hydrotreated slack wax followed
by solvent dewaxing. The pour point of the base oil was about
-23.degree. C., which is a typical pour point for base oils as
obtained by means of a solvent dewaxing process.
[0003] A disadvantage of the ATF fluid as disclosed in WO-A-9941332
is their unfavourable low temperature performance, for example
expressed in their low temperature Brookfield viscosity
performance.
[0004] Applicants found that with the above-described formulation
these disadvantages have been overcome.
[0005] Automatic transmission fluids (ATF's) are divided into two
main groups, friction modified fluids and non-friction modified
fluids and are used in automotive and commercial vehicle service.
The friction modified and non-friction modified fluids are
generally similar in their basic requirements; high thermal and
oxidation resistance, low temperature fluidity, high compatibility,
foam control, corrosion control and anti-wear properties. Both
types of fluids have similar friction properties at high sliding
speeds. Different automatic transmission manufacturers do require
somewhat different properties in the fluids used as sliding speed
approaches zero (clutch lock-up). Some manufacturers specify that
the ATF's used with their transmissions exhibit a decrease in
friction coefficient (i.e., more slipperiness) while others want an
increase in friction coefficient.
[0006] The Automatic Transmission Fluid according to the present
invention will preferably contain detergents, dispersants,
anti-wear, anti-rust, friction modifiers, anti-foaming agents, a
detergent-inhibitor pack, a viscosity index (VI) improver, seal
sweller and a pour point depressant. The amount of additives will
depend on the specific additives and combination used and the
specific required properties as specified below in more detail.
[0007] Preferably the frictional behaviour of the fluid is adjusted
to specific requirements to guaranty safe power transfer and shift
performance at low and high sliding speeds. The fully formulated
fluid is further suitably compatible with synthetic rubber seals
used in automatic transmissions. The kinematic viscosity (cSt) is
preferably between 30 and 60 at 40.degree. C., and between about 4
to 10 at 100.degree. C.; Brookfield viscosity of below 20000 mPas
at -40.degree. C., 10000 mPas at about -26 to -40.degree. C., flash
points (COC) between about 150 to about 220.degree. C.; pour point
between about -36 to -48.degree. C.
[0008] The base oil fraction in the Automatic Transmission Fluid
according to the invention is the base oil as described above and
optionally one or more additional base oils. Possible additional
base stocks are mineral base oils and synthetic base oils. Suitable
synthetic base oils are the so-called poly-alpha olefins base
stocks. The improved solvency properties of the basic base oil of
the presently claimed fluid will enhance the lesser solvency
properties of the poly-alpha olefin base stock, while taking
advantage of the viscometric properties of the poly-alpha olefin.
The advantages of the present invention are however fully
appreciated when the base oil fraction in the claimed fluid
comprises of more than 80 wt %, preferably more than 90 wt % and
most preferably 100 wt % of the basic and novel base oil component
as described in this application.
[0009] The base oil component of the automatic transmission fluid
according to the present invention has not been disclosed in the
prior art and it is this novel base oil component, which provides
the advantages as, described above. Known from WO-A-0014179,
WO-A-0014183, WO-A-0014187 and WO-A-0014188 are lubricant base
stock comprising at least 95 wt % of non-cyclic isoparaffins.
WO-A-0118156 describes a base oil derived from a Fischer-Tropsch
product having a naphthenics content of less than 10%. Also the
base oils as disclosed in applicant's patent applications
EP-A-776959 or EP-A-668342 have been found to comprise less than 10
wt % of cyclo-paraffins. Applicants repeated Example 2 and 3 of
EP-A-776959 and base oils were obtained, from a waxy
Fischer-Tropsch synthesis product, wherein the base oils consisted
of respectively about 96 wt % and 93 wt % of iso- and normal
paraffins. Applicants further prepared a base oil having a pour
point of -21.degree. C. by catalytic dewaxing a Shell MDS Waxy
Raffinate (as obtainable from Shell MDS Malaysia Sdn Bhd) using a
catalyst comprising synthetic ferrierite and platinum according to
the teaching of EP-A-668342 and found that the content of iso- and
normal paraffins was about 94 wt %. Thus these prior art base oils
derived from a Fischer-Tropsch synthesis product had at least a
cyclo-paraffin content of below 10 wt %. Furthermore the base oils
as disclosed by the examples of application WO-A-9920720 will not
comprise a high cyclo-paraffin content. This because feedstock and
preparation used in said examples is very similar to the feedstock
and preparation to prepare the above prior art samples based on
EP-A-776959 and EP-A-668342.
