US3155464A - Fuel composition - Google Patents

Description

United States Patent 3,155,464 FUEL COMPOSITION Richard L. Woodard, Walnut Creek, Califi, assignor to Shell Oil Oompany, New York, N.Y., a corporation of Delaware No Drawing. Filed May 29, 1961, Ser. No. 113,087 in Claims. (e1. 44-63} This invention relates to fuel compositions for internal combustion engines, especially gasoline, and more particularly to gasoline containing deposit modifiers or ignition control compounds of phosphorus and/or boron. The invention particularly relates to such fuel compositions which have improved characteristics with regard to octane number requirement increase of the engine in which they are used.

During the operation of internal combustion engines, a considerable amount of deposits accumulates on the various areas of the combustion chamber. This accumulation of deposits usually causes, or at least contributes to an increase in the octane number requirement of the engine. That is, whereas the clean engine is capable of essentially knock-free operation on a fuel of lower octane number, after the engine has been run for some time and has thus accumulated deposits in the combustion chamber, it then requires a fuel of higher octane number to maintain essentially knock-free operation. The character of combustion chamber deposits may vary widely and depends upon a large number of variables such as (l) manner in which the engine is run, (2) fuel composition, and (3) amount and character of the additives in the gasoline. The first of these three variables is not susceptible to strict control. The manner in which the engine is run is largely determined by the service to which an engine is subjected and the driving habits of the consumer. Fuel composition from a given refiner is not subject to wide variations since the fuel composition is governed mainly by octane number demands, blending characteristics of fuel components, and the economics of both these factors. However, both the performance characteristics of the fuel and the deposit tendencies of gasoline may be affected to a marked degree by the incorporation of additives.

Essentially all commercially available motor gasolines contain additives of various types. The most common of these are the tetraalkyllead antiknock compounds such as tetraethyllead and tetramethyllead, which are added in concentrations up to 4 cc. per U.S. gallon in motor gasoline and up to 6 cc. per U.S. gallon in aviation gasoline. Other organo-metallic ant-iknock additives which may be used are such materials as cyclopentadienyl nickel nitrosyl, methylcyclopentadienyl manganese tricarbonyl, iron pentacarbonyl, tris(acetylacetonate) iron, nickel Z-ethyl salicylate, bis(n-butyl salicylaldimine) nickel, vanadium acetylacetonate, ferrocenes and the like. However, because of the rise in criticality of ignition control problems such as pre-ignb tion, wild ping, and rumble or pounding, in modern automotive engines, better gasolines today also contain certain ignition control additives. The most effective of the ignition control additives in use currently, and those with which the invention is concerned, are compounds of phosphorus and, to a lesser extent, compounds of boron.

Phosphorus compounds which are useful as ignition control additives in leaded gasolines containing halohydrocarbon scavengers are alkaryl phosphates or phosphites as in U.S. patent to Yust et al., 2,889,212, issued June 2,

1959, alicyclic phosphates as shown in U.S. patent to Yust et al., 2,765,220, issued October 2, 1956, carbocyclic phosphorus compounds containing a direct carbon-tophosphorus bond as in U.S. patent to Yust et al., 2,828,195, issued March 25, 1958, esten'fied thiophosphates and thiophosphites containing at least one alkaryl Patented Nov. 3, 1964 ICC ester group as in U.S. patent to Yust et al., 2,843,465, issued July 15, 1958, tri-heterocyclic phosphates as in U.S. patent to Yust et al., 2,841,480, issued July 1, 1958, tri(beta-haloaliphatic) phosphites and phosphates as in U.S. patent to Kolka, 2,866,808, issued December 30, 1958, dimethyl monophenyl phosphates as in U.S. patent to Orloif et al., 2,911,431, issued November 3, 1959, dimethyl monophenyl phosphates as in U.S. patent to Orloif et al., 2,870,186, issued January 20, 1959, and alkyl phosphates and phosphites.

Among the boron compounds useful as additives for abnormal ignition control are oleophilic group-substituted heterocyclic compounds of boron and nitrogen as shown in U.S. patent to Scott et al., 2,821,463, issued January 28, 1958, cyclic esters of boric acid as in U.S. patent to Garner, 2,940,839, issued June 14, 1960, alkyl boronic acids as in U.S. patent to Darling, 2,710,251, issued June 7, 1955, and esters of alkane diols and boronic acids as in U.S. patent to Darling, 2,710,252, issued June 7, 1955.

