U.S. patent application number 12/380125 was filed with the patent office on 2010-08-26 for lubricant compositions containing glycerol tri-esters.
Invention is credited to Suzz Chen Hsi Ho, Abhimanyu Onkar Patil, Margaret May-Som Wu.
Application Number | 20100216678 12/380125 |
Document ID | / |
Family ID | 42631505 |
Filed Date | 2010-08-26 |
United States Patent
Application |
20100216678 |
Kind Code |
A1 |
Patil; Abhimanyu Onkar ; et
al. |
August 26, 2010 |
Lubricant compositions containing glycerol tri-esters
Abstract
A lubricant composition comprising a Group I-IV or Group VI lube
base stock and a glycerol tri-ester of the formula: ##STR00001##
wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected
from linear or branched C.sub.4 to C.sub.14 alkyl groups.
Inventors: |
Patil; Abhimanyu Onkar;
(Westfield, NJ) ; Wu; Margaret May-Som; (Skillman,
NJ) ; Ho; Suzz Chen Hsi; (Princeton, NJ) |
Correspondence
Address: |
ExxonMobil Research & Engineering Company
P.O. Box 900, 1545 Route 22 East
Annandale
NJ
08801-0900
US
|
Family ID: |
42631505 |
Appl. No.: |
12/380125 |
Filed: |
February 24, 2009 |
Current U.S.
Class: |
508/497 |
Current CPC
Class: |
C10N 2020/04 20130101;
C10N 2020/02 20130101; C10M 111/04 20130101; C10M 2203/1025
20130101; C10N 2020/013 20200501; C10M 2207/401 20130101; C10M
2205/0285 20130101; C10N 2020/011 20200501; C11C 3/02 20130101;
C10M 2203/1025 20130101; C10N 2020/02 20130101; C10M 2203/1025
20130101; C10N 2020/02 20130101 |
Class at
Publication: |
508/497 |
International
Class: |
C10M 129/72 20060101
C10M129/72 |
Claims
1. A lubricant composition comprising a Group I-IV or Group VI lube
base stock and a glycerol tri-ester of the formula: ##STR00006##
wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected
from linear or branched C.sub.4 to C.sub.14 alkyl groups.
2. The lubricant composition of claim 1, wherein the Group I-IV or
Group VI lube base stock is present in an amount of 50 wt % to 99
wt %.
3. The lubricant composition of claim 1, wherein the lube base
stock is a liquid polyalphaolefin having a Kv.sub.100 of from
greater than 3 cSt to 10,000 cSt.
4. The lubricant composition of claim 1, wherein R.sub.1, R.sub.2
and R.sub.3 are the same or different.
5. The lubricant composition of claim 4, wherein R.sub.1, R.sub.2
and R.sub.3 are linear alkyl groups.
6. The lubricant composition of claim 4, wherein R.sub.1, R.sub.2
and R.sub.3 are branched alkyl groups.
7. The lubricant composition of claim 4, wherein R.sub.1, R.sub.2
and R.sub.3 are a combination of linear and branched alkyl
groups.
8. The lubricant composition of claim 1, wherein the glycerol
tri-ester is glycerol trioctanoate.
9. The lubricant composition of claim 1, wherein the glycerol
tri-ester is glycerol trinonanoate.
10. The lubricant composition of claim 1, wherein the glycerol
tri-ester is glycerol tridecanoate.
11. The lubricant composition of claim 1, wherein the glycerol
tri-ester has a Kv.sub.100 of less than 20 cSt.
12. The lubricant composition of claim 1, wherein the glycerol
tri-ester has a VI greater than 90.
13. The lubricant composition of claim 3, wherein the liquid
polyalphaolefin has a Kv.sub.100 of from greater than 3 cSt to 300
cSt.
14. The lubricant composition of claim 1, wherein the glycerol
tri-ester has a pour point of less than 0.degree. C.
15. The lubricant composition of claim 1, further comprising at
least one additive selected from the group consisting of
detergents, dispersants, antioxidants, antiwear additives, pour
point depressants, viscosity index modifiers, friction modifiers,
defoaming agents, corrosion inhibitors, wetting agents, densifiers,
fluid-loss additives and rust inhibitors.
16. The lubricant composition of claim 1, wherein the Group I-IV or
Group VI lube base stock is derived from a gas-to-liquid
hydrocarbon material.
17. The lubricant composition of claim 1, wherein the Group I-IV or
Group VI lube base stock is a Group III lube base stock.
18. A lubricant composition comprising greater than 50 wt % of a
metallocene-catalyzed PAO lube base stock, having a Kv.sub.100 from
3 cSt to 300 cSt, and less than 50 wt % of a glycerol tri-ester of
the formula: ##STR00007## wherein R.sub.1, R.sub.2 and R.sub.3 are
independently selected from linear or branched C.sub.4 to C.sub.14
alkyl groups.
19. A lubricant composition comprising greater than 50 wt % of a
Group III lube base stock, and less than 50 wt % of a glycerol
tri-ester of the formula: ##STR00008## wherein R.sub.1, R.sub.2 and
R.sub.3 are independently selected from linear or branched C.sub.4
to C.sub.14 alkyl groups.
