US3460923A - Fuels containing amine phosphate anti-icing compositions - Google Patents

Description

United States Patent Int. Cl. C101 N26 US. CI. 44-72 9 Claims ABSTRACT OF THE DISCLOSURE Compositions effective to reduce icing of gasoline are prepared by reacting a monoor di-ester (or a mixture of monoand di-ester) of phosphoric acid with a C secondary or tertiary amine.

This invention relates to improved fuel compositions. More particularly, this invention relates to gasoline compositions for use in internal combustion engines, and is particularly concerned with improved gasoline compositions containing the salts of organo phosphoric acid ester?- and aliphatic amines.

When internal combustion engines are operated on a gasoline fuel having the desired volatility characteristics for cold weather driving, a stalling problem is encountered during the warm-up period, particularly under cool, humid atmospheric conditions. It has been generally recognized that the cause of repeated engine stalling in cool, humid weather is the formation of ice on the throttle plate and the carburetor valve near it. The Water which forms the ice does not come from the gasoline, i.e., as entrained water, but from the air that enters the carburetor. The gasoline which evaporates in the carburetor has sufiicient refrigerating effect to condense and freeze the moisture in the air and cause ice particles to build up on the throttle plate and in the carburetor valve. Then, as the engine is idled, the throttle plate closes and the ice chokes off the normal small flow of air through the small clearance between the throttle plate and the carburetor wall, causing the engine to stall.

The stalling of automobile engines in cold weather may also result from the presence of water in the gasoline itself. This water may be introduced during blending operations, during storage by condensation from the atmosphere, or during transportation to the consumer. During cold weather, this water will very often freeze and block the fuel lines of plugged filters, thus preventing passage of the gasoline to the engine.

Heretofore, these problems have been at least partially overcome by the addition to the gasoline of alcohols, glycols, or similar materials which lower the freezing point of water. However, the effective amount of such additives is in the order of 1 to 3% by volume. Such large concentrations are expensive and frequently affect the chemical and physical properties of the gasoline.

Accordingly, it is an object of this invention to provide a fuel composition inhibited against ice formation.

It is another object of this invention to provide an improved fuel composition which is designed to reduce or eliminate carburetor icing.

3,460,923 Patented Aug. 12, 1969 It is another object of this invention to provide a motor fuel adapted to prevent stalling during engine warm-up in cool, humid weather.

It is another object of this invention to provide an improved gasoline fuel composition which contains a minor amount of a die-icing :additive.

These and other objects are accomplished in accordance with this invention by providing a fuel compositon for internal combustion engines comprising a major amount of hydrocarbon fuel of the gasoline boiling range, and a minor amount of an amine salt prepared by reacting at a temperature of from about 0 to about C., an aliphatic amine selected from the class consisting of secondary and tertiary amines having from 2 to 4 carbon atoms, with a phosphoric acid having the formula POOH wherein R is an aliphatic hyrocarbon radical having from 8 to 18 carbon atoms, and R is a radical selected from the class consisting of hydrogen and R.

The gasoline comprising the major component of the compositions of this invention may be any hydrocarbon or mixture of hydrocarbons falling substantially within the commercial gasoline range, the boiling point of which normally ranges from about 30 F. to about 440 F. The gasoline composition of this invention is particularly directed to a mixture of hydrocarbon possessing a ASTM boiling range of about 140 F. at 10% distillation to about 392 F. at distillation and possessing a Reid vapor pressure of between 11.5 and 15.0 pounds.

The phosphoric acid which is useful in the preparation of the amine salts of this invention is a partially esterified orthophosphoric acid having the formula POOH wherein R is an aliphatic hydrocarbon radical having from 8 to 18 carbon atoms and R is a radical selected from the class consisting of hydrogen and R. Thus, it is contemplated that the phosphoric acid may be a mono-ester or a di-ester of orthophosphoric acid or a mixture thereof. For reasons of convenience and economy a mixture of monoand di-phosphate esters is preferred. Such'a mixture can be prepared by the reaction of phosphorus pentoxide with 3 moles of an aliphatic alcohol having from 8 to 18 carbon atoms. The reaction may be illustrated by the following equation:

Alternatively, from about 2 to 4 moles of the aliphatic For the preparation of the phosphoric acids useful in the process of this invention, the alcohol will be primary alcohol, and preferably a branched primary alcohol having from 8 to 18 carbon atoms. Examples of such alcohols are the normal alcohols derived from coconut kernel oils. One such commercially available fraction consists mainly of the n-octyl and n-decyl alcohols. Another consists largely of n-dodecyl alcohol but contains other alcohols having from 10 to 18 carbon atoms. Preferably, the alcohol will be a mixture of branched chain primary alcohols such as those produced by the well-known x0 process. Examples of such alcohols include the Oxo octyl, decyl, tridecyl, and octadecyl alcohols, all of which are mixtures consisting predominantly of branched chain primary alcohols obtained from propylene-butylene dimer, tri-propylene, tetra-propylene, and penta-propylene, respectively.

