U.S. patent application number 09/732455 was filed with the patent office on 2002-08-15 for diesel fuel composition.
Invention is credited to Caers, Raf F., Miller, Richard C., Schlosberg, Richard Henry, Yeh, Lisa I-Ching.
Application Number | 20020108299 09/732455 |
Document ID | / |
Family ID | 26868589 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020108299 |
Kind Code |
A1 |
Yeh, Lisa I-Ching ; et
al. |
August 15, 2002 |
Diesel fuel composition
Abstract
This invention is a method of reducing particulate matter
emission from internal combustion engines which use a diesel fuel
composition comprising a major amount of a diesel fuel having a
base fuel which contains no more than 10% by weight of olefins and
no more than 10% by weight of esters, by admixing said fuel with
greater than 5% by weight based on the total composition of a
saturated, aliphatic monohydric alcohol having on an average from 4
to 20 carbon atoms, one or more ketones having on an average 5 to
25 carbons and mixture of said alcohol(s) and ketone(s). The amount
of the oxygenate in the fuel composition is sufficient to provide
the fuel with at least 0.5% by weight of oxygen. The oxygenate
significantly reduce particulate emissions from the exhausts of
diesel powered engines.
Inventors: |
Yeh, Lisa I-Ching; (Marlton,
NJ) ; Schlosberg, Richard Henry; (Bridgewater,
NJ) ; Miller, Richard C.; (Baton Rouge, LA) ;
Caers, Raf F.; (Edegem, BE) |
Correspondence
Address: |
EXXONMOBIL RESEARCH AND ENGINEERING COMPANY
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
26868589 |
Appl. No.: |
09/732455 |
Filed: |
December 7, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60172912 |
Dec 21, 1999 |
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Current U.S.
Class: |
44/439 ;
44/452 |
Current CPC
Class: |
C10L 1/026 20130101;
C10L 10/02 20130101 |
Class at
Publication: |
44/439 ;
44/452 |
International
Class: |
C10L 001/10 |
Claims
What is claimed is:
1. A method of reducing particulate emissions from a vehicle
powered by a diesel fuel composition comprising a major amount of a
diesel fuel having a base fuel which contains no more than 10% by
weight of olefins and no more than 10% by weight of esters, said
method comprising blending with the composition at least 5% by
weight based on the total composition of at least one oxygenate
selected from the group consisting of saturated, aliphatic
monohydric primary, secondary or tertiary alcohol and mixtures
thereof having on an average from 4 to 20 carbon atoms, one or more
mono- or poly-ketones or keto-monohydric aliphatic alcohols having
on an average 5 to 25 carbons, and mixtures of the aforesaid
alcohol(s) and ketone(s) said oxygenate containing no other oxygen
in its structure, the amount of the oxygenate in the composition
being sufficient to provide the fuel composition with at least 0.5%
by weight of oxygen.
2. The method according to claim 1 wherein the fuel is a distillate
fuel comprising a major amount of diesel fuel which is ashless.
3. The method according to claim 1 wherein the alcohol has on an
average from 6-20 carbon atoms.
4. The method according to claim 1 wherein the alcohol has on an
average from 8-20 carbon atoms.
5. The method according to claim 1 wherein the ketone is an
aliphatic ketone.
6. The method according to claim 1 or 5 wherein the ketone has on
average from 5 to 21 carbon atoms.
7. The method according to claim 1 or 5 wherein the ketone has an
average from 7 to 15 carbon atoms.
8. The method according to claim 1 wherein the alcohol is selected
from hexanol, methyl hexanol, 2-ethyl hexanol, octanol, isooctanol,
nonanol, iso-nonanol, 2-propyl heptanol, 2,4-dimethyl heptanol,
decanol, isodecanol, undecanol, isoundecanol, dodecanol,
isododecanol, tridecanol, iso-tridecanol, tetradecanol,
iso-tetradecanol, myristyl alcohol, hexadecanol, octadecanol,
stearyl alcohol, isostearyl alcohol, eicosanol, di-isobutyl
carbinol, tetrahydrolinalool, and mixtures thereof.
