EP1036141A1

EP1036141A1 - Method for defoaming fuels

Info

Publication number: EP1036141A1
Application number: EP98964442A
Authority: EP
Inventors: Thorsten LÖHL; Günter Uphues; Bernd Boutty; Peter Neumann; Frank Bongardt
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: 2000-09-20
Also published as: AU735528B2; JP2001526300A; DE19753792A1; AU1964299A; WO1999029811A1; CA2312064A1

Abstract

According to the inventive method for defoaming fuels, an effective quantity of at least one compound of formula (I) is added to the fuel. The radicals R?1, R2 and R3¿ in said formula represent an alkyl or hydroxyalkyl radical with 1 to 4 C-atoms, an aryl or alkylaryl radical, or a radical of formula (II) independently of each other, A- being an anion, n being a number 2 or 3, p being a number from 1 to 3 and R4 representing an alkyl or alkenyl radical with 7 to 21 C-atoms and 0, 1, 2 or three double bonds.

Description

"Process for defoaming fuels

The present application relates to a method for defoaming fuels, in particular diesel fuels, the use of certain quaternary ammonium compounds as defoamers for fuels and a diesel fuel which contains these quaternary ammonium compounds.

Fuels, in particular the hydrocarbon mixtures used as diesel fuels, have the unpleasant property of developing foam in connection with air when they are filled into storage tanks, such as storage tanks and fuel tanks of motor vehicles. This leads to a delay in the discharge process and inadequate filling of the container. It is therefore common to add defoamers to the fuels. These defoamers should be effective in the lowest possible concentration and must not hinder the combustion process of the fuel, e.g. through the formation of residues that negatively affect the engine's operation.

A large number of defoamers for fuels are known from the literature. As a rule, these are silicone-containing compounds, e.g. described in EP 773 278 AI. Such additives can, however, lead to an undesired covering of the catalytic converter or filter surfaces of the engines with silicon dioxide, which is produced during the combustion of the fuel.

Furthermore, modern fuels are provided with a variety of different additives, such as corrosion inhibitors, friction modifiers, which are used to reduce wear or additives to clean the engine. To interactions of the to avoid individual additives, however, extensive and expensive tests must be carried out. Therefore, additives with a broad spectrum of activity are increasingly being sought.

The object of the present application was therefore to find silicone-free additives for defoaming fuels. Surprisingly, it was found that certain quaternary ammonium salts have excellent properties as defoamers for fuels.

The invention therefore relates to a process for defoaming fuels, an effective amount of at least one compound of the formula (I) being added to the fuel

R ¹ O ι + II

R ² - N - (C _n H _2n -O) _p -CR ⁴ A ^" (I)

I.

R ³

in the formula (I) the radicals R ¹ , R ² and R ³ independently of one another are an alkyl or hydroxyalkyl radical having 1 to 4 carbon atoms, an aryl or alkylaryl radical or a radical of the formula (II),

O

II

(C _n H _2n - O) _p - C - R ⁴ (II)

A ^"is an anion, n is a number of 2 or 3, p is a number of 1 to 3 and R ^{4 is} an alkyl or alkenyl radical with 7 to 21 C atoms and 0, 1, 2 or 3 double bonds.

The compounds of the formula (I) are known and are mainly used as textile-softening components or for the antistatic finishing of fabrics. Examples of compounds of the formula (I) can be found in documents WO 94/06899 and DE 42 03 489 AI of the applicant. which reveal quaternary diesteramine compounds in soft care agents for textiles. EP 239 910 A2 also describes textile care agents which contain readily biodegradable quaternary mono- and diesteramine compounds.

From DE 19649285.8 of the applicant it is already known that the compounds of the formula (I) also have corrosion-inhibiting effects. The document discloses a method for protecting metal surfaces against corrosion in liquid media, in particular crude oil. However, the document contains no evidence of the defoaming effect of these compounds. Nor can it be inferred from the document that the compounds are suitable as an additive for fuels, in particular for diesel fuels.

In the context of this application, fuels are understood to mean all energy-supplying supplies whose free combustion energy is converted into mechanical work. This includes all types of engine and aviation fuels that are liquid at room temperature and normal pressure. Motor fuels, e.g. for car or truck engines, usually contain hydrocarbons, e.g. petrol or higher-boiling petroleum fractions. The process according to the invention is particularly suitable for defoaming diesel fuels. Diesel fuels are flame-retardant mixtures of liquid hydrocarbons that are used as fuels for constant pressure or burner motors. The composition is inconsistent and depends on the manufacturing method. Diesel fuels are obtained from gas oil by cracking or from tars obtained from the smoldering of lignite or hard coal. Conventional products have a density between 0.83 and 0.88 g / cm ³ , a boiling point between 170 and 360 ° C and flash points between 70 and 100 ° C.

In the process according to the invention, the compounds of the formula (I) are added to the fuel in effective amounts. Effective concentrations are preferably in the range between 5 and 1000 ppm and in particular between 10 and 50 ppm, based on all the fuel. The compounds of the formula (I) are effective defoamers for fuels and additionally have a corrosion-inhibiting action.

The substances of the formula (I) represent technically quaternized mono-, di- or trifatty acid amine ester compounds which can be obtained by known synthetic methods. As an example, reference is made to EP 293 955 A2 and EP 293 953 A2 for the production. The quaternary compounds can be obtained, for example, by reacting tertiary mono-, di- or trialkanolamines, preferably triethanol or triisopropanolamine or methyldiethanolamine or dimethylethanolamine, with saturated or unsaturated linear or branched C _g . ₂₂ fatty acids or their derivatives, such as esters or chlorides, are formed. The esters formed in the reaction with the alkanolamines are then quaternized, 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 or mixtures thereof. Examples of unsaturated fatty acids are linoleic, linolaidic or linolenic acid. Suitable derivatives are in particular the alkyl esters, preferably the methyl esters of the above-mentioned fatty acids. Naturally occurring fatty acid mixtures of both animal and vegetable origin are also suitable. Coconut or palm kernel fatty acids are particularly preferred.

Compounds of the formula (I) in which p stands for the number 1 and n has the value 2 are preferably used in the process according to the invention. Those compounds whose anions are selected from the group consisting of halide, methosulfate and methophosphate are particularly preferably used in the process according to the invention. The preferred anion is chloride.

It has proven to be particularly advantageous to use mixtures of the abovementioned compounds of the formula (I) in the process according to the invention, since then a particularly good defoamer effect is observed. Mixtures in a weight ratio of 2: 1 to 1: 2 are preferred between compounds of the formula (I) in which the R ¹ and R ^{2 are} a group of the formula (II) and R ^{3 is} an alkyl radical having 1 to 4 carbon atoms or a benzyl radical and compounds of the formula (I). in which the radicals R ¹ and R ^{2 represent} a methyl radical and R ^{3 represent} an alkyl radical having 1 to 4 carbon atoms or a benzyl radical. Mixtures of these compounds in a weight ratio of 1: 1 are preferably used in the process according to the invention.

The present application also relates to the use of compounds of the formula (I) as defoamers for fuels, in particular for diesel fuels. For this purpose, the compounds of the formula (I) can 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 with 1 to 6 carbon atoms, in particular ethanol, propanol and isopropanol, or aliphatic or aromatic hydrocarbons, such as hexane, heptane or toluene. The solutions or dispersions preferably contain the compounds of the formula (I) in amounts between 10 and 80% by weight.

A diesel fuel is also claimed which contains compounds of the formula (I) in amounts of between 5 and 1000 ppm. It is preferably low-sulfur diesel fuel with a sulfur content of at most 0.2% by weight, and the sulfur content is preferably at most 0.005% by weight. The diesel fuel can also contain other common additives, for example friction modifiers, flow improvers, anti-wax-setting additives or other, conventional corrosion inhibitors. However, the diesel fuel is preferably free of additional corrosion inhibitors.

Examples

Manufacture of additives:

Additive 1 (El):

279.7 g (1.75 mol) of caprylic acid methyl ester and 74.5 g (0.5 mol) of triethanolamine together with 0.5% by weight (based on the total amount) of titanium tetrabutylate as catalyst were placed in a 500 ml stirring apparatus. The mixture was then stirred at 185 ° C. for 10 hours until at least 90% of the theoretically formed methanol (48 g) had distilled off. With the help of a thin-film evaporator, excess or unreacted methyl caprylic acid was distilled off at 160 ° C. and a pressure of 3 × 10 ^"2 mbar. Yield: 228.0 g of a thin, yellow-colored residue with 2.67% titratable nitrogen and a hydroxide number ( OHZ) from 13.

