EP0548617A2 - Fuels for spark ignition engines - Google Patents

Abstract

Fuels for gasoline engines contain a combination of a nitrogen-containing detergent component and an alkoxylate as a carrier oil component, the alkoxylate being a dialkylphenol-initiated propoxylate.

Description

The invention relates to fuels for gasoline engines which contain small amounts of a combination of a nitrogen-containing detergent component and a carrier oil component, the carrier oil component comprising dialkylphenol-started propoxylates.

Carburetor and intake system of gasoline engines, but also injection systems for fuel metering in gasoline and diesel engines, are increasingly contaminated by contaminants 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 richer, the combustion incomplete and in turn the proportions of unburned or partially burned hydrocarbons in the exhaust gas and the gasoline consumption increases.

It is known that in order to avoid these disadvantages, fuel additives are used to keep valves and carburetor or injection systems clean (see, for example: M. Rossenbeck in catalysts, surfactants, mineral oil additives, ed. J. Falbe, U. Hasserodt, p. 223 f ., G. Thieme Verlag, Stuttgart 1978).

Depending on the mode of action, but also on the preferred site of action of such detergent additives, a distinction is made between two generations.

The first generation of additives could only prevent the formation of deposits in the intake system, but not remove existing deposits again, whereas the modern additives of the second generation can do both ("keep-clean" and "clean-up effect") and because of changed thermal properties, in particular also at zones of higher temperatures, namely at the inlet valves.

The question of the increase in the octane number requirement of a gasoline engine due to deposits in the combustion chamber over a certain period of time, and the possibility of intervening positively through targeted fuel additives, are increasingly becoming the focus of interest in the development of new additives.

By cleverly combining such detergents that keep the inlet system clean with other components, a broader spectrum of action of such formulations can be achieved.

In particular, the so-called carrier oils play a central role here.

On the one hand, it is possible to increase the efficiency of the detergents in the gasifier or intake system with special, mostly synthetic carrier oil components due to synergistic effects. Certain additives only develop this effect in combination with an oil.

On the other hand, the addition of carrier oil can have a positive effect on engine areas which are normally not reached by the conventional additives, which mainly work in the intake system.

Above all, the already mentioned combustion chamber deposits (ORI problem) should be mentioned.

US Pat. No. 4,877,416 discloses fuel mixtures which, in addition to an amine as detergent component, contain a carrier oil. Poly (oxyalkylene) monools with hydrocarbon end groups are mentioned as carrier oil. A large number of possible radicals are mentioned as hydrocarbon end groups, including in particular C₇-C₃₀-alkylphenyl. As an example, a carrier oil is described which was obtained by butoxylation of dodecylphenol.

In addition to the effects of keeping valves and intake system clean and preventing combustion chamber deposits, the compatibility with one another must also be taken into account when selecting additives. Thus, the detergents and carrier oils, if they are present in a concentrate, must not lead to depositions or phase separation. This is according to US 4,877,416 for the alkylphenol-started carrier oils e.g. achieved in that butylene oxide is used as the alkylene oxide, which, however, is relatively complex to produce and its use is cost-intensive.

It was therefore the task of finding combinations of additives for fuels which, on the one hand, have a synergistic effect with regard to keeping the intake system clean in gasoline engines, on the other hand keep the increase in the octane requirement of an engine as small as possible or even prevent it, and which are well compatible with one another in concentrated solution , ie don't segregate. The additives should also be made from easily accessible materials and should be thermostable.

• a) 10 bis 5 000 ppm einer Stickstoff-haltigen Detergens-Komponente und
• b) 10 bis 5 000 ppm eines Alkoxylats der folgenden Formel I
  

in der bedeuten

R¹ und R²

unabhängig voneinander einen verzweigten oder unverzweigten C₆-C₃₀-Alkylrest,

einer der beiden Reste R³ Methyl und der andere Wasserstoff und

n

= 1 bis 100.

