US2974027A - Additives for improving the electrical properties of hydrocarbon oils - Google Patents

Description

United States Patent fiice 2,974,027 Patented Mar. 7, 196i ADDITIVES FOR IMPROVING THE ELECTRICAL PROPERTIES OF HYDROCARBON OILS James T. Di Piazza, Mountainside, N .J., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Oct. 6, 1958, Ser. No. 765,306

15 Claims. (Cl. 52-6) tolerance and rust inhibiting action by the incorporation therein of tetra-aliphatic ammonium salts of certain carboxylic acids in combination with certain acidic compounds selected from the class of alkyl acid phosphates and alkyl mercapto acetic acids.

The electrical properties of hydrocarbon oils boiling in the range between about 75 F. and about 750 F. have assumed increasing importance in recent years as a result of a series of explosions which have occurred during the transportation and handling of such oils. Strong evidence indicates that these explosions have been caused by the generation and accumulation of electrical charges within the oils until electrical discharges sufiicient to ignite hydrocarbon vapors in admixture with air occurred. Such explosions have, for the most part, taken place as the oils were being transferred from one vessel into another and it is generally thought that the tribo-electrical properties of the oils were responsible.

Studies have shown that electrical charges are generated during the handling of a wide variety of distillate petroleum products. In laboratory experiments it has been demonstrated that high voltage discharges can be created during the pumping of hydrocarbons ranging in boiling range from about 75 F. up to about 750 F., as shown in the following table.

T ABLE I Production of electrical discharges in laboratory pumping tests In general, the higher boiling, more viscous products are more susceptible to the generation of electrical charges than are the lower boiling materials. Aviation turbo-jet fuels and certain solvents which have relatively low initial boiling points are particularly hazardous, however, because their volatility is such that their vapors form explosive mixtures with air over a relatively 'wide temperature range and hence any discharge which occurs is likely to cause an explosion.

The actual mechanisms involved in the generation, accumulation and discharge of electrical energy during the handling of hydrocarbons are not fully understood. It is known, however, that the electrical conductivity of the hydrocarbons plays an important part in this phenomenon. Increasing the conductivity increases the rate at which charges are dissipated and it therefore appears that the danger of explosions due to electrical discharges can be abated by increasing conductivity. In general, it has been found that hydrocarbons having specific conductivities in the range between about l 1O- and 1X10 mhos per centimeter are particularly hazardous and that the hazard is reduced if the conductivity of the oil is greater than about 1X10 mho per centimeter.

It'has been suggested heretofore that a variety of differentpolar compounds be added to hydrocarbons to increase their specific conductivity and thus reduce the danger that an explosion due to the generation, accumulation and discharge of electrical energy in the hydrocarbons will occur. Certain metallic compounds, particularly soaps of polyvalent metals and combinations of such soaps with other polar compounds, have been said to be particularly elfec-tive. In practice, however, it has been found that such additive materials of the prior art are of little value for improving the electrical properties of hydrocarbons because they are readily extracted by small quantities of water with which the hydrocarbons come into contact and because they degrade other properties of the hydrocarbons.

The present invention provides a new and improved class of additive compositions for use in hydrocarbons boiling in the range between about 75 F. and about 750 F. which greatly improve the electrical properties of such hydrocarbons and in addition are free of the undesirable features which have characterized additives proposed for this service heretofore. In accordance with the invention, it has now been found that tetra-aliphatic ammonium salts of certain carboxylic acids in combination with certain alkyl acid phosphates or alkyl mercapto acetic acids have a synergistic effect upon the electrical properties of hydrocarbons and provide much greater protection against the generation, accumulation and discharge of electrical energy in such hydrocarbons than has been possible in the past. Moreover, it has been found that these synergistic additive combinations markedly improve the water tolerance of hydrocarbons to which they are added and are not extracted by water with which the hydrocarbons come into contact. A further a j advantage of the additive combinations of the invention is that they afford much greater protection against rust and corrosion of metals in contact with the fuels in the presence of water than do the 111st inhibitorsnow 'em The invention thus prou vides a new class of multifunctional additives which ployed in such hydrocarbons.

greatly improve the properties'of hydrocarbon oils and the like to which they are added.

The tetra-aliphatic ammonium salts of carboxylic acids which are employed in the additive combinations of the invention are tetra-aliphatic ammonium salts of hydroxy carboxylic acids containing from 2 to. 10 carbon atoms in the acid portion of the molecule. Examples of hydroxy carboxylic acids which maybe employed in .pre paring these salts include glycolic acid, lactic acid, hydracrylic acid, 3-hydroxybutyric acid, 2-hydroxybutyric acid, l-hydroxybutyric acid, glyceric acid, erythric acid,"

arabitic acid, manniticacid, gluconic acid, galacturonic acid, tartronic acid, malic acid, tartaric acid, trihydroxyglutaric acid, saccharic acid, citric acid, mandelic acid, phenyllactic acid, tropic acid and gallic acid. The additives thus include tetra-aliphatic ammonium salts of both aliphatic and cyclic hydroxy carboxylic acids containing from 2 to 10 carbon atoms .per molecule. The acids must contain at least one hydroxy group as well as one carboxyl group. They may, however, contain up to 5 .hydroxyl groups and up to 4 carboxyl groups. Salts of the aliphatic hydroxy carboxylic acids containing from 2 to 6 carbon atoms per molecule are preferred. Tetraaliphatie ammonium salts of malic acid and gluconic acid, wherein one hydroxyl group and one carboxyl group are attached to a carbon atom in common, have been found to be especially effective and are therefore particularly preferred.

Tetra-aliphatic ammonium salts of the hydroxy carboxylic acids set forth above may be readily prepared by reacting such acids with tetra-aliphatic ammonium hydroxides and then removing the resulting water by means of an azeotropic distillation employing a solvent such as benzene or toluene.

Tetra-aliphatic ammonium hydroxides suitable for use in the preparation of salts by the reaction set forth above are those having aliphatic groups of from 1 to 24 carbon atoms in length. The aliphatic groups may be either alkyl groups or alkenyl groups. Examples of such tetraaliphatic ammonium hydroxides include tetrapropyl ammonium hydroxide, ethyltributyl ammonium hydroxide, dimethyldibutenyl ammonium hydroxide, butyltrihexyl ammonium hydroxide, dimethyldihexadecyl ammonium hydroxide, butyltrioleyl ammonium hydroxide, trimethylhexadecyl ammonium hydroxide, tetraheptadecyl arnmoniurn hydroxide and the like. Tetra-aliphatic ammom'um hydroxides containing alkyl and alkenyl radicals such as those set forth above are widely available and their properties will be familiar to those skilled in the art.

Preferred tetra-aliphatic ammonium hydroxides for use in preparing the salts of'hydroxy carboxylic acids which are employed as one constituent of the additive combinations of the invention are commercial mixtures of such hydroxides derived from naturally-occurring materials such as coconut oil, tallow fat and soy bean oil. One such mixture, for example, is trimethylsoya ammonium hydroxide, which is derived in part from soy bean oil and contains about 8% C about 91% C and about 1% C aliphatic radicals in the soya group. Similar mixed compounds may be derived from Lorol alcohols, which are mixtures of primary alcohols containing from 10 to 18 carbon atoms prepared by the hydrogenation of coconut oil. Such mixed compounds are also sometimes referred to as coco alcohols. Tetra-aliphatic ammonium hydroxides having one or more such mixed aliphatic groups may be employed.

The alkyl acid phosphates which may be used as the second constituent of the additive combination of the invention are monoand dialkyl acid phosphates having alkyl groups of from about 6 to about 10 carbon atoms. Such acid phosphates are normally prepared by the reaction of P with an alcohol or a mixture of alcohols. The resulting products may thus contain mixed alkyl groups. Particularly preferred alkyl acid phosphates for use in accordance with the invention are those which are prepared by the reaction of a C -oxo alcohol with phosphorus pentoxide. The C -oxo alcohols are mixed isoalkyl alcohols derived by the well known Oxo process, by catalytic reaction of a C copolymer of propylene and butene with carbon monoxide and hydrogen to form aldehydes which are then hydrogenated to alcohols. The copolymer normally consists of a mixture of isomers because it is derived from a refinery gas stream containing propylene and mixed normal and iso butylenes. The C -OXD alcohols are now well known in the art. A more 4 complete description of them may be found in colums 4 and 5 of US. Patent 2,837,562.

The alkyl mercapto acetic acids which are also useful in combination with the tetraaliphatic ammonium salts of hydroxy carboxylic acid in accordance with the invention are alkyl thioethers of acetic acid having the formula RSCH COOH where R is an alkyl group containing from about 4 to about 20 carbon atoms, preferably from about 8 to about 18 carbon atoms. These compounds may be prepared by the reaction of an alkyl alkali metal mercaptide with a haloacetic acid as described in US. Patent 2,216,751. Specific examples of alkyl mercapto acetic acids useful in accordance with the invention include amyl mercapto acetic acid, isooctyl mercapto acetic acid, lauryl mercapto acetic acid, hexadecyl mercapto acetic acid and the like. The thioethers having mixed alkyl groups derived from coconut oil, tallow fat, soy bean oil and similar naturally occurring materials are preferred. Lorol mercapto acetic acid, for example, may be derived from a mixture of aliphatic mercaptides prepared from Lorol alcohols and may contain alkyl groups of from 10 to 18 carbon atoms as follows:

Wt. Percent Similar mixed alkyl thioethers derived from other commercial mixtures of aliphatic compounds will be familiar to those skilled in the art.

Alkyl thioethers derived from other low molecular Weight carboxylic acids may also be useful in accordance with the invention.

The tetra-aliphatic ammonium salts of hydroxy carboxylic acids described above are added to hydrocarbons boiling in the range between about 75 F. and about 750 F. in accordance with the invention in concentrations between about 0.00005 by weight and about 0.5% by weight. Concentrations between about 0.0005 by weight and about 0.0.5 by weight are preferred. The alkyl acid phosphates and alkyl mercapto acetic acids which are employed in conjunction with the tetra-aliphatic ammonium salts of hydroxy carboxylic acids may be used in concentrations ranging from about 0.00005% by weight to about 0.5% by weight and are particularly effective in concentrations between about 0.001% by weight and about 0.05% by weight. The :eight ratio between the tetra-aliphatic ammonium salts and the alkyl acid phosphates or alkyl mercapto acetic acids may be varied widely, from about 0.1/1 to about 10.0/1 for example, but in general it is preferred to employ from about 1 to about 4 parts of the tetra-aliphatic ammonium salt per part of the phosphate or of the mercapto acetic acid.

The hydrocarbon oils boiling in the range between about 75 F. and about 750 F. in which the additives of the invention may advantageously be employed include petroleum distillate fuels, solvents, transformer oils, and the like. The additives are particularly useful in distillate fuels including gasolines, aviation turbo-jet fuels, kerosenes, diesel fuels and heating oils. Gasolines which may be benefitted by the presence of the additives include both motor gasolines and aviation gasolines such as those defined by ASTM Specification D-910-56 and D-43956T. Such gasolines may contain a wide variety of other additives such as anti-knock agents, scavenger agents, antioxidants, dyes, anti-icing agents, solvent oils and the like.

The boiling range of such gasolines normally extends between about 75 F. and about 450 F. As pointed out heretofore, the additives of the invention are particularly useful in aviation turbo-jet fuels. Specifications for such fuels are set forth in U.S. Military Specifications MIL-F- 5616, MIL-F-5624D, MILF-25524A and MIL-F- 25558A. These fuels are normally distillable at temperatures between about 100 F. and about 600 F. Diesel fuels as referred to in connection with the invention in general boil between about 250 F. and about 750 F. and are defined at length in ASTM Specification D975- 53T. Heating oils within which the additives may be incorporated include those set forth in ASTM Specification D-396 48T, particularly those falling within grades 1 and 2 of the specification. The additives may also be employed in pure hydrocarbons and in other combustible volatile organic compounds of low electrical conductivity, carbon disulfide for example.

If desired, the additive agents of the invention may be incorporated into distillate fuels and other volatile combustible organic liquids in the form of a concentrate comprising a tetraaliphatic ammonium salt of a hydroxycar boxylic acid; an acidic compound selected from the group consisting of alkyl acid phosphates and alkyl mercapto acetic acids; and a volatile inert organic solvent such as benzene, xylene, toluene, diethylene glycol, pyridine, or the like. A typical concentrate composition is as follows:

It will be understood that the ratio of the tetraaliphatic ammonium salt and the acidic constituent in such concentrates may be varied within the limits set forth above, from about 0.1 to about 10 parts of the ammonium salt per part of the phosphate or mercapto acetic acid, and that the percentage of active ingredients in the concentrate may range from about 10% up to about 90% by weight or more. Other additive agents such'as anti-oxidants, dyes, haze suppressors and the like may also be included in the concentrates.

The exact nature and objects of the invention may be more fully understood from the following examples.

EXAMPLE 1 In order to demonstrate the effectiveness of the additive agents of the invention for improving the electrical properties of hydrocarbon oils, tests were carried out to determine the specific conductivity of samples 'of aviation turbo-jet fuels, samples of the same'fuels containing the individual additive constituents, and samples of the fuels containing the additive constituents in combination. :The fuels which were employed were representative of the fuels classified as JP-4 fuels and defined by-U.S. Military Specification MlL-F-5624D. They had API gravities of about 48.7, Reid vapor pressures of about 2.5 pounds per square inch and boiling ranges of from about 100 to about 520 F. The additive constituents employed in the test were di-trimethylsoya ammonium malate, trimethylsoya "ammonium gluconate, tn'methylsoya ammonium lactate, lorol mercapto acetic acid, and a mixture of equal quantities of monoand di-octyl acid phosphates.

The specific conductivity of each of the samples tested was measured by applying a fixed direct current voltage to a standard conductivity cell containing the sample. A

standard high-resistance element was connected in series with the cell and the current which flowed in the circuit during each test was. computed by measuring the voltage across this resistance'element and applying Ohms law. The resistance of the sample, the specific resistance and the specific conductivity were in turn calculated. The

' ditions which could result in an explosion as are un- A results obtained in these .tests are shown in Table II below. r

TABLE II Synergistic efi'ect of additives upon specific COHdHCIWiIy' Specific Oon- Ratio (Base+ Composition ductivity r, (T Additives) I mho/cm. to :7 Base Base Fuel A 4. 5X10- Base Fuel A +0.005 Wt. Percent Oetyl Acid Phosphate 4.4)(10- 1.0 Base Fuel A +0.005 Wt. Percent DI Irimethylsoya Ammonium Malate 2.3)(10- 5.1 Base Fuel A +0.0005 Wt. Percent Octyl Acid Phosphate +0.0045 Wt. Percent Di-Trimcthylsoya Ammonium Malate 3. 9X10- 8. 7 Base Fuel A +0.001 Wt. Percent Octyi Acid Phosphate +0.004' Wt. Percent Di- Trimethylsoyn Ammonium Malete. 6. 7X10 15 Base Fuel A +0.0025 Wt. Percent Octyl Acid Phosphate +0.0025-Wt. Percent Di-Trimethylsoya Ammonium Malate 5. 5X10" 12 Base Fuel A +0.01 Wt. Percent Oetyl Acid Phosphate 4. 7x10- 1. 0 Base Fuel A +0.01 Wt. Percent Di-Trimethylsoya Ammonium Malate 3. 0X10- 6. 7

' Base Fuel A +0.001 Wt. Percent Octyl Acid Phosphate +0.009 Wt. Percent Di- Trimethylsoya Ammonium Malata. 7. 0X10- 16 Base Fuel A +0.002 Wt. Percent Octyl Acid Phosphate +0008 Wt. Percent D1- Trimethylsoya Ammonium Malate 1.4)(10- 31 Base Fuel A +0.005 Wt. Percent Octyl Acid Phosphate +0.005 Wt. Percent Di- Trimethylsoya Ammonium Malate. 1. 2X10- 27 Base Fuel B 1. 3X10' Base Fuel B+0.01 Wt Percent OctylAcid Phosphete. 3.3)(10- 25 Base Fuel B +0.01 Wt. Percent imethylsoya. Ammonium Gluconate 5. 'i 10- 415 Base Fuel B +0.005 Wt. Percent Octyl Acid Phosphate +0.005 Wt. Percent Trimethylsoya Ammonium Gluconate- 1. 9X10- 1, 462 Base FuelO 3.0X10- Base Fuel 0 +0.01 Wt. Percent Lorol I Mercapto Acetic Acid 6.5)(10- 2. 2 Base Fuel G +0.01 Wt. Percent D methylsoya Ammonium Malate 8. 6X10" 9. 0 Base Fuel 0 +0005 Wt. Percent Lorol Mercapto Acetic Acid +0.005 Wt. Percent Di-Trimethylsoya Ammonium a1ata 1.1 X10" 37 Base Fuel D 1.6)(10-" Base Fuel D +0.01 Wt. ercent Mon Octyl Acid Phosphate 4.6)(10- 2. 9 Base fuel I) +0.01 Wt. Percent; Trimethylsoya Ammonium Lactate. 2. 9X10 1.8 Base Fuel D +0.005 Wt. Percent Mono- Di-Octyl Acid Phosphate +0.005 Wt.

Percent Trimethylspya Ammonium Lactate 1.,2X10? 75 The data in Table II demonstrate that the tetra-aliphatic ammonium salts of hydroxy carboxylic acids coact With the acid phosphates and mercapto acetic acids to produce a much greater increase in specific conductivity than can be obtained when the constituents are employed individually." The improvement in specific conductivity" was particularly pronounced inthe case of fuel B, which had .an' extremely low conductivity initially,'but syn-,

ergism between the additive constituents was manifested A in every instance. It can'be seen that fuels containing the combination additives have a'greatly reduced tend-i ency to accumulate electrical charges thereinand thus are not as likely to discharge electrical energyunder coninhibitedfuels' and fuels containing the individual additives. 1 7

EXAMPLE 2 Tests similar to those described in the. preceding example were carried out by adding varying amounts of di-trimethyloleyl ammonium malate and a mixture; of: equal parts of monoand di-octyl acid phosphate to ples of an aviation turbo-jet fuel. v x i l r The specific conductivities of the samples and the ratios between the conductivities of the samples containing the additive and that of the base fuel were again obtained. Table III sets forth these results. 1'

7 TABLE n1 Synergistic effect of additives upon specific conductivity of aviation turbo-jet fuel Wt. Percent Additive in Fuel Specific Ratio Conductiv- (Base+ Di-Triity, c, a Addinlethyl Octyl Acid Inho/cm. tives) to oleyl Ani- Phosphate l1 Base momum Malate l 1 0 3. 9X10 0 0.01 3.7)(10 0.95 0.01 0 3. 5Xl0' 0 0. 0075 0. 0025 7. 7X10- 20 0.005 0.005 3. 8X10 10 0.0025 0. 0075 2. 5X10 6. 4

1 Base Fuel.

Again it can be seen that the combination of the tetra-aliphatic ammonium salt and the alkyl acid phosphate produced an increase in specific conductivity which was surprisingly greater than that which resulted from use of the individual additives. The use of 3 parts of ditrimethyloleyl ammonium malate and 1 part of octyl acid phosphate was particularly eifective and resulted in a -fold increase in specific conductivity.

EXAMPLE 3 In order to determine the extent to which the additive constituents are extracted from hydrocarbons in the presence of water, tests were carried out by determining the specific conductivities of samples of an aviation turbojet fuel and samples of the same fuel containing the additives. These samples were then extracted with water and the conductivity values were again determined. A decrease in conductivity would indicate that the additive constituents were extracted. The tests were carried out using a fuel similar to that employed in Example 1. The water extraction step involved shaking 80 cc. of the fuel and 20 cc. of water for 2 minutes and then allowing them to stand overnight. Results of these tests are set forth in Table IV.

Although the use of 0.01 wt. percent of di-trimethylsoya ammonium malate appreciably increases the conductivity of aviation turbo-jet fuels and similar hydrocarbon oils, data in the above table show that the benefits of this increased conductivity may be lost if the oil is subsequently extracted with water. The conductivity of the sample containing only the malate in the above table was actually lower than that of the base fuel after water extraction. The sample containing both the malate and the phosphate, on the other hand, had a higher conductivity than that of the sample containing only the malate before water extraction did not undergo any appreciable decrease in conductivity as a result of the extraction step. The additives of the invention are thus clearly superior to the salts of hydroxy carboxylic acids alone.

EXAMPLE 4 It is known that the presence of small amounts of water in aviation turbo-jet fuels, keroscnes, heating oils and similar hydrocarbon oil compositions tend to accelerate the generation and accumulation of electrical charges in such compositions. It has been found, for example, that an oil saturated with water will produce twice as many 7000 volt electrical discharges during laboratory pumping tests as will an anhydrous sample of the same oil. If small amounts of dispersed Water are present in addition to the water of saturation, the number of discharges produced is even higher. For this reason, the water tolerance of such oils is extremely important. Many of the additive materials which have been suggested for improving the electrical properties of oils are highly surface-active materials and have an extremely adverse eifect upon water tolerance. The increased conductivity efiected by such additives may to a considerable extent be offset by their tendency to promote the suspension of dispersed water in the oil to which they are added.

In order to determine the effect of the additives of the invention upon the water tolerance of oils to which they are added, water tolerance studies were carried out on samples of two different aviation turbo-jet fuels, samples of the same fuels to which had been added di-trimethylsoya ammonium malate and samples containing the ma]- ate and small amounts of octyl acid phosphate. The test employed is described in Federal Test Standard No. 791, Method 3251.6, Interaction of Water in Aircraft Fuel. In brief, this test comprises shaking 80 cc. of the fuel to be tested and 20 cc. of water for a 2 minute period and then allowing the mixture to settle for 5 minutes. At the end of the settling period, the condition of the water-fuel interface is noted. An interface rating is assigned in accordance with the following criteria:

Interaction of water and aircraft fuels [Method 3251.0, Fed. Test Std. No. 791} Appearance of Interface Interface Rating Clear and clean A few small clcar bubbles covering not more than Shred of lace and/or film at interface.-- Loose lace and/or slight scum Tight lace and/or heavy scum The condition of the fuel layer and the water layer on either side of the interface are also examined. An interface rating of 1 or 1B, with no sign of haze or emulsion in the fuel or water layers, is a passing rating and meets the requirements of the military specifications governing the water tolerance of aviation turbo-jet fuels. The results obtained in tests of the additives of the invention are set forth in Table V.

It will be noted that the addition of di-trimethylsoya ammonium malate alone to base fuel A reduced the interface rating from a passing rating of 1 to an unacceptable rating of 2. When 0.005 wt. percent of octyl acid phosphate was employed with the same quantity of di-trimethylsoya ammonium malate, a satisfactory rating of 1B resulted. Samples of Base Fuel B containing both the octyl acid phosphate and the di-trimethylsoya ammonium malate had the same interface rating as did the base fuel containing no additive at all. The additive composition of the invention thus meets the critical water tolerance requirements for additives designed to improve the electrical properties of hydrocarbon oils.

EXAMPLE 5 A further critical requirement imposed upon aviation turbo-jet fuels and many other distillate petroleum products is that they must not exhibit a pronounced tendency to promote the rust and corrosion of metallic surfaces with which they come into contact in the presence of small amounts of water. Military Specification MIL-F- 5624D prescribes the use of certain rust inhibitors in turbo-jet fuels. It has been found that the additive combination of the present invention not only improves the electrical properties and water tolerance of such fuels but also is a potent rust inhibitor. In order to demonstrate this, tests were carried out on samples of a turbo-jet fuel containing two different commercial rust inhibitors and samples of the same fuel containing the additive combination of the invention. The test used was Modification B of ASTM D665. In brief, thistest is carried out by immersing a highly polished steel specimen in a vessel containing 300 cc. of oil and 30 cc. of water and agitating the oil-water mixture for a period of 24 hours while maintaining the temperature at 100" F. by thermostatic control. After the 24 hour period, the specimen is removed from the mixture, washed with a light hydrocarbon solvent and examined for corrosion. The results obtained with these tests are shown in Table VI.

7 TABLE VI Additive rust inhibiting properties Composition Percent Rust Turbo-Jet Fuel +0.002 Wt. Percent Commercial Additive A 1 100 Turbo-Jet Fuel +0.003 Wt. Percent Commercial Additive B 2 10 An alkyl coco amine phos hate marketed commercially as a. corrosion inhibitor, descri ed in Belgian Patent 541,762.

A commercial rust inhibitor approved by the milltar services for use in aviation turbo-jet fuels and consisting pr marily ofa dimer of linoleic acid with a minor amount of an alkyl amine phosphate.

Commercial Additive A employed inthe testsreferred to above and inTable VI was an alkyl coco amine phosphate which is widely marketed as a corrosion inhibitor for use in gasolines and similar hydrocarbon compositions. Commercial Additive B was a commercial additive whichhas been approved by the military services for use in aviation turbo-jet fuels and is listed as a satisfactory inhibitor in MilitaryPSpecification MIL-F- 5624D. It will be notedthat neither of these twocomtion thus providesv an improved multi-functional additive which may be employed in-lieu of a multitude of 'sepaf 4 i 75 rate additives which have been usedfheretoforejg EXAMPLE 6' A diesel fuel boiling in the range between about i i F. and about 600 F. is improved with respect to its elec-' EXAMPLE 8 A kerosene boiling in the range between 300 and about 570 F. contains 0.02 wt. percent of C -oxo acid phosphate and 0.007 wt. percent of trimethylsoya ammonium gluconate. I

It will be understood that the additives of the present invention may be included into fuel, solvents and other hydrocarbon oils boiling in the range between about F. and about 750 F. in conjunction with a wide variety of other additives designed'to improve properties not affected by the additives of the invention. Such other additives include, for example, polymeric dispersant stabilizing additives, haze inhibitors, dyes, dye stabilizers and the like.

What is claimed is: a

1. A hydrocarbon oil boiling in the range between about 75 F. and about 750 F. to which has been added from about 0.00005% to about'0.5% by weight of a tetra-acyclic aliphatic ammonium salt of an unsubstituted C to C hydroxy carboxylic acid, the acyclic aliphatic groups of said salt selected from the class consisting of alkyl and alkenyl radicals each radical containing from 1 to about 24 carbon atoms, and from about 0.00005 to about 0.5% by weight of an acidic compound selected from the group consisting of alkyl acid phosphates in which the alkyl radicals each contain from about 6 to about 10 carbon atoms and alkyl mercapto acetic acids having alkyl groups containing from 4 to' 20 carbon atoms.

2. An oil as defined by claim 1 wherein said. tetraacyclic aliphatic ammonium salt is a tetraalkyl ammonium salt of a C to C unsubstituted aliphatic hydroxy' carbox'ylic acid.

3. An oil as defined by claim 1 whereinsaid acidic compound is an isooctyl acid phosphate. g

4. An oil as defined by claim 1 wherein said acidic compound is an alkyl mercapto acetic acid having alkyl groups of from about 8 to about 18 carbon atoms.

5. An oil as defined by claim- 1 wherein said tetraby weight and said acidic compound is present in a concentration between about 0.001% and about 0.05% by weight.

' 6. A liquid hydrocarbon fuel boiling in the range between about 75 F. and about 750? F. to which has been added from about 0.001% to about 0.05% jby 7 weight of a tetra-acyclic aliphatic ammonium salt of an] unsubstituted C to C aliphatic hydroxy carboxylic acid; the aliphatic groups of said saltselected from the class consisting of alkyl and alkenyl radicals each radical taining from 1 to about 24 carbon atoms, and from about r 0.001% to about 0.01% by weight of an alkyl acid phosphate in which the alkyl radicals each contain from about 6 to about '10 carbon-atoms. a 1 7. A fuel as defined by claim 6 wherein said acid]: phosphate is a .monodi-alkyl acid phosphate. t

8. A fuel as defined by claim 6 wherein said ammonis um. salt is a trimethylsoya ammonium Salt. 7

9. A fuel as: defined'byclairn owherein said i um salt is-a malate; I

10. A fuel as defined by claim 6 wherein said ammonium salt is di-trimethylsoya ammonium malate.

11. A fuel as defined by claim 6 wherein said alkyl acid phosphate is a C -oxo acid phosphate.

12. A liquid petroleum distillate turbo-jet engine fuel having incorporated therein from about 0.0005% to about 0.05% by Weight of di-trimethylsoya ammonium malate and from about 0.001% to about 0.05% by weight of an octyl acid phosphate.

13. A liquid petroleum distillate turbo-jet engine fuel having incorporated therein from about 0.0005% to about 0.05% by weight of di-trimethyl oleo ammonium malate and from about 0.001% to about 0.05% by weight of an octyl acid phosphate.

14. A liquid petroleum distillate turbo-jet engine fuel having incorporated therein from about 0.0005% to about 0.05 by weight of trimethylsoya ammonium gluconate and from about 0.001% to about 0.05% by weight of a mixture of alkyl mercapto acetic acids having alkyl groups of from about 8 to about 18 carbon atoms.

15. An additive composition for improving the electrical properties of combustible liquid hydrocarbon fuels boiling between about 75 and 750 F. consisting essentially of 1 part of a tetra-acyclic aliphatic ammonium salt of an unsubstituted C to C hydroxy carboxylic acid having acylic aliphatic groups selected from the class consisting of alkyl and alkenyl radicals of from 1 to 24- carbon atoms in length and from about 0.1 to about 10 parts by weight of an acidic compound selected from the group consisting of alkyl acid phosphates wherein the alkyl groups each contain from about 6 to about 10 carbon atoms and alkyl mercapto acetic acids having alkyl groups containing from 4 to 20 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A HYDROCARBON OIL BOILING IN THE RANGE BETWEEN ABOUT 75*F. AND ABOUT 750*F. TO WHICH HAS BEEN ADDED FROM ABOUT 0.00005% TO ABOUT 0.5% BY WEIGHT OF A TETRA-ACYCLIC ALIPHATIC AMMONIUM SALT OF AN UNSUBSTITUTED C2 TO C10 HYDROXY CARBOXYLIC ACID, THE ACYCLIC ALIPHATIC GROUPS OF SAID SALT SELECTED FROM THE CLASS CONSISTING OF ALKYL AND ALKENYL RADICALS EACH RADICAL CONTAINING FROM 1 TO ABOUT 24 CARBON ATOMS, AND FROM ABOUT 0.00005% TO ABOUT 0.5% BY WEIGHT OF AN ACIDIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYL ACID PHOSPHATES IN WHICH THE ALKYL RADICALS EACH CONTAIN FROM ABOUT 6 TO ABOUT 10 CARBON ATOMS AND ALKYL MERCAPTO ACETIC ACIDS HAVING ALKYL GROUPS CONTAINING FROM 4 TO 20 CARBON ATOMS.