US3481717A - Gasoline composition - Google Patents

Description

United States Patent Int. Cl. C101 1/26 U.S. CI. 4469 2 Claims ABSTRACT OF THE DISCLOSURE A leaded gasoline containing a combination of a zinc phosphate salt and a non-metallic phosphate salt.

This application is a continuation of application Ser. No. 609,273, filed Jan. 9, 1967, now abandoned, and which is a continuation of application Ser. No. 427,152, filed Jan. 21, 1965, which is a continuation-in-part of application Ser. No. 272,227, filed Apr. 11, 1963, now abandoned.

The present invention relates to petroleum distillate fuel compositions which when employed in spark ignition engines lead to improvements in octane requirement increase, rumble and spark plug fouling.

One of the chief disadvantages attending the use of known additives to lessen abnormal combustion of gasoline in, for instance, automobile engines, is that they increase the nature and amount of deposits within the combustion space. This effect takes on greater importance in the case of the higher compression ratio engines in which the combustion space is relatively small. A fuel having an octane' number appropriate to the designed engine compression ratio is therefore unable to give the same anti-knock performance after the formation of such extensive deposits. To obtain the intended anti-knock performance requires a fuel of higher octane number; and this effect has become known as the octane requirement increase or ORI of the engine.

Various commonly employed gasoline additives as for example, phosphate compounds such as tricresyl phosphate, cresyl diphenyl phosphate etc., although known to improve rumble and spark plug fouling, have no effect with respect to decreasing the octane number requirement increase and many even have an adverse effect.

It has now been found that leaded gasolines having added thereto small amounts of each ofcertain gasolinesoluble organic phosphorus compounds and the gasolinesoluble metal salts, i.e. Group II-B metals of 30 to 80 atomic number, of certain phosphorus compounds, surprisingly provides a composition having an improved octane number requirement increase. The Group IIB metals of 3 0 to 80 atomic number are zinc, cadmium and mercury. The results obtained when using these additives are unexpected in that the metal salt component of the combination when present alone in the base fuel, that is, without the phosphate component, adversely affects the octane requirement increase and moreover, increases rumble and spark plug fouling. It has further been found that the combination of additives employed in the present invention in addition to decreasing the oc-- mercury salts of which constitute the additives of the present invention, have the following formula:

R0 OH wherein R is a hydrocarbon radical of up to about 30 or more carbon atoms on the average, often at least about 5 and preferably about 8 to 18 carbon atoms, and R is hydrogen or R. R can be an aliphatic, aromatic or mixed aliphatic-aromatic radical and is preferably nonolefinic and non-acetylenic, i.e. having adjacent carbon atoms no closer than 1.40 A. The total number of carbon atoms in a molecule of the phosphorous compound is preferably up to about 40 or even up to about 30 and the metal salt of the phosphorous compound is soluble in gasoline at least to the extent employed in this invention.

The phosphorous compounds from which the metal salts of the invention are made can be obtained by methods known to the art as, for instance, by reacting aliphatic alcohols, including cycloaliphatic alcohols, or aromatic hydroxy compounds with P 0 The preferred a1- cohols are alkanols which can be straight or branch chained and alkyl-substituted phenols whose alkyl substituents contain a total of up to 18 carbon atoms, and preferably are lower alkyl, especially methyl. The aromatic hydroxy compounds and aliphatic alcohols may be substituted with non-deleterious groups. Illustrative of suitable alcohols are pentanol, butanol, octanol, isooctanol, Z-ethyI-heptanol, dodecanol, oleyl alcohol, octadecyl alcohol, tetradecyl alcohol, alcohols prepared by the 0x0 process, phenol and alkylated phenols such as cresol, xylenol, propyl phenol, butyl phenol, dibutyl phenol, monoamylphenol, diamyl phenol, decyl phenol, dodecyl phenol, tetradecyl phenol, hexadecyl phenol and octadecyl phenol.

The reaction of the alcohol and P 0 to prepare the partial esters can be conducted by heating the reactants at temperatures of from about C. to about C. for a period of time sufficient to effect substantially complete reaction, usually about 1 to 15 hours. An inert solvent such as toluene, xylene or the like may be used to facilitate the reaction. A suitable molar ratio of alcohol to P 0 may be about 3: 1.

The ester products thus produced can be, for instance, monoalkyl, dialkyl, monoaryl or diaryl esters of phosphoric acid or any combination thereof. The mixed esters are often present, for instance, in a mole ratio of at least about 25% of each, say about 60 to 40% monoester: 40 to 60% diester. The metal salts of the esters can be prepared by directly reacting the esters with the zinc, cadmium or mercury carbonate or acetate. Either the metal of the acidic component of the salts may be used in excess and either the monoor di-partial ester salts may be employed but they are conveniently prepared and made available as the mixed ester salts.

