U.S. patent application number 11/069979 was filed with the patent office on 2006-09-07 for polyalphaolefin & fischer-tropsch derived lubricant base oil lubricant blends.
This patent application is currently assigned to Chevron U.S.A. Inc.. Invention is credited to Robert J. Farina, Brent K. Lok, Joseph M. Pudlak, John M. Rosenbaum, James N. Ziemer.
Application Number | 20060196807 11/069979 |
Document ID | / |
Family ID | 36941889 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196807 |
Kind Code |
A1 |
Rosenbaum; John M. ; et
al. |
September 7, 2006 |
Polyalphaolefin & Fischer-Tropsch derived lubricant base oil
lubricant blends
Abstract
Blended lubricant base oils and blended finished lubricants
comprising .gtoreq.70 weight percent Fischer-Tropsch derived
lubricant base oils comprising .gtoreq.6 weight % molecules with
monocycloparaffinic functionality and less than 0.05 weight %
molecules with aromatic functionality; at least one polyalphaolefin
lubricant base oil with a kinematic viscosity at 100.degree. C.
greater than about 30 cSt and less than 150 cSt are provided. These
blended lubricant base oils and blended finished lubricants exhibit
superior friction and wear properties, in addition to other highly
desired properties. Also provided are processes for making these
blended lubricant base oils and blended finished lubricants.
Inventors: |
Rosenbaum; John M.;
(Richmond, CA) ; Lok; Brent K.; (San Francisco,
CA) ; Pudlak; Joseph M.; (Vallejo, CA) ;
Ziemer; James N.; (Martinez, CA) ; Farina; Robert
J.; (Richmond, CA) |
Correspondence
Address: |
BUCHANAN INGERSOLL PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Chevron U.S.A. Inc.
San Ramon
CA
|
Family ID: |
36941889 |
Appl. No.: |
11/069979 |
Filed: |
March 3, 2005 |
Current U.S.
Class: |
208/19 ; 208/27;
508/322; 508/363; 508/371; 508/433; 508/441; 508/591 |
Current CPC
Class: |
C10N 2030/02 20130101;
C10N 2040/253 20200501; C10N 2040/255 20200501; C10N 2030/06
20130101; C10M 111/04 20130101; C10N 2040/04 20130101; C10N 2010/12
20130101; C10N 2040/12 20130101; C10N 2030/10 20130101; C10N
2040/252 20200501; C10N 2030/74 20200501; C10N 2040/25 20130101;
C10N 2050/10 20130101; C10M 2223/043 20130101; C10N 2040/08
20130101; C10N 2040/30 20130101; C10M 2205/173 20130101; C10M
2219/068 20130101; C10M 2205/0285 20130101; C10M 169/04 20130101;
C10M 2223/042 20130101; C10M 2223/049 20130101; C10M 2223/045
20130101; C10M 2219/062 20130101; C10M 2205/0285 20130101; C10N
2020/02 20130101; C10M 2205/173 20130101; C10N 2020/02 20130101;
C10M 2205/0285 20130101; C10N 2020/02 20130101; C10M 2205/173
20130101; C10N 2020/02 20130101 |
Class at
Publication: |
208/019 ;
208/027; 508/591; 508/371; 508/363; 508/441; 508/433; 508/322 |
International
Class: |
C10M 111/04 20060101
C10M111/04 |
Claims
1. A blended lubricant base oil comprising: a. .gtoreq.70 weight %
Fischer-Tropsch derived lubricant base oil comprising .gtoreq.6
weight % molecules with monocycloparaffinic functionality and less
than 0.05 weight % molecules with aromatic functionality; and b. at
least one polyalphaolefin lubricant base oil with a kinematic
viscosity at 100.degree. C. greater than about 30 cSt and less than
150 cSt.
2. The blended lubricant base oil of claim 1, wherein the
Fischer-Tropsch derived lubricant base oil comprises a weight
percent of molecules with cycloparaffinic functionality of greater
than 10, and a ratio of weight percent of molecules with
monocycloparaffinic functionality to weight percent of molecules
with multicycloparaffinic functionality greater than 15.
3. The blended lubricant base oil of claim 1, wherein the
Fischer-Tropsch derived lubricant base oil comprises a weight
percent of molecules with aromatic functionality less than
0.01.
4. The blended lubricant base oil of claim 1, wherein the
Fischer-Tropsch derived lubricant base oil comprises .gtoreq.10
weight % of molecules with monocycloparaffinic functionality.
5. The blended lubricant base oil of claim 1, wherein the
difference in the kinematic viscosities at 100.degree. C. of the
Fischer-Tropsch derived lubricant base oil and the polyalphaolefin
lubricant base oil is greater than 40 cSt.
6. The blended lubricant base oil of claim 5, wherein the
difference in the kinematic viscosities at 100.degree. C. of the
Fischer-Tropsch derived lubricant base oil and the polyalphaolefin
lubricant base oil is greater than 70 cSt.
7. A blended finished lubricant comprising: a. .gtoreq.70 weight %
Fischer-Tropsch derived lubricant base oil comprising .gtoreq.6
weight % molecules with monocycloparaffinic functionality and less
than 0.05 weight % molecules with aromatic functionality; b. at
least one polyalphaolefin lubricant base oil having a kinematic
viscosity at 100.degree. C. greater than about 30 cSt and less than
150 cSt; and c. an effective amount of at least one anti-wear
additive.
8. The blended finished lubricant of claim 7, wherein the
Fischer-Tropsch derived lubricant base oil comprises a weight
percent of molecules with aromatic functionality of less than 0.05,
a weight percent of molecules with cycloparaffinic functionality of
greater than 10, and a ratio of weight percent of molecules with
monocycloparaffinic functionality to weight percent of molecules
with multicycloparaffinic functionality greater than 15.
9. The blended finished lubricant of claim 7, wherein the
Fischer-Tropsch derived lubricant base oil comprises a weight
percent of molecules with aromatic functionality less than
0.01.
10. The blended finished lubricant of claim 7, wherein the
Fischer-Tropsch derived lubricant base oil comprises .gtoreq.8
weight % molecules with monocycloparaffinic functionality.
11. The blended finished lubricant of claim 10, wherein the
Fischer-Tropsch derived lubricant base oil comprises .gtoreq.10
weight % molecules with monocycloparaffinic functionality.
12. The blended finished lubricant of claim 7, wherein the
effective amount of at least one anti-wear additive is between
0.001 and 5 weight %.
13. The blended finished lubricant of claim 7, wherein the blended
finished lubricant has a kinematic viscosity between about 2.0 and
20 cSt at 100.degree. C.
14. The blended finished lubricant of claim 7, wherein the blended
finished lubricant has a Noack volatility of less than 12 weight
%.
15. The blended finished lubricant of claim 7, wherein the blended
finished lubricant has an Oxidator B with L-4 Catalyst test result
of greater than 22 hours.
16. The blended finished lubricant of claim 7, wherein the blended
finished lubricant has a TEOST-MHT total deposit weight of less
than or equal to about 45 milligrams.
17. The blended finished lubricant of claim 7, wherein the blended
finished lubricant has a viscosity index greater than 165.
18. The blended finished lubricant of claim 7, wherein the blended
finished lubricant exhibits an HFRR Wear Volume Below the Plane of
less than or equal to 300,000 cubic microns.
19. The blended finished lubricant of claim 7, wherein the at least
one anti-wear additive is selected from the group consisting of
metal phosphates, metal dithiophosphates, metal
dialkyldithiophosphates, metal thiocarbamates, metal
dithiocarbamates, metal dialkyldithiocarbamates, ethoxylated amine
dialkyldithiophosphates, ethoxylate amine dithiobenzoates, neutral
organic phosphites, organo-molybdenum compounds, organo-sulfur
compounds, sulfur compounds, chlorine compounds, and mixtures
thereof.
20. The blended finished lubricant of claim 7, further comprising
at least one additional lubricant additive selected from the group
consisting of EP agents, detergents, dispersants, antioxidants,
pour point depressants, viscosity index improvers, ester
co-solvents, viscosity modifiers, friction modifiers, demulsifiers,
antifoaming agents, corrosion inhibitors, rust inhibitors, seal
swell agents, emulsifiers, wetting agents, lubricity improvers,
metal deactivators, gelling agents, tackiness agents, bactericides,
fluid-loss additives, colorants, and mixtures thereof.
21. The blended finished lubricant of claim 20, wherein the
finished lubricant is a multigrade internal combustion engine
crankcase oil, a transmission oil, a power train fluid, a turbine
oil, a compressor oil, a hydraulic oil, or a grease.
22. The blended finished lubricant of claim 21, wherein the blended
finished lubricant is a multigrade internal combustion engine
crankcase oil meeting SAE J300, June 2001, specifications.
23. The blended finished lubricant of claim 22, wherein the
internal combustion engine crankcase oil meets the specifications
for an engine oil having a viscosity grade of 0W-20, 5W-XX, 10W-XX,
or 15W-XX wherein XX is 20, 30, 40, 50 or 60.
24. The blended finished lubricant of claim 22, wherein the
internal combustion engine crankcase oil meets the specifications
for at least one ACEA 2002 European Oil Sequences for gasoline
engines, light duty diesel engines, or heavy duty diesel
engines.
25. The blended finished lubricant of claim 7, wherein the
effective amount of at least one anti-wear additive is less than
the effective amount of anti-wear additive in a finished lubricant
comprising Fischer-Tropsch derived lubricant base oil in the
absence of a polyalphaolefin lubricant base oil.
26. The blended finished lubricant of claim 7, wherein the
effective amount of at least one anti-wear additive is less than
the effective amount of anti-wear additive in a finished lubricant
comprising polyalphaolefin lubricant base oil in the absence of a
Fischer-Tropsch derived lubricant base oil.
27. A method of operating an internal combustion engine having a
valve train, comprising: a. lubricating the engine using the
blended finished lubricant of claim 7; and b. operating the engine
using a fuel.
28. The method of claim 27, wherein the engine is a compression
ignition engine or a spark ignition engine and the fuel is a diesel
fuel, a low sulfur diesel fuel, a gasoline fuel, an unleaded
gasoline, or natural gas.
29. A method for reducing wear in ferrous alloy equipment,
comprising: a. lubricating the equipment with the blended finished
lubricant of claim 7; and b. operating the equipment after the
lubricating.
Description
[0001] The present invention is directed to blended lubricants and
blended finished lubricants comprising a Fischer-Tropsch derived
lubricant base oil and at least one polyalphaolefin lubricant base
oil and processes for making the same. The blended finished
lubricants require surprisingly less anti-wear additives to achieve
acceptable wear performance than required for Fisher-Tropsch
derived lubricant base oils in the absence of at least one
polyalphaolefin (PAO) lubricant base oil.
BACKGROUND OF THE INVENTION
[0002] High performance automotive and industrial lubricants are in
demand. Accordingly, lubricant manufacturers must provide finished
lubricants that exhibit high performance properties. To produce
these finished lubricants lubricant manufacturers are seeking
higher quality lubricant base oil blend stocks. Performance
characteristics that are significant include additive solubility,
deposit control, and lubricity.
[0003] A growing source of these high quality lubricant base oil
blend stocks is synthetic lubricants. Synthetic lubricants include
Fischer-Tropsch derived lubricant base oils and polyalphaolefins.
Polyalphaolefins are synthetic lubricant base oils produced by a
chemical polymerization process. However, these lubricant base oils
are expensive to produce. In the search for high performance
lubricants, attention has recently been focused on Fischer-Tropsch
derived lubricants. Although Fischer-Tropsch derived lubricant base
oils are desirable for their biodegradability and low amounts of
undesirable impurities such as sulfur, the Fischer-Tropsch derived
lubricants generally do not exhibit desirable wear performance,
lubricity, and deposit performance. Although it is well known in
the art to improve these performance characteristics through the
use of additives, these additives are generally expensive and thus,
can significantly increase the cost of the lubricant base oil. In
addition, engine manufacturers worldwide are considering low sulfur
and phosphorus limits on engine oils and additives because it is
believed that these limits will provide the safe margins for
operation of aftertreatment hardware. Antiwear additives often
contain significant amounts of both sulfur and phosphorus.
Therefore, it is desirable to produce lubricant base oils with high
performance characteristics without the significant use of
expensive additives, or with reduced amounts of additives that
contain sulfur and phosphorus.
[0004] It is well known in the art to produce synthetic lubricants
and there have been many developmental attempts at producing
synthetic lubricants with high performance characteristics. By way
of example, U.S. Pat. No. 6,008,164; U.S. Pat. No. 6,080,301; U.S.
Pat. No. 6,165,949; WO 00/14188; WO 02/064710 A2; WO 02/064711 A1;
WO 02/070629 A1; and WO 02/070636 A1 are directed to synthetic
lubricant compositions and methods for producing the lubricating
base stocks.
[0005] There has also been research into the properties of
hydrocracked base stocks and polyalphaolefins. "The Influence of
Chemical Structure on the Physical Properties and Antioxidant
Response of Hydrocracked Base Stocks and Polyalphaolefins," by V.
J. Gatto et al., J. Synthetic Lubrication 19-1, April 2002 (19),
3-18, discloses the effect of hydrocracked base stock chemical
composition on lubricant properties, oxidation performance, and
antioxidant additive response. In this study fifteen hydrocracked
base stocks and polyalphaolefins were analyzed.
[0006] In spite of the above research into synthetic lubricants,
there remains a need for synthetic lubricants comprising
Fischer-Tropsch derived lubricant base oils that exhibit high
performance including improved friction and wear properties,
without requiring the addition of large amounts of additives to
achieve this high performance.
SUMMARY OF THE INVENTION
[0007] It has been discovered that the blended lubricant base oils
and blended finished lubricants of the present invention,
comprising Fischer-Tropsch derived lubricant base oils and
polyalphaolefins, exhibit improved friction and wear properties
with reduced amounts of anti-wear additives.
[0008] In one embodiment, the present invention relates to a
blended lubricant base oil. The blended lubricant base oil of the
present invention comprises .gtoreq.70 weight percent
Fischer-Tropsch derived lubricant base oil comprising .gtoreq.6
weight percent molecules with monocycloparaffinic functionality and
less than 0.05 weight percent molecules with aromatic
functionality; and at least one polyalphaolefin lubricant base oil
with a kinematic viscosity at 100.degree. C. greater than about 30
cSt and less than 150 cSt.
[0009] In another embodiment, the present invention relates to a
blended finished lubricant. The blended finished lubricant
comprises .gtoreq.70 weight percent Fischer-Tropsch derived
lubricant base oil comprising .gtoreq.6 weight percent molecules
with monocycloparaffinic functionality and less than 0.05 weight
percent molecules with aromatic functionality; at least one
polyalphaolefin lubricant base oil having a kinematic viscosity at
100.degree. C. greater than about 30 cSt and less than 150 cSt; and
an effective amount of at least one anti-wear additive.
[0010] In another embodiment, the present invention relates to a
method of operating an internal combustion engine comprising a
valve train. The method comprises operating the engine using fuel
and lubricating the engine using a blended finished lubricant
comprising .gtoreq.70 weight percent Fischer-Tropsch derived
lubricant base oil comprising .gtoreq.6 weight percent molecules
with monocycloparaffinic functionality and less than 0.05 weight
percent molecules with aromatic functionality, at least one
polyalphaolefin lubricant base oil having a kinematic viscosity at
100.degree. C. greater than about 30 cSt and less than 150 cSt; and
an effective amount of at least one anti-wear additive.
[0011] In yet another embodiment, the present invention relates to
a method of reducing wear in ferrous alloy equipment. The method
comprises lubricating the equipment with a blended finished
lubricant comprising .gtoreq.70 weight percent Fischer-Tropsch
derived lubricant base oil comprising .gtoreq.6 weight percent
molecules with monocycloparaffinic functionality and less than 0.05
weight percent molecules with aromatic functionality, at least one
polyalphaolefin lubricant base oil having a kinematic viscosity at
100.degree. C. greater than about 30 cSt and less than 150 cSt; and
an effective amount of at least one anti-wear additive; and
operating the equipment after the lubricating.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Finished lubricants comprise at least one lubricant base oil
and at least one additive. Lubricant base oils are the most
important component of finished lubricants, generally comprising
greater than 70% of the finished lubricants. Finished lubricants
may be used in automobiles, diesel engines, axles, transmissions,
and industrial applications. Finished lubricants must meet the
specifications for their intended application as defined by the
concerned governing organization.
[0013] A Fischer-Tropsch derived lubricant base oil is a base oil
derived at least in part from a Fischer-Tropsch process. The
blended lubricants according to the present invention comprise at
least one Fischer-Tropsch derived lubricant base oil comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
and less than 0.05 weight % molecules with aromatic functionality,
and at least one polyalphaolefin lubricant base oil having a
kinematic viscosity greater than about 30 cSt and less than 150 cSt
at 100.degree. C. The blended finished lubricants of the present
invention comprise at least one Fischer-Tropsch derived lubricant
base oil comprising .gtoreq.6 weight % molecules with
monocycloparaffinic functionality and less than 0.05 weight %
molecules with aromatic functionality; at least one polyalphaolefin
lubricant base oil having a kinematic viscosity at 100.degree. C.
greater than about 30 cSt and less than 150 cSt, and an effective
amount of at least one antiwear additive. The blended finished
lubricants of the present invention exhibit exceptional friction
and wear properties. Preferably, the blended lubricant base oil
comprises .gtoreq.70 weight percent Fischer-Tropsch derived
lubricant base oil.
[0014] In general, the effective amount of anti-wear additive
needed in a finished lubricant comprising a Fischer-Tropsch derived
lubricant base oil is less than that required in a finished
lubricant comprising a conventional petroleum lubricant base oil or
a polyalphaolefin lubricant base oil. According to the present
invention, it has been surprisingly discovered that significantly
less anti-wear additive is required for a finished lubricant
comprising a Fischer-Tropsch derived lubricant base oil comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
and less than 0.05 weight % molecules with aromatic functionality
blended with a polyalphaolefin lubricant base oil having a
kinematic viscosity at 100.degree. C. greater than about 30 cSt and
less than 150 cSt than in a finished lubricant comprising a
Fischer-Tropsch derived lubricant base oil in the absence of a
polyalphaolefin lubricant base oil. Accordingly, in the blended
finished lubricants of the present invention, a reduced amount of
anti-wear additive is needed. Thus, the blended lubricants of the
present invention can be used to make high quality engine oils and
other finished lubricants meeting the most stringent modern engine
oil specifications.
[0015] An effective amount of at least one anti-wear additive means
the amount of anti-wear additive that reduces the wear volume below
the plane in the HFRR test of this invention by at least 1,000
microns.sup.3 compared to the wear volume below the plane in the
absence of the additive. Preferably the effective amount of at
least one anti-wear additive means the amount of anti-wear additive
in an additive package or individually added to the blended
lubricant base oil to provide a finished lubricant with an High
Frequency Reciprocating Rig (HFRR) wear volume below the plane with
1000 g applied load of less than 460,000 microns.sup.3, preferably
less than 350,000 microns.sup.3. According to the present
invention, preferably an effective amount of at least one anti-wear
additive is 0.001 to 5 weight % of the blended finished lubricant.
The effective amount of anti-wear additive in the blended finished
lubricants of the present invention is less than the effective
amount of anti-wear additive required in a lubricant comprising a
Fischer-Tropsch derived lubricant base oil with the preferred
composition of this invention in the absence of a polyalphaolefin
lubricant base oil having a kinematic viscosity greater than about
30 cSt and less than 150 cSt at 100.degree. C. The effective amount
of anti-wear additive in the blended finished lubricants of this
invention is less than the effective amount of antiwear additive
required in a lubricant comprising polyalphaolefin lubricant base
oil having a kinematic viscosity of greater than about 30 cSt and
less than 150 cSt at 100.degree. C. in the absence of the
Fischer-Tropsch derived lubricant base oil of the present
invention.
[0016] Many finished lubricant specifications include limits on
wear. Examples of specifications that include test limits on wear
are: API Passenger Car Engine Test Categories SJ and SL; ACEA 2002
European Oil Sequences for Gasoline, Light Duty Diesel, and Heavy
Duty Diesel Engines; ASTM D4950 Grease Categories;
Cincinnati-Milacron P-68 Hydraulic Fluid Specifications; and
General Motors C-4 Automatic Transmission Fluid Specifications.
[0017] The blended lubricants and the blended finished lubricants
according to the present invention comprise a polyalphaolefin
lubricant base oil with a kinematic viscosity of greater than about
30 cSt at 100.degree. C., and less than 150 cSt at 100.degree. C.
The polyalphaolefin lubricant base oil may be obtained commercially
or synthesized as described in Shubkin, Ronald L. (1993)
Polyalphaolefins, in Synthetic Lubricants and High-Performance
Functional Fluids, and Pernik, Mark G. (2002) Polyalphaolefins,
STLE Annual Meeting, Houston Tex., Synthetic Lubricants Course.
Polyalphaolefin base oils with kinematic viscosities greater than
about 30 cSt and less than 150 cSt at 100.degree. C. are
commercially available from a number of manufacturers, including
Chevron Phillips, British Petroleum, and ExxonMobil.
[0018] The blended lubricant base oils and the blended finished
lubricants according to the present invention comprise a
Fischer-Tropsch derived lubricant base oil comprising .gtoreq.6
weight % molecules with monocycloparaffinic fimctionality,
preferably .gtoreq.8 weight % molecules with monocycloparaffinic
functionality, and even more preferably .gtoreq.10 weight %
molecules with monocycloparaffinic functionality.
[0019] The blended lubricant base oils and the blended finished
lubricants according to the present invention comprise a
Fischer-Tropsch derived lubricant base oil comprising very low
weight percent of molecules with aromatic functionality, a high
weight percent of molecules with cycloparaffinic functionality, and
a high ratio of weight percent of molecules containing
monocycloparaffinic functionality to weight percent of molecules
containing multicycloparaffinic functionality (or high weight
percent of molecules with monocycloparaffinic functionality and
very low weight percents of molecules with multicycloparaffinic
functionality), as described in U.S. Ser. No. 10/744389, filed Dec.
23, 2003, U.S. Ser. No. 10/744870, filed Dec. 23, 2003, and U.S.
Ser. No. 10/743,932, filed Dec. 23, 2003, herein incorporated by
reference in their entirety.
[0020] In a preferred embodiment, the blended lubricant base oils
and the blended finished lubricants according to the present
invention comprise a Fischer-Tropsch derived lubricant base oil
comprising a weight percent of molecules with aromatic
functionality of less than 0.05, a weight percent of molecules with
cycloparaffinic functionality of greater than 10, and a high ratio
of weight percent of molecules with monocycloparaffinic
functionality to weight percent of molecules with
multicycloparaffinic functionality, preferably greater than 15. In
another preferred embodiment, the blended lubricant base oils and
the blended finished lubricants according to the present invention
comprise a Fischer-Tropsch derived lubricant base oil comprising a
weight percent of molecules with aromatic functionality less than
0.01, and more preferably less than 0.008.
[0021] The Fischer-Tropsch derived lubricant base oils comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
are prepared from the waxy fractions of the Fischer-Tropsch
syncrude by a process including hydroisomerization. The
Fischer-Tropsch derived lubricant base oils used in the blended
lubricants and blended finished lubricants are made by a process
comprising performing a Fischer-Tropsch synthesis to provide a
product stream; isolating from the product stream a substantially
paraffinic wax feed; hydroisomerizing the substantially paraffinic
wax feed; isolating an isomerized oil; and optionally
hydrofinishing the isomerized oil. From the process, a
Fischer-Tropsch derived lubricant base oil comprising .gtoreq.6
weight % molecules with monocycloparaffinic functionality and less
than 0.05 weight % molecules with aromatic functionality is
isolated. The above-recited preferred embodiments of the
Fischer-Tropsch derived lubricant base oil also may be isolated
from the process. Preferably, the substantially paraffinic wax feed
is hydroisomerized using a shape selective intermediate pore size
molecular sieve comprising a noble metal hydrogenation component
under conditions of about 600.degree. F. to 750.degree. F.
Preferred processes for making the Fischer-Tropsch derived
lubricant base oils are described in U.S. Ser. No. 10/744,389,
filed Dec. 23, 2003, and U.S. Ser. No. 10/744,870, filed Dec. 23,
2003, herein incorporated by reference in their entirety.
[0022] According to the present invention, it is desired that the
blended lubricant base oils and the blended finished lubricants
comprise Fischer-Tropsch derived lubricant base oils containing
high weight percents of molecules with cycloparaffinic
functionality because cycloparaffins impart additive solubility and
elastomer compatibility. Blended lubricant base oils and blended
finished lubricants comprising Fischer-Tropsch derived lubricant
base oils containing very high ratios of weight percent of
molecules with monocycloparaffinic functionality to weight percent
of molecules with multicycloparaffinic functionality (or high
weight percent of molecules with monocycloparaffinic functionality
and extremely low weight percent of molecules with
multicycloparaffinic functionality) are also desirable because
molecules with multicycloparaffinic functionality reduce oxidation
stability, lower viscosity index, and increase Noack volatility.
Models of the effects of molecules with multicycloparaffinic
functionality are given in V. J. Gatto, et al, "The Influence of
Chemical Structure on the Physical Properties and Antioxidant
Response of Hydrocracked Base Stocks and Polyalphaolefins," J.
Synthetic Lubrication 19-1, April 2002, pp 3-18.
[0023] The blended lubricants of the present invention comprise
between 70 and about 99 weight % Fischer-Tropsch derived lubricant
base oil and about 1 to less than 30 weight % polyalphaolefin
lubricant base oil. The blended finished lubricants of the present
invention comprise between 70 and about 99 weight % Fischer-Tropsch
derived lubricant base oil, between about 1 and 30 weight %
polyalphaolefin lubricant base oil, and between 0.001 and 5 weight
% anti-wear additive(s). Preferably, the finished lubricant
comprises between 0.001 and 4 weight % anti-wear additive(s).
Definitions
[0024] The following terms will be used throughout the
specification and will have the following meanings unless otherwise
indicated.
[0025] The term "derived from a Fischer-Tropsch process" or
"Fischer-Tropsch derived," means that the product, fraction, or
feed originates from or is produced at some stage by a
Fischer-Tropsch process.
[0026] Aromatic group means any hydrocarbonaceous compound or group
containing at least one group of atoms that share an uninterrupted
cloud of delocalized electrons, where the number of delocalized
electrons in the group of atoms corresponds to a solution to the
Huckel rule of 4n+2 (e.g., n=1 for 6 electrons, etc.).
Representative examples include, but are not limited to, benzene,
biphenyl, naphthalene, and the like.
[0027] Molecules with aromatic functionality mean any molecule that
is, or contains as one or more substituents, an aromatic group.
[0028] Molecules with cycloparaffinic functionality mean any
molecule that is, or contains as one or more substituents, a
monocyclic or a fused multicyclic saturated hydrocarbon group. The
cycloparaffinic group may be optionally substituted with one or
more, preferably one to three, substituents. Representative
examples include, but are not limited to, cyclopropyl, cyclobutyl,
cyclohexyl, cyclopentyl, cycloheptyl, decahydronaphthalene,
octahydropentalene, (pentadecan-6-yl)cyclohexane,
3,7,10-tricyclohexylpentadecane,
decahydro-1-(pentadecan-6-yl)naphthalene, and the like.
[0029] Molecules with monocycloparaffinic functionality mean any
molecule that is a monocyclic saturated hydrocarbon group of three
to seven ring carbons or any molecule that is substituted with a
single monocyclic saturated hydrocarbon group of three to seven
ring carbons. The cycloparaffinic group may be optionally
substituted with one or more, preferably one to three,
substituents. Representative examples include, but are not limited
to, cyclopropyl, cyclobutyl, cyclohexyl, cyclopentyl, cycloheptyl,
(pentadecan-6-yl)cyclohexane, and the like.
[0030] Molecules with multicycloparaffinic functionality mean any
molecule that is a fused multicyclic saturated hydrocarbon ring
group of two or more fused rings, any molecule that is substituted
with one or more fused multicyclic saturated hydrocarbon ring
groups of two or more fused rings, or any molecule that is
substituted with more than one monocyclic saturated hydrocarbon
group of three to seven ring carbons. The fused multicyclic
saturated hydrocarbon ring group preferably is of two fused rings.
The cycloparaffinic group may be optionally substituted with one or
more, preferably one to three, substituents. Representative
examples include, but are not limited to, decahydronaphthalene,
octahydropentalene, 3,7,10-tricyclohexylpentadecane,
decahydro-1-(pentadecan-6-yl)naphthalene, and the like.
[0031] "Compression ignition internal combustion engines" mean
diesel engines.
[0032] "Internal Combustion Engine" is an engine, such as an
automotive gasoline piston engine or a diesel, in which fuel is
burned within the engine proper rather than in an external furnace,
as in a steam engine. These engines include natural gas engines,
diesel engines, and gasoline engines. They may be two-stroke or
four-stroke.
[0033] "Multigrade internal combustion engine crankcase oil" is a
lubricant meeting the specifications of SAE J300, June 2001. The
API classifies engine oil according to their SAE viscosity grades.
Table I below summarizes the classification. TABLE-US-00001 TABLE I
API Engine Oil Classification Maximum Low Minimum Maximum Maximum
Low Temperature Low-Shear-Rate Low-Shear-Rate Minimum SAE
Temperature Pumping Viscosity Kinematic Kinematic High-Shear-Rate
Viscosity Cranking with No Yield Viscosity at Viscosity at
Viscosity at Grade Viscosity, cP Stress, cP 100.degree. C., cSt
100.degree. C., cSt 150.degree. C., cP 0W-.sub.-- 6200 at
-35.degree. C. 60000 at -40.degree. C. 3.8 -- -- 5W-.sub.-- 6600 at
-30.degree. C. 60000 at -35.degree. C. 3.8 -- -- 10W-.sub.-- 7000
at -25.degree. C. 60000 at -30.degree. C. 4.1 -- -- 15W-.sub.--
7000 at -20.degree. C. 60000 at -25.degree. C. 5.6 -- --
20W-.sub.-- 9500 at -15.degree. C. 60000 at -20.degree. C. 5.6 --
-- 25W-.sub.-- 13000 at -10.degree. C. 60000 at -15.degree. C. 9.3
-- -- _W-20 -- -- 5.6 9.3 2.6 _W-30 -- -- 9.3 12.5 2.9 0W-40, -- --
12.5 16.3 2.9 5W-40, 10W-40 15W-40, -- -- 12.5 16.3 3.7 20W-40,
25W-40 _W-50 -- -- 16.3 21.9 3.7 _W-60 -- -- 21.9 26.1 3.7
An engine oil having a viscosity grade of 0W has a maximum low
temperature cranking viscosity of 6,200 cP at -35.degree. C., a
maximum low temperature pumping viscosity with no yield stress of
60,000 cP at -40.degree. C., and a minimum low-shear-rate kinematic
viscosity of 3.8 cSt at 100.degree. C. An engine oil having a
viscosity grade of 5W has a maximum low temperature cranking
viscosity of 6,600 cP at -30.degree. C., a maximum low temperature
pumping viscosity with no yield stress of 60,000 cP at -35.degree.
C., and a minimum low-shear-rate kinematic viscosity of 3.8 cSt at
100.degree. C. An engine oil having a viscosity grade of 10W has a
maximum low temperature cranking viscosity of 7,000 cP at
-25.degree. C., a maximum low temperature pumping viscosity with no
yield stress of 60,000 cP at -30.degree. C., and a minimum
low-shear-rate kinematic viscosity of 4.1 cSt at 100.degree. C. An
engine oil having a viscosity grade of 15W has a maximum low
temperature cranking viscosity of 7,000 cP at -20.degree. C., a
maximum low temperature pumping viscosity with no yield stress of
60,000 cP at -25.degree. C., and a minimum low-shear-rate kinematic
viscosity of 5.6 cSt at 100.degree. C.
[0034] "Spark ignition internal combustion engines" mean gasoline
engines.
[0035] "Valve train" in an internal combustion engine consists of
valves and a camshaft. Currently, there are two types of designs
used in the automobile engine for the placement of the valves and
camshaft. If the camshaft is located in the cylinder head, the
engine is called an overhead cam design; if the camshaft is located
in the engine block, the engine is called an overhead valve design.
Both designs have their valves mounted above the cylinders in the
cylinder head. It is the location of the camshaft, which operates
the valves, that distinguishes the two designs. A dual overhead cam
(DOHC) engine has two camshafts on each cylinder head; one camshaft
operates the intake valves, while the other one operates the
exhaust valves.
[0036] "Low-sulfur diesel fuel" has a sulfur content of up to about
0.05% by weight as determined by the test method specified in ASTM
D2622-87.
[0037] "Low-sulfur gasolines" have sulfur contents below about 300
ppm, or 0.03%.
[0038] The blended lubricant base oils and blended finished
lubricants according to the present invention exhibit desirable
properties in addition to exceptional friction and wear properties,
including high viscosity indexes, low Noack volatility, excellent
oxidation stability, and low pour points. Further benefits obtained
by the use of the finished lubricants of the present invention
include improved fuel economy, reduced wear of components of
engines, longer oil change intervals, less waste oil for disposal,
and reduced high temperature deposits.
Oxygen Stability Tests:
[0039] Oxidation stability was determined using two different test
methods, Oxidator BN and Oxidator B with L-4 Catalyst. Oxidator BN
was used to determine oxygen stability of the Fischer-Tropsch
derived lubricant base oils, which do not contain any additives. A
convenient way to measure the stability of lubricant base oils is
by the use of the Oxidator BN Test, as described by Stangeland et
al. in U.S. Pat. No. 3,852,207. The Oxidator BN test measures the
resistance to oxidation by means of a Dornte-type oxygen absorption
apparatus. See R. W. Dornte "Oxidation of White Oils," Industrial
and Engineering Chemistry, Vol. 28, page 26, 1936. Normally, the
conditions are one atmosphere of pure oxygen at 340.degree. F. The
results are reported in hours to absorb 1000 ml of O.sub.2 by 100 g
of oil. In the Oxidator BN test, 0.8 ml of catalyst is used per 100
grams of oil and an additive package is included in the oil. The
catalyst is a mixture of soluble metal naphthenates in kerosene.
The mixture of soluble metal naphthenates simulates the average
metal analysis of used crankcase oil. The level of metals in the
catalyst is as follows: Copper=6,927 ppm; Iron=4,083 ppm ;
Lead=80,208 ppm; Manganese=350 ppm; Tin=3565 ppm. The additive
package is 80 millimoles of zinc
bispolypropylenephenyldithio-phosphate per 100 grams of oil, or
approximately 1.1 grams of OLOA 260. The Oxidator BN test measures
the response of a lubricant base oil in a simulated application.
High values, or long times to absorb one liter of oxygen, indicate
good oxidation stability. Traditionally it is considered that the
Oxidator BN should be above 7 hours. For the present invention, the
Oxidator BN value will be greater than about 30 hours, preferably
greater than about 40 hours.
[0040] Oxidator B was used to determine oxygen stability of the
blended finished lubricants, which already contained an antioxidant
additive. The Oxidator B with L-4 Catalyst Test is a test measuring
resistance to oxidation by means of a Dornte-type oxygen absorption
apparatus (R. W. Dornte "Oxidation of White Oils," Industrial and
Engineering Chemistry, Vol. 28, page 26, 1936). Normally, the
conditions are one atmosphere of pure oxygen at 340.degree. F.,
reporting the hours to absorption of 1000 ml of O.sub.2 by 100 g of
oil. In the Oxidator B with L-4 Catalyst test, 0.8 ml of catalyst
is used per 100 grams of oil. The catalyst is a mixture of soluble
metal naphthenates in kerosene. The mixture of soluble metal
naphthenates simulates the average metal analysis of used crankcase
oil. The level of metals in the catalyst is as follows:
Copper=6,927 ppm; Iron=4,083 ppm; Lead=80,208 ppm; Manganese=350
ppm; Tin=3565 ppm. The Oxidator B with L-4 Catalyst Test measures
the response of a finished lubricant in a simulated application.
High values, or long times to adsorb one liter of oxygen, indicate
good stability. Generally, the Oxidator B with L-4 Catalyst Test
results should be above about 7 hours. Preferably, the Oxidator B
with L-4 value will be greater than about 10 hours. The blended
finished blends of the present invention have results much greater
than 10 hours. Preferably, the blended finished lubricants of the
present invention have an Oxidator B with L-4 Catalyst test result
of greater than 22 hours, even more preferably greater than 30
hours.
[0041] HFRR Wear Tests:
[0042] Wear tests were conducted on 1 ml oil samples using a High
Frequency Reciprocating Rig (HFRR) (PCS Instruments HFR2) using
SAE-AISI E-52100 6.00 mm diameter through-hardened balls (Grade 24
per ANSI B3.12, having a Rockwell hardness "C" scale number of
58-66, in accordance with the Test Method ASTM E 18, and a surface
finish of less than 0.05 microns RA); on polished SAE-AISI E-52100
10 mm flat disks, having a Vickers hardness "HV 30", in accordance
with Specification E 92, a Rockwell hardness "C" scale number of
190-210, turned, lapped, and polished to a surface finish of less
than 0.02 microns RA. AISI E-52100 is a ferrous alloy with a
typical elemental composition of: Carbon, 1.00%; Manganese, 0.35%;
Silicon, 0.25%; and Chromium, 1.50%. The test conditions were as
follows: frequency 20 Hz; applied load 1,000 g; stroke length 1 mm;
fluid temperature 120.degree. C., relative humidity greater than
30%, and test duration 200 minutes. The test is a modified version
of that described in ASTM D 6079.
[0043] Because of the extreme hardness differences between the
balls and disks, most of the material wear occurred on the disks in
the form of a 1 mm long hemispherical wear track. Consequently,
anti-wear performances were based solely on the amount of material
removed from the disks, and not the balls. Disk wear volume
measurements were made after first removing fine wear debris from
the surface of the disk with a cotton swab immersed in hexane and
then profiling a 1/24 mm.times.1.64 mm rectangular area of the
surface in the vicinity of the wear scar with a MicroXAM-100
3DSurface Profiler (ADE Phase Shift). A distinction was made
between the volume of material removed by adhesion (lubricant
released wear) from that displaced by abrasion (plowing) by first
leveling the disk's surface profile based on the flat regions
immediately adjacent to the wear scar using the MicroXAM's software
leveling routine, and then subtracting the volume of metal
protruding above the plane of the surface (abrasive) from the void
volume extending below the plane of the surface (adhesive). The
HFRR wear volumes from the void volume extending below the plane of
the surface and the HFRR net wear scar volumes were reported as
HFRR Wear Volume Below the Plane and HFRR Net Wear Volume,
respectively, in cubic microns. The volume precision measurement by
this technique is estimated to be .+-.10 microns.sup.3. All
lubricants were tested in duplicate and the results averaged.
[0044] Preferably, the finished lubricants of the present invention
exhibit an HFRR wear volume below the plane with 1,000 g applied
load of less than 300,000 microns.sup.3, more preferably less than
or equal to about 170,000 microns.sup.3, even more preferably less
than 150,000 microns.sup.3, and even more preferably less than
110,000 microns.sup.3. In addition, the finished lubricants of the
present invention exhibit a HFRR Net Wear Volume less than 100,000
microns.sup.3, preferably less than 50,000 microns.sup.3, and more
preferably less than 25,000 microns.sup.3.
Other Lubricant Tests:
[0045] Kinematic viscosity is a measurement of the resistance to
flow of a fluid under gravity. Many lubricant base oils, finished
lubricants made from them, and the correct operation of equipment
depends upon the appropriate viscosity of the fluid being used.
Kinematic viscosity is determined by ASTM D 445-01. The results are
reported in centistokes (cSt). The blended finished lubricants of
the present invention have a kinematic viscosity of between about
2.0 cSt and about 20 cSt at 100.degree. C.
[0046] Viscosity Index (VI) is an empirical, unitless number
indicating the effect of temperature change on the kinematic
viscosity of the oil. Liquids change viscosity with temperature,
becoming less viscous when heated; the higher the VI of an oil, the
lower its tendency to change viscosity with temperature. High VI
lubricants are needed wherever relatively constant viscosity is
required at widely varying temperatures. VI may be determined as
described in ASTM D 2270-93. Preferably, the blended finished
lubricants of the present invention have a viscosity index of
greater than 140, more preferably greater than 165.
[0047] Pour point is a measurement of the temperature at which a
sample of lubricant base oil will begin to flow under carefully
controlled conditions. Pour point may be determined as described in
ASTM D 5950-02. The results are reported in degrees Celsius. Many
commercial lubricant base oils have specifications for pour point.
When lubricant base oils have low pour points, they also are likely
to have other good low temperature properties, such as low cloud
point, low cold filter plugging point, and low temperature cranking
viscosity. Cloud point is a measurement complementary to the pour
point, and is expressed as a temperature at which a sample of the
lubricant base oil begins to develop a haze under carefully
specified conditions. Cloud point may be determined by, for
example, ASTM D 5773-95
[0048] Noack volatility is defined as the mass of oil, expressed in
weight %, which is lost when the oil is heated at 250.degree. C.
and 20 mmHg (2.67 kPa; 26.7 mbar) below atmospheric in a test
crucible through which a constant flow of air is drawn for 60
minutes, according to ASTM D5800. A more convenient method for
calculating Noack volatility and one which correlates well with
ASTM D5800 is by using a thermo gravimetric analyzer test (TGA) by
ASTM D6375. TGA Noack volatility is used throughout this disclosure
unless otherwise stated. Noack volatility of engine oil, as
measured by TGA Noack and similar methods, has been found to
correlate with oil consumption in passenger car engines. Strict
requirements for low volatility are important aspects of several
recent engine oil specifications, such as, for example, ACEA A-3
and B-3 in Europe and ILSAC GF-3 in North America. Preferably, the
blended finished lubricants of the present invention have a Noack
volatility of less than 12 weight %.
[0049] Cold-cranking simulator apparent viscosity (CCS VIS) is a
test used to measure the viscometric properties of lubricant base
oils under low temperature and high shear. CCS VIS may also be
referred to as low temperature cranking viscosity. The test method
to determine CCS VIS is ASTM D 5293-02, at a set temperature
between -5 and -35.degree. C. Results are reported in centipoise,
cP. CCS VIS has been found to correlate with low temperature engine
cranking. Specifications for maximum CCS VIS are defined for
automotive engine oils by SAE J300, revised in June 2001.
[0050] High Temperature High Shear rate viscosity (HTHS) measures a
fluid's resistance to flow under conditions resembling
highly-loaded journal bearings in fired internal combustion
engines, typically 1 million s.sup.-1 at 150.degree. C. HTHS is a
better indication of how an engine operates at high temperature
with a given lubricant than kinematic low shear rate viscosities at
100.degree. C. HTHS directly correlates to the oil film thickness
in a bearing. SAE J300 June '01 contains the current specifications
for HTHS measured by ASTM D 4683, ASTM D 4741, or ASTM D 5481.
[0051] Mini-Rotary Viscometer (MRV) relates to the mechanism of
pumpability and is a low shear rate measurement. MRV is measured by
ASTM D 4684, and may also be referred to as low temperature pumping
viscosity. Slow sample cooling rate is the method's key feature. A
sample is pretreated to have a specified thermal history which
includes warming, slow cooling, and soaking cycles. MRV measures an
apparent yield stress, which, if greater than a threshold value,
indicates a potential air-binding pumping failure problem. Above a
certain viscosity, currently defined as 60,000 cP by SAE J 300 June
2001, the oil may be subject to pumpability failure by a mechanism
called "flow limited" behavior. An SAE 10W oil, for example, is
required to have a maximum viscosity of 60,000 cP at -30.degree. C.
with no yield stress. This method also measures an apparent
viscosity under shear rates of 1 to 50 s.sup.-1.
[0052] TEOST MHT is a test that determines the amount of deposits,
in mg, formed by automotive engine oils utilizing the
thermo-oxidation engine oil simulation test (TEOST) under
moderately high temperature conditions. The test method is designed
to predict the high temperature deposit forming tendencies of
engine oil at the temperature found in the piston-ring belt area
(around 300.degree. C.). TEOST MHT can be run on TEOST 33C bench
test units already in the field for ASTM D 6335, with retrofit
hardware and modified test conditions. The primary hardware
differences are 1) a glass depositor rod casing instead of steel,
allowing for viewing of the oxidation/deposit process, 2)
wire-wound depositor rods to permit thin-film oil flow over the
heated rod, and 3) collection of volatilized material generated in
the depositor rod casing during the test. TEOST MHT has a maximum
specification of 45 mg total deposits in the newest engine oil
service category for automotive gasoline engines. API SL/ILSAC GF-3
oils that give improved high temperature deposit control in this
test are expected to provide extended oil drain capability, less
abrasive wear, improved piston ring cleanliness, longer engine
life, and improved turbocharger performance. A turbocharger is an
exhaust driven pump that compresses intake air and forces it into
the combustion chambers at higher than atmospheric pressures. The
increased air pressure allows more fuel to be burned and results in
increased horsepower being produced. Table II summarizes the TEOST
MHT protocol. TABLE-US-00002 TABLE II TEOST MHT protocol Test time
24 hours Temperature 285.degree. C. Sample size 10 mL Flow rate
(sample) 0.25 g/min Flow rate (dry air) 12 mL/min Catalyst Fe + Pb
+ Sn
The blended finished lubricants according to the present invention
preferably have a TEOST-MHT total deposit weight of less than or
equal to about 45 mg. Fischer-Tropsch Synthesis
[0053] The Fischer-Tropsch derived lubricant base oils comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
and less than 0.05 wt % molecules with aromatic functionality are
made by a Fischer-Tropsch process followed by hydroisomerization of
the waxy fractions of the Fischer-Tropsch syncrude.
[0054] In Fischer-Tropsch chemistry, syngas is converted to liquid
hydrocarbons by contact with a Fischer-Tropsch catalyst under
reactive conditions. Typically, methane and optionally heavier
hydrocarbons (ethane and heavier) can be sent through a
conventional syngas generator to provide synthesis gas. Generally,
synthesis gas contains hydrogen and carbon monoxide, and may
include minor amounts of carbon dioxide and/or water. The presence
of sulfur, nitrogen, halogen, selenium, phosphorus and arsenic
contaminants in the syngas is undesirable. For this reason and
depending on the quality of the syngas, it is preferred to remove
sulfur and other contaminants from the feed before performing the
Fischer-Tropsch chemistry. Means for removing these contaminants
are well known to those of skill in the art. For example, ZnO
guardbeds are preferred for removing sulfur impurities. Means for
removing other contaminants are well known to those of skill in the
art. It also may be desirable to purify the syngas prior to the
Fischer-Tropsch reactor to remove carbon dioxide produced during
the syngas reaction and any additional sulfur compounds not already
removed. This can be accomplished, for example, by contacting the
syngas with a mildly alkaline solution (e.g., aqueous potassium
carbonate) in a packed column.
[0055] In the Fischer-Tropsch process, contacting a synthesis gas
comprising a mixture of H.sub.2 and CO with a Fischer-Tropsch
catalyst under suitable temperature and pressure reactive
conditions forms liquid and gaseous hydrocarbons. The
Fischer-Tropsch reaction is typically conducted at temperatures of
about 300-700.degree. F. (149-371.degree. C.), preferably about
400-550.degree. F. (204-228.degree. C.); pressures of about 10-600
psia, (0.7-41 bars), preferably about 30-300 psia, (2-21 bars); and
catalyst space velocities of about 100-10,000 cc/g/hr, preferably
about 300-3,000 cc/g/hr. Examples of conditions for performing
Fischer-Tropsch type reactions are well known to those of skill in
the art.
[0056] The products of the Fischer-Tropsch synthesis process may
range from C.sub.1 to C.sub.200+ with a majority in the C.sub.5 to
C.sub.100+ range. The reaction can be conducted in a variety of
reactor types, such as fixed bed reactors containing one or more
catalyst beds, slurry reactors, fluidized bed reactors, or a
combination of different type reactors. Such reaction processes and
reactors are well known and documented in the literature.
[0057] The slurry Fischer-Tropsch process, which is preferred in
the practice of the invention, utilizes superior heat (and mass)
transfer characteristics for the strongly exothermic synthesis
reaction and is able to produce relatively high molecular weight,
paraffinic hydrocarbons when using a cobalt catalyst. In the slurry
process, a syngas comprising a mixture of hydrogen and carbon
monoxide is bubbled up as a third phase through a slurry which
comprises a particulate Fischer-Tropsch type hydrocarbon synthesis
catalyst dispersed and suspended in a slurry liquid comprising
hydrocarbon products of the synthesis reaction which are liquid
under the reaction conditions. The mole ratio of the hydrogen to
the carbon monoxide may broadly range from about 0.5 to about 4,
but is more typically within the range of from about 0.7 to about
2.75 and preferably from about 0.7 to about 2.5. A particularly
preferred Fischer-Tropsch process is taught in EP0609079, also
completely incorporated herein by reference for all purposes.
[0058] In general, Fischer-Tropsch catalysts contain a Group VIII
transition metal on a metal oxide support. The catalysts may also
contain a noble metal promoter(s) and/or crystalline molecular
sieves. Suitable Fischer-Tropsch catalysts comprise one or more of
Fe, Ni, Co, Ru and Re, with cobalt being preferred. A preferred
Fischer-Tropsch catalyst comprises effective amounts of cobalt and
one or more of Re, Ru, Pt, 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. In general, the amount of
cobalt present in the catalyst is between about 1 and about 50
weight percent of the total catalyst composition. The catalysts can
also contain basic oxide promoters such as ThO.sub.2,
La.sub.2O.sub.3, MgO, and TiO.sub.2, promoters such as ZrO.sub.2,
noble metals (Pt, Pd, Ru, Rh, Os, Ir), coinage metals (Cu, Ag, Au),
and other transition metals such as Fe, Mn, Ni, and Re. Suitable
support materials include alumina, silica, magnesia and titania or
mixtures thereof. Preferred supports for cobalt containing
catalysts comprise titania. Useful catalysts and their preparation
are known and illustrated in U.S. Pat. No. 4,568,663, which is
intended to be illustrative but non-limiting relative to catalyst
selection.
[0059] Certain catalysts are known to provide chain growth
probabilities that are relatively low to moderate, and the reaction
products include a relatively high proportion of low molecular
(C.sub.2-8) weight olefins and a relatively low proportion of high
molecular weight (C.sub.30+) waxes. Certain other catalysts are
known to provide relatively high chain growth probabilities, and
the reaction products include a relatively low proportion of low
molecular (C.sub.2-8) weight olefins and a relatively high
proportion of high molecular weight (C.sub.30+) waxes. Such
catalysts are well known to those of skill in the art and can be
readily obtained and/or prepared.
[0060] The product from a Fischer-Tropsch process contains
predominantly paraffins. The products from Fischer-Tropsch
reactions generally include a light reaction product and a waxy
reaction product. The light reaction product (i.e., the condensate
fraction) includes hydrocarbons boiling below about 700.degree. F.
(e.g., tail gases through middle distillate fuels), largely in the
C.sub.5-C.sub.20 range, with decreasing amounts up to about
C.sub.30. The waxy reaction product (i.e., the wax fraction)
includes hydrocarbons boiling above about 600.degree. F. (e.g.,
vacuum gas oil through heavy paraffins), largely in the C.sub.20+
range, with decreasing amounts down to C.sub.10. Both the light
reaction product and the waxy product are substantially paraffinic.
The waxy product generally comprises greater than 70 weight %
normal paraffins, and often greater than 80 weight % normal
paraffins. The light reaction product comprises paraffinic products
with a significant proportion of alcohols and olefins. In some
cases, the light reaction product may comprise as much as 50 weight
%, and even higher, alcohols and olefins. It is the waxy reaction
product (i.e., the wax fraction) that is used as a feedstock to the
process for providing the Fischer-Tropsch derived lubricant base
oil used in the blended lubricants and blended finished lubricants
of the present invention.
[0061] The Fischer-Tropsch derived lubricant base oils comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
and less than 0.05 weight % molecules with aromatic functionality
are prepared from the waxy fractions of the Fischer-Tropsch
syncrude by a process including hydroisomerization. Preferably, the
Fischer-Tropsch derived lubricant base oils are made by a process
as described in U.S. Ser. No. 10/744,389, filed Dec. 23, 2003, and
U.S. Ser. No. 10/744,870, filed Dec. 23, 2003, herein incorporated
by reference in their entirety. The Fischer-Tropsch derived
lubricant base oils used in the blended lubricants and blended
finished lubricants of the present invention may be manufactured at
a site different from the site at which the components of the
blended lubricant are received and blended.
Hydroisomerization
[0062] Hydroisomerization is intended to improve the cold flow
properties of the lubricant base oil by the selective addition of
branching into the molecular structure. Hydroisomerization ideally
will achieve high conversion levels of the Fischer-Tropsch wax to
non-waxy iso-paraffins while at the same time minimizing the
conversion by cracking. Preferably, the conditions for
hydroisomerization in the present invention are controlled such
that the conversion of the compounds boiling above about
700.degree. F. in the wax feed to compounds boiling below about
700.degree. F. is maintained between about 10 wt % and 50 wt%,
preferably between 15 wt % and 45 wt %.
