Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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USE OF A DETERGENT ADDITIVE
Field of the Invention
The present invention relates to the use of a
detergent additive in a fuel composition for reducing
microbial growth.
Background of the Invention
Fuel tanks and distribution systems provide an
environment where microorganisms can flourish. There are
three main types of spoilage and corrosive hydrocarbon-
utilising microorganisms in fuel systems, namely
bacteria, yeasts and moulds, the latter two often named
as fungi. Microbes are ubiquitous and can infect fuel at
any point in the distribution chain, surviving and
proliferating in water/aqueous phase associated with the
fuel and drawing their nutrients across the fuel/water
interface (most nutrients diffuse into the cell in
aqueous solution). Microbes require elements such as
carbon, hydrogen, sulphur, nitrogen and phosphorus in
substantial amounts, trace amounts of other elements and
some form of oxygen. The rate and type of microbial
proliferation is dependent on factors such as water phase
pH, oxygen availability, ambient temperature, nutrient
availability, etc. Optimum growth is achieved in the
temperature range 15 C to 40 C and a neutral/slightly
acidic pH. Most of these conditions are met in fuel
tanks and distribution systems thereby providing an ideal
environment for microbial growth. Water as one key
contributor exacerbates the situation and can never be
completely eradicated due to condensation effects,
leaking tank roofs, poor housekeeping, etc. A fuel
storage system is therefore never sterile and at best,
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the aim is to restrict microbial growth to an acceptable
level by the adoption of good housekeeping practices.
There are several undesirable consequences of
microbial growth in fuel systems. One such consequence
is Microbially Induced Corrosion (MIC) which is corrosion
that is caused by or promoted by microorganisms.
Microbial cells can exist in planktonic (single
cells floating/swimming in the fuel) or sessile forms
(attached to a surface). A biofilm forms when a
collection of microorganisms (mainly bacteria) adhere
irreversibly to a surface and begin to excrete slimy,
extracellular biopolymers. Biofilms enhance microbial
interactions, giving more access to nutrients,
environmental stability, protection from viruses and
biocides. These microbial communities can attach to the
sidewalls and bottoms of fuel storage tanks causing
Microbially Induced Corrosion (MIC).
MIC is one of the most serious consequences of
microbial growth. Aerobes produce organic acids and
deplete oxygen supplies, creating an oxygen-deficient
zone around them. Oxygen gradients develop causing the
formation of anodic corrosion pits. Sulphate Reducing
Bacteria (SRB) can increase this corrosion by producing
H25, HS and S2f all of which are very aggressive to
steel.
Other consequences of microbial growth in fuel
systems are blocked filters, valves and pipelines,
increased pump wear and production of biosurfactants that
can cause stable water hazes and coalescer disarming. In
particular, fungi are implicated in filter blocking in
vehicle fuel systems. Fuel filter plugging is often
caused by mould growth, which manifests itself as a mat
of hyphae (long filaments of fungi) at the fuel/water
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interface. Loss of product quality, foul odour,
cloudiness and discolouration and injector fouling can
also be undesirable consequences of microbial growth.
Biofuels (e.g. FAMEs) can play a role in fossil fuel
replacement to meet reduction targets of greenhouse gas
emissions. Globally, many countries have established or
are developing biofuel mandates, with some countries
(e.g. Indonesia) introducing B30 (30% biofuel), which is
well above the current EU mandated levels of B7 (7%
biofuel). However, it is well established that biodiesel
and its blends, particularly at the EU mandated levels,
are more susceptible to microbial growth than
conventional hydrocarbon diesel. The reasons cited for
this are that FAME is easier for microorganisms to digest
and more hydroscopic than conventional diesel leading to
greater free water entrainment.
Gas-to-liquid (GTL) technology converts CH4/methane
currently from natural gas - the cleanest-burning fossil
fuel - into high-quality liquid fuel products that would
otherwise be made from crude oil. GTL fuel can help to
reduce local emissions in conventional diesel vehicles.
GTL fuel also has other applications, e.g. as a synthetic
marine fuel in inland water way vessels in conventional
marine diesel engines. It is known that GTL fuel is more
biodegradable than conventional diesel due to its
negligible aromatic content and simple structure (it is
fully saturated) but may be more susceptible to microbial
growth than conventional diesel. Fuel handling and
storage conditions with respect to microbial growth could
be considered as even more severe for inland water way
vessels than for road applications due to the potential
presence of water inside the tank, during fuelling and on
board bunker ships.
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Attempts have been made in the past to solve
microbial spoilage incidents in fuels and fuel systems.
Chemical treatments such as biocides and biostats are
currently used to control and eliminate microbial growth
in fuel systems in conjunction with physical control
methods such as good housekeeping, settling, filtration,
centrifugation and heat treatment.
Unfortunately, chemical treatments by their nature
are toxic and their handling presents serious health,
safety and environmental issues. The commonly used
isothiazolinone chemistry, for example, is a skin
sensitiser. Further, it is necessary to dispose of waste
biomass after chemical treatment which can be time
consuming and expensive.
It would therefore be desirable to provide
alternative ways of reducing microbial growth in fuels
and fuel systems.
Summary of the Invention
According to the present invention there is provided
the use of a detergent additive in a fuel composition for
reducing microbial growth.
According to another aspect of the present invention
there is provided a method for reducing microbial growth
in a fuel composition, which method comprises a step of
introducing a detergent additive into said fuel
composition.
It has been found that use of a detergent additive
as described herein can reduce the microbial growth in a
fuel composition to which the detergent additive is
added. Hence, the invention can lead to a reduction in
microbial spoilage incidents in a wide range of fuel
compositions.
Brief Description of the Drawings
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Figure 1 is a graphical representation of the
experimental data generated in Example 1.
Figure 2 is a graphical representation of the
experimental data set out in Table 5 below, and in
particular shows the average dry biomass weight (g) after
4 weeks and after 12 weeks of fuels tested in Example 2
below, with and without additive.
Figure 3 is a graphical representation of the
experimental data set out in Table 5 below, and in
particular shows the average dry biomass weight (g) for
all fuel formulations tested in Example 2 below with and
without Performance Additive Package 2, Performance
Additive Package 3, Detergent Additive 1 and Detergent
Additive 2.
Detailed Description of the Invention
As used herein there is provided the use of a
detergent additive in a fuel composition for reducing
microbial growth in said fuel composition.
In the context of this aspect of the invention, the
term "reducing microbial growth" embraces any degree of
reduction in microbial growth. Microbial growth may be
measured by any suitable method such as the biomass
method described in the Examples below. The reduction in
microbial growth may be of the order of 10% or more,
preferably 20% or more, more preferably 50% or more, and
especially 70% or more compared to the microbial growth
in an analogous fuel composition which does not contain a
detergent additive, in particular during the time period
where the fuel composition is stored in a fuel tank, for
example a time period of up to 12 weeks. As used herein,
the term "reducing microbial growth" also encompasses the
prevention of microbes growing in the first place.
The present invention is relevant for a wide range
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of fuel applications such as diesel fuels, heating oils,
aviation fuels, marine fuels, and mixtures thereof.
Preferred fuel applications include diesel fuels and
aviation fuels.
A first essential component herein is a detergent
additive, by which is meant an agent (suitably a
surfactant) which can act to remove, and/or to prevent
the build-up of, combustion related deposits within an
engine, in particular in the fuel injection system such
as in the injector nozzles. Such materials are sometimes
referred to as dispersant additives.
Detergent-containing diesel fuel additives are known
and commercially available. Examples of suitable
detergent additives include, but are not necessarily
limited to, polyolefin substituted succinimides or
succinimides of polyamines, aliphatic amines, Mannich
bases or amines, polyolefin maleic anhydrides, and
quaternary ammonium salts, and mixtures thereof. A
preferred detergent additive for use herein is a
nitrogen-containing detergent. In one embodiment, the
detergent additive for use herein is a polyolefin
substituted succinimide, such as a polyisobutylene
succinimide. In another embodiment, the detergent
additive for use herein is a quaternary ammonium salt.
Many of the detergents mentioned above are nitrogen-
containing detergents. With nitrogen being an essential
nutrient for microbes, it is particularly surprising that
the nitrogen-containing detergents mentioned above have
been found to reduce microbial growth when included in a
fuel composition.
Fuel additives can encourage water entrainment in
fuel due to their surfactant nature, particularly at
higher treat rates, and also act as food sources;
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additives containing the essential nutrient nitrogen are
particularly important. Therefore, it would be
reasonable to assume that fuels blended with performance
additives, especially nitrogen-containing performance
additives, such as nitrogen-containing detergents, are
more conducive to microbial attack. It has been
surprisingly found by the present inventors that
detergent additives, such as nitrogen-containing
detergents, have surprisingly been found to inhibit
microbial growth in a fuel composition. In particular,
it has been found that detergent additives, such as
nitrogen-containing detergents, have surprisingly been
found to inhibit microbial growth in a fuel composition,
wherein the microbes are fungal species. This is
particularly advantageous as filamentous fungi are
implicated in filter blocking problems.
The detergent additive is preferably present in the
fuel composition at a level from 5 ppmw to 10000ppmw,
preferably 5 ppmw to 1000ppmw, more preferably in the
range 5 to 500 ppmw, even more preferably in the range
from 10 to 200 ppmw active matter detergent based on the
overall fuel composition.
In one embodiment of the present invention the
detergent additive is a component of a detergent additive
package together with one or more other additive
components. Examples of other suitable additive
components are provided in more detail hereinbelow.
The diesel fuel compositions described herein may
comprise a diesel base fuel in addition to the detergent
additive.
The diesel base fuel may be any petroleum derived
diesel suitable for use in an internal combustion engine,
such as a petroleum derived low sulphur diesel comprising
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<50 ppm of sulphur, for example, an ultra-low sulphur
diesel (ULSD) or a zero sulphur diesel (ZSD).
Preferably, the low sulphur diesel comprises <10 ppm of
sulphur.
The petroleum derived low sulphur diesel preferred
for use in the present invention meets the EN590
specification. It will typically have a density from
0.81 to 0.865, preferably 0.82 to 0.85, more preferably
0.825 to 0.845 g/cm3 at 15 C; a cetane number (ASTM D613)
of at least 51; and a kinematic viscosity (ASTM D445)
from 1.5 to 4.5, preferably 2.0 to 4.0, more preferably
from 2.2 to 3.7 mm2/s at 40 C.
In one embodiment, the diesel base fuel is a
conventional petroleum-derived diesel.
A further preferred component of the fuel composition
herein is a biodiesel fuel. Biodiesel fuels are fuels
which derive from biological materials.
The biodiesel component is preferably present in the
fuel composition herein at a level of 5% v/v or greater up
to a level of 50% v/v, preferably from 5% v/v to 30% v/v,
for example at levels of 7%v/v, 10%v/v, 20%v/v and 30%v/v.
In one embodiment of the present invention, the fuel
composition herein is free of biodiesel component (i.e. a
so-called 'BO' fuel).
A preferred biodiesel component for use herein is a
fatty acid alkyl ester (FAAE). It is known to include
fatty acid alkyl esters (FAAEs), in particular fatty acid
methyl esters (FAMEs), in diesel fuel compositions.
Examples of suitable FPLAEs include rapeseed methyl ester
(RME), palm oil methyl ester (POME), and soy methyl ester
(SME). FAAEs are typically derivable from biological
sources and are typically included to reduce the
environmental impact of the fuel production and
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consumption process or to improve lubricity.
PAAEs, of which the most commonly used in the context
of diesel fuels are the methyl esters, are already known
as renewable diesel fuels (so-called 'biodiesel' fuels).
They contain long chain carboxylic acid molecules
(generally from 10 to 22 carbon atoms long), each having
an alcohol molecule attached to one end. Organically
derived oils such as vegetable oils (including recycled
vegetable oils) and animal fats (including fish oils) can
be subjected to a transesterification process with an
alcohol (typically a Ci to C5 alcohol) to form the
corresponding fatty esters, typically mono-alkylated.
This process, which is suitably either acid- or base-
catalysed, such as with the base KOH, converts the
triglycerides contained in the oils into fatty acid
components of the oils from their glycerol backbone.
PAAEs can also be prepared from used cooking oils, and can
be prepared by standard esterification from fatty acids.
In the present invention, the PAAE may be any
alkylated fatty acid or mixture of fatty acids. Its fatty
acid component(s) are preferably derived from a biological
source, more preferably a vegetable source. They may be
saturated or unsaturated; if the latter, they may have one
or more, preferably up to 6, double bonds. They may be
linear or branched, cyclic or polycyclic. Suitably, they
will have from 6 to 30, preferably 10 to 30, more suitably
from 10 to 22 or from 12 to 24 or from 16 to 18, carbon
atoms including the acid group(s) -CO2H. A PAAE will
typically comprise a mixture of different fatty acid
esters of different fatty acid esters of different chain
lengths, depending on its source.
A preferred PAAE for use in the present invention is
selected from a natural fatty oil, for instance tall oil,
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rapeseed oil, palm oil or soy oil.
The FAAE is preferably a C1 to C5 alkyl ester, more
preferably a methyl, ethyl, propyl, (suitably iso-propyl)
or butyl ester, yet more preferably a methyl or ethyl
ester and in particular a methyl ester. In one embodiment
herein, the FAAE is selected from methyl ester of palm oil
(POME) and methyl ester of rapeseed oil (RME, and mixtures
thereof.
In general, it may be either natural or synthetic,
refined or unrefined ('crude').
The FAAE may contain impurities or by-products as a
result of the manufacturing process.
The FAAE suitably complies with specifications
applying to the rest of the fuel composition, and/or to
the base fuel to which it is added, bearing in mind the
intended use to which the composition is to be put (for
example, in which geographical area and at what time of
year). In particular, the FAAE preferably has a flash
point (IP 34) of greater than 101 C; a kinematic viscosity
at 40 C (IP 71) of 1.9 to 6.0 m2/s, preferably 3.5 to 5.0
mm2/s; a density of 845 to 910 kg/m3, preferably from 860
to 900 kg/m3, at 15 C (IP 365, EN ISO 12185 or EN ISO
3675); a water content (IP 386) of less than 500 ppm; a
T95 (the temperature at which 95% of the fuel has
evaporated, measured according to IP 123) of less than
360 C; an acid number (IP 139) of less than 0.8mgKOG/g,
preferably less than 0.5mgKOH/g; and an iodine number (IP
84) of less than 125, preferably less than 120 or less
than 115, grams of iodine (I2) per 110g of fuel. It also
preferably contains (e.g. by gas chromatography (GC)) less
than 0.2% w/w of free methanol, less than 0.02% w/w of
free glycerol and greater than 96.5% w/w esters. In
general it may be preferred for the FAAE to conform to the
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European specification EN14214 for fatty methyl esters for
use as diesel fuels.
Two or more FAAEs may be added to the fuel
composition in accordance with the present invention,
either separately or as a pre-prepared blend.
The FAAE can be incorporated into the fuel
composition typically as a blend (i.e. a physical mixture)
and optionally with one or more other fuel components
(such as diesel base fuels) and optionally with one or
more fuel additives. The FAAE is conveniently
incorporated into the fuel composition before the
composition is introduced into the engine which is to be
run on the fuel composition.
The fuel composition herein can comprise a paraffinic
gasoil, in addition to or instead of the diesel base fuel
mentioned above. A suitable paraffinic gasoil for use in
the present invention can be derived from any suitable
source as long as it is suitable for use in a fuel
composition, especially a diesel fuel composition.
Suitable paraffinic gasoils include, for example,
Fischer-Tropsch derived gasoils, and gasoils derived from
hydrogenated vegetable oil (HVO), and mixtures thereof.
A preferred paraffinic gasoil for use herein is a
Fischer-Tropsch derived gasoil fuel. The paraffinic
nature of Fischer-Tropsch derived gasoil means that
diesel fuel compositions containing it will have high
cetane numbers compared to conventional diesel.
While Fischer-Tropsch derived gasoil is a preferred
paraffinic gasoil for use herein, the term "paraffinic
gasoil" as used herein also includes those paraffinic
gasoils derived from the hydrotreating of vegetable oils
(HVO). The HVO process is based on an oil refining
technology. In the process, hydrogen is used to remove
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oxygen from the triglyceride vegetable oil molecules and
to split the triglyceride into three separate chains thus
creating paraffinic hydrocarbons.
When present, the paraffinic gasoil (i.e. the
Fischer-Tropsch derived gasoil, the hydrogenated vegetable
oil derived gasoil) will preferably consist of at least
95% w/w, more preferably at least 98% w/w, even more
preferably at least 99.5% w/w, and most preferably up to
100% w/w of paraffinic components, preferably iso- and
normal paraffins, preferably comprising 80% w/w or greater
of iso-paraffins.
By "Fischer-Tropsch derived" is meant that a fuel or
base oil is, or derives from, a synthesis product of a
Fischer-Tropsch condensation process. The term "non-
Fischer-Tropsch derived" may be interpreted accordingly.
A Fischer-Tropsch derived fuel may also be referred to as
a GTL (gas-to-liquid) fuel.
The Fischer-Tropsch reaction converts carbon
monoxide and hydrogen into longer chain, usually
paraffinic, hydrocarbons:
n(CO + 2H2) = (-CH2-), + nH20 + heat, in the presence of
an appropriate catalyst and typically at elevated
temperatures (e.g. 125 to 300 C, preferably 175 to 250 C)
and/or pressures (e.g. 5 to 100 bar, preferably 12 to 50
bar). Hydrogen: carbon monoxide ratios other than 2:1
may be employed if desired.
The carbon monoxide and hydrogen may themselves be
derived from organic or inorganic, natural or synthetic
sources, typically either from natural gas or from
organically derived methane. More recently techniques to
derive carbon monoxide and hydrogen from other sources,
including more sustainable ones are being explored and
used. For example, starting with carbon dioxide and
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water, the water can be electrolysed to give free
hydrogen, typically using electricity from a sustainable
source. This hydrogen can react with the carbon dioxide
in the 'reverse water shift reaction' to give a source of
carbon monoxide. This carbon monoxide can then be
reacted with the remaining hydrogen in the typical
Fischer-Tropsch synthesis process. Because of the use of
electrolysis, some of these production processes are
referred to as 'Power-to-liquids'
Gas oil, kerosene fuel and base oil products may be
obtained directly from the Fischer-Tropsch reaction, or
indirectly for instance by fractionation of Fischer-
Tropsch synthesis products or from hydrotreated Fischer-
Tropsch synthesis products. Hydrotreatment can involve
hydrocracking to adjust the boiling range (see, e. g.
GB2077289 and EP0147873) and/or hydroisomerisation which
can improve cold flow properties by increasing the
proportion of branched paraffins. EP0583836 describes a
two-step hydrotreatment process in which a Fischer-
Tropsch synthesis product is firstly subjected to
hydroconversion under conditions such that it undergoes
substantially no isomerisation or hydrocracking (this
hydrogenates the olefinic and oxygen-containing
components), and then at least part of the resultant
product is hydroconverted under conditions such that
hydrocracking and isomerisation occur to yield a
substantially paraffinic hydrocarbon fuel or oil.
Desired diesel fuel fraction(s) may subsequently be
isolated for instance by distillation.
Other post-synthesis treatments, such as
polymerisation, alkylation, distillation, cracking-
decarboxylation, isomerisation and hydroreforming, may be
employed to modify the properties of Fischer-Tropsch
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condensation products, as described for instance in US-A-
4125566 and US-A-4478955.
Typical catalysts for the Fischer-Tropsch synthesis
of paraffinic hydrocarbons comprise, as the catalytically
active component, a metal from Group VIII of the periodic
table, in particular ruthenium, iron, cobalt or nickel.
Suitable such catalysts are described for instance in
EP0583836.
An example of a Fischer-Tropsch based process is the
SMDS (Shell Middle Distillate Synthesis) described in
The Shell Middle Distillate Synthesis Process", van der
Burgt et al (vide supra). This process (also sometimes
referred to as the Shell "Gas-to-Liquids" or "GTL"
technology) produces diesel range products by conversion
of a natural gas (primarily methane) derived synthesis
gas into a heavy long-chain hydrocarbon (paraffin) wax
which can then be hydroconverted and fractionated to
produce liquid transport fuels such as gasoils and
kerosene. Versions of the SMDS process, utilising fixed-
bed reactors for the catalytic conversion step, are
currently in use in Bintulu, Malaysia, and in Pearl GTL,
Ras Laffan, Qatar. Kerosenes and (gas)oils prepared by
the SMDS process are commercially available for instance
from the Royal Dutch/Shell Group of Companies.
By virtue of the Fischer-Tropsch process, a Fischer-
Tropsch derived gasoil has essentially no, or
undetectable levels of, sulphur and nitrogen. Compounds
containing these heteroatoms tend to act as poisons for
Fischer-Tropsch catalysts and are therefore removed from
the synthesis gas feed. Further, the process as usually
operated produces no or virtually no aromatic components.
For example, the aromatics content of a Fischer-
Tropsch gasoil, as determined for instance by ASTM D4629,
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will typically be below 1% w/w, preferably below 0.5% w/w
and more preferably below 0.1% w/w.
Generally speaking, Fischer-Tropsch derived fuels
have relatively low levels of polar components, in
particular polar surfactants, for instance compared to
petroleum derived fuels. It is believed that this can
contribute to improved antifoaming and dehazing
performance. Such polar components may include for
example oxygenates, and sulphur and nitrogen containing
compounds. A low level of sulphur in a Fischer-Tropsch
derived fuel is generally indicative of low levels of
both oxygenates and nitrogen-containing compounds, since
all are removed by the same treatment processes.
A preferred Fischer-Tropsch derived gasoil fuel for
use herein is a liquid hydrocarbon middle distillate fuel
with a distillation range similar to that of a petroleum
derived diesel, that is typically within the 160 C to
400 C range, preferably with a 195 of 360 C or less.
Again, Fischer-Tropsch derived fuels tend to be low in
undesirable fuel components such as sulphur, nitrogen and
aromatics.
A preferred Fischer-Tropsch derived gasoil for use
herein meets the EN15940 specification.
A preferred Fischer-Tropsch derived gasoil fuel will
typically have a density (as measured by EN ISO 12185) of
from 0.76 to 0.80, preferably from 0.77 to 0.79, more
preferably from 0.775 to 0.785 g/cm3 at 15 C.
A preferred Fischer-Tropsch derived gasoil fuel for
use herein has a cetane number (ASTM D613) of greater
than 70, suitably from 70 to 85, most suitably from 70 to
77.
A preferred Fischer-Tropsch derived gasoil fuel for
use herein has a kinematic viscosity at 40 C (as measured
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according to ASTM D445) in the range from 2.0 mm2/s to 5.0
mm2/s, preferably from 2.5 mm2/s to 4.0 mm2/s.
A preferred Fischer-Tropsch derived gasoil for use
herein has a sulphur content (ASTM D2622) of 5 ppmw (parts
per million by weight) or less, preferably of 2 ppmw or
less.
A preferred Fischer-Tropsch derived gasoil fuel for
use in the present invention is that produced as a
distinct finished product, that is suitable for sale and
used in applications that require the particular
characteristics of a gasoil fuel. In particular, it
exhibits a distillation range falling within the range
normally relating to Fischer-Tropsch derived gasoil
fuels, as set out above.
A fuel composition used in the present invention may
include a mixture of two or more paraffinic gasoils, such
as two or more Fisher-Tropsch derived gasoil fuels.
When present, the Fischer-Tropsch derived components
used herein (i.e. the Fischer-Tropsch derived gasoil) will
preferably comprise no more than 3% w/w, more preferably
no more than 2% w/w, even more preferably no more than 1%
w/w of cycloparaffins (naphthenes), by weight of the
Fischer-Tropsch derived component.
When present, the Fischer-Tropsch derived components
used herein (i.e. the Fischer-Tropsch derived gasoil)
preferably comprise no more than 1% w/w, more preferably
no more than 0.5% w/w, of olefins, by weight of the
Fischer-Tropsch derived component.
The fuel compositions described herein for use in
the present invention are particularly suitable for use
as a diesel fuel, in which case the fuel composition is a
diesel fuel composition, and can be used for arctic
applications, as winter grade diesel fuel due to the
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excellent cold flow properties.
For example, a cloud point of -10 C or lower (EN
23015) or a cold filter plugging point (CFPP) of -20 C or
lower (as measured by EN 116) may be possible with fuel
compositions herein.
Generally speaking, in the context of the present
invention the fuel composition may be additivated with
fuel additives, in addition to the detergent additive
already mentioned.
Unless otherwise stated, the (active matter)
concentration of each such additive in a fuel composition
is preferably up to 10000 ppmw, more preferably in the
range from 1 to 1000 ppmw, advantageously from 1 to 400
ppmw, such as from 1 to 200 ppmw. Such additives may be
added at various stages during the production of a fuel
composition; those added to a base fuel at the refinery
for example might be selected from anti-static agents,
pipeline drag reducers, middle distillate flow improvers
(MDFI) (e.g., ethylene/vinyl acetate copolymers or
acrylate/maleic anhydride copolymers), lubricity
enhancers, anti-oxidants and wax anti-settling agents.
Other components which may be incorporated as fuel
additives, for instance in combination with said
detergent additive, include lubricity enhancers;
dehazers, e.g. alkoxylated phenol formaldehyde polymers;
anti-foaming agents (e.g. commercially available
polyether-modified polysiloxanes); ignition improvers
(cetane improvers) (e.g. 2-ethylhexyl nitrate (EHN),
cyclohexyl nitrate, di-tert-butyl peroxide and those
disclosed in U54208190 at column 2, line 27 to column 3,
line 21); anti-rust agents (e.g. a propane-1,2-diol semi-
ester of tetrapropenyl succinic acid, or polyhydric
alcohol esters of a succinic acid derivative, the
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succinic acid derivative having on at least one of its
alpha-carbon atoms an unsubstituted or substituted
aliphatic hydrocarbon group containing from 20 to 500
carbon atoms, e.g. the pentaerythritol diester of
polyisobutylene-substituted succinic acid); corrosion
inhibitors; reodorants; anti-wear additives; anti-
oxidants (e.g. phenolics such as 2,6-di-tert-butylphenol,
or phenylenediamines such as N,N'-di-sec-butyl-p-
phenylenediamine); metal deactivators; static dissipator
additives; and mixtures thereof.
In a preferred embodiment of the present invention
the other additive components in the detergent additive
package are selected from anti-corrosion additives, metal
passivators, antioxidants, metal deactivators, re-
odorants, and the like, and mixtures thereof.
The present invention may in particular be
applicable where the fuel composition is used or intended
to be used in a direct injection diesel engine, for
example of the rotary pump, in-line pump, unit pump,
electronic unit injector or common rail type, or in an
indirect injection diesel engine, or in an HCCI engine.
The fuel composition may be suitable for use in heavy-
and/or light-duty diesel engines, and in engines designed
for on-road use or off-road use.
In order to be suitable for at least the uses listed
above, it is preferred that the final fuel composition is
a diesel fuel composition, preferably which meets the
EN590 specification (October 2017).
In the case of a GTL base fuel being included in the
fuel composition herein, it is preferred that the final
fuel composition fuel meets the EN15940 specification
(2019).
The present invention may also be applicable where
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the fuel composition is used or intended to be used in a
stationary application such as a heating oil system,
heating oil burner, and/or stationary power generators.
A suitable heating oil composition for use herein
has characteristics according to standard DIN 51603
(2020).
The invention is illustrated by the following non-
limiting examples.
Examples
Example 1
Four fuel samples were used in Example 1 as set out
in Table 1 below.
Table 1
Fuel Fuel Type
Performance Additive
No. Package 12 (ppm)
1 GTL Fuel' 0
2 GTL Fuel' 500
3 B7 (93% EN590 diesel base 0
fuel, 7% FAME)
4 B7 (93% EN590 diesel base 500
fuel, 7% FAME)
1. GTL fuel
according to DIN EN15940 2019-10, class A,
commercially available from Shell having the
physicochemical characteristics set out in Table 2 below
2. Commercially available additive package containing a
PIBSI detergent additive. None of the other components
in Performance Additive Package 1 have a biocidal effect.
Table 2 (GTL Fuel used in Example 1)
Test Test Method Units
Parameter
Density at ASTM D 4052 kg/m3 778.8
15C
Distillation ASTM D86
IBP ASTM D86 C 177.0
5% v/v ASTM D86 C 199.1
10% v/v ASTM D86 C 206.3
15% v/v ASTM D86 C 213.7
20% v/v ASTM D86 C 221.4
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30% v/v ASTM D86 C 237.7
40% v/v ASTM D86 C 253.7
50% v/v ASTM D86 C 268.3
60% v/v ASTM D86 C 282.4
70% v/v ASTM D86 C 296.6
80% v/v ASTM D86 C 311.6
85% v/v ASTM D86 C 320.3
90% v/v ASTM D86 C 329.2
95% v/v ASTM D86 C 341.2
FBP ASTM D86 C 346.2
Recovery ASTM D86 %vol 97.4
Residue ASTM D86 %vol 1.4
Loss ASTM D86 %vol 1.2
E250 ASTM D86 %vol 28.6
E300 ASTM D86 %vol 73.5
Water Content DIN EN ISO mg/kg 42
12937
Cloud Point DIN EN 23015 C -20
CFPP DIN EN 16329 C -29
Kv20 ASTM D445 mm2/ s 3.8369
Test Procedure
Test Microorganisms
A defined inoculum with known hydrocarbon degrading
capacity was used, ex. contaminated field diesel sample.
lml was withdrawn from the contaminated field diesel
sample and used to inoculate an aqueous medium/fuel
mixture in the ratio 70:30m1. This was done for each of
the fuels in Table 1 above and allowed to grow for 8 days
to form cultures or microbial communities. Incubation
was carried out in the dark at 25 C. 100p1 from the
aqueous phase of each microbial community was then used
to inoculate the microcosms.
Microcosm Set Up
A stainless steel coupon (to promote biofilm growth)
was inserted into a vial. 5m1 of Bushnell Haas nutrient
medium (aqueous phase) was decanted in and overlaid with
5m1 of fuel. Microbial communities were then inoculated
with either the GTL fuel or B7 cultures. Therefore, two
inocula were derived from one field sample.
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Testing Protocol
Microbial growth and diversity was assessed over 1
month by dry biomass weight to determine the amount of
growth. This is simple technique designed to give a
direct measurement of the total microbial burden at the
end of the experiment. Growth visible at the interface
was captured, solvent washed to remove fuel residues,
dried in an oven, cooled and weighed. The results of
Example 1 are shown in Figure 1. In Figure 1 the key to
the fuel samples is as follows:
GA1 = GTL fuel (additivated) (Community 1)
GU1 = GTL fuel (unadditivated) (Community 1)
DA1 = B7 fuel (additivated) (Community 1)
DU1 = B7 fuel (unadditivated) (Community 1)
GA2 = GTL fuel (additivated) (Community 2)
GU2 = GTL fuel (unadditivated) (Community 2)
DA2 = B7 fuel (additivated) (Community 2)
DU2 = B7 fuel (unadditivated) (Community 2)
As can be seen from Figure 1 there was a reduction
in biomass growth in the fuels containing Performance
Additive Package 1 (containing a PIBSI detergent
additive) compared with the comparative fuels not
containing a performance additive package. This is
particularly surprising for a nitrogen-containing
detergent in view of nitrogen being a nutrient for
microbes.
Example 2
The fuels used in Example 2 are set out in Table 5
below. Each fuel contained an EN590 base fuel or a GTL
EN15940 base fuel, either with or without FAME, and
either with or without a performance additive
package/detergent additive as indicated. The
physicochemical properties of the EN590 base fuel used in
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this example are set out in Table 3 below. The
physicochemical properties of the GTL fuel used in this
example are set out in Table 4 below. The FAME in the B7
fuels (containing 7% biofuel) was derived from SME/RME.
The FAME used in the B30 fuels (containing 30% of
biofuel, respectively) was derived from SME/RME and POME.
The FAME used in the B50 fuels (containing 50% of
biofuel) was derived from POME.
The additives used were as follows:
Performance Additive Package 2: containing detergent
additives. None of the other components present in
Performance Additive Package 2 have a biocidal effect.
Performance Additive Package 2 is used in all fuel
formulations apart from EN 590 BO.
Performance Additive Package 3: containing detergent
additives. None of the other components present in
Performance Additive Package 3 have a biocidal effect.
Performance Additive Package 3 is used in GTL and EN590
BO fuel formulations. Performance Additive Package 3 is
a special additive formulation tailored for heating fuel
formulations typically containing no FAME. The fuel
formulations tested herein also contain no FAME.
Detergent Additive 1: PIBSI detergent additive (used
in EN 590 B7 fuel formulations).
Detergent Additive 2: quaternary ammonium based
detergent additive (used in EN 590 B7 fuel formulations).
Table 3 (EN590 Base Fuel used in Example 2)
Test Test Method Units
Parameter
Density at ASTM D 4052 kg/m3 833.4
15 C
Flash Point DIN EN ISO C 68.5
2719
CN DIN EN ISO 53.3
5165
Distillation ASTM D86
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IBP ASTM D86 C 177.1
5% v/v ASTM D86 C 202.6
10% v/v ASTM D86 C 215.0
15% v/v ASTM D86 C 223.2
20% v/v ASTM D86 C 229.8
30% v/v ASTM D86 C 241.9
40% v/v ASTM D86 C 253.5
50% v/v ASTM D86 C 263.2
60% v/v ASTM D86 C 273.7
70% v/v ASTM D86 C 285.2
80% v/v ASTM D86 C 299.2
85% v/v ASTM D86 C 307.9
90% v/v ASTM D86 C 319.4
95% v/v ASTM D86 C 337.4
FBP ASTM D86 C 351.4
Residue & ASTM D86 %vol 2.0
Loss
E250 ASTM D86 %vol 37.6
E300 ASTM D86 %vol 81.1
E350 ASTM D86 %vol 97.9
S DIN EN ISO mg/kg <5
20884
Cloud Point ASTM D 2500 C -11
CFPP DIN EN 116 C -28
kV40 ASTM D445 mm2/kg 2.6027
HFRR (WS DIN ISO pm 345
Avg.) 12156-1
Aromatic type DIN EN
(IP391) 12916:2006
Mono DIN EN %wt 20.1
aromatics 12916:2006
Di aromatics DIN EN %wt 2.4
12916:2006
Tri+ DIN EN %wt 0.2
aromatics 12916:2006
FAME content DIN EN 14078 %vol <0.1
NZ DIN 51558 Ti mgKOH/g 0.00
Water Content DIN EN ISO mg/kg 41
12937
Rancimat - DIN EN 15751 H 25.1
mod.
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Table 4 (GTL Fuel Used in Example 2)
Test Test Method Units
Parameter
HFRR (WS DIN ISO pm 630
Avg.) 12156-1
Water Content DIN EN ISO mg/kg 26
12937
CN DIN 51773 70.2
Density at DIN EN ISO kg/m3 776.2
15 C 12185
Distillation DIN EN ISO
3405
IBP DIN EN ISO C 175.9
3405
5% v/v DIN EN ISO C 195.0
3405
10% v/v DIN EN ISO C 203.0
3405
20% v/v DIN EN ISO C 220.5
3405
30% v/v DIN EN ISO C 238.5
3405
40% v/v DIN EN ISO C 255.1
3405
50% v/v DIN EN ISO C 269.7
3405
60% v/v DIN EN ISO C 283.6
3405
70% v/v DIN EN ISO C 297.5
3405
80% v/v DIN EN ISO C 312.1
3405
90% v/v DIN EN ISO C 328.4
3405
95% v/v DIN EN ISO C 338.9
3405
FBP DIN EN ISO C 343.5
3405
Residue & DIN EN ISO %vol 2.2
Loss 3405
E250 DIN EN ISO %vol 37.5
3405
E300 DIN EN ISO %vol 72.6
3405
Kv40 DIN EN ISO mm2/s 2.520
3104
FAME Content DIN EN 14078 %vol <0.1
Flash Point DIN EN ISO C 67.5
2719
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S DIN EN ISO mg/kg <5
20884
Cloud Point DIN EN 23015 C -18
CFPP DIN EN 116 C -25
C m/m % ASTM D 5291 %m/m 84.90
mod
H m/m % ASTM D 5291 %m/m 15.10
mod
0 m/m % ASTM D 5291 %m/m <0.50
mod
The testing protocol was the same as that in Example
1 with assessment of the observed microbial growth in all
tested fuel types over a period of 3 months (2 time
points of 4 weeks and 12 weeks) based on total biomass
dry weight. Three replicate microcosms were set up for
each time point. One microbial community was used as
inoculum.
The results are shown in Table 5 below. Figure 2 is
a graphical representation of the data shown in Table 5,
and in particular shows the average dry biomass weight
(g) after 4 weeks and after 12 weeks of all fuels tested
in Example 2, with and without additive.
Figure 3 is a graphical representation of the data
shown in Table 5, and in particular shows the average dry
biomass weight (g) for all fuel formulations tested with
and without Performance Additive Package 2, Performance
Additive Package 3, Detergent Additive 1 and Detergent
Additive 2. Hence, in Figure 3, the block entitled 'Perf
Additive package 2' represents the average dry biomass
weight (g) for all formulations shown in Table 5
containing Performance Additive Package 2, the block
entitled 'Perf Additive package 3' represents the average
dry biomass weight (g) for all formulations shown in
Table 5 containing Performance Additive Package 3, the
block entitled 'none' represents the average dry biomass
weight (g) for all formulations shown in Table 5
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containing no performance additive package and no
detergent additive, the block entitled 'Det Additive 1'
represents the average dry biomass weight (g) for all
formulations shown in Table 5 containing Detergent
Additive 1, and the block entitled 'Det Additive 2'
represents the average dry biomass weight (g) for all
formulations shown in Table 5 containing Detergent
Additive 2.
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Table 5
Fuel Type
(A = FAME
Additive additive) k EANIL Additive Type Origin
Biomass (g)
No GTL k 4 BO None None
0.0397
No GTL 1 4 BO None None
0.0466
No GTL k 4 BO None None
0.0961
Yes GTL+A 1 4 BO Performance Additive Package 2 None
0.0811
Yes GTL+A 4 BO Performance Additive Package 2 None
0.0588
Yes GTL+A 4 BO Performance Additive Package 2 None
0.0353
Yes GTL+A 4 BO Performance Additive Package 3 None
0.0357
Yes GTL+A 1 k 4 BO
Performance Additive Package 3 None 0.0381
Yes GTL+A v 4 BO F rformance Additive Package 3 None
0.042 I
No GTL v k 4 B7'
SME/RME 0.0686 m
--]
No GTL v 4 B7 L SME/RME
0.0475
i
No GTL v k 4 B7 I\ r
SME/RME 0.0751
Yes GTL+A v 4 B7 Performance Additiv P 2 SÃ/RÃ
0.0595
Yes GTL+A v k 4 B7 Performance
Additive J. 1, je 2 SÃ/RÃ 0.0475
Yes GTL+A v 4 B7 F rformance Additive P age 2 SÃ/RÃ
0.0489
No GTL v k 4 B30
SÃ/RÃ 0.1513
No GTL v k 4 B30 I
SME/RME 0.1217
No GTL v k 4 B30 I\ r
SME/RME 0.1425
Yes GTL+A v k 4 B30
Performance Additive Package 2 SÃ/RÃ 0.1053
Yes GTL+A v k 4 B30
Performance Additive Package 2 SÃ/RÃ 0.0878
Yes GTL+A v 4 B30 Performance Additive Package 2 SÃ/RÃ
0.1102
No EN590 v k 4 BO I\ r
None 0.085
No EN590 1 4 BO ' None -
0.0284
No EN590 k 4 BO L r None
0.1764
Yes EN590+A v 4 BO
F formance Additive Package 3 None 0.1687
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Yes EN590+A v ' 4 BO
Performance Additiv- P--1-7- 3 None 0.0777
Yes EN590+A v k 4 BO
Performance Additive J. k e 3 None 0.14
No EN590 v k 4 B7 F ,
SME/RME 0.0811
No EN590 v k 4 B7 "
SÃ/RÃ 0.0572
No EN590 v k 4 B7 L
SME/RME 0.0696
Yes EN590+A v k 4 B7 I t 1 qat Additive
1 SÃ/RÃ 0.0632
Yes EN590+A v k 4 B7 I It Additive 1
SÃ/RÃ 0.0348
Yes EN590+A v k 4 B7 I t It Additive 1
SÃ/RÃ 0.0539
Yes EN590+A v : 4 B7 I t t Additive 2
SÃ/RÃ 0.0524
Yes EN590+A v k 4 B7 I t It Additive 2
SÃ/RÃ 0.0428
Yes EN590+A 1, : 4 B7 L_t_ _t Additive 2
SÃ/RÃ 0.0351
Yes EN590+A k 4 B7 Performance Additive Package 2 SÃ/RÃ
0.0313
Yes EN590+A 1 : 4 B7
Performance Additive Package 2 SÃ/RÃ 0.0318
1
Yes EN590+A k 4 B7 Performance Additive Package 2 SÃ/RÃ
0.0444 m
No EN590 1 k 4 B30 None POMP
0.1348 m
1
I EN590 k 4 B30 None POME
0.096
I EN590 1 k 4 B30 None POMP
0.0557
EN590+A k 4 B30 Performance Additive Package 2 POME
0.0761
' s EN590+A 1 k 4 B30 Performance
Additive Package 2 POME 0.1(83
EN590+A k 4 B30 Performance Additive Package 2
POME 0.E "7
I EN590 1 k 4 B50 None POMP O.
I EN590 v ' 4 B50 None
POMP O. 33
No EN590 v k 4 B50 None
POMP 0.2121
Yes EN590+A v ' 4 B50 Performance
Additive Package 2 POME 0.1178
Yes EN590+A v k 4 B50
Performance Additive Package 2 POME 0.0916
Yes EN590+A v ' 4 B50 Performance
Additive Package 2 POME 0.0796
No GTL v k 1H BO None None
0.1224
No GTL v k 1H BO None None
0.0954
No GTL v k 12 BO None None
0.0756
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Yes GTL+A v ' 12 BO Performance Additiv-
Pfl-1-7.7- 2 None 0.1984
Yes GTL+A v k 1H BO Performance
Additive I.. =k:.je 2 None 0.2239
Yes GTL+A v k 1H BO
Performance Additive P. 'age 2 N( 0.0625
Yes GTL+A v k 1H BO
Performance Additive Package 3 :' ] 0.1107
Yes GTL+A v k 1H BO
Performance Additive Package 3 :: 0.0371
Yes GTL+A v k 1H BO
F rformance Additive Package 3 N( ] 0.0559
No GTL v k 1H B7 I.
SÃ/RÃ 0.0571
No GTL v k 1H B7
SME/RME 0.0631
No GTL v -: 1? B7 F.
SME/RME 0.1005
Yes GTL+A v k 1H B7
Performance Additive Package 2 SÃ/RÃ 0.0508
Yes GTL+A 1, -: 1? B7 Performance
Additive Package 2 SÃ/RÃ 0.0489
Yes GTL+A : 1H B7
Performance Additive Package 2 SÃ/RÃ 0.0455
No GTL 1 : 1? B30 None
SÃ/RÃ 0.1336
I
No GTL : 1H B30 None
SÃ/RÃ 0.1367 m
No GTL 1 : 1'. B30 None
SÃ/RÃ 0.1075 ts)
1
.3' GTL+A : 12 B30 Performance
Additive Package 2 SÃ/RÃ 0.1529
' s GTL+A 1 : 1'. B30 Performance
Additive Package 2 SÃ/RÃ 0.4002
.3' GTL+A : 12 B30 Performance
Additive Package 2 SÃ/RÃ 0.0633
1. EN590 1 : 1H BO 1\. ,r
N( ] 0.1201
I. EN590 : 12 BO
I. 0.0756
1. EN590 1 : 1H BO
:. ] 0.0631
EN590+A v ' 12 BO
F rformance Additive Package 3 N( 0.052
Yes EN590+A v k 1H BO
Performance Additive Package 3 None 0.1099
Yes EN590+A v ' 12 BO
PPrformance Additive Package 3 None 0.0865
No EN590 v k 1H B7 1\. T
SME/RME 0.0389
No EN590 v ' 12 B7 I. SME/RME
0.0407
No EN590 v k 1H B7 ,. , .
SME/RME 0.0367
Yes EN590+A v k 1H B7 I L-gent Additive 1
SÃ/RÃ 0.0447
Yes EN590+A v k 12 B7 Detergent Additive
1 SÃ/RÃ 0.0429
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Yes EN590+A v ' 12 B7 D-'- -t Additive 1
SÃ/RÃ 0.0345
Yes EN590+A v k 1H B7 I t It Additive 2
SÃ/RÃ 0.0475
Yes EN590+A v k 1H B7 Dete qat Additive 2
SÃ/RÃ 0.0483
Yes EN590+A v k 1H B7 Detergent Additive
2 SÃ/RÃ 0.0563
Yes EN590+A v k 1H B7
Performance Additive Package 2 SÃ/RÃ 0.3515
Yes EN590+A v k 1H B7
Performance Additive Package 2 SÃ/RÃ 0.0513
Yes EN590+A v k 1H B7
Performance Additive Package 2 SÃ/RÃ 0.06
No EN590 v k 1H B30 None
POMP 0.5307
No EN590 v -: 1? B30 None
POMP 0.2122
No EN590 v k 1H B30 None
POMP 0.163
Yes EN590+A 1, -: 1? B30 Performance
Additive Package 2 POME 0.1895
Yes EN590+A : 1H B30
Performance Additive Package 2 POME 0.2436
Yes EN590+A 1 : 1? B30 Performance
Additive Package 2 POMP 0.4804
I
No EN590 : 1H B50 None
POMP 0.394 w
No EN590 1 : 1'. B50 None
POMP 0.4321 D
1
1 EN590 : 12 B50 None
POME 0.2501
' s EN590+A 1 : 1'. B50 Performance
Additive Package 2 POME 0.4049
EN590+A : 12 B50 Performance
Additive Package 2 POME 0.2606
' s EN590+A v k 12 B50 Performance
Additive Package 2 POME 0.2285
