CA2049954C - 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 in-jection detergent comprising a branched-chain hydrocarbyl amine having at least one basic nitrogen atom and an average molec-ular 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 syn-thetic carrier fluid.

Description

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WO h1/1Z303 PC.'T/US91/0093A

05 Numerous deposit-forming substances are inherent in , 06 hydrocarbon fuels. These substances when used in internal 07 combustion engines tend to form deposits on and around 08 constricted areas of the engine contacted by the fuel.
09 Typical areas commonly and sometimes seriously burdened by the.formation of deposits include carburetor air bleeds; the 11 throttle body and venturies, engine intake valves and 12 ports, fuel injection nozzles, cylinder head and piston top 13 combustion chamber surfaces, etc.

Deposits adversely affect the operation of vehicles using 16 hydrocarbon fuels. For example, deposits on the carburetor 17 throttle body and venturies increase the fuel-to-air ratio 18 of the gas mixture to the combustion chamber thereby ' 19 increasing the amount of unburned hydrocarbon and carbon monoxide discharged from the chamber. High Euel-to-air 21 ratios also reduce the gas mileage obtainable from the 22 vehicle.

Deposits on the engine intake valves that are sufficiently heavy, restrict the gas mixture flow into the combustion 26 chamber. This restriction starves the engine of air and 27 fuel and results in a loss of power. Deposits on the valves 28 also increase the probability of valve failure due to 2g burning and improper valve seating. In addition, these deposits may break off and enter the combustion chamber 31 possibly resulting in mechanical damage to the piston top, 32 piston rings, cylinder head, etc., WO g1/12303 PCT/U591/009~:~.f O1 It has long~been known that the formation of these deposits 02 can be inhibited as well as removed by incorporating an 03 active detergent into the fuel. These detergents function 04 to cleanse these deposit-prone areas of the harmful 05 deposits, thereby enhancing engine performance and 06 longevity.

08 The first generation of fuel additives consisted of 09 detergents which helped to maintain the cleanliness of critical carburetor elements. These initial fuel additives 11 were typically used in small doses, generally in the range 12 of 15 to 30 ppm. Unfortunately, these small doses of 13 additive provided little deposit control in other parts of 14 combustion engines.
16 The next generation of fuel additives generally provided 17 improved deposit control in the intake system including 18 intake manifold hotspots, runners, intake valve ports, and 19 intake valves. The extent of deposit control was typically modulated by controlling additive dose, usually in the range 21 of 70 to 2,000 ppm. However, as additive doses increased to 22 high levels, the accumulation of combustion chamber deposits 23 became a significant problem for reasons which will become 24 apparent hereinbelow.
26 zn recant years the wide-spsead use of non-leaded gasoline 27 has further complicated the use of detergent-type gasoline 2g additives. In automobile engines that require the use of 2g non-leaded gasolines (to~prevent disablement of catalytic converters used to reduce emissions?. it has been found 31 difficult to provide gasoline of sufficient octane to pre-32 vent knocking and the concomitant damage which it causes.
33 The problem arises from an octane requirement increase, O1 herein called "ORI", which results from deposits formed by .
02 the use of commercial gasolines.

04 The basis of the ORI problem is as follows: each engine, 05 when new, requires a certain minimum octane fuel in order to 06 operate satisfactorily without pinging and/or knocking, 07 and/or after run. As the engine is operated an any Og gasoline, this minimum octane requirement increases. This Og is apparently caused by formation of deposits in the com-bustion chamber. In mast cases, if the engine is operated 11 on the same fuel for a prolonged period, the ORI will reach 12 an equilibrium. Equilibrium is typically reached after 13 5,000 to 15,000 miles of automobile operation.

The octane requirement increase in a particular engine used 16 with commercial gasolines will vary at equilibrium from 4 to 1' 6 octane units to as high as 12 or l5 units, depending upon 1g the gasoline compositions, engine design and type of oper-lg ation. The seriousness of the problem is thus apparent. A
typical automobile with a research octane requirement of 85, 21 when new, may after a few months of operation require 97 22 research octane gasoline for proper operation, and little 23 unleaded gasoline of that octane is available. The ORI
24 problem also exists to some degree with engines operated on Z5 leaded fuels. U.5. Patent Nos. 3,144,311; 3,146,203; and 26 4,247,301 disclose lead-containing fuel compositions having 2~ reduced ORI properties.

2g The ORI problem is compounded by the fact that the most common method for increasing the octane rating of unleaded 31 gasoline is to increase its aromatic content. These aroma-32 tics, however, eventually cause an even greater increase in 33 the octane requirement. Moreover, some of the nitiogen-34 containing compounds presently used as deposit-control ~0~~'~a~
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WO 91IIZ303 PCT/US911009~a H
O1 additives~and their mineral oil or polymer carriers may also 02 significantly contribute to ORI in engines using unleaded 03 fuels.

05 It is, therefore, particularly desirable to provide degosit 06 control additives at doses sufficient to effectively control 07 the deposits in .intake systems of engines without themselves 08 significantly contributing to the ORI problem.
0g I0 In this regard, the hydrocarbyl poly(oxyalkylene) 11 aminoca.rbamate dispersants are commercially successful fuel 12 additives which control induction system deposits without 13 significantly contributing to the ORI problem. However, I4 these additives are relatively expensive and this 15 discourages their use in high concentrations.

,17 At economical fuel concentrations, the hydrocarbyl 18 poly(oxyalkylene) aminocarbamates are not quite as effective 19 at controlling deposits in the injectors or carburetor of ZO mode'rn combustion engines. The performance of these Z1 engines, Which contain fuel injection fuel delivery systems, 22 can be substantially upset by relatively small amounts of 23 deposits.

25 On the other hand, low molecular weight hydrocarbyl amine 2~ and polyamine detergents are known to effectively control 27 deposits in injectors. These amine detergents are similar 2g to those described easlier that were used to maintain clean 2g carburetors. However, to control deposits on injectors, 3p these detergents are used at fuel concentrations in the 31 range of 40 to 70 ppm. It is now known that such high doses 32 of injector detergents negatively impact the control of 33 deposits on intake valves and in the combustion chamber of 34 engines.

