Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TS 7020
FUEL COMPOSITIONS
This invention relates to fuel compositions
containing furan derivatives, a method of operating an
internal combustion engine using such fuel compositions
and to fuel additive concentrates.
It is well known in the art that internal
combustion engines, more particularly spark ignition
engines, tend to exhibit what is termed the octane
requirement increase effect. This effect may be
described as the tendency for an initially new or
relatively clean engine to require higher octane
quality fuel as operating time accumulates, and is
coincidental with the formation of deposits in the
region of the combustion chamber of the engine.
During initial operation of a new or clean engine,
a gradual increase in octane requirement, i.e. fuel
octane number required for knock-free operation, is
observed with an increasing build up of combustion
chamber deposits until a stable or equilibrium octane
requirement level is reached. This level appears to
correspond to a point in time when the quantity of
deposit accumulation on the combustion chamber and
valve surfaces no longer increases but remains
relatively constant. This so-called "equilibrium
value" is normally reached between 3,000 and 20,000
miles (4,000 and 32,000 km) or corresponding hours of
operation. The actual equilibrium value of this
increase can vary with engine design and even with
individual engines of the same design; however, in
almost all cases, the increase appears 'o be
significant, with octane requirement increase values
ranging from about 2 to 14 research octane numbers
being commonly observed in modern engines.
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Fuel additives which inhibit or prevent deposit
formation in the combustion chamber may be termed
octane requirement increase control (ORIC) agents;
those which remove or modify formed deposits, leading
to decrease in octane requirements, may be termed
octane requirement reduction (ORR) agents.
US Patent No. 4,339,245 discloses the use of
certain furyl compounds including furfuryl alcohol,
furfuryl amine, ethylfurfurylacrylate, furfuryl
acetate, furfuryl propionate, furfuryl isobutyrate,
methyl furoate, ethyl furoate and compounds having
alkyl groups substituted on the furyl rings as
antiknock additives in gasoline. Addition of the furyl
compounds described increased the RON (research octane
number) of the gasoline. The RON is an intrinsic
property of a gasoline, and is independent of any ORIC
or ORR effect which that gasoline might, or might not,
manifest in use. No ORIC or ORR activity is either
described or hinted at in US Patent No. 4,339,245.
EP-A-174 123 discloses a process for the
preparation of alkylfurans, and acknowledges that
alkylfurans may be included in gasoline compositions as
octane improving additives. As above, this relates to
the RON of the gasoline, and not to any ORIC or ORR
effect.
It has now surprisingly been found that fuel
compositions containing certain furan derivatives
exhibit octane requirement increase control and/or
octane requirement reduction effects.
According to the present invention there is
provided a fuel composition which comprises a major
amount of a fuel boiling in the gasoline boiling range
and a minor amount of an additive comprising a furan
derivative containing a furyl group bearing one or more
substituents comprising one or more heterocyclic and/or
one or more aryl groups.
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The or each heterocyclic group may be any
optionally substituted saturated or unsaturated ring
system, e.g. a 5 to 7 membered ring system, containing
at least one heteroatom selected from oxygen, nitrogen
and sulphur, 5- and 6-membered rings being preferred,
e.g. a furyl, piperidinyl, pyridinyl, pyrrolyl,
triazinyl, imidazolinyl or thiophenyl(thienyl) group.
Especially preferred are 5-membered ring systems
containing oxygen and/or nitrogen, preferably a furan
or pyrrole ring.
The aryl group(s) may be any optionally substituted
aryl group, preferably an optionally-substituted phenyl
group. Preferred aryl groups are phenyl groups which
are unsubstituted or substituted by an alkyl group.
Thus it is preferred that the heterocyclic and/or
aryl groups comprise unsaturated 5-membered ring
systems containing oxygen and/or nitrogen, or benzene
ring systems.
Examples of substituent groups for both the
heterocyclic and aryl groups include halogen atoms
(e.g. chlorine atoms), nitro, hydroxyl, carboxyl,
amino, cyano, alkyl, formyl, alkoxycarbonyl, alkanoyl,
alkylthio, alkylsulphinyl, alkylsulphonyl, carbamoyl
and alkylamido groups. As used herein, when a
substituent consists of or contains an alkyl, alkoxy or
alkylene moiety, this may be linear or branched and may
contain up to 12, preferably up to 6, especially up to
4, carbon atoms.
The or each heterocyclic group and/or aryl group is
connected to the furyl group directly or by means of a
bridging optionally substituted hydrocarbyl (preferably
alkylene), carbonyl, dicarbonyl, amido, alkyleneamido,
alkyleneoxyalkyl or alkoxycarbonyl group. One or more
additional heterocyclic and aryl groups may also be
connected to a heterocyclic or aryl group which is
connected to the furyl group, directly or via such a
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bridging group.
Preferably connections between furyl groups and
heterocyclic or aryl groups as defined above or between
heterocyclic or aryl groups and additional heterocyclic
S or aryl group are either direct connections or are
bridging groups selected from C1_4 alkylene (preferably
-CH2-), -CH2NHCO-, -NHCO-, -CO-CO-, -CH2-O-CO- and
-CH2OCH2- groups.
Preferably the furyl group bears a single
substituent which comprises one or more heterocyclic
and/or one or more aryl groups.
For example, the number of heterocyclic and/or aryl
groups present in addition in the furyl group may
advantageously range from 1 to 5, preferably from 1 to
4.
The molecular weight of the furan derivative is
preferably in the range from 100 to 5000, more
preferably in the range 100 to 500 and most preferably
145 to 500. When the furan derivative is a single
compound having a discrete chemical structure, the
molecular weight corresponds to the formula weight of
the compound. When, however, the furan derivative has
a range of structures, the molecular weight is number
average molecular weight, as determined by gel
permeation chromatography (GPC), using polystyrene
calibration standards.
By way of example, suitable furan derivatives to be
used in accordance with the present invention include
those having the following general formula:
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,~ R3 tl)
wherein R1, R2, R3 and R4 each independently represent
hydrogen, a heterocyclic group or an aryl group
connected to the furyl group directly or by means of a
bridging group as defined hereinbefore provided that at
least one of R1, R2, R3 and R4 is such a heterocyclic
group or an aryl group. Preferably, one or both of R3
1 and R4 represent an optionally substituted saturated or
unsaturated ring system containing at least one
heteroatom selected from oxygen, nitrogen and sulphur,
connected to the furyl group as defined above.
A particularly preferred furan derivative for use
in fuel compositions of the present invention is a
furfuryl alcohol resin or a derivative thereof.
In the context of the present invention a furfuryl
alcohol resin is defined as a polymer product obtained
by condensation of optionally substituted furfuryl
2 alcohol monomers (e.g. 2-furanmethanol monomers), or a
distillation product thereof containing at least two
furan rings. Preferably, the furfuryl alcohol resin
has a number average molecular weight in the range of
145 (i.e. from about 150) to 5000, more preferably in
the range of from 145 (about 150) to 500, as measured
by gel permeation chromatography (GPC) using
polystyrene calibration standards.
It will be understood that the furfuryl alcohol
resin or derivative thereof comprises in addition to
the furyl group a number of further furyl groups which
are connected to the neighbouring furyl groups by means
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of an optionally substituted hydrocarbyl (preferably
alkylene), alkyleneoxyalkyl or alkoxycarbyl group, e.g.
a -CH2- or -CH2-O-CH2- group.
Preferably, the furfuryl alcohol resin comprises
the condensation product of non-substituted 2-
furanmethanol monomers.
It will be understood that in the latter
condensation product the additional furyl groups are
connected to the neighbouring furyl groups by means of
a methylene group, or in some cases a -CH2-O-CH2-
group.
The preparation of furfuryl alcohol resins is well
known in the art. In this respect reference is for
instance made to Journal of Applied Polymer Science,
Vol. 15, pp. 1079-1090 (1971), which document is hereby
incorporated by reference.
Suitable monomers include those having the
following general formula:
R3~ OH ( 11 )
R1 R2 R5
wherein Rl, R2, R4 and R5 each independently represent
hydrogen, a hydrocarbyl group, a nitrogen-containing,
an oxygen-containing or a sulphur-containing
hydrocarbyl group and R3 represents hydrogen. The
hydrocarbyl group may conveniently comprise an aryl,
alkyl, alkenyl or cycloalkyl group. Advantageously, the
hydrocarbyl group contains 2 to 50 carbon atoms,
preferably 2 to 20 carbon atoms and more preferably 2
to 10 carbon atoms.
Suitable furfuryl alcohol resins or derivatives
thereof include those obtained by polycondensation of
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different types of monomers (II).
Suitably the furfuryl alcohol resins or derivatives
thereof to be applied in accordance with the present
invention include those having the following general
formulae (III) or (IV):
Rl ~I 5R1A;2 5 1A.~ P5
R3~R2 R~4 R6 (IV)
wherein R1, R2, R3, R4 and Rs have the meanings as
defined hereinabove for formula II, R6 represents
hydrogen, OH,
--X--R7 ~R7 ~j R7
~R7 or ~[CH2 ICH~] p R8,
and R7 and R8 represent an optionally nitrogen-
containing, oxygen-containing or sulphur-containing
hydrocarbyl group, x is in the range from 0 to 60,
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preferably from 0 to 30 and more preferably from 0 to
10, y is 0 or 1, z is in the range from 0 to 60,
preferably from 0 to 30 and more preferably from 0 to
10, each of (x + z) and Z' ranges from 1 to 60,
preferably 1 to 30 and more preferably from 1 to 10,
and p is in the range from 1 to 80, preferably ranging
from 5 to 25.
It will be understood that the furfuryl alcohol
resin or derivatives thereof will usually comprise a
mixture of any of the polymer products III and IV
described above, and of course any unreacted 2-furan-
methanol or derivative thereof.
The furfuryl alcohol resins may contain unreacted
hydroxy groups which may subsequently be derivatised,
e.g. esterified, in known manner. A preferred
derivative is an alkylsuccinic acid ester of a furfuryl
resin, which may be prepared by reaction of the
furfuryl resin with an olefin-succinic anhydride, e.g.
a C1s_1g internal olefin-succinic anhydride.
A particularly preferred fuel composition according
to the present invention is one wherein the furan
derivative is selected from the group consisting of N-
furfuryl-2-furamide, 2-amino-1-(2-furanylmethyl)-4,5-
difuryl-3-pyrrolecarbonitrile, N-phenyl furamide, 1-
furfurylpyrrole, furil, furfuryl benzoate, furfuryl
resins having number average molecular weights in the
range 145 to 500 and alkylsuccinic acid esters of
furfuryl resins having number average molecular weights
in said range.
The additive comprising the furan derivative is
preferably present in the fuel composition in an octane
requirement reducing amount.
The fuel is present in a major amount (i.e. more
than 50%w), and the additive comprising the furan
derivative is present in a minor amount, preferably
from 0.005 to 10%w, more preferably from 0.01 to 5%w,
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_ g
and most preferably from 0.02 to 1%w, based on the
weight of the fuel composition.
The invention further provides an additive
concentrate suitable for addition to fuel for an
internal combustion engine which comprises a fuel-
compatible diluent and an additive comprising a furan
derivative as defined above, preferably in an amount of
from 5 to 75%w calculated on the diluent.
Further in accordance with the present invention
there is provided a method of operating an internal
combustion engine which comprises introducing into the
combustion chambers of said engine a fuel composition
as defined above according to the invention.
The fuel boiling in the gasoline boiling range may
consist substantially of hydrocarbons or it may contain
blending components. Alternatively, e.g. in countries
such as Brazil, the fuel may consist substantially of
ethanol.
Suitable liquid hydrocarbon fuels of the gasoline
boiling range are mixtures of hydrocarbon boiling in
the temperature range from about 25~C to about 232~C,
and comprise mixtures of saturated hydrocarbons,
olefinic hydrocarbons and aromatic hydrocarbons.
Preferred are gasoline mixtures having a saturated
hydrocarbon content ranging from about 40% to about 80%
by volume, an olefinic hydrocarbon content from 0% to
about 30% by volume and an aromatic hydrocarbon content
from about 10% to about 60% by volume. The base fuel
is derived from straight run gasoline, polymer
gasoline, natural gasoline, dimer and trimerized
olefins, synthetically produced aromatic hydrocarbon
mixtures, from thermally or catalytically reformed
hydrocarbons, or from catalytically cracked or
thermally cracked petroleum stocks, and mixtures of
these. The hydrocarbon composition and octane level of
the base fuel are not critical. The octane level,
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(R+M)/2, will generally be above about 85 (where R is
Research Octane Number and M is Motor Octane Number).
Any conventional base gasoline can be employed in
the practice of the present invention. For example,
hydrocarbons in the gasoline can be replaced by up to a
substantial amount of conventional alcohols or ethers,
conventionally known for use in fuels. The base
gasolines are desirably substantially free of water
since water could impede a smooth combustion.
Normally, the gasolines to which the invention is
applied may be leaded or unleaded, although are
preferably substantially lead-free, and may contain
minor amounts of one or more blending agents such as
methanol, ethanol, tertiary butanol, ethyl tertiary
butyl ether, methyl tertiary butyl ether, and the like,
at from about 0.1% by volume to about 25% by volume of
the base fuel, although larger amounts (e.g. up to
40%v) may be utilised.
The gasolines may further suitably contain a non-
ionic surfactant, such as an alkylphenol or an alkylalkoxylate. Suitable examples of such surfactants
include C4-C1g-alkylphenol and C2-C6-alkylethoxylate or
C2-C6-alkylpropoxylate or mixtures thereof. The amount
of the surfactant is advantageously from 10 to 1000
ppmw.
The gasoline can also contain other conventional
additives including antioxidants such as phenolics,
e.g. 2,6-di-tert-butylphenol or phenylenediamines, e.g.
