This disclosure relates to fuel compositions containing deposit control additives and methods for reducing deposits on the surface of engine components and within the combustion chamber More specifically, this disclosure relates to fuel compositions containing a deposit-controlling amount of esteramines to inhibit and control engine deposits

It is well known that automobile engines tend to form deposits within the combustion chamber and on the surface of engine components, such as carburetor ports, throttle bodies, fuel injectors, intake ports, intake valves, piston tops, and cylinder heads due to the evaporation, oxidation and polymerization of hydrocarbon fuel These deposits, even when present in relatively minor amounts, often cause noticeable driveability problems, such as stalling and poor acceleration Moreover, engine deposits can significantly increase an automobile's fuel consumption and production of exhaust pollutants Therefore, the development of effective fuel detergents or "deposit control" additives to prevent or control such deposits is of considerable importance

It has now been discovered that certain esteramines are surprisingly useful for reducing engine deposits when employed as fuel additives in fuel compositions

Novel fuel compositions described herein comprise a major amount of fuel and an effective deposit-controlling amount of at least one esteramine of the general formula

(R ¹ -C(0)0-R ² ) _x NR ³ _y R ⁴ _z

wherein R ¹ is a C ₇ -C ₂₁ hydrocarbon group preferaoly a C--C ₂₁ saturated or unsaturated alkyl group, x is 1 , 2 or 3 y and z are individually selected from 0, 1 or 2, x+y+z=3, R ² is selected from the group consisting of C,-C ₆ alkylene groups and -(R ⁵ 0) _n R ⁵ - groups wherein each R ⁵ can be the same or different and is independently selected from the group consisting of linear or branched C C ₆ alkylene groups and n is 1 to 60, R ³ and R ⁴ can be the same or different and are individually selected from the group consisting of C _r C ₆ alkyl groups, -(R ⁵ 0) _π H groups wherein R ⁵ and n are as defined above, and -R ⁶ NR ⁷ R ⁸ groups wherein R ⁶ is a C, to C ₆ linear or branched alkylene group, and R ⁷ and R ⁸ can be the same or different and are individually selected from the group consisting of R ³ , R ⁴ and (R ¹ - C(0)0-R ² )- groups wherein R ¹ , R ² , R ³ , and R ⁴ are as defined above

In particularly useful embodiments, the esteramine is prepared by reacting a fatty acid with an alkanolamine, a polyalkanolamine, an alkoxylated amine or an alkoxylated polyamine. The esteramine can be a mono-, dι-, tπ- or tetra-ester and can be used alone or with other deposit-control additives In a particularly useful embodiment, the presently disclosed esteramine additives are used in combination with a known polyetheramine additive The resulting combination of additives surprisingly provides a synergistic effect with respect to reducing engine deposits

Methods for reducing engine deposits in an internal combustion engine are also described The methods comprise operating an engine with a fuel comprising an effective deposit-controlling amount of an esteramine, preferably an esteramine prepared by reacting a fatty acid with an alkanolamine or an alkoxylated amine

Various embodiments are described herein with reference to tne drawings wherein

Fig 1 is a graph depicting measured engine intake valve deposits resulting from 80 hour operation of a four cycle engine using fuel containing various additive compositions including presently described esteramine deposit control additive compositions, and

Fig 2 is a graph depicting measured engine deposits resulting from 80 hour operation of four cycle engine using fuel containing various additive compositions, including presently described esteramine deposit control additive compositions and showing the synergistic effects obtained when the presently described deposit control additives are combined with a known polyetheramine additive

The fuel compositions described herein contain a major amount of gasoline and an effective deposit-controlling amount of at least one esteramine The esteramine is of the general formula (R ¹ -C(0)0-R ² ) _x NR ³ _y R ⁴ ₂ , wherein R ¹ is a C ₇ -C ₂₁ hydrocarbon group, preferably a C ₇ -C ₂₁ saturated or unsaturated alkyl group, x is 1 , 2 or 3, y and z are individually selected from 0, 1 or 2, x+y+z=3, R ² is selected from the group consisting of C C ₆ alkylene groups and, -(R ⁵ 0) _n R ⁵ - groups wherein each R ⁵ can be the same or different and is individually selected from the group consisting of linear or branched C,- C ₆ alkylene group and n is 1 to 60, R ³ and R ⁴ can be the same or different and are individually selected from the group consisting of C _r C ₆ alkyl groups, -(R ⁵ 0) _n H groups wherein R ⁵ and n are as defined above, and - R ⁶ NR ⁷ R ⁸ groups wherein R ⁶ is a C-, to C ₆ linear or branched alkylene group, and R ⁷ and R ⁸ can be the same or different and are individually selected from the group consisting of R ³ , R ⁴ and (R ¹ -C(0)0-R ² )- groups wherein R ¹ , R ² , R ³ , and R ⁴ are as defined above

In particularly useful embodiments, the esteramine is prepared by reacting a fatty add with an alkanolamine, polyalkanolamine, an alkoxylated amine or alkoxylated polyamine The fatty acid may be hydrogenated and is preferably a saturated fatty acid Long chain fatty acids having 12 carbon atoms or more are particularly preferred for use in making the esteramine Most preferred are long chain fatty acids having 16 to 18 carbon atoms, i e , the tallow acids, including hydrogenated and partially hydrogenated tallow

The fatty acid is reacted with an alkanolamine to provide an esteramine Amines having one, two or three active sites can be employed to produce mono-, dι-, or tπ-esters, respectively Thus, for example, tπethanolamine can be reacted with a fatty acid to provide a tπester Methydiethanolamine will produce a diester when reacted with the fatty acid Dimethylethanol- amine will react with a fatty acid to generate a monoester The conditions under which amines can be reacted with fatty acids to produce the present esteramines are known to those skilled in the art Such reaction conditions are disclosed, for example, in PCT Publication No WO 91/01295, the disclosure of which is incorporated herein by this reference

It is also possible to employ an alkoxylated amine or alkoxylated polyamine in preparing the present esteramine additives Thus, for example, amines having one or more (R ⁵ 0) _n H groups wherein R ⁵ and n are as mentioned above can be used as a starting material to produce the present esteramine deposit control additives Such alkoxylated amines are available, for example, under the names Propomeen® and Ethomeen® from Akzo Nobel Chemicals Inc., Chicago, 111 Preferably R ⁵ is selected from ethylene, propyiene and mixtures thereof The conditions under which alkoxylated amines are reacted with fatty acids to produce esteramines are

also known and are described, for example, in U.S. Patent No. 5,523,433, the disclosure of which is incorporated by reference.

It is also possible to synthesize suitable esteramines by reacting a fatty acid with a diamine having at least one alkanol group of the general formula: R ₂ N-R ⁶ -NR ₂ wherein R ^δ is as mentioned above; R, which can be the same or different in each instance, is selected from H, C C ₆ saturated or unsaturated, substituted or unsubstituted, branched or unbranched alkyl and C _r C ₆ alkanol. Thus, for example, a tetraester can be prepared by reacting a fatty acid with a diamine of the formula: (HOCH ₂ CH ₂ ) ₂ NCH ₂ CH ₂ CH ₂ N(CH ₂ CH ₂ OH) ₂ .

Other starting materials for forming esteramines using diamines as a starting material will be apparent to those skilled in the art.

Esteramines suitable for use in connection with the fuel compositions and methods described in this disclosure should be soluble in the fuel and should not impart excessive water sensitivity to the fuel. Esteramines useful in the present invention are available from Akzo Nobel Chemicals Inc., Chicago, ILL.

The present fuel compositions contain an effective deposit-controlling amount of esteramine additives. The exact amount of additive that is effective in controlling deposits will depend on a variety of factors including the type of fuel employed, the type of engine and the presence of other fuel additives.

In general, the concentration of the esteramines in hydrocarbon fuel will range from about 50 to about 2500 parts per million (ppm) by weight,

preferably from 75 to 1 ,000 ppm, more preferably from 200 to 500 ppm When other deposit control additives are present a lesser amount of the present additive may be used

The present esteramine additives may also be formulated as a concentrate using an inert stable oleophilic (i e , dissolves in gasoline) organic solvent boiling in the range of about 150°F to 400°F (about 65°C to 205°C ) Preferably, an aliphatic or an aromatic hydrocarbon solvent is used, such as benzene, toluene, xylene or high-boiling aromatics or aromatic thinners Aliphatic alcohols containing about 3 to 8 carbon atoms, such as isopropanol, isobutylcarbinol, n-butanol and the like, in combination with hydrocarbon solvents are also suitable for use with the present additives In the concentrate, the amount of the additive will generally range from about 10 to about 70 weight percent, preferably to 50 weight percent, more preferably from 20 to 40 weight percent

In gasoiine fuels, other fuel additives may be employed with the additives of the present invention, including, for example, oxygenates, such as t-butyl methyl ether, antiknock agents, such as methylcyclopentadienyl manganese tncarbonyl, and other dispersants/detergents, such as hydrocarbyl amines, hydrocarbyl poly-(oxyalkylene) amines, or succin- imides Additionally, antioxidants, metal deactivators and demulsifiers may be present

A fuel-soluble, nonvolatile carrier fluid or oil may also be used with the esteramine additives described herein The carrier fluid is a chemically inert hydrocarbon-soluble liquid vehicle which substantially increases the nonvolatile residue (NVR), or solvent-free liquid fraction of the fuel additive composition while not overwhelmingly contributing to octane requirement

increase. The carrier fluid may be a natural or synthetic oil, such as mineral oil, refined petroleum oils, synthetic polyalkanes and alkenes, including hydrogenated and unhydrogenated polyalphaolefins, synthetic polyoxy- alkylene-derived oils, esters and polyesters.

The carriers fluids are typically employed in amounts ranging from about 100 to about 5000 ppm by weight of the hydrocarbon fuel, preferably from 400 to 3000 ppm of the fuel. Preferably, the ratio of carrier fluid to deposit control additive will range from about 0.5:1 to about 10:1 , more preferably from 1 :1 to 4: 1 , most preferably about 2: 1.

When employed in a fuel concentrate, carrier fluids will generally be present in amounts ranging from about 20 to about 60 weight percent, preferably from 30 to 50 weight percent.

EXAMPLES

The following examples are presented to illustrate specific embodiments of the present compositions and methods. These examples should not be interpreted as limitations upon the scope of the invention.

In the following examples, references to Esteramines l-VII relate to the following compounds:

I. N,N-Dimethylethanoiamine cocoate ester

II. N-Methyldiethanolamine di(hydrogenated tallowate) ester

III. Triethanolamine tritallowate ester

IV. N-Methyldiethanolamine ditallowate ester

V. N,N.N\N'-Tetra(2-hydroxyethyl)-1 ,3-propanediamine tetratallowate ester

V! Alkoxylated methylamine ditallowate ester

VII N,N-bιs-(2-hydroxyethyl)-3- dimethylaminopropyiamine ditallowate ester

EXAMPLES 1-6

Esteramines I and II were used to formulate six fuel compositions which were tested to evaluate the tendency of the fuel compositions to form deposits on heated metal surfaces The compositions were evaluated using an induction system deposit (ISD) apparatus which is a bench-scale analytical laboratory tool that simulates two essential conditions that occur in the gasoline induction systems of spark-ignition engines high temperature and thin film oxidation of atomized gasoline In an ISD test, a fuel/air mixture is aspirated onto the outer surface of a internally heated metal deposit tube, in a flat spray pattern This produces a roughly elliptical deposit on the cylindrical tube surface which can be weighed and visually evaluated Test results from additized fuels can be interpreted as an indication of the relative effectiveness of the additives at reducing the deposit forming tendency of the fuel in a simulated induction system environment

Additized samples for the ISD test were prepared by taking appropriate aliquots from 10g/I stock solutions of the additives in the test fuel 150g of each sample was prepared and filtered through a 0 8 micro-meter membrane filter Immediately after filtration, 150 ml of each test sample was tested on the ISD apparatus Test data was recorded as deposit weight to nearest 0 1 mg Tabulated data for additized fuel was presented as the percent of the "baseline" deposit produced by the unadditized test fuel

mq deposit (additized fuel)

% of Baseline = mg deposit (unadditized fuel) x 100

The test parameters used for all the tests are as follows:

Test Temp. 450°F (232 °C) Sample Size 150 ml Fuel Flow Rate 2 ml/min Air Flow Rate 15 l/min Cylinder Materia Aluminum Test Fuel Formulated by Phillips Petroleum Co. for port injector fouling tests

The results which are presented in Table I, show that both esteramine products reduce the fuel deposit weight to between 40% and 45% of the level produced with unadditized fuel when they are used by themselves at 300 ppm by weight in the test fuel. When either product is used in combination with a solvent neutral oil, the deposit reduction is significantly improved (See Examples 3-6 in Table I).

