EP0282845A1 - Fuels containing small amounts of alkoxylate and polycarboxylic acid imide - Google Patents

Abstract

Fuels for petrol and diesel engines containing small amounts (A) of alkoxylates, which are obtained by reacting ethylene oxide, propylene oxide or butylene oxide with mono- or polyhydroxy compounds and have a molecular weight (molar masses, number average) of 500 to 6000 and (B) of imides or amide imides or mixtures thereof, of nitrilotriacetic acid and / or of ethylenediaminetetraacetic acid and amines or amine mixtures having 7 to 18 carbon atoms, of the formula I <IMAGE> in which X is identical or different radicals -HN-R or neighboring radicals X to form a Ring <IMAGE> mean, where m = 0 or 1 and R is unbranched or branched aliphatic radicals having 7 to 18 carbon atoms.

Description

The invention relates to fuels for gasoline and diesel engines containing an additive A) small amounts of alkoxylates obtained by alkoxylation of mono- or polyhydroxy compounds and B) small amounts of tri- or tetracarboxamides or -imides.

Carburetor and intake systems of gasoline engines, but also injection systems for fuel metering in gasoline and diesel engines, are contaminated by contaminants caused by dust particles from the air, unburned hydrocarbon residues from the combustion chamber and the ventilation gases from the crankshaft housing that are returned to the intake or intake system will. By returning these so-called "blow-by gases" to the intake part or the air filter, part of the oil mist that is created in the crankcase is brought back into the engine via the intake system and largely burned there, but they are noticeable Oil mist also deposits in the interior of the carburetor, in the intake ducts, on the intake valves and on the injection nozzles. High-performance carburettors are complex structures with very fine channels and bores and precisely calibrated nozzles for spraying and metering the fuel.

The high-performance injection units for gasoline and diesel engines are similarly complicated and prone to deposits of dirt particles. If there is only slight dirt and residue deposits in these fine control elements, nozzles and channels, their functionality will be greatly affected and usually deteriorated. The result of this is an incorrect composition of the fuel-air mixture, so that unburned or partially burned hydrocarbons occur to a greater extent in the exhaust gases.

At the same time, the ratio of carbon monoxide to carbon dioxide in the exhaust gases is adversely affected, i.e. higher amounts of carbon monoxide in the exhaust gas occur in the case of dirty injection units or intake systems.

To control these highly undesirable phenomena, fuel additives have been added to petrol or diesel fuels for years.

In the course of energy saving measures and for environmental reasons, there have also been constructive changes in the mixture preparation of modern high-performance engines in recent years. These measures aimed to reduce the proportion of carbon monoxide and burned hydrocarbons as well as of To minimize nitrogen oxides in the exhaust gas. This was essentially achieved by changing the air-fuel mixture. While petrol engines used to be operated essentially with or slightly below the theoretical air requirement, ie with λ = 0.9 - 1.0, this has changed in recent years. The key figure λ for the air-fuel mixture today is λ = 1.1 - 1.3, ie the gasoline engines are operated leaner in terms of fuel supply. One speaks of the so-called "lean concept".

These measures led to a significant reduction in the proportion of carbon monoxide or partially burned hydrocarbons in the exhaust gas, but unfortunately for thermodynamic reasons not to a reduction, but rather to an increase in the proportion of nitrogen oxides (NO _x ) in the exhaust gas.

A reduction in the NO _x content or a further reduction in carbon monoxide and partially burned hydrocarbons in the exhaust gas is possible by installing exhaust gas catalysts. As a result of these measures - due to the higher excess of air when the fuel is burned - in some cases significantly higher temperatures have occurred at the intake valves of the engines. This made it necessary to develop fuel additives with significantly improved thermal-oxidative stability.