[0063] According to the present invention, hydroisomerization is
conducted using a shape selective intermediate pore size molecular
sieve. Hydroisomerization catalysts useful in the present invention
comprise a shape selective intermediate pore size molecular sieve
and optionally a catalytically active metal hydrogenation component
on a refractory oxide support. The phrase "intermediate pore size,"
as used herein means an effective pore aperture in the range of
from about 3.9 to about 7.1 .ANG. when the porous inorganic oxide
is in the calcined form. The shape selective intermediate pore size
molecular sieves used in the practice of the present invention are
generally 1-D 10-, 11- or 12-ring molecular sieves. The preferred
molecular sieves of the invention are of the 1-D 10-ring variety,
where 10-(or 11- or 12-) ring molecular sieves have 10 (or 11 or
12) tetrahedrally-coordinated atoms (T-atoms) joined by oxygens. In
the 1-D molecular sieve, the 10-ring (or larger) pores are parallel
with each other, and do not interconnect. Note, however, that 1-D
10-ring molecular sieves which meet the broader definition of the
intermediate pore size molecular sieve but include intersecting
pores having 8-membered rings may also be encompassed within the
definition of the molecular sieve of the present invention. The
classification of intrazeolite channels as 1-D, 2-D and 3-D is set
forth by R. M. Barrer in Zeolites, Science and Technology, edited
by F. R. Rodrigues, L. D. Rollman and C. Naccache, NATO ASI Series,
1984 which classification is incorporated in its entirety by
reference (see particularly page 75).
[0064] Preferred shape selective intermediate pore size molecular
sieves used for hydroisomerization are based upon aluminum
phosphates, such as SAPO-11, SAPO-31, and SAPO-41. SAPO-11 and
SAPO-31 are more preferred, with SAPO-11 being most preferred. SM-3
is a particularly preferred shape selective intermediate pore size
SAPO, which has a crystalline structure falling within that of the
SAPO-11 molecular sieves. The preparation of SM-3 and its unique
characteristics are described in U.S. Pat. Nos. 4,943,424 and
5,158,665. Also preferred shape selective intermediate pore size
molecular sieves used for hydroisomerization are zeolites, such as
ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, and
ferrierite. SSZ-32 and ZSM-23 are more preferred.
[0065] A preferred intermediate pore size molecular sieve is
characterized by selected crystallographic free diameters of the
channels, selected crystallite size (corresponding to selected
channel length), and selected acidity. Desirable crystallographic
free diameters of the channels of the molecular sieves are in the
range of from about 3.9 to about 7.1 Angstrom, having a maximum
crystallographic free diameter of not more than 7.1 and a minimum
crystallographic free diameter of not less than 3.9 Angstrom.
Preferably the maximum crystallographic free diameter is not more
than 7.1 and the minimum crystallographic free diameter is not less
than 4.0 Angstrom. Most preferably the maximum crystallographic
free diameter is not more than 6.5 and the minimum crystallographic
free diameter is not less than 4.0 Angstrom. The crystallographic
free diameters of the channels of molecular sieves are published in
the "Atlas of Zeolite Framework Types", Fifth Revised Edition,
2001, by Ch. Baerlocher, W. M. Meier, and D. H. Olson, Elsevier, pp
10-15, which is incorporated herein by reference.
[0066] A particularly preferred intermediate pore size molecular
sieve, which is useful in the present process is described, for
example, in U.S. Pat. Nos. 5,135,638 and 5,282,958, the contents of
which are hereby incorporated by reference in their entirety. In
U.S. Pat. No. 5,282,958, such an intermediate pore size molecular
sieve has a crystallite size of no more than about 0.5 microns and
pores with a minimum diameter of at least about 4.8 .ANG. and with
a maximum diameter of about 7.1 .ANG.. The catalyst has sufficient
acidity so that 0.5 grams thereof when positioned in a tube reactor
converts at least 50% of hexadecane at 370.degree. C., a pressure
of 1200 psig, a hydrogen flow of 160 ml/min, and a feed rate of 1
ml/hr. The catalyst also exhibits isomerization selectivity of 40
percent or greater (isomerization selectivity is determined as
follows: 100.times.(weight % branched C.sub.16 in product)/(weight
% branched C.sub.16 in product+weight % C.sub.13- in product) when
used under conditions leading to 96% conversion of normal
hexadecane (n-C.sub.16) to other species.
[0067] If the crystallographic free diameters of the channels of a
molecular sieve are unknown, the effective pore size of the
molecular sieve can be measured using standard adsorption
techniques and hydrocarbonaceous compounds of known minimum kinetic
diameters. See Breck, Zeolite Molecular Sieves, 1974 (especially
Chapter 8); Anderson et al. J. Catalysis 58, 114 (1979); and U.S.
Pat. No. 4,440,871, the pertinent portions of which are
incorporated herein by reference. In performing adsorption
measurements to determine pore size, standard techniques are used.
It is convenient to consider a particular molecule as excluded if
does not reach at least 95% of its equilibrium adsorption value on
the molecular sieve in less than about 10 minutes (p/p.sub.o=0.5 at
25.degree. C.). Intermediate pore size molecular sieves will
typically admit molecules having kinetic diameters of 5.3 to 6.5
Angstrom with little hindrance.
[0068] Hydroisomerization catalysts useful in the present invention
comprise a catalytically active hydrogenation metal. The presence
of a catalytically active hydrogenation metal leads to product
improvement, especially VI and stability. Typical catalytically
active hydrogenation metals include chromium, molybdenum, nickel,
vanadium, cobalt, tungsten, zinc, platinum, and palladium. The
metals platinum and palladium are especially preferred, with
platinum most especially preferred. If platinum and/or palladium is
used, the total amount of active hydrogenation metal is typically
in the range of 0.1 to 5 weight percent of the total catalyst,
usually from 0.1 to 2 weight percent, and not to exceed 10 weight
percent.
[0069] The refractory oxide support may be selected from those
oxide supports, which are conventionally used for catalysts,
including silica, alumina, silica-alumina, magnesia, titania and
combinations thereof.
[0070] The conditions for hydroisomerization will be tailored to
achieve a Fischer-Tropsch derived lubricant base oil comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
and less than 0.05 weight % molecules with aromatic functionality.
The conditions for hydroisomerization will depend on the properties
of feed used, the catalyst used, whether or not the catalyst is
sulfided, the desired yield, and the desired properties of the
lubricant base oil. Conditions under which the hydroisomerization
process of the current invention may be carried out include
temperatures from about 600.degree. F. to about 750.degree. F.
(315.degree. C. to about 399.degree. C.), preferably about
600.degree. F. to about 700.degree. F. (315.degree. C. to about
371.degree. C.); and pressures from about 15 to 3000 psig,
preferably 100 to 2500 psig. The hydroisomerization dewaxing
pressures in this context refer to the hydrogen partial pressure
within the hydroisomerization reactor, although the hydrogen
partial pressure is substantially the same (or nearly the same) as
the total pressure. The liquid hourly space velocity during
contacting is generally from about 0.1 to 20 hr-1, preferably from
about 0.1 to about 5 hr-1. The hydrogen to hydrocarbon ratio falls
within a range from about 1.0 to about 50 moles H.sub.2 per mole
hydrocarbon, more preferably from about 10 to about 20 moles
H.sub.2 per mole hydrocarbon. Suitable conditions for performing
hydroisomerization are described in U.S. Pat. Nos. 5,282,958 and
5,135,638, the contents of which are incorporated by reference in
their entirety.
[0071] Hydrogen is present in the reaction zone during the
hydroisomerization process, typically in a hydrogen to feed ratio
from about 0.5 to 30 MSCF/bbl (thousand standard cubic feet per
barrel), preferably from about 1 to about 10 MSCF/bbl. Hydrogen may
be separated from the product and recycled to the reaction
zone.
Hydrotreating
[0072] Waxy feed to the hydroisomerization process may be
hydrotreated prior to hydroisomerization dewaxing. Hydrotreating
refers to a catalytic process, usually carried out in the presence
of free hydrogen, in which the primary purpose is the removal of
various metal contaminants, such as arsenic, aluminum, and cobalt;
heteroatoms, such as sulfur and nitrogen; oxygenates; or aromatics
from the feed stock. Generally, in hydrotreating operations
cracking of the hydrocarbon molecules, i.e., breaking the larger
hydrocarbon molecules into smaller hydrocarbon molecules, is
minimized, and the unsaturated hydrocarbons are either fully or
partially hydrogenated.
[0073] Catalysts used in carrying out hydrotreating operations are
well known in the art. See, for example, U.S. Pat. Nos. 4,347,121
and 4,810,357, the contents of which are hereby incorporated by
reference in their entirety, for general descriptions of
hydrotreating, hydrocracking, and of typical catalysts used in each
of the processes. Suitable catalysts include noble metals from
Group VIIIA (according to the 1975 rules of the International Union
of Pure and Applied Chemistry), such as platinum or palladium on an
alumina or siliceous matrix, and Group VIII and Group VIB, such as
nickel-molybdenum or nickel-tin on an alumina or siliceous matrix.
U.S. Pat. No. 3,852,207 describes a suitable noble metal catalyst
and mild conditions. Other suitable catalysts are described, for
example, in U.S. Pat. Nos. 4,157,294 and 3,904,513. The non-noble
hydrogenation metals, such as nickel-molybdenum, are usually
present in the final catalyst composition as oxides, but are
usually employed in their reduced or sulfided forms when such
sulfide compounds are readily formed from the particular metal
involved. Preferred non-noble metal catalyst compositions contain
in excess of about 5 weight percent, preferably about 5 to about 40
weight percent molybdenum and/or tungsten, and at least about 0.5,
and generally about 1 to about 15 weight percent of nickel and/or
cobalt determined as the corresponding oxides. Catalysts containing
noble metals, such as platinum, contain in excess of 0.01 percent
metal, preferably between 0.1 and 1.0 percent metal. Combinations
of noble metals may also be used, such as mixtures of platinum and
palladium.
[0074] Typical hydrotreating conditions vary over a wide range. In
general, the overall LHSV is about 0.25 to 2.0, preferably about
0.5 to 1.5. The hydrogen partial pressure is greater than 200 psia,
preferably ranging from about 500 psia to about 2000 psia. Hydrogen
recirculation rates are typically greater than 50 SCF/Bbl, and are
preferably between 1000 and 5000 SCF/Bbl. Temperatures in the
reactor will range from about 300.degree. F. to about 750.degree.
F. (about 150.degree. C. to about 400.degree. C.), preferably
ranging from 450.degree. F. to 725.degree. F. (230.degree. C. to
385.degree. C.).
Hydrofinishing
[0075] Hydrofinishing is a hydrotreating process that may be used
as a step following hydroisomerization to provide the
Fischer-Tropsch derived lubricant base oil. Hydrofinishing is
intended to improve oxidation stability, UV stability, and
appearance of the Fischer-Tropsch derived lubricant base oil
product by removing traces of aromatics, olefins, color bodies, and
solvents. As used in this disclosure, the term UV stability refers
to the stability of the lubricant base oil or the finished
lubricant when exposed to UV light and oxygen. Instability is
indicated when a visible precipitate forms, usually seen as floc or
cloudiness, or a darker color develops upon exposure to ultraviolet
light and air. A general description of hydrofinishing may be found
in U.S. Pat. Nos. 3,852,207 and 4,673,487.
[0076] The Fischer-Tropsch derived lubricant base oils of the
present invention may be hydrofinished to improve product quality
and stability. During hydrofinishing, overall liquid hourly space
velocity (LHSV) is about 0.25 to 2.0 hr.sup.-1, preferably about
0.5 to 1.0 hr.sup.-1. The hydrogen partial pressure is greater than
200 psia, preferably ranging from about 500 psia to about 2000
psia. Hydrogen recirculation rates are typically greater than 50
SCF/Bbl, and are preferably between 1000 and 5000 SCF/Bbl.
Temperatures range from about 300.degree. F. to about 750.degree.
F., preferably ranging from 450.degree. F. to 600.degree. F.
[0077] Suitable hydrofinishing catalysts include noble metals from
Group VIIIA (according to the 1975 rules of the International Union
of Pure and Applied Chemistry), such as platinum or palladium on an
alumina or siliceous matrix, and unsulfided Group VIIIA and Group
VIB, such as nickel-molybdenum or nickel-tin on an alumina or
siliceous matrix. U.S. Pat. No. 3,852,207 describes a suitable
noble metal catalyst and mild conditions. Other suitable catalysts
are described, for example, in U.S. Pat. Nos. 4,157,294 and
3,904,513. The non-noble metal (such as nickel-molybdenum and/or
tungsten, and at least about 0.5, and generally about 1 to about 15
weight percent of nickel and/or cobalt determined as the
corresponding oxides. The noble metal (such as platinum) catalyst
contains in excess of 0.01 percent metal, preferably between 0.1
and 1.0 percent metal. Combinations of noble metals may also be
used, such as mixtures of platinum and palladium.
[0078] Clay treating to remove impurities is an alternative final
process step to provide Fischer-Tropsch derived lubricant base
oils.
Fractionation
[0079] Optionally, the process to provide the Fischer-Tropsch
derived lubricant base oil may include fractionating the
substantially paraffinic wax feed prior to hydroisomerization, or
fractionating of the lubricant base oil obtained from the
hydroisomerization process. The fractionation of the
Fischer-Tropsch substantially paraffinic wax feed or lubricant base
oil into distillate fractions is generally accomplished by either
atmospheric or vacuum distillation, or by a combination of
atmospheric and vacuum distillation. Atmospheric distillation is
typically used to separate the lighter distillate fractions, such
as naphtha and middle distillates, from a bottoms fraction having
an initial boiling point above about 600.degree. F. to about
750.degree. F. (about 315.degree. C. to about 399.degree. C.). At
higher temperatures thermal cracking of the hydrocarbons may take
place leading to fouling of the equipment and to lower yields of
the heavier cuts. Vacuum distillation is typically used to separate
the higher boiling material, such as the lubricant base oil
fractions, into different boiling range cuts. Fractionating the
lubricant base oil into different boiling range cuts enables the
lubricant base oil manufacturing plant to produce more than one
grade, or viscosity, of lubricant base oil.
