Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVEMENTS IN FUELS
The present invention relates to improvements in fuels derived wholly or in
part
from animal or vegetable oil sources. Such fuels are called herein Bx fuels.
Bx fuels may be derived entirely from animal or vegetable oil sources (B100
fuels) or they may comprise a proportion of fuels derived from animal or
vegetable oil sources, admixed with fuels from other sources (for example
mineral sources, or synthetic sources, e.g. Fischer-Tropsch sources). For
example B20 herein is a fuel in which 20 wt% of the fuel is from animal or
vegetable oil sources and 80 wt% of the fuel is from other sources. The
proportion may be lower still, as in the case of, for example, a B5 fuel.
A problem has become apparent in Bx fuels: blocking of filters in distribution
systems and vehicles by precipitates in such fuels, typically at temperatures
above the cloud point (CP) of the fuels. The problems have been seen in a
wide range of Bx fuels, from B100 down to B5.
WO 2007/076163 describes such problems, and suggests that the problem of
filter blocking arises as a result of the precipitation of crystals of steryl
glycosides in fuels derived from biological sources. Steryl glycosides are
found in plants and it is suggested that they are carried over into Bx fuels.
WO 2007/076163 proposed a solution to the filter blocking problem; namely
the removal of the steryl glycosides, for example using an adsorbent as an
additive in conjunction with a process of filtration or centrifugation, or
both. In
one example soy biodiesel was filtered through a bed of diatomaceous earth.
The proposals of WO 2007/076163 have the disadvantage that a separation
step is needed, in addition to the treatment of the Bx fuel with the additive.
We are not bound by the explanation for the problem given in WO
2007/076163. We believe it might be more complex, for example also relating
to the total glycerides content, including monoglycerides, diglycerides and
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triglycerides, saturated or unsaturated. We are certainly of the view that
such
problems now seen in Bx fuels are connected with the Bx fuel component
which is derived from vegetable or animal sources, and are quite different
from
precipitation problems which have arisen in the past predominantly in mineral
fuels. The present invention seeks to solve this new problem notwithstanding
that an agreed scientific explanation of its nature or cause may follow.
By mineral fuels herein we mean fuels derived wholly from mineral (i.e.
petroleum) sources. By mineral fuel component herein we mean the mineral-
derived component in a Bx fuel.
Filter blocking problems can occur at temperatures below the cloud point in
mineral and other fuels. Such problems have been closely analysed over
many years. Additives have been developed that allow fuels to be used at
lower temperatures than would otherwise be possible.
The source of the problem of precipitation below the cloud point is the
presence of components such as so-called "waxes" (for example n-alkanes
and methyl n-alkanoates that crystallise at low temperatures). This may cause
the fuels to block filters and to become non-pourable.
Standardised tests have been devised to measure the temperature at which
the fuel hazes (the cloud point - CP), the lowest temperature at which a fuel
can flow (the pour point - PP) and the cold filter plugging point - CFPP); and
the changes thereto caused by additives (ACP, APP, ACFPP). The
standardised tests for measuring PP and, especially, CF and CFPP are among
the common working tools for persons skilled in the art. CF and CFPP may be
further described as follows:
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Cloud Point (CP)
The cloud point of a fuel is the temperature at which a cloud of wax crystals
first appears in a liquid when it is cooled under conditions prescribed in the
test
method as defined in ASTM D 2500.
Until recently, it was considered that problems arising from the formation of
precipitates would not occur at temperatures above the cloud point.
Cold Filter Plugging Point (CFPP)
At temperatures below the cloud point but above the pour point, the wax
crystals can reach a size and shape capable of plugging fuel lines, screens,
and filters even though the fuel will physically flow. These problems are well
recognized in the art and have a number of recognised test methods such as
the CFPP value (cold filter plugging point, determined in accordance with DIN
EN 116).
Tests such as these were introduced to give an indication of low temperature
operability as the cloud point test was considered to be too pessimistic.
The cold flow improvers (CFIs) and wax anti-settling additives (WASAs) which
have been devised considerably ameliorate the problems of precipitation below
the cloud point in fuels, and their effect can studied by the test methods
described above, comparing the results between unadditised fuels and
additised fuels.
Some such additives may assist in keeping the so-called "waxes" in solution in
the mineral fuel; others may alter their crystal morphology or size, so that
filterability and pourability are maintained in spite of precipitation.
