Note: Descriptions are shown in the official language in which they were submitted.
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Additive Composition
This invention relates to additive compositions, and to their use to improve
the
characteristics of fuel oils, especially middle distillate fuels such as
diesel fuels, kerosene
and jet fuel.
Environmental concerns have led to a need for fuels with reduced sulphur
content,
especially diesel fuel, heating oil and kerosene. However, the refining
processes that
produce fuels with low sulphur contents also result in a product of lower
viscosity and a
lower content of other components in the fuel that contribute to its
lubricity, for example,
polycyclic aromatics and polar compounds. Furthermore, sulphur-containing
compounds in
general are regarded as providing some anti-wear properties and a result of
the reduction in
their proportions, together with the reduction in proportions of other
components providing
lubricity, has been an increase in the number of reported problems in fuel
pumps in diesel
engines. The problems are caused by wear in, for example, cam plates,
plungers, rollers,
spindles and drive shafts, which may result in sudden pump failures relatively
early in the
life of the engine.
The problems may be expected to become worse in future because, in order to
meet
stricter requirements on exhaust emissions generally, higher pressure fuel
systems, including
in-line pumps, rotary pumps, common-rail pumps and unit injector systems, are
being
introduced, these being expected to have more stringent lubricity requirements
than present
equipment, at the same time as lower sulphur levels in fuels become more
widely required.
Historically, the typical sulphur content in a diesel fuel was below 0.5% by
weight.
In Europe maximum sulphur levels have been reduced from 0.20% to 0.05% and in
Sweden
grades of fuel with levels below 0.005% (Class 2) and 0.001% (Class 1) are in
use. A fuel
oil composition with a sulphur level below 0.05% by weight is referred to
herein as a low-
sulphur fuel.
Such low-sulphur fuels may contain an additive to enhance their lubricity.
These
additives are of several types. In WO 94/17160, there is disclosed a low
sulphur fuel
comprising a carboxylic acid ester to enhance lubricity, more especially an
ester in which
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the acid moiety contains from 2 to 50 carbon atoms and the alcohol moiety
contains one or
more carbon atoms. In U.S. Patent No. 3273981, a mixture of a dimer acid, for
example, the
dimer of linoleic acid, and a partially esterified polyhydric alcohol is
described for the same
purpose. In U.S. Patent No. 3287273, the use of an optionally hydrogenated
dimer acid
glycol ester is described. Other materials used as lubricity enhancers, or
anti-wear agents as
they are also termed, include a sulphurized dioleyl norbomene ester (EP-A-
99595), castor
oil (U.S. Patent No. 4375360 and EP-A-605857) and, in methanol-containing
fuels, a variety
of alcohols and acids having from 6 to 30 carbon atoms, acid and alcohol
ethoxylates, mono-
and di-esters, polyol esters, and olefin-carboxylic acid copolymers and vinyl
alcohol
polymers (also U.S. Patent No. 4375360).
EP 0 798 364 Al describes the use of a salt formed by the reaction between a
carboxylic acid and an aliphatic amine to improve inter alia, the lubricity of
a diesel fuel.
The amines used have hydrocarbyl groups of between 2 and 50 carbon atoms,
preferably
between 8 and 20 carbon atoms, with amines such as oleyl amine being
exemplified.
US 6,277,158 describes a concentrate containing n-butlyamine oleate as a
friction
modifier for addition to motor gasoline.
US2002/0095858 relates to fuel oil compositions containing an additive formed
by
the reaction of a mono- or dicarboxylic acid of 6 to 50 carbon atoms with an
amine having at
least one branched alkyl substituent. These additives are shown to be
effective lubricity
enhancers for the fuel.
US 2002/0014034 describes the use of additives to improve the lubricity of a
fuel oil.
A suitable additive may be formed by the reaction of N, N-dibutylamine with an
acid
mixture consisting of 70% fatty acids and 30% resin-based acids.
A further consequence of refining processes employed to reduce diesel fuel
sulphur
and aromatic contents is a reduction in the electrical conductivity of the
fuel. The insulating
properties of low sulphur fuels represent a potential hazard to refiners,
distributors and
customers due to the potential for static charge accumulation and discharge.
Static charges
can occur during pumping and especially filtration of the fuel, the release of
this charge
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accumulation as a spark constituting a significant risk in highly flammable
environments.
Such risks are minimised during fuel processing and handling through
appropriate earthing
of fuel lines and tanks combined with the use of anti-static additives. These
anti-static
additives do not prevent the accumulation of static charges but enhance their
release to the
earthed fuel lines and vessels thereby controlling the risk of sparking. A
number of such
additives are in common usage and are available commercially.
It is thus desirable to be able to improve both the lubricity and conductivity
of low
sulphur content fuels.
EP 1 328 609 describes combinations of either a hydrocarbyl monoamine or an N-
hydrocarbyl-substituted poly(alkyleneamine) with either a fatty acid
containing 8 to 24
carbon atoms or an ester thereof with an alcohol or polyol of up to 8 carbon
atoms.
The present invention is based on the observation of a negative interaction
between
certain lubricity improving additives and certain conductivity improving
additives, and the
discovery of combinations of species where this negative interaction is
minimised.
Thus in accordance with a first aspect, the present invention provides an
additive
composition comprising a lubricity enhancer and a conductivity-improving
additive;
wherein the lubricity enhancer comprises a salt formed by the reaction of a
carboxylic acid
with di-n-butylamine; and wherein the conductivity improving additive
comprises the
combination of:
(a) a polymeric condensation product formed by the reaction of an aliphatic
aldehyde or ketone, or a reactive equivalent, with at least one ester of
p-hydroxybenzoic acid with,
(b) a copolymer, terpolymer or polymer of acrylic acid or methacrylic acid or
a
derivative thereof.
The combination of the lubricity enhancer and the conductivity-improving
additive
according to the present invention is able to provide both good lubricity and
good
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conductivity to a fuel oil composition. This is in contrast to combinations of
the lubricity
enhancer with other conductivity-improving additives where a significant loss
in
conductivity performance has been observed.
In this specification, the use of the term 'salt' to describe the product
formed by the
reaction of the carboxylic acid and the amine should not be taken to mean that
the reaction
necessarily forms a pure salt. It is presently believed that the reaction does
form a salt and
thus that the reaction product contains such as salt however, due to the
complexity of the
reaction, it is likely that other species will also be present. The term
'salt' should thus be
taken to include not only the pure salt species, but also the mixture of
species formed during
the reaction of the carboxylic acid and the amine.
As carboxylic acid, those corresponding to the formula [R'(COOH)X]y , where
each
R' is independently a hydrocarbon group of between 2 and 45 carbon atoms, and
x is an
integer between 1 and 4, are suitable. Preferably, R' is a hydrocarbon group
of 8 to 24
carbon atoms, more preferably, 12 to 20 carbon atoms. Preferably, x is 1 or 2,
more
preferably, x is 1. Preferably, y is 1, in which case the acid has a single R'
group.
Alternatively, the acid may be a dimer, trimer or higher oligomer acid, in
which case y will
be greater than 1 for example 2, 3 or 4 or more. R' is suitably an alkyl or
alkenyl group
which may be linear or branched. Examples of carboxylic acids which may be
used in the
present invention include: lauric acid, myristic acid, palmitic acid, stearic
acid, isostearic
acid, neodecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic
acid, montanic
acid, melissic acid, caproleic acid, oleic acid, elaidic acid, linoleic acid,
linolenic acid,
coconut oil fatty acid, soy bean fatty acid, tall oil fatty acid, sunflower
oil fatty acid, fish oil
fatty acid, rapeseed oil fatty acid, tallow oil fatty acid and palm oil fatty
acid. Mixtures of
two or more acids in any proportion are also suitable. Also suitable are the
anhydrides of
carboxylic acids, their derivatives and mixtures thereof. In a preferred
embodiment, the
carboxylic acid comprises tall oil fatty acid (TOFA). It has been found that
TOFA with a
saturate content of less than 5% by weight is especially suitable. As is known
in the art,
TOFA contains small but variable amounts of rosin acids and isomers thereof.