This task is solved by fuels for gasoline engines that contain a combination of

• a) 10 to 5,000 ppm of a nitrogen-containing detergent component and
• b) 10 to 5000 ppm of an alkoxylate of the following formula I
  

in the mean

R1 and R2

independently of one another are a branched or unbranched C₆-C₃₀ alkyl radical,

one of the two radicals R³ is methyl and the other is hydrogen and

n

= 1 to 100.

Surprisingly, it has been shown that the alkoxylates according to the invention, although no butylene oxide is used for their preparation, have good compatibility with the nitrogen-containing detergent component and also prevent the deposits mentioned in the inlet system and in the combustion chamber.

It has been found to be particularly advantageous that the alkoxylates of the formula I according to the invention also provide compatibility with the detergent when a monoalkyl-substituted propoxylate is present as an additional component of the carrier oil component, although this propoxylate is not readily compatible with the Nitrogen-containing detergent component is compatible.

In addition to component b), the carrier oil component can therefore also comprise 10 to 5,000 ppm (based on the fuel) of a monoalkylphenol-started propoxylate, the structure given in formula I applying to this propoxylate, with the proviso that R 1 is eliminated, and in particular, the amount of the monoalkylphenol started propoxylate is not greater than the amount of the dialkylphenol started propoxylate according to formula I.

It is also possible to add other carrier oil components to the additive combination according to the invention, e.g. Esters from monocarboxylic acids or polycarboxylic acids and alkanols or polyols, as described in DE 38 38 918 A1.

Compounds in which R¹ and / or R² are a branched or unbranched C₇-C₁₈ alkyl radical and n = 5 to 50, in particular n = 7 to 30, are used as preferred alkoxylates.

The fuels preferably contain 20 to 2000 ppm, in particular 50 to 1000 ppm (all ppm data are in each case based on the weight) of the detergent component or of the alkoxylate b).

In principle, any known of the products suitable for this purpose can be used as the nitrogen-containing detergent component in the mixture with the carrier oils according to the invention, such as those e.g. with J. Falbe, U. Hasserodt, catalysts, surfactants and mineral oil additives, G. Thieme Verlag Stuttgart 1978, p. 221 f. or in K. Owen, Gasoline and Diesel Fuel Additives, John Wiley & Sons 1989, pp. 23 ff.

Compounds with an amine, amide or imide group, in particular polyisobutylamines according to EP 0 244 616, ethylenediaminetetraacetic acid amides and / or imides according to EP 0 188 786 or polyether amines according to EP 0 356 725, are preferably used, referring to the definitions in these references reference is hereby made.

Mixtures of such detergents can also be used.

Amides or imides of polyisobutylene succinic anhydride, polybutene polyamines and long-chain carbonamides and imides are suitable as further detergents or additional dispersants.

The preparation of the alkoxylates is well known and e.g. described in EP 376 236 A1.

The dialkylphenols used as starters are prepared in a customary manner by Friedel-Crafts alkylation of phenols with the corresponding olefins or olefin mixtures.

The propoxylates according to the invention have excellent compatibility, particularly with the polyisobutylamines already mentioned in the respective formulations.

They support their effect as an inlet system cleaner, among other things in terms of saving detergents.

Leaded and especially unleaded regular and premium gasoline are suitable as fuels for gasoline engines. The gasolines can also contain components other than hydrocarbons, e.g. Alcohols for methanol, ethanol, tert-butanol and ethers, e.g. Contain methyl tertiary butyl ether. In addition to the alkoxylated polyetheramines to be used according to the invention, the fuels generally also contain further additives such as corrosion inhibitors, stabilizers, antioxidants and / or further detergents.

Corrosion inhibitors are mostly ammonium salts org. Carboxylic acids which tend to form films due to the structure of the starting compounds. Amines to lower the pH are also often found in corrosion inhibitors. Heterocyclic aromatics are mostly used as non-ferrous metal corrosion protection.

Antioxidants or stabilizers include, in particular, amines such as para-phenylenediamine, dicyclohexylamine, morpholine or derivatives of these amines. Phenolic antioxidants such as 2,4-di-tert-butylphenol or 3,5-di-tert-butyl-4-hydroxiphenylpropionic acid and their derivatives are also added to fuels and lubricants.

Various authors (see e.g. US 4,877,416) use the results of thermogravimetric analyzes as a measure of the effectiveness with regard to combustion chamber deposits, since a general engine test for this does not yet exist.

On the one hand, thermogravimetric analyzes provide information about the thermal strength of a sample, for example a thermo-oxidative condition. On the other hand, they allow conclusions to be drawn about the formation of deposits or residual amounts after such a thermo-oxidative treatment. Experience has shown that the high thermal load-bearing capacity combined with the least possible to vanishing residue formation is favorable for use as carrier oil in the sense of this invention.

The alkoxylates of longer-chain dialkylphenols according to the invention meet all of these requirements (synergism with detergents, proven in the engine test; excellent thermooxidative properties, proven by thermogravimetric analysis) to a high degree.

The additive combination of nitrogen-containing detergent component and alkoxylate as carrier oil component is preferably provided as a concentrate which contains 10 to 80% by weight, in particular 30 to 60% by weight, of the detergent component and 5 to 70% by weight .-%, in particular 20 to 60 wt .-% of the carrier oil component, ie of the propoxylate. To complete to 100% by weight, the concentrate contains a suitable solvent, e.g. aromatic and / or aliphatic hydrocarbons, especially heavy naphtha (Solvesso®).

The products are tested for suitability as fuel additives using an engine test:
According to CEC-F-02-T-79, the effectiveness as a valve cleaner is tested.

Examples Preparation of an alkoxylate according to the invention

300 parts by weight of a mixture of 55% by weight of dinonylphenol and 45% by weight of nonylphenol are placed in 0.8 part by weight of K-tert-butoxide in autoclaves and with 620 parts by weight of propylene oxide at 120 to 125 ° C implemented. After the reaction has ended, the propoxylate obtained in this way is treated with magnesium silicate until the potassium content is below 1 ppm.

Results of the engine tests

Tests as an intake system and valve cleaner product Deposits [mg] * valve no. 1 2nd 3rd 4th Basic value without additives 417 289 176 660 Polyisobutylamine ¹⁾ 200 ppm + 200 ppm mineral oil ³⁾ 70 83 135 121 Polyisobutylamine (200 ppm) + 200 ppm polyether ²⁾ 0 92 16 216 Polyisobutaylamine ¹⁾ 200 ppm + 200 ppm alkoxylate according to the invention according to the above example 0 0 0 0 * according to CEC-F-02-T-79 ¹⁾ according to DE-OS 36 11 230 ²⁾ longer-chain alcohol butoxylate according to US 5,004,478 ³⁾ SN 500

Result of the thermogravimetric analysis

The thermogravimetry curve shown in the figure shows the relative decrease in mass m / m _o as a function of temperature at a heating rate of 2 ° C. per minute and in the presence of air. The half-life temperature of 260 to 270 ° C indicates sufficient thermo-oxidative stability; at higher temperatures the product disintegrates almost without residue (m is the mass measured in each case, m _o the initial mass).

Claims (6)

Fuels for gasoline engines containing a combination of a) 10 to 5,000 ppm of a nitrogen-containing detergent component and b) 10 to 5000 ppm of an alkoxylate of the following formula I

in the mean R¹ and R² independently of one another are a branched or unbranched C₆-C₃₀ alkyl radical, one of the two radicals R³ is methyl and the other is hydrogen and n = 1 to 100. Fuels according to claim 1, characterized in that the detergent component a) is at least one compound having an amine, amide or imide group. Fuels according to claim 2, characterized in that the detergent component a) is or contains a polyisobutylamine. Fuels according to Claim 1, characterized in that R¹ and / or R² represent a branched or unbranched C₇-C₁₈ alkyl radical. Fuels according to claim 1, characterized in that n = 5 to 50, in particular 7 to 30. Concentrate of components a) and b) according to claim 1 in a solvent containing 10 to 80% by weight of the nitrogen-containing detergent component a) and 5 to 70% by weight of the alkoxylate b) of the formula I and one for Completion to 100 wt% required amount of solvent.

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