CS275637B6 - Medium boiling fuel oil - Google Patents

Abstract

Distillate fuels, particularly those having a relatively high final boiling point, are significantly improved in their flow and filterability properties utilising a two component additive consisting of 25 to 95 wt.% preferably 50 to 90 wt.% of C30-C300 oil-soluble nitrogen compound being an amide or amine salt of an aromatic or cycloaliphatic carboxylic acid and 75 to 5 wt.% preferably 10 to 50 wt.% of a certain category of ethylene-vinyl acetate copolymers.

Description

BACKGROUND OF THE INVENTION The present invention relates to an additivated medium boiling oil (boiling point 120-500 ° C) derived from petroleum containing paraffin and exhibiting improved flow properties and filterability by admixing a combination of a paraffin crystal growth inhibitor and a special ethylene vinyl acetate copolymer.

Various additives are known in the art to improve the flow properties of medium-boiling petroleum fuel oils. Combinations of additives which, on the one hand, cause nucleation of paraffin (paraffin wax) and / or stimulate paraffin crystal growth and, on the other hand, inhibit paraffin crystal growth, are well known and are described, for example, in U.S. Patent 3,961,916. The patent discloses a mixture of additives comprising a copolymer of ethylene with alkyl esters of ethylenically unsaturated monocarboxylic or dlcarboxylic acid or with a vinyl ester of a saturated fatty acid of 1 to 17 carbon atoms.

Nitrogen-containing additive systems in the form of amides or amide salts, also used in the present invention, are described in U.S. Patent No. 4,211,534. This patent discloses a three-component flow additive composition comprising a polymer or copolymer of ethylene, a second a polymer of an oil-soluble ester and / or olefin having 3 or more carbon atoms and, as a third component, a nitrogen-containing compound. This ternary system should be preferable to mixtures containing any two of the three components of the additive to improve the cold flow properties of fuel oils.

U.S. Pat. No. 3,982,909 discloses an additive system comprising amides, diamides and anionic salts alone or in admixture with certain hydrocarbons such as microcrystalline paraffins or vaseline and / or a polymer additive with a polyethylene backbone to lower the temperature, solidification. This additive system is suitable for improving the flow properties of medium-boiling petroleum fuel oils.

Oil-soluble nitrogen-containing succinic acid derivatives are disclosed in U.S. Pat. No. 4,147,520. This patent discloses the use of these compounds in admixture with an ethylene vinyl acetate copolymer as a paraffin nucleator.

The invention is based on the discovery that a two-component additive system containing mainly a particular amine derivative in admixture with a particular ethylene vinyl acetate copolymer is highly effective even in relatively small amounts to improve flow properties and filterability of medium boiling petroleum fuel oils below their cloud point.

SUMMARY OF THE INVENTION The present invention relates to a boiling oil of medium boiling point oil having a boiling point of from 120 to 500, containing paraffin, with improved flow properties at low temperatures, characterized in that it contains 0.005 to 0.5% by weight, preferably 0.005 to 0%. A 25% blend additive for improving flow properties and filterability comprising 25 to 95% by weight of a paraffin wax crystal growth inhibitor which is an oil-soluble nitrogen compound containing 30 to 300 carbon atoms and having at least two straight C 14 to C 24 alkyl chains, consisting of the reaction product of a secondary amine derived from tallow hydrogenated fatty acids and an aromatic or cycloaliphatic polycarboxylic acid or its anhydride and 75 to 5% by weight of ethylene-vinyl acetate copolymer containing 10 to 40% by weight of vinyl acetate and having a number average molecular weight of 1 000 to 30 000 and a degree of branching in the range of from 1 to 20 methyl-terminated side-chain alkyl chains not from vinyl acetate per 100 methylenes, as determined by 1 H NMR spectroscopy.

The additive system described above is suitable for a wide range of petroleum distillation fractions having a boiling point of 120-500 ° C (ASTM 01160) and is particularly suitable for fuel oils boiling in the range of 150-400 ° C. It is particularly suitable for fuel oils with a relatively high end boiling point, for example above 360 ° C.

Such fuels have been used more and more recently, and these fuels usually contain longer-chain n-paraffins and have higher cloud temperatures. In general, the flow properties of these fuels are more difficult to adjust with conventional additives. The most common petroleum fuel oils are kerosene, jet fuels, diesel and fuel oils.

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The nitrogen-containing paraffin crystal growth inhibitors used according to the invention are nitrogen compounds having a total carbon number of 30 to 300, preferably a total carbon number of 50 to 150, which are oil-soluble salts and amides derived from the above-defined secondary amines, usually prepared by reacting at least one molar part of an aromatic or cycloaliphatic polycarboxylic acid, for example an acid having 2-4 carboxylic groups, preferably a dicarboxylic acid or its anhydride.

Secondary amines derived from hydrogenated tallow fatty acid can be characterized by the general formula HNR ₁ R ₂ wherein

R 1 and R ₂ are alkyl groups derived from tallow fatty acids and contain ^{4% C 1-4} alkyl groups, 31% alkyl groups and 59% C 1-6 alkyl groups.

Examples of suitable aromatic and cycloaliphatic polycarboxylic acids (and their anhydrides) include cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, naphthalenedicarboxylic acid, and the like. Generally, these acids have 5 to 13 carbon atoms in the cyclic moiety; Preferred acids of the invention are benzenedicarboxylic acids such as phthalic acid, tetraftalic acid and isophthalic acid. Isophthalic acid and its anhydride are particularly preferred.

Preferably, the nitrogen compound contains at least 3 alkyl chains each containing 14 to 24 carbon atoms, most preferably at least two of these chains are normal. The molecule should also contain at least one ammonium salt, amine or amide bond group. A particularly preferred nitrogenous compound is an amine salt also containing an amido group, prepared by reacting one molar part of phthalic anhydride with two non-molar parts of a diamine derived from hydrogenated tallow fatty acids. Another preferred nitrogen compound is the dianiide formed by dehydrating the amide-amine salt.

Both the type of nitrogen compound used and the type of ethylene-vinyl acetate copolymer are important to obtain an effective two-component additive system according to the invention. The additive concentrate of the invention more effectively improves the flow properties of medium-boiling oils than the ternary systems of the US patent. No. 4,211,534, which are used for treatment at high concentration ratios. It has been found that it is not necessary to use third components for many fuel oils, which is associated with increased costs.

The nitrogen compounds used according to the invention are believed to be highly effective inhibitors of paraffin crystal growth. When the fuel oil cools, normal alkanes of about 14 to 32 carbon atoms generally crystallize, the longer-chain alkanes crystallizing first. In the crystallized n-alkanes, alkanes containing approximately 20 to 22 carbon atoms are usually most represented. Nitrogen compounds are highly effective in controlling the growth of a major proportion of paraffin, but are slightly less effective in controlling the initial stages of paraffin precipitation.

Although the optimum properties of the polymer depend on the particular fuel used, it can be stated that the ethylene vinyl acetate copolymer should contain 10 to 40% by weight and preferably 10 to 35% and especially 10 to 20% vinyl acetate; it should have a number average molecular weight, determined on the basis of an osmometric measurement in the vapor phase, of 1 000 to 30 000, preferably 1 500 to 7 000 and in particular 2 500 to 5 500 and a degree of branching 1 to 20, preferably 2 to 12. means the number of methyl groups other than vinyl acetate per polymer molecule per 100 methylene groups by proton nuclear magnetic resonance spectroscopy, such as using a Perkin-Elmer R-34 spectrometer and a 20¾ mass solution of the polymer in orthodichlorobenzene at 100 ° C; at 220 MHz using a continuous wave.

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The degree of branching of the polymer may vary within said limits; however, it has been found that the most important characteristic of the copolymer is its vinyl acetate content. It has been found that the use of ethylene vinyl acetate copolymers of different solubility or copolymers of different structure and especially containing vinyl acetate groups outside the claimed range can cause the additive to adversely affect flow properties and filterability.

It has also been found that the ratio of nitrogen-containing compound to ethylene-vinyl acetate copolymers to each other is important in order to achieve improved flow properties and filterability. It has been found that with respect to the total weight of the fuel additive combination, at least 25% by weight and preferably at least 50% by weight of the nitrogen-containing compound is present. Preferably, the content of nitrogen compound in the combination of additives is preferably from 25 to 95%, preferably from 50 to 95%, more preferably from 60 to 90%, and in particular from 60 to 80%, the remainder being ethylene vinyl acetate copolymer.

The properties of the fuel oils of the invention are illustrated in the following examples. The examples do not limit the invention in any way. Oils are by weight unless otherwise indicated.

The influence of the additive system on the behavior of fuel oils in the 00T (Flow Improved Distillate Operability Test) test, a slow cooling test simulating the condition that occurs when pumping stored fuel oil, is tested. The cold flow properties of the following additive fuel oils are determined in this test as follows: 300 ml of fuel oil is cooled linearly by 1 ° C / h to the test temperature and the temperature is then kept constant. After two hours at the test temperature, approximately 20 ml of the coating is aspirated to prevent the test from being affected by abnormally large paraffin crystals formed during cooling at the oil / air interface. The paraffin deposited in the flask is dispersed by gentle mixing and a combined filter for cold filter plugging point test (CFPPT - see below) is inserted. A vacuum of 3 kPa is applied and 200 ml of fuel oil is passed through the filter into a graduated vessel. Satisfactory means that 200 ml of fuel oil passes through the sieve within 10 seconds and does not mean that the passage rate of the filter is too slow because the filter is clogged.

For the cold filter clogging test, a device shall be used containing a filter with a sieve of 0,850, 0,600, 0,425, 0,250, 0,100, 0,150, 0,125, 0,111, 0,075, 0,058, and 0,043 mm (20, 30, 40, 60, 80, 100) , 120, 150, 200, 250, and 350 mesh). The smaller the paraffin crystals and thus the lower the mesh diameter of the sieve through which the paraffin-containing fuel passes, the greater the efficiency of the additive to improve flow properties.

It should be noted that two fuels will never give exactly the same test results at the same level of additivation by the same additive to improve flow properties and that, therefore, the actual level of additive will vary somewhat depending on the fuels used.

Nitrogen compound A is understood to mean a compound containing both amide and dialkylammonium groups, formed by the reaction product of 1 mole phthalic anhydride with 2 mole parts of a tallow hydrogenated secondary amine, the n-alkyl groups of which contain 4% C, 31% and 59%. % C ₄ θ groups.

By EVA polymer 1 is meant an ethylene vinyl acetate copolymer having a number average molecular weight of 3,400, the number average molecular weight being determined eighth in the vapor phase. The copolymer contains 17.0% by weight of vinyl acetate and has a branching degree of 8.0, i.e., it comprises 8 methyl-terminated side-chain alkyl chains not originating from vinyl acetate per 100 methylene groups.

The fuel oils used have the following characteristics:

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ASTM D 86 distillation boiling point (° C) Haze temperature ° C Temperature at which paraffin ° C appears fuel beginning 20% 90% end 1 182 220 354 385 + 1 - 2,5 2 180 226 341 368 - 3,5 - 5,5 3 188 238 344 375 - 1 - 4,5

Example 1

The DOT test is carried out on fuel oil additive with an additive concentrate containing 75% by weight of nitrogenous compound A and 25% of EVA polymer 1. The following results were obtained at -12 ° C:

Concentration in Passing the smallest sieve fuel oil mesh diameter in mm (mesh) PPm 100 ALIGN! 0.180 (80) 150 0.043 (350) 200 0.043 (350)

Example 2

The test of Example 1 is repeated, but fuel oil 2 is used:

Concentration in fuel oil ppm Passage through the smallest mesh diameter in mm (mesh) 50 0.425 (40) 150 0.075 (200) 200 0.058 (250)

Example 3 (comparative)

For the purposes of comparison,. the test of Example 1 is carried out with a conventional additive to improve flow properties of U.S. Pat. No. 4,211,534. The additive comprises a 75% crystal growth retardant and a 25% nucleator, both of which are based on an ethylene vinyl acetate polymer referred to as polymer 15.

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Concentration in fuel oil ppm Passage through the smallest mesh diameter in mm (mesh) fuel 1 fuel 2 100 ALIGN! 0.425 (40) 0.600 (30) 150 0.150 (100) 0.425 (40) 200 0.125 (120) 0.180 (80)

Example 4

a) Repeat the test of Example 2 with fuel oil using an additive concentrate containing 100 parts nitrogen compound A and 25 parts EVA polymer 1. 125 ppm of the additive is added to the fuel oil and the fuel oil passes the smallest mesh size test 74 micrometers (200 mesh).

(b) The test of (a) is repeated, but in addition to the concentrate of (a), 25 parts of an ethylene-vinyl acetate copolymer having an average molecular weight of 2,000 and a vinyl acetate content of 36% are added so that the additive concentrate The oil passes the 120 mesh screen of the smallest mesh diameter, thus achieving less favorable results than with the additive concentrate of the invention.

Example 5

The DOT test of Example 1 was repeated with fuel oil 3. The tests were carried out at -12 ° C with the addition of 100 ppm of an additive consisting of 75 ppm of the nitrogenous compound A of Example 1 and 25 ppm of the various vinyl acetate copolymers (EVA) below. The results are shown in Table I. This example illustrates the importance of using a particular group of ethylene vinyl acetate copolymers of the invention.

Table I

Polymer Content of vinyl acetate (¾ wt.) Numeric Medium molecular mass Branching ^x The oil complies with the screen test; with the smallest mesh diameter in / µm (mesh) 2 13.5 2 750 9.1 180 (79) 3 15.8 5 500 7.6 150 (99) 4 17.0 3 400 8.0 111 (150) 5 27.6 6 250 5.6 150 (99) 6 29.4 3 050 9.1 250 (59) 7 33.0 5 000 io; o 250 (59) 8 36.0 2 000 4.0 250 (59)

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By branching is meant the number of methyl groups excluding vinyl acetate methyl groups as measured by nuclear megnatic resonance spectroscopy. All spectra were measured on a Perkin-Elmer R-34 spectrometer using a 20% by weight solution of the polymer in orthodichlorobenzene at 100 ° C at 200 MHz.

Example 6

The efficacy of the mixed additive containing 3 parts by weight of nitrogenous compound A and 1 part by weight of EVA polymer 1 is compared at different concentrations of the additive with

I with polymer 15 -B

II EVA polymer 1 -C

III of EVA polymer 8 according to Table I-D

The DOR test results at -12 ° C for Fuel 1 are shown in the graph of Figure 1; curve A corresponds to the blend of the present invention, curve 15 corresponds to curve 15 of polymer 15, curve C to curve E and curve 8 to curve E from curve E to curve 8 to curve E. hole sizes are given in the BOT test description.

Examples 7 and 8

For comparison, the test of Example 6 is repeated for fuel 2 and fuel 3, and the results are shown in Figures 2 and 3. The meaning of the individual curves and the values plotted on the x and y axes are the same as in Figure 1.

Example 9

Mixtures of varying proportions of nitrogenous compound A and EVA polymer 1 were prepared and tested in fuel 1 (DOT test) at -12 ° C using 200 and 125 ppm blended fuel additives. The results are compared with a similar blend additive but containing the EVA polymer 8 according to Table 8. The results are shown in Fig. 4, with the upper curves for the additive amount 200 ppm and the lower curves for the additive amount 125 ppm. The curve E always corresponds to the composition of the additive according to the invention, the curve F to the composition of the additive comprising EVA polymer 8 according to Table I instead of EVA polymer 1. The x-axis Mesh.

Examples 10 and 11

The test of Example 9 is repeated, but instead of fuel 1, fuel 2 and 3 are used and the results are shown in Figures 5 and 6.

In the following Examples 12-16, the response of the oil to the ingredients is measured by a cold filter plugging temperature test (CFPPT test) conducted in a manner detailed in the Journal of the Institute of Petroleum, Volume 52, Issue 510, June 1966, p. 173 This test is intended to mimic the flow of cold diesel fuel (medium boiling petroleum distillate) at pumping.

The test is performed as follows:

40 ml sample of the oil is cooled in a bath which is maintained at about -34 C for ^q nalineárního cooling at about 1 ° C / min. Periodically, at any one-stage temperature drop from at least 2 ° C above the turbidity of the oil, the ability of the cooled oil to flow through the fine sieve over a prescribed period of time is tested using a test device which is a pipette to the underside of which is inverted. the surface of the oil to be tested. A 350 mesh sieve (mesh size approximately 43 microns) with an area defined by a diameter of 12 mm is stretched across the funnel orifice. In the test, a vacuum source is always connected to the upper end of the pipette and sucked through a sieve into the pipette up to the mark indicating 20 ml of oil. After each successful passage, the oil immediately returns to

EN 275637 B 6 the test vessel. The test is repeated with each 1 drop in temperature of ^{the case} C, until the oil fails to fill the pipette within 60 seconds. This temperature is referred to as the cold filter clogging temperature. The difference between the cold filter clogging temperature of the additive-free fuel and the same fuel containing the additive is reported as the CFPP reduction - the cold filter clogging temperature caused by the test additive. More efficient cold flow enhancing additives have a greater CFPP reduction value at the same additive concentration.

Example 12

The cold filter clogging temperature (CFPP) of the various fuels containing the following additives is measured and recorded in the graph of Figure 7.

Ingredient The curve in the graph in Fig. 7 AND) nitrogenous compound A 0 II) EVA polymer 8 according to Table I H III) EVA polymer 1 AND IV) Polymer 15 3 IN) 3 parts nitrogen compound 1 part EVA polymer 1 TO

Fig. 7 shows the concentration of the additive in ppm of the active substance on the x-axis and the cold filter clogging temperature in ° C (Δ CFPP) on the y-axis.

Examples 13 and 14

The test of Example 12 was repeated but fuel 2 and 3 were used instead of fuel 1. The results are shown in Figures 8 and 9, where the same values are plotted on both axes as in Figure 7.

Example 15

The cold filter clogging temperature for fuel 1 is measured, containing 50 ppm and 100 ppm of a mixture of different proportions of nitrogenous compound A and EVA polymer 1; the results are plotted in FIG.

10. On the x-axis, the upper percent values of the EVA copolymer 1 and the lower percentages of the percentage of nitrogenous compound A. On the y-axis are the cold filter clogging temperature values in ° C (Δ CFPP).

Example 16 ·

The test of Example 15 is repeated but fuel 2 and 3 are used instead of fuel 1. The results are shown in Figures 11 and 12, where the x and y axes are the same as those in Figure 10.

Example 17

Mixtures according to the invention are evaluated in fuels 4 and 5 having the following characteristics:

fuel 4 fuel 5 Λ5ΤΜ turbidity temperature, ° C -15 . -10 rotation temperature, ° C -21.5 -24 paraffin discovery temperature, ° C -17.5 -15

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^Ί a, fuel 4 fuel 5 Distillation (boiling point ° C) initial boiling point 179 150 10% 215 203 20% 230 225 50% 263 269 90% 314 320 boiling point 345 (98.2%) 347 rest% 1 1.1

The performance of additives shall be evaluated by a test developed for low temperature diesel fuel properties at which the fuel sample is brought to the test temperature by cooling at 1,1 ° C per hour and tested for filterability at an appropriate temperature by determining whether the fuel passes through a 350 mesh screen 43 microns) under a vacuum of 20 kPa for 60 seconds. If this happens, the fuel is considered satisfactory.

T a b u-1 k and II

polymer molecular weight determined by soniometry in the vapor phase vinyl acetate (%) methyl branching 9 5 600 36.2 8.5 10 5 000 17.0 7.5 11 3 050 29.4 9.1 12 2 775 17.1 6.2 13 2 000 36.0 4.0 14 1 950 29.1 4.6

Mixtures of nitrogen compounds A with varying amounts of ethylene vinyl acetate copolymers 9 to 14 are tested in fuels 4 and 5, with the necessary additive being recorded in Figures 13 and 14 to classify the fuel as satisfactory. The lower amount of additive demonstrates better additive efficiency.

The curve numbers correspond to the number of ethylene vinyl acetate copolymers according to Table II.

The x-axis indicates the percentage of nitrogen compound A in the top row and the EVA copolymer percentage in the lower row. The y-axis indicates the additive amounts in ppm.

Example 18

In this example, fuel 7 is used which has the following characteristics: cloud point, ° C -2 paraffin discovery temperature, ° C -6 ASTM distillation, (boiling point, ° C)

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initial boiling point 164 20 May % 212 50 0, 0 262 90 0, O 333 boiling point 370 aromatic content,% vol. 2B

Two tanks of 3 fuel 7 are cooled under ambient conditions to a temperature of -14 ° C and, after temperature equalization, are tested for 300 ml of the fuel sample by the DOT cold flow test. The tanks are then slowly heated to a temperature above the paraffin discovery temperature in the fuel and then cooled again at a rate of 0.5 ° C / h to -14 ° C. The fuel is then pumped from the tanks through a set of filter screens to determine the finest screen through which the paraffin fuel passes.

The fuel in one tank contains 135 ppm of polymer 15 and passes only through a 30 mesh sieve, while the fuel in the second tank contains 135 ppm of a mixture of 4 parts nitrogen compound Λ and 1 part EVA polymer 1 passes through a 100 mesh screen ( mesh size 150 microns).

Example 19

In this example, the test results are shown using four 25 m ¹ tanks filled with fuel 7 which are tested side by side. During three days of storage at natural low temperatures (including natural cyclic temperature variation), fuel is pumped at -14 ° C from fuel tanks as at the sale of fuel, and the finest screen through which the fuel passes is recorded. The results are as follows:

amount of ingredient ppm Ingredient passing through the finest sieve Mesh eye diameter (/ Uni) 70 polymer 15 30 495 70 4 parts nitrogenous compound 1 part EVA polymer 1 40 420 135 polymer 15 30 495 ¹³⁵ 4 parts nitrogenous compound 1 parts of EVA polymer 1 100 ALIGN! 147

PATENT CLAIMS

Claims (9)

PATENT CLAIMS Medium boiling oil produced by distillation of petroleum with a boiling point of from 120 to 500, containing paraffin, with improved flow properties at low temperatures, characterized in that it contains 0.005 to 0.5% by weight, preferably 0.005 to 0, A 25% blend additive for improving flow properties and filterability, comprising 25 to 95% by weight of a paraffin wax crystal growth inhibitor which is an oil-soluble nitrogen compound of 30 to 300 carbon atoms and having at least two straight C 14 to C 24 alkyl chains the reaction product of a secondary amine derived from hydrogenated tallow fatty acids and aromatic or cycloaliphatic Of polycarboxylic acid or its anhydride and 75 to 5% by weight of ethylene-vinyl acetate copolymer containing 10 to 40% by weight of vinyl acetate and having a number average molecular weight of 1,000 to 30,000 and a degree of branching ranging from 1 to 20 side alkyls of methyl-terminated non-vinyl acetate per 100 methylene groups as determined by 1 H NMR spectroscopy. 2. A medium-boiling fuel oil according to claim 1, wherein the additive comprises 50 to 90% by weight paraffin crystal growth inhibitor and 50 to 10% by weight ethylene vinyl acetate copolymer. 3. A medium-boiling fuel oil according to claim 1 or 2, wherein the oil-soluble nitrogen compound contains 50 to 150 carbon atoms. 4. The medium-boiling fuel oil of claims 1 to 3, wherein the oil-soluble nitrogen compound contains at least three alkyl chains of 14 to 24 carbon atoms. A medium-boiling fuel oil according to Claims 1 to 4, characterized in that the aromatic polycarboxylic acid is phthalic acid or its anhydride. 6. A medium-boiling fuel oil according to any one of claims 1 to 5, wherein the oil-soluble nitrogen compound is a product comprising both amide groups and amine salt groups obtainable by reacting one molar part of phthalic anhydride and two molar parts of a secondary amine derived from hydrogenated fatty acids. tallow. 7. The medium-boiling fuel oil of claims 1 to 6, wherein the additive comprises from about 60% to about 80% by weight of the oil-soluble nitrogen compound. 8. The medium-boiling fuel oil of claim 1, wherein the ethylene vinyl acetate copolymer has a branching degree of 2 to 12. 9. A medium-boiling fuel oil according to claim 1, comprising from 0.005 to 0.5% by weight of a blend to improve flow properties and filterability, comprising from 50% to 90% of an oil-soluble nitrogen compound containing by weight of the blend. 30 to 300 carbon atoms and having at least two straight C 14 to C 24 alkyl chains consisting of the reaction product of a secondary amine derived from a tallow hydrogenated fatty acid and an aromatic or cycloaliphatic mono and di-carboxylic acid or its anhydride and 10 to 50% by weight of a copolymer ethylene-vinyl acetate, which contains 10 to 35% by weight of vinyl acetate, has a number average molecular weight of 1,000 to 30,000 and a degree of branching in the range of from 2 to 10 side methyl-terminated alkyl chains other than vinyl acetate per 100 methylene groups.