Note: Descriptions are shown in the official language in which they were submitted.
CA 02489192 2004-12-10
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METHOD AND COMPOSITION FOR USING STABILIZED BETA-CAROTENE
AS CETANE )OVIPROVER IN HYDROCARBONACEOUS DIESEL FUELS
Field of the Invention
A diesel fuel additive is provided that includes beta-carotene stabilized with
2,2,4-
triinethyl-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
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.
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 (GARB) have adopted ambient air quality standards directed to
these pollutants.
Both agencies have also adopted specifications for lower-emission gasolines.
The Phase II California Reformulated Gasoline (CaRFG2) regulations became
operative in
March 1, 1996. Governor Davis signed Executive Order D-5-99 on March 25, 1999,
which.directs
the phase-out of methyl tertiary butyl ether (MTBE) in California's gasoline
by December 31, 2002.
The Phase III California Reformulated Gasoline (CaRFG3) regulations were
approved on August 3,
2000, and became operative on September 2, 2000. The CaRFG2 and CaRFG3
standards are
presented in Table A.
Table A
The California Reformulated Gasoline Phase 2 and Phase 3 Specifications
Property Flat ~ m~ Avera its Ca Limits
Limits in
Lim
CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG
Phase Phase Phase Phase Phase Phase Phase Phase Phase
I II III I II III I II III
Reid n/a 7.0 7.0 7.8 n/a n/a n/a 7.0 6.4
or -
7.2
Vapor 6.9
Pressure
si
Sulfur n/a 40 20 151 30 15 n/a 80 60
Content
30
wt. m
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PropertyFlat Avera its C a Limits
Limits in
Lim
CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG CaRFG
Phase Phase Phase Phase Phase Phase Phase Phase Phase
I II III I II III I II III
Benzene nla 1.0 0.8 1.7 0.8 0.7 n/a 1.2 1.1
Content
vol.
Aromaticsn/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
F
T90 n/a 300 305 329 290 295 n/a 330 330
F
O n/a 2 8 - n/a n/a_ n/a n/a 1.8 1.8
8 - 2.2 - - 3.5
2 1 3.5
1
xygen . .
.
Content 0 - 0 -
3.5 3.5
wt.
MTBE n/a n/a Pro- n/a n/a n/a n/a n/a Pro-
and Other hibited hibited
Oxygen-
ates
(other
than
ethanol
n/a = not applicable
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,
includiizg 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.
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.
Summarx of the Invention
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.
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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.
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.
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.
In an aspect of the second embodiment, the stabilizing compound includes 2,2,4-
trimethyl-
6-ethoxy-1,2-dihydroquinoline.
In an aspect of the second embodiment, the cetane improver further includes a
plant oil
extract and a thermal stabilizer.
In an aspect of the second embodiment, the plant oil extract includes an oil
extract of a
plant of the Legumizzosae family.
In an aspect of the second embodiment, the plant oil extract includes oil
extract of barley.
In an aspect of the second embodiment, the plant oil extract includes
chlorophyll.
In an aspect of the second embodiment, the thermal stabilizer includes jojoba
oil.
In an aspect of the second embodiment, the thermal stabilizer includes an
ester of a C20-
C22 straight chain monounsaturated carboxylic acid.
In an aspect of the second embodiment, the plant oil extract includes oil
extract of barley
and the thermal stabilizer includes jojoba oil.
In an aspect of the second embodiment, the cetane improver further includes a
diluent.
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.
In an aspect of the second embodiment, the cetane improver further includes an
oxygenate.
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.
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,
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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.
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.
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.
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.
In an aspect of the second embodiment, the diesel fuel cetane improver further
includes 2-
ethylhexyl nitrate.
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.
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 olefmic
compounds, and mixtures thereof; and a stabilizing compound that inhibits
oxidation of the cetane
improving additive.
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.
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.
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.
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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 m
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.
In a sixth embodiment, a gum inhibitor for gasoline is provided, the gum
inhibitor including
2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.
In a seventh embodiment, a gasoline composition including 2,2,4-trimethyl-6-
ethoxy-1,2-
dihydroquinoline is provided.
In an aspect of the seventh embodiment, the 2,2,4-trimetlryl-6-ethoxy-1,2-
dihydroquinoline
is present in the gasoline composition at a concentration of about 50 to 1000
ppm.
