US2849301A - Fuel oil composition - Google Patents

Description

FUEL OIL COMPOSITION Paul Y. C. Gee, Woodbury, N. J., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Application July 18, 1956 Serial No. 598,543

13 Claims. (Cl. 44-64) This invention has to do with improved fuel oil compositions. More specifically it has to do with fuel oils which have been stabilized and which are particularly suitable for use as industrial and domestic fuels.

Thefuel oils improved in accordance with this invention are hydrocarbon fractions having initial boiling points of at least 100 F. and end point not higher than about 750 F., and which boil substantially continuously throughout their distillation ranges. Such fuel oils are generally known as distillate fuel oils. It is to be understood, however, that this term is not restricted to straightrun distillate fractions. Thus, as is well known to those skilled in the art, the distillate fuel oils can be straightrun distillate fuel oil's, catalytically or thermally cracked distillate fuel oils or mixtures of straight-run distillate naphthas and the like, with cracked distillate stocks. Moreover, such fuel oils can be treated in accordance with well known commercial methods, such as, acid 'or caustic treatment, solvent refining, clay treatment, etc.

The distillate fuel oils are characterized by their relatively low viscosities, pour points and the like. The principal property which characterizes the contemplated hydrocarbons fractions however, is the distillation range. As mentioned hereinbefore, this range will lie between about 100 F. and about 750 F. Obviously, the distillation range of each individual fuel oil will cover a narrower range falling, nevertheless, within the abovespecified limits. Likewise, each fuel oil will boil substantially continuously throughout its distillation range.

The fuel oils particularly contemplated herein are Nos. 1, 2 and 3 fuel oils used in domestic heating and as diesel fuel oils, particularly those made up chiefly or en tirely of cracked distillate stocks. The domestic heating oils generally conform to the specification set forth in ASTM Specifications D39648T. The specifications for diesel fuels are defined in ASTM Specifications D975- 4ST. Contemplated herein also are fuels for jet combustion engines. Typical jet fuels are defined in Military Specification MIL-F-5624B.

As is well known, fuel oils of the above-defined character have a tendency to deteriorate in storage and to form colored bodies and sludge therein. This deterioration of the oil is highly undesirable in that it causes serious adverse efiects on the characteristics of the oil, particularly on the ignition and burning qualities thereof. It is also a contributory factor, along with the presence of other impurities in the oil, such as rust, dirt and moisture, in causing clogging of the equipment parts, such as screens, filters, nozzles, etc. as is explained hereinbelow. An important economical factor is also involved in the problem of oil deterioration in storage, viz., customer resistance. Thus, customers judge the quality of an oil by its color and they oftentimes refuse to purchase highly colored oils.

Another and distinct problem that has plagued fuel oil manufacturers and users is that referred to as screen clogging. This involves the deposition of foreign subatent ce 2,849,301 Patented Aug. 26, 1958 well as any sludge material formed by the deterioration said deposition of foreign substances.

of the oil, on the metallic surfaces of screens and filters of burners and engines in which the oil is utilized. Additives have been developed to impart anti-clogging properties to fuel oils, functioning therein to inhibit the afore- The mechanism by which the clogging is prevented involves the adsorption of the anti-clogging agent or additive on the metal surfaces whereby the contacting of these surfaces by the foreign substances and/or preformed sludge is prevented.

In this way, deposition and build-up of these materials on the metal surfaces is avoided. It will be appreciated, therefore, that the problem of preventing screen clogging by fuel oils is entirely different from that of preventing the formation of sediment and color therein as occurs in the oil during prolonged periods of storage. Thus, it will be appreciated that any fuel distribution system will contain small amounts of foreign substances, such as condensed moisture and particles of rust and dirt, which become entrained in the oil, even though the oil has not been stored for any appreciable length of time. On the other hand, fuel oils which have been in storage for substantial periods of time will also contain another kind of sediment, or sludge, which is produced by the gradual deterioration of the oil per se. This sediment, or sludge, is formed in the oil as the result of chemical phenomena. Thus, during storage, oxidation of the various c01n ponents of the oil, such as pyrrolic compounds; phenols and thiophenols present therein, takes place forming quinoid molecules which condense with one another and/ or with other active hydrogen compounds also present in the oil to produce highly colored bodies of increasing molecular weight. When an oil has been in storage for any substantial period of time these compounds separate out as insoluble sludge. Additives have also been developed to inhibit the formation of sediment or sludge inthe oil due to oxidative deterioration of the oil in storage, as above described. Such additives act by inhibiting the initial oxidation and the subsequent reactions which produce such sludge.

It is apparent, then, that the problem of preventing screen-clogging by fuel oils is entirely different from the problem of preventing the formation of sediment and color therein as occurs in the oil during prolonged periods of storage. As evidence of the difference between these problems, additives which prevent screen-clogging have generally little or no effectiveness in preventing the formation of sediment and color. Correspondingly, other additives which eifectively inhibit sediment and color formation generally have little or no anti-screen clogging properties.

This invention is primarily concerned with preventing or retarding screen-clogging of fuel oils and the like, by

incorporating with said fuel oils a small amount of av novel additive. The invention is also concerned with overcoming the sediment and color formation shortcomings of fuel oils, as well as-the screen-clogging problems, by incorporating with the fuel oils amounts of the novel additive and other additives.

It is an object of this invention, therefore, to stabilize fuel oils.

It is a further object of this invention to provide a fuel oil free from screen-clogging tendencies.

Another object of the invention is to provide a fuel oil free from screen-clogging tendencies and stabilized against WhereinR is selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl and aryl radicals, R is selected from the group consisting of hydrogen, alkyl, aryl and hetero radicals, and m and n are integers including and whole numbers from 1 to 20 or more.

The esters described by the foregoing general formulae are prepared by reaction of one molar proportion of an aldehyde with one molar proportion of either an alkanol amine, a hydroxyalkyl polyalkyleneamine or a hydroxyalkyl hydrazine, to form a corresponding alkanolformaldimine; followed by reaction of one molar proportion of the latter with one molar proportion of an organic monocarboxylic acid. These reactions are shown below in terms of the foregoing general formulae:

Representative aldehydes suitable for use in preparing the desired esters of this invention are: (1) aliphatic aldehydes such as formaldehyde, acetaldehyde, chloral, glyoxal, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, isovaleraldehyde, n-caproaldehyde, n-heptaldehyde, stearaldehyde, acrolein, crotonaldehyde, etc.; (2) aromatic aldehydes such as benzaldehyde, tolualdehydes, chlorobenzaldehydes, nitrobenzaldehydes, aminobenzaldehydes, salicylaldehyde, hydroxybenzaldehydes, methoxybenzaldehyde, anisealdehyde, p-dimethylamino-benzaldehyde, etc.; (3) heterocyclic aldehydes such as furfural, thiophene aldehyde, pyrrole aldehyde, etc. Preferred, herein, of such aldehydes is formaldehyde, which can be used in monomeric form or polymeric form such as paraformaldehyde.

Alkanol amines used in forming the esters are typified by: hydroxylamine, ethanolamine, propanolamine, butanolamine, etc. Preferred of such compounds is ethano1- amine.

Hydroxyalkyl polyalkyleneamines used herein are illustrated by: aminoethylethanolamine, aminopropylethanolamine, aininobutylethanolamine, aminoethylbutanoh amine, etc. Preferred of such compounds is aminoethylethanolamine.

Typical hydroxyalkyl hydrazines used in forming the desired esters are: hydroxyethylhydrazine, hydroxypropylhydrazine, hydroxybutylhydrazine, etc. Preferred of such compounds is hydroxyethylhydrazine.

Numerous types of organic acids can be used, and are so contemplated, in forming the esters of this invention. These can be classified in the following-manner:

.(l) Carboxylic acids of the aliphatic, aromatic-and .naphthenic types.

Typical aliphatic acids are formic, acetic, propionic, caprylic, decanoic, lauric, stearic, oleic, linoleic and abietic acids. Aromatic acids are illustrated by benzoic salicylic and phthalic acids, which may or may not have aliphatic substituents such as diamyl benzoic acid, parafiin wax benzoic acid and the like. Of the carboxylic acids, those having from about twelve to about eighteen carbon atoms per molecule are preferred, and of these oleic acid is particularly preferred.

(2) Heterocycli-c acids such as thiophene carboxylic acid, furoic acids, pyrrole carboxylic acids and the like.

(3) Mixtures of such acids can also be used. For example, a mixture of stearic and oleic acids is shown in one of the following illustrative examples. A commercial mixture is Indusoil which is a mixture of rosin acids and fatty acids. This has an acid number of 180l85; a saponification value of 181-186; and iodine number (Wijs) of 175-185. It is comprised of 33-36% (weight) of rosin acids, 57-62% of fatty acids and 5 7% of sterols. Another commercial mixture is Facoil CB which is similar to Indusoil. It has an acid number of 166; a saponification value of 174; and an iodine number of 143 (Wijs). It contains 45.4% (weight) of rosi acids, 47.8% of fatty acids and 6.6% of sterols.