[0010] The lubricating base oil component comprises preferably at
least 98 wt % saturates, more preferably at least 99.5 wt %
saturates and most preferably at least 99.9 wt %. This saturates
fraction in the base oil component comprises between 10 and 40 wt %
of cyclo-paraffins. Preferably the content of cyclo-paraffins is
less than 30 wt % and more preferably less than 20 wt %. Preferably
the content of cyclo-paraffins is at least 12 wt %. The unique and
novel base oils are further characterized in that suitably the
weight ratio of 1-ring cyclo-paraffins relative to cyclo-paraffins
having two or more rings is greater than 3 preferably greater than
5. It was found that this ratio is suitably smaller than 15.
[0011] The cyclo-paraffin content as described above is measured by
the following method. Any other method resulting in the same
results may also be used. The base oil sample is first separated
into a polar (aromatic) phase and a non-polar (saturates) phase by
making use of a high performance liquid chromatography (HPLC)
method IP368/01, wherein as mobile phase pentane is used instead of
hexane as the method states. The saturates and aromatic fractions
are then analyzed using a Finnigan MAT90 mass spectrometer equipped
with a Field desorption/Field Ionisation (FD/FI) interface, wherein
FI (a "soft" ionisation technique) is used for the
semi-quantitative determination of hydrocarbon types in terms of
carbon number and hydrogen deficiency. The type classification of
compounds in mass spectrometry is determined by the characteristic
ions formed and is normally classified by "z number". This is given
by the general formula for all hydrocarbon species:
C.sub.nH.sub.2n+z. Because the saturates phase is analysed
separately from the aromatic phase it is possible to determine the
content of the different (cyclo)-paraffins having the same
stoichiometry. The results of the mass spectrometer are processed
using commercial software (poly 32; available from Sierra Analytics
LLC, 3453 Dragoo Park Drive, Modesto, Calif. GA95350 USA) to
determine the relative proportions of each hydrocarbon type and the
average molecular weight and polydispersity of the saturates and
aromatics fractions.
[0012] The base oil component preferably has a content of aromatic
hydrocarbon compounds of less than 1 wt %, more preferably less
than 0.5 wt % and most preferably less than 0.1 wt %, a sulphur
content of less than 20 ppm and a nitrogen content of less than 20
ppm. The pour point of the base oil is preferably less than
-30.degree. C. and more preferably lower than -40.degree. C. The
viscosity index is higher than 120. It has been found that the
novel base oils typically have a viscosity index (VI) of below 150
and a dynamic viscosity at -40.degree. C. of between 3000 and 6000
cP. The kinematic viscosity at 100.degree. C. of the base oil
component is preferably between 3.5 and 6 cSt and the Noack
volatility is preferably between 6 and 14 wt %. The flash point
(COC) is preferably above 140.degree. C.
[0013] Applicants found that the above base oil component is
obtainable according to the following process wherein the following
steps are performed:
[0014] (a) contacting a mixture of carbon monoxide and hydrogen
with a hydrocarbon synthesis catalyst at elevated temperature and
pressure to prepare a substantially paraffinic Fischer-Tropsch
product, which product has a weight ratio of compounds having at
least 60 or more carbon atoms and compounds having at least 30
carbon atoms in the Fischer-Tropsch product of at least 0.2 and
wherein at least 30 wt % of compounds in the Fischer-Tropsch
product have at least 30 carbon atoms
[0015] (b) hydrocracking/hydroisomerisating the Fischer-Tropsch
product,
[0016] (c) separating the product of step (b) into one or more gas
oil fractions, a base oil precursor fraction and a optionally a
higher boiling fraction,
[0017] (d) performing a pour point reducing step to the base oil
precursor fraction obtained in step (c), and
[0018] (e) recovering the base oil component from the effluent of
step (d).
