RU2416628C2 - Oxidatively stable oil containing base oil and additive - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: composition contains oil which contains naphthene base oil on a mineral base, paraffin base oil on a mineral base and/or paraffin base oil obtained via Fischer-Tropsch synthesis, a copper passivator, and from 0.001 to less than 0.1 wt % sulphur-based organic compound as an antiwear additive. The composition can also contain a phenol or amine antioxidant. The composition of the base oil and antiwear additive undergoes purification with bleaching clay with subsequent addition of the copper passivator and an optional antioxidant. The composition is used as electrically insulating oil, particularly transformer oil. ^ EFFECT: high oxidative stability with low content of additive. ^ 21 cl, 6 tbl, 2 dwg, 4 ex

Description

FIELD OF THE INVENTION

The present invention relates to an oxidation stable oil, which is a base oil and additive composition.

State of the art

US Pat. No. 6,790,386 describes a dielectric fluid containing isoparaffin base oil and additives. This isoparaffin base oil is obtained by hydrotreating, hydroisomerizing and hydrogenating paraffin raw materials of vacuum distillation.

US Pat. No. 6,214,776 describes a formulation containing a paraffin base oil and an additive package containing a hindered phenolic antioxidant and a metal deactivator that is used as oil in an output winding switch or in a transformer. According to this publication, base oils having a kinematic viscosity at 40 ° C between 5 and 20 cSt can be used as base oil in formulations such as electrical insulating oils or transformer oils.

US-A-5241003 discloses a combination of a sulfur-containing antiwear additive and a dispersant, a carboxylic acid derivative that is used as a lubricant additive package.

US-A-5773391 describes a composition comprising a polyol ester base oil, a mixture of aliphatic monocarboxylic acids, and an additive package containing an antioxidant and a metal deactivator. In addition, phosphorodithionates as antiwear additives are disclosed in this document.

WO-A-02070629 describes a method for producing isoparaffin base oil from wax, which is formed in the Fischer-Tropsch synthesis. In accordance with this publication, base oils having a kinematic viscosity at 100 ° C. between 2 and 9 cSt can be used as base oil in compositions such as electrical insulating oils or transformer oils.

US Pat. No. 5,912,212 describes an oxidation stable lubricating oil composition comprising a paraffin mineral base hydrocracking oil and from 0.1 to 5% by weight of a sulfur or phosphorus-containing compound. The examples describe a formulation containing a base oil and an ester of 3-methyl-5-tert-butyl-4-hydroxypropionic acid, dioctylaminomethyltolyltriazole and dilaurylthiodipropionate. The oil has high oxidative stability.

There is a need for oil products with high oxidation stability for use, for example, in electrical insulating oils, in particular as transformer oil or switch gear oil, preferably without a high degree of additives, due to adverse effects on characteristics other than oxidative stability .

SUMMARY OF THE INVENTION

This goal is achieved by the following oil recipe. An oxidation stable oil formulation containing a base oil composition that includes a naphthenic base oil of mineral origin, a paraffin base oil of mineral origin and / or a Fischer-Tropsch base oil, a copper passivator and from 0.001 to less than 0, 1 wt.% Organic compound containing sulfur or phosphorus.

The inventors have found that it turns out the oil formulation having a very high oxidative stability, and does not require a high degree of additives.

Brief Description of the Drawings

1 and 2 show the distribution of carbon atoms for two base oils obtained in the Fischer-Tropsch synthesis, which are used in the examples.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have found that by combining a mineral-based base oil, the so-called paraffin type or naphthenic type, and / or a Fischer-Tropsch derived base oil with at least one copper passivator and anti-wear additive, oil products are obtained having characteristics that are very suitable for use as an insulating oil. It turned out to be very unexpected that the combination of a copper passivator and a small amount of antiwear additives can lead to such an improvement in oxidative stability. In the context of the present invention, a mineral-based base oil means that the base oil is derived from a mineral oil source, while the term “Fischer-Tropsch derived base oil” means an oil made from Fischer-Tropsch synthesis products.

Sulfur or phosphorus-based organic compounds are preferably sulfur and phosphorus compounds such as sulfides, phosphides, dithiophosphates and dithiocarbamates. More preferably, sulfur and phosphorus compounds are used, the use of which is known as antiwear additives in lubricating oil compositions. Even more preferably, organic polysulfide compounds are used. In this description, the term "polysulfide" means that the organic compound includes at least one group in which two sulfur atoms are directly bonded. A preferred polysulfide compound is a disulfide compound. Preferred polysulfide compounds are represented by formula (I)

wherein:

a is 2, 3, 4 or 5, preferably 2;

the radicals R1 and R2 can be the same or different, and each can be an unbranched or branched alkyl group containing 1-22 carbon atoms, aryl groups of 6-20 carbon atoms, alkylaryl groups of 7-20 carbon atoms or arylalkyl groups of 7 -20 carbon atoms. Arylalkyl groups are preferred, optionally substituted benzyl groups are more preferred. More preferably, R1 and R2 are independently selected from a benzyl group or a straight or branched dodecyl group. Examples of possible sulfur and phosphorus-containing compounds and the preferred compounds mentioned herein are described in US Pat. No. 5,912,212 mentioned above as component (b), this publication being incorporated by reference. Examples of suitable disulfide compounds are dibenzyl disulfide, di-tert-dodecyl disulfide and didodecyl disulfide. The content of organic sulfur or phosphorus antiwear additives in the oil composition is preferably less than 800 mg / kg of the formulation and even more preferably less than 400 mg / kg. The lower limit is preferably 1 mg / kg, more preferably 10 mg / kg, most preferably 50 mg / kg.

