U.S. patent application number 09/732374 was filed with the patent office on 2002-08-08 for diesel fuel composition.
Invention is credited to Bateman, John Richard, Caers, Raf F., Miller, Richard C., Schlosberg, Richard Henry, Yeh, Lisa I-Ching.
Application Number | 20020104256 09/732374 |
Document ID | / |
Family ID | 26868594 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104256 |
Kind Code |
A1 |
Yeh, Lisa I-Ching ; et
al. |
August 8, 2002 |
Diesel fuel composition
Abstract
This invention relates to an ultra-low sulphur fuel composition
comprising (A) a major amount of a base fuel having (a) no more
than 50 ppm by weight of sulphur, (b) no more than 10% by weight of
olefins and (c) no more than 10% by weight of an ester and (B) at
least 1% by weight based on the total fuel composition of an
oxygenate selected from its group consisting of a saturated,
aliphatic monohydric alcohol having 4 to 20 carbon atoms, ketone
having on an average 5 to 25 carbons and mixtures of the alcohol(s)
and ketone(s) and having no other oxygen atom in its structure.
These specific oxygenates further reduce particulate emissions from
the exhausts of engines powered by ultra-low sulphur diesel fuels
which fuels are already known to generate low particulate
emissions. These oxygenates are capable of an impressive
performance with respect to particulate emissions over a broad
range of vehicles and driving cycles when compared with the
performance of oxygenates used hitherto.
Inventors: |
Yeh, Lisa I-Ching; (Marlton,
NJ) ; Schlosberg, Richard Henry; (Bridgewater,
NJ) ; Miller, Richard C.; (Baton Rouge, LA) ;
Bateman, John Richard; (Hermitage, GB) ; Caers, Raf
F.; (Edegem, BE) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
(formerly Exxon Research and Engineering Company)
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
26868594 |
Appl. No.: |
09/732374 |
Filed: |
December 7, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60172914 |
Dec 21, 1999 |
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Current U.S.
Class: |
44/451 ;
44/452 |
Current CPC
Class: |
C10L 1/026 20130101;
C10L 10/02 20130101 |
Class at
Publication: |
44/451 ;
44/452 |
International
Class: |
C10L 001/10 |
Claims
What is claimed is:
1. A fuel composition comprising: (A) a major amount of a base fuel
having a. no more than 50 ppm by weight of sulphur, b. no more than
10% by weight of olefins, c. no more than 10% by weight of an ester
and (B) at least 1% by weight based on the total fuel composition
of an oxygenate selected from the group consisting of saturated,
aliphatic monohydric primary, secondary, tertiary alcohol and
mixtures thereof having an average of from 4-20 carbon atoms, one
or more mono- or poly-ketone or keto-monohydric aliphatic alcohol
having on an average 5 to 25 carbons, and mixtures of the aforesaid
alcohol(s) and ketone(s) and having no other oxygen atom in its
structure.
2. The composition according to claim 1 wherein the fuel is an
ashless diesel fuel.
3. The composition according to claim 1 wherein the fuel
composition contains less than 5% by weight of olefins.
4. The composition according to claim 1 wherein the base fuel has a
density below 850 kg/m.sup.3 and a T.sub.95 of no more than
345.degree. C.
5. The composition according to claim 1 wherein the alcohol has on
average from 9-20 carbon atoms.
6. The composition according to claim 1 wherein the saturated,
aliphatic monohydric alcohol is a primary alcohol.
7. The composition according to claim 1 wherein the saturated
aliphatic monohydric alcohol is a branched chain alcohol.
8. The composition according to claim 1 wherein the ketone has on
an average 5 to 21 carbons.
9. The composition according to claim 1 wherein the ketone has on
an average 7 to 15 carbons.
10. The composition according to claim 1 wherein the saturated
aliphatic monohydric alcohol is selected from pentanol,
iso-pentanol, hexanol, iso-hexanol, heptanol, iso-heptanol,
octanol, iso-octanol, 2-ethylhexanol, nonanol, iso-nonanol,
2-propyl heptanol, 2,4-dimethyl heptanol, decanol, iso-decanol,
undecanol, iso-undecanol, dodecanol, iso-dodecanol, tridecanol,
iso-tridecanol, tetradecanol, iso-tetradecanol, myristyl alcohol,
hexadecanol, octadecanol, stearyl alcohol, isostearyl alcohol,
eicosanol, diisobutyl carbinol, tetrahydrolinalool, and mixtures
thereof.
11. The composition according to claim 1 wherein the oxygenate is
used in an amount such that the final fuel composition has at least
0.5% w/w of oxygen.
12. A method of reducing particulate emissions from an internal
combustion engine powered by a fuel composition comprising a major
amount of a base fuel having a. no more than 50 ppm by weight of
sulphur, b. no more than 10% by weight of olefins, and c. no more
than 10% by weight of an ester said method comprising blending said
base fuel with at least 1% by weight based on the total fuel
composition of an oxygenate selected from the group consisting of
saturated, aliphatic monohydric primary, secondary, tertiary
alcohol and mixtures thereof having an average of from 4-20 carbon
atoms, one or more mono- or polyketone or keto-monohydric alcohol
having on an average 5 to 25 carbons, and mixtures of the aforesaid
alcohol(s) and ketone(s), and having no other oxygen atom in its
structure.
Description
[0001] This invention relates to fuel compositions of low sulphur
content which contain at least one component capable of reducing
particulate emissions from the exhausts of engines which generate
power by combustion of such fuels.
[0002] Of particular interest are fuels such as diesel which are
used widely in automotive transport and for providing power for
heavy duty equipment due to their high fuel economy. However, one
of the problems when such fuels are burned in internal combustion
engines is the pollutants in the exhaust gases that are emitted
into the environment. For instance, some of the most common
pollutants in diesel exhausts are nitric oxide and nitrogen dioxide
(hereafter abbreviated as "NO.sub.X"), hydrocarbons and sulphur
dioxide, and to a lesser extent carbon monoxide. In addition,
diesel powered engines also generate a significant amount of
particulate emissions which include inter alia soot, adsorbed
hydrocarbons and sulphates, which are usually formed due to the
incomplete combustion of the fuel and are hence the cause of dense
black smoke emitted by such engines through the exhaust. The oxides
of sulphur have recently been reduced considerably by refining the
fuel, e.g., by hydrodesulphurisation thereby reducing the sulphur
levels in the fuel itself and hence in the exhaust emissions.
However, the presence of particulate matter in such exhaust
emission has been a more complex problem. It is known that the
primary cause of the particulate matter emission is incomplete
combustion of the fuel and to this end attempts have been made to
introduce into the fuel organic compounds which have oxygen value
therein (hereafter referred to as "oxygenates") to facilitate
combustion. Oxygenates are known to facilitate the combustion of
fuel to reduce the particulate matter and the use of alcohols as
oxygenates has been described in the prior art especially with
respect to conventional diesel fuels which have a relatively high
sulphur content of, e.g., >200 ppm. For instance, U.S. Pat. No.
5,425,790 describes the use of alcohols and glycols for reducing
particulate emissions from such relatively high sulphur diesel
fuels. The authors confirm that the amount of reduction in
particulate matter scales roughly linearly with the oxygen content
of the component added although ethers seem to be more effective
for reducing particulates than alcohols for the same oxygen
content.
[0003] U.S. Pat. No. 4,378,973 discloses the use of a combination
of cyclohexane and an oxygenated additive for reducing particulate
emissions from fuels. This document states that the beneficial
effect cannot be achieved in the absence of cyclohexane. This
document discloses 2-ethyl hexanol and "EPAL 1012" which comprises
a mixture of normal C.sub.6-C.sub.20 alcohols as the oxygenated
additives. However, there is no mention of the sulphur content of
such fuels.
[0004] A further reference, WO 93/24593, is primarily concerned
with gasohol blends from diesel and alcohols. This blend must
contain 20-70% by volume of ethanol or methanol, 1-15% by volume of
a tertiary alkyl peroxide and 4.5-5.5% by volume of a higher
straight chain alcohol. The straight chain alcohols disclosed have
from 3-12 carbon atoms. According to this reference the presence of
a tertiary alkyl peroxide is essential for the performance of the
fuel since using 10% v/v alcohol performs no better than a straight
diesel whereas 30% v/v of ethanol "severely degraded the engine's
operation" (page 8, lines 14-19).
[0005] WO 98/35000 relates to lubricity enhancing agents and makes
no mention of controlling or reducing emission of particulate
matter. This document discloses the use of primary, linear C7+
alcohols in an amount of <5% w/w of a diesel fuel
composition.
[0006] U.S. Pat. No. 5,324,335 and U.S. Pat. No. 5,465,613 both in
the name of the same assignee relate to fuels produced by the
Fischer-Tropsch process which also contain inter alia alcohols
formed in situ in the process which is recycled to the process.
Whilst several primary alcohols are disclosed most of these are
linear except the reference to methyl butanol and methyl pentanol.
However, the streams recycled contain a considerable amount of
other components such as, e.g., aldehydes, ketones, aromatics,
olefins, etc. Also, the amount of alcohols generated by this
process, especially the content of branched alcohols (<0.5%),
appears to be very low in relation to the total stream recycled.
These two do refer to the use of Fischer Tropsch diesel fuels which
have a sulphur content of less than 50 ppm.
[0007] U.S. Pat. No. 5,720,784 refers to fuel blends and the
difficulty in rendering diesel fuels miscible with the
conventionally used methanol and ethanol. This document purports to
mitigate the problem of miscibility by adding to such formulations
a C.sub.3 (excluding n-propanol)-C.sub.22 organic alcohol. However,
whilst the document refers to the use of higher alcohols to form
single phase compositions which are not prone to separation, it is
silent on the nature of the diesel fuel --for these can vary
significantly in their composition from light naphtha to heavy duty
diesel oils--nor indeed the effect of any of the alcohols referred
to on the problems of particulate emissions when using such fuels
in diesel fuel powered internal combustion engines. Furthermore,
when addressing the issue of miscibility, it fails to distinguish
between fuel compositions which contain the lower C.sub.1 and
C.sub.2 alcohols and compositions which contain no lower alcohols.
There is no mention of the sulphur content of fuels.
[0008] More recently, ashless diesel fuels having an ultra-low
sulphur (.ltoreq.50 ppm) content are also known as Ultra Low
Sulphur Automotive Diesel Oil (hereafter "ULSADO"), a density of no
more than 835 kg/m.sup.3, and a T.sub.95 (i.e., a temperature by
which 95% of the fuel has distilled) of no more than 345.degree. C.
have been developed. Such fuels are considered as "clean" diesel
fuels and are expected to have lower particulate emissions over a
broad range of vehicles than the fuels of relatively higher sulphur
content used hitherto.
[0009] WO 92/20761 discloses compositions comprising biodiesel in
which the base fuels are predominantly esters and alcohols. There
is no mention in this document of reducing particulate matter from
emissions.
DESCRIPTION OF THE FIGURES
[0010] FIGS. 1A and 1B graphically present the data for absolute
particulate matter (PM) and NO.sub.X emissions measured for a
ULSADO base fuel and the base fuel containing 2% oxygen from
primary, secondary and tertiary saturated aliphatic monohydric
alcohol and ketone.
[0011] FIG. 2 graphically presents and compares the emissions data
relating to PM, NO.sub.X, HC, and CO for ULSADO fuel additized with
primary, secondary and tertiary saturated aliphatic monohydric
alcohols and ketone.
[0012] It has now been found that certain specific oxygenates when
added to the ultra-low sulphur diesel fuels can enable the
particulate emissions from the exhausts of engines powered by these
relatively clean fuels to be substantially reduced further when
compared with some of the additives used hitherto with little to no
NO.sub.X increase.
[0013] Accordingly, an embodiment of the present invention is a
fuel composition comprising a major amount of a base fuel
having:
[0014] a. no more than 50 ppm by weight of sulphur,
[0015] b. no more than 10% by weight of olefins,
[0016] c. no more than 10% by weight of an ester and
[0017] d. at least 1% by weight based on the total fuel composition
of an oxygenate selected from the group consisting of a saturated,
aliphatic monohydric primary, secondary, tertiary alcohol and
mixture thereof having an average of from 4-20 carbon atoms, one or
more mono- or poly-ketones or keto-monohydric aliphatic alcohol
having on an average 5 to 25 carbons, and mixtures of the aforesaid
and alcohol(s) and ketone(s), and having no other oxygen atom in
its structure.
[0018] The fuels that may be used as base fuels comprise inter alia
distillate fuels, and typically comprise a major amount of diesel
fuel, jet fuel, kerosene, bunker fuel or mixtures thereof. The
fuels, especially the diesel fuels, are suitably ashless fuels.
[0019] The feature of an embodiment of the invention is that the
addition of at least one of the aforesaid alcohol(s), ketone(s) or
mixture thereof to a base fuel such as, e.g., the ULSADO base
fuel--which is considered a "clean fuel"--surprisingly reduces
further the particulate emissions from such so called "clean"
fuels.
[0020] The olefin content of the fuel compositions of an embodiment
of the present invention are not intended to include diesel fuels
which contain substantial amounts of olefins (e.g., greater than
40% by weight) such as those produced in some of the
Fischer-Tropsch processes. In any event, the fuel compositions of
an embodiment of the present invention contain no more than 10% by
weight of olefins, suitably less than 5% by weight of olefins and
preferably less than 2% by weight of olefins. Such fuels may be
produced by modified Fischer-Tropsch processes to control the
olefins formed therein to below the threshold levels now specified.
Furthermore, the base fuel used in the present invention has less
than 10% by weight of esters, i.e., the base fuels do not include
the so called biodiesels.
[0021] The diesel fuel suitably comprises at least 70% by weight,
preferably at least 80% by weight of the base fuel, more preferably
greater than 85% by weight of the base fuel. The base fuel suitably
contains greater than 1% by weight of aromatics, preferably greater
than 5% by weight of aromatics and even more preferably from 5-20%
by weight of aromatics. The base fuel suitably has a density below
855 kg/m.sup.3, preferably no more than 835 kg/m.sup.3. The base
fuel suitably has a T.sub.95 of no more than 345.degree. C.
[0022] The saturated, aliphatic, monohydric primary, secondary,
tertiary alcohols used in the fuel compositions of an embodiment of
the present invention may be used singly or as an admixture. The
alcohols may also be in the form of an isomeric mixture. The
saturated, aliphatic monohydric alcohols used in the compositions
of the present invention are suitably primary, secondary, or
tertiary alcohols which may be straight chain alcohols, branched
chain alcohols or mixtures thereof. The alcohols suitably have on
an average from 4-20 carbon atoms, preferably from 6-20 carbon
atoms and more preferably from 8-20 carbon atoms. Particularly
preferred are alcohols having on average from 9-18 carbon atoms. It
is particularly preferable that where a mixture of alcohols is
used, and in certain instances where a single alcohol is used, said
mixture or single alcohols comprises a predominate amount of at
least one of the branched chain alcohol referred to herein. Thus,
the alcohols are suitably selected from open chain alcohols, such
as, e.g., pentanol, iso-pentanol, hexanol, iso-hexanol, heptanol,
iso-heptanol, octanol, iso-octanol, 2-ethylhexanol, nonanol,
iso-nonanol, 2-propyl heptanol, 2,4-dimethyl heptanol, decanol,
iso-decanol, undecanol, iso-undecanol, dodecanol, iso-dodecanols,
tridecanol, iso-tridecanol, tetradecanol, iso-tetradecanol,
myristyl alcohol, hexadecanol, octadecanol, stearyl alcohol,
isostearyl alcohol, eicosanol, di-isobutyl carbinol,
tetrahydro-linalool and mixtures thereof, especially Exxal.RTM.-10,
Exxal.RTM.-12 and Exxal.RTM.-13. In these expressions the term
"iso" is generally meant to indicate a mixture of branched
alcohols. For instance, iso-nonanol represents a mixture containing
approximately 85% 3,5,5-trimethyl hexanol, iso-decanol represents a
mixture of C.sub.9-C.sub.11 alcohols, iso-dodecanol represents a
mixture of C.sub.11-C.sub.13 alcohols, isotri-decanol a mixture of
C.sub.12-C.sub.14 alcohols and iso-tetradecanol is a mixture of
linear and branched chain C.sub.13-C.sub.15 alcohols. Several of
the alcohols referred to herein may be derived from natural
sources. These alcohols, for instance, belong to two families,
i.e., the lauric oils (primarily from coconut oil, palm kernel oil
and jojoba oil) and the stearic oils. The lauric oils give rise to
alcohols in the C.sub.6-C.sub.18 range peaking in C.sub.12-C.sub.14
(respectively C.sub.12=lauryl alcohol and C.sub.14=myristyl
alcohol) alcohols. The stearic oils led to alcohols in the
C.sub.14-C.sub.22 range peaking in C.sub.16-C.sub.18 (respectively
C.sub.16=cetyl alcohol and C.sub.18=stearyl alcohol) alcohols.
Since these are generally produced by hydrogenation of the
corresponding acids or methyl esters, these alcohols are considered
to be saturated alcohols. It is the intention to embrace within its
scope the use of such alcohols and mixtures thereof in the fuel
compositions. Particularly preferred examples of the alcohols that
may be used are iso-nonanol and iso-decanol.
[0023] The term ketone includes mono- and poly-ketone or
keto-monohydric aliphatic alcohol may contain straight chain or
branched chain aliphatic groups and mixtures thereof attached to
the central carbonyl (C.dbd.O) group, or aromatic or naphthenic
groups, or mixtures of aliphatic and aromatic groups, preferably
one or both of the groups are aliphatic groups which may themselves
be substituted with aryl moiety (e.g., phenyl, napthyl groups,
etc.), preferably the alkyl groups are unsubstituted. The ketones
suitably have on an average 5 to 25 carbon atoms, preferably on an
average 5 to 21 carbon atoms, more preferably on an average of 7-21
carbons, still more preferably on an average of 7-17 carbons.
Examples of suitable ketones include di-n-propyl ketone,
cyclo-pentanone, cyclohexanone, methyl undecylketone,
8-pentadecanne, 2-hepta-decanone, 9-eicosanone, 10-heneicosanone,
and 2- doeicosanone as well as alkyl derivatives thereof and
mixtures thereof. The ketones most preferred are open chain ketones
such as di-ethyl ketone, methyl propyl ketone, methyl isopropyl
ketone, ethyl propyl ketone, ethyl isopropyl ketone, di-n-propyl
ketone, di-isopropyl ketone, isopropyl isobutyl ketone, di-n-butyl
ketone, di-isobutyl ketone, di-n-pentyl ketone, di-isopentyl
ketone, isobutyl isopentyl ketone, isopropyl isopentyl ketone,
di-n-hexyl ketone, di-isohexyl ketone, isopentyl isohexyl ketone,
and other ketones having aliphatic groups wherein each aliphatic
group is independently a straight chain, singly branched chain or
multiply branched chain aliphatic group. As previously stated, also
included are hydrocarbons with multiple ketone functions as well as
with mixed ketone and monohydric aliphatic alcohol function (e.g.,
keto-monohydric aliphatic alcohol), such keto-monohydric aliphatic
alcohol having up to 25 carbons in total.
[0024] The fuel compositions are suitably substantially free of
C.sub.1-C.sub.2 alcohols, i.e., they are present in an amount of
<5% by weight, preferably .ltoreq.1% by weight, of the total
composition.
[0025] The amount of any of the oxygenates referred to above and
used in the compositions of the present invention is at least 1% by
weight of the total composition and is such that it is capable of
providing the composition with at least 0.5% w/w of oxygen,
suitably at least 1.0% by weight of oxygen and preferably at least
2% by weight of oxygen. Thus to achieve this composition, the
amount of oxygenate added to the composition is suitably greater
than 2% by weight of the total composition, and is preferably
greater than 5% w/w and more preferably greater than 7% by weight
of the total composition. Typically, the oxygenate(s) is (are) used
in an amount in the range from 7 to 60% by weight, preferably from
7 to 40 % by weight of the total composition. Within these ranges,
it would be possible to use a relatively low amount of a specific
oxygenate, if said oxygenate has a relatively high oxygen content
and conversely, one may have to use a higher amount of a particular
oxygenate, if it is relatively low in oxygen content. This improved
performance in reducing particulate emission is achieved without
recourse to the use of further additives such as, e.g., cyclohexane
or peroxides or the use of aromatic alcohols. A further feature is
that these oxygenates are capable of an impressive performance with
respect to particulate emissions over a broad range of vehicles and
driving cycles when compared with the performance of esters,
glycols and ethers used hitherto for this purpose which perform
only over a restricted range of vehicles and driving cycles. An
additional feature is that the particulate reduction is obtained
with little to no increase in NOx emissions at high engine
loads.
[0026] The diesel fuel composition may contain one or more
conventional fuel additives, which may be added at the refinery, at
the fuel distribution terminal, into the tanker, or as bottle
additives purchased by the end user for addition into the fuel tank
of an individual vehicle. These additives may include cold flow
improvers (also known as middle distillate flow improvers), wax
antisettling additives, diesel fuel stabilizers, antioxidants,
cetane improvers, combustion improvers, detergents, demulsifiers,
dehazers, lubricity additives, anti-foamants, anti-static additive,
conductivity improvers, corrosion inhibitors, drag reducing agents,
reodorants, dyes and markers, and the like.
[0027] Fuels compositions of an embodiment of the present invention
were prepared by blending a fuel having no more than 10% by weight
of olefins and no more than 10% by weight of an ester with at least
5% by weight based on the total composition of at least one
saturated, aliphatic monohydric alcohol having on average from 4-20
carbon atoms, or a ketone having on an average of 5 to 25
carbons.
[0028] The alcohols used in an embodiment of the fuel compositions
were evaluated for their performance in reducing particulate
emission using a single cylinder Caterpillar 3406 HD engine (which
is a Cat 1Y450 engine) with gaseous emission analyses for:
hydrocarbons, NO.sub.X, carbon monoxide, carbon dioxide, oxygen
(Horiba, Mexa-9100 DEGR) and a full dilution particulate tunnel
(Horiba, DLS-9200). The particulates generated in the combustion
process are collected on a 70 mm diameter Whatman GF/A glass fibre
filter paper after the primary dilution tunnel. No secondary
dilution is used. The filter papers used are stabilized and weighed
both before and after testing. Stabilization conditions are at a
temperature of 20.+-.2.degree. C. and at a relative humidity of
45.+-.10%. The difference in weight measured is taken to be the
mass of particulate matter collected. The analytical and sampling
systems for particulate collection conform to EEC Directive
88/77/EEC.
[0029] The performance of the compositions and additives of the
present invention are further illustrated with reference to the
following Examples and Comparative Tests:
EXAMPLE 1
[0030] In this Example the following base fuels and alcohols are
used:
[0031] LSADO--Low sulphur automotive diesel oil (ex Esso's Fawley
refinery) having the following characteristics:
1 Density - 851 kg/m.sup.3 KV20 (cSt) - 5.03 Sulphur content - 400
ppm T.sub.95 - 343.degree. C.
[0032] ULSADO--Ultra-low sulphur automotive diesel oil (ex Esso's
Fawley refinery) having the following characteristics:
2 Density - 825 kg/m.sup.3 kV.sub.20 (cSt) - 3.41 Sulphur content -
31 ppm T.sub.95 - 314.degree. C.
[0033] Exxal.RTM.10--Isodecanol (CAS No. 93821-11-5, EINECS No.
2986966, ex Exxon Chemicals)
[0034] Iso-nonanol--A mixture rich (80+% by weight) in
3,5,5-trimethylhexanol (CAS No. 3452-97-9, EINECS 222-376-7)
[0035] PM--Particulate Matter
[0036] The four fuel compositions tested were:
3 Fuel 1 - LSADO Fuel 2 - ULSADO Fuel 3 - ULSADO + 19.7% w/w Exxal
.RTM.-10 providing the fuel with 2% w/w oxygen content, and Fuel 4
- ULSADO + 18.0% w/w Isononanol providing the fuel with 2% w/w
oxygen content.
[0037] Emissions testing was carried out in a single cylinder
version of the Caterpillar 3406 heavy duty engine. A full dilution
tunnel with a primary dilution ratios of about 15:1 at low load was
used for particulate collection and analysis. Dynamic injection
timing was kept constant for the range of fuels tested and the
engine was supercharged using two external Roots pumps. The steady
state condition used for testing was at 1500 rpm and the low load
condition was 60 Nm. The dimensions of the engine used for testing
are shown in Table 1 below:
4 TABLE 1 Engine Cat 1Y540 Bore (mm) 137.2 Stroke (mm) 165.1 Swept
Volume (liters) 2.43 Compression ratio 13.37:1 Aspiration Simulated
turbo-charged
[0038] Each fuel was tested over 6 days in a randomized fuel test
sequence for each day to simulate varied driving conditions.
Particulate emissions from the engine exhausts were collected on
two filter papers for 10 minutes each and these results were
averaged to generate the data point for each fuel for each day.
[0039] The resultant particulate results are listed in Table 2
below for each fuel averaged over 6 test repeats as a % change
compared to LSADO, the base diesel fuel with 400 ppm sulphur.
5TABLE 2 Blend % Change Quantity Oxygen PM Mass compared to Fuel
Type (wt %) (wt %) (g/kWh) LSADO 1 - LSADO 0.0 0.0 0.485 0.0 2 -
ULSADO 0.0 0.0 0.377 -22.4 3 - ULSADO + Exxal .RTM.-10 19.7 2.0
0.339 -30.1 4 - ULSADO + Iso-nonanol 18.0 2.0 0.329 -32.3
[0040] From the above results it can be seen that the use of ULSADO
did reduce the particulate matter emissions under the low load
conditions used by 22.4% when compared with the LSADO fuel.
However, upon addition of the branched chain alcohols according to
an embodiment of the present invention, the particulate matter
emissions were surprisingly reduced a further 7.7% for
Exxal.RTM.-10 and 9.9% for Iso-nonanol compared to the ULSADO fuel
without these additives thus resulting in a total particulate
matter reduction in the emissions of 30.1% and 32.3% respectively
relative to the LSADO fuel. Both these reductions are substantial
and were surprisingly large since the emissions from ULSADO as such
were already quite low.
EXAMPLE2
[0041] The base fuel used was a Fawley ULSADO and this was blended
with the appropriate amount of oxygenate to achieve an oxygen
content in the final blend of 2% by weight. A primary alcohol,
secondary alcohol, tertiary alcohol and ketone were selected for
screening. The fuel details are shown in Table 5.
6TABLE 3 Blend % weight Ref. Fuel Description oxygenate UK ULSADO
Base Fuel 0 TO Base + Isodecanol Primary: Exxal 10 18.74 TL Base +
Dimethyl Secondary: Di-isobutyl carbinol 18.0 Heptanol TN Base +
Dimethyl Tertiary: Tetrahydrolinalool 19.75 Octanol TM Base +
Dimethyl Ketone: Di-isobutyl ketone 17.75 Heptanone
[0042] Testing was carried out on a single vehicle. The VW Golf 1.9
TDI was selected. This vehicle is a 1.9 liter turbo-charged
intercooled DI engine with an oxidation catalyst mounted very close
to the engine block, exhaust gas recirculation, and an
electronically controlled distributor fuel pump with a needle lift
sensor allowing for closed loop control of injection timing.
[0043] The fuel blends were tested according to a specific test
protocol and involved testing a base fuel against a different test
fuel each day. The base fuel was tested first followed by the test
fuel which was tested three times in succession followed by a final
base fuel test (base 1, test 1, test2, test3, base2). Each of these
five tests comprised a hot ECE+EUDC drive cycle. Gaseous and
particulate emissions were collected for each test.
[0044] Results and Discussion
[0045] Shown in FIG. 1A and 1B and Table 4 are the data for
absolute PM and NO.sub.X emissions measured for each fuel. In the
Figures the bars show the 95% least significant difference limits
and if these do not overlap then there is said to be significant
difference between fuels. All 4 oxygenates showed substantial and
significant reductions in particulate emissions relative to the
base ULSADO fuel. There was no statistically significant difference
between the type of oxygenates used. All 4 oxygenated blends also
generated higher absolute emissions of NO.sub.X than for the
ULSADO. However, for the tertiary alcohol and the ketone these
increases were only small and not statistically significant at the
95% level, as compared with the base fuel UK ULSADO.
[0046] FIG. 2 and Table 6 shows the relative change in emissions of
each oxygenated blend compared with the base fuel. The differences
observed from FIG. 1A and 1B are clearly represented here.
Reductions in particulate emissions varied from 19.8% (tertiary
alcohol) to 22.6% (primary & secondary alcohols and ketone).
The corresponding increases in NO.sub.X emissions relative to
ULSADO were 0.5% (tertiary), 1.0% (ketone), 3.8% (primary) and 4.4%
(secondary). The addition of an oxygenate to the base diesel fuel
also had the effect of increasing HC and CO emissions, although
these can be more easily controlled using an oxidation catalyst,
now common on all light-duty diesel vehicles. The increase in HC
and CO emissions do not outweigh the significance and importance of
the reduction in particulate matter.
7 TABLE 4 CO CO.sub.2 HC NOx PM Fuel g/km g/km g/km g/km g/km
ULSADO 0.230 130.1 0.064 0.479 0.047 Primary 0.297 128.5 0.071
0.497 0.037 Secondary 0.292 128.4 0.077 0.500 0.037 Tertiary 0.270
129.4 0.075 0.481 0.038 Ketone 0.280 128.2 0.081 0.484 0.037
Difference from ULSADO base [%] Fuel CO CO.sub.2 HC NO.sub.x PM
Primary 29.27095 -1.2042 9.98703 3.827418 -22.6033 Secondary
27.23975 -1.28107 19.84436 4.384134 -22.6033 Tertiary 17.51904
-0.56367 16.73152 0.487126 -19.7889 Ketone 22.01668 -1.46042
26.07004 0.974252 -22.6033
[0047] This data demonstrates that secondary and tertiary alcohols
and ketone produce a similar level of reduction in particulate
emissions from base fuel to that previously demonstrated with a
primary alcohol.
* * * * *