U.S. patent application number 14/086371 was filed with the patent office on 2014-06-05 for fuel compositions.
This patent application is currently assigned to Shell Oil Company. The applicant listed for this patent is Shell Oil Company. Invention is credited to Mark Lawrence BREWER, Roger Grancis CRACKNELL, Matthias EGGENSTEIN, Tor Kit GOH.
Application Number | 20140150333 14/086371 |
Document ID | / |
Family ID | 47257670 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140150333 |
Kind Code |
A1 |
BREWER; Mark Lawrence ; et
al. |
June 5, 2014 |
FUEL COMPOSITIONS
Abstract
Disclosed is a diesel fuel composition containing 2-ethylhexyl
nitrate (2-EHN) and one or more organic peroxides for providing
improved fuel economy. The organic peroxides may have a cyclic
peroxide of the general formula (I). ##STR00001##
Inventors: |
BREWER; Mark Lawrence;
(Chester, GB) ; CRACKNELL; Roger Grancis;
(Chester, GB) ; EGGENSTEIN; Matthias; (Neu
Wulmstoff, DE) ; GOH; Tor Kit; (Kuala Lumpur,
MY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shell Oil Company |
Houston |
TX |
US |
|
|
Assignee: |
Shell Oil Company
Houston
TX
|
Family ID: |
47257670 |
Appl. No.: |
14/086371 |
Filed: |
November 21, 2013 |
Current U.S.
Class: |
44/326 |
Current CPC
Class: |
C10L 1/14 20130101; C10L
2230/22 20130101; C10L 1/231 20130101; C10L 10/12 20130101; C10L
10/00 20130101; C10L 2200/0446 20130101; C10L 1/23 20130101; C10L
1/1811 20130101 |
Class at
Publication: |
44/326 |
International
Class: |
C10L 1/18 20060101
C10L001/18 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2012 |
EP |
12195017.4 |
Claims
1. A diesel fuel composition comprising a diesel base fuel,
2-ethylhexylnitrate and one or more peroxides selected from the
group of peroxides represented by the general formula (I) below:
##STR00004## wherein R.sub.1, R.sub.3, and R.sub.5 are
independently selected from the group consisting of hydrogen,
C.sub.1-C.sub.20 alkyl, C.sub.3-C.sub.20 cycloalkyl,
C.sub.6-C.sub.20 aryl, C.sub.7-C.sub.20 aralkyl and
C.sub.7-C.sub.20 alkaryl, which groups may include linear or
branched alkyl moieties; R.sub.2, R.sub.4 and R.sub.6 are
independently selected from the group consisting of hydrogen,
C.sub.2-C.sub.20 alkyl, C.sub.3-C.sub.20 aryl, C.sub.7-C.sub.20
aralkyl, and C.sub.7-C.sub.20 alkaryl, which groups may include
linear or branched alkyl moieties; and each of R.sub.1 to R.sub.6
may optionally be substituted with one or more groups selected from
hydroxyl, alkoxy, linear or branched alkyl, aryloxy, ester,
carboxy, nitrile, and amido.
2. The diesel fuel composition of claim 1 wherein the amount of the
one or more peroxides is in the range of from 0.001% w/w to 1% w/w,
based on the weight of the total diesel fuel composition.
3. The diesel fuel composition of claim 1 wherein the amount of
2-ethylhexyl nitrate is in the range of from 0.001% w/w to 1% w/w,
based on the weight of the total diesel fuel composition.
4. The diesel fuel composition of claim 1 wherein at least one of
the peroxides in the fuel composition is derived from one or more
ketones selected from the group consisting of acetone,
methyl-n-amyl ketone, ethyl butyl ketone, ethylpropyl ketone,
methylheptyl ketone, methylhexyl ketone, ethylamyl ketone,
methylpropyl ketone, diethyl ketone, methylethyl ketone, isomers of
these ketones, and mixtures thereof.
5. The diesel fuel composition of claim 1 wherein the cyclic ketone
peroxide of general formula (I) is selected from the group
consisting of cyclic methylethyl ketone peroxide, cyclic
methylisobutyl ketone peroxide, and cyclic methylisopropyl ketone
peroxide.
6. The diesel fuel composition of claim 1 comprising
2-ethylhexylnitrate and cyclic methylethyl ketone peroxide.
7. The diesel fuel composition of claim 6 wherein the cyclic
methylethyl ketone peroxide is
3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane.
8. The diesel fuel composition of claim 1 further comprising one or
more fuel additives.
9. A method of operating an internal combustion engine and/or a
vehicle powered by such an engine comprising introducing into a
combustion chamber of the engine the diesel fuel composition of
claim 1 and operating the internal combustion engine and/or the
vehicle powered by such an engine.
10. A method of improving the fuel economy performance of an
internal combustion engine comprising introducing into a combustion
chamber of the internal combustion engine a diesel fuel composition
of claim 1.
Description
[0001] The present application claims the benefit of European
Procedure Patent No. 121950.4, filed Nov. 30, 2012.
FIELD OF THE INVENTION
[0002] The present invention relates to liquid fuel compositions
having improved fuel economy benefits containing 2-ethylhexyl
nitrate and one or more peroxides in a diesel fuel composition.
BACKGROUND OF THE INVENTION
[0003] Government regulations and market demands continue to
emphasize conservation of fossil fuels in the transportation
industry. There is increasing demand for more fuel-efficient
vehicles in order to meet CO.sub.2 emissions reductions targets.
Any incremental improvement in fuel economy (FE) is of great
importance in the automotive sector. There is therefore a
continuing need for improvements in fuel economy performance of
fuel compositions used to fuel an internal combustion engine.
[0004] The cetane number of a diesel fuel composition is a measure
of its ease of ignition and combustion. With a lower cetane number
fuel, a compression ignition (diesel) engine tends to be more
difficult to start and may run more noisily when cold; conversely a
fuel of higher cetane number tends to impart easier cold starting,
to lower engine noise, to alleviate white smoke ("cold smoke")
caused by incomplete combustion.
[0005] There is a general preference, therefore, for a diesel fuel
composition to have a high cetane number, a preference which has
become stronger as emissions legislation grows increasingly
stringent, and as such automotive diesel specifications generally
stipulate a minimum cetane number. To this end, many diesel fuel
compositions contain ignition improvers, also known as cetane boost
additives or cetane (number) improvers/enhancers, to ensure
compliance with such specifications and generally to improve the
combustion characteristics of the fuel.
[0006] Organic nitrates have been known for some time as ignition
accelerants in fuels, and some are also known to increase the
cetane number of diesel fuels. Perhaps the most commonly used
diesel fuel ignition improver is 2-ethylhexyl nitrate (2-EHN),
which operates by shortening the ignition delay of a fuel to which
it is added.
[0007] European consumption of 2-EHN grew from 75 kt/a to 101 kt/a
from 2000 to 2008, and an average annual growth of approximately
3.5% has been predicted from 2008 to 2013.
[0008] The consumption of 2-EHN in North America (USA: 7.2 kt/a in
2008) is much lower than in Europe.
[0009] 2-EHN is produced industrially by the nitration of
2-ethylhexanol, and in Europe this consumes almost a quarter of the
production of this alcohol. The nitration of the alcohol involves
reaction with a 1/1 mixture of undiluted nitric and sulfuric acids
(using stoichiometric amounts of alcohol and nitric acid).
[0010] Organic peroxides have also been known for some time as
cetane improvers.
[0011] US2011/0099979 discloses diesel fuel compositions and method
for reducing NOx emissions. Paragraph [0038] of US2011/0099979
discloses cetane improvers which are organic compounds containing
O--O bonds such as alkyl peroxides, aryl peroxides, alkyl aryl
peroxides, acyl peroxides, peroxyesters, peroxyketones, per acids,
hydroperoxides, and mixtures thereof. Examples include
di-tert-butyl peroxide, cumyl peroxide,
2,5-dimethyl-2,5-di(tertiarybutylperoxy) hexane, tertiary butyl
cumyl peroxide, benzoyl peroxide, tertiary butyl peracetate,
3,6,9-triethyl-3,9-trimethyl-1,4,7-triperoxononan,
2,2-di(tertiarybutyl)butane, peroxy acetic acid, tertiary butyl
hydroperoxide. Di-tert-butyl peroxide is stated to be the preferred
peroxide compound.
[0012] U.S. Pat. No. 4,045,188 discloses that the use of
di-tert-butyl peroxide in conjunction with di-tert-butyl alcohol
provides a synergistic effect in gasolines, particularly pronounced
in leaded gasolines, to increase engine performance, measured by an
increase in miles per gallon.
[0013] WO2004/072059 (EP1592682) relates to a composition
comprising a cyclic ketone peroxide and one or more dialkyl
peroxides.
[0014] WO99/32584 relates to a fuel comprising one or more cyclic
ketone peroxides for reducing the emission of pollutants.
Comparative Example D discloses a combination of 2-ethylhexyl
nitrate and di-tert-butyl peroxide.
[0015] RU2010124844A relates to diesel fuel containing additives
which increase cetane number. Additives consist of premixed
cyclohexyl nitrate or 2-EHN and peroxides selected from
di-tert-butyl peroxide, dicumyl peroxide and cumyl hydroperoxide.
The effect of these additives is high cetane number of diesel fuel
and low content of nitrogen oxides in exhaust gas.
[0016] "Unique trifurcated hydrogen bonding in a pseudopolymorph of
tricyclohexane triperoxide (TCTP) and its thermal studies",
Chiranjeev Sharma Neupane, Satich Kumar Awasthi, Tetrahedron
Letters, accepted manuscript 28 Aug. 2012, discloses that cyclic
peroxides have been studied as cetane enhancers. This document
discloses the synthesis of TCTP (tricyclohexane triperoxide).
[0017] "Synthesis and cetane-improving performance of
1,2,4,5-tetraoxane and 1,2,4,5,7,8-hexaoxonane derivatives",
Ambadas B Rode, Keunwoo Chung, Young-Wun Kim, In Seok Hong, Energy
& Fuels, 2010, 24, pages 1366 to 1639, discloses examples of
diesel fuels containing a combination of 2-EHN with cyclic ketone
peroxide compounds 3a (tetraoxane), 4b, 4c and 4d
(hexaoxonanes).
[0018] "Solid deposits from thermal stressing of n-dodecane and
Chinese RP-3 jet fuel in the presence of several initiators",
Guozhu Liu, Yongjin Han, Li Wang, Xiangwen Zhang, Zhentao Mi,
Energy & Fuels, 2009, 23, pages 356 to 365, discloses
3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxononane (TEMPO) and
demonstrates the role of initiators in the carbon deposition
because of thermal cracking of jet fuel.
[0019] "Supercritical thermal cracking of N-dodecane in the
presence of several initiator additives: Products distribution and
kinetics", Guozhu Liu, Yongjin Han, Li Wang, Xiangwen Zhang,
Zhentao Mi, Energy & Fuels, 2008, 22, pages 3960 to 3969,
discloses 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxononane
(TEMPO) and demonstrates thermal cracking of n-dodecane in the
presence TEMPO.
SUMMARY OF THE INVENTION
[0020] It has now been found that 2-EHN together with organic
peroxides can improve the fuel economy properties in a diesel fuel
composition.
[0021] Accordingly, in one embodiment, a diesel fuel composition is
provided comprising a diesel base fuel, 2-ethylhexylnitrate and one
or more peroxides selected from the group of peroxides represented
by the general formula (I) below:
##STR00002##
wherein R1, R3, and R5 are independently selected from the group
consisting of hydrogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20
aryl, C7-C20 aralkyl and C7-C20 alkaryl, which groups may include
linear or branched alkyl moieties; R2, R4 and R6 are independently
selected from the group consisting of hydrogen, C2-C20 alkyl,
C3-C20 aryl, C7-C20 aralkyl, and C7-C20 alkaryl, which groups may
include linear or branched alkyl moieties; and each of R1 to R6 may
optionally be substituted with one or more groups selected from
hydroxyl, alkoxy, linear or branched alkyl, aryloxy, ester,
carboxy, nitrile, and amido.
[0022] In another embodiment, a method of operating an internal
combustion engine and/or a vehicle powered by such an engine is
provided, which comprises introducing into a combustion chamber of
the engine the diesel fuel composition and operating the internal
combustion engine and/or vehicle powered by such an engine.
BRIEF DESCRIPTION OF THE DRAWING
[0023] FIG. 1 shows the Derived Cetane Number (DCN) of the fuel
blends tested in Example 2.
DETAILED DESCRIPTION OF THE INVENTION
[0024] In order to assist with the understanding of the invention
several terms are defined herein.
[0025] The term "fuel economy" as used herein refers to optimized
efficiency of an engine consuming fuel, i.e. the same power output
can be obtained from the engine while consuming less fuel (and
therefore emitting less carbon dioxide).
[0026] According to the present invention, there is provided the
use of 2-ethylhexyl nitrate and one or more organic peroxides in a
diesel fuel composition for the purpose of improving fuel economy.
In the context of this aspect of the invention, the term
"improving" embraces any degree of improvement. The improvement may
for instance be 0.1% or more, preferably 0.5% or more, more
preferably 1% or more, and especially 2% or more of the fuel
economy of an analogous fuel formulation, prior to adding both
2-ethylhexyl nitrate and one or more organic peroxides to it in
accordance with the present invention. The improvement in fuel
economy may be at most 5% of the fuel economy of an analogous fuel
formulation, prior to adding both 2-ethylhexyl nitrate and one or
more organic peroxides to it in accordance with the present
invention.
[0027] In accordance with the present invention, the fuel economy
of a fuel composition may be determined in any known manner, for
instance using the standard test procedure according to EEC
Directive 90/C81/01 using the New European Drive Cycle (NEDC) for a
vehicle on a chassis dynamometer or a bench engine. This provides a
so-called "measured" fuel consumption number obtained under engine
running conditions. Alternatively, the fuel economy performance of
a fuel composition may be determined using the "Fuel Economy Test
Method" described in the Examples of the present application. In
some embodiments, the methods/uses encompass adding 2-EHN and one
or more organic peroxides to a fuel composition so as to adjust the
fuel economy performance or to achieve or reach a desired target
fuel economy value. In the context of the invention, to "reach" a
target fuel economy value can also embrace exceeding that number.
Thus, the target fuel economy number may be a target minimum fuel
economy value.
[0028] The concentration of the 2-EHN and the one or more peroxides
used may depend on desirable fuel characteristics/properties, such
as: the desired combustability of the overall fuel composition; the
combustability of the composition prior to incorporation of the
additive; the combustability and/or stability of the additive
itself; and/or the properties of any solvent in which the additive
is used. By way of example, the concentration of the one or more
organic peroxides in the fuel composition may be up to 1% w/w and
suitably up to 0.5% w/w. Thus, the concentration of the one or more
peroxides may be from 0.001% w/w to 1% w/w, from 0.003% w/w to
0.005% w/w, or from 0.005% w/w to 0.5% w/w. In some cases, the
concentration of the one or more peroxides is from 0.001% w/w to
1.0 w/w, such as 0.001% w/w, 0.01% w/w, 0.025% w/w, 0.05% w/w, 0.1%
w/w, 0.5% w/w or 1.0% w/w based on the total weight of the fuel
composition.
[0029] With regard to the concentration of 2-EHN, the same
concentration ranges may apply to the concentration of 2-EHN as
specified above for the concentration ranges of the one or more
organic peroxides.
[0030] With regard to the combination of 2-EHN and one or more
peroxides, the same concentration ranges may apply to the total
combination of 2-EHN and one or more peroxides as are given above
for the concentration ranges of 2-EHN and for the concentration
ranges of one or more peroxides. It will be appreciated that
amounts/concentrations may also be expressed as ppm, in which case
1% w/w corresponds to 10,000 ppm w/w.
[0031] The remainder of the composition will typically consist of
one or more automotive base fuels optionally together with one or
more fuel additives, for instance as described in more detail
below.
[0032] The engine in which the fuel composition of the invention is
used may be any appropriate engine. Thus, where the fuel is a
diesel, including a biodiesel, fuel composition, the engine is a
diesel or compression ignition engine. Likewise, any type of diesel
engine may be used, such as a turbo charged diesel engine, provided
the same or equivalent engine is used to measure fuel economy with
and without the fuel economy increasing components. Generally, the
fuel economy improvers of the invention are suitable for use over a
wide range of engine working conditions.
[0033] An essential component of the fuel compositions herein is
one or more organic peroxides. Preferably, the one or more organic
peroxides are selected from the group of peroxides represented by
formula (I) below:
##STR00003##
wherein R.sub.1, R.sub.3, and R.sub.5 are independently selected
from the group consisting of hydrogen, C.sub.1-C.sub.20 alkyl,
C.sub.3-C.sub.20 cycloalkyl, C.sub.6-C.sub.20 aryl,
C.sub.7-C.sub.20 aralkyl and C.sub.7-C.sub.20 alkaryl, which groups
may include linear or branched alkyl moieties; R.sub.2, R.sub.4 and
R.sub.6 are independently selected from the group consisting of
hydrogen, C.sub.2-C.sub.20 alkyl, C.sub.3-C.sub.20 aryl,
C.sub.7-C.sub.20 aralkyl, and C.sub.7-C.sub.20 alkaryl, which
groups may include linear or branched alkyl moieties; and each of
R.sub.1 to R.sub.6 may optionally be substituted with one or more
groups selected from hydroxyl, alkoxy, linear or branched alkyl,
aryloxy, ester, carboxy, nitrile, and amido.
[0034] The cyclic ketone peroxide(s) can be produced as described
in WO96/03397. Further details on the preparation methods and other
aspects of the cyclic ketone peroxide(s) can be found in
WO99/32584.
[0035] Suitable ketones for use in the synthesis of cyclic ketone
peroxides as used in the invention include, for example, acetone,
acetophenone, methyl-n-amyl ketone, ethylbutyl ketone, ethylpropyl
ketone, methylisoamyl ketone, methylheptyl ketone, methylhexyl
ketone, ethylamyl ketone, dimethyl ketone, diethyl ketone, dipropyl
ketone, methylethyl ketone, methylisobutyl ketone, methyl isopropyl
ketone, methylpropyl ketone, methyl tert-butyl ketone,
isobutylheptyl ketone, diisobutyl ketone, 2,4-pentanedione,
2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione,
3,5-octanedione, 5-methyl-2,4-hexanedione,
2,6-methyl-3,5-heptanedione, 2,4-octanedione,
5,5-dimethyl-2,4-hexanedione, 6-methyl-2,4-heptanedione,
1-phenyl-1,3-propanedione, 1-phenyl-1,3-pentanedione,
1,3-diphenyl-1,3-propanedione, 1-phenyl-2,4-pentanedione,
methylbenzylketone, phenylmethyl ketone, phenylethyl ketone, and
coupling products thereof. Of course, other ketones having
appropriate R groups corresponding to the peroxides of formula (I)
can also be used, as well as mixtures of two or more ketones.
[0036] Examples of preferred peroxides of formula (I) for use in
accordance with the present invention are the cyclic ketone
peroxides derived from methyl-n-amyl ketone, ethylbutyl ketone,
ethylpropyl ketone, methylheptyl ketone, methylhexyl ketone,
ethylamyl ketone, methylpropyl ketone, diethyl ketone, methylethyl
ketone, isomers of these ketones, and mixtures thereof. More
preferably the peroxides of formula (I) are based on at least one
ketone selected from the group consisting of methyl-n-amyl ketone,
ethylbutyl ketone, ethylpropyl ketone, methylheptyl ketone,
methylhexyl ketone, ethylamyl ketone, methylpropyl ketone, diethyl
ketone, methylethyl ketone, and one or more isomers of these
ketones, such as methyl-isobutyl ketone and methylisopropyl
ketone.
[0037] In preferred embodiments herein the cyclic ketone peroxide
of formula (I) is selected from the group consisting of cyclic
methylethyl ketone peroxide, cyclic methylisobutyl ketone peroxide,
and cyclic methylisopropyl ketone peroxide.
[0038] In a particularly preferred embodiment herein the cyclic
ketone peroxide of formula (I) is cyclic methylethyl ketone
peroxide.
[0039] A particularly preferred cyclic ketone peroxide for use
herein is 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane which
is commercially available from Akzo-Nobel under the tradename
Trigonox 301. Trigonox 301 is a solution of 41% w of
3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane in isoparafinic
solvent.
[0040] In addition to 2-EHN and the one or more peroxides, the fuel
composition herein may comprise one or more cetane number
enhancers. Cetane number enhancers are known and commercially
available, and may also be known (in the context of diesel fuels)
as "cetane (number) improvers", "combustion improvers" and
"ignition improvers" etc. as previously described.
[0041] Cetane enhancers are often added to diesel fuels, at
additive levels (typically 10 to 2000 ppm w/w).
[0042] They function to reduce the ignition delay, i.e. the period
between the time of injection of the fuel and the start of
combustion (ignition).
[0043] The cetane number (CN) of a fuel is defined by reference to
the ignition properties of standard mixtures of n-hexadecane
(cetane, CN=100) and 2,2,4,4,6,8,8-hepta-methylnonane (CN=15). A
fuel with a high CN has a short ignition delay. Typically,
molecules with high octane numbers, which confer a resistance to
spontaneous ignition in gasoline spark ignition engines, have low
cetane numbers. The addition of small amounts of cetane enhancers
to a diesel fuel may, therefore, result in improved fuel properties
based on the shorter ignition delay.
[0044] Known cetane number enhancers include, but are not limited
to certain organic nitrates other than 2-EHN (e.g. isopropyl
nitrate, cyclohexyl nitrate, and methoxyethyl nitrate) and organic
peracids and peresters.
[0045] In use, the 2-EHN and the one or more peroxides may be
pre-dissolved in a suitable solvent, for example an oil such as a
mineral oil or Fischer-Tropsch derived hydrocarbon mixture; a fuel
component (which again may be either mineral or Fischer-Tropsch
derived) compatible with the diesel fuel composition in which the
additive is to be used (for example a middle distillate fuel
component such as a gas oil or kerosene); a poly alpha olefin; a
so-called biofuel such as a fatty acid alkyl ester (FAAE), a
Fischer-Tropsch derived biomass-to-liquid synthesis product, a
hydrogenated vegetable oil, a waste or algae oil or an alcohol such
as ethanol; an aromatic solvent; any other hydrocarbon or organic
solvent; or a mixture thereof. Preferred solvents for use in this
context are mineral oil based diesel fuel components and solvents,
and Fischer-Tropsch derived components such as the "XtL" components
referred to below. Biofuel solvents may also be preferred in
certain cases. Typically, the 2-EHN and the one or more peroxides
will be part of an additive (performance) package additionally
containing other additives such as detergents, anti-foaming agents,
corrosion inhibitors, dehazers etc. Alternatively, the 2-EHN and
the one or more peroxides may be blended directly with the base
fuel.
[0046] The relative proportions of the 2-EHN, one or more
peroxides, fuel components and any other components or additives
present in a diesel fuel composition prepared according to the
invention may also depend on other desired properties such as
density, emissions performance and viscosity.
Diesel Fuel Compositions
[0047] In one aspect of the invention, there is provided a diesel
fuel composition, which comprises 2-EHN and one or more peroxides
of the general formula (I) above, preferably cyclic methylethyl
ketone peroxide. It has been found that a combination of 2-EHN and
such peroxides, e.g. cyclic methylethyl ketone peroxide, has
surprising advantages in terms of providing an improvement in fuel
economy performance.
[0048] A particularly preferred cyclic ketone peroxide for use in
the diesel fuel composition of the present invention is
3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane which is
commercially available from Akzo-Nobel under the tradename Trigonox
301.
[0049] The concentrations of 2-EHN and peroxide of general formula
(I), e.g. cyclic methylethyl ketone peroxide, are in the same
ranges as given above for the one or more organic peroxides.
[0050] A diesel fuel composition prepared in accordance with the
present invention may in general be any type of diesel fuel
composition suitable for use in a compression ignition (diesel)
engine; and it may itself comprise a mixture of diesel fuel
components.
[0051] Thus, in addition to the 2-EHN and one or more organic,
suitably, cyclic peroxides, a diesel fuel composition prepared
according to the present invention may comprise one or more diesel
fuel components of conventional type. It may, for example, include
a major proportion of a diesel base fuel, for instance of the type
described below. In this context, a "major proportion" means at
least 50% w/w, and typically at least 85% w/w based on the overall
composition. More suitably, at least 90% w/w or at least 95% w/w.
In some cases at least 98% w/w or at least 99% w/w of the fuel
composition consists of the diesel base fuel. Accordingly, in some
embodiments, the base fuel may itself comprise a mixture of two or
more diesel fuel components of the types described below.
[0052] Typical diesel fuel components comprise liquid hydrocarbon
middle distillate fuel oils, for instance petroleum derived gas
oils. Such base fuel components may be organically or synthetically
derived, and are suitably obtained by distillation of a desired
range of fractions from a crude oil. They will typically have
boiling points within the usual diesel range of 150 to 410.degree.
C. or 170 to 370.degree. C., depending on grade and use. They will
typically have densities from 0.75 to 0.9 g/cm.sup.3, such as from
0.8 to 0.86 g/cm.sup.3, at 15.degree. C. (IP 365) and measured
cetane numbers (ASTM D613) of from 35 to 80, more preferably from
40 to 75. Their initial boiling points will suitably be in the
range 150 to 230.degree. C. and their final boiling points in the
range 290 to 400.degree. C. Their kinematic viscosity at 40.degree.
C. (ASTM D445) might suitably be from 1.5 to 4.5 centistokes. Such
fuels are generally suitable for use in compression ignition
(diesel) internal combustion engines, of either the indirect or
direct injection type.
[0053] An automotive diesel fuel composition which results from
carrying out the present invention will also suitably fall within
these general specifications. Accordingly, it will generally comply
with applicable current standard specification(s) such as for
example EN 590 (for Europe) or ASTM D975 (for the USA). By way of
example, the fuel composition may have a density from 0.82 to 0.845
g/cm.sup.3 at 15.degree. C.; a T.sub.95 boiling point (ASTM D86) of
360.degree. C. or less; a cetane number (ASTM D613) of 45 or
greater; a kinematic viscosity (ASTM D445) from 2 to 4.5 mm.sup.2/s
at 40.degree. C.; a sulphur content (ASTM D2622) of 50 mg/kg or
less; and/or a polycyclic aromatic hydrocarbons (PAH) content
(IP391 (mod)) of less than 11% w/w. Relevant specifications may,
however, differ from country to country and from year to year and
may depend on the intended use of the fuel composition. In
particular, its measured cetane number will preferably be from 45
to 70, to 75 or to 80, more preferably from 50 to 65, or at least
greater than 50, greater than 55, greater than 60, or greater than
65.
[0054] A petroleum derived gas oil, e.g. obtained from refining and
optionally (hydro) processing a crude petroleum source, may be
incorporated into a diesel fuel composition. It may be a single gas
oil stream obtained from such a refinery process or a blend of
several gas oil fractions obtained in the refinery process via
different processing routes. Examples of such gas oil fractions are
straight run gas oil, vacuum gas oil, gas oil as obtained in a
thermal cracking process, light and heavy cycle oils as obtained in
a fluid catalytic cracking unit, and gas oil as obtained from a
hydrocracker unit. Optionally a petroleum derived gas oil may
comprise some petroleum derived kerosene fraction. Such gas oils
may be processed in a hydro-desulphurisation (HDS) unit so as to
reduce their sulphur content to a level suitable for inclusion in a
diesel fuel composition. This also tends to reduce the content of
other polar species such as oxygen- or nitrogen-containing species.
In some cases, the fuel composition will include one or more
cracked products obtained by splitting heavy hydrocarbons.
[0055] In some embodiments of the present invention, the base fuel
may be or contain another so-called "biodiesel" fuel component,
such as a vegetable oil, hydrogenated vegetable oil or vegetable
oil derivative (e.g. a fatty acid ester, in particular a fatty acid
methyl ester, FAME), or another oxygenate such as an acid, ketone
or ester. Such components need not necessarily be bio-derived.
Where the fuel composition contains a biodiesel component, the
biodiesel component may be present in quantities up to 100%, such
as between 1% and 99% w/w, between 2% and 80% w/w, between 2% and
50% w/w, between 3% and 40% w/w, between 4% and 30% w/w, or between
5% and 20% w/w. In one embodiment the biodiesel component may be
FAME.
[0056] A diesel base fuel may consist of or comprise a
Fischer-Tropsch derived diesel fuel component, typically a
Fischer-Tropsch derived gas oil. As used herein, the term
"Fischer-Tropsch derived" means that a material is, or is obtained
from, a synthesis product of a Fischer-Tropsch condensation
process. A Fischer-Tropsch derived fuel or fuel component will
therefore be a hydrocarbon stream in which a substantial portion,
except for added hydrogen, is derived directly or indirectly from a
Fischer-Tropsch condensation process.
[0057] Fischer-Tropsch fuels may be derived by converting gas,
biomass or coal to liquid (XtL), specifically by gas to liquid
conversion (GtL), or from biomass to liquid conversion (BtL). Any
form of Fischer-Tropsch derived fuel component may be used as a
base fuel in accordance with the invention.
[0058] The base fuel suitably has a low sulphur content, for
example at most 1000 mg/kg (1000 parts per million by weight/ppmw).
More suitably it will have a low or ultra low sulphur content, for
instance at most 500 mg/kg (500 ppmw), such as no more than 350
mg/kg (350 ppmw), and still more suitably no more than 100 or 50 or
10 or even 5 mg/kg (5 ppmw) of sulphur. It may be a so-called
"zero-sulphur" fuel; although in some cases it may be desired that
the base fuel is not a sulphur free ("zero sulphur") fuel. Ideally
a fuel composition which results from carrying out the present
invention will also have a sulphur content falling within these
limits.
[0059] Furthermore, a fuel composition prepared according to the
present invention, or a base fuel used in such a composition may
contain one or more fuel additives, or may be additive-free. If
additives are included (e.g. added to the fuel at the refinery), it
may contain minor amounts of one or more additives. Selected
examples or suitable additives include (but are not limited to):
anti-static agents; pipeline drag reducers; flow improvers (e.g.
ethylene/vinyl acetate copolymers or acrylate/maleic anhydride
copolymers); lubricity enhancing additives (e.g. ester- and
acid-based additives); viscosity improving additives or viscosity
modifiers (e.g. styrene-based copolymers, zeolites, and high
viscosity fuel or oil derivatives); dehazers (e.g. alkoxylated
phenol formaldehyde polymers); anti-foaming agents (e.g.
polyether-modified polysiloxanes); 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); corrosion
inhibitors; reodorants; anti-wear additives; antioxidants (e.g.
phenolics such as 2,6-di-tert-butylphenol); metal deactivators;
combustion improvers; static dissipator additives; antioxidants;
and wax anti-settling agents. The composition may for example
contain a detergent. Detergent-containing diesel fuel additives are
known and commercially available. Such additives may be added to
diesel fuels at levels intended to reduce, remove or slow the build
up of engine deposits. Examples of detergents suitable for use in
diesel fuel additives for the present purpose include polyolefin
substituted succinimides or succinamides of polyamines, for
instance polyisobutylene succinimides or polyisobutylene amine
succinamides, aliphatic amines, Mannich bases or amines and
polyolefin (e.g. polyisobutylene) maleic anhydrides. Succinimide
dispersant additives are described for example in GB-A-960493,
EP-A-0147240, EP-A-0482253, EP-A-0613938, EP-A-0557516 and
WO-A-98/42808. Particularly preferred are polyolefin substituted
succinimides such as polyisobutylene succinimides.
[0060] Other detergents suitable for use in diesel fuel additives
for the present purpose include quaternary ammonium salts such as
those disclosed in US2012/0102826, US2012/0010112, WO2011/149799
and WO2011/110860.
[0061] In some embodiments, it may be advantageous for the fuel
composition to contain an anti-foaming agent, more preferably in
combination with an anti-rust agent and/or a corrosion inhibitor
and/or a lubricity enhancing additive.
[0062] Where the composition contains such additives (other than
the 2-EHN and one or more organic peroxides described hereinabove),
it suitably contains a minor proportion (such as 1% w/w or less,
0.5% w/w or less, 0.2% w/w or less), of the one or more fuel
additives, in addition to the 2-EHN and the one or more organic
peroxides. Unless otherwise stated, the (active matter)
concentration of each such additive component in the fuel
composition may be up to 10000 ppmw, such as in the range of 0.1 to
1000 ppmw; and advantageously from 0.1 to 300 ppmw, such as from
0.1 to 150 ppmw.
[0063] If desired, one or more additive components, such as those
listed above, may be co-mixed (e.g. together with suitable diluent)
in an additive concentrate, and the additive concentrate may then
be dispersed into a base fuel or fuel composition. In some cases,
it may be possible and convenient to incorporate the 2-EHN and/or
the one or more organic peroxides into such an additive
formulation. Thus, the 2-EHN and/or one or more organic peroxides
may be pre-diluted in one or more such fuel components, prior to
its incorporation into the final automotive fuel composition. Such
a fuel additive mixture may typically contain a detergent,
optionally together with other components as described above, and a
diesel fuel-compatible diluent, which may be a mineral oil, a
solvent such as those sold by Shell companies under the trade mark
"SHELLSOL", a polar solvent such as an ester and, in particular, an
alcohol (e.g. hexanol, 2-ethylhexanol, decanol, isotridecanol and
alcohol mixtures such as those sold by Shell companies under the
trade mark "LINEVOL", especially LINEVOL 79 alcohol which is a
mixture of C.sub.7-9 primary alcohols, or a C.sub.12-14 alcohol
mixture which is commercially available).
[0064] The total content of the additives in the fuel composition
may be suitably between 0 and 10000 ppmw and more suitably below
5000 ppmw.
[0065] As used herein, amounts (e.g. concentrations, ppmw and %
w/w) of components are of active matter, i.e. exclusive of volatile
solvents/diluent materials.
[0066] An automotive diesel fuel composition prepared according to
the present invention will suitably comply with applicable current
standard specification(s) such as, for example, EN 590 (for Europe)
or ASTM D-975 (for the USA). By way of example, the overall fuel
composition may have a density from 820 to 845 kg/m.sup.3 at
15.degree. C. (ASTM D-4052 or EN ISO 3675); a T95 boiling point
(ASTM D-86 or EN ISO 3405) of 360.degree. C. or less; a measured
cetane number (ASTM D-613) of 51 or greater; a VK 40 (ASTM D-445 or
EN ISO 3104) from 2 to 4.5 mm.sup.2/s; a sulphur content (ASTM
D-2622 or EN ISO 20846) of 50 mg/kg or less; and/or a polycyclic
aromatic hydrocarbons (PAH) content (IP 391 (mod)) of less than 8%
w/w. Relevant specifications may, however, differ from country to
country and from year to year, and may depend on the intended use
of the fuel composition.
[0067] It will be appreciated, however, that a diesel fuel
composition prepared according to the present invention may contain
fuel components with properties outside of these ranges, since the
properties of an overall blend may differ, often significantly,
from those of its individual constituents.
Uses and Methods
[0068] In accordance with one aspect of the invention, there is
provided the use of 2-EHN and one or more organic peroxides for
improving the fuel economy performance of a fuel composition. In
the context of the present invention, use of 2-EHN and one or more
organic peroxides in a fuel composition means incorporating the
2-EHN and/or the one or more organic peroxides into the
composition, typically as a blend (i.e. a physical mixture) with
one or more fuel components (typically diesel base fuels) and
optionally with one or more fuel additives.
[0069] The 2-EHN and the one or more organic peroxides are
preferably incorporated into the fuel composition before the
composition is introduced into an engine which is to be run on the
composition. Accordingly, the 2-EHN and the one or more organic
peroxides may be dosed directly into (e.g. blended with) one or
more components of the fuel composition or the base fuel at the
refinery. For instance, they may be pre-diluted in a suitable fuel
component, which subsequently forms part of the overall automotive
fuel composition. Alternatively, they may be added to a diesel fuel
composition downstream of the refinery. For example, they may be
added as part of an additive package containing one or more other
fuel additives. This can be particularly advantageous because in
some circumstances it can be inconvenient or undesirable to modify
the fuel composition at the refinery. For example, the blending of
base fuel components may not be feasible at all locations, whereas
the introduction of fuel additives, at relatively low
concentrations, can more readily be achieved at fuel depots or at
other filling points such as road tanker, barge or train filling
points, dispensers, customer tanks and vehicles.
[0070] The 2-EHN and/or one or more organic peroxides may be
supplied as a component of a formulation which is suitable for
and/or intended for use as a fuel additive, in particular a diesel
fuel additive. By way of example, the 2-EHN and/or one or more
organic peroxides may be incorporated into an additive formulation
or package along with one or more other fuel additives. As
described above, the one or more fuel additives may be selected
from any useful additive, such as detergents, anti-corrosion
additives, esters, poly-alpha olefins, long chain organic acids,
components containing amine or amide active centres, and mixtures
thereof, as is known to the person of skill in the art.
[0071] According to another aspect of the invention, there is
provided a process for the preparation of an automotive fuel
composition, which process involves blending a diesel base fuel (or
base fuel mixture) with 2-EHN and one or more organic peroxides,
such as a cyclic methylethyl ketone peroxide. The blending may be
carried out for one or more of the purposes described herein.
[0072] In some cases the 2-EHN and/or the one or more organic
peroxides may not be suitable for pre-mixing with other fuel
additives and may, therefore, be dosed directly into the fuel
composition from a concentrated (100%) or pre-diluted stock.
[0073] It has been found that the combination of 2-EHN and one or
more organic peroxides, such as cyclic methylethyl ketone peroxide,
can, at relatively low concentrations, improve the fuel economy of
a diesel fuel composition by an amount greater than other known
cetane enhancers under some engine operating conditions, for
example under harsh engine working conditions (e.g. high engine
speeds and powers).
[0074] While the amount of the 2-EHN and the one or more organic
peroxides for use in accordance with the invention may vary
depending of fuel type and/or engine working conditions to be used,
a further benefit of the invention is that under some engine
conditions the amount of 2-EHN and/or the one or more organic
peroxides needed to observe the benefit of the invention may be
surprisingly low, such as at the level of typical fuel
additives.
[0075] This in turn can reduce the cost and complexity of the fuel
preparation process. For example, it can allow a fuel composition
to be altered in order to improve certain properties, by the
incorporation of additives downstream of the refinery, rather than
by altering the content of the base fuel at its point of initial
preparation. The blending of base fuel components may not be
feasible at all locations, whereas the introduction of fuel
additives, at relatively low concentrations, can more readily be
achieved at fuel depots or at other filling points such as road
tanker, barge or train filling points, dispensers, customer tanks
and vehicles. This in particular may be achievable where the 2-EHN
and/or one or more organic peroxides is sufficiently stable to
allow it to be transported under suitable conditions without taking
unnecessary safety risks. Of course, in some case it may not be
appropriate due to safety factors to transport the 2-EHN and/or the
one or more organic peroxides.
[0076] Moreover, an additive which is to be used at a relatively
low concentration can naturally be transported, stored and
introduced into a fuel composition more cost effectively than can a
fuel component which needs to be used at concentrations of the
order of tens of percent by weight.
[0077] Another aspect of the invention provides a method of
operating an internal combustion engine and/or a vehicle powered by
such an engine, which comprises introducing into a combustion
chamber of the engine a fuel composition prepared in accordance
with the invention. The fuel composition is advantageously
introduced for one or more of the purposes described in connection
with this invention. Thus, the engine is preferably operated with
the fuel composition for the purpose of improving fuel economy
during use of the engine and, for example, associated benefits such
as reduced engine emissions, etc. The engine is in particular a
diesel engine, and may be a turbo charged diesel engine. The diesel
engine may be of the direct injection type, for example of the
rotary pump, in-line pump, unit pump, electronic unit injector or
common rail type, or of the indirect injection type. It may be a
heavy or a light duty diesel engine. For example, it may be an
electronic unit direct injection (EUDI) engine.
[0078] Where relevant to a particular assessment, emission levels
may be measured using standard testing procedures such as the
European R49, ESC, OICA or ETC (for heavy-duty engines) or ECE+EUDC
or MVEG (for light-duty engines) test cycles. Ideally emissions
performance is measured on a diesel engine built to comply with the
Euro II standard emissions limits (1996) or with the Euro III
(2000), IV (2005) or even V (2008) standard limits.
[0079] Throughout the description and claims of this specification,
the singular encompasses the plural unless the context otherwise
requires. In particular, where the indefinite article is used, the
specification is to be understood as contemplating plurality as
well as singularity, unless the context requires otherwise.
[0080] Thus features, integers, characteristics, compounds,
chemical moieties or groups described in conjunction with a
particular aspect, embodiment or example of the present invention
are to be understood to be applicable to any other aspect,
embodiment or example described herein unless incompatible
therewith. Thus, features of the uses of the invention are directly
applicable to the methods of the invention. Moreover, unless stated
otherwise, any feature disclosed herein may be replaced by an
alternative feature serving the same or a similar purpose.
[0081] The invention will now be further illustrated by way of the
following non-limiting examples.
EXAMPLES
Example 1
Combustion Properties of Fuels Containing 2-EHN and Peroxides
[0082] Certain organic peroxide compounds were blended at various
levels into a standard low sulphur diesel fuel compliant with EN590
containing 600 mg/kg of 2-EHN. The specification of the base fuel
is shown in Table 1 below. The type and concentration of organic
peroxide compound in each fuel blend is shown in Table 3 below.
TABLE-US-00001 TABLE 1 Density IP365 836.1 kg/m.sup.3 Kinematic
Viscosity at 40.degree. C. IP71 2.738 mm.sup.2/s Initial boiling
point IP123 169.8.degree. C. Cold Filter Plugging Point IP309
-16.degree. C. Cloud Point IP219 -3.degree. C. Lubricity (HFRR wear
scar ISO 12156 163 .mu.m diameter) Sulphur ISO 20846 6.9 mg/kg
Total aromatics IP391 19.8% m/m
[0083] The fuel blends to be tested were subjected to ignition
testing in a Combustion Research Unit (CRU) obtained from Fueltech
Solutions AS/Norway. Fuels were injected into a constant volume
combustion chamber preconditioned as set out in Table 2 below.
[0084] The Derived Ignition Quality (DIQ) was determined as a
function of Ignition Delay (ID) recorded as the time from start of
injection (SOI) to the point where the chamber pressure has risen
to 0.2 bar above the pressure before SOI, denoted as DIQ.sup.0.2
(ID.sup.0.2). The results of these experiments are shown in Table
3.
TABLE-US-00002 TABLE 2 Chamber Injection Pulse Chamber pressure/
pressure/ width/ Condition Temperature/.degree. C. bar bar ms 01
590 75 900 0.9 02 560 50 900 0.9 03 530 30 900 0.9 04 590 65 1600
1.5 05 570 21.4 200 1.5
TABLE-US-00003 TABLE 3 Type Concen- of tration of Perox- peroxide
DIQ.sup.0.2 @ condition Fuel ide (mg/kg) 01 02 03 04 05 F1 (Base
none n/a 56.7 55.6 58.1 54.6 51.6 fuel including 600 mg/kg 2-EHN)
F2 DTBP 100 56.6 55.0 57.9 56.6 51.6 F3 DTBP 300 57.8 56.4 60.2
56.6 52.2 F4 TTTP 100 58.1 56.6 59.0 55.6 52.2 F5 TTTP 300 60.5
59.4 60.8 59.5 53.1 In Table 3, the abbreviations used have the
following meanings: DTBP = ditertbutylperoxide (commercially
available from Akzo Nobel under the tradename Trigonox B); TTTP =
3,6,9-Triethyl-3,6,9-trimethyl-1,4,7-triperoxonane (commercially
available from Akzo Nobel under the tradename Trigonox 301). In
simple terms the higher the DIQ.sup.0.2 value, the better the
performance. The results of Table 3 demonstrate both peroxides
perform well in conjunction with 2-EHN, but that the better
performing peroxide is the cyclic ketone peroxide TTTP.
Example 2
Measuring Ignition Quality on CID 510
[0085] The ignition quality of 2-EHN and/or organic peroxide
containing fuels was also investigated using the standard test
method PAC cetane ID510 (according to ASTMD7668). 2-EHN and/or the
organic peroxide TTTP were blended into market diesel fuel
compliant to EN590. Selected properties of the base fuel are shown
in Table 4 below. Table 5 shows the concentration of 2-EHN and TTTP
used in each fuel blend tested. Table 5 also shows the Derived
Cetane Number (DCN) of each of the fuel blends tested in this
Example.
[0086] FIG. 1 shows the Derived Cetane Number (DCN) of each of the
fuel blends tested in Example 2.
TABLE-US-00004 TABLE 4 Density DIN EN ISO 12185 843.1 kg/m.sup.3
Initial boiling point DIN EN ISO 3405 174.4.degree. C. Cold Filter
Plugging DIN EN 116 -16.degree. C. Point Cloud Point DIN EN 23015
-5.degree. C. Sulphur ISO 20846 <10 mg/kg
TABLE-US-00005 TABLE 5 2-EHN (mg/kg) TTTP (mg/kg) DCN 0 0 54.04 300
0 55.95 600 0 56.89 900 0 57.59 1200 0 59.05 1500 0 59.45 1800 0
59.98 2100 0 60.99 2400 0 61.37 0 0 54.04 0 300 56.13 0 600 56.03 0
900 57.38 0 1200 58.29 0 1500 59.12 0 1800 59.53 0 2100 59.95 0
2400 60.10 0 300 56.13 600 0 57.23 600 300 59.03 600 600 59.10 600
900 58.57 600 1200 59.04 600 1500 59.61 600 1800 60.18
Example 3
Fuel Economy Test Method: Measurement of Fuel Consumption
Benefits
[0087] Fuel consumption was measured using a Renault Megane (1.5
dCi common rail engine, max power output 78 kw, DPF, EURO4
emissions standard, manufacturing year 2009) run at constant speed
of 50 km/h on a chassis dynamometer (CD) applying road load
conditions with automated driving. The test cell was preconditioned
to 23.degree. C. FC consumption was measured gravimetrically using
a corriolis device (Siemens) over a period of 30 minutes. Test and
reference fuel were each repeated eight times in an A-B-A-B . . .
and so on test design. Fuel was taken from individual 25 L drums
and all lines were flushed with the fuel to be tested test before
restarting the measurement. The overall fuel consumption of a test
fuel was compared with overall fuel consumption of a reference fuel
to obtain a fuel economy benefit.
[0088] Fuels were blended by dissolving either 2-EHN and/or organic
peroxide into market typical AGO (Automotive Gas Oil) from the
German market complying with DIN EN590. Table 6 below shows the
properties of the AGO base fuel.
TABLE-US-00006 TABLE 6 Density DIN EN ISO 12185 839.1 kg/m.sup.3
Initial boiling point DIN EN ISO 3405 169.7.degree. C. Kinematic
Viscosity DIN EN ISO3104 2.567 mm.sup.2/s Sulphur DIN EN ISO 20884
7 mg/kg Flash point DIN EN ISO 2719 63.0.degree. C. Cetane Number
DIN EN ISO 5165 50.7
[0089] The reference fuel was the base AGO fuel with the addition
of 600 mg/kg 2-EHN. The test fuel was the reference fuel with the
addition of 600 mg/kg (on an active matter basis) of Trigonox
301.
[0090] Table 7 below shows the fuel consumption of the fuels tested
together with the % improvement in fuel economy benefit of the test
fuel compared with the reference fuel.
TABLE-US-00007 TABLE 7 FC of Reference Fuel FC of Test Fuel Repeat
(L per 100 km) (L per 100 km) FE benefit/% 1 2.788 2.771 0.62 2
2.783 2.767 0.57 3 2.780 2.761 0.69 4 2.811 2.802 0.31 5 2.787
2.771 0.58 6 2.776 2.770 0.24 7 2.795 2.773 0.78 8 2.783 2.763 0.71
average 2.788 2.772 0.56
DISCUSSION
[0091] The results shown in Table 7 demonstrate an improvement in
fuel economy for the test fuel (containing a combination of 2-EHN
and Trigonox 301) compared to the reference fuel (containing 2-EHN
only).
* * * * *