JPH0353355B2 - - 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]

TECHNICAL FIELD This invention relates to methods of improving the flow and filtration properties of distillate fuels at low temperatures using certain additive mixtures. In particular, the present invention improves the low temperature flow and filtration properties of waxy middle distillate fuels using additives containing nitrogenous wax crystal growth inhibitors and a special range of ethylene-vinyl acetate copolymers. Regarding how to. 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, e.g. in Ilynckyi et al., June 8, 1976. Described in issued U.S. Patent No. 3,961,916,
This US patent describes an additive combination consisting of ethylene copolymerized with ethylenically unsaturated mono- or dicarboxylic acid alkyl esters or vinyl esters of _C1 - _C17 saturated fatty acids. Additive systems containing nitrogen-containing amides or amine salts as used in the process of the present invention are described in U.S. Pat. No. 4,211,534 to Feldman, issued July 8, 1980; The patent describes a component combination flow improver additive consisting of an ethylene polymer or copolymer and 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. There is. This three-component system is
It is stated that there are advantages 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 its derivatives are described in U.S. Pat. The above substances combined are listed. The present invention is based on the condensation products 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 in combination with certain ethylene-vinyl acetate copolymers. It is based on the discovery that the addition of essentially two-component additives is highly effective at improving the flow and filtration properties of below-cloud point middle distillate fuels at relatively low process concentrations. be. 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,
having a number average molecular weight (Mn) of 1500 to 7000, preferably 1500 to 5500, and a degree of branching in the range of about 2 to 12 alkyl groups per 100 methylene groups as determined by nuclear magnetic resonance ( ¹ HNMR) spectroscopy. 75-5%, preferably 50-10% by weight of an ethylene-vinyl acetate copolymer and 0.005-0.5%, preferably 0.005-0.25% by weight of a flow and filtration improver. It has been found that the cold flow and filtration properties of waxy middle distillate fuel oils can be improved by The flow improver mixture used in the process of the present invention has a boiling point range of about 120°C to about 500°C (ASTM
D1160) is useful for a wide range of distillate fuels, preferably distillate fuels with a boiling point range of about 150°C to 400°C. The method of the 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. Add the above (a) component and (b) component to fuel oil as individual components at a ratio of (a):(b) = 25 to 95: 75 to 5, and add both components (a) and (b) to the fuel oil. Similar excellent effects can be obtained even if the total amount is 0.005 to 0.5% by weight based on the fuel oil. The nitrogen-containing compound used in the method of the present invention, that is, component (a), has a 1 molar ratio of aromatic cyclic anhydride and
It is a condensation product with 2 molar proportions of a secondary amine containing a C _14-18 linear alkyl group. Preferred secondary amines have the formula HNR ₁ R ₂ where R ₁ and R ₂ are approximately C ₁₄ 4
%, an alkyl group derived from beef tallow consisting of 31% C ₁₆ and 59% C ₁₈ ). Further, preferred aromatic cyclic anhydrides include phthalic acid,
Anhydrides of benzenedicarboxylic acids such as terephthalic acid, inphthalic acid, etc. Particularly preferred (a)
The component is an amide-amine salt obtained by the reaction of 1 molar proportion of phthalic anhydride and 2 molar proportions of dihydrogenated beef tallow amine. In the process of 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 found out something. Thus, for example, the flow improver mixture used in the process of the present invention is a highly effective flow improver mixture compared to ternary systems such as those described in U.S. Pat. No. 4,211,534, which are used at relatively high treatment concentrations. It was found that It has also been found in the present invention that the use of a third component (including its associated cost) is unnecessary for many fuels. We believe that the nitrogen-containing compounds used in the method of the present invention are extremely effective in inhibiting the growth of wax crystals. Typically, when distillate fuel is cooled, approximately
Normal alkanes containing 14 to 32 carbon atoms crystallize, with long chain alkanes crystallizing out first, generally with a maximum of about 20 to 22 carbon atoms. 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 are preferred at 10-40 wt.%, more preferably 10-35 wt.%, and most preferably 10-40 wt.%.
Contains 20% by weight vinyl acetate, about 1000-30000, preferably 1500-7000, more preferably 1500-
5500, most preferably in the range of 2500 to 5500,
It is preferred to have a number average molecular weight (Mn) measured by Osmometry and a degree of branching in the range from 2 to 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 contents 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 filtration performance. The inventors have also discovered that the relative proportions of nitrogen-containing compounds and ethylene vinyl acetate copolymer are important in achieving improved flow and filterability. 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 used in the process of the present invention comprises: in oil;
Alternatively, it can be conveniently supplied as a concentrate of a mixture of nitrogen-containing compounds and ethylene vinyl acetate copolymer in other solvents suitable for addition into bulk distillate fuels. These concentrates can also contain other additives as required. It is also within the scope of the invention to use concentrates containing 3 to 90% by weight, preferably 3 to 60% by weight, more preferably 10 to 50% by weight of additives in oil or other solvents. Also, as mentioned above, the nitrogen-containing compound and the ethylene vinyl acetate copolymer may be added directly to the fuel as individual components. 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 evaluation of fuels with improved low temperature properties was performed using the Distillate Operability Test (DOT test).
I followed. 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,
After cooling linearly to the test temperature at a rate of 1° C./hour, 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. Apply a vacuum of 300 mmH ₂ O and pour 200 ml of fuel into the graduated receiver through the filter. 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 filter screen of 120, 150, 200, 250, 350, measure 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% _C14 , 31% _C16 , 59% _C18 with 1 mole of 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. This 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 copolymers (hereinafter referred to as Polymer 15). ). Finest mesh fuel 1 through ppm of additive Fuel 2 100 ppm 40 30 150 ppm 100 40 200 ppm 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 Performance of an additive mixture containing 3 parts by weight of nitrogen compound A and 1 part by weight of EVA polymer 1 at various additive concentrations: () Polymer 15 -B () EVA polymer 1 itself -C () 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 additive mixture used in the process of the invention is curve A, with the letters of the other curves (B, C,
D) corresponds 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 used in the method of the invention and line F is the one used in Table 1 instead of EVA polymer 1.
It is of a composition containing EVA polymer 8. 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 in a bath maintained at about -34°C, giving 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. Each weekly test draws the test oil through the screen into the pipette up to the 20ml mark by applying a vacuum to the top of the pipette. If suction is successful each time,
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 () Nitrogen compound A G () EVA polymer 8 H () EVA polymer 1 I () Polymer 15 J (v) Nitrogen compound A 3 parts K EVA polymer 1 1 part Examples 13 and 14 Example 12 The evaluation 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 mixtures used in the process of the invention were evaluated on fuels 4 and 5 with the following properties.

[Table] The performance of additives is evaluated in tests developed for the low temperature properties of diesel fuels. 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
Filterability is tested 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 9-14 were tested in fuels 4 and 5. 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 indicate the order assigned to the ethylene vinyl acetate copolymer 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 17 are placed under surrounding conditions -
After cooling to 14°C and a cold soak period, a 300 ml fuel sample was collected as in the DOT test.
Tested for cold flow performance. 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 15
contained 4 parts nitrogen compound A and 1 part EVA, although it passed only 30 mesh screens.
The fuel in the other tank containing 135 ppm of the mixture with 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:

【table】 [Brief explanation of drawings]

FIG. 1 shows a comparison of the test results of the flow improver additive used in the method of the invention with other additives in a DOT test in Fuel 1 at -12°C;
Figures 2 and 3 show similar results to Figure 1 for fuels 2 and 3, and Figure 4 shows the results of the present invention in the DOT test with fuel 1 at -12°C. Figures 5 and 6 are similar to Figure 4 using Fuels 2 and 3, showing a comparison of the flow improver additive mixture used in the process and a similar additive mixture containing EVA Polymer 8. Figure 7 shows the CFPP performance of Fuel 1 with various concentrations of additives, and Figures 8 and 9 show similar results to Figure 7 using Fuels 2 and 3. Figure 10 shows the CFPP performance with various ratios of nitrogen compound A and
Mixture with EVA polymer 1 50ppm and 100ppm
Figures 11 and 12 show CFPP performance similar to Figure 10 with Fuels 2 and 3, and Figures 13 and 14 show the CFPP performance of Fuel 1 containing various fuels. The amount of each additive required to pass the test is shown when mixtures of amounts of ethylene vinyl acetate copolymer 9-14 and nitrogen compound A are 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;
Number average molecular weight (Mn) of 30000 and nuclear magnetic resonance (
methylene group 100 as determined by spectroscopic analysis ( ¹ HNMR)
75 to 5% by weight of an ethylene-vinyl acetate copolymer having a degree of branching of about 2 to 12 alkyl groups per unit, and a cold flow and filterability improving mixture consisting of: added as an additive concentrate, or in the same amount as above. By adding both components (a) and (b) as individual components to the fuel oil in appropriate proportions, the total weight of both components (a) and (b) in the fuel oil becomes 0.005% based on the weight of the fuel oil.
~0.5% by weight,
A method of improving the low temperature flow and filtration properties of wax-containing middle distillate fuel oils having a boiling point range of about 120-500°C.