DE69101603T2 - FUEL ADDITIVE COMPOSITION. - Google Patents

Abstract

A homogeneous fuel additive composition which comprises: (a) a dispersant comprising a hydrocarbyl poly (oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of about 1000 to about 3000; (b) an injection detergent comprising a branched-chain hydrocarbyl amine having at least one basic nitrogen atom and an average molecular weight of about 300 to about 700, wherein the hydrocarbyl moiety is derived from polymers of C2 to C6 olefins; (c) a fuel demulsifier which is homogeneous with the other components of said fuel additive composition; and (d) a natural or synthetic carrier fluid.

Description

BACKGROUND OF THE INVENTION

Hydrocarbon fuels have a number of deposit-forming substances inherent in them. When these substances are used in internal combustion engines, they tend to form deposits in and around localized areas of the engine that come into contact with the fuel. Typical areas commonly and sometimes severely affected by deposit formation include carburetor vents, the throttle body and horn, engine intake valves and intake ports, fuel injectors, the cylinder head and combustion chamber piston cover surfaces, etc.

Deposits have a detrimental effect on the operation of vehicles that use hydrocarbon fuels. For example, deposits on the throttle body and vents increase the fuel/air ratio of the gas mixture to the combustion chamber, increasing the amount of unburned hydrocarbon and carbon monoxide expelled from the chamber. High fuel/air ratios also reduce the gas mileage that can be achieved with the vehicle.

Deposits on the engine intake valves that are sufficiently heavy restrict the flow of the gas mixture into the combustion chamber. This restriction causes the engine to be starved of air and fuel and a loss of power occurs. Deposits on the valves also increase the likelihood of valve failure due to burning and improper valve seating. In addition, these deposits can break off and enter the combustion chamber, possibly causing mechanical damage to the piston cap, piston rings, cylinder head, etc.

It has long been known that the formation of these deposits can be both inhibited and eliminated by adding an active detergent to the fuel. These detergents have the function of cleaning the areas prone to deposits of the harmful deposits, thereby increasing the performance and service life of the engine.

The first generation of fuel additives consisted of detergents that helped maintain the cleanliness of critical carburetor elements. These original fuel additives were typically used in low doses, generally in the range of 15 to 30 ppm. Unfortunately, these low doses of additives provided little control of deposits in other parts of the internal combustion engine.

The next generation of fuel additives generally provided improved control of deposits in the intake system, including hot spots in the intake manifold, in ports, in intake valve slots and inlet valves. The degree of deposit control was typically regulated by controlling the dosage of additive, usually in the range of 70 to 2,000 ppm. However, when the dosages of additive were increased to high levels, the accumulation of deposits in the combustion chambers became a significant problem, for reasons which will become apparent below.

In recent years, the widespread use of unleaded gasoline has further complicated the use of detergent-type gasoline additives. In automotive engines requiring the use of unleaded gasolines (to prevent catalytic converters used to reduce emissions from being rendered ineffective), it has been found difficult to supply gasoline with an octane rating sufficient to prevent knocking and the associated damage caused thereby. The problem arises from an increase in octane requirement, hereinafter referred to as "ORI," which is a result of the deposits formed by the use of commercial gasolines.

The basis of the ORI problem is this: every engine, when new, requires a fuel with a certain minimum octane rating to run satisfactorily without pinging and/or knocking, and/or after operation. As the engine is run on any gasoline, this minimum octane requirement increases. This is obviously caused by the formation of deposits in the combustion chamber. In most cases, if the engine is run on the same fuel for an extended period of time, the ORI will reach equilibrium. Equilibrium is typically reached after 5,000 to 15,000 miles (3107.5 - 9322.5 km) of vehicle operation.

The increase in octane requirement in a given engine running on commercial gasolines will vary from 4 to 6 octane units at equilibrium to 12 or 15 units, depending on the gasoline compositions, engine design, and type of operation. This demonstrates the severity of the problem. A typical automobile with a research octane requirement of 85 when new may, after a few months of operation, require research octane gasoline of 97 for proper operation, and little unleaded gasoline of that octane is available. The ORI problem also exists to some extent in engines running on leaded gasoline. U.S. Patent Nos. 3,144,311; 3,146,203 and 4,247,301 disclose leaded fuel compositions which have reduced ORI properties.

The ORI problem is related to the fact that the most common method of increasing the octane content of unleaded gasoline is to increase its aromatics content. However, these aromatics ultimately cause an even greater increase in octane requirement. Moreover, some of the nitrogen-containing compounds currently used as deposit control additives and their mineral oil or polymer carriers in engines using unleaded fuels can also contribute significantly to ORI.

It is therefore particularly desirable to supply deposit control additives in doses sufficient to successfully control deposits in engine intake systems without themselves contributing significantly to the ORI problem.

In this regard, the hydrocarbyl poly(oxyalkylene) aminocarbamate dispersants are commercially successful fuel additives that control intake system deposits without themselves contributing significantly to the ORI problem. However, these additives are relatively expensive and this discourages their use in high doses.

At economical fuel concentrations, hydrocarbyl poly(oxyalkylene) aminocarbamates are not as effective at controlling deposits in the injectors or carburetor of modern internal combustion engines. The performance of these engines, which contain fuel injection/fuel distribution systems, can be significantly affected by relatively small amounts of deposits.

