Note: Descriptions are shown in the official language in which they were submitted.
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1
Use of mixtures of monocarboxylic acids and polycyclic hydrocarbon compounds
for
increasing the cetane number of fuel oils
Description
The present invention relates to the use of mixtures of aliphatic saturated or
unsaturated, relatively long-chain monocarboxylic acids or derivatives thereof
and
polycyclic hydrocarbon compounds for increasing the cetane number of fuel oils
which
comprise at least one additive with detergent action and at least one cetane
number
improver.
Fuel oils generally comprise cetane number improvers, which are also referred
to as
ignition accelerators or combustion improvers. For this purpose, typically
organic
nitrates are used, which have been known for some time as cetane number
improvers
in fuel oils or middle distillates such as diesel fuels, and have also been
used therein.
Higher cetane numbers lead to more rapid engine starts, especially in cold
weather, to
lower engine noise, to more complete combustion, to less evolution of smoke
and,
under some circumstances, to lower injector carbonization.
Typical organic nitrates which are suitable as cetane number improvers in fuel
oils,
especially in diesel fuels, are nitrates of short- and medium-chain, linear
and branched
alkanols and nitrates of cycloalkanols, such as n-hexyl nitrate, 2-ethyl-hexyl
nitrate,
n-heptyl nitrate, n-octyl nitrate, isooctyl nitrate, sec-octyl nitrate, n-
nonyl nitrate, n-decyl
nitrate, n-dodecyl nitrate, cyclopentyl nitrate, cyclohexyl nitrate,
methylcyclohexyl
nitrate and isopropylcyclohexyl nitrate. Specific branched decyl nitrates of
the formula
R1R2CH-CH2-0-NO2 in which R1 denotes an n-propyl or isopropyl radical and R2 a
linear or branched alkyl radical having 5 carbon atoms are also recommended in
WO 2008/092809 as combustion improvers or cetane number improvers. However,
the
most commercially important cetane number improver is 2-ethylhexyl nitrate.
However, the prior art cetane number improvers mentioned are still in need of
improvement in terms of action. It was thus an object of the present invention
to
increase the cetane number of fuel oils, especially of diesel fuels and of
mixtures of
biofuel oils and middle distillates of fossil, vegetable or animal origin, by
a suitable
measure.
Accordingly the use has been found of mixtures of
(A) aliphatic saturated or unsaturated monocarboxylic acids having 12 to
24 carbon
atoms or the dimerization or trimerization products thereof, which may be
present
in the form of free carboxylic acids and/or in the form of ammonium salts,
amides,
esters and/or nitriles, and
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(B) polycyclic hydrocarbon compounds which are obtainable from
distillation residues
of natural oils, which have been extracted from tree resins,
for increasing the cetane number of fuel oils which comprise at least one
additive
with detergent action and at least one cetane number improver, the mixtures of
components (A) and (B) being used in a concentration of 10 to 500 ppm by
weight, based on the total amount of the fuel oil.
This mixture of components (A) and (B) in fuel oils in the presence of
customary
amounts of cetane number improvers and additives with detergent action
increases the
cetane number (determined to the standard EN ISO 5165) generally by at least
1.0
unit, usually even by at least 1.5 units, compared to the fuel oil without
cetane number
improver and without additives with detergent action. The corresponding
increase in
the cetane number (determined to the standard EN ISO 5165) is generally at
least 0.5
unit compared to the fuel oil containing the same amount of cetane number
improver
and the same amount of additives with detergent action. The mixture of
components
(A) and (B), together with the cetane number improver, brings about a
synergistic
increase in the cetane number.
Mixtures of said saturated or unsaturated monocarboxylic acids having 12 to 24
carbon
atoms or the dimerization or trimerization products thereof (A) and said
polycyclic
carbon compounds (B), which are obtainable from distillation residues of
natural oils
which have been extracted from tree resins, are described in WO 2007/082825
for
improvement of the storage stability of fuel additive concentrates which
comprise at
least one detergent and at least one cetane number improver.
Component (A) in the mixtures mentioned comprises preferably aliphatic
saturated or
unsaturated monocarboxylic acids having 14 to 20 carbon atoms, especially 16
to 18
carbon atoms. These monocarboxylic acids are generally linear. Useful for
component
(A) are especially naturally occurring fatty acids, in particular those having
14 to 20
carbon atoms, especially 16 to 18 carbon atoms. Typical representatives of
such
monocarboxylic acids or fatty acids are lauric acid, myristic acid, palmitic
acid, stearic
acid, oleic acid, linoleic acid, linolenic acid and elaidic acid. Component
(A) may consist
only of one such monocarboxylic acid or fatty acid or preferably of a mixture
of two or
more such monocarboxylic acids or fatty acids. In the case of naturally
occurring fatty
acids, as obtained, for example, from rapeseed oil, soybean oil or tall oil,
these are
generally mixtures of several such monocarboxylic acids.
Component (B), which naturally originates from tree resins, especially conifer
resins
from pines or spruces, is formed from one or preferably more than one so-
called resin
acid. Resin acids are carboxyl-containing polycyclic hydrocarbon compounds.
They
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include, as the most important representatives, abietic acid, dehydroabietic
acid,
dihydroabietic acid, tetrahydroabietic acid, neoabietic acid, palustric acid,
pimaric acid,
isopimaric acid and levopimaric acid. These resin acids may partly also be
present in
oxidized form as so-called oxy acids.
In a preferred embodiment, components (A) and (B) are used in the mixtures to
be
used in accordance with the invention in a weight ratio of 65 to 99.9:0.1 to
35,
especially of 90 to 99.9:0.1 to 10, in particular of 97 to 99.9:0.1 to 3.
Particularly suitable mixtures of components (A) and (B) are those of tall oil
fatty acid
and dimerized tall oil fatty acid. Tall oil fatty acid is produced from tall
oil, which is
obtained by digestion of resin-rich wood types, especially of spruce or pine
wood. Tall
oil fatty acid is a mixture of fatty acids in which the C18-unsaturated
monocarboxylic
acids, in particular oleic acid, linoleic acid and conjugated C18 fatty acids,
and also
5,9,12-octadecatrienoic acid, predominate, resin acids and optionally oxyacids
(i.e.
oxidized fatty acids and resin acids). Resin acids are so-called tall resin,
in which
abietic acid, dehydroabietic acid and palustric acid predominate, and smaller
proportions of dihydroabietic acid, neoabietic acid, pimaric acid and
isopimaric acid can
be found as well as further resin acids. In the best tall oil fatty acid
quality, the fatty acid
content is at least 97% by weight and the tall resin content is up to 3% by
weight.
The recovery of tall oil fatty acid and resin acids from resin trees by
digestion,
extraction and distillation processes is known to those skilled it the art and
therefore
need not be explained any further here.
In dimerized tall oil fatty acid, the fatty acid component (A) is present in
dimerized form.
Dimerizations and trimerizations of monocarboxylic acids or fatty acids can be
performed by processes customary for this purpose and are known in principle
to those
skilled in the art.
The monocarboxylic acids or fatty acids and their dimerization or
trimerization products
of component (A) may be present as free carboxylic acids and/or as ammonium
salts,
for example as NH4 salts or substituted ammonium salts such as mono-, di-, tri-
or
tetramethylammonium salts, and/or in the form of amides, esters or nitriles.
Amide
structures typical thereof have the -CO-NH2, -CO-NH-alkyl or -CO-N(alkyl)2
moieties,
where "alkyl" here represents especially C1- to Ca-alkyl radicals such as
methyl or ethyl.
Ester structures typically include C1- to Ca-alkanol ester radicals such as
methyl or ethyl
ester radicals.
Additives with detergent action refer, in the context of the present invention
to those
compounds whose effect in an internal combustion engine, especially a diesel
engine,
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consists predominantly or at least essentially of eliminating and/or
preventing deposits.
The detergents are preferably amphiphilic substances which have at least one
hydrophobic hydrocarbyl radical having a number-average molecular weight (Mn)
of 85
to 20 000, especially of 300 to 5000, and in particular of 500 to 2500, and at
least one
polar moiety.
In a preferred embodiment, the fuel oils comprise at least one additive with
detergent
action which is selected from
(i) compounds with moieties derived from succinic anhydride and having
hydroxyl
and/or amino and/or amido and/or imido groups;
(ii) nitrogen compounds quaternized in an acid-free manner, obtainable by
addition
of a compound comprising at least one oxygen- or nitrogen-containing group
reactive with an anhydride and additionally at least one quaternizable amino
group onto a polycarboxylic anhydride compound and subsequent
quaternization;
(iii) polytetrahydrobenzoxazines and bistetrahydrobenzoxazines.
Additives comprising moieties deriving from succinic anhydride and having
hydroxyl
and/or amino and/or amido and/or imido groups are preferably corresponding
derivatives of polyisobutenylsuccinic anhydride, which are obtainable by
reaction of
conventional or high-reactivity polyisobutene with Mn = 300 to 5000, in
particular with
Mn = 500 to 2500, with maleic anhydride by a thermal route or via the
chlorinated
polyisobutene. Of particular interest in this context are derivatives with
aliphatic
polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine
or
tetraethylenepentamine. The moieties with hydroxyl and/or amino and/or amido
and/or
imido groups are for example carboxylic acid groups, acid amides, acid amides
of di- or
polyamines, which, as well as the amide function, also have free amine groups,
succinic acid derivatives with an acid and an amide function, carboxymides
with
monoamines, carboxymides with di- or polyamines, which, as well as the imide
function, also have free amine groups, and diimides, which are formed by the
reaction
of di- or polyamines with two succinic acid derivatives. Such fuel additives
are
described especially in US-A 4 849 572.
Nitrogen compounds quaternized in an acid-free manner according to the above
group
(ii), which are obtainable by addition of a compound which comprises at least
one
oxygen- or nitrogen-containing group reactive with an anhydride and
additionally at
least one quaternizable amino group onto a polycarboxylic anhydride compound
and
subsequent quaternization, especially with an epoxide in the absence of free
acid, are
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described in EP patent application 10 168 622.8. Suitable compounds having at
least
one oxygen- or nitrogen-containing group reactive with anhydride and
additionally at
least one quaternizable amino group are especially polyamines having at least
one
primary or secondary amino group and at least one tertiary amino group. Useful
5 polycarboxylic anhydrides are especially dicarboxylic acids such as
succinic acid,
having a relatively long-chain hydrocarbyl substituent, preferably having a
number-
average molecular weight Mn for the hydrocarbyl substituent of 200 to 10 000,
in
particular of 350 to 5000. Such a quaternized nitrogen compound is, for
example, the
reaction product, obtained at 40 C, of polyisobutenylsuccinic anhydride, in
which the
polyisobutenyl radical typically has an Mn of 1000, with 3-
(dimethylamino)propylamine,
which constitutes a polyisobutenylsuccinic monoamide and which is subsequently
quaternized with styrene oxide in the absence of free acid at 70 C.
Polytetrahydrobenzoxazines and bistetrahydrobenzoxazines according to the
above
group (iii) are described in EP patent application 10 194 307.4. Such
polytetrahydrobenzoxazines and bistetrahydrobenzoxazines are obtainable by
successively reacting, in a first reaction step, a C1- to C20-alkylenediamine
having two
primary amino functions, e.g. 1,2-ethylenediamine, with a C1- to C12-aldehyde,
e.g.
formaldehyde, and a C1- to C8-alkanol at a temperature of 20 to 80 C with
elimination
and removal of water, where both the aldehyde and the alcohol can each be used
in
more than twice the molar amount, especially in each case in 4 times the molar
amount, relative to the diamine, in a second reaction step reacting the
condensation
product thus obtained with a phenol which bears at least one long-chain
substituent
having 6 to 3000 carbon atoms, e.g. a tert-octyl, n-nonyl, n-dodecyl or
polyisobutyl
radical having an Mn of 1000, in a stoichiometric ratio relative to the
originally used
alkylenediamine of 1.2:1 to 3:1 at a temperature of 30 to 120 C and optionally
in a third
reaction step heating the bistetrahydrobenzoxazine thus obtained to a
temperature of
125 to 280 C for at least 10 minutes.
The at least one additive with detergent action used for the present invention
is more
preferably a compound from group (i), which is a polyisobutenyl-substituted
succinimide.
Cetane number improvers used are typically organic nitrates. Such organic
nitrates are
especially nitrate esters of unsubstituted or substituted aliphatic or
cycloaliphatic
alcohols, usually having up to about 10, in particular having 2 to 10 carbon
atoms. The
alkyl group in these nitrate esters may be linear or branched, and saturated
or
unsaturated. Typical examples of such nitrate esters are methyl nitrate, ethyl
nitrate,
n-propyl nitrate, isopropyl nitrate, ally' nitrate, n-butyl nitrate, isobutyl
nitrate, sec-butyl
nitrate, tert-butyl nitrate, n-amyl nitrate, isoamyl nitrate, 2-amyl nitrate,
3-amyl nitrate,
tert-amyl nitrate, n-hexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-
octyl nitrate,
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6
2-ethylhexyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate,
cyclopentyl nitrate,
cyclohexyl nitrate, methylcyclohexyl nitrate and isopropylcyclohexyl nitrate
and also
branched decyl nitrates of the formula R1R2CH-CH2-0-NO2 in which R1 is an n-
propyl
or isopropyl radical and R2 is a linear or branched alkyl radical having 5
carbon atoms,
as described in WO 2008/092809. Additionally suitable are, for example,
nitrate esters
of alkoxy-substituted aliphatic alcohols such as 2-ethoxyethyl nitrate, 2-(2-
ethoxyethoxy)ethyl nitrate, 1-methoxypropyl nitrate or 4-ethoxybutyl nitrate.
Additionally
suitable are also diol nitrates such as 1,6-hexamethylene dinitrate. Among the
cetane
number improver classes mentioned, preference is given to primary amyl
nitrates,
primary hexyl nitrates, octyl nitrates and mixtures thereof.
In one preferred embodiment, 2-ethylhexyl nitrate is present in the fuel oils
as the sole
cetane number improver or in a mixture with other cetane number improvers.
Said mixtures of the monocarboxylic acids or the dimerization or trimerization
products
thereof (A) and the polycyclic hydrocarbon compounds (B) can in principle be
used to
increase the cetane numbers in any fuel oils which comprise cetane number
improvers
and additives with detergent action. However, they are especially suitable for
use in
middle distillate fuels, especially in diesel fuels. However, use in heating
oil or kerosene
is also possible. Diesel fuels or middle distillate fuels are typically
mineral oil raffinates
which generally have a boiling range from 100 to 400 C. These are usually
distillates
having a 95% point up to 360 C or even higher. However, these may also be what
is
called "ultra low sulfur diesel" or "city diesel", characterized by a 95%
point of, for
example, not more than 345 C and a sulfur content of not more than 0.005% by
weight,
or by a 95% point of, for example, 285 C and a sulfur content of not more than
0.001%
by weight. In addition to the diesel fuels obtainable by refining, the main
constituents of
which are relatively long-chain paraffins, those obtainable by coal
gasification or gas
liquefaction ["gas to liquid" (GTL) fuels] are suitable. Also suitable are
mixtures of the
aforementioned diesel fuels with renewable fuels (biofuel oils) such as
biodiesel or
bioethanol. Of particular interest at present are diesel fuels with low sulfur
content, i.e.
with a sulfur content of less than 0.05% by weight, preferably of less than
0.02% by
weight, particularly of less than 0.005% by weight and especially of less than
0.001%
by weight of sulfur. Diesel fuels may also comprise water, for example in an
amount of
up to 20% by weight, for example in the form of diesel-water microemulsions or
in the
form of what is called "white diesel".
In a preferred embodiment, said mixtures of the monocarboxylic acids or the
dimerization or trimerization products thereof (A) and the polycyclic
hydrocarbon
compounds (B) are used together with cetane number improvers and additives
with
detergent action in fuel oils which consist
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(a) to an extent of 0.1 to 100% by weight, preferably to an extent of 0.1
to less than
100% by weight, especially to an extent of 10 to 95% by weight and in
particular
to an extent of 30 to 90% by weight, of at least one biofuel oil based on
fatty acid
esters, and
(b) to an extent of 0 to 99.9% by weight, preferably to an extent of more
than 0 to
99.9% by weight, especially to an extent of 5 to 90% by weight, and in
particular
to an extent of 10 to 70% by weight, of middle distillates of fossil origin
and/or of
vegetable and/or animal origin, which are essentially hydrocarbon mixtures and
are free of fatty acid esters.
Said mixtures of components (A) and (B) can of course also be used together
with
cetane number improvers and additives with detergent action in fuel oils which
consist
to an extent of 100% by weight of at least one biofuel oil (a), based on fatty
acid esters.
The fuel oil component (a) is usually also referred to as "biodiesel". This
preferably
comprises essentially alkyl esters of fatty acids which derive from vegetable
and/or
animal oils and/or fats. Alkyl esters typically refer to lower alkyl esters,
especially C1- to
Ca-alkyl esters, which are obtainable by transesterifying the glycerides which
occur in
vegetable and/or animal oils and/or fats, especially triglycerides, by means
of lower
alcohols, for example, ethanol, n-propanol, isopropanol, n-butanol,
isobutanol, sec-
butanol, tert-butanol or especially methanol ("FAME").
Examples of vegetable oils which can be converted to corresponding alkyl
esters and
can thus serve as the basis of biodiesel are castor oil, olive oil, peanut
oil, palm kernel
oil, coconut oil, mustard oil, cottonseed oil, and especially sunflower oil,
palm oil,
soybean oil and rapeseed oil. Further examples include oils which can be
obtained
from wheat, jute, sesame and shea tree nut; it is additionally also possible
to use
arachis oil, jatropha oil and linseed oil. The extraction of these oils and
the conversion
thereof to the alkyl esters are known from the prior art or can be inferred
therefrom.
It is also possible to convert already used vegetable oils, for example used
deep fat
fryer oil, optionally after appropriate cleaning, to alkyl esters, and thus
for them to serve
as the basis of biodiesel.
Vegetable fats can in principle likewise be used as a source for biodiesel,
but play a
minor role.
Examples of animal oils and fats which can be converted to corresponding alkyl
esters
and can thus serve as the basis of biodiesel are fish oil, bovine tallow,
porcine tallow
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8
and similar fats and oils obtained as wastes in the slaughter or utilization
of farm
animals or wild animals.
The parent saturated or unsaturated fatty acids of said vegetable and/or
animal oils
and/or fats, which usually have 12 to 22 carbon atoms and may bear an
additional
functional group such as hydroxyl groups, and which occur in the alkyl esters,
are
especially lauric acid, myristic acid, palmitic acid, stearic acid, oleic
acid, linoleic acid,
linolenic acid, elaidic acid, erucic acid and/or ricinoleic acid.
Typical lower alkyl esters based on vegetable and/or animal oils and/or fats,
which find
use as biodiesel or biodiesel components, are, for example, sunflower methyl
ester,
palm oil methyl ester ("PME"), soybean oil methyl ester ("SME") and especially
rapeseed oil methyl ester ("RME").
However, it is also possible to use the monoglycerides, diglycerides and
especially
triglycerides themselves, for example castor oil, or mixtures of such
glycerides, as
biodiesel or components for biodiesel.
In the context of the present invention, the fuel oil component (b) shall be
understood to
mean the abovementioned middle distillate fuels, especially diesel fuels,
especially
those which boil in the range from 120 to 450 C.
In a further preferred embodiment, said mixtures of the monocarboxylic acids
or the
dimerization or trimerization products thereof (A) and the polycyclic
hydrocarbon
compounds (B) are used together with cetane number improvers and additives
with
detergent action in fuel oils which have at least one of the following
properties:
(a) a sulfur content of less than 50 mg/kg (corresponding to 0.005% by
weight),
especially less than 10 mg/kg (corresponding to 0.001% by weight);
(8) a maximum content of 8% by weight of polycyclic aromatic
hydrocarbons;
(y) a 95% distillation point (vol/vol) at not more than 360 C.
Polycyclic aromatic hydrocarbons in (3) shall be understood to mean
polyaromatic
hydrocarbons according to standard EN 12916. They are determined according to
this
standard.
The fuel oils comprise said mixtures of the monocarboxylic acids or the
dimerization or
trimerization products thereof (A) and the polycyclic hydrocarbon compounds
(B) in the
context of the present invention generally in an amount of 1 to 1000 ppm by
weight,
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9
preferably of 5 to 500 ppm by weight, especially of 10 to 300 ppm by weight,
in
particular of 25 to 150 ppm by weight, for example of 40 to 100 ppm by weight.
The cetane number improver or a mixture of a plurality of cetane number
improvers is
present in the fuel oils normally in an amount of 10 to 10 000 ppm by weight,
especially
20 to 5000 ppm by weight, even more preferably of 50 to 2500 ppm by weight and
especially of 100 to 1000 ppm by weight, for example of 150 to 500 ppm by
weight.
The additive with detergent action or a mixture of a plurality of such
additives with
detergent action is present in the fuel oils, typically in an amount of 10 to
2000 ppm by
weight, especially 20 to 1000 ppm by weight, even more preferably of 50 to 500
ppm
by weight and especially of 30 to 250 ppm by weight, for example of 50 to 150
ppm by
weight.
Said fuel oils such as diesel fuels or middle distillate fuels, or such as
said mixtures of
biofuel oils and middle distillates of fossil, vegetable or animal origin, may
comprise, in
addition to the mixtures of the monocarboxylic acids or the dimerization or
trimerization
products thereof (A) and the polycyclic hydrocarbon compounds (B), the
additives with
detergent action and the cetane number improvers, as coadditives, further
customary
additive components, especially cold flow improvers, corrosion inhibitors,
demulsifiers,
dehazers, antifoams, antioxidants and stabilizers, metal deactivators,
antistats, lubricity
improvers, dyes (markers) and/or diluents and solvents.
Cold flow improvers suitable as further coadditives are, for example,
copolymers of
ethylene with at least one further unsaturated monomer, in particular ethylene-
vinyl
acetate copolymers.
Corrosion inhibitors suitable as further coadditives are, for example,
succinic esters, in
particular with polyols, fatty acid derivatives, for example oleic esters,
oligomerized
fatty acids and substituted ethanolamines.
Demulsifiers suitable as further coadditives are, for example, the alkali
metal and
alkaline earth metal salts of alkyl-substituted phenol- and
naphthalenesulfonates and
the alkali metal and alkaline earth metal salts of fatty acid, and also
alcohol alkoxylates,
e.g. alcohol ethoxylates, phenol alkoxylates, e.g. tert-butylphenol
ethoxylates or tert-
pentylphenol ethoxylates, fatty acid, alkylphenols, condensation products of
ethylene
oxide and propylene oxide, e.g. ethylene oxide-propylene oxide block
copolymers,
polyethyleneimines and polysiloxanes.
Dehazers suitable as further coadditives are, for example, alkoxylated phenol-
formaldehyde condensates.
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Antifoams suitable as further coadditives are, for example, polyether-modified
polysiloxanes.
Antioxidants suitable as further coadditives are, for example, substituted
phenols, e.g.
5 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-3-methylphenol, and also
phenylenediamines, e.g. N,N'-di-sec-butyl-p-phenylenediamine.
Metal deactivators suitable as further coadditives are, for example, salicylic
acid
derivatives, e.g. N,N'-disalicylidene-1,2-propanediarnine.
A lubricity improver suitable as a further coadditive is, for example,
glyceryl
monooleate.
Suitable solvents, especially for diesel performance packages, are, for
example,
nonpolar organic solvents, especially aromatic and aliphatic hydrocarbons, for
example
toluene, xylenes, "white spirit" and the technical solvent mixtures of the
designations
Shellsol (manufacturer: Royal Dutch/Shell Group), Exxol (manufacturer:
ExxonMobil) and Solvent Naphtha. Also useful here, especially in a blend with
the
nonpolar organic solvents mentioned, are polar organic solvents, in particular
alcohols
such as 2-ethylhexanol, decanol and isotridecanol.
When the coadditives and/or solvents mentioned are used additionally, they are
used
in the amounts customary therefor.
The examples which follow are intended to illustrate the present invention
without
restricting it.
Examples
In a diesel fuel which is typical for the European market, conforms to
standard EN 590
and comprised a proportion of 7% by weight of biodiesel (FAME), the cetane
numbers
were determined to EN ISO 5165 with the following additions:
Sample No. Dosage [ppm by weight] Cetane number to EN ISO 5165
1 none (base fuel) 51.9
2 65 PIBSI *
0 2-ethylhexyl nitrate
60 tall oil fatty acid
CA 02819057 2013-05-27
. .
11
110 Solvent Naphtha heavy
Tot. 5 customary antifoam + customary
dehazer 52.1
3 65 PIBSI *
360 2-ethylhexyl nitrate
0 tall oil fatty acid
110 Solvent Naphtha heavy
Tot. 5 customary antifoam + customary
dehazer 52.9
4 65 PIBSI *
360 2-ethylhexyl nitrate
60 tall oil fatty acid
110 Solvent Naphtha heavy
Tot. 5 customary antifoam + customary
dehazer 53.6
* commercial polyisobutenyl-substituted succinimide (Kerocom PIBSI from BASF
SE)
As evident from the above results, the addition of tall oil fatty acid to a
fuel which
comprises an additive with detergent action but no cetane number improver does
not
lead to any significant change in the cetane number (sample No. 2).
The addition of cetane number improver to a fuel which comprises an additive
with
detergent action but no tall oil fatty acid leads to an increase in the cetane
number of
1.0 compared to the unadditized base fuel (sample No. 3). When, in contrast,
both tall
oil fatty acid and cetane number improver are added to the fuel which
comprises an
additive with detergent action, there is a surprisingly large increase in the
cetane
number by 1.7 units compared to the unadditized base fuel to 53.6 (sample No.
4).
This demonstrates the synergistic action of the mixture of components (A) and
(B),
represented by tall oil fatty acid, and cetane number improvers from the
increase in the
cetane number.