Such ignition control additives do not generally reduce the amount of combustion chamber deposits but rather they modify the deposits in such a manner as to reduce abnormal ignition phenomena, e.g., by lowering the electrical or thermal conductivity of deposits. Furthermore, such additives do not significantly reduce the tendency of the octane number requirement of the engine to increase. Additives which either remove formed deposits or serve to prevent the deposition of materials on the various areas of the combustion chamber are referred to as octane requirement reduction agents (abbreviated ORR).

It is therefore an object of the invention to provide an improved internal combustion engine fuel composition having reduced tendency to form combustion chamber deposits. It is also an object of the invention to provide a fuel which will reduce the quantity of combustion chamber deposits which are laid down in such engines. It is a further object of the invention to provide an improved fuel composition which will have a reduced octane requirement at engine deposit equilibrium. A still further object of the invention is to provide a new method of reducing the octane number requirement of engines already containing substantial quantities of combustion chamber deposits. Another object of the invention is to provide an ORR agent with properties such that it will perform effectively in an internal combustion engine under varying conditions. Still other objects will become apparent in the description of the invention.

The attainment of these and other objects will be apparent from the detailed description of the invention, which, broadly stated, is an improved gasoline type hydrocarbon fuel for internal combustion engines containing an organo-metallic' antiknock compound, a surface ignition control additive and a small amount of nitrogen containing heterocyclic compound having at least 5 carbon atoms in the cyclic structure. In a more restricted aspect, it is an improved gasoline composition, having reduced tendency to cause increased octane number requirement in engines, containing an organo-metallic antiknock compound, a boron or phosphorus ignition control compound, and a small amount of a lactam having at least 5 carbon atoms and containing carbon, hydrogen, oxygen and nitrogen.

More specifically, the invention is an improved fuel composition for use in internal combustion engines consisting essentially of a stable gasoline composition containing an octane number-improving amount of or'ganometallic antiknock compound, a minor amount of an ignition control phosphorus or boron compound, or a mixture of two or more ignition control compounds, and from 0.05 to 5.0% by weight of a gasoline soluble cyclic amide or mixtures of cyclic amides containing only hydrogen and carbon atoms in addition to the amido-nitrogen 3 and oxygen atoms. These compounds may be represented by the following structural formula:

In the foregoing formula, each R can be a hydrogen atom or a low molecular weight radical containing from 1 to 4 carbon atoms inclusively, x is an integer from 1 to 2 with the proviso that when x equals 2 one of the Rs must be an alkyl group, the compound having from 5 to 14 carbon atoms. These materials can be further described as lactams, that is, as the nitrogen containing heterocyclic compound formed by the intrarnolecular condensation of an amino carboxylic acid and characterized by the grouping o H II I In a preferred embodiment of the invention, x equals 1 and all Rs are hydrogen, i.e., the lactam Z-piperidone is a preferred ORR agent of the invention. The above formula will be referred to hereafter as (I).

Specific examples of ORR agents of the invention include fl-methyl-e-caprolactam, i.e.

CHT-CHCH8 and S-butyl-Z-piperidone, i.e.

N CH1 CH (CH2) zCHz-CEE engine having a significant equilibrium octane requirement increase. It was further noted that the 7 membered lactam compounds of Formula I were ineffective as ORR agents unless the ring was substituted with one or more alkyl groups.

The surprising benefits which may be obtained from the use of the lactams of Formula I will be seen and the invention will be more fully understood from the following examples.

Example I A clean Oldsmobile CFR engine was operated on a commercial premium gasoline fuel containing 3 cc. per gallon (U.S.) of tetraethyl-lead as TEL Motor Mix and 0.3 T (theories) of phosphorus in the form of tricresyl phosphate. The octane number requirement of the clean engine was about 97 Research octane numbers. The octane number requirement of the engine rose in the first 20 hours of operation to about 99.5, declined slightly to 99 in the next 45 hours and then rose steadily to an equilibrium octane requirement of about 101 Research octane numbers (RON) at the end of the 170 hour period. At this time, 0.5% by weight of Z-piperidone was added to the fuel and the operation was continued for another 31 hours. During this latter period when the engine was operating on the same fuel to which the 2-piperidone had been added, the octane number requirement of the engine declined from 101 to a level of 98 at the end of 31 hours of operation. These results show a very dramatic decrease in octane number requirement resulting from the addition of the Z-piperidone to the fuel containing an ignition control additive.