The second additive of the present invention is a gasoline-soluble phosphorus compound having the formula:

wherein R has the value described above with respect to the phosphorous compounds from which the zinc, cadmium and mercury salts of the invention are made; R is hydrogen or R and n is an integer of to 1. R is preferably an aromatic, e.g. phenyl, hydrocarbon radical of 6 to 12 carbon atoms and can be substituted as, for instance, with lower alkyl groups say of 1 to 4 carbon atoms. Thus, the phosphorous compound can be a mono-, di-, or triester, or mixture of such and is preferably a triester. We also prefer to employ a phenyl, alkyl phenyl or a mixed phenyl-alkyl phenyl ester of phosphorous. Thus, one or more of the ester groups is preferably an alkyl phenyl radical, often of about 7 to 15 carbon atoms. See US. Patent No. 2,889,212 for a further list of the useful phosphates and phosphites.

These auxiliary phosphate and phosphite additives can be prepared by reacting the appropriate alcohol or phenol with phospheric acid to make the phosphate or with phosphorous trichloride to form the phosphite. Illustrative of suitable alcohols and phenols are those mentioned above in the description of the phosphorous esters used to form the metal salts of the invention. Examples of suitable alkyl phenols are ortho, metal and para cresol, 2,4- and 2,5-xylenol; 2,4-dimethyl-6-tertiary butylphenol; octyl and nonyl phenols, etc.

By the term leaded gasoline to which the additives of the present invention are incorporated is meant petroleum hydrocarbon fractions boiling primarily in the gasoline hydrocarbon range, usually about 100 to 425 F., having added thereto a small amount, generally between about 1 to 6 cc. per gallon of a tetra-lower-alkyl lead compound as an anti-knock agent. The gasolines are usually composed of a major amount of blends of hydrocarbon mineral oil fractions boiling primarily in the aforementioned range and will contain varying proportions of parafiins, olefins, naphthenes and aromatics derived by distillation, cracking and other refining and chemical conversion processes practiced upon crude petroleum fractions. Straight run gasolines, gasolines derived from cracking gas oil, gasolines or reformate from reforming straight run naphtha over a platinum-alumina catalyst in the presence of hydrogen, etc., are components frequently used in making up a gasoline composition. A typical premium gasoline, besides containing a small amount of a tetra-lower-alkyl lead compound as an antiknock agent may also contain small amounts of other non-hydrocarbon constituents used to impart various properties to the gasoline in its use in internal combustion engines, e.g. scavengers, corrosion inhibitors, etc. Such gasolines frequently have a Research Method octane number of about 90 to 105 and a Motor Method octane number of about 80 to 98.

The zinc, cadmium, or mercury salt additive component of the invention added to the leaded gasoline is incorporated in amounts sufiicient to provide a composition exhibiting an improved octane number requirement increase. The actual amount of each additive employed will vary depending upon the particular gasoline employed, its lead content, etc. In any event, sufiicient of the metal salt is employed to supply 0.002 to 0.4 or even 0.8, preferably 0.025 to 0.3, millimole or milligram atoms of the metal per gallon of gasoline. The additive will usually provide the gasoline with 0.00004 to 0.008 gram of one or a combination of the metals as the salts per gram of lead, preferably 0.0005 to 0.006 gram of the metal per gram of lead. This often means that about 0.5 to 15 or 30 pounds or more of the metal salt per 1000 barrels of gasoline is added. The phosphate or phosphite additive is usually added in an amount of about 0.05 to 0.5 theory, preferably about 0.2 to 0.3 theory, based on the lead content of the gasoline. The term theory as applied to the amount of the second phosphorous additive means the amount required to react stoichiometrically with the lead so that all of the lead atoms and all of the phosphorous atoms form Pb (PO 4, The following examples are given to illustrate the advantages provided leaded gasolines by the combination of additives of the present invention.

5 EXAMPLE I A sample of a base gasoline was obtained which was composed of 25 vol. percent straight run naphtha, 25 vol. percent light catalytically cracked gasoline, 25 vol. percent butane-butylene alkylate and 25 vol. percent reformed naphtha. The base gasoline contained 3 cc. per gallon of TEL as Motor Mix (TEL Motor Mix contains 59.2% tetraethyl lead, 13.0% ethylene dibromide, 23.9% ethylene dichloride and 3.9% hydrocarbon diluent dyes etc.). The base gasoline when containing the tetraethyl lead had an API gravity of 61.2, an octane number of 100 by the Research Method and an octane number of 91.5 by the Motor Method. The ASTM distillation of the gasoline was as follows:

IBP 93 Into a portion of the gasoline was added the zinc salt of mixed approximately 50% monoand approximately 50% di-C oxo esters of phosphoric acid in a concentration that provides 10 lbs. of the ester per 1000 barrels of the leaded gasoline. The gasoline blend was then tested in a 1962 Model Chevrolet engine and the octane requirement increase, rumble and power loss from spark plug fouling was determined. The results are shown in Table I below.

TABLE I Octane Requirement Spark Plug (Research) Rumble Fouling Rpm. 3,000 LIB No.*/ Percent R.p.m. 1,500 R.p.m. 2,500 R.p.m. Power Loss Base plus Base plus 1321s; plus Base plun *A measure of the rumble tendency of an engine after a given time 0 use. The number represents the percent isooctane required in a blend with benzene after a given period of engine operation using the fuel under test, to avoid rumble at a given r.p.m., e.g. 2,000 r.p.m. The test procedure comprises stopping the gasoline to the engine at any given period of engine operation and employing as a fuel to the engine a fuel containing a certain percent of isooetane in an isooctane-benzene blend (containing 3 co. TEL/gal.), manually opening the throttle at a given rate and recording the rpm. at which rumble occurs, if any in fact occurs. The faster you are able to run the engine with the lowest percent of isooetane in the blend the better the rumble resistance of the engine. Thus, the lower the LIE number the better the rumble characteristics of the engine.

EXAMPLE II Into a sample of the leaded gasoline blend employed above in Example I, i.e. containing 10 lbs. of the Zn salt of the mixed monoand di-C oxo esters of phosphoric acids/1000 bbls. of gasoline, was added 0.2 theory of cresyl diphenyl phosphate (CDP). This blend was similarly tested. The results are shown in Table II below:

EXAMPLE III To a leaded base gasoline identical in composition to that employed in Example I was added 0.2 theories of cresyl diphenyl phosphate and the blend was tested as in Example I and II. The results are shown in Table III below:

TABLE III Octane Requirement Spark Plug (Research) Rumble Fouling R.p.m. 3,000, Test LIB No./ Percent Hours Rpm. 1,500 R.p.m. 2,500 R.p.m. Power Loss The data of the above tables establish the following: Table III shows that the addition to leaded gasolines of the cresyl diphenyl phosphate alone to the leaded base gasoline gave an ORI of 4, a rumble of 60 LIB and a power loss through spark plug fouling of 4.9%. It is known that cresyl diphenyl phosphate improves rumble and spark plug fouling but that it has no efiect on octane requirement increase. Table I shows that addition of the zinc salt component of the present invention to leaded gasoline not only adversely afiects octane requirement increase but the rumble and spark plug fouling ratings were bad. Surprisingly, however, as shown by the data of Table 11 when the combination of components is employed not only was an improvement in octane requirement increase obtained but rumble and spark plug fouling are reduced as well.

EXAMPLE IV A gasoline composition exhibiting similar properties to that of Example 11 can be prepared by adding to the base gasoline of Example II a zinc salt of approximately 50% monoand approximately 50% di-C oxo esters of phosphoric acid in a concentration of lbs. of the ester per 1000 barrels of the gasoline and 0.2 theory of cresyl diphenyl phosphite.

EXAMPLE V One mole of mixed approximately 50% monoand approximately 50% di-C oxo esters of phosphoric acid was reacted with one mole of phenyl mercuric acetate in a hydrocarbon solvent. The reaction was carried out at 50 C. for one hour, then filtered. The hydrocarbon solubles were water-washed several times and the resulting phenyl mercuric salt of mixed monoand di-C oxo esters of phosphoric acid was dried and added to a hydrocarbon gasoline in a concentration that provided 10 pounds of the ester salt per 1000 barrels of the gasoline. The gasoline to which the mercuric salt was added contained 3 cc./gal. TEL and 0.2 theory of cresyl diphenyl phosphate. The gasoline employed was composed of 12% olefins, 22% aromatics, and the remainder saturates and had an ASTM distillation of F. to 390 F.

The above gasoline without the mercuric phosphate ester additive was first run in a 1962 Chevrolet 327 cubic inch engine, which had. a clean or initial octane requirement of 96.0 octane. After 216 hours of operation, the octane requirement was increased 5.0 octane to 101.0 octane. This engine was thoroughly cleaned of all deposits which lowered the octane requirement to 96 octane, and then run on an identical cycle, with the same fuel containing the 10 lbs. per 1000 barrels of the mercuric ester. After 216 hours use, the octane requirement increase was reduced 30% by the addition of the mercuric phosphate ester.

What is claimed:

1. A gasoline composition consisting essentially of hydrocarbon gasoline, an anti-knock quantity of a tetralower-alkyl-lead compound, a gasoline-soluble zinc salt of a phosphorus compound having the formula:

R0 OH wherein R is a hydrocarbon radical of from about 8 to 18 carbon atoms, R is selected from the group consisting of hydrogen and R, said salt being suflicient to provide about 0.025 to 0.3 milligram atoms of metal per gallon of said gasoline, and about 0.05 to 0.6 theory of a gasolinesoluble phosphorous compound having the formula:

wherein R is a lower alkyl phenyl radical of 7 to 15 carbon atoms and R is selected from the group consisting of phenyl and R.

2. The composition of claim 1 wherein the gasolinesoluble phosphorous compound is cresyl diphenyl phosphate.

References Cited UNITED STATES PATENTS 2,560,542 7/1951 Bartleson et al. 44-68 X 2,889,212 6/1959 Yust et al 44-69 3,010,811 11/ 1961 Gimmaria.

3,055,925 9/1962 Hartle.

2,763,613 9/ 1956 Scott et a1 4469 2,863,745 12/ 1958 Cantrell et al. .-1.....- 44-69 2,989,386 6/1961 Lovett et al. 44--69 FOREIGN PATENTS 538,474 8/ 1941 Great Britain.

DANIEL E. WYMAN, Primary Examiner W. I. SHINE, Assistant Examiner US. Cl. X.R. 4468