EP0081744A2 - Fuel additives for internal-combustion engines - Google Patents

Abstract

1. A fuel for Otto engines, containing a small amcunt of compounds of the formula I see diagramm : EP0081744,P13,F2 where R**1 is alkyl having a total of 3 to 24 carbon atoms and optionally substituted by a carboxylic acid amide or carboxylic acid ester group, R**2 and R**3 are identical or different and each denotes hydrogen or alkyl, preferably methyl or ethyl, X is an ethylene or propylene group, n is 1 to 10, preferably 1 to 5, and m is 1 to 50.

Description

The invention relates to fuels for gasoline engines containing an addition of small amounts of the alkoxylated amides of polyamines and carboxylic acids having 5 to 22 carbon atoms.

The carburetor and intake system of gasoline engines are increasingly loaded with contaminants that are caused by dust particles from the air, unburned hydrocarbon residues from the combustion chamber and the crankcase ventilation gases that are led into the carburetor. These residues shift the air-fuel ratio at idle and in the lower part-load range, so that the mixture is richer, the combustion is incomplete and, in turn, the proportions of unburned or partially burned hydrocarbons in the exhaust gas are increased and gasoline consumption increases.

It is known that in order to avoid these disadvantages, fuel additives are used to keep valves and carburetors clean. On the one hand, these additives are intended to prevent deposits of such residues or to detach residues, on the other hand, the additives must withstand thermal stress and must not strain the engine. Above all, the previously known carburetor detergents based on fatty acid amide or imidazoline had these disadvantages and, with good action as carburetor cleaners, had only slight cleaning properties at the inlet valve.

wobei

• R¹ eine gegebenenfalls durch eine Carbonsäureamid- oder Carbonsäureestergruppe substituierte Alkylgruppe mit insgesamt 3 bis 24 Kohlenstoffatomen,
• _R ² und _R ³ gleich oder verschieden sind und jeweils ein Wasserstoffatom oder eine Alkylgruppe, vorzugsweise eine Methyl- oder Ethylgruppe und
• X eine Ethylen- oder eine Propylengruppe bedeuten und
• n für Werte von 1 bis 10, vorzugsweise 1 bis 5 und
• m für Werte von 1 bis 50 steht.

It was therefore the object of the invention to find gasoline additives which clean the carburetor and valves without stressing the engine. These conditions, ie very good washing effect on valves and carburetor and a high thermal stability combine alkoxylated carboxylic acid amides of formula I ¹ when ppm in small amounts, for example, 10 to 2000, preferably 50 to 500 ppm, fuels for gasoline engines are added,

in which

• R ^{1 is} an alkyl group with a total of 3 to 24 carbon atoms, optionally substituted by a carboxamide or carboxylic ester group,
• _R ² and _R ^{3 are the} same or different and each represents a hydrogen atom or an alkyl group, preferably a methyl or ethyl group and
• X represents an ethylene or a propylene group and
• n for values from 1 to 10, preferably 1 to 5 and
• m stands for values from 1 to 50.

The alkoxylated carboxamides are obtained, for example, as follows: in a first stage, a carboxylic acid amide is prepared by reacting a carboxylic acid or a carboxylic acid mixture with an amine or an amine mixture, which is then alkoxylated with an alkylene oxide in a second stage. This alkoxylation can be carried out in one step with alkali analysis, but also in two steps, first reacting free NH groups with alkylene oxide in a thermal step and then alkoxylating the aminoalkanol obtained further in a second step.

The amidation according to stage A is generally carried out by known methods in such a way that the carboxylic acid is mixed with the amine in the desired molar ratio (between 1: 1 and 2: 1) and at temperatures between 80 ° C. and 220 ° C. preferably between 140 ° C and 180 ^o C, is distilled off at atmospheric pressure or under reduced pressure, water of reaction. To control the reaction, one can use the determination of the amount of water distilled off, but also the determination of the amine number or the acid number of the reaction mixture. The reaction does not have to be driven to the theoretical end point; Partially converted acid - amine mixtures can also be used in the following alkoxylation step. The amidation reaction can also be continued in part until the formation of imidazoline rings while distilling off further water of reaction.

The amides (II) described can also be obtained by reacting carboxylic esters, anhydrides, halides, etc. with amines by methods known from the literature.

Saturated monocarboxylic acids having 4 to 20 carbon atoms, but also half esters or half amides of dicarboxylic acids, the total number of C atoms of which is between 8 and 24, are suitable as carboxylic acids. Correspondingly, dicarboxylic acids with higher molecular weight alkyl side chains, such as alkenyl succinic acids, can also be used. The following may be mentioned as monocarboxylic acids: oleic acid, lauric acid, palmitic acid, isononanoic acid, 2-ethylhexanoic acid, naphthenic acids, dicarboxylic acids, maleic acid monotridecylamide, adipic acid monooctyl ester, octenyl succinic acid, etc.

Suitable amines of the formula IV are straight-chain but also branched polyamines, preferably polyethylene or polypropylene amine with three or more nitrogen atoms.

Examples include: diethylenetriamine, tetraethylenepentamine, dipropylenetriamine, tripropylenetetramine, aminopropylethylenediamine, N, N'-diaminopropylethylenediamine or polyethyleneimine with degrees of polymerization up to 35.

The amides or amide mixtures obtained by reaction with the carboxylic acids are then thermally at temperatures between 60 and 150 ° C, preferably between 80 and 140 ° C, with the addition of up to 10% water in a first step under pressure up to 20 bar an alkylene oxide with 2 to 4 carbon atoms or a mixture of these alkylene oxides to an alkanolamine. The water is then optionally distilled off under reduced pressure and, after addition of up to 5% alkaline or also acidic catalysts which are customary for alkoxylation, in a second step at temperatures between 100 and 160 ° C. and pressures up to 20 bar, preferably up to 12 bar with further alkylene oxide, preferably with 3 or 4 carbon atoms to a polyalkylene oxide. Suitable alkylene oxides include ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide and 2,3-butylene oxide. In particular, oxides or hydroxides of alkali or alkaline earth metals, preferably KOH, NaOH or LiOH, may be mentioned as catalysts; other acidic or alkaline alkoxylation catalysts customary in industry, such as BF ₃ dihydrate, CaO or NaOCH _3, are also suitable. The alkoxylation can also be carried out in one step, water being dispensed with and the alkoxylation catalyst being added to the amide immediately.

Fuels for gasoline engines are characterized by properties known per se. A definition can be found, for example, in the German DIN standard 51 600. According to ASTM, the volatility range at 100 ° F (37.8 ° C) is 6 lbs / sq. In. (0.41 bar) to └ ┘ 16 lbs / sq.in. (1.03 bar) and over a range of "50% points" in the ASTM D-86 test from 170 ⁰ F (77 ° C) to (132 ° C). The ASTM endpoint of petroleum spirit is between 350 ° F (176 ° C) and 450 ° F (232 ° C). Full specifications for gasoline are fully defined in United States Federal Specification VV-M-561 a-2 Oct. 30, 1954 as Fuel M, Regular and Premium grades of classes A, B and C.

The carboxamide oxalkylates to be used according to the invention have a pronounced cleanliness or cleaning action on the intake system (intake duct and intake valve) of gasoline engines. The carburettor also has a cleaning and purifying effect when additives of the described class of compounds are added to petrol.

• - Vergaserdetergents (wenn die bereits vorhandene Vergaserwirksamkeit verstärkt werden soll), deren thermische Stabilität geringer als die der beanspruchten Verbindungsklasse sein kann,
• - spezielle Schmierölfraktionen,
• - Antioxidantien auf Basis sterisch gehinderter Phenolderivate oder p-Phenylendiaminderivate,
• Korrosionsinhibitoren zum Schutz von Stahl, Buntmetallen, Blei und Vergaserlegierungen gegen korrosive Angriffe des Kraftstoffes,
• - antistatische Zusätze, welche die Leitfähigkeit des Kraftstoffs erhöhen und dadurch die Gefahr statischer Aufladung bei Umfüllvorgängen verringern,
• - Vergaservereisungsverhinderer auf Basis gefrierpunktserniedrigender Oligoglykole oder/und an der Grenzfläche Metall/Luft-Kraftstoffgemisch wirksamer Verbindungen.

