EP0526129A1

EP0526129A1 - Compositions for control of octane requirement increase

Info

Publication number: EP0526129A1
Application number: EP92306805A
Authority: EP
Inventors: Lawrence Joseph Cunningham
Original assignee: Afton Chemical Corp
Current assignee: Afton Chemical Corp
Priority date: 1991-07-29
Filing date: 1992-07-24
Publication date: 1993-02-03
Anticipated expiration: 2012-07-24
Also published as: EP0526129B1; AU2059792A; DE69202642T2; ES2073248T3; AU654569B2; DE69202642D1; CA2074208A1; JPH05194966A

Abstract

Fuel additive concentrates for controlling octane requirement increase in internal combustion engines comprising the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl substituted succinic acylating agent; an unhydrotreated poly-α-olefin; and optionally, a mineral oil having a viscosity index of less than about 90, and a volatility of about 50% or less as determined by a test method described herein.

Description

This invention relates to controlling octane requirement increase in internal combustion engines. More particularly this invention relates to fuel compositions and to gasoline type fuels and fuels mixtures for internal combustion engines capable of reducing and at least minimizing the amount of octane requirement increase during engine operation.
As is well known, fuels used in internal combustion engines contain a number of additives to enhance the performance of the engines. However, these additives oftentimes lead to the buildup of undesirable deposits which tend to increase the octane requirement over time of internal combustion engines. The deposits also tend to form in the combustion chamber and on intake valves and fuel injectors during engine operation. An object of this invention is to provide compositions capable of reducing the severity of the octane requirement increase problem. Another object is to provide compositions which also reduce deposits which are already present due to prior operation with fuels which have formed such deposits. Still another object is to provide compositions which tend to reduce the plugging of fuel injectors and which do not contribute significantly to intake valve sticking problems.
As the emphasis has shifted to providing fuels and fuel mixtures which are more environmentally "friendly", and as more vehicles are being equipped with fuel injectors to increase the efficiency and further reduce emissions from gasoline engines, a need has developed for fuels and fuel mixtures which reduce or eliminate deposits which accumulate on fuel injectors, intake valves, and combustion chamber surfaces. Such deposits not only increase the octane requirement of the engines but also tend to decrease the fuel flow to the engine as well as contribute to valve sticking. To reduce the amount of deposits on the fuel injector valves, detergent additives designed for this purpose have been added to gasolines. While these detergents provide a significant reduction in the deposits which heretofore have inhibited the operation of fuel injected gasoline engines, such formulations may not provide the most desirable detergent effect for inhibiting and/or cleaning deposits on other internal engine parts, e.g. intake valves, and may in fact lead to an increase in the octane requirement of the engines. There is a need therefore for detergents which are not only keep fuel injectors clean, but which effectively control deposits on other engine parts of internal combustion engines.
Figure 1 is a plot of octane requirement increase versus additive treat rate in pounds per thousand barrels.
This invention provides a fuel additive concentrate for controlling octane requirement increase in internal combustion engines comprising the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl substituted succinic acylating agent; an unhydrotreated poly-α-olefin; and optionally, a mineral oil having a viscosity index of less than about 90, and a volatility of about 50% or less as determined by a test method described herein.
In one of its forms, this invention provides a major amount of hydrocarbons in the gasoline boiling range, or hydrocarbon/oxygenate mixtures, or oxygenates containing a minor, but effective amount, of (a) a fuel additive comprising the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl substituted succinic acylating agent; (b) an unhydrotreated poly-α-olefin having a volatility of about 50% or less as determined by a test method described herein; (c) and optionally (A) a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less as determined by a test method described herein; (B) an antioxidant, or (C) a demulsifier, or (D) an aromatic hydrocarbon solvent, or (E) a corrosion inhibitor, or any combination of any two, three, four, or all five of components (A), (B), (C), (D) and (E). Other performance additives such as combustion improvers, and octane improvers, may also be present.
Another embodiment of this invention is a method for controlling octane requirement increase of internal combustion engines comprising providing for use as a fuel composition (a) a major amount of an unleaded gasoline and (b) a minor but effective amount of a octane requirement increase controlling mixture comprising (i) the reaction product of polyamine and at least one acyclic hydrocarbyl substituted succinic acylating agent, (ii) an unhydrotreated poly-α-olefin having a volatility of 50% or less as determined by a method described herein, and (iii) optionally, a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less as determined by a method described herein, whereby the octane requirement increase of an internal combustion engine is effectively controlled.
These and other embodimenu of this invention will be apparent from the ensuing description and appended claims.
Detergent/dispersant. As noted above, the fuel additive concentrate of this invention comprises (a) as a detergent/dispersant, the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl substituted succinic acylating agent; (b) an unhydrotreated poly-α-olefin having a volatility of 50% or less; and (c) optionally, a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less. The polyamine reactant may be one or more alkylene polyamine(s), which polyamines are may be linear, branched, or cyclic; or a mixture of linear, branched and/or cyclic polyamines and wherein each alkylene group contains from 1 to 10 carbon atoms. A preferred polyamine is a polyamine containing from 2 to 10 nitrogen atoms per molecule or a mixture of polyamines containing an average of from 2 to 10 nitrogen atoms per molecule. A particularly preferred polyamine is a polyamine or mixture of polyamines having from 3 to 7 nitrogen atoms with triethylene tetramine or a combination of ethylene polyamines which approximate triethylene tetramine being the most preferred. In selecting an appropriate polyamine, consideration should be given to the compatibility of the resulting detergent/dispersant with the gasoline fuel mixture with which it is mixed.
Ordinarily the most highly preferred polyamine, triethylene tetramine, will comprise a commercially available mixture having the general overall composition approximating that of triethylene tetramine but which can contain minor amounts of branched-chain and cyclic species as well as some linear polyethylene polyamines such as diethylene triamine and tetraethylene pentamine.For best results, such mixtures should contain at least 50% and preferably at least 70% by weight of the linear polyethylene polyamines enriched in triethylene tetramine.
The acylating agent which is reacted with the polyamine is an acyclic hydrocarbyl substituted succinic acylating agent in which the substituent contains an average of 50 to 100 (preferably 64 to 80) carbon atoms. In order to accomplish the objectives of this invention, it is important that the acyclic hydrocarbyl substituted succinic acylating agent have an acid number in the range of 0.7 to 1.1 (preferably in the range of 0.8 to 1.0, and most preferably 0.9).
To achieve the objectives of this invention, the molar ratio of acylating agent to polyamine in the reaction product of (i) and (ii) is desirably greater than 1 : 1. Preferably the molar ratio of acylating agent to polyamine in the reaction product is in the range of 1.5 : 1 to 2.2 : 1, more preferably from 1.7 : 1 to 1.9 : 1, and most preferably 1.8 : 1.
The acid number of the acyclic hydrocarbyl substituted succinic acylating agent is determined in the customary way -- i.e., by titration -- and is reported in terms of mg of KOH per gram of product. It is to be noted that this determination is made on the overall acylating agent with any unreacted olefin polymer (e.g., polyisobutene) present.
The acyclic hydrocarbyl substituent of the acylating agent is preferably an alkyl or alkenyl group having the requisite number of carbon atoms as specified above. Alkenyl substituents derived from poly-α-olefin homopolymers or copolymers of appropriate molecular weight (e.g., propene homopolymers, butene homopolymers, C₃ and C₄ α-olefin copolymers) are suitable. Most preferably, the substituent is a polyisobutenyl group formed from polyisobutene having a number average molecular weight (as determined by gel permeation chromatography) in the range of 700 to 1200, preferably 900 to 1100, most preferably 940 to 1000.
Acyclic hydrocarbyl-substituted succinic acid acylating agents and methods for their preparation and use in the formation of succinimide are well known to those skilled in the art and are extensively reported in the patent literature. See for example the following U. S. Patents.
When utilizing the general procedures such as described in these patents, the important considerations insofar as the present invention is concerned, are to insure that the hydrocarbyl substituent of the acylating agent contain the requisite number of carbon atoms, that the acylating agent have the requisite acid number, that the acylating agent be reacted with the requisite polyethylene polyamine, and that the reactants be employed in proportions such that the resultant succinimide contains the requisite proportions of the chemically combined reactants, all as specified herein. When utilizing this combination of features, formulations containing detergent/dispersants may be formed which possess exceptional effectiveness in controlling or reducing the amount of induction system deposits formed during engine operation and which permit adequate demulsification performance.
As pointed out in the above listed patents, the acyclic hydrocarbyl-substituted succinic acylating agents include the hydrocarbyl-substituted succinic acids, the hydrocarbyl-substituted succinic anhydrides, the hydrocarbyl-substituted succinic acid halides (especially the acid fluorides and acid chlorides), and the esters of the hydrocarbyl-substituted succinic acids and lower alcohols (e.g., those containing up to 7 carbon atoms), that is, hydrocarbyl-substituted compounds which can function as carboxylic acylating agents. Of these compounds, the hydrocarbyl-substituted succinic acids and the hydrocarbyl-substituted succinic anhydrides and mixtures of such acids and anhydrides are generally preferred, the hydrocarbyl-substituted succinic anhydrides being particularly preferred.
The acylating agent used in producing the detergent/dispersants of this invention is preferably made by reacting a polyolefin of appropriate molecular weight (with or without chlorine) with maleic anhydride. However, similar carboxylic reactants can be employed such as maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, and hexylmaleic acid, including the corresponding acid halides and lower aliphatic esters.
The reaction between components (i) and (ii) is generally conducted at temperatures of 80°C to 200°C, more preferably 140°C to 180°C, such that a succinimide is formed. These reactions may be conducted in the presence or absence of an ancillary diluent or liquid reaction medium, such as a mineral lubricating oil solvent. Suitable solvent oils include natural and synthetic base oils having a volatility of 50% or less as determined by the test method described herein. Suitable synthetic diluent include polyesters, hydrogenated or unhydrogenated poly-α-olefin (PAO) such as hydrogenated or unhydrogenated 1-decene oligomer. Blends of mineral oil and synthetic oils are also suitable for this purpose. In a particularly preferred embodiment, the reactions are conducted in the substantial absence of an ancillary diluent oil so that the reaction product is essentially free of paraffinic mineral oils. By essentially free is meant that the reaction product contains less than about 1% by weight paraffinic mineral oil.
As used herein, the term succinimide is meant to encompass the completed reaction product from components (i) and (ii) and is intended to encompass compounds wherein the product may have amide, aidine, and/or salt linkages in addition to the imide linkage of the type that results from the reaction of a primary amino group and an anhydride moiety.
Diluent Oil. A key feature of this invention is the use of an unhydrotreated poly-α-olefin having a volatility of 50% or less and, optionally, a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less as a diluent in the formation of the fuel additive concentrate or as a key component in blends of gasoline and succinimide reaction product. It has been found surprisingly, and quite unexpectedly, that when particular succinimide and particular poly-α-olefins are admixed, with or without particular mineral oils, with gasoline in particular proportions, the octane requirement increase of internal combustion engines is effectively controlled. By "effectively controlled" is meant, that the formation of deposits which tend to increase the octane requirement are significantly inhibited, and/or engines initially containing heavy deposits, exhibit a substantial reduction in deposits when operated in accordance with the method of this invention.
The poly-α-olefins (PAO) useful in compositions and methods of this invention are preferably the unhydrotreated poly-α-olefins. As used herein, poly-α-olefin are unhydrogenated or unhydrotreated oligomers, primarily trimers, tetramers and pentamers of alphaolefin monomers containing from 6 to 12, generally 8 to 12 and most preferably 10 carbon atoms. Their synthesis is outlined in Hydrocarbon Processing, Feb. 1982, page 75 et seq. and essentially comprises catalytic oligomerization of short chain linear alpha olefins (suitably obtained by catalytic treatment of ethylene). The nature of an individual PAO depends in part on the carbon chain length of the original alphaolefin, and also on the structure of the oligomer. The exact molecular structure may vary to some extent according to the precise conditions of the oligomerization, which is reflected in changes in the physical properties of the final PAO. Since the suitability of a particular PAO as base lubrication oil is determined primarily by its physical properties, and in particular its viscosity, the various products are generally differentiated and defined by their viscosity characteristics. According to the present invention, polyalphaolefins having a viscosity (measured at 100°C) from 2 to 20 centistokes are particularly desirable for forming fuel additive compositions of this invention. Preferably, the polyalphaolefin has a viscosity of at least 8 centistokes, and most preferably about 10 centi-stokes at 100°C. The volatility of the poly-α-olefin is also a key feature of this invention and may be determined by the ensuing procedure.
