U.S. patent application number 11/717343 was filed with the patent office on 2007-10-04 for soot control for diesel engine lubricants.
Invention is credited to Jason Z. Gao, Heather M. Haigh, Brandon T. Weldon.
Application Number | 20070232503 11/717343 |
Document ID | / |
Family ID | 38511396 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070232503 |
Kind Code |
A1 |
Haigh; Heather M. ; et
al. |
October 4, 2007 |
Soot control for diesel engine lubricants
Abstract
The present invention is directed to a method for controlling
soot induced viscosity increase in diesel engines, by using as the
diesel engine lubricant an oil formulation comprising a base oil
containing about 10 to 80 wt % GTL base stock and/or base oil
and/or hydrodewaxed or hydroisomerized/catalytic (or solvent)
dewaxed base stock and/or base oil in combination with 20 to 90 wt
% conventional Group I petroleum derived base oil, said base oil
being further combined with a polymeric viscosity modifier, and to
the lubricating oil which effects such control over soot induced
viscosity increase.
Inventors: |
Haigh; Heather M.;
(Philadelphia, PA) ; Weldon; Brandon T.; (Cherry
Hill, NJ) ; Gao; Jason Z.; (Rose Valley, PA) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
38511396 |
Appl. No.: |
11/717343 |
Filed: |
March 13, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60788213 |
Mar 31, 2006 |
|
|
|
Current U.S.
Class: |
508/192 |
Current CPC
Class: |
C10N 2030/041 20200501;
C10M 169/041 20130101; C10M 111/02 20130101; C10N 2030/04 20130101;
C10M 2203/1006 20130101; C10M 111/04 20130101; C10M 2205/173
20130101; C10M 2201/041 20130101; C10N 2030/02 20130101; C10M
169/04 20130101 |
Class at
Publication: |
508/192 |
International
Class: |
C10L 1/22 20060101
C10L001/22 |
Claims
1. A method for controlling the soot induced viscosity increase of
conventional/mineral oil derived base stock or base oil lubricating
oils used in diesel engines during use by adding to the lubricating
oil about 10 to 80 wt % of a GTL base stock and/or base oil and/or
hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base
stock or base oil, based on the weight of the total base oil.
2. A method for controlling the soot induced viscosity increase of
lubricating oils used in diesel engines during use by employing as
the diesel engine lubricating oil an oil formulation comprising a
base stock or base oil containing about 10 to 80 wt % of a GTL base
stock and/or base oil and/or hydrodewaxed or
hydroisomerized/catalytic (or solvent) dewaxed base stock and/or
base oil in combination with about 90 to 20 wt % of a conventional
petroleum/mineral oil derived base stock, based on the weight of
the total base oil.
3. The method of claim 1 or 2 wherein the amount of GTL base stock
and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic
(or solvent) dewaxed base stock and/or base oil is in the range of
about 10 to 70 wt % based on the weight of the total base oil.
4. The method of claim 1 or 2 wherein the conventional
petroleum/mineral oil derived base stock is a Group I and/or Group
II base stock.
5. The method of claim 4 wherein the conventional petroleum/mineral
oil derived base stock is a Group I base stock.
6. The method of claim 1 or 2 wherein the GTL base stock and/or
base oil and/or hydrodewaxed or hydroisomerized/catalytic (or
solvent) dewaxed base stock and/or base oil has a kinematic
viscosity at 100.degree. C. in the range of about 2 to 50
mm.sup.2/s.
7. The method of claim 1 or 2 wherein the GTL base stock and/or
base oil and/or hydrodewaxed or hydroisomerized/catalytic (or
solvent) dewaxed base stock and/or base oil has a kinematic
viscosity at 100.degree. C. in the range of about 3 to 40
mm.sup.2/s.
8. The method of claim 1 or 2 wherein the GTL base stock and/or
base oil and/or hydrodewaxed or hydroisomerized/catalytic (or
solvent) dewaxed base stock and/or base oil has a kinematic
viscosity at 100.degree. C. in the range of about 3.5 to 30
mm.sup.2/s.
9. The method of claim 2 wherein the conventional petroleum/mineral
oil derived base stock has a kinematic viscosity at 100.degree. C.
in the range of about 2 to 20 mm.sup.2/s.
10. The method of claim 4 wherein the conventional
petroleum/mineral oil derived base stock has a kinematic viscosity
at 100.degree. C. in the range of about 4 to 10 mm.sup.2/s.
11. The method of claim 5 wherein the conventional
petroleum/mineral oil derived base stock has a kinematic viscosity
at 100.degree. C. in the range of about 4 to 8 mm.sup.2/s.
12. The method of claim 1 or 2 wherein the GTL base stock and/or
base oil and/or hydrodewaxed or hydroisomerized/catalytic (or
solvent) dewaxed base stock and/or base oil has a kinematic
viscosity at 100.degree. C. in the range of about 3.5 to 30
mm.sup.2/s and the conventional petroleum/mineral oil derived stock
is a Group I and/or Group II stock which has a kinematic viscosity
at 100.degree. C. in the range of about 4 to 8 mm.sup.2/s.
13. A diesel engine lubricating oil formulation resistant to soot
induced viscosity increase during use comprising a base oil
containing about 10 to 80 wt % GTL base stock and/or base oil
and/or hydrodewaxed or hydroisomerized/catalytic (or solvent)
dewaxed base stock and/or base oil, about 90 to 20 wt % of a
conventional petroleum/mineral oil derived base oil, based on the
weight of the total base oil and about 1 to 25 wt % on an as
received basis of a polymeric viscosity modifying additive, based
on the total weight of the lubricating oil formulation.
14. The diesel engine lubricating oil formulation of claim 13
wherein the GTL base stock and/or base oil and/or hydrodewaxed or
hydroisomerized/catalytic (or solvent) dewaxed base stock and/or
base oil comprises about 10 to 70 wt % of the total base oil.
15. The diesel engine lubricating oil formulation of claim 13
wherein the GTL base stock and/or base oil and/or hydrodewaxed or
hydroisomerized/catalytic (or solvent) dewaxed base stock and/or
base oil comprises about 10 to 60 wt % of the total base oil.
16. The diesel engine lubricating oil formulation of claim 13, 14
or 15 wherein the conventional petroleum/mineral oil derived base
oil is a Group I and/or Group II base oil.
17. The diesel engine lubricating oil formulation of claim 16
wherein the base oil is a Group I base oil.
18. The diesel engine lubricating oil formulation of claim 13, 14
or 15 wherein the polymeric viscosity modifying additive is present
in an amount in the range of about 5 to 25 wt % on an as received
base, based on the total weight of the lubricating oil formulation.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/788,213 filed Mar. 31, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to diesel engine lubricating
oils and to the control of soot induced viscosity increase of the
lubricating used in such engines.
[0004] 2. Description of the Related Art
[0005] Internal combustion engines function by the combustion of
fuels which in turn generate the power needed to propel vehicles.
In the case of a diesel engine, the fuel is a diesel fuel and the
combustion thereof generally results in emissions from the exhausts
of such vehicles which comprise three main components. These are:
soot and particulate matter, carbon monoxide and nitrogen oxides
(the latter will hereafter be abbreviated as NOx for convenience).
To alleviate environmental concerns, research is ongoing to reduce
the levels of these emissions. NOx emission can be reduced by
lowering the temperature at which the fuel is combusted in the
engine. Typically this is achieved by retarding the combustion,
i.e., by injecting the fuel shortly after the peak temperature is
reached in the cylinder. However, this retarded combustion has the
disadvantage that it causes more soot to accumulate in the engine
lubricant partly due to incomplete combustion of the fuel because
of the lower combustion temperature, and partly due to increased
soot deposition on the cylinder wall which is drawn down into the
lubricant with the downward stroke of the piston. The presence of
soot in the lubricant has the adverse affects of causing viscosity
increase and accelerated wear. It is important that soot induced
viscosity increase be controlled such that the lubricant stays
within viscosity grade in order to maintain its expected
performance and to enable quick and clean drainage of the engine
during servicing.
[0006] The formation of soot may be alleviated to a significant
extent by operating the diesel engine at relatively higher
temperatures. However, the higher temperatures whilst mitigating
the formation of soot also result in the formation of increased
amounts of NOx. If, however, the engine temperature is lowered,
incomplete combustion ensues and whilst this reduces the amount of
NOx formed in the emissions, it also substantially increases the
amount of soot generated. The soot so formed can manifest itself in
two ways. It can either appear as a thick black smoke emitted from
the exhaust of the vehicle or can be accumulated in the engine
lubricant. As the soot builds up in the lubricant, the latter
becomes more and more viscous and upon reaching a critical value
can cause gelation of the lubricant and may eventually cause
seizure of the engine.
[0007] Several methods have been put forward to alleviate this
problem including the use of one or more of dispersants, metal
salts and solvents which may be ethers, esters and the like. The
dispersants function by forming a coating of the dispersant on the
surface of soot particles and thereby minimizing the tendency of
the soot particles to agglomerate. However, the potency of the
dispersants to perform this function, in turn, declines with time
and thus, one of the methods of improving the useful life of
lubricants, particularly crankcase lubricants, would be to improve
the dispersancy retention capability of crankcase lubricants. This
may be achieved, e.g., by minimizing the risk of oxidation of the
dispersants under the conditions prevalent in the engines during
use. One such method is described in U.S. Pat. No. 5,837,657 which
discloses a method of improving the performance of a sooted diesel
oil and controlling soot induced viscosity increase by adding to
the diesel oil a minor amount of a trinuclear molybdenum compound
of the generic formula MO.sub.3S.sub.kL.sub.nQ.sub.z wherein L is a
ligand having organo groups, n is from 1 to 4, k various from 4
through 10, Q is a neutral electron donating compound such as,
e.g., water, amines, alcohols, phosphines and ethers, and z ranges
from 0 to 5.
[0008] Hydrocarbon base oils have differing solvency
characteristics that affect their capability to solubilize
performance additives. Highly paraffinic hydrocarbon base oils
(those having low levels of aromaticity) are known to have
low-to-poor additive solubility characteristics. For example, such
low-solvency hydrocarbon base oils include polyalpha olefins (PAO)
which are 100% isoparaffinic and have essentially 0% aromatics
content. Similarly, wax isomerate base oils, in particular
hydroisomerized Fischer-Tropsch (F-T) waxes, often called
Gas-to-Liquids (GTL) lubricant base oils, are very highly
paraffinic and have essentially 0% aromatics content. The base
stock is derived from a waxy, F-T synthesized hydrocarbon feed
fraction comprising hydrocarbons having an initial b.p. in the
range of approximately 650-750.degree. F., by a process which
comprises hydroisomerizing the feed and optionally dewaxing the
isomerate. The lubricant also contains hydrocarbonaceous and
synthetic base stock material in mixture with the F-T derived base
stock. Consequently, such wax isomerate base oils would be expected
to have low solvency and poor additive solubility performance.
[0009] High isoparaffinic base stocks, however, are advantageous in
soot control for diesel engine lubricants. Lower soot-induced
viscosity increase and lower soot-induced wear are observed for
diesel engine lubricants with higher saturate contents. In
addition, GTL base oils are essentially sulfur-free, which is
highly desirable for the next generation engine lubricants such as
GF-5 and PC-10. In these new engine lubricant categories, a maximum
sulfur level is defined for improved compatibility with new low
emission engines equipped with aftertreatment devices.
[0010] It would be advantageous if a way could be found to reduce
the soot induced viscosity increase experienced in diesel engine
lubricating oils during use while not negatively affecting the
desired viscosity modifying effect of polymeric viscosity modifier
which are normally added to diesel engine lubricating oils without
the need of employing cosolvents.
