BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to novel unleaded fuel compositions for spark ignition internal combustion engines. More particularly, it relates to organomanganese and unleaded fuel combinations, and a mechanical and/or chemical means capable of reducing the formation of heavy manganese oxides (e.g. Mn ₃ 0 ₄ ) during combustion, such that resultant hydrocarbon emissions can meet minimal legal environmental standards.

Description of the Prior Art

The incorporation of various organo-metallic compounds as antiknock agents in fuels for high compression, spark ignited, internal combustion engines has been practiced for some time. The common organo-metallic compound used for this purpose has been tetraethyl lead (TEL) . Generally, these organo-metallic compounds have served well as antiknock agents. However, certain environmental hazards have been associated with the alkyl lead components of these compounds. This circumstance has precipitated a series of Environmental Protection Agency (EPA) mandates which has essentially phased out leaded gasolines.

Many alternatives to tetraethyl lead compounds have been proposed and/or used. For example, organomanganese compounds such as cyclomatic manganese tricarbonyls (CMT) , particularly methylcyclopentadienyl manganese tricarbonyl

(MMT) , were once accepted alternatives to TEL. However, these compounds produced another set of environmental problems. Namely, their use steadily increased the amount of unoxidized and/or partially oxidized hydrocarbon emissions. Fuels containing such organomanganese compounds gradually cause substantially higher levels of hazardous hydrocarbon emissions than are permitted under law. Further, industry experience shows that organomanganese concentrations greater than 1/16 gram Mn/per gallon (0.0165212 grams/liter) are directly responsible for catalytic converter plugging. Accordingly, U.S. federal law bans the use of manganese (i.e. MMT) in all unleaded gasolines absent an EPA § 211(f) (4) Waiver. Thus far every attempt to obtain such a waiver has failed. It is well known in the art that many types of oxygenated components can be included with unleaded bases as a means of improving antiknock properties and/or reducing the carbon monoxide emissions of a fuel. These oxygenated components include lower molecular weight alcohols, various ethers, esters, oxides, phenols, ketones and the like. Several of these components have also been used as neat motor fuels in their own right, i.e. methanol.

Several of these oxygenated components can be used in combination with each other. See, for example, "Low-Lead Fuel with MTBE and C4 alcohols," Csikos, Pallay, Laky, et al, "Hydrocarbon Processing," July 1976, and U.S. Patents 4,207,077 and 4,207,976.

Numerous studies have been conducted on the use of ethers, particularly methyl tertiary butyl ether and tertiary amyl methyl ether in gasoline bases, see for example "Ether Ups Antiknock of Gasoline," Pecci and Floris, HYDROCARBON PROCESSING, December 1977. The U.S. Clean Air Act as amended (42 USC 7445) ("CAA") , governs the usage and introduction of all additives in unleaded gasolines in the United States. The CAA under Section 211(f)(4) permits the EPA Administrator to waive the prohibition on new fuel additives in unleaded gasolines ("Waiver") . The CAA specifically bans manganese ("Mn") additives in unleaded fuels, absent a waiver. However, prior to granting a waiver, the Administrator must determine applicant\'s waiver request meets the burden of demonstrating that the new fuel or fuel additive will not cause or contribute to the failure of an emission control system or regulated emission standard(s) . Under this section of the CAA, the Administrator has both denied and granted numerous waiver requests. However, as noted in the case of organomanganese compounds (i.e. MMT) , the EPA has denied each and every one of four separate Waiver applications since 1978. Denial was based upon the failure to demonstrate at 1/8, 1/16, 1/32, and 1/64 grams of manganese per gallon (3.785 liters) that MMT would not cause long term hydrocarbon emission degradation or emission system failure (e.g. catalyst plugging) . See generally Environmental Protection Agency RE Applications for MMT Waiver, Federal Register, Vol. 43,

No. 181, Monday, September 18, 1978, and Ethyl Corp.; Denial of Application for Fuel Waiver; Summary of Decision, Federal Register, Vol. 46, No. 230, Tuesday, Dec. 1, 1981. In view of the U.S. federally mandated ban on manganese, namely, methyl cyclopentadienyl manganese tricarbonyls (MMT) in unleaded gasoline, the inability of industry in spite of repeated attempts to obtain a § 211(f) waiver for MMT, and in view of overwhelming industry need, there exists a very pressing requirement to find a way in which organomanganese compounds can qualify use in unleaded gasolines on an environmentally acceptable basis, particularly in meaningful concentrations.

SUMMARY OF THE INVENTION

As presented herein. Applicant\'s discovery resides in the source of the problem that causes organomanganese compounds to aggravate hydrocarbon emissions over time. Applicant has discovered that the formation of heavy manganese oxides during combustion (e.g. Mn ₃ 0 ₄ and Mn ₂ 0 ₃ ) are associated with the build up of engine deposits, catalyst plugging, and aggravated hydrocarbon emissions, which are the features responsible for the failure of cyclomatic manganese tricarbonyl compounds to meet CAA regulated emission standards. Applicant has discovered that it is the management of these heavy manganese oxides during combustion that represents the long eluded solution to the problem of organomanganese compounds.

Applicant\'s invention is distinguished from the prior art in that Applicant has discovered the source of the problem together with the means to solve it.

Applicant has discovered that the adverse hydrocarbon (HC) emission degradation over time and the other pollution problems associated with cyclomatic manganese tricarbonyls are directly traceable to first, the formation of heavy manganese oxides, namely, Mn ₃ 0 ₄ and Mn ₂ 0 ₃ , and second, to their build-up into particles of sufficient size and mass to become problematic. This particulate build up and engine deposit process is instantaneous and in combination with the complex hydrocarbon combustion reactions that occur during combustion and shortly thereafter. In other words, these Mn oxides combine with each other, and the other organic and inorganic material found in gasolines and air during the rapid combustion and exhaust process.

Those skilled in the art have generally accepted heavier manganese oxides (i.e. Mn ₃ 0 _A and Mn ₂ 0 ₃ ) as a given, i.e. that they are the primary and/or only manganese ("Mn") oxidation product formed during combustion.

Applicant has discovered that it is the formation of these heavier manganese oxides during [a less than optimum] combustion process that ultimately causes spark plug and catalyst fouling, combustion chamber deposits and the like. This in turn leads to adverse hydrocarbon emission problems, preventing organomanganese compounds from qualifying for § 211 (f) EPA waivers, and from complying with appropriate environmental standards.

Applicant has unexpectedly discovered that by accelerating and improving combustion to an optimum state, thereby controlling and/or eliminating the formation of heavier manganese oxides during combustion, that hazardous combustion emissions (chiefly hydrocarbon emissions) , catalyst plugging, and the like, can be controlled and even reduced. Such control will permit Applicant\'s fuels to meet required environmental standards and to qualify for § 211 (f) EPA waivers. Applicant has unexpectedly discovered that the control of these heavier manganese oxides during combustion is primarily a function of 1) increasing combustion burning velocity (flame speed) and 2) reducing combustion temperatures. By increasing the burning velocity (flame speed, fuel economy, etc) , i.e. shortening the interval of combustion, the hazardous emission causing heavier manganese oxides are not readily formed. By increasing burning velocity, when employing an organomanganese compound, combustion is efficient and cleaner. Applicant has unexpectedly discovered that improvements in burning velocity reduces both hazardous HC and NOx emissions.

Applicant has also unexpectedly discovered that by reducing combustion temperatures, hazardous combustion emissions can be additionally controlled. The reduction of combustion temperatures helps reduce the formation of problematic heavier manganese oxides during combustion.

Applicant has unexpectedly discovered that reductions in combustion temperatures reduces both HC and NOx emissions. In the practice of this invention, compounds/ components and/or means that reduce combustion temperatures are particularly preferred. The greater the temperature reductions, the better.

Fuel compositions, that as a consequence of their pre- ignition vaporization into the combustion chamber that reduce the vapor fraction\'s temperature, are also preferred.

Naturally, compounds/components and/or means that both increase burning velocity and reduce combustion temperatures are particularly preferred.

By increasing burning velocity (e.g. flame speed, laminar or turbulent burning velocity, fuel economy, combustion efficiency, etc.) while simultaneously reducing combustion temperatures, substantial reductions in heavy manganese oxide formation can be achieved, hence controlling hazardous emissions. It appears that the phenomena of accelerating burning velocity and/or reducing combustion temperatures also helps non-manganese fuels. In other words, fuels that do not contain Mn, but which due to their chemistry, operating conditions, and the like, have hazardous exhaust emissions, can be made cleaner by Applicant\'s invention.

It has been unexpectedly discovered that use the of methylene di methyl ether, carbonic acid dimethyl ester, methyl tertiary butyl ether, in defined concentrations,

together with defined concentrations of Mn in unleaded gasoline, both increase burning velocities and reduce temperature of fuels combusted in engines specially designed for unleaded gasoline usage, resulting in a significant reduction of hazardous hydrocarbon and NOx emissions.

Therefore, an integral element of the claimed invention is the engine, itself, which contributes to the beneficial results. This is unexpected because the use of Mn in fuels combusted in such engines in the past has caused an increase in hazardous hydrocarbon and NOx emissions.

Therefore, the practice of this invention includes the utilization of an engine and exhaust system, specially designed for unleaded fuel usage.

It is now anticipated that due to the discovery of the source of the problem, that other compounds, which increase burning velocity, will be identified by routine research.

It is known in the art that several mechanisms may increase burning velocity. Therefore, in the practice of this invention, compounds/components and/or means that increase burning velocity are desired. For example, the increase of the partial vapor pressure of the vaporized fraction prior to combustion, resulting in increased burning velocity, would be desirable. Those compounds/components and/or means that increase Reid Vapor

Pressure (RVP) of the finished gasoline, which in turn

operates to increase burning velocity, would also be desirable.

In the practice of this invention, compound/components and/or means, be they chemical or mechanical, including exhaust oxygen sensing systems, which increase the fuel-air equivalency ratio, resulting in increased burning velocity, are desirable.

Those means which operate to increase combustion pressures and/or compression, which in turn increase burning velocity, are desirable.

In the practice of this invention, combustion catalysts that operate to improve combustion, and combustion efficiency, fuel economy, particularity those also reducing combustion temperatures and/ or increasing burning velocities are desirable.

Certain molecular features have been identified by Applicant that reduce heavy manganese oxide formation during combustion. They include H, H ₂ , CO, and/or 0CH ₃ (methoxy radicals) , and/or OH (hydroxyl radicals) . Those compound/components wherein H, H ₂ CO, OCH ₃ , and/or OH radicals exist, in high relative concentrations and/or become intermediate combustion products are preferred. The higher the relative weight percentage of these structural components in the component/compound and/or that otherwise occur/result during combustion, the better. Such features may be individual or collective. Again, the object is to reduce adverse emissions by increasing burning velocity and/or by reducing combustion temperatures.

Those compounds that applicant has thus far identified that are effective in accomplishing this object, include: carbon monoxide, ethylene di methyl ether (also known as methylal, di-methoxy methane) , carbonic acid dimethyl ester (also known as dimethyl carbonate) , and methyl tertiary butyl ether (MTBE) , C, to C ₆ lower molecular weight alcohols, particularly methanol and ethanol. Applicant believes many others also exist.

Applicant notes that the desirable OCH ₃ (methoxy radical) structure is common to methanol, methylene di methyl ether (methylal) , and carbonic acid dimethyl ester (dimethyl carbonate) . Applicant believes these latter compounds to be among the best in accomplishing Applicant\'s object. Accordingly, those oxygenates which employ methanol and ethanol in their manufacture are likely to be effective and are contemplated within the scope of this invention. It is believed that such a compound\'s intermediate combustion and other features will positively effect Applicant\'s object.

EXAMPLE TEST FUELS Applicant tested several example fuels, including: A. MEOH FUEL 0.033025 grams manganese of MMT per liter of composition, 5% methanol and 5% ethanol by volume, and unleaded gasoline base.

B. ISO/HEX FUEL 0.033025 grams manganese of MMT per liter, 10% isopropanol and 10% hexanol by volume, and unleaded gasoline base.

C. MTBE FUEL 0.033025 grams manganese of MMT per liter, 14.6% MTBE by volume, and unleaded gasoline base.

D. PMC FUEL 0.033025 grams manganese of MMT per liter, 4.6% Dimethyl Carbonate (DMC) by volume, and unleaded gasoline base.

E. METHYLAL FUEL 0.033025 grams manganese of MMT per liter, 7.2% Methylal by volume, and unleaded gasoline base.

F. THF FUEL 0.033025 grams manganese of MMT per liter, 1.6% Tetrahydrofuran by volume, and unleaded gasoline base.

G. HIGH MANGANESE (Mn) FUEL 0.5284 grams manganese of MMT per liter, 5% Methanol by volume, and unleaded gasoline base.

H. MANGANESE FUEL 0.033025 grams manganese of MMT per liter, and unleaded gasoline base.

I. BASE FUEL Unleaded gasoline base (Clear fuel).

Test Methodology

The above example fuels were tested in a 1988 Chevrolet C1500 pickup truck with a 350 CID V-8 engine, having a throttle-body fuel injection system and oxygen sensor-closed loop fuel control. The inclusion of this oxygen sensing system provided a means of adjusting the stoichiometry to compensate for variations in the oxygen content of the various test fuels. This feature eliminated

bias in HC and NOx emissions due to oxygen content differences. In other words, a test fuel with a high oxygen content, tending to enlean combustion, would not necessarily show better or worse emissions than the fuel containing little or no oxygen.

Furthermore, this is an integral feature of the unleaded fuel engine and exhaust systems, and particularly, the regulated emission control systems of the instant invention. The engine heads and valves were cleaned before each fuel was tested. A new oxygen sensor and new spark plugs were also installed.

Each fuel was subjected to two (2) principal tests. The First Test ("Test One") measured HC and NOx emissions from the engine over a forty (40) hour, steady state, 1000 rpm, no load cycle. The purpose of this no load, steady state test was to elicit worse case hydrocarbon (HC) emissions over time. This test condition accelerated HC emission degradation from what would have been expected had a much longer durability type test been conducted.

Prior to introducing each new test fuel, the clean engine was cured on the BASE fuel ("clear fuel") until exhaust emissions stabilized. This generally required approximately 3 to 6 hours of steady state operation. Hydrocarbon and NOx emissions were measured periodically utilizing Beckman exhaust emission analyzers. See TABLE 1 for a summary of data.

The Second Test ("Test Two") was conducted immediately after the First Test using the same fuel with the same engine still warm. The Second Test was conducted with the vehicle on a stationary chassis dynamometer. Test measurements were made at 50 mph (80.5 kilometers per hour "kph") under varying load conditions, e.g. from 15 to 24 indicated horse power ("ihp") . This test measured differences in combustion temperatures, HC and NOx emissions, and fuel economy. See Figures 1 through 6 for a summary of results.

The test results for Test One and Test Two are set forth as follows:

A. MEOH FUEL 0.033025 grams Manganese of MMT per liter of composition, 5% methanol and 5% ethanol by volume, and unleaded gasoline base. -Test One-

PH (80.5kph)

B. ISO/HEX FUEL 0.033025 grams Manganese of MMT per liter, 10% isopropanol and 10% hexanol by volume, and unleaded gasoline base.

-Test One-

-Test Two- Not conducted

C. MTBE FUEL 0.033025 grams Manganese of MMT per liter, 14.6% MTBE by volume, and unleaded gasoline base.

NOx ppm

98

98

91

103

108

109

104

97 81

-Test TWO- ENGINE GAS HC NOX FUEL ECON TEMP F/C° gpt ppm (mp /kpl) COMMENTS

749(398C) 2.06 4.31 19.3/8.2 50 MPH (80.5 kph) § 16 ihp 778(414C) 2.33 5.34 16.2/6.9 50 MPH (80.5 kph) @ 22 ihp

D. DMC FUEL 0.033025 grams Manganese of MMT per liter, 4.6% Dimethyl Carbonate (DMC) by volume, and unleaded gasoline base.

-Test One-

F. THF FUEL 0.033025 grams Manganese of MMT per liter, 1.6% Tetrahydrofuran by volume, and unleaded gasoline base.

-Test One-

-Test Two- (not conducted)

G. HIGH MN FUEL 0.5284 grams Manganese of MMT per liter, 5% Methanol by volume, and unleaded gasoline base.

-Test One-

NOx ppm

169

167

206 182

268

281

198

195 167

174

167

H. MANGANESE FUEL 0.033025 rams Man ane

TABLE 1

HYDROCARBON EMISSIONS OVER TIME SUMMARY OF RESULTS (TEST ONE.

NOTES:

(1) This column represents the % change of HC emissions for the last half of Test One.

(2) This column represents total % change of HC emissions over the entire test.

(3) This represents the average of the more stabilized, later stage HC emissions. Average calculated for the final hours of the test, as indicated.

Analysis of TABLE 1

TABLE 1 sets forth the HC emission results of Test

One. It shows that the Manganese, THF, and High Mn fuels result in significant increases in HC emissions over time. It shows that these increases are much greater than the

ISO/HEX, MEOH, MTBE, METHYLAL, and DMC fuels.

Applicant notes that the HC emission changes of the last 20 hours of the test (column B) are fairly indicative of long term HC emission degradation. Even the Base fuel (absent Mn) experienced significant HC emission degradation during this period. The BASE fuel shows an increase of 38%, slightly lower than the Manganese, and THF fuels, which each showed 41% increases in HC\'s (Column B) .

In stark contrast, the ISO/HEX, MEOH, MTBE, METHYLAL, and DMC fuels did not show the same significant HC emission increases. Their increases were substantially lower than the Manganese fuel, ranging from a 15% increase for MEOH, to a 25% decrease for DMC; HC emission decreases were noted for the METHYLAL and DMC fuels at 9% and 25%, respectively. (Column B) . Incredibly the ISO/HEX, MEOH, MTBE, METHYLAL, and DMC fuels (all containing Mn) experienced HC increases much lower than even the Base fuel (absent Mn) .

The Manganese, High Mn, and THF fuels all showed materially higher later stage (Column D) HC emissions (3390, 6554, and 4130 ppmc, respectively), than the Base fuel (3067 ppmc) .

In contrast, the ISO/HEX, MEOH, MTBE, METHYLAL, and DMC fuels did not show the high HC emission levels of the Manganese fuel (3390 ppmc) (Column D) . Their HC emission levels, instead, were materially lower ranging from 2953 to 2024 ppmc for MEOH and ISO/HEX, respectively (Column D) . Astonishingly, the ISO/HEX, MEOH, MTBE, METHYLAL, and DMC hydrocarbon emissions (Column D) are all also below the Base (clear) fuel (3076 ppmc) . These results are most unexpected. In summary, the Manganese, THF, High Manganese test fuels show considerably high increases in HC emissions over time. In contrast, the ISO/HEX, MEOH, MTBE, METHYLAL, and DMC fuels do not. They control HC emissions, not only better than the Manganese fuel, but even better than the BASE fuel (absent Mn) .

DESCRIPTION OF TEST TWO FIGURES 1 THROUGH 6 FIGURE 1

Combustion Temperature Differences. This Figure compares engine exhaust gas temperatures ("EGT") of the MANGANESE, BASE, MEOH, MTBE, METHYLAL, and DMC fuels as a function of engine load. Test Two placed the engine under load conditions at 50 mph in order to elicit differences in fuel combustion temperatures, measured by engine exhaust gas temperatures ("EGT").

At 15 ihp the EGT\'s for all tested fuels (except MTBE) are relatively close together. The BASE and Manganese fuels are the same at 707°F (375C) , while the DMC, MEOH, and

METHYLAL fuels range tightly from 717°F (381C) , 722°F (383C) , and 724°F (384C) , respectively. The MTBE fuel, which was tested at 16 ihp, measured 749°F (398C) .

As load was increased, EGT\'s increased very rapidly for the Manganese and BASE fuels. The Manganese fuel increase was the greatest. For example, at 20 ihp, the BASE fuel temperature was 828°F (442C) and Manganese\'s projected temperature at the same ihp was 860°F (460C) .

In contrast, the MEOH, MTBE, METHYLAL, and DMC fuels had lower rates of EGT increase. For example, at 24 ihp, the MEOH, METHYLAL, and DMC fuels were tightly grouped at

785°F (418C), 795°F (424C) , and 798°F (426C) , respectively.

Similarly, MTBE showed an even lower rate of increase of

778°F (414C) at 22 ihp. The most significant aspect of Figure 1, is the strong showing that MEOH, MTBE, METHYLAL, and DMC fuels, enjoy markedly lower combustion temperatures than either the BASE or Manganese fuels at the same loads. For example, Figure

1 shows that at 20 ihp the EGT for the Manganese fuel is 104°F (40C) higher than the MEOH fuel. Additionally, Figure

1 shows that the fuels containing both Mn and an oxygenate

(i.e. the MEOH, MTBE, METHYLAL, and DMC fuels) also had significantly lower combustion temperatures than the BASE fuel. For example, the MEOH fuel was 72°F (22C) lower than the BASE fuel.

Figure 1 shows that the higher the load, the greater the EGT differences between the two classes of fuels.

FIGURE 2

Combustion Temperatures and Hydrocarbon Emissions. This Figure shows hydrocarbon emissions of Test Two as a function of engine gas temperatures ("EGT") . This Figure shows that there is a direct correlation between HC emissions and engine gas temperatures. The relationship is most notable in the MEOH, MTBE, METHYLAL, and DMC fuels. Figure 2 shows that the HC/EGT rate of change for the various oxygenates is higher than the HC/EGT rate of change for the non-oxygenated fuels. Figure 2 shows that the lower the combustion temperature of a given oxygenate, the lower the HC emissions.

FIGURE 3 Combustion Temperatures and NOx Emissions. This

Figure shows NOx emission results as a function of EGT. Figure 3, like Figure 2, shows a direct and significant relationship between NOx emissions and EGT for MEOH, MTBE, METHYLAL, and DMC fuels. This Figure clearly shows that at lower EGT\'s, particularly in the case of the MEOH, MTBE, METHYLAL, and DMC fuels, NOx emissions are much lower than when compared to the BASE and Manganese fuels.

FIGURE 4 Indicated Burning Velocity. This Figure measures burning velocity indirectly via fuel economy measurements as a function of load. It is known in the art that increases in fuel economy, absent a BTU boost, is an

indicator of a flame speed or burning velocity increase. Figure 4 shows fuel economy in miles per gallon ("mpg") (or 0.42566 kilometers per liter "kpl") as a function of load (ihp) . Figure 4 shows significant fuel economy ("FE") differences between the BASE and the oxygenated fuels, beginning almost immediately with the application of load. Note, that at 20 ihp the fuel economy of the Base fuel is 13.2 mpg (5.619 kpl), compared to 15.7 mpg (6.683 kpl), 15.9 mpg (6.768 kpl), 16.5 mpg (7.0234 kpl) and 17.2 mpg (7.321 kpl) for METHYLAL, MEOH, DMC, and MTBE, respectively. These material differences account for a 19% to 30% improvement in fuel economy over the BASE fuel. These FE improvements indicate substantial burning velocity increases for the METHYLAL, MEOH, DMC, and MTBE fuels.

FIGURE 5

Burning Velocity and HC Emissions. This Figure shows HC emissions as a function of fuel economy, i.e. indicated burning velocity. Figure 4 shows a strong correlation between increased burning velocity to improvements in HC emissions. Figure 5 clearly shows that increased burning velocity for METHYLAL, MEOH, DMC, and MTBE translates into improved HC emissions. This correlation is most apparent for the MEOH fuel.

FIGURE 6

Burning Velocity and NOx Emissions. This Figure shows NOx emissions as a function of fuel economy. This

Figure shows a very strong correlation between increased indicated burning velocity to improvements in NOx emissions. This correlation exists for oxygenated fuels, but is not noticeable for the BASE fuel.

PREFERRED PRACTICE

To the extent that oxygenated compounds are utilized to accomplish the object of accelerating burning velocity and/or to reduce combustion temperatures, while not required, it is preferred that the oxygen content, as a percent of total weight of the constituent additive compound, be 15% or more of the total weight of the oxygenate. While lower oxygen concentrations are acceptable, the higher the relative oxygen content, as a weight percentage of the total oxygenated compound/component, the more preferred. It is believed that the simpler the compound/component\'s molecular structure the better. More complicated molecular structure is acceptable, particularly, if the intermediate combustion products enhance burning velocity and/or reduce combustion temperatures.

It is preferred that the thermal efficiency (e.g. fuel economy) of the finished fuel containing the component/compound, be an improvement over the base fuel alone.

Applicant appreciates that numerous means may be employed to achieve the beneficial results contemplated by Applicant\'s discovery of the source of the problem.

Applicant further appreciates that with his discovery of the source of the problem that numerous other components, compounds, oxygenated and non-oxygenated, including combinations thereof, and/or mechanical/chemical means, will be identified by routine investigation to reduce and/or eliminate heavy manganese oxide formation during combustion.

It is contemplated that by the practice of this invention that fuels utilizing applicant\'s discovery of the source of the problem, can meet minimal environmental standards and become eligible for § 211 (f) EPA type waivers, which have heretofore been denied organomanganese and unleaded gasoline combinations.

It is contemplated that by the practice of this invention that problematic, non-Mn containing unleaded fuels (absent organomanganese compounds) may benefit from Applicant\'s discovery of the source of the problem. It is contemplated that in order to control of hazardous emission from these fuels that organomanganese compounds may be required.

It is contemplated that through investigation that certain ethers, phenols, esters, oxides, ketones, alcohols and/or other chemical agents can be identified that will solve Applicant\'s discovery of the source of the problem. The production of ethers is also well known to the art. See for example, U.S. Patents 4,262,145; 4,175,210; 4,252,541; 4,270,929; 3,482,952; 2,384,866; 1,488,605; 4,256,465; 4,267,393; 4,330,679; 4,299,999; 4,302,298;

4,310,710; 4,324,924; 4,329,516; 4,336,407; 4,320,233; 2,874,033; 3,912,463; 4,297,172; 4,334,890, et al.

Possible C2 to C6 ethers for use in the practice of this invention may include branched and straight chain ethers, di ethers having two oxygen and dual ether linkage, and tri ethers having three oxygens and multiple ether linkages. Non-limiting examples of possible C2 to C6 ethers include dimethyl ether, methyl ethyl ether, di ethyl ether, ethyl propyl ether, methyl normal propyl ether, ethyl isopropyl ether, methyl isopropyl ether, ethyl normal propyl ether, propyl propyl ether, propyl isopropyl ether, isopropyl isopropyl ether, ethyl butyl ether, ethyl isobutyl ether, ethyl tertiary butyl ether, ethyl secondary butyl ether, methyl normal butyl ether, methyl isobutyl ether, methyl tertiary butyl ether, methyl secondary butyl ether, methyl normal amyl ether, methyl secondary amyl ether, methyl tertiary amyl ether, and methyl iso amyl ether. Additional non-limiting examples of acceptable di ethers (having two oxygens and dual ether linkage) include methylene di methyl ether, methylene di ethyl ether, methylene di propyl ether, methylene di butyl ether, and methylene di isopropyl ether.

It is expected that ethers, where significant amounts of free H, H ₂ CO, 0CH ₃ , and/or OH radicals become intermediate combustion products, are likely to be the best candidates.

Preferably, the ether(s) employed should be anhydrous. Within the preferred concentration range, most C2 - C6

ethers are completely miscible with petroleum hydrocarbons; and it is preferred that such ethers be used in amounts within their solubility limits. However, if desirable, an amount of ether in excess of its solubility can be incorporated in the fuel by such means, as for example, use of mutual solvents.

Possible ketones that may be acceptable include ketones with three to about twelve carbon atoms. Lower alkenyl ketones are, however, likely to be slightly preferred. Representative lower alkenyl ketones would include diethyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, ethyl butyl ketone, butyl isobutyl ketone, ethyl propyl ketone, and the like. Other ketones include acetone, diacetone alcohol, diisobutyl ketone, isophorone, methyl amyl ketone, methyl isamyl ketone, methyl propyl ketone, and the like. A representative cyclic ketone would be ethyl phenyl ketone. It is expected that those ketones where free H, H ₂ CO, OCH ₃ , and/or OH radicals become intermediate combustion products are likely to be the best candidates. Possible esters that may be acceptable include anisol (methyl ester of benzene) , isopropyl acetate, and ethyl acrylate.

The preferred chemical means for achieving these results is by the addition of a compound or combination of compounds and/or components which, individually or in combination, operate to increase flame speeds/burning velocity and/or reduce combustion temperatures.

An illustrative example of a desirable fuel composition containing an oxygenated agent, would include the oxygenate from about 0.1 to about 20.0 weight percent by oxygen in the composition, with or without co-solvents, and about 0.000264 to about 0.264200 gram manganese per liter of unleaded fuel. A more desirable composition would include the oxygenate from about 0.5 to about 10.0 weight percent by oxygen in the composition, with or without cosolvents, and an organomanganese concentration from about 0.004128 to about 0.099075 grams manganese per liter of the fuel composition. While not required, anhydrous fuel are desirable.

Another desirable composition would include the oxygenate from about 1.0 to about 5.0 weight percent by oxygen in the composition, with or without cosolvents, and an organomanganese concentration from about 0.004128 to about 0.066050 grams manganese per liter of the fuel composition.

Control of Hydrocarbons Emissions

Applicant has discovered that those Cyclomatic Manganese Tricarbonyls (CMT) concentrations that heretofore have been considered excessive for reasons associated with unacceptable engine out hydrocarbon (EOHC) emissions and catalyst plugging, when constructed to solve Applicant\'s discovery of the source of the problem, can prevent unacceptable long term hydrocarbon emissions degradation and prevent catalyst plugging. In other words, manganese

concentrations, for example, greater than 1/64, 1/32, or even 1/16 grams of manganese per 3.785 liters are satisfactory. In view of the prior art literature on the subject, this result is quite unexpected. It appears that levels equal to and exceeding 1/8 or even 3/8 gram of manganese per 3.785 liters are quite satisfactory.

Since the heavy manganese oxides of the above cyclomatic manganese tricarbonyls plays a leading role in hydrocarbon deposit build-up, it is desirable to balance the amount of cyclomatic manganese tricarbonyl compounds employed with the efficacy of the heavy manganese oxide alleviation means, as is necessary in order to maximize the benefits of the invention. In the practice of Applicant\'s invention, concentrations of manganese from about 0.000264 up to as high as 0.2642 gram of manganese per liter may be used. However, concentration levels greater than 0.00825 or even 0.016505 grams but less than 0.1321 grams manganese per liter are more preferred.

In terms of emissions benefits, concentrations of cyclomatic manganese tricarbonyl from about 0.00825 grams to about 0.099075 grams manganese/liter are acceptable; concentrations in the range of about 0.033025 grams to about 0.06605 grams manganese/ liter are preferred.

In terms of octane benefits, a desirable range is from about 0.000264 to about 0.06605 grams manganese per liter of composition. A more desirable range is from about 0.004128 to about 0.033025 grams manganese per liter of

composition. A preferred range is from about 0.004128 to about 0.016512 grams manganese per liter of composition.

A preferred cyclomatic manganese tricarbonyl used in the composition is cyclopentadienyl manganese tricarbonyl. A more preferred cyclomatic manganese tricarbonyl is methyl cyclopentadienyl manganese (MMT) . As contemplated in this invention, the composition can also contain homologues or other cyclomatic manganese tricarbonyl substitutes. Non- limiting examples of these other acceptable substitutes include the alkenyl, aralkyl, aralkenyl, cycloalkyi, cycloalkenyl, aryl and alkenyl groups. Illustrative and other nonlimiting examples of acceptable cyclomatic manganese tricarbonyl antiknock compounds include benzyleyelopentadienyl manganese tricarbonyl; 1.2-dipropyl 3-cyclohexylcyclopentadienyl manganese tricarbonyl; 1.2- diphenylcyclopentadienyl manganese tricarbonyl; 3- propenylienyl manganese tricarbonyl; 2-tolyindenyl manganese tricarbonyl; fluorenyl manganese tricarbonyl; 2.3.4.7 - propyflourentyl manganese tricarbonyl; 3- naphthy1fluorenyl manganese tricarbonyl; 4.5.6.7- tetrahydroindenyl manganese tricarbonyl; 3-3ethenyl-4, 7- dihydroindenyl manganese tricarbonyl; 2-ethyl 3 (a- phenylethenyl) 4,5,6,7 tetrahydroindenyl manganese tricarbonyl; 3 - (a-cyclohexylethenyl) -4.7 dihydroindenyl manganese tricarbonyl; 1,2,3,4,5,6,7,8 - octahydrofluorenyl manganese tricarbonyl and the like. Mixtures of such compounds can also be used. The above compounds can be generally prepared by methods that are

known in the art. Representative preparative methods are described, for example, in U.S. Patents 2,819,416 and 2,818,417.

