Note: Descriptions are shown in the official language in which they were submitted.
CA 02810284 2014-11-06
GASOLINE FUEL ADDITIVES HAVING DETERGENT ACTION OR VALVE
SEAT WEAR-INHIBITING ACTION
This application is a divisional application of co-pending application Serial
No. 2,520,578, filed April 8, 2004.
The present invention relates to a fuel composition comprising a major amount
of a
specific lower alkanol-containing gasoline fuel and a minor amount of selected
gasoline
fuel additives.
Carburetors and intake systems of gasoline engines, and also injection systems
for fuel
metering, are contaminated to an increasing degree by impurities which are
caused by
dust particles from the air, uncombusted hydrocarbon residues from the
combustion
chamber and the crankcase vent gases conducted into the carburetor.
These residues shift the air-fuel ratio when idling and in the lower partial
load range, so
that the mixture becomes leaner, the combustion more incomplete and in turn
the
proportions of uncombusted or partially combusted hydrocarbons in the exhaust
gas
become higher and the gasoline consumption increases.
It is known that these disadvantages can be prevented by using fuel additives
to keep
valves and carburetors or injection systems of gasoline engines clean (cf.,
for example:
M. Rossenbeck in Katalysatoren, Tenside, Mineraldadditive [Catalysts,
surfactants,
mineral oil additives], Eds.: J. Falbe, U. Hasserodt, p. 223, G. Thieme
Verlag, Stuttgart
1978).
Moreover, in gasoline engines of older design, the problem of valve seat wear
occurs
on operation with lead-free gasoline fuels. To counteract this, valve seat
wear-inhibiting
additives have been developed which are based on alkali metal or alkaline
earth metal
compounds.
For trouble-free use, modern gasoline engines require fuels having a complex
profile of
properties which can only be ensured in combination with appropriate gasoline
fuel
additives. Such gasoline fuels generally consist of a complex mixture of
chemical
compounds and are characterized by physical quantities. However, the interplay
between gasoline fuels and appropriate additives is still in need of
improvement in the
known fuel compositions with regard to the action of cleaning and keeping
clean, and
the valve seat wear-inhibiting action.
It is an object of the present invention to find a more effective gasoline
fuel-gasoline
fuel additive composition. In particular, the intention is to find more
effective additive
formulations.
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=
We have found that this object is achieved by a fuel composition which
comprises a
major amount of a gasoline fuel having a maximum sulfur content of 150 ppm by
weight and a minor amount of at least one gasoline fuel additive having
detergent
action or having a valve seat wear-inhibiting action, wherein this gasoline
fuel additive
has at least one hydrophobic hydrocarbon radical having a number-average
molecular
weight (MN) of from 85 to 20 000 and at least one polar moiety, and wherein
the fuel
composition also has a content of at least one lower alkanol of from about 5
to 75% by
volume.
The polar moiety is selected from:
(a) mono- or polyamino groups having up to 6 nitrogen atoms, of which at
least one
nitrogen atom has basic properties,
(b) nitro groups, if appropriate in combination with hydroxyl groups,
(c) hydroxyl groups in combination with mono- or polyamino groups, in
which at least
one nitrogen atom has basic properties,
(d) carboxyl groups or the.r alkali metal or their alkaline earth metal
salts,
(e) sulfonic acid groups or their alkali metal or alkaline earth metal
salts,
(f) polyoxy-C2- to -C4-alkylene groups which are terminated by hydroxyl
groups,
mono- or polyamino groups, in which at least one nitrogen atom has basic
properties,
or by carbamate groups,
(g) carboxylic ester groups,
(h) moieties derived from succinic anhydride and having hydroxyl and/or amino
and/or amino and/or imido groups and
(i) moieties obtained by IVIannich reaction of substituted phenols with
aldehydes and
mono- or polyamines.
The alkanol used in accordance with the invention is preferably a straight-
chain or
branched, saturated C1-C6-mono- or ¨diol, in particular a C1¨C3-mono alkanol,
such as
methanol, ethanol, n- or i-propanol, or a mixture of a plurality of these
alkanols.
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The alkanol content, based on the total volume of the fuel composition, is a
maximum
of 75% by volume, for example from 5 to 75% by volume, preferably from 10 to
65% by
volume, in particular from 20 to 55% by volume, for example 30 ¨ 40% by volume
or
40 ¨ 50% by volume.