[0019] Step (a) is preferably performed by making use of a specific
catalyst in order to obtain the relatively heavy Fischer-Tropsch
product. The Fischer-Tropsch catalyst is suitably a
cobalt-containing catalyst as obtainable by (aa) mixing (1) titania
or a titania precursor, (2) a liquid, and (3) a cobalt compound,
which is at least partially insoluble in the amount of liquid used,
to form a mixture; (bb) shaping and drying of the mixture thus
obtained; and (cc) calcination of the composition thus
obtained.
[0020] Preferably at least 50 weight percent of the cobalt compound
is insoluble in the amount of liquid used, more preferably at least
70 weight percent, and even more preferably at least 80 weight
percent, and most preferably at least 90 weight percent. Preferably
the cobalt compound is metallic cobalt powder, cobalt hydroxide or
an cobalt oxide, more preferably Co(OH).sub.2 or Co.sub.3O.sub.4.
Preferably the cobalt compound is used in an amount of up to 60
weight percent of the amount of refractory oxide, more preferably
between 10 and 40 wt percent. Preferably the catalyst comprises at
least one promoter metal, preferably manganese, vanadium, rhenium,
ruthenium, zirconium, titanium or chromium, most preferably
manganese. The promoter metal(s) is preferably used in such an
amount that the atomic ratio of cobalt and promoter metal is at
least 4, more preferably at least 5. Suitably at least one promoter
metal compound is present in step (aa). Suitably the cobalt
compound is obtained by precipitation, optionally followed by
calcination. Preferably the cobalt compound and at least one of the
compounds of promoter metal are obtained by co-precipitation, more
preferably by co-precipitation at constant pH. Preferably the
cobalt compound is precipitated in the presence of at least a part
of the titania or the titania precursor, preferably in the presence
of all titania or titania precursor. Preferably the mixing in step
(aa) is performed by kneading or mulling. The thus obtained mixture
is subsequently shaped by pelletising, extrusion, granulating or
crushing, preferably by extrusion. Preferably the mixture obtained
has a solids content in the range of from 30 to 90% by weight,
preferably of from 50 to 80% by weight. Preferably the mixture
formed in step (aa) is a slurry and the slurry thus-obtained is
shaped and dried by spray-drying. Preferably the slurry obtained
has a solids content in the range of from 1 to 30% by weight, more
preferably of from 5 to 20% by weight. Preferably the calcination
is carried out at a temperature between 400 and 750.degree. C.,
more preferably between 500 and 650.degree. C. Further details are
described in WO-A-9934917.
[0021] The process is typically carried out at a temperature in the
range from 125 to 350.degree. C., preferably 175 to 275.degree. C.
The pressure is typically in the range from 5 to 150 bar abs.,
preferably from 5 to 80 bar abs., in particular from 5 to 50 bar
abs. Hydrogen (H.sub.2) and carbon monoxide (synthesis gas) is
typically fed to the process at a molar ratio in the range from 0.5
to 2.5. The gas hourly space velocity (GHSV) of the synthesis gas
in the process of the present invention may vary within wide ranges
and is typically in the range from 400 to 10000 Nl/l/h, for example
from 400 to 4000 Nl/l/h. The term GHSV is well known in the art,
and relates to the volume of synthesis gas in Nl, i.e. litres at
STP conditions (0.degree. C. and 1 bar abs), which is contacted in
one hour with one litre of catalyst particles, i.e. excluding
interparticular void spaces. In the case of a fixed catalyst bed,
the GHSV may also be expressed as per litre of catalyst bed, i.e.
including interparticular void space. Step (a) can be performed in
a slurry reactor or preferably in a fixed bed. Further details are
described in WO-A-9934917.