On the other hand, low molecular weight hydrocarbylamine and polyamine detergents are known to successfully control injector deposits. These amine detergents are similar to those previously described that have been used to keep carburetors clean. However, to control injector deposits, these detergents are used at fuel concentrations in the range of 40 to 70 ppm. Now it is known that such high doses of injector detergents have a negative effect on the control of deposits on intake valves and in the combustion chamber of engines.

An additional problem with some low molecular weight hydrocarbylamine and polyamine detergents containing primary or secondary amine functionality is the formation of a solid precipitate when the amine is exposed to carbon dioxide, such as exposure to carbon dioxide in the air. This precipitate is believed to be a carbamic acid adduct formed by the reaction of the primary or secondary amine with carbon dioxide. Whatever its chemical structure, the formation of such a precipitate is undesirable for reasons explained below.

Another problem associated with some low molecular weight amines, especially those containing polar substituents such as hydroxy groups, is the fact that these amines have high water solubility and can therefore be completely extracted from the hydrocarbon phase into the water phase upon contact with water. Therefore, such amines would have reduced effectiveness in hydrocarbon fuels.

In this regard, U.S. Patent No. 4,810,263 to Zimmerman et al. discloses an additive package for reducing and/or preventing fouling in a multi-port fuel injected engine comprising an amine oxide such as bis(2-hydroxyethyl)cocamine oxide and a demulsifier comprising one or more demulsifying agents selected from a reaction product of a fatty acid alkylamine and a solution of oxyalkylated alkylphenol formaldehyde resins and polyglycols. U.S. Patent No. 4,836,829 to Zimmerman et al. discloses a similar additive package comprising a tertiary amine such as bis(2-hydroxyethyl)cocamine, preferably in conjunction with an amine oxide, and a demulsifying agent. As noted in U.S. Patent No. 4,810,263, the amine oxide typically contains water from the manufacturing process that is difficult to remove entirely. As a result, the amine oxide is commercially available as an isopropyl alcohol solution containing from 6 to 8 weight percent water.

Mineral oil carriers are often used with either the amine detergents or the hydrocarbyl poly(oxyalkylene) aminocarbamate dispersants to aid in the removal and prevention of deposits. However, even with the addition of mineral oil carriers, neither group of fuel additives provides complete control of intake system deposits.

It would therefore be particularly desirable to combine an intake valve and combustion chamber deposit control additive, such as a hydrocarbyl poly(oxyalkylene) aminocarbamate dispersant, with an injector detergent, such as a low molecular weight amine or polyamine, and an effective amount of a carrier fluid to provide a multi-component, multi-functional fuel additive package that maximizes effective deposit control throughout the intake system and combustion chamber of engines and that does not itself significantly contribute to the octane requirement increase problem.

The selection of components for a multi-component, multi-functional deposit control fuel additive composition is not straightforward. The composition must provide effective deposit control at additive levels that are economical and with additives that do not contribute to ORI. It is also essential that the composition remain homogeneous, i.e., a single liquid phase, under all field conditions if the composition is to reliably deliver the expected deposit control performance when mixed with fuel and in actual engine operation.

In providing an effective fuel additive composition, maintaining a single liquid phase is critical. Typically, there is no practical means of rehomogenizing an additive composition once it has been delivered. If the bulk of the additive composition separates into two or more phases as a result of component incompatibility, neither phase will contain the effective combination of components intended for the fuel. Therefore, the overall deposit control performance of the fuel will be severely compromised. Moreover, the composition of additive delivered to the fuel will be erratic.

Phase separation of an incompatible composition can take many forms. Typically, phase separation first appears as a turbidity that eventually settles, either on top or on the bottom, depending on the relative densities of the two phases. Therefore, if the additive level in, for example, a storage tank is lowered, the interface between the phases may drop below the liquid withdrawal point, at which point the composition of the additive flowing into the fuel will change, possibly drastically.

Phase separation will also cause serious problems in the additive distribution or delivery system that delivers the additive composition to the fuel. If the phase separation involves two liquid phases, the heavier phase will collect at the bottom of the additive storage tank and at the low points of the additive delivery lines. This will result in the need for expensive and inconvenient periodic cleaning of the additive delivery system.

If the phase separation involved a solid separating from the bulk of the liquid additive composition, the effect would be more severe and immediate. Virtually all additive injection systems have fine mesh filters to protect the valves and seals in the injection pump. A solid phase would quickly clog these filters and seal the injector, and thus the filter would have to be cleaned before the injector was restarted. A separate solid phase would also require periodic cleaning of the additive storage tank. Thus, it is clear that a homogeneous additive composition is critical.

It is generally considered desirable to add a minor amount of a material exhibiting properties of a fuel/water demulsifier to fuel blends of additive compositions. The demulsifier must exhibit demulsifying properties when used in motor fuels at relatively low levels, such as 5 to 25 parts per million. However, it has been observed that even small doses of such a material in certain cases have a negative effect on the deposit inhibiting properties of the additive composition. Therefore, it is desirable to select a demulsifier which does not exhibit this negative effect. Moreover, for the reasons stated above, it is critical that the demulsifier remain homogeneous with the additive composition.

It is also generally beneficial to include a solvent or diluent in the additive composition. The primary function of this component is to reduce the viscosity of the composition at low temperatures. However, the solvent must be compatible with the additive components and economical.

Relevant state of the art

U.S. Patent Nos. 4,160,648 and 4,191,537 disclose hydrocarbyl poly(oxyalkylene) aminocarbamates as fuel additives. The use of a fuel-soluble carrier oil and additionally a demulsifier in combination with the hydrocarbyl poly(oxyalkylene) aminocarbamates is also disclosed.

The use of hydrocarbyl amines and hydrocarbyl polyamines as fuel additives is disclosed in U.S. Patent Nos. 3,438,757: 3,565,834: 3,574,576, 3,898,056 and 3,960,515.

U.S. Patent Nos. 3,898,056 and 3,960,515 disclose a mixture of high and low molecular weight hydrocarbyl amines used as detergents and dispersants at low concentrations in fuels. The high molecular weight hydrocarbyl amine contains at least one hydrocarbyl group having a molecular weight between about 1,900 and 5,000 and the low molecular weight hydrocarbyl amine contains at least one hydrocarbyl group having a molecular weight between about 300 and 600. The weight ratio of low molecular weight amine to high molecular weight amine in the mixture is maintained between about 0.5:1 and 5:1.

While these references disclose hydrocarbyl poly(oxyalkylene) aminocarbamates useful as dispersants and hydrocarbyl amines and polyamines useful as detergents, none of these references teach a homogeneous additive composition comprising a dispersant, detergent, carrier oil and demulsifier which, when mixed with fuel at low concentrations, provides effective control of deposits in the sanitation intake system while minimizing contribution to the ORI problem.

SUMMARY OF THE INVENTION

The present invention provides a new homogeneous fuel additive composition which contains:

(a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of about 1,000 to about 3,000;

(b) an injector detergent comprising a branched chain hydrocarbylamine having at least one basic nitrogen atom and an average molecular weight of from about 300 to about 700, wherein the hydrocarbyl portion is derived from polymers of C2 to C6 olefins;

(c) a fuel demulsifier which is homogeneous with the other components of said fuel additive composition, and

(d) a natural or synthetic carrier fluid.

The present invention further provides a fuel composition comprising a hydrocarbon boiling in the gasoline or diesel range and containing from 400 to 1,200 parts per million of the homogeneous fuel additive composition described above.

The present invention also relates to a fuel concentrate comprising an inert, stable, oleophilic organic solvent boiling in the range of 150° to 400°F (65.6-204.4°C) and about 5 to 50 weight percent of a homogeneous fuel additive composition of the invention.

Among other things, the present invention is based on the surprising discovery that the unique combination of dispersant, low molecular weight injector detergent, demulsifier and carrier fluid described herein provides complete control of intake deposits while minimizing the debilitating combustion chamber deposits correlated with ORI.

Furthermore, the use of a low molecular weight branched chain hydrocarbylamine as an injector detergent avoids the problem of precipitation associated with known amine detergents such as oleylamine.

DETAILED DESCRIPTION OF THE INVENTION

Essentially, the present invention addresses the problem associated with the fact that none of the prior art fuel additives, individually or in typically used concentration combinations, can provide complete control of deposits on the gasoline intake system. The present invention demonstrates a new formulation technology which provides maximum deposit control at each of the critical deposit forming areas while simultaneously minimizing the doses of each critical component. As a result, it is now possible to minimize the negative influence of each component on the overall intake system and combustion chamber deposit control performance.

The present invention describes a fuel additive composition which provides a homogeneous mixture of deposit control additives and carrier fluid in individual proportions significantly below the levels traditionally recognized for maintaining adequate intake system deposit control in their respective ranges of effectiveness, and an oil compatible demulsifier.

Therefore, the novel fuel additive composition of the present invention is a homogeneous mixture comprising the following components:

(a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of about 1,000 to about 3,000;

(b) an injector detergent comprising a branched chain hydrocarbylamine having at least one basic nitrogen atom and an average molecular weight of from about 300 to about 700, wherein the hydrocarbyl portion is derived from polymers of C2 to C6 olefins;

(c) a fuel demulsifier which is homogeneous with the other components of said fuel additive composition; and

(d) a natural or synthetic carrier fluid.

Generally, the homogeneous fuel additive composition of the invention will comprise about 10 to 70 weight percent aminocarbamate dispersant, about 1 to 10 weight percent hydrocarbylamine injector detergent, about 0.5 to 5 weight percent fuel demulsifier, and about 25 to 80 weight percent carrier fluid Although the present fuel additive composition may be used undiluted, it is often desirable to dilute the composition with an inert solvent or diluent to about 50 percent dilution.

The dispersant

The dispersant used in the homogeneous fuel additive composition of the invention is a hydrocarbyl poly(oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of about 1,000 to 3,000. Thus, the dispersant used can be said to contain a poly(oxyalkylene) component, an amine component and a carbamate linking group.

A. The poly(oxyalkylene) component

The hydrocarbyl terminated poly(oxyalkylene) polymers used to prepare the carbamates of the present invention are monohydroxy compounds, e.g., alcohols, often referred to as monohydroxy polyethers or polyalkylene glycol monocarbyl ethers or "protected" poly(oxyalkylene) glycols, and should be distinguished from the poly(oxyalkylene) glycols (diols) or polyols which are not hydrocarbyl terminated, i.e., are not protected. The hydrocarbyl terminated poly(oxyalkylene) alcohols are prepared by adding lower alkyl oxides such as oxirane, ethylene oxide, propylene oxide, butylene oxide, etc. to the hydroxy compound, ROH, under polymerization conditions, where R is the hydrocarbyl group protecting the poly(oxyalkylene) glycol. In the poly(oxyalkylene) component used in the present invention, the group R will generally contain from 1 to about 30 carbon atoms, preferably from 2 to about 20 carbon atoms, and is preferably aliphatic or aromatic, i.e., an alkyl or an alkylphenyl, where the alkyl is a straight or branched chain of from 1 to about 24 carbon atoms. More preferably, R is alkylphenyl, where the alkyl group is a branched chain of 12 carbon atoms derived from propylene tetramer and commonly referred to as tetrapropenyl. The oxyalkylene units in the poly(oxyalkylene) component preferably contain from 2 to about 5 carbon atoms, but one or more units with a higher carbon number may also be present. The poly(oxyalkylene) component used in the present invention is more fully described and exemplified in U.S. Patent No. 4,191,537.

Although the hydrocarbyl group on the hydrocarbyl poly(oxyalkylene) moiety will preferably contain from 1 to 30 carbon atoms, longer hydrocarbyl groups, particularly longer chain alkylphenyl groups, may also be used.

For example, alkylphenyl poly(oxyalkylene) aminocarbamates in which the alkyl group contains at least 40 carbon atoms, as described in U.S. Patent No. 4,881,945 to Buckler, are also contemplated for use in the present invention. The alkylphenyl group on the aminocarbamates of U.S. Patent No. 4,881,945 will preferably contain an alkyl group having from 50 to 200 carbon atoms, and more preferably an alkyl group having from 60 to 100 carbon atoms.

B. The amine component

The amine portion of the hydrocarbyl-terminated poly(oxyalkylene) aminocarbamate is preferably derived from a polyamine having from 2 to about 12 amine nitrogen atoms and from 2 to about 40 carbon atoms. The polyamine is preferably reacted with a hydrocarbyl poly(oxyalkylene) chloroformate to produce a hydrocarbyl poly(oxyalkylene) aminocarbamate fuel additive useful in the present invention. The chloroformate itself is derived from hydrocarbyl poly(oxyalkylene) alcohol by reaction with phosgene. The polyamine, which includes diamines, provides the product poly(oxyalkylene) aminocarbamate having an average of at least about one basic nitrogen atom per carbamate molecule, i.e., a nitrogen atom that is titratable with strong acid. The polyamine preferably has a carbon/nitrogen ratio of about 1:1 to about 10:1. The polyamine may be substituted with substituents selected from hydrogen, hydrocarbyl groups having from 1 to about 10 carbon atoms, acyl groups having from 2 to about 10 carbon atoms, and monoketone, monohydroxy, mononitro, monocyano, alkyl and alkoxy derivatives of hydrocarbyl groups having from 1 to 10 carbon atoms. It is preferred that at least one of the basic nitrogen atoms of the polyamine is a primary or secondary amino nitrogen. The polyamine component used in the present invention has been described in more detail and exemplified in U.S. Patent No. 4,191,537.

Hydrocarbyl, as used in describing the hydrocarbyl poly(oxyalkylene) and amine components used in this invention, refers to an organic radical consisting of carbon and hydrogen which may be aliphatic, alicyclic, aromatic, or combinations thereof, e.g., aralkyl. Preferably, the hydrocarbyl group will be relatively free of aliphatic unsaturation, i.e., ethylenic and acetylenic, especially acetylenic, unsaturation. The more preferred polyamine used in the scope of the present invention is a polyalkylene polyamine, e.g., an alkylenediamine, and e.g., substituted polyamines, e.g., alkyl and hydroxyalkyl substituted polyalkylene polyamines. Preferably, the alkylene group contains 2 to 6 carbon atoms, with preferably 2 to 3 carbon atoms between the nitrogen atoms. Examples of such polyamines are, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, di(trimethylene)triamine, dipropylenetriamine, tetraethylenepentamine, etc. Among the polyalkylenepolyamines, polyethylenepolyamine and polypropylenepolyamine having 2-12 amine nitrogen atoms and 2-24 carbon atoms are particularly preferred, and in particular, the lower polyalkylenepolyamines, e.g. ethylenediamine, diethylenetriamine, propylenediamine, dipropylenetriamine, etc., are most preferred.

C. The aminocarbamate

The poly(oxyalkylene) aminocarbamate fuel additive used in compositions of the present invention is prepared by linking the amine component and the poly(oxyalkylene) component via a carbamate bond. i.e.,

-O-C(O)- -.

wherein the oxygen can be considered as the terminal hydroxyl oxygen of the poly(oxyalkylene) alcohol component and the carbonyl group -C(O)- is preferably supplied by a coupling agent, e.g. phosgene. In the preferred manner of preparation, the hydrocarbyl poly(oxyalkylene) alcohol is reacted with phosgene to give a chloroformate and the chloroformate is reacted with the polyamine. The carbamate bonds are formed as the poly(oxyalkylene) chains and are attached to the nitrogen of the polyamine via the oxycarbonyl group of the chloroformate. Since more than one nitrogen atom of the polyamine may be present capable of reacting with the chloroformate, the aminocarbamate contains at least one hydrocarbyl poly(oxyalkylene) polymer chain attached to a nitrogen atom of the polyamine through an oxycarbonyl group, but the carbamate may contain from 1 to 2 or more such chains. It is preferred that the hydrocarbyl poly(oxyalkylene) aminocarbamate product contain an average of about 1 poly(oxyalkylene) chain per molecule (i.e., be a monocarbamate), although it is believed that this reaction route may result in mixtures containing appreciable amounts of di- or higher poly(oxyalkylene) chain substitution on a polyamine having some reactive nitrogen atoms. A particularly preferred aminocarbamate is alkylphenyl poly(oxybutylene) aminocarbamate in which the amine portion is derived from ethylenediamine or diethylenetriamine. Synthetic methods for avoiding higher degrees of substitution, methods of preparation, and other features of the aminocarbamates used in the present invention are described in more detail and exemplified in U.S. Patent No. 4,191,537.

The injector detergent

The injector detergent used in the homogeneous fuel additive composition of the present invention is a branched chain hydrocarbyl amine having at least one basic nitrogen atom and an average molecular weight of from about 300 to about 700 and wherein the hydrocarbyl portion is derived from polymers of C2 to C6 olefins.

In the amine injector detergent, the branched chain hydrocarbyl group is usually prepared by polymerizing olefins having 2 to 6 carbon atoms (ethylene being copolymerized with another olefin to obtain a branched chain). The branched chain hydrocarbyl group will generally have at least 1 branch per 6 carbon atoms along the chain, preferably at least 1 branch per 4 carbon atoms along the chain, and more preferably at least 1 branch per 2 carbon atoms along the chain. The preferred branched chain hydrocarbyl groups are polypropylene and polyisobutylene. The branches will usually consist of 1 to 2 carbon atoms, preferably 1 carbon atom, i.e., methyl. Generally, the branched chain hydrocarbyl group will contain about 20 to 40 carbon atoms.

In most cases, the branched chain hydrocarbyl amines are not a pure single product, but rather a mixture of compounds with an average molecular weight. Usually, the range of molecular weights will be relatively narrow, reaching the highest point near the stated molecular weight.

The amine component of the branched chain hydrocarbyl amines can be either a monoamine or a polyimine. The monoamine or polyamine component represents a broad class of amines having from 1 to 10 amine nitrogen atoms and having from 2 to 40 carbon atoms, with a carbon/nitrogen ratio of between about 1:1 and 10:1. In most cases, the amine component is not a pure single product, but rather a mixture of compounds having a major amount of the designated amine. For the more complex polyamines, the compositions will be a mixture of amines having as the major product the designated compound and minor amounts of analogous compounds.

When the amine component is a polyamine, it will preferably be a polyalkylenepolyamine, e.g. alkylenediamine. Preferably, the alkylene group will contain 2 to 6 carbon atoms, and more preferably 2 to 3 carbon atoms. Examples of such polyamines are ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

A particularly preferred branched chain hydrocarbylamine is polyisobutenylethylenediamine.

The branched chain hydrocarbylamine injector detergents used in the fuel additive composition of the invention are prepared by conventional methods known in the art. Such branched chain hydrocarbylamines and their preparations are described in detail in U.S. Patent Nos. 3,438,757; 3,565,804; 3,574,576; 3,848,056 and 3,960,515.

The demulsifier

The demulsifier used in the fuel additive composition of the present invention is a chemical agent which, when used in relatively low concentrations in gasoline compositions, promotes rapid coalescence of emulsified water to the point where it can be effectively separated from the main hydrocarbon by static gravity assisted by separation in a quiescent storage tank. The demulsifier agent is often a mixture of various chemical agents which in proper combination impart the desired demulsifying properties. These agents are typically selected from, but are not limited to, alkylphenol resins, polyoxyalkylene-based fluids, alkylaryl sulfonates, derivatives of fatty acids, and the like. A preferred demulsifier for use in this composition of the present invention is known as Tolad T-326, a commercially available product from Petrolite Corporation, Tretolite Division. St. Louis, Missouri, which contains a mixture of oxyalkylated alkylphenol-formaldehyde resins, polyoxyalkylene glycols and sodium aryl sulfonate in heavy aromatic naphtha.

In selecting a suitable fuel/water demulsifying agent, it is important that the fuel, when mixed with an effective deposit-controlling amount of a fuel additive, be able to repel water or become substantially emulsion-free within 15 to 30 minutes of contact with an aqueous phase. The fuel additive composition of the present invention, generally considered a dispersant, also has a tendency to promote emulsion formation when gasoline compositions containing the additive composition are contacted with water. At relatively low fuel concentrations, demulsifiers assist in demulsifying such emulsions and thereby help to clarify otherwise cloudy, wet fuels. It is important to note that demulsifiers, when used at concentrations greater than about 25 ppm, can also promote emulsification. Their dosage must therefore be carefully regulated and adapted to the physical/chemical characteristics of fuel compositions containing fuel additive components. Many demulsifiers meet this criterion, but will nevertheless not meet the criterion of compatibility with other components of the fuel additive composition.

The carrier fluid

The carrier fluid used in this invention is a chemically inert, hydrocarbon-soluble liquid vehicle which substantially increases the non-volatile residue (NVR) or solvent-free liquid fraction of the fuel additive composition while not overwhelmingly contributing to the increase in octane requirement. The carrier fluid may be a natural or synthetic oil, such as a Mineral oil, refined petroleum oils, synthetic polyalkanes and alkenes, synthetic polyoxyalkylene derived oils, and the like, such as those described in U.S. Patent No. 4,191,537 to Lewis. These carrier fluids are believed to act as a vehicle for the dispersant and detergent and to assist in removing and retaining deposits.

The carrier fluid used in the present invention must also be capable of forming a homogeneous mixture with the other components of the present fuel additive composition. Examples of suitable carrier fluids include Chevron Neutral Oil 500R and Chevron Neutral Oil 600P, available from Chevron U.S.A. Inc., San Francisco, California.

Fuel compositions

The fuel additive composition of the present invention is typically employed as a hydrocarbon distillate fuel boiling in the gasoline or diesel range. The proper concentration of this additive composition is important to achieve the desired detergent and dispersant effects depending on the type of fuel employed, the presence of other additives, and the like. Typically, however, about 400 to 1,200 parts per million (ppm) of the present fuel additive composition are required in the base fuel to achieve the best results. With respect to individual components, fuel compositions containing the homogeneous fuel additive composition of the present invention will typically contain about 100 to 225 ppm aminocarbamate dispersant, about 10 to 70 ppm hydrocarbylamine injector detergent, about 5 to 25 ppm demulsifier, and about 250 to 800 ppm carrier fluid.

The deposit control fuel additive composition of the present invention can also be formulated as a concentrate using an inert, stable, oleophilic organic solvent boiling in the range of about 15°C to 400°F (65.5°C to 204.4°C). Preferably, an aliphatic or aromatic hydrocarbon solvent is used, such as benzene, toluene, xylenes, or higher boiling aromatics or aromatic diluents. Also, aliphatic alcohols having about 3 to 8 carbon atoms, such as isopropanol, isobutylcarbinol, n-butanol, and the like, are suitable in combination with hydrocarbon solvents for use with the additive composition of the present invention. In the fuel concentrate, the amount of the additive composition present will normally be at least 5% by weight and will usually not exceed 50% by weight and will preferably be between 10 and 30% by weight.

Other fuel additives can also be added to gasoline fuels, such as anti-knock agents, e.g. methylcyclopentadienylmanganese tricarbonyl, tetramethyl or tetraethyl lead, tert.butylmethyl peroxide and various oxygenates, such as methanol, ethanol and t.butylmethyl ether. Lead scavengers, such as aryl halides, e.g. dichlorobenzene or alkyl halides, e.g. ethylene dibromide, can also be added. In addition, antioxidants and metal deactivators can be present.

Other well-known additives such as pour point depressants, flow improvers, cetane improvers, etc. can be used in diesel fuels.

The following examples are offered to specifically illustrate this invention. However, these examples and explanations should not be construed as limiting the scope of this invention in any way.

EXAMPLES EXAMPLE 1 Preparation of an aminocarbamate dispersant useful in this invention

A dispersant useful in this invention was prepared in a manner similar to that described in Lewis, U.S. Patent No. 4,160,648, Examples 6-8, except that diethyltriamine was used in place of ethylenediamine. In this example, a tetrapropenylphenol was reacted stepwise with butylene oxide, phosgene and diethylenetriamine to obtain a high molecular weight tetrapropenyl poly(oxybutylene) aminocarbamate, hereinafter referred to as polyetheramine (PEA).

EXAMPLE 2 A hydrocarbylamine injector detergent useful in this invention

An injector detergent (ID) was prepared in a manner similar to that described by Honnen, U.S. Patent No. 3,438,757, Example 2. In this example, a C30 polyisobutene having a molecular weight of about 420 was reacted stepwise with chlorine and ethylenediamine to produce a polyisobutene-ethylenediamine adduct.

EXAMPLE 3 Carrier fluids useful in this invention

Chevron Neutral Oil 500R and Chevron Neutral Oil 600P were used as carrier fluids (CF) in the following examples. Chevron Neutral Oil 500R is a highly refined base oil with a pour point of -12ºC (max.) and a viscosity of 98.6 cSt at 40ºC. Chevron Neutral Oil 600P is a highly refined base oil with a pour point of 10ºF (-12.2ºC) and a viscosity of 129.5 cSt (mm2/s) at 37.8ºC.

EXAMPLE 4 A demulsifier useful in this invention

The demulsifier (D) used in these examples to illustrate the present invention was a commercially available demulsifier (from Petrolite Corporation, Tretolite Division, St. Louis, MO) identified by the manufacturer as Tolad T-326. This demulsifier comprises a mixture of oxyalkylated alkylphenol-formaldehyde resins, polyoxyalkylene glycols and sodium aryl sulfonate (1 to 5 weight percent) in heavy aromatic naphtha (30 to 60 weight percent). Tolad T-326 is reported to have a flash point, SFCC, of 114°F (45.5°C), a pour point, ASTM D-97, of 5°F (-15°C) and a viscosity of 263 SUS at 60°F (57.3 mm2/s 15.5°C).

EXAMPLE 5 Demulsibility test

The procedure described by ASTM Method D-1094 was used to test demulsibility. Here, the fuel phase and interface are evaluated for clarity and persistence of a boundary emulsion layer. The fuel additive compositions were tested and rated numerically on a scale of one to four. The number "one" was the highest rating for clarity and "one" was the highest rating for persistence of a boundary emulsion layer.

The fuel additive composition of the invention, exemplified by Sample 6A below, met the requirement of a rating of one in both of these tests.

EXAMPLE 6 Production of fuel additive compositions

Two fuel additive compositions were prepared. 150 parts of the polyetheramine of Ex.1, 25 parts of the injector detergent of Ex.2, 12 parts demulsifier, 212 parts Chevron Solvent 25 (which is a blend of C-9 mixed aromatics available from Chevron, U.S.A. Inc., San Francisco, California), and 450 parts Chevron Neutral Oil 500R (Ex. 3) were mixed at room temperature with stirring in a 200 ml flask.

Sample 6A contained Tolad T-326 (as described in Ex. 4) as a demulsifier. Sample 6B contained L-1562 as a demulsifier. L-1562 is a commercially available demulsifier purchased from Petrolite Corporation, St. Louis, MO. A third additive composition, Sample 6C, contained oleylamine as an injector detergent and is shown for comparison purposes. Oleylamine is a low molecular weight, straight C18 chain primary amine.

EXAMPLE 7 Compatibility test

The compatibility test used was a modification of the procedure described by ASTM Method D-2273, except that since a significant amount of diluent solvent (Chevron Solvent 25, a mixture of C-9 mixed aromatics) was already present in these compositions, this test was conducted without further dilution. The test was conducted in two parts. In Part A, the samples prepared using the procedure of Example 6 were held at ambient or room temperature (about 20-25°C) for 24 hours. Each sample was then visually inspected for a secondary phase. If a secondary phase was observed, the sample was centrifuged and the volume percent of the secondary phase was determined. If no secondary phase was observed, Part B of this test was conducted.

In Part B, samples were cooled to 0ºF (-17.7ºC) and held at that temperature for 24 hours. Each sample was then visually inspected for a secondary phase. If a secondary phase was observed, the sample was centrifuged and the volume percent of the secondary phase was determined.

Results are reported as volume percent of secondary phase sediment after centrifugation, which was either a liquid, a solid, or a combination. Sediment (or secondary phase) contents exceeding 0.005 vol% are considered unacceptable.

The fuel additive composition of this invention (Sample 6A) does not possess any measurable volume percent of secondary phase under these test conditions. However, when L-1562 was used as the demulsifier (Sample 6B) or when oleylamine was used as the injector detergent (Sample 6C), significant and unacceptable levels of secondary phase were observed. Vol% Secondary Phase Fuel Additive Composition Part Sample Chevron Parts Chev. Sol. Comparison Oleylamine

In Sample 6B, a liquid secondary phase was observed at room temperature, demonstrating the incompatibility of the demulsifier with the other components of the fuel additive composition.

Sample 6C, which contained oleylamine as an injector detergent, was centrifuged after cooling to 0ºF (-17.7ºC) and showed a small volume (0.05 vol.%) of insoluble solid sediment. It therefore did not meet the criterion that sediment levels must not exceed 0.005 vol.%.

EXAMPLE 8 Inlet nozzle deposition test

A standard grade unleaded gasoline was mixed with fuel additive packages of this invention so that the fuel contained the following ingredients:

8A: 150 ppm of PEA (Ex. 1)

25 ppm of ID (Ex. 2)

450 ppm of CF (Example 3, Chevron 600 P)

12 ppm of D (T-326)

8B: 150 ppm of PEA (Ex. 1)

25 ppm of D (Ex. 2)

450 ppm of CF (Example 3, Chevron 500 R)

12 ppm of D (T-326)

The gasolines were tested for effectiveness in keeping the intake nozzle clean using a procedure that used a 1981 Pontiac 2.5-liter engine mounted on an engine test bench and operated for 90 hours. ran. This test simulated a difficult field test operation characterized by light load driving conditions. The effectiveness of an additive package is determined by averaging the weights of accumulated intake nozzle deposits obtained at the end of the test and comparing these results with those obtained using identical test conditions and using the unadjusted fuel. A good fuel additive package capable of keeping the entire intake system completely clean will typically reduce intake nozzle deposits for the base gasoline.

Using the above test conditions, the non-adjusted base fuel test resulted in an average of 1,090 milligrams of deposits per inlet nozzle. The same gasoline containing a fuel additive package of this invention using Chevron Neutral Oil 600P, Example 8A, resulted in an average of 23 milligrams of deposits per inlet nozzle. In the above comparison between the base fuel and the adjuvanted fuel containing Chevron Neutral Oil 500R, Example 8B, we observed an average of 299 milligrams of inlet nozzle deposits. These results are summarized below. Fuel mixture containing: Average deposit weights No additive (base case)

In both Figures 8A and 8B, the average deposit weight is below the base case, demonstrating the effectiveness of the fuel additive composition of the present invention.