~U~3~JJ a., W~ 91/12303 ~ PLTJUS91/00934 O1 An additional problem with some low molecular weight 02 hydrocarbyl amine and polyamine detergents that contain a 03 primary or secondary amine functionality is the formation of 04 a solid precipitate when the amine is exposed to carbon 05 dioxide, such as exposure to the carbon dioxide in air. It 06 is believed that this precipitate is a carbamic acid adduct 07 formed by reaction of the primary or secondary amine with 08 carbon dioxide. whatever its chemical structure, formation 09 of such a precipitate is undesirable for reasons which will be explained hereinbelow.

I2 A further problem associated with some low molecular weight 13 amines; particularly those containing polar substituents 14 such a.s hydroxy groups, is the fact that these amines have a 1S high water solubility, and therefore, on contact with water, 16 can be completely extracted out of the hydrocarbon phase and 17 into the water phase. As a result, such amines would have I8 reduced effectiveness in hydrocarbon fuels.

In this regard, U.S. Patent No. 4,810.263 to Zimmerman et 21 al. discloses an additive package for reducing and/or 22 preventing fouling in a multiport fuel-infected engine which 23 contains an amine oxide, such as bis(2-hydroxy ethyl) 24 cocamine oxide, and a demulsifier comprising one or more demulsifying agents selected from a fatty acid alkylamine 26 reaction product and a solution of oxyalkylated alkylphenol 27 formaldehyde resins and polyglycols. U.S. Patent 28 No. 4,836,829 to Zimmerman et al discloses a similar addi-2g tive package which contains a tertiary amine, such as bis(2-hydroxy ethyl) cocamine, preferably in combination 31 with an amine oxide. and a demulsifying agent. As noted in 32 U.S. Patent No. 4,810,263, the amine oxide typically has 33 water present from the manufacturing process, which is 34 difficult to comgletely remove. As a result, the amine VfO 91/12303 ~ PGT/US91/OOgs4 O1 oxide is commercially available as an isopropyl'alcohol 02 solution which contains from 6 to 8 weight percent water.

04 Frequently, mineral oil carriers are used with either the OS amine detergents or the hydrocarbyl poly(oxyalkylene) 06 aminocarbamate dispersants to assist in rsemaving and 07 preventing deposits. However, even with t:he addition of 0$ mineral oil carriers, neither group of fuel additives 09 provides complete intake system deposit control.-1I It would, therefore, be particularly desirable to combine an 12 intake valve and combustion chamber degosit control addi-13 tive, such as a hydrocarbyl poly(oxyalkylene) aminocarbamate 14 dispersant, with an injector detergent, such as a low I5 molecular weight amine or polyamine, and an effective amount I6 of a carrier fluid to provide a multi-component, multi-17 functional fuel additive package which maximizes effective 1g control of deposits throughout the entire intake system and 19 combustion chamber of engines, and which itself does not significantly contribute to the octane requirement increase 21 problem.

23 The choice of components for a mufti-component, 24 mufti-functional deposit control fuel additive composition is not straightforward. The composition must provide 26 effective deposit control at additive levels which are 2~ economical, and with additives which do not contribute to 28 ORI. It is also essential that the composition remains 29 homogeneous, i.e., a single liquid phase, under all field conditions, if the composition is to dependably deliver the 31 expected deposit control performance when blended with fuel 32 and in actual engine service.

~t VVO 91/1Z303 IP~CT/US91/~0934 O1 In providing an effective fuel additive composition, 02 maintaining a single liquid phase is critical. Typically, 03 there are no practical means to re-homogenize an additive 04 composition once distributed to the field. If the bulk , 05 additive composition separates into two or more phases, as a 06 result of component incompatibility, neither phase will 07 contain the effective combination of components intended for 08 the fuel. Therefore, the overall deposit control per-09 formance of the fuel will be seriously degraded.
Furthermore, the composition of additive delivered to the 12 fuel will be erratic.

I3 The phase separation of an incompatible composition can take 14 many forms. Typically, the phase separation appears first as a haze Which eventually settles out, either up or down, I6 depending on the relative densities of the two phases. Thus 17 as the level of additive in, for example, a storage tank is 1g drawn down, the interface between the phases may pass below 1g the liquid draw point, at which time the composition of ZO additive flowing into the fuel will change, perhaps Zl drastically.

23 A phase separation will also cause serious problems in the 24 additive distribution system which distributes the additive ZS composition to the fuel. If the phase separation involves 26 two liquid phases, the heavier phase will collect on the 27 bottom of the additive storage tank and at the low points of Zg the additive delivery lines. This will result in the need 29 for expensive and inconvenient periodic cleanout of the 30 additive distribution equipment.

32 If the phase separation involves a solid separating from the 33 bulk liquid additive composition, the effect would be more 34 serious and immediate. Virtually all additive injection ~~~~~5~ ~_ VbrO 91/12303 PCTlUS9IlfHD~:..:e O1 systems have fine-mesh filters to pcotect the valves and 02 seals in the injection Bump. A solid phase would rapidly 03. plug these filters and shut down the injector, thus 04 requiring that the filter be cleaned before restarting the 05 injector. A separate solid phase would also require the 06 periodic cleaning of the additive storage tank. The 0? criticality of a homogeneous additive composition is thus 08 apparent.

IO It is generally considered beneficial to include a minor I1 amount of a material which has fuel/water demulsifirr I2 properties in fuel blends of additive compositions. The 13 demulsifier must exhibit demulsification properties when 14 utilized in motor fuels at relatively low levels, such -as 5 15 to 25 parts per million. However, it has been observed that 16 even low dosages of such material can, in certain instances, I? have a negative effect on the deposit-inhibiting properties 18 of the additive composition. Consequently, it is desirable 1g to choose a demulsifier which does not exhibit this negative 20 effect. In addition, it is critical that the demulsifier 21 remain homogeneous with the additive composition for reasons 22 cited hereinabove.

24 It is also generally beneficial to include a solvent or 25 diluent in the additive composition. The primary function 26 of this component' is to reduce the low-temperature viscosity 2? of the composition. The solvent must however be compatible 28 with the additive components and economical.

30 Relevant Art 32 ~.8. Patent Nos. 4,160,648 and 4,191,537 disclose 33 hydrocarbyl poly(oxyalkylene) aminocarbamates as fuel 34 additives. The use of a fuel-soluble carrier oil and, WQ ~1/I2303 Pt.T/US91100934 O1 additionally, a demulsifier in combination with the 02 hydrocarbyl poly(oxyalkylene) aminocarbamates is also 03 disclosed.

05 The use of hydrocarbyl amines and hydrocarbyl polyamines as 06 fuel additives is disclosed in U.S. Patent Nos.:

O8 3,438,757; 3,898,056; and Og 3,565,804; 3,960,515 3,574,576 12 U.S. Patent Nos. 3,898,056 and 3,960,515 disclose a mixture 13 of high and low molecular weight hydrocarbyl amines used as 14 detergents and dispersants at low concentrations in fuels.
The high molecular weight hydrocarbyl amine contains at 16 least one hydrocaryl group having a molecular weight from 17 about 1,900 to 5,000 and the low molecular weight hydro-18 carbyl amine contains at least one hydrocarbyl,group having 1g a molecular weight from about 300 to 600. The weight ratio of low molecular weight amine to high molecular weight amine 21 in the mixture is maintained between about 0.5:1 and 5:1.

23 while these references disclose hydrocarbyl poly(oxyalkylene) 24 aminocarbamates useful as dispersants and hydrocarbyl amines and polyamines useful as detergents, none of these references 26 teach a homogeneous additive composition comprising a dis-27 persant, detergent, carrier oil and demulsifier which, when 2g mixed with fuel at low concentrations, provides effective 2g deposit control throughout the entire intake system while minimizing contribution to the olti problem.

i~VO 9i/12303 P~If'/LJS9I lOOys4 ID

03 The present invention provides a novel homogeneous fuel 04 additive composition which comprises:
OS
06 (a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) 07 aminocarbamate having at least one basic nitrogen atom 08 and an average molecular weight of about 1,000 to about 09 3,000;
IO
11 (b) an injector detergent comprising a branched-chain 12 hydrocarbyl amine having at least one basic nitrogen 13 atom and an average molecular weight of about 300 to ,14 about 700, wherein the hydrocarbyl moiety is derived 15 ~rom polymers of C2 to C6 olefins;

I? (c) a fuel demulsifier which is homogeneous with the other 18 components of said fuel additive composition) and 20 (d? a natural or synthetic carrier fluid.

22 The present invention further provides a fuel composition 23 comprising a hydrocarbon boiling in the gasoline or diesel 24 range and from about 400 to 1,200 parts per million of the 2$ homogeneous fuel additive composition described above.

27 The present invention is also concerned With a fuel 28 concentrate comprising an inert stable oleophilic organic 29 solvent boiling in the range of 150° to 400°F and from about 30 S to 50 weight percent o~ the homogeneous fuel additive 3I composition of the invention.

33 Among other factors, the present~invention is based on the 34 surprising discovery that the unique combination of ~~4~~~~
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WO gl/1Z303 PGTIUS91/00934 9l O1 dispersan~, low molecular weight injector detergent, 02 demulsifier and carrier fluid described herein provides com-03 plate intake deposit control while minimizing debilitating 04 combustion chamber deposits, which correlate to ORI.

06 In addition, the use of a low molecular weight branched 07 chain hydrocarbyl amine as an injector detergent avoids the 08 precipitation problem associated with known amine deter-Og gents, such as oleyl amine.

11 DETAILED DESCRIPTION OF THE INVENTIaN

13 In essence, the present invention addresses the problem 14 associated with the fact that none of the prior art fuel ZS additives can singly, or in typical use concentration com-I6 binations, grovide complete gasoline intake system deposit I7 control. The instant invention demonstrates a new formulat-18 ing technology which provides maximum deposit control in Ig each critical deposit forming area while at the same time ZO minimizing the doses of each critical ingredient. As a 21 consequence, it is now possible to minimize the negative ZZ impact of each individual ingredient upon overall intake Z3 system and combustion chamber deposit control performance.
2'4 Z5 The instant invention describes a fuel additive composition 26 which provides a homogeneous mixture of deposit control .Z7 additives and carrier fluid, in individual proportions Z8 significantly below tha levels historically recognized for Zg maintaining adequate intake system deposit control in their 30 respective areas of effectiveness, and an oil compatible 31 demulsifier.
32 _ ._.
WO 91112303 FCT/US9~t00~5~a4 /~
O1 Accordingly, the novel fuel additive composition of the 02 present invention is a homogeneous mixture which comprises A3 the following components:

05 (a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) OS aminocarbamate having at Least one basic nitrogen atom 07 and an average molecular weight of about 1.000 to about 08 3,000, (b) an injector detergent comprising a branched-chain 1I hydrocarbyl amine having at least one basic nitrogen 12 atom and an average molecular weight of about 300 to 13 about 700, wherein the hydrocarbyl moiety is derived 14 from polymers of C2 to C6 olefins;
16 (c) a fuel demulsifier which is homogeneous with the other 17 components of said fuel additive composition) and 19 (d) a natural or synthetic carrier fluid.
21 In general, the homogeneous fuel additive composition of the 22 invention will contain about 10 to 70 weight percent of the Z3 aminocarbamate dispersant, about 1 to 10 weight percent of 24 the hydrocarbyl amine injector detergent, about 0.5 to Z5 5 weight percent of the fuel demulsifier and about 25 to 26 80 weight percent of the carrier fluid. Although the 27 present fuel additive composition can be used neat, it is 28 often desirable to dilute the composition with a.n inert 29 solvent or diluent, up to about 50 percent dilution.
3I The Dispersant 33 The dispersant employed in the homogeneous fuel additive 34 composition of the invention is a hydrocarbyl fy0 91!12303 PCTlUS91l00934 ~3 Ol poly(oxyalkylene) aminocarbamate having at least one basic 02 nitrogen atom and an average molecular weight o~f about 1,000 03 to 3,000. Thus the dispersant employed can be said to 04 contain a poly(oxyalkylene) component, an amine component 05 and a carbamate connecting group.

0? A. The Poly(oxyalkylene.) Component 09 The hydrocarbyl-terminated poly(oxyalk~Ylene) polymers IO which are utilized in preparing the carbamates of the 11 present invention are monohydroxy compounds, e.g., 12 alcohols, often termed monohydroxy polyethers, or 13 polyalkylene glycol monocarbyl ethers, or "capped"
14 poly(oxyalkyle,ne> glycols, and are to be distinguished 15 from the goly(oxyalkylene) glycols (diols), or polyols, 16 which are not hydrocarbyl-terminated, i.e., are not 1? capped. The hydrocarbyl-terminated poly(oxyalkylene) 18 alcohols are produced by the addition of lower alkylene !g oxides, such as oxirane, ethylene oxide, propylene 20 oxide, butylene oxide, etc. to the hydroxy compound, 21 RAH, under polymerizatian conditions, wherein R is the 22 hydrocarbyl group which caps the poly(oxyalkylene) 23 chain. In the poly(oxyalkylene) component employed in 24 the present invention, the group R will generally 25 contain from 1 to about 30 carbon atoms, preferably from 26 2 to about 20 carbon atoms and is preferably aliphatic 2? or aromatic, i.e., an alkyl or alkyl phenyl wherein the 28 alkyl is a straight or branched-chain of from 1 to about 2g 24 carban atoms. More preferably, R is alkylphenyl 30 wherein the alkyl group is a branched-chain of 12 carbon 31 atoms, derived from propylene tetramer, and commonly 32 referred to as tetrapropenyl._ The oxyalkylene units in 33 the poly(oxyalkylene) component preferably contain from 34 2 to about 5 carbon atoms but one or more units of a i ;.

' 14 O1 larger carbon number may also be present. The 02 poly(oxyalkylene) component employed in the present 03 invention is more fully described and exemplified in 04 U.S. Patent No. 4,191,537.

06 Although the hydrocarbyl group on the hydrocarbyl 07 poly(oxyalkylene) component will preferably contain from 08 l to about 30 carbon atoms, longer hydrocarbyl groups, 09 particularly longer chain alkyl phenyl groups, may also be employed.

12 For example, alkylphenyl poly(oxyalkylene) 13 aminocarbamates wherein the alkyl group contains at 14 least 40 carbon atoms, as described in U.S. Patent No. 4,881.945 to Buckley, are also contemplated for use 16 in the present invention. The alkyl phenyl group on the 17 aminocarbamates of U.S. Patent No. 4,881,945 will pre-18 ferably contain an alkyl group of 50 to 200 carbon 1g atoms, and more preferably, an alkyl group of 60 to 100 carbon atoms.

22 B. The Amine Component 24 The amine moiety of the hydrocarbyl-terminated poly(oxyalkylene) ami.nocarbamate is preferably derived 26 from a polyamine having from 2 to about 12 amine 27 nitrogen atoms and from 2 to about 40 carbon atoms. The 28 polyamine is preferably reacted with a hydrocarbyl poly-29 (oxyalkylene) chloroformate to produce the hydrocarbyl poly(oxyalkylene) aminocarbamate fuel additive finding 31 use within the scope of the present invention. The 32 chloroformate is itself derived from hydrocarbyl ~c~~9~j4 "' ' WO 91112303 PCI'1US91f~1934 !3 O1 poly(oxyalkylene) alcohol by reaction with phosgene.
02 The polyamine, encompassing diamines, provides the 03 product poly(oxyalkylene) aminocarbamate with, on the 04 average, at least about one basic nitrogen atom per 05 carhamate molecule, i.e., a nitrogen atom titratable by 06 strong acid. The golyamine preferably has a carbon-to-07 nitrogen ratio of from about 1:1 to about 10:1. The 08 polyamine may be substituted with substituents selected 09 from hydrogen, hydrocarbyl groups of from 1 to about 10 carbon atoms, acyl groups of from 2 to about 10 carbon 11 atoms, and monoketone, monohydroxy, mononitro, mono-12 cyano, alkyl and alkoxy derivatives of hydrocarbyl 13 groups of from 1 to 10 carbon atoms. It is preferred 14 that at least one of the basic nitrogen atoms of the polyamine is a primary or secondary amino nitrogen. The 16 polyamine component employed in the present invention 17 has been described and exemplified more fully in U.S.
18 Patent No. 4,191,537.

Hydrocarbyl, as used in describing the hydrocarbyl 21 poly(oxyalkylene) and amine components used in this 22 invention, denotes an organic radical composed of carbon 23 and hydrogen which may be aliphatic, alicyclic, aromatic 24 or combinations thereof, e.g., aralkyl. Preferably, the hydrocarbyl group will be relatively free of aliphatic 26 unsaturation, i.e.. ethylenic and acetylenic, particu-27 lady acetylenic unsaturation. The more .preferred poly-2g amine finding use within the scope of the present inven-29 tion is a polyalkylene polyamine, including alkylene-diamine, and including substituted polyamines, e.g., 31 alkyl and hydroxyalkyl-substituted polyalkylene poly-32 amine. Preferably, the alkylene group contains from 2 33 to 6 carbon atoms, there being preferably from 2 to 3 34 carbon atoms between the nitrogen atoms. Examples of W(D 91/2303 PC'f/US91/00~9a4 l l~
O1 such polyamines include ethylenediamine, diethylene tri-02 amine, triethylene tetramine, di(trimethylene) triamine, 03 dipropylene triamine, tetraethylene pentamine, etc.
04 Among the polyalkylene polyamines, polyethylene poly-05 amine and polypropylene polyamine containing 2-12 amine 06 nitrogen atoms and 2-24 carbon atoms are especially pre-0? ferred and in particular, the lower ;polyalkylene poly-08 amines, e.g., ethylenediamine, diethylene triamine, 09 propylene diamine, dipropylene triamine, etc., are most preferred.

