Note: Descriptions are shown in the official language in which they were submitted.
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Fuel Compositions
Field of the Invention
This invention relates to fuel/ethanol mixtures containing reaction
products from the reaction of di- or trialkanolamines with vegetable oils as
additives. The present invention also relates to a process for the
production of diesel oil/ethanol mixtures and to the use of the reaction
products as solubilizers for ethanol-containing diesel fuel.
Prior Art
Numerous additives are used in hydrocarbon-based fuels, i.e. for
example gas oils, heating oils, gasoline, diesel, kerosene, etc. Besides
anti-corrosion and lubricity additives, known additives include flow
improvers or compounds which improve the emission values of gases such
as CO, C02 or NOX.
International patent application WO 98117745 describes a
preparation containing fatty acid diethanolamides, alcohol ethoxylates and
fatty acid ethoxylates as additives for fuels. International patent
application
WO 02/088280 describes preparations containing oleic acid alkanolamides
and alkoxylated oleic acid as additives for fuels.
In International patent application WO 02138707, nitrogen-containing
additives are mentioned as solubilizing aids for diesel/ethanol mixtures.
Although preparations of this type, as additives in diesel fuels,
reduce gaseous emissions and can be used in low concentrations, there is
still a demand for fuel additives which reduce the emission of harmful
gases without adversely affecting the properties of the fuel. The use of
preparations containing several components or the use of expensive raw
materials and/or elaborate refining processes should be avoided on
economic grounds.
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Accordingly, the problem addressed by the present invention was to
find an additive which, even in small quantities, would adequately reduce
the emission values of harmful gases and which would be inexpensive in
terms of production and raw materials. In addition, the additives would
advantageously be obtainable from renewable raw materials and would
represent surfactants that would enable the homogeneity of diesel fuel
mixtures containing alcohols to be increased by increasing the solubility of
the alcohol, particularly the commonly used ethanol, in the diesel fuel.
It has now surprisingly been found that ethanol can be adequately
dissolved in fuels, preferably in diesel oil, by using reaction products of
the
reaction of di- or trialkanolamines with vegetable oils or with alkyl esters
of
the fatty acid mixtures from vegetable oils.
Description of the Invention
Accordingly, the present invention relates firstly to fuel compositions
free from alkoxylated compounds containing at least 90% by weight of a
hydrocarbon-based fuel, 0.5 to 9% by weight dry ethanol and 0.1 to 5% by
weight of an additive in the form of a reaction product from the reaction of
di- or trialkanolamines with vegetable oils or with alkyl esters of the fatty
acid mixtures from vegetable oils.
In the context of the present invention, fuels are understood to be
any energy-yielding fuels of which the free combustion energy is converted
into mechanical work. This includes all types of motor and aircraft fuels
that are liquid at room temperature and normal pressure. Motor fuels, for
example for automobile or truck engines, generally contain hydrocarbons,
for example gasoline or higher-boiling petroleum oil fractions. The fuels
according to the invention are preferably diesel oil, more particularly diesel
containing biodiesel.
Diesel fuels are obtained from gas oil by cracking or from tars
obtained in the low-temperature carbonization of lignitic or hard coal.
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Diesel fuels are poorly flammable mixtures of liquid hydrocarbons which
are used as fuels for constant-pressure or compression-ignition engines
(diesel engines) and which consist predominantly of paraffins with
admixtures of olefins, naphthenes and aromatic hydrocarbons. Their
composition is variable and depends in particular on the method of
production. Typical products have a density of 0.83 to 0.88 g/cm3, a boiling
point of 170 to 360°C and flash points of 70 to 100°C. The fuels
according
to the invention preferably contain diesel oil or consist of diesel oil. This
also includes so-called biodiesel, i.e. a fatty acid methyl ester, preferably
rapeseed oil fatty acid methyl ester, which according to the invention is
preferably present in the diesel.
The dry ethanol is either commercially available "absolute ethanol"
with a specific water content, which can vary according to the particular
commercial product, or ethanol which is dried over generally known
desiccants, such as sodium for example, to a water content of preferably
below 0.5% by volume water. This drying step may optionally be followed
by drying over a molecular sieve.
The fuels according to the invention are distinguished by the fact
that they contain only the reaction product from the reaction of di- or
trialkanolamines with vegetable oils or with alkyl esters of the fatty acid
mixtures from vegetable oils as additives, so that there is no need for
expensive mixtures of different individual substances. Accordingly, the fuel
is a very inexpensive product because, apart from filtration, the reaction
product does not have to be subjected to any other refinement, thus
eliminating the need for expensive and time-consuming refining steps. The
main reaction products from the reaction of di- or trialkanolamines with
vegetable oils or with alkyl esters of the fatty acid mixtures from vegetable
oils are alkanolamides of the fatty acids present in the oils. Since,
according to the invention, these alkanolamides do not have to be
separated from unreacted raw materials, such as alkanolamines, partly
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reacted raw materials, such as di- or monoglycerides for example, other
reaction products, such as glycerol or ethanol or methanol, but only have to
be filtered to remove insoluble constituents, the reaction products are very
cost-favorable.
A particularly preferred embodiment of the invention are fuel
compositions which contain additives in the form of reaction products of di-
or trialkanolamines with vegetable oils in which the vegetable oils contain
fatty acid esters containing mono- or polyunsaturated C~,_2~ alkyl groups.
Fatty acid esters containing monounsaturated C~~ alkyl groups are
particularly preferred.
Unsaturated representatives are, for example, lauroleic, myristoleic,
palmitoleic, petroselaidic, oleic, elaidic, ricinoleic, linoleic, linolaidic,
linolenic, gadoleic, arachidonic and erucic acid. Mixtures of the methyl
esters of these acids are also suitable. A particularly preferred
embodiment is characterized by the use of fatty acid esters containing fatty
acids from the group consisting of methyl oleate, methyl palmitate, methyl
stearate and/or methyl pelargonate.
The fuel compositions according to the invention preferably contain
additives in the form of reaction products of di- or trialkanolamines with
vegetable oils where the vegetable oils are selected from the group
consisting of soybean oil, rapeseed oil, sunflower oil, peanut oil, linseed
oil,
olive oil, castor oil, palm oil and thistle oil. According to the invention,
the
reaction of soybean oil, sunflower oil or rapeseed oil, above all the reaction
of soybean oil, is particularly preferred.
The vegetable oils are essentially triglyceride mixtures, the glycerol
being completely esterified with relatively long-chain fatty acids.
Peanut oil contains on average (based on fatty acid) 54% by weight
oleic acid, 24% by weight linoleic acid, 1% by weight linolenic acid, 1% by
weight arachic acid, 10% by weight palmitic acid and 4% by weight stearic
acid. The melting point is 2 to 3°C.
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Linseed oil typically contains 5% by weight palmitic acid, 4% by
weight stearic acid, 22% by weight oleic acid, 17% by weight linoleic acid
and 52% by weight linolenic acid. The iodine value of linseed oil is in the
range from 155 to 205 and the saponification value in the range from 188
5 to 196. The melting point is ca. -20°C.
Olive oil mainly contains oleic acid. Palm oil contains around 2% by
weight myristic acid, 42% by weight palmitic acid, 5% by weight stearic
acid, 41 % by weight oleic acid and 10% by weight linoleic acid as fatty acid
components.
Rapeseed oil typically contains around 48% by weight erucic acid,
15% by weight oleic acid, 14% by weight linoleic acid, 8% by weight
linolenic acid, 5% by weight eicosenoic acid, 3% by weight palmitic acid,
2% by weight hexadecenoic acid and 1 % by weight docosadienoic acid as
fatty acid components. Rapeseed oil from new plants has higher levels of
the unsaturated components. Typical fatty acid contents here are 0.5% by
weight erucic acid, 63% by weight oleic acid, 20% by weight linoleic acid,
9% by weight linolenic acid, 1 % by weight eicosenoic acid, 4% by weight
palmitic acid, 2% by weight hexadecenoic acid and 1 % by weight
docosadienoic acid.
80 to 85% by weight of castor oil consists of the glyceride of
ricinoleic acid, around 7% by weight of the glycerides of oleic acid, 3% by
weight of the glycerides of linoleic acid and around 2% by weight of the
glycerides of palmitic and stearic acid.
Soybean oil contains 55 to 65% by weight, based on the total fatty
acids, of polyunsaturated acids, more particularly linoleic and linolenic
acid.
The situation is similar with sunflower oil, of which the typical fatty acid
spectrum, based on total fatty acid, is as follows: ca. 1 % by weight myristic
acid, 3 to 10% by weight palmitic acid, 14 to 65% by weight oleic acid and
20 to 75% by weight linoleic acid.
All the above figures relating to the fatty acid contents of the
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triglycerides are known to be dependent on the quality of the raw materials
and, accordingly, may vary.
In one particular embodiment of the invention, the additives are
reaction products of the reaction of di- or trialkanolamines with alkyl esters
of the fatty acid mixtures of the vegetable oils mentioned, particularly the
preferred vegetable oils. According to the invention, the alkyl esters of the
fatty acid mixtures are methyl esters and/or ethyl esters. The fatty acid
composition in the mixture derives from the particular native fatty acid
composition of the vegetable oil used and the particular quality of the raw
material from which the methyl and/or ethyl esters are produced in known
manner.
According to the invention, the di- or trialkanolamines to be reacted
to form the required reaction product are alkanolamines containing C~_a
alkanol groups, preferably ethanolamines. The di- or trialkanolamines may
have alkanol groups with the same number or with different numbers of
carbon atoms. However, the reaction with amines containing two or three
of the same alkanol groups is preferred, the reaction with diethanolamine or
triethanolamine being particularly preferred.
The additives present in the fuel compositions according to the
invention in the form of reaction products from the reaction of di- or
trialkanolamines with vegetable oils or with alkyl esters of the fatty acid
mixtures from vegetable oils are preferably characterized in that the
reaction is continued until the reaction product is clear and the product
dissolves clearly in diesel in the form of a 1% mixture at -10 to -
20°C. In
addition, apart from filtration, no other refining steps are necessary.
According to the invention, preferred fuel compositions are those in
which the ratio by volume (v/v) of diesel oil to additive is in the range from
1000:0.5 to 1000:50 and preferably in the range from 1000:1 to 1000:50. A
preferred embodiment is a fuel composition consisting of 90 to 98% by
weight diesel oil, 1 to 8% by weight dry ethanol and 0.1 to 1.5% by weight
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and preferably 0.5 to 1.0% by weight of an additive in the form of the
reaction product of di- or trialkanolamines with vegetable oils or with alkyl
esters of the fatty acid mixtures from vegetable oils.
The present invention also relates to a process for the production of
diesel oil/ethanol mixtures in which either diesel oil and dry ethanol are
mixed and an additive in the form of a reaction product from the reaction of
di- or trialkanolamines with vegetable oils or with alkyl esters of the fatty
acid mixtures from vegetable oils is added in quantities of at most 0.5 to
5.0% by weight or the additive in the form of a reaction product from the
reaction of di- or trialkanolamines with vegetable oils or with alkyl esters
of
the fatty acid mixtures from vegetable oils is first mixed in quantities of at
most 0.1 to 5.0% by weight in dry ethanol and then added to the diesel.
The use of the additives according to the invention enables mixtures
of fuels with dry ethanol, preferably diesel oil with dry ethanol, to be
inexpensively produced. Maximum quantities of 0.5 to 1.5% by weight of
additive are preferably added to the diesel oil/ethanol mixture. The fuel
composition as a whole is preferably dry, i.e. the water content of the fuel
composition as a whole should be less than 0.2% by volume and preferably
less than 0.1 % by volume.
The additives have a solubilizing effect. Accordingly, the present
invention also relates to the use of reaction products from the reaction of di-
or trialkanolamines with vegetable oils or with alkyl esters of the fatty acid
mixtures from vegetable oils as solubilizers for ethanol-containing diesel
fuels.
Examples
Production Examale 1
Reaction of soybean oil with triethanolamine (reaction ratio 1 mol oil : 1.5
mol amine):
772.4 g soybean oil and 199.3 g triethanolamine were weighed into
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a 2-liter three-necked flask and heated with stirring under nitrogen to
150°C. The temperature was then increased to 200°C over a period
of 1
hour, followed by stirring for 4 hours at 200°C. The initially cloudy
mixture
turned clear after 3 hours. After the 4 hours, the mixture was cooled to
80°C and, after the addition of 0.1 % filter aid, was filtered through
a Seitz
filter. The product was light brown, clear and liquid.
Products with other reaction ratios were similarly produced.
Production Example 2
Reaction of soybean oil with diethanolamine (reaction ratio 1 mol oil : 1.5
mol amine):
867.2 g soybean oil and 157.7 g diethanolamine were weighed into
a 2-liter three-necked flask and heated with stirring under nitrogen to
160°C, followed by stirring for 3 h at that temperature. After about 2
hours,
the cloudy starting mixture turned clear. After 3 hours, the mixture was
cooled to 80°C and, after the addition of 0.1 % filter aid, was
filtered through
a Seitz filter. The product was light brown, clear and liquid.
Products with other reaction ratios were similarly produced.
Production Example 3
Reaction of soybean oil fatty acid methyl ester with triethanolamine
(reaction ratio 3 mol Me ester : 3 mol amine):
872.1 g soybean oil fatty acid methyl ester and 447.6 g
triethanolamine were weighed into a 2-liter three-necked flask and heated
with stirring under nitrogen to 190°C. The temperature was then
increased
to 230°C over a period of 1 hour, followed by stirring for 3 hours at
230°C.
The initially cloudy mixture turned clear after 2 hours. After the 3 hours,
the
mixture was cooled to 80°C and, after the addition of 0.1 % filter aid,
was
filtered through a Seitz filter. The product was brown, clear and liquid.
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Example 4
The following Table shows some physical data of the reaction
prod ucts.
The effect of the additives according to the invention was tested inter
alia by the cold filter plugging point test (CFPP) according to EN 116:1997.
In this test, the additive-containing fuel was cooled in steps to -
30°C in a
mixture of 94% diesel LS, 5% ethanol and 1% reaction product, samples
being taken at temperature intervals of 1 °C and drawn through a
standardized filter unit under a reduced pressure of 2 kPa. The
temperature shown corresponds to the temperature at which the fuel is no
longer able to flow through the filter unit in a fixed time.
Reaction Reaction ratioAV SV AMV WaterDensity Pour
product (equivalents) (%) (20C) Point
oillmethylester:DEAITEA: (glcm') (C)
eth lene I
col
So a meth 1:1 0.08 -3
I ester
with DEA
So a meth 1:1 2.9133134 0.260.960 0
I ester
with TEA
So bean oil 3:1.5 0.71622.4 0.100.955 -6
with DEA
So bean oil 3:1.5 0.715272 0.050.956 0
with TEA
Soybean oil 3:1:1 2.315650.10.210.954 -2
with
TEAleth lene
I col
So bean oil 3:2.2 1.2139102 0.968 1
with TEA
So bean oil 3:0.8 0.917139 0.932 -2
with TEA
So bean oil 3:2.2 5.21465.2 0.967 -14
with DEA
So bean oil 3:0.8 1.11734.6 0.939 -8
with DEA
Soybean oil 3:2:1 1.913590 0.971 -2
with
TEAleth lene
I col
Soya methyl 3:2:1 2.113592 0.230.962 -3
ester with
~
TEA/ethylene
glycol
Continuation of Table
Reaction RefractionViscosityCFPP*Stability Water
product (n20D) (40C) (C) in uptake
mm~ls) storage* +0.1%water
0C
50C
20C
So a meth -20 ClearClearClearClear
I ester
with DEA
So a meth 1.4757 43.1 -23 ClearClearClearClear
I ester
with TEA
So bean oil 1.4808 111.0 -22 ClearClearClearClear
with DEA
So bean oil 1.4758 51.7 -20 ClearClearClearClear
with TEA
Soybean oil 1.4730 2.3 -21 ClearClearClearClear
with
TEA/eth lene
I col
So bean oil 1.4760 61.9 -22 ClearClearClearClear
with TEA
So bean oil 1.4745 38.9 -21 ClearClearClearClear
with TEA
So bean oil 1.4826 208.0 -21 ClearClearClearClear
with DEA
So bean oil 1.4778 61.3 -22 ClearClearClearClear
with DEA
Soybean oil 1.4740 59.0 -22 ClearClearClearClear
with
TEAleth lene
I col
Soya methyl 1.4735 2.1 -21 ClearClearClearClear
ester with
TEAlethylene
glycol
DEA = diethanolamine; TEA = triethanolamine; AV = acid value; SV =
saponification value;
AMV = amine value; CFPP = cold filter plugging point