Solvent Dewaxing
[0080] The process to make the Fischer-Tropsch derived lubricant
base oil may also include a solvent dewaxing step following the
hydroisomerization process. Solvent dewaxing optionally may be used
to remove small amounts of remaining waxy molecules from the
lubricant base oil after hydroisomerization dewaxing. Solvent
dewaxing is done by dissolving the lubricant base oil in a solvent,
such as methyl ethyl ketone, methyl iso-butyl ketone, or toluene,
or precipitating the wax molecules as discussed in Chemical
Technology of Petroleum, 3rd Edition, William Gruse and Donald
Stevens, McGraw-Hill Book Company, Inc., New York, 1960, pages 566
to 570. Solvent dewaxing is also described in U.S. Pat. Nos.
4,477,333, 3,773,650 and 3,775,288.
Fischer-Tropsch Derived Lubricant Base Oil
[0081] The Fischer-Tropsch derived lubricant base oil used to
prepare the blended lubricants and the blended finished lubricants
of the invention preferably have a viscosity of about between about
2 and 20 cSt at 100.degree. C.
[0082] The Fischer-Tropsch derived lubricant base oils comprise
.gtoreq.6 weight % molecules with monocycloparaffinic
functionality, preferably .gtoreq.8 weight % molecules with
monocycloparaffinic functionality, and even more preferably
.gtoreq.10 weight % molecules with monocycloparaffinic
functionality. In a preferred embodiment, the Fischer-Tropsch
derived lubricant base oil comprises very low weight percents of
aromatics, a high weight percent of molecules with cycloparaffinic
functionality, and a high ratio of weight percent of molecules with
monocycloparaffinic functionality to weight percent of molecules
with multicycloparaffinic functionality (or high weight percent of
molecules with monocycloparaffinic functionality and very low
weight percents of molecules with multicycloparaffinic
functionality). The Fischer-Tropsch derived lubricant base oil
comprises a weight percent of molecules with aromatic functionality
of less than 0.05, preferably less than 0.02 weight %. In a
preferred embodiment, the Fischer-Tropsch derived lubricant base
oil comprises a weight percent of molecules with cycloparaffinic
functionality of greater than 10, and a high ratio of weight
percent of molecules with monocycloparaffinic functionality to
weight percent of molecules with multicycloparaffinic
functionality, preferably greater than 15. In yet another preferred
embodiment, the Fischer-Tropsch derived lubricant base oil
comprises a weight percent of molecules with aromatic functionality
less than 0.05, a weight percent of molecules with
monocycloparaffinic functionality of greater than 10, and a weight
percent of molecules with multicycloparaffinic functionality of
less than 0.1.
[0083] The Fischer-Tropsch derived lubricant base oils used in the
blended lubricants and blended finished lubricants contain greater
than 95 weight % saturates as determined by elution column
chromatography, ASTM D 2549-02. Olefins are present in an amount
less than detectable by long duration C.sup.13 Nuclear Magnetic
Resonance Spectroscopy (NMR). Molecules with aromatic functionality
are present in an amount of less than 0.05 weight percent by
HPLC-UV, and confirmed by ASTM D 5292-99 modified to measure low
level aromatics. In preferred embodiments molecules with aromatic
functionality are present in an amount less than 0.02 weight
percent, preferably less than 0.01 weight percent.
[0084] Sulfur is present in an amount less than 25 ppm, more
preferably less than 1 ppm, as determined by ultraviolet
fluorescence by ASTM D 5453-00.
Aromatics Measurement by HPLC-UV:
[0085] The method used to measure low levels of molecules with
aromatic functionality in the Fischer-Tropsch derived lubricant
base oils uses a Hewlett Packard 1050 Series Quaternary Gradient
High Performance Liquid Chromatography (HPLC) system coupled with a
HP 1050 Diode-Array UV-Vis detector interfaced to an HP
Chem-station. Identification of the individual aromatic classes in
the highly saturated Fischer-Tropsch derived lubricant base oils
was made on the basis of their UV spectral pattern and their
elution time. The amino column used for this analysis
differentiates aromatic molecules largely on the basis of their
ring-number (or more correctly, double-bond number). Thus, the
single ring aromatic containing molecules would elute first,
followed by the polycyclic aromatics in order of increasing double
bond number per molecule. For aromatics with similar double bond
character, those with only alkyl substitution on the ring would
elute sooner than those with cycloparaffinic substitution.
[0086] Unequivocal identification of the various base oil aromatic
hydrocarbons from their UV absorbance spectra was somewhat
complicated by the fact their peak electronic transitions were all
red-shifted relative to the pure model compound analogs to a degree
dependent on the amount of alkyl and cycloparaffinic substitution
on the ring system. These bathochromic shifts are well known to be
caused by alkyl-group delocalization of the .pi.-electrons in the
aromatic ring. Since few unsubstituted aromatic compounds boil in
the lubricant range, some degree of red-shift was expected and
observed for all of the principle aromatic groups identified.
[0087] Quantification of the eluting aromatic compounds was made by
integrating chromatograms made from wavelengths optimized for each
general class of compounds over the appropriate retention time
window for that aromatic. Retention time window limits for each
aromatic class were determined by manually evaluating the
individual absorbance spectra of eluting compounds at different
times and assigning them to the appropriate aromatic class based on
their qualitative similarity to model compound absorption spectra.
With few exceptions, only five classes of aromatic compounds were
observed in highly saturated API Group II and III lubricant base
oils.
HPLC-UV Calibration:
[0088] HPLC-UV is used for identifying these classes of aromatic
compounds even at very low levels. Multi-ring aromatics typically
absorb 10 to 200 times more strongly than single-ring aromatics.
Alkyl-substitution also affected absorption by about 20%.
Therefore, it is important to use HPLC to separate and identify the
various species of aromatics and know how efficiently they
absorb.
[0089] Five classes of aromatic compounds were identified. With the
exception of a small overlap between the most highly retained
alkyl-1-ring aromatic naphthenes and the least highly retained
alkyl naphthalenes, all of the aromatic compound classes were
baseline resolved. Integration limits for the co-eluting 1-ring and
2-ring aromatics at 272 nm were made by the perpendicular drop
method. Wavelength dependent response factors for each general
aromatic class were first determined by constructing Beer's Law
plots from pure model compound mixtures based on the nearest
spectral peak absorbances to the substituted aromatic analogs.
[0090] For example, alkyl-cyclohexylbenzene molecules in base oils
exhibit a distinct peak absorbance at 272 nm that corresponds to
the same (forbidden) transition that unsubstituted tetralin model
compounds do at 268 nm. The concentration of alkyl-1-ring aromatic
naphthenes in base oil samples was calculated by assuming that its
molar absorptivity response factor at 272 nm was approximately
equal to tetralin's molar absorptivity at 268 nm, calculated from
Beer's law plots. Weight percent concentrations of aromatics were
calculated by assuming that the average molecular weight for each
aromatic class was approximately equal to the average molecular
weight for the whole base oil sample.
[0091] This calibration method was further improved by isolating
the 1-ring aromatics directly from the lubricant base oils via
exhaustive HPLC chromatography. Calibrating directly with these
aromatics eliminated the assumptions and uncertainties associated
with the model compounds. As expected, the isolated aromatic sample
had a lower response factor than the model compound because it was
more highly substituted.
[0092] More specifically, to accurately calibrate the HPLC-UV
method, the substituted benzene aromatics were separated from the
bulk of the lubricant base oil using a Waters semi-preparative HPLC
unit. 10 grams of sample was diluted 1:1 in n-hexane and injected
onto an amino-bonded silica column, a 5 cm.times.22.4 mm ID guard,
followed by two 25 cm.times.22.4 mm ID columns of 8-12 micron
amino-bonded silica particles, manufactured by Rainin Instruments,
Emeryville, Calif., with n-hexane as the mobile phase at a flow
rate of 18 mls/min. Column eluent was fractionated based on the
detector response from a dual wavelength UV detector set at 265 nm
and 295 nm. Saturate fractions were collected until the 265 nm
absorbance showed a change of 0.01 absorbance units, which signaled
the onset of single ring aromatic elution. A single ring aromatic
fraction was collected until the absorbance ratio between 265 nm
and 295 nm decreased to 2.0, indicating the onset of two ring
aromatic elution. Purification and separation of the single ring
aromatic fraction was made by re-chromatographing the monoaromatic
fraction away from the "tailing" saturates fraction which resulted
from overloading the HPLC column.
[0093] This purified aromatic "standard" showed that alkyl
substitution decreased the molar absorptivity response factor by
about 20% relative to unsubstituted tetralin.
Confirmation of Aromatics by NMR:
[0094] The weight percent of molecules with aromatic functionality
in the purified mono-aromatic standard was confirmed via
long-duration carbon 13 NMR analysis. NMR was easier to calibrate
than HPLC UV because it simply measured aromatic carbon so the
response did not depend on the class of aromatics being analyzed.
The NMR results were translated from % aromatic carbon to %
aromatic molecules (to be consistent with HPLC-UV and D 2007) by
knowing that 95-99% of the aromatics in highly saturated lubricant
base oils were single-ring aromatics.
[0095] High power, long duration, and good baseline analysis were
needed to accurately measure aromatics down to 0.2% aromatic
molecules.
[0096] More specifically, to accurately measure low levels of all
molecules with at least one aromatic function by NMR, the standard
D 5292-99 method was modified to give a minimum carbon sensitivity
of 500:1 (by ASTM standard practice E 386). A15-hour duration run
on a 400-500 MHz NMR with a 10-12 mm Nalorac probe was used. Acorn
PC integration software was used to define the shape of the
baseline and consistently integrate. The carrier frequency was
changed once during the run to avoid artifacts from imaging the
aliphatic peak into the aromatic region. By taking spectra on
either side of the carrier spectra, the resolution was improved
significantly.
Cycloparaffin Distribution by FIMS:
[0097] Paraffins are considered more stable than cycloparaffins
towards oxidation, and therefore, more desirable.
Monocycloparaffins are considered more stable than
multicycloparaffins towards oxidation. However, when the weight
percent of all molecules with at least one cycloparaffinic function
is very low in a lubricant base oil, the additive solubility is low
and the elastomer compatibility is poor. Examples of base oils with
these properties are polyalphaolefins and Fischer-Tropsch base oils
(GTL base oils) with less than about 5% cycloparaffins. To improve
these properties in finished lubricants, expensive co-solvents such
as esters must often be added. Preferably, the Fischer-Tropsch
derived lubricant base oils used in the blended lubricants and
blended finished lubricants of the present invention comprise a
high weight percent of molecules with monocycloparaffinic
functionality and a low weight percent of molecules with
multicycloparaffinic functionality such that the Fischer-Tropsch
derived lubricant base oils, and thus the blended lubricants and
blended finished lubricants, have high oxidation stability and high
viscosity index in addition to good additive solubility and
elastomer compatibility.
[0098] The composition of molecules with cycloparaffinic and
multicycloparaffinic functionality are determined using Field
Ionization Mass Spectroscopy (FIMS). FIMS spectra were obtained on
a VG 70 VSE mass spectrometer. The samples were introduced via
solid probe, which was heated from about 40.degree. C. to
500.degree. C. at a rate of 50.degree. C. per minute. The mass
spectrometer was scanned from m/z 40 to m/z 1000 at a rate of 5
seconds per decade. The acquired mass spectra were summed to
generate one "averaged" spectrum. Each spectrum was C13 corrected
using a software package from PC-MassSpec. FIMS ionization
efficiency was evaluated using blends of nearly pure branched
paraffins and highly naphthenic, aromatics-free base stock. The
ionization efficiencies of iso-paraffins and cycloparaffins in
these base oils were essentially the same. Iso-paraffins and
cycloparaffins comprise more than 99.9% of the saturates in the
lubricant base oils of this invention. Response factors for all
compound types were assumed to be 1.0, such that weight percent was
given directly from area percent.
[0099] The lubricant base oils of this invention are characterized
by FIMS into paraffins and molecules with different numbers of
unsaturations. The molecules with different numbers of
unsaturations may be comprised of cycloparaffins, olefins, and
aromatics. As the lubricant base oils of this invention have very
low levels of aromatics and olefins, the molecules with different
numbers of unsaturations may be interpreted as being cycloparaffins
with different numbers of rings. Thus, for the lubricant base oils
of this invention, the 1-unsaturations are monocycloparaffins, the
2-unsaturations are dicycloparaffins, the 3-unsaturations are
tricycloparaffins, the 4-unsaturations are tetracycloparaffins, the
5-unsaturations are pentacycloparaffins, and the 6-unsaturations
are hexacycloparaffins. If aromatics were present in significant
amounts in the lubricant base oil they would be identified in the
FIMS analysis as 4-unsaturations. The total of the 2-unsaturations,
3-unsaturations, 4-unsaturations, 5-unsaturations, and
6-unsaturations in the white oils of this invention are the weight
percent of molecules with multicycloparaffinic functionality. The
total of the 1-unsaturations in the lubricant base oils of this
invention are the weight percent of molecules with
monocycloparaffinic functionality.
[0100] In one embodiment, the Fischer-Tropsch derived lubricant
base oils have a weight percent of molecules with cycloparaffinic
functionality greater than 10, preferably greater than 15, more
preferably greater than 20. They have a ratio of weight percent of
molecules with monocycloparaffinic functionality to weight percent
of molecules with multicycloparaffinic functionality greater than
15, preferably greater than 50, more preferably greater than 100.
In preferred embodiments, the Fischer-Tropsch derived lubricant
base oils have a weight percent of molecules with
monocycloparaffinic functionality greater than 10, and a weight
percent of molecules with multicycloparaffinic functionality less
than 0.1, or even no molecules with multicycloparaffinic
functionality. In this embodiment, the Fischer-Tropsch derived
lubricant base oils may have a kinematic viscosity at 100.degree.
C. between about 2 cSt and about 20 cSt, preferably between about 2
cSt and about 12 cSt, most preferably between about 3.5 cSt and
about 12 cSt.
[0101] In another embodiment in the Fischer-Tropsch derived
lubricant base oils, there is a relationship between the weight
percent of all molecules with at least one cycloparaffinic
functionality and the kinematic viscosity of the lubricant base
oils of this invention. That is, the higher the kinematic viscosity
at 100.degree. C. in cSt, the higher the amount of molecules with
cycloparaffinic functionality that are obtained. In a preferred
embodiment, the Fischer-Tropsch derived lubricant base oils have a
weight percent of molecules with cycloparaffinic functionality
greater than the kinematic viscosity in cSt multiplied by three,
preferably greater than 15, more preferably greater than 20; and a
ratio of weight percent of molecules with monocycloparaffinic
functionality to weight percent of molecules with
multicycloparaffinic functionality greater than 15, preferably
greater than 50, more preferably greater than 100. The
Fischer-Tropsch derived lubricant base oils have a kinematic
viscosity at 100.degree. C. between about 2 cSt and about 20 cSt,
preferably between about 2 cSt and about 12 cSt. Examples of these
base oils may have a kinematic viscosity at 100.degree. C. of
between about 2 cSt and about 3.3 cSt and have a weight percent of
molecules with cycloparaffinic functionality that is high, but less
than 10 weight percent.
[0102] The modified ASTM D 5292-99 and HPLC-UV test methods used to
measure low level aromatics, and the FIMS test method used to
characterize saturates are described in D. C. Kramer, et al.,
"Influence of Group II & III Base Oil Composition on VI and
Oxidation Stability," presented at the 1999 AIChE Spring National
Meeting in Houston, Mar. 16, 1999, the contents of which is
incorporated herein in its entirety.
[0103] Although the Fischer-Tropsch wax feeds are essentially free
of olefins, base oil processing techniques can introduce olefins,
especially at high temperatures, due to `cracking` reactions. In
the presence of heat or UV light, olefins can polymerize to form
higher molecular weight products that can color the base oil or
cause sediment. In general, olefins can be removed during the
process of this invention by hydrofinishing or by clay
treatment.
[0104] The properties of the Fischer-Tropsch derived lubricant base
oils used in the examples are summarized below in Table III.
TABLE-US-00003 TABLE III FTBO Properties FT-4A FT-4B FT-8B
Viscosity at 100.degree. C. (cSt) 3.94 4.415 7.953 Viscosity Index
143 147 165 Pour Point (.degree. C.) -19 -12 -12 FIMS Analysis %
Paraffins 89.0 89.1 87.2 % Monocycloparaffins 11.0 10.9 12.6 %
Multicycloparaffins 0.0 0.0 0.2 Total 100.0 100.0 100.0
[0105] Of the different saturated hydrocarbons found in lubricant
base oils, traditionally paraffins have been considered more stable
than cycloparaffins (naphthenes) toward oxidation, and therefore,
more desirable. However, when the amount of aromatics in the base
oil is less than 1 weight %, the most effective way to further
improve oxidation stability is to increase the viscosity index of
the base oil. Fischer-Tropsch derived lubricant base oils typically
contain less than 1% aromatics. Due to their extremely low amount
of aromatics and multi-ring cycloparaffins in the Fischer-Tropsch
derived lubricant base oils of the present invention, their high
oxidation stability far exceeds that of conventional lubricant base
oils. Additionally, Fischer-Tropsch derived lubricant base oils are
generally classified as API Group III base oils and have a low
sulfur content of less than 5 ppm, a saturates content of greater
than 95%, a high viscosity index, and excellent cold flow
properties.
[0106] The Fischer-Tropsch derived lubricant base oils useful in
this invention have high viscosity indexes. Viscosity index is
measured by ASTM D 2270-93(98). Generally, they have a viscosity
index greater than 120, preferably an amount calculated by the
equation: Viscosity Index=28.times.Ln(Kinematic Viscosity at
100.degree. C.)+95, more preferably greater than an amount
calculated by the equation: Viscosity Index=28.times.Ln(Kinematic
Viscosity at 100.degree. C.)+105.
Blended Lubricant Base Oils
[0107] The blended lubricant base oils of the present invention
comprise .gtoreq.70 weight % Fischer-Tropsch derived lubricant base
oil and at least one polyalphaolefin lubricant base oil having a
kinematic viscosity at 100.degree. C. greater than about 30 cSt and
less than 150 cSt. The blended lubricant base oil preferably
comprises the at least one Fischer-Tropsch derived lubricant base
oil in an amount between 70 and about 99 weight % and the at least
one polyalphaolefin in an amount between about 1 and 30 weight %.
The blended lubricant base oil may be made by blending the
Fischer-Tropsch derived lubricant base oil and the polyalphaolefin
lubricant base oil by techniques known to those of skill in the
art.
[0108] The Fischer-Tropsch derived lubricant base oils have a
kinematic viscosity at 100.degree. C. between about 2 cSt and about
20 cSt, preferably between about 2 cSt and about 12 cSt.
Preferably, the difference in the kinematic viscosities at
100.degree. C. of the Fischer-Tropsch derived lubricant base oil
and the polyalphaolefin lubricant base oil is greater than 40 cSt
and more preferably is greater than 70 cSt.
[0109] To provide the blended finished lubricants, the blended
lubricant base oil is mixed with at least one antiwear additive.
The blended finished lubricant may be made by blending the blended
lubricant base oil and the anti-wear additive by techniques known
to those of skill in the art. The blended finished lubricant
components may be blended in a single step going from the
individual components (i.e., the Fischer-Tropsch derived lubricant
base oil, the polyalphaolefin lubricant base oil, and the anti-wear
additive) directly to provide the blended finished lubricant. In
the alternative, the Fischer-Tropsch derived lubricant base oil and
the polyalphaolefin lubricant base oil may initially be blended to
provide the blended lubricant and then the blended lubricant, as
such, may be mixed with the anti-wear additive. The blended
lubricant may be isolated as such or the addition of the anti-wear
additive may occur immediately.
[0110] The Fischer-Tropsch derived lubricant base oils used in the
blended lubricant base oils and blended finished lubricants of the
present invention may be manufactured at a site different from the
site at which the components of the blended lubricant are received
and blended. In addition, the blended finished lubricant may be
manufactured at a site different from the site at which the
components of the blended lubricant base oil are received and
blended. Preferably, the blended lubricant base oil and the blended
finished lubricant are made at the same site, which site is
different from the site at which the Fischer-Tropsch derived
lubricant base oil is originally made. Accordingly, the
Fischer-Tropsch derived lubricant base oil is manufactured as a
first site and shipped to a second remote site. The second remote
site receives the Fischer-Tropsch derived lubricant base oil, the
polyalphaolefin, and the additives, and the blended finished
lubricant is manufactured at this second site.
Blended Finished Lubricant
[0111] Finished lubricants comprise at least one lubricant base oil
and at least one additive. Lubricant base oils are the most
important component of finished lubricants, generally comprising
.gtoreq.70% of the finished lubricants. The finished lubricants of
the present invention may be used in automobiles, diesel engines,
axles, transmissions, and industrial applications.
[0112] The blended finished lubricants of the present invention
comprise at least one Fischer-Tropsch derived lubricant base oil
comprising .gtoreq.6 weight % molecules with monocycloparaffinic
functionality and less than 0.05 weight % molecules with aromatic
functionality; at least one polyalphaolefin lubricant base oil
having a kinematic viscosity greater than about 30 cSt and less
than 150 cSt, and an effective amount of at least one antiwear
additive. The blended finished lubricants of the present invention
exhibit exceptional friction and wear properties.
[0113] In general, the effective amount of anti-wear additive
needed in a finished lubricant comprising a Fischer-Tropsch derived
lubricant base oil is less than that required in a finished
lubricant comprising a conventional petroleum lubricant base oil or
a polyalphaolefin lubricant base oil. According to the present
invention, it has been surprising discovered that significantly
less anti-wear additive is required for a finished lubricant
comprising a Fischer-Tropsch derived lubricant base oil comprising
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
and less than 0.05 weight % molecules with aromatic functionality
blended with a polyalphaolefin lubricant base oil having a
kinematic viscosity at 100.degree. C. greater than about 30 cSt and
less than 150 cSt than in a finished lubricant comprising a
Fischer-Tropsch derived lubricant base oil in the absence of a
polyalphaolefin lubricant base oil. Accordingly, in the blended
finished lubricants of the present invention, a reduced amount of
anti-wear additive is needed. Thus, the blended lubricants of the
present invention can be used to make high quality engine oils and
other finished lubricants meeting the most stringent modern engine
oil specifications.
[0114] An effective amount of at least one anti-wear additive means
the amount of anti-wear additive in an additive package or
individually added to the blended lubricant base oil to provide a
blended finished lubricant with an HFRR wear volume with 1,000 g
applied load of less than 300,000 microns.sup.3, preferably less
than 170,000 microns.sup.3, more preferably less than 150,000
microns.sup.3. Even more preferably, the blended finished lubricant
has an HFRR wear volume with 1,000 g applied load of less than
110,000 microns.sup.3. According to the present invention,
preferably an effective amount of at least one anti-wear additive
is between about 0.001 and 5 weight % of the blended finished
lubricant. The effective amount of anti-wear additive in the
blended finished lubricants of the present invention is less than
the effective amount of anti-wear additive required in a lubricant
comprising a Fischer-Tropsch derived lubricant base oil in the
absence of a polyalphaolefin lubricant base oil and a
polyalphaolefin lubricant base oil in the absence of a
Fischer-Tropsch derived lubricant base oil.
[0115] Antiwear additives react chemically with metal surfaces in
equipment being lubricated to form a layer that reduces wear at
either low-medium temperatures and loads or high-temperatures and
loads. Typically the metal surfaces comprise a ferrous alloy. The
anti-wear additive may be one or more metal phosphates, metal
dithiophosphates, metal dialkyldithiophosphates, metal
thiocarbamates, metal dithiocarbamates, metal
dialkyldithiocarbamates, ethoxylated amine dialkyldithiophosphates,
ethoxylate amine dithiobenzoates, neutral organic phosphites,
organo-molybdenum compounds, organo-sulfur compounds, sulfur
compounds, chlorine compounds, or mixtures thereof. Preferably, the
anti-wear additive is a metal dialkyldithiophosphate and even more
preferably, the metal is zinc. An overview of different types of
antiwear additives is given by McDonald, R. A. and Phillips, W. D.,
"Lubricant Additives Chemistry and Applications," Chapters 2 &
3, 2003.
[0116] The blended finished lubricants of the present invention may
further comprise additional additives such as EP agents,
detergents, dispersants, antioxidants, pour point depressants,
viscosity index improvers, ester co-solvents, viscosity modifiers,
friction modifiers, demulsifiers, antifoaming agents, corrosion
inhibitors, rust inhibitors, seal swell agents, emulsifiers,
wetting agents, lubricity improvers, metal deactivators, gelling
agents, tackiness agents, bactericides, fluid-loss additives,
colorants, and combinations thereof.
[0117] When viscosity index improvers are added, preferably they
are present in an amount less than 8 weight percent, and when ester
co-solvents are added, preferably they are present in an amount
less than 3 weight percent. Even more preferably, the finished
lubricants according to the present invention do not comprise a
viscosity index improver or an ester co-solvent. Preferably, the
blended finished lubricants of the present invention have a
viscosity index of greater than 140, more preferably greater than
165, without use of any viscosity index improver.
[0118] The finished lubricants of the present invention may be
formulated to be a multigrade internal combustion engine crankcase
oil, a transmission oil, a power train fluid, a turbine oil, a
compressor oil, a hydraulic oil, or a grease. In one embodiment,
the blended finished lubricant is a multigrade internal combustion
engine crankcase oil meeting SAE J300, June 2001, specifications.
In one specific embodiment, the blended finished lubricant is a
multigrade internal combustion engine crankcase oil meeting the
specifications for an engine oil having a viscosity grade of 0W-20,
5W-XX, 10W-XX, or 15W-XX wherein XX is 20, 30, 40, 50 or 60. In
another embodiment, the blended finished lubricant is an internal
combustion engine crankcase oil meeting the specifications for at
least one ACEA 2002 European Oil Sequences for gasoline, light duty
diesel engines, or heavy duty diesel engines.
[0119] The multigrade internal combustion engine crankcase oil
according to the present invention preferably exhibits a TEOST-MHT
total deposit weight of less than or equal to about 45
milligrams.
[0120] Surprisingly, the blended finished lubricants of the present
invention exhibit exceptional friction and wear properties while
requiring reduced amounts of anti-wear additives. The blended
finished lubricants of the present invention reduce wear in
equipment made of ferrous alloys. Ferrous alloys are alloys of
iron, containing various amounts of carbon, manganese, and one or
more other elements, such as sulfur, nickel, silicon, phosphorus,
chromium, molybdenum, and vanadium. These elements, when combined
with iron, form different types of steels with varying properties.
Antiwear additives are designed to react with the metal surfaces,
usually of ferrous alloys, to reduce wear when the asperities on
the surfaces come in contact with each other.
[0121] When the blended finished lubricant is formulated to be a
multigrade internal combustion engine crankcase oil, an internal
combustion engine comprising a valve train may be operated by
operating the engine using fuel and lubricating the engine using
the blended finished lubricant of the presently claimed invention.
The engine may be a compression ignition engine, or more
specifically a compression ignition engine equipped with an exhaust
gas after treatment device. The engine may be a spark ignition
engine, or more specifically a spark ignition engine equipped with
an exhaust gas after treatment device. The engine may further be
quipped with a turbocharger. The fuel may be a diesel fuel, a low
sulfur diesel fuel, a gasoline fuel, an unleaded gasoline, or
natural gas.
EXAMPLES
[0122] The invention will be further explained by the following
illustrative examples that are intended to be non-limiting.
Example 1
Fischer-Tropsch Wax and Preparation of Fischer-Tropsch Derived
Lubricant Base Oils
[0123] Two samples of hydrotreated Fischer-Tropsch wax, FT Wax A
and FT Wax B, were made using a Co-based Fischer-Tropsch catalyst.
Both samples were analyzed and found to have the properties shown
in Table V. TABLE-US-00004 TABLE V Fischer-Tropsch Wax
Fischer-Tropsch Catalyst Co-Based Co-Based Fischer-Tropsch Wax FT
Wax A FT Wax B Sulfur, ppm <6 7, <2 Nitrogen, ppm 6, 5 12,
19* Oxygen by NA, Wt % 0.59 0.69 GC N-Paraffin Analysis Total N
Paraffin, Wt % 84.47 83.72 Avg. Carbon Number 27.3 30.7 Avg.
Molecular Weight 384.9 432.5 D-6352 SIMDIST TBP (WT %), .degree. F.
T.sub.0.5 515 129 T.sub.5 597 568 T.sub.10 639 625 T.sub.20 689 674
T.sub.30 714 717 T.sub.40 751 756 T.sub.50 774 792 T.sub.60 807 827
T.sub.70 839 873 T.sub.80 870 914 T.sub.90 911 965 T.sub.95 935
1005 T.sub.99.5 978 1090 T.sub.90-T.sub.10, .degree. C. 133 171 Wt
% C.sub.30+ 34.69 40.86 Wt % C.sub.60+ 0.00 0.00
C.sub.60+/C.sub.30+ 0.00 0.00 *The results with more than one value
are duplicate test results.
[0124] The Fischer-Tropsch syncrudes had a weight ratio of
compounds having at least 60 carbons atoms to compounds having at
least 30 carbon atoms of less than 0.18 and a T.sub.90 boiling
point between 900.degree. F. and 1000.degree. F. Three samples of
the Fischer-Tropsch waxes (one sample of FT Wax A and two samples
of FT Wax B) were hydroisomerized over a Pt/SSZ-32 catalyst or
Pt/SAPO-11 catalyst on an alumina binder. Operating conditions
included temperatures between 652.degree. F. and 695.degree. F.,
LHSVs of 0.6 to 1.0 hr.sup.-1, reactor pressure of 1000 psig, and
once-through hydrogen rates of between 6 and 7 MSCF/bbl. The
reactor effluent passed directly to a second reactor containing a
Pt/Pd on silica-alumina hydrofinishing catalyst also operated at
1000 psig. Conditions in the second reactor included a temperature
of 450.degree. F. and an LHSV of 1.0 hr.sup.-1.
[0125] The products boiling above 650.degree. F. were fractionated
by atmospheric or vacuum distillation to produce distillate
fractions of different viscosity grades. Three Fischer-Tropsch
derived lubricant base oils were obtained: FT-4A (from FT Wax A),
and FT-4B and FT-8B (both from FT Wax B). Test data on specific
distillate fractions useful as the Fischer-Tropsch derived
lubricant base oil are shown below in Table VI. TABLE-US-00005
TABLE VI Properties of Fischer-Tropsch derived lubricant base oils
Properties FT-4A FT-4B FT-8B Hydroisomerization 672 700 694
Temperature, .degree. F. Hydroisomerization Pt/SAPO-11 Pt/SAPO-11
Pt/SAPO-11 Dewaxing Catalyst Reactor Pressure, psig 1000 1000 1000
Viscosity at 100.degree. C., cSt 3.94 4.415 7.953 Viscosity Index
143 147 165 Aromatics, Wt % 0.004 0.008 0.006 FIMS, Wt % of
Molecules Paraffins 89.0 89.1 87.2 Monocycloparaffins 11.0 10.9
12.6 Multicycloparaffins 0.0 0.0 0.2 Total 100.0 100.0 100.0 API
Gravity 42.0 41.6 39.62 Pour Point, .degree. C. -19 -12 -12 Cloud
Point, .degree. C. -9 -8 +13 Ratio of >100 >100 61
Mono/Multicycloparaffins Ratio of Pour Point/Vis100 -4.82 -2.72
-1.51 (SMA consider removing) Base Oil Pour Factor -7.92 -7.09
-2.76 Oxidator BN, Hours No data 41.35 No data Noack Volatility, Wt
% 14.6 10.89 2.72 CCS Viscosity @ -35C, cP 1611 2079 13627
The ratio of pour point and kinematic viscosity at 100.degree. C.
is merely the pour point in .degree. C. divided by the kinematic
viscosity at 100.degree. C. The Base Oil Pour Factor is an
empirical number calculated by the following equation: Base Oil
Pour Factor=7.35.times.Ln (Kinematic Viscosity at 100.degree.
C.)-18, wherein Ln (Kinematic Viscosity at 100.degree. C.) is the
natural logarithm with base "e" of Kinematic Viscosity at
100.degree. C. in cSt.
Example 2
Preparation of Blended Finished Lubricants
[0126] The Fischer-Tropsch derived lubricant base oils prepared
above (FT-4A, FT-4B, and FT-8B) were used to make the blended
finished lubricants.
[0127] Several PAOs of varied kinematic viscosities at 100.degree.
C. were also used to make the blended finished lubricants. The PAOs
used were as follows: Chevron Phillips PAO-4, PAO-8, and PAO-25;
Durasyn.RTM. 174 PAO-40 (Durasyn.RTM. is a registered trademark of
Amoco Chemical Company); and Mobil SHF-1003 PAO-100. The number in
the PAO identifications (i.e., PAO-100) represents the kinematic
viscosities of the PAO at 100.degree. C., in cSt.
[0128] Blends containing both Fischer-Tropsch derived lubricant
base oil and high viscosity PAO (PAO-40 or PAO-100) were formulated
into engine oils using a standard passenger car with
Detergent-Inhibitor (DI) additive package and a pour point
depressant (PPD). No viscosity index improver was added to the
blends, as the viscosity indexes were already very high, and
therefore, it was not necessary to add any viscosity index
improvers. Friction and wear measurements were made on the test
oils using an HFRR, with low HFRR friction coefficients generally
correlated with good fuel economy. Test results on these blends are
shown in Table VII. TABLE-US-00006 TABLE VII Very Low Wear Blends
of FTBO and High Viscosity PAO Description 0W-20 10W-30 Wt % FT-4A
73.36 0 Wt % FT-8B 0 78.5 Wt % Mobil SHF-1003 PAO-100 0 10.85 Wt %
Durasyn .RTM. 174 PAO-40 15.99 0 Wt % DI Additive Package 10.35
10.35 Wt % PPD 0.3 0.3 CCS (cP) 4100 6360 at -35.degree. C. at
-25.degree. C. Viscosity at 100.degree. C. (cSt) 7.093 12.54
Viscosity Index 170 172 Noack Volatility (Weight %) 14.36 3.65 MRV
(cP) 8,442 228,879-YS at -40.degree. C. at -30.degree. C. Oxidator
B, L-4 Catalyst (Hours) Not tested 30.04 HTHS at 150.degree. C.
(cP) 2.22 3.93 TEOST MHT (mg) 33.3 54.2 HFRR Friction Coefficient
0.111 0.104 HFRR Wear Volume Below the Plane 148,645 109,779
(Microns.sup.3) HFRR Net Wear Volume (Microns.sup.3) -1,600 20,086
YS refers to the presence of yield stress in the MRV test.
[0129] The above data demonstrated low wear, as well as excellent
oxidation stability (Oxidator B with L-4 Catalyst) of blends of
.gtoreq.70 wt % Fischer-Tropsch derived lubricant base oils with
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
(FT-4A and FT-8B) and high viscosity PAO (PAO-40 and PAO-100). The
blend with the lowest HFRR coefficient of friction and lowest HFRR
Wear Below the Plane was a blend of .gtoreq.70 wt % Fischer-Tropsch
derived lubricant base oil with .gtoreq.6 weight % molecules with
monocycloparaffinic functionality and high viscosity PAO, where the
difference in the kinematic viscosities at 100.degree. C. between
the Fischer-Tropsch derived lubricant base oil and PAO was greater
than 70 cSt.
[0130] By comparison, as can be seen in Table VIII, blends of
.ltoreq.70 wt % Fischer-Tropsch derived lubricant base oils with
.gtoreq.6 weight % molecules with monocycloparaffinic functionality
(FT-4A or FT-4B) with either low viscosity PAO (PAO-8 and PAO-25)
or high viscosity PAO (PAO-100), exhibited excellent friction and
wear properties, but did not demonstrate the enhanced friction and
wear benefits seen with blends of the present invention containing
.gtoreq.70 wt % Fischer-Tropsch derived lubricant base oil and PAO
having a kinematic viscosity at 100.degree. C. greater than about
30 cSt and less than 150 cSt (PAO-40 and PAO-100). TABLE-US-00007
TABLE VIII Comparison Blends of FT and PAO Description 0W-20 0W-20
5W-30 Wt % FT-4A 31.83 69.87 0 Wt % FT-4B 0 0 66.15 Wt % Chevron
Phillips 57.52 0 0 PAO-8 Wt % Chevron Phillips 0 19.47 0 PAO-25 Wt
% Mobil SHF-1003 0 0 23.2 PAO-100 Wt % DI Additive Package 10.35
10.35 10.35 Wt % PPD 0.3 0.3 0.3 CCS (cP) 5534 3876 5993 at
-35.degree. C. at -35.degree. C. at -30.degree. C. Viscosity at
100.degree. C. 7.555 6.981 11.32 (cSt) Viscosity Index 145 169 161
Noack Volatility 7.19 13.77 9.6 (Weight %) MRV (cP) 11,768 9,600
13,207 at -40.degree. C. at -40.degree. C. at -35.degree. C.
Oxidator B, L-4 Catalyst 28.82 Not tested 23.29 (Hours) HTHS at
150.degree. C. (cP) 2.32 2.41 3.58 TEOST MHT (mg) 28.7 25.9 28.5
HFRR Friction Coefficient 0.116 0.115 0.111 HFRR Wear Volume Below
187,885 182,030 172,120 the Plane (Microns.sup.3) HFRR Net Wear
Volume 55,510 35,960 29,425 (Microns.sup.3)
[0131] Two 0W-20 blends, one with an all-FTBO formulation and one
with an all-PAO formulation, were made. HFRR wear tests were done
on these blends for comparison. The test results on these samples
are shown in Table IX. TABLE-US-00008 TABLE IX Comparison Blends of
All-FTBO and All-PAO All-FTBO All-PAO Description 0W-20 0W-20 Wt %
FT-4B 53.74 0 Wt % FT-8B 35.61 0 Wt % Chevron Phillips PAO-4 0
31.83 Wt % Chevron Phillips PAO-8 0 57.52 Wt % DI Additive Package
10.35 10.35 Wt % PPD 0.3 0.3 CCS (cP) 5660 5534 at -35.degree. C.
at -35.degree. C. Viscosity at 100.degree. C. (cSt) 7.09 7.555
Viscosity Index 167 145 Noack Volatility (Weight %) 8.86 7.19 MRV
(cP) Fail 11,768 (71,156 at -40.degree. C. at -40.degree. C.)
Oxidator B, L-4 Catalyst (Hours) 28.7 28.82 HTHS at 150.degree. C.
(cP) 2.36 2.3 TEOST MHT (mg) 40 28.7 HFRR Friction Coefficient
0.110 0.116 HFRR Wear Volume Below the Plane 170,340 180,560
(Microns.sup.3) HFRR Net Wear Volume (Microns.sup.3) 30,190
38,975
[0132] While these comparison results demonstrated that
all-Fischer-Tropsch derived lubricant base oil blends give better
frictional properties and lower wear than all-PAO blends, it was
found that a blend of the same viscosity grade, 0W-20, comprised of
a mixture of .gtoreq.70 wt % Fischer-Tropsch derived lubricant base
oil and higher viscosity PAO (PAO-100), had significantly lower
wear than the all-Fischer-Tropsch derived lubricant base oil blend.
It was surprising that the blends having the mixture of .gtoreq.70
wt % Fischer-Tropsch lubricant base oil and high viscosity PAOs
gave reductions in HFRR Wear Volume Below the Plane of 12.7 %
(0W-20) and 35.6% (10W-30).
[0133] While the present invention has been described with
reference to specific embodiments, this application is intended to
cover those various changes and substitutions that may be made by
those of ordinary skill in the art without departing from the
spirit and scope of the appended claims.
* * * * *