9. The method according to claim 1 wherein the amount of oxygenate
used to provide the composition with at least 0.5% by weight of
oxygen is in the range from 7 to 60% by weight based on the total
fuel composition.
10. The method according to claim 1 wherein the amount of oxygenate
used is such that it is capable of providing the composition with
at least 2% by weight of oxygen.
11. The method according to claim 1 wherein the diesel composition
comprises at least 80% by weight of the base fuel.
12. A method for reducing CO emissions without any substantial
increase in NO.sub.X from a vehicle powered under high load
conditions by a diesel fuel composition comprising a major amount
of the diesel fuel having a base fuel which contain no more than
10% by weight of olefins as base stock and no more than 10% by
weight of an ester, said method comprising blending with the
composition at least 5% by weight based on the total composition of
at least one oxygenate selected from the group consisting of
saturated, aliphatic monohydric primary, secondary, tertiary
alcohol and mixtures thereof having on an average from 4 to 20
carbon atoms, one or more mono- or poly-ketones or keta-monohydric
aliphatic alcohol having on an average 5 to 25 carbons, and
mixtures of the aforesaid alcohol(s) and ketone(s), said oxygenate
containing no other oxygen in its structure, the amount of the
oxygenate in the composition being sufficient to provide the fuel
composition with at least 0.5% by weight of oxygen.
Description
[0001] This invention relates to a method of reducing particulate
emissions from the exhausts of internal combustion engines powered
by diesel 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 hydrode- sulphurization thereby reducing the sulphur
levels in the fuel itself and hence in the exhaust emissions.
However, the presence of particulate matter in such exhaust
emissions 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. Examples of such compounds
include some of the lower aliphatic esters such as, e.g., the ortho
esters of formic and acetic acid, ethers, glycols, polyoxyalkylene
glycols, ethers and esters of glycerol, and carbonic acid esters.
For instance, U.S. Pat. No. 5,308,365 describes the use of ether
derivatives of glycerol which reduce particulate emissions when
added to diesel fuel. This patent teaches that the amount of
reduction in particulate matter is linearly proportional to the
oxygen content of the added components, i.e., the greater the
oxygen content the higher are the reductions in particulate matter
for a range of added compounds and that it is independent of the
specific compound chosen over the range described.
[0003] Similarly, Society of Automotive Engineering paper 932734
summarizes a heavy-duty diesel engine study over a broader range of
oxygenated fuels and one of the authors (Liotta, F J) is also one
of the inventors of U.S. Pat. No. 5,425,790 (alcohols and glycols)
and U.S. Pat. No. 5,308,365 (glycerol ethers and esters). 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.
[0004] Again, SAE Paper No. 942023 teaches the use of alcohols
generically disclosed as A and B. This paper however fails to
identify the alcohols tested.
[0005] Similarly, U.S. Pat. No. 5,425,790 (corresponding to SAE
932734) discloses the use of cyclohexyl ethanol and methyl benzyl
alcohol as additives for fuels to reduce particulate emissions and
states that these do not work (col. 6, lines 53-57). No other
alcohols are disclosed. This reference which is primarily concerned
with testing glycols and glycol ethers, does not state in what
concentration the alcohols were tested.
[0006] 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 C6-C20 alcohols as the oxygenated
additives.
[0007] 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).
[0008] 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.
[0009] Similarly, WO 96/23855 relates to the use of glycol ethers
and esters as lubricity enhancing additives to fuel oils such as
diesel. There is no mention of using any alcohols as such although
several alcohols have been listed as being used to prepare the
ethers and esters.
[0010] Like the WO 96/23855 above, U.S. Pat. No. 5,004,478 refers
to the use of polyethers and esters of aromatic carboxylic acids in
diesel fuels as additives. There is no mention of the use of any
alcohols as additives.
[0011] U.S. Pat. Nos. 5,324,335 and 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.
[0012] 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.