Preferably,
TOFA with an abietic acid content of less than 5% by weight, for example, less
than 2% by
weight, is used.
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In another preferred embodiment, the carboxylic acid comprises rapeseed oil
fatty
acid.
In another preferred embodiment, the carboxylic acid comprises soy bean fatty
acid.
In another preferred embodiment, the carboxylic acid comprises sunflower oil
fatty
acid.
Also suitable are aromatic carboxylic acids and their alkyl derivatives as
well as
aromatic hydroxy acids and their alkyl derivatives. Illustrative examples
include benzoic
acid, salicylic acid and acids derived from such species.
Preferably, the carboxylic acid has an iodine value of at least 80g/100g, more
preferably at least 100 g/100g, for example, at least 130 g/lOOg or at least
150 g/100g.
Particularly preferred embodiments of the present invention are thus where the
lubricity enhancer comprises a salt formed by the reaction of
Tall oil fatty acid with di-n-butylamine,
Rapeseed oil fatty acid with di-n-butylamine,
Soy bean fatty acid with di-n-butylamine, and
Sunflower oil fatty acid with di-n-butylamine.
The salt may conveniently be produced by mixing the carboxylic acid with the
amine.
The order in which one component is added to the other is not important. The
molar ratio of
the amount of acid to the amount of amine is suitably from 10:1 to 1:10,
preferably from
10:1 to 1:2, more preferably from 2:1 to 1:2, for example, around 1:1. In an
embodiment, a
molar ratio of 1.1:1 to 1:1.1 has been found to be suitable. The reaction may
be conducted
at room temperature, but is preferably heated gently, for example to 40 C.
These salts are the subject of the present Applicant's co-pending application
EP 05270062.2 where in addition to providing good lubricity to fuel oil
compositions they
were found to display particularly good low temperature properties.
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Component (a)
Component (a) is a condensate species derived from an alkyl ester of
p-hydroxybenzoic acid. These HydroxyBenzoate-Formaldehyde Condensates are the
subject of the present Applicant's co-pending application EP 1 640 438 A and
are referred to
herein as HBFC.
Preferably, the at least one ester of p-hydroxybenzoic acid comprises; (i) a
straight or
branched chain Ci - C7 alkyl ester of p-hydroxybenzoic acid; (ii) a branched
chain Cg- C16
alkyl ester of p-hydroxybenzoic acid, or; (iii) a mixture of long chain C8 -
C18 alkyl esters
of p-hydroxybenzoic acid, at least one of said alkyls being branched.
Preferably, the alkyl in (i) is ethyl or n-butyl.
Preferably, the branched alkyl group in (ii) is 2-ethylhexyl or isodecyl.
Conveniently, the molar ratio of the branched ester to the other ester is in
the range
of5:1 to 1:5.
Condensates of mixed esters may be used, for example mixed ester condensates
of
n-octyl and 2-ethylhexyl esters of p-hydroxybenzoic acid may be prepared. The
ratio of the
esters in the mixed condensates may be varied as required. A mixed ester
condensate where
the molar ratio of 2-ethylhexyl ester to n-octyl ester is 3:1 has been found
to be useful.
Mixed ester condensates of more than two ester monomers may also be prepared.
The number average molecular weight of the polymeric condensation products is
suitably in the range of 500 to 5000, preferably 1000 to 3000, more preferably
1000 to 2000
Mn.