[0022] The Fischer-Tropsch product obtained in step (a), optionally
after separating some of the lower boiling compounds, for example
the compounds having 4 carbon atoms or less and any compounds
having a boiling point in that range, is used in step (b). This
product has at least 30 wt %, preferably at least 50 wt % and more
preferably at least 55 wt %, of compounds having at least 30 carbon
atoms. Furthermore the weight ratio of compounds having at least 60
or more carbon atoms and compounds having at least 30 carbon atoms
of the Fischer-Tropsch product is at least 0.2, preferably at least
0.4 and more preferably at least 0.55. Preferably the
Fischer-Tropsch product comprises a C.sub.20.sup.+ fraction having
an ASF-alpha value (Anderson-Schulz-Flory chain growth factor) of
at least 0.925, preferably at least 0.935, more preferably at least
0.945, even more preferably at least 0.955. The initial boiling
point of the Fischer-Tropsch product may range up to 400.degree.
C., but is preferably below 200.degree. C.
[0023] The Fischer-Tropsch product as described in detail above
suitably has a content of non-branched compounds of above 80 wt %.
In addition to the Fischer-Tropsch product obtained in step (a)
also other fractions may be additionally processed in step (b). A
possible other fraction may suitably be the higher boiling fraction
obtained in step (c) or part of said fraction.
[0024] The Fischer-Tropsch product will contain no or very little
sulphur and nitrogen containing compounds. This is typical for a
product derived from a Fischer-Tropsch reaction, which uses
synthesis gas containing almost no impurities. Sulphur and nitrogen
levels will generally be below the detection limit, which is
currently 1 ppm for nitrogen and 5 ppm for sulphur.
[0025] The Fischer-Tropsch product can optionally be subjected to a
mild hydrotreatment step before performing step (b) in order to
remove any oxygenates and saturate any olefinic compounds present
in the reaction product of the Fischer-Tropsch reaction. Such a
hydrotreatment is described in EP-B-668342.
[0026] The hydrocracking/hydroisomerisation reaction of step (b) is
preferably performed in the presence of hydrogen and a catalyst,
which catalyst can be chosen from those known to one skilled in the
art as being suitable for this reaction. Catalysts for use in step
(b) typically comprise an acidic functionality and a
hydrogenation/dehydrogenation functionality. Preferred acidic
functionalities are refractory metal oxide carriers. Suitable
carrier materials include silica, alumina, silica-alumina,
zirconia, titania and mixtures thereof. Preferred carrier materials
for inclusion in the catalyst for use in the process of this
invention are silica, alumina and silica-alumina. A particularly
preferred catalyst comprises platinum or platinum/palladium
supported on a silica-alumina carrier. If desired, applying a
halogen moiety, in particular fluorine, or a phosphorous moiety to
the carrier, may enhance the acidity of the catalyst carrier.
Examples of suitable hydrocracking/hydroisomerisation processes and
suitable catalysts are described in WO-A-0014179, EP-A-532118,
EP-B-666894 and the earlier referred to EP-A-776959. The
hydrocracking catalyst may also contain a molecular sieve as for
example described in U.S. Pat. No. 5,362,378.
[0027] Preferred hydrogenation/dehydrogenation functionalities are
Group VIII non-noble metals, for example nickel and cobalt and
Group VIII noble metals, for example palladium and more preferably
platinum or platinum/palladium alloys. The catalyst may comprise
the hydrogenation/dehydrogenation active component in an amount of
from 0.005 to 5 parts by weight, preferably from 0.02 to 2 parts by
weight, per 100 parts by weight of carrier material. A particularly
preferred catalyst for use in the hydroconversion stage comprises
platinum in an amount in the range of from 0.05 to 2 parts by
weight, more preferably from 0.1 to 1 parts by weight, per 100
parts by weight of carrier material. The catalyst may also comprise
a binder to enhance the strength of the catalyst. The binder can be
non-acidic. Examples are clays and other binders known to one
skilled in the art.