The results indicate quite clearly that ONR increase of engines running on leaded gasolines containing ignition control additives may be reduced to an insignificant and unimportant level by the addition of only small amounts of the lactams of Formula I. In addition it has been found that the beneficial effects of the additive are retained for a significant period after the engine is switched to a fuel which does not contain the ORR additive.

It is not known whether the action of the lactams of Formula I is of purely physical nature or whether some chemical interaction of gasoline components also takes place. If the action of the compounds of Formula I were only that of a solvent it would be expected that similar materials having the same or higher solubility for lead salts would work as well.

Example II A number of organic compounds having analogous structures or which contained the same functional groupings, each having a solubility for PbCl of at least the same order of magnitude as the lactam compounds of the invention were tested in essentially the same manner as in the foregoing examples. The results were as fol- Since lead chloride, which is formed from the decompo sition of the tetraalkyllead and the ethylene dichloride scavenger, is a major component of combustion chamber deposits, it is evident that the ORR effect of the lactam compounds in accordance with the invention is not due to solvent power alone. Furthermore, the octane number requirement reduction properties of the class of the lactam compounds as defined hereinbefore is thought to result from an unexpected interaction with the ignition control additive in the gasoline. That is, though neither the lactam compounds of the invention, nor the ignition control additives exhibit any power to reduce octane number requirement in the absence of the other; however, When both are used in accordance with the invention, they co-act to reduce both octane number requirement and combustion chamber deposits as well.

In the foregoing example the lactams of Formula I were added into the combustion chamber by inclusion in small quantities in the fuel. When it is added in this manner, these materials should be present in the gasoline in concentrations of at least 0.05% by weight and preferably at least 0.1% by weight. Though concentrations as high as 5% by weight are effective to reduce ONR, concentrations over 1.0% by weight are undesirable because of adverse side effects, among which are the tendencies to form sludge and to plug the piston rings. To obtain the most effective results in a concentration of from about 0.1 to 0.6% by weight is preferred, a range of from about 0.3 to 0.5 being particularly preferred to obtain both maximum deposits removal and reduction in ONR.

Though addition of the compounds of Formula I to the combustion chamber by means of the gasoline is probably the most convenient method of utilizing the unique properties of the additive, in still another aspect of the invention it has been found that similar benefits may be obtained by adding the compound only intermittently, but in much larger concentrations, into the combustion chamber. Thus, a concentrated solution of the lactam additive in gasoline when added to the combustion chamber, for example, through the spark plug holes or through the intake valves of an engine which has been run for an extended time on a gasoline containing ignition control additive of boron and phosphorus and which contains equilibrium deposits from such operation, is effective to reduce octane number requirement therein. When at least 15 milliliters are added in the foregoing manner to each of the cylinders of an automobile engine, and the engine is then operated, a considerable portion of the deposits is removed and the octane number requirement of the engine is considerably reduced. Most elfective distribution of the lactarn additive and most effective results therefrom are obtained by rapidly accelerating the engine immediately after adding the additive concentrate. Moreover, the beneficial effect in ONR reduction is retained for a considerable period, for example, up to 100 hours of further operation, Without further addition of the additive concentrate. Though the foregoing amount of the additive concentrate may be added all at one time, it is preferable to add it in increments of, say 5-15 smaller dosages over a 30-60 minute period. In either case, when the lactam additive is added in the concentrated form, none of the additive is required in the principal fuel supply.

The concentrated solution of the additive should contain at least 25% by volume of the lactam additive in order to get significant benefits. However, the concentrate should not contain over about 75% by volume of the additive. At higher concentrations the effect of the additive is relatively low per unit of concentrate added due, in large part, to maldistribution to the various parts of the combustion chamber. Therefore, a 50/50 mixture of the lactam additive and diluent is preferred.

As diluent for the ORR additive concentrate any nonviscous readily burnable organic compound in which the additive is soluble may be used. However, for reasons of both economics and availability, it is preferred to use a hydrocarbon fuel therefor. When gasoline is used as the diluent, it may contain additives such as tetraethyllead and ignition control compounds; however, these are notrequired. 1 The ORR agents of Formula I were also found to be effective in multicylinder engines. See Example III.

Example III I A 1957 Cadillac engine (8 cylinders) was operated on a commercial premium fuel of the same type as used in The equilibrium octane requirement of the engine was reduced 1 ON after 37 hours of operation on a' similar fuel containing 0.5% byweight piperidone.

The fuel to which the additive is added is preferably a gasoline boiling in the range of about 30 F. to 600 F. and especially preferred is a gasoline having a boiling range from about 30 F. to 425 F. and preferably consisting mainly of hydrocarbons... However, the additives can also be added to diesel engine fuel comprising hydrocarbons boiling in the range of about 400 F. to 750 F. and to jet engine fuels comprising hydrocarbons boiling in the range of about 100 F. to 600 F. It will, of course, be recognized by anyone skilled in the art of fuels technology that the composition of the gasoline fuel is not at all critical as regards hydrocarbon type or the use of nonhydrocarbon constituents such as alkanols and alkyl ethers and the use of other types of additives. Thus any practicable stable motor gasoline fuel may be employed so long as it contains an operable amount of the ignition control additive, which will usually be from about 0.1 to 2.0 T when the ignition control additive is a phosphorus compound, and from about 0.5 to 10 T when the ignition control additive is a boron compound.

As applied to the phosphorus ignition control compound, the term theory designates the amountrequired to react stoichiometrically with the lead so that all of the lead atoms and all of the phosphorus atoms form Pb (PO As applied to the boron ignition control compound, the term theory designates the amount required to react stoichiometrically with the lead so that all of the-lead atoms and all of the boron atoms from Pb (BO It will, of course, be recognized that when other organo-metallic antiknock compounds which contain no lead are used, the term theory refers to the stoichiometric amount of phosphorus or boron which will react with the metal in the organo-metallic antiknock compound to form the analogous metal phosphates or orthoborates.

Besides the aforementioned ignition control compounds, lead scavengers, and organo-metallic antiknock compounds, the fuel compositions of the invention can, and ordinarily will, contain other additives, for example, dyes, oxidation inhibitorssuch as N,N'-ditertiarybutyl-4-methylphenol, metal activators such as N,N'-disalicylal-l,2-propanediamine, and rust inhibitors such as polymerized linoleic acidsand N,C-disubstituted imidazolines, and the like. In addition, the fuel compositions of the invention may also contain small amounts of various supplemental or co-antiknock compounds which are employed to enhance the antiknock action of the primary antiknock additives. These co-antiknock compounds may be organometallic in nature, such as iron pentacarbonyl, methyl cyclopentadienyl manganese tricarbonyl, and cyclopentadienyl nickel nitrosyl, or they may be primarily organic in nature, such as tertiary butyl acetate.

The following are illustrative examples of compositions suitable for use according to the invention:

Example IV I Gasoline containing tetraethyllead, 1.0 theory ethylene dibromide, 0.3 theory tricresyl phosphate, and 0.5% by weight 2-piperidone.

Example V Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide,. 1.0 theory ethylene dichloride, 1.52 theories of his (2-methyl-2,4-pentanediol) meso-borate, 0.18 theory of tricresyl phosphate, and 0.25% by weight N-methyl (-s) .caprolactam.

Example VIII Gasoline containing tetraethyllead, 0.3 theory tricresyl phosphate, and 0.5% by weight 5-methyl-2-piperidone.

I Example IX Gasoline containing methylcyclopentadienyl manganese tricarbonyl, 0.3 theory tricresyl phosphate, and 0.5% by Weight fi-methyLs-caprolactam.

Example X Gasoline containing tetraethyllead, 0.3 theory tricresyl phosphate, 1.0 theory ethylene dibromide, and 0.4% by weight of N-methyl-Z,S-dimethyl-Z-piperidone.

Example XI Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, and 1.0% by weight of N-butyl (e) caprolactam.

Example XII Gasoline containing tetraethyllead, 0.2 theory tris (chloropropyl) thionophosphate, and 0.3% by weight N-methyl--ditertiarybutyl-2-piperidone.

Example XIII Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.2 theory tricresyl phosphate, and 0.8% by weight 2-piperidone.

Example XIV Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.3 theory tri- (chloroethyl) phosphate, and 0.5% by weight of N-propyl (-s) caprolactam.

Example XV Gasoline containing tetraethyllead, 0.5 theory ethylene dibromide, 1.0 theory ethylene dichloride, 0.4 theory cresyl diphenyl phosphate, and 0.05% by weight 3,4-dimethyl-2-piperidone.

It is to be understood that the order of mixing the various constituents of the compositions of the invention in gasoline is immaterial. For example, the ORR agent of Formula I may be added to gasoline which already contains ignition control and antiknock compounds. Likewise, the ORR agent, ignition control compound and an antiknock compound may be first mixed, stored and handled as a concentrate and added to the gasoline at a later time. A gasoline additive concentrate of this latter type may also contain halogen scavenger compounds and other additives. Under some circumstances it may be desirable to mix the halogen scavenger and the antiknock compound with the ORR compound of Formula I in the desired relative proportions and handle or store this mixture with or without stabilizers, anti-fouling compounds, inhibitors, etc., as a concentrate for incorporation with the other components of the ultimate fuel composition.

I claim as my invention:

1. An improved fuel composition for use in internal combustion engines consisting essentially of a stable gasoline boiling between about 30 F. and about 425 F. containing an octane-number-improving amount of an organometallic antiknock agent, a minor amount of an ignition control deposit modifying compound selected from the group consisting of compounds of phosphorus, boron and mixtures thereof, and an octane requirement reducing amount of a gasoline soluble heterocyclic compound containing from 5 to 14 carbon atoms and having the structural formula:

wherein R is selected from the group consisting of a hydrogen atom, a low molecular weight alkyl radical con- (J taining from 1 to 4 carbon atoms, x is an integer from 1 to 2 with the proviso that when x equals 2 one R is an alkyl group.

2. An improved fuel composition for use in internal combustion engines consisting essentially of a stable gasoline boiling between about 30 F. and 425 F. containing an octane number-improving amount of a tetraalkyllead antiknock agent, a minor amount of an ignition control additive selected from the group consisting of compounds of phosphorus, boron, and mixtures thereof, and from 0.05 to 5.0% by weight of gasoline soluble heterocyclic compound containing from 5 to 14 carbon atoms and having the structural formula:

wherein R is selected from the group consisting of a hydrogen atom, a low molecular weight alkyl radical containing from 1 to 4 carbon atoms, x is an integer from 1 to 2 with the proviso that when x equals 2 one R is an alkyl group.

3. The composition of claim 1 which contains from 0.05 to 1.0% by weight of the heterocyclic compound.

4. The composition of claim 1 in which the heterocyclic compound is ,8-methyl-(e)-caprolactam.

5. The composition of claim 1 in which the heterocyclic compound is 5-methyl-2-piperidone.

6. The composition of claim 1 in which the organometallic primary antiknock agent is methylcyclopentadienyl manganese tricarbonyl.

7. The composition of claim 2 in which the organometallic primary antiknock agent is tetraethyllead.

8. The composition of claim 2 in which the organometallic primary antiknock agent is tetramethyllead.

9. An improved fuel composition for use in internal combustion engines consisting essentially of a stable gasoline boiling between about 30 F. and 425 F. containing an octane number-improving amount of an organo-metallic primary antiknock agent and from 0.05 to 5.0% by weight of an alkyl-substituted Z-piperidone compound.

10. A new method for reducing combustion chamber deposits and octane number requirement of engines containing combustion chamber deposits formed during operation of the engine on gasoline fuel containing an ignition control additive selected from the group consisting of compounds of phosphorus, boron, and mixtures thereof, which comprises adding at least 15 milliliters of a gasoline fuel, containing dissolved therein from about 25 to about by volume of an alkyl-substituted 2-piperidone compound, directly to the combustion chambers of said engine and operating the engine.

References Cited in the file of this patent UNITED STATES PATENTS 1,908,705 Jaeger May 16, 1933 2,784,191 Fischer et a1. Mar. 5, 1957 2,806,847 Nedwick Sept. 17, 1957 2,806,848 Nedwick Sept. 17, 1957

Claims (1)

1. AN IMPROVED FUEL COMPOSITION FOR USE IN INTERNAL COMBUSTION ENGINES CONSISTING ESSENTIALLY OF A STABLE GASOLINE BOILING BETWEEN ABOUT 30*F. AND ABOUT 425*F. CONTAINING AN OCTANE-NUMBER-IMPROVING AMOUNT OF AN ORGANOMETALLIC ANTIKNOCK AGENT, A MINOR AMOUNT OF AN IGNITION CONTROL DEPOSIT MODIFYING COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF PHOSPHORUS, BORON AND MIXTURES THEREOF, AND AN OCTANE REQUIREMENT REDUCING AMOUNT OF A GASOLINE SOLUBLE HETEROCYCLIC COMPOUND CONTAINING FROM 5 TO 14 CARBON ATOMS AND HAVING THE STRUCTURAL FROMULA: