Non leaded fuel composition

Fuel compositions comprised of well-defined proportions of cyclopentadienyl manganese tricarbonyl antiknock compounds, solvents selected from the group consisting of C.sub.1 to C.sub.6 aliphatic alcohols and nonleaded gasoline bases, possess improved long term hydrocarbon combustion emissions and technical enleanment characteristics. When methanol is used as the solvent it is desirable that a cosolvent selected from the group consisting of C.sub.2 to C.sub.12 aliphatic alcohols, C.sub.3 to C.sub.12 ketones and/or C.sub.2 to C.sub.12 ethers also be present in the fuel composition to assure phase stability.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to novel fuel compositions for spark 
ignition internal combustion engines. More particularly, it relates to a 
novel additive combination for "nonleaded" gasoline compositions. 
2. 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 most common organo-metallic compound 
used for this purpose is tetraethyl lead ("TEL"). Generally these 
organo-metallic compounds have served well as antiknock agents. However, 
certain environmental hazards are now associated with the alkyl lead 
components of these compounds. This circumstance has precipitated a series 
of Environmental Protection Agency ("EPA") mandates aimed at completely 
phasing out leaded gasolines. 
Many alternatives to these organo-metallic compounds also have been 
proposed and/or used. For example organomanganese compounds such as 
cyclomatic manganese tricarbonyls particularly methylcyclopentadienyl 
manganese tricarbonyl ("MMT"), were once accepted alternatives to TEL. 
However, these compounds produced another set of environmental problems. 
Their use tends to steadily increase the amount of unoxidized and/or 
partially oxidized hydrocarbons emitted from engines commonly referred to 
as "engine out hydrocarbons" (EOHC). Fuels containing such organomanganese 
compounds gradually cause the emission of substantially higher levels of 
hydrocarbons than are permitted under law. Aggravating the air pollution 
problem, such organomanganese compounds, particularly MMT, when used at 
concentrations greater than about 1/16 per gram manganese per gallon, are 
believed to be responsible for catalytic converter plugging. Accordingly, 
under Federal Law the use of MMT is currently banned in all unleaded 
gasolines. 
It is well known in the art that many lower molecular weight aliphatic 
alcohols possess antiknock properties. They have been used as motor fuels 
in their own right and they have also been used as antiknock additives in 
both leaded and nonleaded gasolines. 
As might be expected, many attempts have been made to combine tetraethyl 
lead, cyclomatic manganese tricarbonyls, and/or lower aliphatic alcohols 
with petroleum hydrocarbon products boiling within the gasoline range. 
Some combinations are the result of chemical compounding, while others 
represent noncompounded physical blends in various combinations. Certain 
combinations of these ingredients have been blended with or without the 
use of stabilizers. U.S. Pat. No. 3,030,195 (the "195 patent") well 
summarizes the results of prior art efforts to physically blend TEL, MMT 
and certain lower aliphatic alcohol antiknock agents in gasoline without 
the aid of stabilizing agents. For example, the 195 patent points out that 
when lower aliphatic alcohols and TEL type compounds are present together 
in petroleum hydrocarbon gasolines, the antiknock effect achieved by the 
combination is substantially lower than would be expected in view of their 
known individual antiknock efficacies. This phenomena is commonly referred 
to as "negative lead susceptibilities". The 195 patent teaches that a 
positive synergism in the antiknock properties of leaded gasoline/alcohol 
fuel compositions can be obtained by adding a cyclomatic manganese 
tricarbonyl such as MMT to leaded gasoline compositions. However, at this 
time the technical advantages produced by such fuel compositions are being 
effectively negated by the phase out of lead containing antiknock 
additives. 
Other investigations aimed at describing the physical properties of leaded 
gasoline/alcohol blends have shown that n-propanol and i-butanol give 
smaller octane increases than methanol or ethanol in leaded 
gasolines/alcohol blends. The antiknock qualities of nonleaded 
gasoline/alcohol blends have also been investigated. These investigations 
also indicate that alcohols in general are considerably more effective 
octane improvers in blends utilizing low octane gasoline components as 
compared to high octane gasolines. See, for example, Cox, Frank W., 
PHYSICAL PROPERTIES OF GASOLINE/ALCOHOL BLENDS, Bartlesville Energy 
Technology Center, Bartlesville, Okla. (1979). 
It is also well known that lower molecular weight aliphatic alcohols and 
gasoline when blended together form nonideal mixtures with respect to 
octane numbers. This nonideal behavior results in an additional benefit in 
that the actual increase in octane value of a gasoline/alcohol mixture is 
greater than that expected from the amount of alcohol added and the octane 
value of the gasoline taken separately. Consequently, those skilled in 
this art generally use the octane value, known as "blending octane value" 
or the average of research and motor octane (R+M)/2, to estimate the 
effect of alcohol on the gasoline base. For example, depending upon the 
octane values of the base gasoline, methanol/gasoline blends have been 
reported to be 2 to 3 Motor Octane Number and as high as 16 Research 
Octane Number above the reported values for the base gasoline. In any 
event, such finished methanol/gasoline fuels normally are 1.5 to 3 octane 
points (R+M)/2 higher than the base fuel itself. See for example, 
Eccleston, B. H. and Cox, F. W., PHYSICAL PROPERTIES OF GASOLINE/METHANOL 
MIXTURES, Bartlesville Energy Research Center, Bartlesville, Okla. (1977). 
Notwithstanding these antiknock benefits, methanol by itself is not widely 
used as a gasoline additive due to the number of serious technical and 
legal problems associated with its use. In the technical realm, the 
presence of even small amounts of water can cause serious operational 
problems. Methanol when used by itself (and to a lesser extent ethanol) 
tends to phase-separate from gasoline in the presence of water and/or when 
exposed to cold weather conditions. This tendency to phase-separate has 
been a major obstacle to the use of such alcohols as octane enhancers and 
gasoline extenders. Further, methanol, particularly when it has 
phase-separated from gasoline, is known to have harmful corrosive 
tendencies to certain fuel delivery and engine components. 
