IMPROVED FUEL COMPOSITION

Abstract: An additive package for reducing and/or preventing injector fouling in a multiport fuel injec­ tion means is described. The additive package preferably comprises a particularly described amine oxide, one or more particularly described demulsifiers, and a particularly described solvent system.

Description: BACKGROUND OF THE INVENTION This invention is directed to an anti-­ fouling fuel composition. More specifically, the present invention is directed at a fuel composition having particular applicability in minimizing and/or preventing injector fouling in gasoline engines equipped with electronically controlled multiport fuel injectors. Over the past several years, improvements have been made in the performance of internal combus­ tion engines. One of the most significant improvements which has been made has been the widespread use of fuel injection to improve the performance and fuel economy of internal combustion engines. While carburetor-­ equipped internal combustion engines admix the air and fuel for distribution through a manifold to all of the cylinders, in a fuel injected engine the fuel is in­ jected into the manifold close to the intake valve of each cylinder for combustion. Fuel injection systems are of two basic types, mechanically controlled and electronically controlled. The early fuel injected engines were controlled mechanically, i.e., the opera­ tion of each injector was controlled by pressure. Recently, however, the use of electronically con­ trolled fuel injection engines has become increasingly widespread. In an electronically controlled fuel injection system sensors disposed in the exhaust are employed to maintain the air to fuel ratio within narrow limits. Electronically controlled fuel in­ jection systems offer the same performance and fuel economy benefits that would be achieved with mechani­ cally controlled fuel injection systems and also serve to more closely regulate fuel-air mixtures to thereby enable the catalytic converter to oxidize carbon monoxide and hydrocarbons to carbon dioxide and simultaneously to reduce nitrogen oxides and thus meet emissions control legislation. Such legislation imposing as it did strict control of exhaust pollutants utimately led to the development and widespread appli­ cation of new technologies such as electronic fuel injection. It has been found that the electronically controlled fuel injector systems have small port openings which are prone to fouling by deposits. These deposits are believed to occur, at least in part, by gasoline and oil vapor, which is present in close proximity to the injector tip, becoming baked onto the hot surfaces of the injector pintle and on the surfaces of the annulus surrounding the pintle when the engine is shut off. These deposits restrict the fuel flow to that particular cylinder. This, in turn, causes a sensor disposed in the exhaust to detect a higher than desired oxygen to fuel ratio. The sensor will attempt to correct this condition by increasing the amount of fuel injected into all of the cylinders. This, in turn, will result in a richer than desired fuel to air ratio in the exhaust. The sensor then will attempt to correct this by decreasing the amount of fuel injected into each cylinder. This cyclical adjustment of the fuel to air ratio ranging between too lean a mixture and too rich a mixture can at times result in poor operating performance of the vehicle. In addition, close tolerances in this new type of injector and con­ currently higher underhood temperature also tend to enhance deposit formation resulting in poor vehicle driveability and exhaust pollutant emission levels which exceed the maximum levels set by emisisons control legislation. It has been found that conventional gasoline detergents, which have proven effective in preventing and/or eliminating carburetor deposits are not par­ ticularly effective in removing and/or preventing deposit build-up that may occur in electronically con­ trolled fuel injection systems. Presently available methods for removing deposits from fuel injector orifices typically comprise either mechanically cleaning the injectors or the addition to the fuel of relatively large quantities of particular additives. Mechanical cleaning, which may involve either the com­ plete removal of the injector for manual deposit re­ moval or the use of polar solvents for flushing the deposits free, is not desired because of the rela­ tively high cost and inconvenience. Currently avail­ able additives are not particularly desirable because product recommendations indicate they must be used at relatively high concentrations, i.e. about one to about two tons per thousand barrels of fuel. To be useful commercially a gasoline additive for reducing and/or preventing injector port fouling must be effective at low concentration, must not significantly affect the combustion characteristics of the fuel and must not foul the catalytic converter catalyst. The additive also should not promote excessive emulsification, and should not promote the formation of two organic phases. Additives have been added to gasoline to improve certain properties of the fuel. U.S. Patent No. 3,387,953 is directed at the use of organo-substituted nitrogen oxides, particularly amine oxides for rust inhibition and as anti-icing agents in gasoline. Several representative formulas for amine oxides are given including the following: where: R₁ is C₆-C₂₄ alkyl, aryl, cycloaliphatic, heterocyclic, substituted alkyl or substituted aryl; and R₂ and R₃ are the same or different and are C₁-C₂₄ alkyl, aryl, substituted alkyl or aryl, cycloaliphatic or heterocylic. R₂ and R₃ preferably comprise hydroxy substituted alkyls. These compounds typically are added to gasoline in a concentration within the range of about 2.0 to about l00 pounds of amine oxide per l,000 barrels of gasoline (ptb). Among the most preferred additives is bis(2-hydroxy ethyl) cocoamine oxide. U.S. Patent No. 3,594,l39 is directed at a rust-inhibitor concentrate that can be blended with gasoline year-round including amine oxides having the aforementioned formula, with a particularly preferred amine oxide comprising bis(2-hydroxy ethyl) cocoamine oxide. The concentrate also comprises a liquid aromatic C₇-C₁₀ hydrocarbon and an aliphatic monohydric or dihydric alcohol having from about 6 to about l3 carbon atoms. Preferred aromatic hydrocarbons comprise ortho, meta and mixed xylenes. Preferred aliphatic alcohols comprise C₆-C₁₃ oxo alcohols. The examples disclose the combination of xylene, bis(2 hydroxyethyl) cocoamine oxide, and C₈ oxo alcohols. The amine oxides described above have been typically used to inhibit rust and carburetor icing. While these compounds were used commercially during the late l960's and early l970's, their use in the United States was discontinued as more effective additives were found. The use of these compounds had been dis­ continued in the United States well before the develop­ ment of electronically controlled, fuel injected engines. It has been discovered that use of amine oxides at concentrations generally higher than that which previously had been used for rust inhibition would be effective in preventing and/or reducing injector fouling in multiport fuel injected engines. However, when amine oxides are used at these higher concentrations they tend to act as emulsifiers which bring into the gasoline layer, water, sediment and impurities which may have entered the product distribu­ tion system. This prevents normal separation of the gasoline from any water or normally insoluble impurities. The admixture of these impurities is not desired with the gasoline, since this would result in excessive fuel filter fouling and in poor vehicle operation. In addition, it is believed that formation of an emulsion results in undesirable concentration of the amine oxide additive at the interface. It also has been found that the use of certain solvents to produce an additive concentrate having low cloud and pour points may form two organic layers, resulting in uneven additive distribution. Accordingly, it would be desirable to provide an additive package for gasoline which will be effective in reducing and/or eliminating fouling without forming an emulsion with water bottoms and interfacial solids. It also would be desirable to provide an additive package having a demulsifying agent which is effective in the presence of both neutral and basic waters. It also would be desirable to provide an additive concentrate which has low cloud and pour points and which does not result in the formation of more than one organic layer. Accordingly, it would be desirable to pro­ vide a gasoline additive package which is relatively inexpensive and effective at low concentrations to reduce and/or eliminate injector fouling. It also would be desirable to provide a gasoline additive package which is non-corrosive, non­ deleterious to the catalyst, and does not effect the combustion characteristics of the fuel. It also would be desirable to provide a gasoline additive package which could be easily added to the finished gasoline at any point during the storage and/or distribution system. SUMMARY OF THE INVENTION The present invention is directed at a fuel composition for minimizing and/or preventing injector fouling in a multiport electronically controlled fuel injected engine. The composition comprises: A. gasoline B. an anti-fouling agent having the formula: where: R₁ is C₆-C₂₄ alkyl, aryl, cycloaliphatic, heterocyclic, substituted alkyl or substituted aryl; and R₂ and R₃ independently are C₁-C₂₄ alkyl, aryl, substituted alkyl or aryl, cycloaliphatic or heterocylic; and, C. a demulsifier comprising one or more of the following demulsifying agents: i. a fatty acid alkylamine reaction product; and, ii. a solution of oxyalkylated alkyl phenol formaldehyde resins and polyglycols. In this composition R₁ preferably is C₆-C₂₀ alkyl, or alkylated aryl, and R₂ and R₃ independently are C₁-C₁₂ hydroxy substituted alkyl. In a more preferred composition R₁, comprises C₈-C₁₈ substituents derived from fatty acid. The additive preferably is selected from the group consisting of bis(2-hydroxy ethyl) cocoamine oxide, bis(2-hydroxy ethyl) tallow amine oxide, bis(2-hydroxy ethyl) stearyl-amine oxide, dimethylcocoamine oxide, dimethyl hydrogenated tallow amine oxide, dimethylhexadecylamine oxide and mixtures thereof. A particularly preferred additive is bis(2-­ hydroxy ethyl) cocoamine oxide. The anti-fouling agent concentration in the fuel typically may range between about 0.5 and about 50 ptb (i.e. about 2 to about 200 ppm, by weight), preferably between about 5 and about l5 ptb (i.e. about 20 to about 60 ppm). In demulsifying agent (ii) the oxyalkylated compounds preferably comprise ethylene oxide and propylene oxide copolymers. The active concentration of the demulsifying agent may range between about 0.025 and about l0 ptb (about 0.l and about 40 ppm), preferably between about 0.25 and about 2.0 ptb (about l.0 and 8.0 ppm). A fuel composition may comprise: A. about 2 to about 200 ppm bis(2-hydroxy ethyl) cocoamine oxide; and, B. about 0.l to about 40 ppm of a demulsifying agent selected from the group consisting of: i. fatty acid alkylamine reaction product; ii. a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols; and mixtures of i and ii. A preferred composition comprises: A. about 20 to about 60 ppm bis(2-hydroxy ethyl) cocoamine oxide; and, B. about l to about 8 ppm of a demulsifying agent selected from the group consisting of: i. fatty acid alkylamine reaction product; ii. a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols; and mixtures of i and ii. A preferred fuel composition includes an additive package comprising: A. about 20 ppm to about 60 ppm bis(2-­ hydroxy ethyl) cocoamine oxide; B. about 0.5 ppm to about 4 ppm fatty acid alkylamine reaction product; and, C. about 0.5 ppm to about 4 ppm of a solu­ tion of oxyalkylated alkylphenol formaldehyde resins and polyglycols. The present invention also is directed at a fuel additive concentrate for internal combustion engines, said additive concentrate comprising: A. about 5 to about 50 wt.% bis(2-hydroxy ethyl) cocoamine oxide; B. about 0.25 to about l0 wt.% of a demulsifying agent selected from the group consisting of: i. fatty acid alkylamine reaction product; ii. a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols; and mixtures of i and ii; and, C. about 40 to about 95 wt.% solvent. The solvent preferably comprises xylene and a C₄+ alcohol, preferably a C₄-C₁₂ alcohol, more preferably a C₈ alcohol and most preferably a C₈ oxo alcohol. Where the ratio of the concentration of water relative to amine oxide exceeds about 0.05, a highly water and hydrocarbon soluble alcohol, preferably isopropanol, also should be added. DETAILED DESCRIPTION OF THE INVENTION The present invention is directed at a fuel composition and a gasoline additive package which has been found to be particularly effective in reducing and/or eliminating injector fouling. The present in­ vention is directed at a fuel comprising: A. gasoline; B. an anti-fouling agent having the following structural formula: where R₁ is C₆-C₂₄ alkyl, aryl, cycloaliphatic, heterocyclic, substituted alkyl, substituted aryl; R₂ and R₃ independently are C₁-C₂₄ alkyl, aryl, sub­ stituted alkyl or aryl, cycloaliphatic, heterocyclic, and mixtures thereof; and, C. a demulsifying agent selected from the group consisting of: i. a fatty acid alkylamine reaction product; ii. a solution of an oxyalkylated alkylphenol formaldehyde resins and polyglycols; and mixtures thereof. Preferred anti-fouling agents include compounds wherein: R₁ is C₆-C₂₀ alkyl, or alkylated aryl; and R₂ and R₃ independently are hydroxy substituted C₁-C₁₂ alkyl. Particularly preferred compounds are compounds wherein R₁ comprises a C₈-C₁₈ substituent. The additive preferably is selected from the group consisting of bis (2-hydroxy ethyl) coco­ amine oxide, bis(2-hydroxy ethyl) stearylamine oxide dimethylcocoamine oxide, dimethyl hydrogenated tallow amine oxide, dimethylhexadecylamine oxide and mixtures thereof. These additives are prepared in accordance with known techniques, such as disclosed in U.S. Patent 3,387,953, the disclosure of which is incorporated herein by reference. A particularly preferred anti-­ fouling agent is bis(2-hydroxy ethyl) cocoamine oxide. The following Comparative Examples and Examples demonstrate the utility of the anti-fouling agent in reducing and/or eliminating fuel injector fouling. In the following Comparative Examples and Examples, the octane rating of the fuel utilized is the posted octane rating which is defined as: COMPARATIVE EXAMPLE I In this test three l985 Oldsmobile 98's having electronically controlled, fuel injected, 3.8 liter, six cylinder engines were driven on a commer­ cial, unleaded, 87 octane reference fuel having a detergent concentration of 8.5 ptb for approximately 3500 miles under the following driving cycle: 0.5 hours city-type driving, 0.5 hour engine off, 0.5 hour high­ way driving, 0.5 hour engine off. Driveability on all four vehicles became poor to very poor. The vehicles then were driven for 300 miles with a commercial premium grade 92 octane unleaded fuel containing 2.5 times the detergent used in the above reference fuel. Driveability remained unchanged. The data in Table I below show that there was still a marked reduction in fuel flow indicating that a high level of deposit was unaffected by the detergent even at the high treat rate. The percent fuel flow reduction was determined by measuring the volume of a mineral spirit that flowed through the injector under predetermined standardized conditions, including fuel pressure, pulse width and duty cycle. The percent reduction is calculated using the formula: where V clean and V dirty are the measured volumes of mineral spirit passed through the clean and dirty fuel injectors. From Table I it can be seen that this con­ ventional, known carburetor detergent was ineffective in removing deposits from injector ports and in fact permitted deposits to form. COMPARATIVE EXAMPLE II A l985 Chrysler LeBaron equipped with a 2.2 liter turbocharged engine having electronically con­ trolled fuel injection was driven for l300 miles on a mileage accumulation dynamometer using a typical regular grade, 87 octane, unleaded, detergent-free gasoline. The driving was based on repetition of the following cycle: 30 minutes city driving, 30 minutes engine off, 30 minutes highway driving, 30 minutes engine off. The driveability became very poor as typified by rough idle and severe hesitation. The hydrocarbon emissions measured before the catalytic converter were 32l ppm at engine idle. The injector fouling was measured using a pressure differential test. In this test the fuel rail is pressurized to 49 psig and an injector is pulsed for 0.5 seconds. The pressure drop, or leakdown P, is indicative of how readily the fuel flows, i.e., the higher the number, the less the injector is obstructed. In this vehicle the pressure differential for a clean injector under these conditions is l9-22 psig. This data is set forth below in Table II. EXAMPLE I Following the test set forth in comparative Example II, the vehicle was refueled with the same fuel except that the fuel also contained l0 ptb of bis(2-­ hydroxy ethyl) cocoamine oxide (HECO). The vehicle then was driven on the following cycle: l5 minutes city driving, 30 minutes highway driving, l5 minutes city driving, 2 hours engine off. This test continued until 270 miles were accumulated on the vehicle. At the end of this test period the driveability was very good. The hydrocarbon emissions at idle before the catalytic converter were reduced to 200 ppm. The percent in­ jector flow reduction and the pressure differential were significantly improved as set forth in Table II. From the data of Example I and Table II it can be seen that the use of a relatively low concen­ tration of HECO was able to produce a significant im­ provement in driveability. The idle emissions were significantly reduced and the pressure differential and percent flow reduction of the flow injectors were re­ turned to "as new" conditions after a relatively few miles of driving. As shown by the following Comparative Examples and Example, bis (2-hydroxy ethyl) cocoamine oxide also was effective in preventing the build-up of fuel injector tip deposits. COMPARATIVE EXAMPLE III In this Comparative Example, four l985 Chrysler LeBarons equipped with four cylinder, electronically controlled, fuel injected, turbocharged, 2.2 liter engines were driven on mileage accumulation dynamometers under the following conditions: 0.5 hour city-type driving, 0.5 hour engine off, 0.5 hour high­ way type driving and 0.5 hour engine off for 4,000 miles. The control cars ran on a regular grade, 87 octane, detergent-free, unleaded fuel. Following the test, the percent flow reduction was measured using the procedures previously set forth hereinabove. The tests were repeated in four different runs (same make and model). The results of these tests are set forth in Table III below. EXAMPLE II A l985 Chrysler LeBaron, similar to that set forth in Comparative Example III was used in this test which was conducted under the same conditions set forth in that Comparative Example. The gasoline used during this test was the same as that used in the control cars, but with the further addition of l0 ptb of bis(2-hydroxy ethyl) cocoamine oxide (HECO). The results of these tests are also set forth in Table III below. From a review of these tests it can be seen that the addition of a relatively low concentration of HECO was