A copper passivator or electrostatic discharge suppressor, sometimes referred to as a metal deactivator, may be a conventional copper passivator from N-salicylideneethylamine, N, N'-disalicylideneethyl diamine, triethylenediamine, ethylenediaminetetraacetic acid, phosphoric acid, citric acid and gluconic acid. More preferred are lecithin, thiadiazole, imidazole and pyrazole and their derivatives. Even more preferred are dialkyl dithiophosphates, zinc dialkyl dithiocarbamates and benzotriazoles and their tetrahydro derivatives. Most preferred are compounds according to formula (II) or even more preferred are optionally substituted benzotriazole compounds represented by formula (III)

in which R4 may mean hydrogen or a group represented by formula (IV)

or formula (V)

wherein:

c is 0.1, 2 or 3;

R3 represents an unbranched or branched C _1-4 alkyl group. Preferably R3 is methyl or ethyl, and c is 1 or 2. R5 is a methylene or ethylene group; R6 and R7 are hydrogen or the same or different unbranched or branched alkyl groups having 1-18 carbon atoms, preferably a branched alkyl group of 1-12 carbon atoms; R8 and R9 are the same or different alkyl groups of 3-15 carbon atoms, preferably of 4-9 carbon atoms.

Preferred compounds are 1- [bis (2-ethylhexyl) aminomethyl] benzotriazole, methylbenzotriazole, dimethylbenzotriazole, ethylbenzotriazole, ethylmethylbenzotriazole, diethylbenzotriazole and mixtures thereof. Other preferred compounds include (N-bis (2-ethylhexyl) aminomethyl) toluene triazole, unsubstituted benzotriazole and 5-methyl-1H-benzotriazole. Examples of the above copper passivating additives are described in US-A-5912212, EP-A-1054052 and US-A-2002/0109127, these publications are references in the present invention. These benzotriazole compounds are preferred because they also serve as an electrostatic discharge suppressor, which is advantageous when the oil composition is used as an insulating oil. Copper passivating additives, such as those described above, are commercially available products under the names BTA, TTA, IRGAMET 39, IRGAMET30 and IRGAMET 38S from CIBA Ltd Basel Switzerland, and are also marketed under the trademark Reomet from CIBA.

The preferred content of the above copper passivator in the oil composition is more than 1 mg / kg and more preferably above 5 mg / kg. The practical upper limit may vary depending on the particular application of the oil composition. For example, when it is desirable to improve the characteristics of the dielectric discharge in oil, which is used as an insulating oil, it is desirable to add an additive - a passivator of copper in high concentration. This concentration can reach up to 3 wt.%, However, preferably in the range from 0.001 to 1 wt.%. The inventors have found that the advantages of the present invention can be realized at concentrations below 1000 mg / kg and more preferably below 300 mg / kg, even more preferably below 50 mg / kg.

In addition, the oil composition preferably contains an antioxidant additive. It has been found that especially when the base oil is a mineral paraffin base oil or a Fischer-Tropsch derived base oil, and when an antioxidant is also present, the amount of sludge formed and overall acidity are significantly reduced, which are determined after the oxidation test of IEC 61125 C, and these characteristics are indicators of good oxidation stability of the oils. The antioxidant can be a so-called hindered phenolic or amine antioxidant, for example, naphthols, sterically hindered monoatomic, diatomic and triatomic phenols, sterically hindered di-nuclear, trinuclear and polynuclear phenols, alkylated or styrene-containing diphenylamines or hindered phenols - derived ions. Particularly promising sterically hindered phenolic antioxidants are selected from the group consisting of 2,6-di-tert-butylphenol (IRGANOX ™ L 140, CIBA), di-tert-butylated hydroxytoluene (BHT), methylene-4,4'-bis- (2.6-tert-butylphenol), 2,2'-methylene-bis- (4,6-di-tert-butylphenol), 1,6-hexamethylene-bis- (3,5-di-tert-butyl-hydroxyhydrocinnamate) (IRGANOX TM L109, CIBA), ((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) thio) -acetic acid, C ₁₀ -C ₁₄ isoalkyl esters (IRGANOX TM L118, CIBA) , 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid, C ₇ -C ₉ alkyl esters (IRGANO X TM L135, CIBA,) tetrakis- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl-hydroxymethyl) methane (IRGANOX TM 1010, CIBA), bis (3,5-di- thioethylene ether tert-butyl-4-hydroxyhydrocinnamic acid (IRGANOX ™ 1035, CIBA), octadecyl ester of 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid (IRGANOX ™ 1076, CIBA) and 2,5-di-tert-butylhydroquinone. These products are well known and commercially available. Of these, the most promising is the C ₇ -C ₉ -alkyl ester of 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid.

Examples of amine antioxidants are antioxidants - aromatic amines, for example, N, N'-diisopropyl-para-phenylenediamine, N, N'-di-sec-butyl-para-phenylenediamine, N, N'-bis (1,4-dimethylpentyl) -para-phenylenediamine, N, N'-bis (1-ethyl-3-methylpentyl) -para-phenylenediamine, N, N'-bis (1-methyl-heptyl) -para-phenylenediamine, N, N'-dicyclohexyl-para- phenylenediamine, N, N'-diphenyl-papa-phenylenediamine, N, N'-di (naphthyl-2) -para-phenylenediamine, N-isopropyl-N'-phenyl-papa-phenylenediamine, N- (1,3-dimethylbutyl ) -N'-phenyl-para-phenylenediamine, N (1-methylheptyl) -N'-phenyl-para-phenylenediamine, N'-cyclohexyl-N'-phenyl-vapor a-phenylenediamine, 4- (para-toluene-sulfamido) diphenylamine, N, N'-dimethyl-N, N'-di-sec-butyl-para-phenylenediamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxyphenylamine, N-phenyl -1-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, e.g. p, p'-di-tert-octyl diphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol di (4-methoxyphenyl) amine, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N, N, N ', N'-tetramethyl-4 , 4'-diaminodiphenylmethane, 1,2-di- (f enylamino) ethane, 1,2-di [(2-methylphenyl) amino] ethane, 1,3-di (phenylamino) propane, (ortho-tolyl) biguanidine, di [4- (1 ', 3'-dimethylbutyl) phenyl ] amine, tert-octylated N-phenyl-l-naphthylamine, a mixture of mono- and dialkylated tert-butyl- / tert-octyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, N-allylphenothiazine, tert-octylated phenothiazine, 3,7-di-tert-octylphenothiazine. In addition, possible amine antioxidants are compounds in accordance with Formulas VIII and IX of EP-A-1054052, which are also described in US Pat. No. 5,424,601, these publications being references in the present invention.

The content of the antioxidant additive is preferably less than 2 wt.% And more preferably less than 1 wt.%. This content is preferably less than 0.6 wt.% In some applications, such as using an oil composition as an insulating oil. Preferably, the antioxidant content is greater than 10 mg / kg.

Preferably, the oil composition has a sulfur content below 0.5 wt.% And even more preferably below 0.15 wt.%. The main source of sulfur in the oil composition will be sulfur, which is contained in the base oil component of the oil composition according to the invention.

Preferably, the base oil composition has a kinematic viscosity at 100 ° C. of less than 50 mm ² / s, more preferably between 2 and 25 mm ² / s, most preferably between 2 and 15 mm ² / s. Preferably, the base oil composition has a kinematic viscosity at 40 ° C. between 1 and 200 mm ² / s, more preferably between 3.5 and 100 mm ² / s, most preferably between 5 and 12 mm ² / s. In addition, the viscosity of the base oil composition may depend on the particular application of the oil composition. If the oil composition is used as an insulating oil, preferably its kinematic viscosity at 40 ° C. is between 1 and 50 mm ² / s. More preferably, if this formulation of electrical insulating oil is a transformer oil, then preferably the base oil will have a kinematic viscosity at 40 ° C. between 5 and 15 mm ² / sec. If the insulating oil is a low temperature switch oil, then the viscosity of the base oil at 40 ° C. is preferably between 1 and 15 and more preferably between 1 and 4 mm ² / s.

The flash point of the base oil composition as measured by ASTM D92 may be greater than 90 ° C, preferably greater than 120 ° C, even more preferably greater than 140 ° C, and even more preferably greater than 170 ° C. An increased flash point is desirable for applications where the temperature peak may exceed the average oil temperature, for example, in applications with a high temperature and / or with a limited heat transfer potential. Examples are electric transformers and electric motors.

The base oil composition may contain one or more base oils selected from mineral-based naphthenic base oils, mineral-based paraffin base oils, or Fischer-Tropsch derived base oils.

Thus, the base oil composition may include a mineral-based base oil of the so-called paraffin type or naphthenic type. Such base oils are obtained using oil refining processes based on paraffinic and naphthenic crude oils. In the framework of the present invention, mineral-based naphthenic base oils are defined as oils having as a pour point below -20 ° C and a viscosity index below 70. Mineral-based base oils are determined by a viscosity index of greater than 70, preferably greater than 90. Naphthenic and Mineral-based paraffin base oils are well known and described in more detail in the book "Processing of Lubricating Base Oil and Wax," Avilino Sequeira, Jr., Marcel Dekker, Inc, New York, 1994, ISBN 0-8247-9256-4, p. 28-35.

The inventors have found that oil compositions with very good oxidation stability can be obtained when the base oil composition has a saturated content, measured by IP386, preferably greater than 98 wt.%, More preferably higher than 99 wt.% And even more preferably higher than 99.5 wt.%, which is measured for fresh base oil.

Preferably, the base oil composition includes a base oil containing a series of isoparaffins having n, n + 1, n + 2, n + 3 and n + 4 carbon atoms, where n is a number between 20 and 35.

Preferably, the paraffin content of the base oil composition is more than 80 wt.%, More preferably more than 90 wt.%, Even more preferably higher than 95%, and even more preferably higher than 98%.

In addition, the base oil composition may preferably have a naphthenic compound content between 1 and 20 wt.%. It has been found that these base oils have good pick-up for the above additives when it is desirable to improve oxidative stability. The content of naphthenic compounds and the presence of such a continuous series of isoparaffins can be measured using the field desorption / field ionization (FD / FI) method. In this method, the oil sample is first separated into the polar (aromatic) phase and the non-polar phase (saturated compounds) using IP368 / 01 high-performance liquid chromatography (HPLC), in which pentane is used instead of hexane as the mobile phase, as in the specified method. The fractions of saturated and aromatic compounds are then analyzed using a Finnigan MAT90 mass spectrometer equipped with a field desorption / field ionization (FD / FI) interface in which the FI (soft ionization) technique is used to determine the type of hydrocarbon in terms of carbon number and deficiency hydrogen.

The typical classification of compounds in mass spectrometric analysis is determined according to the generated characteristic ions, and they are usually classified by the "number z". This is given by the general formula for all hydrocarbon particles: C _n H _{2n + z} . Since the phase of saturated compounds is analyzed separately from the aromatic phase, it is possible to determine the content of various isoparaffins having the same stoichiometry or number n. Mass spectrometric analysis results are processed using an industrial program (poly 32; available from Sierra Analytics LLC, 3453 Dragoo Park Drive, Modesto, California GA95350 USA) in order to determine the relative proportions of each type of hydrocarbon.

Base oil compositions having a continuous series of isoparaffins, as described above, are preferably prepared by hydroisomerization of paraffin wax, even more preferably followed by a certain type of dewaxing, such as solvent dewaxing or catalytic dewaxing.

The base oil composition described above can preferably be obtained by hydroisomerization of paraffin wax, preferably followed by dewaxing treatment, such as solvent treatment or catalytic dewaxing. Paraffin wax can be paraffin wax with a high paraffin content. More preferably, paraffin wax is produced in the Fischer-Tropsch synthesis, since this wax is pure and has a very high paraffin content.

Base oils produced in the Fischer-Tropsch synthesis, as described in this invention, will be referred to herein as base oils produced in the Fischer-Tropsch synthesis.

Examples of Fischer-Tropsch syntheses, which, for example, can be used to produce the Fischer-Tropsch derived base oil described above, are the so-called industrial Sasol suspension distillate production technology, Shell middle distillate synthesis method and method " AGC-21 "by Exxon Mobil. These and other methods are described in more detail, for example, in documents EP-A-776959, EP-A-668342, US-A-4943672, US-A-5059299, WO-A-9934917 and WO-A-9920720. Typically, these Fischer-Tropsch synthesis products will contain hydrocarbons having from 1 to 100 and even more than 100 carbon atoms. This hydrocarbon product may include normal paraffinic, isoparaffinic, oxygen-containing compounds and unsaturated compounds. If the base oil is one of the desired isoparaffin products, then it may be advantageous to use relatively heavy Fischer-Tropsch derived feedstocks. This relatively heavy Fischer-Tropsch derived feed contains at least 30 wt.%, Preferably at least 50 wt.% And more preferably at least 55 wt.% Of compounds having, by at least 30 carbon atoms. In addition, the weight ratio of compounds having at least 60 or more carbon atoms and compounds containing at least 30 carbon atoms in the Fischer-Tropsch feed is preferably at least 0 , 2, more preferably at least 0.4, and most preferably at least 0.55. Preferably, the Fischer-Tropsch feed comprises a C20 + fraction having an alpha-ACF coefficient (Anderson-Schulz-Flory chain growth factor) of at least 0.925, preferably at least 0.935, more preferably at least 0.945, even more preferably at least 0.955. Such raw materials produced in the Fischer-Tropsch synthesis can be obtained in any process in which the relatively heavy product of the Fischer-Tropsch synthesis, which is described above, is formed. Such a heavy product is not formed in all Fischer-Tropsch processes. An example of a suitable Fischer-Tropsch process is described in WO-A-9934917.

A product made in the Fischer-Tropsch synthesis may contain very little (or absent) sulfur and nitrogen compounds. This is characteristic of a product made in the Fischer-Tropsch synthesis, in which synthesis gas is used, almost free of impurities. The sulfur and nitrogen content will usually be lower than the detection level, which is currently 5 mg / kg for sulfur and 1 mg / kg for nitrogen, respectively.

Typically, the method may include Fischer-Tropsch synthesis, a hydroisomerization step, and an optional step to reduce the pour point, wherein said hydroisomerization step and an optional step to reduce the pour point are carried out as follows:

(a) hydrocracking / hydroisomerization of a Fischer-Tropsch synthesis product,

(b) separating the product of step (a) into at least one or more fractions of a distillate fuel and a base oil or an intermediate fraction of a base oil.

If the viscosity and pour point of the base oil obtained in step (b) are as desired, then additional processing is not required, and this oil can be used as the base oil according to the invention. If necessary, the pour point of the intermediate base oil fraction is further reduced accordingly in step (c) by solvent dewaxing or preferably catalytic dewaxing of the oil obtained in step (b) in order to obtain an oil having a preferably low pour point. The desired viscosity of the base oil can be obtained by isolating, by distillation, from the intermediate fraction of the base oil or from a dewaxed oil of a product with a suitable boiling range corresponding to the desired viscosity. The distillation can be carried out appropriately as a vacuum distillation step.

Preferably, the hydroconversion / hydroisomerization processes in step (a) are carried out in the presence of hydrogen and a catalyst, which catalyst may be selected from those known to those skilled in the art as suitable for this process; some of these catalysts will be described in more detail below. In principle, the catalyst can be any catalyst known in the art as suitable for isomerization of paraffin molecules. In general, suitable hydroconversion / hydroisomerization catalysts are those that contain a hydrogenation component supported on a refractory oxide support such as amorphous aluminosilicate (AAC), alumina, fluorinated alumina, molecular sieves (zeolites), or mixtures of two or more thereof components. One type of preferred catalysts that can be used in the hydroconversion / hydroisomerization step of the present invention are hydroconversion / hydroisomerization catalysts containing platinum and / or palladium as a hydrogenation component. A highly preferred hydroconversion / hydroisomerization catalyst includes platinum and palladium supported on an amorphous aluminosilicate (AAC) support. It is advisable that platinum and / or palladium are present in an amount of from 0.1 to 5.0 wt.%, More suitably, from 0.2 to 2.0 wt.%, Calculated on the element related to the total weight of the carrier. If both metals are present, then the weight ratio of platinum to palladium can vary widely, but it is advisable in the range from 0.05 to 10, more preferably 0.1 to 5. Examples of suitable noble metals on AAS are, for example, the catalysts described in WO-A-9410264 and EP-A-0582347. Other suitable noble metal catalysts, such as platinum on a fluorinated alumina support, are described, for example, in US Pat. No. 5,092,999 and WO-A-9,220,759.

A second type of suitable hydroconversion / hydroisomerization catalysts are those containing at least one metal from group VIB, preferably tungsten and / or molybdenum, and at least one base metal from group VIII, preferably nickel and / or cobalt, in as a hydrogenating component. Both metals may be present in the form of oxides, sulfides, or combinations thereof. The metal of group VIB is suitably present in an amount of from 1 to 35 wt.%, More suitably from 5 to 30 wt.%, Based on the element, referred to the total weight of the carrier. It is advisable that the base metal of group VIII is present in an amount of from 1 to 25 wt.%, Preferably from 2 to 15 wt.%, Calculated on the element related to the total weight of the carrier. A hydroconversion catalyst of this type, which is found to be particularly suitable, is a catalyst containing nickel and tungsten supported on fluorinated alumina.

The above base metal catalysts are preferably used in sulfide form. In order to maintain the sulfide form of the catalyst during its operation, it is necessary that a certain amount of sulfur be present in the feed. Preferably, at least 10 mg / kg, and more preferably between 50 and 150 mg / kg of sulfur, is present in the feed.

A preferred catalyst that can be used in a non-sulfidized form includes a non-noble metal of group VIII, for example, iron, nickel, in combination with a metal of group IB, for example, copper supported on an acidic support. Preferably, copper is present to suppress the hydrogenolysis of paraffins to methane. Preferably, the catalyst has a pore volume in the range of 0.35 to 1.10 ml / g, which is determined by the absorption of water, a surface area of preferably between 200 and 500 m ² / g, which is determined by the BET method for nitrogen adsorption, and a bulk density between 0 , 4 and 1.0 g / ml. Preferably, the catalyst support is an amorphous aluminosilicate in which alumina may be present in the range between 5 and 96 wt.%, Preferably between 20 and 85 wt.%. The content of silicon dioxide in the form of SiO _{2 is} preferably between 15 and 80 wt.%. In addition, the carrier may contain small amounts, for example, 20-30 wt.%, A binder, for example, alumina, silica, Group IVA metal oxides, and various types of clays, magnesium oxide, etc., preferably alumina or silica .

The preparation of amorphous aluminosilicate microspheres is described by Ryland, B. Lloyd, Tamele, M.W., and Wilson, J.N. "Cracking catalysts." Catalysis: Volume VII, eds. Paul H. Emmett, Reinhold Publishing Corporation, New York, 1960, pp. 5-9.

The catalyst is obtained by co-impregnating the carrier with metals from solutions, drying at 100-150 ° C and calcining in air at 200-550 ° C. Group VIII metal is present in an amount of about 15 wt.% Or less, preferably 1-12 wt.%, While a group IB metal is usually present in a smaller amount, for example, in a weight ratio of about 1: 2 to 1:20 relative to the group metal Viii.

A typical catalyst is described below:

Ni, wt.% 2.5-3.5 Cu, wt.% 0.25-0.35 Al ₂ O ₃ -SiO ₂ wt.% 65-75 Al ₂ O ₃ (binder) wt.% 25-30 Surface area 290-325 m ² / g Pore volume (mercury) 0.35-0.45 ml / g Bulk density 0.58-0.68 g / ml

Another class of suitable hydroconversion / hydroisomerization catalysts are those based on molecular sieve materials, suitably containing at least one Group VIII metal component, preferably Pt and / or Pd, as a hydrogenation component. Suitable zeolite and other aluminosilicate materials then include zeolite beta, zeolite Y, ultrastable Y, ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48, MCM-68, ZSM-35, SSZ-32 ferrierite, mordenite and silicon dioxide-aluminophosphates such as SAPO-11 and SAPO-31. Examples of suitable hydroconversion / hydroisomerization catalysts are, for example, those described in WO-A-9201657. In addition, combinations of these catalysts are possible. Very suitable hydroconversion / hydroisomerization processes are those that include the first stage, which uses a catalyst based on zeolite beta or ZSM-48, and the second stage, which uses a catalyst based on zeolites ZSM-5, ZSM-12, ZSM-22 , ZSM-23, ZSM-48, MCM-68, ZSM-35, SSZ-32, ferrierite, mordenite. Of the latter group, ZSM-23, ZSM-22, and ZSM-48 are preferred. Examples of such processes are described in US-A-20040065581, which discloses a process that includes a catalyst containing platinum and zeolite beta in a first step and a catalyst containing platinum and ZSM-48 in a second step.

Combinations of processes in which the Fischer-Tropsch synthesis product is first sent to the first hydroisomerization step using an amorphous catalyst containing an aluminosilicate carrier as described above, followed by the second hydroisomerization step using a molecular sieve catalyst, are also recognized as preferred methods for producing a base oil. which can be used in the present invention. More preferably, the first and second hydroisomerization steps are carried out sequentially in a stream. Most preferably, these two steps are carried out in a single reactor containing layers of the above amorphous and / or crystalline catalyst.

In step (a), the feed is contacted with hydrogen in the presence of a catalyst at elevated temperatures and pressures. Typically, the temperature may range from 175 to 380 ° C., preferably higher than 250 ° C., and more preferably from 300 to 370 ° C. Typically, the pressure may be in the range from 10 to 250 bar (1-25 MPa) and preferably between 20 and 80 bar. Hydrogen gas may be supplied at a space velocity of from 100 to 10,000 nl / liter per hour, preferably from 500 to 5,000 nl / liter per hour. The hydrocarbon feed may be supplied at a space velocity of 0.1 to 5 kg / liter per hour, preferably higher than 0.5 kg / liter per hour, and more preferably less than 2 kg / liter per hour. The hydrogen / hydrocarbon ratio may vary from 100 to 5000 nl / kg and preferably from 250 to 2500 nl / kg.

The degree of conversion in stage (a), which is defined as the percentage of raw materials (by weight) boiling above 370 ° C, which is converted in one pass into a fraction boiling below 370 ° C, is at least 20 wt.%, Preferably at least 25 wt.%, but preferably not more than 80 wt.%, more preferably not more than 65 wt.%. As used above, the term “feed” in the definition is the total hydrocarbon feed fed to step (a), and thus also includes any optional recycling of the high boiling fraction that can be obtained in step (b).

In step (b), the product of step (a) is preferably separated into one or more distillate fuel and base oil fractions, or a base oil precursor fraction having the desired viscosity characteristics. If the pour point is outside the desired range, then the base fluid pour point is further reduced using the dewaxing step (c), preferably by catalytic dewaxing. In such an embodiment, an additional advantage can be obtained by dewaxing a wider fraction of the product of step (a). Then, base oil and oils having a desired viscosity can be isolated predominantly by distillation from the obtained dewaxed product. The dewaxing is preferably carried out by catalytic dewaxing, for example, as described in WO-A-02070629, which is a reference in the present invention. The end boiling point of the feed for the dewaxing step (c) may be the end boiling point of the product of step (a) or lower, if desired.

The oil composition may include a single type of base oil or a mixture of the base oils described above as the base oil composition. Preferably, the present invention further relates to formulations in which the base oil composition comprises at least 80% of the total weight of the mineral-based naphthenic base oil formulation; to formulations in which the base oil includes at least 80% of the total mass of mineral-based paraffin base oil; and to formulations in which the base oil composition contains at least 80 wt.% of the Fischer-Tropsch derived base oil.

In addition, additional base oils and other synthetic components of base oils may be present in the oil composition, for example, esters, poly-alpha olefins, which are preferably obtained by oligomerization of olefin compounds, polyalkylene glycols and the like. Possible base oil compositions preferably include mineral-based paraffinic and Fischer-Tropsch derived base oils, mineral-based naphthenic base oils and Fischer-Tropsch derived base oils, and mixtures of the three base oil components.

However, it has been found that it is especially advantageous to use a Fischer-Tropsch derived base oil as the practically sole component of the base oil. The term practically means here that more than 80 wt.%, More preferably more than 90 wt.% And most preferably 100 wt.% Of the base oil component in the oil composition is a Fischer-Tropsch derived base oil, which is described in detail above. .

In addition to the additive described above, additional additives may also be present in the composition. The type of additives will depend on the specific application. Without the intention of creating limitations, examples of possible additives are dispersants, detergents, viscosity modifying polymers, flow loss depressants such as hydrocarbons or oxidized hydrocarbons, emulsifiers, demulsifiers, anti-corrosion additives and friction modifiers. Specific examples of such additives are described, for example, in the Encyclopedia of Chemical Technology (Kirk-Othmer Encyclopedia of Chemical Technology), 3rd edition, Volume 14, pages 77-526. Suitably, the dispersant is an ashless dispersant, for example polyamines of polybutylene succinimide or dispersers of the Mannich base type. Accordingly, the detergent is a detergent with an excess of the base metal, for example, phosphonate, sulfonate, phenolate or salicylate type, as described above with reference to the General allowance. Suitably, the viscosity modifier is a viscosity modifying polymer, for example polyisobutylene, olefin copolymers, polymethacrylates and polyalkyl styrene and hydrogenated polyisoprene star polymers (Shellvis). Examples of suitable antifoam agents are polydimethylsiloxanes and polyethylene glycol ethers and esters.

Oil compositions can be used as turbine oil, oil for gasoline engines, oil for diesel engines, automotive and industrial gear oils, for example, oils for automatic and manual transmissions and differentials, hydraulic machine oil, refrigerator oil, plastic processing oil for rolling, pressing, forging, crimping, drawing, stamping and the like technological operations, oils for heat treatment, process oils for unloading, oils for the guide rails, protective oil from corrosion and as a coolant. Preferably, the oil composition is used as an electrical insulating oil. In addition, it was found that when the base oil component of the oil composition practically consists of a Fischer-Tropsch derived base oil, an insulating oil formulation is obtained that has good oxidative stability, which manifests itself as low acid formation and / or low sludge formation, and also has excellent low temperature viscosity characteristics. Examples of applications are switch drives, transformers, regulators, circuit breakers, power plant reactors, cables, and other electrical equipment.

When using insulating oil based on naphthenic base oil, the problem often arises that the kinematic viscosity at -30 ° C is too high. When such an oil is intended to be used in areas where operation begins at a low temperature, especially at temperatures below 0 ° C, high viscosity will negatively affect the necessary heat dissipation in the insulating oil. As a result, equipment overheating may occur. The inventors have found that when using a base oil obtained in the Fischer-Tropsch synthesis and having a kinematic viscosity at 40 ° C between 1 and 15 mm ² / sec and the temperature of the fluidity below -30 ° C, more preferably below -40 ° C, an electrical insulating oil is obtained which has the aforementioned desirable characteristics.

In order to improve the tendency of gas evolution by the oil composition, preferably between 0.05 and 10 wt.%, Preferably between 0.1 and 5 wt.% Of the aromatic compound, is added to it. Preferred aromatic compounds are, for example, tetrahydronaphthalene, diethylbenzene, di-isopropylbenzene, a mixture of alkylbenzenes, which are commercially available products such as Shell Oil 4697 or Shellsol A 150 from Shell Deutschland GmbH. Another preferred mixture of aromatic compounds contains a mixture of 2,6-di-tert-butylphenol and 2,6-di-tert-butylcresol. Preferably, the oil composition comprises between 0.1 and 3 wt.% 2,6-di-tert-butylphenol and from 0.1 to 2 wt.% 2,6-di-tert-butylcresol in a weight ratio of between 1: 1 and 1: 1.5.

Preferably, the anti-wear additive oil composition is further purified with bleaching clay. Clay bleaching is a well-known treatment for removing polar compounds from an oil composition. This treatment is carried out in order to further improve the color, chemical and thermal stability of the oil composition. It can be carried out before adding the additives mentioned in this description, on a partially composed oil composition. Methods for cleaning with bleaching clay are described, for example, in the book “Processing of base lubricating oil and wax”, Avilino Sequeira, Jr., Marcel Dekker, Inc, New York, 1994, ISBN 0-8247-9256-4, p. 229 -232. Preferably, the copper passivator and optional antioxidant are added after cleaning with bleaching clay.

Oil compositions containing a Fischer-Tropsch derived base oil as described above exhibit a very low dielectric loss, even after lengthy tests at elevated temperatures. A low value of the loss tangent characterizes small losses of electricity in the field of application of electrical insulating oil. Since the loss tangent does not significantly increase over time, especially when compared with naphthenic-based insulating oil compositions, high efficiency is achieved in this field of application.

The above insulating oil can be used in areas where regular start-up is required, in particular more than 10 times a year at temperatures below 0 ° C, more preferably below -5 ° C, and the temperature of the oil during its operation is above 0 ° C . Examples of such applications are low temperature switch gear oils, transformers, regulators, circuit breakers, power plant reactors, switch drives, cables, and electrical equipment. Such applications are well known to those skilled in the art and are described, for example, in the book Lubricating Oils and Related Products, Dieter Klamann, Verlag Chemie GmbH, Weinhem, 1984, pp. 330-339.

The present invention will be illustrated by the following non-limiting examples. Four different types of base oils are used in these examples. One base oil produced in the Fischer-Tropsch synthesis is called GTL VO, two base oils of the naphthenic type are called naphthenic-1 and naphthenic-2 and mineral paraffin base oil. The characteristics of these base oils are shown in table 1.

Table 1 Base oil GTL VO-1 GTL BO-2 GTL BO-3 Naphthene-1 Naphthene-2 Paraffin-1 Paraffin-2 KB * at 100 ° C ASTM D445 mm ² / s 2,4 4.0 7.8 2.1 2.1 2.2 8.3 KB * at 40 ° C ASTM D445 mm ² / s 7.9 8.8 7.8 8.0 75.1 Viscosity index ASTM D2270 126 135 148 0 47 88 73 Pour point ASTM D5950 ° C -51 -thirty -24 -60 -60 -fifteen -eighteen Flash point ASTM D92 ° C 192 228 274 147 154 186 232 Paraffins according to the FD / FI method wt.% 90.7 92.3 90.8 Carbon atom distribution see figure 1 ** figure 2 ** Basic nitrogen ISO 3771mod mg / kg four <1 one 3 Sulfur ISO 14596 wt.% <0.001 0,075 0.001 0.015 0,021 Color ASTM D2049 L0.5 L0.5 L0.5 L0.5 L1.5 Biodegradation after 28 days ISO 14593 % 60 * Kinematic viscosity
(**) The distribution of carbon atoms by the number of carbon atoms, measured by the field desorption / field ionization (FD / FI) method, in which Z = 2 corresponds to iso- and normal paraffins, Z = 0 corresponds to single-ring naphthenic compounds,
Z = -2 - two-ring naphthenic compounds, Z = -4 - three-ring naphthenic compounds, etc.

Example 1

In Example 1, two formulations A and B are obtained in which the base oil component consists of 95 wt.% Naphthenic-2 base oil and 5 wt.% Of paraffin-1 base oil. To these mixtures was added 10 mg / kg of 1- [bis (2-ethylhexyl) aminomethyl] benzotriazole (Reomet38S). 200 mg / kg of dibenzyl disulfide is added to mixture A and 200 mg / kg of di-n-dodecyl disulfide is added to mixture B. Oil mixtures A and B are tested according to the method of IEC 61125 C oxidation tests for 164 hours at 120 ° C with a measurement of the acidity of a small phase. The acidity of the oil phase of mixture A is 0.26 mg KOH / g and the acidity of the oil phase of mixture B is 0.94 mg KOH / g. Both values are very low and exhibit excellent oxidative stability. The acidity for mixture A shows that even better results are obtained. When a preferred dibenzyl disulfide additive is used as an organic polysulfide anti-wear additive, it is surprising that the selection of a particular anti-wear additive can improve oxidative stability, as demonstrated in the example.

Example 2

Based on mineral-based naphthenic-1 base oil, mineral-based paraffin base-1 oil and GTL base oil-1 from table 1, five different oil mixtures were prepared in accordance with the addition schemes 1-5 in table 2. For all of these oil mixtures, the formation of sludge is determined in accordance with the oxidation test of IEC 61125 C for 164 hours at 120 ° C. The lower the oxidizability value, the less sludge is formed. The results are also presented in table 2.

From table 2 it can be seen that the combination of an organic polysulfide anti-wear additive and a copper passivator leads to the formation of a very small amount of sludge. Especially significantly reduced sludge formation for mineral paraffin base oils and base oils produced in the Fischer-Tropsch synthesis in the presence of an antioxidant.

table 2
Sludge formation in accordance with IEC 61125 C Add Scheme one 2 3 four 5 Dibenzyl disulfide mg / kg - 200 200 200 1- [bis (2-ethylhexyl) aminomethyl] benzotriazole (Reomet38S) mg / kg 10 10 10 BHT Antioxidant wt.% 0.08 Naphthenic base oil Sludge 1,700 1,530 0.561 0.281 0.295 Paraffin Base Oil-1 Sludge 3,340 2,440 0.209 0,086 <0.006 GTL base oil-1 Sludge 0,085 0,023 0,043 0,071 0.006

For all of these oil mixtures, the total acidity was also determined using the oxidation test of IEC 61125 C for 164 hours at 120 ° C in accordance with the aforementioned schemes of additions 1-5. The lower the acidity, the less acidic compounds are formed and the higher the oxidation stability of the oil composition. The results are presented in table 3.

Table 3
Formation of total acidity in accordance with IEC 61125 C Add Scheme one 2 3 four 5 Dibenzyl disulfide mg / kg 200 200 200 1- [bis (2-ethylhexyl) aminomethyl] benzotriazole mg / kg 10 10 10 BHT Antioxidant wt.% - 0.08 Total acidity according to IEC 61125 C Naphthenic base oil-1 mg KOH / g 4.14 3.87 1,59 0.83 1,02 Paraffin Base Oil-1 mg KOH / g 9.12 6.78 0.78 0.38 0.02 GTL Base Oil-1 mg KOH / g 13.67 10.55 12.65 12.57 0.10

Example 3

In accordance with the addition schemes indicated in table 4, four oil mixtures were prepared. The two oil mixtures are cleaned with bleaching clay using Tonsil 411 clay, available from Sued Chemie, Munchen (D). Antioxidant and passivating copper additives are added after cleaning with bleaching clay. The characteristics of the oil mixtures are determined and the oil mixtures are subjected to an IEC oxidation test for 500 hours at 120 ° C.

As can be seen from table 4, the oil composition based on the base oil produced in the Fischer-Tropsch synthesis has a low viscosity at -30 ° C in combination with excellent oxidative stability characteristics. The gas evolution trend for mixture Z in table 4 can be improved by adding an aromatic solvent, as shown in table 5.

Table 5 Sample designation Z Z ' GTL base oil-1 wt.% 94.68 94.18 Naphthenic base oil-1 wt.% Mineral Paraffin Base Oil-1 wt.% 5.00 5.00 Dibenzyl disulfide (antiwear additive) wt.% 0.02 0.02 Clay Whitening (Tonsil) wt.% one one 1- [bis (2-ethylhexyl) aminomethyl] benzotriazole mg / kg 10 10 Shellsol A 150 (aromatic hydrocarbon solvent) wt.% no 0.5 BHT Antioxidant wt.% 0.30 0.30 Outgassing trend measured in accordance with BS 5797 mm ³ / min > 0 -8.9

Example 4

In accordance with the formulations shown in Table 6, three AC oil formulations were prepared using GTL 1, 2, and 3 base oils from Table 1. These AC oil formulations were cleaned with bleaching clay using Tonsil 411 clay, which is supplied Sued Chemie, Munchen (D). Antioxidant and passivating copper additives are added after cleaning with bleaching clay.

These oils are tested in the test methods shown in Table 6. The results show that excellent oils have been obtained for use as electrical insulating oils.

Table 6 Oil characteristics Oil A Oil B Oil C Recipe GTL BO-1 wt.% 94.7 GTL BO-2 wt.% 98.7 GTL VO-3 wt.% 98.7 Paraffin base oil 1 wt.% 5,0 Paraffin base oil 2 wt.% 1,0 1,0 Dibenzyl disulfide mg / kg 200 200 200 1- [bis (2-ethylhexyl) aminomethyl] benzotriazole mg / kg 10 10 10 Ionol 861805 % 0.3 0.3 0.3 Test results Test Dimension Method Flash point ° C ISO 2592 160 226 263 Pour point ° C DIN ISO 3016 -51 -thirty -eighteen Kinematic viscosity 40 ° C mm ² / s DIN 51562 7.8 17.5 Not measured Kinematic viscosity 100 ° C mm ² / s DIN 51562 2,4 4.1 7.8 lEC Oxidation test 500 h / 120 ° C IEC 61125 / C - total acidity mg KOH / g 0.02 0.02 0.04 Sludge wt.% <0.006 <0.008 <0.007 - Loss tangent at 90 ° С 0.0035 0,0004 0,0004

Claims (21)

1. An oxidation stable oil composition comprising a base oil composition comprising a mineral-based naphthenic base oil, a mineral-based paraffin base oil, and / or a Fischer-Tropsch paraffin base oil, a copper passivator, and from 0.001 to less than 0.1 wt.% Organic sulfur-based compounds as antiwear additives. 2. The composition according to claim 1, in which the antiwear additive contains an organic polysulfide represented by the formula

wherein:
a means 2, 3, 4 or 5;
R1 and R2 are independently selected from the group consisting of optionally substituted, unbranched or branched, saturated or unsaturated C ₁ -C ₂₅ hydrocarbon groups. 3. The composition according to claim 2, in which R1 and R2 are independently selected from the group consisting of optionally substituted, unbranched or branched, aromatic or aliphatic hydrocarbon groups of C ₄ -C ₂₀ , preferably C ₆ -C ₁₄ . 4. The composition according to claim 3, in which R1 and R2 are independently selected from unbranched or branched dodecyl and benzyl. 5. The composition according to any one of claims 1 to 4, in which the content of sulfur-based organic antiwear additives in the composition is less than 800 mg / kg, more preferably less than 400 mg / kg. 6. The composition according to any one of claims 1 to 4, in which the copper passivator is a compound in accordance with formula (II) or an optionally substituted benzotriazole compound represented by formula (III)

in which R ⁴ may mean hydrogen or a group represented by formula (IV)

or formula (V)

wherein:
c is 0, 1, 2 or 3;
R ³ represents an unbranched or branched C1-4 alkyl group; R ⁵ is a methylene or ethylene group; the radicals R ⁶ and R ⁷ mean hydrogen or the same or different unbranched or branched alkyl groups having 1-18 carbon atoms, preferably a branched alkyl group of 1-12 carbon atoms; R ⁸ and R ⁹ are the same or different alkyl groups of 3-15 carbon atoms. 7. The composition according to claim 6, in which R ³ represents methyl or ethyl and with means 1 or 2. 8. The composition according to any one of claims 1 to 4, in which the content of the passivator of copper is between 5 and 1000 mg / kg 9. The composition according to any one of claims 1 to 4, in which the sulfur content is less than 0.5 wt.%. 10. The composition according to any one of claims 1 to 4, additionally containing an antioxidant additive. 11. The composition of claim 10, in which the antioxidant additive is a phenolic or amine antioxidant. 12. The composition according to claim 11, in which the antioxidant additive is a di-tert-butylated hydroxytoluene. 13. The composition according to any one of claims 1 to 4, in which the composition of the base oil contains at least 80 wt.% Naphthenic base oil on a mineral basis. 14. The composition according to any one of claims 1 to 4, in which the base oil composition contains at least 80 wt.% Mineral-based paraffin base oil. 15. The composition according to any one of claims 1 to 4, in which the base oil composition contains at least 80 wt.% The base oil obtained by the Fischer-Tropsch synthesis. 16. The composition according to any one of claims 1 to 4, in which the kinematic viscosity of the base oil composition at 40 ° C is between 1 and 4 mm ² / s. 17. The composition according to any one of claims 1 to 4, in which the kinematic viscosity of the base oil composition at 40 ° C is between 5 and 15 mm ² / s. 18. A method of obtaining a composition according to any one of claims 1 to 17, in which the mixture of the composition of the base oil and organic antiwear additives based on sulfur is subjected to purification with bleaching clay and then a copper passivator is added. 19. The use of the composition according to any one of claims 1 to 17 as an insulating oil. 20. The use of the composition according to claim 19 as a low-temperature oil for a switchgear. 21. The use of the composition according to claim 19 as a transformer oil.

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