US2643942A - Fuel composition containing nu, nu'-dimethyl phenylene diamine to prevent knocking - Google Patents

Description

Patented June 30, 1953 FUEL COMPOSITION CONTAINING N,N-DI- .METHYL PHENYLENE DIAMINE TO PRE- VENT KNOCKING Maurice It. Barusch, Richmond, Calif., assignor to California Research Corporation, San'Francisco, Calif., a corporation ofrDelaware No Drawing. Application September 19, 1949,

1 Serial No. 116,640

This invention relates to spark-ignition engine fuels; more particularly, to spark-ignition engine fuels boiling in the gasoline boiling range and having improved anti-knock characteristics and stability in the presence of light, and to a method of producing such fuels. In an attempt to reach a level of higher power output of a gasoline engine before knocking occurs, it has become the practice to supercharge the engine. However, supercharging, as a means of obtaining increased power output, is limited. A given fuel can tolerate only a limited amount of supercharging beyond which limit it knocks excessively. By employing rich fuel-air mixtures, that is, fuel-air mixtures in which the proportion offuel to air is such that there is a complete combustion of the fuel, a greater amount of supercharging can be tolerated with a given fuel than if a lean mixture is employed. This expedient also has its limitations in that when a certain richness is reached, the engine misfires and power output drops off.

In an effort to increase the power output still further before knocking occurs, numerous antiknock agents are added to the base fuel. Tetraethyl lead is one of the most important of the anti-knock agents which have been added to spark ignition-engine fuels. Other agents which have been proposed are, for the most part, less effective than tetraethyl lead, and are more expensive. Despite the advantages of tetraethyl lead, its use is disadvantageous owing to several factors, such as its toxicity and its tendency to deposit lead compounds in carburetors,.manifolds, valves, cylinders or exhaust pipes.

In still further efforts to increase the power of fuels before knocking occurs, special base fuels,

are manufactured by cracking, isomerization of straight-chain to branched-chain hydrocarbons, and alkyla'g'iion of isoparafiins with oleiins. Judicious blending of stocks so prepared with one another, or with straight-run distillates, has also contributed to upgrading base fuels. Even when anti-knock agents have been added to special base fuels, these fuels have not had sufi'icient anti-knock capacity to obtain the amount of power desired in such instances as airplane takeoffs and rapid ascents.

Even by combining the advantages oftetra ethyl lead, superior base stocks and rich fuelair mixtures, it is difficult to meet the desired aviation fuel requirements such as desired in'the take-off of heavily loaded aircraft.

Fuels of the gasoline type have been rated by the CFR-ASTM-D357-43T method and the? CFR-ASTM-Dfil-437 method. These methods are commonly known as the FF-2, and F-37.

9 Claims. (Cl. 44-56) 2 methods, respectively. The failure of the above methods to rate fuels dependably for certain purposes has led to the development of another method, designated as the CFR-AFD-F l-443 method, commonly called the F- l method;

A fuel which meets the requirements described hereinabove is disclosed in pending application ofFir-ey et al., Serial No. 792,349, now abandoned. This application discloses a fuel composition for spark-ignition engines containing N-methylat'edphenylene-diamines added in an amount sufficient to increase substantially the anti-knock value of the fuel. While the fuel compositions disclosedin the Firey et a1. application are'fuels having unusually superior properties, they are not ideal in all respects.

of the additives disclosed in the Firey et al. 'application, is exposed to daylight, a haze formation occurs with subsequent deposition of a tarry-like precipitate.

It is an object of this invention to provide a fue1 suitable for compression-ignition engines containing N,N'-dimethyl-p-phenylene diamine in suflicient amount substantially to raise the anti-knock value of the fuel which does not form a haze upon exposure to light.

It is another object of the present invention to provide a method of obtaining a light-stable fuel composition containing anti-knock or octane improving additives including N,N-dimethyl-pphenylene diamine.

It is a particular object of this invention to provide a light-stable rich-mixturefuel.

Anotherobject of this invention is to provide; a light-stable fuel containing N,N'-dimethyl-p phenylene diamine that does not plug fuel-line filters.

It has been discovered that a motor fuel containing N,N'-dimethyl-p-phenylene diamine in a sufficient amount substantially to increase the molecule.

The base fuel may be any hydrocarbon fuel boiling in the gasoline boiling range, that is, having an ASTM (D-86') distillation with an initial boiling point of about F. and a final boiling Y point of about 400 F. The base fuel may be run petroleum distillate, a cracked-petroleum dis- It has been found that when a fuel containing N,N'-dimethy1-p-phenylene diamine; one

tillate, an alkylate (such as sulfuric acid or HF isoparaffin-olefin alkylate), an aromatic fuel or a blend of two or more-of the above fuels. Most advantageously, a base fuel is employed boiling within the range above prescribed, which is de 5 rived from petroleum. The fuel should not oxidize readily upon standing, forms gums or poly- V merization products, or loses color upon standing, and should have an octane rating not less than about 80 (by the F-2 method).

The base fuels may or may notcontain tetraethyl lead. The unleaded fuels offer the advantage of improved anti-knock ratings without the deleterious effects of tetraethyl lead. On the other hand, the leaded fuels are especially useful as high-octane fuels. As N,N-dimethylpphenylene diamine may be used to obtain ahighoctane fuel and only small amounts Of tetraethyl leadare required in this fuel, the present invention obviates the disadvantages inherent in the use of;large quantities of lead (such as the deposition of lead compounds in carburetors, manifolds, valves, cylinders or exhaust pipes, and the toxicity of lead) The additives which inhibit haze formation in fuels containing N,N'-dimethyl-p-phenylene diamine are alcohols, ketones, or mixtures thereof. The alcohols may have 2 through 4 carbon atoms in the molecule, such as: ethyl alcohol; propyl alcohol; isopropyl alcohol; n-butyl alcohol; isobutyl alcohol; secondary butyl alcohol; tertiary butyl alcohol; and mixtures thereof.

The ketones in this-invention have 3 through'B carbon atoms'in themolecule. The ketones may be straight-chained, branch-chained and cyclic orwa mixture of these three types of ketones such asacetone; diethyl ketone; methyl ethyl ketone; dibutyl ketone; di-isobutyl ketone; cyclohexanone, etc; and mixtures thereof.

The N,N'-dimethyl-p-phenylene diamine is used in amounts sufficient to improve the antiknock value (the octane number) of the sparkignition engine fuel; amounts: ranging from about 0.1 to about 10 per cent by weight, based on finished fuel, have been found desirable: while amounts not less than about 0.3 per cent are generally preferred.

The amount of the additive added to a fuel containing N,N-dimethyl-p-phenylene diamine should be sufiicient to light stabilize the fuel against the formation of haze. The haze-inhibiting additive may be used in amounts such that theblended fuels containat least 2 per cent (by weight of the blended fuel) of the additive. The amount of the agent present in the blended fuel is generally 2 through 10 per cent by weight of the blended fuel with 2 through 4 per cent being generally preferred.

Blendingof the diamine, the additive, and the base fuel may be accomplished by mixing the three components in a container and using such heat and/or agitation as may be necessary, or a concentrate may be formed from the diamine and theradditive and then the concentrate may be blended with the base fuel.

In addition to anti-knock agents, the fuel composition may contain gum inhibitors in amounts of about 0.001 to about 0.05 weight per cent such as N-n butyl -para-amino phenol, N-isobutyl para-amino phenol, and 2,6-ditertiary butyl-qmethyl phenol, etc. Also, the fuel may contain metal deactivators in small amounts such as 0.001 to about 0.05 weight per cent such as N,N'-disalicylidene-1,2-diamino propane, various corrosion inhibitors, and coloring agents, etc.

When tetraethyl. lead is used in the fuel composition, it is often necessary to add stabilizers for the tetraethyl lead compound.

The mechanism by which the haze forms in a N,N-dimethyl-p-phenylene diamine-containing fuel is not clearly understood. It is thought that once this haze begins to form, continued haze formation may occur even in the absence of sunlight.

In. order to better understand this invention, the following example is given:

EXAMPLE A base fuel containing 35 per cent isoparafiinic alkylate, '7 per cent isopentane, and, 58 per cent Midway California straight-run gasoline (composed essentially of naphthene and parailin hydrocarbons and containing less than 5 volume per cent of aromatic hydrocarbons) was blended both with 0.1 per cent and 0.5 per cent N,N'-dimethylp-phenylene diamine. A cc. sample of each blend was added, in a dark room, to a series of glass test tubes set in a shielded rack. One tube from each of the blends was set asideand to eachof the others was added varying amounts of methyl alcohol, diethyl ether, n-butanol, ethyl alcohol, methyl ethyl ketone, di-isobutyl ketone, tertiary butyl alcohol and acetone. This was likewise done in a dark room. The color of each of the tubes was observed. Then all Of the samples were placed in the bright daylight (mid-day) and the color was observed after 10 and 20 min- 1 utes.

The table which follows is a tabulation of the results obtained:

Table .Percent of .N,N-di methyl-p- 'phenylene v mine added Color Upon Exposure to Day-- g t, ime

Amount (Percent) Compound Added 20 Min.

Tertiarybutyl a1cohol None Methyl alcohol n-but ol Ethyl Methyl ethyl ketone Dlethyl ether Di-isobutyl ketone Acetone Tertiary butyl alcohol-.. None Very dark. D

Di-isohutyl ketone Acetone Methyl ethyl ketone..-" Methyl'alcohol Very dark.

Hazy.

. Very dark.

OOOOOOOO OQOQOOOOO Diethyl ether The table clearly shows that a fuel containing N,N-dimethyl-p-phenylene diamine will become hazy upon exposure to daylight. Likewise, this table shows that methyl alcohol and cliethyl ether will not inhibit the formation of the haze. Ethyl alcohol, n-butanol, methyl ethyl ketone, diisobutyl ketone and acetone, as is shown, prevented the formation of the haze; The tertiary butyl alcohol, also, as can be seen from the table, has an inhibiting effect. The substance, that formed in the fuels with or without methyl alcohol or diethyl'ether after minutes of exposure to daylight appeared to be a tar-like precipitate.

It is believed that the haze and the tar-like precipitate that forms in fuels containing the phenylene diamine may possibly be an oxidized form of the N,N-dimethyl-p-phenylene diamine. Thus, it can be seen that if substantial amounts of this haze or precipitate form in a fuel, reduction of the octane number of the fuel may occur. The ketones and alcohols, containing at least 2 carbon atoms per molecule, inhibit the formation of haze in a diamine-containing fuel and render a fuel that is stable in the presence of daylight.

The fuel composition of this invention may be used as an aviation fuel or automobile fuel, or as a fuel in other types of spark-ignition engines.

While the fuel of this invention is especially desirable for usage under rich-mixture and supercharging conditions, it may likewise be used under lean-mixture conditions.

While various specific embodiments of the invention have been illustrated and described, many modifications and adaptations maybe made without departing from this invention, and all such changes as are included within the scope of the claims are embraced thereby.

I claim:

1. A light-stable fuel comprising a major portion of hydrocarbons boiling in the gasoline boiling range, a minor portion above 0.1% of N-,N'- dimethyl-p-phenylene diamine sufficient substantially to increase the octane rating of said hydrocarbons, and a minor portion of 2-10% of at least one material selected from the group consisting of alcohols containing 2 through 4 carbon atoms per molecule and ketones containing 3 through 8 carbon atoms per molecule sufiicient substantially to prevent formation of haze from said phenylene diamine in said hydrocarbons upon exposure to daylight.

2. The light-stable fuel of, claim 1, wherein said material is ethyl alcohol.

3. The light-stable fuel of claim 1, wherein said material is methyl ethyl ketone.

4. The light-stable fuel of claim 1, wherein said material is acetone.

5. A light-stable fuel comprising a major ill portion of hydrocarbons boiling in the gasoline boiling range, above 0.1 to 10% by weight of N,N'-dimethyl-p-phenylene diamine suflicient substantially to increase the octane rating of said hydrocarbons, and 2 to 10% by weight of at least one material selected from the group consisting of alcohols containing 2 through 4 carbon atoms per molecule and ketones containing 3 through 8 carbon atoms per molecule sufficient substantially to prevent formation of haze from said phenylene diamine in said hydrocarbons upon exposure to daylight. I

6. The light-stable fuel of claim 5, wherein said N,N'-,dimethyl-p-phenylene diamine is present in an amount not less than 0.3 per cent by weight.

7. The light-stable fuel of claim 5, wherein said material selected from the group consisting of alcohols and ketones is present in an amount of 2 to 4 per centby weight.

8. A light-stable gasoline comprising a. major portion of hydrocarbons boiling within the gasoline boiling range selected from the group consisting of isopentane, alkylate, straight run gasoline, aromatics, isoparafilnic alkylate, and above 0.1 to 10% of N,N'-dimethyl-p-phenylene diamine suflicient substantially to increase the octane rating of said hydrocarbons, and a minor portion of 2 to 10% of at least one material selected from the group consisting of alcohols containing 2 through 4 carbon atoms per molecule and ketones containing 3 through 8 carbon atoms per molecule sufiicient substantially to prevent formation of haze from said phenylene diamine in said hydrocarbons upon exposure to daylight.

9. In a fuel composition comprising hydrocarbons boiling in the gasoline boiling range and above 0.1% of N,N-dimethyl-p-phenylene diamine sufiicient substantially to increase the octane rating of said hydrocarbons, the improvement which comprises rendering said composition light stable by adding at least 2% by weight of at least one material selected from the group consisting of alcohols containing 2 through 4 carbon atoms per molecule and ketones containing 3 through 8 carbon atoms per molecule suflicient substantially to prevent formation of haze from said phenylene diamine in said hydrocarbons upon exposure to daylight.

. MAURICE R. BARUSCH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,571,862 Midgley Feb. 2, 1926 1,690,988 Marley et a1. Nov. 6, 1928 2,120,244 Dryer June 14, 1938 2,443,569 Ruggles June 15, 1948 2,487,909 Von Bramer Nov. 15, 1949 2,504,361 Van Hartesveldt Apr. 18, 1950

Claims (1)

1. A LIGHT-STABLE FUEL COMPRISING A MAJOR PORTION OF HYDROCARBONS BOILING IN THE GASOLINE BOILING RANGE, A MINOR PORTION ABOVE 0.1% OF N,N''DIMETHYL-P-PHENYLENE DIAMINE SUFFICIENT SUBSTANTIALLY TO INCREASE THE OCTANE RATING OF SAID HYDROCARBONS, AND A MINOR PORTION OF 2-10% OF AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALCOHOLS CONTAINING 2 THROUGH 4 CARBON ATOMS PER MOLECULE AND KETONES CONTAINING 3 THROUGH 8 CARBON ATOMS PER MOLECULE SUFFICIENT SUBSTANTIALLY TO PREVENT FORMATION OF HAZE FROM SAID PHENYLENE DIAMINE IN SAID HYDROCARBONS UPON EXPOSURE TO DAYLIGHT.