WO2006053664A1

WO2006053664A1 - Additive for improving the lubricating properties of diesel oils

Info

Publication number: WO2006053664A1
Application number: PCT/EP2005/011998
Authority: WO
Inventors: Markus Dierker; Herbert Fischer; Frank Bongardt; Harald Wallis
Original assignee: Cognis Ip Management Gmbh
Priority date: 2004-11-18
Filing date: 2005-11-09
Publication date: 2006-05-26
Also published as: DE102004055589A1

Abstract

The invention relates to the use of esters of di-, oligo- and/or polyglycerine with unsaturated fatty acids as a lubricity improver in fuels, particularly in low-sulphur diesel fuels.

Description

Additive for lubricity improvement of diesel oils

The present invention relates to the use of certain esters as lubricity improvers in hydrocarbon-based fuels, especially diesel fuels.

Hydrocarbon-based fuels, in particular gasoline and diesel, usually contain a large number of additives in order to improve their usability. In recent years, there has been an increasing tendency to reduce the content of sulfur in fuels for the sake of environmental protection. On top of this, the SOχ emission of fuel combustion can be significantly reduced.

However, the substantial absence of sulfur compounds and free sulfur in the fuel, as it is possible today, also causes the lubricating properties of this

Worsen fuels. There is therefore a need for additives which are suitable

Lubricating properties of fuels and in particular of diesel fuels to increase, with the use of these additives, of course, no environmentally harmful emissions are triggered. Furthermore, the additives have to fulfill all the technical properties otherwise required of additives in this area, in particular the combustion of the

Do not hinder fuel and have no harmful interactions with other ingredients of the fuels.

No. 6,280,488 discloses additive mixtures which contain an ashless dispersant in combination with carboxylic esters, this additive increasing the lubricity of the oil. In one example, a glycerol monooleate is tested as an additive to agents which, in addition to the glycerol monooleate, still contain the dispersants within the meaning of the technical teaching of US Pat. No. 6,280,488. It can be seen from Table 4 in column 12 of US Pat. No. 6,280,488 that the use of glycerol monooleate alone is not suitable for sufficiently improving the lubricity of diesel oil.

The present invention was therefore based on the object, an effective additive for improving the lubricity of fuels, especially low sulfur

Provide fuels and in particular low-sulfur diesel fuels. l It was found that the use of certain polyol esters has the desired properties and thus the object of the present invention could be achieved.

A first subject of the present invention therefore relates to the use of esters prepared by reacting carboxylic acids of the general formula R-COOH in which R is a simple or polyunsaturated, branched or unbranched alkyl radical having 11 to 21 carbon atoms, or Mixtures of these carboxylic acids, with diglycerol, oligoglycerols and / or polyglycerols, as smokability improvers in hydrocarbon-based fuels.

Esters of carboxylic acids of the formula R-COOH with polyols are compounds known per se. US Pat. No. 3,637,774 describes esters of polyglycerols and their preparation. Within the scope of the technical teaching claimed here, those esters are used to improve lubricity, the alcohol component of which is either a diglycerol or an oligoglycerol, that is to say a starting material formed by oligomerizing 2 to 5 moles of glycerol. Also suitable and preferred are polyglycerols, i. Condensation products of more than 5 moles of glycerol with each other. For the sake of simplicity, reference is made to Tables I, Ia and II in columns 3 and 4 of US Pat. No. 3,637,774 for the physical properties of the di-, oligo- and polyglycerides.

The polyols in the sense of the provisional present invention are reacted in a manner known per se in the presence of acidic and alkaline catalysts with the carboxylic acids of general formula R-COOH or derivatives thereof, for example the methyl ester thereof. It is essential for the present invention that the carboxylic acids used for the esterification are completely or predominantly monounsaturated or polyunsaturated. Particularly preferred is the esterification of the polyols with oleic acid. Since the use of pure oleic acid is cost-intensive, it is preferred for the purposes of the present technical teaching to use oleic acid mixtures of technical or natural origin which contain a particularly high proportion of oleic acid. Preferably, such acid mixtures would be used which contain more than 50 mol%, preferably more than 75 mol% and in particular more than 90 mol% of oleic acid. It is particularly preferred to resort to fatty acid mixtures obtained from rapeseed or rapeseed oil. Rapeseed oil or rapeseed oil is obtained from the seeds of rape or turnip rape. Rapeseed contains about 40-50% oil u. about 30% protein. Old oilseed rape varieties contain high levels (35-64%) erucic acid, 5-10% Gondo acid [(Z) -11-eicosenoic acid, C ₂₀ H ₃₈ O _2, MR 310.52, Melting point: 24- 25 ⁰ C ] and nervonic acid in addition to 13-38% oleic acid, 10-22% linoleic acid and 2-10% linolenic acid. New rape varieties usually contain <2% of the long-chain monoeno fatty acids. The breeding of new varieties has resulted in so-called double-erosion or low erucic acid rapeseed (LEAR) varieties, which only contain trace amounts of both erucic acid and toxic glucosinolates, while being rich in oleic acid (50-65%), Linoleic acid (15-30%) and linolenic acid (5-13%) are preferred For the purposes of the present technical teaching, preference is given to using an ester of a di-, oligo- or polyglycerol with a fatty acid mixture, these fatty acid mixtures being based on The preferred alcohol component is diglycerol, the fatty acid mixtures which are rich in oleic acid and which have a low erucic acid content and which have been obtained on the basis of rapeseed or rapeseed oil.

The esters according to the present invention have an acid number according to DIN 53169 of at most 1.0, preferably less than 1.0 and in particular less than 0.6. In addition to the esters of unsaturated acid with di-, oligo- and / or polyglycerols, the additives may also contain less than 50% by weight, based on the total amount of ester used, of carboxylic acid esters with saturated carboxylic acids. However, it is preferred within the meaning of the present technical teaching to select those additives which have particularly high proportions of esters of the designated polyols with unsaturated acids. The glycerol esters of the present invention may be partially or fully esterified, i. it is possible that some or all of the free OH functions of the polyols have been reacted with carboxylic acids.

According to the invention, the esters are added to the fuel in amounts of from 10 to 1000 ppm, preferably from 50 to 200 ppm, and in particular in amounts of from 70 to 120 ppm, based on the amount of fuel. For the purposes of this application, fuels are understood as all energy-yielding fuels based on hydrocarbons whose free combustion energy is converted into mechanical work. These include all types of liquid at room temperature and normal pressure motor and aviation fuels. Motor fuels, e.g. for passenger car or truck engines, usually contain hydrocarbons, e.g. Benzine or higher boiling petroleum fractions or diesel fuel. Particularly preferred is the

Use of the additives according to the invention in diesel fuel. Diesel fuels refer to flame-retardant mixtures of liquid hydrocarbons which are used as fuels for constant pressure or burner engines (diesel engines) and consist predominantly of paraffins with admixtures of olefins, naphthenes and aromatic hydrocarbons. Their composition varies and depends mainly on the method of preparation: common products have a density of 0.83-0.88, a boiling point in the range of 170-360 ⁰ C and a flash point between 70-100 ⁰ C. Diesel is obtained at the distillation of petroleum from gas oil, cracking, tars obtained from the carbonization (or hydrogenation) of brown or hard coal, and the hydrogenation of the coal extract. Diesel for stationary equipment and marine engines have a similar composition as heavy fuel oil, which for cars, buses and trucks correspond to the fuel oil EL. A key factor in the usability of diesel is its ignitability, for which the cetane number (CZ) was introduced in quantitative terms. The ignition capability is the property of a motor fuel, lighter or harder to ignite in an operating on the diesel principle engine. The requirements for diesel are CZ 20-40 for low-speed engines, CZ> 45 for small and high-speed engines. One of the quality features of diesel is its low-temperature behavior, which can be described by the cloudpoint or preferably by the cold filter plugging point (CFPP), the temperature at which sucked-in diesel blocks a filter. Desirable are also a low pour point, low content of non-combustible and sooty substances and a niedri¬ ger sulfur content. In DIN-EN 590 (05/1993), the requirements and test methods for diesel are specified throughout Europe. Cetane number improvers (nitric or nitric acid esters), corrosion inhibitors, flow improvers, surfactants (keeping the injection nozzles clean), defoamers, and sometimes smoke reducers as additives are added to the diesel.

Another object of the present invention relates to a process for improving the lubricity of fuels, in particular diesel oil, wherein the Dieselöl¬ ester or ester mixtures according to the above description in amounts of 10 to 1000 ppm added. The process according to the invention is preferably carried out with fuels whose sulfur content is as low as possible, preferably less than 0.2% by weight of sulfur, based on the total amount of fuel. Examples

Preparation of a diglycerin fatty acid ester:

3 moles of a fatty acid mixture based on sunflower oil having an acid number of 211 (EDE nor SB 00, Fa. Cognis), were mixed with 2 mol of diglycerol in the presence of a catalyst (Zin noxalat) mixed and esterified at temperatures up to 250 ⁰ C. The resulting product was yellow, clear and viscous. The acid number was measured at 0.9.

Subsequently, the product was tested in the HFRR test (according to ISO 12156-1). As a comparison, a diesel oil without additives was tested. The results were as follows:

HFRR value (EN 590) diesel (standard) 615 diesel + 100 ppm diglycerol ester 194 diesel + 200 ppm diglycerol ester 193

Claims

claims

1. Use of esters prepared by reacting carboxylic acids of the general formula R-COOH in which R is a mono- or polyunsaturated, branched or unbranched alkyl radical having 11 to 21 carbon atoms, or mixtures thereof Carboxylic acids, with diglycerol, oligoglycerols and / or polyglycerols, as lubricity improvers in hydrocarbon-based fuels.

2. Use according to claim 1, characterized in that esters of monosaturated carboxylic acids are used according to claim 1, characterized gekennzeich¬ net, that the esters are prepared from carboxylic acids or carboxylic acid mixtures containing more than 50 mol%, preferably to more than 75 mol% and in particular to more than 90 mol% of oleic acid.

3. Use according to one of claims 1 to 2, characterized in that the Es¬ ter from carboxylic acids or carboxylic acid mixtures are prepared which contain less than 5 mol% of erucic acid.

4. Use according to any one of claims 1 to 3, characterized in that the esters contain ter as the alcohol component diglycerol.

5. Use according to any one of claims 1 to 4, characterized in that the esters have an acid number of at most 1.0, preferably less than 1.0 and in particular less than 0.6.

6. Use according to any one of claims 1 to 5, characterized in that esters of saturated carboxylic acids with diglycerol, oligoglycerols or polyglycerols in amounts of less than 50 wt .-%, based on the total amount of ester used, are also used.

7. Use according to claims 1 to 6, characterized in that the esters are used in amounts of 10 to 1000 ppm, preferably 50 to 200 ppm and in particular in amounts of 70 to 120 ppm, based on the fuel.

8. Use according to claims 1 to 7, characterized in that the esters are used in diesel fuels, preferably with diesel fuels containing less than 0.2 wt .-% sulfur.

9. A process for improving the lubricity of diesel oil, characterized gekennzeich¬ net that is added to the diesel ester or ester mixtures according to claims 1 to 6 in amounts of 10 to 1000 ppm.