[0028] In step (b) the feed is contacted with hydrogen in the
presence of the catalyst at elevated temperature and pressure. The
temperatures typically will be in the range of from 175 to
380.degree. C., preferably higher than 250.degree. C. and more
preferably from 300 to 370.degree. C. The pressure will typically
be in the range of from 10 to 250 bar and preferably between 20 and
80 bar. Hydrogen may be supplied at a gas hourly space velocity of
from 100 to 10000 Nl/l/hr, preferably from 500 to 5000 Nl/l/hr. The
hydrocarbon feed may be provided at a weight hourly space velocity
of from 0.1 to 5 kg/l/hr, preferably higher than 0.5 kg/l/hr and
more preferably lower than 2 kg/l/hr. The ratio of hydrogen to
hydrocarbon feed may range from 100 to 5000 Nl/kg and is preferably
from 250 to 2500 Nl/kg.
[0029] The conversion in step (b) as defined as the weight
percentage of the feed boiling above 370.degree. C. which reacts
per pass to a fraction boiling below 370.degree. C., is at least 20
wt %, preferably at least 25 wt %, but preferably not more than 80
wt %, more preferably not more than 65 wt %. The feed as used above
in the definition is the total hydrocarbon feed fed to step (b),
thus also any optional recycles, such as the optional higher
boiling fraction as obtained in step (c).
[0030] In step (c) the product of step (b) is separated into one or
more gas oil fractions, a base oil precursor fraction having
preferably a T10 wt % boiling point of between 200 and 450.degree.
C. If also a higher boiling fraction is isolated in step (c) the
T90 wt % boiling point of the base oil precursor fraction is
preferably between 300 and 650 preferably 550.degree. C.
[0031] If also a high boiling fraction is isolated in step (c) the
separation is preferably performed by means of a atmospheric and
vacuum distillation step. In a first distillation at about
atmospheric conditions, preferably at a pressure of between 1.2-2
bara, a gas oil product and lower boiling fractions, such as
naphtha and kerosine fractions, are separated from the higher
boiling fraction of the product of step (b). The higher boiling
fraction, of which suitably at least 95 wt % boils above 350
preferably above 370.degree. C., is subsequently further separated
in a vacuum distillation step wherein a vacuum gas oil fraction,
the base oil precursor fraction and the higher boiling fraction are
obtained. The vacuum distillation is suitably performed at a
pressure of between 0.001 and 0.05 bara.
[0032] When no higher boiling fraction is isolated in step (c)
vacuum distillation step ca be omitted. The heavy fraction obtained
in the atmospheric distillation step can then be used as base oil
precursor fraction.
[0033] In step (d) the base oil precursor fraction obtained in step
(c) is subjected to a pour point reducing treatment. With a pour
point reducing treatment is understood every process wherein the
pour point of the base oil is reduced by more than 10.degree. C.,
preferably more than 20.degree. C., more preferably more than
25.degree. C.
[0034] Preferably step (d) is performed by means of a catalytic
dewaxing process. With such a process it has been found that a base
oil component having a pour point of below -30.degree. C. and even
below -40.degree. C. can be prepared.
[0035] The catalytic dewaxing process can be performed by any
process wherein in the presence of a catalyst and hydrogen the pour
point of the base oil precursor fraction is reduced as specified
above. Suitable dewaxing catalysts are heterogeneous catalysts
comprising a molecular sieve and optionally in combination with a
metal having a hydrogenation function, such as the Group VIII
metals. Molecular sieves, and more suitably intermediate pore size
zeolites, have shown a good catalytic ability to reduce the pour
point of the base oil precursor fraction under catalytic dewaxing
conditions. Preferably the intermediate pore size zeolites have a
pore diameter of between 0.35 and 0.8 nm. Suitable intermediate
pore size zeolites are mordenite, ZSM-5, ZSM-12, ZSM-22, ZSM-23,
SSZ-32, ZSM-35 and ZSM-48. Another preferred group of molecular
sieves are the silica-aluminaphosphate (SAPO) materials of which
SAPO-11 is most preferred as for example described in U.S. Pat. No.
4,859,311. ZSM-5 may optionally be used in its HZSM-5 form in the
absence of any Group VIII metal. The other molecular sieves are
preferably used in combination with an added Group VIII metal.
Suitable Group VIII metals are nickel, cobalt, platinum and
palladium. Examples of possible combinations are Ni/ZSM-5,
Pt/ZSM-23, Pd/ZSM-23, Pt/ZSM-48 and Pt/SAPO-11. Further details and
examples of suitable molecular sieves and dewaxing conditions are
for example described in WO-A-9718278, U.S. Pat. No. 5,053,373,
U.S. Pat. No. 5,252,527 and U.S. Pat. No. 4,574,043.
[0036] The dewaxing catalyst suitably also comprises a binder. The
binder can be a synthetic or naturally occurring (inorganic)
substance, for example clay, silica and/or metal oxides. Natural
occurring clays are for example of the montmorillonite and kaolin
families. The binder is preferably a porous binder material, for
example a refractory oxide of which examples are: alumina,
silica-alumina, silica-magnesia, silica-zirconia, silica-thoria,
silica-beryllia, silica-titania as well as ternary compositions for
example silica-alumina-thoria, silica-alumina-zirconia,
silica-alumina-magnesia and silica-magnesia-zirconia. More
preferably a low acidity refractory oxide binder material, which is
essentially free of alumina, is used. Examples of these binder
materials are silica, zirconia, titanium dioxide, germanium
dioxide, boria and mixtures of two or more of these of which
examples are listed above. The most preferred binder is silica.
[0037] A preferred class of dewaxing catalysts comprise
intermediate zeolite crystallites as described above and a low
acidity refractory oxide binder material which is essentially free
of alumina as described above, wherein the surface of the
aluminosilicate zeolite crystallites has been modified by
subjecting the aluminosilicate zeolite crystallites to a surface
dealumination treatment. A preferred dealumination treatment is by
contacting an extrudate of the binder and the zeolite with an
aqueous solution of a fluorosilicate salt as described in for
example U.S. Pat. No. 5,157,191. Examples of suitable dewaxing
catalysts as described above are silica bound and dealuminated
Pt/ZSM-5, silica bound and dealuminated Pt/ZSM-23, silica bound and
dealuminated Pt/ZSM-12, silica bound and dealuminated Pt/ZSM-22, as
for example described in WO-A-0029511 and EP-B-832171.
[0038] Catalytic dewaxing conditions are known in the art and
typically involve operating temperatures in the range of from 200
to 500.degree. C., suitably from 250 to 400.degree. C., hydrogen
pressures in the range of from 10 to 200 bar, preferably from 40 to
70 bar, weight hourly space velocities (WHSV) in the range of from
0.1 to 10 kg of oil per litre of catalyst per hour (kg/l/hr),
suitably from 0.2 to 5 kg/l/hr, more suitably from 0.5 to 3 kg/l/hr
and hydrogen to oil ratios in the range of from 100 to 2,000 litres
of hydrogen per litre of oil. By varying the temperature between
315 and 375.degree. C. at between 40-70 bars, in the catalytic
dewaxing step it is possible to prepare base oils having different
pour point specifications varying from suitably -10 to below
-60.degree. C.
[0039] After performing a catalytic dewaxing step (d) lower boiling
compounds formed during catalytic dewaxing are removed, preferably
by means of distillation, optionally in combination with an initial
flashing step. The remaining fraction can be further separated into
one or more base oil products, wherein at least one base oil
product is the base oil component having the properties suitable
for the automatic transmission fluid of the present invention.
[0040] The invention will be illustrated by means of the following
non-limiting examples.
EXAMPLE 1
[0041] Example 1 illustrates the process to prepare a base oil
having a higher cyclo-paraffin content.
[0042] A Fischer-Tropsch product was made having boiling curve as
in Table 1 by repeating Example VII of WO-A-9934917 using the
catalyst as prepared in Example III of the same publication and
subsequently removing the C.sub.4 and lower boiling compounds from
the effluent of the synthesis reaction. The feed contained about 60
wt % C.sub.30.sup.+ product. The ratio
C.sub.60.sup.+/C.sub.30.sup.+ was about 0.55.
1 TABLE 1 Temperature Recovered (wt %) (.degree. C.) Initial
boiling 82 point 10 249 30 424 50 553 70 671 90 >750
[0043] The Fischer-Tropsch product as thus obtained was
continuously fed to a hydrocracking step (step (a)). In the
hydrocracking step the Fischer-Tropsch product and a recycle stream
consisting of the 370.degree. C..sup.+ fraction of the effluent of
step (a) was contacted with a hydrocracking catalyst of Example 1
of EP-A-532118 at a reactor temperature of 330.degree. C. The
Fischer-Tropsch product WHSV was contacted at 0.8 kg/l.h and the
recycle stream was contacted at 0.2 kg/l.h at a total pressure of
35 bar and a hydrogen partial pressure of 33 bar. The recycle gas
rate was 2000 Nl/kg of total feed. The conversion of compounds
boiling above 370.degree. C. in the total feed which were converted
to products boiling below 370.degree. C. was 55 wt %. The product
of the hydrocracking step was distilled into one or more fuels
fractions boiling in the naphtha, kerosene and gas oil range and a
bottom product boiling above 370.degree. C.
[0044] The 370.degree. C..sup.+ fraction thus obtained was in turn
distilled in a vacuum distillation column, wherein the feed rate to
the column was 750 g/h, the pressure at the top was kept at 0.4 mm
Hg (0.5 mbar) and the temperature at the top was kept at
240.degree. C., which is equal to an atmospheric cut off
temperature of 515.degree. C. The top product had thus a boiling
range of between 370 and 515.degree. C. Further properties were a
pour point of +18.degree. C. and a kinematic viscosity at
100.degree. C. of 3.8 cSt. This top product was further used as the
base oil precursor fraction in step (c).
[0045] In the dewaxing step (c) the base oil precursor fraction was
contacted with a dealuminated silica bound ZSM-5 catalyst
comprising 0.7% by weight Pt and 30 wt % ZSM-5 as described in
Example 9 of WO-A-0029511. The dewaxing conditions were: total
pressure 40 bar, a hydrogen partial pressure at the reactor outlet
of 36 bar, WHSV=1 kg/l.h, a temperature of 340.degree. C. and a
recycle gas rate of 500 Nl/kg feed.
[0046] The dewaxed oil was distilled, wherein a lighter and a
heavier fraction was removed to obtain the final base oil having
properties as listed in Table 2.
2 TABLE 2 Density d20/4 814 Mean boiling point (50 wt % recovered)
430.degree. C. Kinematic viscosity at 40.degree. C. 18 cSt
Kinematic viscosity at 100.degree. C. 4.0 cSt Viscosity index 121
Pour point -50.degree. C. Noack volatility 11 wt %
EXAMPLE 4-5
[0047] Base oils as prepared from the same feed as in Examples 1
and 2 under varying conditions were prepared. Properties are listed
in Table 3. The cyclo-paraffins and normal and iso-paraffins of the
base oil of Example 5 (see Table 3) were further analysed. In FIG.
1 the content of the components, normal and iso-paraffins, 1-ring
cyclo-paraffins, 2-ring cyclo-paraffins, etc. in the saturates
phase as a function of their respective carbon numbers are shown of
the base oil of Example 5.
3TABLE 3 Base oil as Base oil as obtained by obtained by catalytic
catalytic dewaxing a dewaxing a Shell MDS Shell MDS Base oil as
Waxy Raffinate Waxy Raffinate obtained in over a over a Example 2
Pt/synthetic Pt/synthetic of EP-A- ferrierite ferrierite Base oil
type Example 4 Example 5 776959 catalyst (*) catalyst (**)
Viscosity Index 127 121 151 138 132 Pour point (.degree. C.) -48
-54 -19 -21 -39 Kinematic 4.77 4.14 4.80 4.91 4.96 viscosity at
100.degree. C. (cSt) Dynamic 5500 3900 6800 5300 5700 viscosity as
measured by CCS at -40.degree. C. (cP) Saturates 99.1 99.9 99.8
99.7 99.6 content (wt %) Total cyclo- 13.7 18.5 4.1 6.1 8.2
paraffin content 1-ring cyclo- 11.1 16.8 3.7 4.9 6.4 paraffins (wt
%) 2-ring cyclo- 1.4 1.4 0.2 0.5 0.7 paraffins 3 and higher 1.2 0.3
0.2 0.7 1.1 number rings cyclo-paraffins (*) Reaction conditions:
total pressure 40 bars, WHSV = 1 kg/l/h, gas recycle rate = 700
Nl/kg feed and temperature of 290.degree. C. (**) as in (*) but at
320.degree. C. dewaxing temperature.