In a further effort to control hydrocarbon emissions, Applicant also contemplates the use of other additives with his ingredients, such as gum and corrosion inhibitors, detergents, multipurpose additives, and scavengers, made necessary or desirable to maintain fuel system cleanliness and control exhaust emissions. Applicant\'s invention contemplates a method for controlling hazardous combustion emissions originating in internal combustion engines. This method comprises the mixing of a nonleaded gasoline base comprised of hydrocarbons with a cyclopentadienyl manganese tricarbonyl antiknock compound having a manganese concentration from about 0.000264 to about 0.2642 grams of manganese per liter of the fuel composition, together with a chemical and/or mechanical means for reducing the formation of heavy and/or hazardous emission causing oxides of manganese during the combustion of said fuel. Applicants method then contemplates the combustion of said fuel composition in an internal combustion engine; then emitting the resultant engine emissions through an exhaust system, including catalytic exhaust systems; such that the resultant emissions and/or emission control systems meet § 211 (f) waiver requirements.

Applicant\'s invention also contemplates a method for controlling hazardous combustion emissions originating in

internal combustion engines; comprises the mixing of a nonleaded gasoline base comprised of hydrocarbons with a cyclopentadienyl manganese tricarbonyl antiknock compound having a manganese concentration from about 0.000264 to about 0.2642 grams of manganese per liter of the fuel composition, together with a chemical and/or mechanical means for accelerating burning velocity and/or reducing combustion temperatures of said fuel; then combusting said fuel composition in a spark ignited internal combustion engine; then emitting the resultant emissions through an exhaust system, including catalytic exhaust systems; such that the resultant emissions meet § 211 (f) waiver requirements.

USING COSOLVENTS It is contemplated that co-solvents may be employed for several reasons, including, the correction of technical enleanment, vapor pressure control, and phase stability. Cosolvent(s) may be selected from the group consisting of C2 to C12 aliphatic alcohols, C3 to C12 ketones, C2 to C12 ethers, esters, oxides, phenols, and the like. It is in the scope of this invention to employ one or more co¬ solvents within a particular class of cosolvents and/or to employ any one or more classes of cosolvents simultaneously. It is also within the scope of this invention to mix different classes of cosolvents, including mixed alcohols, ethers, esters, oxides, phenols and/or ketones. For example, it has been found that mixed cosolvent alcohols.

particularly those in the C2 to C8 range, have a particularly ameliorative effect on both RVP and octane blending values.

Acceptable cosolvent concentrations will vary depending upon the other components and their concentrations in the composition, but will normally range from between 0.1 to about 20.0 volume percent of the composition. More desirable concentrations will normally range from between 0.1 and to about 15.0% volume percent of the composition. Preferred concentrations will range from about 0.1 volume percent to 10 volume percent, with the most preferred ranging from about 0.1 to about 5.0 volume percent.

It is also within the scope of this invention to utilize individual and/or different molecular weight cosolvent mixtures. For example, higher molecular weight alcohol mixtures (especially C4 - C12 in varying combinations and concentrations) can be employed as a means of controlling RVP, evaporative emissions, volatility, initial and mid-range distillation depressions, to reduce end boiling point temperatures, and to even provide for the inclusion of hydrocarbons boiling above gasoline temperatures in the composition.

Technical enleanment is related to depressed initial and mid-range distillation curves. It is contemplated that the use of cosolvents may be employed independently or in combination with hydrocarbons boiling above idrange boiling temperatures so as to improve distillation

temperature depression in order to mitigate technical enleanment. Such temperature depression may also be remedied independent of co-solvents with the use of one of more higher boiling temperature hydrocarbons, which when added to the composition corrects the depression of distillation temperatures.

It has also been discovered and is within the scope of this invention to employ higher molecular weight co- solvents, in combination with the other necessary elements of this invention, to reduce hazardous emissions. For example, an azeotroping co-solvent in combination with hazardous emission causing heavier hydrocarbon, where the resultant heavier hydrocarbon and co-solvent oxygen combust together, under conditions where combustion is accelerated and/or where combustion temperature is reduced, is one such means.

UNLEADED BASE GASOLINE COMPOSITION The gasoline to which this invention is applied is a lead free gasoline. The gasoline bases in Applicant\'s fuel composition are conventional motor fuels, boiling in the general range of about 70 degrees to about 440 degrees F. However, boiling ranges outside gasoline ranges are contemplated and may be used. Substantially all grades of unleaded gasoline employed in spark ignition internal combustion engines are contemplated. Other non-internal combustion engine fuel applications are also contemplated.

Generally, fuel bases may contain both straight runs and cracked stock, with or without alkylated hydrocarbons, reformed hydrocarbons, and the like. Such fuels can be prepared from saturated hydrocarbons, e.g., straight stocks, alkylation products, and the like, with or without detergents, antioxidants, dispersants, metal deactivators, lead scavengers, rust inhibitors, multi-functional additives, emulsifiers, demulsifiers, fluidizer oils, anti- icing, combustion catalysts, corrosion and gum inhibitors, emulsifiers, surfactants, solvents, and/or other similar or known additives. It is contemplated that in certain circumstances, these additives may be included in concentrations above normal levels, made necessary to accommodate the ingredients of Applicant\'s invention. Generally, the base gasoline will be a blend of stocks obtained from several refinery processes. The final blend may also contain hydrocarbons made by other procedures, such as alkylates made by the reaction of C4 olefins; butanes using an acid catalyst such as sulfuric acid or hydrofluoric acid; and aromatics made from a reformer.

The olefins are generally formed by using such procedures as thermal cracking and catalytic cracking. Dehydrogenation of paraffins to olefins can supplement the gaseous olefins occurring in the refinery to produce feed material for either polymerization or alkylation processes. The saturated gasoline components comprise paraffins and naphthenates. These saturates are obtained from: (1) virgin gasoline by distillation (straight run gasoline) ,

(2) alkylation processes (alkylates) , and (3) isomerization procedures (conversion of normal paraffins to branched chain paraffins of greater octane quality) . Saturated gasoline components also occur in so-called natural gasolines. In addition to the foregoing, thermally cracked stocks, catalytically cracked stocks and catalytic reformates contain saturated components. Preferred gasoline bases are those having an octane rating of (R + M)/2 ranging from 70-95. A desirable gasoline base should have an olefinic content ranging from 1 to 30 volume percent, and a saturate hydrocarbon content ranging from about 40 to 80 volume percent.

The motor gasoline bases used in formulating the fuel blends of this invention generally are within the parameters of ASTM D-439 and have initial boiling points ranging from about 70 degrees F to about 115 degrees F and final boiling points ranging from about 380 degrees F to about 437 degrees F as measured by the standard ASTM distillation procedure (ASTM D-86) . Intermediate gasoline fractions boil away at temperatures within these ranges.

In terms of phase stability and water tolerance, especially when employing lower molecular weight alcohols, desirable base gasoline compositions would include as many aromatics with C8 or lower carbon molecules as possible in the circumstances. The ranking or aromatics in order of their preference would be: benzene, toluene, m-xylene, ethylbenzene, o-xylene, isoproplybenzene, N-propybenzene, and the like. After aromatics, the next preferred gasoline

component in terms of phase stability would be olefins. The ranking of preferred olefins in order of their preference would be: 2-methyl-2-butene, 2 methyl-1 butene, 1 pentene, and the like. However, from the standpoint of minimizing the high reactivity of olefins and their smog contributing tendencies, olefinic content must be closely watched. After olefins the least preferred gasoline component in terms of phase stability, when using for example alcohols, would be paraffins. The ranking of preferred paraffins in order of their preference would be: cyclopentane, N-pentane, 2,3 dimethylbutane, isohexane, 3- methylpentane and the like.

In terms of phase stability, aromatics are generally preferred over olefins; and olefins are preferred over paraffins. Within each specific class, the lower molecular weight components are preferred over the higher molecular weight components.

It is also desirable to utilize base gasolines having a low sulfur content, as the oxides of sulfur tend to contribute to the irritating and choking characteristics of smog and other forms of atmospheric pollution. To the extent it is economically feasible, the base gasolines should contain not more than 0.1 weight percent of sulfur in the form of conventional sulfur-containing impurities. Fuels in which the sulfur content is no more than about 0.02 weight percent are especially preferred for use in this invention.

The gasoline bases of this invention can also contain other high octane organic components, including phenols (e.g., P-cresal, 2, 4 xylenal, 3-methoxyphenal) , esters (e.g., isopropyl acetate, ethyl acrylate) , oxides (e.g., 2- methylfuran) , ketones (e.g., acetone, cyclopentanone) , alcohols (furon, furfuryl) , ethers (e.g., MTBE, TAME, dimethyl, diisopropyl) , aldehydes, and the like. See generally "Are There Substitutions for Lead Anti-Knocks?," Unzelman, G. H. , Forster, E. J., and Burns, A. M. , 36th Refining Mid-Year Meeting, American Petroleum Institute, San Francisco, California, May 14, 1971.

The gasoline may further contain antiknock quantities of other agents, such as cyclopentadienyl nickel nitrosyl, N-methyl aniline, and the like. Antiknock promoters such as 2.4 pentanedione may also be included. The gasoline may contain supplemental valve and valve seal recession protectants. Nonlimiting examples of such additives include boron oxides, bismuth oxides, ceramic bonded CaF2, iron phosphate, tricresylphosphate, phosphorous and sodium based additives, and the like. The fuel may also contain antioxidants, such as 2,6 di-tert-butylephenol, 2,6-di- tert-butyl-p-cresol, and phenylenediamines such as N-N-di- sec-butyl-p-phenylenediamines, N-isopropylphenylene diamine, and the like. The fuel may contain such additives as F310, polybutene amines, aminated or polymerized detergents, and the like.

The gasoline base may contain hydrocarbons boiling outside normal gasoline ranges. It is contemplated in

certain occasions these higher boiling point hydrocarbon can be incorporated into a finished normal boiling gasoline by utilizing the azeotroping effect of certain co- solvents/additives. Applicant has found that higher molecular weight C4-C12 alcohols are particularly useful in reducing end boiling point temperatures.

Those skilled in the art will appreciate that many variations and modifications of the invention disclosed herein may be made without departing from the spirit and scope thereof.