U.S. patent application number 10/517901 was filed with the patent office on 2005-07-28 for method and composition for using stabilized beta-carotene as cetane improver in hydrocarbonaceous diesel fuels.
This patent application is currently assigned to Oryxe Energy International, Inc.. Invention is credited to Jordan, Frederick L.
Application Number | 20050160662 10/517901 |
Document ID | / |
Family ID | 34799561 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050160662 |
Kind Code |
A1 |
Jordan, Frederick L |
July 28, 2005 |
Method and composition for using stabilized beta-carotene as cetane
improver in hydrocarbonaceous diesel fuels
Abstract
A diesel fuel additive is provided that includes beta-carotene
stabilized with 2,2,4-trimethyl-6-ethoxy-1,2-dihydro-quinoline. The
additive may be added to any liquid hydrocarbon fuel, solid
hydrocarbon fuel, or other hydrocarbonaceous combustible fuel to
reduce emissions of undesired components during combustion of the
fuel, provide improved fuel economy, engine cleanliness, and/or
performance. A method for preparing the additive is also
provided.
Inventors: |
Jordan, Frederick L; (Santa
Ana, CA) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI, LLP
1301 MCKINNEY
SUITE 5100
HOUSTON
TX
77010-3095
US
|
Assignee: |
Oryxe Energy International,
Inc.
Irvine
CA
92618
|
Family ID: |
34799561 |
Appl. No.: |
10/517901 |
Filed: |
December 10, 2004 |
PCT Filed: |
June 10, 2003 |
PCT NO: |
PCT/US03/18282 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60388385 |
Jun 11, 2002 |
|
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60409114 |
Sep 5, 2002 |
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Current U.S.
Class: |
44/329 |
Current CPC
Class: |
C10L 1/1608 20130101;
C10L 1/301 20130101; C10L 1/14 20130101; C10L 1/1616 20130101; C10L
1/1802 20130101; C10L 1/1852 20130101; B01J 13/02 20130101; C10L
1/231 20130101; C10L 1/232 20130101; C10L 1/1824 20130101; C10L
10/12 20130101; C10L 10/02 20130101 |
Class at
Publication: |
044/329 |
International
Class: |
C10L 001/18 |
Claims
What is claimed is:
1. A diesel fuel cetane improver, the cetane improver comprising:
beta-carotene; and
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.
2. A diesel fuel cetane improver, the cetane improver comprising: a
cetane improving additive selected from the group consisting of
carotenes, carotenoids, carotene derivatives, carotene precursors,
carotenoid derivative, carotenoid precursors, long chain olefinic
compounds, and mixtures thereof; and a stabilizing compound that
inhibits oxidation of the cetane improving additive.
3. The diesel fuel cetane improver of claim 2, wherein the
stabilizing compound comprises
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.
4. The diesel fuel cetane improver of claim 2, further comprising a
plant oil extract and a thermal stabilizer.
5. The diesel fuel cetane improver of claim 4, wherein the plant
oil extract comprises an oil extract of a plant of the Leguminosae
family.
6. The diesel fuel cetane improver of claim 4, wherein the plant
oil extract comprises oil extract of barley.
7. The diesel fuel cetane improver of claim 4, wherein the plant
oil extract comprises chlorophyll.
8. The diesel fuel cetane improver of claim 4, wherein the thermal
stabilizer comprises jojoba oil.
9. The diesel fuel cetane improver of claim 4, wherein the thermal
stabilizer comprises an ester of a C20-C22 straight chain
monounsaturated carboxylic acid.
10. The diesel fuel cetane improver of claim 4, wherein the plant
oil extract comprises oil extract of barley and the thermal
stabilizer comprises jojoba oil.
11. The diesel fuel cetane improver of claim 2, further comprising
a diluent.
12. The diesel fuel cetane improver of claim 11, wherein the
diluent is selected from the group consisting of toluene, gasoline,
diesel fuel, jet fuel, and mixtures thereof.
13. The diesel fuel cetane improver of claim 2, further comprising
an oxygenate.
14. The diesel fuel cetane improver of claim 13, wherein the
oxygenate is selected from the group consisting of methanol,
ethanol, methyl tertiary butyl ether, ethyl tertiary butyl ether,
and tertiary amyl methyl ether, and mixtures thereof.
15. The diesel fuel cetane improver of claim 2, further comprising
at least one additional additive selected from the group consisting
of octane improvers, cetane improvers, detergents, demulsifiers,
corrosion inhibitors, metal deactivators, ignition accelerators,
dispersants, anti-knock additives, anti-run-on additives,
anti-pre-ignition additives, anti-misfire additives, antiwear
additives, antioxidants, thermal stabilizers, plant oil extracts,
demulsifiers, carrier fluids, solvents, fuel economy additives,
emission reduction additives, lubricity improvers, and mixtures
thereof
16. The diesel fuel cetane improver of claim 1, wherein a ratio of
grams of beta-carotene to grams of
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinolin- e in the additive is
from about 20:1 to about 1:1.
17. The diesel fuel cetane improver of claim 1, wherein a ratio of
grams of beta-carotene to grams of
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinolin- e in the additive is
from about 15:1 to about 5:1.
18. The diesel fuel cetane improver of claim 1, wherein a ratio of
grams of beta-carotene to grams of
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinolin- e in the additive is
about 10:1.
19. The diesel fuel cetane improver of claim 2, further comprising
2-ethylhexyl nitrate.
20. An additized diesel fuel, the diesel fuel comprising a base
fuel and a fuel additive for use in improving cetane number, the
fuel additive comprising: beta-carotene; and
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinol- ine.
21. An additized diesel fuel, the diesel fuel comprising a base
diesel fuel and a fuel additive for use in improving cetane number,
the fuel additive comprising: a cetane improving additive selected
from the group consisting of carotenes, carotenoids, carotene
derivatives, carotene precursors, carotenoid derivative, carotenoid
precursors, long chain olefinic compounds, and mixtures thereof;
and a stabilizing compound that inhibits oxidation of the cetane
improving additive.
22. The additized diesel fuel of claim 20, wherein the fuel
comprises from about 0.00025 g to about 0.05 g beta-carotene per
3785 ml additized diesel fuel and from about 0.000025 g to about
0.005 g ethoxyquin per 3785 ml additized diesel fuel.
23. The additized diesel fuel of claim 20, wherein the fuel
comprises from about 0.00053 g to about 0.021 g beta-carotene per
3785 ml additized diesel fuel and from about 0.000053 g to about
0.0021 g ethoxyquin per 3785 ml additized diesel fuel.
24. A method for producing an additized diesel fuel, the method
comprising the steps of: preparing a first additive by combining
beta-carotene, ethoxyquin, jojoba oil, and a diluent, the first
additive comprising about 4 ml jojoba oil, about 4 g beta-carotene,
and about 0.4 g ethoxyquin per 3785 ml of the first additive;
preparing a second additive by combining an oil extract of barley,
jojoba oil, and a diluent, the second additive comprising about 4
ml jojoba oil and about 19.36 g oil extract of barley per 3785 ml
of the second additive; and adding the first additive and the
second additive to a base diesel fuel to produce all additized
diesel fuel, such that the additized diesel fuel comprises from
about 0.15 ml to about 20 ml of the first additive per 3785 ml of
additized diesel fuel and from about 0.3 ml to about 3.6 ml of the
second additive per 3785 ml of additized diesel fuel.
25. A method for producing an additized diesel fuel, the method
comprising the steps of: preparing a first additive by combining
beta-carotene, ethoxyquin, jojoba oil, and a diluent, the first
additive comprising about 32 ml jojoba oil, about 3.2 g ethoxyquin,
about 32 g beta-carotene per 3785 ml of the first additive;
preparing a second additive by combining an oil extract of barley,
jojoba oil, and a diluent, the second additive comprising about 32
ml jojoba oil and about 155 g oil extract of barley per 3785 ml of
the second additive; and adding the first additive and the second
additive to a base diesel fuel to produce an additized diesel fuel,
such that the additized diesel fuel comprises from about 0.0625 ml
to about 0.625 ml of the first additive per 3785 ml of additized
diesel fuel and from about 0.3 ml to about 0.45 ml of the second
additive per 3785 ml of additized diesel fuel.
26. A gum inhibitor for gasoline, the gum inhibitor comprising:
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.
27. A gasoline composition comprising
2,2,4-trimethyl-6-ethoxy-1,2-dihydro- quinoline.
28. The gasoline composition of claim 27, wherein the
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline is present in the
gasoline composition at a concentration of about 50 to 1000
ppm.
29. The gasoline composition of claim 27, wherein the
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline is present in the
gasoline composition at a concentration of about 100 to 500
ppm.
30. The gasoline composition of claim 27, wherein the
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline is present in the
gasoline composition at a concentration of about 200 to 400 ppm.
Description
FIELD OF THE INVENTION
[0001] A diesel fuel additive is provided that includes
beta-carotene stabilized with
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline. The additive may be
added to any liquid hydrocarbon fuel, solid hydrocarbon fuel, or
other hydrocarbonaceous combustible fuel to reduce emissions of
undesired components during combustion of the fuel, provide
improved fuel economy, engine cleanliness, and/or performance. A
method for preparing the additive is also provided.
BACKGROUND OF THE INVENTION
[0002] Hydrocarbon fuels typically contain a complex mixture of
hydrocarbons, namely, molecules containing various configurations
of hydrogen and carbon atoms. They may also contain various
additives, including detergents, anti-oxidants, anti-icing agents,
emulsifiers, corrosion inhibitors, dyes, deposit modifiers, and
non-hydrocarbons such as oxygenates.
[0003] When such hydrocarbon fuels are combusted, a variety of
pollutants are generated. These combustion products include ozone,
particulates, carbon monoxide, nitrogen dioxide, sulfur dioxide,
and lead. Both the U.S. Environmental Protection Agency (EPA) and
the California Air Resources Board (CARB) have adopted ambient air
quality standards directed to these pollutants. Both agencies have
also adopted specifications for lower-emission gasolines.
[0004] The Phase II California Reformulated Gasoline (CaRFG2)
regulations became operative in Mar. 1, 1996. Governor Davis signed
Executive Order D-5-99 on Mar. 25, 1999, which directs the
phase-out of methyl tertiary butyl ether (MTBE) in California's
gasoline by Dec. 31, 2002. The Phase III California Reformulated
Gasoline (CaRFG3) regulations were approved on Aug. 3, 2000, and
became operative on Sep. 2, 2000. The CaRFG2 and CaRFG3 standards
are presented in Table A.
1TABLE A The California Reformulated Gasoline Phase 2 and Phase 3
Specifications Flat Limits Averaging Limits Cap Limits CaRFG CaRFG
CaRFG CaRFG CaRFG CaRFG CaRFG Phase Phase CaRFG Phase Phase CaRFG
Phase Phase Property Phase I II III Phase I II III Phase I II III
Reid n/a 7.0 7.0 or 7.8 n/a n/a n/a 7.0 6.4-7.2 Vapor 6.9 Pressure
(psi) Sulfur n/a 40 20 151 30 15 n/a 80 60 Content 30 (wt. ppm)
Benzene n/a 1.0 0.8 1.7 0.8 0.7 n/a 1.2 1.1 Content (vol. %)
Aromatics n/a 25 25 32 22 22 n/a 30 35 Content (vol. %) Olefins n/a
6.0 6.0 9.6 4.0 4.0 n/a 10.0 10.0 Content (vol. %) T50 n/a 210 213
212 200 203 n/a 220 220 (.degree. F.) T90 n/a 300 305 329 290 295
n/a 330 330 (.degree. F.) Oxygen n/a 1.8-2.2 1.8-2.2 n/a n/a n/a
n/a 1.8-3.5 1.8-3.5 Content 0-3.5 0-3.5 (wt. %) MTBE n/a n/a
Prohibited n/a n/a n/a n/a n/a Prohibited and Other Oxygenates
(other than ethanol) n/a = not applicable
[0005] Considerable effort has been expended by the major oil
companies to formulate gasolines that comply with the EPA and CARB
standards. The most common approach to formulating compliant
gasolines involves adjusting refinery processes so as to produce a
gasoline base fuel meeting the specifications set forth above. Such
an approach suffers a number of drawbacks, including the high costs
involved in reconfiguring a refinery process, possible negative
effects on the quantity or quality of other refinery products, and
the inflexibility associated with having to produce a compliant
base gasoline.
[0006] As with gasoline, diesel fuels may also be subject to
regulation. Diesel fuels of poor quality may not be suitable for
use until and unless they are brought up to specification. This is
also typically accomplished in a refinery-based process, which
suffers the same drawbacks as described above for refinery process
for upgrading gasoline base fuel.
SUMMARY OF THE INVENTION
[0007] Conventional refinery-based processes for producing quality
diesel fuels of acceptable cetane number suffer from a number of
drawbacks. A method of producing quality diesel fuels that does not
suffer these drawbacks is therefore desirable. Methods of preparing
beta-carotene-containing diesel fuel additives and diesel fuel,
wherein the methods may be conducted under ambient conditions
rather than an inert atmosphere as in prior art methods, is also
desirable.
[0008] A diesel fuel additive is provided which may be combined
with conventional diesel fuels so as to yield a diesel fuel with
improved cetane number. Because an additive is used to produce
improved diesel fuels, the equipment and product costs associated
with a refinery solution are avoided. The additive may also be
combined with other hydrocarbon fuels, such as gasoline fuels, jet
fuels, two-cycle fuels, coals, and other hydrocarbonaceous fuels to
reduce the emission of pollutants during combustion of the fuel, to
improve combustion, to improve fuel economy, and/or to provide
other benefits.
[0009] In a first embodiment, a diesel fuel cetane improver is
provided, the cetane improver including beta-carotene; and
2,2,4-trimethyl-6-ethoxy- -1,2-dihydroquinoline.
[0010] In a second embodiment, a diesel fuel cetane improver is
provided, the cetane improver including a cetane improving additive
selected from the group consisting of carotenes, carotenoids,
carotene derivatives, carotene precursors, carotenoid derivative,
carotenoid precursors, long chain olefinic compounds, and mixtures
thereof; and a stabilizing compound that inhibits oxidation of the
cetane improving additive.
[0011] In an aspect of the second embodiment, the stabilizing
compound includes
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.
[0012] In an aspect of the second embodiment, the cetane improver
further includes a plant oil extract and a thermal stabilizer.
[0013] In an aspect of the second embodiment, the plant oil extract
includes an oil extract of a plant of the Leguminosae family.
[0014] In an aspect of the second embodiment, the plant oil extract
includes oil extract of barley.
[0015] In an aspect of the second embodiment, the plant oil extract
includes chlorophyll.
[0016] In an aspect of the second embodiment, the thermal
stabilizer includes jojoba oil.
[0017] In an aspect of the second embodiment, the thermal
stabilizer includes an ester of a C20-C22 straight chain
monounsaturated carboxylic acid.
[0018] In an aspect of the second embodiment the plant oil extract
includes oil extract of barley and the thermal stabilizer includes
jojoba oil.
[0019] In an aspect of the second embodiment, the cetane improver
further includes a diluent.
[0020] In an aspect of the second embodiment, the diluent is
selected from the group consisting of toluene, gasoline, diesel
fuel, jet fuel, and mixtures thereof.
[0021] In an aspect of the second embodiment, the cetane improver
further includes an oxygenate.
[0022] In an aspect of the second embodiment, the oxygenate is
selected from the group consisting of methanol, ethanol, methyl
tertiary butyl ether, ethyl tertiary butyl ether, and tertiary amyl
methyl ether, and mixtures thereof.
[0023] In an aspect of the second embodiment the cetane improver
further includes at least one additional additive selected from the
group consisting of octane improvers, cetane improvers, detergents,
demulsifiers, corrosion inhibitors, metal deactivators, ignition
accelerators, dispersants, anti-knock additives, anti-run-on
additives, anti-pre-ignition additives, anti-misfire additives,
antiwear additives, antioxidants, thermal stabilizers, plant oil
extracts, demulsifiers, carrier fluids, solvents, fuel economy
additives, emission reduction additives, lubricity improvers, and
mixtures thereof.
[0024] In an aspect of the first embodiment, a ratio of grams of
beta-carotene to grams of
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline in the additive is
from about 20:1 to about 1:1.
[0025] In an aspect of the first embodiment, a ratio of grams of
beta-carotene to grams of
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline in the additive is
from about 15:1 to about 5:1.
[0026] In an aspect of the first embodiment, a ratio of grams of
beta-carotene to grams of
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline in the additive is
about 10:1.
[0027] In an aspect of the second embodiment, the diesel fuel
cetane improver further includes 2-ethylhexyl nitrate.
[0028] In a third embodiment, an additized diesel fuel is provided,
the diesel fuel including a base fuel and a fuel additive for use
in improving cetane number, the fuel additive including
beta-carotene; and
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.
[0029] In a fourth embodiment, an additized diesel fuel is
provided, the diesel fuel including a base diesel fuel and a fuel
additive for use in improving cetane number, the fuel additive
including a cetane improving additive selected from the group
consisting of carotenes, carotenoids, carotene derivatives,
carotene precursors, carotenoid derivative, carotenoid precursors,
long chain olefinic compounds, and mixtures thereof; and a
stabilizing compound that inhibits oxidation of the cetane
improving additive.
[0030] In an aspect of the fourth embodiment, the fuel includes
from about 0.00025 g to about 0.05 g beta-carotene per 3785 ml
additized diesel fuel and from about 0.000025 g to about 0.005 g
ethoxyquin per 3785 ml additized diesel fuel.
[0031] In an aspect of the fourth embodiment, the fuel includes
from about 0.00053 g to about 0.021 g beta-carotene per 3785 ml
additized diesel fuel and from about 0.000053 g to about 0.0021 g
ethoxyquin per 3785 ml additized diesel fuel.
[0032] In a fifth embodiment, a method for producing an additized
diesel fuel is provided, the method including the steps of
preparing a first additive by combining beta-carotene, ethoxyquin,
jojoba oil, and a diluent, the first additive including about 4 ml
jojoba oil, about 4 g beta-carotene, and about 0.4 g ethoxyquin per
3785 ml of the first additive; preparing a second additive by
combining an oil extract of barley, jojoba oil, and a diluent, the
second additive including about 4 ml jojoba oil and about 19.36 g
oil extract of barley per 3785 ml of the second additive; and
adding the first additive and the second additive to a base diesel
fuel to produce an additized diesel fuel, such that the additized
diesel fuel includes from about 0.15 ml to about 20 ml of the first
additive per 3785 ml of additized diesel fuel and from about 0.3 ml
to about 3.6 ml of the second additive per 3785 ml of additized
diesel fuel.
[0033] In a fifth embodiment, a method for producing an additized
diesel fuel is provided, the method including the steps of
preparing a first additive by combining beta-carotene, ethoxyquin,
jojoba oil, and a diluent, the first additive including about 32 ml
jojoba oil, about 3.2 g ethoxyquin, about 32 g beta-carotene per
3785 ml of the first additive; preparing a second additive by
combining an oil extract of barley, jojoba oil, and a diluent, the
second additive including about 32 ml jojoba oil and about 155 g
oil extract of barley per 3785 ml of the second additive; and
adding the first additive and the second additive to a base diesel
fuel to produce an additized diesel fuel, such that the additized
diesel fuel includes from about 0.0625 ml to about 0.625 ml of the
first additive per 3785 ml of additized diesel fuel and from about
0.3 ml to about 0.45 ml of the second additive per 3785 ml of
additized diesel fuel.
[0034] In a sixth embodiment, a gum inhibitor for gasoline is
provided, the gum inhibitor including
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline- .
[0035] In a seventh embodiment, a gasoline composition including
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline is provided.
[0036] In an aspect of the seventh embodiment, the
2,2,4-trimethyl-6-ethox- y-1,2-dihydroquinoline is present in the
gasoline composition at a concentration of about 50 to 1000
ppm.
[0037] In an aspect of the seventh embodiment, the
2,2,4-trimethyl-6-ethox- y-1,2-dihydroquinoline is present in the
gasoline composition at a concentration of about 100 to 500
ppm.
[0038] In an aspect of the seventh embodiment, the
2,2,4-trimethyl-6-ethox- y-1,2-dihydroquinoline is present in the
gasoline composition at a concentration of about 200 to 400
ppm.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] Introduction
[0040] The following description and examples illustrate preferred
embodiments of the present invention in detail. Those of skill in
the art will recognize that there are numerous variations and
modifications of this invention that are encompassed by its scope.
Accordingly, the description of preferred embodiments should not be
deemed to limit the scope of the present invention.
[0041] Cetane Improving Additive Formulation
[0042] The emissions reduction additive formulation contains two
components: beta-carotene or a suitable substitute, as described
below, and 2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline or a
suitable substitute, as described below. In preferred embodiments,
the additive formulation further contains as an optional additive a
conventional cetane-improving additive, such as 2-ethylhexyl
nitrate.
[0043] Virtually all practical uses of fossil energy involve
combustion processes, whereby a fuel is combined with oxygen from
the air to release heat from oxidation reactions. The fuel and
oxygen will react when heated to a sufficiently high temperature,
allowing a certain threshold energy level to be overcome. This
threshold level, called the "Arrhenius Activation Energy," is
strongly dependent on temperature, with higher temperatures
resulting in lower required energy levels. The activation energy
can also be lowered by other factors, such as the presence of
catalysts.
[0044] The additives of preferred embodiments may be different from
catalysts, in that it is believed that they lower the activation
energy and are consumed in the combustion process. In contrast,
catalysts promote the reaction and lower the activation energy but
are not consumed in the combustion process. While not wishing to be
bound to any particular theory, it is believed that the active
materials in the formulations of preferred embodiments, which are
typically derived from plants and other renewable resource
biodegradable materials, weaken the bonds of longer hydrocarbon
chains at pre-combustion temperatures. The additives also bind
oxygen from the fuel-air mixture, thus promoting the proximity of
oxygen and hydrocarbons at a sub-molecular level. The improved
mixing and lower activation energy may result in a more complete
combustion process, reducing unwanted byproducts such as carbon
monoxide and hydrocarbon emissions, while at the same time
improving the overall efficiency of combustion. Lower combustion
temperatures across a more even flame front also generally result
in lower NOx emissions. Since the early work on tetraethyl lead and
other antiknock agents by Charles F. Kettering and others in the
1920's, it has been recognized that small amounts of additives may
have a substantial impact on the way a flame front propagates (or
burns) within the cylinder of an internal-combustion engine.
[0045] Although it is believed that certain components present in
the formulations of preferred embodiments may bind oxygen for
release during the combustion reaction process, they are not
generally considered "oxygenates" as the term is conventionally
used in the field of hydrocarbon-based fuel formulations.
Oxygenates, such as methyl tert-butyl ether (MTBE) and ethanol are
chemical compounds that contain oxygen in the molecular chain. When
fuel and air are heated in the presence of an oxygenate, such as
MTBE, the oxygenate decomposes at the onset of ignition, releasing
free radicals. Free radicals facilitate the break-up of hydrocarbon
chains, promoting combustion. Because oxygenates release their free
radicals only once the ignition temperature is reached and because
they suppress reactions ahead of the flame front, they also
generally act as octane enhancers. When fuel and air are heated in
the presence of the formulations of preferred embodiments, the
components of the formulation contribute to weakening the
hydrocarbon structure and capture oxygen. Proximity effects of the
combustion agents lower the activation energy, accelerating
combustion. The formulations of preferred embodiments may smooth
out the flame front, providing a more uniform heat distribution,
better stoichiometric (air to fuel ratio) combustion, and create a
detergency effect that helps to prevent the build up of carbon
deposits. The action of oxygenates can be compared to "pushing"
oxygen into the combustion reaction by releasing it from their
inherent molecular structures, whereas the formulations of
preferred embodiments may be viewed as "pulling" oxygen out of the
fuel-air mixture and into the combustion process.
[0046] While not wishing to be bound to any particular theory, it
is believed that compounds containing a long hydrocarbon chain,
(namely, a hydrocarbon chain comprising about five, six or seven
carbon atoms, preferably about eight or nine carbon atoms, more
preferably about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more
carbon atoms) with one, two, three or more olefinic linkages are
particularly reactive under combustion conditions. Accordingly,
long chain olefinic (unsaturated) compounds, such as beta-carotene,
may provide an enhanced cetane improving effect, especially when
compared to conventional cetane improving additives such as
2-ethylhexyl nitrate (2EHN).
[0047] It is known that a beta-carotene-containing additive
prepared under an inert atmosphere and added to a diesel fuel under
an inert atmosphere is an effective cetane-improving additive for
diesel fuel. See co-pending PCT Publication No. WO01/79398 filed
Apr. 12, 2001; U.S. application Ser. No. 10/084,838 filed on Feb.
26, 2002; U.S. application Ser. No. 10/084,602 filed on Feb. 26,
2002; U.S. application Ser. No. 10/084,603 filed on Feb. 26, 2002;
U.S. application Ser. No. 10/084,237 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,835 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,601 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,836 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,579 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,243 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,833 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,236 filed on Feb. 26, 2002; U.S.
application Ser. No. 10/084,831 filed on Feb. 26, 2002; PCT
Application No. US02/06137 filed on Feb. 26, 2002; and Canadian
Application No. 2,373,327 filed on Feb. 26, 2002.
[0048] In contrast, when beta-carotene is added to diesel fuel
according to conventional preparation methods (e.g., under ambient
atmosphere), the beta-carotene rapidly loses its effectiveness as a
cetane improver. The stability of beta-carotene and other carotenes
and carotenoids have been the subject of a number of studies,
particularly in regard to the stability of such compounds in foods
and food products. See, e.g., "Stability of Beta-Carotene in
Isolated Systems" in J. Food Technol. (1979), 14(6), 571-8; "Use of
Beta-Carotene in Extrusion-Cooking" in Ind. Aliment. Agric. (1986),
103(6), 527-32; "Thermal Degradation of Beta-Carotene--Formation of
Nonvolatile Compound by Thermal Degradation of Beta-Carotene:
Protection by Antioxidants" in Methods in Enzymology, Vol. 213,
(1992), Acad. Press, Inc., 129-142; U.S. Pat. No. 4,504,499
entitled "Heat-Stabilized, Carotenoid-Colored Edible Oils";
"Beta-Lactoglobulin Protects Beta-Ionone-Related Compound from
Degradation by Heating, Oxidation, and Irradiation" in Biosci.
Biotech. Biochem. (1995), 59(12), 2295-2297; "Study of the Effect
of Some Antioxidants on the Stability of Beta-Carotene in an
Ointment Containing Extracts from Flos arnicae and Herba
calendulae" in Herba Pol. (1981), 27(1), 39-43; "Thermal
Degradation of All-Trans-Beta-Carotene in the Presence of
Phenylalanine" in J. Sci. Food Agric. (1994), 65(4), 373-9;
"Kinetics of All-Trans-Beta-Carotene Degradation on Heating With
and Without Phenylalanine" in J. Am. Oil Chem. Soc. (1994), 71(8),
893-6; "Proposal of a Mechanism for the Inhibition of
All-Trans-Beta-Carotene Autoxidation at Elevated Temperature by
N-(2-phenylethyl)-3,4-Diphenylpyr- role" in Food Chem. (1995),
54(3), 251-3; "The Stability of Beta-Carotene Under Different
Laboratory Conditions" in J. Nutr. Biochem. (1992), 3(3), 124-8;
"Inhibition of Beta-Carotene Oxidation in an Aromatic Solvent" in
Izv. Akad. Nauk SSR, Ser. Khim. (1972), (2), 312-16; "Kinetics and,
Mechanism of Oxidation and Stabilization of Beta-Carotene" in
Vitam. Vitam. Prep. (1973), 232-40; "Efficient Search for New
Antioxidants as Stabilizers of Carotene in Dehydrated Feeds" in
Fiziol.-Biokhim. Osn. Povysh. Prod. Sel'skokhoz. Zhivotn. (1971),
232-41; and "Tetaahydroquinone Derivatives as Feed Antioxidants" in
Sin. Issled. Eff. Khim. Polim. Mater. (1970), (4), 283-8.
[0049] Encapsulation of beta-carotene and other carotenoid and the
use of other preservation and protection methods for improving
stability have also been investigated. See, e.g., "Comparison of
Spray Drying, Drum Drying and Freeze Drying for Beta-Carotene
Encapsulation and Preservation" in J. Food Sci. (1997), 62(6),
1158-1162; "Preservation of Beta-Carotene from Carrots" in Crit.
Rev. Food Sci. Nutr. (1998), 38(5), 381-396; "Influence of
Maltodextrin Systems at an Equivalent 25DE on Encapsulated
Beta-Carotene" in J. Food Process. Preserv. (1999), 23(1), 39-55;
"Kinetic Studies of Degradation of Saffron Carotenoids Encapsulated
in Amorpohous Polymer Matrices" in Food Chemistry (2000), 71(2),
199-206; "Stability of Spray-Dried Encapsulated Carrot Carotenes"
in J. Food Sci. (1995), 60(5), 1048-53.
[0050] None of these references, however, discusses stabilizers or
preservation methods for use with beta-carotene or other carotenes
and carotenoids when used as cetane improvers, much less the
efficacy of such methods in enabling beta-carotene-containing
cetane improvers to retain their cetane improving properties when
prepared or added to fuel in ambient conditions, or in fuels stored
under ambient conditions. Unexpectedly, it has been discovered that
beta-carotene or other carotenes and carotenoids, when combined
with certain stabilizing components or subjected to certain
preservation techniques, retains its effectiveness as a cetane
improving additive when formulated into an additive package under
ambient conditions or when present in additized fuel stored under
ambient conditions.
[0051] Beta-Carotene
[0052] One component of the formulations of preferred embodiments
is beta-carotene. The beta-carotene may be added to the base
formulation as a separate component in a purified form, or may be
present or naturally occurring in another component, such as, for
example, a plant oil extract as described below. Beta-Carotene is a
high molecular weight antioxidant. In plants, it functions as a
scavenger of oxygen radicals and protects chlorophyll from
oxidation.
[0053] The beta-carotene may be natural or synthetic. In a
preferred form, the beta-carotene is in natural form and contains a
mixture of naturally occurring isomers, i.e., a mixture of the cis
and trans isomers. In another preferred form, the beta-carotene is
synthetic, but contains a mixture of isomers similar to that
observed for natural beta-carotene. In other embodiments, in may be
preferred that the beta-carotene include only trans-beta-carotene,
only cis-beta-carotene, or a mixture of the cis and trans isomers
in various ratios. Other isomers, enantiomers, stereoisomers, or
substituted forms of beta-carotene may also be suitable for
use.
[0054] In a preferred embodiment, the beta-carotene is provided in
a form equivalent to vitamin A having a purity of 1.6 million units
of vitamin A activity. Vitamin A of lesser or greater purity may
also be suitable for use. It may be desirable to adjust the amount
of beta-carotene utilized depending upon the activity. It is
particularly preferred to adjust the amount to yield an equivalent
activity to 1.6 million units of vitamin A activity. For example,
if the purity is 800,000 units of vitamin A activity, the amount
used is doubled to yield the desired activity.
[0055] Precursors, derivatives, or substituted versions, of
beta-carotene or other carotenes or carotenoids, for example,
vitamin A, may be suitable for use in preferred embodiments.
Alkoxylated derivatives, including methoxylated and ethoxylated
derivatives of carotenes and carotenoids may also be suitable for
use, as well as esters of carotenes and carotenoids. Suitable
substituted versions may include hydrocarbyl substituted versions,
including straight and branched hydrocarbyl groups, alkyl, alkenyl,
aryl, alkylaryl, arylalkyl, cycloalkyl, alkynyl groups, and any
combination thereof Heteroatom substituted versions, or versions
with other substituents may also be suitable for use. All isomeric
forms, including stereoisomers, geometric isomers, optical isomers,
enantiomers, and the like, are also suitable for use.
[0056] While beta-carotene is preferred in many embodiments, in
other embodiments it may be desirable to substitute another
carotene or carotenoid, for example, alpha-carotene or carotenoids
as described below, for beta-carotene. Alternatively, another
component may supplement the beta-carotene, including, but not
limited to, alpha-carotene, or additional carotenoids from algae
xeaxabthin, crypotoxanthin, lycopene, lutein, broccoli concentrate,
spinach concentrate, tomato concentrate, kale concentrate, cabbage
concentrate, brussels sprouts concentrate and phospholipids, green
tea extract, milk thistle extract, curcumin extract, quercetin,
bromelain, cranberry and cranberry powder extract, pineapple
extract, pineapple leaves extract, rosemary extract, grapeseed
extract, ginkgo biloba extract, polyphenols, flavonoids, ginger
root extract, hawthorn berry extract, bilberry extract, butylated
hydroxytoluene (BHT), oil extract of marigolds, any and all oil
extracts of carrots, fruits, vegetables, flowers, grasses, natural
grains, leaves from trees, leaves from hedges, hay, any living
plant or tree, and combinations or mixtures thereof.
[0057] Vegetable carotenoids of guaranteed potency are particularly
preferred, including those containing lycopene, lutein,
alpha-carotene, other carotenoids from carrots or algae, betatene,
and natural carrot extract. The vegetable carotenoids are
particularly preferred as substitutes for beta-carotene or in
combination with beta-carotene.
[0058] Any suitable isomeric form or mixture of isomeric forms of
carotenes or carotenoids may be employed in preferred embodiments.
Pure carotenes or carotenoids, or mixtures of two or more carotenes
and/or carotenoids may also be suitable for use in certain
embodiments. Suitable substitutes for the carotenes and carotenoids
described above include compounds containing a long hydrocarbon
chain, (namely, a hydrocarbon chain comprising about five, six or
seven carbon atoms, preferably about eight or nine carbon atoms,
more preferably about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or
more carbon atoms) with one, two, three, or more olefinic linkages.
Such compounds may be also be present in combination with the
carotenes and/or carotenoids.
[0059] The carotene, carotenoid, or precursor, derivative, or
substituted version thereof may be natural, e.g., plant derived, or
synthetic. It may also be produced by genetically engineered,
altered, or modified organisms, e.g., algae, bacteria,
microorganisms, or plants. It may be particularly preferred to
utilize a carotene or carotenoid or related compound obtained from
a plant that has been genetically engineered to yield relatively
high levels of the compound, relatively high levels of a preferred
isomeric form, or a particularly preferred ratio or combination of
carotenes or carotenoids or other components.
[0060] While not wishing to be limited to any particular mechanism,
it is believed that the beta-carotene in the formulations of
preferred embodiments may scavenge oxygen radicals in the
combustion process or may act as an oxygen solubilizer or oxygen
getter for the available oxygen that is present in the air/fuel
stream for combustion.
[0061] The beta-carotene is typically added hi a liquid form to the
diesel fuel formulation. In addition to adding beta-carotene in a
liquid form to a fuel formulation, beta-carotene may also be added
in solid form, for example, in dehydrated form, or in the form of
an encapsulated liquid or solid, as described in detail below. The
preservation and storage of solutions or suspensions of
beta-carotene or other plant-based materials may carry benefits,
such as reduced weight and storage space, and increased stability
and resistance to oxidation. Beta-Carotene in dehydrated form may
be prepared by methods including freeze-drying, vacuum or
air-drying, lyophilization, spray-drying, fluidized bed drying, and
other preservation and dehydration methods as are known in the art.
Beta-Carotene in dehydrated form may be added to fuel in the
dehydrated form, or may be added as a reconstituted liquid in an
appropriate solvent. In a preferred embodiment, a solid containing
beta-carotene is added to the fuel to be additized. Suitable solid
forms include, but are not limited to, tablets, granules, powders,
encapsulated solids and/or encapsulated liquids, and the like.
Additional components may also be present in the solid form. Any
suitable encapsulating material may be used, preferably a polymeric
or other material that is soluble in the fuel to be additized. The
encapsulating material dissolves in the fuel, releasing the
encapsulated material. The tablet preferably dissolves in the fuel
over an acceptable period of time. Dissolving aids may be included
hi the tablet, e.g., small granules or particles of active
ingredient may be present in a matrix with high solubility in the
fuel. A combination of solid and liquid dosing methods may be
utilized, and the solid may be added to the fuel at any preferred
time, e.g., by the consumer directly to a vehicle's fuel tank, to
bulk fuel in the refinery, and the like. In certain embodiments, it
may be preferred to utilize a combination of additive forms, e.g.,
liquid and solid, as will be appreciated by one skilled in the
art.
2,2,4-Trimethyl-6-Ethoxy-1,2-Dihydroquinoline
[0062] The beta-carotene or other long chain olefinic compound in
the formulations of preferred embodiments is present in combination
with a stabilizing compound. The stabilizing compound enables the
beta-carotene to retain its cetane improving properties despite the
presence of ambient atmosphere during the preparation of the
additive package, the additization of the diesel fuel, or the
storage of the diesel fuel.
[0063] In a particularly preferred embodiment, the stabilizing
compound contains a quinoline moiety, preferably
2,2,4-trimethyl-6-ethoxy-1,2-dihy- droquinoline, commonly referred
to as ethoxyquin. The compound is marketed under the trademark
SANTOQUIN.RTM. by Solutia Inc. of St. Louis, Mo., and is widely
used as an antioxidant for animal feed and forage. 1
[0064] Other suitable stabilizing compounds for beta-carotene (or
suitable substitutes such as carotenes, carotenoids, their
derivatives and precursors, and long chain unsaturated compounds)
include butylated hydroxyanisole; butylated hydroxytoluene;
gallates such as octyl gallate, dodecyl gallate, and propyl
gallate; fatty acid esters including, but not limited to, methyl
esters such as methyl linoleate, methyl oleate, methyl stearate,
and other esters such as ascorbic palmitate; disulfiram;
tocopherols, such as gamma-tocopherol, delta-tocopherol and
alpha-tocopherol, and tocopherol derivatives and precursors;
deodorized extract of rosemary; propionate esters and
thiopropionate esters such as lauryl thiodipropionate or dilauryl
thiodipropionate; beta-lactoglobulin; ascorbic acid; amino acids
such as phenylalanine, cysteine, tryptophan, methionine, glutamic
acid, glutamine, arginine, leucine, tyrosine, lysine, serine,
histidine, threonine, asparagine, glycine, aspartic acid,
isoleucine, valine, and alanine; 2,2,6,6-tetramethylpiperidinooxy,
also referred to as tanan;
2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, also referred to as
tanol; dimethyl-p-phenylaminophenoxysilane; di-p-anisylazoxides;
2,2,4-trimethyl-6-ethoxy-1,2,3,4-tetrahydroquinoline- ;
dihydrosantoquin; santoquin; p-hydroxydiphenylamine, and
carbonates, phthalates, and adipates thereof; and diludin, a
1,4-dihydropyridine derivative.
[0065] Particularly preferred stabilizing compounds for
beta-carotene include oil-soluble antioxidants, including, but not
limited to ascorbyl palmitate, butylated hydroxyanisole, butylated
hydroxytoluene, lecithin, propyl gallate, alpha-tocopherol,
phenyl-alpha-naphthylamine, hydroquinone, nordihydroguaiaretic
acid, rosemary extract, mixtures thereof, and the like.
[0066] Also preferred in certain embodiments as stabilizing
compounds for beta-carotene are conventional synthetic and natural
antioxidants. Synthetic and natural antioxidants include, but are
not limited to, Vitamin C and derivatives (ascorbic acid); Vitamin
E and derivatives (tocopherols & tocotrienols); flavonoids and
derivatives (including catechins); phenolic acids and derivatives;
tert-butyl hydroquinone (TBHQ); imidazolidinyl urea, quaternary
ammoniums, diazolidinyl urea; erythorbic acid; sodium erythorbate,
lactic acid, calcium ascorbate, sodium ascorbate, potassium
ascorbate, ascorbyl stearate, erythorbin acid; sodium erythorbin;
butylhydroxinon; sodium or potassium or calcium or magnesium
lactate; citric acid; sodium, monosodium, disodium or trisodium
citrates; potassium, monopotassium or tripotassium citrate;
tartaric acid; sodium, monosodium or disodium tartrates; potassium,
monopotassium tartrate or diipotassium tartrate; sodium potassium
tartrate; phosphoric acid; sodium, monosodium, disodium or
trisodium phosphates; potassium, monopotassium, dipotassium and
tripotassium phosphates; stannous chloride; lecithin;
nordihydroguaiaretic acid (NDGA); alcoholic esters of the gallates;
ascorbyl stearate; 2-tertiarybutyl-4-hydroxyanisole;
3-tertiarybutyl-4-hydroxyanisole; 1-cysteine hydrochloride; gum
guaiacum; lecithin citrate; monoglyceride citrate; monoisopropyl
citrate; Ethylenediaminetetraacetic acid;
2,6-di-tert-butyl-4-hydroxymethylphenol; polyphosphates; trihydroxy
butyrophenone; and anoxomer.
[0067] Water soluble antioxidants such as ascorbic acid, sodium
metabisulfite, sodium bisulfite, sodium thiosulfite, sodium
formaldehyde sulfoxylate, isoascorbic acid, thioglyerol,
thiosorbitol, thiourea, thioglycolic acid, cysteine hydrochloride,
1,4-diazobicyclo-(2,2,2)-octan- e, malic acid, fumaric acid,
licopene and mixtures thereof, may also be suitable for use as
stabilizing compounds for beta-carotene in preferred embodiments.
Such water soluble components are preferably formulated into an
emulsion compatible with diesel fuel, or encapsulated in a
non-polar or oleophilic substance prior to addition to diesel
fuel.
[0068] Other compounds that may be suitable for use as stabilizers
include alkyl phenols, such as mono-butylphenols,
tetrabutylphenols, tributylphenols, 2-tert-butylphenol,
2,6-di-tert-butylphenol, ethyl phenols,
2-tert-butyl-4-n-butylphenol, 2,4,6-tri-tert-butylphenol, and
2,6-di-tert-butyl-4-butylphenol; 2,6-di-t-butylphenol;
2,2'-methylene-bis(6-t-butyl-4-methylphenol); n-octadecyl
3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate;
1,1,3-tris(3-t-butyl-6-met- hyl-4-hydroxyphenyl) butane;
pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-- hydroxyphenyl)
propionate]; di-n-octadecyl(3,5-di-t-butyl-4-hydroxybenzyl)
phosphonate; 2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl) mesitylene;
tris(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate; pentaerythritol
co-esters derived from pentaerythritol,
(3-alkyl-4-hydroxyphenyl)-alkanoi- c acids and alkylthioalkanoic
acids or lower alkyl esters of such acids which are useful as
stabilizers of organic material normally susceptible to oxidative
and/or thermal deterioration; the reaction product of malonic acid,
dodecyl aldehyde and tallowamine; hindered phenyl phosphites;
hindered piperidine carboxylic acids and metal salts thereof,
acylated derivatives of 2,6-dihydroxy-9-azabicyclo[3.3.1]nonane;
bicyclic hindered amines; sulfur containing derivatives of
dialkyl-4-hydroxyphenyl- triazine; bicyclic hindered amino acids
and metal salts thereof; trialkylsubstituted hydroxybenzyl
malonates; hindered piperidine carboxylic acids and metal salts
thereof; pyrrolidine dicarboxylic acids and ester; metal salts of
N,N-disubstituted beta-alanines; hydrocarbyl thioalkylene
phosphites; hydroxybenzyl thioalkylene phosphites; diphenylamines,
dinaphthylamines, and phenylnaphthylamines, either substituted or
unsubstituted, e.g., N,N'-diphenylphenylenediamine,
p-octyldiphenylamine, p,p-dioctyldiphenylamine,
N-phenyl-1-naphthylamine, N-phenyl-2-naphthylarnine,
N-(p-dodecyl)phenyl-2-naphthylamine, di-1-naphthylamine, and
di-2naphthylamine; phenothazines such as N-alkylphenothiazines;
imino(bisbenzyl); emu oil; alpha-lipoic acid; and the like; and
mixtures thereof.
[0069] While not wishing to be bound to any particular mechanism or
theory, it is believed that the stabilizing compound functions as a
preservative or stabilizer by inhibiting oxidation of a carotene or
other long chain olefinic compound due to free radical formation.
When the stabilizing compound is present in combination with
beta-carotene, it is not necessary to prepare or store the fuel
additive or the additized fuel under an inert atmosphere. This is
in contrast to prior art methods wherein preparation and storage
under an inert atmosphere were generally necessary in order to
preserve the activity of the beta-carotene prior to combustion of
the additized fuel. The combination of a stabilizing compound such
as ethoxyquin in combination with cetane improving compounds such
as beta-carotene or long chain olefinic compounds may result in a
synergistic increase in cetane number, as demonstrated in the
examples below.
[0070] Cetane Improvers
[0071] In certain embodiments, the additive or diesel fuel may
contain one or more conventional cetane improvers and/or ignition
accelerators. Preferred organic nitrates are substituted or
unsubstituted alkyl or cycloalkyl nitrates having up to about 10
carbon atoms, preferably from 2 to 10 carbon atoms. The alkyl group
may be either linear or branched. Specific examples of nitrate
compounds suitable for use in preferred embodiments include, but
are not limited to the following: methyl nitrate, ethyl nitrate,
n-propyl nitrate, isopropyl nitrate, allyl nitrate, n-butyl
nitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate,
n-amyl nitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate,
tert-amyl nitrate, n-hexyl nitrate, 2-ethylhexyl nitrate, n-heptyl
nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate,
n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate,
cyclopentylnitrate, cyclobexylnitrate, methylcyclohexyl nitrate,
isopropylcyclohexyl nitrate, and the esters of alkoxy substituted
aliphatic alcohols, such as l-methoxypropyl-2-nitrate,
1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl
nitrate and the like. Preferred alkyl nitrates are ethyl nitrate,
propyl nitrate, amyl nitrates, and hexyl nitrates. Other preferred
alkyl nitrates are mixtures of primary amyl nitrates or primary
hexyl nitrates. By primary is meant that the nitrate functional
group is attached to a carbon atom which is attached to two
hydrogen atoms. Examples of primary hexyl nitrates include n-hexyl
nitrate, 2-ethylhexyl nitrate, 4-methyl-n-pentyl nitrate, and the
like. Preparation of the nitrate esters may be accomplished by any
of the commonly used methods: such as, for example, esterification
of the appropriate alcohol, or reaction of a suitable alkyl halide
with silver nitrate. Another additive suitable for use in improving
cetane and/or reducing particulate emissions is di-t-butyl
peroxide.
[0072] Conventional ignition accelerators may also be used, such as
hydrogen peroxide, benzoyl peroxide, di-tert-butyl peroxide, and
the like. Moreover, certain inorganic and organic chlorides and
bromides, such as, for example, aluminum chloride, ethyl chloride
or bromide may find use in the preferred embodiments as primers
when used in combination with the other ignition accelerators.
[0073] Ratio of Beta-Carotene to Stabilizing Compound
[0074] In preferred embodiments, the components of the base
additive formulation are present in specified ratios and are
present in specific treat rates in the additized fuel. In
determining the ratios and treat rates of the components, factors
taken into consideration may include elevation, base fuel purity,
type of fuel (e.g., gasoline, diesel, residual fuel, two-cycle
fuel, and the like), sulfur content, mercaptan content, olefin
content, aromatic content and the engine or device using the fuel
(e.g., gasoline powered engine, diesel engine, two-cycle engine,
stationary boiler). For example, if a diesel fuel is of a lower
grade, such as one that has a high sulfur content (1 wt. % or
more), a high olefin content (12 ppm or higher), or a high
aromatics content (35 wt. % or higher), the ratios may be adjusted
to compensate by providing additional beta-carotene.
[0075] In additive formulations and additized fuels of preferred
embodiments, the ratio of grams of beta-carotene to grams
ethoxyquin in the additive is generally from about 20:1 or greater
to about 1:20 or lower; typically from about 19:1, 18:1, 17:1;
16:1, or 15:1 to about 1:15, 1:16, 1:17, 1:18; or 1:19; preferably
from about 14:1, 13:1, 12:1, or 11:1 to about 1:11, 1:12; 1:13; or
1:14, more preferably from about 10:1, 9:1, 8:1, 7:1, 6:1, or 5:1
to about 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, and most preferably from
about 4:1, 3:1, 2:1, or 1:1 to about 1:2, 1:3, or 1:4. These ratios
are also generally preferred for the suitable substitutes of
beta-carotene and suitable substitutes for ethoxyquin. However, if
the stabilizer is less potent or effective than ethoxyquin, it may
be preferred to use proportionally more of the stabilizer in the
additive combination. Likewise, if the stabilizer is more potent or
effective than ethoxyquin, it may be preferred to use
proportionally less of the stabilizer in the additive
combination.
[0076] It is preferred that the ratio of beta-carotene and/or
substitutes(s) to ethoxyquin and/or substitute(s) approach the
above ratios. In certain embodiments, it may be preferred to adjust
the treat rate of ethoxyquin up or down, depending upon the
oxidative severity of the fuel and the degree of stabilization to
be provided the beta-carotene. The total treat rate of each
component in the additized fuel may be adjusted up or down,
depending upon various factors as described above.
[0077] Other Additives
[0078] The additive packages and formulated fuels compositions of
preferred embodiments may contain additives other than the ones
described above. These additives may include, but are not limited
to, one or more octane improvers, detergents, antioxidants,
demulsifiers, corrosion inhibitors and/or metal deactivators,
diluents, cold flow improvers, thermal stabilizers, and the like,
as described below.
[0079] Plant Oil Extracts
[0080] In a preferred embodiment, the formulation may include as an
additional component a plant oil extracted from, e.g., vetch, hops,
barley, or alfalfa. The term "plant oil extract" as used herein, is
a broad term and is used in its ordinary sense, including, without
limitation, those components present in the plant material which
are soluble in n-hexane. Chlorophyll may be used as a substitute
for, or in addition to, all or a portion of the oil extract. The
hydrophobic oil extract contains chlorophyll. Chlorophyll is the
green pigment in plants that accomplishes photosynthesis, the
process in which carbon dioxide and water combine to form glucose
and oxygen. The hydrophobic oil extract typically also contains
many other compounds, including, but not limited to,
organometallics, antioxidants, oils, lipids thermal stabilizers or
the starting materials for these types of products, and
approximately 300 other compounds primarily consisting of low to
high molecular weight antioxidants.
[0081] While the oil extract from barley is preferred in many
embodiments, in other embodiments it may be desirable to
substitute, in whole or in part, another plant oil extract,
including, but not limited to, alfalfa, hops oil extract, fescue
oil extract, vetch oil extract, green clover oil extract, wheat oil
extract, extract of the green portions of grains, green food
materials oil extract, green hedges or green leaves or green grass
oil extract, any flowers containing green portions, the leafy or
green portion of a plant of any member of the legume family,
chlorophyll or chlorophyll containing extracts, or combinations or
mixtures thereof. Suitable legumes include legume selected from the
group consisting of lima bean, kidney bean, pinto bean, red bean,
soy bean, great northern bean, lentil, navy bean, black turtle
bean, pea, garbanzo bean, and black eye pea. Suitable grains
include fescue, clover, wheat, oats, barley, rye, sorghum, flax,
tritcale, rice, corn, spelt, millet, amaranth, buckwheat, quinoa,
kamut, and teff.
[0082] Especially preferred plant oil extracts are those derived
from plants that are members of the Fabaceae (Leguminosae) plant
family, commonly referred to as the pulse family, and also as the
pea or legume family. The Leguminosae family includes over 700
genera and 17,000 species, including shrubs, trees, and herbs. The
family is divided into three subfamilies: divided into three
subfamilies: Mimosoideae, which are mainly tropical trees and
shrubs; Caesalpinioideae, which include tropical and sub-tropical
shrubs; and Papilioniodeae which includes peas and beans. A common
feature of most members of the Leguminosae family is the presence
of root nodules containing nitrogen-fixing Rhizobium bacteria. Many
members of the Leguminosae family also accumulate high levels of
vegetable oils in their seeds. The Leguminosae family includes the
lead-plant, hog peanut, wild bean, Canadian milk vetch, indigo,
soybean, pale vetchling, marsh vetchling, veiny pea, round-headed
bush clover, perennial lupine, hop clover, alfalfa, white sweet
clover, yellow sweet clover, white prairie-clover, purple
prairie-clover, common locust, small wild bean, red clover, white
clover, narrow-leaved vetch, hairy vetch, garden pea, chick pea,
string green, kidney bean, mung bean, lima bean, broad bean,
lentil, peanut or groundnut, and the cowpea, to name but a few.
[0083] The most preferred form of oil-extracted material consists
of a material having a paste or mud-like consistency after
extraction, namely, a solid or semi-solid, rather than a liquid,
after extraction. Such pastes typically contain a higher
concentration of Chlorophyll A to Chlorophyll B in the extract. The
color of such a material is generally a deep black-green with some
degree of fluorescence throughout the material. Such a material can
be recovered from many or all the plant sources enumerated for the
Leguminosae family. While such a form is generally preferred for
most embodiments, in certain other embodiments a liquid or some
other form may be preferred.
[0084] The oil extract may be obtained using extraction methods
well known to those of skill in the art. Solvent extraction methods
are generally preferred. Any suitable extraction solvent may be
used which is capable of separating the oil and oil-soluble
fractions from the plant material. Nonpolar extraction solvents are
generally preferred. The solvent may include a single solvent, or a
mixture of two or more solvents. Suitable solvents include, but are
not limited to, cyclic, straight chain, and branched-chain alkanes
containing from about 5 or fewer to 12 or more carbon atoms.
Specific examples of acyclic alkane extractants include pentane,
hexane, heptane, octane, nonane, decane, mixed hexanes, mixed
heptanes, mixed octanes, isooctane, and the like. Examples of the
cycloalkane extractants include cyclopentane, cyclohexane,
cycloheptane, cyclooctane, methylcyclohexane, and the like. Alkenes
such as hexenes, heptenes, octenes, nonenes, and decenes are also
suitable for use, as are aromatic hydrocarbons such as benzene,
toluene, and xylene. Halogenated hydrocarbons such as
chlorobenzene, dichlorobenzene, trichlorobenzene, methylene
chloride, chloroform, carbon tetrachloride, perchloroethylene,
trichloroethylene, trichloroethane, and trichlorotrifluoroethane
may also be used. Generally preferred solvents are C6 to C12
alkanes, particularly n-hexane.
[0085] Hexane extraction is the most commonly used technique for
extracting oil from seeds. It is a highly efficient extraction
method that extracts virtually all oil-soluble fractions in the
plant material. In a typical hexane extraction, the plant material
is comminuted. Grasses and leafy plants may be chopped into small
pieces. Seed are typically ground or flaked. The plant material is
typically exposed to hexane at an elevated temperature. The hexane,
a highly flammable, colorless, volatile solvent that dissolves out
the oil, typically leaves only a few weight percent of the oil in
the residual plant material. The oil/solvent mixture may be heated
to 212.degree. F., the temperature at which hexane flashes off, and
is then distilled to remove all traces of hexane. Alternatively,
hexane may be removed by evaporation at reduced pressure. The
resulting oil extract is suitable for use in the formulations of
preferred embodiments.
[0086] Plant oils extracts for use in edible items or cosmetics
typically undergo additional processing steps to remove impurities
that may affect the appearance, shelf life, taste, and the like, to
yield a refined oil. These impurities may include phospholipids,
mucilaginous gums, free fatty acids, color pigments and fine plant
particles. Different methods are used to remove these by-products
including water precipitation or precipitation with aqueous
solutions of organic acids. Color compounds are typically removed
by bleaching, wherein the oil is typically passed through an
adsorbent such as diatomaceous clay. Deodorization may also be
conducted, which typically involves the use of steam distillation.
Such additional processing steps are generally unnecessary.
However, oils subjected to such treatments may be suitable for use
in the formulations of preferred embodiments.
[0087] Other preferred extraction processes include, but are not
limited to, supercritical fluid extraction, typically with carbon
dioxide. Other gases, such as helium, argon, xenon, and nitrogen
may also be suitable for use as solvents in supercritical fluid
extraction methods.
[0088] Any other suitable method may be used to obtain the desired
oil extract fractions, including, but not limited to, mechanical
pressing. Mechanical pressing, also known as expeller pressing,
removes oil through the use of continuously driven screws that
crush the seed or other oil-bearing material into a pulp from which
the oil is expressed. Friction created in the process can generate
temperatures between about 50.degree. C. and 90.degree. C., or
external heat may be applied. Cold pressing generally refers to
mechanical pressing conducted at a temperature of 40.degree. C. or
less with no external heat applied.
[0089] The yield of oil extract that may be obtained from a plant
material may depend upon any number of factors, but primarily upon
the oil content of the plant material. For example, a typical oil
content of vetch (hexane extraction, dry basis) is approximately 4
to 5 wt. %, while that for barley is approximately 6 to 7.5 wt. %,
and that for alfalfa is approximately 2 to 4.2 wt.%.
[0090] Thermal Stabilizers
[0091] In a preferred embodiment, the formulation may also contain
jojoba oil as an additional component. It is a liquid that has
antioxidant characteristics and is capable of withstanding very
high temperatures without losing its antioxidant abilities. Jojoba
oil is a liquid wax ester mixture extracted from ground or crushed
seeds from shrubs native to Arizona, California and northern
Mexico. The source of jojoba oil is the Simmondsia chinensis shrub,
commonly called the jojoba plant. It is a woody evergreen shrub
with thick, leathery, bluish-green leaves and dark brown, nutlike
fruit. Jojoba oil may be extracted from the fruit by conventional
pressing or solvent extraction methods. The oil is clear and golden
in color. Jojoba oil is composed almost completely of wax esters of
monounsaturated, straight-chain acids and alcohols with high
molecular weights (C16-C26). Jojoba oil is typically defined as a
liquid wax ester with the generic formula RCOOR", wherein RCO
represents oleic acid (C18), eicosanoic acid (C20) and/or erucic
acid (C22), and wherein --OR" represents eicosenyl alcohol (C20),
docosenyl alcohol (C22) and/or tetrasenyl alcohol (C24) moieties.
Pure esters or mixed esters having the formula RCOOR", wherein R is
a C20-C22 alk(en)yl group and wherein R" is a C20-C22 alk(en)yl
group, may be suitable substitutes, in part or in whole, for jojoba
oil. Acids and alcohols including monounsaturated straight-chain
alkenyl groups are most preferred.
[0092] While the jojoba oil is preferred in many embodiments, in
other embodiments it may be desirable to substitute, in whole or in
part, another component, including, but not limited to, oils that
are known for their thermal stability, such as, peanut oil,
cottonseed oil, rape seed oil, macadamia oil, avocado oil, palm
oil, palm kernel oil, castor oil, all other vegetable and nut oils,
all animal oils including mammal oils (e.g., whale oils) and fish
oils, and combinations and mixtures thereof. In preferred
embodiments, the oil may be alkoxylated, for example, methoxylated
or ethoxylated. Alkoxylation is preferably conducted on medium
chain oils, such as castor oil, macadamia nut oil, cottonseed oil,
and the like. Alkoxylation may offer benefits in that it may permit
coupling of oil/water mixtures in a fuel, resulting in a potential
reduction in nitrogen oxides and/or particulate matter emissions
upon combustion of the fuel.
[0093] In preferred embodiments, these other oils are substituted
for jojoba oil on a 1:1 volume ratio basis, in either a partial
substitution or complete substitution. In other embodiments it may
be preferred to substitute the other oil for jojoba oil at a volume
ration greater than or less than a 1:1 volume ratio. In a preferred
embodiment, cottonseed oil, either purified or merely extracted or
crushed from cottonseed, squalene, or squalane are substituted on a
1:1 volume ratio basis for a portion or an entire volume of jojoba
oil.
[0094] Although jojoba oil is preferred for used in many of the
formulations of the preferred embodiments, in certain formulations
it may be preferred to substitute one or more different thermal
stabilizers for jojoba oil, either in whole or in part. Suitable
thermal stabilizers as known in the art include liquid mixtures of
alkyl phenols, including 2-tert-butylphenol,
2,6-di-tert-butylphenol, 2-tert-butyl-4-n-butylphenol- ,
2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-n-butylphenol
which are suited for use as stabilizers for middle distillate fuels
(U.S. Pat. No. 5,076,814 and U.S. Pat. No. 5,024,775 to Hanlon, et
al.). Other commercially available hindered phenolic antioxidants
that also exhibit a thermal stability effect include
2,6-di-t-butyl-4-methylphenol; 2,6-di-t-butylphenol;
2,2'-methylene-bis(6-t-butyl-4-methylphenol); n-octadecyl
3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate;
1,1,3-tris(3-t-butyl-6-methyl-4hydroxyphenyl) butane;
pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate];
di-n-octadecyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate;
2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl) mesitylene; and
tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate (U.S. Pat. Nos.
4,007,157, U.S. Pat. No. 3,920,661).
[0095] Other thermal stabilizers include: pentaerythritol co-esters
derived from pentaerythritol, (3-alkyl-4-hydroxyphenyl)-alkanoic
acids and alkylthioalkanoic acids or lower alkyl esters of such
acids which are useful as stabilizers of organic material normally
susceptible to oxidative and/or thermal deterioration. (U.S. Pat.
No. 4,806,675 and U.S. Pat. No. 4,734,519 to Dunski, et al.); the
reaction product of malonic acid, dodecyl aldehyde and tallowamine
(U.S. Pat. No. 4,670,021 to Nelson, et al.); hindered phenyl
phosphites (U.S. Pat. No. 4,207,229 to Spivack); hindered
piperidine carboxylic acids and metal salts thereof (U.S. Pat. No.
4,191,829 and U.S. Pat. No. 4,191,682 to Ramey, et al.); acylated
derivatives of 2,6-dihydroxy-9-azabicyclo[3.3.1]nonane (U.S. Pat.
No. 4,000,113 to Stephen); bicyclic hindered amines (U.S. Pat. No.
3,991,012 to Ramey, et al.); sulfur containing derivatives of
dialkyl-4-hydroxyphenyltriazine (U.S. Pat. No. 3,941,745 to Dexter,
et a.); bicyclic hindered amino acids and metal salts thereof (U.S.
Pat. No. 4,051,102 to Ramey, et al.); trialkylsubstituted
hydroxybenzyl malonates (U.S. Pat. No. 4,081,475 to Spivack);
hindered piperidine carboxylic acids and metal salts thereof (U.S.
Pat. No. 4,089,842 to Ramey, et al.); pyrrolidine dicarboxylic
acids and esters (U.S. Pat. No. 4,093,586 to Stephen); metal salts
of N,N-disubstituted p-alanines (U.S. Pat. No. 4,077,941 to
Stephen, et al.); hydrocarbyl thioalkylene phosphites (U.S. Pat.
No. 3,524,909); hydroxybenzyl thioalkylene phosphites (U.S. Pat.
No. 3,655,833); and the like.
[0096] Certain compounds are capable of performing as both
antioxidants and as thermal stabilizers. Therefore, in certain
embodiments it may be preferred to prepare formulations containing
as additional components a hydrophobic plant oil extract in
combination with a single compound that provides both a thermal
stability and antioxidant effect, rather than two different
compounds, one providing thermal stability and the other
antioxidant activity. Examples of compounds known in the art as
providing some degree of both oxidation resistance and thermal
stability include diphenylamines, dinaphthylamines, and
phenylnaphthylamines, either substituted or unsubstituted, e.g.,
N,N'-diphenylphenylenediamine, p-octyldiphenylamine,
p,p-dioctyldiphenylamine, N-phenyl-1-naphthylamine,
N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine,
di-1-naphthylamine, and di-2naphthylamine; phenothazines such as
N-alkylphenothiazines; imino(bisbenzyl); and hindered phenols such
as 6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol,
4-methyl-2,6-di-(t-butyl) phenol,
4,4'-methylenebis(-2,6-di-(t-butyl)phenol), and the like.
[0097] Certain lubricating fluid base stocks are known in the art
to exhibit high thermal stability. Such base stocks may be capable
of imparting thermal stability to the formulations of preferred
embodiments, and as such may be substituted, in part or in whole,
for jojoba oil. Suitable base stocks include polyalphaolefins,
dibasic acid esters, polyol esters, alkylated aromatics,
polyalkylene glycols, and phosphate esters.
[0098] Polyalphaolefins are hydrocarbon polymers that contain no
sulfur, phosphorus, or metals. Polyalphaolefins have good thermal
stability, but are typically used in conjunction with a suitable
antioxidant. Dibasic acid esters also exhibit good thermal
stability, but are usually also used in combination with additives
for resistance to hydrolysis and oxidation.
[0099] Polyol esters include molecules containing two or more
alcohol moieties, such as trimethylolpropane, neopentylglycol, and
pentaerythritol esters. Synthetic polyol esters are the reaction
product of a fatty acid derived from either animal or plant sources
and a synthetic polyol. Polyol esters have excellent thermal
stability and may resist hydrolysis and oxidation better than other
base stocks. Naturally occurring triglycerides or vegetable oils
are in the same chemical family as polyol esters. However, polyol
esters tend to be more resistant to oxidation than such oils. The
oxidation instabilities normally associated with vegetable oils are
generally due to a high content of linoleic and linolenic fatty
acids. Moreover, the degree of unsaturation (or double bonds) in
the fatty acids in vegetable oils correlates with sensitivity to
oxidation, with a greater number of double bonds resulting in a
material more sensitive to and prone to rapid oxidation.
[0100] Trimethylolpropane esters may include mono, di, and tri
esters. Neopentyl glycol esters may include mono and di esters.
Pentaerythritol esters include mono, di, tri, and tetra esters.
Dipentaerythritol esters may include up to six ester moieties.
Preferred esters are typically of those of long chain monobasic
fatty acids. Esters of C20 or higher acids are preferred, e.g.,
gondoic acid, eicosadienoic acid, eicosatrienoic acid,
eicosatetraenoic acid, eicosapentanoic acid, arachidic acid,
arachidonic acid, behenic acid, erucic acid, docosapentanoic acid,
docosahexanoic acid, or ligniceric acid. However in certain
embodiments, esters of C18 or lower acids may be preferred, e.g.,
butyric acid, caproic acid, caprylic acid, capric acid, lauric
acid, myristoleic acid, myristic acid, pentadecanoic acid, palmitic
acid, palmitoleic acid, hexadecadienoic acid, hexadecatienoic acid,
hexadecatetraenoic acid, margaric acid, margroleic acid, stearic
acid, linoleic acid, octadecatetraenoic acid, vaccenic acid, or
linolenic acid. In certain embodiments, it may be preferred to
esterify the pentaerythritol with a mixture of different acids.
[0101] Alkylated aromatics are formed by the reaction of olefins or
alkyl halides with aromatic compounds, such as benzene. Thermal
stability is similar to that of polyalphaolefins, and additives are
typically used to provide oxidative stability. Polyalkylene glycols
are polymers of alkylene oxides exhibiting good thermal stability,
but are typically used in combination with additives to provide
oxidation resistance. Phosphate esters are synthesized from
phosphorus oxychloride and alcohols or phenols and also exhibit
good thermal stability.
[0102] In certain embodiments, it may be preferred to prepare
formulations containing jojoba oil in combination with other
vegetable oils. For example, it has been reported that crude
meadowfoam oil resists oxidative destruction nearly 18 times longer
than the most common vegetable oil, namely, soybean oil. Meadowfoam
oil may be added in small amounts to other oils, such as triolein
oil, jojoba oil, and castor oil, to improve their oxidative
stability. Crude meadowfoam oil stability could not be attributed
to common antioxidants. One possible explanation for the oxidative
stability of meadowfoam oil may be its unusual fatty acid
composition. The main fatty acid from meadowfoam oil is
5-eicosenoic acid, which was found to be nearly 5 times more stable
to oxidation than the most common fatty acid, oleic acid, and 16
times more stable than other monounsaturated fatty acids. See
"Oxidative Stability Index of Vegetable Oils in Binary Mixtures
with Meadowfoam Oil," Terry, et al., United States Department of
Agriculture, Agricultural Research Service, 1997.
[0103] Detergent Additives--Carburetor deposits may form in the
throttle body and plate, idle air circuit, and in the metering
orifices and jets. These deposits are a combination of contaminants
from dust and engine exhaust, held together by gums formed from
unsaturated hydrocarbons in the fuel. They can alter the air/fuel
ratio, cause rough idling, increased fuel consumption, and
increased exhaust emissions. Carburetor detergents can prevent
deposits from forming and remove deposits already formed.
Detergents used for this application are amines in the 20-60 ppm
dosage range.
[0104] Fuel injectors are very sensitive to deposits that can
reduce fuel flow and alter the injector spray pattern. These
deposits can make vehicles difficult to start, cause severe
driveability problems, and increase fuel consumption and exhaust
emissions. Fuel injector deposits are formed at higher temperatures
than carburetor deposits and are therefore more difficult to deal
with. The amines used for carburetor deposits are somewhat
effective but are typically used at roughly the 100 ppm dosage
level. At this level, the amine detergent can actually cause the
formation of inlet manifold and valve deposits. Polymeric
dispersants with higher thermal stability than the amine detergents
have been used to overcome this problem. These are used at dosages
in the range of 20 to 600 ppm. These same additives are also
effective for inlet manifold and valve deposit control. Inlet
manifold and valve deposits have the same effect on driveability,
fuel consumption, and exhaust emissions as carburetor and engine
deposits. The effect of detergent and dispersant additives on
engines with existing deposits may require several tanks of
gasoline, especially if the additives are used at a low dosage
rate.
[0105] Combustion chamber deposits can cause an increase in the
octane number requirement for vehicles as they accumulate miles.
These deposits accumulate in the end-gas zone and injection port
area. They are thermal insulators and so can become very hot during
engine operation. The metallic surfaces conduct heat away and
remain relatively cool. The hot deposits can cause pre-ignition and
misfire leading to the need for a higher-octane fuel.
Polyetheramine and other proprietary additives are known to reduce
the magnitude of combustion chamber deposits. Reduction in the
amount of combustion chamber deposits has been shown to reduce
NO.sub.x emissions.
[0106] Any of a number of different types of suitable detergent
additives can be included in diesel fuel compositions of various
embodiments. These detergents include succinimide
detergent/dispersants, long-chain aliphatic polyamines, long-chain
Mannich bases, and carbamate detergents. Desirable succinimide
detergent/dispersants for use in gasolines are prepared by a
process that includes reacting an ethylene polyamine such as
dietlylene triamine or triethylene tetramine with at least one
acyclic hydrocarbyl substituted succinic acylating agent. The
substituent of such acylating agent is characterized by containing
an average of about 50 to about 100 (preferably about 50 to about
90 and more preferably about 64 to about 80) carbon atoms.
Additionally, the acylating agent has an acid number in the range
of about 0.7 to about 1.3 (for example, in the range of 0.9 to 1.3,
or in the range of 0.7 to 1.1), more preferably in the range of 0.8
to 1.0 or in the range of 1.0 to 1.2, and most preferably about
0.9. The detergent/dispersant contains in its molecular structure
in chemically combined form an average of from about 1.5 to about
2.2 (preferably from 1.7 to i.9 or from 1.9 to 2.1, more preferably
from 1.8 to 2.0, and most preferably about 1.8) moles of the
acylating agent per mole of the polyamine. The polyamine can be a
pure compound or a technical grade of ethylene polyamines that
typically are composed of linear, branched and cyclic species.
[0107] The acyclic hydrocarbyl substituent of the
detergent/dispersant is preferably an alkyl or alkenyl group having
the requisite number of carbon atoms as specified above. Alkenyl
substituents derived from poly-olefin homopolymers or copolymers of
appropriate molecular weight (for example, propene homopolymers,
butene homopolymers, C.sub.3 and C.sub.4 olefin copolymers, and the
like) are suitable. Most preferably, the substituent is a
polyisobutenyl group formed from polyisobutene having a number
average molecular weight (as determined by gel permeation
chromatography) in the range of 700 to 1200, preferably 900 to
1100, most preferably 940 to 1000. The established manufacturers of
such polymeric materials are able to adequately identify the number
average molecular weights of their own polymeric materials. Thus in
the usual case the nominal number average molecular weight given by
the manufacturer of the material can be relied upon with
considerable confidence.
[0108] Acyclic hydrocarbyl-substituted succinic acid acylating
agents and methods for their preparation and use in the formation
of succinimide are well known to those skilled in the art and are
extensively reported in the literature. See, for example, U.S. Pat.
No. 3,018,247.
[0109] Use of fuel-soluble long chain aliphatic polyamines as
induction cleanliness additives in distillate fuels is described,
for example, in U.S. Pat. No.3,438,757.
[0110] Use of fuel-soluble Mannich base additives formed from a
long chain alkyl phenol, formaldehyde (or a formaldehyde precursor
thereof), and a polyamine to control induction system deposit
formation in internal combustion engines is described, for example,
in U.S. Pat. No. 4,231,759.
[0111] Carbamate fuel detergents are compositions which contain
polyether and amine groups joined by a carbamate linkage. Typical
compounds of this type are described in U.S. Pat. No. 4,270,930. A
preferred material of this type is commercially available from
Chevron Oronite Company LLC of Houston, Tex. as OGA-480.TM.
additive.
[0112] Driveability Additives--For gasoline powered engines, these
include anti-knock, anti-run-on, anti-pre-ignition, and
anti-misfire additives that directly effect the combustion process.
Anti-knock additives include lead alkyls that are no longer used in
the United States. These and other metallic anti-knock additives
are typically used at dosages of roughly 0.2 g metal/liter of fuel
(or about 0.1 wt % or 1000 ppm). A typical octane number
enhancement at this dosage level is 3 units for both Research
Octane Number (RON) and Motor Octane Number (MON). A number of
organic compounds are also known to have anti-knock activity. These
include aromatic amines, alcohols, and ethers that can be employed
at dosages in the 1000 ppm range. These additives work by
transferring hydrogen to quench reactive radicals. Oxygenates such
as methanol and MTBE also increase octane number but these are used
at such high dosages that they are not really additives but blend
components. Pre-ignition is generally caused by the presence of
combustion chamber deposits and is treated using combustion chamber
detergents and by raising octane number. Driveability additives may
also be employed for diesel engines.
[0113] Antiwear Agents--The diesel fuel compositions of various
embodiments advantageously contain one or more antiwear agents.
Preferred antiwear agents include long chain primary amines
incorporating an alkyl or alkenyl radical having 8 to 50 carbon
atoms. The amine to be employed may be a single amine or may
consist of mixtures of such amines. Examples of long chain primary
amines which can be used in the preferred embodiments are
2-ethylhexyl amine, n-octyl amine, n-decyl amine, dodecyl amnine,
oleyl amine, linolylamine, stearyl amine, eicosyl amine, triacontyl
amine, pentacontyl amine and the like. A particularly effective
amine is oleyl amine obtainable from Akzo Nobel Surface Chemistry
LLC of Chicago, Ill. under the name ARMEEN.RTM. O or ARMEEN.RTM.
OD. Other suitable amines which are generally mixtures of aliphatic
amines include ARMEEN.RTM. T and ARMEEN.RTM. TD, the distilled form
of ARMEEN.RTM. T which contains a mixture of 0-2% of tetradecyl
amine, 24% to 30% of hexadecyl amine, 25% to 28% of octadecyl amine
and 45% to 46% of octadecenyl amine. ARMEEN.RTM. T and ARMEEN.RTM.
TD are derived from tallow fatty acids. Lauryl amine is also
suitable, as is ARMEEN.RTM. 12D obtainable from the supplier
indicated above. This product is about 0-2% of decylamine, 90% to
95% dodecylamine, 0-3% of tetradecylamine and 0-1% of
octadecenylamine. Amines of the types indicated to be useful are
well known in the art and may be prepared from fatty acids by
converting the acid or mixture of acids to its ammonium soap,
converting the soap to the corresponding amide by means of heat,
further converting the amide to the corresponding nitrile and
hydrogenating the nitrile to produce the amine. In addition to the
various amines described, the mixture of amines derived from soya
fatty acids also falls within the class of amines above described
and is suitable for use according to this invention. It is noted
that all of the amines described above as being useful are straight
chain, aliphatic primary amines. Those amines having 16 to 18
carbon atoms per molecule and being saturated or unsaturated are
particularly preferred.
[0114] Other preferred antiwear agents include dimerized
unsaturated fatty acids, preferably dimers of a comparatively long
chain fatty acid, for example one containing from 8 to 30 carbon
atoms, and may be pure, or substantially pure, dimers.
Alternatively, and preferably, the material sold commercially and
known as "dimer acid" may be used. This latter material is prepared
by dimerizing unsaturated fatty acid and consists of a mixture of
monomer, dimer and trimer of the acid. A particularly preferred
dimer acid is the dimer of linoleic acid.
[0115] Antioxidants--Various compounds known for use as oxidation
inhibitors can be utilized in fuel formulations of various
embodiments. These include phenolic antioxidants, amine
antioxidants, sulfurized phenolic compounds, and organic
phosphites, among others. For best results, the antioxidant
includes predominately or entirely either (1) a hindered phenol
antioxidant such as 2,6-di-tert-butylphenol,
4-methyl-2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol,
4,4'-methylenebis(2,6-di-tert-butylphenol), and mixed methylene
bridged polyalkyl phenols, or (2) an aromatic amine antioxidant
such as the cycloalkyl-di-lower alkyl amines, and
phenylenediamines, or a combination of one or more such phenolic
antioxidants with one or more such amine antioxidants. Particularly
preferred are combinations of tertiary butyl phenols, such as
2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol and
o-tert-butylphenol. Also useful are N,N'-di-lower-alkyl
phenylenediamines, such as N,N'-di-sec-butyl-p-phenylenediamine,
and its analogs, as well as combinations of such phenylenediamines
and such tertiary butyl phenols.
[0116] Demulsifiers--Demulsifiers are molecules that aid the
separation of oil from water usually at very low concentrations.
They prevent formation of a water and oil mixture. A wide variety
of demulsifiers are available for use in the fuel formulations of
various embodiments, including, for example, organic sulfonates,
polyoxyalkylene glycols, oxyalkylated phenolic resins, and like
materials. Particularly preferred are mixtures of alkylaryl
sulfonates, polyoxyalkylene glycols and oxyalkylated alkylphenolic
resins, such as are available commercially from Baker Petrolite
Corporation of Sugar Land, Tex. under the TOLAD.RTM. trademark.
Other known demulsifiers can also be used.
[0117] Corrosion Inhibitors--A variety of corrosion inhibitors are
available for use in the fuel formulations of various embodiments.
Use can be made of dimer and trimer acids, such as are produced
from tall oil fatty acids, oleic acid, linoleic acid, or the like.
Products of this type are currently available from various
commercial sources, such as, for example, the dimer and trimer
acids sold under the EMPOL.RTM. trademark by Cognis Corporation of
Cincinnati, Ohio. Other useful types of corrosion inhibitors are
the alkenyl succinic acid and alkenyl succinic anhydride corrosion
inhibitors such as, for example, tetrapropenylsuccinic acid,
tetrapropenylsuccinic anhydride, tetradecenylsuccinic acid,
tetradecenylsuccinic anhydride, hexadecenylsuccinic acid,
hexadecenylsuccinic anhydride, and the like. Also useful are the
half esters of alkenyl succinic acids having 8 to 24 carbon atoms
in the alkenyl group with alcohols such as the polyglycols.
[0118] Also useful are the aminosuccinic acids or derivatives.
Preferably a dialkyl ester of an aminosuccinic acid is used
containing an alkyl group containing 15-20 carbon atoms or an acyl
group which is derived from a saturated or unsaturated carboxylic
acid containing 2-10 carbon atoms. Most preferred is a dialkylester
of an aminosuccinic acid.
[0119] Metal Deactivators--If desired, the fuel compositions may
contain a conventional type of metal deactivator of the type having
the ability to form complexes with heavy metals such as copper and
the like. Typically, the metal deactivators used are gasoline
soluble N,N'-disalicylidene-1,2-- alkanediamines or
N,N'-disalicylidene-1,2-cycloalkanediamines, or mixtures thereof.
Examples include N,N'-disalicylidene-1,2-ethanediamine,
N,N'-disalicylidene-1,2-propanediamine,
N,N'-disalicylidene-1,2-cyclo-hex- anediamine, and
N,N"-disalicylidene-N'-methyl-dipropylene-triamine.
[0120] The various additives that can be included in the diesel
compositions of this invention are used in conventional amounts.
The amounts used in any particular case are sufficient to provide
the desired functional property to the fuel composition, and such
amounts are well known to those skilled in the art.
[0121] Thermal Stabilizers--Thermal stabilizers such as Octel
Starreon high temperature fuel oil stabilizer FOA-81.TM., or other
such additives may also be added to the fuel formulation.
[0122] Carrier fluids--Substances suitable for use as carrier
fluids include, but are not limited to, mineral oils, vegetable
oils, animal oils, and synthetic oils. Suitable mineral oils may be
primarily paraffinic, naphthenic, or aromatic in composition.
Animal oils include tallow and lard. Vegetable oils may include,
but are not limited to, rapeseed oil, soybean oil, peanut oil, corn
oil, sunflower oil, cottonseed oil, coconut oil, olive oil, wheat
germ oil, flaxseed oil, almond oil, safflower oil, castor oil, and
the like. Synthetic oils may include, but are not limited to, alkyl
benzenes, polybutylenes, polyisobutylenes, polyalphaolefins, polyol
esters, monoesters, diesters (adipates, sebacates, dodecanedioates,
phthalates, dimerates), and triesters.
[0123] Solvents--Solvents suitable for use in conjunction with the
formulations of preferred embodiments are miscible and compatible
with one or more components of the formulation. Preferred solvents
include the aromatic solvents, such as benzene, toluene, o-xylene,
m-xylene, p-xylene, and the like, as well as nonpolar solvents such
as cyclohexanes, hexanes, heptanes, octanes, nonanes, and the like.
Suitable solvents may also include the fuel to be additized, e.g.,
gasoline, Diesel 1, Diesel 2, and the like. Depending upon the
material to be solvated, other liquids may also be suitable for use
as solvents, such as oxygenates, carrier fluids, or even additives
as enumerated herein.
[0124] Oxygenates--Oxygenates are added to gasoline to improve
octane number and to reduce emissions of CO. These include various
alcohols and ethers that are typically blended with gasoline to
produce an oxygen content typically of up to about 2 weight
percent, although higher concentrations may be desirable in certain
embodiments. The CO emissions benefit appears to be a function of
fuel oxygen level and not of oxygenate chemical structure. Because
oxygenates have a lower heating value than gasoline, volumetric
fuel economy (miles per gallon) is lower for fuels containing these
components. However, at typical blend levels the effect is so small
that only very precise measurements can detect it. Oxygenates are
not known to effect emissions of NO.sub.x or hydrocarbon.
[0125] In certain embodiments, it may be preferred to add one or
more oxygenates to the fuel. Oxygenates are hydrocarbons that
contain one or more oxygen atoms. The primary oxygenates are
alcohols and ethers, including: methanol, fuel ethanol, methyl
tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE),
diisopropyl ether (DIPE), and tertiary amyl methyl ether
(TAME).
[0126] Microencapsulated Beta-Carotene
[0127] In certain of the preferred embodiments, it may be desirable
to encapsulate the beta-carotene or other carotenoid(s) and/or
carotene(s) prior to incorporation into the fuel additive, diesel
fuel formulation, or other fuel formulation. Microencapsulation is
an effective technique to avoid undesired chemical interaction
between additives and ambient oxygen and other substances.
Encapsulated or otherwise preserved beta-carotene may resist
oxidation and other degradative effects that may inhibit its
effectiveness as a cetane improver or other type of fuel additive
(e.g., an emission reducing additive, a fuel economy additive, and
the like). Accordingly, an antioxidant or other additive, such as
ethoxyquin, may not be necessary to stabilize the beta-carotene
such that it remains effective as a cetane improver under ambient
conditions.
[0128] In a preferred embodiment, the beta-carotene and optionally
other additive components are entrapped into lecithin microcapsules
or nanoparticles. Other preferred shell materials include
fuel-soluble polymers or fuel-miscible polymers. The microcapsules'
shells block undesired reactions by substantially preventing direct
contact of the additive contained within and the fuel or
atmosphere. The microencapsulated additives may also provide
long-term controlled release of additives to the fuel at a
preselected concentration.
[0129] Microencapsulation techniques generally involve the coating
of small solid particles, liquid droplets, or gas bubbles with a
thin film of a material, the material providing a protective shell
for the contents of the microcapsule. Microcapsules suitable for
use in the preferred embodiments may be of any suitable size,
typically from about 1 .mu.m or less to about 1000 .mu.M or more,
preferably from about 2 .mu.m to about 50, 60, 70, 80, 90, 100,
200, 300, 400, 500, 600, 700, 800, or 900 .mu.m, and more
preferably from about 3, 4, 5, 6, 7, 8, or 9 .mu.m to about 10, 15,
20, 25, 30, 35, 40 or 45 .mu.m. In certain embodiments, it may be
preferred to use nanometer-sized microcapsules. Such microcapsules
may range from about 10 nm or less up to less than about 1000 nm (1
P.mu.m), preferably from about 10, 15, 20, 25, 30, 35, 40, 45, 50,
60, 70, 80, or 90 nm up to about 100, 200, 300, 400, 500, 600, 700,
800, or 900 nm.
[0130] While in most embodiments liquid phase beta-carotene or
another liquid additive substance is encapsulated, in certain
embodiments it may be preferred to incorporate a solid substance.
Solid containing microcapsules may be prepared using conventional
methods well known in the art of microcapsule formation, and such
microcapsules may be incorporated into the additive packages and
fuels of preferred embodiments.
[0131] Microcapsule Components
[0132] The microcapsules of preferred embodiments contain a filling
material. The filling material is typically one or more carotenes,
carotenoids, their derivatives and precursors, or long chain
unsaturated compounds, optionally in combination with other
substances, such as a beta-carotene stabilizer, e.g., ethoxyquin.
The filling material is encapsulated within the microcapsule by a
shell material.
[0133] Typical shell materials may include, but are not limited to,
gum arabic, gelatin, ethylcellulose, polyurea, polyamide,
aminoplasts, maltodextrins, and hydrogenated vegetable oil. While
any suitable shell material may be used in the preferred
embodiments, it is generally preferred to use shell materials
approved for use in food or pharmaceutical applications. Gelatin is
particularly preferred because of its low cost, biocompatibility,
and the ease with which gelatin shell microcapsules may be
prepared. In certain embodiments, however, other shell materials
may be preferred. The optimum shell material may depend, for
example, upon the particle or droplet size and size distribution of
the filling material, the shape of the filling material particles,
compatibility with the filling material, stability of the filling
material, and the rate of release of the filling material from the
microcapsule. If a hydrophilic substance is utilized as a shell
material, it may be desirable to utilize a dispersing or
emulsifying agent to ensure uniform distribution of the
microcapsules in the fuel additive package or additized fuel.
[0134] Microencapsulation Processes
[0135] A variety of encapsulation methods may be used to prepare
the microcapsules of preferred embodiments. These methods include
gas phase and vacuum processes wherein a coating is sprayed or
otherwise deposited on the filler material particles so as to form
a shell, or processes wherein a liquid is sprayed into a gas phase
and is subsequently solidified to produce microcapsules. Suitable
methods also include emulsion and dispersion methods wherein the
microcapsules are formed in the liquid phase in a reactor.
[0136] Spray Drying
[0137] Encapsulation by spray drying involves spraying a
concentrated solution of shell material containing filler material
particles or a dispersion of immiscible liquid filler material into
a heated chamber where rapid desolvation occurs. Any suitable
solvent system may be used. Spray drying is commonly used to
prepare microcapsules including shell materials such as, for
example, gelatin, hydrolyzed gelatin, gum arabic, modified starch,
maltodextrins, sucrose, or sorbitol. When an aqueous solution of
shell material is used, the filler material typically includes a
hydrophobic liquid or water-immiscible oil. Dispersants and/or
emulsifiers may be added to the concentrated solution of shell
material. Relatively small microcapsules may be prepared by spray
drying methods, e.g., from less than about 1 .mu.m to greater than
about 50 .mu.m. The resulting particles may include individual
particles as well as aggregates of individual particles. The amount
of filler material that may be encapsulated using spray drying
techniques is typically from less than about 20 wt. % of the
microcapsule to more than 60 wt. % of the microcapsule. The process
is preferred because of its low cost compared to other methods, and
has wide utility in preparing microcapsules. The method may not be
preferred for preparing heat sensitive materials.
[0138] In another variety of spray drying, chilled air rather than
desolvation is used to solidify a molten mixture of shell material
containing filler material in the form of particles or an
immiscible liquid. Various fats, waxes, fatty alcohols, and fatty
acids are typically used as shell materials in such an
encapsulation method. The method is generally preferred for
preparing microcapsules having water-insoluble shells.
[0139] Fluidized-Bed Microencapsulation
[0140] Encapsulation using fluidized bed technology involves
spraying a liquid shell material, generally in solution or melted
form, onto solid particles suspended in a stream of gas, typically
heated air, and the particles thus encapsulated are subsequently
cooled. Shell materials commonly used include, but are not limited
to, colloids, solvent-soluble polymers, and sugars. The shell
material may be applied to the particles from the top of the
reactor, or may be applied as a spray from the bottom of the
reactor, e.g., as in the Wurster process. The particles are
maintained in the reactor until a desired shell thickness is
achieved. Fluidized bed microencapsulation is commonly used for
preparing encapsulated water-soluble ingredients. The method is
particularly suitable for coating irregularly shaped particles.
Fluidized bed encapsulation is typically used to prepare
microcapsules larger than about 100 .mu.m, however smaller
microcapsules may also be prepared.
[0141] Complex Coacervation
[0142] A pair of oppositely charged polyelectrolytes capable of
forming a liquid complex coacervate (namely, a mass of colloidal
particles that are bound together by electrostatic attraction) can
be used to form microcapsules by complex coacervation. A preferred
polyanion is gelatin, which is capable of forming complexes with a
variety of polyanions. Typical polyanions include gum arabic,
polyphosphate, polyacrylic acid, and alginate. Complex coacervation
is used primarily to encapsulate water-immiscible liquids or
water-insoluble solids. The method is not suitable for use with
water soluble substances, or substances sensitive to acidic
conditions.
[0143] In the complex coacervation of gelatin with gum arabic, a
water insoluble filler material is dispersed in a warm aqueous
gelatin emulsion, and then gum arabic and water are added to this
emulsion. The pH of the aqueous phase is adjusted to slightly
acidic, thereby forming the complex coacervate which adsorbs on the
surface of the filler material. The system is cooled, and a
cross-linking agent, such as glutaraldehyde, is added. The
microcapsules may optionally be treated with urea and formaldehyde
at low pH so as to reduce the hydrophilicity of the shell, thereby
facilitating drying without excessive aggregate formation. The
resulting microcapsules may then be dried to form a powder.
[0144] Polymer-Polymer Incompatibility
[0145] Microcapsules may be prepared using a solution containing
two liquid polymers that are incompatible, but soluble in a common
solvent. One of the polymers is preferentially absorbed by the
filler material. When the filler material is dispersed in the
solution, it is spontaneously coated by a thin film of the polymer
that is preferentially absorbed. The microcapsules are obtained by
either crosslinking the absorbed polymer or by adding a nonsolvent
for the polymer to the solution. The liquids are then removed to
obtain the microcapsules in the form of a dry powder.
[0146] Polymer-polymer incompatibility encapsulation can be carried
out in aqueous or nonaqueous media. It is typically used for
preparing microcapsules containing polar solids with limited water
solubility. Suitable shell materials include ethylcellulose,
polylactide, and lactide-glycolide copolymers. Microcapsules
prepared by polymer-polymer incompatibility encapsulation tend to
be smaller than microcapsules prepared by other methods, and
typically have diameters of 100 .mu.m or less.
[0147] Interfacial Polymerization
[0148] Microcapsules may be prepared by conducting polymerization
reactions at interfaces in a liquid. In one such type of
microencapsulation method, a dispersion of two immiscible liquids
is prepared. The dispersed phase forms the filler material. Each
phase contains a separate reactant, the reactants capable of
undergoing a polymerization reaction to form a shell. The reactant
in the dispersed phase and the reactant in a continuous phase react
at the interface between the dispersed phase and the continuous
phase to form a shell. The reactant in the continuous phase is
typically conducted to the interface by a diffusion process. Once
reaction is initiated, the shell eventually becomes a barrier to
diffusion and thereby limits the rate of the interfacial
polymerization reaction. This may affect the morphology and
uniformity of thickness of the shell. Dispersants may be added to
the continuous phase. The dispersed phase can include an aqueous or
a nonaqueous solvent The continuous phase is selected to be
immiscible in the dispersed phase.
[0149] Typical polymerization reactants may include acid chlorides
or isocyanates, which are capable of undergoing a polymerization
reaction with amines or alcohols. The amine or alcohol is
solubilized in the aqueous phase in a nonaqueous phase capable
solubilizing the amine or alcohol. The acid chloride or isocyanate
is then dissolved in the water- (or nonaqueous solvent-) immiscible
phase. Similarly, solid particles containing reactants or having
reactants coated on the surface may be dispersed in a liquid in
which the solid particles are not substantially soluble. The
reactants in or on the solid particles then react with reactants in
the continuous phase to form a shell.
[0150] In another type of microencapsulation by interfacial
polymerization, commonly referred to as in situ encapsulation, a
filler material in the form of substantially insoluble particles or
in the form of a water immiscible liquid is dispersed in an aqueous
phase. The aqueous phase contains urea, melamine, water-soluble
urea-formaldehyde condensate, or water-soluble urea-melamine
condensate. To form a shell encapsulating the filler material,
formaldehyde is added to the aqueous phase, which is heated and
acidified. A condensation product then deposits on the surface of
the dispersed core material as the polymerization reaction
progresses. Unlike the interfacial polymerization reaction
described above, the method may be suitable for use with sensitive
filler materials since reactive agents do not have to be dissolved
in the filler material. In a related in situ polymerization method,
a water-immiscible liquid or solid containing a water-immiscible
vinyl -monomer and vinyl monomer initiator is dispersed in an
aqueous phase. Polymerization is initiated by heating and a vinyl
shell is produced at the interface with the aqueous phase.
[0151] Gas Phase Polymerization
[0152] Microcapsules may be prepared by exposing filler material
particles to a gas capable of S undergoing polymerization on the
surface of the particles. In one such method, the gas comprises
p-xylene dimers that polymerize on the surface of the particle to
form a poly(p-xylene) shell. Specialized coating equipment may be
necessary for conducting such coating methods, making the method
more expensive than certain liquid phase encapsulation methods.
Also, the filler material to be encapsulated is preferably not
sensitive to the reactants and reaction conditions.
[0153] Solvent Evaporation
[0154] Microcapsules may be prepared by removing a volatile solvent
from an emulsion of two immiscible liquids, e.g., an oil-in-water,
oil-in-oil, or water-in-oil-in-water emulsion. The material that
forms the shell is soluble in the volatile solvent. The filler
material is dissolved, dispersed, or emulsified in the solution.
Suitable solvents include methylene chloride and ethyl acetate.
Solvent evaporation is a preferred method for encapsulating water
soluble filler materials, for example, polypeptides. When such
water-soluble components are to be encapsulated, a thickening agent
is typically added to the aqueous phase, then the solution is
cooled to gel the aqueous phase before the solvent is removed.
Dispersing agents may also be added to the emulsion prior to
solvent removal. Solvent is typically removed by evaporation at
atmospheric or reduced pressure. Microcapsules less than 1 .mu.m or
over 1000 .mu.m in diameter may be prepared using solvent
evaporation methods.
[0155] Centrifugal Force Encapsulation
[0156] Microencapsulation by centrifugal force typically utilizes a
perforated cup containing an emulsion of shell and filler material.
The cup is immersed in an oil bath and spun at a fixed rate,
whereby droplets including the shell and filler material form in
the oil outside the spinning cup. The droplets are gelled by
cooling to yield oil-loaded particles that may be subsequently
dried. The microcapsules thus produced are generally relatively
large. In another variation of centrifugal force encapsulation
referred to as rotational suspension separation, a mixture of
filler material particles and either molten shell or a solution of
shell material is fed onto a rotating disk. Coated particles are
flung off the edge of the disk, where they are gelled or desolvated
and collected.
[0157] Submerged Nozzle Encapsulation
[0158] Microencapsulation by submerged nozzle generally involves
spraying a liquid mixture of shell and filler material through a
nozzle into a stream of carrier fluid. The resulting droplets are
gelled and cooled. The microcapsules thus produced are generally
relatively large.
[0159] Desolvation
[0160] In desolvation or extractive drying, a dispersion filler
material in a concentrated shell material solution or dispersion is
atomized into a desolvation solvent, typically a water-miscible
alcohol when an aqueous dispersion is used. Water-soluble shell
materials are typically used, including maltodextrins, sugars, and
gums. Preferred desolvation solvents include water-miscible
alcohols such as 2-propanol or polyglycols. The resulting
microcapsules do not have a distinct filler material phase.
Microcapsules thus produced typically contain less than about 15
wt. % filler material, but in certain embodiments may contain more
filler material.
[0161] Liposomes
[0162] Liposomes are microparticles typically ranging in size from
less than about 30 nm to greater than 1 mm. They consist of a
bilayer of phospholipid encapsulating an aqueous space. The lipid
molecules arrange themselves by exposing their polar head groups
toward the aqueous phase, and the hydrophobic hydrocarbon groups
adhere together in the bilayer forming close concentric lipid
leaflets separating aqueous regions. Medicaments can either be
encapsulated in the aqueous space or entrapped between the lipid
bilayers. Where the medicament is encapsulated depends upon its
physiochemical characteristics and the composition of the lipid.
Liposomes may slowly release any contained medicament through
enzymatic hydrolysis of the lipid. Lecithin-based bilayered
liposomes are particularly desirable encapsulants, due in part to
the antioxidant properties of lecithin.
[0163] Nanoparticles
[0164] Nanoparticles are small lipid vesicles, typically prepared
from lecithin, in the range of nanometers. Liposomes and
nanoparticles are of comparable size. Both occur in the range from
20 to 1000 nm in diameter. Whereas liposomes are composed of one or
more bilayer membranes, nanoparticles are formed by a single
layered shell. Liposomes are typically filled with water-soluble or
hydrophilic components and therefore are typical carriers for
hydrophilic substances. In contrast, nanoparticles are filled with
oleophilic or hydrophobic substances and lend themselves ideally as
carriers for lipophilic agents.
[0165] High pressure homogenization using a microfluidizer is a
sophisticated technology to prepare lipid vesicles such as
liposomes and nanoparticles. The method is easy to scale up and
yields reproducible results. The homogenizer has a specially
designed interaction chamber. In this chamber, the stream of the
premixed components is first divided and then combined again at a
particular angle. At this point, high shear and cavitation forces
form the lipid vesicles at a pressure of up to 1200 bar. The
technique of high pressure homogenization yields a i00%
encapsulation of dispersed oil in the vesicles.
[0166] Usually, multiple cycles through the interaction chamber are
necessary to obtain a homogenous product. The mean droplet size and
the size distribution are the main parameters to characterize
nanoparticle preparations. They can be determined by photon
correlation spectroscopy or by means of electron microscopy of
samples prepared by freeze fracture.
[0167] The core of the particles can contain a wide variety of
lipophilic agents, such as carotenes and carotenoids, as well as
hydrophobic antioxidants. The chemical stability of these
ingredients (against oxidation) can be enhanced by their
encapsulation into nanoparticles. Nanoparticle preparations can
contain up to 40% of oil soluble components. The vesicle size is
influenced by many parameters. Most important are homogenization
pressure, concentration and type of lecithin, concentration and
type of oil and the solvent concentration. Very small particles can
only be achieved at a high ratio of phospholipid to oil.
[0168] Miscellaneous Microencapsulation Processes
[0169] While the microencapsulation methods described above are
generally preferred for preparing the microcapsules of preferred
embodiments, other suitable microencapsulation methods may also be
used, as are known to those of skill in the art. Moreover, in
certain embodiments, it may be desired to incorporate an
unencapsulated carotene, carotenoid, or the like or other substance
directly into the fuel additive or additized fuel formulation.
Alternatively, the additive or other substance may be incorporated
into a solid matrix of a carrier substance. The microcapsules that
are added to the fuel additive or additized fuel formulation may
all be of the same type and contain the same additives or other
substances, or may include a variety of types of microcapsules
and/or encapsulated additives or other substances.
[0170] Spray Drying and Freeze Drying
[0171] Spray drying is widely used in industry as a method for the
production of dry solids in either powder, granulate or agglomerate
form from liquid feedstocks as solutions, emulsions and pumpable
suspensions. Spray drying methods may be suitable for preparing
solid particles containing carotenes, carotenoids, and the like.
The apparatus used for spray drying typically consists of a feed
pump, rotary or nozzle atomizer, air heater, air disperser, drying
chamber, and systems for exhaust air cleaning and powder recovery.
In spray drying, a liquid feedstock is atomized into a spray of
droplets and the droplets are contacted with hot air in a drying
chamber. Evaporation of moisture from the droplets and formation of
dry particles proceed under controlled temperature and airflow
conditions. The powder, granulate or agglomerate formed is then
discharged from the drying chamber. In some cases, it may be
necessary to continue the stirring or agitation of the solution
during the spray drying process so that the composition made at the
end of the spraying procedure is still well mixed. By adjusting the
operating conditions and dryer design, the characteristics of the
spray dried product can be determined.
[0172] Another preferred method for removing the solvent is freeze
drying. Freeze drying consists of three stages: pre-freezing,
primary drying, and secondary drying. Before freeze drying may be
initiated, the mixture to be freeze dried must be adequately
pre-frozen, i.e., the material is completely frozen so that there
are no pockets of unfrozen concentrated solute. In the case of
aqueous mixtures of solutes that freeze at lower temperature than
the surrounding water, the mixture must be frozen to the eutectic
temperature. Once the mixture is adequately pre-frozen, then the
solvent is removed from the frozen mixture via sublimation in the
primary drying step. After the primary drying step is completed,
solvent may still be present in the mixture in bound form. To
remove this bound solvent, continued drying is necessary to desorb
the solvent from the product
[0173] Preferred Methods for Encapsulating or Preserving
Beta-Carotene
[0174] In preferred embodiments, beta-carotene may be encapsulated
or preserved according to the methods described above.
Beta-Carotene may be encapsulated by spray drying, drum drying, or
freeze drying a mixture of beta-carotene in maltodextrin. It is
generally preferred to utilize 0.5 g beta-carotene per 1000 g
aqueous solution of 40% maltodextrin 25 DE, and subject the mixture
to homogenization prior to drying. Suitable methods of
encapsulating beta-carotene in maltodextrin by freeze drying, spray
drying, and/or drum drying are described in J. Food Sci. (1997),
62(6), 1158-1162; Crit Rev. Food Sci. Nutr. (1998), 38(5), 381-396;
and J. Food Process. Preserv. (1999), 23(1), 39-55.
[0175] Encapsulants other than maltodextrin for beta-carotene may
also be employed. Such encapsulants include pullulan (water-soluble
polysaccharide composed of glucose units that are polymerized in
such a way as to make it viscous and impermeable to oxygen) and
polyvinyl pyrrolidone of various molecular weights (PVP40 and
PVP360, for example) as described in Food Chemistry (2000), 71(2),
199-206. Hydrolyzed starch may also be utilized as an encapsulant,
as described in J. Food Sci. (1995), 60(5), 1048-53.
[0176] Additive Concentrates
[0177] The cetane improving package can be added to the base fuel
directly. Alternatively, the additive formulation may be provided
in the form of an additive package that may be used to prepare an
additized fuel. Optionally, various additives described above may
also be present in a concentrate.
[0178] Base Diesel Fuel
[0179] The diesel fuels utilized in the preferred embodiments
include that portion of crude oil that distills out within the
temperature range of approximately 150.degree. C. to 370.degree. C.
(698.degree. F.), which is higher than the boiling range of
gasoline. Diesel fuel is ignited in an internal combustion engine
cylinder by the heat of air under high compression, in contrast to
motor gasoline which is ignited by an electrical spark. Because of
the mode of ignition, a high cetane number is required in a good
diesel fuel. Diesel fuel is close in boiling range and composition
to the lighter heating oils. There are two grades of diesel fuel,
established by the ASTM: Diesel 1 and Diesel 2. Diesel 1 is a
kerosene-type fuel, lighter, more volatile, and cleaner burning
than Diesel 2, and is used in engine applications where there are
frequent changes in speed and load. Diesel 2 is used in industrial
service and No. 4, No. 5 light and heavy, and No. 6 Fuel oil are
used in heavy mobile service.
[0180] Suitable diesel fuels may include both high and low sulfur
fuels. Low sulfur fuels generally include those containing 500 ppm
(on a weight basis) or less sulfur, and may contain as little as
100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25,
20, 15, 20, or 5 ppm or less sulfur, or even 0 ppm sulfur, for
example, in the case of synthetic diesel fuels. High sulfur diesel
fuels typically include those containing more than 500 ppm sulfur,
for example, as much as 1, 2, 3, 4, or 5 wt. % sulfur or more.
[0181] Fuels that boil in a range of 150.degree. C. to 330.degree.
C. work best in diesel engines because they are completely consumed
during combustion, with no waste of fuel or excess emissions.
Paraffins, which offer the best cetane rating, are preferred for
diesel blending. The higher the paraffin content of a fuel, the
more easily it burns, providing quicker warm-ups and complete
combustion. Heavier crude components that boil at higher ranges,
although less desirable, may also be used. Naphthenes are the next
lightest components and aromatics are the heaviest fractions found
in diesel. Using these heavier components helps minimize diesel
fuel waxiness. At low temperatures, paraffins tend to solidify,
plugging fuel filters.
[0182] In addition to Diesel 1 and Diesel 2 fuels, other fuels
capable of combusting in a diesel engine may also be used as base
fuels in various embodiments. Such fuels may include, but are not
limited to, those based on coal dust emulsions and vegetable oil.
The vegetable oil based diesel fuels are commercially available and
are marketed under the name "bio-diesel." They typically contain a
blend of methyl esters of fatty acids of vegetable origin and are
often used as an additive to conventional diesel fuels.
[0183] Cetane Improver
[0184] A composition and method for increasing the amount of cetane
in fuel is provided. In certain preferred embodiments, the cetane
improver comprises beta-carotene or another carotene, carotenoid,
derivative or precursor thereof in combination with one or more
stabilizing compounds. In other preferred embodiments, the cetane
improver comprises encapsulated or otherwise preserved or protected
beta-carotene or another carotene, carotenoid, derivative or
precursor thereof, optionally in combination with one or more
stabilizing compounds.
[0185] Beta-Carotene, when encapsulated or in the presence of a
stabilizing compound, raises the level of cetane in No. 2 diesel
fuel more effectively and maintains the raised cetane level longer
than beta-carotene prepared by conventional methods. In preferred
embodiments, a cetane improver is prepared by mixing beta-carotene
with a stabilizer, such as ethoxyquin, and adding an alkyl nitrate,
for example, 2-ethylhexyl nitrate. The preferred cetane improver
prepared by the methods described herein increases the level of
cetane in No. 2 diesel fuel in a synergistic fashion.
[0186] In a preferred embodiment, the cetane improver formulation
can be formulated by the following method. Three grams of
beta-carotene (1.6 million International units of vitamin A
activity per gram) and 3 grams of ethoxyquin are dissolved in 200
ml of a liquid hydrocarbon carrier comprising toluene. It is
preferred to dissolve the beta-carotene and ethoxyquin with heating
and stirring. Next, approximately 946 milliliters of a 100%
solution of 2-ethylhexyl nitrate is added to the mixture and
toluene is added so as to obtain a total volume of 3.785 liters. It
is not necessary to prepare the cetane improver formulation under
inert atmosphere, although it is acceptable to do so. One or more
of the fuel additives recited above may also be added to the cetane
improver formulation, as desired.
[0187] It is to be understood that pure 2-ethylhexyl nitrate is
particularly preferred as an optional additive, but that other
alkyl nitrates or other grades of 2-ethylhexyl nitrate are also
suitable. Further, one of skill in the art will appreciate that
other alkyl nitrates or conventional cetane improvers or ignition
accelerators, as described above, perform similarly to 2-ethylhexyl
nitrate and can be substituted accordingly. Desirably, many
different formulations of cetane improver may be made, each having
a different alkyl nitrate or more than one alkyl nitrate and/or
proportions thereof relative to the beta-carotene. Certain such
formulations were evaluated for the ability to raise cetane levels
in No. 2 diesel fuel according to the methods described below. In
the embodiment described above, it is desirable to add the
ingredients in the order described above. However, in other
embodiments, variations in the order of addition can be made.
[0188] The cetane improver prepared as described above is one
embodiment of a "concentrated cetane improver." To improve the
cetane level in No. 2 diesel fuel, it is preferred to add from
about 0.1 ml or less to about 70 ml or more of the cetane improver
described above per one gallon No. 2 diesel fuel. Preferably, the
amount of concentrated cetane improver added to a gallon of No. 2
diesel fuel is in the range from about 0.3 ml to about 30 ml or 35
ml, more desirably, from about 0.5 ml to about 25 ml, still more
preferably, from about 0.75 ml to about 20 ml, even more
preferably, from about 1 ml to about 15 ml, and most preferably,
from about 2, 3, 4, or 5 ml to about 6, 7, 8, 9, 10, 11, 12, 13, or
14 ml. Similar treat rates may be utilized for other diesel fuels,
including high sulfur diesel fuels, low sulfur diesel fuels, poor
quality diesel fuels, high quality diesel fuels, biodiesel fuels,
and the like.
[0189] Although the above additive levels may be preferred for
certain embodiments, in other embodiments it may be preferred to
have other additive levels. For example, an additive comprising 125
ml of 2-ethylhexyl nitrate to 0.49 g beta-carotene and q.s. toluene
to yield 500 ml additive total ("OR--CT") may be present at about
0.05 ml per gallon additized fuel or less up to about 100 ml per
gallon additized fuel or more, preferably at about 0.2, 0.3, 0.4,
0.5, 0.6, 0.7, 0.8 or 0.9 ml up to about 10, 15, 20, 30, 40 or 50
ml, and most preferably at about 1, 1.5, 2, 2.5, 3, 3.5 or 4 ml up
to about 4.5, 5, 6, 7, 8, 9 or 10 ml. To this additized fuel
containing the OR--CT additive may be added ethoxyquin at about
0.05 ml per gallon additized fuel or less up to about 100 ml per
gallon additized fuel or more, preferably at about 0.2, 0.3, 0.4,
0.5, 0.6, 0.7, 0.8 or 0.9 ml up to about 10, 15, 20, 30, 40 or 50
ml, and most preferably at about 1, 1.5, 2, 2.5, 3, 3.5 or 4 ml up
to about 4.5, 5, 6, 7, 8, 9 or 10 ml.
[0190] In other embodiments, preferred fuels contain beta-carotene
without any 2-ethylhexyl nitrate added. In those embodiments, an
additive comprising 0.49 g beta-carotene and q.s. toluene to yield
500 ml additive may be added to yield a treat rate of from about
0.05 ml per gallon additized fuel or less to about 100 ml (or g)
per gallon additized fuel or more, preferably from about 0.2, 0.3,
0.4, 0.5, 0.6, 0.7, 0.8 or 0.9 ml (or g) to about 10, 15, 20, 30,
40 or 50 ml (or g), and most preferably from about 1, 1.5, 2, 2.5,
3, 3.5 or 4 ml (or g) up to about 4.5, 5, 6, 7, 8, 9 or 10 ml (or
g). Levels of ethoxyquin or other stabilizer(s) added may range
from about 0.05 ml or less per gallon additized fuel or less to
about 100 ml or more per gallon additized fuel, preferably from
about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9 ml (or g) to about
10, 15, 20, 30, 40 or 50 ml (or g), and most preferably from about
1, 1.5, 2, 2.5, 3, 3.5 or 4 ml (or g) to about 4.5, 5, 6, 7, 8, 9
or 10 ml (or g). These treat rates are preferred whether the
beta-carotene is in pure form or is encapsulated or otherwise
preserved or protected.
[0191] Appropriate substitutions for beta-carotene and/or
ethoxyquin may be made, with an appropriate adjustment in additive
levels, if desired. However the above additive levels are generally
preferred for substitutions as well. In certain embodiments, higher
or lower treat rates may be preferred.
EXAMPLES
[0192] Fuel additives of certain preferred embodiments may be
prepared according to the following descriptions. In other
embodiments, other methods of preparing the additives may be
preferred. Modifications to these methods, including the order of
addition of ingredients, substitutions of ingredients as described
above, the use of various diluents, the equipment utilized, mixing
conditions, and other aspects of the methods, are all
contemplated.
[0193] Various cetane improving additive formulations were tested
in base diesel fuels. Cetane testing was performed by independent
petroleum laboratories, each of which was CARB, EPA, and ASTM
Certified. The procedure for testing Cetane is ASTM D-613, a
published procedure that measures the ignition point of No. 2
diesel fuel. The test data, provided in Tables 1 and 2, verify that
the cetane improver described herein synergistically improves the
level of cetane in No. 2 diesel fuel.
[0194] Additive OR--CT was prepared which contained 395.8 parts by
weight toluene to 660.6 parts by weight of 2-ethylhexyl nitrate to
0.53 parts by weight of beta-carotene. Various samples of No. 2
diesel fuel were treated to contain 1057 ppm of additive OR--CT
(referred to as a "2+2" fuel). An additized fuel referred to as
"1+0.5" in the following tables corresponds to a fuel treated with
264 ppm OR--CT and 132 ppm 2-ethylhexyl nitrate. Additized fuel
referred to as "4+4" contains 1057 ppm OR--CT and 1057 ppm
2-ethylhexyl nitrate, and additized fuel referred to as "8+8"
contains 2114 ppm OR--CT and 2114 ppm 2-ethylhexyl nitrate.
[0195] Table 1 provides baseline cetane number data. Data include
cetane numbers for base fuels including various No. 2 diesel fuels,
base fuels additized with the conventional cetane improver
2-ethylhexyl nitrate, and base fuels additized with OR--CT prepared
under an inert atmosphere.
2TABLE 1 Change Cetane over Formulation Number Baseline Baseline
fuel - No. 2 Diesel 44.8 -- No. 2 diesel with 8 ml 100%
2-ethylhexyl nitrate 51.8 +7 added No. 2 diesel "8 + 8" 54.4 +9.6
Baseline fuel - No. 2 Diesel + 2-ethylhexyl 42.5 -- nitrate
pretreat No. 2 diesel + 2-ethylhexyl nitrate pretreat "4 + 4" 44.6
+2.1 Baseline fuel -No. 2 Diesel 37.0 -- No. 2 diesel with 8 ml
100% 2-ethylhexyl 41.8 +4.8 nitrate added No. 2 diesel "4 + 4" 41.9
+4.9 No. 2 diesel "8 + 8" 43.3 +6.3 Baseline fuel - No. 2 Diesel
32.7 -- No. 2 diesel with 8 ml 100% 2-ethylhexyl 39.4 +6.7 nitrate
added No. 2 diesel "4 + 4" 37.3 +4.6 No. 2 diesel "8 + 8" 41.4 +8.7
Baseline fuel - No. 2 Diesel 40.6 -- No. 2 diesel with 8 ml 100%
2-ethylhexyl 46.0 +5.4 nitrate added No. 2 diesel "2 + 2" 42.6 +2.0
No. 2 diesel "4 + 4" 45.6 +5.0 Baseline fuel - No. 2 Diesel 34.9 --
No. 2 diesel with 1.5 ml 100% 2-ethylhexyl 39.9 +5.0 nitrate added
No. 2 diesel with "1 + 0.5" 38.8 +3.9 Baseline fuel - No. 2 Diesel
36.4 -- No. 2 diesel with 4 ml 100% 2-ethylhexyl 40.3 +3.9 nitrate
added No. 2 diesel "2 + 2" 40.7 +4.3 Baseline fuel - No. 2 Diesel
42.2 -- No. 2 diesel "4 + 4" 50.7 +8.5 No. 2 diesel "8 + 8" 60.0
+17.3 Baseline fuel - No. 2 Diesel 47.8 -- No. 2 diesel "4 + 4"
57.4 +9.6 No. 2 diesel "8 + 8" 62.5 +14.7 Baseline fuel - No. 2
Diesel 51.3 -- No. 2 diesel "4 + 4" 61.0 +9.7 No. 2 diesel "8 + 8"
70.5 +19.2 Baseline fuel - No. 2 Diesel 22.9 -- No. 2 diesel "4 +
4" 31.6 +8.7 No. 2 diesel "8 + 8" 36.6 +13.7 Baseline fuel - No. 2
Diesel 31.8 -- No. 2 diesel "4 + 4" 39.1 +7.3 No. 2 diesel "8 + 8"
42.1 +10.3 Baseline fuel - No. 2 Diesel 38.0 -- No. 2 diesel "4 +
4" 48.5 +10.5 No. 2 diesel "8 + 8" 51.1 +13.1 Baseline fuel - No. 2
Diesel 49.2 -- No. 2 diesel "4 + 4" 54.6 +5.4 No. 2 diesel "8 + 8"
62.5 +13.3
[0196] Diesel fuel formulations containing the cetane improving
formulations of preferred embodiments were prepared and cetane
numbers compared to control diesel fuels. Air was bubbled through
samples designated "w/o nitrogen." Samples designated "w/nitrogen"
were prepared under inert atmosphere. No 2-EHN was separately added
to any of the treated samples designated as "4+0. " Ethoxyquin was
added to the formulations designated by "+ethoxyquin." The base
fuel used in the experiments reported in Tables 2 and 3 was a
Imperial Oil "clear" diesel fuel basestock. The base fuel used in
the experiments reported in Table 4 was a Petro-Canada "clear"
diesel fuel basestock.
3TABLE 2 Sample Number Cetane Number Change Treat Rate 1 37.8 --
base fuel 2 40.9 +3.1 2 + 2 (w/nitrogen) 3 42.5 +4.7 4 + 4
(w/nitrogen) 4 40.5 +2.7 2 + 2 (w/o nitrogen) (+ethoxyquin) 5 42.3
+4.5 4 + 4 (w/o nitrogen) (+ethoxyquin)
[0197]
4TABLE 3 Sample Number Cetane Number Change Treat Rate 6 36.8 --
base fuel 7 42.2 +5.4 4 + 4 (w/o nitrogen) 8 43.6 +6.8 8 + 8 (w/o
nitrogen) 9 41.4 +4.6 4 + 4 (w/o nitrogen) (+ethoxyquin) 10 44.9
+8.1 8 + 8 (w/o nitrogen) (+ethoxyquin)
[0198]
5TABLE 4 Sample Number Cetane Number Change Treat Rate 11 51.8
(neat) -- base fuel 12 49.2 -2.6 4 + 0 (w/o nitrogen) 13 50.1 -1.7
4 + 0 (w/o nitrogen) 14 54.9 +3.1 4 + 0 (w/o nitrogen)
(+ethoxyquin) 15 55.5 +3.7 4 + 0 (w/o nitrogen) (+ethoxyquin)
[0199] The comparative data in Tables 2-4 clearly demonstrate the
protective effect of ethoxyquin on the cetane improving properties
of beta-carotene even under harsh oxidative conditions (namely,
bubbling air through the sample for several minutes).
[0200] Table 5 provides a description of five diesel fuel samples
tested to further quantify the effects of exposure to air of fuels
treated with conventional additives and additives of preferred
embodiments. Additive OR--CT-A described below contained 125 ml of
2-ethylhexyl nitrate to 0.49 g beta-carotene and q.s. toluene to
yield 500 ml additive (prepared under inert atmosphere). The
OR--CT-A additive was added to selected samples to yield an
effective treat rate as reported in the table. Supplemental 2EHN
was added to selected samples. The total sample size for each
sample was 950 ml. Samples 4a-5a were subject to an aeration step
(shaking under ambient conditions). Samples 3a-5a were stored under
an air headspace. Samples 1a-2a were prepared under an inert
atmosphere and stored under an inert headspace. The time between
preparation of the fuel sample (including aeration, if performed)
and octane testing was over three days for each sample.
6TABLE 5 Additive OR-CT Ethoxyquin (effective Supplemental
Equivalent Equivalent added to treat rate 2EHN OR-CT-A Supplemental
sample in ml per (treat rate in (treat rate 2EHN (treat Inert
Cetane Sample (ml) gallon) ml per gallon) in ppm) rate in ppm) Air
Atm. Number 1a 0 2 2 528.5 528.5 no yes 40.9 2a 0 4 4 1057 1057 no
yes 42.5 3a 0 0 0 0 0 no no 37.8 4a 1 2 2 528.5 528.5 yes no 40.5
5a 1 4 4 1057 1057 yes no 42.3
[0201] The data demonstrate that similar octane improving
performance is observed for a beta-carotene containing a
formulation prepared under an inert atmosphere with no ethoxyquin
added as for a beta-carotene- and ethoxyquin-containing formulation
prepared under ambient conditions.
[0202] The protective effects of ethoxyquin in an aerated diesel
fuel containing beta-carotene as a cetane improving additive were
determined. Table 6 provides a description of the five diesel fuel
samples tested. Additive OR--CT-B contained 250 ml of 2-ethylhexyl
nitrate to 1 g beta-carotene to 0.25 g ethoxyquin and q.s. toluene
to yield 1000 ml additive. The OR--CT-B additive was added to
selected samples to yield an effective treat rate as reported in
the table. Supplemental 2EHN was added to selected samples.
Ethoxyquin was added to Samples 3b-4b. The total sample size for
each sample was 950 ml. Each sample was subjected to an aeration
step wherein air at 20 psi was bubbled through the additized sample
for 20 minutes. Such aeration conditions are substantially more
severe than any ambient atmosphere conditions to which a fuel may
be exposed in the field. Cetane test results were as follows.
7TABLE 6 Ethoxyquin Supplemental added Additive OR-CT-B 2EHN to
sample (effective treat rate (treat rate in ml Cetane Sample (ml)
in ml per gallon) per gallon) Number 1b 0 4 4 42.2 2b 0 8 8 43.6 3b
1 4 4 41.4 4b 1 8 8 44.9 5b 0 0 0 36.8
[0203] Diesel fuels containing ethoxyquin and beta-carotene as the
sole additives were tested for cetane improving properties. Table 7
provides a description of the five diesel fuel samples tested.
Samples 3c and 5c were prepared under ambient conditions. Samples
2c and 4c were prepared under inert atmosphere, but the cap to the
storage container was left off the samples for 15 minutes to expose
the samples to ambient conditions for that time period. Cetane test
results were as follows.
8TABLE 7 Ethoxyquin Beta-Carotene (ml per (ml per Inert Cetane
Sample gallon) gallon) Atmosphere Number 0c 0 0 No 51.8 1c 0 4 Yes
49.2 2c 0 4 No 50.1 3c 1 4 Yes 54.9 4c 1 4 No 55.5
[0204] The data demonstrate that the addition of ethoxyquin may
result in an effective doubling in cetane number improvement over
that observed for beta-carotene alone. Addition of conventional
cetane improving additives at typical treat rates generally yield a
cetane number improvement of about 2-3 cetane numbers. The OR--CT
additives described above with supplemental 2EHN may yield a cetane
number improvement of about 5 or more cetane numbers. Beta-Carotene
containing formulations to which ethoxyquin has been added may
yield a cetane number improvement of about 8 or more cetane
numbers.
[0205] Gum Inhibitor for Gasoline Jet and Other Fuels
[0206] As gasoline ages in the presence of air, chemical changes
may occur because certain fuel components will slowly oxidize.
These chemical changes contribute to existent gum and potential
gum, as described below. This oxidation process may be slowed by
adding inhibitor additives to the fuel. Oxidation stability tests
predict the ability of the fuel to resist gum formation when
stored, but gasoline does have a finite storage life since gum
formation cannot be completely eliminated.
[0207] Conventional as well as reformulated and oxygenated
gasolines generally have a storage life of about six months, but
under harsh storage conditions, the storage life can be
considerably shortened. Gasoline manufactured by cracking processes
contains unsaturated components which may oxidize during storage
and form undesirable oxidation products. Any unstable gasoline
undergoes oxidation and polymerization under favorable ambient
conditions to form gum, a resinous material. These early stage gums
may remain in solution and, due to further chemical changes, may be
precipitated. Gum formation is generally believed to be the result
of chain reactions of unsaturated paraffins initiated by radicals,
such as peroxides, and catalyzed by the presence of metals,
particularly copper, which have contaminated the fuel during
refining and handling operations.
[0208] Since gasoline is generally consumed shortly after a vehicle
is fueled, storage life is of little consequence to most consumers.
However, gasoline distributors, vendors, or even consumers may wish
to store gasoline for extended periods of time, e.g., for longer
than six months, or under non-optimal storage conditions.
Accordingly, an additive that provides superior resistance to
formation of gums which enables stored gasoline to perform
satisfactorily when used is desirable.
[0209] Existent gum is a sticky, tacky, varnish-like material that
is objectionable in fuel systems. When present in excess, gum clogs
fuel lines, filter and pump screens, and carburetor jets; causes
manifold deposits and sticky intake valves; and reduces the knock
value of gasoline. Existent gum is the nonvolatile residue present
in a gasoline or jet fuel. Results of existent gum tests indicate
the quantity of gum deposit that may occur if the product is used
immediately, but not the quantity of gum that may form when the
product is stored. ASTM test D381 for Existent Gum in Fuels by Jet
Evaporation is used to measure the gum (oxidation products) which
are formed before or during the test. In most instances, it can be
assumed that the low gum formation will ensure absence of
induction-system difficulties. On the other hand, large quantities
of gum in aviation turbine fuels is indicative of contamination of
fuel by higher boiling oils or particulate matter and generally
reflect poor handling practices in distribution downstream of the
refinery. High gum can cause deposits and sticking of intake valves
in automobile engines.
[0210] Potential gum (indicative of oxidation stability) is
determined by a test that indicates the presence of gum forming
materials and the relative tendency of gasolines and jet fuels to
form gums after a specified period of accelerated aging. This value
is used as an indication of the tendency of fuels to form gum
during extended storage. When added to fuels, inhibitors retard gum
formation but will not reduce gum that has already been formed. The
effects of potential gum are similar to those described for
existent gum. For automotive gasolines, the potential gum may be
expressed as the "induction period" (sometimes called the breakdown
time). This is a measure of the time (in minutes) elapsed during
the accelerated test until the fuel absorbs oxygen rapidly. For
aviation gasoline and jet fuel, the potential gum may be expressed
as the "potential or accelerated gum." This is the gum plus lead
deposits (from leaded fuels) measured at the end of a specified
accelerated aging (oxidation) period. ASTM test D525 for Oxidation
Stability of Gasoline (Induction Period Method) utilizes
accelerated oxidation conditions to determine the stability of
finished gasolines. The induction period may be used as an
indication of the tendency of motor gasoline to form gum in
storage, i.e., potential gum.
[0211] Quinolines, including dihydroquinolines such as ethoxyquin,
are particularly preferred for use in fuels to inhibit gum
formation, especially gum as measured by potential or accelerated
gum tests. The quinoline may be added to the fuel at levels typical
of other gum inhibitors. Depending upon the severity of the fuel,
the quinoline may be added at a level of less than 1 ppm or at a
level of 2, 3, 4, 5, 6, 7, 8, 9, or 10 ppm or more, preferably 10,
15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,
or 100 ppm or more, more preferably about 100, 150, 200, 250, 300,
350, 400, 450, or 500 ppm or more. If the fuel is particularly
severe, i.e., the base fuel has a high potential gum, then it may
be desirable to add the quinoline at a level of 600, 650, 700, 750,
800, 850, 900, 950, 1000, 2000, 3000, or 4000 ppm or more. In a
particularly preferred embodiment, ethoxyquin is added to gasoline
at a level of 50 to 750 ppm, preferably, 100 to 500 ppm, and more
preferably 200 or 400 ppm.
[0212] The gasolines utilized in the practice of various
embodiments can be traditional blends or mixtures of hydrocarbons
in the gasoline boiling range, or they can contain oxygenated
blending components such as alcohols and/or ethers having suitable
boiling temperatures and appropriate fuel solubility, such as
methanol, ethanol, methyl tert-butyl ether (MTBE), ethyl tert-butyl
ether (ETBE), tert-amyl methyl ether (TAME), and mixed
oxygen-containing products formed by "oxygenating" gasolines and/or
olefinic hydrocarbons falling in the gasoline boiling range. Thus
various embodiments involve the use of gasolines, including the
so-called reformulated gasolines which are designed to satisfy
various governmental regulations concerning composition of the base
fuel itself, components used in the fuel, performance criteria,
toxicological considerations and/or environmental considerations.
The amounts of oxygenated components, detergents, antioxidants,
demulsifiers, and the like that are used in the fuels can thus be
varied to satisfy any applicable government regulations.
[0213] Aviation gasoline is especially for aviation piston engines,
with an octane number suited to the engine, a freezing point of
-60.degree. C., and a distillation range usually within the limits
of 30+ C. And 180.degree. C.
[0214] Gasolines suitable for used in preferred embodiments also
include those used to fuel two-cycle (2T) engines. In two-cycle
engines, lubrication oil is added to the combustion chamber and
admixed with gasoline. Combustion results in emissions of unburned
fuel and black smoke. Certain two-cycle engines may be so
inefficient that 2 hours of running such an engine under load may
produce the same amount of pollution as a gasoline-powered car
equipped with a typical emission control system that is driven
130,000 miles. In a typical two-cycle engine vehicle, 25 to 30% of
the fuel leaves the tailpipe unburned. In California alone there
are approximately 500,000 two-cycle engines, which produce the
equivalent of the emissions of 4,000,000 million gasoline powered
cars. In Malaysia and throughout much of Asia, China and India the
problem is much more severe. Malaysia has 4,000,000 two-cycle
engines, which produce pollution equivalent to that from 32,000,000
automobiles.
[0215] Quinolines such as ethoxyquin may be added to any liquid
hydrocarbonaceous fuel susceptible to gum formation, including
diesel fuels, jet fuels, and resid fuels. Treat rates may be
similar to those used for gasoline, however it may be preferred to
adjust the treat rate up or down depending upon the severity of the
fuels and its susceptibility to gum formation.
[0216] The above description discloses several methods and
materials of the present invention. This invention is susceptible
to modifications in the methods and materials, such as the choice
of base fuel, the components selected for the base formulation, as
well as alterations in the formulation of fuels and additive
mixtures. Such modifications will become apparent to those skilled
in the art from a consideration of this disclosure or practice of
the invention disclosed herein. Consequently, it is not intended
that this invention be limited to the specific embodiments
disclosed herein, but that it cover all modifications and
alternatives coming within the true scope and spirit of the
invention as embodied in the attached claims.
* * * * *