In addition to the changed concepts for mixture preparation, there has also been a clear trend towards extending the oil change intervals in recent years. The result of this was not only an increased, but also a longer-lasting requirement for the performance of the engine oils. These changes in engine oils have also affected the requirements for fuel additives. As a result of the design, the fuel oil content (so-called fuel dilution) is always more or less present in the engine oils, and the corresponding amounts of fuel additives also get into the oil. Depending on the driving style and condition of the engine, the fuel dilution is in the order of 0.5 to approx. 3%. After engine oils have been driven much longer and, above all, hotter, the question of the oil compatibility of fuel additives also plays an important role.

It was therefore the object of the invention to provide thermally and oxidatively more stable fuel additives which keep the carburetor, the valves and the intake system or the injection nozzles clean and also show no undesirable side reactions in the engine or in the engine oil.

An important property of fuel additives is, in addition to keeping the inlet valves clean, the maintenance of their basic tech niche-mechanical functionality. Carburetor and valve cleaners based solely on condensation products made from amines or polyamines with mono- or polycarboxylic acids have an excellent clean-keeping effect, but - depending on their molecular structure - they accumulate over time in the form of a thin layer on top of them due to their high boiling point Valve plate and the valve stem (valve guide) of the inlet valves. Under certain driving conditions and especially at low outside temperatures, the sticky layer can become so viscous that the functionality of the valves is impaired. This can lead to loss of compression on individual cylinders and, in unfavorable cases, to engine failure due to valve insertion.

Therefore, such fuel additives have advantages that, as a result of their cleaning effect - which is desirable - form thin protective films in the intake systems (valve plate and valve stem), but the viscosity of these protective films at low temperatures must not be too high or their consistency must not be too sticky there are failures, ie that the inlet valves get stuck due to excessive stickiness of the valve stem.

It was therefore a further object of the present invention to find such fuel additives or additive combinations for petrol and diesel fuels which keep or clean the carburetor as well as the intake valves, injection nozzles and the entire injection system, but otherwise no negative side effects in the sense described above exhibit.

• (A) an Alkoxylaten, die durch Umsetzung von Ethylenoxid, Propylenoxid oder Butylenoxid mit Mono- oder Polyhydroxyverbindungen erhalten werden und ein Molekulargewicht (Molmassen, Zahlenmittel) von 500 bis 6000 auf­weisen und
• (B) an Imiden oder Amid-Imiden oder von deren Gemischen, aus Nitrilotri­essigsäure und/oder aus Äthylendiamintetraessigsäure und Aminen oder Amingemischen mit 7 bis 18 Kohlenstoffatomen, der Formel I
  
        in der X gleiche oder verschiedene Reste -HN-R oder benachbarte Reste X unter Bildung eines Ringes
  
  bedeuten, wobei
        m = 0 oder 1 ist und R unverzweigte oder verzweigte aliphatische Reste mit 7 bis 18 Kohlenstoffatomen bedeuten.

This task is solved by fuels for petrol and diesel engines that contain small amounts

• (A) on alkoxylates which are obtained by reacting ethylene oxide, propylene oxide or butylene oxide with mono- or polyhydroxy compounds and have a molecular weight (molar masses, number average) from 500 to 6000 and
• (B) on imides or amide-imides or mixtures thereof, from nitrilotriacetic acid and / or from ethylenediaminetetraacetic acid and amines or amine mixtures having 7 to 18 carbon atoms, of the formula I.
  
  in which X is the same or different radicals -HN-R or neighboring radicals X to form a ring
  
  mean where
  m is 0 or 1 and R is unbranched or branched aliphatic radicals having 7 to 18 carbon atoms.

The amount of additives (A) and (B) according to the invention added to petrol and diesel fuels is between 0.01 and 0.3% by weight, preferably between 0.005 and 0.15% by weight.

The weight ratio of components (A) and (B) is usually between 5: 1 to 1: 3.

