U.S. patent application number 09/732373 was filed with the patent office on 2002-01-03 for diesel fuel composition.
Invention is credited to Caers, Raf F., Miller, Richard C., Schlosberg, Richard Henry, Yeh, Lisa I-Ching.
Application Number | 20020000063 09/732373 |
Document ID | / |
Family ID | 26868595 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000063 |
Kind Code |
A1 |
Yeh, Lisa I-Ching ; et
al. |
January 3, 2002 |
Diesel fuel composition
Abstract
This invention is a fuel composition for use in internal
combustion engines comprising a major amount of a base fuel which
contains no more than 10% by weight of olefins and no more than 10%
by weight of esters, and greater than 5% by weight based on the
total composition of an oxygenate selected from the group
consisting of a saturated, aliphatic monohydric alcohol having on
an average from 8 to 20 carbon atoms, one or more ketones having on
an average 5 to 25 carbons, and mixtures of the 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 reduces 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: |
26868595 |
Appl. No.: |
09/732373 |
Filed: |
December 7, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60172915 |
Dec 21, 1999 |
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Current U.S.
Class: |
44/437 ; 44/438;
44/439; 44/443; 44/451 |
Current CPC
Class: |
C10L 1/026 20130101;
C10L 10/02 20130101 |
Class at
Publication: |
44/437 ; 44/438;
44/439; 44/443; 44/451 |
International
Class: |
C10L 001/18 |
Claims
What is claimed is:
1. A fuel composition comprising a major amount of a base fuel
having no more than 10% by weight of olefins and no more than 10%
by weight of esters, and 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
and tertiary alcohol and mixtures thereof having on an average from
8 to 20 carbon atoms, at least one mono- or poly-ketone or
keto-monohydric aliphatic alcohol having on an average at 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 composition according to claim 1 wherein the fuel is an
ashless diesel fuel.
3. The composition according to claim 1 wherein the saturated,
aliphatic monohydric alcohol has on an average from 9-20 carbon
atoms.
4. The composition according to claim 1 wherein the alcohol is
selected from octanol, iso-octanol, 2-ethyl hexanol, 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.
5. The composition according to claim 1 wherein the ketone has on
an average 5 to 21 carbons.
6. The composition according to claim 1 wherein the ketone has on
an average 7 to 15 carbons.
7. A composition according to claim 1 wherein the amount of
oxygenate present to provide the composition with at least 0.5% w/w
of oxygen is greater than 7% by weight of the total
composition.
8. The composition according to claim 1 wherein the amount of
oxygenate present is such that it is capable of providing the
composition with at least 2% by weight of oxygen.
9. The composition according to claim 1 wherein the amount of any
C1 to C2 alcohol in said composition is less than 5% by weight.
10. The composition according to claim 1 comprising at least 80% by
weight of the base fuel.
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 hydrode-sulphurisation 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 (column 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 C.sub.6-C.sub.20 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. 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.
[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 present invention is a
fuel composition comprising a major amount of a base fuel having no
more than 10% by weight of olefins, no more than 10% by weight of
an ester, and greater than 5% by weight based on the total fuel
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 8 to 20
carbon atoms, at least one 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), 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.
[0018] The fuels that may be used in and benefit from the addition
of the aforesaid oxygenate 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 olefin content of the fuel compositions 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 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 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 at least 70% by weight of
the base fuel, 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] The amount of any of the oxygenate referred to above and
used in the compositions of embodiment of the present invention is
greater than 5% 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 5% by weight of the total composition, and is
preferably greater than 7% w/w 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.
[0022] The feature of an embodiment of the invention is the use of
greater than 5% by weight of at least one oxygenate selected from
the group consisting of saturated, aliphafic monohydric, primary,
secondary, tertiary alcohol and mixture thereof having 8-20 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) 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 oxygenate 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 is that these oxygenate 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 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.
[0023] The saturated, aliphatic, monohydric alcohols in the
compositions of embodiments of the present invention are suitably
used alone or as an admixture. The alcohols suitably have on an
average from 8-20 carbon atoms, preferably 9-20 carbon atoms, more
preferably, 9-16 carbon atoms. The alcohols are primary, secondary,
tertiary monohydric alcohols and mixtures thereof. Particularly
preferred are branched, open chain alcohols. Specific examples of
such alcohols include inter alia octanol, iso-octanol, 2-ethyl
hexanol, nonanol, iso-nonanol, 2-propyl heptanol, 2,4-dimethyl
heptanol, decanol, isodecanol, undecanol, isoundecanol, dodecanol,
iso-dodecanol, tridecanol, iso-tridecanol, tetradecanol,
iso-tetradecanol, myristyl alcohol, hexadecanol, octadecanol,
stearyl alcohol, isostearyl alcohol, eicosanol, di-isobutyl
carbinol, 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.