The useful amines are the aliphatic secondary and tertiary amines having from 2 to 4 carbon atoms. Examples of such amines include dimethyl amine, trimethyl amine, methyl ethyl amine, diethyl amine, methyl propyl amine, and dimethyl ethyl amine.

The limitation to secondary and tertiary amines having from 2 to 4 carbon atoms is necessitated by the discovery that prmiary aliphaic amines form salts which are either insoluble in fuel oils or result in the formation of gels when aromatic solvents such as xylene are used in their preparation.

The amine salts can be prepared simply by mixing the organic substituted phosphoric acid and the aliphatic amine reactant at a temperature below about 100 C. The reaction in most instances is slightly exothermic, and is preferably carried out in the presence of a solvent. Solvent swhich have been found to be useful are the hydrocarbons or polar solvents such as benzene, naphtha, toluene, xylene, n-hexane, dioxane, chlorobenzene, kerosene, naphtha, or a fuel oil. Ordinarily, the relative proportions of the reactants used to prepare the salt are one equivalent of the phosphoric acid and one equivalent of the aliphatic amine so that all of the free amino groups are converted to salts. In some instances, however, only one acidic hydrogen of a mono-organic substituted phosphoric acid may be utilized to form a salt. Thus, amine salts which are useful in this invention are prepared by reacting an amine with from one to two equivalents of a phosphoric acid.

The following examples illustrate the methods for preparing the amine salts which are useful in the compositions of this invention. (Parts are by weight unless otherwise indicated.)

EXAMPLE 1 Phosphorus pentoxide (130 parts, 0.91 mole) is added to 550 parts (2.75 moles) of tridecyl alcohol at 3852 C. over a period of 5 hours. The mixture is then heated to 60 C. and maintained at a temperature of 60-63 C. for 5 hours. The mixture is cooled to 53 C. and 14 parts (0.09 mole) of phosphorus pentoxide is added in 15 minutes. The mixture is again heated to 60 C. and maintained at a temperature of 6062 C. for 5.3 hours. The mixture is filtered and the filtrate is the desired product, a mixture of monoand di-tridecyl phosphoric acids having a phosphorus content of 9.04%.

A solution of 348 grams (1.4 equivalents) of the tridecyl phosphoric acid mixture in 176 grams of xylene is prepared and cooled to 26 C. To this mixture there is added 64 grams (1.42. equivalents) of dimethylamine below the surface of the solution over a period of 1 hour while maintaining the temperature of the reaction mixture at 23 -26 C. The solution is then filtered using a filter aid. The filtrate, containing 30% by weight of xylene, is the desired product having a phosphorus content of 5.36%, and a nitrogen content of 3.16%.

EXAMPLE 2 A solution of 189 grams (0.77 equivalent) of the tridecyl phosphoric acid mixture of Example lin 101 grams of xylene is prepared and cooled to 17 C. To this solution there is added 46 grams (0.77 equivalent) of trimethylamine over a period of 30 minutes while maintaining the reaction temperature at 17-25 C. The solution is then filtered and the filtrate is the desired product containing 30% by weight of xylene, and having a nitrogen content of 2.62% and a phosphorus content of 5.23%.

EXAMPLE 3 To a mixture of 285 grams (1.17 equivalents) of the tridecyl phosphoric acid mixture of Example 1 in 137 grams of xylene, there is added over a period of 20 minutes 35 grams (0.78 equivalent) of dimethylamine below the surface of the solution while maintaining the reaction temperature between 25 45 C. The mixture was stirred an additional 30 minutes and filtered. The desired product, containing 30% by weight of xylene and having a phosphorus content of 5.67% and a nitrogen content of 2.20%.

EXAMPLE 4 To a solution of 864 grams (3.54 equivalents) of the tridecyl phosphoric acid mixture of Example 1 in 430 grams of xylene, there is added 139 grams (2.36 equivalents) of trimethylamine over a period of 45 minutes while maintaining the reaction temperature between 18- 25 C. After stirring an additional 30 minutes, the solution is filtered through a filter aid. The filtrate is the desired product, containing 30% by weight of xylene and having the phosphorus content of 5.25% and a nitrogen content of 2.46%.

EXAMPLE 5 To 474 parts (3 moles) of a commercial mixture of isomeric trimethyl heptanols there is added 142 parts (1 mole) of phosphorus pentoxide over a period of 6 hours while maintaining the reaction temperature at 15-35 C. The mixture is then held to 65 C. and maintained at this temperature for 4 hours. The residue is the desired product, a mixture of monoand di-substituted phosphoric acids having a phosphorus content of 9.98%.

To 352 grams (1.7 equivalents) of the above prepared phosphoric acid mixture in 184 grams of xylene, there is added below the surface of the solution 76.5 grams (1.7 equivalents) of dimethylamine below the surface of the solution over a period of 30 minutes while maintaining the reaction tempearture between 2038 C. The mixture is then warmed to 40 C. and filtered through a filter aid. The filtrate is the desired product containing 30% by weight of xylene and having a nitrogen content of 3.22% and a phosphorus content of 5.81%.

EXAMPLE 6 To 280 grams (1.35 equivalents) of the phosphoric acid mixture of Example 5 in 137 grams of xylene, there is added beneath the surface of the solution, 41 grams (0.915 equivalent) of dimethylamine over a period of 25 minutes while maintaining the reaction temperature between 2425 C. The mixture is then warmed to 40 C. and filtered through a filter aid. The filtrate is then desired product containing 30% by weight of xylene and having a phosphorus content of 5.87% and a nitrogen content of 2.79%.

EXAMPLE 7 A solution of 461 grams (1.0 equivalent) of di-tridecyl phosphoric acid in 200 grams of xylene is prepared and cooled to 25 C. whereupon 45 grams of dimethylamine is added below the surface of the solution over a period of 30 minutes while maintaining the reaction temperature between 25 -30 C. After stirring an additional 30 minutes, the solution is filtered through a filter aid. The filtrate is the desired product.

EXAMPLE 8 The procedure of Example 2 is repeated except that the tridecyl phosphoric acid is replaced by an equivalent amount of a hexadecyl phosphoric acid ester prepared by reacting 600 grams of hexadecyl alcohol (3 equivalents) with 142 parts of phosphorus pentoxide according to the procedure of Example 1.

EXAMPLE 9 The procedure of Example 1 is repeated except that 83 grams (1.42 equivalents) of methyl ethyl amine is used in lieu of the dimethylamine.

EXAMPLE The procedure of Example 1 is repeated except that the tridecyl phosphoric acid used to prepare the salt is prepared by reacting one equivalent of phosphorus pentoxide with 2 equivalents of tridecyl alcohol.

The salts of the organic subsituted phosphoric acid reactant and the aliphatic amine are soluble in gasoline and may be incorporated in a gasoline simply by mixing them with the gasoline at the desired concentration. Alternatively, they may be dissolved first in a combustible solvent, particularly a hydrocarbon solvent having a boiling point below about 250 C. such as nphtha, benzene, toluene, xylene, gasoline or light mineral oil to obtain a fluid concentrate and the concentrate can then be diluted with gasoline to obtain the final fuel composition. In many instances, it is convenient to form the salt in the final fuel composition by adding the acidic phosphorus reactant and the amine reactant to the fuel composition at suitable concentrations. The concentration of the salts in the final gasoline composition usually ranges from about 0.000l% to about 0.05% by weight. The preferred concentration is from about 0.002% to about 0.02%. A higher concentration than 0.05% may be used but this is ordinarily unnecessary.

It is believed that much of the bucking and stalling of carbureted gasoline engines, particularly during cool, humid weather, is caused by ice which forms near the circumference of the throttle plate. This ice restricts flow of the ari-gasoline mixture into the combustion chambers and causes an idling engine to stall. The utility of the compositions of this invention as anti-icing agents or gasoline is shown by a carburetor icing test performed in the laboratory using a 6-cylinder Chevrolet engine. In this test, air at 46 49 F. and 100% relative humidity is supplied by an air-conditioning and humidifying system to a Stromberg BXOV-2 single barrel carburetor mounted on an 18-inch vertical extension of the intake manifold of a 216 cubic inch 6-cylinder Chevrolet engine. A clear plastic spacer is inserted between the carburetor and the throttle body to permit the observation of ice formation during this test.

In preparation for the test the engine is supplied with fresh oil and new or clean spark plugs. The fuel system is purged and the throttle plate is washed with xylene. Timing of the engine is set at 5 DTC at 500 r.p.m. and the throttle stops are adjusted for the engine to idle at 500 r.p.m. and run at 1750 r.p.m.

During the test, the intake air dry bulb temperature, the intake air wet bulb temperature, and the fuel temperature are maintained at 46-49 F. while the carburetor throttle bore is maintained at 28 F.:1 F.

The test procedure is as follows:

1) The engine is run at 1750 r.p.m. until the throttle plate drops to 30 F.

(2) The engine is stopped until the throttle plate warms to 40 F.

(3) The engine and a stop watch are started simultaneously and the engine is run at 1750 r.p.m. until it appears that enough ice is built up to cause the engine to stall.

(4) The carburetor heater is turned off and the engine is run for an additional 20 seconds at 1750 r.p.m. The engine is then returned to idle at 500 r.p.m. for 10 seconds.

(5) If a stall occurs, steps 1 through 4 are repeated reducing the running time at 1750 r.p.m. by one-quarter minute increment until the engine will continue to run for 10 seconds at idle. If no stall occurs, steps 1 through 4 are repeated increasing the running time at 1750 r.p.m. by one-quarter minute increments until a stall occurs during the idle time of 10 seconds. If no stall occurs in 6 minutes of running time, the fuel is given a rating of 6+.

The engine is calibrated for testing with a base fuel and the base fuel plus 1% isopropyl alcohol. The engine is adjusted to stall with the base fuel after 1 /2 i A minutes of running for 1750 r.p.m., and to run between 5 and 6 minutes at 1750 r.p.m. before stalling when the base fuel contains 1% isopropyl alcohol.

The improved anti-icing characteristics obtained by incorporating the composition of this invention in a gasoline are clearly shown by the results given in the table.

TableEngine laboratory carburetor anti-icing test Improving agent in the Time in minutes at test gasoline (percent by wt.) 17 50 r.p.m. to stall None (control) 2.00; 2.00; 1.75; 2.00

19 0 5 I standard winter grade gasoline having a mid-point of In addition to the anti-icing additive herein described, the gasoline compositions of this invention may also contain conventional additives such as: anti-knock agents such as tetraethyl lead compounds; lead scavengers such as the haloalkanes; anti-oxidants such as 2,6-di-tertiarybutyl-4-methylphenol; rust inhibitors such as alkylated succinic acids; bacteriastatic agents; gum inhibitors; metal deactivators; upper cylinder lubricants; etc.

What is claimed is:

1. A fuel composition for internal combustion engines comprising a major amount of hydrocarbon fuel of the gasoline boiling range, and a minor amount sufiicient to inhibit ice formation of an amine salt prepared by reacting at a temperature of from about 0 C. to about 75 C., an aliphatic amine selected from the class consisting of secondary and tertiary amines having from 2 to 4 carbon atoms, with a phosphoric acid having the formula POOH R 0 wherein R is an aliphatic hydrocarbon radical having from 8 to 18 carbon atoms, and R is a radical selected from the class consisting of hydrogen and R.

2. The composition of claim 1 wherein the equivalent ratio of amine to phosphoric acid is within the range of from about 1:1 to about 1:2.

3. The composition of claim 1 wherein R is the tridecyl radical.

4. The composition of claim 1 wherein the amine is a secondary amine.

5. A fuel composition for internal combustion engines comprising a major amount of hydrocarbon fuel of the gasoline boiling range, and a minor amount sufficient to inhibit ice formation of an amine salt prepared by reacting at a temperature of from about 0 C. to about 75 C., a secondary amine having from 2 to 4 carbon atoms with from about 1 to 2 equivalents of a phosphoric acid selected from the class consisting of monoand di-tridecyl phosphoric acids and mixtures thereof.

6. The composition of claim 5 wherein the amine is dimethyl amine.

7. The composition of claim 5 wherein the phosphoric acid is a mixture of monoand di-tridecyl phosphoric acids.

8. A fuel composition for internal combustion engines comprising a major amount of hydrocarbon fuel of the gasoline boiling range, and a minor amount suflicient to inhibit ice formation of an amine salt prepared by reacting 2 equivalents of dimethyl amine with 3 equivalents of di-tridecyl phosphoric acid.

9. A fuel composition for internal combustion engines comprising a major amount of hydrocarbon fuel of the gasoline boiling range, and a minor amount sufiicient to inhibit ice formation of an amine salt prepared by reacting 2 equivalents of dimethyl amine with 3 equivalents of a mixture of monoand di-tridecyl phosphoric acids.

I 8 V 7 References Cited UNITED STATES PATENTS 9/ 1942 Thompson 4472 12/1958 Coutrell et' a1 4472 12/1958 Contrell etal. v 4472 12/1958 Cantrell et al.'.;. 4472 US. Cl. X.R.