For these and other reasons, Section 211(f)(a) of the Clean Air Act, as 
amended (42 USC 7445), governs the usage and introduction of additives in 
unleaded gasolines and specifically provides that no fuel or fuel additive 
may be first introduced into commerce that is not "substantially similar" 
to any fuel or fuel additive used in the certification of any 1974 or 
later model year vehicle. In July 1981, EPA defined "substantially 
similar" to include fuels with up to 2.0 wt. percent oxygen. Ethers or 
alcohols (except methanol) are acceptable additives if they otherwise meet 
these oxygen limitations. Methanol can be used as a de-icer when used up 
to 0.3 volume percent or be used for this purpose up to 2.75 volume 
percent when introduced with an equal volume of butanol or a higher 
molecular weight alcohol. However, the fuel must conform to the 
characteristics of an unleaded gasoline as specified by ASTM D 439. This 
definition of "substantially similar" provides a general rule for the 
inclusion of oxygenates in unleaded gasolines. Methyl tertiary butyl ether 
(MTBE) qualifies under the general 2% oxygen rule. This is equivalent to 
about 11% MTBE by volume, depending on the specific gravity of the 
gasoline. 
The Clean Air Act under Section 211(f)(4) provides that the EPA 
Administrator may waive the prohibition on new fuels or fuel additives. 
However, prior to granting a waiver the Administrator must determine if 
the application meets the burden of demonstrating that the new fuel or 
fuel additive will not cause the failure of an emission control system or 
an emission standards(s). Under this section of the Act, the Administrator 
has both denied and granted several waiver requests. 
The EPA has denied all previous waiver requests involving MMT in unleaded 
gasoline. The EPA denied Ethyl Corporation's MMT waiver applications 
because Ethyl failed to demonstrate that MMT at its proposed concentration 
levels of 1/16, 1/32 and 1/64 gram per gallon of gasoline would not cause 
or ultimately cause unacceptable hydrocarbon emissions. See generally 
Environmental Protection Agency in RE Applications for MMT Waiver, Federal 
Register, Vol. 43, No. 181, Monday, Sep. 18, 1978, and Ethyl Corp; Denial 
of Application for Fuel Waiver; Summary of Decision, Federal Register, 
Vol. 46, No. 230, Tuesday, Dec. 1, 1981. 
The EPA has also denied several waiver requests for alcohol additives. 
However, on Sep. 23, 1981, Anafuel Unlimited was granted a waiver for a 
proprietary fuel called "Petrocoal" (see generally the Petrocoal Waiver 
and Supporting Docket EN 81-8). "Petrocoal" is a mixture of methanol and 
certain four-carbon alcohols in unleaded gasoline in the presence of a 
proprietary corrosion inhibitor. The fuel can contain up to 12 volume 
percent methanol and up to 15% total alcohols. The ratio of methanol to 
four-carbon alcohols cannot exceed 6.5 to 1. The fuel must meet ASTM D 439 
specifications. 
The EPA granted on Nov. 16, 1981 a request by ARCO for a waiver for 
mixtures of methanol and gasoline-grade tertiary butyl alcohol "GTBA" (see 
generally the Oxinal Waiver granted in the EPA and Supporting Docket 
EN-81-10). ARCO markets these mixtures under the name "Oxinol". The ratio 
of methanol to GTBA cannot exceed 1 to 1, and the concentration of oxygen 
in the finished fuel cannot exceed 3.5 weight percent. The 3.5% oxygen 
limit translates into about 9.6% by volume. The lower the methanol 
content, the greater the total alcohol volume allowable. At zero methanol 
content, the 3.5 weight percent oxygen is equivalent to about 16 volume 
percent GTBA. 
In 1979, EPA granted a waiver for "gasohol", which contains 10 volume 
percent ethanol (see generally the Gasohol Waiver). However, the general 
rule of 2 weight percent oxygen would limit ethanol to about 5.5 volume 
percent. This left an "illegal" limit between the 5.5 and 10 percent 
levels. In 1982, EPA interpreted the "gasohol" waiver to include any 
amount up to 10 volume percent anhydrous ethanol in unleaded gasoline. 
The above described legal limitations also follow from the physical 
properties of such alcohol gasoline compositions, e.g., vapor pressure, 
enleanment, and evaporative emissions which can be adversely affected by 
the presence of lower molecular weight alcohols such as methanol and 
ethanol. 
For example, methanol is 50 percent by weight oxygen. This leads to a 
potential problem known in the art as "enleanment". Fuel introduction and 
delivery systems (e.g., fuel injection systems, carburetors) are designed 
and adjusted to provide a predetermined stoichiometric amount (ratio) of 
air to fuel, and hence the amount of oxygen to fuel. In fuel carburetors 
and in cars without oxygen sensing devices this predetermined 
stoichiometric ratio is calculated without regard for gasolines containing 
oxygen. If a gasoline contains excessive concentrations of oxygenated 
components such as methanol, the air (oxygen) to fuel ratio is 
significantly changed from the predetermined ratio. Significant deviations 
from the predetermined ratio causes poor ignition and combustion 
properties of the fuel. A high air (oxygen) to fuel ratio produced in this 
manner will cause the engine to run lean. If an engine's air (oxygen) to 
fuel ratio becomes too high or lean, the engine will fail to start and/or 
continue to run. 
In effect, enleanment sets a technical limit on the total amount of any 
oxygenated component such as alcohol that can be incorporated into a 
gasoline without making major modifications to most fuel introduction and 
delivery systems. Moreover, higher air (oxygen) to fuel ratios also may 
contribute to the production of certain environmentally harmful nitrogen 
oxides. 
An attribute of enleanment which heretofore has not been distinguished by 
those skilled in the art is called "technical enleanment". "Technical 
enleanment" is that unexpected phenomena which exhibits symptoms of 
enleanment occurring when the total air (oxygen) content of the finished 
fuel is not stoichiometrically or chemically lean. Such behavior is very 
similar to enleanment and includes engine stalling, lack of power, poor 
combustion, difficult start-ups (especially warm start-ups) and other 
problems normally associated with oxygen containing fuels, including 
alcohol/gasoline fuels and combustion/fuel systems which are known to be 
chemically or stoichiometrically lean. The difference between chemical or 
stoichiometric enleanment and "technical enleanment" is that traditional 
chemical or stoichiometric enleanment can be predicted from a chemical 
and/or stoichiometric basis, whereas "technical enleanment" is not 
predictable on the same basis. 
Since the EPA has exclusive jurisdiction of unleaded gasoline additives, 
exhaust emissions are a major concern when incorporating alcohols into 
unleaded gasolines. Numerous studies on this subject, including prior EPA 
waiver applications for alcohol additives, exist in the literature. These 
studies generally show that carbon monoxide emissions are reduced, and 
that nitrogen oxide emissions are generally unchanged. Hydrocarbon 
emissions from such fuels generally vary. For example Appendix B of the 
EPA's Waiver for "Petrocoal" showed the fuel's hydrocarbon emissions to be 
unchanged, see Federal Register Vol. 46, No. 192, Monday, Oct. 5, 1981, 
Page 48978. However, in one of the more comprehensive studies on the 
subject prepared under the direction of the U.S. Energy Research and 
Development Administration, hydrocarbon emissions increased with the 
introduction of methanol. Hydrocarbon emissions increased further by 
increasing the methanol concentrations in the base gasoline. See J. R. 
Allsey, EXPERIMENTAL RESULTS USING METHANOL AND METHANOL/GASOLINE BLENDS 
AS AUTOMOTIVE ENGINE FUEL, Bartlesville Energy Research Center, 
Bartlesville, Okla. (1977). 
Therefore, in view of the federally mandated ban on methyl cyclopentadienyl 
manganese tricarbonyls (MMT), the phase-out of leaded gasolines, and in 
further view of the above noted technical and legal problems associated 
with gasoline/alcohol blends, there now exists a very pressing need to 
find new families of environmentally safe antiknock agents and/or learn to 
use known antiknock agents in ways which are technically and 
environmentally acceptable. Applicants believe that the latter course 
holds the best immediate promise. 
SUMMARY OF THE INVENTION 
Applicant believes that the unacceptable hydrocarbon emissions and other 
pollution problems associated with the use of cyclomatic manganese 
tricarbonyls such as MMT are directly traceable to the associative 
build-up of unoxidized or partially oxidized hydrocarbons and the oxide of 
manganese ("Mn.sub.3 0.sub.4 "). The oxide of manganese is the oxidation 
product of the cyclomatic manganese tricarbonyls. Although the exact 
chemical mechanism of this hydrocarbon/Mn.sub.3 0.sub.4 build-up is not 
fully understood, applicant believes that it begins with the formation of 
a hydrocarbon gum material ("HGM") comprised chiefly of unoxidized or 
partially oxidized hydrocarbons and Mn.sub.3 0.sub.4. It is believed that 
once formed, the HGM tends to attract other unoxidized or partially 
oxidized hydrocarbons and Mn.sub.3 0.sub.4 which together tend to plug 
catalysts, foul spark plugs and form combustion chamber deposits. It is 
also believed, especially when the quantities of MMT are in excess of 
about 1/16 g manganese per gallon, that the presence of HGM causes a 
certain type of Mn.sub.3 0.sub.4 deposit in the catalytic converter system 
which ultimately causes it to plug. 
In the first aspect of this invention, Applicant have discovered that 
certain beneficial chemical reaction(s) unexpectedly occur when 
organomanganese containing unleaded gasolines are combined with C.sub.1 to 
C.sub.6 aliphatic alcohols such that the resultant novel fuel composition 
can be made to meet current federal hydrocarbon emission standards of 0.41 
grams per mile. This novel fuel composition can become eligible for EPA 
waivers of the type noted above which heretofore have been denied due to 
potential catalyst plugging and excessive hydrocarbon emissions. The 
beneficial effect of this novel fuel is achieved by the use of certain 
well-defined proportions of C.sub.1 to C.sub.6 aliphatic alcohols, and 
well-defined proportions of cyclopentadienyl manganese tricarbonyl 
antiknock agents and nonleaded gasoline bases. 
In the second aspect of this invention, Applicant have further discovered 
that usage of the well-defined proportions of cyclopentadienyl manganese 
tricarbonyl antiknock agents in unleaded gasoline bases together with the 
well-defined proportions of C.sub.1 to C.sub.6 aliphatic alcohols and/or 
co-solvents in a manner more fully described below, unexpectedly 
alleviates and corrects the phenomena of "technical enleanment (T.E.)". 
No blending stabilizers (other than the disclosed cosolvents needed when 
methanol is employed) are required when these three ingredient categories 
are combined in applicants' defined proportions. Cosolvents are added when 
methanol is used to insure the phase stability of the fuel composition.

DETAILED DESCRIPTION OF THE INVENTION 
1. Defined Proportions of the Ingredients 
The defined range of proportions over which the gasoline bases, the C.sub.1 
to C.sub.6 aliphatic alcohol component, and the cyclopentadienyl manganese 
tricarbonyl component may be employed to reduce hydrocarbon emissions, and 
control technical enleanment are: 
______________________________________ 
TABLE OF INGREDIENT RANGES 
______________________________________ 
Unleaded base 95-99.9 92-95 70-92 
Gasoline (Vol. %) 
C.sub.1 to C.sub.6 aliphatic 
0.1-5.0 5.0-8.0 8.0-30.0 
alcohols 
(vol. %) 
O.sub.2 % by weight* 
0.05-2.4 0.7-3.8 1.2-14.2 
Methyl Cyclopentadienyl 
**-1.0 **-1 7/8 **-2.0 
manganese tri- 
carbonyl (MMT) 
(grams/manganese/ 
gallon 
______________________________________ 
*including cosolvents, if any. 
**1/1000 gram. 
Generally, within these ranges, the higher the total concentration of the 
lower molecular weight alcohols (particularly methanol, ethanol and 
propanol in order of their preference) the higher the preferred 
concentrations of manganese. With manganese concentrations of 1/8 gram in 
the fuel composition the beneficial EOHC effect generally does not begin 
to occur until approximately 2% by volume of the C.sub.1 to C.sub.6 
alcohol component is introduced into the fuel composition. 
It is recommended in normal cases that when methanol is used as the sole 
aliphatic alcohol without the benefit of any cosolvent(s) it should be 
limited to a concentration of about 5 volume percent or less of the fuel 
composition. 
However, in most cases when methanol is employed in concentrations ranging 
from about 1 to about 24 volume percent of the fuel composition, 
cosolvent(s) selected from the group consisting of C.sub.2 to C.sub.12 
aliphatic alcohols, C.sub.3 to C.sub.12 ketones and/or C.sub.2 to C.sub.12 
ethers in concentrations from about 1 to about 20 volume percent should 
also be employed. The combined methanol and cosolvent concentration 
should, however, not exceed 30 volume percent of the entire fuel 
composition. When the cosolvent alcohol(s) is selected from the group 
consisting of C.sub.2 to C.sub.8 aliphatic alcohols, the preferred 
aliphatic alcohol(s) are saturated aliphatic alcohol(s). 
In the practice of this invention, one or more C.sub.1 to C.sub.6 aliphatic 
alcohols, preferably, C.sub.1 to C.sub.6 saturated aliphatic alcohols, 
must be employed in the fuel composition. The alcohol component may be any 
individual alcohol or any combination thereof. Mixed alcohol combinations 
may be desirable for enhancing blending octane values and controlling RVP 
increases. It is contemplated in the practice of this invention that mixed 
alcohols produced from the modification of known methanol or other alcohol 
catalysts, use of alkali metal oxide catalysts, use of rhodium catalysts, 
isosynthesis using alkalized ThO.sub.2 catalysts, modified lurgi 
catalysts, and/or produced from certain isomerization/dehydrogenation 
processes, olefinic/hydration processes, "OXO" processes and the like, are 
acceptable. 
Alcohol mixtures, generally having methanol, ethanol, propanols, butanols, 
pentanols and hexanols in the composition; which by weight percent of the 
composition decline as the individual molecular weight of the alcohol 
increases, are desirable. An example of a mixed alcohol composition 
wherein the lower molecular weight alcohols have a higher relative 
proportion of the composition by volume percent than do the higher 
molecular alcohols include: methanol at approximately 50 weight percent of 
the alcohol component, ethanol at approximately 25 weight percent, 
propanols at approximately 13 weight percent, butanols at approximately 6 
weight percent, pentanols at approximately 3 weight percent, with hexanols 
and other higher alcohols generally representing the balance of the 
alcohol component. 
Another example of a desirable alcohol mixture would include a composition 
wherein the higher molecular weight alcohols have higher relative 
proportions by volume percent of the composition than do the lower 
molecular weight alcohols. Still another example would include a mixed 
alcohol composition wherein similar proportions of each alcohol exist by 
volume percent in the composition. Mixed alcohol compositions generally 
include methanol to higher alcohol ratios generally varying from about 4:1 
to 1:4 weight percent of the alcohol compositions. Those other 
combinations of alcohol mixtures which positively effect RVP, octane, 
distillation characteristics, end boiling point temperatures, and/or 
emissions are particularly desirable. 
Suitable alcohols for use include methanol, ethanol, N-propanol, 
isopropanol, N-butanol, secondary-butanol, isobutanol, tertiary butanol, 
pentanols, hexanols and the like. As noted in the Table of Ingredient 
Ranges, aliphatic alcohols in ranges from up to about 30.0% by volume with 
about up to 14.2% oxygen by weight give good hydrocarbon emission results 
when used in unleaded gasolines. One percent to five percent oxygen by 
weight in the fuel composition are, however, more preferred. The 
composition should have at least 0.001 grams manganese and generally no 
more than 2.0 grams manganese of a cyclomatic manganese tricarbonyl 
compound per gallon. Preferably, the alcohol employed should be anhydrous, 
but alcohols containing small amounts of water can also be used. Within 
the preferred concentration range most of the C.sub.1 to C.sub.6 aliphatic 
alcohols are completely miscible with petroleum hydrocarbons and it is 
preferred that such alcohols be used in amounts within their solubility 
limits. However, if desirable, an amount of alcohol in excess of its 
solubility can be incorporated in the fuel by such means, as for example, 
by use of mutual solvents. 
Desirable individual alcohol compositions would contain up to about 20 
volume percent methanol, or up to about 25 volume percent ethanol, or up 
to about 25 volume percent isopropanol, or up to about 25 volume percent 
normal propanol, or up to about 30 volume percent tertiary butanol, or up 
to about 30 volume percent secondary butanol, or up to about 30 volume 
percent isobutanol, or up to about 30 volume percent normal butanol, or up 
to about 30 volume percent pentanols, or up to about 30 volume percent 
hexanols, together with MMT as the cyclopentadienyl manganese in a 
concentration of about 0.001 grams to 2.0 gram of manganese per gallon of 
fuel composition. A more preferred manganese concentration is from about 
1/32 to about 1/8 gram of manganese per gallon of fuel composition. 
A desirable fuel composition contains methanol from about 1 to about 15 
volume percent of the composition, C.sub.2 to C.sub.8 aliphatic alcohols 
in concentrations from about 1 to about 15 volume percent of the 
composition and a preferred MMT concentration from about 0.001 to about 
1/4 gram of manganese per gallon of fuel composition and a more preferred 
MMT concentration from about 1/64 to 1/8 gram per gallon. 
A preferred fuel composition contains methanol from about 1 percent to 
about 9 volume percent of the composition, C.sub.2 to C.sub.8 aliphatic 
alcohols in concentrations from about 1 to about 10 volume percent of the 
composition, a MMT concentration from about 0.001 to about 1/4 gram 
manganese per gallon of fuel composition and a more preferred MMT 
concentration from about 1/64 to 1/8 gram per gallons. 
A more preferred fuel composition contains methanol from about 2 to about 6 
volume percent with C.sub.3 to C.sub.8 aliphatic alcohols in concentration 
from about 1 percent to about 10 volume percent of the composition and a 
MMT concentration from about 0.001 to about 1/4 gram manganese per gallon 
of fuel composition and a more preferred MMT concentration from about 1/64 
to 1/8 gram per gallon. 
An even more preferred fuel composition would contain methanol from about 2 
to 6 volume percent with C.sub.4 to C.sub.6 saturated aliphatic alcohols 
in concentrations from about 1 percent to about 10 volume percent of the 
composition, particularly those having boiling points higher than tertiary 
butanol and a MMT concentration from about 0.001 to about 1/4 gram 
manganese per gallon of fuel composition and a more preferred MMT 
concentration from about 1/64 to 1/8 gram per gallon. 
2. Correcting Technical Enleanment 
The second aspect of this invention involves controlling T.E. although the 
actual cause of "technical enleanment " ("T.E.") is not fully understood, 
Applicant has discovered that methanol and/or ethanol gasoline blends are 
particularly susceptible to technical enleanment T.E. symptoms are 
aggravated when the base fuel is highly volatile, low aromatic, high 
paraffin, and/or has a high mid-range boiling temperature. Applicant has 
discovered that technical enleanment symptoms of oxygenated fuels can be 
substantially alleviated or even corrected by the use of the above noted 
proportions of base gasolines, cyclopentadienyl manganese tricarbonyl 
antiknock compounds and the addition of aliphatic alcohols and/or 
cosolvent(s) in the manner described below. 
An unexpected synergism has been discovered when both MMT and the C.sub.1 
to C.sub.6 aliphatic alcohols, especially the higher boiling point 
alcohols, are used jointly to alleviate and correct the symptoms of T.E. 
Applicants are not entirely sure of MMT chemical mechanism. However, it is 
believed that MMT when in combination with the aliphatic alcohols tends to 
act as some sort of combustion catalyst improving the fuels ignition and 
combustion properties in such a manner as to alleviate T.E. symptoms. 
Another aspect which Applicant believes influences technical enleanment is 
the distillative nature of alcohol/gasoline fuels themselves. Lower 
boiling point oxygenates, including alcohols tend to form azetropes with 
the lower boiling gasoline components and depress the temperatures at 
which the initial and middle fuel fractions distill. The applicant 
believes that in certain cases this depression or displacement becomes so 
aggravated as to become a principal factor in T.E. 
FIG. 1 illustrates the improved technical enleanment aspects achieved by 
this invention. Referring now to FIG. 1, line 10 represents the volume 
percent of distillate recovered as temperature increases for a base 
nonleaded fuel. Line 12 represents the volume percent of distillate 
recovered as temperature increases for a base nonleaded fuel with 6% 
methanol and 4% ethanol by volume percent (4.4% O.sub.2 by weight), which 
may be referred to herein as "uncorrected fuel". Line 14 represents the 
volume percent of distillate recovered as temperature increases for a base 
nonleaded fuel with 1/2 gram of MMT/gallon, 6% methanol and 6% ethanol by 
volume percent (4.3% O.sub.2 by weight), which may be referred to herein 
as "corrected fuel". Specifically, the tendency of the methanol and/or 
ethanol gasoline blends of this invention to fall into the region 16 
"TECHNICAL ENLEANMENT REGION". FIG. 1 also shows the distillation curve of 
a base gasoline (the "Base Fuel") with a high mid-range boiling point. It 
also shows the base gasoline in combination with a 6 volume percent 
methanol and 4 volume percent ethanol mixture, the "Uncorrected Fuel". 
Note, that the Uncorrected Fuel mixture having an oxygen content of 
approximately 4.4 percent by weight intrudes into the TECHNICAL ENLEANMENT 
REGION due to the aggravated displacement of the lower and mid-range areas 
of the distillation curve. This intrusion is typical of many methanol 
and/or ethanol gasoline mixtures. FIG. 1 illustrates the effect of the 
"Corrected Fuel" by having an oxygen content of approximately 4.3 percent 
by weight and prepared by adding an 1/8 gram manganese of MMT and changing 
the cosolvent from 4 volume percent ethanol to 6 volume percent normal 
butanol. Note that the Corrected Fuel's distillation curve is above the 
TECHNICAL ENLEANMENT REGION. This example is illustrative of the improved 
technical enleanment characteristics of oxygen containing fuel 
compositions of the second of aspect of this invention. Naturally, the 
various compositions disclosed in this invention do not possess exactly 
identical effectiveness, and the most advantageous concentration for each 
such compound will depend to a large extent upon the particular alcohol or 
cosolvent used and will also depend to some extent upon the composition of 
the base gasoline itself. 
By correcting the aggravated displacement in the distillation curve as 
presented in FIG. 1 with the inclusion of MMT and the higher boiling point 
alcohols (cosolvents) in accordance with the Applicant's described 
construction, Applicant has discovered a control for T.E. The combined 
usage of MMT, C.sub.1 -C.sub.6 alcohols or cosolvents, exhibits a 
particularly ameleorative synergism effectively controlling T.E. symptoms, 
when constructed to have a distillation fraction above the T.E. region of 
FIG. 1. 
This departure from the prior art understanding of enleanment behavior is 
important to the whole enleanment issue. This is due principally to the 
fact that certain oxygenates, such as methanol and/or ethanol mixtures 
normally are more likely to distill out of the gasoline system together 
with other lower boiling point gasoline substituents where azetropes are 
formed prior to the distillation of the other components of the gasoline. 
The early distillation of these oxygenated components means that the 
oxygen in the fuel is being distilled off at lower temperatures in the 
initial and/or middle fractions of the gasoline and not over the fuels 
entire volatility range which often results in poor combustion and 
symptoms of enleanment. 
With the second aspect of Applicant invention, Applicants can effectively 
improve combustion efficiency and spread the volatility of oxygenated 
mixtures to match the volatility of the hydrocarbons; thereby correcting 
technical enleanment and permitting greater concentrations of total oxygen 
to be present in the fuel mixture than heretofore would have been 
considered practical to those skilled in the art. This represents a 
significant departure from the prior art. In view of the prior art 
literature this is quite unexpected and novel. 
3. Reduction of Engine Out Hydrocarbons (EOHC) 
Applicants have discovered that those MMT concentrations that heretofore 
have been considered excessive for reasons associated with unacceptable 
EOHC emissions and possible catalyst plugging, when combined with the 
aliphatic alcohols, and unleaded gasoline bases in accordance with 
Applicant's noted proportions and construction, tend to prevent 
unacceptable EOHC emissions and prevent catalyst plugging. In view of the 
extensive prior art literature on the subject, this result is also quite 
unexpected. 
The beneficial hydrocarbon emission effects are best illustrated in FIG. 2. 
FIG. 2 illustrates the 17A, 17B and 17C low, medium and high ranges, 
respectively, of hydrocarbon emissions improvement expected at 5,000 miles 
using the defined proportions of C.sub.1 to C.sub.6 aliphatic alcohols 
(cosolvents), MMT and unleaded base gasolines (the "Corrected Fuels"), 
i.e., nonleaded fuels containing MMT with C1 to C6 aliphatic alcohols, 
including co-solvents, in accordance with applicant's defined proportions, 
over 18 A. 18B and 18C low, medium and hi ranges, respectively, of fuels 
just employing MMT concentrations without the benefit of C.sub.1 to 
C.sub.6 aliphatic alcohols (the "Uncorrected Fuels"). The 5,000 mile mark 
reflects the critical point where the initial assent in hydrocarbon 
emissions is typically experienced in MMT containing nonleaded fuels. The 
effect of methanol and its associated cosolvents, including ethers and 
ketones, are incorporated in FIG. 2. FIG. 2 illustrates the significant 
differences in the hydrocarbon emission behavior of pre-1980 standard 
model cars (manufactured for under 1.5 grams of hydrocarbon emission per 
mile standards) using the Uncorrected Fuel and the Corrected Fuel 
formulated in accordance with Applicant's invention. 
The methyl cyclomatic manganese tricarbonyls used in our compositions can 
contain such homologes or substituents as, for example, alkenyl, aralkyl, 
aralkenyl, cycloalkyi, cycloalkenyl, aryl and alkenyl groups. 
Illustrative, but nonlimiting examples of such substituted and 
unsubstituted cyclomatic manganese tricarbonyl antiknock compounds are: 
cyclopentadienyl manganese tricarbonyl; methylcyclopentadienyl manganese 
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-propyfluorenyl manganese tricarbonyl; 
3-naphthylfluorenyl manganese tricarbonyl; 4,5,6,7-tetrahydroindenyl 
manganese tricarbonyl; 3-ethenyl-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 generally be prepared by methods which are known in the art. 
Representative preparative methods are described, for example, in U.S. 
Pat. Nos. 2,818,416 and 2,818,417. 
Since the oxidation product of the above methyl cyclomatic manganese 
tricarbonyls, i.e., Mn.sub.3 O.sub.4, plays a leading role in HGM 
build-up, it is desirable to use as little of these methyl cyclomatic 
manganese tricarbonyl compounds as is necessary in order to maximize the 
HGM inhibition benefits of the invention. As seen in the Table of 
Ingredient Concentrations, concentrations of the methyl cyclomatic 
manganese tricarbonyl compound concentrations (expressed as grams of 
manganese metal per gallon of the resulting fuel composition) as low as 
0.001 gram per gallon may be used. However, concentrations up to and 
including 2.0 grams manganese per gallon can be employed, but are less 
preferred. On occasion, amounts above the recited range can also be 
employed, but such concentrations tend to be less satisfactory. 
In terms of economic octane benefits, concentrations in the range of from 
about 0.001 to about 2.0 grams manganese per gallon give good results, 
concentrations from about 0.001 gram to 1/2 gram give better results, and 
concentrations from about 1/64-1/8 gram/gallon give excellent results and 
are more preferred. This invention also contemplates the use of other 
additives, such as multipurpose additives. Nonlimiting examples include 
scavengers, made necessary or desirable to maintain fuel system 
cleanliness and control exhaust emissions due to the presence of the 
organo-manganese compound in the fuel. 
4. Using Cosolvents 
When methanol is used as the aliphatic alcohol of choice, it is desirable 
that a cosolvent should also be employed to insure phase stability of the 
fuel composition to the extent that the fuel composition containing 
methanol and approximately 500 parts per million water will not phase 
separate at 15.degree. F., or the lowest temperature to which the fuel 
composition will be exposed. Generally speaking the methanol to cosolvent 
ratio should not exceed about 5 parts methanol to 1 part cosolvent 
depending upon the nature of the base fuel and the cosolvent(s) used. 
The cosolvent(s) can be selected from the group consisting of C.sub.2 to 
C.sub.12 aliphatic alcohols, C.sub.3 to C.sub.12 ketones and/or C.sub.2 to 
C.sub.12 ethers. Within the scope of this invention it is contemplated 
that these cosolvents may also be used with any C.sub.1 -C.sub.6 aliphatic 
alcohol, especially in cases where corrosion, phase stability or vapor 
pressure become an issue. It is also within the scope and teaching of this 
invention to employ one or more alcohols, ketones or ethers as cosolvents 
or any one, two or all three cosolvents classes of this invention 
simultaneously. 
It is further contemplated, within the scope of this invention, in cases 
where vapor pressure or evaporative emissions are a concern, especially 
when C.sub.1 to C.sub.3 molecular weight alcohols are used individually or 
in combination, to employ C.sub.2 to C.sub.7 ethers individually or in 
combination with each other with or without other cosolvents. 
It is also within the scope and practice of this invention to use mixed 
cosolvents, including mixed alcohols, ethers and/or ketones as cosolvents. 
It has been found that mixed cosolvent alcohols particularly those in the 
C.sub.2 to C.sub.8 range have an ameleorative effect on both RVP and 
octane blending values. 
In accordance with the discussion of cosolvents within this invention with 
regard to phase stability, the preferred cosolvent class rankings would be 
alcohols first, ketones second, and ethers last. Also, the higher the 
average boiling point of the cosolvents employed within a particular 
class, up to a C.sub.8 cosolvent, the greater the preference. With 
cosolvents greater than C.sub.8 the reference is reversed so that a 
C.sub.9 cosolvent would be preferred over a C.sub.10 cosolvent and so 
forth. 
Within the sub-categories of the particular cosolvent class, after 
preference is given to the alcohol, ketone and ether ranking, and after 
preference is given to the average boiling point characteristics, then 
preference would be given the branched chain molecules over straight or 
cyclical chained molecules. 
The alcohol cosolvents will have from two to twelve carbon atoms. The 
preferred cosolvent alcohols are saturates having high water tolerances 
and high boiling points. Representative alcohol cosolvents include 
ethanol, isopropanol, n-propanol, tertiary butanol, 2-butanol, isobutanol, 
n-butanol, pentanols, amyl alcohol, cyclohexanol, 2-ethylhexanol, furfuryl 
alcohol, iso amyl alcohol, methyl amyl alcohol, tetrahydrofurfuryl 
alcohol, hexanols, cyclohexanols, furons, septanols, octanols and the 
like. The alcohol cosolvents, in reverse order of their preference, are 
propanols, butanols, pentanols, hexanols and the other higher boiling 
point alcohols. The more preferred alcohol cosolvents include isobutanol, 
n-butanol, pentanol and the other higher boiling point alcohols. 
The ketones used as cosolvents in fuel compositions taught herein will have 
from three to about twelve carbon atoms. Lower alkenyl ketones are, 
however, slightly preferred. Representative lower alkenyl ketones would 
include diethyl ketone, methyl ethyl ketone, cyclohexanone, 
cyclopentanone, methyl isobutyl ketone, ethyl butyl ketone, butyl isobutyl 
ketone and 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. 
Representative ethers which can be used as cosolvents in fuel compositions 
taught herein will have from 2 to about 12 carbon atoms and would include 
the preferred methyl alkyl t-butyl ethers such as methyl tert-butyl ether, 
ethyl tertiary butyl ether, also preferred tertiary amyl methyl ether, 
dialkyl ether, isopropyl ether, di methyl ether, diisopropyl ether, 
diethyl ether, ethyl n-butyl ether, ethylilenedimethyl ether, butyl ether, 
and ethylene glycol dibutyl ether and the like. The representative 
straight ethers which can be used in the fuel blends of this invention 
would include straight chain ethers such as those presented above, as well 
as cyclic ethers wherein the ether's oxygen molecule is in a ring with 
carbon atoms. For example, 4,4-dimethyl-1,3-dioxane, tetrahydrofurans, 
such as, for example, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, and 
3-methyletetrahydrofuran may also find use in the present invention. The 
most preferred ether would be a branch chained ether. In order to be most 
advantageously employed, the above ethers should also be readily soluble, 
either directly or indirectly in the gasoline. 
Generally, the preferred methanol/cosolvent ratio will range from 0.5 to 3 
parts methanol to 1 part cosolvent. Ratios from about 3 to 5 parts 
methanol to 1 part cosolvent are also preferred in certain circumstances. 
The ratio of methanol to cosolvent can exceed 5 to 1 or be less than 0.5 
to 1. However methanol/cosolvent ratios outside these ranges are normally 
less desirable unless vapor pressure or technical enleanment are issues in 
the fuel formulation. The methanol to cosolvent ratios will generally be 
higher when a higher boiling point aliphatic alcohol up to C8 is the 
cosolvent and lowest when ethanol is the cosolvent. In the same sense 
methanol to cosolvent ratios are higher with alcohols, than they are with 
ketones, than they are with ethers. That is to say, when a comparable 
higher boiling point or molecular weight alcohol, ketone or ether is 
compared, the highest ratio (within the general range of 3 to 5 parts 
methanol to 1 part cosolvent) is permissible when the cosolvent is an 
alcohol, the second highest ratio when the cosolvent is an alcohol, the 
second highest ratio when the cosolvent is the ketone and the lowest ratio 
when the cosolvent is an ether. 
For example, in comparing normal-butanol, CH.sub.3 (CH.sub.2).sub.2 
CH.sub.2 OH; diethyl ether, C.sub.2 H.sub.5).sub.2 O; and methyl ethyl 
ketone CH.sub.3 CO CH.sub.2 CH.sub.3 ; the preferred ratios might be 3 to 
5 parts methanol to 1 part N-butanol, 1 to 2 parts methanol to 1 part 
methyl ethyl ketone, and 1 part methanol to 2 to 3 parts diethyl ether. 
Within each of these cosolvent groups, the methanol-cosolvent ratios 
should be at their highest when higher molecular weight molecules (e.g., 
C.sub.4 -C.sub.12) are used. 
It is also within the scope and practice of this invention to utilize 
individual and/or different molecular weight cosolvent mixtures, higher 
alcohol mixtures (especially C.sub.4 -C.sub.12 in varying combinations and 
concentration) together with aromatic hydrocarbons as a means of 
controlling RVP and technical enleanment. 
5. Formulating the C.sub.1 -C.sub.6 Aliphatic Alcohol and/or Cosolvent 
Component 
In formulating the desired alcohol or cosolvent components and determining 
the preferred ratio of methanol to cosolvent(s) the following factors 
should be taken into consideration: 
(1) The base gasoline composition. 
(2) The distribution system which the finished fuel will be exposed to. 
(3) The average age of the vehicular population consuming the fuel. 
(4) The fuel's propensity towards technical enleanment. 
(5) The fuel's effect on EOHC. 
Generally the more desirable the base fuel composition as described 
hereafter, the less restrictive the formulation and construction of the 
C.sub.1 to C.sub.6 aliphatic alcohol or cosolvent component. The more 
desirable the base gasoline, the lower can be the average boiling point of 
the alcohol or cosolvent component. The more desirable the base gasoline 
the greater the permissible percentage oxygen by weight that can be 
contained in the finished fuel. For example, the more desirable the base 
gasoline the greater the flexibility in reducing or increasing the total 
percent alcohol or cosolvent by volume in the finished fuel. 
For example, the higher the aromatic content of the base gasoline the 
higher the permissible methanol to cosolvent ratio, and the lower the 
required average boiling point of the alcohol or cosolvent component. 
Inversely, a less desirable base gasoline with lower percentages of 
aromatic components generally will require a lower methanol to cosolvent 
ratio and a higher average boiling point alcohol or cosolvent component. 
This same low aromatic gasoline will limit the flexibility of reducing or 
increasing the total volume of the alcohol component. It is likely that 
the alcohol component as a percent of volume would be easier to increase 
then it would be to decrease. 
As discussed above azetropic relationships aggravate the alcohol or 
cosolvent component configurations as well. Particular attention must be 
given to the characteristics of technical enleanment. Generally in 
gasolines with higher mid-range volatility and/or higher paraffinic 
content, the methanol to cosolvent ratios are lower, sometimes less than 
1. In these cases the required average boiling point of the alcohol 
(cosolvent) component is normally higher, and the flexibility of either 
increasing or reducing the total alcohol or cosolvent component is 
restricted. The permissible oxygen content is normally reduced and in some 
severe cases it should not exceed 2.5% by weight. In these base gasolines 
it is important to construct the alcohol or cosolvent component so as to 
prevent any significant displacement of the lower and particularly the 
mid-range gasoline fractions during distillation. It is desirable to 
construct the alcohols or cosolvent's volatility (distillation) to match 
the hydrocarbons volatility as closely as possible to cover the largest 
portion of the distillation curve. 
In addition to considering the base gasoline to which the alcohol or 
cosolvent component is added, consideration must also be given to the fuel 
distribution system to which the finished fuel will be exposed. The 
greater the likelihood of significant exposure to moisture, temperature 
variations and cold weather conditions, the more restrictive will be the 
alcohol or cosolvent component construction and the higher should be the 
total alcohol percent volume and the lower the alcohol cosolvent ratio 
which is contained in the fuel. 
For example, a methanol to cosolvent ratio of 3 to 1 using isopropanol as 
the cosolvent, together with the alcohols representing 7 percent by volume 
of the fuel, would normally be acceptable if the fuel were to be 
distributed in a dry system averaging 60.degree. F. However, if it were 
anticipated that the fuel would be exposed to 20.degree. F. temperatures, 
or to greater concentrations of moisture or water, then certain 
adjustments would have to be made. One or more of the following 
adjustments would be required: 
(a) The methanol to cosolvent ratios would be reduced to 2 to 1, or 1 to 1, 
increasing the average weight of the combined alcohol (cosolvents) 
component. 
(b) The cosolvent would be changed from isopropanol to a butanol or higher 
boiling point alcohols. 
(c) The volume of alcohols (cosolvents) would be increased from 7 percent 
to 12 percent. 
The age of the vehicular population which consumes the finished fuel also 
impacts the amount of oxygen which may be contained in the fuel. In the 
case of older automobiles the finished fuel may contain upwards to 5-7 
percent total oxygen by weight. Those newer automobiles using 3-way 
catalysts which require more stringent air fuel ratios are limited to 
generally 4-5 percent total oxygen by weight. New vehicles containing 
oxygen sensing devices may use fuels containing upwards of 7 percent 
oxygen by weight. With the anticipated improvements of oxygen sensing 
devices in 1985 and future model years, the oxygen content of the finished 
fuel could approach 12 percent or more by weight. 
In an effort to minimize the effect of EOHC and increase the anti-knock 
concentrations of MMT one should employ the maximum concentrations 
possible of C.sub.1 to C.sub.3 alcohols. The highest preference is given 
to methanol, the second to ethanol and the third to propanol. 
6. Unleaded Base Gasoline Composition 
The nonleaded or unleaded gasoline bases in Applicants'fuel composition are 
conventional motor fuel distillates boiling in the general range of about 
70.degree. to 480.degree. F. They include substantially all grades of 
unleaded gasoline presently being employed in spark ignition internal 
combustion engines. Generally they contain both straight runs and cracked 
stock, with or without alkylated hydrocarbons, reformed hydrocarbons and 
the like. Such gasolines can be prepared from saturated hydrocarbons, 
e.g., straight stocks, alkylation products and the like, with detergents, 
antioxidants, dispersants, metal deactivators, rust inhibitors, 
multi-functional additives, demulsifiers, fluidizer oils, anti-icing, 
combustion catalysts, corrosion inhibitors, emulsifiers, surfactants, 
solvents or other similar and known additives. It is contemplated that in 
certain circumstances these additives may be included in concentrations 
above normal levels. 
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 C.sub.4 
olefins and 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. Deyhydrogenation 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 reformated 
contain saturated components. Preferred gasoline bases are those having an 
octane rating of (R+M)/2 ranging from 78-95. It is desirable to blend the 
gasoline base so that the minimum aromatic content is no less than 15% and 
preferably greater than 20%. The gasoline base should have an olefinic 
content ranging from 1% to 30%, 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 have initial boiling points ranging from about 
70.degree. F. to about 115.degree. F. and final boiling points ranging 
from about 380.degree. F. to about 480.degree. F. as measured by the 
standard ASTM distillation procedure (ASTM D-86). Intermediate gasoline 
fractions boil away at temperatures within these extremes. 
Table 1 illustrates the hydrocarbon-type makeup of a number of preferred 
fuels which can be used in this invention. 
TABLE I 
______________________________________ 
Hydrocarbon Blends of Preferred Base 
Fuels--Volume Percentage 
Fuel Aromatics Olefins Saturates 
______________________________________ 
A 35.0 12.0 73.0 
B 40.0 11.5 48.5 
C 20.0 22.5 57.5 
D 33.5 10.0 55.5 
E 36.5 5.0 58.5 
F 43.5 21.5 35.0 
G 49.5 2.5 48.0 
______________________________________ 
In terms of phase stability and water tolerance, desirable base gasoline 
compositions would include as many aromatics with C.sub.8 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 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 about 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. Nonlimiting examples include 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, Calif., May 14, 1971. 
The gasoline bases which this invention employs should be lead-free or 
substantially lead-free. However, the gasoline may 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. On certain occasions it will be 
desirable for the gasoline to contain supplemental valve and valve seat 
recession protectants. Nonlimiting examples include; boron oxides, bismuth 
oxides, ceramic bonded CaF.sub.2, iron phosphate, tricresylphosphate, 
phosphorus and sodium based additives and the like. The fuel may further 
contain antioxidants such as 2,6 di-tert-butylephenol, 
2,6-di-tert-buyl-p-cresol, phenylenediamines such as N-N.sup.1 
-di-sec-butyl-p-pheylenediamine, N-isopropylphenylenediamine, and the 
like. Likewise, the gasoline may contain dyes, metal deactivators, or 
other additives recognized to serve some useful purpose. The descriptive 
characteristics of one common base gasoline is given as example 2. 
Obviously many other standard and specialized gasolines can be used in 
Applicants'fuel blend. 
______________________________________ 
CHARACTERISTICS OF BASE GASOLINE 
______________________________________ 
Reid Vapor Pressure, psi 
7.2 
API Gravity @ 60 F. 
64.4 
______________________________________ 
ASTM Distillation 
Vol % Evaporate Temp., F. 
______________________________________ 
IBP 86* 
5 115 
10 132 
15 145 
20 157 
30 178 
40 197 
50 213 
60 229 
70 250 
80 286 
90 353 
95 391 
EP 428 
Lead Content, g/gal 
0.005 (or less 
and preferably 
none) 
Sulfur Content, wt % 
0.04 
Research Octane Number 
91.5 
Motor Octane Number 
83.9 
______________________________________ 
Component Vol. 
______________________________________ 
Paraffins 59.03 
Olefins 5.01 
Naphthenes 6.63 
Aromatics 29.33 
Average Molecular Weight 
101.3 
______________________________________ 
It is contemplated that the fuel composition of this invention may be used 
in spark-ignited internal combustion engines which operate on speciality 
oils which are formulated to suit the general combustion and other 
characteristics of the fuel. The fuel composition of this invention can 
generally be prepared by adding the cyclopentadienyl manganese antiknock 
compound, the C.sub.1 to C.sub.6 alcohols and/or the cosolvents, if any, 
to the base gasoline with sufficient agitation to give a uniform 
composition to the finished fuel. It is essential in the practice of this 
invention only that the novel combination of additives, a cyclopentadienyl 
manganese tricarbonyl and the C.sub.1 to C.sub.6 alcohols and/or cosolvent 
be present in the defined-proportions with unleaded gasoline bases 
immediately prior to vaporization and combustion of the fuel in the 
engine. Accordingly, it is within the scope of this invention to add the 
components to the base fuel either separately in any sequence, or as a 
mixture with each other, so long as the foregoing requirement is met. 
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.