[0024] The term ketone includes mono- or poly-ketone or
keto-monohydric aliphatic alcohol which may contain straight chain
or branched chain aliphatic groups and mixtures thereof attached to
the central carbonyl (C=O) group, or aromatic or naphthenic groups,
or mixtures of aliphatic, aromatic and naphthenic 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 to 21 carbons, still more preferably on an average
of 7 to 15 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
derivates 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 and with mixed
ketone and monohydric functions (i.e., keto-monohydric aliphatic
alcohol), with such keto-monohydric alcohols containing up to 25
carbons in total.
[0025] 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. The oxygenates 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, 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] The fuel compositions used in the method of the present
invention may additionally contain cetane improvers.
[0028] Some of the oxygenates which can be used in the fuel
compositions of embodiment of the present invention 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 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 are
further illustrated with reference to the following Examples and
Comparative Tests:
EXAMPLE 1
[0030] The 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:
[0031] Density--851 kg/m.sup.3
[0032] KV20 (cSt)--5.03
[0033] Sulphur content--400 ppm
[0034] The dimensions of the engine used for testing are shown in
Table 1 below:
1 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
[0035] In the Tables below by references to "Tech. Polyol Ester
(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 (linear acids)" is meant a mixed
ester of technical pentaerythritol with a mixture or linear
C.sub.8-C.sub.10 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.
[0036] In the Tables the following abbreviations have been
used:
[0037] LSADO--Low sulphur automotive diesel oil (ex Esso's Fawley
refinery) as base fuel
[0038] Exxal.RTM. 10--Isodecanol (CAS No. 93821-11-5, EINECS No.
2986966, ex Exxon Chemicals)
[0039] Exxal.RTM. 12--Isododecanol (CAS No. 90604-37-8, EINECS No.
2923309, ex Exxon Chemicals)
[0040] PM--Particulate Matter
[0041] 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 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.
[0042] 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 LSADO
which served as the reference fuel.
[0043] 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.
[0044] The resultant particulate results are listed in the table
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 with
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. 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 about
16% was seen (Table 2). These reductions in PM were obtained
without increasing NO.sub.X emissions and with a large reduction in
CO emissions as seen from Table 2A below.
2TABLE 2 % Change in Particulate Matter between Test Fuel and
Reference LSADO % Change of Test Fuel Amount PM g/kWh 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 Branched Acids 9.4 0.1495 0.3957 -16.4 -1.0 Fuel 4 Tech Polyol
Ester with Linear Acids 10.0 0.1455 0.3912 -18.7 -2.2 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 *Embodiment of the invention.
[0045]
3TABLE 2A % Change in CO and NO.sub.x between Test Fuel and
Reference LSADO Base Fuel 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 *Embodiment of the invention
EXAMPLE 2
[0046] 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.
[0047] Six samples of 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 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 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.
[0048] 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.
[0049] The resultant particulate results 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 fuel with primary C.sub.10 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.
4TABLE 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
*Embodiment of the invention
[0050]
5 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
*Embodiment of the invention
EXAMPLE 3
[0051] 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.
[0052] Three alcohols were tested in LSADO blended to make test
fuels with 2 weight % oxygen content. Their emissions performance
was compared against the LSADO which served as the reference
fuel.
[0053] 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.
[0054] The resultant particulate results 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 ADO with little to no increase in
NO.sub.X.
6 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
[0055] The base fuel used was a Fawley ULSADO, which had a density
of 825 kg/m.sup.3 a kV.sub.20 (cSt) of 3.41, 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.
7TABLE 5 Blend % wt Ref. Fuel Description oxygenate ULSADO Base
Fuel 0 TO Base + Isodecanol Primary: Exxal .RTM. 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
[0056] 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.
[0057] 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.
RESULTS AND DISCUSSION
[0058] Shown in FIGS. 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.
[0059] FIG. 2 and Table 6 shows the relative change in emissions of
each oxygenated blend compared with the base fuel. The differences
observed from FIGS. 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.
8TABLE 6 CO CO.sub.2 HC NO.sub.x 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 [%] 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
[0060] 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.
* * * * *