Description
FIELD
[0001] The present disclosure relates to a lubricant useful in
engine oils and in general lubricant applications. The present
disclosure further relates to a lubricant composition containing
highly non-polar base stocks, that has improved solvency for polar
additives.
BACKGROUND
[0002] Poly-.alpha.-olefins (PAOs) are important non-polar lube
base stocks with many excellent lubricant properties, including
high viscosity index (VI) and low volatility and are available in a
wide viscosity range, i.e., a Kv.sub.100 of about 2 to about 600
centistokes (cSt)). PAOs are disclosed as lube base stocks, for
example, in U.S. Published Patent Application No. 20080177121
A1.
[0003] Other important lube base stocks are those derived from one
or more Gas-to-Liquids materials (GTLs) that are derived via one or
more synthesis, combination, transformation, rearrangement, and/or
degradation/deconstructive processes from gaseous carbon-containing
compounds. GTLs are disclosed as lube base stocks, for example, in
U.S. Published Application No. 2007/0265178, which is incorporated
herein by reference.
[0004] Other important lube base stocks are the Groups I, II, III
and VI base stocks, which are discussed in "Synthetics, Mineral
Oils and Bio-Based Lubricants, Chemistry and Technology" Edited by
L. R. Rudnick, published by CRC Press, Taylor & Francis, 2006,
which is incorporated herein by reference.
[0005] Base stocks of PAOs, GTLs, and Groups I-III and VI exhibit
relatively low polarity. This low polarity leads to low solubility
and dispersancy for polar additives or sludge generated in
lubricants containing these base stocks.
[0006] To compensate for the low polarity of base stocks of PAOs,
GTLs, and Groups I-III and VI, lubricant manufacturers commonly
incorporate one or more polar co-base stocks. Commonly used co-base
stocks are esters or alkylated naphthalenes, which are typically
present in the lube base stock at about 1 wt % to about 50 wt %
based on the total weight of the base and co-base stocks. Esters
and alkylated naphthalenes are disclosed, for example, in U.S. Pat.
Nos. 6,627,779 B2 and 6,833,065 B2 as well as WO 03/035585. Other
co-base stocks include various dicarboxylic acid esters, which are
disclosed, for example, in U.S. Pat. Nos. 2,936,320; 3,251,771;
3,409,553; 4,464,277; and 6,667,285.
[0007] U.S. Pat. No.3,701,730 discloses extreme pressure additives
for lubricant compositions which are synthetic esters, such as (a)
dibrominated neopentyl glycol esters, (b) phosphate esters,
polycarboxylic acids having 2-54 carbon atoms, or (d) combinations
of (a), (b) and (c).
[0008] U.S. Pat. No. 4,683,069 discloses lubricating oil
compositions exhibiting improved fuel economy which contain 0.05 to
0.2 wt % of a glycerol partial ester of a C.sub.16-C.sub.18 fatty
acid as a fuel economy additive.
[0009] U.S. Pat. No. 5,034,144 discloses lubricating oil
compositions used for food processing machines, which exhibit
highly improved oxidation stability, wear resistance and rust
prevention, comprising as the base oil a saturated fatty acid
glyceride and as an essential component, a fatty acid in an amount
of 0.001 to 5% by weight, based on the total composition.
[0010] U.S. Pat. No. 5,262,076 discloses synthetic lubricating oils
having as a base oil at least one carbonic acid ester of various
disclosed polyols.
[0011] U.S. Pat. No. 5,503,762 discloses base oils with high
viscosity indices and low pour points which are mixtures of a
complex ester formed from aliphatic, cycloaliphatic or aromatic
dicarboxylic acids, aliphatic polyols containing 2 to 6 hydroxyl
groups and aliphatic monocarboxylic acids containing 6 to 22 carbon
atoms and adipic acid esters of unbranched aliphatic monohydric
alcohols.
[0012] U.S. Pat. No. 5,538,654 discloses a food grade lubricant
composition for equipment in the food service industry, comprising
(A) a major amount of a genetically modified vegetable oil and (B)
a minor amount of a performance additive.
[0013] U.S. Pat. No. 5,658,864 discloses the use of biodegradable
polyalphaolefins ("PAOs") to treat biodegradable industrial fluids,
such as lubricants, hydraulic fluids, fuel oils, and the like, to:
(a) reduce their pour point; (b) improve their oxidation stability
performance; and/or, (c) improve their hydrolytic stability
performance. A preferred industrial fluid is mixture of vegetable
oil and branched alkane where the average molecular weight of the
alkane is about 200-400, and the alkane additionally has a
sufficient degree of branching to have a pour point of about
-25.degree. C. or lower.
[0014] U.S. Pat. No. 6,833,065 discloses methods for preparing a
blended lube base oils comprising at least one highly paraffinic
Fischer-Tropsch lube base stocks and at least one base stock
composed of alkylaromatics, alkylcycloparaffins, or mixtures
thereof. The use of base stocks composed of alkylaromatics,
alkylcycloparaffins, or mixtures thereof improves the yield of lube
base oils from Fischer-Tropsch facilities, as well as provides
moderate improvements in physical properties including additive
solubility. The disclosure provides processes for obtaining such
blended lube base oils using the products of Fischer-Tropsch
processes.
[0015] WO 97/22572 discloses a dielectric fluid or coolant
comprising relatively pure blends of compounds selected from the
group consisting of aromatic hydrocarbons, polyalphaolefins, polyol
esters, glycerol tri-esters and natural vegetable oils, along with
additives to improve pour point, increase stability and reduce
oxidation rate.
[0016] WO 2004/108866 discloses an improved food grade lubricant
comprising at least one vegetable oil, at least one
polyalphaolefin, and at least one antioxidant.
[0017] However, despite recent advances, there remains an unmet
need in the art to formulate highly non-polar lubricant base stocks
with inexpensive polar co-solvents to improve the solubility of
various lube oil additives in the non-polar base stock.
Unfortunately, conventional polar co-base stocks can be quite
expensive, and when present in large amounts in a lubricant
formulation, can raise the cost of the overall composition
significantly.
SUMMARY
[0018] In a first embodiment, the present disclosure is directed to
a lubricant composition comprising a Group I-IV or
poly-internal-olefin (PIO or Group VI) lube base stock and a
glycerol tri-ester of the formula:
##STR00002##
wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected
from linear or branched C.sub.4 to C.sub.14 alkyl groups.
[0019] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the Group I-IV or
VI lube base stock is present in an amount of 50 wt % to 99 wt
%.
[0020] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the lube base
stock is a liquid polyalphaolefin having a Kv.sub.100 of from
greater than 3 cSt to 10,000 cSt.
[0021] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein R.sub.1, R.sub.2
and R.sub.3 are the same or different.
[0022] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein R.sub.1, R.sub.2
and R.sub.3 are linear alkyl groups.
[0023] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein R.sub.1, R.sub.2
and R.sub.3 are branched alkyl groups.
[0024] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein R.sub.1, R.sub.2
and R.sub.3 are a combination of linear and branched alkyl
groups.
[0025] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the glycerol
tri-ester is glycerol trioctanoate.
[0026] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the glycerol
tri-ester is glycerol trinonanoate.
[0027] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the glycerol
tri-ester is glycerol tridecanoate.
[0028] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the glycerol
tri-ester has a Kv.sub.100 of less than 20 cSt.
[0029] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the glycerol
tri-ester has a VI greater than 90.
[0030] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the liquid
polyalphaolefin has a Kv.sub.100 of from greater than 3 cSt to 300
cSt.
[0031] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the glycerol
tri-ester has a pour point of less than 0.degree. C.
[0032] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, further comprising at
least one additive selected from the group consisting of
detergents, dispersants, antioxidants, antiwear additives, pour
point depressants, viscosity index modifiers, friction modifiers,
defoaming agents, corrosion inhibitors, wetting agents, densifiers,
fluid-loss additives and rust inhibitors.
[0033] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the Group I-IV or
VI lube base stock is derived from a gas-to-liquid hydrocarbon
material.
[0034] In another embodiment, the disclosure is directed to a
lubricant composition as disclosed above, wherein the Group I-IV or
VI lube base stock is a Group III lube base stock.
[0035] In another embodiment, the disclosure is directed to a
lubricant composition comprising greater than 50 wt % of a
metallocene-catalyzed PAO lube base stock, having a Kv.sub.100 from
3 cSt to 300 cSt, and less than 50 wt % of a glycerol tri-ester of
the formula:
##STR00003##
wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected
from linear or branched C.sub.4 to C.sub.14 alkyl groups.
[0036] In another embodiment, the disclosure is directed to a
lubricant composition comprising greater than 50 wt % of a Group
III lube base stock, and less than 50 wt % of a glycerol tri-ester
of the formula:
##STR00004##
wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected
from linear or branched C.sub.4 to C.sub.14 alkyl groups.
DETAILED DESCRIPTION
[0037] All numerical values in this disclosure are understood as
being modified by "about" or "approximately" the indicated value,
and take into account experimental error and variations that would
be expected by a person having ordinary skill in the art.
[0038] Glycerol tri-esters of the formula:
##STR00005##
wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected
from linear or branched C.sub.4 to C.sub.14 alkyl groups, which can
be the same or different, or can be combinations of linear and
branched alkyl groups, are very effective as polar co-base lube
stocks, particularly for PAO and GTL lube base stocks and can be
blended therewith to obtain clear and bright liquids from very low
to very high concentrations. The tri-esters are amorphous, have low
glass transition temperature (Tg) and are cost-competitive with
other polar co-bases. The tri-esters have advantageous lubrication
properties, such as low volatility and low viscosity.
[0039] The blends of the present disclosure have a first lube base
stock of one or more glycerol tri-esters from 1 wt % to 50 wt % and
a second lube base stock selected from a Group I to Group IV or
Group VI lube base stock, preferably of one or more
poly-.alpha.-olefin and/or a GTL base stock at 99 wt % to 50 wt %
based on the total weight of the blend. Preferred blends have 1 wt
% to 50 wt % of the first base stock and 99 wt % to 50 wt % of the
second base stock. More preferred blends have the first base stock
at 2 wt % to 25 wt % and the second base stock at 98 wt % to 75 wt
%.
