MX2008008406A - Use of mixtures of monocarboxylic acids and polycyclic hydrocarbon compounds for improving the storage stability of fuel additive concentrates - Google Patents

Abstract

The invention relates to the use of mixtures of:A) aliphatic saturated or unsaturated monocarboxylic acids with 12 to 24 carbon atoms or the dimerised or trimerised products, ammonium salts, amides, esters or nitriles thereof and B) polycyclic hydrocarbon compounds made from distillation residues of natural oils extracted from tree resins, for improving the storage stability of fuel additive concentrates comprising at least one detergent and at least one cetane number improver, wherein said mixtures are applied with a concentration of 0.7 to 20 wt.%, relative to the total amount of fuel additive concentrate.

Description

USE OF MIXTURES OF MONOCARBOXYLIC ACIDS AND COMPOUNDS OF POLYCYCLIC HYDROCARBONS TO IMPROVE STABILITY TO THE STORAGE OF CONCENTRATES OF ADDITIVES FOR COMBUSTIBLES Description The present invention relates to the use of aliphatic saturated or unsaturated long chain monocarboxylic acids or their derivatives and polycyclic hydrocarbon compounds in a special range of concentrations to improve the storage stability of concentrates of fuel additives, which contain less one detergent and at least one higher cetane number. The invention also relates to a concentrate of fuel additives, which contains detergents based on succinic acid anhydride, a cetane number improver and the mixtures mentioned above in special proportions. Concentrates of fuel additives remain, after preparation, before being mixed with fuels in refineries, commonly a prolonged time in transport and storage containers. This time of permanence can be from a few weeks to months. With this, concentrates of fuel additives frequently tend to cloud, disintegrate the components and in part even to precipitations. From US-A 5 591 237 (1) it is known that storage stability of additive concentrates for fuels containing detergents based on succinic acid anhydride, especially polyisobutynyl succinimide and cetane index improvers, it can be improved by the addition of nitric acid, hydrochloric acid or aliphatic monocarboxylic acids in an amount of 1,500 to 10,000 ppm. Examples of (1) include, among others, oleic acid in a concentration of 6,000 ppm and hydrochloric acid in a concentration of 10,000 ppm in the concentrate as effective buffers for storage stability. EP-A 890 631 (2) describes an additive composition containing an ash-free detergent based on an acylated nitrogen compound, for example a polyisobutenylsuccinimide and a long-chain carboxylic acid or an ester thereof and which causes an improved lubrication capacity of fuel oils as well as a better solubility in fuel oils. WO 98/04656 (3) describes the use of a lubricant additive of aliphatic saturated or unsaturated long chain monocarboxylic acids or their derivatives and polycyclic hydrocarbon compounds which are obtained especially from tall oil. , to improve the lubricating properties of diesel fuels with low sulfur content. The object of the present invention was to further improve the storage stability of additive concentrates for fuels containing detergents and cetane index improvers. Accordingly, the use was found of mixtures of: (A) saturated or unsaturated aliphatic monocarboxylic acids with 12 to 24 aliphatic carbon atoms or their dimerization or trimerization products which may be present as free carboxylic acids and / or in the form of salts of ammonium, amides, esters and / or nitriles, and (B) polycyclic hydrocarbon compounds that can be obtained from distillation residues of natural oils that were extracted from tree resins, to improve the storage stability of concentrates of fuel additives, which contain at least one detergent and at least one higher cetane number, wherein the mixtures of the components (A) and (B) are used in a concentration of 0.7 to 20% by weight with respect to the total amount of the fuel additive concentrate. Component (A) in the aforementioned mixtures preferably comprises saturated or unsaturated aliphatic monocarboxylic acids with 14 to 20 carbon atoms, especially 16 to 18 carbon atoms. These carboxylic acids are, in general, linear. For the component (A), especially natural fatty acids, especially those with 14 to 20 carbon atoms, especially 16 to 18 carbon atoms, are particularly suitable. Typical representatives of such carboxylic acids and / or fatty acids are lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and elaidic acid. The component (A) can only be composed of a monocarboxylic acid and / or fatty acid of this type or preferably by a mixture of two or more such monocarboxylic acids and / or fatty acids. In the case of natural fatty acids, such as those obtained from rapeseed oil, soybean oil or pine oil, these are generally mixtures of monocarboxylic acids of this type. The component (B) whose natural origin is represented by tree resins, especially pine or spruce conifer resins, is formed of one or preferably more of the so-called resin acids. Resin acids are polycyclic hydrocarbon compounds that contain carboxyl groups. To these belong