TABLE I

Ex. Ex. Ex. Ex. Ex. Ex. Ex. 1 2 3 4 5 6 A

Esteramine I 300 ^* - 300 - - - -

Esteramine II - 300 - 300 300 150

Solvent - - 500 500 500 500 500 Neutral Oil ^**

ISD Deposit 44 42 27 11 15 28 58 (% of Baseline)

^* Additive Concentration is given as ppm by weight in test fuel. ^** The Solvent Neutral Oil used was Kendex 600, Kendex/Amali Div. of Witco Corp.

Examples 7-13

Seven fuel compositions containing esteramine additives were formulated and tested to evaluate the additive's effectiveness at reducing deposits in an operating engine

The fuel compositions identified in Table II were used to operate pre- cleaned Honda Genset Engines for 80 hours The engines were then disassembled and any deposits on the underside of the inlet valves were carefully removed and weighed Any deposits on the piston top and combustion chamber of these four-cycle engines were also carefully collected and weighed A baseline was established by operating a Honda Genset Engine using a test fuel containing no additives The results are reported in Table II and are graphically depicted in Fig 1

TABLE II

Example Additive Combustion Intake Intake

Chamber Valve Valve

Deposit Deposit Deposit

(g) (mg) (% of Base-line)

Control None 1 2 205 100%

7 Esteramine I 0 4 105 51 %

8 Esteramine II 1 3 29 14%

9 Esteramine III 1 1 49 24%

10 Esteramine IV 0 7 41 20%

1 1 Esteramine V 1 4 51 25%

12 Esteramine VI 1.2 55 27%

13 Esteramine VII 1 4 1 13 55%

In each case the concentration of the identified additive was 400 ppm and 500 ppm of a neutral solvent oil was also used

As is evident from the values reported in Table II, the present esteramine additives reduced intake valve deposits by a minimum of about half to as much as 86% compared to the amount of deposit produced by non- additized fuel.

Examples 14 and 15

Fuel compositions were prepared by adding 400 ppm of the Esteramine II used in Example 2 to two different commercial fuels; namely Shell 87 octane regular unleaded gas and Exxon 87 octane regular unleaded gas. The chemical make-up of any additive package already in the commercial fuels was unknown. Each fuel composition was used to operate a Honda Genset Engine for 80 hours. Then, any deposits formed in the intake valve and combustion chamber were carefully removed and weighed as previously described. For comparison purposes the commercial fuels were tested without the addition of the present esteramine additives. The results are reported in Table 111.

TABLE

Example Composition Intake Valve Combustion

Deposit Chamber

(mg) Deposit (g)

Control Shell Regular Gas 0.0 1.9 (unleaded)

14 Shell Regular 0.0 1.1 Gas Plus Esteramine I

Control Exxon Regular 38 2.5 Gas (unleaded)

15 Exxon Regular 2.5 1.3 Gas Plus Esteramine II

As the data in Table III show, the present esteramine additives significantly enhance any deposit control additives contained in the commercially available fuels tested

EXAMPLES 16 AND 17

The unexpected synergistic effects of the present esteramines when combined with a known polyetheramine additive were shown as follows An 87 octane base fuel containing no additives was tested in the manner previously described to establish a baseline of deposits at the intake valve and combustion chamber of a four cycle engine An esteramine deposit control additive in accordance with this disclosure (Esteramine II) was added to the base fuel to a concentration of 300 ppm and tested in the manner previously described to determine the amount of intake valve and combustion chamber deposits generated A similar fuel composition containing the base fuel and 400 ppm of a polyetheramine additive that is commercially available under the name Techron from Chevron Corp was also tested Finally, a fuel composition containing the base fuel, 200 ppm of Esteramine II and 300 ppm polyetheramine was prepared and tested The results are summarized in Table IV and graphically depicted in Fig 2

TABLE IV

Example Additive In take Valve Combustion Composition Deposit Chamber

(mg) Deposit (g)

Control None 205 1 2

16 Esteramine II 24 1 3

Control Polyetheramine 6 3 2 2

17 Esteramine II 1 3 1 4 plus

Polyetheramine

As the data in Table IV and Fig 2 show, with respect to intake valve deposits the combined effects of the present esteramine additive and known polyether additive is greater than either of the additives individually

It will be understood that various modifications may be made to the embodiments disclosed herein Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto