RU2302452C2 - Method of preparation of additive for lubricants - Google Patents

Abstract

FIELD: petroleum chemistry; sulfur-containing compounds of molybdenum used as additives for lubricants reducing the friction coefficient.

SUBSTANCE: proposed method includes addition of ammonium thiomolybdate into homogeneous mixture of ammonium thiomolybdate and first modifying agent at equimolar ratio in the five-fold amount relative to the initial amount; then, second modifying agent in aromatic hydrocarbon solvent is introduced into mixture and homogenized mixture is subjected to heat treatment by boiling. Used as solvent for homogenization of mixture with the first modifying agent is bipolar aprotic solvent selected from the following series: N, N-dimethyl formamide, N, N-dimethyl acetamide, N-methyl-2-pyrrolidone or their mixtures, or dimethyl sulfoxide. Used as solvent for homogenization of mixture with the second modifying agent is o-xylol, m-xylol, p-xylol or their mixtures. Boiling is carried out with back-flow condenser at temperature of 140-150°C for -12 h. For separation of target product, use is made of petroleum ether, pentane, xehane, heptane, isooctane or their mixtures. Use may be also made of synthesized salt of thiomolybdic acid obtained from ammonium molybdate and inorganic ammonium sulfide. Used as first modifying agent is tetraalkyl ammonium salts or mixture of salts of common formula R¹R²R³R⁴NX, where R¹, R², R³ and R⁴ are similar or different and are selected from the group including C₁-C₁₆ alkyl, X=Cl, Br. Used as second modifying agent are derivatives of succinimide of the following common formula:

where R⁵ is normal or branched alkyl or oligoalkylene at molecular mass of from 140 to approximately 1000; R⁶ is selected from group containing H, -C(=O)NH₂, -C(CH₂CH₂NH)_nCH₃; n= 1-4 or mixture of said succinimide derivatives.

EFFECT: increased content of molybdenum in final product; minimum friction coefficient at minimum amount of additive in lubricant.

6 cl, 3 tbl, 23 ex

Description

The invention relates to the field of petrochemistry, and more particularly to sulfur-containing compounds of molybdenum and their use as additives to lubricants that reduce the coefficient of friction.

It is well known that to save fuel consumption and to reduce wear of machine parts during friction, antifriction additives (friction modifiers) are introduced into lubricating oils. It is also known that, as friction modifiers, oil-soluble complex compounds of molybdenum are used, including sulfur, nitrogen or phosphorus atoms as ligands.

So, for example, in US patent [1] describes a method of obtaining additives to a lubricating oil based on tetraalkyl (alkenyl) ammonium thiomolybdate, which improves the antifriction properties of the oil. The disadvantages of the proposed method include the use of one of the starting components, namely tetraalkylammonium halides, as hydrocarbon radicals, rather inaccessible and expensive alkyl and alkenyl groups of vegetable oils and fats, for example cocoa or soybean oil.

A known method [2], in which additives to lubricating oils are obtained by the reaction of a sulfur-containing organic compound having a mobile hydrogen atom, with molybdenum pentachloride. The product isolated as a result of the reaction contained 3% molybdenum and about 1% chlorine, which is undesirable for environmental reasons and because of the possible corrosive activity of the product.

A molybdenum-containing oil additive exhibiting antifriction and antioxidant properties is obtained, as described in US Pat. - the reaction of the obtained product with sulfur or with a sulfur-containing compound. The disadvantages of the method include a rather complex synthesis route (multi-stage, the presence of an inert atmosphere, strictly limited temperature ranges).

Known methods [4.5], where oil additives are obtained on the basis of dithiocarbamine complexes of molybdenum. These additives have multifunctional (including antifriction) properties, but their synthesis is very complicated and involves the use of toxic reagents, such as carbon disulfide.

There is a method according to which an additive to oils is obtained on the basis of a mixture of a friction modifier (nitrogen or oxygen-containing organic compound) with a trinuclear sulfur-containing molybdenum complex, including dithiocarbamine groups as ligands [6]. The disadvantages of the method include the complex composition of the additive and multi-stage synthesis of the organomolybdenum compound.

A known method of obtaining and using as antifriction additives surface-modified nanoparticles of molybdenum trisulfide, according to which MoS ₃ nanoparticles are obtained in reversed microemulsions, stabilized surfactants and salts of molybdenum acid, the successive replacement of oxygen by sulfur in the molybdate anion, followed by acidification, surface modification and product isolation [7]. The disadvantage of this method is its low manufacturability associated with the use of highly diluted inverted microemulsions and, accordingly, large volumes of organic solvents.

The closest analogue of the claimed invention is a method for producing additives for lubricants based on chemically modified nanosized particles of molybdenum trisulfide and its derivatives [8], in which nanoparticles of molybdenum trisulfide and its derivatives are obtained from salts of thiomolybdenum acid of the general formula M ₂ MoS _4-x O _x where M = NH ₄ , Na, x = 0-3, or from a mixture of these salts of thiomolybdenum acid or from salts of molybdenum acid of the formula M ₂ MoO ₄ , where M = NH ₄ , Na and a sulfur donor, which is used as an inorganic sulfide Whether polysulfide of the general formula M _'2 S _n, where M' = NH _4, Na, n = 1-4, or thiourea in the presence of two modifiers, of which the first is used as tetraalkylammonium salts or mixtures of salts of general formula R ¹ R ² R ³ R ⁴ NX, where R ¹ , R ² , R ³ and R ⁴ , the same or different, are selected from the group consisting of C ₁ -C ₁₆ alkyl, X = Cl, Br, and as the second, succinimide derivatives of the general formula

where R ⁵ = straight or branched alkyl or oligoalkylene with a molecular weight of from 140 to about 1000, R ^{6 is} selected from the group consisting of H, -C (= O) NH ₂ , - (CH ₂ CH ₂ NH) CH ₃ , n = 1-4, or mixtures of the aforementioned succinimide derivatives, the process being carried out by heat treatment of a mixture of the thiomolybdenum acid salt and the first or second modifier homogenized in a polar solvent, cooling the resulting mixture, adding a second or first modifier, respectively.

The disadvantage of this method is the low content of molybdenum in the product, which is from 0.5 to 2.0 wt.%.

The objective of the invention is to develop a method that allows to increase the content of molybdenum in the final product and, as a result, to reduce the amount of additives to lubricants necessary to achieve the same effect as in the prototype.

This problem is solved by the fact that in the method for producing additives to lubricants by heat treatment of ammonium thiomolybdate homogenized in a polar solvent, the general formula (NH ₄ ) ₂ MoS _4-x O _x , where x = 0-3, or mixtures thereof using two modifiers the first of which is tetraalkylammonium salts or mixtures of salts of the general formula R ¹ R ² R ³ R ⁴ NX, where R ¹ , R ² , R ³ and R ⁴ , the same or different, are selected from the group consisting of C ₁ -C alkyl ₁₆ , X = Cl, Br; the second modifier is succinimide derivatives of the general formula O

where R ⁵ = straight or branched alkyl or oligoalkylene with a molecular weight of from 140 to about 1000, R ^{6 is} selected from the group consisting of H, -C (= O) NH ₂ , - (CH ₂ CH ₂ NH) _n CH ₃ , n = 1-4, or a mixture of the aforementioned succinimide derivatives, followed by isolation of the target product, in which, first, from a mixture of ammonium thiomolybdate and the first modifier, taken in an equimolar ratio, the tetraalkylammonium salt of ammonium thiomolybdate is obtained at room temperature, homogenized for 1-2 hours using a bipolar aprotic solvent selected of a number of:

N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or mixtures thereof, or dimethyl sulfoxide.

Then, ammonium thiomolybdate is added to the obtained product in a five-fold amount with stirring in relation to the initially taken one, stirring is continued for 1-2 hours, after which a second modifier in a solution of xylene (o-xylene, m-xylene, p-xylene) is introduced or mixtures thereof) and stirred for 30 minutes - 1 hour at 50 ° C.

The resulting product is subjected to boiling under reflux at a temperature of 140-150 ° C for 1-2 hours.

Synthesized ammonium thiomolybdate obtained from ammonium molybdate and inorganic ammonium sulfide can be used.

Then the solvents are removed in vacuo, a semi-solid residue, to isolate the target product, treated with a non-polar paraffin hydrocarbon solvent, which is used as petroleum ether, pentane, hexane, heptane, isooctane or mixtures thereof.

The resulting mixture was filtered through a blue ribbon filter to separate solid impurities and the solvent was removed in vacuo.

The target product is a dark brown viscous liquid that mixes easily with hydrocarbon and petroleum oils to form clear solutions or compositions having a red-brown to brown color. The molybdenum content in the product is 4-5 wt.%.

The following examples illustrate the present invention, but in no way limit its scope.

Example 1

In 5 ml of dimethylformamide, 0.13 g of ammonium tetratiomolybdate and 0.45 g of methyltrialkyl (C ₈ -C ₁₀ ) ammonium chloride (Adogen® 464) are homogenized for 1 h at room temperature.

To the obtained methyltrialkyl (C ₈ -C ₁₀ ) ammonium tetratiomolybdate, 0.65 g of ammonium tetratiomolybdate is added and homogenization is continued for 1 h, then a solution of 3.0 g of alkenyl succinimide in which R ⁶ is hydrogen is added to the product (designation in table 1 -II.1) in 5 ml of o-xylene and homogenization is continued for 1 h at 50 ° C. The resulting homogenized mixture was refluxed for 2.0-2.5 hours. The solvents were completely removed in vacuo, 70 ml of isooctane was added to the residue and stirred at room temperature for 15-20 minutes, after which it was filtered through a blue ribbon filter. The isooctane from the filtrate is removed in vacuo. The product yield is 78%.

The molybdenum content in the product is 5.05%.

Example 2

In 5 ml of dimethylformamide, 0.13 g of ammonium tetratiomolybdate and 0.45 g of tricaprylmethylammonium chloride (Aliquat® 336) were homogenized for 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 4.8%.

Example 3

In 5 ml of dimethylformamide, 0.13 g of ammonium tetratiomolybdate and 0.4 g of cetyltrimethylammonium bromide (CTAB) were homogenized for 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 4.3%.

Example 4

In 5 ml of dimethylformamide, 0.13 g of ammonium tetratiomolybdate, 0.22 g of Adogen and 0.22 g of cetyltrimethylammonium bromide are homogenized for 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 4.5%.

Example 5

In 5 ml of dimethylformamide, 0.13 g of ammonium tetratiomolybdate and 0.45 g of Adogen are homogenized for 1 h at room temperature.

Further, the product is obtained according to example 1, but instead of a solution of alkenylsuccinimide, a solution of the N-alkyleneamine derivative of alkenylsuccinimide is used, in which R ⁶ is a group - (CH ₂ CH ₂ NH) _n CH ₃ , n = 1-4, (the designation in Table 1- II.3).

The molybdenum content in the product is 4.75%.

Example 6

In 5 ml of dimethylformamide, 0.13 g of ammonium tetratiomolybdate and 0.45 g of Adogen are homogenized for 1 h at room temperature. Next, the product is obtained according to example 1, but instead of a solution of alkenylsuccinimide, a solution of an alkenylsuccinimide derivative of urea is used, in which R ₆ is a group -C (= O) NH ₂ (designation in table 1-II.2).

The molybdenum content in the product is 4.9%.

Example 7

In 5 ml of N, N-dimethylacetamide, 0.13 g of ammonium tetratiomolybdate and 0.45 Adogen are homogenized for 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 5.0%.

Example 8

In 5 ml of N-methyl-2-pyrrolidone, 0.13 g of ammonium tetratiomolybdate and 0.45 Adogen are homogenized for 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 4.8%.

Example 9

In 5 ml of dimethyl sulfoxide, 0.13 g of ammonium molybdate and 0.45 g of Adogen are homogenized for 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 4.3%.

Example 10

In a 10 ml mixture of dimethylformamide and N-methyl-2-pyrrolidone, 0.26 g of ammonium tetratiomolybdate and 0.9 g of Adogen are homogenized for 1 h at room temperature. To the resulting product, 1.3 g of ammonium tetratiomolybdate are added and homogenization is continued for 1 h, then a solution of 6.0 g of an alkenyl succinimide urea derivative (symbol II.2) in 10 ml of o-xylene is added to the product and homogenization is continued for 1 h at 50 ° C. The homogenized mixture was refluxed for 2.0-2.5 hours. The solvents were removed in vacuo.

The molybdenum content in the product is 4.3%.

Example 11

The production method according to example 1, characterized in that instead of o-xylene, m-xylene is used.

Example 12

The production method according to example 1, characterized in that instead of o-xylene, p-xylene is used.

Example 13

The production method according to example 1, characterized in that instead of o-xylene, a mixture of o-, m- and p-xylenes is used.

Example 14

The production method according to example 1, characterized in that instead of isooctane, petroleum ether is used.

Example 15

The production method according to example 1, characterized in that instead of isooctane, n-pentane is used.

Example 16

The production method according to example 1, characterized in that instead of isooctane, a mixture of pentanes is used.

Example 17. The production method according to example 1, characterized in that instead of isooctane using n-hexane.

Example 18

The production method according to example 1, characterized in that instead of isooctane, n-heptane is used.

Example 19

The production method according to example 1 is characterized in that instead of

dimethylformamide use a mixture of dimethylformamide and N, N-dimethylacetamide.

Example 20

The production method according to example 1, characterized in that instead of ammonium tetratiomolybdate, ammonium trithiomolybdate is used.

Example 21

The production method according to example 1, characterized in that instead of ammonium tetratiomolybdate, ammonium dithiomolybdate is used.

Example 22

The production method according to example 1, characterized in that instead of ammonium tetratiomolybdate, ammonium monothiomolybdate is used.

Example 23

The production method according to example 1, characterized in that ammonium tetratiomolybdate is obtained from 0.59 g of (NH ₄ ) ₂ MoO ₄ and 0.82 g of (NH ₂ ) ₂ S in an aqueous medium, it is isolated, dried and homogenized in 5 ml of dimethylformamide with 0.45 g Adogen 1 h at room temperature. Next, the product is obtained according to example 1.

The molybdenum content in the product is 4.6%.

All results are summarized in table 1.

Below are the characteristics of samples of antifriction additives based on surface-modified nanoparticles of molybdenum trisulfide obtained in examples 1-23 (table 2).

Table 1 Example No. Ammonium thiomolybdates of the general formula (NH ₄ ) ₂ MoS _4-x O _x , where x = 0-3 (amount, g) / solvent Quaternary ammonium salt (amount, g) Derivative of succinimide (amount, g) The synthesis temperature, ° C, one (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen® 464 (0.45) II.1 (3) twenty 144 2 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Aliquat® 336 (0.45) II.1 (3) twenty 144 3 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide CTAB (0.40) II.1 (3) twenty 144 four (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide CTAB: Adogen 1: 1 (0.45) II.1 (3) twenty 144 5 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen 1: 1 (0.45) II.3 (3) twenty 144 6 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.2 (3) twenty 144 7 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylacetamide Adogen (0.45) II.1 (3) twenty 144 8 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-methyl-2-vinylpyrrolidone Adogen (0.45) II.1 (3) twenty 144 9 (NH ₄ ) ₂ MoS ₄ (0.78) dimethyl sulfoxide Adogen (0.45) II.1 (3) twenty 144 10 (NH ₄ ) ₂ MoS ₄ (1.56) / N, N-dimethylformamide + N, N-dimethylacetamide Adogen (0.45) II.2 (3) twenty 144 eleven (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 13 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 140 13 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 139 fourteen (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 140 fifteen (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 140 16 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 17 (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 eighteen (NH ₄ ) ₂ MoS ₄ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 19 (NH ₄ ) ₂ MoS ₂ (0.78) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 twenty (NH ₄ ) ₂ MoOS ₃ (0.87) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 21 (NH ₄ ) ₂ MoO ₂ S ₂ (0.96) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 22 (NH ₄ ) ₂ MoO ₃ S (1.05) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144 23 NH ₄ ) ₂ MoO ₄ (0.59) (NH ₄ ) ₂ S (0.82) / N, N-dimethylformamide Adogen (0.45) II.1 (3) twenty 144

table 2 Sample No. Yield,% mass. The concentration of molybdenum,% mass. The ratio of Mo: S. mol / mol The average particle size, And O-1 78.1 5.05 1: 2.5 27.3 O-2 74.3 4.80 1: 2.7 32,4 O-3 72.0 4.30 1: 3.1 28.1 O-4 74.0 4,50 1: 2,8 28,4 O-5 76,4 4.75 1: 2.9 26.7 O-6 79.8 4.90 1: 2.7 33.3 O-7 71.8 5.00 1: 2.9 30.5 O-8 72,2 4.80 1: 2.6 29.0 O-9 36.8 4.30 1: 2.5 29.6 O-10 79.5 430 1: 3,2 28.9 O-11 79.6 4.35 1: 2.7 29.4 O-12 73.1 4,55 1: 2.7 27.9 O-13 78.8 4.67 1: 2.5 26.9 O-14 70.9 4.76 1: 2,8 26.8 O-15 79.6 4.47 1: 2.1 24.7 O-16 75.8 4.29 1: 1.8 31,4 O-17 74.7 4.72 1: 1,1 34.3 O-18 71.5 4.45 1: 2,3 28.1 O-19 75.9 4,56 1: 2.6 28,2 O-20 70.5 4.47 1: 2.7 27,2 O-21 77.0 4.39 1: 3.0 26.7 O-22 70.6 4.21 1: 3.1 29.6 O-23 68.1 4.6 1: 2.1 24.8 Comparison with prototype 87.1 1.8 1: 2,3 28.0

The tribological properties of the obtained antifriction additives based on surface-modified molybdenum trisulfide nanoparticles were studied for their compositions in T46 turbine oil using an SRV vibrotribometer (Optimol, Germany). Test conditions: ball-plane friction pair; oscillation amplitude 1 mm, frequency 50 Hz; the axial load varies from 20 to 600 N in steps, for 1 min each platform, in increments of 50 H. The value of the coefficient of friction is measured, the test is considered completed if the value of the coefficient of friction exceeds 0.22, or if scoring occurs (automatic stop).

Oil compositions were prepared by mixing T46 with 1.5 wt.% Samples O-1 - O-23. As a comparison sample, surface-modified molybdenum trisulfide nanoparticles obtained in accordance with [8] (sample [MoS _x ]) at a concentration of 5% and molybdenum dithiocarbamate of formula III are used. The samples used for comparison have a molybdenum concentration close to samples O-1 - O-23.

Below are tribological test data for some samples.

Table Sample No. The amount of additive, wt.% In oil, The number of Mo in oil, parts per million Minimum coefficient of friction Critical load, N O-1 1,5 757 0,065 No O-5 1,5 712 0,065 No O-6 1,5 735 0,065 No O-17 1,5 708 0,065 600 O-19 684 0,066 No Comparative Sample [MoSx] 5,0 670 0,065 No Dithiocarbamate Mo III 1000 0,067 550

The tribological test data presented in the table allow us to conclude that to achieve the same effect, namely to achieve a minimum coefficient of friction of 0.065, a significantly lower amount of additive in oil is required than in a comparative sample (according to the prototype).

Thus, a method has been developed that allows to increase the molybdenum content in the final product and as a result to reduce the amount of additives to lubricants, necessary to achieve the same effect as in the prototype, more than three times.

Information sources

1. Pat. U.S. N 4400282 (08.23.1983).

2. Pat. U.S. N 4474673 (10/02/1984).

3. Pat. U.S. N 4765918 (08.23.1988).

4. Pat. U.S. N 6117826 (09/12/2000).

5. Pat. U.S. N 6245725 (06/12/2001).

6. Pat. Great Britain N 2359092 (08/15/2001).

7. Application WO 0194504 (05/08/2001).

8. Application WO 2004/037957 A1 (May 6, 2004).

Claims (6)

1. The method of obtaining additives for lubricants by heat treatment of homogenized in a polar solvent ammonium thiolybdate of the general formula (NH ₄ ) ₂ MoS _4-x O _x , where x = 0-3, or mixtures thereof using two modifiers, the first of which is are tetraalkylammonium salts or mixtures of salts of the general formula R ¹ R ² R ³ R ⁴ NX, where R ¹ , R ² , R ³ and R ⁴ , the same or different, are selected from the group consisting of alkyl C ₁ -C ₁₆ , X = Cl , Br, the second modifier is succinimide derivatives of the general formula

where R ⁵ is a straight or branched alkyl or oligoalkylene with a molecular weight of from 140 to about 1000, R ^{6 is} selected from the group consisting of H, -C (= O) NH ₂ , - (CH ₂ CH ₂ NH) _n CH ₃ , n = 1-4, or a mixture of the aforementioned succinimide derivatives, followed by isolation of the target product, characterized in that in a homogeneous mixture of ammonium thiomolybdate and the first modifier, taken in an equimolar ratio, ammonium thiomolybdate is added with stirring in a five-fold amount to that taken initially, with subsequent introduction into the mixture of the second modifier in aromatic hydrocarbon solvent; homogenizing the mixture; and heat treating the homogenized mixture by boiling. 2. The method according to claim 1, characterized in that the salts of thiomolybdic acid obtained from ammonium molybdate and inorganic ammonium sulfide are used. 3. The method according to claim 1, characterized in that the boiling is carried out under reflux at a temperature of 140-150 ° C for 1-2 hours 4. The method according to claim 1, characterized in that a bipolar aprotic solvent from the series: N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone or mixtures thereof is used as a solvent for homogenizing the mixture with the first modifier or dimethyl sulfoxide. 5. The method according to claim 1, characterized in that an aromatic hydrocarbon solvent from the series o-xylene, m-xylene, p-xylene or mixtures thereof is used as a solvent for homogenizing the mixture with the second modifier. 6. The method according to claim 1, characterized in that for the isolation of the target product, a non-polar paraffin hydrocarbon solvent is used from the series: petroleum ether, pentane, hexane, heptane, isooctane or mixtures thereof.