EXAMPLE 9 Octane requirement increase test

This test measures the potential that any gasoline additive can have to increase the octane requirement of gasoline-fueled engines. Over time, due to the buildup of deposits in the combustion chamber, a higher octane gasoline is required to minimize engine knock. Gasolines without additives contribute a base level of deposits which typically require a fuel having an octane rating four numbers higher than that of the initial fuel used to win the test to minimize the increase in engine knock condition. Gasoline additives contribute to this problem to varying degrees, and the magnitude of this contribution can be measured by comparisons with engine tests using additive-added fuel. The difference in ORI observed between tests is that additional gain of increased octane required to further minimize engine knock and is typically referred to as the octane requirement increase attributable to the gasoline additive package itself. This value is typically referred to as the "additive ORI number."

This approach uses a 1975 Toyota 2.2-liter engine mounted on an engine stand and equipped with a control system to carefully regulate the test conditions and engine operating cycles. The engine is first run for fifteen hours on a relatively clean-burning, additive-free alkylate fuel. At this time, the octane requirement is determined and the fuel is changed to a mixture of 70% unleaded conventional gasoline and 30% FCC heavy gasoline. The FCC heavy gasoline component is used to control the rate of deposit accumulation in the combustion chamber. during this phase of the test. After an additional 110 hours of engine operation, the final measurement of the octane requirement is taken.

When the fuel additive package of this invention was tested in this manner, it contributed one-half octane more than the octane requirement observed for the unadditive fuel (Test 9A). This increase was considerably less than that observed for a commercial gasoline additive package consisting of a heavy polybutene amine prepared from a polybutene having an average of 100 carbons per molecule and an average molecular weight of about 1,450, which is reacted stepwise with chlorine and ethylenediamine, and a large dose of carrier oil (Test 9B). Fuel containing: ORI number increase over base Base: No additive Test Chevron 500R 250 ppm heavy polybutenamine

Claims (16)

1. Homogeneous fuel additive composition with: (a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of about 1,000 to about 3,000; (b) an injector detergent comprising a branched chain hydrocarbylamine having at least one basic nitrogen atom and an average molecular weight of from about 300 to about 700, wherein the hydrocarbyl portion is derived from polymers of C2 to C6 olefins: (c) a fuel demulsifier which is homogeneous with the other components of the fuel additive composition, and (d) a natural or synthetic carrier fluid. 2. The fuel additive composition of claim 1, wherein the hydrocarbyl group in component (a) contains 1 to about 30 carbon atoms. 3. A fuel additive composition according to claim 1 or 2, wherein the hydrocarbyl group in component (a) is an alkylphenyl group. 4. A fuel additive composition according to claim 3, wherein the alkyl portion in the alkylphenyl group is tetrapropenyl. 5. A fuel additive composition according to any preceding claim, wherein the amine portion of the aminocarbamate is derived from a polyamine having 2 to 12 amine nitrogen atoms and 2 to 40 carbon atoms. 6. A fuel additive composition according to claim 5, wherein the polyamine is a polyalkylene polyamine having 2 to 12 amine nitrogen atoms and 2 to 24 carbon atoms. 7. A fuel additive composition according to claim 6, wherein the polyalkylene polyamine is selected from the group of ethylenediamine, propylenediamine, diethylenetriamine and dipropylenetriamine. . A fuel additive composition according to any preceding claim, wherein the poly(oxyalkylene) portion of component (a) is derived from C2 to C5 oxyalkylene units. 9. A fuel additive composition according to any preceding claim, wherein the hydrocarbyl poly(oxyalkylene) aminocarbamate of component (a) is an alkylphenyl poly(oxybutylene) aminocarbamate, wherein the amine portion is derived from ethylenediamine or diethylenetriamine. 10. A fuel additive composition according to any preceding claim, wherein the branched chain hydrocarbyl portion of component (b) is polypropenyl or polyisobutenyl. 11. A fuel additive composition according to any preceding claim, wherein the amino group of the branched chain hydrocarbylamine of component (b) is selected from the group of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine. 12. A fuel additive composition according to any preceding claim, wherein the branched chain hydrocarbylamine of component (b) is a polyisobutenylethylenediamine. 13. A fuel additive composition according to claim 1, wherein component (a) is an alkylphenyl poly(oxybutylene) aminocarbamate wherein the amine portion is derived from ethylenediamine or diethylenetriamine, and component (b) is a polyisobutenylethylenediamine. 14. A fuel composition comprising a hydrocarbon boiling in the gasoline or diesel range, and from about 400 to about 1,200 parts per million of a homogeneous fuel additive composition as claimed in any of claims 1 to 13. 15. The fuel composition of claim 14, wherein the fuel composition contains: about 100 to 225 ppm dispersant of component (a), about 10 to 70 ppm injector detergent of component (b), about 5 to 25 ppm demulsifier of component (c), and about 250 to 800 ppm carrier fluid of component (d). 16. A fuel concentrate comprising an inert, stable, oleophilic organic solvent boiling in the range of 150° to 400°F (65.6 to 204.4°C) and about 5 to 50 weight percent of a homogeneous fuel additive composition as claimed in any one of claims 1 to 13.