12 C. The Aminocarbamate 14 The poly(oxyalkylene) aminocarbamate fuel additive used in compositions of the present invention is obtained by 16 linking the amine component and the poly(oxyalkylene) 17 component together through a carbamate linkage, i.e., -°'°(°)-~'w 22 wherein the oxygen may be regarded as the terminal 23 hydroxyl oxygen of the poly(oxyalkylene) alcohol 24 component, and the carbonyl group -C(°)-, is preferably Provided by a cougling agent, e.g., phosgene. In the 2~ preferred method of preparation, the hydrocarbyl 27 Poly(oxyalkylene) alcohol is reacted with phosgene to 28 Produce a chloroformate and the chloroformate is reacted 29 with the polyamine. The carbamate linkages are formed as the poly(oxyalkylene) chains are bound to the 31 nitrogen of the polyamine through the oxycarbonyl group 32 of the chloroformate. Since there may be more than one 33 nitrogen atom of the polyamirie which is capable of 34 reacting with the chloroformate, the aminocarbamate contains at least one hydrocarbyl poly(oxyalkylene) ~'~~~J
iy~ 91/I2303 1P(.'T/US91/00934 /7 .
0I polymer chain bonded through an oxycarbonyl group to a 02 nitrogen atom of the polya~aine, but the carbonate may 03 contain from 1 to 2 or more such chains. It is pre-04 (erred that the hydrocarbyl poly(oxyalkylene) amino-05 carbamate product contains on the average, about 1 06 poly(oxyalkylene) chain per molecule (i.e., is a 07 monocarbamate), although it is understood that this OS reaction route may lead to mixtures containing 09 appreciable amounts of di or higher poly(oxyalkylene) chain substitution on a polyamine containing several 11 reactive nitrogen atoms. A particularly preferred 12 aminocarbamate is alkylphenyl poly(oxybutylenep amino-13 carbamate, wherein the amine moiety is derived from I4 ethylene diamine or diethylene triamine. Synthetic methods to avoid higher degrees of substitution, methods 16 of preparation, and other characteristics of the amino-17 carbamates used in the present invention are more fully 1g described and exemplified in U.S. Patent No. 4,191,537.
19 ' The In hector Detergent 22 The injector detergent employed in the homogeneous fuel 23 additive composition of the present invention is a 24 branched-chain hydrocarbyl amine having at least one basic ZS nitrogen atom and an average molecular weight of about 300 26 to about 700, and wherein the hydrocarbyl moiety is derived 27 from polymers of CZ to C6 olefins.

29 Tn the amine injector detergent, the branched-chain hydrocarbyl group will ordinarily be prepared by polymec-31 izing olefins of from 2 to 6 carbon atoms fethylene being 32 copolymerized With another olefin so as to provide a 33 branched-chain). The branched chain hydrocarbyl group will 34 generally have at least I branch per 6 carbon atoms along ~~~~~5~?
WO 91/12303 PGT/gJ591/OO~j4 ~$
O1 the chain, preferably at least 1 branch per 4 carbon atoms 02 along the chain and, more preferably, at least 1 branch per 03 2 carbon atoms along the chain. The preferred branched-04 chain hydrocarbyl groups are polypropylene and polyiso-05 butylene. The branches will usually be of from 1 to 2 06 carbon atoms, preferably I carbon atom, that is, methyl. In 07 general, the branched-chain hydrocarbyl group will contain 08 from about 20 to 40 carbon atoms.

IO In most instances, the branched-chain hydrocarbyl amines are 1I not a pure single product, but rather a mixture of compounds 1Z having an average molecular weight. Usually, the range of 13 molecular weights will be relatively narrow and peaked near 14 the indicated molecular weight.
I6 The amino component of the branched-chain hydrocarbyl amines 17 may be either a monoamine or a polyamine. The monoamine or I8 polyamine component embodies a broad class of amines having 19 from I to 10 amine nitrogen atoms and from Z to 40 carbon atoms with a carbon to nitrogen ratio between about 1:I and 21 10:1. In most instances, the amine component is not a pure Z2 single product, but rather a mixture of compounds having a 23 major quantity of the designated amine. For the more 24 complicated polyamines, the compositions will be a mixture of amines having as the major groduct the compound indicated 26 and having minor amounts of analogous compounds.
2?
28 When the amine component is a polyamine, it will preferably 2g be a polyalkylene polyamine, including alkylenediamine.
preferably, the alkylene group will contain from 2 to 6 31 carbon atoms, more preferably from 2 to 3 carbon atoms.
32 examples of such polyamines include ethylene diamine, 33 diethyl,ene triamine, triethylene~tetramine and tetraethylene 34 pentamine.

O1 A particularly preferred branched-chain hydrocarbyl amine is 02 polyisobutenyl ethylene diamine.

04 The branched-chain hydrocarbyl amine injector detergents 05 employed in the fuel additive composition of the invention 06 are prepared by conventional procedures known in the art.
07 Such branched-chain hydrocarbyl amines and their prepa-08 rations are described in detail in U.S. Patent 09 Nos. 3,438,757; 3,565,804; 3,574,576; 3,848,056 and 3,960,515.

12 The Demulsifier 14 The demulsifier employed in the fuel additive composition of the invention is a chemical agent which, when used in 16 relatively low concentrations in gasoline compositions, will 17 promote the rapid coalescence of emulsified water to the 18 point where it can be effectively removed from the bulk 19 hydrocarbon by means of static gravity assisted separation in a quiescent storage tank. The demulsifier agent is 21 frequently a mixture of several chemical agents which in Z2 proper combination afford the desired demulsifying charac-23 teristics. These agents are typically selected from, but 24 are not restricted to, alkylphenol resins, polyoxyalkylene-based fluids, alkylarylsulfonates, derivatives of fatty 26 acids, and the like. One.preferred demulsifier for use in 27 the composition of this invention is known as Tolad ~ T-326, 28 a commercially available demulsifier from Petrolite 29 Corporation, Tretolite Division, St. Louis, Missouri, which comprises a mixture of oxyalkylated alkylphenol-formaldehyde 31 resins, polyoxyalkylene glycols, and sodium arylsulfonate in 32 heavy aromatic naphtha.

W~ 91/IZ303 P(.'T/US91/00934{.,1 as O1 In selectiflg a proper fuel/water demulsifying agent, it is 02 important that the fuel, blended with an effective deposit 03 control amount of a fuel additive, be able to shed water or 04 become essentially emulsion-free within 15 to 30 minutes of 05 its contact with an aqueous phase. The fuel additive com-06 position of this invention, being generally regarded as a 07 dispersant agent, also has the tendency to promote emulsion 48 formation when gasoline compositions containing the additive 09 composition are contacted with water. Demulsifiers. at relatively low fuel concentrations, assist in the demulsifi-11 cation of such emulsions and thereby help to clarify other-12 wise cloudy wet fuels. It is important to note that 13 demulsifiers, when used in concentrations higher than about 14 25 pgm, can also promote emulsification. Hence, their dosage must be carefully regulated and adjusted to the 16 physical/chemical characteristics of fuel compositions 17 containing the fuel additive components. Many demulsifiers 18 will satisfy this criterion but will nevertheless fail the 19 criterion of compatibility with the other components of the fuel additive composition.

22 The Carrier Fluid 24 The carrier fluid employed in this invention is a chemically inert hydrocarbon-soluble liquid vehicle which substantially 26 increases the nonvolatile residue (NVR), or solvent-free 27 liquid fraction of the fuel additive composition while not 28 overwhelmingly contributing to octane requirement increase.
29 The carrier fluid may be a natural or synthetic oil, such as 3p mineral oil, refined petroleum oils, synthetic polyalkanes 31 and alkenes, synthetic polyoxyalkylene derived oils, and the 32 like, as described, for example, in U.S. Patent 33 ~lo. 4,191,537 to Lewis. These carrier fluids are believed f.-WO 91/123(63 ~ 1'CT/US91/0093a O1 to act as a carrier for the dispersant and detergent and to 02 assist in removing and retarding deposits.

04 The carrier fluid employed in the instant invention must 05 also be capable of forming a homogeneous mixture with the 06 other components of the present fuel additive composition.
07 Examples of suitable carrier fluids include Chevron Neutral 08 Oil 5008 and Chevron Neutral Oil 600P, available from 09 Chevron U.S.A. Inc., San Francisco, California.
11 Fuel Com ositions 13 The fuel additive composition of the present invention will 1q generally be employed in a hydrocarbon distillate fuel boiling in the gasoline or diesel range. The proper concen-18 tration of this additive composition necessary in order to 1~ achieve the desired detergency and dispersancy varies 18 depending upon the type of fuel employed, the presence of 1g other additives, and the like. In general, however, from about 400 to 1,200 parts per million (ppm) of the instant 21 fuel additive composition in the base fuel is needed to 22 achieve the best results. In terms of individual compo-23 vents, fuel compositions containing the homogeneous fuel 2q additive composition of the invention will generally contain about 100 to 225 ppm of the aminocarbamate dispersant, about 26 10 to 70 ppm of the hydrocarbyl amine injector detergent, 27 about 5 to 25 ppm of the demulsifier and about 250 to 28 800 ppm of the carrier fluid.

The deposit control fuel additive composition of the present 3I invention may also be formulated as a concentrate, using an 32 inert, stable oleophilic organic solvent boiling in the 33 range of about 150° to 400°F. Preferably, an aliphatic or an 3q aromatic hydrocarbon solvent is used, such as benzene, ~~~~~5~~ .
WO 91/12303 PCT/US91/OOys4 as 01 toluene, xylenes, or higher-boiling aromatics or aromatic 02 thinners. Aliphatic alcohols of about 3 to 8 carbon atoms, 03 such as isopropanol, isobutylcarbinol, n-butanol, and the 04 like, in combination with hydrocarbon salveents are also 05 suitable for use with the additive composition of the 06 invention. In the fuel concentrate, the amount of the 07 instant additive composition will be ordinarily at least 5 08 percent by weight and generally not exceed 50 percent by 09 weight, preferably from 10 to 30 weight percent.
11 In gasoline fuels, other fuel additives may also be included 1Z such as antiknock agents, e.g., methylcyclopentadienyl 13 manganese tricarbonyl, tetramethyl or tetraethyl lead, tert-14 butyl methyl peroxide and various oxygenates, such as methanol, ethanol and methyl t-butyl ether. Also included 16 may be lead scavengers such as aryl halides, e.g., dichloro-17 benzene or alkyl halides, e.g., ethylene dibromide. Addi-18 tionally, antioxidants and metal deactivators may be 19 present.
21 In diesel fuels, other well-known additives can be employed Z2 such as pour point depressants, flow improvers, cetane 23 improvers, etc.

The following examples are offered to specifically 26 illustrate this invention. These examples and illustrations 27 are not to be construed in any way as limiting the scope of 28 this invention.

~r0 91/12303 PCf/US91/0093~
?..3 05 Preparation of an Aminocarbamate Dispersant Useful in this Invention ~7 A dispersant useful in this invention was prepared in a 0'8 manner similar to that described in Lewis, U.S. Patent Og No. 4,160,648, Examples 6-8, except that diethylene triamine was used in place of ethylene diamine. In this example, a 11 tetrapropenyl phenol was reacted stepwise with butylene 12 oxide, phosgene, and diethylene triamine to afford a high 13 molecular weight tetrapropenyl polyloxybutylene) 14 aminocarbamate, referred to hereinbelow as a polyether amine (PEA1.

19 A Hydrocarbyl Amine Injector Detergent Useful in this Invention 22 An injector detergent (ID) was prepared in a manner similar 23 to that described by Honnen, U.S. Patent No. 3,438,757, 24 Example 2. In this example, a C30 polyisobutene having a molecular weight of approximately 420 was reacted stepwise 2~, with chlorine and ethylene diamine to produce a 27 polyisobutene ethylene diamine adduct.

Carrier Fluids Useful in this Invention 33 Chevron Neutral Oil 5008 and Chevron Neutral Oil 600P were 34 used as carrier fluids (CF) in the examples hereinbelow.
Chevron Neutral Oil 500R.is a highly refined base oil having WO 91!12303 ' a ~ PLT'/US911009~, .
O1 a pour point of -12°C (Max.) and a viscosity of 98.6 cSt at 02 40°C. Chevron Neutral Oil 600P is a highly refined base oil 03 having a pour point of 10°F (-12.2°C) and a viscosity of 04 129.5 cSt at 37.8°C.

08 A Demulsifier Useful in this Invention The demulsifier (D) used in these examples to illustrate the !I present invention was a commercially available demulsifier 12 (from Petrolite Corporation, Tretolite Division, St. Louis, 13 MO) identified by the manufacturer as Tolad ~ T-326. This 14 demulsifier .comprises a mixture of oxyalkylated alkylphenol-formaldehyde resins, polyoxyalkylene glycols, and sodium 16 arylsulfonate (1 to S weight percent) in heavy aromatic 17 naphtha (30 to 60 weight percent). Tolad ~ T-326 is 18 reported to have a flash point, SPCC, of 114°F, a pour 19 point, ASTM D-97, of 5°F, and a viscosity of 263 SUS at 60°F.

24 Demulsibility Test 26 The procedure described by ASTM Method D-1094 was used to 27 test demulsibility. Here, the fuel phase and the interface 28 are rated for clarity and for persistence of an interfacial 29 emulsion layer. The fuel additive compositions were tested and rated numerically, on a scale from one to four. The 31 number "one" was the highest rating for clarity, and "one"
32 was the highest rating for persistence of an interfacial 33 emulsion layer.

WO 91!12303 PCTlUS91/00934 O1 The fuel additive composition of this invention, exemplified 02 by Sample 6A below, met the requirement of a rating of one, 03 on both these tests.

07 Preparation of Fuel Additive Compositions Og Two fuel additive compositions were prepared. 150 parts of the polyether amine of Ex. 1, 25 parts of the injector 11 detergent of Ex. 2, 12 parts of a demulsifier, 212 parts of 12 Chevron Solvent 25, (which is a mixture of C-9 blending 13 aromatics available from Chevron U.S.A. Inc., San Francisco, !q California') and 450 parts of Chevron Neutral Oil 5008 (Ex. 3) were mixed at room temperature with stirring in a 16 200 ml flask.

18 Sample 6A contained Tolad O T-326 (as described in Ex. 4) as 1g the demulsifier. Sample 6B contained L-1562 as the demulsi-fier. L-1562 is a commercially available demulsifier pur-21 chased from Petrolite Corporation, St. Louis, M0. A third 2Z additive composition, Sample 6C, contained oleyl amine as 23 the injector detergent, and is shown for comparison pur-24 poses. Oley1 amine is a low molecular weight straight chain Clg primary amine.

a~ EXAMPLE 7 Compatibility Test 31 The compatibility test used was a modification of the 32 procedure described by ASTM Method D-2273, except that, 33 since a significant amount of diluent solvent (Chevron 3q Solvent 25, a mixture of C-9 blending aromatics) was already ~Q~~°~~
!y0 91/12303 PC,'T/US91/00r:~4 O1 present in these compositions, this test was gerformed with-02 out further dilution. The test was performed in two parts, 03 In Part A, the samples prepared by the procedure of 04 Example 6 were held at ambient or room temperature (about 05 20-25°C) for 24 hours. Each sample was then visually 06 inspected for a secondary phase. If a secondary phase was 07 observed, the sample was centrifuged and the volume percent 08 of the secondary phase determined.. If no secondary phase 09 was observed, Part B of this test was performed.
11 In Part B, the samples were cooled to 0°P and held at this 12 temperature for 24 hours. Each sample was then visually 13 inspected for a secondary phase. If a secondary phase was 14 observed, the sample was centrifuged and the volume percent of the secondary phase determined.

17 The results are reported in terms of volume percent of 18 secondary phase sediment after centrifuging, which was I9 either a liquid, a solid or a combination. Levels of sediment (or secondary phase) that exceed 0.005 vol.~ are 21 considered unacceptable.

23 The fuel additive composition of this invention (Sample 6A) 24 does not have any measurable volume percent of a secondary phase under these test conditions. However, when L-1562 was 26 used as the demulsifier (Sample 6B),' or when oleyl amine was Z.7 used as the injector detergent (Samgle 6C), significant and 28 unacceptable levels of a secondary phase were observed.

3Z _ ~~~~~54 .--~ WO 91/12303 PCTlUS91l00939 a~
01 Vol. %
OZ Fuel Additive Composition Secondar~Phase Part A Part B
03 (20-25°C) (0°F) 04 Sample 6A.: 150 parts PEA (Ex 1) e0.005 e0.005 05 25 parts ID (Ex 2) 06 450 parts CF (Ex 3, Chevron 500R) p7 222 parts Chev. Sol. 25 08 12 parts T-326 09 Sample 6a.: 150 parts PEA (Ex 1) 0.75 -(Comparative) 25 parts ID (Ex 2) 450 parts CF (Ex 3, 1l Chevron 500R) 12 212 parts Chev. Sol. 25 12 parts L-1562 14 Sample 6C.: 150 parts PEA (Ex 1) e0.005 0.05 (Comparative) 25 parts oleyl amine 450 parts CF (Ex 3, 16 Chevron 500R) 212 parts Chev. Sol. 25 1~ ~ 12 parts T-326 18 For Sample 6B, a liquid second phase was observed at ambient i9 temperature showing the incompatibility of the demulsifier with the other components of the fuel additive composition.

22 Sample 6C, containing oleyl amine as an injector detergent, 23 was centrifuged after cooling to 0°F and showed a small 24 volume (0.05 vol.%) of an insoluble solid sediment. Thus it failed the criterion that sediment levels must not exceed 26 0 005 vol.%.

28 _EXAMPLE 8 Intake Valve Deposit Test 3i 3Z An unleaded regular grade gasoline was additized with fuel 33 additive packages of this invention such that the fuel 34 contained the following ingredients:

2O~~~Jt WO 91/123(13 PCT/US9I100~:
:;'.

a$ , 02 8A: 150 ppm of PEA (Ex 1) 25 ppm of ID (Ex 2) 03 450 ppm of CF (Ex 3, Chevron600P) 04 12 ppm of D (T-326) 05 88: 150 ppm of PEA (Ex 1) 06 25 gpm of ID (Ex 2) 450 ppm of CF (Ex 3, Chevron500R) 07 12 ppm of D (T-326) 09 The gasolines were tested for intake valve keep-clean effectiveness using a procedure which utilizes a 1981 11 Pontiac 2.5-liter engine mounted upon an engine test stand, 12 and run for 90 hrs. This test simulates a type of severe 13 field test service characterized by light load driving 14 conditions. The effectiveness of an additive package is determined by averaging the weights of accumulated intake 16 valve deposits obtained by the end of test, and comparing 17 these results with those obtained using identical test 18 conditions and the unadditized fuel. A good fuel additive 19 package capable of complete intake system keep-clean performance will typically reduce base gasoline intake valve 21 deposits.

23 Using the above test conditions, the unadditized base fuel 24 test produced, on average, 1,090 milligrams of deposits per intake valve. The same gasoline containing a fuel additive 26 package of this invention using Chevron Neutral Oil 600P, 27 Example 8A, gave on average 23 milligrams of deposits per 28 intake valve. When the above comparison was made between 29 base fuel and an addftized fuel containing Chevron Neutral Oil 5008, Example 88, we observed an average of 299 milli-31 grams of intake valve deposits. These results are 32 summarized below:
33 ' 3~

~~~~9~~ 4 Pcrevs9ieoo9~a WO 91e1Z343 act O1 Fuel Blend~Containin~ Av. Deposit wgts.

03 No Additive (Base Case) 1090 mg 8A 23 mg 8B 299 mg Oy In both 8A and 8B, the average deposit weight is well below Og the base case, showing the effectiveness of the fuel ~g additive composition of the invention.

13 -Octane Requirement Increase Test This test measures the potential that any gasoline additives 16 may have in upsetting the octane requirements of gasoline operated engines. Over time, due to the buildup of deposits 1g in the combustion chamber, higher octane gasoline is 1g required to minimize engine knock. Unadditized gasolines contribute a baseline level of deposits which typically 21 require a fuel having an octane value four numbers higher 22 than the initial fuel used to start the test in oxder to 23 minimize the increasing engine knock condition. Gasoline 24 additives contribute to this problem to different degrees, and the magnitude of this contribution can be measured by 26 comparisons with engine tests using additized fuel. The difference of OItI observed between the tests is that addi-~
28 tional increment of increased octane number required to 2g further minimize engine knock and is generally referred to as the octane requirement increase attributable to the 31 gasoline additive package itself. This value is typically 32 referred to as the "additive OFtI number".

~0~~~~~~
W~ 91/12303 PCT/I1~91/OOd ~v O1 This procedure utilizes a 1975 Toyota 2.2-liter engine 02 mounted on an engine stand and equipped with a control 03 system to carefully regulate test conditions and engine 04 operating cycles. The engine is first run for fifteen hours 05 on a relatively clean-burning, additive-free alkylate fuel.
06 At this time, the octane requirement is determined, and the 0? fuel is switched to a mixture of~70% unleaded regular OS gasoline and 30% of FCC Heavy gasoline. The FCC Heavy 09 component is employed to increase the rate of combustion chamber deposit accumulation during this phase of the test.
11 After 110 hours of additional engine operation, the final I2 octane requirement measurement is made.

14 When tested in this~manner, the fuel additive package of this invention contributed one half of one octane number I6 more than the octane requirement observed for the unaddi-1? tized fuel (Test 9A). This increase was significantly less 18 than that observed for a commercial gasoline additive 19 package consisting of a heavy polybutene amine made from a polybutene containing, on average, 100 carbons per molecule, 21 and having an average molecular weight of about 1450, which 22 is reacted stepwise with chlorine and ethylene diamine, and 23 a large dose of carrier oil (Test 9B).
24 Increase Fuel Containing: ORI Number Over Base 26 Base: No Additive 4.0 0 2? Test 9A: 150 ppm PEA (Ex 1) 4.5 0.5 28 25 ppm ID (Ex 2) 29 600 ppm CF (Ex 3, Chevron SOOR) 12 ppm D (T-326) 31 (Ex 4) 3Z Test 9B: 250 ppm F~eavy 7.0 3.0 33 Polybutene Amine -1000 ppm CF (Ex 3, 34 'Chevron 500R)

Claims (16)

WHAT IS CLAIMED IS:

1. 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 1000 to 3000;
(b) an injector detergent comprising a branched-chain hydrocarbyl amine having at least one basic nitrogen atom and an average molecular weight of 300 to 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.

2. The fuel additive composition according to Claim 1, wherein the hydrocarbyl group in component (a) contains from 1 to 30 carbon atoms.

3. The fuel additive composition according to Claim 1, wherein the hydrocarbyl group in component (a) is an alkylphenyl group.

4. The fuel additive composition according to Claim 3, wherein the alkyl moiety in the alkylphenyl group is tetrapropenyl.

5. The fuel additive composition according to Claim 1, wherein the amine moiety of the aminocarbamate is derived from a polyamine having from 2 to 12 amine nitrogen atoms and from 2 to 40 carbon atoms.

6. The fuel additive composition according to Claim 5, wherein the polyamine is a polyalkylene polyamine having 2 to 12 amino nitrogen atoms and 2 to 24 carbon atoms.

7. The fuel additive composition according to Claim 6, wherein the polyalkylene polyamine is selected from the group consisting of ethylene diamine, propylene diamine, diethylene triamine and dipropylene triamine.

8. The fuel additive composition according to Claim 1, wherein the poly(oxyalkylene) moiety of component (a) is derived from C2 to C5 oxyalkylene units.

9. The fuel additive composition according to Claim 1, wherein the hydrocarbyl poly(oxyalkylene) amino-carbamate of component (a) is an alkylphenyl poly-(oxybutylene)aminocarbamate, wherein the amine moiety is derived from ethylene diamine or diethylene triamine.

10. The fuel additive composition according to Claim 1, wherein the branched-chain hydrocarbyl moiety of component (b) is polypropenyl or polyisobutenyl.

11. The fuel additive composition according to Claim 1, wherein the amine group of the branched-chain hydro-carbyl amine of component (b) is selected from the group consisting of ethylene diamine, diethylene triamine, triethylene tetramine and tetraethylene pentamine.

12. The fuel additive composition according to Claim 1, wherein the branched-chain hydrocarbyl amine of component (b) is a polyisobutenyl ethylene diamine.

13. The fuel additive composition according to Claim 1, wherein component (a) is an alkylphenyl poly(oxy-butylene)aminocarbamate, wherein the amine moiety is derived from ethylene diamine or diethylene triamine, and component (b) is a polyisobutenyl ethylene diamine.

14. A fuel composition comprising a hydrocarbon boiling in the gasoline or diesel range and from 400 to 1,200 parts per million of a homogeneous fuel additive composition comprising:
(a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of 1000 to 3000;
(b) an injector detergent comprising a branched-chain hydrocarbyl amine having at least one basic nitrogen atom and an average molecular weight of 300 to 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.

15. The fuel composition according to Claim 14, wherein said fuel composition contains 100 to 225 ppm of the dispersant of component (a), 10 to 70 ppm of the injector detergent of component (b), 5 to 25 ppm of the demulsifier of component (c) and 250 to 400 ppm of the 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 and from 5 to 50 weight percent of a homogeneous fuel additive composition comprising:
(a) a dispersant comprising a hydrocarbyl poly(oxyalkylene) aminocarbamate having at least one basic nitrogen atom and an average molecular weight of 1000 to 3000;
(b) an injector detergent comprising a branched-chain hydrocarbyl amine having at least one basic nitrogen atom and an average molecular weight of (t 300 to 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.