It is to be understood that in order that an ester product have satisfactory solubility in oil, proper combination of reactants must be made. For example, when hydroxylamine is used as an alkanol amine, the aldehyde and/or acid with which it is associated should have. one or more long chain aliphatic groups. In the same .connection, when an acid such as phthalic acid is used, an aldehyde and/or amine having one or more aliphatic groups should be used. 1

The esters contemplated herein are used in fuel oils in concentrations varying between about 10 pounds per thousand barrels of oil, and about 200 pounds per thousand barrels of oil. Preferably, the concentration will vary between about 25 and 100 pounds per thousand barrels. In terms of weight percent based upon the weight of the'fuel oil, the concentrations vary preferably between about 0.01 percent and about 0.05 percent.

As indicated above, the fuel oils of this invention can also contain, in addition to the aforementioned esters, an addiitive serving as a sedimentand color-forming inhibitor. Outstanding inhibitors which cooperate with the esters are tertiary alkyl primary amines described in application Serial No. 299,249, filed July 16, 1952, now abandoned, and Serial No. 578,881, filed April 18, 1956. Briefly, such amines are tertiary alkyl, primary, monoamines having from about four to about twenty-four carbon atoms per molecule and having the primary amino nitrogen atom attached directly to a tertiary carbon atom. These amines all contain the terminal unit:

Mixtures of the foregoing alkyl primary amines having from about 4 to about 24 carbon atoms are also highly suitable for use in the invention. A typical mixture of amines, for example, is onecomprised of tertiary alkyl primary amines of from about 12 to about 15 carbon atoms, said mixture averaging about 12 carbon atoms per amine molecule. This mixture, designated hereinafter as Mixture A, contains, by weight, about of tertiary dodecyl amine, about 10% tertiary pentadecyl amine and relatively small amounts, i. e., less than about 5% of amines having less than 12 or more than 15 carbon atoms.

Another mixture of tertiary alkyl primary amines which is highly suitable for use in the inventon is composed of tertiary alkyl primary amines of from about 18 to 24 carbon atoms and averaging about 20 carbon atoms per molecule.

This mixture designated herein as Mixture l3, contains the C -C tertiary alkyl primary amines in about the following proportions:

The amount of tertiary alkyl, primary monoamine additives used, together with the esters described above, can vary from about 25 to about 100 pounds per thousand barrels of oil (i. e., about 0.01 percent to about 0.05 percent by weight) depending upon the particular oil to be stabilized, and the conditions of storage.

Ifit is desired, the fuel oil compositions can contain other additives for the purpose of achieving other results. Thus, for example, there can be present foam inhibitors, anti-rust agents, and ignition and burning quality improving agents. Examples of such additives are silicones, dinitropropane, amyl nitrate, metal sulfonates and the like.

The following specific examples are for the purpose of illustrating the fuel oil compositions of this invention and of exemplifying the specific nature thereof. It is to be understood, however, that this invention is not to be limited by the particular additives and fuel oils, or to the operations and manipulations described herein. Other esters of the above-described character and fuel oils are utilizable, as those skilled in the art will readily appreciate.

EXAMPLE 1 A quantity (0.5 mol; 30.5 parts by weight) of ethanolamine was added gradually to a mixture of parts by weight (0.5 mol) of paraformaldehyde and 87.8 parts by weight of benzene, as a diluent, at a temperature of about C. The mixture was stirred while the ethanolamine was added, and stirring was continued throughout the preparation. Reaction between the amine and aldehyde was exothermic and the temperature rose rapidly to 70 C. The resulting mixture was heated under benzene reflux until the evolution of water of reaction ceased. Then, one hundred parts by weight (0.5 mol) of lauric acid were added. The mixture thus formed was heated gradually to 200 C. and was held at 200 C. until water evolution ceased. The product, the lauric ester of ethanolformaldimine, was filtered through Hi-Flo Clay, a

1 diatomaceous earth. The product contains 4.7 percent of nitrogen, as compared with a theoretical value of 5.5 percent.

EXAMPLE 2 Ethanolamine (2.25 mol; 137 parts by weight) was added gradually to a mixture of paraformaldehyde (2.25 mol; 68 parts by weight) and 130 parts by weight of toluene, as a diluent, at 25 C. Again, stirring of the materials was maintained throughout the preparation. The reaction was exothermic. The temperature rose rapidly to 75 C. The resulting mixture was heated EXAMPLE 3 A quantity (0.5 mol; 48 parts by weight) of furfural was added gradually to a mixture of ethanolamine (0.5 mol; 30.5 parts by weight) and toluene (100 parts by 6 weight), at 25 C. Again, toluene was used as a diluent and stirring of the materials was continued during the preparation. Reaction was exothermic. The temperature rose rapidly to C. After all of the furfural had been added, the resulting mixture was heated under toluene reflux until the evolution of water had ceased. Then, oleic acid 0.5 mol; 141 parts by weight) was added to the above reaction mixture. The reaction mixture thus formed was heated gradually to 200 C. and was held at the latter temperature until water and toluene were no longer evolved. The product, the oleic ester of ethanolfurfuraldimine, contains 2.96 percent of nitrogen, in comparison with the theoretical value of 3.4 percent.

EXAMPLE 4 Fifty-five parts by weight of a 70 percent aqueous solution of hydroxyethylhydrazine (0.5 mole; 38 parts by weight) were added gradually to a mixture of paraformaldehyde (0.5 mol; 15 parts by weight) and toluene at about 25 C. Here, too, toluene was the diluent and the materials used were stirred throughout the preparation. Reaction was exothermic, with the temperature rising rapidly to 78 C. After the hydroxyethylhydrazine solution had been added, the resulting mixture was heated under toluene reflux until water was no longer evolved. Then, oleic acid (0.5 mol; 141 parts by weight) was added. The mixture so formed was heated gradually to 200 C. and was maintained at 200 C. until the evolution of water had ceased. The product, the oleic ester of hydroxyethylhydrazoformaldimine, was filtered through Hi-Flo Clay. The filteredproduct has a nitrogen content of 5.26 percent, comparing with the theoretical value of 7.9.

EXAMPLE 5 A quantity of 305 parts (0.5 mole) of ethanolamine was added gradually at 25 C. to a mixture of 15 parts (0.5 mole) of paraformaldehyde and cc. of benzene as a diluent with stirring. The reaction was exothermic and the temperature rose rapidly to 70 C. The resulting mixture was heated under benzene reflux until water stopped coming over. Then, 141 parts (0.5 mole) of oleic acid were added to the reaction mixture above. The mixture was gradually heated to 195 C. and was held at 195 C. until water stopped coming over. The product, the oleic ester of ethanolformaldimine, was not filtered. Analysis: Nitrogen found 4.69%; theory 5.5%.

EXAMPLE 6 A quantity of 75 parts (1.25 moles) of ethanolamine was added gradually at 25 C. to a mixture of 37 parts (1.25 moles) of paraformaldehyde and cc. of toluene as a diluent with stirring. The reaction was exothermic and the temperature rose rapidly to 85 C., then dropped. The mixture was heated under toluene reflux until the evolution of water ceased. Then 300 parts (approx. 1 mole) of Indusoil Tall oil were added to the reaction mixture. The mixture was gradually heated to 200 C. and was held at 200 C. until water and toluene stopped coming over. The product, a mixed ester of ethanolformaldimine, was filtered through Hi-Flo Clay. Analysis: Nitrogen found 3.72%; theory 3.9%.

EXAMPLE 7 A quantity of 61 parts (1 mole) of ethanolamine was gradually added at 25 C. to a mixture of 30 parts (1 mole) ofparaformaldehyde and 150 cc. of toluene as a diluent with stirring. The reaction was exothermic and the temperature rose rapidly to 85 C. then dropped. The mixture was heated under toluene reflux until the evolution of water ceased. Then, 280 parts (1 mole) of naphthenic acid were added to the reaction mixture. The mixture was gradually heated to 200 C. and was held at 200 C. until water and toluene stopped coming over. The product, a naphthenic ester of formaldimine,

7 was filtered through Hi-Flo Clay. Analysis: Nitrogen found 3.56%; theory 4.1%.

EXAMPLE 8 Aquantity of 76 parts (1.25 moles) of ethanol-amine was-gradually added at 25 C. to'amixture of 37.5 parts (1.25 moles) 'of paraformaldehyde and 150 cc. of toluene as a diluent with stirring. The reaction was exothermic and the temperature rose rapidly to 85 C., then dropped. The mixture was heated under toluene reflux until the evolution of water ceased. Then, 340 parts (approx. l'mole) of Facoil 'CB were added to the reaction-mixture. The mixture was gradually heated to 200 C. and was held at 200 C. until water and toluene stopped coming over. The product, a mixed ester of formaldimine, -was filtered through Hi-Flo Clay. Analysis: Nitrogen found 2.98%; theory 3.5%.