DESCRIPTION OF THE FIGURES
[0011] FIG. 1 shows the relationship between % viscosity increase
due to soot and the GTL content of the base oil.
[0012] FIG. 2 shows the relationship between thickening ability
attributable to Viscosity Modifier and the GTL content of the base
oil.
[0013] FIG. 3 shows the interrelationship between % viscosity
increase due to soot and the thickening ability attributable to the
viscosity modifier at different GTL levels in the base oil.
DESCRIPTION OF THE INVENTION
[0014] The present invention is directed to a method for
controlling the soot induced viscosity increase of
conventional/mineral oil derived base oil lubricating oil used in
diesel engines while not adversely affecting the viscosity
modifying effect of viscosity improver added to diesel engine
lubricating oils.
[0015] It has been discovered that the soot induced viscosity
increase of diesel engine conventional petroleum/mineral oil
derived base stock or base oil lubricating oils can be controlled
in the diesel engine by adding to the diesel engine lubricant
comprising a conventional petroleum/mineral oil derived base stock
or base oil about 10 to 80 wt %, preferably about 10 to 70 wt %,
more preferably about 20 to 60 wt % of a GTL base stock and/or base
oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent)
dewaxed base stock or base oil based on the total base oil. The
soot induced viscosity increase of diesel engine lubricating engine
oils during use can be controlled by employing as the diesel engine
lubricating oil a formulation comprising a base stock or base oil
containing about 10 to 80 wt %, preferably about 10 to 70 wt %,
more preferably about 20 to 60 wt % of a GTL base stock and/or base
oil and/or hydrodewaxed or hydroisomerizad/catalytic (or solvent)
dewaxed base stock and/or base oil in combination with about 90 to
20 wt %, preferably about 90 to 30 wt %, more preferably about 90
to 40 wt % of a conventional petroleum/mineral oil derived base
stock or base oil based on the weight of the total base oil.
[0016] It has been discovered that the addition of the GTL base
stock(s) and/or base oil(s) and/or hydrodewaxed or
hydroisomerized/catalytic (or solvent) dewaxed base stock(s) or
base oil(s) in the amount indicated to the conventional
petroleum/mineral oil derived base stock(s) or base oil(s) results
in a base oil which exhibits both the ability to control soot
induced viscosity increase while not adversely affecting the
desirable viscosity modifying effect of polymeric viscosity
modifiers which are deliberately added to the diesel engine
lubricating oil formulation.
[0017] Thus the present invention is directed to a method for
controlling soot is induced viscosity increase in diesel engine
lubricating oil during use by using as the diesel engine lubricant
an oil formulation comprising a base stock or base oil containing
about 10 to 80 wt %, preferably about 10 to 70 wt %, more
preferably about 10 to 60 wt % of one or more GTL base stock(s)
and/or base oil(s) and/or hydrodewaxed or hydroisomerized/catalytic
(or solvent) dewaxed base stock(s) or base oil(s), preferably GTL
base stock in combination with about 90 to 20 wt %, preferably
about 90 to 30 wt %, more preferably about 90 to 40 wt % of a
conventional, petroleum/mineral oil derived base stock or base
oil.
[0018] The GTL base stock(s) and/or base oil(s) and/or hydrodewaxed
or hydroisomerizaed/catalytic (or solvent) dewaxed base stock(s)
and/or base oil(s) is (are) characterized as having a kinematic
viscosity at 100.degree. C. in the range of about 2 to 50
mm.sup.2/s, preferably about 3 to 40 mm.sup.2/s, more preferably
about 3.5 to 30 mm.sup.2/s.
[0019] The conventional petroleum/mineral oil derived base stock or
base oil is preferably a Group I and/or Group II base stock, more
preferably Group I base stock. Groups I and II are broad categories
of base oil stocks developed and defined by the American Petroleum
Institute (API Publication 1509; www.API.org) to create guidelines
for lubricant base oils Group I base stocks generally have a
viscosity index of between about 80 to 120 and contain greater than
about 0.03 wt % sulfur and less than about 90 wt % saturates, Group
II base stocks generally have a viscosity index of between about 80
to 120 and contain less than or equal to about 0.03 wt % sulfur and
grater than or equal to about 90 wt % saturates. The
conventional/mineral oil derived base stock or base oil used in the
present invention has a kinematic viscosity at 100.degree. C. in
the range of about 2 to 20 mm.sup.2/s, preferably about 4 to 10
mm.sup.2/s, more preferably about 4 to 8 mm.sup.2/s. The blend of
the GTL base stock(s) and/or base oil(s) and/or hydrodewaxed or
hydroisomerized/catalytic (or solvent) dewaxed base stock(s) or
base oil(s) with the conventional petroleum/mineral oil derived
base stock or base oil preferably exhibits an unadditized kinematic
viscosity at 100.degree. C. in the range of about 4 to 12
mm.sup.2/s, preferably 4 to 10 mm.sup.2/s, more preferably 4 to 8
mm.sup.2/s while the fully formulated lubricating oil composition
made using the base oil exhibits a kinematic viscosity at
100.degree. C. in the range of about 6 to 14 mm.sup.2/s.
[0020] The present invention is also directed to a diesel engine
lubricating oil formulation comprising a base oil containing about
10 to 80 wt %, preferably about 10 to 70 wt %, more preferably
about 10 to 60 wt % of one or more GTL base stock(s) and/or base
oil(s) and/or hydrodewaxed or hydroisomerized/catalytic (or
solvent) dewaxed base stock(s) and/or base oil(s) in combination
with about 90 to 20 wt %, preferably about 90 to 30 wt %, more
preferably about 90 to 40 wt % of a conventional, petroleum/mineral
oil derived base stock or base oil, preferably a Group I and/or
Group II base stock and a polymeric viscosity modifying additive in
an amount in the range of about 1 to 25 wt % on an as received
basis, preferably about 5 to 25 wt % on an as received basis based
on the total weight of the formulated diesel engine lubricating oil
composition.
[0021] Viscosity modifiers (also known as VI improvers and
viscosity index improvers) provide lubricants with high and low
temperature operability. These additives impart shear stability at
elevated temperatures and acceptable viscosity at low
temperatures.
[0022] Suitable viscosity index improvers include high molecular
weight (polymeric) hydrocarbons, polyesters and viscosity index
improver dispersants that function as both a viscosity index
improver and a dispersant. Typical molecular weights of these
polymers are between about 10,000 to 1,000,000, more typically
about 20,000 to 500,000, and even more typically between about
50,000 and 200,000.
[0023] Examples of suitable viscosity index improvers are polymers
and copolymers of methacrylate, butadiene, olefins, or alkylated
styrenes. A suitable viscosity index improver is polymethacrylate
(copolymers of various chain length alkyl methacrylates, for
example), some formulations of which also serve as pour point
depressants. Polyisobutylene is another example of a suitable
viscosity index improver. Other suitable viscosity index improvers
include copolymers of ethylene and propylene, hydrogenated block
copolymers of styrene and isoprene, or styrene and butadiene, and
polyacrylates (copolymers of various chain length acrylates, for
example). Specific examples include olefin copolymer and
styrene-hydrogenated isoprene copolymer of 50,000 to 200,000
molecular weight.
[0024] As previously indicated, viscosity modifiers are used in an
amount of about 1 to 25 wt % on an as received basis, preferably
about 5 to 25 wt % on an as-received basis.
[0025] Because viscosity modifiers are usually supplied diluted in
a carrier or diluent oil and constitute anywhere from about 5 to 50
wt % active ingredient in the additive concentrates as received
from the manufacturer, the amount of viscosity modifiers used in
the formulation on an active ingredient basis can also be expressed
as being in the range of about 0.20 to about 4.0 wt % active
ingredient, preferably about 0.3 to 2.5 wt % active ingredient. For
olefin copolymer and styrene-hydrogenated isoprene copolymer
viscosity modifier, the active ingredient is in the range of about
5 to 15 wt % in the additive concentrates from the manufacturer,
the amount of these viscosity modifiers used in the formulation can
also be expressed as being in the range of about 0.20 to 1.9 wt %
active ingredient, preferably about 0.3 to 1.5 wt % active
ingredient.
[0026] Preferably the conventional, petroleum/mineral oil derived
Group I base stock or base oil has a sulfur content of about 0.2 wt
% sulfur or base, more preferably about 0.15 wt % sulfur or less,
even more preferably about 0.1 wt % sulfur or less.
[0027] The GTL base stock(s) and/or base oil(s) and/or hydrodewaxed
or hydroisomerized/catalytic (or solvent) dewaxed base stock(s)
and/or base oil(s) useful in the present invention include one or
more or a mixture of base stock(s) and/or base oil(s) derived from
one or more Gas-to-Liquids (GTL) materials, as well as
hydrodewaxed, or hydroisomerized/conventional cat (or solvent)
dewaxed base stock(s) and/or base oils derived from natural wax or
waxy feeds, mineral and or non-mineral oil waxy feed stocks such as
slack waxes, natural waxes, and waxy stocks such as gas oils, waxy
fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal
crackates, or other mineral, mineral oil, or even non-petroleum oil
derived waxy materials such as waxy materials received from coal
liquefaction or shale oil, and mixtures of such base stocks and/or
base oils.
[0028] As used herein, the following terms have the indicated
meanings: [0029] a) "wax"--hydrocarbonaceous material having a high
pour point, typically existing as a solid at room temperature,
i.e., at a temperature in the range from about 15.degree. C. to
25.degree. C., and consisting predominantly of paraffinic
materials; [0030] b) "paraffinic" material: any saturated
hydrocarbons, such as alkanes. Paraffinic materials may include
linear alkanes, branched alkanes (iso-paraffins), cycloalkanes
(cycloparaffins; mono-ring and/or multi-ring), and branched
cycloalkanes; [0031] c) "hydroprocessing": a refining process in
which a feedstock is heated with hydrogen at high temperature and
under pressure, commonly in the presence of a catalyst, to remove
and/or convert less desirable components and to produce an improved
product; [0032] d) "hydrotreating": a catalytic hydrogenation
process that converts sulfur- and/or nitrogen-containing
hydrocarbons into hydrocarbon products with reduced sulfur and/or
nitrogen content, and which generates hydrogen sulfide and/or
ammonia (respectively) as byproducts; similarly, oxygen containing
hydrocarbons can also be reduced to hydrocarbons and water; [0033]
e) "catalytic dewaxing": a conventional catalytic process in which
normal paraffins (wax) and/or waxy hydrocarbons, e.g., slightly
branched iso-paraffins, are converted by cracking/fragmentation
into lower molecular weight species to insure that the final oil
product (base stock or base oil) has the desired product pour
point; [0034] f) "hydroisomerization" (or isomerization): a
catalytic process in which normal paraffins (wax) and/or slightly
branched iso-paraffins are converted by rearrangement/isomerization
into branched or more branched iso-paraffins (the isomerate from
such a process possibly requiring a subsequent additional wax
removal step to ensure that the final oil product (base stock or
base oil) has the desired product pour point); [0035] g)
"hydrocracking": a catalytic process in which hydrogenation
accompanies the cracking/fragmentation of hydrocarbons, e.g.,
converting heavier hydrocarbons into lighter hydrocarbons, or
converting aromatics and/or cycloparaffins (naphthenes) into
non-cyclic branched paraffins. [0036] h) "hydrodewaxing": (e.g.,
ISODEWAXING.RTM. of Chevron or MSDW.TM. of Exxon Mobil corporation)
a very selective catalytic process which in a single step or by use
of a single catalyst or catalyst mixture effects conversion of wax
by isomerization/rearrangement of the n-paraffins and slightly
branched isoparaffins into more heavily branched isoparaffins, the
resulting product not requiring a separate conventional catalytic
or solvent dewaxing step to meet the desired product pour point;
[0037] i) the terms "hydroisomerate", "isomerate", "catalytic
dewaxate", and "hydrodewaxate" refer to the products produced by
the respective processes, unless otherwise specifically indicated;
[0038] j) "base stock" is a single oil secured from a single feed
stock source and subjected to a single processing scheme and
meeting a particular specification; [0039] k) "base oil" is a
mixture of base stocks.
[0040] Thus the term "hydroisomerization/cat dewaxing" is used to
refer to catalytic processes which have the combined effect of
converting normal paraffins and/or waxy hydrocarbons by
rearrangement/isomerization, into more branched iso-paraffins,
followed by (1) catalytic dewaxing to reduce the amount of any
residual n-paraffins or slightly branched iso-paraffins present in
the isomerate by cracking/fragmentation or by (2) hydrodewaxing to
effect further isomerization and very selective catalytic dewaxing
of the isomerate, to reduce the product pour point. When the term
"(or solvent)", is included in the recitation, the process
described involves hydroisomerization followed by solvent dewaxing
which effects the physical separation of wax from the
hydroisomerate so as to reduce the product pour point.
[0041] GTL materials are materials that are derived via one or more
synthesis, combination, transformation, rearrangement, and/or
degradation/deconstructive processes from gaseous carbon-containing
compounds, hydrogen-containing compounds, and/or elements as
feedstocks such as hydrogen, carbon dioxide, carbon monoxide,
water, methane, ethane, ethylene, acetylene, propane, propylene,
propyne, butane, butylenes, and butynes. GTL base stocks and/or
base oils are GTL materials of lubricating viscosity that are
generally derived from hydrocarbons, for example waxy synthesized
hydrocarbons, that are themselves derived from simpler gaseous
carbon-containing compounds, hydrogen-containing compounds and/or
elements as feedstocks. GTL base stock(s) and/or base oil(s)
include oils boiling in the lube oil boiling range
separated/fractionated from synthesized GTL materials such as for
example, by distillation and subsequently a final wax processing
step which is either the well-known catalytic dewaxing process, or
solvent dewaxing process, to produce lube oils of reduced/low pour
point; synthesized wax isomerates, comprising, for example,
hydrodewaxed, or hydroisomerized/cat (or solvent) dewaxed
synthesized waxy hydrocarbons; hydrodewaxed, or hydroisomerized/cat
(or solvent) dewaxed Fischer-Tropsch (F-T) material (i.e.,
hydrocarbons, waxy hydrocarbons, waxes and possible analogous
oxygenates); preferably hydrodewaxed, or hydroisomerized/cat (or
solvent) dewaxed F-T hydrocarbons, or hydrodewaxed or
hydroisomerized/cat (or solvent) dewaxed, F-T waxes, hydrodewaxed,
or hydroisomerized/cat (or solvent) dewaxed synthesized waxes, or
mixtures thereof.
[0042] GTL base stock(s) and/or base oil(s) derived from GTL
materials, especially, hydrodewaxed, or hydroisomerized/cat (or
solvent) dewaxed F-T material derived base stock(s) and/or base
oil(s), and other hydrodewaxed, or hydroisomerized/cat (or solvent)
dewaxed wax derived base stock(s) and/or base oil(s) are
characterized typically as having kinematic viscosities at
100.degree. C. of from about 2 mm.sup.2/s to about 50 mm.sup.2/s,
preferably from about 3 mm.sup.2/s to about 50 mm.sup.2/s, more
preferably from about 3.5 mm.sup.2/s to about 30 mm.sup.2/s, as
exemplified by a GTL base stock derived by the hydrodewaxing or
hydroisomerization catalytic (or solvent) dewaxing of F-T wax,
which has a kinematic viscosity of about 4 mm.sup.2/s at
100.degree. C. and a viscosity index of about 130 or greater.
Preferably the wax treatment process is hydrodewaxing carried out
in a process using a single hydrodewaxing catalyst. Reference
herein to Kinematic viscosity refers to a measurement made by ASTM
method D445.
[0043] GTL base stock(s) and/or base oil(s) derived from GTL
materials, especially hydrodewaxed, or hydroisomerized/cat (or
solvent) dewaxed F-T material derived base stock(s) and/or base
oil(s), and other hydrodewaxed, or hydroisomerized/cat (or solvent)
dewaxed wax-derived base stock(s) and/or base oil(s), which can be
used as base stock and/or base oil components of this invention are
further characterized typically as having pour points of about
-5.degree. C. or lower, preferably about -10.degree. C. or lower,
more preferably about -15.degree. C. or lower, still more
preferably about -20.degree. C. or lower, and under some conditions
may have advantageous pour points of about -25.degree. C. or lower,
with useful pour points of about -30.degree. C. to about
-40.degree. C. or lower. If necessary, a separate dewaxing step may
be practiced to achieve the desired pour point. References herein
to pour point refer to measurement made by ASTM D97 and similar
automated versions.
[0044] The GTL base stock(s) and/or base oil(s) derived from GTL
materials, especially hydrodewaxed or hydroisomerized/cat (or
solvent) dewaxed F-T material derived base stock(s) and/or base
oil(s), and other such wax-derived base stock(s) and/or base oil(s)
which can be used in this invention are also characterized
typically as having viscosity indices of 80 or greater, preferably
100 or greater, and more preferably 120 or greater. Additionally,
in certain particular instances, the viscosity index of these base
stocks and/or base oil(s) may be preferably 130 or greater, more
preferably 135 or greater, and even more preferably 140 or greater.
For example, GTL base stock(s) and/or base oil(s) that derive from
GTL materials preferably F-T materials especially F-T wax generally
have a viscosity index of 130 or greater. References herein to
viscosity index refer to ASTM method D2270.
[0045] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins multicycloparaffins in combination
with non-cyclic isoparaffins. The ratio of the naphthenic (i.e.,
cycloparaffin) content in such combinations varies with the
catalyst and temperature used. Further, GTL base stock(s) and/or
base oil(s) typically have very low sulfur and nitrogen content,
generally containing less than about 10 ppm, and more typically
less than about 5 ppm of each of these elements. The sulfur and
nitrogen content of GTL base stock(s) and/or base oil(s) obtained
by the hydroisomerization/isodewaxing of F-T material, especially
F-T wax, is essentially nil.
[0046] In a preferred embodiment, the GTL base stock(s) and/or base
oil(s) comprises paraffinic materials that consist predominantly of
non-cyclic isoparaffins and only minor amounts of cycloparaffins.
These GTL base stock(s) and/or base oil(s) typically comprise
paraffinic materials that consist of greater than 60 wt %
non-cyclic isoparaffins, preferably greater than 80 wt % non-cyclic
isoparaffins, more preferably greater than 85 wt % non-cyclic
isoparaffins, and most preferably greater than 90 wt % non-cyclic
isoparaffins.
[0047] Useful compositions of GTL base stock(s) and/or base oil(s),
hydrodewaxed or hydroisomerized/cat (or solvent) dewaxed F-T
material derived base stock(s), and wax-derived hydrodewaxed, or
hydroisomerized/cat (or solvent) dewaxed base stock(s), such as wax
isomerates or hydrodewaxates, are recited in U.S. Pat. Nos.
6,080,301; 6,090,989, and 6,165,949 for example.
[0048] Base stock(s) and/or base oil(s) derived from waxy feeds,
which are also suitable for use in this invention, are paraffinic
fluids of lubricating viscosity derived from hydrodewaxed, or
hydroisomerized/cat (or solvent) dewaxed waxy feedstocks of mineral
oil, non-mineral oil, non-petroleum, or natural source origin,
e.g., feedstocks such as one or more of gas oils, slack wax, waxy
fuels hydrocracker bottoms, hydrocarbon raffinates, natural waxes,
hyrocrackates, thermal crackates, foots oil, wax from coal
liquefaction or from shale oil, or other suitable mineral oil,
non-mineral oil, non-petroleum, or natural source derived waxy
materials, linear or branched hydrocarbyl compounds with carbon
number of about 20 or greater, preferably about 30 or greater, and
mixtures of such isomerate/isodewaxate base stock(s) and/or base
oil(s).
[0049] Slack wax is the wax recovered from any waxy hydrocarbon oil
including synthetic oil such as F-T waxy oil or petroleum oils by
solvent or autorefrigerative dewaxing. Solvent dewaxing employs
chilled solvent such as methyl ethyl ketone (MEK), methyl isobutyl
ketone (MIBK), mixtures of MEK/MIBK, mixtures of MEK and toluene,
while autorefrigerative dewaxing employs pressurized, liquefied low
boiling hydrocarbons such as propane or butane.
[0050] Slack wax(es) secured from synthetic waxy oils such as F-T
waxy oil will usually have zero or nil sulfur and/or nitrogen
containing compound content. Slack wax(es) secured from petroleum
oils, may contain sulfur and nitrogen containing compounds. Such
heteroatom compounds must be removed by hydrotreating (and not
hydrocracking), as for example by hydrodesulfurization (HDS) and
hydrodenitrogenation (HDN) so as to avoid subsequent
poisoning/deactivation of the hydroisomerization catalyst.
[0051] The term GTL base stock and/or base oil and/or wax isomerate
base stock and/or base oil as used herein and in the claims is to
be understood as embracing individual fractions of GTL base stock
and/or base oil and/or of wax-derived hydrodewaxed or
hydroisomerized/cat (or solvent) dewaxed base stock and/or base oil
as recovered in the production process, mixtures of two or more GTL
base stock and/or base oil fractions and/or wax-derived
hydrodewaxed, or hydroisomerized/cat (or solvent) dewaxed base
stocks/base oil fractions, as well as mixtures of one or two or
more low viscosity GTL base stock and/or base oil fraction(s)
and/or wax-derived hydrodewaxed, or hydroisomerized/cat (or
solvent) dewaxed base stock and/or base oil fraction(s) with one,
two or more higher viscosity GTL base stock and/or base oil
fraction(s) and/or wax-derived hydrodewaxed, or hydroisomerized/cat
(or solvent) dewaxed base stock and/or base oil fraction(s) to
produce a dumbbell blend wherein the blend exhibits a kinematic
viscosity within the aforesaid recited range.
[0052] In a preferred embodiment, the GTL material, from which the
GTL base stock(s) and/or base oil(s) is/are derived is an F-T
material (i.e., hydrocarbons, waxy hydrocarbons, wax). A slurry F-T
synthesis process may be beneficially used for synthesizing the
feed from CO and hydrogen and particularly one employing an F-T
catalyst comprising a catalytic cobalt component to provide a high
Schultz-Flory kinetic alpha for producing the more desirable higher
molecular weight paraffins. This process is also well known to
those skilled in the art.
[0053] In an F-T synthesis process, a synthesis gas comprising a
mixture of H.sub.2 and CO is catalytically converted into
hydrocarbons and preferably liquid hydrocarbons. The mole ratio of
the hydrogen to the carbon monoxide may broadly range from about
0.5 to 4, but is more typically within the range of from about 0.7
to 2.75 and preferably from about 0.7 to 2.5. As is well known, F-T
synthesis processes include processes in which the catalyst is in
the form of a fixed bed, a fluidized bed or as a slurry of catalyst
particles in a hydrocarbon slurry liquid. The stoichiometric mole
ratio for a F-T synthesis reaction is 2.0, but there are many
reasons for using other than a stoichiometric ratio as those
skilled in the art know. In cobalt slurry hydrocarbon synthesis
process the feed mole ratio of the H.sub.2 to CO is typically about
2.1/1. The synthesis gas comprising a mixture of H.sub.2 and CO is
bubbled up into the bottom of the slurry and reacts in the presence
of the particulate F-T synthesis catalyst in the slurry liquid at
conditions effective to form hydrocarbons, a portion of which are
liquid at the reaction conditions and which comprise the
hydrocarbon slurry liquid. The synthesized hydrocarbon liquid is
separated from the catalyst particles as filtrate by means such as
filtration, although other separation means such as centrifugation
can be used. Some of the synthesized hydrocarbons pass out the top
of the hydrocarbon synthesis reactor as vapor, along with unreacted
synthesis gas and other gaseous reaction products. Some of these
overhead hydrocarbon vapors are typically condensed to liquid and
combined with the hydrocarbon liquid filtrate. Thus, the initial
boiling point of the filtrate may vary depending on whether or not
some of the condensed hydrocarbon vapors have been combined with
it. Slurry hydrocarbon synthesis process conditions vary somewhat
depending on the catalyst and desired products. Typical conditions
effective to form hydrocarbons comprising mostly C.sub.5+
paraffins, (e.g., C.sub.5+-C.sub.200) and preferably C.sub.10+
paraffins, in a slurry hydrocarbon synthesis process employing a
catalyst comprising a supported cobalt component include, for
example, temperatures, pressures and hourly gas space velocities in
the range of from about 320-850.degree. F., 80-600 psi and
100-40,000 V/hr/V, expressed as standard volumes of the gaseous CO
and H.sub.2 mixture (0.degree. C., 1 atm) per hour per volume of
catalyst, respectively. The term "C.sub.5+" is used herein to refer
to hydrocarbons with a carbon number of greater than 4, but does
not imply that material with carbon number 5 has to be present.
Similarly other ranges quoted for carbon number do not imply that
hydrocarbons having the limit values of the carbon number range
have to be present, or that every carbon number in the quoted range
is present. It is preferred that the hydrocarbon synthesis reaction
be conducted under conditions in which limited or no water gas
shift reaction occurs and more preferably with no water gas shift
reaction occurring during the hydrocarbon synthesis. It is also
preferred to conduct the reaction under conditions to achieve an
alpha of at least 0.85, preferably at least 0.9 and more preferably
at least 0.92, so as to synthesize more of the more desirable
higher molecular weight hydrocarbons. This has been achieved in a
slurry process using a catalyst containing a catalytic cobalt
component. Those skilled in the art know that by alpha is meant the
Schultz-Flory kinetic alpha. While suitable F-T reaction types of
catalyst comprise, for example, one or more Group VIII catalytic
metals such as Fe, Ni, Co, Ru and Re, it is preferred that the
catalyst comprise a cobalt catalytic component. In one embodiment
the catalyst comprises catalytically effective amounts of Co and
one or more of Re, Ru, Fe, Ni, Th, Zr, Hf, U, Mg and La on a
suitable inorganic support material, preferably one which comprises
one or more refractory metal oxides. Preferred supports for Co
containing catalysts comprise Titania, particularly. Useful
catalysts and their preparation are known and illustrative, but
nonlimiting examples may be found, for example, in U.S. Pat. Nos.
4,568,663; 4,663,305; 4,542,122; 4,621,072 and 5,545,674.
[0054] As set forth above, the waxy feed from which the base
stock(s) and/or base oil(s) is/are derived is a wax or waxy feed
from mineral oil, non-mineral oil, non-petroleum, or other natural
source, especially slack wax, or GTL material, preferably F-T
material, referred to as F-T wax. F-T wax preferably has an initial
boiling point in the range of from 650-750.degree. F. and
preferably continuously boils up to an end point of at least
1050.degree. F. A narrower cut waxy feed may also be used during
the hydroisomerization. A portion of the n-paraffin waxy feed is
converted to lower boiling isoparaffinic material. Hence, there
must be sufficient heavy n-paraffin material to yield an
isoparaffin containing isomerate boiling in the lube oil range. If
catalytic dewaxing is also practiced after
isomerization/isodewaxing, some of the isomerate/isodewaxate will
also be hydrocracked to lower boiling material during the
conventional catalytic dewaxing. Hence, it is preferred that the
end boiling point of the waxy feed be above 1050.degree. F.
(1050.degree. F.+).
[0055] When a boiling range is quoted herein it defines the lower
and/or upper distillation temperature used to separate the
fraction. Unless specifically stated (for example, by specifying
that the fraction boils continuously or constitutes the entire
range) the specification of a boiling range does not require any
material at the specified limit has to be present, rather it
excludes material boiling outside that range.
[0056] The waxy feed preferably comprises the entire
650-750.degree. F.+ fraction formed by the hydrocarbon synthesis
process, having an initial cut point between 650.degree. F. and
750.degree. F. determined by the practitioner and an end point,
preferably above 1050.degree. F., determined by the catalyst and
process variables employed by the practitioner for the synthesis.
Such fractions are referred to herein as "650-750.degree. F.+
fractions". By contrast, "650-750.degree. F..sup.- fractions"
refers to a fraction with an unspecified initial cut point and an
end point somewhere between 650.degree. F. and 750.degree. F. Waxy
feeds may be processed as the entire fraction or as subsets of the
entire fraction prepared by distillation or other separation
techniques. The waxy feed also typically comprises more than 90%,
generally more than 95% and preferably more than 98 wt % paraffinic
hydrocarbons, most of which are normal paraffins. It has negligible
amounts of sulfur and nitrogen compounds (e.g., less than 1 wppm of
each), with less than 2,000 wppm, preferably less than 1,000 wppm
and more preferably less than 500 wppm of oxygen, in the form of
oxygenates. Waxy feeds having these properties and useful in the
process of the invention have been made using a slurry F-T process
with a catalyst having a catalytic cobalt component, as previously
indicated.
[0057] The process of making the lubricant oil base stocks from
waxy stocks, e.g., slack wax or F-T wax, may be characterized as an
isomerization process. If slack waxes are used as the feed, they
may need to be subjected to a preliminary hydrotreating step under
conditions already well known to those skilled in the art to reduce
(to levels that would effectively avoid catalyst poisoning or
deactivation) or to remove sulfur- and nitrogen-containing
compounds which would otherwise deactivate the hydroisomerization
or hydrodewaxing catalyst used in subsequent steps. If F-T waxes
are used, such preliminary treatment is not required because, as
indicated above, such waxes have only trace amounts (less than
about 10 ppm, or more typically less than about 5 ppm to nil) of
sulfur or nitrogen compound content. However, some hydrodewaxing
catalyst fed F-T waxes may benefit from prehydrotreatment for the
removal of oxygenates while others may benefit from oxygenates
treatment. The hydroisomerization or hydrodewaxing process may be
conducted over a combination of catalysts, or over a single
catalyst. Conversion temperatures range from about 150.degree. C.
to about 500.degree. C. at pressures ranging from about 500 to
20,000 kPa. This process may be operated in the presence of
hydrogen, and hydrogen partial pressures range from about 600 to
6000 kPa. The ratio of hydrogen to the hydrocarbon feedstock
(hydrogen circulation rate) typically range from about 10 to 3500
n.l.l..sup.-1 (56 to 19,660 SCF/bbl) and the space velocity of the
feedstock typically ranges from about 0.1 to 20 LHSV, preferably
0.1 to 10 LHSV.
[0058] Following any needed hydrodenitrogenation or
hydrodesulfurization, the hydroprocessing used for the production
of base stocks from such waxy feeds may use an amorphous
hydrocracking/hydroisomerization catalyst, such as a lube
hydrocracking (LHDC) catalysts, for example catalysts containing
Co, Mo, Ni, W, Mo, etc., on oxide supports, e.g., alumina, silica,
silica/alumina, or a crystalline hydrocracking/hydroisomerization
catalyst, preferably a zeolitic catalyst.
[0059] Other isomerization catalysts and processes for
hydrocracking, hydro-dewaxing, or hydroisomerizing GTL materials
and/or waxy materials to base stock or base oil are described, for
example, in U.S. Pat. Nos. 2,817,693; 4,900,407; 4,937,399;
4,975,177; 4,921,594; 5,200,382; 5,516,740; 5,182,248; 5,290,426;
5,580,442; 5,976,351; 5,935,417; 5,885,438; 5,965,475; 6,190,532;
6,375,830; 6,332,974; 6,103,099; 6,025,305; 6,080,301; 6,096,940;
6,620,312; 6,676,827; 6,383,366; 6,475,960; 5,059,299; 5,977,425;
5,935,416; 4,923,588; 5,158,671; and 4,897,178; EP 0324528 (B1), EP
0532116 (B1), EP 0532118 (B1), EP 0537815 (B1), EP 0583836 (B2), EP
0666894 (B2), EP 0668342 (B1), EP 0776959 (A3), WO 97/031693 (A1),
WO 02/064710 (A2), WO 02/064711 (A1), WO 02/070627 (A2), WO
02/070629 (A1), WO 03/033320 (A1) as well as in British Patents
1,429,494; 1,350,257; 1,440,230; 1,390,359; WO 99/45085 and WO
99/20720. Particularly favorable processes are described in
European Patent Applications 464546 and 464547. Processes using F-T
wax feeds are described in U.S. Pat. Nos. 4,594,172; 4,943,672;
6,046,940; 6,475,960; 6,103,099; 6,332,974; and 6,375,830.
[0060] Hydrocarbon conversion catalysts useful in the conversion of
the n-paraffin waxy feedstocks disclosed herein to form the
isoparaffinic hydro-carbon base oil are zeolite catalysts, such as
ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-12, ZSM-38, ZSM-48, offretite,
ferrierite, zeolite beta, zeolite theta, and zeolite alpha, as
disclosed in U.S. Pat. No. 4,906,350. These catalysts are used in
combination with Group VIII metals, in particular palladium or
platinum. The Group VIII metals may be incorporated into the
zeolite catalysts by conventional techniques, such as ion
exchange.
[0061] In one embodiment, conversion of the waxy feedstock may be
conducted over a combination of Pt/zeolite beta and Pt/ZSM-23
catalysts in the presence of hydrogen. In another embodiment, the
process of producing the lubricant oil base stocks comprises
hydroisomerization and dewaxing over a single catalyst, such as
Pt/ZSM-35. In yet another embodiment, the waxy feed can be fed over
the hydrodewaxing catalyst comprising Group VIII metal loaded
ZSM-48, preferably Group VIII noble metal loaded ZSM-48, more
preferably Pt/ZSM-48 in either one stage or two stages. In any
case, useful hydrocarbon base oil products may be obtained.
Catalyst ZSM-48 is described in U.S. Pat. No. 5,075,269. The use of
the Group VIII metal loaded ZSM-48 family of catalysts, preferably
platinum on ZSM-48, in the hydroisomerization of the waxy feedstock
eliminates the need for any subsequent, separate dewaxing step.
[0062] A dewaxing step, when needed, may be accomplished using one
or more of solvent dewaxing, catalytic dewaxing or hydrodewaxing
processes and either the entire hydroisomerate or the
650-750.degree. F.+ fraction may be dewaxed, depending on the
intended use of the 650-750.degree. F.- material present, if it has
not been separated from the higher boiling material prior to the
dewaxing. In solvent dewaxing, the hydroisomerate may be contacted
with chilled solvents such as acetone, methyl ethyl ketone (MEK),
methyl isobutyl ketone (MIBK), mixtures of MEK/MIBK, or mixtures of
MEK/toluene and the like, and further chilled to precipitate out
the higher pour point material as a waxy solid which is then
separated from the solvent-containing lube oil fraction which is
the raffinate. The raffinate is typically further chilled in
scraped surface chillers to remove more wax solids.
Autorefrigerative dewaxing using low molecular weight hydrocarbons,
such as propane, can also be used in which the hydroisomerate is
mixed with, e.g., liquid propane, a least a portion of which is
flashed off to chill down the hydroisomerate to precipitate out the
wax. The wax is separated from the raffinate by filtration,
membrane separation or centrifugation. The solvent is then stripped
out of the raffinate, which is then fractionated to produce the
preferred base stocks useful in the present invention. Also well
known is catalytic dewaxing, in which the hydroisomerate is reacted
with hydrogen in the presence of a suitable dewaxing catalyst at
conditions effective to lower the pour point of the hydroisomerate.
Catalytic dewaxing also converts a portion of the hydroisomerate to
lower boiling materials, in the boiling range, for example,
650-750.degree. F.-, which are separated from the heavier
650-750.degree. F.+ base stock fraction and the base stock fraction
fractionated into two or more base stocks. Separation of the lower
boiling material may be accomplished either prior to or during
fractionation of the 650-750.degree. F.+ material into the desired
base stocks.
[0063] Any dewaxing catalyst which will reduce the pour point of
the hydroisomerate and preferably those which provide a large yield
of lube oil base stock from the hydroisomerate may be used. These
include shape selective molecular sieves which, when combined with
at least one catalytic metal component, have been demonstrated as
useful for dewaxing petroleum oil fractions and include, for
example, ferrierite, mordenite, ZSM-5, ZSM-11, ZSM-23, ZSM-35,
ZSM-22 also known as theta one or TON, and the
silicoaluminophosphates known as SAPO's. A dewaxing catalyst which
has been found to be unexpectedly particularly effective comprises
a noble metal, preferably Pt, composited with H-mordenite. The
dewaxing may be accomplished with the catalyst in a fixed, fluid or
slurry bed. Typical dewaxing conditions include a temperature in
the range of from about 400-600.degree. F., a pressure of 500-900
psig, H.sub.2 treat rate of 1500-3500 SCF/B for flow-through
reactors and LHSV of 0.1-10, preferably 0.2-2.0. The dewaxing is
typically conducted to convert no more than 40 wt % and preferably
no more than 30 wt % of the hydroisomerate having an initial
boiling point in the range of 650-750.degree. F. to material
boiling below its initial boiling point.
[0064] GTL base stock(s) and/or base oil(s), hydrodewaxed, or
hydroisomerized/cat (or solvent) dewaxed wax-derived base stock(s)
and/or base oil(s), have a beneficial kinematic viscosity advantage
over conventional API Group II and Group III base stock(s) and/or
base oil(s), and so may be very advantageously used with the
instant invention. Such GTL base stock(s) and/or base oil(s) can
have significantly higher kinematic viscosities, up to about 20-50
mm.sup.2/s at 100.degree. C., whereas by comparison commercial
Group II base oils can have kinematic viscosities up to about 15
mm.sup.2/s at 100.degree. C., and commercial Group III base oils
can have kinematic viscosities up to about 10 mm.sup.2/s at
100.degree. C. The higher kinematic viscosity range of GTL base
stock(s) and/or base oil(s), compared to the more limited kinematic
viscosity range of Group II and Group III base stock(s) and/or base
oil(s), in combination with the instant invention can provide
additional beneficial advantages in formulating lubricant
compositions.
[0065] In the present invention mixtures of hydrodewaxate, or
hydroisomerate/cat (or solvent) dewaxate base stock(s) and/or base
oil(s), mixtures of the GTL base stock(s) and/or base oil(s), or
mixtures thereof, preferably mixtures of GTL base stock(s) and/or
base oil(s), can constitute all or part of the base oil.
[0066] The preferred base stock(s) and/or base oil(s) derived from
GTL materials and/or from waxy feeds are characterized as having
predominantly paraffinic compositions and are further characterized
as having high saturates levels, low-to-nil sulfur, low-to-nil
nitrogen, low-to-nil aromatics, and are essentially water-white in
color.
[0067] A preferred GTL liquid hydrocarbon composition is one
comprising paraffinic hydrocarbon components in which the extent of
branching, as measured by the percentage of methyl hydrogens (BI),
and the proximity of branching, as measured by the percentage of
recurring methylene carbons which are four or more carbons removed
from an end group or branch (CH.sub.2.gtoreq.4), are such that: (a)
BI-0.5(CH.sub.2.gtoreq.4)>15; and (b) BI+0.85
(CH.sub.2.gtoreq.4)<45 as measured over said liquid hydrocarbon
composition as a whole.
[0068] The preferred GTL base stock and/or base oil can be further
characterized, if necessary, as having less than 0.1 wt % aromatic
hydrocarbons, less than 20 wppm nitrogen containing compounds, less
than 20 wppm sulfur containing compounds, a pour point of less than
-18.degree. C., preferably less than -30.degree. C., a preferred
BI.gtoreq.25.4 and (CH.sub.2.gtoreq.4).ltoreq.22.5. They have a
nominal boiling point of 370.degree. C..sup.+, on average they
average fewer than 10 hexyl or longer branches per 100 carbon atoms
and on average have more than 16 methyl branches per 100 carbon
atoms. They also can be characterized by a combination of dynamic
viscosity, as measured by CCS at -40.degree. C., and kinematic
viscosity, as measured at 100.degree. C. represented by the
formula: DV (at -40.degree. C.)<2900 (KV at 100.degree.
C.)-7000.
[0069] The preferred GTL base stock and/or base oil is also
characterized as comprising a mixture of branched paraffins
characterized in that the lubricant base oil contains at least 90%
of a mixture of branched paraffins, wherein said branched paraffins
are paraffins having a carbon chain length of about C.sub.20 to
about C.sub.40, a molecular weight of about 280 to about 562, a
boiling range of about 650.degree. F. to about 1050.degree. F., and
wherein said branched paraffins contain up to four alkyl branches
and wherein the free carbon index of said branched paraffins is at
least about 3.
[0070] In the above the Branching Index (BI), Branching Proximity
(CH.sub.2.gtoreq.4), and Free Carbon Index (FCI) are determined as
follows:
Branching Index
[0071] A 359.88 MHz 1 H solution NMR spectrum is obtained on a
Bruker 360 MHz AMX spectrometer using 10% solutions in CDCl.sub.3.
TMS is the internal chemical shift reference. CDCl.sub.3 solvent
gives a peak located at 7.28. All spectra are obtained under
quantitative conditions using 90 degree pulse (10.9 .mu.s), a pulse
delay time of 30 s, which is at least five times the longest
hydrogen spin-lattice relaxation time (T.sub.1), and 120 scans to
ensure good signal-to-noise ratios.
[0072] H atom types are defined according to the following regions:
[0073] 9.2-6.2 ppm hydrogens on aromatic rings; [0074] 6.2-4.0 ppm
hydrogens on olefinic carbon atoms; [0075] 4.0-2.1 ppm benzylic
hydrogens at the .alpha.-position to aromatic rings; [0076] 2.1-1.4
ppm paraffinic CH methine hydrogens; [0077] 1.4-1.05 ppm paraffinic
CH.sub.2 methylene hydrogens; [0078] 1.05-0.5 ppm paraffinic
CH.sub.3 methyl hydrogens.
[0079] The branching index (BI) is calculated as the ratio in
percent of non-benzylic methyl hydrogens in the range of 0.5 to
1.05 ppm, to the total non-benzylic aliphatic hydrogens in the
range of 0.5 to 2.1 ppm.
Branching Proximity (CH.sub.2.gtoreq.4)
[0080] A 90.5 MHz.sup.3CMR single pulse and 135 Distortionless
Enhancement by Polarization Transfer (DEPT) NMR spectra are
obtained on a Brucker 360 MHzAMX spectrometer using 10% solutions
in CDCL.sub.3. TMS is the internal chemical shift reference.
CDCL.sub.3 solvent gives a triplet located at 77.23 ppm in the
1.sup.3C spectrum. All single pulse spectra are obtained under
quantitative conditions using 45 degree pulses (6.3 .mu.s), a pulse
delay time of 60 s, which is at least five times the longest carbon
spin-lattice relaxation time (T.sub.1), to ensure complete
relaxation of the sample, 200 scans to ensure good signal-to-noise
ratios, and WALTZ-16 proton decoupling.
[0081] The C atom types CH.sub.3, CH.sub.2, and CH are identified
from the 135 DEPT
[0082] .sup.13C NMR experiment. A major CH.sub.2 resonance in all
.sup.13C NMR spectra at .apprxeq.29.8 ppm is due to equivalent
recurring methylene carbons which are four or more removed from an
end group or branch (CH2>4). The types of branches are
determined based primarily on the .sup.13C chemical shifts for the
methyl carbon at the end of the branch or the methylene carbon one
removed from the methyl on the branch.
[0083] Free Carbon Index (FCI). The FCI is expressed in units of
carbons, and is a measure of the number of carbons in an
isoparaffin that are located at least 5 carbons from a terminal
carbon and 4 carbons way from a side chain. Counting the terminal
methyl or branch carbon as "one" the carbons in the FCI are the
fifth or greater carbons from either a straight chain terminal
methyl or from a branch methane carbon. These carbons appear
between 29.9 ppm and 29.6 ppm in the carbon-13 spectrum. They are
measured as follows: [0084] a) calculate the average carbon number
of the molecules in the sample which is accomplished with
sufficient accuracy for lubricating oil materials by simply
dividing the molecular weight of the sample oil by 14 (the formula
weight of CH.sub.2); [0085] b) divide the total carbon-13 integral
area (chart divisions or area counts) by the average carbon number
from step a. to obtain the integral area per carbon in the sample;
[0086] c) measure the area between 29.9 ppm and 29.6 ppm in the
sample; and [0087] d) divide by the integral area per carbon from
step b. to obtain FCI.
[0088] Branching measurements can be performed using any Fourier
Transform NMR spectrometer. Preferably, the measurements are
performed using a spectrometer having a magnet of 7.0T or greater.
In all cases, after verification by Mass Spectrometry, UV or an NMR
survey that aromatic carbons were absent, the spectral width was
limited to the saturated carbon region, about 0-80 ppm vs. TMS
(tetramethylsilane). Solutions of 15-25 percent by weight in
chloroform-d1 were excited by 45 degrees pulses followed by a 0.8
sec acquisition time. In order to minimize non-uniform intensity
data, the proton decoupler was gated off during a 10 sec delay
prior to the excitation pulse and on during acquisition. Total
experiment times ranged from 11-80 minutes. The DEPT and APT
sequences were carried out according to literature descriptions
with minor deviations described in the Varian or Bruker operating
manuals.
[0089] DEPT is Distortionless Enhancement by Polarization Transfer.
DEPT does not show quaternaries. The DEPT 45 sequence gives a
signal for all carbons bonded to protons. DEPT 90 shows CH carbons
only. DEPT 135 shows CH and CH.sub.3 up and CH.sub.2 180 degrees
out of phase (down). APT is Attached Proton Test. It allows all
carbons to be seen, but if CH and CH.sub.3 are up, then
quaternaries and CH.sub.2 are down. The sequences are useful in
that every branch methyl should have a corresponding CH and the
methyls are clearly identified by chemical shift and phase. The
branching properties of each sample are determined by C-13 NMR
using the assumption in the calculations that the entire sample is
isoparaffinic. Corrections are not made for n-paraffins or
cyclo-paraffins, which may be present in the oil samples in varying
amounts. The cycloparaffins content is measured using Field
Ionization Mass Spectroscopy (FIMS).
[0090] GTL base stock(s) and/or base oil(s), and hydrodewaxed, or
hydroisomerized/cat (or solvent) dewaxed wax base stock(s) and/or
base oil(s), for example, hydroisomerized or hydrodewaxed waxy
synthesized hydrocarbon, e.g., Fischer-Tropsch waxy hydrocarbon
base stock(s) and/or base oil(s) are of low or zero sulfur and
phosphorus content. There is a movement among original equipment
manufacturers and oil formulators to produce formulated oils of
ever increasingly reduced sulfated ash, phosphorus and sulfur
content to meet ever increasingly restrictive environmental
regulations. Such oils, known as low SAPS oils, would rely on the
use of base oils which themselves, inherently, are of low or zero
initial sulfur and phosphorus content. Such oils when used as base
oils can be formulated with additives. Even if the additive or
additives included in the formulation contain sulfur and/or
phosphorus the resulting formulated lubricating oils will be lower
or low SAPS oils as compared to lubricating oils formulated using
conventional mineral oil base stock(s) and/or base oil(s).
[0091] For example, low SAPS formulated oils for vehicle engines
(both spark ignited and compression ignited) will have a sulfur
content of 0.7 wt % or less, preferably 0.6 wt % or less, more
preferably 0.5 wt % or less, most preferably 0.4 wt % or less, an
ash content of 1.2 wt % or less, preferably 0.8 wt % or less, more
preferably 0.4 wt % or less, and a phosphorus content of 0.18% or
less, preferably 0.1 wt % or less, more preferably 0.09 wt % or
less, most preferably 0.08 wt % or less, and in certain instances,
even preferably 0.05 wt % or less.
[0092] The instant invention can be used with additional lubricant
components in effective amounts in lubricant compositions, such as
for example polar and/or non-polar lubricant base oils, and
performance additives such as for example, but not limited to,
oxidation inhibitors, metallic and non-metallic dispersants,
metallic and non-metallic detergents, corrosion and rust
inhibitors, metal deactivators, anti-wear agents (metallic and
non-metallic, phosphorus-containing and non-phosphorus,
sulfur-containing and non-sulfur types), extreme pressure additives
(metallic and non-metallic, phosphorus-containing and
non-phosphorus, sulfur-containing and non-sulfur types),
anti-seizure agents, pour point depressants, wax modifiers,
viscosity modifiers, seal compatibility agents, lubricity agents,
anti-staining agents, chromophoric agents, defoamants,
demulsifiers, and others. For a review of many commonly used
additives see Klamann in Lubricants and Related Products, Verlag
Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0, which also gives
a good discussion of a number of the lubricant additives mentioned
below. Reference is also made "Lubricant Additives" by M. W.
Ranney, published by Noyes Data Corporation of Parkridge, N.J.
(1978).
[0093] The types and quantities of performance additives used in
combination with the instant invention in lubricant compositions
are not limited by the examples shown herein as illustrations.
Antiwear and EP Additives
[0094] Internal combustion engine lubricating oils require the
presence of antiwear and/or extreme pressure (EP) additives in
order to provide adequate antiwear protection for the engine.
Increasingly specifications for engine oil performance have
exhibited a trend for improved antiwear properties of the oil.
Antiwear and extreme EP additives perform this role by reducing
friction and wear of metal parts.
[0095] While there are many different types of antiwear additives,
for several decades the principal antiwear additive for internal
combustion engine crankcase oils is a metal alkylthiophosphate and
more particularly a metal dialkyldithio-phosphate in which the
primary metal constituent is zinc, or zinc dialkyldithio-phosphate
(ZDDP). ZDDP compounds generally are of the formula
Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2 where R.sup.1 and R.sup.2 are
C.sub.1-C.sub.18 alkyl groups, preferably C.sub.2-C.sub.12 alkyl
groups. These alkyl groups may be straight chain or branched. The
ZDDP is typically used in amounts of from about 0.4 to 1.4 wt % of
the total lube oil composition, although more or less can often be
used advantageously.
[0096] However, it is found that the phosphorus from these
additives has a deleterious effect on the catalyst in catalytic
converters and also on oxygen sensors in automobiles. One way to
minimize this effect is to replace some or all of the ZDDP with
phosphorus-free antiwear additives.
[0097] A variety of non-phosphorous additives are also used as
antiwear additives. Sulfurized olefins are useful as antiwear and
EP additives. Sulfur-containing olefins can be prepared by
sulfurization or various organic materials including aliphatic,
arylaliphatic or alicyclic olefinic hydrocarbons containing from
about 3 to 30 carbon atoms, preferably 3-20 carbon atoms. The
olefinic compounds contain at least one non-aromatic double bond.
Such compounds are defined by the formula
R.sup.3R.sup.4C.dbd.CR.sup.5R.sup.6
where each of R.sup.3-R.sup.6 are independently hydrogen or a
hydrocarbon radical. Preferred hydrocarbon radicals are alkyl or
alkenyl radicals. Any two of R.sup.3-R.sup.6 may be connected so as
to form a cyclic ring. Additional information concern-ing
sulfurized olefins and their preparation can be found in U.S. Pat.
No. 4,941,984.
[0098] The use of polysulfides of thiophosphorus acids and
thiophosphorus acid esters as lubricant additives is disclosed in
U.S. Pat. Nos. 2,443,264; 2,471,115; 2,526,497; and 2,591,577.
Addition of phosphorothionyl disulfides as an antiwear,
antioxidant, and EP additive is disclosed in U.S. Pat. No.
3,770,854. Use of alkylthiocarbamoyl compounds
(bis(dibutyl)thiocarbamoyl, for example) in combination with a
molybdenum compound (oxymolybdenum diisopropyl-phosphorodithioate
sulfide, for example) and a phosphorous ester (dibutyl hydrogen
phosphite, for example) as antiwear additives in lubricants is
disclosed in U.S. Pat. No. 4,501,678. U.S. Pat. No. 4,758,362
discloses use of a carbamate additive to provide improved antiwear
and extreme pressure properties. The use of thiocarbamate as an
antiwear additive is disclosed in U.S. Pat. No. 5,693,598.
Thiocarbamate/molybdenum complexes such as moly-sulfur alkyl
dithio-carbamate trimer complex (R.dbd.C.sub.8-C.sub.18 alkyl) are
also useful antiwear agents. The use or addition of such materials
should be kept to a minimum if the object is to produce low SAP
formulations. Each of the aforementioned patents is incorporated by
reference herein in its entirety.
[0099] Esters of glycerol may be used as antiwear agents. For
example, mono-, di-, and tri-oleates, mono-palmitates and
mono-myristates may be used.
[0100] ZDDP is combined with other compositions that provide
antiwear properties. U.S. Pat. No. 5,034,141 discloses that a
combination of a thiodixanthogen compound (octylthiodixanthogen,
for example) and a metal thiophosphate (ZDDP, for example) can
improve antiwear properties. U.S. Pat. No. 5,034,142 discloses that
use of a metal alkyoxyalkylxanthate (nickel ethoxyethylxanthate,
for example) and a dixanthogen (diethoxyethyl dixanthogen, for
example) in combination with ZDDP improves antiwear properties.
Each of the afore-mentioned patents is incorporated herein by
reference in its entirety.
[0101] Preferred antiwear additives include phosphorus and sulfur
compounds such as zinc dithiophosphates and/or sulfur, nitrogen,
boron, molybdenum phosphorodithioates, molybdenum dithiocarbamates
and various organo-molybdenum derivatives including heterocyclics,
for example dimercaptothiadiazoles, mercaptobenzothiadiazoles,
triazines, and the like, alicyclics, amines, alcohols, esters,
diols, triols, fatty amides and the like can also be used. Such
additives may be used in an amount of about 0.01 to 6 wt %,
preferably about 0.01 to 4 wt %. ZDDP-like compounds provide
limited hydroperoxide decomposition capability, significantly below
that exhibited by compounds disclosed and claimed in this patent
and can therefore be eliminated from the formulation or, if
retained, kept at a minimal concentration to facilitate production
of low SAP formulations.
Antioxidants
[0102] Antioxidants retard the oxidative degradation of base oils
during service. Such degradation may result in deposits on metal
surfaces, the presence of sludge, or a viscosity increase in the
lubricant. One skilled in the art knows a wide variety of oxidation
inhibitors that are useful in lubricating oil compositions. See,
Klamann in Lubricants and Related Products, op cite, and U.S. Pat.
Nos. 4,798,684 and 5,084,197, for example, each of which is
incorporated by reference herein in its entirety.
[0103] Useful antioxidants include hindered phenols. These phenolic
anti-oxidants may be ashless (metal-free) phenolic compounds or
neutral or basic metal salts of certain phenolic compounds. Typical
phenolic antioxidant compounds are the hindered phenolics which are
the ones which contain a sterically hindered hydroxyl group, and
these include those derivatives of dihydroxy aryl compounds in
which the hydroxyl groups are in the o- or p-position to each
other. Typical phenolic antioxidants include the hindered phenols
substituted with C.sub.6+alkyl groups and the alkylene coupled
derivatives of these hindered phenols. Examples of phenolic
materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl
phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant invention. Examples of ortho-coupled
phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol);
2,2'-bis(4-octyl-6-t-butyl-phenol); and
2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols
include for example 4,4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0104] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or
in combination with phenolics. Typical examples of non-phenolic
antioxidants include: alkylated and non-alkylated aromatic amines
such as aromatic monoamines of the formula R.sup.8R.sup.9R.sup.10N
where R.sup.8 is an aliphatic, aromatic or substituted aromatic
group, R.sup.9 is an aromatic or a substituted aromatic group, and
R.sup.10 is H, alkyl, aryl or R.sup.11S(O).sub.xR.sup.12 where
R.sup.11 is an alkylene, alkenylene, or aralkylene group, R.sup.12
is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and
x is 0, 1 or 2. The aliphatic group R.sup.8 may contain from 1 to
about 20 carbon atoms, and preferably contains from about 6 to 12
carbon atoms. The aliphatic group is a saturated aliphatic group.
Preferably, both R.sup.8 and R.sup.9 are aromatic or substituted
aromatic groups, and the aromatic group may be a fused ring
aromatic group such as naphthyl. Aromatic groups R.sup.8 and
R.sup.9 may be joined together with other groups such as S.
[0105] Typical aromatic amines antioxidants have alkyl substituent
groups of at least about 6 carbon atoms. Examples of aliphatic
groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally,
the aliphatic groups will not contain more than about 14 carbon
atoms. The general types of amine antioxidants useful in the
present compositions include diphenylamines, phenyl naphthylamines,
phenothiazines, imidodibenzyls and diphenyl phenylene diamines.
Mixtures of two or more aromatic amines are also useful. Polymeric
amine antioxidants can also be used. Particular examples of
aromatic amine antioxidants useful in the present invention
include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
[0106] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants.
[0107] Another class of antioxidant used in lubricating oil
compositions is oil-soluble copper compounds. Any oil-soluble
suitable copper compound may be blended into the lubricating oil.
Examples of suitable copper antioxidants include copper
dihydrocarbyl thio- or dithio-phosphates and copper salts of
carboxylic acid (naturally occurring or synthetic). Other suitable
copper salts include copper dithiacarbamates, sulphonates,
phenates, and acetylacetonates. Basic, neutral, or acidic copper
Cu(I) and or Cu(II) salts derived from alkenyl succinic acids or
anhydrides are know to be particularly useful.
[0108] Preferred antioxidants include hindered phenols, arylamines.
These antioxidants may be used individually by type or in
combination with one another. Such additives may be used in an
amount of about 0.01 to 5 wt %, preferably about 0.01 to 1.5 wt %,
more preferably zero to less than 1.5 wt %, most preferably
zero.
Detergents
[0109] Detergents are commonly used in lubricating compositions. A
typical detergent is an anionic material that contains a long chain
hydrophobic portion of the molecule and a smaller anionic or
oleophobic hydrophilic portion of the molecule. The anionic portion
of the detergent is typically derived from an organic acid such as
a sulfur acid, carboxylic acid, phosphorous acid, phenol, or
mixtures thereof. The counterion is typically an alkaline earth or
alkali metal.
[0110] Salts that contain a substantially stochiometric amount of
the metal are described as neutral salts and have a total base
number (TBN, as measured by ASTM D2896) of from 0 to 80. Many
compositions are overbased, containing large amounts of a metal
base that is achieved by reacting an excess of a metal compound (a
metal hydroxide or oxide, for example) with an acidic gas (such as
carbon dioxide). Useful detergents can be neutral, mildly
overbased, or highly overbased.
[0111] It is desirable for at least some detergent to be overbased.
Overbased detergents help neutralize acidic impurities produced by
the combustion process and become entrapped in the oil. Typically,
the overbased material has a ratio of metallic ion to anionic
portion of the detergent of about 1.05:1 to 50:1 on an equivalent
basis. More preferably, the ratio is from about 4:1 to about 25:1.
The resulting detergent is an overbased detergent that will
typically have a TBN of about 150 or higher, often about 250 to 450
or more. Preferably, the overbasing cation is sodium, calcium, or
magnesium. A mixture of detergents of differing TBN can be used in
the present invention.
[0112] Preferred detergents include the alkali or alkaline earth
metal salts of sulfonates, phenates, carboxylates, phosphates, and
salicylates.
[0113] Sulfonates may be prepared from sulfonic acids that are
typically obtained by sulfonation of alkyl substituted aromatic
hydrocarbons. Hydro-carbon examples include those obtained by
alkylating benzene, toluene, xylene, naphthalene, biphenyl and
their halogenated derivatives (chlorobenzene, chlorotoluene, and
chloronaphthalene, for example). The alkylating agents typically
have about 3 to 70 carbon atoms. The alkaryl sulfonates typically
contain about 9 to about 80 carbon or more carbon atoms, more
typically from about 16 to 60 carbon atoms.
[0114] Klamann in Lubricants and Related Products, op cit discloses
a number of overbased metal salts of various sulfonic acids which
are useful as detergents and dispersants in lubricants. The book
entitled "Lubricant Additives", C. V. Smallheer and R. K. Smith,
published by the Lezius-Hiles Co. of Cleveland, Ohio (1967),
similarly discloses a number of overbased sulfonates that are
useful as dispersants/detergents.
[0115] Alkaline earth phenates are another useful class of
detergent. These detergents can be made by reacting alkaline earth
metal hydroxide or oxide (CaO, Ca(OH).sub.2, BaO, Ba(OH).sub.2,
MgO, Mg(OH).sub.2, for example) with an alkyl phenol or sulfurized
alkylphenol. Useful alkyl groups include straight chain or branched
C.sub.1-C.sub.30 alkyl groups, preferably, C.sub.4-C.sub.20.
Examples of suitable phenols include isobutylphenol,
2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It
should be noted that starting alkylphenols may contain more than
one alkyl substituent that are each independently straight chain or
branched. When a non-sulfurized alkylphenol is used, the sulfurized
product may be obtained by methods well known in the art. These
methods include heating a mixture of alkylphenol and sulfurizing
agent (including elemental sulfur, sulfur halides such as sulfur
dichloride, and the like) and then reacting the sulfurized phenol
with an alkaline earth metal base.
[0116] Metal salts of carboxylic acids are also useful as
detergents. These carboxylic acid detergents may be prepared by
reacting a basic metal compound with at least one carboxylic acid
and removing free water from the reaction product. These compounds
may be overbased to produce the desired TBN level. Detergents made
from salicylic acid are one preferred class of detergents derived
from carboxylic acids. Useful salicylates include long chain alkyl
salicylates. One useful family of compositions is of the
formula
##STR00001##
where R is a hydrogen atom or an alkyl group having 1 to about 30
carbon atoms, n is an integer from 1 to 4, and M is an alkaline
earth metal. Preferred R groups are alkyl chains of at least
C.sub.11, preferably C.sub.13 or greater. R may be optionally
substituted with substituents that do not interfere with the
detergent's function. M is preferably, calcium, magnesium, or
barium. More preferably, M is calcium.
[0117] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction. See U.S. Pat. No. 3,595,791 for
additional information on synthesis of these compounds. The metal
salts of the hydrocarbyl-substituted salicylic acids may be
prepared by double decomposition of a metal salt in a polar solvent
such as water or alcohol.
[0118] Alkaline earth metal phosphates are also used as
detergents.
[0119] Detergents may be simple detergents or what is known as
hybrid or complex detergents. The latter detergents can provide the
properties of two detergents without the need to blend separate
materials. See U.S. Pat. No. 6,034,039 for example.
[0120] Preferred detergents include calcium phenates, calcium
sulfonates, calcium salicylates, magnesium phenates, magnesium
sulfonates, magnesium salicylates and other related components
(including borated detergents). Typically, the total detergent
concentration is about 0.01 to about 6.0 wt %, preferably, about
0.1 to 0.4 wt %.
Dispersant
[0121] During engine operation, oil-insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposition on metal surfaces. Dispersants
may be ashless or ash-forming in nature. Preferably, the dispersant
is ashless. So called ashless dispersants are organic materials
that form substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are
considered ashless. In contrast, metal-containing detergents
discussed above form ash upon combustion.
[0122] Suitable dispersants typically contain a polar group
attached to a relatively high molecular weight hydrocarbon chain.
The polar group typically contains at least one element of
nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain
50 to 400 carbon atoms.
[0123] Chemically, many dispersants may be characterized as
phenates, sulfonates, sulfurized phenates, salicylates,
naphthenates, stearates, carbamates, thiocarbamates, phosphorus
derivatives. A particularly useful class of dispersants are the
alkenylsuccinic derivatives, typically produced by the reaction of
a long chain substituted alkenyl succinic compound, usually a
substituted succinic anhydride, with a polyhydroxy or polyamino
compound. The long chain group constituting the oleophilic portion
of the molecule which confers solubility in the oil, is normally a
polyisobutylene group. Many examples of this type of dispersant are
well known commercially and in the literature. Exemplary U.S.
patents describing such dispersants are U.S. Pat. Nos. 3,172,892;
3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607;
3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other
types of dispersant are described in U.S. Pat. Nos. 3,036,003;
3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804;
3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059;
3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300;
4,100,082; 5,705,458. A further description of dispersants may be
found, for example, in European Patent Application No. 471 071, to
which reference is made for this purpose.
[0124] Hydrocarbyl-substituted succinic acid compounds are popular
dispersants. In particular, succinimide, succinate esters, or
succinate ester amides prepared by the reaction of a
hydrocarbon-substituted succinic acid compound preferably having at
least 50 carbon atoms in the hydrocarbon substituent, with at least
one equivalent of an alkylene amine are particularly useful.
[0125] Succinimides are formed by the condensation reaction between
alkenyl succinic anhydrides and amines. Molar ratios can vary
depending on the poly-amine. For example, the molar ratio of
alkenyl succinic anhydride to TEPA can vary from about 1:1 to about
5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936;
3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616,
3,948,800; and Canada Pat. No. 1,094,044.
[0126] Succinate esters are formed by the condensation reaction
between alkenyl succinic anhydrides and alcohols or polyols. Molar
ratios can vary depending on the alcohol or polyol used. For
example, the condensation product of an alkenyl succinic anhydride
and pentaerythritol is a useful dispersant.
[0127] Succinate ester amides are formed by condensation reaction
between alkenyl succinic anhydrides and alkanol amines. For
example, suitable alkanol amines include ethoxylated
polyalkylpolyamines, propoxylated polyalkylpoly-amines and
polyalkenylpolyamines such as polyethylene polyamines. One example
is propoxylated hexamethylenediamine. Representative examples are
shown in U.S. Pat. No. 4,426,305.
[0128] The molecular weight of the alkenyl succinic anhydrides used
in the preceding paragraphs will typically range between 800 and
2,500. The above products can be post-reacted with various reagents
such as sulfur, oxygen, formaldehyde, carboxylic acids such as
oleic acid, and boron compounds such as borate esters or highly
borated dispersants. The dispersants can be borated with from about
0.1 to about 5 moles of boron per mole of dispersant reaction
product.
[0129] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No.
4,767,551, which is incorporated herein by reference. Process aids
and catalysts, such as oleic acid and sulfonic acids, can also be
part of the reaction mixture. Molecular weights of the alkylphenols
range from 800 to 2,500. Representative examples are shown in U.S.
Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953;
3,798,165; and 3,803,039.
[0130] Typical high molecular weight aliphatic acid modified
Mannich condensation products useful in this invention can be
prepared from high molecular weight alkyl-substituted
hydroxyaromatics or HN(R).sub.2 group-containing reactants.
[0131] Examples of high molecular weight alkyl-substituted
hydroxyaromatic compounds are polypropylphenol, polybutylphenol,
and other polyalkylphenols. These polyalkylphenols can be obtained
by the alkylation, in the presence of an alkylating catalyst, such
as BF.sub.3, of phenol with high molecular weight poly-propylene,
polybutylene, and other polyalkylene compounds to give alkyl
substituents on the benzene ring of phenol having an average
600-100,000 molecular weight.
[0132] Examples of HN(R).sub.2 group-containing reactants are
alkylene polyamines, principally polyethylene polyamines. Other
representative organic compounds containing at least one
HN(R).sub.2 group suitable for use in the preparation of Mannich
condensation products are well known and include the mono- and
di-amino alkanes and their substituted analogs, e.g., ethylamine
and diethanol amine; aromatic diamines, e.g., phenylene diamine,
diamino naphthalenes; heterocyclic amines, e.g., morpholine,
pyrrole, pyrrolidine, imidazole, imidazolidine, and piperidine;
melamine and their substituted analogs.
[0133] Examples of alkylene polyamide reactants include
ethylenediamine, diethylene triamine, triethylene tetraamine,
tetraethylene pentaamine, penta-ethylene hexamine, hexaethylene
heptaamine, heptaethylene octaamine, octaethylene nonaamine,
nonaethylene decamine, and decaethylene undecamine and mixture of
such amines having nitrogen contents corresponding to the alkylene
polyamines, in the formula H.sub.2N-(Z-NH--).sub.nH, mentioned
before, Z is a divalent ethylene and n is 1 to 10 of the foregoing
formula. Corresponding propylene polyamines such as propylene
diamine and di-, tri-, tetra-, penta-propylene tri-, tetra-, penta-
and hexaamines are also suitable reactants. The alkylene polyamines
are usually obtained by the reaction of ammonia and dihalo alkanes,
such as dichloro alkanes. Thus the alkylene polyamines obtained
from the reaction of 2 to 11 moles of ammonia with 1 to 10 moles of
dichloroalkanes having 2 to 6 carbon atoms and the chlorines on
different carbons are suitable alkylene polyamine reactants.
[0134] Aldehyde reactants useful in the preparation of the high
molecular products useful in this invention include the aliphatic
aldehydes such as formaldehyde (also as paraformaldehyde and
formalin), acetaldehyde and aldol (P-hydroxybutyraldehyde).
Formaldehyde or a formaldehyde-yielding reactant is preferred.
[0135] Hydrocarbyl substituted amine ashless dispersant additives
are well known to one skilled in the art; see, for example, U.S.
Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433; 3,822,209 and
5,084,197.
[0136] Preferred dispersants include borated and non-borated
succinimides, including those derivatives from mono-succinimides,
bis-succinimides, and/or mixtures of mono- and bis-succinimides,
wherein the hydrocarbyl succinimide is derived from a
hydrocarbylene group such as polyisobutylene having a Mn of from
about 500 to about 5000 or a mixture of such hydrocarbylene groups.
Other preferred dispersants include succinic acid-esters and
amides, alkylphenol-polyamine-coupled Mannich adducts, their capped
derivatives, and other related components. Such additives may be
used in an amount of about 0.1 to 20 wt %, preferably about 0.1 to
8 wt %.
Pour Point Depressants
[0137] Conventional pour point depressants (also known as lube oil
flow improvers) may be added to the compositions of the present
invention if desired. These pour point depressant may be added to
lubricating compositions of the present invention to lower the
minimum temperature at which the fluid will flow or can be poured.
Examples of suitable pour point depressants include
poly-methacrylates, polyacrylates, polyarylamides, condensation
products of haloparaffin waxes and aromatic compounds, vinyl
carboxylate polymers, and terpolymers of dialkylfumarates, vinyl
esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos.
1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746;
2,721,877; 2.721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Such additives may be
used in an amount of about 0.01 to 5 wt %, preferably about 0.01 to
1.5 wt %.
Corrosion Inhibitors
[0138] Corrosion inhibitors are used to reduce the degradation of
metallic parts that are in contact with the lubricating oil
composition. Suitable corrosion inhibitors include thiadiazoles.
See, for example, U.S. Pat. Nos. 2,719,125; 2,719,126; and
3,087,932. Such additives may be used in an amount of about 0.01 to
5 wt %, preferably about 0.01 to 1.5 wt %.
Seal Compatibility Additives
[0139] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl
succinic anhydride. Such additives may be used in an amount of
about 0.01 to 3 wt %, preferably about 0.01 to 2 wt %.
Anti-Foam Agents
[0140] Anti-foam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical anti-foam agents. For
example, polysiloxanes, such as silicon oil or polydimethyl
siloxane, provide antifoam properties. Anti-foam agents are
commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually
the amount of these additives combined is less than 1 percent and
often less than 0.1 percent.
Inhibitors and Antirust Additives
[0141] Antirust additives (or corrosion inhibitors) are additives
that protect lubricated metal surfaces against chemical attack by
water or other contaminants. A wide variety of these are
commercially available; they are referred to in Klamann in
Lubricants and Related Products, op cit.
[0142] One type of antirust additive is a polar compound that wets
the metal surface preferentially, protecting it with a film of oil.
Another type of antirust additive absorbs water by incorporating it
in a water-in-oil emulsion so that only the oil touches the metal
surface. Yet another type of antirust additive chemically adheres
to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates,
basic metal sulfonates, fatty acids and amines. Such additives may
be used in an amount of about 0.01 to 5 wt %, preferably about 0.01
to 1.5 wt %.
Friction Modifiers
[0143] A friction modifier is any material or materials that can
alter the coefficient of friction of a surface lubricated by any
lubricant or fluid containing such material(s). Friction modifiers,
also known as friction reducers, or lubricity agents or oiliness
agents, and other such agents that change the ability of base oils,
formulated lubricant compositions, or functional fluids, to modify
the coefficient of friction of a lubricated surface may be
effectively used in combination with the base oils or lubricant
compositions of the present invention if desired. Friction
modifiers that lower the coefficient of friction are particularly
advantageous in combination with the base oils and lube
compositions of this invention. Friction modifiers may include
metal-containing compounds or materials as well as ashless
compounds or materials, or mixtures thereof. Metal-containing
friction modifiers may include metal salts or metal-ligand
complexes where the metals may include alkali, alkaline earth, or
transition group metals. Such metal-containing friction modifiers
may also have low-ash characteristics. Transition metals may
include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may include
hydrocarbyl derivative of alcohols, polyols, glycerols, partial
ester glycerols, thiols, carboxylates, carbamates, thiocarbamates,
dithiocarbamates, phosphates, thiophosphates, dithiophosphates,
amides, imides, amines, thiazoles, thiadiazoles, dithiazoles,
diazoles, triazoles, and other polar molecular functional groups
containing effective amounts of O, N, S, or P, individually or in
combination. In particular, Mo-containing compounds can be
particularly effective such as for example Mo-dithiocarbamates,
Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines, Mo (Am),
Mo-alcoholates, Mo-alcohol-amides, etc. See U.S. Pat. No.
5,824,627; U.S. Pat. No. 6,232,276; U.S. Pat. No. 6,153,564; U.S.
Pat. No. 6,143,701; U.S. Pat. No. 6,110,878; U.S. Pat. No.
5,837,657; U.S. Pat. No. 6,010,987; U.S. Pat. No. 5,906,968; U.S.
Pat. No. 6,734,150; U.S. Pat. No. 6,730,638; U.S. Pat. No.
6,689,725; U.S. Pat. No. 6,569,820; WO 99/66013; WO 99/47629; WO
98/26030.
[0144] Ashless friction modifiers may have also include lubricant
materials that contain effective amounts of polar groups, for
example, hydroxyl-containing hydrocarbyl base oils, glycerides,
partial glycerides, glyceride derivatives, and the like. Polar
groups in friction modifiers may include hydrocarbyl groups
containing effective amounts of O, N, S, or P, individually or in
combination. Other friction modifiers that may be particularly
effective include, for example, salts (both ash-containing and
ashless derivatives) of fatty acids, fatty alcohols, fatty amides,
fatty esters, hydroxyl-containing carboxylates, and comparable
synthetic long-chain hydrocarbyl acids, alcohols, amides, esters,
hydroxy carboxylates, and the like. In some instances fatty organic
acids, fatty amines, and sulfurized fatty acids may be used as
suitable friction modifiers.
[0145] Useful concentrations of friction modifiers may range from
about 0.01 wt % to 10-15 wt % or more, often with a preferred range
of about 0.1 wt % to 5 wt %. Concentrations of
molybdenum-containing materials are often described in terms of Mo
metal concentration. Advantageous concentrations of Mo may range
from about 10 ppm to 3000 ppm or more, and often with a preferred
range of about 20-2000 ppm, and in some instances a more preferred
range of about 30-1000 ppm. Friction modifiers of all types may be
used alone or in mixtures with the materials of this invention.
Often mixtures of two or more friction modifiers, or mixtures of
friction modifier(s) with alternate surface active material(s), are
also desirable.
Typical Additive Amounts
[0146] When lubricating oil compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
invention are shown in Table 1 below.
[0147] Note that many of the additives are shipped from the
manufacturer and used with a certain amount of base oil solvent in
the formulation. Accordingly, the weight amounts in the table
below, as well as other amounts mentioned in this patent, unless
otherwise indicated are directed to the amount of active ingredient
(that is the non-solvent portion of the ingredient). The wt %
indicated below are based on the total weight of the lubricating
oil composition.
TABLE-US-00001 TABLE 1 Typical Amounts of Various Lubricant Oil
Components Approximate wt % Approximate wt % Compound (useful)
(preferred) Detergent 0.01 6 0.01 4 Dispersant 0.1 20 0.1 8
Friction Reducer 0.01 5 0.01 1.5 Antioxidant 0.0 5 0.0 1.5
Corrosion Inhibitor 0.01 5 0.01 1.5 Anti-wear Additive 0.01 6 0.01
4 Pour Point Depressant 0.0 5 0.01 1.5 Anti-foam Agent 0.001 3
0.001 0.15 Base stock or base oil Balance Balance
EXAMPLES
Example 1
[0148] Blends were prepared comprising only GTL 6 of nominal KV 6.0
mm.sup.2/s at 100.degree. C., a mixture of only 150N and 600N Group
I base oil the KV of the mixture being nominally 6.0 mm.sup.2/s @
100.degree. C., and combinations of the GTL 6 and the 150N/600N
base oils. All contained 2.0 wt % (as received) dispersant Infineum
C9268. The blends were tested in a soot handling screener test
which adds 3 wt % carbon black to the blend replicating 3 wt % soot
in the oil.
[0149] The screener test is summarized below: [0150] 1. Prepared
blend by adding designated amount of carbon black paste (20% carbon
black) and test oil to a blender. Blend for 5 minutes at high
speed. [0151] 2. Transfer mixture to beaker with magnetic stir bar.
Stir at 200 rpm for 1 hour at 65.degree. C. [0152] 3. Immediately
after stirring, charge the mixture to the viscometer in the
100.degree. C. KV bath. Allow sample to equilibrate for exactly 15
minutes, then measure the Kinematic viscosity. [0153] 4. For each
oil, measure the viscosity increase at each increasing weight
percent. Stop testing when viscosity increase exceeds 200%.
In Example 1 the blends did not contain a viscosity modifier.
[0154] Results show that as more GTL is added, there is less
increase in viscosity. Dispersancy, which relates to soot control
capability, increases with increasing amounts of GTL:
TABLE-US-00002 TABLE 2 Viscosity of % Viscosity % base oil and
Viscosity with increase with % Low S % dispersant Carbon Black,
carbon black GTL 150N 600N blend, mm.sup.2/s mm.sup.2/s added as
soot 0.0 83.0 17.0 6.661 20.490 208% 20.0 66.4 13.6 6.580 11.360
73% 40.0 49.8 10.2 6.543 9.250 41% 60.0 33.2 6.8 6.543 8.480 30%
80.0 16.6 3.4 6.451 7.970 24% 100.0 0.0 0.0 6.451 7.440 15%
The results are presented graphically in FIG. 1.
Example 2
[0155] In this Example the relationship between GTL content and the
desired thickening ability of two different viscosity modifiers at
two different concentrations in blends is investigated. A 6.0
mm.sup.2/s GTL 6 and a 6.0 mm.sup.2/s Group I blend were used. No
carbon black was added. The GTL/Group I base stock combinations
used in Example 2 are the same as those used in Example 1
above.
TABLE-US-00003 TABLE 3 % GTL/% Group I Blend 0/100 20/80 40/60
60/40 80/20 100/0 Viscosity: Blend with 15 wt 16.0 15.5 15.2 14.8
14.5 14.2 % (as received) Paratone 8011 (mm.sup.2/s) Thickening
parameter: % 1.50 1.57 1.64 1.70 1.77 1.82 Paratone 8011/change in
KV100 Viscosity: Blend with 25 wt 15.4 14.8 14.2 13.7 13.3 12.9 %
(as received) Infineum SVs 151 (mm.sup.2/s) Thickening parameter: %
2.65 2.85 3.05 3.25 3.44 3.64 Shellvis 151/change in KV100
[0156] Larger ratios of % viscosity modifier to change in viscosity
represent less thickening ability or solubilizing power of the base
stock of the deliberately added viscosity modifier. Smaller values,
i.e., lower ratio values are indicative of better thickening due to
the viscosity modifiers. As more GTL is added, the thickening
ability of the viscosity modifier in the blend decreases. The
results are presented graphically in FIG. 2.
[0157] When one plots the % viscosity increase from FIG. 1/Table 2
against the polymer thickener parameter of FIG. 2/Table 3 one sees
that there is an unexpected optional regime of GTL content within
which one achieves not only a significant reduction in viscosity
increase due to soot but still obtains the desirable thickening due
to soot but still obtains the desirable thickening due to the
viscosity modifiers. The results are presented in Table 4 and FIG.
3.
TABLE-US-00004 TABLE 4 % GTL/% Group I Blend 0/100 20/80 40/60
60/40 80/20 100/0 wt % Sulfur 0.183 0.147 0.110 0.073 0.037 0.000 %
Viscosity Increase from 208% 73% 41% 30% 24% 15% Soot Viscosity:
Blend with 16.0 15.5 15.2 14.8 14.5 14.2 15 wt % (as received)
Paratone 8011 (cSt) % Paratone/delta KV100 1.50 1.57 1.64 1.70 1.77
1.82
[0158] Blends containing between 10 and 80 wt % GTL in the base
oil, prefer-ably 20 to 60 wt % GTL in the base oil unexpectedly
exhibited both a significant reduction in the viscosity increase
due to soot in the oil which retaining the desired thickening
effect due to the viscosity modifier.
* * * * *
References