[0013] 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
[0014] 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.
[0015] 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.
[0016] It has now been found that certain specific oxygenates when
added to diesel fuels can enable the particulate emissions from the
exhausts of engines powered by these fuels to be substantially
reduced when compared with some of the additives used hitherto with
little to no NO.sub.x increase.
[0017] Accordingly, an embodiment of the invention is a method of
reducing particulate emissions from a vehicle powered by a diesel
fuel composition comprising a major amount of a diesel fuel and
having a base fuel which has no more than 10% by weight of olefins
and no more than 10% by weight of esters, said method comprising
blending with the composition greater than 5% by weight based on
the total composition of at least one oxygenate selected from the
group consisting of saturated, aliphatic monohydric primary,
secondary, tertiary alcohol and mixture thereof having on an
average from 4 to 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 alcohol(s)
and ketone(s), said oxygenate containing no other oxygen in its
structure, the oxygenate in the composition being sufficient to
provide the fuel composition with at least 0.5% by weight of
oxygen.
[0018] The diesel fuels that may be used in and benefit by the
method of the addition of the aforesaid oxygenates comprise inter
alia distillate fuels, and typically comprise a major amount of the
diesel fuel which is preferably an ashless fuel.
[0019] The diesel fuel compositions are not intended to include
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. The fuel compositions 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 has less than 10% by
weight of esters, i.e., the base fuels do not include the so called
biodiesels.
[0020] The diesel fuel suitably comprises .gtoreq.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.
[0021] A feature of an embodiment of the invention is the use of at
least 5% by weight of an oxygenate selected from the group
consisting of at least one saturated alcohol selected from the
group consisting of aliphatic monohydric primary, secondary,
tertiary alcohol and mixture thereof having on an average 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 alcohol(s) and ketone(s), which is
blended with the base fuel such that the final composition has an
oxygen content of at least 0.5% by weight in order to reduce
particulate emission when such a composition is used as a fuel in
an internal combustion engine. It has been found that these
alcohols, ketones and mixtures thereof when used in the amounts now
specified are better at reducing emission of particulates from
engine exhausts than the esters and ethers used hitherto. 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 of the present invention 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. A further feature of the
present invention is that the particulate reduction is achieved
with little to no increase in NO.sub.x emissions and also with a
substantial decrease in CO emissions at high engine loads.
[0022] The saturated, aliphatic monohydric alcohols used in the
method of an embodiment of the present invention are suitably
primary, secondary and tertiary alcohols or mixtures thereof which
may be straight chain alcohols, branched chain alcohols or mixtures
thereof and are preferably branched chain alcohols whether used
alone or as an admixture. The alcohols suitably have on an average
from 5-20 carbon atoms, preferably from 6-20 carbon atoms and more
preferably from 8-20 carbon atoms. Particularly preferred are
alcohols having on average from 9-15 carbon atoms. The alcohols
most preferred are open chain alcohols, such as, e.g., hexanol,
isohexanol, methyl hexanol, 2-ethyl hexanol, octanol, isooctanol,
nonanol, iso-nonanol, 2-propyl heptanol, 2,4-dimethyl heptanol,
decanol, isodecanol, undecanol, isoundecanol, dodecanol,
isododecanols, tridecanol, iso-tridecanol, tetradecanol,
iso-tetradecanol, myristyl alcohol, hexadecanol, octadecanol,
stearyl alcohol, isostearyl alcohol, eicosanol, dibutylcarbinol,
tetrahydrolinalool, 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, isotridecanol 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.
[0023] The term ketone includes mono- and poly-ketone and
keto-monohydric aliphatic alcohols which may contain straight chain
or branched chain aliphatic groups and mixtures thereof attached to
the central carbonyl (C.dbd.O) group, or aromatic 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, cyclopentanone,
cyclohexanone, methyl undecylketone, 8-pentadecanone,
2-heptadecanone, 9-eicosanone, 10 heneicosanone, and 2-doeicosanone
as well as their alkyl derivatives 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. Also included are hydrocarbons with multiple
ketone functions as well as mixed ketone and mono-hydric aliphatic
alcohol functions (e.g., keto-monohydric alcohols), such
keto-monohydric aliphatic alcohol materials having up to 25 carbons
in total.
[0024] The amount of any of the alcohol, ketone or mixture thereof
used in the method of the present invention is at least 5% by
weight of the total fuel 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 greater than 5%
by weight of the total composition, and is suitably greater than 7%
w/w and preferably from 7-60% by weight of the total composition.
Typically, the alcohols, ketones or mixtures thereof are used in an
amount in the range from 5 to 60% by weight, preferably from 7 to
40% by weight of the total fuel composition. Within these ranges,
it would be possible to use a relatively low amount of a specific
oxygenate or mixture of oxygenates, if said oxygenate or mixture of
oxygenates has a relatively high oxygen content and conversely, one
may have to use a higher amount of a particular oxygenate, or
mixture of oxygenates, if it is relatively low in oxygen
content.
[0025] The fuel compositions used in an embodiment of the invention
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. The
C.sub.4-C.sub.20 alcohols and/or ketones used suitably have an acid
value of no more than 0.1 mg KOH/g and a carbonyl number of no more
than 0.35 mg KOH/g.
[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, anfioxidants,
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] The fuel compositions may additionally contain cetane
improvers.
[0028] In the method of an embodiment of the present invention, the
alcohols used in the fuel compositions were evaluated for their
performance in reducing particulate emission using a single
cylinder Caterpillar 3406 HD engine (which is a Cat 1 Y450 engine)
with gaseous emission analyses for: hydrocarbons, NO.sub.x, carbon
monoxide, carbon dioxide, oxygen (Horiba, Mexa-9100 DEGR) and a
full flow 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 in the
method of embodiment of the invention are further illustrated with
reference to the following Examples and Comparative Tests:
EXAMPLE 1
[0030] The reference fuel used as base fuel in the tests conducted
below was that from Esso's Fawley refinery (hereafter referred to
as "LSADO") and had the following characteristics:
1 Density 851 kg/m.sup.3 KV.sub.20 (cSt) 5.03 Sulphur content 400
ppm T.sub.95 343.degree. C.
[0031] In the Tables below by references to "Tech. Polyol Ester
with branched acids" is meant an ester of technical pentaerythritol
derived by reacting pentaerythritol with an isomeric mixture of
branched C8 acids (isooctanoic acid sold as Cekanoic.RTM. 8 by
Exxon Chemical Company) and branched C9 acids
(3,5,5-trimethylhexanoic acid, sold as Cekanoic.RTM. 9 by Exxon
Chemical Company) in the ratio of 1:5 by weight respectively such
that the resultant ester had a hydroxyl number of 100-120 as
measured by infra-red technique. The branched ester of
Cekanoic.RTM. 8 acid has a molecular weight of 514 whereas that of
Cekanoic.RTM. 9 has a molecular weight of 556. Similarly,
references to "Tech. Polyol Ester with linear acids" is meant a
mixed ester of technical pentaerytiritol with a mixture or linear
C8-C10 monocarboxylic acids derived from natural oils such as,
e.g., coconut oil. Such a mixture of linear acids comprising 55%
w/w of C8 acids, 40% w/w C10 acids and the remainder being C6 and
C12 acids is available from Procter & Gamble. The linear ester
of C8 linear acid has a molecular weight of 514 whereas that of the
C10 linear acid has a molecular weight of 598.
[0032] The dimensions of the engine used for testing are shown in
Table 1 below:
2 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
[0033] In the Tables the following abbreviations have been
used:
3 LSADO Low sulphur automotive diesel oil (ex Esso's Fawley
refinery) as base fuel. Exxal .RTM. 10 Isodecanol (CAS No.
93821-11-5, EINECS No. 2986966, ex Exxon Chemicals) Exxal .RTM. 12
Isododecanol (CAS No. 90604-37-8, EINECS No. 2923309, ex Exxon
Chemicals) PM Particulate Matter
[0034] Emissions testing was carried out in a single cylinder
version of the Caterpillar 3406 heavy duty engine. A full dilution
tunnel with primary dilution ratios of about 10:1 at high load and
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.
[0035] Seven oxygenated fuels were made by blending seven
oxygenates into LSADO to make test fuels with 2 weight % oxygen
content. Their emissions performance was compared against the LSADO
base fuel which served as the reference fuel.
[0036] Two steady state conditions were chosen for testing, both at
1500 rpm. The high load condition was 220 Nm and the low load
condition was 60 Nm. Each fuel was tested over five or six
different days at each load in a randomized fuel test sequence for
each day. Particulates 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.
[0037] The resultant particulate emissions are listed in Table 2
below for each fuel averaged over the 5-6 days of testing as a %
change compared to the LSADO base fuel, the base diesel fuel
containing 400 ppm sulphur. At high load, the amount of PM
reduction was typically around 20%. The largest reduction in PM was
38% which was seen for the fuel containing the primary alcohol
(Fuel 5). At low load, the amount of PM reduction seen was smaller.
Again, the largest reduction in PM seen amongst any of the
oxygenates tested was for the fuel containing the primary alcohol
where a reduction of 16% was seen. These reductions in PM were
obtained without increasing NO.sub.x emissions and with large
reductions in CO emissions as seen from Table 2A below.
4TABLE 2 % Change in Particulate Matter between Test Fuel and
Reference LSADO % Change of Test Fuel Amount PM g/kW PM over LSADO
LSADO Oxygenate Used (%) High Load Low Load High Load Low Load Fuel
1 Trimethoxymethane 4.5 0.1420 0.3998 -20.6 -2.7 Fuel 2 2-Methoxy
ethyl ether 5.6 0.1332 0.3775 -25.5 -5.6 Fuel 3 Tech Polyol Ester
with 9.4 0.1495 0.3957 -16.4 -1.0 Branched Acids Fuel 4 Tech Polyol
Ester with Linear 10.0 0.1455 0.3912 -18.7 -2.2 Acids Fuel 5* Exxal
.RTM.-10 19.8 0.1110 0.3368 -38.0 -15.8 Fuel 6 Anisole 13.5 0.1354
0.3461 -24.3 -13.4 Fuel 7 Methyl tert.-butyl ether 11.0 0.1439
0.3784 -19.6 -5.4 *an embodiment of the invention
[0038]
5TABLE 2A % Change in CO and NO.sub.x between Test Fuel and
Reference LSADO High Load Low Load Test Fuel + Oxygenate CO
NO.sub.x CO NO.sub.x Fuel 1 -9.7 1.5 0.23 0.56 Fuel 2 -12.7 2.5
0.16 1.28 Fuel 3 -16.5 2.6 0.11 0.05 Fuel 4 -10.5 2.3 -2.39 1.83
Fuel 5* -22.7 1.2 -1.13 -2.25 Fuel 6 -11.0 6.2 -1.58 4.80 Fuel 7
-7.7 -1.0 2.65 -2.73 *an embodiment of the invention
EXAMPLE 2
[0039] Emissions testing was also carried out in 3 passenger cars
that spanned a range of vehicle technologies. The Ford Escort (1.8
liter IDI) represented the older vehicle technology and had no
after-treatment. This vehicle was a typical vehicle sold from
1990-1991. The intermediate technology was the VW Jetta (1.6 liter
IDI) that had turbo-charging and an oxidation catalyst and
represented a state of the art vehicle in 1990-1991. The VW Golf
(1.9 liter TDI) represented the newest vehicle technology and was
turbo-charged, intercooled, had a closely mounted oxidation
catalyst and used exhaust gas recirculation. It was a state of the
art vehicle in 1996-1997.
[0040] Six oxygenated fuels were made by blending six oxygenates
into LSADO to make test fuels with 2 weight % oxygen content as was
described previously and whose compositions are given in Table 2
(Fuels 1, 3 to 7). The emissions performance of these oxygenated
fuels was compared against LSADO which served as the reference fuel
and this performance is shown in Table 3. The improvement in the
particulate matter emissions over the reference fuel can be
compared between these six fuels. In particular, the improvement
using the primary monohydric alcohol compound in Fuel 5 can be
compared with Fuels 1, 3, 4, 6, and 7 which contained various other
oxygenated compounds.
[0041] Testing was done running the European hot ECE 15-EUDC test
cycle. Each fuel was tested three times over the complete test
cycle with a base fuel test completed before and after the three
runs on the test fuel. Results for each test fuel are then
expressed as a relative change from the base fuel data taken on the
same day.
[0042] The resultant particulate emissions are listed below for
each fuel for each of the three vehicles as a % change compared to
LSADO, the base diesel fuel with 400 ppm sulphur. Note that for
many of the fuels tested, the amount of particulate reduction
varied widely between the three vehicles tested. Surprisingly, the
results for the fuels with primary alcohol (Fuel 5) were extremely
consistent showing a PM reduction of 18-20% over the ECE-EUDC test
cycle. Again, no significant increase in NO.sub.x occurred for the
fuel with the primary alcohol.
6TABLE 3 % Change in Particulate Matter Between the Test Fuel and
LSADO Reference Fuel Test Fuel + Oxygenate Escort Jetta Golf Fuel 1
-9.8 -6.5 +4.5 Fuel 3 -0.1 -2.7 -9.1 Fuel 4 -3.8 -9.3 -2.0 Fuel 5*
-18.9 -18.2 -19.6 Fuel 6 -19.0 +10.8 -13.4 Fuel 7 -18.4 -10.2 -11.6
*an embodiment of the invention
[0043]
7 TABLE 3A NO.sub.x DATA Test Fuel + Oxygenate Escort Jetta Golf
Fuel 1 -0.1 3.2 -1.6 Fuel 3 6.5 -2.2 -1.9 Fuel 4 5.3 4.2 -2.3 Fuel
5* 1.2 2.5 0.9 Fuel 6 -0.4 -5.2 10.3 Fuel 7 -10.1 -3.1 1.9 *an
embodiment of the invention
EXAMPLE 3
[0044] 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 ratio 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.
[0045] Three alcohols were tested in LSADO blended to make test
fuels with 2 weight % oxygen content. Their emissions performance
was compared against the LSADO with 400 ppm sulphur which served as
the reference fuel.
[0046] One steady state condition was chosen for testing at 1500
rpm and 60 Nm. Each fuel was tested over six different days in a
randomized fuel test sequence for each day. Particulates 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.
[0047] The resultant particulate emissions are listed in Table 4
below for each fuel averaged over the six days of testing as a %
change compared to LSADO, the base diesel fuel with 400 ppm
sulphur. All three of these alcohols led to a particulate matter
decrease of 17-19% compared to LSADO with no increase in
NO.sub.x.
8 TABLE 4 % Change in Test Fuel PM NO.sub.x Exxal .RTM. -10 in
Fawley LSADO -17.1 -2.3 Iso-Nonanol in Fawley LSADO -18.8 -2.0
Exxal-12 in Fawley LSADO -18.0 -2.6
EXAMPLE 4
[0048] The base fuel used was a Fawley ULSADO, which had a density
of 825 kg/m.sup.3, a kV.sub.20 of 3.41 cSt, a sulfur content of 31
ppm and a T.sub.95 of 314.degree. C., 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.
9TABLE 5 Blend % wt Ref. Fuel Description oxygenate 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
[0049] 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.
[0050] 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 (base1, test1, test2, test3, base2). Each of these
five tests comprised a hot ECE+EUDC drive cycle. Gaseous and
particulate emissions were collected for each test.
[0051] Results and Discussion
[0052] Shown in FIG. 1A and 1B and Table 6 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 ULSADO.
[0053] 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.
10 TABLE 6 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
[0054] 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.
* * * * *