EXAMPLE 9 A quantity of 76 parts (1.25 moles) of ethanolamine was gradually added at 25 C. to a mixture of 37.5 parts (1.25 moles) of paraformaldehyde and 150 cc. of toluene as a diluent with stirring. The reaction mixture was exothermic and the temperature rose rapidly to 80 C., then dropped. The mixture was heated under toluene reflux until the evolution of water ceased. Then, 114 parts (0.4 mole) of stearic acid and 169 parts (0.6 mole) of oleyl acid were added to the reaction mixture. The mixture was gradually heated to 200 C. and was held at'200 C. until water and toluene stopped coming over. The product, a mixture of stearyl and oleyl esters of formaldimine, was filtered through Hi-Flo Clay. Analysis: Nitrogen found 3.7%; theory 4.1%.

EXAMPLE 10 A quantity of 25 parts (0.125 mole) ofamine Mixture A, described above, was gradually added at 25 C. to 25 parts (0.102 mole) of oleyl ester of ethanolformaldimine (Example 2, above), with stirring. No heat of reaction was observed. The mixture was stirred at 25 C. for thirty minutes.

EXAMPLE 11 'A quantity of 10 parts (0.05 mole) of amine Mixture A was gradually added at 25 C. to 10 parts (0.04 mole) of lauryl ester of ethanolformaldimine (Example 1, above), with stirring. No'heat of reaction was observed.

The mixture was stirred at 25 C. for thirty minutes.

EXAMPLE 12 8 EXAMPLE 13 :A quantity of 10 parts (0.05 mole) of amine Mixture A was gradually addedat 25 C. to 10 parts (0.035 mole) of stearic-oleyl ester of ethanolformaldimine (Example 9, above), with stirring. No-heat of reaction was observed. The mixture was stirred at25C."for thirty minutes.

EXAMPLE 14 A quantity of 10 parts (0.05 mole) of amine Mixture A was gradually added at 25 C. to 10-parts (0.26 mole) of FacoilCB ester of ethanolformaldimine (Example 8, above), with stirring. No heat of reaction was observed. The mixture was stirred at 25 C. for thirty minutes.

The effectiveness of the additives of this invention in reducing screen-clogging is shown by screen-clogging test data.

The amount of screen-clogging is determined witha Sunstrand V3 or S1 home fuel oil burner pump having a self-contained mesh Monel metal screen. About 0.05 percent, by weight, of a naturally-formed fuel oil sludge, composed of fuel oil, water, dirt, rust, and organic sediment, is added to ten liters of the fuel oil under test. This mixture is circulated by the pump through the screen for six hours. Then the sludge deposited on the screen is washed off with normal pentane, and filtered through a tarred asbestos (Gooch crucible) filter. After it is dried, the material on the filter is washed with .a 50-50 (volume) acetone-methanol mixture. The total amount of organic sediment is determined by evaporatingythe nepentane and the acetone-methanol filtrates, and weighing the residue. The weight of material on the filter is the amount of inorganic sediment deposited. The sum of the weights of the organic and the inorganic deposits, in milligrams, gives the weight of .sludge deposited, which weight is compared with the Weight of sludge deposited from the uninhibited (blank) fuel oil to determine the percent of screen-clogging. The uninhibited fuel oil, after six hours on test, eifects 100 percent screen-clogging. Thus, the comparison percentagewise between the weight of sludge deposited by the uninhibited fuel oil and the inhibited fuel oil affords a measure of. the percent of screen-clogging. The fuel oil used in this test is a blend comprising sixty percent (by weight) of catalytically cracked component .and forty percent -.of.straight run component, the blend having a boiling range from about 320 F., to about 640 F. The data obtained from said tests are provided in Table I. Examples 1 through 9, inclusive, show fuei oils inhibited with the above-described esters. Examples 10 through 14, inclusive, show fuel oils inhibited with said esters and amine mixtures.

Table I Example Product of- Screen clogging,

Aldehyde percent Hydroxyamme Furfural Paraformaldehydm Hydroxyethylhydrazine... 25 Ethanolamlne 1 Amine used with ester.

Sedimentation tests were run on fuel oils and the same oils inhibited with the esters and amines described above in Examples 10 through 14. In the 110 F. storage test used, a 500-milliliter sample of the fuel oil under test is placed in a convected oven maintained at 100 F., for a period of six weeks. Then, the sample is removed from the oven and cooked. The cooled sample is filtered through a tarred asbestos filter (Gooch crucible) to remove the insoluble matter. The weight of such matter, in milligrams, is reported as the amount of sediment. In the test, a sample of the blank, uninhibited oil is run along with the fuel oil blend under test. The effectiveness of fuel oil compositions containing the esters and amines of said Examples 10 through 14, is determined by comparing the test data therefor with the test data for the unihibited, blank fuel oils. The results are given be low in Table II. The fuel oils used were of the same character as those described above in connection with Table I.

Table II Concn., Sedi- Inhibitor lb./1,000 ment,

bbls. rug/liter 158 +Example 100 18 0 111 +Example 11 100 19 0 122 +Example 12 100 28 0 122 +Example 13 100 6 0 122 +Example 14- 100 20 Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to,'without departing from the spirit and scope of wherein R is a hydrocarbon radical, and n is an integer from 0 to 20, and R is selected from the group consisting of hydrogen, alkyl, aryl, and hetero radicals,

R o o 0 0H, oHz)..NH(oH2 ,,.N=0-R' wherein R, R' and n are as described in (a), and m is an integer from 0 to 20.

2. A distillate fuel oil containing a small amount,

. fromv about 0.01 to about 0.05 percent by weight of the fuel oil, a fuel oil soluble ester of an organic acid and an alkanolformaldimine as defined by claim 1.

3. A distillate fuel oil defined by claim 1 wherein the alkanolformaldimine is formed from an aldehyde and an alkanol amine.

4. A distillate fuel oil defined by claim 1 wherein the alkanolformaldimine is formed from an aldehyde and a hydroxyalkyl hydrazine.

5. A distillate fuel oil defined by claim 1 wherein the alkanolformaldimine is formed from formaldehyde.

6. A distillate fuel oil defined by claim 1 wherein the organic acid is an aliphatic acid having from about twelve to about eighteen carbon atoms per molecule.

7. A distillate fuel oil containing a small amount, sufilcient to reduce the screen-clogging tendencies there-' of, of a fuel oil soluble ester of lauric acid and of an alkanolformaldimine formed from ethanolamine and formaldehyde.

8. A distillate fuel oil containing a small amount, sufficient to reduce the screen-clogging tendencies thereof, of a fuel oil soluble ester of olcic acid and an alkanolformaldimine formed from ethanolamine and formaldehyde.

9. A distillate fuel oil containing a small amount, sufficient to reduce the screen-clogging tendencies thereof, of a fuel oil soluble ester of oleic acid and an al kanolformaldimine formed from ethanolamine and furfural.

10. A distillate fuel oil containing a small amount, sufficient to reduce the screen-clogging tendencies thereof, of a fuel oil soluble ester of oleic acid and an alkanolformaldimine formed from hydroxyethylhydrazine and formaldehyde.

11. A distillate fuel oil containing a small amount, suflicient to reduce the screen-clogging tendencies thereof, of a fuel oil soluble ester of a naphthenic acid and an alkanolformaldimine formed from formaldehyde and ethanolamine.

12. A distillate fuel oil containing a small amount, sufficient to improve the screen clogging properties thereof, of a fuel oil soluble ester of an organic acid and an alkanolformaldimine as defined by claim 1, and a small amount, sufiicient to improve the resistance to sedimentation thereof, of a tertiary alkyl primary monoamine containing from four to about twenty-four carbon atoms per molecule and characterized by structural unit 13. A distillate fuel oil defined by claim 12 wherein the monoamine is tertiary dodecyl amine.

References Cited in the file of this patent UNITED STATES PATENTS 2,223,244 Bohm Nov. 26, 1940 2,346,663 Chenicek Apr. 18, 1944 2,361,339 White et a1 Oct. 24, 1944 2,420,122 Chenicek May 6, 1947 2,564,106 Gribbins et a1. Aug. 14, 1951 2,641,538 Thompson et al. June 9, 1953 2,641,539 Thompson et a1. June 9, 1953

Claims (1)

1. A DISTILLATE FUEL OIL CONTAINING A SMALL AMOUNT, SUFFICIENT TO REDUCE THE SCREEN-CLOGGING TENDENCIES THEREOF, OF A FUEL OIL SOLUBLE ESTER SELECTED FROM THE GROUP CONSISTING OF: