JPH0258318B2 - - 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

[Detailed description of the invention]

FIELD OF THE INVENTION This invention relates to fuel oils containing certain additive mixtures to improve the flow and filtration properties of distillate fuel oils at low temperatures and to additive concentrates for addition into the fuel oils. In particular, the present invention relates to additive systems containing a nitrogen-containing wax crystal growth inhibitor and a special category of ethylene-vinyl acetate copolymers. Various additives have been disclosed in the prior art to improve the flow properties of middle distillate fuel oils. Combinations of additives that act both as wax nucleators and/or wax crystal growth stimulators and as wax growth inhibitors are known and are described, for example, in Ilnyckyl et al., June 8, 1976. Described in issued U.S. Patent No. 3,961,916,
This US patent describes an additive combination consisting of ethylenically unsaturated mono- or dicarboxylic acid alkyl esters or vinyl esters of _C1 - _C17 saturated fatty acids and copolymerized ethylene. Additive systems containing nitrogen-containing amides or amine salts as used in the present invention are described in U.S. Pat. No. 4,211,534 to Feldman, issued July 8, 1980; A ternary combination flow improver additive is described consisting of an ethylene polymer or copolymer, a second polymer of an oil-soluble ester and/or a _C3 or higher olefin polymer, and a nitrogen-containing compound as a third component. This three-component system is stated to be advantageous over combinations of any two additive components for improving the cold flow properties of distillate fuels. U.S. Pat. No. 3,982,909, issued September 28, 1976 to Hollyday, discloses that amide, diamide and ammonium salts alone or certain hydrocarbons such as microcrystalline waxes or petrolatum and/or ethylene-based Additive systems consisting of amide, diamide and ammonium salts in combination with chain polymer pour point depressants and the combination are described as being useful as flow improvers for middle distillate fuels. Nitrogen-containing oil-soluble succinic acid or derivatives thereof are described in U.S. Pat. The above substances combined are listed. The present invention utilizes a secondary amine containing a 1 molar proportion of an aromatic cyclic anhydride and a C _14-18 linear alkyl group in combination with certain ethylene vinyl acetate copolymers.
A two-component additive system consisting essentially of condensation products with molar proportions has been shown to be extremely effective in improving the flow and excess properties of below-cloud point middle distillate fuels at relatively low treatment concentrations. It is based on discovery. In accordance with the present invention, essentially (a) 1 molar proportion of aromatic cyclic anhydride and 2 molar proportions of secondary amine containing C _14-18 linear alkyl groups, based on the total weight of the flow improver; (b) an amount in the range of about 25-95%, preferably 50-90% by weight of the condensation product; (b) a vinyl acetate content of about 10-40%, preferably 10-35% by weight; ,for example,
A number average molecular weight (Mn) of 1500-7000, preferably 1500-5500 and a degree of branching in the range of about 2-12 alkyl groups per 100 methylene groups as determined by nuclear magnetic resonance ( ^1H NMR) spectroscopy. 75-5%, preferably 50-10% by weight of the ethylene-vinyl acetate copolymer with the addition of 0.005-0.5%, preferably 0.005-0.25% by weight of a flow and performance improver. Improved waxy petroleum fuel oil compositions have now been discovered that include waxy middle distillate fuel oils that have improved low temperature properties. The flow improver formulations of the present invention have a boiling point range of about 120
Distillate fuels in a wide range from 150°C to 500°C (ASTM D1160), preferably boiling ranges from 150°C to 400°C.
is useful for distillate fuels. The present invention is particularly applicable to fuels having a relatively high final boiling point (FBP), ie, 360° C. or higher. The use of such fuels has recently become more widespread; these fuels tend to contain long chain n-paraffins and generally have high cloud points. Generally speaking, these fuels are difficult to treat effectively with conventional flow improver additives. The most common petroleum fuels are kerosene, jet fuel, diesel fuel, and heating oil. Cold flow property problems are the most commonly encountered problems with diesel fuels and heating oils. Fuel treatment rates above 0.25% by weight, such as up to about 0.5% by weight, can be used, but typically 0.005 to 0.25% by weight based on the weight of the distillate fuel.
Excellent results are obtained within the range of 0.005 to 0.05% by weight, preferably 0.005 to 0.05% by weight. The nitrogen-containing compound used in the present invention, component (a), is a condensation product of 1 molar proportion of an aromatic cyclic anhydride and 2 molar proportion of a secondary amine containing a _C14-18 linear alkyl group. Preferred secondary amines have the formula
HNR ₁ R ₂ (wherein R ₁ and R ₂ are and C ₁₄ 4%,
It is a secondary hydrogenated beef tallow amine (an alkyl group derived from beef tallow consisting of 31% C ₁₆ and 59% C ₁₈ ).
Preferred aromatic cyclic anhydrides are benzenecarboxylic acid anhydrides such as phthalic acid, terephthalic acid, isophthalic acid, and the like. A particularly preferred component (a) is an amide-amine salt obtained by the reaction of 1 molar proportion of phthalic anhydride with 2 molar proportions of dihydrogenated beef tallow amine. In the present invention, both the type of nitrogen-containing compound used and the type of ethylene vinyl acetate copolymer are important parameters to provide an effective two-component additive system that is an excellent flow improver. I understood. Thus, for example, the flow improver formulations of the present invention are highly effective flow improver formulations compared to three-component systems such as those described in U.S. Pat. No. 4,211,534, which are used at relatively high treatment concentrations. was found. In the present invention, the use of a third component (including its associated cost) has been found to be unnecessary for many fuels. We believe that the nitrogen-containing compounds of the present invention are extremely effective in inhibiting the growth of wax crystals. Typically, when the distillate fuel is cooled, normal alkanes containing about 14-32 carbon atoms crystallize out, with long-chain alkanes crystallizing out first, generally up to about 20-22 carbon atoms. It's in the atom. Nitrogen-containing compounds appear to be very effective at inhibiting the growth of most alkane waxes, but appear to be slightly less effective at inhibiting the early stages of wax precipitation. Optimum polymer properties vary from fuel to fuel, but ethylene vinyl acetate copolymers contain 10-40% by weight, more preferably 10-35% by weight, and most preferably 10-40% by weight.
Contains 20% by weight vinyl acetate, about 1000-30000,
Preferably 1500-7000, more preferably 1500-
5500, most preferably in the range of 2500-5500.
It is preferred to have a number average molecular weight (Mn) measured by Osmometry and a degree of branching in the range 2-12. The degree of branching is, for example, 20% (W/W) at 100℃
For orthodichlorobenzene solution, 220MHz
A Perkin-Elmer R-34 spectrometer (Perkin-Elmer R-34) operating in continuous wave mode
It is the number of methyl groups other than vinyl acetate methyl groups in a polymer molecule per 100 methylene groups, as determined by proton nuclear magnetic resonance spectroscopy, such as using a R-34 Spectrometer. Although the degree of polymer branching can vary within these limits, we have found that the more important property of the copolymer is the vinyl acetate content, and the polymer structure, especially for vinyl acetate content outside the above content range, It has been found that the use of ethylene vinyl acetate copolymers with different solubility characteristics can result in fuels with poor flow and overperformance. The inventors have also discovered that the relative proportions of nitrogen-containing compound and ethylene vinyl acetate copolymer are important in achieving improved flow and permeability. We have determined that at least 25% by weight, preferably at least
50% by weight of nitrogen-containing compounds should be used, preferably 25-95% by weight, more preferably 50-95% by weight, most preferably 60-90% by weight, especially 60-80% by weight.
% by weight, with the remainder being ethylene/vinyl acetate copolymer. The additive system of the present invention can be conveniently supplied as a concentrate of a mixture of nitrogen-containing compounds and ethylene vinyl acetate copolymer in oil or other solvent suitable for addition into bulk distillate fuels. Can be done. These concentrates can also contain other additives as required. 3-90% by weight, preferably 3-60% by weight in oil or other solvents,
Concentrates containing more preferably 10-50% by weight of additives are also within the scope of the invention. Hereinafter, the present invention will be further explained by examples (Examples and Comparative Examples), but these examples should not be considered as limiting the scope of the present invention.
Unless otherwise specified, parts in the examples are parts by weight. In Examples 1 to 11 below, the fuel was evaluated using the Distillate Operability Test (Dlstillate Operability Test).
Operability Test) (DOT test). This DOT test is a slow cooling test that has been shown to be a reasonably accurate comparison to actual field conditions. DOT Test Flow Improved Distillate Operability Test (DOT Test)
is a slow cooling test designed to correlate with pumping of stored heating oil. The cold flow properties of the above-described fuels containing additives were determined in a slow cool flow test as described below. 300ml of fuel 1
After linear cooling to the test temperature at a rate of °C/h, it is held constant at the test temperature. After 2 hours at the test temperature, approximately 20 ml of the surface layer is suctioned off so that the test is not influenced by unusually large wax crystals that tend to form at the oil/air interface during cooling.
After dispersing the wax that has settled in the bottle by gentle stirring, the CFPP filter device is inserted, which will be described later with respect to the CFPP test. 300
Apply a vacuum of _mmH2O and drain the fuel through the filter.
Pour 200ml into the graduated container. If 200 ml is collected within 60 seconds through the specified mesh size, it will be considered a pass, and if the filter is clogged and the flow rate is too slow, it will be judged as a fail. Messenger number, 20, 30, 40, 60, 80, 100,
Using a filter device with a 120, 150, 200, 250, or 350 filter screen, determine the finest mesh number that the waxy fuel can pass through. The smaller the wax crystals and therefore the finer the mesh, the greater the effectiveness of the flow improver additive. 2
It should be pointed out that no two fuels will give exactly the same test results with the same treatment concentration of the same flow improver additive, so the actual treatment concentration will vary somewhat from fuel to fuel. “Nitrogen Compound A” Reaction of 2 moles of a secondary di(hydrogenated tallow) amine containing a mixture of tallow n-alkyl groups such as 4% C ₁₄ , 31% C ₁₆ , and 59% C ₁₈ with 1 mole phthalic anhydride. Amide/dialkylammonium salt of the product. “EVA Polymer 1” This is a n3400 “VPO” ethylene-vinyl acetate copolymer with 17% by weight vinyl acetate and a degree of branching of 8.0, or 8 methyl-terminated alkyl side chains other than vinyl acetate per 100 methylene groups. has. The characteristics of the fuel used in the examples below are as follows.

[Table] Example 1 Fuel 1, 75% by weight of nitrogen compound A and 25% by weight
A flow improver consisting of EVA Polymer 1 was evaluated in a DOT test at -12°C, and the following results were obtained. Concentration in fuel Finest mesh passed 100 ppm 80 150 ppm 350 200 ppm 350 Example 2 Example 1 was repeated using Fuel 2 and the following results were obtained. Concentration in fuel Finest mesh passed 50 ppm 40 150 ppm 200 200 ppm 250 Example 3 - Comparison For comparison, Example 1 of U.S. Pat. No. 4,211,534
The tests of Example 1 were conducted on a conventional flow improver additive reported as Medium Polymer 1. The flow improver additive is described as a polymer mixture of about 75% by weight wax growth inhibitor and about 25% by weight nucleating agent, both of which are ethylene vinyl acetate polymers (hereinafter referred to as polymers). ). Finest mesh fuel 1 fuel 2 passing ppm of additive 100 40 30 150 100 40 200 120 80 Example 4 (a) Using a flow improver consisting of 100 parts by weight of nitrogen compound A and 25 parts by weight of polymer 1 , fuel 2
The test of Example 2 was repeated. When 125 ppm of this substance was added to fuel, the finest filter mesh that passed was 200. (b) Example 4(a) was repeated. However, by adding 25 parts of ethylene vinyl acetate copolymer having Mn 2000 and a vinyl acetate content of 36% to the composition of Example 4(a),
Ingredient additives were given. The finest filter mesh passed was 120. This means that
This shows that adding components previously considered desirable to the two-component system of the present invention can lead to negative results. Example 5 The DOT test used in Example 1 was repeated using Fuel 3. All tests were carried out using the nitrogen compound of Example 1.
It was carried out at -12°C using 100 ppm flow improver consisting of 75 ppm A and 25 ppm of various ethylene vinyl acetate copolymers (EVA) from Table 1 below. The purpose of this example is to demonstrate the importance of a special category of ethylene-vinyl acetate copolymers.