able to prevent a significant reduction in the fuel injector flow rate. COMPARATIVE EXAMPLE IV In this test a l985 Chrysler LeBaron having a four cylinder, turbocharged, 2.2 liter engine with electronically controlled fuel injection was operated for 2,002 miles on a mileage accumulation dynamometer simulating alternating driving and engine-off cycles. The fuel utilized was typical of a regular grade, 87 octane, unleaded fuel containing 8.5 ptb of the same detergent used in Comparative Example I. Following the completion of this test, the percent flow reduction through the fuel injector ports was measured by the method previously described herein. As shown in Table IV below the use of this conventional carburetor detergent was ineffective in preventing injector fouling. EXAMPLE III A vehicle similar to that utilized in Comparative Example IV was utilized in this Example under the same operating conditions. The fuel utilized was similar but with the replacement of the conven­ tional carburetor detergent by l0 ptb of bis(2-hydroxyl ethyl) cocoamine oxide. The vehicle was driven for 9,600 miles under the same sequence set forth in Comparative Example IV. The bis(2-hydroxy ethyl) cocoamine oxide was able to prevent any significant flow reduction in the fuel injectors as shown by data presented in Table IV. From this Table it can be seen that the use of a relatively low concentration of HECO was able to prevent any significant buildup of injector tip de­ posits. By comparison, the use of a conventional carburetor detergent at approximately the same rate was unable to prevent a relatively rapid deposit build­ up of injector tip deposits. While the data presented above has demonstrated the utility of the anti-fouling agent in gasoline, the anti-fouling agent also may be of utility in other fuels, such as diesel fuel. While the presently described anti-fouling agent may be used alone, it also may be desirable to utilize the present invention in combination with a demulsifier to facilitate the separation of the gasoline from any foreign substances which may be present in the distribution system, such as water and sediment. The water, if any, typically has a pH ranging from about 7 to about l2. Thus, a demulsifier for use with the anti-fouling agent preferably should be effective over this pH range. The following Comparative Examples and Examples demonstrate the utility of a demulsifying agent selected from the group consisting of: A. a fatty acid alkylamine reaction product; B. a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols; and mixtures of A and B above. COMPARATIVE EXAMPLE V In this Comparative Example the effective­ ness of various commercially availabIe demulsifying agents were tested in a 90 wt.% fuel - l0 wt.% water system. The fuel contained l0 ptb HECO and l ptb of the various additives noted below. The effectiveness of the various demulsifying agents was reached using a Multiple Contact Emulsion Test. In this test l0 ml of distilled water was added to separate half-pint bottles. To each bottle was added l00 ml of gasoline. The bottles were capped, placed on their sides in a mechanical shaker and agitated at approximately 28 cycles per minute for five minutes. The bottles then were placed upright in a dark location and allowed to stand for 24 hours. The mixture then was rated considering the gasoline layer, the water layer and the interface using the rating scale set forth in Table V below. After the ratings were completed, the gasoline level was sucked down to a level about l/4 inch above the emulsion layer without disturbing the interface or water layer. The withdrawn fuel was discarded and l00 ml of fresh gasoline was added to each bottle. The mixture was then shaken and the test repeated for a total of ten times (i.e. a total of about l0 days) or until it became apparent that the emulsion forming tendencies had exceeded acceptable levels of 3 or lower. The trade names of the commercially available additive utilized, the worst ratings of each mixture and the time period before each test was terminated are set forth in Table VI below. EXAMPLE IV A gasoline-distilled water sample having l0 ptb of HECO similar to that of Comparative Example V was utilized. However, in place of the demulsifiers listed in Table VI the following additives were used alone or in combination. Additive A - Nalco 3BD829 Fuel Dehazer, manufactured by Nalco Chemical Company, Oak Brook, Illinois, which comprises a fatty acid alkylamine reaction product and methanol in a hydrocarbon solvent. Additive B - Tolad T-326 manufactured by the Tretolite Division of Petrolite Corporation, St. Louis, Missouri. This additive comprises oxyalkylated alkylphenol-­ formaldehyde resins and polyglycols in aromatic naphtha. The Multiple Contact Emulsion Test previously described was utilized to determine the effectiveness of these demulsifiers. These test results are summarized in Table VII below. From a review of Table VII, it can be seen that both Additive A and Additive B were effective. It also can be seen that Additive A and the same total concentration of a mixture of Additive A and Additive B were more effective than Additive B alone. EXAMPLE V A sample comprising l00 ml portions of gasoline containing l0 ptb of HECO and a total of l ptb of Additive A, Additive B or a combination of Additive A and Additive B was tested with another typical gasoline contaminant, refinery process water bottoms having a pH of l0. A sample containing 90 wt.% of this fuel and l0 wt.% of the process water bottoms was utilized. The Multiple Contact Emulsion Test described in Comparative Example V was utilized with one modification. The sample was shaken at l l/2 hour intervals rather than 24 hour intervals. Thus, this procedure is more severe than the test method of Comparative Example V. The results of this test are set forth in Table VIII below. From this table it can be seen that Additive B and a mixture of Additive A and Additive B were more effective than Additive A alone. Demulsifier Additive A was thus found to be more effective than Additive B with neutral water, while Additive B was much more effective than Additive A when the water was basic. The combination of these additives is particularly preferred, since it was highly effective in both neutral and basic conditions. Where the presently described invention is used as a gasoline additive, the additive package may be added to the gasoline at any point after the gasoline has been refined, i.e., the additive package can be added at the refinery or in the distribution system. To assure a relatively constant concentration of the additive package in the gasoline and to assure that none of the additives precipitate from the addi­ tive package, diluent solvents typically are combined with the additive package to produce an additive con­ centrate which is metered into the fuel. The amine oxide typically has water present from the manufacturing process. While it is possible to remove most of the water, removal of the water to relatively low levels, i.e. a ratio of about 0.02 to about 0.04 of water to amine oxide, adds complexity to the manufacturing process. Therefore, the amine oxide is commercially available as a solution which has the following composition: To provide an additive concentrate which is pumpable and which does not precipiate even in winter conditions, the concentrate preferably should have a cloud point below about -20°F and a pour point of less than -40°F. Typically, the additive package is diluted in the range of about l:l to about l0:l with diluent solvent, preferably about 5:l to facilitate metering and to provide a concentrate having the desired cloud and pour points. COMPARATIVE EXAMPLE VI In this test, the additive package was diluted about 4.9:l with a diluent which comprised about 90 wt.% xylene and l0 wt.% isopropanol. The resulting concentrate had the following composition: Twenty-five ml. of this additive concentrate were mixed with 25 ml. of gasoline and l0 ml. of refinery water bottoms in an 8 inch centrifuge tube with a narrow tip to simulate the conditions which could occur in the field before the additive concentrate is completely mixed with the gasoline. An excess of water was included for illustrative purposes as set forth below. The tube was placed in an ultrasonic bath at room temperature and subjected to ultrasonic fre­ quencies for about five minutes to cause intimate mixing. After removal from the ultrasonic bath and centrifugation to facilitate separation, it was noted that three phases had formed, two organic phases and a water phase. Formation of two organic phases is not desirable, since this was found to result in uneven distribution of the HECO between the layers. In addi­ tion, the second organic layer which has a much higher HECO concentration, tends to adhere to the surfaces, resulting in additive loss and potential contamination of subsequent hydrocarbon products that might contact these surfaces. EXAMPLE VI In this Example, the same additive package was used as was used in Comparative Example VI. The additive package again was diluted with about 4.9 parts solvent. However, in this Example the isopropanol in the diluent solvent was replaced with an equal weight of C₈ oxo alcohol. The concentrate had the following composition: Twenty-five ml. of this additive concentrate were mixed with 25 ml. of gasoline and l0 ml. of refinery water bottoms and intimately mixed in an ultrasonic bath as described in Comparative Example VI. After intimate mixing and centrifugation to facilitate separation, it was noted that only two layers, an organic layer and a water layer were formed. From this Example it can be seen that the replacement of at least a portion of the isopropanol by a higher molecular weight alcohol, preferably a C₄-C₁₂ alcohol, more preferably an oxo alcohol and most preferably a C₈ oxo alcohol, prevented the formation of two organic layers. As used herein the term "oxo alcohol" refers to one or more branched chain aliphatic alcohols prepared by the reaction of carbon monoxide and olefins followed by hydrogenation of the resulting aldehydes. A series of tests also were run utilizing different solvents to determine the cloud point of the resulting additive concentrates. Those tests generally were conducted in accordance with ASTM test method D2500, the disclosure of which is incorporated herein by reference. These results are presented in Table IX. From a review of Table IX, it can be seen that the combination of a solvent system comprising xylene, isopropyl alcohol and C₈ oxo alcohol produces an additive concentrate which has a cloud point below about -46°F for the point tested. By comparison, use of a solvent system comprising only xylene and C₈ oxo alcohol produced a system which had acceptable cloud points only over a very narrow concentration range. Therefore, the use of a mixed alcohol solvent system is desirable to produce a concentrate having good low temperature properties without the tendency to form a second organic layer. Multiple Contact Emulsion Tests were con­ ducted in a manner similar to that set forth in Comparative Example V for gasoline samples. The tests were run on both unleaded regular grade gasoline and unleaded premium grade gasoline containing l0 ptb HECO and 0.5 ptb each of Demulsifiers A and B, to which l0 wt.% terminal water bottoms having a pH of about 7 and 8, respectively, had been added as previously described. The samples were shaken for l0 minutes at l80 cycles per minute. The bottles then were permitted to stand for the times indicated and rated. As shown by the data in Table X, the replacement of the isopropanol by the combination of isopropanol with C₈ oxo alcohol did not adversely affect the effectiveness of the demulsifier package. Thus, a concentrate in­ cluding a solvent system comprising isopropanol and C₈ oxo alcohol has acceptable demulsifying properties and an improved cloud point relative to a solvent system comprising C₈ oxo alcohol alone, when significant quantities of water are present. As previously noted, such a solvent system also does not promote the forma­ tion of multiple organic layers.

Claims: 1. A fuel composition for an internal combustion engine said engine composition comprising: A. gasoline; B. an antifouling agent having the formula wherein: R₁ is C₆ to C₂₄ alkyl, aryl, cycloaliphatic, heterocyclic, substituted alkyl or substituted aryl; R₂ and R₃ independently are C₁ to C₂₄ alkyl, aryl, substituted alkyl or aryl, cycloaliphatic or heterocyclic; and C. a demulsifier selected from the group consisting of: i. a fatty acid alkylamine reaction product; ii. a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols; and mixtures of i and ii. 2. The fuel composition of claim l wherein R₁ is C₆ to C₂₀ alkyl, or alkylated aryl; and, R₂ and R₃ independently are hydroxy substituted C₁ to C₁₂ alkyl. 3. The fuel composition of claim 2 wherein the fuel comprises unleaded gasoline. 4. The fuel composition of claim 3 wherein the demulsifier comprises: A. a fatty acid alkylamine reaction product; and, B. a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols. 5. A fuel additive concentrate for internal combustion engines, said additive comprising: A. about 5 to about 50 wt.% bis(2-hydroxy ethyl) cocoamine oxide; B. about 0.25 to about l0 wt.% fatty acid alkylamine reaction product; and, C. about 0.25 to about l0 wt.% oxyalkylated alkylphenol formaldehyde resins and polyglycols; D. about 40 to about 95 wt.% solvent. 6. The fuel additive concentrate of claim 5 wherein the solvent comprises xylene and an alcohol. 7. The fuel additive concentrate of claim 6 wherein the alcohol is selected from the group consisting of isopropanol, C₄-C₁₂ alcohols, and mixtures thereof. 8. A fuel additive concentrate for internal combustion engines, said additive comprising: A. about 5 to about 50 wt.% bis(2-hydroxy ehtyl) cocoamine oxide; B. about 0.25 to about l0 wt.% of a demulsifying agent; and, C. about 40 to about 95 wt.% of a solvent comprising: i. xylene; and ii. a C₄-C₁₂ alcohol. 9. The fuel additive of claim 8 wherein the solvent further comprises isopropanol. l0. A fuel composition for reducing and/or preventing fouling in a multiport electronically controlled fuel injection system for an internal combustion engine, said fuel composition comprising: A. about 20 to about 60 ppm bis(2-hydroxy ethyl) cocoamine oxide; B. about 0.5 to about 4 ppm fatty acid alkylamine reaction product; and, C. about 0.5 to about 4 ppm oxyalkylated alkylphenol formaldehyde resins and polyglycols.

Inventors: VARDI, JOSEPH, ZIMMERMAN, ABRAHAM ABBA
Applicants: EXXON RESEARCH AND ENGINEERING COMPANY
Application year: 1987
Main classification: C10L10
IPC codes: C10L1, F02B1, F02B77, C10L10, F02B3