Other comonomers may be added to the reaction mixture of aldehyde and alkyl
ester
or mixture of alkyl esters. Some of the polymers described above, for example,
that are
based on the 2-ethylhexyl ester, are too viscous to be handled conveniently at
temperatures
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they would be used commercially, i.e. ambient to 60 C, unless diluted with a
large
proportion of solvent. This problem can be overcome by replacing up to 33 mole
% of the p-
hydroxybenzoic ester or ester mixture used in the condensation reaction with
other
comonomers in order to modify the physical properties of the polymers whilst
still retaining
activity. The comonomers are aromatic compounds that are sufficiently reactive
to take part
in the condensation reaction. They include alkylated, arylated and acylated
benzenes such as
toluene, xylene, mesitylene, biphenyls and acetophenone. Other comonomers
include
hydroxy aromatic compounds such as p-hydroxybenzoic acid, acid derivatives of
p-
hydroxyaromatic acids such as amides and salts, other hydroxyaromatic acids,
alkylphenols,
naphthols, phenylphenols, acetamidophenols, alkoxyphenols and o-alkylated, o-
arylated and
o-acylated phenols. The hydroxy compounds should be either di- or mono-
functional with
regard to the condensation reaction. The hydroxy compounds that are di-
functional should
be substituted in the para- position whilst those that are mono-functional can
be substituted
in any position, e.g. 2,4-di-t-butylphenol - these will only incorporate at
the end of a
polymer chain.
HBFC may be prepared by the reaction between one or more aldehydes or ketones
or
reactive equivalents with esters of p-hydroxybenzoic acid. The term "reactive
equivalent"
means a material that generates an aldehyde under the conditions of the
condensation
reaction or a material that undergoes the required condensation reaction to
produce moieties
equivalent to those produced by an aldehyde. Typical reactive equivalents
include oligomers
or polymers of the aldehyde, acetals or aldehyde solutions.
The aldehyde may be a mono- or di- aldehyde and may contain other functional
groups, such as -COOH, and these could be capable of post-reactions in the
product. The
aldehyde or ketone or reactive equivalent preferably contains 1-8 carbon
atoms, particularly
preferred are formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde,
most
preferred is formaldehyde. Formaldehyde could be in the form of
paraformaldehyde, trioxan
or formalin.
HBFC may be prepared by reacting 1 molecular equivalent (M.E.) of the esters
of p-
hydroxybenzoic acid with about 0.5-2 M.E. of the aldehyde, preferably 0.7-1.3
M.E. and
more preferably 0.8-1.2 M.E. of the aldehyde. The reaction is preferably
conducted in the
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presence of a basic or acidic catalyst, more preferably an acidic catalyst,
such as p-
toluenesulphonic acid. The reaction is conveniently conducted in an inert
solvent, such as
Exxsol D60 (a non-aromatic, hydrocarbon solvent, having a boiling point of -
200 C), the
water produced in the reaction being removed by azeotropic distillation. The
reaction is
typically run at a temperature of 90-200 C, preferably 100-160 C, and may be
run under
reduced pressure.
Conveniently, the HBFC can be prepared in a 2-step process whereby the esters
of p-
hydroxybenzoic acid are first prepared in the same reaction vessel that is
used for the
subsequent condensation reaction. Thus, the ester is prepared from the
appropriate alcohol
and p-hydroxybenzoic acid in an inert solvent using an acid catalyst such as p-
toluenesulphonic acid, continuously removing water produced in the reaction.
Formaldehyde
is then added and the condensation reaction conducted as described above to
give the desired
HBFC.
Preferably, the solvent is a hydrocarbon solvent, such as an aromatic
hydrocarbon
solvent. Examples of hydrocarbon solvents include petroleum fractions such as
naphtha,
kerosene, diesel and heater oil; aromatic hydrocarbons such as aromatic
fractions, e.g. those
sold under the 'SOLVESSO' tradename; alcohols and/or esters; and paraffinic
hydrocarbons
such as hexane and pentane and isoparaffins. The additive concentrate may also
contain
further additives as required. Such further additives are known in the art and
include, for
example the following: detergents, antioxidants (to avoid fuel degradation),
corrosion
inhibitors, dehazers, demulsifiers, metal deactivators, antifoaming agents,
cetane improvers,
co-solvents, package compatibilisers, reodourants, additives to improve the
regeneration of
particulate traps, middle distillate cold flow improvers and other lubricity
additives.
Component (b)
The copolymers, terpolymers and polymers of acrylic acid or methacrylic acid
or a
derivative thereof may be branched or linear. Suitable copolymers, terpolymers
or polymers
of acrylic acid or methacrylic acid or derivatives thereof are those polymers
of ethylenically
unsaturated monomers such as methacrylic or acrylic acid esters of alcohols
having about 1
to 40 carbon atoms, such as methylacrylate, ethylacrylate, n-propylacrylate,
lauryl acrylate,
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stearyl acrylate, methylmethacrylate, ethylmethacrylate, n-propylmethacrylate,
lauryl
methacrylate, stearyl methacrylate, isodecylmethacrylate, 2-
ethylhexylmethacrylate and the
like. These copolymers, terpolymers and polymers may have number average
molecular
weights (Mn) of 1,000 to 10,000,000 and preferably the molecular weight range
is from
about 5,000 to 1,000,000, most preferably 5,000 to 100,000. A mixture of
copolymers,
terpolymers and polymers of acrylic acid or methacrylic acid may also be used.
In a preferred embodiment, the acrylate or methacrylate monomer or derivative
thereof is copolymerized with a nitrogen-containing, amine-containing or amide-
containing
monomer, or includes nitrogen-containing, amine-containing or amide-containing
branches.
This may be achieved by providing the polymer with sites suitable for
grafting, and then
nitrogen-containing, amine-containing or amide-containing branches, either
monomers or
macromonomers, are grafted onto the main chain. Transesterification reactions
or amidation
reactions may also be employed to produce the same products. Preferably, the
copolymer,
terpolymer or polymer will contain 0.01 to 5 wt.% nitrogen, more preferably
0.02 to 1 wt.%
nitrogen, even more preferably 0.04 to 0.15 wt.% nitrogen.
Examples of amine-containing monomers include: the basic amino substituted
olefins such as p-(2-diethylaminoethyl) styrene; basic nitrogen-containing
heterocycles
having a polymerizable ethylenically unsaturated substituent, such as the
vinyl pyridines or
the vinyl pyrrolidones; esters of amino alcohols with unsaturated carboxylic
acids such as
dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, tertiary
butylaminoethyl
methacrylate or dimethylaminopropyl methacrylate; amides of diamines with
unsaturated
carboxylic acids, such as dimethylaminopropyl methacrylamide; amides of
polyamines with
unsaturated carboxylic acids, examples of such polyamines being ethylene
diamine (EDA),
diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene
pentamine (TEPA),
pentaethylene hexamine (PEHA), and higher polyamines, PAM (N = 7,8) and Heavy
Polyamine (N>8); morpholine derivatives of unsaturated carboxylic acids, such
as N-
(aminopropyl)morpholine derivatives; and polymerizable unsaturated basic
amines such as
allyl amine.
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Particularly preferred is a copolymer of a methacrylate ester of a C8-Ci4
alcohol with
a methacrylate ester of an N,N-dialkylaminoalkyl alcohol, such as N,N dimethyl-
2-
aminoethanol.
In accordance with a second aspect, the present invention provides a fuel oil
composition comprising a major proportion of a fuel oil and a minor proportion
of an
additive composition according to the first aspect. .
As discussed above, it has been observed that there is a negative interaction
between
certain lubricity improving additives and certain conductivity improving
additives. The
present invention minimises this negative interaction. Accordingly, in a
preferred
embodiment of the second aspect, the fuel oil composition has a conductivity
which is at
least 50%, preferably at least 60% of the conductivity of an equivalent fuel
oil composition
containing the same quantity of the conductivity-improving additive, in the
absence of the
lubricity enhancer. In the context of this preferred embodiment it will be
understood that the
only difference between the fuel composition of the invention and the
'equivalent' fuel oil
composition is the absence of the lubricity enhancer. It will also be
understood that the
percentage of conductivity retained is to be determined using identical
measurement
conditions, e.g. temperature, measuring apparatus, sample age etc.
Preferably, the fuel oil is e.g., a petroleum-based fuel oil, especially a
middle
distillate fuel oil. Such distillate fuel oils generally boil within the range
of from 110 C to
500 C, e.g. 150 C to 400 C. The fuel oil may comprise atmospheric distillate
or vacuum
distillate, cracked gas oil, or a blend in any proportion of straight run and
thermally and/or
refinery streams such as catalytically cracked and hydro-cracked distillates.
The most
common petroleum distillate fuels are kerosene, jet fuels, diesel fuels,
heating oils and heavy
fuel oils. The heating oil may be a straight atmospheric distillate, or it may
contain minor
amounts, e.g. up to 35 wt %, of vacuum gas oil or cracked gas oil or of both.
Other examples of fuel oils include Fischer-Tropsch fuels. Fischer-Tropsch
fuels,
also known as FT fuels, include those described as gas-to-liquid (GTL) fuels,
biomass-to-
liquid (BTL) fuels and coal conversion fuels. To make such fuels, syngas (CO +
H2) is first
generated and then converted to normal paraffins by a Fischer-Tropsch process.
The normal
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paraffins may then be modified by processes such as catalytic
cracking/reforming or
isomerisation, hydrocracking and hydroisomerisation to yield a variety of
hydrocarbons such
as iso-paraffins, cyclo-paraffins and aromatic compounds. The resulting FT
fuel can be used
as such or in combination with other fuel components and fuel types such as
those
mentioned in this specification. Also suitable are fuels derived from plant or
animal sources
such as FAME. These may be used alone or in combination with other types of
fuel.
Preferably, the fuel oil has a sulphur content of at most 0.05% by weight,
more
preferably of at most 0.035% by weight, especially of at most 0.015%. Fuels
with even
lower levels of sulphur are also suitable such as, fuels with less than 50ppm
sulphur by
weight, preferably less than 20 ppm, for example lOppm or less.
In accordance with a third aspect, the present invention provides the use of
an
additive composition according to the first aspect to improve the lubricity of
a fuel oil
having a sulphur content of at most 0.05% by weight, preferably at most 0.035%
by weight,
especially of at most 0.0 15%.
Treat rates
Preferably, the salt is present in the fuel oil at level of between 5 and
1000ppm by
weight based on the weight of the fuel oil, more preferably between 10 and
500ppm, even
more preferably between 10 and 250ppm, especially between 10 and 150ppm, for
example,
between 50 and 150ppm.
Preferably, the ratio of the amount of component (a) to the amount of
component (b)
in the additive composition is between 9:1 to 1:9, more preferably between 6:1
to 1:6, for
example between 4:1 to 1:4, 3:1 to 1:3, 2:1 to 1:2 or 1:1 based on the molar
amounts of
active ingredient.
Suitably, the total amount of (a) and (b) present in the fuel oil is between
0.1 and
10,000ppm of active ingredient by weight based on the weight of the fuel oil,
preferably
between 1 and 500ppm, more preferably between 1 and 100ppm, for example,
between 3
and 50ppm.
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The invention will now be described by way of example only.
Preparation of the lubricity enhancer
Example 1
Tall oil fatty acid, with a saturate content of ca. 2% and a rosin acid
content of ca.
1.8%, (TOFA-1) (50.0g, 173mmoles) was added to a beaker with stirring. Di-n-
butylamine
(22.36g, 173mmoles) was then added to the beaker. An exotherm of ca. 38.3 C
was
measured indicating that the two components reacted. FTIR analysis of the
reaction product
showed a reduction in the strong carboxylic acid peak at 1710cm"1 compared to
the starting
acid, and a corresponding appearance of carboxylate antisymmetric and
symmetric stretches
at 1553 and 1399 cm' as well as the appearance of a broad range of peaks 2300-
2600cni 1
assignable to ammonium species. This was a clear indication of the formation
of a salt. The
flash-point of the reaction product was 67 C.
Example 2
Example I was repeated using a Tall oil fatty acid with a saturate content of
ca. 2%
and a rosin acid content of ca. 0.8%, (TOFA-2).
HFRR testin
The salts prepared in Examples 1- 4 above were tested in two low-sulphur
diesel
fuels (details given in Table 1) using the High Frequency Reciprocating Rig
(HFRR) test in
accordance with BS EN ISO 12156-1 (2000). Results are given in Table 2. The
HFRR value
for untreated Fuel 1 was 664 m, and that for untreated Fue12 was 518 m.
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Fuel 1 Fuel 2
Specification Unit
Density kg/m 811.1 858.4
Kv (40 C) cSt 1.942 2.883
Kv (20 C) cSt 2.843 4.597
Cetane No. 58.1 41.9
Sulphur wt% <0.0005 0.0428
Distillation characteristics
IBP C 175.0 187.3
10% C 206.1 219.2
50% C 235.2 270.4
95% C 279.1 333.6
FBP C 291.8 347.3
Table 1
Example Treat rate/ppm HFRR in Fuel l/ m HFRR in Fuel 21 m
50 646 385
1 100 469 377
150 438 -
50 648 -
100 608 -
2 150 522 -
200 433 -
50 666 425
3 100 451 329
50 654 -
100 614 -
150 525 -
4 200 477 -
-250 414 -
300 400 -
Table 2
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Preparation of Component (a)
The following synthetic schemes relate to the preparation of some HBFC
compounds
which may be used in the present invention. It will be understood that these
examples are
given merely to illustrate possible preparative routes and as such are not
intended to be
limiting in any way. The skilled man will be aware of other synthetic methods
and will be
able to extend the teachings to the preparation of other compounds, which
whilst not
explicitly described herein, will nonetheless be suitable for use in the
present invention.
Example 3
A mixture of p-hydroxybenzoic acid (111 Og), isodecanol (1397g), Exxsol D60
(670g,
a non-aromatic, hydrocarbon solvent, bp -200 C), and p-toluenesulphonic acid
(43g) was
heated to 160 C over 1.5 hours, slowly reducing the pressure to -200mbar. The
water
produced in the reaction was continuously removed using a Dean and Stark
apparatus.
Heating was continued for a total of 4.5 hours and the vacuum released. The
reaction
mixture was then cooled to -80 C and then to it was added 95% paraformaldehyde
(216g).
The mixture was kept at 80-85 C for 2 hours and then heated to 135 C. The
pressure was
gradually reduced to -120mbar and the water produced in the reaction was
continuously
removed using a Dean and Stark apparatus. Heating was continued for 5 hours
and then
Solvesso 150 (1500g) was added to dilute the mixture and give a product having
a Mn of
1800 and a Mw of 2400.
Example 4
A mixture of p-hydroxybenzoic acid (1109g), 2-ethylhexanol (862g), n-octanol
(288g), p-toluenesulphonic acid (43g) and Exxsol D60 (670g) heated to -157 C
over -30
mins, slowly reducing the pressure to -240mbar. Water produced in the reaction
was
continuously removed using a Dean and Stark apparatus. Heating was continued
for a total
of 3.5 hours then the vacuum was released and the mixture cooled to -80 C.
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95% Paraformaldehyde (228g) was then added and the mixture kept at 80-85 C for
2
hours followed by an hour at 95-100 C. It was then heated to 135 C and the
pressure was
gradually reduced to -120mbar. Water produced in the reaction was continuously
removed
using a Dean and Stark apparatus. Heating was continued for a total of 5
hours. Solvesso
150 (900g) and 2,4-di-t-butylphenol (500g) were then added to the mixture as
diluents to
give the final product, which had a Mn of 1150 and a Mw of 1400.
Example 5
(i) A mixture of p-hydroxybenzoic acid (213g), 2-ethylhexanol (220g), xylene
(200m1) and p-toluenesulphonic acid (2g) was refluxed at -155 C for 10 hours
and the water
produced in the reaction was continuously removed using a Dean and Stark
apparatus. The
mixture was then evaporated under reduced pressure to give 393g of product,
i.e. 2-
ethylhexyl p-hydroxybenzoate.