Alkoxylates used are preferably butoxylates of mono- or polyhydroxy compounds or mixed alkoxylates using propylene / butylene mixed oxides. The proportion of butylene oxide or longer-chain alkylene oxide in the mixed alkoxylate is responsible for the oil solubility or oil compatibility of the alkoxide. The propylene oxide / butylene oxide ratio can be between 5:95 and 95: 5 parts by weight. Advantageous mixtures contain propylene oxide / butylene oxide in a ratio of 60:40 to 30:70. In principle, all butylene oxides, i.e. Butene-1, butene-2 or isobutene oxide or any mixtures of these oxides with one another or with propylene oxide are suitable for the preparation of the alkoxylates according to the invention. Effective alkoxylates are likewise obtained from mixtures of propylene oxide, butylene oxide and higher open-chain and cyclic alkene oxides or from the higher open-chain and cyclic alkene oxides alone.

Examples include: pentene-1-oxide, decene-1-oxide, cyclopentene oxide, cyclohexene oxide and cyclooctene oxide and vinyl-cyclohexene oxides.

Alcohols of the general formula come as mono- or polyhydroxy compounds
R (OH) _n ,
in which n is the numbers 1 to 4 and R is a C₁-C₂₀ straight-chain or preferably branched alkane, into consideration.

Typical examples are butanol, isobutanol, 2-ethylhexanol, isononanol, isodekanol, isotridekanol, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol , 1,6-hexanediol, trimethylolpropane, 1,2,4-butanediol and pentaerythritol.

The alkoxylates are prepared by the methods of the prior art, i.e. As a starting molecule, a mono- or polyhydroxy compound is placed in a reactor together with the catalyst (e.g. sodium hydroxide, potassium hydroxide or alkali alcoholates) and gassed with alkylene oxides or alkylene oxide mixtures or reacted with liquid alkylene oxides with stirring at temperatures from 120 to 150 ° C. After the reaction has ended, any gaseous alkylene oxide which has not reacted is drawn off under vacuum and the crude alkoxylate is optionally washed with water largely free of alkali. For complete removal of the alkaline catalyst e.g. when using potassium hydroxide, the alkoxylate can be washed with a sufficient amount of an aqueous solution of sodium pyrophosphate (Na₂H₂P₄O₇). Sodium potassium pyrophosphate precipitates as an insoluble double salt and can be filtered off.

In the case of the alkoxylates to be used according to the invention, it is not necessary to start from mixtures of the alkylene oxides in question in the case of mixed alkoxylates. It is also possible to react two or more alkylene oxides in succession with the mono- or polyhydroxy compound as the starting molecule. Alkoxylates, which are initially obtained by reacting mono- or polyhydroxy compounds only with a small amount of ethylene oxide (e.g. 1-5 mol ethylene oxide per hydroxyl group of the mono- or polyhydroxy compound), can also be obtained by subsequent reaction with a correspondingly large amount of higher alkylene oxides implement alkoxylates to be used according to the invention.

Possible components (B) are, for example, reaction products of nitrogen-containing polycarboxylic acids with mono-, oligo- or polyamines or technical amine mixtures, such as are described, for example, as mixed components in EP-A-6527.

The compounds according to (B) of the formula I are prepared by methods known per se, for example by reacting nitrilotriacetic acid or ethylenediaminetetraacetic acid with the amines or amine mixtures
R-NH₂
obtained at temperatures of 150 to 220 ° C usually 160 to 200 ° C. Depending on the desired product, the amines are used in a molar ratio of 2: 1 (cyclic diimide) or in an amount of 3 moles of amine or amine mixture per mole of ethylenediaminetetraacetic acid (amine imide) or 2 moles per mole of nitriloacetic acid (amide imide) or To a small extent, additional amounts applied. In most cases, amidimides or imides are obtained in this way in addition to minor amounts of amides, ie substitution of all carbonyl groups by one amide residue.

In particular, the procedure is such that the amine or amine mixture is placed in a stirred vessel under a nitrogen atmosphere and the nitriloacetic acid or ethylenediaminetetraacetic acid is introduced at approximately 80 ° C. and the mixture is stirred at 160 to 200 ° C. for 4 to 10 hours, at slowly reacting amines or amine mixtures also heated to a higher temperature until the acid number is less than 10.

As amines of the formula
R-NH₂
those with 7 to 18, preferably 8 to 14 carbon atoms are suitable. These amines can also have further amino groups, for example non-primary amino groups or alkoxy groups. Likewise, oxygen atoms can be present in the chain.

In particular, e.g. the following amines into consideration, where the alkyl radicals can be interrupted by nitrogen or oxygen atoms: 2-ethylhexylamine, n-dodecylamine, n-tridecylamine, n-pentadecylamine, stearylamine, 2-amino-5-dimethylaminopentane and 1- (2-ethylhexoxy) -propylamine- (3).

In some cases, the use of amine mixtures has also proven to be advantageous.

Depending on the composition of the mixtures of the alkoxylates according to the invention with the imides or amide imides of EP-A-6527, it is possible to use simultaneously highly stable, highly hydrated petroleum distillates (so-called less suitable for the desired effect). Carrier oils), as also described in EP-A-6527, to be dispensed with entirely or at least in part.

Fuel additives using the alkoxylates (A) and the polycarboximides can additionally contain a number of other known active components, such as sterically hindered substituted phenols as antioxidants, dipropylene glycol or similarly designed glycols as antiicing additives to protect the carburetor from ice formation, corrosion inhibitors, metal deactivators, Demulsifiers and antistatic agents to increase the conductivity of the fuels.

The effectiveness of the combination to be used according to the invention is demonstrated in the following by means of various test methods in comparison with the fuel additives customary in the market up to now.

The behavior during driving is decisive for the effectiveness of fuel additives, i.e. in a motor operated under practical or practical conditions on a motor test bench. For this purpose, the effect of the combination according to the invention was investigated in a number of test engines.

Testing the cleanliness effect in the Opel Kadett engine according to CEC method F-02-C 79

The valve cleaning effect of additive fuels is assessed in this test method after 40 hours. The conditions for the method are summarized in the table below.
Engine:
4-cylinder engine, 1.2 l displacement, 40 KW, carburetor 2 Solex PDSI

Engine oil:
Reference oil RL 51

Running time:
40 hours

Test program per cycle:
Stage 1: 30 s idling at 1000 rpm
Stage 2: 1 min at 3000 rpm 11.0 KW
Stage 3: 1 min at 1300 rpm 4.0 KW
Stage 4: 2 min at 1850 rpm 6.3 KW

Oil temperature in the oil pan 94 ± 2 ° C
Coolant temperature (outlet) 92 ± 2 ° C
Intake air temperature (idle) 100 ° C
Carbon monoxide content in the exhaust gas, at idle 3, 5 ± 0.5 vol.%

The results are evaluated as follows. The new inlet valves are cleaned or degreased with solvent before the test and weighed exactly to three decimal places. At the end of the test, the valves are removed. First of all, the stems or the valve tulips are assessed by checking the stickiness with finger pressure. The valves, including the stems, are then swung twice in n-heptane for 5 seconds and dried in air by swirling. The valves are then mechanically freed from the combustion residues adhering to the underside of the tulip after clamping on the shafts in a horizontally mounted drilling machine with the help of a wood chip or sanding cloth with a grain size of 400 and then at three points behind exactly weighed the comma. The Ab Bearings of all 4 valves are averaged and the result is given in mg / valve.

The carburettor is kept clean by evaluating the carburettor according to the CRC rating scale. Carburetor contamination with non-additive fuels generally gives a rating of 6.5 to 8.5. If effective carburetor-cleaning additives are present, the rating after the end of the test is between 8.0 and 10.0. The rating 10.0 corresponds to a completely clean carburetor.

Table 2 contains test results with fuels without the use of fuel additives (Ex. 1 to 3), as well as results of engine test runs using the components of the combination to be used according to the invention.

In addition to the Opel Kadett engine, a Daimler-Benz M 102 electric engine was also used to check the cleanliness in the intake system.

The test procedure is similar to the Opel Kadett test, the test conditions are shown in the following list:

Engine:
4-cylinder injection engine, 2.3 l displacement, 100 KW

Engine oil:
RL 51 or SAE 15W / 40, API-SF / CC

Running time:
40 to 150 hours

Test program per cycle:
Stage 1: 30 s idling at 800 rpm
Stage 2: 1 min at 3000 rpm 18.4 KW
Stage 3: 1 min at 1300 rpm 4.4 KW
Stage 4: 2 min at 1750 rpm 7.4 KW

Oil temperature in the oil pan 90 ± 3 ° C
Coolant temperature (outlet) 89 ± 3 ° C
Intake air temperature 30 ± 5 ° C

The valves are evaluated using the same method as for the Opel Kadett engine. Runtimes longer than 40 hours can also be selected to tighten the test conditions.

Example 12 (comparative example)

The test of non-additive gasoline was also carried out (as a comparison test as in Table 2, Ex. 1, 2, 3) in the Daimler-Benz M 102 electric motor. It was found that during the usual test runs over 40, 60, 80 or 150 hours with different specimens of the standard Daimler-Benz M 102 electric motor, fluctuating amounts of deposits were found on the intake valves. These fluctuations may be due to the production-related fluctuations within the manufacturing tolerances of the engine. The amount of valve deposits in mg / valve (as the average of the 4 individual values of each test run) strongly depends on the "condition" (i.e. on the total runtime or the number of tests previously carried out.

Table 3 shows some results for valve deposits of non-additive fuels in the Daimler-Benz M 102 electric motor. Each test run was carried out over a test period of 40 hours.

Example 12 (comparative example)

The individual additives A, B and E were tested in accordance with Table 2 in the M 102 E test engine. Table 4 contains the results.

Example 14

An additive mixture of the following composition was used:

24 parts by weight component F in Table 1
60 parts by weight of alkoxylate B in Table 1
16 parts by weight a high-boiling aromatic solvent (solvent naphtha with a boiling point of approx. 160 ° C, mainly consisting of C₉ + aromatics, such as commercial products Solvesso 150 or Shellsol AB)

500 g / t of a commercial leaded super fuel (West German refinery goods according to DIN 51 600) are added from this mixture and the engine test run in the Opel Kadett engine is carried out according to the regulations.
Valve deposit result: 0 mg / valve
Carburetor rating: Rating 9.9

Deposits of 23 mg / valve and a carburetor rating of 9.6 were obtained at a dosage of only 350 g / t additive dosage.

Example 15

The additive mixture was the same as that given in Example 14, but was tested in a Daimler-Benz M 102 E test engine. Additive dosage 800 g / t.

Result after 40 hours of operation
Valve deposits: 0 mg / valve
Result after 150 hours of operation
Valve deposits: 22 mg / valve

Example 16

An additive mixture of the following composition was used:

10 parts by weight component F in Table 1
25 parts by weight of alkoxylate B in Table 1
65 parts by weight the lubricating oil mixture G in Table 1

600 g / t of this mixture were dosed and tested as described in Example 14.
Result valve deposits 18 mg / valve
Carburetor rating 9.2

At a dosage of 800 g / t, the valve deposits are 0 mg / valve and the carburetor rating is 9.4.

Example 17

An additive mixture of the following composition was used:

25 parts by weight component E in Table 1
60 parts by weight of alkoxylate B in Table 1
10 parts by weight Dipropylene glycol
5 parts by weight Solvent naphtha according to Ex. 17

Of this mixture, 800 g / t was added to the test fuel and tested in the Daimler-Benz M 102 electric motor.

Result after 40 hours of operation: valve deposits 0 mg / valve.

Example 18

When using the additive mixture according to Example 17, but using equal amounts of component F instead of component E in Table 1, the following results were obtained:

Valve deposits less than 3 mg / valve.

Testing the valve stickiness in the intake valve with a 4-cylinder engine, type: Opel-Ascona, displacement 1.6 l, 66 KW

The engine is operated according to the same test cycle as the Daimler Benz M 102 electric motor. The clean-up effect for the intake valves is evaluated after 40, 80, 120 or 200 hours; the evaluation is carried out in the same way as for the Opel Kadett and Daimler-Benz engines.

The valve stickiness is checked visually. For this purpose, the cylinder head is stored in an inclined position of approx. 45-60 ° with the intake valves still inside. With non-additive fuels, where no valve sticking can be observed, the inlet valves slip through their own weight in a very short time out of the valve guide. Adhesive valves as a result of unsuitable fuel additives can be recognized by the fact that the inlet valves do not slide out of the guide due to their own weight or can only be moved out by mechanical assistance.

• Stufe 1: Freies Herausgleiten der Ventile innerhalb von 5 bis 10 s.
• Stufe 2: Allmähliches Herausgleiten der Ventile, Dauer mehr als 30 s.
• Stufe 3: Ventile gleiten nicht frei heraus, können jedoch mit der Hand herausgezogen werden.
• Stufe 4: Ventile kleben so fest, daß sie nicht mehr mit der Hand herausgezogen werden können.

A distinction is made between 4 levels for the assessment of valve movement:

• Stage 1: The valves slide out freely within 5 to 10 s.
• Level 2: Gradual sliding out of the valves, duration more than 30 s.
• Level 3: Valves do not slide out freely, but can be pulled out by hand.
• Level 4: Valves stick so firmly that they can no longer be pulled out by hand.

Example 19

Test runs were carried out in the 1.6 t engine, type Opel Ascona, to test the valve stickiness. All tests were carried out over a period of 200 hours. This corresponds to a fuel consumption of approx. 2000 l and an approximate running distance of 4000-5000 km. The results are shown in Table 4.

Test conditions for testing valve stickiness in practical driving tests

Engine:
Volkswagen, boxer engine, 1.9 l displacement, 44 KW

Driving program:
10 km with max. 50 km / h
10 km with max. 60 km / h
10 min standstill

According to this exchange program, a total of 130 km are driven per day. The vehicle is parked outdoors overnight. The next morning the following tasks are carried out and the behavior of the vehicle is described:
- Check compression
- Visual evaluation of the inlet valves or the valve stems using an endoscope through the candle openings
- start attempt (s)

The tests listed in the table below were carried out in accordance with the above test room. All tests were carried out using the same commercially available super fuel, leaded from a West German refinery.

In all tests, the outside temperature during the night of the vehicle was between +3 and -3 ° C. The temperatures in the engine compartment were between +3 and + 8 ° C the next morning before the measurement.

Claims (6)

1. Fuels for petrol and diesel engines containing small amounts (A) on alkoxylates which are obtained by reacting ethylene oxide, propylene oxide or butylene oxide with mono- or polyhydroxy compounds and have a molecular weight (molar masses, number average) from 500 to 6000 and (B) on imides or amide-imides or mixtures thereof, from nitrilotriacetic acid and / or from ethylenediaminetetraacetic acid and amines or amine mixtures having 7 to 18 carbon atoms, of the formula I.

in which X is the same or different radicals -HN-R or neighboring radicals X to form a ring

mean where
m is 0 or 1 and R is unbranched or branched aliphatic radicals having 7 to 18 carbon atoms. 2. Fuels according to Claim 1, characterized in that alkoxylates of mono- or polyhydroxy compound of the formula are used as component (A)
R (OH) _n used
in which n is the numbers 1 to 4 and R is a C₁-C₂₀ straight-chain or branched alkane. 3. Fuels according to claim 2, characterized in that butoxylates are used as component (A). 4. Fuels according to claim 1, characterized in that alkoxylates of propylene oxide and butylene oxide are used as component (A), the ratio of propylene oxide to butylene oxide being 5:95 to 95: 5. 5. Fuels according to claim 1, characterized in that the weight ratio of components (A) and (B) is 5 to 1 to 1 to 3. 6. Fuels according to claim 1, characterized in that they contain 0.01 to 0.3% by weight of the sum of components (A) and (B).