The use of the compounds of formula I can be used both alone - where appropriate, the oxo-synthesis of C pre-dissolved in a solvent such as xylene, toluene, alcohol, isobutanol, byproducts ₄ -C1 ₅ alcohols or a gasoline-section for ease of blending into gasolines - as well as in Combination with other additives. Suitable components for such a combination are, for example

• Carburetor detergents (if the already existing carburetor effectiveness is to be increased), the thermal stability of which may be lower than that of the claimed compound class,
• - special lubricating oil fractions,
• Antioxidants based on sterically hindered phenol derivatives or p-phenylenediamine derivatives,
• Corrosion inhibitors to protect steel, non-ferrous metals, lead and carburetor alloys against corrosive attacks by the fuel,
• - antistatic additives which increase the conductivity of the fuel and thereby reduce the risk of static charging during refilling processes,
• - Carburetor icing inhibitors based on freezing point-lowering oligoglycols and / or compounds effective at the metal / air-fuel mixture interface.

Preparation of the compounds to be used according to the invention

General rule

Level A:

The carboxylic acid and the polyamine are mixed in the molar ratios shown in the tables and the mixture is first stirred at 120 to 130 ° C. under nitrogen.

Then the temperature is raised to 160 to 180 ° C. and at the same time water of reaction is distilled off until the desired final acid number is reached.

Level B, step 1:

The amide thus obtained is reacted with the addition of 5% water in the autoclave at pressures up to 10 bar and temperatures of 115-125 ⁰ C until a constant pressure with the indicated amounts of alkylene oxide in the tables; the water is distilled off again at 90 ° C. and a reduced pressure of 20 to 60 mbar and the product is processed in step 2:

Stage B, step 2:

The product obtained according to B is treated with 1% KOH powder and up to 10 bar to constant pressure with the desired amount of alkylene oxide alkoxylated at 135 to 145 ⁰ C in an autoclave at printing.

Examples of use

To test the effectiveness of the compounds to be used according to the invention on the carburetor and intake system of gasoline engines, engine tests were carried out, the results of which are given below.

For this purpose, an Opel Kadett engine was used, which is equipped with two carburettors. This experimental arrangement allows the simultaneous investigation of two fuels, of which only one fuel can contain an additive or both fuels can contain different additives.

The test engine (power 46 KW / 60 HP at 5200 rpm) is operated for 40 hours according to the following repetitive load and speed cycle:

Further operating data:

At the start of the experiment, the CO content in the exhaust gas is set to 3.5 ± 0.5% by volume.

Such a 40-hour cycle corresponds to a distance traveled of around 2,000 kilometers by road.

┌The carburetor and valve cleanliness was rated according to the "CRC rating" scale for diesel engines (CRC merit rating 10.0 = 100% clean).

The results summarized in the following table were determined with the same petrol (ROZ 98-99, MOZ 88-88.5, 0.15 g / l lead) under the test conditions described above.

As can be seen from Table 2, additional amounts of 100 ppm by volume already significantly reduce the valve deposits. In most examples, the carburettor ratings are also 0.5 to 1.5 points higher than the basic value found with non-additive fuel.

With the addition of 200 vol.ppm, only minor deposits are found on the inlet valve.

Even higher doses than are required to keep the intake system clean, as can occur, for example, in the event of faults in automatic or semi-automatic dosing devices, have no side effects on the gasoline engine, as has been shown in tests with 500 and 1000 ppm of the acid amide alkoxylates to be used.

There were no additive residues in the intake pipes or in the combustion chamber itself.

Lines 11 and 12 of Table 2 show the results of test bench tests with the Opel Kadett engine, in which the claimed compound class with an antioxidant (C) and a component that is particularly effective on the carburetor (D) was added to the fuel in the form of a multifunctional package . The advantages of the selected combination are shown by the carburettors and intake valves, which are practically completely free of deposits.

Claims (2)

1. Fuels for gasoline engines, characterized by a low content of compounds of formula I.

in which _R ^{1 is} an alkyl group with a total of 3 to 24 carbon atoms, optionally substituted by a carboxamide or carboxylic ester group, _R ² and _R ^{3 are the} same or different and each represents a hydrogen atom or an alkyl group, preferably a methyl or ethyl group and X represents an ethylene or a propylene group n for values from 1 to 10, preferably 1 to 5 and m stands for values from 1 to 50. 2. Fuels for gasoline engines according to claim 1, characterized by a content of 10 to 2000 ppm of the compounds of formula I.