Note: Descriptions are shown in the official language in which they were submitted.
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ULTRA-LOW SULFUR FUEL COMPOSITIONS CONTATNING
ORGANOMETALLIC.ADDITIVES
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates, generally, to ultra-low sulfur fuel
compositions
containing organometalIic additives and a method of protecting emissions
systems.
Emissions systems as used herein broadly includes catalysts and associated
equipment
which is generally located in,the effluent stream of a combustion system, e.g.
in the
exhaust or the like. The invention contemplates the addition of various
compounds to an
ultra low sulfur fuel to protect the emissions systems from poisoning by
exhaust
byproducts, and a method of protecting emissions systems from poisoning from
impurities found in the fuel and lubricant sources and increasing the catalyst
durability in
these systems.
More specifically, the present invention relates to ultra-low sulfur fuel
compositions containing an organometallic compound which acts as a scavenger
to
prevent poisoning deposits such as sulfur, phosphorus or lead on catalytic
emissions
systems used for reducing tailpipe emissions, thereby contributing to lowered
emissions
characteristics and improved emissions system efficiency, thereby contributing
to
lowered emissions characteristics and improved emissions system efficiency and
improved emission hardware (e.g., catalyst) durability.
Description of the Prior Art
If is well known in the automobile industry to reduce tailpipe emissions by
using
various strategies. The most common method fox xeducing emissions from spark
ignition
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engines is by careful control of the air-fuel ratio and ignition timing. For
example,
retarding ignition timing from the best efficiency setting reduces HC and NOx
emissions,
while excessive retard of ignition increases the output of CO and HC.
Increasing engine
speed reduces HC emissions, but NOx emissions increase with load.. Increasing
coolant
temperature tends to reduce HC emissions, but this results in an increase in
NOX
emissions.
It is also known that treating the effluent stream from a combustion process
by
exhaust after treatment can lower emissions. The effluent contains a wide
variety of
chemical species and compounds, some of which may be converted by a catalyst
into
other compounds or species. For example, it is known to provide exhaust after
treatment
including a three-way catalyst and a lean NOX trap. Other catalytic and non-
catalytic
methods are also known.
Thermal reactors are noncatalytic devices which rely on homogeneous bulk gas
reactions to oxidize CO and HC. However, in thermal reactors, NOX is largely
unaffected. Reactions are enhanced by increasing exhaust temperature (e.g. by
a reduced
compression ratio or retarded timing) or by increasing exhaust combustibles
(rich
mixtures). Typically, temperatures of 1500 °F (800 °C) or more
are required for peak
efficiency. Usually, the engine is run rich to give 1 percent CO and air is
injected into the
exhaust. Thermal reactors are seldom used, as the required setting
dramatically reduces
fuel efficiency.
Catalytic systems are capable of reducing NOX as well as oxidizing CO and HC.
However, a reducing environment for NOX treatment is required which
necessitates a
richer than chemically correct engine air-fuel ratio. A two-bed converter may
be used in
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which air is injected into the second stage to oxidize CO and HC. While
efficient, this
procedure results in lower fuel economy.
Single stage, three way catalysts (TWC's) are widely used, but they require
extremely precise fuel control to be effective. Only in the close proximity of
the
stoichiometric ratio is the efficiency high for all three pollutants,
excursions to either side
of stoichiornetric can cause increase in hydrocarbon and carbon monoxide or
NOx
emissions. Such TWC systems can employ, fox example, either a zirconia or
titanium
oxide exhaust oxygen sensor or other type of exhaust sensor and a feedback
electronic
controls system to maintain the required air-fuel ratio near stoichiometric.
Catalyst support beds may be pellet or honeycomb (e.g. monolithic). Suitable
reducing materials include ruthenium and rhodium, while oxidizing materials
include
cerium, platinum and palladium.
Diesel systems raise a different set of challenges for emissions control.
Strategies
for reducing particulate and HC include optimizing fuel injection and air
motion,
effective fuel atomization at varying loads, control of timing of fuel
injection,
minimization of parasitic losses in combustion chambers, low sac volume or
valve cover
orifice nozzles for direct injection, reducing lubrication oil contributions,
and rapid
engine warm-up.
In terms of after treatment, it is known that diesel engines generally burn
lean and
the exhaust will therefore usually contain excess oxygen. Thus, NOX reduction
with
conventional three-way catalysts is not feasible. NOX is removed from diesel
exhaust by
either selective catalytic reduction, the use of lean NOX catalysts such as
those comprised
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of zeolitxc catalysts or using metals such as iridium, or catalyzed thermal
decomposition
of NO into OZ and NZ.
Diesel particulate traps have been developed which employ ceramic or metal
filters. Thermal and catalytic regeneration can bum out the material stored.
Particulate
standards of 0.2 g/mile may necessitate such traps. Both fuel sulfur and
aromatic content
contribute to particulate emissions. Catalysts have been developed for diesels
which are
very effective in oxidizing the organic portion of the particulate.
Improved fuel economy can be obtained by using a lean-burn gasoline engine,
for
example, a direct injection gasoline engine, however currently NOx cannot be
reduced
effectively from oxidizing exhaust using a typical three-way catalyst because
the high
levels of oxygen suppress the necessary reducing reactions. Without a NOx
adsorber or
lean NOX trap (LNT), the superior fuel economy of the lean-burn gasoline
engine cannot
be exploited. The function of the LNT is to scavenge the NOX from the exhaust,
retaining
it for reduction at some later time. Periodically, the LNT must be regenerated
by reducing
the NOX. This can be accomplished by operating the engine under rich air-fuel
ratios for
the purpose of purging the trap. This change in operating conditions can
adversely effect
fuel economy as well as driveability. These LNT's may also be placed on diesel
engines,
which also operate in a lean air-fuel mode. As in the lean-burn gasoline
engines, the
exhaust of both types of engines is net oxidizing and therefore is not
conducive to the
reducing reactions necessary to remove NOx. It is an object of the present
invention to
improve the storage efficiency and durability of the LNT and to prolong the
useful life of
the LNT before regeneration is necessary.
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It is well known that NOX adsorbers are highly vulnerable to deactivation by
sulfur (see, for example, M. Guyon et al., Impact of Sulfur on NOx Trap
Catalyst II ctivity-
Study of the Regeneration Cofzditions, SAE Paper No. 982607(1998); and P.
Eastwood,
Critical Topics ire Exhaust Gas Aftertreatrnent, Research Studies Press Ltd.
(2000)
pp.215-218.) and other products resulting from fuel combustion and normal
lubxicant
consumption. The US Environmental Protection Agency (EPA) has set forth
proposed
rules for limiting the sulfur content of highway diesel fuels to a level of 15
parts per
million (see 6S FR 35429, June 2, 2000, the complete text of which is
incorporated herein
by reference). The EPA states "This proposed sulfur standard is based on our
assessment
of how sulfur-intolerant advanced exhaust emission control technologies will
be." It is an
object of the present invention to provide fuel or lubricant compositions
capable of
reducing the adverse impact of sulfur, and other exhaust~byproducts, on
catalytic
emissions control technologies including NOx adsorbers and LNTs. Further, the
present
invention provides refiners with flexibility in complying with the objective
of said
proposed rule by allowing refiners to reduce sulfur to a certain level above
the 15 ppm
level of the rule and still obtain the benef is of improved exhaust emissions
control
technology performance obtained by using fuels containing lower levels of
sulfur.
Performance fuels for varied applications and engine requirements are known
for
controlling combustion chamber and intake valve deposits, cleaning port fuel
injectors
and carburetors, protecting against wear and oxidation, improving lubricity
and emissions
performance, and ensuring storage stability and cold weather flow. Fuel
detergents,
dispersants, corrosion inhibitors, stabilizers, oxidation preventers, and
performance
additives are known to increase desirable properties of fuels.
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Organometallic manganese compounds, for example methylcyclopentadienyl
manganese tricarbonyl (MMT), available from Ethyl Corporation of Richmond,
Virginia,
is known for use in gasoline as an antiknock agent (see, e.g. US Patent
2;818,417). These
manganese compounds have been used to lower deposit formation in fuel
induction
systems (US Patents 5,551,957 and 5,679,116), sparkplugs (US Patent 4,674,447)
and in
exhaust systems (US Patents 4,175,927, 4,266,946, 4,317,657, and 4,390345.
Organometallic iron compounds, such as ferrocene, are known as well for octane
enhancement (US Patent 4,I39,349).
I O SUMMARY OF THE INVENTION
The present invention contemplates supplying, in a spark- or compression
ignition
lean, stoichiometric, or rich system, a Iow sulfur fuel containing a
sufficient amount of an
organometallic compound, e.g. MMT or the like, to effectively reduce the
impact of
poisoning substances on emissions systems for fuel-combustion systems.
The combustion of a fuel containing an organometallic manganese compound,
such as MMT, results in mixtures of manganese compounds containing, among
others,
species of manganese oxides, manganese phosphates and manganese sulfates. As
used
hereinafter, a stoichiometric ratio will be referred to using lambda, which is
calculated
using the following formula:
lambda = air /fuel ratio
stoichiometric air/fuel ratio.
When lambda = l, the system is stoichiometric. When lambda > I, or more
preferably > 1.02, the system is a lean system. When lambda < I, the system is
a rich
system.
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In a gasoline or diesel engine that is operating with excess air according to
the
present invention, under lean conditions and using a fuel containing an
organometallic
compound according to the present invention, the metal will combine with
combustion
byproducts, e.g. sulfur, to form, e.g., metal sulfates in the exhaust. These
compounds are
not stable at the high, temperatures found in the exhaust manifold or those
associated
around typical three way catalysts. However, at lower temperatures under which
lean
NOX catalysts, diesel particulate traps, continuously regenerating traps, lean
NOx traps or
diesel oxidation catalysts operate, the metal can scavenge the sulfur and form
stable metal
sulfate compounds. This scavenging process then ties up the sulfur and
protects the
catalyst from sulfur deposition. Suitable exhaust temperatures are below 650
°C,
preferably below 600 °C and more preferably below about 500 °C.
For example, from
about 200 to about 650 °C.
Suprisingly, when a compound according to the present invention is used in a
fuel
containing low amounts of sulfur, the conversion efficiency of emissions
systems is
maintained at a much higher rate than when the base fuel is used alone.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graphical representation comparing the sulfur content on a
diesel oxidation
catalyst aged 80,000 km on base diesel fuel (Base) or additized diesel fuel
containing
organometallic compounds (Metal).
Figure 2 is a graphical representation comparing NOX conversion loss of a lean
NOx trap
with a spark-ignition base fuel and the base fuel plus an organometallic
compound
according to the present invention, wherein the base fuel contains 30 ppm
sulfur.
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Figure 3 is a graphical representation comparing NOX conversion of a lean NOx
trap after
operating 46 hours on a base fuel and a fuel composition according to the
present
invention.
Figure 4 is a gxaphical representation comparing NOX conversion loss of a
catalysts with
a spark-ignition base fuel and the base fuel plus an organometallic compound
according
to the present invention, wherein the base fuel contains 30 ppm sulfur.
DETAILED DESCRIPTION
Catalytic based emissions systems are well known. As exhaust emissions control
systems become more advanced and emissions restrictions become tighter, the
susceptibility of emissions control systems to poisoning increases.
Exhaust emission control systems have a tendency to lose their effectiveness
over
time. The present invention contemplates providing an organometallic compound
to a
low sulfur fuel composition. Suitable organometallic compounds include those
1 S containing at least one alkali, alkaline earth or transition metal in
conjunction with an
appropriate ligand.
The fuel compositions of the present invention can further enhance the
emissions
control system protection of the low sulfur fuel. Also, the present invention
allows for
use of fuels having a higher sulfur content to function in a similar manner to
a fuel having
a lower sulfur content with respect to protecting the exhaust emission control
technologies.
Preferred metals include sodium, potassium, calcium, barium, strontium,
rhodium,
cerium, palladium, platinum, iron, manganese and mixtures thereof. The
addition of a
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variety of organometallic compounds to fuel compositions is known.
Representative
organometallic compounds for use in the present invention include those
compounds
taught in US Patents 4,036,605; 4,104,036; 4,474580; 4,568,357; 4,588,416;
4,674,447;
4,891,050; 4,908,045; 4,946,609; 4,955,331; 5,113, 803; S,S99,3S7; 5,919,276;
S 5,944,858; 6,0S1,040 and 6,056,792; and European Patent EP 466 S12 Bl.
Especially preferred organometallic compounds are those containing at least
one
of the metals selected from the group consisting of manganese, iron,
strontium, cerium,
barium, platinum and palladium. Preferred manganese containing organometallic
compound are manganese tricarbonyl compounds delivered in the fuel or through
the
lubricating composition. Such compounds are taught, for example, in US Patent
Nos.
4,568,357; 4,674,447; 5,113,803; S,S99,3S7; 5,944,858 and European Patent No.
466 512
Bl. Other methods of delivery, including direct injection inta the combustion
chamber or
exhaust, are also suitable for practice of the instant invention.
Suitable manganese tricarbonyl compounds which can be used in the practice of
1 S this invention include cyclopentadienyl manganese tricarbonyl,
methylcyclopentadienyl
manganese tricarbonyl, dimethylcyclopentadienyl manganese tricarbonyl,
trirnethylcyclopentadienyl manganese tricarbonyl, tetramethylcyclopentadienyl
manganese tricarbonyl, pentamethylcyclopentadienyl manganese tricarbonyl,
ethylcyclopentadienyl manganese tricarbonyl, diethylcyclopentadienyl manganese
tricarbonyl, propylcyclopentadienyl manganese tricarbonyl,
isopropylcyclopentadienyl
manganese tricarbonyl, tent-butylcyclopentadienyl manganese tricarbonyl,
octylcycIopentadienyl manganese tricarbonyl, dodecyIcyclopentadienyl manganese
tricarbonyl, ethylmethylcyclopentadienyl manganese tricarbonyl, indenyl
manganese
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tricarbonyl, and the like, including mixtures of two or more such compounds.
Preferred
are the manganese tricarbonyl compounds which axe liquid at room temperature
such as
methylcyclopentadienylmanganesetricarbonyl, ethylcyclopentadienyl manganese
tricarbonyl, liquid mixtures of cyclopentadienyl manganese tricarbonyl and
methylcyclopentadienyl manganese tricarbonyl, mixtures of
methylcyclopentadienyl
manganese tricarbonyl and ethylcyclopentadienyl manganese tricarb'onyl, etc.
Preparation of such compounds is described in the literature, for example,
U.S.
Pat. No. 2,818,417, the disclosure of which is incorporated herein in its
entirety.
When formulating fuel compositions of this invention, the organometallic
compounds (e.g., cyclopentadienyl manganese tricarbonyl compounds) are
employed in
amounts sufficient to reduce the impact of poisons, e.g., sulfur, lead and
phosphorus, on
the emissions systems of a low sulfur fuel fired engine. Thus the fuels will
contain minor
amounts of the organometallic compounds sufficient to control the impact of
such
deposits on catalytic exhaust emission control technologies. Generally
speaking, the
fuels of the invention will contain an amount of the organometallic compound
sufficient
to provide from about 0.5 to about 120 mg of metal per liter of fi.~el, and
preferably from
about I to about 66 mg of manganese per liter and more preferably from about 2
to about
33 rng of metal per liter of fuel. When added to the lubrication systems of
automobiles as
a means of delivering the metal to the fuel combustion system, the
organometallic
concentration will be increased to provide the above amounts of the metal in
the
combustion chamber.