[Table] Example 6 The performance of an additive mixture containing 3 parts by weight of nitrogen compound A and 1 part by weight of EVA polymer 1 was evaluated at various additive concentrations: (i) Polymer 15 -B (ii) EVA Polymer 1 itself -C (iii) Compared with EVA polymer 8 -D in Table 1. The results of the DOT test in Fuel 1 at -12°C are shown in Figure 1. The composition of the invention is curve A, the letters of the other curves (B, C, D) correspond to the table above. Examples 7 and 8 The comparison of Example 6 was repeated with Fuels 2 and 3. The results are shown in FIGS. 2 and 3, respectively. Example 9 Nitrogen compound A and EVA polymer 1 in various ratios
Prepare a mixture of and at -12℃ in Fuel 1,
DOT tests were conducted at treatment rates of 200 ppm and 125 ppm additive in the fuel. These results are summarized in the first
A comparison was made with a similar additive mixture except that it included EVA Polymer 8 in the table. The results are shown in Figure 4. The upper curve is the treatment rate curve for 200 ppm additive and the lower curve is for 125 ppm additive. In each curve, line E is for the present invention, line F is for EVA
EVA polymer 8 from Table 1 instead of polymer 1
It is of a composition containing. Examples 10 and 11 Example 9 was repeated using Fuels 2 and 3. The results are shown in Figures 5 and 6, respectively. In Examples 12-16 below, the response of the oil to additives was determined using the Cold Filter Plugging Point Test.
(CFPPT). This CFPPT exam is
“Journal of the Institute
of Petroleum (Journal of the Institute
of Petroleum)” Vol.52, No.510. June 1966,
It is carried out by the method described in detail on pages 173-185. This test was designed to correlate with the cold flow of middle distillate oils in European automatic diesels. Briefly, a 40 ml sample of the oil to be tested is cooled into a bath maintained at about -34°C, providing a non-linear cooling of about 1°C/min. Weekly (at least 2°C above cloud point)
Starting from the above temperature, each time the temperature decreases by 1°C),
The ability of the cooled test oil to flow through a fine screen during a predetermined period of time is tested using a test device that is a pipette with an overturned funnel at the bottom end that is placed below the surface of the test oil. The mouth of the funnel is lined with a 350 mesh screen with a diameter of 12 mm and a limited area. Weekly tests draw up the test oil through the screen into the pipette to the 20 ml mark each day by applying a vacuum to the top of the pipette. If suction is successful every day,
Immediately return the oil to the CFPP pipe. Repeat this test for each 1°C decrease in temperature until oil no longer fills the pipette within 60 seconds, which is taken as the CFPP temperature. The difference between the CFPP of a fuel without additives and the CFPP of the same fuel with additives is determined by the additives.
Assume CFPP descent. The more effective the flow improver additive, the greater the CFPP drop for the same additive concentration. Example 12 CFPP of fuel 1 containing various concentrations of the following additives:
The performance was measured and shown in FIG. Additive curve (i) Nitrogen compound A G (ii) EVA polymer 8 H from Table 1 (iii) EVA polymer 1 I (iv) Polymer 15 J (v) Nitrogen compound A 3 parts K EVA polymer 1 1 part K Examples 13 and 14 The evaluation of Example 12 was repeated with Fuels 2 and 3. The results are shown in Figures 8 and 9, respectively. Example 15 Fuel 1 containing mixtures of nitrogen compound A and EVA polymer 1 in various proportions 50 ppm and 100 ppm
The CFPP performance was measured and the results are shown in Figure 10. Example 16 Example 15 was repeated using fuels 2 and 3 and the results are shown in Figures 11 and 12, respectively. Example 17 Additive formulations of the present invention were evaluated in Fuels 4 and 5 having the following properties. Fuel 4 Fuel 5 ASTM cloud point, °C -15 -10 Pour point, °C -21 -24 WAP, °C -17.5 -15 Distillation, °C Initial boiling point 179 158 10% 215 203 20% 230 225 50% 263 269 90% 314 320 End Boiling Point 345 347 (98.2%) Residue, % 1 1 1.1 The performance of the additive is evaluated in a test developed for the low temperature properties of diesel fuel. In this test, a fuel sample is cooled to the test temperature at a rate of 1.1°C (2〓) per hour.
Within 60 seconds under 152.4mm (6 inches) Hg vacuum
Test for hyperactivity by measuring whether it passes through a 350 mesh screen. If it passes, the fuel is considered acceptable. The ethylene vinyl acetate copolymer used in this example has the structure shown in Table 2 below.

[Table] Mixtures of nitrogen compound A and various amounts of ethylene vinyl acetate copolymers 9 to 14 were used as fuels 4 and 5.
Tested inside. The amounts of additive required to pass the test are listed in Figures 13 and 14, respectively. The lower the amount of additive, the better the performance of the additive. The numbers on the curves refer to the numbers given for the ethylene vinyl acetate copolymers in Table 2 above. In the following two examples, fuel 7 has the following properties:
was used. Cloud point (℃) -2 Wax appearance point (WAP) (℃) -6 Distillation (ASTM D-86) (℃) Initial boiling point 164 20 212 50 262 90 333 Final boiling point 370 Aromatic hydrocarbons (% (v /v)) 28 Example 18 Two ^3m3 tanks of fuel 7 under surrounding conditions -14
After cooling to 0.degree. C. and a cold soak period, 300 ml fuel samples were tested for cold flow performance as in the DOT test. Then, after gradually heating the tank to a higher temperature than WAP, again 0.5
Cooled to -14°C at a rate of 0°C/hour. The fuel was then pumped from the tank through a range of filter screens to determine the finest filter screen that the waxy fuel was able to pass through. The fuel in one tank is 135ppm Polymer 1
5 and passed only 30 mesh screens, but it contained 4 parts of nitrogen compound A and 1 part of nitrogen compound A.
The fuel in the other tank containing 135 ppm of the mixture with EVA Polymer 1 passed through a 100 mesh screen. Example 19 This example shows the results of testing four ^25m3 tanks of Fuel 7 side by side. After 3 weeks of storage under natural cold conditions (including natural temperature cycling) -14
℃ fuel was pumped from the tank as in a fuel distribution situation, and the finest filter screen through which the fuel passed was as follows: Mesh 70 through ppm additives Polymer 15 30 70 Nitrogen A 4 parts 40 EVA polymer 11 parts 135 Polymer 15 30 Mesh through ppm additives 135 Nitrogen A 4 parts 100 EVA polymer 11 parts

[Brief explanation of drawings]

Figure 1 shows a comparison of the test results of the flow improver additive of the present invention with other additives in a DOT test in Fuel 1 at -12°C; Figure 2 and Figure 3 shows similar results to Figure 1 for Fuels 2 and 3, and Figure 4 shows the flow improver additive of the present invention in the DOT test with Fuel 1 at -12°C. Figures 5 and 6 show a comparison similar to Figure 4 using fuels 2 and 3, and Figure 7 shows a comparison of the mixture with a similar additive mixture containing EVA polymer 8. , shows the CFPP performance of Fuel 1 with various concentrations of additives, Figures 8 and 9 show similar CFPP performance to Figure 7 with Fuels 2 and 3, and Figure 10 shows , mixtures of nitrogen compound A and EVA polymer 1 in various ratios
Figures 11 and 12 show similar CFPP performance to Figure 10 with Fuels 2 and 3; Figures 13 and 14 show CFPP performance for Fuel 1 containing 50 ppm and 100 ppm; , shows the amount of each additive required to pass the test when various amounts of mixtures of ethylene vinyl acetate copolymers 9-14 and nitrogen compound A were tested in fuels 4 and 5.

Claims (1)

Claims: 1. Essentially (a) 1 molar proportion of an aromatic cyclic anhydride and 2 molar proportions of a secondary amine containing a C _14-18 linear alkyl group, based on the total weight of the flow improver; of the condensation product of
(b) a vinyl acetate content of about 10-40% by weight and about 1000-95% by weight;
Methylene groups as determined by nuclear magnetic resonance ( ^1HNMR ) spectroscopy with a number average molecular weight (Mn) of 30,000 and 100
75-5% by weight of an ethylene-vinyl acetate copolymer having a degree of branching of about 2-12 alkyl groups per piece, suitable for wax-containing middle distillate fuel oils having a boiling point range of about 120-500°C. Additive concentrate consisting of an oil solution containing 3 to 60% by weight of the flow and filtration property improving mixture. 2 The mixture contains 50 to 90% by weight of (a) and 10 to 90% of (b)
An additive concentrate according to claim 1 comprising 50% by weight. 3. Claim 1 or 3, wherein component (a) of the mixture is an amide-amine salt obtained by reacting 1 molar proportion of phthalic anhydride with 2 molar proportions of dihydrogenated tallow amine. Additive concentrate according to paragraph 2. 4 essentially (a) a condensation product of 1 molar proportion of an aromatic cyclic anhydride and 2 molar proportions of a secondary amine containing a C _14-18 linear alkyl group, based on the total weight of the flow improver;
(b) a vinyl acetate content of about 10-40% by weight and about 1000-95% by weight;
Methylene groups as determined by nuclear magnetic resonance ( ^1HNMR ) spectroscopy with a number average molecular weight (Mn) of 30,000 and 100
75 to 5% by weight of an ethylene-vinyl acetate copolymer having a degree of branching of about 2 to 12 alkyl groups per ethylene-vinyl acetate copolymer;
A wax-containing middle distillate fuel oil with a boiling point range of about 120-500°C, the low temperature properties of which are improved by the addition of 0.005-0.5% by weight.