AU735528B2

AU735528B2 - Method for defoaming fuels

Info

Publication number: AU735528B2
Application number: AU19642/99A
Authority: AU
Inventors: Frank Bongardt; Bernd Boutty; Thorsten Lohl; Peter Neumann; Gunter Uphues
Original assignee: Cognis Deutschland GmbH and Co KG
Current assignee: BASF Personal Care and Nutrition GmbH
Priority date: 1997-12-04
Filing date: 1998-11-25
Publication date: 2001-07-12
Anticipated expiration: 2018-11-25
Also published as: EP1036141A1; AU1964299A; DE19753792A1; CA2312064A1; WO1999029811A1; JP2001526300A

Description

Method for Defoaming Fuels This invention relates to a process for defoaming fuels, more particularly diesel fuels, to the use of certain quaternary ammonium compounds as defoamers for fuels and to a diesel fuel containing these quaternary ammonium compounds.

Fuels, more particularly the hydrocarbon mixtures used in diesel fuels, have the unpleasant property of generating foam with air during the filling of storage containers, such as storage tanks and fuel tanks of motor vehicles. This results in delays in the filling process and in inadequate filling of the tank. Accordingly, it is standard practice to add defoamers to the fuels. These defoamers are supposed to be effective in low concentrations and not to interfere in any way with the combustion process of the fuel, for example through the formation of residues which adversely affect the performance of the engine.

Various defoamers for fuels are known from the literature. They are generally siliconecontaining compounds, as described for example in EP 773 278 Al. Unfortunately, additives such as these can lead to the unwanted coating of the catalyst or filter surfaces of the engines with silicon dioxide which is formed during combustion of the fuel.

In addition, modern fuels are provided with various additives, for example corrosion inhibitors, friction modifiers, which are used to reduce wear, and engine-cleaning additives. Unfortunately, elaborate and expensive tests have to be carried out in order to prevent the individual additives from interacting with one another. There is therefore an increased demand for additives with a broad action spectrum.

Accordingly, the problem addressed by the present invention was to provide silicone-free additives for defoaming fuels. It has surprisingly been found that certain quaternary ammonium salts have excellent properties as defoamers for fuels.

Accordingly, the present invention relates to a process for defoaming fuels in which an effective quantity of at least one compound corresponding to formula 1 O R3

P

(I)

in which R 1

R

2 and R 3 independently of one another represent an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms, an aryl or alkylaryl group or a group corresponding to formula (11): 0 0}kpR4 (1

(I)

where A- is an anion, n is the number 2 or 3, p is a number of 1 to 3 and R 4 is an alkyl or alkenyl group containing 7 to 21 carbon atoms and 0, 1, 2 or 3 double bonds, is added to the fuel.

The compounds corresponding to formula are known and are mainly used as fabricsoftening components or for the antistatic finishing of fabrics. Examples of compounds corresponding 74N- o formula can be found in WO 94106899 and DE 42 03 489 Al (Henkel KGaA) which disclose C08275 quaternary diester amine compounds in fabric softeners. EP 239 910 A2 also describes fabric-care compositions containing readily biodegradable quaternary mono- and diester amine compounds.

It is known from applicants' DE 196 49 285.8 that the compounds corresponding to formula (I) can also have corrosion-inhibiting effects. This document discloses a process for protecting metal surfaces against corrosion in liquid media, more particularly crude oil. However, the document in question does not contain any references to the defoaming effect of these compounds. Nor is it apparent from the document in question that the compounds are suitable as an additive for fuels, more particularly diesel fuels.

Fuels in the context of the present application are understood to be any energy-producing materials of which the free combustion energy is converted into mechanical work. These include all types of automotive and aircraft fuels which are liquid at room temperature/normal pressure.

Automotive fuels, for example for car and truck engines, generally contain hydrocarbons, for example gasoline or relatively high-boiling petroleum fractions.

The process according to the invention is particularly suitable for defoaming diesel fuels. Diesel fuels are substantially non-inflammable mixtures of liquid hydrocarbons which are used as fuels for constant-pressure combustion or compression-ignition engines. Their composition is variable and depends upon the method of production. Diesel fuels are obtained from gas oil by cracking or from tars which are obtained in the low-temperature carbonisation of lignite or hard coal. Standard products have a density of 0.83 to 0.88glcm 3 a boiling point of 170 to 360 0 C and flash points of 70 to 100 0

C.

In the process according to the invention, the compounds corresponding to formula are added to the fuel in effective quantities. Effective concentrations are preferably between 5 and 1000ppm and more preferably between 10 and 50ppm, based on the fuel as a whole. The compounds corresponding to formula are effective defoamers for fuels and also have a corrosioninhibiting effect.

The compounds corresponding to formula are industrially quaternised mono-, di- or trifatty acid amine ester compounds which can be obtained by known synthesis methods, see for example EP 293 955 A2 and EP 293 953 A2. The quaternary compounds can be formed, for example, by reaction of tertiary mono-, di- or trialkanolamines, preferably triethanolamine or triisopropanolamine or methyl diethanolamine or dimethyl ethanolamine, with saturated or unsaturated linear or branched C8- 22 fatty acids or derivatives thereof, such as esters or chlorides. The esters formed in the reaction with the alkanolamines are then quaternised, for example with methyl chloride, benzyl chloride or dimethyl sulfate. Suitable fatty acids are, for example, the saturated representatives, such as caprylic, capric, lauric, myristic, palmitic, stearic or arachic acid and mixtures thereof. Suitable unsaturated fatty acids are, for example, linoleic, linolaidic or linolenic acid. Suitable derivatives are, in particular, the alkyl esters and preferably the methyl esters of the fatty acids mentioned above. Naturally accumulating fatty acid mixtures of both animal and vegetable origin are also suitable. Coconut and palm kernel A fatty acids are particularly preferred.

Compounds corresponding to formula in which p is the number 1 and n has a value of 2, are .pferably used in the process according to the invention. Compounds of which the anions are C08275 selected from the group consisting of halide, methosulfate and methophosphate are particularly preferred for use in the process according to the invention. The preferred anion is chloride.

It has proved to be of particular advantage to use mixtures of the above-mentioned compounds corresponding to formula in the process according to the invention because they have been found to develop a particularly good defoaming effect. Mixtures of compounds corresponding to formula in which R 1 and R 2 represent a group corresponding to formula (II) and R 3 is an alkyl group containing 1 to 4 carbon atoms or a benzyl group, and compounds corresponding to formula in which R 1 and

R

2 represent a methyl group and R 3 is a C1.

4 alkyl group or a benzyl group, in a ratio by weight of 2:1 to 1:2 are preferred. Mixtures of these compounds in a ratio by weight of 1:1 are preferably used in the process according to the invention.

The present invention also relates to the use of compounds corresponding to formula as defoamers for fuels, more particularly diesel fuels. To this end, the compounds corresponding to formula may be added to the fuels either directly or in the form of solutions or dispersions in suitable solvents. Particularly suitable solvents are short-chain alcohols containing 1 to 6 carbon atoms, more particularly ethanol, propanol and isopropanol, or aliphatic or aromatic hydrocarbons, such as hexane, heptane or toluene. The solutions or dispersions preferably contain the compounds corresponding to formula in quantities of 10 to The present invention also relates to a diesel fuel which contains compounds corresponding to formula in quantities of 5 to 1000ppm. The diesel fuel according to the invention is preferably a low-sulfur diesel fuel with a sulfur content of at most 0.2wt% and preferably of at most 0.005wt%. The diesel fuel may contain other typical additives, for example friction modifiers, flow improvers, anti-waxsetting additives or other typical corrosion inhibitors. However, the diesel fuel is preferably free from additional corrosion inhibitors.

Examples Production of the additives Additive 1 (El): 279.7g (1.75mol) of caprylic acid methyl ester and 74.5g (0.5mole) of triethanolamine were introduced into a 500mL stirred reactor together with 0.5wt% (based on the total quantity) of titanium tetrabutylate as catalyst. The mixture was then stirred for 10 hours at 185°C until at least 90% of the methanol to be theoretically formed (48g) had distilled off. Excess and unreacted caprylic acid methyl ester was distilled off in a thin-layer evaporator at 160°C/3 x 10- 2 mbar pressure. Yield: 228.0g of a low-viscosity, yellow coloured residue containing 2.67% of titratable nitrogen and having a hydroxy value (OHV) of 13.

105.1g (0.2mol, based on titratable nitrogen) of the residue obtained were introduced into a 250mL stirred reactor and 24.2g (0.19mol) of dimethyl sulfate were then added dropwise at The reaction mixture was then stirred for another 5 hours at 90°C and subsequently concentrated.

The solid residue was then recrystallised from ethyl acetate, a product containing 0.02% of residual titratable nitrogen being obtained in a yield of 62.8g.

Additive 2 (E2): 0 4 444.4g (2.0mole) of coconut fatty acid methyl ester and 198.0g (2.2mole) of dimethyl e olamine were introduced into a 1000mL stirred reactor together with 0.2% (based on the total 4 C08275 quantity) of titanium tetrabutylate as catalyst. The reaction mixture was then heated while stirring to the reflux temperature. The product was subsequently distilled under a pressure of 10mbar. The main fraction was a low-viscosity liquid containing 4.43% of titratable nitrogen.

For quaternisation, 173.6g (0.55mol, based on titratable nitrogen) of dissolved in 60g of isopropanol were introduced into the reactor. After heating to 80 0 C, 66.4g (0.52mole) of benzyl chloride were added dropwise, followed by stirring for 5 hours at 85°C. The medium-viscosity end product contained 80% of isopropanol and had a residual content of 0.13% of titratable nitrogen.

Defoaming test of diesel were introduced into a 100mL gas jar and shaken 10 times. The time taken by the foam formed to collapse was then measured. The measurement was terminated when the foam carpet broke up and the foam-free surface was visible. The measurements were carried out with additive-free diesel and diesel to which the defoamers according to the invention had been added in a concentration of 30ppm (active substance) in the form of a solution in toluene. The improved defoaming effect is particularly clear where two additives El and E2 according to the invention are added in a ratio by weight of 1:1. The results are set out in Table 1.

Table 1: Additive Foam collapse time in seconds* El 21 E2 23 1:1 Mixture** of El and E2 12 No additive 49 Average value of three series of measurements each comprising 10 individual measurements Parts by weight Corrosion test The corrosion-inhibiting properties were tested by the corrosion test according to ASTM D 665- 92. To this end, test specimens of steel were immersed in 330mL of a diesel oillwater mixture parts by volume oil to 1 part by volume water) for 24 hours at a temperature of 60°C. The test specimens were then cleaned with water and visually inspected for corrosion in relation to a reference test specimen. The test specimens were evaluated under the NACE scheme. To this end, the surface of the test specimen showing rust is measured and evaluated in accordance with the following scheme: Evaluation Surface with visible rust (in A 0 <0.1 B+ B 5 to C 15 to D 51 to E 76 to 100 The results are set out in Table 2. Diesel oil/water mixtures containing the defoamers according to the invention in concentrations of 10 ppm (active substance) were used. The tests were carried out at three different pH values.

C08275 Table 2: Additive pH4 pH7 pH9 El B+ B D E2 B C C 1:1 Mixture* of El and E2 B+ B B Parts by weight It can be seen that the defoamers according to the invention also produce good corrosion inhibiting results. The favourable results of the mixtures of defoamers El and E2 merit particular emphasis.

C08275

Claims

1. A process for defoaming fuels, wherein an effective quantity of at least one compound corresponding to formula 1 O R O1 R 4 AO NA R P R (I) in which R 1 R 2 and R 3 independently of one another represent an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms, an aryl or alkylaryl group or a group corresponding to formula (II): S0 where A- is an anion, n is the number 2 or 3, p is a number of 1 to 3 and R 4 is an alkyl or alkenyl group containing 7 to 21 carbon atoms and 0, 1, 2 or 3 double bonds, is added to the fuel.

2. A process as claimed in claim 1, wherein the fuel is a diesel fuel.

3. A process as claimed in claim 1 or claim 2, wherein the compounds corresponding to formula are added to the fuel in quantities of 5 to 1000ppm.

4. A process as claimed in claim 3, wherein the compounds corresponding to formula (I) are added to the fuel in quantities of 10 to 15

5. A process as claimed in any one of claims 1 to 4, wherein compounds corresponding to formula in which R 1 and R 2 represent a group corresponding to formula (II) and R 3 is an alkyl group containing 1 to 4 carbon atoms or a benzyl group, are added to the fuel.

6. A process as claimed in any one of claims 1 to 5, wherein compounds corresponding to formula in which R 1 and R 2 represent a methyl group and R 3 is an alkyl group containing 1 to 4 carbon atoms or a benzyl group, are added to the fuel.

7. A process as claimed in any one of claims 1 to 6, wherein mixtures of compounds of formula according to claim 4 or claim 6 in a ratio by weight of 1:2 to 2: are added to the fuel.

8. A process as claimed in claim 7, wherein mixtures of compounds of formula according to claim 4 or claim 6 in a ratio by weight of 1:1 are added to the fuel.

9. A process as claimed in any one of claims 1 to 8, wherein compounds corresponding to formula in which n has the value 2 and p has the value 1, are added to the fuel.

A process for defoaming fuels, said process being substantially as hereinbefore described with reference to any one of the examples.

11. The use of compounds corresponding to formula as defoamers for fuels.

12. A diesel fuel containing compounds corresponding to formula R1 ,O t\ R (1) C08275 in which R 1 R 2 and R 3 independently of one another represent an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms, an aryl or alkylaryl group or a group corresponding to formula (II): 0 0R 4 where A- is an anion, n is the number 2 or 3, p is a number of 1 to 3 and R 4 is an alkyl or alkenyl group containing 7 to 21 carbon atoms and 0, 1, 2 or 3 double bonds in quantities of 5 to 1000ppm.

13. A diesel fuel as claimed in claim 12, wherein the quantities are 10 to

14. A diesel fuel as claimed claim 12 or claim 13, wherein in compounds corresponding to formula R 1 and R 2 represent a group corresponding to formula (II) and R 3 is an alkyl group containing 1 to 4 carbon atoms or a benzyl group.

15. A diesel fuel as claimed in any one of claims 12 to 14, wherein in compounds corresponding to formula R 1 and R 2 represent a methyl group and R 3 is an alkyl group containing 1 to 4 carbon atoms or a benzyl group.

16. A diesel fuel as claimed in any one of claims 12 to 14, containing mixtures of compounds of formula according to claim 14 or claim 15 in a ratio by weight of 1:2 to 2. is

17. A diesel fuel as claimed in claim 16, containing mixtures of compounds of formula (I) according to claim 14 or claim 15 in a ratio by weight of 1:1.

18. A diesel fuel as claimed in any one of claims 12 to 17, wherein in compounds corresponding to formula n has the value 2 and p has the value 1, are added to the fuel.

19. A diesel fuel as claimed in any one of claims 12 to 18, free from additional corrosion inhibitors. A diesel fuel, substantially as hereinbefore described with reference to any one of the examples. Dated 15 May 2001 S COGNIS DEUTSCHLAND GMBH Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON C08275