In an aspect of the seventh embodiment, 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.
In an aspect of the seventh embodiment, 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.
Detailed Description of the Preferred Embodiment
Introduction
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.
Cetane Improving Additive Formulation °
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-
dihydroquinoluie 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.
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
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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.
The additives of preferred embodiments may be difFerent from catalysts, in
that it is
believed tlzat 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 mixiizg 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.
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.
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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 I0, I 1, 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).
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 April 12, 2001; U.S.
Application No.
10/084,838 filed on February 26, 2002; U.S. Application No. 10/084,602 filed
on February 26,
2002; U.S. Application No. 10/084,603 filed on February 26, 2002; U.S.
Application No.
101084,237 filed on February 26, 2002; U.S. Application No. 10/084,835 filed
on February 26,
2002; U.S. Application No. 10/084,601 filed on February 26, 2002; U.S.
Application No.
10/084,836 filed on February 26, 2002; U.S. Application No. 10/084,579 filed
on February 26,
2002; U.S. Application No. 10/084,243 filed on February 26, 2002; U.S.
Application No.
10/084,833 filed on February 26, 2002; U.S. Application No. 10/084,236 filed
on February 26,
2002; U.S. Application No. 10/084,831 filed on February 26, 2002; PCT
Application No.
US02/06137 filed on February 26, 2002; and Canadian Application No. 2,373,327
filed on
February 26, 2002.
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 iti
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.
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 Floc
arfzicae and Hez~ba
calezzdulae" 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
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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-
Diphenylpyrrole" 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.-Biokhiin. Osn. Povysh. Prod. Sel'skokhoz. ZhivoW . (1971), 232-41; and
"Tetrahydroquinone Derivatives as Feed Antioxidants" in Sin. Issled. Eff.
Khim. Polim. Mater.
(1970), (4), 283-8.
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.
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 car0tenoids, 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.
Beta-Carotene
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.
The beta-carotene may be natural or synthetic. In a preferred form, the beta-
carotene is iil
natural form and contains a mixture of naturally occurring isomers, i.e., a
mixW re of the cis and
t~~a~s isomers. In another preferred form, the beta-carotene is synthetic, but
contains a mixture of
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isomers similar to that observed for natural beta-carotene. In other
embodiments, in may be
preferred that the beta-carotene include only t~~ans-beta-carotene, only cis-
beta-carotene, or a
mixture of the cis and t~ahs isomers in various ratios. Other isomers,
enantiomers, stereoisomers,
or substituted forms of beta-carotene may also be suitable for use.
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.
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.
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.
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 axe particularly preferred
as substitutes for beta
carotene or in combination with beta-carotene.
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
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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, 1 l,
12, 13, 14, 15, 16, 17,
18, 19, 20 or more carbon atoms) with one, two, three, or more olefinic
lincages. Such compounds
may be also be present in combination with the carotenes and/or carotenoids.
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.
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 iil 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.
The beta-carotene is typically added in 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 ui the fuel, releasing the encapsulated material., The tablet
preferably dissolves in the fuel
over an acceptable period of time. Dissolving aids may be included iii 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 tune, e.g., by the consumer directly to a vehicle's fuel tank, to
bulls fuel in the refinery, and
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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-Dihydroguiiioliiie
The beta-carotene or other long chain olefmic 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.
In a particularly preferred embodiment, the stabilizing compound contains a
quinoline
moiety, preferably 2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline, commonly
referred to as
ethoxyquin. The compound is marketed under the trademark SANTOQLTIN~ by
Solutia Inc. of St.
Louis, Missouri, and is widely used as an antioxidant for animal feed and
forage.
HaC~C
H2
iIICH3
Ha
H
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,
histidiiie, 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-dihydropyridiiie
derivative.
Particularly preferred stabilizing compounds for beta-carotene include oil-
soluble
antioxidants, including, but not limited to ascorbyl palmitate, butylated
hydroxyanisole, butylated
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hydroxytoluene, lecithin, propyl gallate, alpha-tocopherol, phenyl-alpha-
naphthylamine,
hydroquinone, nordihydroguaiaretic acid, rosemary extract, mixtures thereof,
and the like.
