U.S. patent application number 12/841483 was filed with the patent office on 2011-01-27 for fuel composition derived from biodiesel.
Invention is credited to Chandrashekhar H. Joshi.
Application Number | 20110016776 12/841483 |
Document ID | / |
Family ID | 43496063 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110016776 |
Kind Code |
A1 |
Joshi; Chandrashekhar H. |
January 27, 2011 |
Fuel Composition Derived from Biodiesel
Abstract
The present invention relates to a fuel composition and method
for the preparation thereof. The fuel composition is particularly
useful as an aviation fuel and as a ground transportation fuel in
cold weather environments. The fuel composition includes oil
derived from a biological source such as vegetable oil and/or
animal fat. Further, the fuel composition can be based on
biodiesel. Moreover, the fuel composition of the present invention
includes a reduced amount of oxygen as compared to the biodiesel or
substantially no oxygen.
Inventors: |
Joshi; Chandrashekhar H.;
(Bedford, MA) |
Correspondence
Address: |
ECKERT SEAMANS CHERIN & MELLOTT
600 GRANT STREET, 44TH FLOOR
PITTSBURGH
PA
15219
US
|
Family ID: |
43496063 |
Appl. No.: |
12/841483 |
Filed: |
July 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61227583 |
Jul 22, 2009 |
|
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Current U.S.
Class: |
44/388 ;
44/451 |
Current CPC
Class: |
C10G 2300/1011 20130101;
C10G 3/42 20130101; C10G 2300/1018 20130101; C10G 2300/304
20130101; C10G 2300/202 20130101; Y02T 50/678 20130101; C10G
2300/1014 20130101; C10L 1/04 20130101; Y02E 50/13 20130101; Y02P
30/20 20151101; C10G 2400/08 20130101; Y02E 50/10 20130101; C10G
3/50 20130101; C10G 2300/30 20130101 |
Class at
Publication: |
44/388 ;
44/451 |
International
Class: |
C10L 1/19 20060101
C10L001/19; C10L 1/182 20060101 C10L001/182 |
Claims
1. A fuel composition, comprising: oil derived from a biological
source; and alcohol, wherein the fuel composition is at least
substantially free of oxygen and oxygen-containing compounds.
2. The fuel composition of claim 1, where the oil is selected from
the group of biological sources consisting of vegetable oil, crop
seed oil, animal oil, animal fat and combinations thereof.
3. The fuel composition of claim 1, wherein the alcohol is selected
from the group consisting of methanol, ethanol, propanol,
isopropanol, butanol and mixtures thereof.
4. The fuel composition of claim 1, wherein the fuel composition is
oxygen-free.
5. The fuel composition of claim 1, wherein the fuel composition
has a level of oxygen that is less than the level of oxygen in
biodiesel.
6. The fuel composition of claim 1, wherein the fuel composition
has a level of oxygen that is less than 2000 parts per million
oxygen based on the fuel composition.
7. The fuel composition of claim 1, wherein the fuel composition
includes molecules and each of the molecules has a carbon chain
length of from 12 to 14 carbons atoms.
8. The fuel composition of claim 1, wherein the fuel composition is
used for aviation fuel.
9. The fuel composition of claim 1, wherein the fuel composition is
used for ground transportation fuel in a cold climate.
10. The fuel composition of claim 1, wherein the fuel composition
comprises an alkane.
11. The fuel composition of claim 1, wherein the fuel composition
further comprises catalyst.
12. The fuel composition of claim 11, wherein the catalyst is
selected from the group consisting of calcium hydroxide, potassium
hydroxide and mixtures thereof.
13. A method for preparing a fuel composition, the method
comprising: reacting oil derived from a biological source and
alcohol to produce an alkyl ester-containing product, removing at
least a portion of oxygen from the alkyl ester-containing product
to produce a fuel composition which is at least substantially free
of oxygen and oxygen-containing compounds.
14. The method of claim 13, wherein the alkyl ester-containing
product comprises alkyl ester selected from the group consisting of
methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl
ester and mixtures thereof.
15. The method of claim 13, wherein the alkyl ester-containing
product comprises biodiesel.
16. The method of claim 13, wherein the reacting step is conducted
in accordance with a transesterification reaction.
17. The method of claim 13, wherein the removing step is conducted
in accordance with a nucleophilic acyl reaction.
18. The method of claim 13, wherein the cloud point of the fuel
composition is lower than the cloud point of the alkyl
ester-containing product.
19. The method of claim 13, wherein the removing step further
comprises removing a portion of carbon atoms from the alkyl
ester-containing product.
20. The method of claim 13, wherein the fuel composition comprises
molecules and each of the molecules has a carbon chain length of
from 12 to 14 carbon atoms.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/227,583, filed Jul. 22, 2009, and
entitled "Conversion and Purification of Biodiesel to Aviation
Fuel."
FIELD OF THE INVENTION
[0002] The present invention relates to a fuel composition and a
method of producing the fuel composition. In particular, the fuel
composition can be useful in cold temperature environments and as
aviation fuel.
BACKGROUND OF THE INVENTION
[0003] Global climate change is causing a shift in the sources of
energy from fossil fuels to more sustainable and renewable
resources, such as biodiesel. For ground transportation, there is a
significant development effort to use electricity from non-fossil
primary fuel to power cars, trucks and rail systems. However, in
cold climates, such as in temperate or polar regions of the world
(including a significant portion of the United States, Canada,
northern Europe and northern Asia), biodiesel fuels tend to
solidify rendering inoperable engines that use it.
[0004] Furthermore, for aircraft, the energy densities available
from batteries, fuel cells and other portable sources are not
sufficient. Aviation fuel, such as jet fuel, is generally a
specialized type of petroleum-based fuel used to power an aircraft
and is generally of a higher quality than fuel used for ground
transportation. Aviation fuel is designed to remain liquid at cold
temperatures as found in the upper atmosphere where aircraft fly.
Aviation fuels can include hydrocarbons, such as paraffins;
olefins; naphthenes and aromatics; antioxidants; and metal
deactivators. Known aviation fuels include jet fuels, such as JP-5,
JP 8, Jet A, Jet A-1, and Jet B. Aviation requires a high energy
dense liquid fuel to achieve the speeds and distances airplanes can
deliver today. Jet fuel has the highest volumetric energy density
of liquid fuels, such as ethanol, butanol, bio-kerosene, and
biodiesel.
[0005] There is a need in the art to develop a fuel composition
that does not solidify in cold temperature environments for use as
ground transportation fuel, that satisfies the specified standard
requirements for use as aviation fuel, and is based on sustainable
and renewable resources, such as biodiesel.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present invention provides a fuel
composition including oil derived from a biological source and
alcohol. The fuel composition is at least substantially free of
oxygen and oxygen-containing compounds.
[0007] The oil may be selected from the group of biological sources
including vegetable oil, crop seed oil, animal oil, animal fat, and
combinations thereof.
[0008] The alcohol may be selected from the group consisting of
methanol, ethanol, propanol, isopropanol, butanol, and mixtures
thereof.
[0009] The fuel composition may be oxygen free. In another
embodiment, the fuel composition may have a level of oxygen that is
less than the level of oxygen in biodiesel. In yet another
embodiment, the fuel composition may have a level of oxygen that is
less than 2000 parts per million oxygen based on the fuel
composition.
[0010] The fuel composition includes molecules and each of the
molecules may have a carbon chain length of from 12 to 14 carbon
atoms.
[0011] The fuel composition may be used for aviation fuel. In
another embodiment, the fuel composition may be used for ground
transportation fuel in a cold climate.
[0012] The fuel composition may include an alkane.
[0013] The fuel composition may further include a catalyst. The
catalyst may be selected from the group consisting of calcium
hydroxide, potassium hydroxide and mixtures thereof.
[0014] In another aspect, the present invention provides a method
for preparing a fuel composition. The method includes reacting oil
derived from a biological source and alcohol to produce an alkyl
ester-containing product; and removing at least a portion of oxygen
from the alkyl ester-containing product to produce a fuel
composition which is at least substantially free of oxygen and
oxygen-containing compounds.
[0015] In an embodiment, the alkyl ester-containing product may
include an alkyl ester selected from the group consisting of methyl
ester, ethyl ester, propyl ester, isopropyl ester, butyl ester and
mixtures thereof.
[0016] In another embodiment, the alkyl ester-containing product
may include biodiesel.
[0017] In the method, the reacting step may be conducted in
accordance with a transesterification reaction.
[0018] In the method, the removing step may be conducted in
accordance with a nucleophilic acyl reaction.
[0019] In an embodiment, the cloud point of the fuel composition
may be lower than the cloud point of the alkyl ester-containing
product.
[0020] In the method, the removing step may further include
removing a portion of carbon atoms from the alkyl ester-containing
product.
[0021] In the method, the fuel composition includes molecules and
each of the molecules may have a carbon chain length of from 12 to
14 carbon atoms.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention as set forth in the claims will become more
apparent from the following detailed description of certain
preferred practices thereof illustrated, by way of example only,
and the accompanying drawings, wherein
[0023] FIG. 1 is a schematic showing a reaction process for
reducing an ethyl ester to ethanol in accordance with an embodiment
of the present invention; and
[0024] FIG. 2 is a schematic showing a process for chemoselectively
reducing secondary and tertiary alcohols (e.g., 2-decanol) to
alkanes (e.g., decane) in accordance with an embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention relates to a fuel composition and
method thereof. The fuel composition can be used in various
applications. In particular, the fuel composition can be employed
as a cold weather fuel for use in ground transportation vehicles,
such as trucks, automobiles, railroads, and the like, and as an
aviation fuel for use in aircrafts, such as airplanes, helicopters,
and the like. Further, the fuel composition of the present
invention can be prepared based on biodiesel. For example,
biodiesel can be produced and converted to a fuel composition that
is suitable for use as cold weather ground transportation and
aviation fuel. Biodiesel is derived from plant oils, algae oils,
and animal fats, and therefore, the present invention provides a
fuel composition which is grown and produced using standard
agricultural and chemical processing methods. The biodiesel can be
converted to a fuel composition including an alkane or a mixture of
alkanes.
[0026] Biodiesel has various characteristics and properties that
make it unattractive for use in cold weather environments and as
aviation fuel. For example, biodiesel has an energy density that is
lower than required for aviation fuel. Further, at low
temperatures, certain molecules within biodiesel begin to
agglomerate into solid particles causing the normally translucent
biodiesel to appear cloudy. The highest temperature at which the
biodiesel begins to agglomerate or cloud is called the cloud point.
The cloud point is an important characteristic of fuels used in
internal combustion engines and jet engines because the presence of
solid or agglomerated particles causes fuel pumps and injectors to
clog rendering the engines inoperable. The cloud point for some
common biodiesel products are as follows: 0.degree. C. for canola;
1.degree. C. for soybean; -6.degree. C. for safflower; 1.degree. C.
for sunflower; -2.degree. C. for rapeseed; 13.degree. C. for
jatropha; and 15.degree. C. for palm. The cloud points of various
fossil fuels are as follows: 0.degree. C. for ULS diesel;
-40.degree. C. for Jet A; -47.degree. C. for JP-8; and -40.degree.
C. for ULS kerosene. Aviation fuels have very low cloud points. For
aviation fuels, the low cloud point is important because the fuel
must remain liquid at high altitude where temperatures are well
below zero. For ground transportation fuels, a low cloud point is
important because the fuel must remain liquid in cold weather
environments where ground vehicles are used.
[0027] The cloud point of fuel is a function of its chemical
composition. Most fossil fuels include numerous compounds in the
form of linear or branched chains of carbon atoms with one or more
oxygen and hydrogen atoms bound to each carbon atom. For example, a
general composition of conventional aviation fuel is
C.sub.mH.sub.n, where .sub.m is an integer from 12-14, and .sub.n
is an integer from 20 to 30, and a general composition of
conventional biodiesel is C.sub.jH.sub.kCO.sub.2CH.sub.3, where
.sub.j is an integer from 14 to 16, and .sub.k is an integer from
26 to 33. Jet A and synthetic aviation fuel are both composed of
alkanes, which are compounds of carbon and hydrogen only. Biodiesel
is a vegetable oil or animal fat-based diesel fuel composed of
long-chain alkyl esters. The differences between aviation fuels and
biodiesel include (i) the size of the molecules (biodiesel
molecules are larger and include more carbon atoms per molecule)
and (ii) the presence of oxygen (biodiesel contains oxygen, whereas
aviation fuel is at least substantially oxygen free).
[0028] The presence of the oxygen in the biodiesel molecule causes
it to have a degree of polarity (an electrostatic charge
separation). This polarity results in an attraction between oxygen
in one molecule to hydrogen atoms bound in an adjacent molecule
through van der Waal's forces. This attractive force among
biodiesel molecules causes solidification at higher temperatures
than a similar molecule without oxygen. For example, Table 1 shows
a comparison of the solidification temperature for various alkanes,
i.e., oxygen-free molecules, and corresponding alcohols, i.e.,
oxygen-containing molecules. As shown below, the alcohols have a
single oxygen atom in addition to the corresponding alkane. The
alcohol has a higher solidification point than the corresponding
alkane. The presence of additional oxygen atoms would result in a
greater difference in solidification points as compared to the
alkane.
TABLE-US-00001 TABLE 1 Solidifi- Solidifi- cation cation Alkane
Composition (C) Alcohol Composition (C) Methane CH.sub.4 -183
Methanol CH.sub.4O -97 Ethane C.sub.2H.sub.6 -183 Ethanol
C.sub.2H.sub.6O -115 Propane C.sub.3H.sub.8 -190 Propanol
C.sub.3H.sub.8O -127 Butane C.sub.4H.sub.10 -138 Butanol
C.sub.4H.sub.10O -90 Hexane C.sub.6H.sub.14 -95 Hexanol
C.sub.6H.sub.14O -47 Octane C.sub.8H.sub.18 -57 Octanol
C.sub.8H.sub.18O -16 Dodecane C.sub.12H.sub.26 -10 Dodecanol
C.sub.12H.sub.26O 24 Eicosane C.sub.20H.sub.42 37 Eicosanol
C.sub.20H.sub.42O 66
[0029] Thus, it is contemplated by the present invention that the
reduction in or removal of oxygen from the biodiesel, i.e.,
long-chain alkyl esters, will result in a product, i.e., an alkane,
having a lower solidification temperature or cloud point.
[0030] In addition, it is contemplated by the present invention
that reducing the length of the carbon chain in the biodiesel
molecule from 16-18 carbons to 12-14 carbons will further reduce
the solidification temperature or the cloud point of the resultant
fuel composition.
[0031] The reduction or removal of oxygen or oxygen-containing
components from biodiesel can be accomplished by employing a
variety of chemical or thermal processes that result in a
hydrocarbon, e.g., alkane, having less or no oxygen. The resulting
hydrocarbon (e.g., fuel) will have a lower solidification
temperature or cloud point than the starting biodiesel. The process
used for the reduction in or removal of oxygen from biodiesel can
include the reaction of an ester group, e.g., alkyl ester, with
other chemicals either catalytically or electrically. In addition
to removing oxygen atoms from the ester group, this ester reaction
may also remove carbon atoms such that the overall carbon chain
length of the biodiesel molecule is reduced. In one embodiment, the
fuel composition of the present invention is substantially free of
oxygen and has a carbon chain length of from 12 to 14 carbon atoms.
This embodiment produces a fuel composition that is essentially
comparable to aviation fuel (and compatible with aviation fuels to
produce a mixture thereof) and can be used as a fuel for ground
transportation vehicles in cold climates. In another embodiment,
the produced fuel contains a reduced oxygen content and has a
carbon chain length of 12-14 atoms. In a further embodiment, the
fuel composition of the present invention contains less than 2000
parts per million of oxygen based on the fuel composition.
[0032] Biodiesel can be produced by a variety of conventional
processes that are known in the art. Biodiesel is an oil-based
diesel fuel, wherein the oil is obtained from a biological source,
such as, but not limited to, a vegetable oil or animal fat. Oils
suitable for use in producing biodiesel can be oils obtained from a
wide variety of biological sources. Suitable oils from a biological
source can include, but are not limited to, crop seed oils,
vegetables oils, animal oils, animal fats, and combinations
thereof. The crop seed oils can be isolated from biological
sources, such as, but not limited to, rapeseed oil, sunflower oil,
mustard oil, canola oil, peanut oil, palm oil, coconut oil, soybean
oil, and mixtures thereof. Additional examples of suitable oils
include, but are not limited to, waste vegetable oil; animal fats,
including tallow, lard, yellow grease, chicken fat, by-products of
the production of Omega-3 fatty acids from fish oil, and mixtures
thereof; algae; oil from halophytes, such as salicornia bigelovii;
and mixtures thereof. In alternative embodiments, the oil from a
biological source can be distilled, separated, or at least
partially purified to increase or decrease the content of a
particular component of the oil, such as, but not limited to,
triglycerides, diglycerides, monoglycerides, saturated fatty acids,
unsaturated fatty acids, trilaurin, erucic acid, lauric acid, oleic
acid, linoleic acid, linolenic acid, stearic acid, palmitic acid,
and mixtures thereof.
[0033] In an embodiment, the oil from a biological source can be
hydrocracked in accordance with conventional processes known in the
art to yield smaller molecular weight species.
[0034] Biodiesel includes long-chain alkyl esters, such as, but not
limited to, methyl ester, ethyl ester, propyl ester, isopropyl
ester, butyl ester, and mixtures thereof. Biodiesel can be prepared
by a transesterification process, wherein lipids are chemically
reacted with alcohol. Suitable lipids include the oils derived from
biological sources (such as, but not limited to, vegetable oils and
animal fats) described herein. Suitable alcohols include, but are
not limited to, ethanol, methanol, propanol, isopropanol, butanol,
and mixtures thereof. In addition, the transesterification process
can include the presence of catalyst. The catalyst can be selected
from a wide variety of materials known in the art to facilitate the
reaction between lipids and alcohols. Suitable catalysts include,
but are not limited to, calcium hydroxide, potassium hydroxide, and
mixtures thereof. The transesterification reaction can be carried
out using a variety of conventional processes known in the art.
Suitable processes include, but are not limited to, common batch
processes, supercritical processes, and ultrasonic methods. In
general, the transesterification reaction converts base oil in the
vegetable or animal starting materials to the desired esters, e.g.,
alkyl esters, in the biodiesel product. The transesterification
process can produce by-products. For example, free fatty acids
present in the base oil are typically converted to soap and removed
from the process or they are esterified using an acidic catalyst.
Further, glycerol can be produced as a by-product of the
transesterification process. Typically, this crude glycerol is
purified by employing a conventional purification process known in
the art, such as, but not limited to, vacuum distillation. The
refined, purified glycerol then can be utilized directly or
converted into other products.
[0035] In one embodiment, biodiesel is made by reacting animal fat
or vegetable oil with methanol by transesterification. The process
yields two products: (i) methyl esters, i.e., biodiesel, and (ii)
glycerin, i.e., a by-product that can be used for the production of
soap. In alternate embodiments, this process can be conducted on
any scale, e.g., in a mason jar or in a large-scale production
facility.
[0036] In another embodiment, vegetable oil or animal fat reacts
with ethanol or methanol or mixtures thereof, and a catalyst, such
as calcium hydroxide or potassium hydroxide or a mixture thereof.
In a further embodiment, the initial oil or fat is relatively low
in free fatty acids in order to reduce or prevent the formation of
soap. The reactants are mixed thoroughly for about an hour at room
temperature or slightly-elevated temperature. In one embodiment,
the temperature is from about 20.degree. C. to about 50.degree. C.
After about one hour of mixing, the solution is allowed to
settle.
[0037] During the settling time, the heavy glycerin (glycerol)
settles to the bottom of the solution and biodiesel is formed on
top. The glycerin is then separated by, for example, draining it
from the bottom of a settling tank. In an alternate embodiment,
separation can be accomplished by using a centrifuge which is
typically employed in large scale production of biodiesel to reduce
the time needed to carry out the process.
[0038] The final steps in the process include washing and drying
the biodiesel using conventional methods known in the art. In one
embodiment, a fine mist of water is applied to the biodiesel to
absorb any trace amounts of the catalyst remaining in the
biodiesel. This is separated from the biodiesel, for example, in
the same manner as the glycerin separation. A subsequent bubbling
of air through the biodiesel removes any remaining water to ensure
a high purity biodiesel product for use in diesel engines.
[0039] In another embodiment, wherein the starting material
contains a significant amount of free fatty acids (as is typical in
vegetable oil after it is used for cooking or animal fat), a
pretreatment of the free fatty acid can be conducted using
conventional methods known in the art. For example, the vegetable
oil or animal fat can be reacted with hydrochloric acid and
methanol. This pretreatment converts the free fatty acids into
biodiesel. After washing and drying the hydrochloric acid from the
resulting solution using a conventional method known in the art,
the remaining vegetable oil can be converted to biodiesel using the
transesterification process described herein.
[0040] The following table gives approximate amounts of the
reactants needed to produce one gallon of biodiesel in accordance
with an embodiment of the invention. The amounts can depend on the
level of free fatty acid and water in the feedstock vegetable oil
or animal fat.
TABLE-US-00002 TABLE 2 Feedstock (veg. oil or animal fat) 1 gal
Methanol 0.1667 gal Potassium hydroxide 0.0435 kg Hydrochloric Acid
0.001 Gal Water 0.4 Gal Electric Power 0.6667 kW/Gal/hr
[0041] In one embodiment of the present invention, multiple
reactions may be necessary to reduce or remove the oxygen and/or
oxygen-containing compounds from biodiesel to produce a fuel having
a low solidification temperature or cloud point for use in cold
climates or as aviation fuel. For example, an ester, such as an
alkyl ester in biodiesel, can be reduced to two alcohols through a
reaction with lithium aluminum hydride (LiA1H.sub.4). This
nucleophilic acyl substitution reaction is generally conducted as
follows:
##STR00001##
[0042] FIG. 1 shows a four-step reaction process for reducing an
ethyl ester (I) to ethanol (V). In FIG. 1, the nucleophilic
hydrogen atom (H) from the hydride reagent (LiA1H.sub.4) adds to
the electrophilic carbon (C) in the polar carbonyl group of the
ester (I). Electrons from the carbon and oxygen double bond
(C.dbd.O) move to the electronegative oxygen atom (O) creating an
intermediate metal alkoxide complex (II).
[0043] The tetrahedral intermediate collapses and displaces the
alcohol portion of the ester as a leaving group, which produces a
ketone as an intermediate (III).
[0044] The nucleophilic H from the hydride reagent adds to the
electrophilic C in the polar carbonyl group of the aldehyde.
Electrons from the C.dbd.O move to the electronegative O creating
an intermediate metal alkoxide complex (IV).
[0045] The final step is a simple acid/base reaction. Protonation
(H+) of the alkoxide oxygen creates the primary alcohol product (V)
from the intermediate complex.
[0046] Reduction of the resultant alcohol to alkane can be
accomplished by a variety of chemical processes. FIG. 2 shows a
process for chemoselectively reducing secondary and tertiary
alcohols to alkanes. This direct pathway shows selective reduction
of the hydroxyl (OH) moiety without affecting other functional
groups. In FIG. 2, 2-decanol (compound 1a) is reduced to decane
(compound 2a) using this process. The reducing system in FIG. 2
includes dissolving 2-decanol in a CH.sub.2ClCH.sub.2Cl solvent
with hydrosilane and indium chloride (InCl.sub.3) catalyst, at a
temperature of about 80.degree. C. for about 4 hours.
[0047] The fuel composition of the present invention can provide at
least one of the following benefits: [0048] Reduced solidification
temperature or cloud point; and [0049] Agricultural-based starting
materials.
[0050] In one embodiment, wherein the fuel composition of the
present invention includes the conversion of biodiesel fuel to
ground transportation fuel or aviation fuel, the cloud point of the
fuel composition is less than the cloud point of the biodiesel. In
another embodiment, wherein the fuel composition of the present
invention is used as aviation fuel, the cloud point can be less
than or equal to about -40.degree. C. In another embodiment,
wherein the fuel composition of the present invention is used as
ground transportation fuel in cold temperature conditions, the
cloud point can be less than about -20.degree. C. Cold climate
conditions can vary and in one embodiment, cold climate
temperatures can be less than or equal to about 0.degree. C.
[0051] While specific embodiments of the invention have been
described in detail, it will be appreciated by those skilled in the
art that various modifications and alternatives to those details
could be developed in light of the overall teachings of the
disclosure. Accordingly, the particular embodiments disclosed are
meant to be illustrative only and not limiting as to the scope of
the invention, which is to be given the breadth of the appended
claims and any and all equivalents thereof.
* * * * *