(ii) A mixture of the above product (39.7g), 95% paraformaldehyde (4.55g), p-
toluenesulphonic acid (0.35g) and heptane (60m1) was heated at 80-85 C for 2
hours. It was
then refluxed at -115 C for 9 hours and the water produced in the reaction was
continuously
removed using a Dean and Stark apparatus. Toluene (60m1) was then added as a
diluent to
give the product, which had a Mn of 1300 and a Mw of 1750.
Example 6
A mixture consisting of 2-ethylhexyl p-hydroxybenzoate (41.1 g, as produced in
Example 7), xylene (8.7g), 95% paraformaldehyde (5.2g), p-toluenesulphonic
acid (0.4g)
and octane (50m1) was heated to 80-85 C for 2 hours then refluxed at -135 C
for 4.5 hours,
continuously removing the water produced in the reaction using a Dean and
Stark apparatus.
Toluene (40m1) was then added to dilute the product, which had a Mn of 1000
and a Mw of
1300.
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Example 7
A mixture of 2-ethylhexyl p-hydroxybenzoate (37.3g, as produced in Example 7),
2,4-di-t-butylphenol (7.7g), 95% paraformaldehyde (5.65g), 0.45g p-
toluenesulphonic acid
and octane (25g) was heated to 80-85 C for 2 hours then refluxed at -.135 C
for 5 hours.
The water produced in the reaction was continuously removed using a Dean and
Stark
apparatus. Solvesso 150 (27g) was then added to dilute the product, which had
a Mn of 1250
and a Mw of 2000.
Component (b)
Example 8
A high molecular weight (ca. 300,000) polymethacrylate containing ca. 4 wt% of
dimethylaminoethylmethacrylate monomers.
Example 9
Isodecyl methacrylate dimethylaminoethylmethacrylate copolymers of -20,000
molecular weight where the content of the aminic monomer was 1.5, 2.5 , 5.0 or
15 wt%.
Conductivity Testing
Conductivity testing was carried out using an EmceeTM Digital Conductivity
Meter
(Model 1152), which has a calibrated range of 0-390 pSm'. The instrument is
self
calibrating and zeroing and was used in accordance with the user manual. All
conductivity
measurements were performed at room temperature on 250-300 ml of fuel in a 300
ml, tall
glass beaker. The conductivity measurements were made within 2 hours of
placing the fuel
into the beaker, dosing it with the respective additives and mixing.
Fuel samples were prepared containing the conductivity-improving additives
alone
and containing both the conductivity-improving additives and the lubricity
enhancer of
Example 2 at 200ppm by weight. Results are given in Table 3 below. Each sample
was
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tested as soon as it was prepared and again after standing for 7 and 14 days.
Fuel 1 was used.
The results are given as the percentage loss in measured conductivity between
the sample
containing only the conductivity-improving additive and the sample containing
both the
conductivity-improving additive and the lubricity enhancer.
Conductivity Treat rate / % loss after 0 % loss after 7 % loss after 14
additive wppm days days days
Al 6 28 31 36
12 25 29 29
24 11 29 17
C 1 1 64 69 76
2 73 78 83
3 78 83 85
C2 1 59 64 80
2 67 70 68
3 66 73 81
C3 1 54 73 77
2 62 67 79
3 58 66 77
Table 3
Conductivity improving additive Al was within the scope of the present
invention
being a 7:3 molar ratio of the HBFC of Example 3 and the copolymer of Example
9, where
the amine content of the copolymer was 15%. Conductivity improving additives
C1, C2 and
C3 were used for comparative purposes and were respectively; Stadis 450,
Stadis 425
which are products of the Octel Corporation, and AS-2010 available from DBM
Chemicals.
It is clear from the data presented that a large negative interaction on fuel
conductivity occurs with combinations of the lubricity enhancer and
conductivity-improving
additives Cl, C2 and C3. On average, these combinations lose 70% or more of
the
conductivity they have in the absence of the lubricity enhancer.
Contrastingly, conductivity-
improving additive Al is much less affected by the presence of the lubricity
enhancer.