The additives devised to deal with the problems arising from precipitation
below the cloud point have been very successful, to the extent that such
fuels,
suitably additised with, for example, CFIs (with or without WASAs), can be
used even in severe low temperature conditions. In many fuels the CFPP
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value may be lowered by 10-20 C, compared with corresponding fuels without
additives.
Additives are also known which improve the CFPP of Bx grades, including
B100 grade, and thus it would be expected that fuels treated in this way
should
have no operating problems even at temperatures significantly below the CF of
the fuels.
However, as noted above, the problems which have emerged in Bx fuels are
very different from those which can arise in mineral fuels. In particular the
precipitates cause filter blocking with Bx fuels at temperatures above the
cloud
point, whereas precipitation problems in mineral fuels occur below the cloud
point, and generally at much lower temperatures; and the chemical nature of
the precipitates is believed to be entirely different. As noted above the
origin of
the precipitation, though not fully understood, is believed to be entirely
different
- specific compounds found in animal or vegetable sources, and not found in
mineral sources. The testing regimes described above are inappropriate for
testing these precipitation issues in Bx fuels because they fail to predict
adequately the temperature at which filters are likely to block in real life
situations such as in storage, distribution and use in vehicles and heating
systems.
One of the reasons for this failure is believed to be that the precipitation
occurs
during a period of "cold soaking" over several hours or longer and therefore
is
not detected by tests such as Cloud Point or CFPP.
Critically, the precipitate does not redissolve when the temperature is raised
again. This is very different to conventional wax precipitation where at
temperatures above the cloud point, wax can readily redissolve, particularly
if
kept dispersed in the fuel through use of WASAs.
Without wishing to be bound by theory, we believe that the precipitates
causing
the problem of filter blocking at temperatures above the cloud point are
present
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as minor constituents within the B100 and are more soluble in the B100 than in
mineral fuels and hence in Bx blends. Furthermore, it is thought that as the
polarity of the mineral fuel is decreased for example removal of sulphur, the
solubility of these constituents will be even less and the problem will be
5 exacerbated.
In the light of differences, in the nature of these precipitation phenomena
below
and above the cloud point, additives developed to solve a problem arising from
precipitation below the cloud point, predominantly in mineral fuels, are not
promising starting points to solve a problem arising from precipitation in a
Bx
fuel, arising from the fuel component derived from an animal or vegetable oil.
Indeed, it must be borne in mind that Bx fuels have already contained
additives
of the type used to improve flow properties below the cloud point; and yet the
new problems of higher temperature filter blocking have still arisen.
However, we have now found that, unexpectedly, there is one class of additive
which is particularly effective at improving the flow properties, and hence
the
filterability, of Bx fuels above the cloud point. This class was already known
to
improve the flow properties of fuels below the cloud point. The finding of one
class of additive which:
(a) improves the flow properties of fuels having an animal or vegetable
origin above the cloud point, and
(b) improves the flow properties of fuels, including mineral fuels, below
the cloud point;
notwithstanding the different nature of the fuels and, in particular, the
different
nature of the respective problems and precipitates, is serendipitous.
In accordance with a first aspect of the present invention there is provided a
method of providing an improved Bx fuel, by the presence of an additive which
is the reaction product of (i) a compound containing the segment -NR1R2
where R1 represents a group containing from 4 to 44 carbon atoms and R2
represents a hydrogen atom or a group R1, and (ii) a carboxylic acid having
from 1 to 4 carboxylic acid groups or an acid anhydride or acid halide
thereof.
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Preferably R1 is a hydrocarbyl group or a polyethoxylate or polypropoxylate
group.
Preferably the group R1 is a hydrocarbyl group. Preferably the group R1 is
predominantly a straight chain group.
The term "hydrocarbyl" as used herein denotes a group having a carbon atom
directly attached to the remainder of the molecule and having a predominantly
aliphatic hydrocarbon character. Suitable hydrocarbyl based groups may
contain non-hydrocarbon moieties. For example they may contain up to one
non-hydrocarbyl group for every ten carbon atoms provided this non-
hydrocarbyl group does not significantly alter the predominantly hydrocarbon
character of the group. Those skilled in the art will be aware of such groups,
which include for example hydroxyl, halo (especially chloro and fluoro),
alkoxyl,
alkyl mercapto, alkyl sulfoxy, etc. Preferably the group R1 is an organic
group
entirely predominantly containing carbon and hydrogen atoms.
A hydrocarbyl group Rlis preferably predominantly saturated, that is, it
contain
no more than one carbon-to-carbon unsaturated bond for every few (for
example six to ten) carbon-to-carbon single bonds present. In the case of a
hydrocarbyl group R1 having from 4 to 10 carbon atom it may contain one
unsaturated bond. In the case of a hydrocarbyl group R1 having from 11 up to
20 carbon atom it may contain up to two unsaturated bonds. In the case of a
hydrocarbyl group R1 having from 21 up to 30 carbon atom it may contain up to
three unsaturated bonds. In the case of a hydrocarbyl group R1 having from
31 up to 40 carbon atom it may contain up to four unsaturated bonds. In the
case of a hydrocarbyl group R1 having from 41 up to 44 carbon atom it may
contain up to five unsaturated bonds. Preferably, however, a hydrocarbyl
group R1 is preferably a fully saturated alkyl group, preferably a fully
saturated
n-alkyl group.
Preferably a group R1 comprises from 6 to 36 carbon atoms, preferably 8 to
32, preferably 10 to 24, preferably 12 to 22, most preferably 14 to 20.
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It will be appreciated that the group 1:11 will typically include moieties
with a
range of carbon atoms. The definitions C4-44 ............................ C14-
22 are not intended to
denote that all R1 groups must fall within the stated range.
The group R2, when present, preferably conforms to the same definitions as
are given for R1. R1 and R2 need not be the same. Preferably, however, R1
and R2 are the same.
Preferably the species (ii) is a carboxylic acid or an acid anhydride thereof.
However if an acid halide is used it is preferably an acid chloride.
Suitable compounds (i) include primary, secondary, tertiary and quaternary
amines. Tertiary and quaternary amines only form amine salts.
Secondary amines, of formula HNR1R2, are an especially preferred class of
compounds (i).
Examples of especially preferred secondary amines include
di-octadecylamine, di-cocoamine, di-hydrogenated tallow amine and
methylbehenyl amine. Amine mixtures are also suitable such as those derived
from natural materials. A preferred amine is a secondary hydrogenated tallow
amine, the alkyl groups of which are derived from hydrogenated tallow fat
composed of approximately 3-5%wt C14,30-32%wt C16, and 58-60%wt C18.
Quaternary amines, of formula [+NR1R2R3R4 ¨An], are an especially preferred
class of compounds (i). R1 and R2 are as defined above (but R2 is not
hydrogen). R3 and R4 independently represent a C(1-4) alkyl group, preferably
propyl, ethyl or, most preferably, methyl. +NR1R2(CH3)2 represents a preferred
cation. ¨An represents the anion. The anion may be any suitable species but
is preferably a halide, especially a chloride. Where (i) comprises a
quaternary
amine, the reaction conditions may be adjusted to assist the reaction between
(i) and (ii). Preferably the reaction conditions are adjusted by the
introduction
of an auxiliary base. The auxiliary base is preferably an inorganic base, such
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as sodium methoxide, sodium ethoxide, or sodium hydroxide. Preferably the
inorganic base is a metal alkoxide or metal hydroxide. Alternatively, the
quaternary amine salt may be preformed as the corresponding basic salt, for
example, a quaternary ammonium hydroxide or alkoxide.
Also preferred are mixtures of primary and secondary amines, as species (i).
Also preferred are mixtures of secondary and quaternary amines, as species
(ii).
Preferred carboxylic acids include carboxylic acids containing two, three or
four
carboxylic acid groups, and acid anhydrides and acid halides thereof.
Examples of suitable carboxylic acids and their anhydrides include
aminoalkylenepolycarboxylic acids, for example nitrilotriacetic acid,
propylene
diamine tetraacetic acid, ethylenediamine tetraacetic acid, and carboxylic
acids
based on cyclic skeletons, e.g., pyromellitic acid, cyclohexane-1,2-
dicarboxylic
acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid
and naphthalene dicarboxylic acid, 1,4-dicarboxylic acids, and dialkyl
spirobislactones. Generally, these acids have about 5 to 13 carbon atoms in
the cyclic moiety. Preferred acids useful in the present invention are
optionally
substituted benzene dicarboxylic acids, e.g. phthalic acid, isophthalic acid,
and
terephthalic acid, and their acid anhydrides or acid chlorides.
Optional
substituents include 1-5 substituents, preferably 1-3 substituents,
independently selected from C(1-4)alkyl, C(1-4)alkoxy, halogen, C(1-
4)haloalkyl, C(1-4)haloalkoxy, nitrile, -COOH, -00-0C(1-4)alkyl, and ¨
CONR3R4 where R3 and R4 are independently selected from hydrogen and C(1-
4)alkyl. Preferred halogen atoms are fluorine, chlorine and bromine. However
unsubstituted benzene carboxylic acids are preferred. Phthalic acid and its
acid anhydride are particularly preferred.
Preferably the molar ratio of compound (i) to acid, acid anhydride or acid
halide
(ii) is such that at least 50% of the acid groups (preferably at least 75%,
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preferably at least 90%, and most preferably 100%) are reacted in the reaction
between the compounds (i) and (ii), for example to form the amide and/or the
amine salt.
Where compound (ii) comprises one or more free carboxylic acid groups,
reaction conditions may be adjusted to allow reaction between compounds (i)
and (ii), for example to form the respective amide or amine salt. The reaction
conditions may be adjusted by raising reaction temperatures. The reaction
conditions may be adjusted by including a dehydrating agent within the
reaction mixture. The one or more carboxylic acid groups may be activated in
situ ready for coupling (i) and (ii), for example, by the use of such as
carbodiimides (eg. EDCI). However, where activated forms of (ii) are
employed, the activated forms of (ii) are preferably preformed, for example,
as
acid halides or acid anhydrides. Acid anhydrides are most preferred.
In the case of a preferred reaction, between a compound (i) and a dicarboxylic
acid, or acid anhydride or acid halide thereof, preferably the molar ratio of
compound (i) (or mixtures of compounds (i), in that situation) to acid, acid
anhydride or acid halide (ii) (or mixed compounds (ii), in that situation) is
at
least 0.7:1, preferably 1:1, preferably at least 1.5:1. Preferably it is up to
3:1,
preferably up to 2.5:1. Most preferably it is in the range 1.8:1 to 2.2:1. A
molar
ratio of 2:1, (i) to (ii) is especially preferred. Also preferred is a molar
ratio of
1:1.
It will be understood by those skilled in the art that compound (ii) is
defined as
the original starting material. However, preferred products may be obtained by
step-wise reactions involving reacting compound (i) with an adduct of
compound (ii), particularly where (ii) has already reacted in with a compound
(i)
to form an intermediate. Such an intermediate may be fully isolated or
partially
isolated so as to allow step-wise reactions. Such an intermediate may
comprise a mono-amide/mono-carboxylic acid adduct, for instance, where in a
first step a first equivalent of (i) is reacted with a dicarboxylic acid, acid
anhydride, or acid halide. Partial isolation may therefore be mere isolation
of
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the reaction mixture resulting from the first step of a reaction to form the
mono-
amide/mono-carboxylic acid. In such circumstances, a subsequent reaction of
compound (i) (optionally a different compound (i) than that used in the first
step) with the mono-amide/mono-carboxylic acid adduct may yield further
5 derivatives, for instance, a diamide or a mono-amide/ammonium carboxylate
salt. Such a step-wise process provides for greater selectivity of either or
both
of an amide group and/or an ammonium salt, especially where the amines of
said amide group and said ammonium group are different, such as when (i)
essentially comprises more than one amine.
In the case of a preferred reaction, between a secondary amine as the only
compound (i) and a dicarboxylic acid, or acid anhydride or acid halide
thereof,
preferably the molar ratio of amine (i) to acid, acid anhydride or acid halide
(ii)
is at least 1:1, preferably at least 1.5:1. Most preferably it is in the range
1.8:1
to 2.2:1. A molar ratio of 2:1, (i) to (ii) is especially preferred.
In the case of another preferred reaction, between a quaternary ammonium
salt as the only compound (i) and a dicarboxylic acid, or acid anhydride or
acid
halide thereof, preferably the molar ratio of quaternary ammonium salt (i) to
acid, acid anhydride or acid halide (ii) is at least 1:1, preferably at least
1.5:1.
Most preferably it is in the range 1.8:1 to 2.2:1. A molar ratio of 2:1, (i)
to (ii) is
especially preferred.
Preferred reaction products for use in this invention contain at least the
mono-
amide adduct and quaternary ammonium salt and this may be achieved by
using a mixture of compounds as compound (i), preferably both a secondary
amine and a quaternary ammonium compound.
Another preferred reaction employs both a secondary amine and a quaternary
ammonium salt as compounds (i). Preferably the ratio of the secondary amine
to the quaternary ammonium salt in the reaction mixture is 30-70% to 70-30%
molar/molar, preferably 40-60% to 60-40%, and most preferably they are
present in equimolar amounts. Consistent with what is stated above,
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therefore, this reaction employs in its most preferred embodiment equimolar
amounts of the secondary amine, the quaternary ammonium salt and the acid,
acid anhydride or acid halide (ii).
Preferably the reaction between the compound (i) and the carboxylic acid, acid
anhydride or acid halide forms one or more amide, imide or ammonium salts,
combinations of these within the same compound, and mixtures of these
compounds.
Thus, in one preferred embodiment a dicarboxylic acid, acid anhydride or acid
halide is reacted with a secondary amine in a mole ratio of 1:2 such that one
mole of the amines form an amide and one mole forms an ammonium salt.
An especially preferred additive is a N,N-dialkylammonium salt of 2-NI,Ni-
dialkylamide benzoic acid, which suitably is the reaction product of
di(hydrogenated) tallow amine (i) and phthalic acid or its acid anhydride
(ii);
preferably at a molar ratio of 2:1.
An especially preferred additive is the reaction product of di(hydrogenated)
tallow amine (i) and phthalic acid or its acid anhydride (ii); preferably at a
molar
ratio of 1:1.
Other preferred additives are the reaction products (hydrogenated) tallow
amine with EDTA reaction in a molar ratio of 4:1 with removal of four moles of
water or two moles of water to form respectively the tetraamide derivative or
the diamide diammonium salt derivative.
Another preferred additive is the reaction product of one mole of
alkylspirobislactone, for example dodecenyl-spirobislactone with one mole of
mono-tallow amine and one mole of di-tallow amine.
The fuel composition of the present invention may contain at least 1 wt% of
fuel derived from animal or vegetable sources, for example at least 2 wt%, at
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least 3 wt%, at least 4 wt%, at least 5 wt%, at least 6 wt%, at least 8 wt%,
or at
least 10 wt%, of fuel derived from animal or vegetable sources. Some
embodiments may contain at least 15 wt%, or at least 20 wt%, of fuel derived
from animal or vegetable sources. The fuel composition may contain up to 99
wt% of fuel derived from animal or vegetable sources, for example up to 95
wt%, up to 90 wt%, up to 85 wt%, up to 80 wt%, up to 75 wt%, up to 70 wt%,
up to 60 wt%, up to 50 wt%, up to 40 wt%, up to 30 wt%, up to 25 wt%, up to
20 wt%, up to 15 wt%, or up to 12 wt%, of fuel derived from animal or
vegetable sources.
A fuel which comprises 100% fuel produced from an animal or vegetable
source is denoted as B100, a fuel which comprises 90% mineral diesel and
10% biodiesel is known as B10; fuel comprising 50% mineral diesel and 50%
biodiesel is known as B50; and so on.
Fuel of animal or vegetable origin may include ethyl or methyl esters of fatty
acids of biological origin. Starting materials for the production of such fuel
include, but are not limited to, materials containing fatty acids. These
materials
include, without limitation, triacylglycerols, diacylglycerols,
monoacylglycerols,
phospholipids, esters, free fatty acids, or any combinations thereof. The
diesel
is produced by incubating the material including the fatty acids with a short
chain alcohol in the presence of heat, pressure, a catalyst, or combinations
of
any thereof to produce fatty acid esters of the short chain alcohols.
The fatty acids used to produce the fuel may originate from a wide variety of
natural sources including, but not limited to, vegetable oil, canola oil,
safflower
oil, sunflower oil, nasturtium seed oil, mustard seed oil, olive oil, sesame
oil,
soybean oil, com oil, peanut oil, cottonseed oil, rice bran oil, babassu nut
oil,
castor oil, palm oil, palm oil, rapeseed oil, low erucic acid rapeseed oil,
palm
kernel oil, lupin oil, jatropha oil, coconut oil, flaxseed oil, evening
primrose oil,
jojoba oil, camelina oil, tallow, beef tallow, butter, chicken fat, lard,
dairy
butterfat, shea butter, used frying oil, oil miscella, used cooking oil,
yellow trap
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grease, hydrogenated oils, derivatives of the oils, fractions of the oils,
conjugated derivatives of the oils, and mixtures of any thereof.
Preferably the precipitates which form above the cloud point and which the
present invention seeks to combat are not revealed by cloud point test ASTM
D 2500.
Preferably the precipitates which form above the cloud point and which the
present invention seeks to combat are not revealed immediately merely by
cooling the fuel to a given temperature. Preferably they form following an
incubation period, by holding the fuel at a temperature above the cloud point
for a incubation period. Preferably the incubation period is at least 4 hours,
preferably at least 12 hours, preferably at least 16 hours, preferably at
least 48
hours, preferably at least 96 hours.
Preferably the precipitates which form above the cloud point and which the
present invention seeks to combat are not removed merely by raising the
temperature of the fuel above the temperature at which they formed.
Preferably the Bx fuel is a middle distillate fuel, generally boiling within
the
range of from 110 to 500, e.g. 150 to 400 C. Preferably it is a Bx fuel for
use
in diesel engines or heating fuel oil.
In one embodiment the fuel is B100. Preferably however the fuel is a blend of
fuel derived from animal or vegetable sources and fuel derived from mineral
sources and/or synthetic sources (e.g. FT fuels, derived from the Fischer-
Tropsch process).
Preferably the fuel is a blend of a fuel derived from vegetable sources and a
fuel derived from non-vegetable sources; preferably from mineral sources.
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The Bx fuel may contain other flow-improving additives to provide the usual
benefits, in reducing the CF and CFPP. Such compounds may include CFIs
and WASAs.
Examples of such additives and their use in petroleum-based oils are
described in US 3048479; GB 1263152; US 3961916; US 4211534; EP
153176A; and EP 153177A.
US 3048479 describes ethylene-vinyl ester pour depressants for middle
distillates. GB 1263152 describes distillate petroleum oil compositions
containing ethylene ester copolymers. The preferred copolymers are of
ethylene and vinyl acetate. US 3961916 describes middle distillate
compositions with improved filterability containing mixtures of two different
EVA copolymers. US 4211534 describes combinations of ethylene polymer,
polymer having alkyl side chains, and nitrogen containing compound to
improve cold flow properties of distillate fuel oils. EP 153176A and EP
153177A describe polymers or copolymers containing an n-alkyl ester of a
mono-ethylenically unsaturated C4 to C8 mono- or dicarboxylic acid.
Use of an ethylene vinyl acetate copolymer as a CFI in conjunction with an
adduct of compounds (i) and (ii) as defined herein, is especially preferred.
Preferably the Bx fuel is a low sulphur content fuel, preferably having a
sulphur
content less than 200 ppm, preferably less than 100 ppm, preferably less than
50 ppm, preferably less than 20 ppm, preferably less than 15 ppm, preferably
less than 10 ppm.
Preferably the additive is present in the fuel in an amount (as active
material)
of from 5 mg/kg fuel, preferably from 10 mg/kg fuel, preferably from 20 mg/kg
fuel, preferably from 30 mg/kg fuel.
Preferably the additive is present in the fuel in an amount (as active
material)
up to 500 mg/kg, preferably up to 200 mg/kg fuel, preferably up to 100 mg/kg
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fuel, preferably up to 80 mg/kg fuel, preferably up to 60 mg/kg fuel,
preferably
up to 45 mg/kg fuel.
The additive may be added to Bx fuel which is known to exhibit a filtration
5 problem above the cloud point, to reduce the problem or, preferably, to
obviate
the problem by preventing precipitation above the cloud point.
Reducing or solving the problem may be achieved by reducing the size or
quantity of the precipitates which may appear in the Bx fuel above the cloud
10 point, or by controlling the morphology of the precipitates in the Bx
fuel above
the cloud point.
Preferably, however, the additive is added to Bx fuel in order to prevent the
emergence of precipitates above the cloud point. By preventing the
15 emergence of precipitates above the cloud point we mean that detectable
precipitates do not appear in the Bx fuel under normal storage or use
conditions.
In accordance with a second aspect of the present invention there is provided
the use of an additive which is the reaction product of (i) a compound
containing the segment -NR1R2 where R1 represents a group containing from 4
to 44 carbon atoms and R2 represents a hydrogen atom or a group R1, and (ii)
a carboxylic acid having from 1 to 4 carboxylic acid groups or an acid
anhydride or acid halide thereof, in order to maintain the filterability of
the Bx
fuel above the cloud point of the Bx fuel.
In accordance with a third aspect of the present invention there is provided
the
use of an additive which is the reaction product of (i) a compound containing
the segment -NR1R2 where R1 represents a group containing from 4 to 44
carbon atoms and R2 represents a hydrogen atom or a group R1, and (ii) a
carboxylic acid having from 1 to 4 carboxylic acid groups or an acid anhydride
or acid halide thereof in order to prevent the emergence of precipitates in
the
Bx fuel above the cloud point of the Bx fuel.
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Aspects and preferred features described above following presentation of the
first
aspect apply also to the second aspect and third aspect, including: ways in
which
filterability may be maintained; ways in which precipitation may be
controlled, inhibited
or prevented; preferred compounds (i) and (ii); preferred ratios of (I) to
(II); preferred Bx
fuels; and preferred concentrations of the additive in the Bx fuel.
In accordance with a fourth aspect of the present invention there is provided
a Bx fuel
having improved flow properties above the cloud point of the Bx fuel, the fuel
comprising
an additive which is the reaction product of (i) a compound containing the
segment -
NR1R2 where R1 represents a group containing from 4 to 44 carbon atoms and R2
represents a hydrogen atom or a group R1, and (ii) carboxylic acid having from
1 to 4
carboxylic acid groups or an acid anhydride or acid halide thereof.
In accordance with a fifth aspect of the present invention there is provided
an additive
composition comprising an additive which is the reaction product of (i) a
compound
containing the segment -NR1R2 where R1 represents a group containing from 4 to
44
carbon atoms and R2 represents a hydrogen atom or a group R1, and (ii) a
carboxylic
acid having from 1 to 4 carboxylic acid groups or an acid anhydride thereof in
a solvent.
In accordance with a sixth aspect of the present invention there is provided a
method of
improving the filter blocking tendency of a Bx fuel by addition of an additive
as defined
herein.
In accordance with an aspect of the present invention, there is provided a
method of
treating a Bx fuel in order to improve the filterability of the Bx fuel above
the cloud point
of the Bx fuel, by addition of a reaction product of (i) a compound containing
a segment
-NR1R2 where R1 represents a group containing from 4 to 44 carbon atoms and R2
represents a hydrogen atom or a group R1, and (ii) a carboxylic acid having
from 1 to 4
carboxylic acid groups or an acid anhydride or acid halide thereof, wherein
the Bx fuel
comprises fuel derived from animal or vegetable oil sources admixed with fuel
derived
from mineral or synthetic sources; wherein the Bx fuel has a sulphur content
less than
200ppm; wherein the Bx fuel contains at least 4 wt% of fuel derived from
animal or
CA 02751628 2012-05-07
16a
vegetable sources; and wherein the reaction product is present in the Bx fuel
in an
amount, as active material, of from 10 mg/kg up to 200 mg/kg.
In accordance with another aspect of the present invention, there is provided
a Bx fuel
comprising a fuel additive which is the reaction product of (i) a compound
containing a
segment -NR1R2 where R1 represents a group containing from 4 to 44 carbon
atoms
and R2 represents a hydrogen atom or a group R1, and (ii) an optionally
substituted
benzene dicarboxylic acid or an acid anhydride or acid halide thereof, wherein
the Bx
fuel has a sulphur content less than 200ppm and contains at least 4 wt% of
fuel derived
from animal or vegetable sources; and wherein the additive is present in the
Bx fuel in
an amount, as active material, of from 10 mg/kg up to 200 mg/kg so as to
provide
improved filterability of the Bx fuel above the cloud point of the Bx fuel.
The invention will now be further described, by way of example, with reference
to the
following test descriptions.
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17
Example Set A
The tests involved using a modified version of the IP387 (Determination of
filter
blocking tendency of gas oils and distillate diesel fuels) method.
In the IF 387 method, a sample of the fuel to be tested is passed at a
constant
rate of flow through a glass fibre filter medium. The pressure drop across the
filter is monitored, and the volume of fuel passing the filter medium within a
prescribed pressure drop is measured.
The filter blocking tendency (FBT) can be described in one of the following
ways:
- The pressure drop (P) across a GF/A (glass fibre) filter medium
for 300 ml of fuel to pass at a rate of 20 ml/min is recorded.
- The volume of fuel (v) passed when a pressure of 105kPa is
reached. This method of report is used when less than 300 ml
passes at that pressure drop.
The FBT may be expressed on a single scale by combining these using the
following formulae
FL T = 111+ r ' 2 and i r 300` 2
F B-r = 11.+ _
,IOS, V2
Thus when exactly 300m1 passes through the filter at a pressure of 105 kPa,
the FBT is 1.41. Values of FBT >1.41 indicate that less than 300 ml pass
through the filter before a pressure of 105 kPa is reached. Values of FBT
<1.41 indicate that 300m1 pass through the filter at a pressure of less than
105kPa
An FBT <1.4 is considered to be a good result.
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The modification to the IF 387 method relates to thermal conditioning and cold
soak of a sample being tested.
1. the sample is heated to a temperature of 60 C for 3 hours and then
allowed to cool to 20 C.
2. The sample is then cooled to 5 C for 16 hours and then allowed to
warm to room temperature.
Following this conditioning, the Filter Blocking Tendency is determined using
IF 387.
The base fuel used in these tests was a B5 fuel which met the requirements of
DIN EN 590 and contained a commercially available cold flow additive
believed to comprise EVA copolymers in an amount effective to achieve a
CFPP of <-15 C. The fuel had the following properties:
Method Method Number Result
Density at 1F365 0.8417g/m1
C
CFPP IF 309 -17 C
Cloud Point ASTM D5772 -5.8 C
Distillation IF 123
IBP 175.5 C
5% 195.9 C
10% 206.4 C
20% 226.0 C
30% 244.0 C
40% 260.5 C
50% 275.0 C
60% 288.7 C
70% 302.3 C
80% 317.2 C
90% 335.3 C
95% 348.6 C
FBP 359.5 C
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Testing was carried out using
a) this base fuel,
b) this base fuel additised with 37.5 mg/kg of Compound A, and
c) this base fuel additised with a commercial WASA (believed to be a nitrogen-
containing polymeric WASA) long used with success to improve the flow
properties of mineral diesel fuels below the cloud point.
To prepare Compound A phthalic anhydride (7.4g) was mixed with di
(hydrogenated tallow) amine (Commercially available as Armeen 2HT)
(50.02g) at a molar ration of 1:2 in Shellsol AB solvent (57.5g). The reaction
mixture was heated at 65 C for approximately 6hours.
The results are as follows:
Sample (a) base fuel (b) base fuel (c) base fuel
+ 37.5 mg/kg + 150 mg/kg
Compound A WASA
Filter Blocking 1.8 1.23 1.87
Tendency
Initial pressure 10 10 10
(kPa)
Final pressure 105 75 105
(kPa)
Volume filtered 200 300 190
(ml)
Test temperature 23 23 23
(2C)
Using Compound A allowed all 300 ml of the fuel to pass through the filter
without the pressure reaching 105 kPa. The
improvement over the
performance of the base fuel is very marked. In contrast it is observed that
the
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commercial WASA, at a higher treat rate, causes no discernable improvement
in the flow properties of the base fuel.
Example Set B
5
In Example Set B the testing was the same as in Example Set A but the base
fuel ("Basefuel 2") also met the requirements of DIN EN90 and was a B10 fuel
prepared from a standard diesel meeting the specifications of CEC Fuel
Specification RF-06-03, blended with rapeseed methyl ester (RME) and a
10 commercially available cold flow additive believed to comprise EVA
copolymers in an amount effective to achieve a CFPP of < -15 C.
The FBT of Basefuel 2 was 2.52.
15 The FBT of Basefuel 2 additised with 37.5 mg/kg of Compound A was 1.03.
The FBT of Basefuel 2 additised with 150 mg/kg of WASA (believed to be a
nitrogen-containing polymeric WASA) was 2.03.