105.1 g (0.2 mol, based on titratable nitrogen) of the residue obtained were placed in a 250 ml stirrer and 24.2 g (0.19 mol) of dimethyl sulfate were added dropwise at 85.degree. The mixture was stirred for a further 5 hours at 90 ° C and then concentrated. The solid residue was then recrystallized from ethyl acetate and 62.8 g of product with 0.02% residual titratable nitrogen were obtained.

Additive 2 (E2):

444.4 g (2.0 mol) of coconut fatty acid methyl ester and 198.0 g (2.2 mol) of dimethylethanolamine together with 0.2% (based on the total amount) of titanium tetrabutylate as catalyst were placed in a 1000 ml stirring apparatus. The mixture was heated to reflux with stirring. The product was then distilled at a pressure of 10 mbar. The main fraction was a low viscosity liquid with 4.43% titratable nitrogen.

For quaternization, 173.6 g (0.55 mol, based on titratable nitrogen) dissolved in 60 g of isopropanol were initially charged. After heating to 80 ° C, 66.4 g (0.52 mol) Benzyl chloride added dropwise. The mixture was then stirred at 85 ° C for 5 hours. The medium-viscosity end product contained 80% isopropanol and had a residual content of 0.13% titratable nitrogen.

Defoamer test:

50 ml of diesel were filled into a 100 ml standing cylinder and shaken ten times. The time it took for the foam formed to collapse was then measured. The measurement was finished when the foam carpet tore open 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 were added in a concentration of 30 ppm (active substance) in the form of a solution in toluene. The improved defoaming effect can be seen particularly clearly when two additives E1 and E2 according to the invention are added in a weight ratio of 1: 1. The results are shown in Table 1:

Table 1 :

* Average of three series of measurements with 10 individual measurements each ** parts by weight

Corrosion test

To test the corrosion-inhibiting properties, a corrosion test was carried out in accordance with ASTM D 665-92. For this purpose, steel test specimens were immersed in 330 ml of a diesel oil / water mixture (10 parts by volume of oil to 1 part by volume of water) over a period of 24 hours at a temperature of 60 ° C. The test specimen was then cleaned with water and optically examined for corrosion with reference to a reference test specimen. The test specimens were evaluated according to the NACE scheme. To the surface of the test specimen, which shows rust, is measured and evaluated according to the following scheme:

The results are shown in Table 2. Diesel oil / water mixtures were used which contained the defoamers according to the invention in concentrations of 10 ppm (active substance). The tests were carried out at three different pH values.

Table 2: pH

Parts by weight

It can be seen that the defoamers according to the invention also show good results in corrosion inhibition. Of particular note are the good results of the mixtures of defoamers El and E2.

Claims

claims

1. A process for defoaming fuels, characterized in that an effective amount of at least one compound of formula (I) is added to the fuel

R ¹ O l + II

R ² - N - (C _n H _2n -O) _p -CR ⁴ A ^" (I)

I.

R ³

O

II

(C _n H _2n - O) - C - R ⁴ (II)

2. The method according to claim 1, characterized in that the fuel is a diesel fuel.

3. The method according to claim 1 or 2, characterized in that the fuel, the compounds of formula (I) in amounts between 5 and 1000 ppm, preferably in amounts between 10 and 50 ppm are added.

4. The method according to claim 1 to 3, characterized in that the fuel compounds of formula (I) are added in which R 'and R ² for a radical of formula (II) and R ³ for an alkyl radical with 1 to 4 C. -Atoms or a benzyl radical.

5. The method according to any one of claims 1 to 4, characterized in that the fuel compounds of formula (I) are added in which R ¹ and R ² for a methyl radical and R ³ for an alkyl radical having 1 to 4 carbon atoms or one Benzyl radical stand.

6. The method according to any one of claims 1 to 5, characterized in that mixtures of compounds of formula (I) according to claim 4 and 5 in a weight ratio of 1: 2 to 2: 1 and preferably 1: 1 are added to the fuel.

7. The method according to any one of claims 1 to 6, characterized in that the fuel compounds of formula (I) are added in which n is 2 and p is 1.

8. Use of compounds of formula (I) as defoamers for fuels.

9. Diesel fuel containing compounds of formula (I) according to claim 1 in amounts between 5 and 1000 ppm.

10. Diesel fuel according to claim 9, characterized in that it is free of additional corrosion inhibitors.