[0040] The glycerol tri-esters useful as co-basestocks can be
selected based on physical properties desired. Kinematic viscosity
can vary from 2 cSt to 20 cSt, even from 2.5 cSt to 10 cSt, and
even from 3 to 7 cSt. Noack volatility can vary from 2 wt % to 30
wt %, even from 3 wt % to 15 wt %. Glass transition temperature,
Tg, can vary from 0.degree. C. to -90.degree. C., and even from
-10.degree. C. to -80.degree. C. Viscosity index, VI, can vary from
50 to 300, even from 70 to 250 and even from 90 to 250. Pour points
are generally less than 0.degree. C., even less than -15.degree.
C., even less than -20.degree. C., or even less than -30.degree. C.
Kinematic viscosities at 100.degree. C. (Kv.sub.100) and 40.degree.
C. (Kv.sub.40) are measured according to ASTM method D445.
Viscosity index is measured according to ASTM method D2270. Noack
volatility is measured according to ASTM D5800. The pour points are
measured according to ASTM D97.
[0041] Particularly useful glycerol tri-esters are those having
C.sub.4 to C.sub.14 alkyl substituents at the ester linkages, with
average carbon length of 6 to 10, even between 7 to 9 carbon atoms,
from a single acid or a mixture of acids, especially the C.sub.8
and C.sub.9 tri-esters exhibiting a Kv.sub.100 of less than 4 cSt.
These glycerol tri-esters are "green" additive solubilizers because
they do not contain N, S, or aromatic rings and because they also
exhibit superior oxidative and cleanliness attributes.
[0042] The glycerol tri-esters can be synthesized by reacting
glycerol with either C.sub.4 to C.sub.14 alkyl acids, or with
C.sub.4 to C.sub.14 alkyl acid chlorides with average carbon length
of 6 to 10, even between 7 to 9 carbon atoms, from a single acid or
a mixture of acids. The esterification procedure is carried out in
the presence of a catalyst. While the selection of the particular
alkyl acids or alkyl acid chlorides is not critical, it is
important that the reactant acids or acid chlorides be fully
saturated compounds, i.e. having no unsaturated sites within the
carbon chains thereof. We have found that glycerol tri-esters of
unsaturated organic acids will tend to degrade under the high
temperature conditions typically encountered by engine lubricating
oils, forming unwanted contaminants in the lubricating oil.
[0043] The reactants may be contacted in the presence of a
heterogeneous or a homogenous acid catalyst. The acid catalyst is
used to increase the rate of reaction. The amount of catalyst is
not critical, but at least enough catalyst must be used to provide
a reasonable rate of esterification.
[0044] A conventional heterogeneous esterification catalyst may be
used. One preferred heterogeneous catalyst that may be used is a
sulfonic acid cation exchange resin having a macro-reticular
structure. These catalysts, their properties, and method of
preparation are shown in U.S. Pat. No. 3,037,052, which is
incorporated herein by reference. Such catalysts are available
commercially and are sold under the trade name Amberlyst by Rohm
& Haas of Philadelphia, Pa. Acidic zeolite catalysts may also
be used.
[0045] Alternatively, a conventional homogenous esterification acid
catalyst may be utilized in the reaction. Useful catalysts include
sulfuric acid, phosphoric acid, p-toluene sulfonic acid, sodium
bisulfate, potassium bisulfate, related catalysts, and the like.
Other catalysts that may be used include esters of titanium or
zirconium, such as tetraalkyl titanates or zirconates (e.g.
tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate,
tetra-n-propyl zirconate). Also, metal oxides such as zinc oxide,
alumina, and the like can be used. A preferred homogenous catalyst
is 4-toluene sulfonic acid monohydrate. A preferred catalyst is
titanium isopropoxide.
[0046] The esterification is carried out at a temperature,
pressure, and for a period of time sufficient to affect the desired
level of conversion. The reaction temperature is usually from 25 to
300.degree. C., even from 50 to 250.degree. C., and even from 100
to 220.degree. C. The reaction is carried out for a time preferably
from 1 to 48 hours, even from 2 to 36 hours, and even from 4 to 24
hours. Completion of reaction may be determined by gas
chromatography analysis of the product composition.
[0047] PAOs are a class of hydrocarbons that can be manufactured by
the catalytic oligomerization (polymerization to
low-molecular-weight products) of linear .alpha.-olefin (LAO)
monomers. These typically range from 1-hexene to 1-tetradecene,
with 1-decene being an advantageous material, although oligomeric
copolymers with lower olefins such as ethylene and propylene may
also be used, including copolymers of ethylene with higher olefins
as described in U.S. Pat. No. 4,956,122 and the patents referred to
therein. PAO products have achieved importance in the lubricating
oil market. Typically there are two classes of synthetic
hydrocarbon fluids (SHF) produced from linear alpha-olefins, the
two classes of SHF being denoted as PAO and HVI-PAO (high viscosity
index PAO's). PAO's of different viscosity grades are typically
produced using promoted BF.sub.3 or AlCl.sub.3 catalysts.
[0048] Specifically, PAOs may be produced by the polymerization of
olefin feed in the presence of a catalyst such as AlCl.sub.3,
BF.sub.3, or promoted AlCl.sub.3 or BF.sub.3. Processes for the
production of PAOs are disclosed, for example, in the following
patents: U.S. Pat. Nos. 3,149,178; 3,382,291; 3,742,082; 3,769,363;
3,780,128; 4,172,855 and 4,956,122, which are fully incorporated by
reference. PAOs are also discussed in the following: Will, J. G.
Lubrication Fundamentals, Marcel Dekker: New York, 1980. Subsequent
to polymerization, the PAO lubricant range products are typically
hydrogenated in order to reduce residual unsaturation, generally to
a level of greater than 90% of hydrogenation. HVI-PAOs may be
conveniently made by the polymerization of an alpha-olefin in the
presence of a polymerization catalyst such as Friedel-Crafts
catalysts. These include, for example, boron trifluoride, aluminum
trichloride, or boron trifluoride, promoted with water, with
alcohols such as ethanol, propanol, or butanol, with carboxylic
acids, or with esters such as ethyl acetate or ethyl propionate or
ether such as diethyl ether, and diisopropyl ether. (See for
example, the methods disclosed by U.S. Pat. Nos. 4,149,178 and
3,382,291.) Other descriptions of PAO synthesis are found in the
following: U.S. Pat. No. 3,742,082; U.S. Pat. No. 3,769,363; U.S.
Pat. No. 3,876,720; U.S. Pat. No. 4,239,930; U.S. Pat. No.
4,367,352; U.S. Pat. No. 4,413,156; U.S. Pat. No. 4,434,408; U.S.
Pat. No. 4,910,355; U.S. Pat. No. 4,956,122; and U.S. Pat. No.
5,068,487.
[0049] Another class of HVI-PAOs may be prepared by the action of a
supported, reduced chromium catalyst with an alpha-olefin monomer.
Such PAOs are described in U.S. Pat. No. 4,827,073; U.S. Pat. No.
4,827,064; U.S. Pat. No. 4,967,032; U.S. Pat. No. 4,926,004; and
U.S. Pat. No. 4,914,254. Commercially available PAOs include
SpectraSyn.TM. 2, 4, 5, 6, 8, 10, 40, 100 and SpectraSyn Ultra.TM.
150, SpectraSyn Ultra.TM. 300, SpectraSyn Ultra.TM. 1000, etc.
(ExxonMobil Chemical Company, Houston, Tex.). Also included are
PAOs prepared in the presence of an activated metallocene catalyst
with a non-coordinating anion activator or a methyaluminoxane
activator, and optionally in the presence of hydrogen as discussed
in U.S. Published Patent Application No. 2008/0177121 or
EP1910432A1, which can have Kv.sub.100 values from 2 cSt to as much
as 10,000 cSt, even between 3 cSt to 10,000 cSt, even between 3.5
cSt to 1000 cSt, or between 4 cSt to 600 cSt, or between 4 cSt to
300 cSt, or between 4 cSt to 150 cSt, or between 4 cSt to 100 cSt,
or between 20 cSt and 300 cSt.
[0050] Polyinternalolefin (PIO) or Group VI base stocks are
long-chain hydrocarbons, typically a linear backbone with some
branching randomly attached; they are obtained by oligomerization
of internal n-olefins. The details about these base stocks are
discussed in "Synthetics, Mineral Oils and Bio-Based Lubricants,
Chemistry and Technology" Edited by L. R. Rudnick, published by CRC
Press, Taylor & Francis, 2006, which is incorporated herein by
reference.
[0051] Gas-to-liquid (GTL) base oils comprise base stocks obtained
from GTL materials that are derived via one or more synthesis,
combination, transformation, rearrangement, and/or
degradation/deconstructive processes from gaseous carbon-containing
compounds. Preferably, the GTL base stocks are derived from the
Fischer-Tropsch (F-T) synthesis process wherein a synthesis gas
comprising a mixture of H.sub.2 and CO is catalytically converted
to lower boiling materials by hydroisomerisation and/or dewaxing.
The process is described, for example, in U.S. Pat. Nos. 5,348,982
and 5,545,674, and examples of suitable catalysts are described in
U.S. Pat. No. 4,568,663, each of which is incorporated herein by
reference.
[0052] GTL base stocks are characterized typically as having
Kv.sub.100 of from 2 cSt to 50 cSt, even from 3 cSt to 50 cSt, and
even from 3.5 cSt to 30 cSt. The GTL base stock and/or other
hydrodewaxed, or hydroisomerized/catalytically (or solvent) dewaxed
wax derived base stocks useful in the present disclosure have
Kv.sub.100 in the range of 3.5 cSt to 7 cSt, even 4 cSt to 7 cSt,
and even 4.5 cSt to 6.5 cSt, and pour points of -5.degree. C. or
lower, even -10.degree. C. or lower, and even -15.degree. C. or
lower.
[0053] The GTL base stocks derived from GTL materials, especially
hydrodewaxed or hydroisomerized/catalytically (or solvent) dewaxed
F-T material derived base stocks, and other such wax-derived base
stocks which are base stock components which can be used in this
disclosure are also characterized typically as having viscosity
indices of 80 or greater, even 100 or greater, and even 120 or
greater. Additionally, in certain particular instances, the
viscosity index of these base stocks may be 130 or greater, even
135 or greater, and even 140 or greater. For example, GTL base
stocks that derive from GTL materials preferably F-T materials
especially F-T wax generally have a viscosity index of 130 or
greater.
[0054] Examples of useful compositions of GTL base stocks are
recited in U.S. Pat. Nos. 6,080,301; 6,090,989; and 6,165,949, for
example, which are herein incorporated by reference.
[0055] Base stock(s), derived from waxy feeds, which are also
suitable for use in this disclosure, are paraffinic fluids of
lubricating viscosity derived from hydrodewaxed, or
hydroisomerized/catalytically (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 20 or greater, even 30 or greater, and mixtures of such
isomerate/isodewaxate base stocks and base oils.
[0056] Slack waxes are waxes recovered from any waxy hydrocarbon
oils, including synthetic oils 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.
[0057] Slack waxes 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 waxes 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.
[0058] Preferred base stocks or base oils 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.
[0059] The lubricant of the present disclosure can have API Group
I-III oils as second base stocks. Useful Group I-III base stocks
have a Kv.sub.100 of greater than 3 cSt to 5 cSt. API Groups I, II,
and III represent base stocks typically refined from crude oil and
are differentiated by viscosity index (VI), saturation content, and
sulfur content.
[0060] The specifications for the lube base oils are defined in the
API Interchange Guidelines (API Publication 1509) using sulfur
content, saturates content, and viscosity index, as follows:
TABLE-US-00001 Group Sulfur (ppm) Saturates (%) Viscosity Index
(VI) I >300 <90 80-120 II <300 >90 80-120 III <300
>90 >120 IV All Polyalphaolefins (PAOs) V All Stocks Not
Included in Groups I-IV VI All Poly-internal-olefins (PIOs)
[0061] Manufacturing plants that make Group I base oils typically
use solvents to extract the lower viscosity index (VI) components
and increase the VI of the crude to the specifications desired.
These solvents are typically phenol or furfural. Solvent extraction
gives a product with less than 90% saturates and more than 300 ppm
sulfur. The majority of the lube production in the world is in the
Group I category.
[0062] Manufacturing plants that make Group II base oils typically
employ hydroprocessing such as hydrocracking or severe
hydrotreating to increase the VI of the crude oil to the
specifications value. The use of hydroprocessing typically
increases the saturate content above 90 and reduced the sulfur
below 300 ppm. Approximately 10% of the lube base oil production in
the world is in the Group II category, and 30% of U.S. production
is Group II.
[0063] Manufacturing plants that make Group III base oils typically
employ wax isomerization technology to make very high VI products.
Since the starting feed is waxy vacuum gas oil (VGO) or wax which
contains all saturates and little sulfur, the Group III products
have saturate content above 90 and sulfur content below 300
ppm.
[0064] The lubricant of the present disclosure may optionally
include lube base oil additives such as detergents, dispersants,
antioxidants, antiwear additives, pour point depressants, viscosity
index modifiers, friction modifiers, defoaming agents, corrosion
inhibitors, wetting agents, densifiers, fluid-loss additives, rust
inhibitors, and the like. The additives are incorporated into the
blend to make a finished lubricant that has desired viscosity and
physical properties. Typically, additives will make up 10 wt % or
less of the lubricant. Typical description of additives used in
different lubricant product formulation can be found in "Lubricant
Additives, Chemistry and Applications" Ed. L. Rudnick, published by
Marcel Dekker, Inc. New York, N.Y., 2003.
[0065] The lubricant can be employed in a variety of end uses, such
as automotive crank case lubricant, automotive engine lubricants,
automotive driveline lubricants, automotive gear oils, automotive
transmission lubricants, general industrial lubricants, gear and
circulation oils, hydraulic lubricants, grease, etc.
[0066] We found that glycerol tri-esters are very effective polar
co-base stocks for PAO of all viscosity ranges, GTL fluids and
other hydrocarbon base stocks such as Group I-III or Group VI, and
can be blended with these non-polar base stocks to improve their
polarity, solvency and unexpectedly, their low temperature
properties. These blends were clear and bright liquids from very
low to very high concentrations.
[0067] We have synthesized several glycerol tri-esters using
glycerol (derived from plant oils and a by-product in bio-diesel
process) as feed and studied their lube properties. Base stocks
with wide viscosity ranges, high VI (>80) and low pour points
and excellent low temperature properties can be prepared.
[0068] We discovered that some of the glycerol tri-esters have
unique lube properties, such as low Kv.sub.100 viscosity and high
VI. For example, C.sub.9 tri-ester has a Kv.sub.100 of 3.84 cSt
(<4 cSt) and VI of 124. These types of polar base stocks are
"green" additive solubilizers, since they can be derived from
renewable or sustainable sources, and also have superior oxidative
and cleanliness features.
[0069] Four glycerol tri-esters were synthesized by reaction of
glycerol and various (C.sub.6-C.sub.10) acids or acid chlorides.
The lube properties and product performance of these esters were
evaluated to develop structure-property-performance knowledge for
these Group V base stocks. Other compositions can be synthesized to
optimize lube properties (linear vs. branched and using various
carbon length acids, i.e. C.sub.7, C.sub.8, C.sub.9, etc).
EXAMPLES
[0070] Kinematic viscosities (Kv), viscosity index (VI), and pour
point (PP) temperature of the products were evaluated using
following techniques. Kinematic viscosity was measured according to
ASTM method D445. Viscosity index was measured according to ASTM
method D2270. The pour points are measured according to ASTM
D97.
Preparation of Tri-esters Using Glycerol and Acid Chlorides
Example 1
Synthesis of Glycerol Trioctanoate
[0071] Glycerol (1.430 g, FW. 92.09) and octanoyl chloride (7.65 g,
FW. 162.7) were weighed in a 50 ml flask and cooled down in an ice
bath. Pyridine (4.0 g, FW. 79.1) was slowly added drop-wise while
stirring. The reaction mixture turned slightly yellow. After 10
minutes, the mixture was filtered to remove pyridine HCl salt that
had formed in the reaction mixture. The solution was diluted with
100 ml t-butyl methyl ether and any unreacted pyridine was removed
by washing with dilute HCl solution (1N, 50 ml.times.2). The
solution was further washed with brine and dried by MgSO.sub.4. The
t-butyl methyl ether solvent was removed by rotary evaporation. 8.6
g of a viscous, slightly yellow product was obtained. Yield: 95.5%.
The product was analyzed using IR spectroscopy.
Example 2
Synthesis of Glycerol Trinonanoate
[0072] Glycerol (1.03 g, FW. 92.09) and nonanoyl chloride (5.94 g,
FW. 176.7) were weighed in a 50 ml flask and cooled down in an ice
bath. Pyridine (3.0 g, FW. 79.1) was slowly added drop-wise to the
flask while stirring. The reaction mixture turned slightly yellow.
After 10 minutes the mixture was filtered to remove pyridine HCl
salt that had formed in the reaction mixture. The solution was
diluted with 100 ml t-butyl methyl ether and any unreacted pyridine
was removed by washing with dilute HCl solution (1N, 50
ml.times.2). The solution was further washed with brine and dried
by MgSO.sub.4. The t-butyl methyl ether solvent was removed by
rotary evaporation. 3.85 g of a viscous, slightly yellow product
was obtained. Yield: 57%. The product was analyzed using IR
spectroscopy.
Example 3
Synthesis of Glycerol Tridecanoate
[0073] Glycerol (0.953 g, FW. 92.09) and decanoyl chloride (5.933
g, FW. 190.71) were weighed in a 50 ml flask and cooled down in an
ice bath. Pyridine (3.0 g, FW. 79.1) was slowly added drop-wise to
the flask while stirring. The reaction mixture turned slightly
yellow. After 10 minutes the mixture was filtered to remove
pyridine HCl salt that had formed in the reaction mixture. The
solution was diluted with 100 ml t-butyl methyl ether and any
unreacted pyridine was removed by washing with dilute HCl solution
(1N, 50 ml.times.2). The solution was further washed with brine and
dried by MgSO.sub.4. The t-butyl methyl ether solvent was removed
by rotary evaporation. 4.63 g of a viscous, slightly yellow product
was obtained. Yield: 68%. The product was analyzed using IR
spectroscopy.
Example 4
Synthesis of C.sub.6/C.sub.8 Glycerol Ester
[0074] Glycerol (10 g, FW. 92.09), octanoyl chloride (35.32 g) and
hexanoyl chloride (14.61) were weighed in a 500 ml flask and cooled
down in an ice bath. Pyridine (31.6 g, FW. 79) was added slowly
drop-wise to the flask while stirring. The reaction mixture turned
slightly yellow. The reaction mixture was stirred for 16 hours at
room temperature. The solution was diluted with 200 ml t-butyl
methyl ether and stirred for 18 hours. The mixture was filtered to
remove pyridine HCl salt that had formed in the reaction mixture.
Any unreacted pyridine was removed by washing with dilute HCl
solution (1N, 150 ml.times.2). The solution was further washed with
brine (1.times.150 ml) and dried by MgSO.sub.4. The t-butyl methyl
ether solvent was removed by rotary evaporation and the product was
dried at 160.degree. C. for 3 hours. 4.63 g of a viscous, slightly
yellow product was obtained. Yield: 68%. The product was analyzed
using IR spectroscopy. The pour point of the product was
-45.degree. C.
[0075] The physical and chemical properties of these products are
shown in Table 1.
TABLE-US-00002 TABLE 1 (lubricant properties of glycerol esters)
Glycerol Kv.sub.40 Kv.sub.100 Sample # Ester (cSt) (cSt) VI Example
1 C.sub.8-Ester 13.80 3.29 108 Example 2 C.sub.9-Ester 16.72 3.84
124 Example 3 C.sub.10-Ester 24.45 4.89 125 Example 4
C.sub.6/C.sub.8 Ester 12.43 2.97 94
[0076] The viscosities of the neat glycerol esters are generally
low. For example, the polar C.sub.8-ester has a Kv.sub.100 of 3.29
cSt and a high viscosity index of 108. The C.sub.9-ester has a
Kv.sub.100 of 3.84 cSt (<4 cSt) and a VI of 124.
Preparation of Tri-esters Using Glycerol and Saturated Organic
Acids
Examples 5-8
Synthesis of Glycerol Tri-esters
[0077] Glycerol tri-esters were prepared by reacting glycerol and
various saturated organic acids (Example 4: Cekanoic C.sub.7 acid,
Example 5: LION C.sub.7 acid, Example 6: Cekanoic C.sub.8 acid and
Example 7: Cekanoic C.sub.9 acid) in the presence of titanium
tetra-isopropoxide as the catalyst. These organic acids have slight
branching in their compositions. The physical and chemical
properties of these products are shown in Table 2.
TABLE-US-00003 TABLE 2 (lubricant properties of glycerol esters)
Glycerol Kv.sub.40 Kv.sub.100 Pour Point Sample # Ester (cSt) (cSt)
VI (.degree. C.) Example 5 C.sub.7-Ester 10.13 2.69 102 -75 Example
6 C.sub.7-Ester 12.97 3.08 92 -66 Example 7 C.sub.8-Ester 17.52
3.69 92 -63 Example 8 C.sub.9-Ester 32.72 5.47 102 -45
[0078] The glycerol tri-esters showed high VI and very low pour
points.
[0079] Other compositions can be synthesized to optimize lube
properties (linear vs. branched) and using various carbon length
acids, i.e. C.sub.7, C8, C.sub.9, etc. or mixed acids.
EXAMPLES OF BLENDS OF THE PRESENT DISCLOSURE
[0080] Blend properties of various hydrocarbon base stocks like
PAO, Group III, and glycerol esters are shown in Table 3 below. The
glycerol esters were blended with hydrocarbon fluids in the wt %
ratio of 20:80. All the blend samples were clear and bright, which
suggests that these two types of base stocks are miscible in each
other. The viscosities, viscosity index (VI), and pour point
temperatures are shown in the tables. The test methods for
Kv.sub.100 and Kv.sub.40 was ASTM D445, for viscosity index (VI)
was ASTM D2270 and for pour point (PP) was ASTM D97.
TABLE-US-00004 TABLE 3 Blend Base Stock ratio Kv.sub.100 Kv.sub.40
PP Type (wt %) (cSt) (cSt) VI (.degree. C.) Hydrocarbon Base Stock
Data PAO-6.sup.1 100:0 5.50 28.50 132 -54.0 PAO 150.sup.2 100:0
153.3 1675 205 -39 Group III 100:0 3.87 16.21 137 -27.0 Glycerol
Tri-ester Data C.sub.8-glycerol 0:100 3.29 13.80 108 -31.0 ester
C.sub.8/C.sub.10- 0:100 3.48 14.73 115 -19.0 glycerol ester
C.sub.6/C.sub.8 0:100 2.97 12.43 94 -45.0 glycerol ester Blend Data
PAO-6/C.sub.8- 80:20 5.09 25.55 130 -39.0 Ester PAO150/C.sub.8-
80:20 64.85 577 187 -36 Ester Group III/C.sub.8- 80:20 3.56 14.83
124 -27 Ester PAO-6/ 80:20 5.20 26.16 132 -36
C.sub.8/C.sub.10-Ester PAO150/ 80:20 65.40 602.61 183 -21
C.sub.8/C.sub.10 Ester Group III/ 80:20 3.67 15.23 130 -33
C.sub.8/C.sub.10 Ester PAO-6/ 80:20 4.85 24.83 119 -54
C.sub.6/C.sub.8 Ester PAO150/ 80:20 63.78 579.7 183 -42
C.sub.6/C.sub.8 Ester Group III/ 80:20 3.50 14.65 120 -30
C.sub.6/C.sub.8 Ester .sup.1PAO-6 is low viscosity SpectraSyn .TM.
6 polyalpholefin (PAO) commercially available from ExxonMobil
Chemical. .sup.2PAO 150 is prepared according to U.S. Published
Patent Application No. 2008/0177121.
[0081] The viscosity indices (VI) of the blends are high. The
viscosity of high-VI fluids changes less dramatically with changes
in temperature compared with the viscosity change of low-VI fluids.
A practical consequence of this property is that a high-VI fluid
may not need a viscosity index improver (VII) in some applications.
The presence of a VII is often undesirable because many tend to be
unstable toward shear. Once the VII begins to break down, the fully
formulated fluid goes "out of grade" (i.e., fails to retain the
original viscosity grade).
[0082] All products have very low pour points. The property of low
pour point makes the fluid very attractive in the cold-climate
applications.
[0083] While the present disclosure has been described and
illustrated by reference to particular embodiments, those of
ordinary skill in the art will appreciate that the disclosure lends
itself to variations not necessarily illustrated herein. For this
reason, then, reference should be made solely to the appended
claims for purposes of determining the true scope of the present
disclosure.
* * * * *