as the most important representatives, abietic acid, dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid and levopimaric acid. These resin acids may also be present in part in oxidized form such as the so-called oxyacids. In a preferred embodiment, the components (A) and (B) are used in the aforementioned mixtures in a weight ratio of 65 to 99.9 to 0.1 to 35, especially 90 to 99.9 to 0.1. to 10, especially from 97 to 99.9 to 0.1 to 3. Especially suitable as mixtures of components (A) and (B) are the pine oil fatty acid and the dimerized pine oil fatty acid. The pine oil fatty acid is prepared from pine oil obtained by breaking down resin-rich woods, especially pine or spruce wood. The fatty acid of pine oil is a mixture of fatty acids where unsaturated Clß monocarboxylic acids, especially oleic acid, linoleic acid and conjugated C18 fatty acids, as well as 5, 9, 12 -octadecatriene acid, resin acids and possibly oxyacids prevail (ie, oxidized fatty acids and resins). Resin acids form the so-called pine oil resin, where abietic acid, dehydroabietic acid and palustric acid predominate, and small parts of dihydroabietic acid, neoabieic acid, pimaric acid and isopimaric acid can be found in addition to other acids resin. For the best quality of pine oil fatty acid, the fatty acid part is at least 97% by weight and the resin part of the pine oil is up to 3% by weight. Obtaining the fatty acid of pine oil and resin acids from tree resins by disintegration, extraction and distillation processes are known to the person skilled in the art and need not be explained in greater detail here. In the fatty acid of dimerized pine oil the fatty acid component (A) is in diked form. The dimerizations and trimerizations of monocarboxylic acids or fatty acids may be carried out according to common procedures and are known to the person skilled in the art. The monocarboxylic acids or fatty acids and their dimerization or trimerization products of the component (A) can exist as free carboxylic acids and / or ammonium salts, for example, as NH 4 salts or substituted salts, such as mono-, di- -, tri- or tetramethylammonium, and / or in the form of amides, esters or nitriles. Typical amide structures have the groups -CO-NH2, -CO-NH-alkyl or -CO- N (alkyl) 2, wherein "alkyl" represents in the present especially Ci-C4-alkyl moieties, such as methyl or ethyl. The structures of the esters typically contain residues of esters of alkanol-Ci to C4, as remains of methyl or ethyl esters. The concentrates of additives for fuels mentioned can be used mainly for the additivation of any fuels, fuels or fuel oils. In particular, however, they are suitable for the additivation of diesel fuels (medium distillate fuels). In diesel fuels (middle distillate fuels) it is commonly referred to as petroleum refining which generally have a boiling range of 100 ° C to 400 ° C. These are mostly distillates with a point of 95% up to 360 ° C or above. But these can also be the so-called diesel with very low sulfur content ("Ultra low sulfur diesel") or city diesel ("City diesel"), characterized by a point of 95%, for example, at most 345 ° C and a sulfur content of at most 0.005% by weight or by a point of 95%, for example, 285 ° C and a sulfur content of at most 0.001%. Along with diesel fuels obtained by refining, whose main components represent long-chain paraffins, those that can be obtained by coal gasification or coal liquefaction [gas to liquid fuels (GTL) "gas to liquid"] are suitable. Mixtures of the aforementioned diesel fuels with regenerative fuels such as biodiesel or bioethanol are also suitable. Of special interest are diesel fuels with low sulfur content, that is, with a sulfur content of less than 0.05% by weight, preferably less than 0.02% by weight, especially less than 0.005% by weight and very especially less than 0.001% by weight. Diesel fuels can also contain water, for e. , in an amount of up to 20% by weight, for example, in the form of diesel-water microemulsions or as the so-called "white diesel". As detergents (detergent additives) they are commonly referred to as precipitation inhibitors for fuels, especially diesel fuels here. The detergents are preferably amphiphilic substances, which have at least one hydrophobic hydrocarbon radical with a number average molecular weight (Mn) of 85 to 20,000, especially 300 to 5,000, especially 500 to 2,500, and at least one group polar. In a preferred embodiment, the mixture of components (A) and (B) is used to improve the storage stability of fuel additive concentrates, which contain in addition to at least one cetane number enhancer, at least one detergent with groups derived from the anhydride of succinic acid with hydroxy and / or amino and / or amido and / or yunde groups. This detergent with groups derived from the anhydride of succinic acid with hydroxy and / or ammo and / or amido and / or amido groups is preferably an amide of the succinic acid substituted with polusobutenyl. The additives containing groups derived from the anhydride of succinic acid with hydroxy and / or arymo and / or amido and / or attached groups are preferably corresponding derivatives of sucralnic acid polyusobutenyl-anhydride, which can be obtained by conversion of conventional or highly reactive polusobutene with Mn = 300 to 5,000, especially with Mn = 500 to 2500, with maleic acid anhydride by the thermal method or through chlorinated polybutene. Of special interest here are the derivatives with aliphatic polyamines, such as ethylene diamine, diethylene triamma, triethylene tetraamine or tetraethylene pentamine. The groups comprising hydroxy and / or amino and / or amido and / or lido groups are, for example, carboxylic acid groups, acid amides, di- or polyamine acid amides, which in addition to the amide function also have free amine groups, succinic acid derivatives with an acid function and an amide function, carboxylic acid ions with monoamines, attached to the carboxylic acid with di- or polyamines, which in addition to the amide function also have free amine groups, and dumid, which are formed by the transformation of di- or polyamines with two succinic acid derivatives. Such fuel additives are described in particular in US-A-4 849 572. As the cetane index improver (ignition and combustion improver), organic nitrates are commonly used. Such organic nitrates are especially nitrate esters of aliphatic or substituted or unsubstituted cycloaliphatic alcohols, mostly with up to approx. 10, especially with 2 to 10 carbon atoms. The alkyl groups in these nitrate esters can be linear or branched, saturated or more saturated. Typical examples of such nitrate esters are methyl nitrate, ethyl nitrate, n-propyl nitrate, isopropyl nitrate, ammonium nitrate, n-butyl nitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate , n-amyl nitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate, tert-amyl nitrate, n-hexyl nitrate, n-heptyl nitrate, n-octyl nitrate , 2-ethylhexyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, cyclopentyl nitrate, cyclohexyl nitrate, methylcyclohexyl-nitrate and isopropyl-cyclohexyl-nitrate. Further suitable are, for example, the aliphatic aliphatic alcohols substituted with alkoxy esters, such as 2-ethoxyether nitrate, 2- (2-ethoxy? -ethoxy) ethyl nitrate, 1-methoxypropyl nitrate or nitrate nitrate. 4-ethoxybutyl. In addition, diol nitrates, such as 1, 6-hexamethylene dinitrate, are also suitable. Preferred cetane number improving classes are preferred primary amyl nitrates, primary hexyl nitrates, octyl nitrates, as well as mixtures thereof. In a preferred embodiment, the mixture of components (A) and (B) is used to improve the storage stability of concentrates of fuel additives, which in addition to at least one detergent contain 2-ethylhexyl nitrate as Cetane index improver. For this purpose 2-ethylhexyl nitrate can be present as the sole cetane index improver or mixed with other cetane index improvers. The aforementioned fuel additive concentrates, which are especially suitable for the additivation of diesel fuels (medium distillation fuels), may contain, in addition to the detergency component and the cetane index improver component, other components of common additives, for example, inhibitors. corrosion, demulsifiers, antifoaming agents, antioxidants and stabilizers, antistatic agents, lubricant capacity enhancers, paints (markers) and / or thinners and solvents. The mixture of the carboxylic acids (A) and the polycyclic hydrocarbon compounds (B) is used according to the present invention in amounts of 0.7 to 20% by weight, especially of 1.1 to 15% by weight, more especially from 1.5 to 10% by weight, more preferably from 3 to 8% by weight, in each case referred to the total amount of the fuel additive concentrate. The use concentration of the mixture of (A) and (B) represents a critical parameter, since it was demonstrated that the recommended dose in (1) of 6000 ppm (corresponding to 0.6% by weight) for monocarboxylic acids (illustrative for oleic acid) does not yet produce sufficient storage stability for concentrates of fuel additives. The greater amount of the mixture of (A) and (B) in the present invention with respect to the teaching of (1) furthermore shows positive effects in the use of concentrates of fuel additives, especially the lubrication effect is simultaneously improved of diesel fuel poor in additive sulfur. Since a portion of the above-mentioned fuel additive concentrates represents new mixtures of substances, an object of the present invention is also a fuel additive concentrate., which contains, in each case referred to the total amount of the concentrate of the fuel additive: (a) 0.5 to 60% by weight, especially 10 to 45% by weight, most especially 20 to 35% by weight, of one or more detergents with groups derived from the anhydride of succinic acid with hydroxy and / or amino and / or amido and / or lido groups, (b) 0.5 to 80% by weight, especially 30 to 75% by weight, very especially 45 to 70% by weight, of one or more builders of the cetane number, preferably 2-ethylhexyl nitrate, alone or mixed with other builders of the cetane number, and (c) 0.7 to 20% by weight, especially 1 , 1 to 15% by weight, very especially 1.5 to 10% by weight of a mixture of carboxylic acids (A) and polycyclic hydrocarbon compounds (B), as specified above.

The following examples will explain the present invention in greater detail without limiting it. Examples 1A (comparative) and IB (according to the invention) The two additive concentrates for fuels 1A and IB, suitable for use in diesel fuel have the compositions indicated in Table 1 [in% by weight]: Table 1 1A IB Detergent * 20.31 27.66 2-ethylhexyl nitrate as a builder of the cetane number 46.87 63.83 Fatty acid of pine oil (part of fatty acid: 97% by weight) 0 6,38 2-ethylhexanol as diluent 31,25 0 Antifoam that can be obtained commercially 1.25 1.70 Commercially available corrosion inhibitor 0.32 0.43 * Imitation of the succinic acid anhydride substituted with polyisobutenyl (Mn of the polyisobutenyl radical: 1000) and tetraethylenepentamine. Result of storage tests: Concentrate 1A evidently became turbid after 2 weeks of storage at 40 ° C, while concentrate IB remained clear after 50 weeks of storage.

Claims (2)

1. Claims 1. Use of mixtures of: (A) saturated or unsaturated aliphatic monocarboxylic acids with 12 to 24 carbon atoms or their dimerization or trimerization products which may be present as free carboxylic acids and / or in the form of ammonium salts, amides , esters and / or nitriles, and (B) polycyclic hydrocarbon compounds containing carboxyl groups, which can be obtained from distillation residues of natural oils that were extracted from tree resins, to improve storage stability of fuel additive concentrates , which contain at least one detergent and at least one cetane index improver, wherein the mixtures of the components (A) and (B) are used in a concentration of 0.7 to 20% by weight with respect to to the total amount of the fuel additive concentrate.
2. 2. Use according to claim 1, characterized in that the fuel additive concentrates contain at least one detergent with groups derived from the anhydride of the anhydride succinic acid with hydroxy and / or amino and / or amido and / or imido groups. Use according to claim 2, characterized in that the concentrates of fuel additives contain as detergent an imide of the succinic acid substituted with polyisobutenyl. Use according to claims 1 to 3, characterized in that the additive concentrates for fuels contain 2-ethylhexyl nitrate as an enhancer of the cetane number. Use according to claims 1 to 4, characterized in that the carboxylic acids (A) and the polycyclic hydrocarbon compounds containing carboxyl groups (B) are present in the mixture in a weight ratio of 65 to 99.9 to 0, 1 to 35, especially from 90 to 99.9 to 0.1 to 10. Use according to claims 1 to 5, characterized in that as a mixture of carboxylic acids (A) and polycyclic hydrocarbon compounds containing carboxyl groups (B), pine oil fatty acids or dimerized pine oil fatty acids are used. Use according to claims 1 to 6, characterized in that the mixture of carboxylic acids (A) and polycyclic hydrocarbon compounds containing carboxyl groups (B) is used in amounts of 0.7 to 20% by weight, especially of 1, 5 to 10% by weight with reference to the total amount of the fuel additive concentrate. Additive concentrate for fuel containing, in each case, the total amount of the concentrate of the fuel additive, (a) 0.5 to 60% by weight of one or more detergents with groups derived from the anhydride of succinic acid with hydroxy groups and / or amino and / or amido and / or imido, (b) 0.5 to 80% by weight of one or more builders of the cetane number and (c) 0.7 to 20% by weight of a mixture of carboxylic acids (A) and polycyclic hydrocarbon compounds containing carboxyl groups (B) according to claim 1, 5 or 6.