The content of further alcohols and ethers in the gasoline fuel is normally
relatively low.
Typical maximum contents are 7% by volume for tert-butanol, 10% by volume for
isobutanol and 15% by volume for ethers having 5 or more carbon atoms in the
molecule.
The maximum aromatics content of the gasoline fuel is preferably 40% by
volume, in
particular 38% by volume. Preferred ranges for the aromatics content are from
20 to
42% by volume, in particular from 25 to 40% by volume.
The maximum sulfur content of the gasoline fuel is preferably 100 ppm by
weight, in
particular 50 ppm by weight. Preferred ranges for the sulfur content are from
0.5 to
150 ppm by weight, in particular from 1 to 100 ppm by weight.
In a preferred embodiment, the gasoline fuel has a maximum olefin content of
21% by
volume, preferably 18% by volume, in particular 10% by volume. Preferred
ranges for
the olefin content are from 6 to 21% by volume, in particular from 7 to 18% by
volume.
In a further preferred embodiment, the gasoline fuel has a maximum benzene
content
of 1.0% by volume, in particular 0.9% by volume, Preferred ranges for the
benzene
content are from 0.5 to 1.0% by volume, in particular from 0.6 to 0.9% by
volume.
In a further preferred embodiment, the oxygen content of the gasoline fuel is
a
maximum of 2.7% by weight, and is preferably from 0.1 to 2.7% by weight, in
particular
from 1.0 to 2.7% by weight, especially from 1.2 to 2.0% by weight.
Particular preference is given to a gasoline fuel which at the same time has a
maximum
aromatics content of 38% by volume, a maximum olefin content of 21% by volume,
a
maximum sulfur content of 50 ppm by weight, a maximum benzene content of 1.0%
by
volume and an oxygen content of from 1.0 to 2.7% by weight.
The above percentages by volume for all of them, benzene, aromatics and oxygen
content are each based on the volume of the mineral gasoline fuel component,
i.e.
without additives and without alkanol.
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The summer vapor pressure of the gasoline fuel is typically a maximum of 70
kPa, in
particular 60 kPa (each at 370C).
The research octane number ("RON") of the gasoline fuel is generally from 90
to 100. A
typical range for the corresponding motor octane number ("MON") is from 80 to
90.
The specifications mentioned are determined by customary methods (DIN EN 228).
The hydrophobic hydrocarbon radical in the gasoline fuel additives, which
ensures
sufficient solubility in the fuel, has a number-average molecular weight (Mn)
of from 85
to 20 000, especially from 113 to 10 000, in particular from 300 to 5 000.
Typical
hydrophobic hydrocarbon radicals which can be used, in particular in
conjunction with
the polar moieties (a), (c), (h) and (i) are the polypropenyl, polybutenyl and
polyisobutenyl radical each having Mn = from 300 to 5 000, especially from 500
to
2 500, in particular from 750 to 2 250.
Individual gasoline fuel additives having detergent action or having valve
seat wear-
inhibiting action include the following:
Additives comprising mono- or polyamino groups (a) are preferably
polyalkenemono- or
polyalkenepolyamines based on polypropene or on highly reactive (i.e. having
predominantly terminal double bonds, usually in the alpha- and beta-position)
or
conventional (i.e. having predominantly internal double bonds) polybutene or
polyisobutene having Mn = from 300 to 5000. Such additives based on highly
reactive
polyisobutene, which can be prepared from the polyisobutene which may comprise
up
to 20% by weight of n-butene units by hydroformylation and reductive amination
with
ammonia, monoamines or polyamines, such as dimethylaminopropylamine,
ethylenediamine, diethylenetriamine, triethylenetetramine or
tetraethylenepentamine,
are disclosed in particular in EP-A 244 616. When polybutene or polyisobutene
having
predominantly intemal double bonds (usually in the beta and gamma position)
are used
as starting materials in the preparation of the additives, a possible
preparative route is
by chlorination and subsequent amination or by oxidation of the double bond
with air or
ozone to give the carbonyl or carboxyl compound and subsequent amination under
reductive (hydrogenating) conditions. The amines used here for the amination
may be
the same as those used above for the reductive amination of the
hydroformylated
highly reactive polyisobutene. Corresponding additives based on polypropene
are
described in particular in WO-A 94/24231.
Further preferred additives containing monoamino groups (a) are the
hydrogenation
= 40 products of the reaction products of polyisobutenes having an
average degree of
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polymerization P = from 5 to 100 with nitrogen oxides or mixtures of nitrogen
oxides
and oxygen, as described in particular in WO-A 97/03946.
Further preferred additives comprising monoamino groups (a) are the compounds
obtainable from polyisobutene epoxides by reaction with amines and subsequent
dehydration and reduction of the amino alcohols, as described in particular in
DE-A 196 20 262.
Additives comprising nitro groups, if appropriate in combination with hydroxyl
groups,
(b) are preferably reaction products of polyisobutenes having an average
degree of
polymerization P = from 5 to 100 or from 10 to 100 with nitrogen oxides or
mixtures of
nitrogen oxides and oxygen, as described in particular in WO-A 96/03367 and
WO-A 96/03479. These reaction products are generally mixtures of pure
nitropoly-
isobutanes (e.g. alpha, beta-dinitropolyisobutane) and mixed hydroxynitropoly-
isobutanes (e.g. alpha-nitro-beta-hydroxypolyisobutane).
Additives comprising hydroxyl groups in combination with mono- or polyamino
groups
(c) are in particular reaction products of polyisobutene epoxides obtainable
from
polyisobutene having preferably predominantly terminal double bonds and Mn
from 300
to 5 000, with ammonia or mono- or polyamines, as described in particular in
EP-A
476 485.
Additives comprising carboxyl groups or their alkali metal or alkaline earth
metal salts
(d) are preferably copolymers of C2-C40-olefins with maleic anhydride which
have a
total molar mass of from 500 to 20 000 and of whose carboxyl groups some or
all have
been converted to the alkali metal or alkaline earth metal salts and any
remainder of
the carboxyl groups has been reacted with alcohols or amines. Such additives
are
disclosed in particular by EP-A 307 815. Such additives serve mainly to
prevent valve
seat wear and can, as described in WO-A 87/01126, advantageously be used in
combination with customary fuel detergents such as poly(iso)butenamines or
polyetheramines.
Additives comprising sulfonic acid groups or their alkali metal or alkaline
earth metal
salts (e) are preferably alkali metal or alkaline earth metal salts of an
alkyl
sulfosuccinate, as described in particular in EP-A 639 632. Such additives
serve mainly
to prevent valve seat wear and can be used advantageously in combination with
customary fuel detergents such as poly(iso)butenamines or polyetheramines.
Additives comprising polyoxy-C2- to Ccalkylene moieties (f) are preferably
polyethers
or polyetheramines which are obtainable by reaction of C2- to Caralkanols, Cs-
to C30-
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alkanediols, mono- or di-C2-C30-alkylamines, C1-C30-alkylcyclohexanols or C1-
C30-
alkylphenols with from 1 to 30 mot of ethylene oxide and/or propylene oxide
and/or
butylene oxide per hydroxyl group or amino group and, in the case of the
polyetheramines, by subsequent reductive amination with ammonia, monoamines or
polyamines. Such products are described in particular in EP-A 310 875, EP-A
356 725,
EP-A 700 985 and US-A 4 877 416. In the case of polyethers, such products also
have
carrier oil properties. Typical examples of these are tridecanol butoxylates,
isotridecanol butoxylates, isononylphenol butoxylates and polyisobutenol
butoxylates
and propoxylates and also the corresponding reaction products with ammonia.
Additives comprising carboxylic ester groups (g) are preferably esters of mono-
, di- or
tricarboxylic acids with long-chain alkanols or polyols, in particular those
having a
minimum viscosity of 2 mm2/s at 100 C, as described in particular in DE-A 38
38 918.
The mono-, di- or tricarboxylic acids used may be aliphatic or aromatic acids,
and
particularly suitable ester alcohols or ester polyols are long-chain
representatives
having, for example, from 6 to 24 carbon atoms. Typical representatives of the
esters
are adipates, phthalates, isophthalates, terephthalates and trimellitates of
isooctanol, of
isononanol, of isodecanol and of isotridecanol. Such products also have
carrier oil
properties.
Additives comprising moieties derived from succinic anhydride and having
hydroxyl
and/or amino and/or amido and/or imido groups (h) are preferably corresponding
derivatives of polyisobutenylsuccinic anhydride which are obtainable by
reacting
conventional or highly reactive polyisobutene having Mn = from 300 to 5 000
with
maleic anhydride by a thermal route or via the chlorinated polyisobutene.
Particular
interest attaches to derivatives with aliphatic polyamines such as
ethylenediamine,
diethylenetriamine, triethylenetetramine or tetraethylenepentamine. Such
gasoline fuel
additives are described in particular in US-A 4 849 572.
Additives comprising moieties obtained by Mannich reaction of substituted
phenols with
aldehydes and mono- or polyamines (i) are preferably reaction products of
polyisobutene-substituted phenols with formaldehyde and mono- or polyamines
such
as ethylenediamine, diethylenetriamine, triethylenetetramine,
tetraethylenepentamine
or dimethylaminopropylamine, The polyisobutenyl-substituted phenols may stem
from
conventional or highly reactive polyisobutene having Mn = from 300 to 5 000.
Such
"polyisobutene-Mannich bases" are described in particular in EP-A 831 141.
For a more precise definition of the gasoline fuel additives detailed
individually,
reference is explicitly made here to the disclosures of the abovementioned
prior art
documents.
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The fuel composition according to the invention may additionally comprise
further
customary components and additives. These include primarily carrier oils
without
marked detergent action, for example mineral carrier oils (base oils), in
particular those
of the viscosity class "Solvent Neutral (SN) 500 to 2 000", and synthetic
carrier oils
based on olefin polymers having Mn = from 400 to 1800, in particular based on
polybutene or polyisobutene (hydrogenated or nonhydrogenated), on poly-alpha-
olefins
or poly(internal olefin)s.
Useful solvents or diluents (when providing additive packages) are aliphatic
and
aromatic hydrocarbons such as Solvent Naphtha.
Further customary additives are corrosion inhibitors, for example based on
ammonium
salts of organic carboxylic acids, said salts tending to form films, or of
heterocyclic
aromatics for nonferrous metal corrosion protection, antioxidants or
stabilizers, for
example based on amines such as p-phenylenediamine, dicyclohexylamine or
derivatives thereof or of phenols such as 2,4-di-tert-butylphenol or 3,5-di-
tert-butyl-4-
hydroxyphenylpropionic acid, demulsifiers, antistats, metallocenes such as
ferrocene or
methylcyclopentadienylmanganese tricarbonyl, lubricity additives such as
certain fatty
acids, alkenylsuccinic esters, bis(hydroxyalkyl) fatty amines,
hydroxyacetamides or
castor oil and also markers. Amines are also optionally added to lower the pH
of the
fuel.
Also useful for the fuel composition according to the invention are in
particular
combinations of the gasoline fuel described with a mixture of gasoline fuel
additives
having the polar moiety (f) and corrosion inhibitors and/or lubricity
additives based on
carboxylic acids or fatty acids which may be present as monomeric and/or
dimeric
species. Typical mixtures of this type comprise polyisobutanamines in
combination
with alkanol-started polyethers such as tridecanol or isotridecanol
butoxylates or
ropoxylates, polyisobutenamines in combination with alkanol-started
polyetheramines
such as tridecanol or isotridecanol butoxylate-ammonia reaction products and
alkanol-
started polyetheramines such as tridecanol or isotridecanol butoxylate
reaction
products in combination with alkanol-started polyethers such as tridecanol or
isotridecanol butoxylates or propoxylates, used together with the corrosion
inhibitors
and/or lubricity additives mentioned.
The gasoline fuel additives having the polar moieties (a) to (i) mentioned,
and also the
other components mentioned, are metered into the gasoline fuel and exhibit
their action
there. The components and/or additives may be added to the fuel individually
or as a
concentrate prepared beforehand ("additive package").
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The gasoline fuel additives having the polar moieties (a) to (i) mentioned are
added to
the gasoline fuel typically in an amount of from 1 to 5 000 ppm by weight,
especially
from 5 to 3 000 ppm by weight, in particular from 10 to 1 000 ppm by weight.
The other
components and additives mentioned are, if desired, added in amounts customary
for
this purpose.
In the fuel composition according to the invention, it is surprisingly
possible with
distinctly less detergent or valve seat wear inhibitor to achieve the same
action of
cleaning or keeping clean, or valve seat wear-inhibiting action as for
comparable fuel
compositions without lower alkanol addition. Moreover, the use of the same
amounts of
detergent or valve seat wear inhibitor in the fuel composition according to
the invention,
compared to conventional fuel compositions, surprisingly results in a
distinctly better
action of cleaning or keeping clean, and valve seat wear-inhibiting action.
In addition, the fuel composition according to the invention additionally
exhibits
advantages to the effect that fewer deposits are formed in the combustion
chamber of
the gasoline engine and that less additive is entrained into the engine oil
via the fuel
dilution.
The invention further relates to
i) the use of a lower alkanol in low-sulfur gasoline fuels to improve the
action of an
additive having detergent action or having valve seat wear-inhibiting action
as defined
above;
ii) a process for improving the additive action of an additive having
detergent action or
having valve seat wear-inhibiting action as defined above in low-sulfur
gasoline fuels,
by admixing the gasoline fuel with an effective amount of a lower alcohol;
iii) the use of a combination of lower alcohol and at least one additive
having detergent
action or having valve seat wear-inhibiting action as defined above to reduce
combustion chamber deposits and/or to reduce deposits in the intake system of
a
gasoline engine;
iv) the use of a combination of lower alcohol and additive having valve seat
wear-
inhibiting action as defined above as a valve seat wear-inhibitor for gasoline
fuels.
The examples which follow are intended to illustrate the invention without
restricting it.
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Examples:
The gasoline fuel additive used was a commercial additive package comprising
60% by
weight of detergent additive, polyisobutenamine (Mn = 1 000 g/mol), and 32% by
weight of carrier oil (tridecanol etherified with 22 units of butylene oxide).
The gasoline fuels used were those listed below with the particular
specification stated,
and GF 1 (parameters see Table 1) is a typical commercially available fuel.
Table 1
Specification GF 1
Aromatics content
[% by vol.] 39.8
Paraffin content
[cY0 by vol.] 47.7
Olefin content
[% by vol.] 12.5
Sulfur content
[ppm by weight] 35
Density 743.6
[15 C] [kg/m3]
Initial boiling point 34.5 C
10 % volume 50 C
50 % volume 85 C
90 % volume 150.5 C
Final boiling point 189.0 C
GF 2 = GF 1 + 10% by vol. of Et0H
GF 3 = GF 1 + 50% by vol. of Et0H
Preparation of the fuel compositions
Example 1 (comparative experiment)
150 or 200 mg of additive package were dissolved in 1 kg of GF 1 according to
Table
1.
Example 2 (inventive)
Example 1 was repeated except that GF 2 was used instead of GF 1.
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Example 3 (inventive)
Example 1 was repeated except that GF 3 was used instead of GF 1
Performance investigations
Example 4
Gasoline fuels according to Examples 1 to 3 were investigated for their
influence on the
intake valve deposits (IVD) and on the total combustion deposits (TCD). This
was
effected with the aid of engine tests which were carried out in test rig
experiments with
a Mercedes-Benz engine M102 E according to CEC F-05-A-93. The IVD values for
additized and nonadditized fuels are compiled in the following Table 2.
In addition, the amount of total combustion deposits (TCD) was determined in
the same
experimental series for each of the four cylinders of the engine. The
particular average
value is likewise quoted in Table 2. To determine the TCD value, the procedure
was
similar to the method CEC F-20-A-98.
Table 2
Fuel GF 1 GF 2 GF 3
Amount of additive
[mg/kg] 0 150 200 0 150 200 0 150 200
IVD
[mg/valve] 269 85 23 293 98 15 239 31 3
TCD =
[mg/cylinder] 1778 1864 1807 1677 1668 1713 1056 1248 764
1) Intake Valve Deposits
2) Total Combustion Deposits
As is evident from Table 2, the admixing of relatively large amounts of
ethanol (i.e.
> 10%) to the gasoline fuel results in surprisingly little formation of valve
or combustion
chamber (cylinder) deposits being observed.