While not wishing to be bound by the following theory, it is postulated that
the
sulfur in the fuel reacts with the metal; for example the manganese in MMT, to
form
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metal sulfate (M~04) which are stable in the temperature range of 200-650
°C.
Surprisingly, metal sulfates such as MnS04 do not bind to active sites on the
catalyst
whereas free sulfur does, in the form of a sulfate.
When the emissions system contains a component (e.g. a barium-containing lean
NOx trap) which is poisonable by combustion products, applicants novel
compositions
and methods provide a substance which competes with the active site (e.g.
barium) in the
low-sulfur fueled engine-out exhaust. So long as the metal of the scavenging
agent will
compete with the metal of the catalyst system for complexing with the sulfur,
the metals
may be suitable for use as scavenging agents in the practice of the present
invention. The
l 0 ability of the metal scavenging agent to compete with the metals of the
catalyst for
complexing with the catalyst poisons can be determined by monitoring catalyst
durability. Further, the organometallic scavengers of the present invention
can reduce the
detrimental impact of other poisons, such as phosphorus and lead, on emissions
control
technologies of the combustion systems of the present invention.
It is especially preferred that the sulfizr content of the fuel be less than
100 ppm,
and the treatment rate of the organometallic compound be up to 120 mg/l, more
preferably up to 66 mgll, and most preferably up to 33 mg/I, based upon the
amount of
metal delivered to the fuel composition. Higher rates are possible, but
excessive
treatment of the fuel stock may be detrimental to proper functioning of the
combustion
system componentry.
In a combustion engine, normal operation results in the combustion of the
lubricant and additives such as those containing phosphorus or zinc added to
the
lubricant. In addition to the sulfur present in the fuel, the compositions of
the present
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invention interact with the combustion products of these additives and reduce
their
adverse impact on exhaust aftertreatment devices. By preventing deposition,
the novel
compositions prevent the compounds, such as phosphorus, from covering catalyst
or
storage sites in the aftertreatment systems and reducing the aftertxeatment
system's
effectiveness. With the compositions of the present invention, the
aftertreatment
system's effectiveness in maintained over extended periods of operation.
Examples
Example 1
Two vehicles equipped with diesel engines and oxidation catalysts were tested
over X0,000 km. One vehicle used diesel fuel. The other used diesel fuel
containing
organometallic additives in an amount sufficient to provide 17 ppm calcium and
3 ppm
manganese to the fuel. At the end of mileage accumulation the two catalysts
were
removed from the vehicle and the elemental content of these catalysts was
evaluated. As
seen in Figure l, the catalysts from the vehicle operated on a fuel containing
organometallic scavengers contained lower amounts of sulfur. This demonstrates
that use
of organometallic compounds scavenges sulfur and prevents it deposition on the
catalyst.
Example 2.
These same diesel catalysts were examined for other catalyst poisons as shown
in
Table 1 below. The catalyst from the engine operated according to the present
invention
was found to contain lower amounts of phosphorus and lead compared to the
catalysts
from the vehicle using base fuel. This scavenging of P and Pb has not been
observed in
engines that run significantly greater air than stoichiometric or in diesel
engine
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applications. The presence of P and Pb on a catalyst would reduce catalyst
activity;
therefore, the scavenging of these compounds by the additive should provide
greater
catalyst durability.
TABLE I - CATALYST
POISON CONTENT
(ppm)
Base Fuel CatalystsPb P S MMT Fuel CatalystsPb P S
Front in 22 4756 2344 Front in 19.6 1565 812
mid 24 4375 2518 mid I2.8 1294 33I
out 20.9 4303 1812 out 16.6 1046 1586
Rear in 26 4246 2683 Rear in 16.1 1379 I 623
mid 25 2094 2543 mid 17.8 944 IIII
out 23.8 1361 3098 out 17.8 794 965
Average 23.623522.5 Average 16.781170.31071.33
2499.7
1 S As may be seen from the above examples, the addition of the organometallic
compound acts to reduce the deposits of P, Pb and S upon the catalyst
structure, thereby
enhancing life and maintaining efficiency of the emissions system and reducing
overall
emissions.
Such a reduction of deposits on catalysts is unexpected, as heretofore, such
~0 catalysts have been suitable only for so-called stoichiometrically balanced
systems, and it
is unexpected that an unbalanced system, e.g. a lean fuel combustion system,
would
work. It has been understood that fox such three-way catalysts to work, they
must be
exactly matched to the stoichiometry of the combustion system or the
production of
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emissions would be above that which is achievable with the practice of the
instant
invention.
Further, the method according to the instant invention is especially useful in
low
sulfur fuels, e.g., those with less than 100 ppm, preferably 50 ppm or less,
more
preferably 30 ppm or less, most preferably 20 ppm or less, for example 15 ppm
or less,
sulfur as it enhances the sulfur emissions reduction without the need to
resort to more
expensive desulfurization procedures.
An especially preferred sulfur range in the fuel according to the present
invention
is from about 20 to about 50 ppm sulfur. The deleterious effects of other
catalyst poisons,
including those such as phosphorus and lead are also suitable for reduction
according to
the present invention by providing competing scavengers according to the
present
invention. Thus the advantages of the present invention can still be
recognized with fuels
containing ultra-low levels of sulfur, for example 15 ppm or less, 5 ppm or
less as well as
sulfur-free fuels.
The base fuels used in formulating the compositions of the present invention
include base fuels suitable for use in the operation of spark-ignition or
compression-
ignition internal combustion engines such as diesel fuel, jet fuel, kerosene,
unleaded
motor and aviation gasolines, and so-called reformulated gasolines which
typically
contain both hydrocarbons of the gasoline boiling range and fuel-soluble
oxygenated
blending agents, such as alcohols, ethers and other suitable oxygen-containing
organic
compounds. Oxygenates suitable for use in the present invention include
methanol,
ethanol, isopropanol, t-butanol, mixed CI to CS alcohols, methyl tertiary
butyl ether,
tertiary amyl methyl ether, ethyl tertiary butyl ether and mixed ethers.
Oxygenates, when
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used, will normally be present in the base fuel in an amount below about 25%
by volume,
and preferably in an amount that provides an oxygen content in the overall
fuel in the
range of about 0.5 to about 5 percent by volume.
In a preferred embodiment, the middle-distillate fuel is a diesel fuel having
a
sulfur content of up to about 0.01 %, preferably 0.005% or less, more
preferably 0.003%
or less, by weight, as determined by the test method specified in ASTM D 2622-
98.
Example 3
A commercial lean NOx trap from a direct injection gasoline (DIG) engine was
cored and cut into 1 inch by 3/4 inch diameter samples. A catalyst sample was
placed in a
I inch stainless tube which in turn was in an electric oven down stream of a
pulsed flame
combustor. The pulsed flame combustor burned iso-octane with and without MMT.
The
combustor cycle was 5 min. consisting of 4 min. lean operation to trap NOx
(lambda l .3
with NOx added to give SOOppm to the catalyst), and 1 min. rich operation to
reduce the
trapped NOx (lambda 0.9 with no added NOx). Typically the catalyst approached
1 S saturation with NOx at the end of the 4 min. lean period so NOx conversion
were
measured during the first 1 min. of the lean period to give data more
representative of a
commercial vehicle. The catalyst oven provided a constant catalyst
temperature. SO2 gas
could be added to the combustor to simulate exhaust from a 30pprn sulfur fuel.
Turning now to Figures 2 and 3, experimental data from a lean NOx trap
evidences the beneficial properties of the present invention. The experimental
protocol
was as follows: exhaust gas from a 30 ppm sulfur equivalent fuel was run over
the lean
NOX catalysts for 46 hours with the catalyst temperature 350C. The NOX
conversion was
measured constantly throughout the test. The MMT fuel contained MMT at 18 mg
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Mniliter. Reported conversion was calculated for the frst I minute at lean
operation.
The loss in NOX conversion on an hourly basis is substantially higher for non-
MMT
containing fuels.
Figure 2 illustrates the deterioration rate for NOx conversion. Conversely,
this
could be looked upon as the rate of sulfur poisoning of the conversion
process. As can be
seen from this data, MMT at 18 mg Mn/liter protected the catalyst from sulfur
poisoning
and resulted in a deterioration rate that was only 80% of that observed from
base fuel
without MMT.
Figure 3 illustrates the lean NOx Trap NOX efficiency at the end of test for
several
temperatures.. The LNT operated on a fuel containing MMT displayed higher
activity
across a range of temperatures.
Figure 4 illustrates the deterioration rate for NOx conversion with four
separate
catalyst samples from the same catalyst. Samples #I and #2 utilized base fuel
and
samples #3 and #4 utilized a fuel containing MMT. Both samples with MMT showed
I S lower deterioration rates. Since the differences in deterioration rates
axe much greater
than the 95% confidence limits, these differences are considered statistically
significant.
The present invention is suitable for use in all combustion systems including
burners and large and small engines, such as 4 stroke and 2 stroke engines,
e.g. those in
generators, leaf blowers, trimmers, snow blowers, marine engines, or other
types of
engines which may have the scavenger delivered to the combustion chamber. The
scavenger is effective in the effluent stream of an exhaust system, especially
where the
emissions control is downstream from the combustion system.
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It is to be understood that the reactants and components referred to by
chemical
name anywhere in the specification or claims hereof, whether referred to in
the singular
or plural, are identified as they exist prior to coming into contact with
another substance
referred to by chemical name or chemical type (e.g., base fuel, solvent,
etc.). It matters
not what chemical changes, transformations andlor reactions, if any, take
place in the
resulting mixture or solution or reaction medium as such changes,
transformations and/or
reactions are the natural result of bringing the specified reactants and/or
components
together under the conditions called for pursuant to this disclosure. Thus the
reactants
and components are identified as ingredients to be brought together either in
performing a
desired chemical reaction (such as formation of the organornetallic compound)
or in
forming a desired composition (such as an additive concentrate or additized
fuel blend).
It will also be recognized that the additive components can be added or
blended into or
with the base fuels individually per se and/or as components used in forming
preformed
additive combinations and/or sub-combinations. Accordingly, even though the
claims
hereinafter may refer to substances, components and/or ingredients in the
present tense
("comprises", "is", etc.), the reference is to the substance, components or
ingredient as it
existed at the time just before it was first blended or mixed with one or more
other
substances, components and/or ingredients in accordance with the present
disclosure.
The fact that the substance, components or ingredient may have lost its
original identity
through a chemical reaction or transformation during the course of such
blending or
mixing operations is thus wholly immaterial for an accurate understanding and
appreciation of this disclosure and the claims thereof.
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At numerous places throughout this specification, reference has been made to a
number of U.S. Patents and published foreign patent applications. All such
cited
documents are expressly incorporated in full into this disclosure as if fully
set forth
herein.
This invention is susceptible to considerable variation in its practice.
Therefore
the foregoing description is not intended to limit, and should not be
construed as limiting,
the invention to the particular exemplifications presented hereinabove.
Rather, what is
intended to be covered is as set forth in the ensuing claims and the
equivalents thereof
permitted as a matter of law.
Patentee does not intend to dedicate any disclosed embodiments to the public,
and
to the extent any disclosed modifications or alterations may not literally
fall within the
scope of the claims, they are considered to be part of the invention under the
doctrine of
equivalents.
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