EXAMPLE 6
[0048] A base oil having the properties as in Table 4 and as
prepared according to Example 1 using the same Fischer-Tropsch
product but at slightly different catalytic dewaxing conditions was
formulated with 5 wt % Lubad 924 and 6 wt % of Viscoplex 12-410 to
arrive at an Automatic Transmission Fluid (ATF) having the
properties as described in Table 5. A minor portion of a second
mineral based base oil was added to adjust the base oil kinematic
viscosity at 100.degree. C. to 4.03 cSt.
4 TABLE 4 Specific Gravity kg/m.sup.3 818.5 Flashpoint COC .degree.
C. 232 Pour point .degree. C. -48 Viscosity at 40.degree. C.
mm.sup.2/s 20.08 Viscosity at 100.degree. C. mm.sup.2/s 4.30
Viscosity Index 122 Brookfield Viscosity at - 20.degree. C. mPa s
550 at - 30.degree. C. mPa s 1.320 Cyclic-paraffin content wt %
12.2 Aromatics content wt % 0.8
Comparative Experiment A
[0049] An automatic transmission fluid was formulated using the
same additive package as used in Example 4, wherein the base oil
component was a blend of 50 wt % Shell XHVI 5.2, 12 wt % MVIN40 (as
obtainable from Shell Europe Oil Products) and HVI-50 (as
obtainable from Shell Europe Oil Products) balance having a base
oil viscosity of 4.03 mm.sup.2/s at 100.degree. C. The properties
of the resulting formulation are presented in Table 5.
Comparative Experiment B
[0050] An automatic transmission fluid was formulated using the
same additive package as used in Example 4, wherein the base oil
component was a blend of Nexbase 3030 and Nexbase 3043 (as
obtainable from Fortum Base Oils, Porvoo, Finland) such that the
base had a oil viscosity of 4.03 mm.sup.2/s at 100.degree. C.
Nexbase is a base oil prepared by a severe hydro-cracking of vacuum
gas oil. The properties of the resulting formulation are presented
in Table 5.
Comparative Experiment C
[0051] An automatic transmission fluid was formulated using the
same additive package as used in Example 4, wherein the base oil
component was a blend of poly-alpha olefin grade 4 and poly alpha
olefin grade 6 (as obtained from Chevron) having a base oil
viscosity of 4.03 mm.sup.2/s at 100.degree. C. The properties of
the resulting formulation are presented in Table 5.
5 TABLE 5 Example 6 A B C Base Oil mm.sup.2/s 4.02 4.03 4.03 4.03
kinematic viscosity at 100.degree. C. ATF mm.sup.2/s 6.84 7.2 7.02
6.85 kinematic viscosity at 100.degree. C. ATF mPa s 5930 14000
7860 4800 Dynamic viscosity at -40.degree. C.
[0052] The above table 5 shows that in Example 6 an ATF formulation
was prepared which had a combination of a low kinematic viscosity
at 100.degree. C. and a low dynamic viscosity at -40.degree. C.
comparable to when a poly-alpha olefin base oil is used
(Comparative experiment C). The advantage of using the specific
base oil having the high cyclic-paraffin content and the other
properties as herein described over a PAO base oil is the better
solvency properties of the base oil of Example 6.
[0053] The results of Example 6 are expected to be even better if
the base oil would not have been blended with a mineral base oil,
but instead would have been 100% Fischer-Tropsch derived base oil,
such as the base oil as prepared in Example 1.
* * * * *