Note: Descriptions are shown in the official language in which they were submitted.
FA 4~ ~ ~2~777~
A FUEL ADDITIVE FOR USE
IN ALCOHOL FUELS
The present invention is directed to a method for
inhibiting corrosion and elastomer swellirlg and
degradation caused by alcohol or alcohol-cor,taining
fuels, and for increasing lubricity of alcohol or
alcohol-containing fuels. The present invention is
also directed to alcohol and alcohol-containing fuel
compositions containing said fuel additive and charac-
terized by improved corrosion inhibition, elastomer-
swelling and degradation inhibition, and increased
io lubricity.
Alcohol fuels and alcohol-containing fuels, such as
alcohol-gasoline fuel blends, possess a much higher
degree of corrcsive activity than non-alcohol fuels,
such as gasoline, the individual hydrocarbon compo-
nents of gasoline, and dimethoxymethane (commonly
known as methylal). The high corrosive activity is
generally attributed to the presence of acidic and
halogen ion containing contaminants present in
20 alcohols but not present in the non-alcohol fuels
identified above.
The metal alloys, protective coatings and elastomers
used in constructing automotive components and
25 gasoline fuel dispensing systems have traditionally
been selected and developed specifically for chemical
compatibility with gasoline and the individual hydro-
carbon components of gasoline. The contaminants
A-40488/DED
77~
present in alcohols are particularly destructive to
various non-ferrous metals and metal coatinys, such as
lead-tin alloys (i.e., lead-terneplate alloys) used to
coat the internal surfaces of steel fuel tanks and
fuel lines, and to zinc or aluminum alloys used in
carburetor construction. AS a result, motor vehicles
using alcohol or alcohol-containing fuels have shown a
greater propensity toward corrosion in the fuel tank,
fuel line and fuel dispensing system areas.
The corrosive failure of the metal alloys and protec-
tive coatings used in constructing the automotive
components increases proportionately to the percentage
increase of alcohol in the fuel. Thus, some corrosion
protection is required whenever alcohol or alcohol-con-
taining fuels are used in an internal combustion
engine. The relative corrosivity of the alcohols is
inversely proportional to their polarities expressed
in units of dielectric constant. The dielectric
constant of alcohols having 1 to 4 carbon atoms,
gasoline and dimethoxymethane are shown in TABLE 1.
TABLE 1
DIELECTRIC CONSTANT OF ALCOHOLS AND GASOLINE
DIELECTRIC CONSTANT,
ALCOHOL at 25C
methanol 32.6
ethanol 24.3
n-propanol 20.1
iso-propanol 18.3
n-butanol 17.8
iso-butanol 17.7
tert-butanol 17.0
sec-butanol 10.9
dimethoxymethane 10.0
gasoline 2.0
i7~
The quantity and efficiency of a corrosion inhibitor
necessary to provide adequate protection to the metal
alloy automotive parts is directly proportional to the
amount of alcohol in the fuel and inversely propor-
tional to the polarity of the alcohol expressed inunits of dielectric constant.
Because the alcohols in Table 1 are more polar than
gasoline, many of the elastomers traditionally used to
construct automotive components in internal combustion
engines are not chemically compatible with alcohol
fuels or alcohol-containing fuels containing larger
amounts of alcohol. The degree of elastomer swelling
and degradation is directly proportional to the
alcohol's polarity expressed in units of dielectric
strength in Table 1. In general, alcohols with higher
polarity or dielectric strengths are good solvents for
the elastomers and cause attendant elastomer swelling
and degradation. B~cause methanol has the highest
polarity of the alcohols in Table 1, methanol or
methanol-containing fuels are the least compatible
with the elastomers normally present in a gasoline
burning internal combustion engine.
Some common elastomer failures are caused by the
swelling of the elastomer known as Vitonl~ used in
critical carburetor components, the hardening and
cracking of the elastomer known as Buna-N~ used in
fuel pump diaphragms, the hardening of neoprene-coated
diaphragms, the shrinking of cork gaskets, the disin-
tegration of polyurethane components, the hardening of
vinyl fuel hoses, and the delamination of polyester-
laminated fiberglass used in some vehicle fuel tanks
and many underground fuel storage tanks.
Alcohol fuels and alcohol-containing fuels, particu-
larly methanol fuels, are "dry" fuels and do not
display the oiliness characteristic of gasoline. As a
~.:2S777~
_4_
consequence metal-to-metal wear in alcohol fuels or
alcohol-containing fuels is significantly gre~ter than
in gasoline fuels. To counteract this deficiency,
alcohol fuels and particularly methanol fuels should
contain a lubricity additive. Alcohol-gasoline blends
containing low alcohol contents usually do not require
lubricity additives. However, as the alcohol content
of the fuel increases, the need for additional lubric-
ity protection increases. This is particularly true
during cold weather and Arctic operating conditions.
Some known corrosion inhibitors for use in alcohol or
alcohol-containing hydrocarbon fuels have been dis-
closed in U.S. Patent Nos. 4,282,007~ 4,28~2,008, and
4,376,635, and in European Patent~ Application No.
0086049. U.S. Patent No. 4,282,007 discloses an
anti-corrosion fuel additive comprising the reaction
product of aminotriazoles and polyisobutenyl succinic
acid anhydride. U.S. Patent No. 4,282,008 discloses
an anti-corrosion fuel additive comprising the reac-
tion products of aminotriazole, isatoic anhydride and
N-alkylpropylene diamine. U.S. Patent No. 4,376,635
discloses an anti-corrosion fuel additive comprising a
reaction product of a benzotriazole, an aldehyde or a
ketone, and a C3-C12 poly-primary amine bearing at
least one free -NH2 group and at least one NHR' group
wherein R' is a C12-C18 hydrocarbon group.
P~bQ;~c~
European Patent~Application No. 0086049 discloses a
corrosion inhibiting fuel additive comprising a
reaction product of at least one succinic acylating
agent selected from the group consistinc~ of unsubsti-
tuted and aliphatic hydrocarbon bascd substituted
succinic acylating agents, and at least one amine of
the formula
Rl \
N-~3
R2
-` ~25~
~5--
wherein Rl is a hydrocarbon based radical and R2 and
R3 are independently hydrogen or hydrocarbon based
radicals with the proviso that when R2 and R3 are both
hydrogen, Rl is a hydrocarbon based radical selected
from the group consisting of tertiaryalkyl, cycloyal-
kyl, aryl, alkaryl and aralkyl radicals.
It is an object of the present invention to provide a
method for inhibiting corrosion of metals and metal
coatings and the swelling and degradation of elasto-
mers in an internal combustion engine caused by
alcohol or alcohol-containing fuels and for increasing
the lubricity of alcohol or alcohol-containing fuels.
It is another object of the present invention to
provide an alcohol or alcohol-containing fuel composi-
tion containing said fuel additive and characterized
by corrosion inhibition, elastomer swelling and
degradation inhibition, and increased lubricity.
It is another object of the present invention to
provide a method for inhibiting corrosion and
elastomer swelling and degradation caused b~ alcohol
or alcohol-containing fuels and for increasing
lubricity of alcohol or alcohol-containing fuels, such
that the alcohol or alcohol-containing fuel will be
compatible with the materials of construction commonly
used in the petrochemical industry for tankers,
pipelines, metal and fiberglass storage tan~s, service
station storage tanks, fuel lines and fuel pumps.
In general, the present invention provides a method
for inhibiting corrosion and elastomer swelling and
degradation caused by alcohol or alcohol-containing
35 fuels and for increasing lubricity of alcohol or
alcohol-containing fuels, comprising the step of
adding to alcohol or alcohol-containing fuels a fuel
additive comprising: a reaction product of a) a
~25777Z
--6--
carboxylic acid or acid chloride selected from the
group consisting of unsubstituted aromatic carboY.ylic
acids, aliphatic carboxylic acids, nitro-substituted
aromatic carboxylic acids, and their corresponding
acid chlorides; and b) an amine selected from the
group consisting of aliphatic amines, cycloaliphatic
amines and aromatic amines. Preferred carboxylic
acids or their corresponding acid chlorides are
nitro-substituted aromatic carboxylic acids or acid
chlorides. Preferred amines are aliphatic amines.
The most preferred reaction product is meta-nitro-
benzoctadecylamide.
Tne present invention also provides a fuel composition
for use in internal combustion engines comprising a3 a
major portion of a fuel comprising from about 1 to
100% by volume of an alcohol having 1 to 4 carbon
atoms and from about 99 to 0% by volume of gasoline,
individual hydrocarbon gasoline components, or dimeth-
oxymethane, and b) a minor portion of the fuel addi-
tive generally described above.
The fuel additives comprising one aspect of this
invention are prepared by the reaction of a carboxylic
acid or acid chloride selected from the group consist-
ing of unsubstituted aromatic carboxylic acids,
aliphatic carboxylic acids, nitro-substituted aromatic
carboxylic acids and their corresponding acid chlor-
ides, and an amine selected from the group consisting
of aliphatic amines, cycloaliphatic amines, and
aromatic amines to form an amide as shown in equations
1 and 2 below.
COOH CONHR
~ + RNH2 ~ ~ + H20 ( 1 )
COCl CONHR
N 2 ~ ~ + HCl (2)
~ ~25~7~7~
_ 7 _ 73321-1
Preferred unsubstituted aromatic carboxylic acids or acid
chlorides are benzoic acid, ortho-toluic acid, para-toluic acid,
phthalic acid and -their corresponding acid chlorides. Preferred
aliphatic carboxylic acids or acid chlorides are aliphatic car-
boxylic acids having more than 12 and less than 30 carbon atoms
and their corresponding acid chlorides. A more preferred alipha-
tic carboxylic acid or acid chloride is octa-decylcarboxylic acid
or acid chloride.
Preferred nitro-substituted aromatic carboxylic acids or
acid chlorides are ortho-nitrobenzoic acid, meta-nitrobenzoic
acid, para-nitrobenzoic acid, orthopara-dinitrophenyl acetic acid,
3,5,6-trinitrosalicylic acid, and their corresponding acid chlor-
ides. More preferred nitro-substituted carboxylic acids or acid
chlorides are ortho-nitrobenzoic acid, meta-nitrobenzoic acid,
para-nitrobenzoic acid, and their corresponding acid chlorides.
The most preferred nitro-substituted carboxylic acid or acid
chloride is meta-nitrobenzoic acid or acid chloride.
The amine reactant is selected from the group consisting
of aliphatic amines, cycloaliphatic amines and aromatic amines.
Preferred aliphatic, cycloaliphatic, and aromatic amines include,
Clo-C30 aliphatic amines, cyclohexyl amine, methylcyclohexyl
amine, aniline, o-toluidine, m-toluidine, p-toluidine, 2,4-
xylidine, 2,5-xylidine, 2,6-xylidine, 3,4-xylidine and 3,5-
xylidine. A preferred amine is an aliphatic amine having more
than 12 and less than 30 carbon atoms. The most preferred amine
is octadecylamine.
.
- ~ ~S~ 7 ~ ~
- 7a - 73321-1
The additive composition of the present invention may be
prepared by heating mixtures of the carboxylic acid or acid
chloride with the amine at temperatures ranging from about 15C to
about 100C. A preferred range o temperature is rom about 15~C
to about 50C
`` ~2577q~
- 8 - 73321-1
for carboxylic acid chlorides and 60C -to 100C for carboxylic
acids.
The proportions of the reactants are not critical.
However, it is preferred that the molar ratio of the carboxylic
acid or acid chloride to the amine range from about 1.05/1.0 to
about 1.30/1,0. A more preferred molar ratio is 1.1/1Ø
An organic solvent may be used to provide a homogenous
mixture for the reaction of the amine wi-th the carboxylic acid
or acid chloride. Almost any common organic solvent can be used,
including alcohols, benzene, acetone, methylethyl ketone, diethyl
ether, dioxane, aliphatic hydrocarbons having 6 to 10 carbon
atoms, and cyclohexane. Preferred solvents are methanol and
ethanol. The optimum choice for any particular reaction depends
on the physical and chemical properties of the reactants.
A preferred reaction product is an amide with a car-
boxylic acid component having a dielectric constant higher than
that of the alcohol in the fuel and an aliphatic amine component
having a chain length of more than 12 and less than 30 carbon
atoms. Preferred reaction products are nitro-benzoctadecylamide,
benzoctadecylamide, and dioctadecylamide. The latter two reaction
products are suitable for use with methanol-gasoline fuel blends
containing lS percent or less methanol, any alcohol-gasoline fuel
blend containing the higher alcohols (ethanol, propano:L, butanol
and isomers thereof), or any alcohol-dimethoxymethane fuel blend.
~itrobenzoctadecylamide is suitable for use with any alcohol fuel
or alcohol-containing fuel blend described herein. The most pre-
`` ~2S7772
- 8a - 73321-1
ferred reaction product is meta-nitrobenzoctadecylamide, also
known as l-nitro-3-hexadecylamide, 3-nitrobenzoctadecylamide, and
l-octadecylamide-3-nitrobenzene.
~'æ~72
The fuel additive of the present invention may also
comprise a mixture of two or more of the reaction
products of a) a carboxylic acid or acid chloride
selected from the group consisting of unsub~tituted
aromatic carboxylic acids, aliphatic carboxylic acids,
nitro-substituted aromatic carboxylic acids, and their
corresponding acid chlorides, and b) an amine selected
from the group consisting of aliphatic amines, cyclo-
aliphatic amines, and aromatic amines. The fuel
additive of the present invention may comprise a
mixture of two or more of any reaction product
described herein or of any reaction product formed by
the reaction of any carboxylic acid or acid chloride
and any amine described herein. Preferably, the fuel
additive of the present invention may comprise a
mixture of two or more of the following preferred
reaction products: nitro benzoctadecylamide,
benzoctadecylamide and dioctadecylamide.
The method of the present invention comprises the step
of adding the fuel additive described above to alcohol
or alcohol-containing fuels to inhibit corrosion and
elastomer swelling and degradation in internal combus-
tion engines and in fuel dispensing systems caused by
alcohol or alcohol-containing fuels and to increase
the lubricity of alcohol or alcohol-containing fuels.
The fuel compositions of the present invention com-
prise: (a) a major portion of a fuel comprising from
about 1 to 100% by volume of an alcohol having 1 to 4
carbon atoms and from about 99 to 0% by volume of a
non-alcohol fuel selected fxom gasoline, individual
hydrocarbon components of gasoline, and dimethoxy-
methane (hereinafter methylal), and (b) a minor
35 portion of the fuel additive of the present invention
as described above.
~5777~
--10--
Alcohols useful in combination with the additive of
the present invention described hereln include such
cornmercially available alcohols as methanol, ethanol
n-propanol, iso-propanol, n-butanol, sec-butanol,
iso-butanol and tertiary-butanol. Preferred alcohols
are methanol and ethanol and the most preferred
alcohol is methanol. Mixtures of the various alcohols
may be used. In methanol-gasoline blends, it is often
necessary to include other alcohols to provide ade-
quate protection against phase separation under highhumidity and cold weather conditions.
Non-alcohol fuels useful in combination with the
alcohols and the additive of the present invention
include gasoline, individual hydrocarbon components of
gasoline, and methylal. The preferred non~alcohol
fuel is gasoline.
In a preferred embodiment, the fuel portion of the
fuel composition comprises from about 1 to 50~ by
volume of at least one alcohol having 1 to 4 carbon
atoms and from about 99 to 50~ by volume of a
non-alcohol fuel selected from the group identified
above. In a more preferred ernbodiment, the fuel
portion comprises about 3 to 20% by volume of the
alcohol and about 97 to 80% by volume of a non-alcohol
fuel identified above.
The preferred alcohol is methanol and the preferred
non-alcohol fuel is gasoline. A preferred fuel
composition comprises from about 1 to 100 % by volume
methanol and from about 99 to 0% by volume gasoline.
A more preferred fuel composition comprises from about
1 to 50% by volume methanol and about 99 to 50% by
volume gasoline. The most preferred fuel composition
comprises from about 3 to 20% by volume methanol and
from about 97 to 80% by volume gasoline.
~'~5'777~
The amount of the fuel additive of the present inven-
tion to be added to the fuel portion to provide the
fuel cornposition of the present invention will be an
amount sufficient to impart improved corrosion-
inhibiting, elastomer swelliny and degradation inhib-
iting, and increased lubricity characteristics to the
fuel compositions. Preferably, the amount of additive
in the fuel composition will be in the range of from
about 0.1 to 5.0% by weight. More preferably, the
additive will be present in the fuel composition
in the range of from about 0.1 to 1.0% by weight.
Most preferably, 0.15% by weight of the additive of
the present invention will be present in the fuel
composition.
The fuel compositions of the present invention can be
prepared by adding the reaction product of the
nitro-substituted aromatic carboxylic acid and the
- amine directly to the alcohol fuel portion or the
alcohol-containing fuel portion.
The fuel additive of the present invention is an
effective corrosion inhibitor for alcohol fuels and
alcohol-containing fuels. It is equally effective in
25 providing corrosion protection against both acidic and
alkaline contaminants. Common sources of acidic
contaminants are tanker trucks, acidic soils and fuel
combustion products. Common sources of alkaline
contaminants are tanker trucks, alkaline soils and
30 alkaline detergents used in automotive cleaning
facilities.
Each molecule of the fuel additive of the present
invention can neutralize one molecule of acid or one
35 molecule of base thereby providing corrosion protec-
tion. Equations 3 and 4 illustrate the reactions
wherein the fuel additive of the present invention
neutralizes hydrochloric acid (an acidic contaminant)
~:2S~7~
and sodium hydroxide (an alkaline contaminant).
CONHR COOH
2 ~ + H20 ~ ~ O2N ~ + RNH2~Hcl (3)
CONHR COONa
O2N ~ + H o NaOH, o N ~ + RNH3 OH ~4)
The corrosion reaction product of the acidic reaction,
RNH2-HCl, can in turn neutralize an alkaline contam-
inant, if present, as illustrated in Equation 5.
RNH2 HCl + NaOH --~ RNH2 + NaCl (5)
This is a cyclical process in which the amine is
regenerated and is then available for neutralization
of another acid molecule. This cyclical process can
be repeated indefinitely until the relative amounts of
acidic and alkaline contaminants introduced into the
system have been substantially depleted.
The corrosion reaction product from the basic reac-
tion, the amine salt RNH3 OH , can in turn neutralizean acidic contaminant, if present, and regenerate the
amine which is then available for neutralization of
another molecule of acidic contaminant, as illustrated
in Equation 6.
RNH3 OH + HCl ~ RNH2 ~ HCl + H20 (6)
The fuel additive of the present invention effectively
inhibits the swelling and degradation of hydrocarbon
polymers or elastomers caused by alcohol fuels.
Retention of original dimensions through long periods
of service is an essential requirement for elastomer
automotive components. Hydrocarbon polymers or
~25777'~
-13-
elastomers used to construct parts for internal
combustion engines are commonly selected for their
compatability with gasoline and have a ~olarity
approximately equal to the polarity of ~asoline
(dielectric constant of gasoline = 2 at 25C).
Alcohols having 1 to 4 carbon atoms have a much higher
polarity than gasoline, particularly rnethanol which
has a dielectric constant of 32 at 25~C. The swelling
and degradation of hydrocarbon polymers or elastomers
selected for use with gasoline fuels is due to the
large difference in polarity between the alcohol and
the elastomer.
While not intending to limit the invention by a
particular theory, it is believed that the additive of
the present invention inhibits elastomer swelling and
degradation by forming a protective layer adjacent to
the elastomer surface. The carboxylic acid component
of the additive is more polar than the alcohols having
1 to 4 carbons and thus, will displace the alcohol
from the surface of the elastomer and attach itself to
the elastomer surface. For irstance, the nitrobenzoic
acid component of a preferred additive, meta-nitro-
benzoctadecylamide, has a dielectric constant of 40 at
25C, whereas methanol has a dielectric constant of 32
at 25C. Since the nitro-substituted aromatic car-
boxylic acid component is more polar than the methanol
or other alcohols, it will displace the methanol or
alcohol from the surface of the elastomer and form a
protective layer. The amine component of the addi-
tive, which has a dielectric constant closer to that
of gasoline, extends outward from the carboxylic acid
component anchored to the elastomer surface, thus
providing a polar environment adjacent to the
elastomer surface similar to that of gasoline. For
instance, an aliphatic amine having more than 12 and
less than 30 carbon atoms has a dielectric constant
from about 2 to 5 at 25C., whereas gasoline has a
~25777~
-14-
dielectric constant of 2 at 25C. The amine component
provides a protective barrier against re-entry of the
alcohol and thus inhibits the swelling and chemical
degradation of elastomers caused by alcohols.
The additive of the present invention also increases
the lubricity of the fuel composition. The fuel
additive of the present invention provides lubricity
properties via the amine component. Preferably, for
optimum lubricity properties, the amine will be an
aliphatic amine having 10 to 30 carbon atoms. The
most preferred aliphatic amine has 18 carbon atoms.
The long chain aliphatic amine ensures that the acidic
contaminants or combustion products which are neutral-
ized by the additive of the present invention will bein the liquid state. The long chain aliphatic amine
also ensures that any blowby products which enter the
crank case will be soluble in the lubricating oil.
Example 1
A test was performed to determine whether the additive
of the present invention would alleviate the elastomer
swelling encountered when operating vehicles on
methanol-gasoline blends of more than 8~. The control
data was obtained from a 1980 Chevrolet Citation~
which had been driven 349 miles on a 5% methanol-95%
gasoline fuel blend. The carburetor was then dis-
assembled and inspected, and measurements of elastomer
components in the carburetor were taken. See column 1
of CHART 1 below.
The same vehicle was then driven for 2979 miles on a
10% methanol-90% unleaded gasoline fuel blend con-
taining meta-nitrobenzoctadecylamide. 225 ml. of the
additive was added to 30 gallons of the 10% methanol-
90~ unleaded gasoline fuel blend. The only difference
in drivability noted was an increase in warm-up time.
The carburetor was disassembled and inspected, and
~;~57~
-15-
measurements of the elastomer components in the
carburetor were taken. See column 2 of CHART 1 below.
CHART 1
CARBURETOR MEASUREMENTS
Carburetor Components -1- 2-
Accelerator Pump Cup .650 units .650 units
Float Needle .164 units .164 units
Mixture Control
Solenoid O-Ring .332 units .332 units
Float Weight 8.3 grams 8.3 grams
Float Level (Dry) .250 units .250 units
The inspection of the carburetor elastomers demon-
strated that no swelling had occurred and that all
items measured before and after the vehicle was driven
on the 10% methanol fuel blend remained the same size.
No foreign material was found in the fuel filter or
the carburetor bowl. The mixture control solenoid
O-ring appeared to soften slightly. The Citation
achieved 19.4 miles per gallon when operated on the 5%
methanol blend for 349 miles and 20.5 mi]es per gallon
when operated on the 10% methanol fuel blend with
meta-nitroben~octadecylamide.
