NO119123B - - Google Patents

Description

Process for the production of hydrocarbon

oils with improved aging stability as well as agent

for carrying out the procedure.

The present invention relates to a method for

production of hydrocarbon oils with improved aging stability.

Hydrocarbon oils, such as petrol, kerosene, gas oil and transformer oil are prone to ageing. This aging takes place under the influence of oxygen and peroxides which have been formed and can express themselves e.g. by precipitation of varnish-like or sludge-like products in storage tanks and lines, by a change in viscosity and by the formation of acidic compounds. The aging process is significantly accelerated by traces of metals

which is almost always present in hydrocarbon oil. Copper in particular has a distinct accelerating or accelerating influence on ageing. In transformer oils, e.g. this causes the oil's acid number and the content of sludge-like components to remain in it

so high that the oil must be replaced with fresh oil. In petrol, rubber-like products can form under the line and these cause disturbances in the carburettor and intake system.

A known working technique is to add to the hydrocarbon oils compounds which, due to the formation of complex compounds with the metals present in the oil, eliminate the catalytic effect of these metals on the aging process. The majority of compounds used; for this purpose, however, it has the disadvantage of possessing a group that can react with alkali, the alkali salts that are formed, no longer have any ability to form complex compounds with the catalytically active metals, so that these compounds become inactive. Furthermore, the alkali salts formed are water-soluble so that they e.g. during storage are collected in the aqueous phase that is excreted and they are thus lost.

British patent 931 436 describes complexing agents which, in the presence of alkali, are capable of forming complex compounds with polyvalent metals, and which, if an aqueous phase is present which may be alkaline or non-alkaline, do not pass into in this. The compounds which according to the British patent are added to the hydrocarbon oils have the formula:

where R means a heterocyclic radical containing the group -C=N- in a five- or six-membered ring and Y means hydrogen or a cyclic or acyclic substituent, or the two Y groups form together with the group

a cyclic or ring structure.

The present invention relates to the production of hydrocarbon oils containing compounds of this type.

Although these compounds are extremely active as metal deactivators, and furthermore do not exhibit the disadvantages associated with the use of the aforementioned metal deactivators, they do however exhibit a certain disadvantage which causes difficulties when these compounds are used in practice. Their solubility in hydrocarbon oils is relatively low, which makes correct dosing difficult.

The applicant has now discovered the surprising fact that the dosing problems associated with the use of the present metal deactivators can be completely eliminated if the metal deactivators are added to the hydrocarbon oil in the form of a mixture

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with an antioxidant of the phenol type or the amine type.

The invention therefore relates to a method for producing hydrocarbon oils with improved aging stability, which involves the addition of one or more metal deactivators of the formula:

where R means a heterocyclic radical containing the group -C=N- in a five- or six-membered ring and Y means hydrogen or a cyclic or acyclic substituent, or the two Y groups form together with the group

a cyclic structure, to a hydro-

carbon oil, and the method is characterized in that the metal deactivator is in the form of a previously prepared mixture with one or more antioxidants of the phenol type and/or amine type.

Antioxidants of the phenol type and/or amine type include both antioxidants that contain one or more phenolic hydroxyl groups and those in which one or more amine groups occur, as well as antioxidants that contain one or more amine groups in addition to one or more phenolic hydroxyl groups. These antioxidants have a very favorable effect on the oxidation stability of hydrocarbon oils to which they are added.

One of the most advantageous features of the present invention is that the metal deactivators can be taken up in hydrocarbon oils in the desired concentrations in a simple way, without at the same time introducing foreign auxiliary substances into the hydrocarbon oils which, when the hydrocarbon oils are used, can lead to disturbing side effects. This is of particular importance for applications where high demands are made with regard to the hydrocarbon oil's electrical resistance, such as in transformer oils.

The invention is of particular interest in cases where the hydrocarbon oil is to contain the specified metal activator as well as an antioxidant of the phenol type and/or amine type.

Hydrocarbon oils with which it is desirable to improve aging stability according to the invention are primarily petrol, kerosene, gas oil and transformer oil, particularly petrol and kerosene. During the refining process, these hydrocarbon oils come into contact with the alkali solution and traces of these may remain in the hydrocarbon oil. When the oils are pumped through pipelines, traces of alkali can also be absorbed, as these pipelines

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are mostly protected against corrosion by injecting alkaline corrosion inhibitors. During storage, traces of water can get into the hydrocarbon oil, e.g. by condensation of water vapour. With transformer oil, condensation of water vapor can also occur during use as a result of temperature changes that occur in transformers that are installed outdoors.

Other hydrocarbon oils of which it is also desirable to improve the aging stability are lubricating oils, in particular such lubricating oils as are used in crankcase oils in marine diesel engines with separate cylinder lubrication.

Examples of metal deactivators that can be added to the hydrocarbon oil in the form of a pre-prepared mixture with an antioxidant of the phenol type and/or amine type are compounds in which the group R is a thiazole, pyridine, quinoline or iso-pyrrole ring, especially compounds where this ring is bonded to the nitrogen atom in the 2-position.

The group R occurs twice in this formula. It is not necessary that the two R groups represent the same group, e.g. both a pyridine ring or both a thiazole ring. Such compounds are also desirable where an R group represents e.g. one pyridine ring and the other, e.g. a thiazole ring.

Y can e.g. be an alkyl group or a phenyl group which may contain substituents. As noted in connection with R, the two Y groups need not necessarily be the same group-

per, or the two Y groups can together with the group

create

a cyclical structure. In the latter case, they form two Y groups, e.g. the group -CR'=CR'-, in which R<1>is hydrogen or a hydrocarbon group, or both Y groups are two neighboring carbon atoms in a benzene ring or two neighboring carbon atoms in a naphthene ring.

Particularly desirable are compounds where R is a pyridine ring bound to the nitrogen atom in the 2-position and where the Y groups are two neighboring carbon atoms in a benzene ring, compounds where R is a pyridine ring bound to the nitrogen atom in the 2-position and where the two Y groups form the group -CR'-CR<1->, where R'

is a phenyl group, as well as compounds where R is a thiazole ring bound to the nitrogen atom in the 2-position and where the two Y groups are two neighboring carbon atoms in a benzene ring and compounds where R is a pyridine ring bound to the nitrogen atom in the 2-position and where the two Y groups are the two neighboring carbon atoms, joined by a double bond, in a 1,4-dithia-2,3-dehydrocyclohexane ring.

According to the invention, very satisfactory results can be obtained by using one or more of the following compounds: 1,3-di(2<1->pyridylimino)isoindoline, 2,5-di(2'-pyridylimino)-3,4- diphenylpyrroline, 1,3-di(2'-thiazolylimino)iso-indoline, 1,3-di(2'-pyridylimino)-4,7-dithia-4,5,6,7-tetrahydro-isoindoline.

Examples of antioxidants which may be mixed with the metal deactivators before being added to the hydrocarbon oil include the following: (1) Phenolic type antioxidants, such as: 2,4-dimethyl-6-tert-butylphenyl, 2,6-di-tert- butyl-4-methylphenol, 4,4'-methylene-bis-2,6-di-tert-butylphenol, 2,6-di-tert-butylphenol, 2-tert-butylphenol, 2,4,6-tris(3 ,5-di-tert-butyl-4-hydroxybenzyl)-phenol, 2,4,6-tri-tert-butylphenol, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) mesitylene, 4,4'-bis-2,6-di-tert-butylphenol, bis(3,5-di-tert-butyl-4-hydroxybenzyl)ether, 4,4'-bis-2-methyl-6- tert-butylphenol, 4,4'-methylene-bis-2-methyl-6-tert-butylphenol, 3-tert-butyl-4-hydroxyanisole, 2,2'-methylene-bis-4-methyl-6-tert- butylphenol, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 4,4'-thio-bis-2-tert-butyl-6-methylphenol, 2,2'-thio-bis-4-methyl-6- tert-butylphenol, 2,2'-methylene-bis4-ethyl-6-tert-butylphenol, S,B-bis(2-hydroxy-3-tert-butyl-5-methoxyphenyl)propane. (2) Antioxidants of the amine type, such as: N,N'-di-sec-butyl-paraphenylenediamine, N,N'-diisopropylparaphenylene-diamine, N-phenyl-a-naphthylamine, phenothiazine, N-phenyl-S -naphthylamine, diphenylamine, ar-na f tylamine, 8,8-di-naphthylamine, tri-n-butylamine, octadecylamine, dodecylamine, 4,4'-methylene-bis-N-sec-butylaniline, 4,4<*- >methylene-bis-N,N-dimethylaniline. (3) Antioxidants of the mixed phenolamine type, such as N-n-butyl para-aminophenol, ortho-dimethylaminomethylphenol, 2,4,6-tris(dimethylaminomethyl)phenol.

Very satisfactory results can be obtained according to the invention by using one or more of the following compounds: 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, N,N'- di-sec-butyl-para-phenylenediamine. These 3 antioxidants are therefore preferred.

The preparation of the mixture of the metal deactivator and the antioxidant which, according to the invention, must be added to the hydrocarbon oil, can be carried out in different ways.

If the antioxidant is liquid at room temperature, a certain amount of the metal deactivator can be dissolved in it, and as much of this solution is added to the hydrocarbon as corresponds to the required concentration of the metal deactivator in the hydrocarbon oil.

The ratio between metal deactivator and antioxidant in the solution preferably corresponds to the ratio between metal deactivator and antioxidant selected for the hydrocarbon oil. If desired, a concentrate of the metal deactivator and the antioxidant can be prepared in a solvent and a certain amount of this concentrate can be added to the hydrocarbon oil to be stabilized.

If the antioxidant is a solid at room temperature, it can be melted and a certain amount of the metal deactivator can be absorbed into the melted antioxidant. On cooling, mostly mixed crystals are formed which are easily soluble in the hydrocarbon oil. In this case, it is also preferable that the composition of the melt corresponds to the required amount of antioxidant and metal deactivator in the hydrocarbon oil. A concentrate of the melt in a solvent can be prepared and this concentrate can be used to stabilize large quantities of hydrocarbon oils.

Another possibility for preparing mixtures of the metal deactivator and the antioxidant is to prepare a concentrated solution of the solid or liquid antioxidant in a solvent and in this concentrate the metal deactivator is absorbed, if necessary by heating. The concentrate thus obtained, in which both the antioxidant and the metal deactivator are present, can then be used for the stabilization of hydrocarbon oils.

Since the amounts of metal deactivator and antioxidant required to achieve the desired aging stability are quite small compared to the amount of the hydrocarbon oil to be stabilized, an embodiment of the method in which the mixture of metal deactivator and antioxidant is preferred in practice, also with a view to facilitating dosing is added to the hydrocarbon oil to be stabilized in the form of a concentrate in a solvent.

The solvent must be chosen so that its presence in the hydrocarbon oil to be stabilized does not cause disturbing side effects. A hydrocarbon fraction is preferred as a solvent, e.g. a hydrocarbon oil and more particularly the hydrocarbon oil to be stabilized with the concentrate.

The amounts of metal deactivator and antioxidant required

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added to the hydrocarbon oils to achieve the desired degree of stabilization can vary within very wide limits. These amounts depend on both the nature and activity of the antioxidant and the metal deactivator and the nature of the hydrocarbon oil and the manner in which it is prepared. To clarify this further, it must be

a few values that have proven to be suitable in real practice are

say. However, the invention is in no way limited to such amounts, as in the meantime much smaller amounts are sufficient

while in other cases a significantly larger quantity must be used

there than those mentioned here to achieve the desired degree of stabilization. The quantities are for the most part stated in ppm, i.e. parts by weight of the additive per 10^ parts by weight of hydrocarbon oil. Too easy-

for this reason, the hydrocarbon oils are classified as "relatively low-boiling", such as petrol, kerosene and gas oil, and "relatively high-boiling

de", such as transformer oil and lubricating oil.

With regard to antioxidants of the phenol type, it should be noted that the relatively low-boiling hydrocarbon oils are used in amounts of from 1 to 1000 ppm, particularly in amounts of from 10 to 200 ppm. In the relatively high-boiling hydrocarbon oils, these quantities are considerably larger, namely between 100 and 20,000 ppm, preferably in the range between 2,000 and 7,000 ppm.

When using the antioxidants of the amine type is for

mostly smaller amounts are sufficient than those required if a phenolic antioxidant is used.

For relatively low-boiling hydrocarbon oils, the required amount of amine type antioxidant is mostly between 1 and 250 ppm and preferably the range is between 10 and 100 ppn". For relatively high-boiling hydrocarbon oils, for the most part from 50 to 2000 ppm, in particular from 200 to 500 ppm, are used.

The antioxidants that contain both phenolic hydroxyl groups and amine groups and which are usually used exclusively

those in gasoline, are generally used in the same amounts as antioxidants

danter of the amine type.

With regard to metal deactivators, it should be noted that in relatively low-boiling hydrocarbon oils they are used in amounts of from 0.1 to 100 ppm, particularly in amounts of from 0.5 to 10 ppm. In relatively high-boiling hydrocarbon oils, these quantities are significant

equal greater, namely between 1 and 100 ppm, preferably in the range between 10 and 200 ppm.

The mixing problems that exist when adding the present metal deactivators in hydrocarbons are particularly relevant when large quantities of hydrocarbon oils are to be mixed with these metal deactivators, such as in refineries and mixing stations. In such places, there is usually equipment available for the mixing of relatively small amounts of these substances, such as e.g. antioxidants, with relatively large amounts of hydrocarbon oils.

Although the amounts of metal deactivator and phenolic and/or amine antioxidant that must be added to different hydrocarbon oils are different, nevertheless in principle a simple standard mixture is sufficient for the present invention. The amount of metal deactivator in this standard mixture must be chosen so that a hydrocarbon oil can be stabilized with the minimum amount of antioxidant required. This standard mixture can be mixed with hydrocarbon oil using the available equipment in the usual way. For stabilization of hydrocarbon oils where large amounts of the antioxidant are required, the excess amount of antioxidant, together with the standard mixture, can be mixed with the hydrocarbon oil using the available equipment.

The results are listed in the table below

of a number of experiments in which the solubilities of various metal deactivators in phenol-type and amine-type antioxidants were determined at room temperature.

The resulting mixtures dissolve easily in hydrocarbon oils. They prove to be excellently suitable for the production of concentrates in hydrocarbon oils, which concentrates served to stabilize larger amounts of hydrocarbon oils just before ageing. There were no dosing problems.

Claims (5)

1. Process for the production of hydrocarbon oils with improved aging stability, comprising the addition of one or more metal deactivators of the formula: where R means a heterocyclic radical containing the group - C = N - in a five- or six-membered ring, and Y means hydrogen or a cyclic or acyclic substituent, or the two Y-grup- per forms together with the group a cyclical stroke turn, to a hydrocarbon oil, characterized in that the metal deactivator is used in the form of a previously prepared mixture with one or more antioxidants of the phenol type and/or amine type. 2. Method as stated in claim 1, characterized in that 2,4-dimethyl-6-tert-butyl-phenol is used as antioxidant. 3. Method as stated in claim 1, characterized in that 2,6-di-tert-butyl-4-methyl-phenol is used as antioxidant. 4. Method as stated in claim 1, characterized in that N,N'-di-sec-butyl-paraphenylenediamine is used as antioxidant. 5. Means for carrying out the method according to claims 1 to 4, characterized in that it comprises a mixture of one or more metal deactivators with the formula: where R means a heterocyclic radical containing the group - C = N - in a five- or six-membered ring, and Y means hydrogen or a cyclic or acyclic substituent, or the two Y-grup- per forms together with the group = = a cyclic structure, with one or more antioxidants of the phenol type and/or amine type, optionally in the form of a concentrate in a solvent, preferably a hydrocarbon oil.