N,N'-di-sec-butyl-p-phenylenediamine, dyes, metal
deactivators, dehazers such as polyester-type
ethoxylated alkylphenol-formaldehyde resins. Corrosion
inhibitors, such as that commercially sold by Rhein
Chemie, Mannheim, Germany as "RC 4801", or a polyhydric
alcohol ester of a succinic acid derivative having on
at least one of its alpha-carbon atoms an unsubstituted
or substituted aliphatic hydrocarbon group having from
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20 to 500 carbon atoms, for example, pentaerythritol
diester of polyisobutylene-substituted succinic acid,
the polyisobutylene group having an average molecular
weight of about 950, in an amount from about 1 ppmw to
about 1000 ppmw, may also be present. The fuels can
also contain antiknock compounds such as methyl
cyclopentadienylmanganese tricarbonyl, tetraethyl lead
or other lead-containing compounds, and ortho-
azodiphenol as well as co-antiknock compounds such as
benzoyl acetone.
A preferred gasoline composition of the invention
may additionally contain a minor amount of at least one
additional additive compound selected from the group
consisting of polyalkenyl amines, Mannich amines,
polyalkenyl succinimide, poly(oxyalkylene)amines,
poly(oxyalkylene)carbamates, and poly(alkenyl)-N-
substituted carbamates.
An effective amount of the additive comprising the
furan derivative is introduced into the combustion zone
of the engine in a variety of ways to prevent build-up
of deposits or to accomplish the modification of
existing deposits that are related to octane
requirement. A preferred method is to add a minor
amount of a furan derivative as defined above to the
gasoline. For example, one or more furan derivatives
as defined above are added directly to the gasoline or
are blended with one or more carriers and/or one or
more hydrocarbon-soluble alkali metal or alkaline earth
metal salts and/or one or more additional detergents
before being added to the gasoline.
The amount of furan derivative used will depend on
the particular furan derivative used, the fuel, and the
presence or absence of carriers, detergents and
diluents.
The carrier, when utilised, may conveniently have
an average molecular weight from about 250 to about
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5000. Suitable carriers, when utilised, include
hydrocarbon based materials such as polyisobutylenes
(PIB's), polypropylenes (PP's) and polyalphaolefins
(PAO's), all of which may be hydrogenated or
unhydrogenated but are preferably hydrogenated;
polyether based materials such as polybutylene oxides
(poly BO's), polypropylene oxides (poly PO's),
polyhexadecene oxides (poly HO's) and mixtures thereof
(i.e. both (poly BO) + (poly PO) and poly-BO-PO)); and
mineral oils such as those sold by member companies of
the Royal Dutch/Shell group under the designations
"HVI" and "XHVI" (trade mark), Exxon Naphthenic 900 sus
mineral oil and high viscosity index oils in general.
The carrier is preferably selected from PIB's, poly
BO's and poly PO's with poly PO's being the most
preferred.
A particularly prepared carrier fluid comprises a
combination of a polyalphaolefin having a viscosity at
100~C in the range 2 x 10-6 to 2 x 10-5 m2/s (2 to 20
centistokes) being a hydrogenated oligomer containing
18 to 80 carbon atoms derived from at least one
alphaolefinic monomer containing from 8 to 16 carbon
atoms, and a polyoxyalkylene compound selected from
glycols, mono- and diethers thereof, having number
average molecular weight (Mn) in the range 400 to 3000,
the weight ratio polyalphaolefin: polyoxyalkylene
compound being in the range 1:10 to 10:1.
The polyalphaolefins are primarily trimers,
tetramers and pentamers, and synthesis of such
materials is outlined in Campen et al., "Growing use of
synlubes", Hydrocarbon Processing, February 1982, pages
75 to 82. The polyalphaolefin is preferably derived
from an alphaolefinic monomer containing from 8 to 12
carbon atoms. Polyalphaolefins derived from decene-1
have been found to be very effective. The
polyalphaolefin preferably has viscosity at 100~C in
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the range of 6 x 10-6 to 1 x 10-5 m2/s (6 to 10
centistokes). Polyalphaolefin having a viscosity at
100~C of 8 x 10-6 m2/s (8 centistokes) has been found
to be very effective.
Preferred polyoxyalkylene compounds for use in
combination with these polyalphaolefins are described
in EP-A-588429 (Applicants reference T 5677).
The carrier concentration in the final fuel
composition is up to about 1000 ppm weight. When a
carrier is present, the preferred concentration is from
about 50 ppm by weight to about 400 ppm by weight,
based on the total weight of the fuel composition.
Once the carrier is blended with the furan derivative
and any other desired components, the blend is added
directly to the fuel or packaged for future use.
The hydrocarbon-soluble alkali metal or alkaline
earth metal salt, when utilised, may be one of those
described in WO 87/01126, and the compounds of formula
I are particularly suitable for incorporation, as
additional component, in fuel compositions as described
in WO 87/01126. Preferred hydrocarbon-soluble alkali
metal or alkaline earth metal salts are, however,
alkali metal or alkaline earth metal salts of a
succinic acid derivative. Such a salt of a succinic
acid derivative, when utilised, will have as a
substituent on one of its alpha-carbon atoms an
unsubstituted or substituted aliphatic hydrocarbon
group having from 20 to 200 carbon atoms.
Alternatively, the succinic acid derivative will have
as a substituent on one of its alpha-carbon atoms an
unsubstituted or substituted hydrocarbon group having
from 20 to 200 carbon atoms which is connected to the
other alpha-carbon atom by means of a hydrocarbon
moiety having from 1 to 6 carbon atoms, forming a ring
structure. Suitable such salts are described for
example in EP-A-207560 and in EP-A-491439.
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The salts of the succinic acid derivative can be
monobasic or dibasic. Monobasic salts in which the
remaining carboxylic acid group has been transformed
into an amide or ester group may also be used.
Suitable alkali metal salts of a partial ester of an
alkyl polyether alcohol with a succinic acid derivative
are described in EP-A-491439.
Suitable metal salts include lithium, sodium,
potassium, rubidium, caesium and calcium salts.
Particularly preferred salts are described in EP-A-
207560.
The aliphatic hydrocarbon substituent(s) of the
succinic acid derivative is suitably derived from a
polyolefin, the monomers of which have 2 to 6 carbon
atoms. Thus, convenient substituents include
polyethylene, polypropylene, polybutylenes,
polypentenes, polyhexenes or mixed polymers.
Particularly preferred is an aliphatic hydrocarbon
group which is derived from polyisobutylene.
The hydrocarbon group may include an alkyl and/or
an alkenyl moiety and may contain substituents. One or
more hydrogen atoms may be replaced by another atom,
for example halogen, or by a non-aliphatic organic
group, e.g. an (un)substituted phenyl group, a hydroxy,
ether, ketone, aldehyde or ester. A very suitable
substituent in the hydrocarbon group is at least one
other metal succinate group, yielding a hydrocarbon
group having two or more succinate moieties.
The aliphatic hydrocarbon group should contain 20
to 200, preferably 35-150, carbon atoms. When a
polyolefin is used as substituent the chain length is
conveniently expressed as the number average molecular
weight. The number average molecular weight of the
substituent, e.g. determined by osmometry, is
advantageously from 400 to 2000.
The succinic acid derivative may have more than one
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C20_20o aliphatic hydrocarbon group attached to one or
both alpha-carbon atoms, but preferably it has one C20_
200 aliphatic hydrocarbon group on one of its alpha-
carbon atoms and on the other alpha-carbon atom either
no substituent or a hydrocarbon of only a short chain
length, e.g. C1_6 group. The latter group can be
linked with the C20_20o hydrocarbon group forming a
ring structure.
The gasoline compositions of the present invention
may also contain one or more detergents. When
detergents are utilised, the gasoline composition will
comprise a mixture of a major amount of fuel boiling in
the gasoline boiling range as described hereinbefore, a
minor amount of the furan derivative as defined above
and a minor amount of an detergent selected from
polyalkenyl amines, e.g. polybutyleneamines, such as
"KEROCOM" polyisobutyleneamine, available ex BASF,
Mannich amines, polyalkenyl succinimides,
poly(oxyalkylene)amines, poly(oxyalkylene) carbamates,
poly(alkenyl)-N-substituted carbamates, and mixtures
thereof. As noted above, a carrier as described
hereinbefore may also be included. The "minor amount"
of detergent is preferably less than about 10% by
weight of the total fuel composition, more preferably
less than about 1% by weight of the total fuel
composition and yet more preferably less than about
0.1% by weight of the total fuel composition.
The polyalkenyl amine detergents utilised comprise
at least one monovalent hydrocarbon group having at
least 50 carbon atoms and at least one monovalent
hydrocarbon group having at most five carbon atoms
bound directly to separate nitrogen atoms of a diamine.
Preferred polyalkenyl amines are polyisobutenyl amines.
Polyisobutenyl amines are known in the art and
representative examples are disclosed in various US
Patents including US Patent No. 3,753,670, US Patent
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No. 3,756,793, US Patent No. 3,574,576 and US Patent
No. 3,438,757. Particularly preferred polyisobutenyl
amines for use in the present fuel composition include
N-polyisobutenyl-N', N'-dimethyl-1,3-diaminopropane
(PIB-DAP), OGA-472 (a polyisobutenyl ethylene diamine
available commercially from Oronite), N-polyisobutenyl
diethylene triamine (PIB-DETA) and N-polyisobutenyl
triethylene tetramine (PIB-TETA).
The Mannich amine detergents utilised comprise a
condensation product of a high molecular weight alkyl-
substituted hydroxyaromatic compound, an amine which
contains an amino group having at least one active
hydrogen atom (preferably a polyamine), and an
aldehyde. Such Mannich amines are known in the art and
are disclosed in US Patent No. 4,231,759. Preferably,
the Mannich amine is an alkyl substituted Mannich
amine.
The polyalkenyl succinimide detergents comprise the
reaction product of a dibasic acid anhydride with
either a polyoxyalkylene diamine, a hydrocarbyl
polyamine or mixtures of both. Typically the
succinimide is substituted with the polyalkenyl group
but the polyalkenyl group may be found on the
polyoxyalkylene diamine or the hydrocarbyl polyamine.
Polyalkenyl succinimides are also known in the art and
representative examples are disclosed in various patent
references including US Patent No. 3,443,918, EP-A-
208560, DE-OLS 3,126,404, US Patent No. 4,234,435, US
Patent No. 4,810,261, US Patent No. 4,852,993, US
Patent No. 4,968,321, US Patent No. 4,985,047, US
Patent No. 5,061,291 and US Patent No. 5,147,414.
Particularly effective succinimide detergents are
those obtained by reacting at least one amine, with a
polyalkenyl derivative of a monoethylenically
unsaturated C4_10 dicarboxylic acid material in which
the ratio of dicarboxylic acid moieties per polyalkenyl
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chain is not greater than 1.2:1 and the number average
molecular weight (Mn) of the polyalkenyl chain is in
the range from 1600 to 5000, e.g. as described in EP-A-
587250 (Applicants reference T1665).
Amines employed in the preparation of said
succinimide detergents are preferably C1_30, more
preferably C1_18, and especially Cg_12, amines
containing 1 to 8 nitrogen atoms. Such amines may be
branched or unbranched, saturated aliphatic, primary or
secondary amines, containing 1 to 8 nitrogens,
preferably mono- or diamines, such as ethylamine,
butylamine, sec. butylamine, diethylamine and 3-
dimethylamino-1-propylamine, but including higher
polyamines such as alkylene polyamines, wherein pairs
of nitrogen atoms are joined by alkylene groups of 2 to
4 carbon atoms.
Poly(oxyalkylene)amines are described, for example,
in US Patents Nos. 4,985,047 and 4,332,595, in EP-A-440
248, EP-A-310 875, EP-A-208 978 and WO-A-85 01956. The
poly(oxyalkylene) carbamate detergents comprise an
amine moiety and a poly(oxyalkylene) moiety linked
together through a carbamate linkage, i.e., -O-C(O)-N<.
These poly(oxyalkylene) carbamates are known in the
art and representative examples are disclosed for
example in US Patent No. 4,191,537, US Patent No.
4,160,648, US Patent No. 4,236,020, US Patent No.
4,270,930, US Patent No. 4,288,612 and US Patent No.
4,881,945. Particularly preferred poly(oxyalkylene)
carbamates for use in the present fuel composition
include OGA-480 (a poly(oxyalkylene) carbamate which is
available commercially from Oronite).
The poly(alkenyl)-N-substituted carbamate
detergents utilised are of the formula:
o
R-A-C-OR
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in which R is a poly(alkenyl) chain; R1 is a
hydrocarbyl or substituted hydrocarbyl group; and A is
an N-substituted amino group. Poly(alkenyl)-N-
substituted carbamates are known in the art and are
disclosed in US Patent No. 4,936,868.
The one or more detergents are added directly to
the fuel boiling in the gasoline boiling range, blended
with the furan derivative as defined above, or blended
with the furan derivative and one or more carriers
before being added to the fuel.
The concentration of the one or more detergents in
the final fuel composition is generally up to about
1000 ppmw for each detergent. When one or more
detergents are utilised, the preferred concentration
for each detergent is from about 10 ppmw to about 400
ppmw, based on the total weight of the fuel
composition, even more preferably from about 25 ppmw to
about 250 ppmw, based on the total weight of the fuel
composition.
Additive components can be added separately to the
fuel boiling in the gasoline boiling range or can be
blended with one or more diluents, forming an additive
concentrate, and added to the fuel together. Suitable
gasoline-compatible diluents are hydrocarbons and
mixtures of hydrocarbons with alcohols or ethers, such
as methanol, ethanol, propanol, 2-butoxyethanol, methyl
tert-butyl ether, or higher alcohols such as "Dobanol
91", (Trade Mark) available from member companies of
the Royal Dutch/Shell group.
Preferably the diluent is an aromatic hydrocarbon
solvent such as toluene, xylene, mixtures thereof or
mixtures of toluene or xylene with an alcohol.
Additionally preferred diluents include "Shellsol AB",
"Shellsol R", (Trade Marks) and low aromatic white
spirit (LAWS), which are available from member
companies of the Royal Dutch/Shell group.
2199914
- 19 -
Use in fuels of the preferred furan derivatives of
the present invention, especially preferred furfuryl
alcohol resins, in concentrations within the preferred
ranges has been found to bring about considerable
reduction in combustion chamber deposit weights. From
observations, it is believed that this is achieved by
promotion of deposit flaking in combustion chambers.
The present invention will be further understood
from the following illustrative examples, in which the
test materials were as follows:-
Test Material 1 - N-furfuryl-2-furamide
N-furfuryl-2-furamide was prepared by adding
dropwise to a mixture of furfurylamine (7.44 g; 76
mmol; ex Aldrich) and triethylamine (35.6 g; 352 mmol)
in dichloromethane 2-furoyl chloride (23 g; 176 mmol)
at a temperature of 0 to 5 ~C. The product obtained was
washed with water, dried with magnesium sulphate and
evaporated. Subsequently, the product so obtained was
purified by flash chromatography (silica, hexane/ethyl
acetate as eluant) and 14 g (97 ~ yield) of the product
was recovered.
Test Material 2 - 2-amino-1-(2-furanylmethyl)-4,5-
difuryl-3-pyrrolecarbonitrile
2-amino-1-(2-furanylmethyl)-4,5-difuryl-3-
pyrrolecarbonitrile was prepared as follows: 300 g(1.56 mol) of furoin (ex Aldrich) was reacted with
151.6 g (1.56 mol) of furfurylamine in the presence of
1.5 g of p-toluenesulphonic acid in toluene under
stirring at reflux temperature. Water produced by the
reaction was removed via a Dean Stark trap. When
formation of water had ceased (31 ml removed), 103.1 g
(1.56 mol) of malononitrile was added as a dispersion
in 100 ml toluene, reflux was continued. When again
formation of water had ceased (26 ml removed via the
Dean Stark trap), the reaction mixture was cooled and
the toluene was removed by evaporation. In this way 498
2199914
- 20 -
g of a black solid product was obtained. Subsequently,
100 g of this product was purified by flash
chromatography (silica, hexane/ethyl acetate as eluant)
and 24 g of the product was recovered.
Test Material 3 - N-phenyl furamide
N-phenyl furamide was prepared by adding to a
mixture of aniline (23.3 g; 250 mmol) and triethylamine
(25.3 g; 250 mmol) in dichloromethane slowly 32.6 g
(250 mmol) of 2-furoyl chloride, while maintaining the
temperature at -10~C. The product obtained was washed
with diluted hydrochloric acid and water, dried with
magnesium sulphate and evaporated. The product so
obtained was than triturated with hexane and filtered.
39.3 g (84 ~ yield) of product was recovered.
Test Material 4 - 1-furfurylpyrrole (ex Aldrich)
Test Material 5 - furil (ex Aldrich)
Test Material 6 - furfuryl benzoate (ex Aldrich)
Test Material 7 - furfuryl alcohol resin, Mn 175
10.6 g of a furfuryl alcohol resin of the present
invention (Mn 175) was obtained by distilling 100 g of
"QuaCorr 1300" furfuryl alcohol resin (Trade Mark) (ex
QO Chemicals) (Mn 425) under reduced pressure at a
temperature from 42~C (2.24 10-3 atm) (224 to 92~C
(6.58 10-5 atm) (6.58 Pa)
Test Material 8 - furfuryl alcohol resin, Mn 156
123 g of a furfuryl alcohol resin of the present
invention (Mn 156) was obtained by distilling 1,014 g
of "QuaCorr 1300" resin (ex QO Chemicals) under reduced
pressure at a temperature from 42 ~C (7.24 10-4 atm)
(72.4 Pa) to 120 ~C (1.97 10-3 atm) (197 Pa).
Test Material 9 - Furfuryl alcohol resin, Mn 228
150 g of a furfuryl alcohol resin of the present
invention (Mn 228) was prepared by mixing 500 g (5.1
mol) of furfuryl alcohol (ex Aldrich) with 500 g of
water and 1.15 g (11.5 mmol) of concentrated sulphuric
acid and heating the mixture for 2 hours at a
2199914
'._ .
- 21 -
temperature of 50 ~C. The mixture so obtained, which
separated into two phases, was then neutralised with a
saturated sodium bicarbonate solution. The organic
phase containing the furfuryl alcohol resin produced
was extracted into ether, washed with water, dried with
magnesium sulphate and evaporated under reduced
pressure.
Test Material 10 - furfuryl alcohol resin, Mn 272
117 g of a furfuryl alcohol resin of the present
invention (Mn 272) was prepared in a manner similar to
that described for Test Material 9 except that 400 g
(4.1 mol) of the furfuryl alcohol was mixed with 400 g
water and 0.092 g (0.92 mmol) of concentrated sulphuric
acid, and the mixture was heated for 6 hours at a
temperature of from 70 ~C to 90~C.
Test Material 11 - furfuryl alcohol resin, Mn 388
255 g of a furfuryl alcohol resin of the present
invention (Mn 388) was prepared in a manner similar to
that described for Test Material 10 except that the
heating was carried out for 24 hours at a temperature
of 50~C, and ten times the amount of concentrated
sulphuric acid was used (0.92 g, 9.2 mmol).
Test Material 12 - esterified furfuryl alcohol resin
321 g of an esterified furfuryl alcohol resin of
the present invention was prepared by reacting 150 g
(0.42 mol) of Test Material 10 with 176 g (0.42 mol) of
C1s-C1g internal olefin-succinic anhydride (ex Shell
Chemicals) in toluene under reflux for 6 hours, after
which the toluene was evaporated.
Test Material 13 - "QuaCorr 1300" furfuryl alcohol
resin
(ex QO Chemicals, Sheffield, UK) (Mn 425)
Comparative Test Material A - 2 - furaldehyde diethyl-
(Comp. A) acetal (ex Aldrich)
Comparative Test Material B - 2-furaldehyde dimethyl-
(Comp. B) hydrazone (ex Aldrich)
2199914
-
- 22 -
Comparative Test Material C - furfuryl alcohol (ex
(Comp. C) Aldrich)
In each of the examples which follow, samples of
the test materials were dissolved in unleaded gasoline
and the resulting fuels (gasoline compositions) were
tested as will be described.
EXAMPLES l to 5
The beneficial effect on octane requirement of
gasoline additives comprising furan derivatives in
accordance with the present invention was demonstrated
by the following procedure.
A single cylinder Hydra engine was used,
manufactured by Ricardo Co., Shoreham, Sussex, UK,
having bore/stroke 86 mm/86 mm and compression ratio
9.5:1, and fitted with a flat-topped piston and flat-
topped cylinder head having two valves. A fuel
injector was employed, targeted onto the back of the
inlet valve and arranged for injection whilst the valve
is closed.
Deposits were built up at l000 rpm with wide open
throttle (WOT) and high load during 200 hours with an
unleaded gasoline containing 0.5 wt% fluoranthene.
Cylinder pressure signals were monitored to detect the
high rate of change in cylinder pressure during
autoignition and Knock Limited Spark Advance (KLSA) was
determined under l000 rpm and WOT conditions.
Calibration tests with reference fuels showed that the
engine responded to the Research Octane Number (RON) of
the fuel and that the KLSA changed by approximately one
crank angle degree (cad) per octane number. Starting
from clean combustion chamber conditions, the KLSA of
the Hydra engine was reduced by between 8 and l0 cad
(DKLSA between -8 and -l0) over the first 200 hours
operation as combustion chamber deposits built up,
after which it reached equilibrium. Each additive was
tested over a period of continued running, after which
~ _ - 23 - 2199914
the engine was reconditioned on base fuel.
The various properties of the additives, conditions
applied and results of the experiments are shown in
Table 1. It will be clear from these results that the
S use of the test materials 1 to 1~ in accordance with
the present invention (Examples 1 to 15) brings about a
surprisingly high reduction in the octane requirement
of the engine when compared with the comparative test
materials A, B and C falling outside the scope of the
present invention (Comparative Examples A, B and C).
24 - 2199914
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21q9914
- 25 -
The "molecular weight" values for Test Materials 7
to 13 inclusive are number average molecular weight
(Mn) values determined by gel permeation chromatography
(GPC), using polystyrene calibration standards.
Examples 16 and 17
In two further experiments a VW engine (1.8 1)
modified for research was operated at a speed of 1500
rpm. The deposits were built up at 2250 rpm and a load
of 30 Nm. The engine was knock rated by measuring Knock
Limited Spark Advance (KLSA) at 1500 rpm and a load of
80 Nm at frequent intervals during the test.
Combustion chamber deposit (CCD) weight was monitored
by stopping the engine and removing two plugs from the
combustion chamber.
In Example 16, the engine was run for 120 hours
using an unleaded gasoline. The engine was then
switched to the same gasoline which in addition
contained 0.75 g/l of "QuaCorr 1300" furfuryl alcohol
resin (ex QO Chemicals) which was dissloved in
methylpropanol (0.5% by volume of the gasoline). An
increase in KLSA was observed of 2.5 crank angle
degrees, after 45 hours when a reference fuel of 85
octane number was used for knock rating. Over the same
period of time the CCD weight was reduced from 41.5 mg
to 26.6 mg. In other words use of the present additive
package established a 36% reduction in CCD weight.
In Example 17, the engine was run for 43 hours
using an unleaded gasoline containing 0.5% by volume of
methylpropanol. The engine was then switched to the
same gasoline which in addition contained 0.35 g/l of
"QuaCorr 1300" furfuryl alcohol resin. An almost
immediate increase was observed in KLSA of 3 crank
angle degrees, whereas after 43 hours an increase was
observed of 1.5 crank angle degrees. Over the same
period of time the CCD weight was reduced from 29 mg to
24.5 mg. In other words the use of the present additive
established a 16% reduction in CCD weight.