To determine the volatility of the mineral oils and poly-α-olefins suitable for use with this invention, the following procedure is used. Mineral oil or poly-α-olefin ( 110-135 grams) is placed in a three-neck, 250 mL round-bottomed flask having a threaded port for a thermometer. Such a flask is available from Ace Glass (Catalog No. 6954-72 with 20/40 fittings). Through the center nozzle of the flask is inserted a stirrer rod having a Teflon blade, 19 mm wide x 60 mm long (Ace Glass Catalog No. 8085-07). The mineral oil or poly-α-olefin is heated in an oil bath to 300°C for 1 hour while stirring the oil in the flask at a rate of 150 rpm. During the heating and stirring, the free space above the oil in the flask is swept with 7.5 L/hr of air. The volatility of the oil thus determined is expressed in terms of the weight percent of material lost based on the total initial weight of material tested.
Mineral oils having suitable volatilities include naphthenic and asphaltic oils which are defined generally as those found along the Gulf Coast such as a Coastal Pale. A typical Coastal Pale may contain 3-5 wt. % polar material, 20-35 wt.% aromatic hydrocarbons, and 50-75 wt.% saturated hydrocarbons and have a molecular weight in the range of from 300 to 600. Asphaltic oils are defined as containing high molecular weight (ca > 800) compounds with high polar functionality and little or no pure hydrocarbon type compounds. Principal polar functionalities generally present in such asphaltic oils include carboxylic acids, phenols, amides, carbazoles, and pyridine benzologs. Typically, asphaltenes contain 40-50% by weight aromatic carbon and have molecular weights of several thousand. Asphaltic oils are generally found along the West Coast. Preferably the mineral oil has a viscosity at 100°F of less than 1600 SUS more preferably less than 1500 SUS, and most preferably between 800 and 1500 SUS at 100°F. It is highly desirable that the mineral oil have a viscosity index of less than 90, more particularly, less than 70 and most preferably in the range of from 30 to 60.
The weight ratio of succinimide to the diluent oil in the mixtures of this invention is a particularly key feature of this invention It has been discovered that a weight ratio of less than 1 part succinimide to 3 parts diluent oil achieves the purposes of this invention. Preferably the weight ratio of succinimide to diluent oil is in the range of from 1 : 1.5 to 1 : 3.0 and most preferably, the weight ratio is from 1 : 1.2 to 1 : 2.5.
The diluent oil desirably contains from 30 to 80 percent by weight mineral oil and from 70 to 20 percent by weight unhydrotreated polyalphaolefin. A more preferred diluent oil contains from 50 to 65 percent by weight mineral oil and from 35 to 50 percent by weight unhydrotreated polyalphaolefin. Particularly preferred is a diluent oil having from 55 to 60 percent naphthenic mineral oil and from 40 to 45 percent unhydrotreated polyalphaolefin.
Antioxidant. Various compounds known for use as oxidation inhibitors can be utilized in the practice of this invention These include phenolic antioxidants, amine antioxidants, sulfurized phenolic compounds, and organic phosphites, among others. For best results, the antioxidant should be composed predominantly or entirely of either (1) a hindered phenol antioxidant such as 2-tert-butylphenol, 2,6-di-tert-butylphenol,2,4,6-tri-tert-butylphenol,4-methyl-2,6-di-tert-butylphenol, 4,4′-methylenebis-(2,6-di-tert-butylphenol), and mixed methylene bridged polyalkyl phenols, or (2) an aromatic amine antioxidant such as the cycloalkyl-di-lower alkyl amines, and phenylenediamines, or a combination of one or more such phenolic antioxidants with one or more such amine antioxidants. Particularly preferred for use in the practice of this invention are tertiary butyl phenols, such as 2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and o-tert-butylphenol.
Demulsifier. A wide variety of demulsifiers are available for use in the practice of this invention, including, for example, polyoxyalkylene glycols, oxyalkylated phenolic resins, and like materials. Particularly preferred are mixtures of polyoxyalkylene glycols and oxyalkylated alkylphenolic resins, such as are available commercially from Petrolite Corporation under the TOLAD trademark. One such proprietary product, identified as TOLAD 9308, is understood to be a mixture of these components dissolved in a solvent composed of heavy aromatic naphtha and isopropanol. This product has been found efficacious for use in the compositions of this invention. However, other known demulsifiers can be used such as TOLAD 286.
Corrosion Inhibitor. Here again, a variety of materials are available for use as corrosion inhibitors in the practice of this invention Thus, use can be made of dimer and trimer acids, such as are produced from tall oil fatty acids, oleic acid linoleic acid, or the like. Products of this type are currently available from various commercial sources, such as, for example, the dimer and trimer acids sold under the HYSTRENE trademark by the Humko Chemical Division of Witco Chemical Corporation and under the EMPOL trademark by Emery Chemical. Another useful type of corrosion inhibitor for use in the practice of this invention are the alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors such as, for example, tetrapropenylsuccinic acid, tetrapropenylsuccinicanhydride,tetradecenylsuccinicacid, tetradecenylsuccinicanhydride,hexadecenylsuccinicacid, and hexadecenylsuccinic anhydride. Also useful are the half esters of alkenyl succinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as the polyglycols. Preferred materials are the succinic acids or derivatives thereof represented by the formula:

wherein each of R², R³, R⁵ and R⁶ is, independently, a hydrogen atom or a hydrocarbyl group containing 1 to 30 carbon atoms, and wherein each of R¹ and R⁴ is, independently, a hydrogen atom, a hydrocarbyl group containing 1 to 30 carbon atoms, or an acyl group containing from 1 to 30 carbon atoms.
The groups R¹, R², R³, R⁴, R⁵, and R⁶ when in the form of hydrocarbyl groups, can be, for example, alkyl, cycloalkyl or aromatic containing groups. Preferably R¹, R², R³, R⁴ and R⁵ are hydrogen or the same or different straight-chain or branched-chain hydrocarbon radicals containing 1-20 carbon atoms. Most preferably, R¹, R², R³, R⁴, and R⁵ are hydrogen atoms. R⁶ when in the form of a hydrocarbyl group is preferably a straight-chain or branched-chain saturated hydrocarbon radical.
Most preferred is a tetralkenyl succinic acid of the above formula wherein R¹, R², R³, R⁴ and R⁵ are hydrogen and R⁶ is a tetrapropenyl group.
Aromatic Hydrocarbon Solvent A wide variety of aromatic hydrocarbon solvents can be used with this invention such as benzene, and alkyl substituted benzene or mixtures thereof. Particularly useful are mixtures of o-, p-, and m- xylenes and mesitylene and higher boiling aromatics such as Aromatic 150 which is available from Chemtech. However, other mixtures of aromatic hydrocarbon solvents may also be used.
The relative proportions of the various ingredients used in the additive concentrates and distillate fuels of this invention can be varied within reasonable limits. However, for best results, these compositions should contain from 10 to 50 parts by weight (preferably from 20 to 35 parts by weight) of succinimide, up to 75 parts by weight (preferably from 50 to 65 parts by weight) of diluent oil, 0 to 5 parts by weight (preferably, from 1 to 3 parts by weight) of antioxidant, from 0 to 10 parts by weight (preferably, from 0.3 to 3 parts by weight) of demulsifier, from 0 to 75 parts by weight (preferably 5 to 25 parts by weight) of aromatic hydrocarbon solvent, and from 0 to 5 parts by weight (preferably, from 0.025 to 1.0 part by weight) of corrosion inhibitor per each one hundred parts by weight of fuel additive composition.
The above additive compositions of this invention are preferably employed in hydrocarbon mixtures in the gasoline boiling range or hydrocarbon/ oxygenate mixtures, or oxygenates, but are also suitable for use in middle distillate fuels, notably, diesel fuels and fuels for gas turbine engines. The nature of such fuels is so well known to those skilled in the art as to require no further comment. By oxygenates is meant alkanols and ethers such as methanol, ethanol, propanol, methyl-tert-butyl ether, ethyl-tert-butyl ether, tert-amyl-methyl ether, or combinations thereof. It will of course be understood that the base fuels may contain other commonly used ingredients such as cold starting aids, dyes, metal deactivators, octane improvers, cetane improvers, emission control additives, and antioxidants.
When formulating the fuel compositions of the invention, the additives are employed in amounts sufficient to reduce or inhibit octane requirement increase in an internal combustion engine. Generally speaking, the fuel additive comprising a succinimide, a unhydrotreated polyalphaolefin having a volatility of 50% or less and a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less will be employed in unleaded gasoline in minor amounts such that the gasoline portion of the fuel is the major component. By minor amount is meant less than 3000 parts per million parts of gasoline, preferably, less than 1500 parts per million parts of gasoline. A particularly preferred amount of additive is in the range of from 600 to 1200 parts per million parts of gasoline. The other components which are preferably used in conjunction with the detergent/dispersant and diluent oil can be blended into the fuel individually or in various sub-combinations. However, it is definitely preferable to blend all of the components concurrently using an additive concentrate of this invention as this takes advantage of the mutual compatibility afforded by the combination of ingredients when in the form of an additive concentrate.
The following Examples in which all parts are by weight illustrate, but are not intended to limit, this invention.

Example 1

A fuel additive concentrate is prepared from the following ingredients:

(a) 50 parts of a detergent/dispersant formed by reacting polyisobutenylsuccinic anhydride having an acid number of 1.1 (made by reaction of maleic anhydride and polyisobutene having a number average molecular weight of 950) with a commercial mixture approximating triethylene tetramine, in a mole ratio of 2:1 respectively.
(b) 75 parts of naphthenic mineral oil of Witco Corporation H-4053.
(c) 25 parts of 10 cSt unhydrotreated PAO.
(d) 3.5 parts of a demulsifier mixture composed of alkylaryl sulfonates, polyoxyalkylene glycols and oxyalkylated alkylphenolic resins in alkylbenzenes (TOLAD 9308).
(e) 2 parts percent of tetrapropenyl succinic acid supplied as a 50% solution in light mineral oil.

This concentrate is blended with gasolines and with diesel fuels at concentrations of 155.5 pounds per thousand barrels (PTB).

Example 2

Example 1 is repeated using each of the components set forth therein except 60 parts of (a); 60-80 parts of (b); 40-60 parts of (c); and in addition, 4 parts of a tertiary butylated phenol antioxidant mixture containing a minimum of 75 percent of 2,6-di-tert-butylphenol, 10 - 15 percent of 2,4,6-tri-tert-butyl-phenol, and 15-10 percent of 2-tert-butylphenol; 3 parts of Tolad® 286; and 2 parts of tetrapropenyl succinic acid supplied as a 50% solution in light mineral oil. This mixture is then blended with gasoline at a rate of 180 pounds per thousand barrels (PTB).

Example 3

Example 1 is repeated using each of the components set forth therein except that 75 parts of (a); 75-100 parts of (b); and 75 parts of (c); and in addition, 5 parts of a tertiary butylated phenol antioxidant mixture containing a minimum of 75 percent of 2,6-di-tert-butylphenol, 10-15 percent of 2,4,6-tri-tert-butyl-phenol, and 15-10 percent of 2-tert-butylphenol; 3.5 parts of Tolad® 9308; and 2 parts of tetrapropenyl succinic acid supplied as a 50% solution in light mineral oil. This mixture is then blended with gasoline at a rate of 225-250 pounds per thousand barrels (PTB).

Example 4

The effectiveness of the compositions of this invention to reduce or inhibit the octane requirement increase in an internal combustion engine is illustrated by a series of test performed on a 2.3L Ford Engine. The engine was run with the indicated amount of additive for 112 hours and the octane requirement increase was determined by standard octane requirement determination methods. Figure 1 is a graphic illustration of the effect different additive concentrations have on the octane requirement of the 2.3L Ford Engine.
The effectiveness of the compositions of this invention in reducing induction system deposits was demonstrated in a series of standard engine tests using the test gasoline formulation as in Examples 1, 2 and 3.

Example 5

In one set of tests -- the Briggs and Stratton engine test -- formulations of Example 1 were compared to an untreated gasoline. The tests utilized a Briggs & Stratton 3 Hp engine with SAE 10W-40 oil. The length of the tests were 150 hours. After breaking the engine in at varying speeds and loads, the engine was run at 3,000 RPM with a load of 500 Watts/0.67 Hp. The spark plug temperature was maintained at about 400°F. Oil level was checked often and the oil was changed after 80 hours. Valves were weighed before and after each test to determine the amount of deposits. Using Phillips J unleaded, untreated gel, the amount of intake valve deposits was measured. Results of the tests under the same test conditions are indicated in Table 1.

Example 6

In another series of tests using a 2.3L, 4 cylinder Ford engine and Union Oil Clear base fuel, test gasolines as in Example 2 were compared to an untreated fuel. Duration of the tests were 112 hours. The engine was prepared by cycling at 2,000 RPM with 0-4 BHP for 1 minute then 2,800 RPM at 37 BHP for 3 minutes. The oil was checked every 8 hours and was changed at 56 hours. At the end of the testing periods the intake valves and ports were removed and weighed. Results of testing with treated and untreated fuels under the same test conditions are as indicated in Table 2.

Example 7

In yet another test, a BMW 318 with automatic transmission, 1.8L PFI engine was run on untreated and treated Mobil regular unleaded fuel. The engine was run for 10,000 miles. During the testing, the BMW was operated 10% at city speeds in stop and go traffic, 20% at moderate speeds with infrequent stops, and 70% at highway speeds of 65 MPH. To accumulate the required mileage, the BMW was operated for 20 hours a day or 800 miles per day. The oil was changed according to the BMW maintenance schedule. The intake valves were removed and weighed after 5,000 and 10,000 miles. Results of the testing of various additive concentrations are as indicated in Table 3.

Example 8

In order to determine the potential for the compositions of this invention to prevent or at least control valve sticking, a series of valve sticking tests were performed with the formulation of Example 3 using the standard Volkswagon Wasser Boxer Valve Sticking test. The VW Boxer test consists of 3 consecutive runs of 13 cycles each run for 21 minutes unders varying speed load and down time. The engine was prepared, prior to running, by standard procedures. After each run the engine was stopped and the test cell temperature held at 5°C for a minimum of 16 hours. Then the compression of each cylinder was measured at 5°C. Any loss of compression is considered a failure. Table 4 illustrates the results of the valve sticking tests when an engine was operated on fuel containing the detergent/additive of this invention.

Claims

A fuel additive concentrate for controlling octane requirement increase in internal combustion engines comprising (a) the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl substituted succinic acylating agent; (b) an unhydrotreated poly-α-olefin having a volatility of 50% or less as determined by a test method described herein; and (c) optionally, (A) a mineral oil having a viscosity index of less than about 90, and a volatility of 50% or less as determined by a test method described herein.
The concentrate of Claim 1 further comprising a minor but effective amount of:
(B) an antioxidant;

(C) a demulsifier;

(D) an aromatic hydrocarbon solvent;

(E) a corrosion inhibitor; or any combination of any of components (A), (B), (C), (D) and (E).
The concentrate of claim 1 wherein the weight ratio of (a) to (b) plus (c) is less than 1:3.
The concentrate of Claim 3 wherein the weight ratio of (a) to (b) plus (c) is in the range of from 1:1.2 to 1:2.5.
The concentrate of any of the preceding claims wherein the polyamine is one or more alkylene polyamines, cyclic alkylene polyamines, acyclic alkylene polyamines, or a mixture of any two or more of the foregoing wherein each alkylene group contains from 1 to 10 carbon atoms; the acyclic hydrocarbyl substituent is a polyalkylene having from 64 to 80 carbon atoms; and the unhydrotreated poly-α-olefin has a viscosity of 10 cSt at 100°C.
The concentrate of Claim 5 wherein the polyamine is triethylene tetramine or a combination of ethylene polyamines which approximate triethylene tetramine.
The concentrate of any of the preceding claims containing a mineral oil having a volatility of 50% or less wherein the ratio of mineral oil to poly-α-olefin is in the range of from 3:1 to 0.5:1.
A motor fuel containing a major amount of an unleaded gasoline and a minor amount of the concentrate of Claim 1.
A motor fuel containing a major amount of hydrocarbons in the gasoline boiling range, or hydrocarbon/ oxygenate mixtures, or oxygenates and having a minor, but effective amount, of a fuel additive comprising (a) the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl substituted succinic acylating agent; (b) an unhydrotreated poly-α-olefin having a volatility of 50% or less as determined by a test method described herein; (c) and optionally, (A) a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less as determined by a test method described herein; (B) an antioxidant, or (C) a demulsifier, or (D) an aromatic hydrocarbon solvent, or (E) a corrosion inhibitor, or any combination of any two, three, four, or all five of components (A), (B), (C), (D) and (E).
A method for controlling octane requirement increase of internal combustion engines comprising providing for use as a fuel composition a major amount of an unleaded gasoline and a minor but effective amount of a octane requirement increase controlling mixture comprising
(a) the reaction product of polyamine ant at least one acyclic hydrocarbyl substituted succinic acylating agent,

(b) an unhydrotreated poly-α-olefin having a volatility of 50% or less as determined by a method described herein, and

(c) optionally, a mineral oil having a viscosity index of less than about 90 and a volatility of 50% or less as determined by a method described herein, whereby the octane requirement increase of an internal combustion engine is effectively controlled.