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;
tr ihydroxy butyrophenone; and anoxomer.
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)-
octane, 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.
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-tent-butyl-4-n-butylphenol, 2,4,6-tri-tent-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-methyl-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)-allcanoic acids and
allcylthioalkanoic 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
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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-hydroxyphenyltriazine;
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, dinaphtlrylamines, 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); emu oil; alpha-lipoic acid;
and the lilee; and
mixtures thereof.
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 oletrnic 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 olefmic compo2.mds may result in
a synergistic
increase in cetane number, as demonstrated in the examples below.
Cetane Improvers
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 luiear 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
nitxate, n-butyl nitrate, isobutyl
nitrate, sec-butyl nitrate, tent-butyl nitrate, n-amyl nitrate, isoarnyl
nitrate, 2-amyl nitrate, 3-amyl
nitrate, tent-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,
cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, and
the esters of allcoxy
substituted aliphatic alcohols, such as 1-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
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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.
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 fmd use in
the preferred embodiments as primers when used in combination witli the other
ignition
accelerators.
Ratio of Beta-Carotene to Stabilizin~pound
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.
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 l:l 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.
It is preferred that the ratio of beta-carotene and/or substitutes(s) to
ethoxyquin and/or
substitutes) 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 ftiel may be adjusted up or down, depending upon various factors
as described above.
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Other Additives
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.
Plant Oil Extracts
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 forn 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.
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 tef~
Especially preferred plant oil extracts are those derived from plants that are
members of the
Fabaceae (Legt~ntinosae) plant family, commonly referred to as the pulse
family, and also as the
pea or legume family. The Legumi~osae 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: Mitttosoideae, which are mainly tropical trees and shrubs;
Caesalpi>zioideae, which
include tropical and sub-tropical shrubs; and Papilioniodeae which includes
peas and beans. A
common feature of most members of the Legunai~aosae family is the presence of
root nodules
containing nitrogen-fixing Rhizobiuttt bacteria. Many members of the
Leguntittosae family also
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accumulate high levels of vegetable oils in their seeds. The Leguminosae
family includes the lead-
plant, hog peanut, wild bean, Canadian mille 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.
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 Legumiraosae family. While such a form is generally
preferred for most
embodiments, in certain other embodiments a liquid or some other form may be
preferred.
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 octaves, isooctane, and the like.
Examples of the
cycloallcane 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 C 12 alkanes, particularly n-hexme.
Hexane extraction is the most commonly used technique for extracting oil from
seeds. It is
a highly e~cient 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 2I2°
F, the temperature at which
hexane flashes off, and is then distilled to remove all traces of hexane.
Alternatively, hexane may
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be removed by evaporation at reduced pressure. The resulting oil extract is
suitable for use in the
formulations of preferred embodiments.
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.
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.
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°C and 90°C, or external heat may
be applied. Cold pressing
generally refers to mechanical pressing conducted at a temperature of
40°C or less with no external
heat applied.
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.%.
Thermal Stabilizers
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 alinost 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",
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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.
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, palin 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.
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 volmne of jojoba oil.
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-tent-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 (US 5,076,814
and U.S. 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-4-hydroxyphenyl) butane; pentaerythrityl tetraleis[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. 4,007,157, U.S. 3,920,661).
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
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acids which are useful as stabilizers of organic material normally susceptible
to oxidative and/or
thermal deterioration. (U.S. 4,806,675 and U.S. 4,734,519 to Dunski, et al.);
the reaction product of
malonic acid, dodecyl aldehyde and tallowamine (U.S. 4,670,021 to Nelson, et
al.); hindered phenyl
phosphates (U.S. 4,207,229 to Spivack); hindered piperidine carboxylic acids
and metal salts thereof
(U.S. 4,191,829 and U.S. 4,191,682 to Ramey, et al.); acylated derivatives of
2,6-dihydroxy-9-
azabicyclo[3.3.1]nonane (U.S. 4,000,113 to Stephen); bicyclic hindered amines
(U.S. 3,991,012 to
Ramey, et al.); sulfur containing derivatives of diallcyl-4-
hydroxyphenyltriazine (U.S. 3,941,745 to
Dexter, et al.); bicyclic hindered amino acids and metal salts thereof (U.S.
4,051,102 to Ramey , et
al.); trialkylsubstituted hydroxybenzyl malonates (U.S. 4,081,475 to Spivack);
hindered piperidine
carboxylic acids and metal salts thereof (U.S. 4,089,842 to Ramey , et al.);
pyrrolidine dicarboxylic
acids and esters (U.S. 4,093,586 to Stephen); metal salts of N,N-disubstituted
(3-alanines (U.S.
4,077,941 to Stephen , et al.); hydrocarbyl thioalkylene phosphates (U.S.
3,524,909); hydroxybenzyl
thioallcylene phosphates (U.S. 3,655,833); and the like.
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 phenylnaphtlrylamines,
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.
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 polyalphaolefms, dibasic acid esters, polyol esters, alkylated
aromatics, polyalkylene
glycols, and phosphate esters.
Polyalphaolefms are hydrocarbon polymers that contain no sulfur, phosphorus,
or metals.
Polyalphaolefms 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.
Polyol esters include molecules containing two or more alcohol moieties, such
as
trimetlrylolpropane, neopentylglycol, and pentaerythritol esters. Synthetic
polyol esters are the
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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.
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.
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.
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
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with Meadowfoam Oil," Terry, et al., United States Department of Agriculture,
Agricultural
Research Service, 1997.
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 airlfuel 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.
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.
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 NOX emissions.
Any of a number of different types of suitable detergent additives can be
included in diesel
fuel compositions of various embodiments. These detergents include
succiniinide
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 diethylene
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
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example, in the range of 0.9 to 1.3, or in the range of 0.7 to l.l), 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 1.9 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.
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, C3 and Ca
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.
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.
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.
Use of fuel-soluble Mannich base additives formed from a long chain allcyl
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.
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, TX as OGA-480TM additive.
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
metallliter 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
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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.
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 amine, oleyl amine, linolylamine, stearyl amine, eicosyl
amine, triacontyl
amine, pentacontyl amine and the like. A particularly effective amine is oleyl
amine obtainable
1 S from Akzo Nobel Surface Chemistry LLC of Chicago, IL under the name
ARMEEN~ O or
ARMEEN~ OD. Other suitable amines which are generally mixtures of aliphatic
amines include
ARMEEN~ T and ARMEEN~ TD, the distilled form of ARMEEN~ 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~ T and ARMEEN~ TD are derived from
tallow
fatty acids. Lauryl amine is also suitable, as is ARl~~ENO 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 iii the art and yay 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.
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, diner
and trimer of the
acid. A particularly preferred diner acid is the diner of linoleic acid.
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Antioxidants - Various compounds known for use as oxidation inhibitors can be
utilized in
fuel formulations of various embodiments. These include phenolic antioxidants,
amiize
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-tart-butylphenol, 4-methyl-2,6-di-tart-butylphenol, 2,4-
dimethyl-6-tart-butylphenol,
4,4'-methylenebis(2,6-di-tart-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-tart-butylphenol, 2,4,6-tri-tart-butylphenol and o-tart-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.
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, TX under the TOLAD~ trademark. Other known
demulsifiers can also
be used.
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~ trademark by Cognis Corporation of Cincinnati, OH.
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.
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.
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
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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-hexanediamine, and N,N"-disalicylidene-N'-methyl-
dipropylene-triamine.
The various additives that cm 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
lalown to those
skilled in the art.
Thermal Stabilizers - Thermal stabilizers such as Octel Starreon high
temperature fuel oil
stabilizer FOA-81TM, or other such additives may also be added to the fuel
formulation.
Carrier fluids - Substances suitable for use as caiTier fluids include, but
are not limited to,
mineral oils, vegetable oils, animal oils, and synthetic oils. Suitable
mineral oils may be primarily
paraffmic, 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, polyalphaolefms, polyol esters, monoesters, diesters
(adipates, sebacates,
dodecanedioates, phthalates, dimerates), and triesters.
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 l, 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.
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
fimction 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 NOx or
hydrocarbon.
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
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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).
Microencapsulated Beta-Carotene
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.
In a prefewed 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.
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 pxn or less to about 1000 p,m
or more, preferably
from about 2 Nxn to about 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600,
700, 800, or 900 pm,
and more preferably from about 3, 4, 5, 6, 7, 8, or 9 p,m to about 10, 15, 20,
25, 30, 35, 40 or 45
p,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 l.txn),
preferably from about 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, or 90 mn
up to about 100, 200,
300, 400, 500, 600, 700, 800, or 900 nm.
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.
Microcapsule Components
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
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unsaturated compounds, optionally in combination with other substances, such
as a beta-carotene
stabilizer, e.g., ethoxyquin. The filling material is encapsulated within the
microcapsuhe by a shell
material.
Typical shell materials may include, but are not limited to, gum arabic,
gelatin,
ethyhcellulose, pohyurea, 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.
Microencapsulation Processes
A variety of encapsulation methods may be used to prepare the microcapsuhes 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.
Spray Dry
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 microcapsuhes including shell materials such as,
for example, gelatin,
hydrolyzed gelatin, gum arabic, modified starch, maltodextrins, sucrose, or
sorbitoh. 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 p,m to greater than about 50 Vim. 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
microcapsuhe 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.
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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 iinmiscible
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.
Fluidized-Bed Microencapsulation
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 prn, however smaller microcapsules may
also be prepared.
Complex Coacervation
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.
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.
Polymer-Polymer Incompatibility
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 filin of the polymer that is preferentially absorbed. The
microcapsules are obtained by
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either crosslinleing 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.
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 pm or less.
Interfacial Polymerization
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.
Typical polymerization reactants may include acid chlorides or isocymates,
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.
In another type of microencapsulation by interfacial polymerization, commonly
referred to
as ifz 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 i~ situ
polymerization method, a water-immiscible liquid or solid containing a water-
immiscible vinyl
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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.
Gas Phase Polymerization
Microcapsules may be prepared by exposing filler material particles to a gas
capable of
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 polyp-
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.
Solvent Evaporation
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 p,m or over 1000 p,rn in diameter may be prepared using solvent
evaporation methods.
Centrifugal Force Encapsulation
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.
Subiner~ed Nozzle Encapsulation
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.
Desolvation
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,
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including maltodextrins, sugars, and gums. Preferred desolvation solvents
include water-miscible
ahcohohs 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.
Li~osomes
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 bihayer 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.
Nanoparticles
Nanoparticles are small lipid vesicles, typically prepared from lecithin, in
the range of
manometers. Liposomes and nanopartiches are of comparable size. Both occur in
the range from 20
to 1000 nm in diameter. Whereas hiposomes 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 oheophilic or hydrophobic substances and lend
themselves ideally as
carriers for hipophilic agents.
High pressure homogenization using a microfluidizer is a sophisticated
technology to
prepare lipid vesicles such as hiposomes and nanoparticles. The method is easy
to scale up and
yields reproducible results. The homogenizes 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 100%
encapsulation of
dispersed oil in the vesicles.
Usually, multiple cyches 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.
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 nanopartiches.
Nanopartiche
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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.
Miscellaneous Microencapsulation Processes
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.
Spray Dryin~,and Freeze Drying
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.
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.
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Preferred Methods for Encapsulating or Preserving- Beta-Carotene
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
S 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.
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.
Additive Concentrates
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.
Base Diesel Fuel
The diesel fuels utilized in the preferred embodiments include that portion of
crude oil that
distills out within the temperature range of approximately 150°C to
370°C (698°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 l 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.
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 l, 2, 3, 4, or
5 wt. % sulfur or more.
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Fuels that boil in a range of 150°C to 330°C work best in diesel
engines because they are
completely consumed during combustion, with no waste of fuel or excess
emissions. Paraffms,
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 a.nd aromatics are the heaviest fractions
found in diesel. Using
these heavier components helps minimize diesel fuel waxiness. At low
temperatures, paraffms tend
to solidify, plugging fuel filters.
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.
Cetane Im~rover
A composition and method for increasing the amount of ceta.ne 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.
Seta-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.
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
care ier 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.
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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.
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
1 S 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.
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 l, 1.5, 2, 2.5, 3, 3.5
or 4 ml up to about 4.5, 5,
6, 7, 8, 9 or 10 ml.
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 l, 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).
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Levels of ethoxyquin or other stabilizers) 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.
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
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.
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.
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.
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.
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Table 1.
Formulation Cetane Cliange
Number over
Baseline
Baseline fuel - No. 2 Diesel 44.8 --
No. 2 diesel with 8 ml 100% 2-eth lhex 51.8 +7
1 nitrate added
No. 2 diesel "8+8" 54.4 +9.6
Baseline fuel - No. 2 Diesel + 2-eth lliex42.5 ---
1 nitrate retreat
No. 2 diesel + 2-eth Ihex 1 nitrate retreat44.6 +2.1
"4+4"
Baseline fuel - No. 2 Diesel 37.0 --
No. 2 diesel with 8 ml 100% 2-eth lhex 41.8 +4.8
1 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-eth Ihex 39.4 +6.7
I 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-eth lhex 46.0 +5.4
1 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-eth lhex 39.9 +5.0
1 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-eth lhex 40.3 +3.9
1 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
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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-Caxiada
"clear" diesel fuel
basestock.
Table 2.
Sample Cetane Number. Change Treat Rate
Number
1 37.8 -- base fuel
2 40.9 + 3 .1 2 + 2 w/ vitro en
3 42.5 + 4.7 4 + 4 w/ vitro en
4 40.5 + 2.7 2 + 2 w/o vitro en + ethox
uin
5 42.3 + 4.5 4 + 4 w/o vitro en + ethox
uin
Table 3.
Sample Cetane NumberChange Treat Rate
Number
6 36.8 - base fuel
7 42.2 + 5.4 4 + 4 w/o vitro en
8 43.6 + 6.8 8 + 8 w/o vitro en
9 41.4 + 4.6 4 + 4 w/o vitro en + ethox
uin
10 44.9 + 8.1 8 + 8 w/o vitro en + ethox
uin
Table 4.
Sample Cetane NumberChange Treat Rate
Number
11 51.8 neat -- base fuel
12 49.2 - 2.6 4 + 0 w/o vitro en
13 5 0.1 - 1.7 4 + 0 w/o vitro en
14 54.9 + 3.1 4 + 0 w/o vitro en + ethox
uin
15 5 5.5 + 3 .7 4 + 0 w/o vitro en + ethox
uin
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,
bubbluig air through the sample for several minutes).
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
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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-Sa were subject to an aeration step (shaleing
under ambient
conditions). Samples 3a-Sa were stored under an air headspace. Samples la-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.
Table 5.
SampleEthoxyquinAdditiveSupplementalEquivalentEquivalentAir Inert Cetane
added OR-CT 2EHN OR-CT Supplemental Atm. Number
to -A
sample (effective(treat (treat 2EHN (treat
rate in rate
(ml) treat ml per in ppm) rate in
rate gallon) ppin)
in ml
per
allon
la 0 2 2 528.5 528.5 no es 40.9
2a 0 4 4 1057 1057 no es 42.5
3a 0 0 0 0 0 no no 37.8
4a 1 2 2 528.5 528.5 es no 40.5
Sa 1 4 4 1057 1057 es no 42.3
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.
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.
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Table 6.
Sample Ethoxyquin Additive SupplementalCetane Number
added OR-CT-B 2EHN
to sample (effective (treat rate
(ml) treat rate in ml
in ml per er anon
gallon)
lb 0 4 4 42.2
2b 0 8 8 43.6
3b 1 ~ 4 4 41.4
4b 1 8 8 44.9
Sb 0 0 0 36.8
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 Sc 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.
Table 7.
SampleEthoxyquinBeta- Inert Cetane
(ml per CaroteneAtmosphere Number
gallon) (ml
per
allon
Oc 0 0 No 51.8
1 0 4 Yes 49.2
c
2c 0 4 No 50.1
3c 1 4 Yes 54.9
4c 1 4 No 55.5
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.
Gum Inhibitor for Gasoline, Jet, and Other Fuels
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.
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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.
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.
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.
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
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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.
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 gurn, 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.
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.
Aviation gasoline is especially for aviation piston engines, with an octane
number suited to
the engine, a freezing point of -60°C, and a distillation range usually
within the limits of 30°C and
180°C.
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
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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.
Quinolines such as ethoxyquin may be added to any liquid hydrocarbonaceous
fuel
succeptible 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.
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.
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