US3511623A - Gasoline composition containing a metal salt of an azole compound - Google Patents

Description

United States Patent US. Cl. 44-63 21 Claims ABSTRACT OF THE DISCLOSURE A gasoline composition consisting essentially of hydrocarbon gasoline, an anti-knock quantity of tetra-loweralkyl lead compound, and a gasoline-soluble metal salt of an azole having the formula:

6 1 14):] wherein Z is an atom selected from the group consisting of nitrogen and carbon and at least one Z is carbon; R R R and R are hydrocarbon radicals of up to 30 carbon atoms; and n is an integer of 0 to 1, with the proviso that when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical and when n is 1, Z is a carbon atom. The metal is selected from the group consisting of Groups Ia, IIa, IIIa, Va, Ib, IIb, HIb, IVb, Vb, VIb, VIIb, VIII and tin. The invention also contemplates adding an alkali metal salt of an azole to the gasoline composition in combination with a metal salt of an azole wherein the metal is one of Groups IIIa, Va, Ib, IIb, IHb, IVb, Vb, VIb, VIIb, VIII and tin.

This application is a continuation of application Ser. No. 645,490, filed June 12, 1967, which, in turn, was a continuation-in-part of applications Ser. Nos. 399,349 and 399,350, filed Sept. 22, 1964, all now abandoned.

The present invention relates to distillate hydrocarbon gasoline compositions which when employed in spark ignition engines lead to improved engine performance.

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 adversely affect the nature and increase the amount of deposits in the combustion space. These effects manifest themselves in a variety of ways particularly in the case of the higher compression engines. For instance, a fuel having an octane number appropriate to the designed engine compression ratio is unable to give the same antiknock performance after the formation of 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. Modern engines also evidence a tendency to rumble, an objectionable shuddering noise, apparently caused by flexing of the crankshaft due to deposit-induced abnormal combustion. Surface ignition induced by deposits also often creates abnormalities such as pre-ignition, autoignition and wild ping. Combustion chamber deposits are known to cause piston ring wear and to reduce exhaust valve life. All of these facets of combustion abnormalities can lead to engine damage and/or loss in power and efiiciencey.

Various commonly employed gasoline additives as, for example, phosphate compounds such as tricresyl phosphate, cresyl diphenyl phosphate, etc., are known to improve engine operation with respect to certain of the problems presented by deposit-induced ignition. Relatively large amounts of these compounds are needed, however, to effectively combat the combustion abnormalities, particularly rumble.

It has now been found that leaded gasolines having added thereto about 0.002 to 0.4 or even 0.8 millimole or milligram atom of metal per gallon as certain gasolinesoluble metal salts of certain azoles, exhibit improved engine performance with respect to one or more of lower octane number requirement increase, improved rumble, surface ignition characteristics, reduced piston ring wear and extended exhaust valve life. The metals of the azole salts of the invention can be a metal of Groups IIIa, Va, Ib, IIb, IIIb, IVb, Vb, VIb, VIIb, VIII, tin or a mixture of two or more of these metals. Among these metals it is preferred to use aluminum, antimony, bismuth, copper, zinc, cadmium, mercury, scandium, titanium, zirconium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, the iron group metals (iron, cobalt and nickel) and tin. Nickel and cobalt are especially preferred. The Groups of the Periodic Chart mentioned above are as designated on the inside front cover of the Merck Index, seventh edition, Merck & Co., Inc., Rahway, N.I., 1960. As another embodiment, the invention contemplates adding in combination with the aforementioned metal salts, small amounts of gasoline-soluble alkali metal salts of the azoles. The preferred alkali metal salts are those of sodium, potassium and lithium.

It has also been found that leaded gasolines having added thereto about 0.002 to 0.4 or even 0.8 millimole or milligram atoms of metal per gallon as gasoline-soluble alkali or alkaline earth metal, i.e. Group Ia or IIa metal salts of certain azoles, exhibit improved engine performance with respect to one or more of lower octane number requirement increase, improved rumble, surface ignition characteristics, reduced piston ring Wear and extended exhaust valve life. The preferred alkali metal salts are those of sodium, potassium and lithium and the preferred alkaline earth metal salts are those of calcium, barium and strontium.

The azole compounds, the salts of which constitute the additives of the present invention have the following formula:

(1'11) n (I?) n NH i? ah 011 wherein Z is a carbon or nitrogen atom and at least one Z is a carbon atom; R R R and R are hydrocarbon radicals of up to 30 or more carbon atoms on the average, often at least about 4 and preferably about 8 to 18 carbon atoms, and n is an integer of 0 to 1 with the proviso that when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical and when n is 1, Z is carbon atom. R R R and R, can be an aliphatic, aromatic or mixed aliphatic-aromatic radical and is preferably non-olefinic and non-acetylenic, i.e. having adjacent carbon atoms no closer than 1.40 A.

Patented May 12, 1970 I Also, R and R together and/or R and R together can form cycloaliphatic or aromatic hydrocarbon rings, preferably C 11 in fused relationship with the azole ring (i.e. two carbon atoms common to both the hydrocarbon ring, which is preferably a benzene ring, and the azole ring). The total number of carbon atoms in a molecule of the azole compounds is preferably up to about 40 or even up to about 30 and the metal salt of the azole is soluble in the gasoline at least to the extent employed in the invention. Also, the salts may contain more or less than the stoichiometric equivalent of the metal and thus the product may contain free azole or when polyvalent, may be attached to another group, for instance, the inorganic anion of the metal compound used to form the azole salt.

The azole compounds from which the metal salts of the invention are made include, for instance, pyrrole; imidazole; pyrazole; 1,2,3-triazole; 1,2,4-triazole; tetrazoles; alkyl-substituted azoles such as 2-isobutylpyrrole; 2,5-dioctyl pyrrole; 2,3,5-trihexyl pyrrole; 2-stearyl pyrrole; 2,5-didecyl imidazole; 2,4,5-trinonyl imidazole; 5- hexyl-1,2,3-triazole; 4,5 dioleyl 1,2,3-triazole; S-pentacosyll,2,3-triazole; 3,5-dipentyl-1,2,4-triazole; 3-hexadecyl-1,2,4-triazole; 3,5-dibutyl-l,2,4-triazole; S-pentadecyl- 1,2,4 triazole; 5 octyl 1,2,3,4 tetrazole; 5 octadecyl- 1,2,3,4-tetrazole; aryl-substituted azoles such as Z-phenyl pyrrole; 2-cresyl-1-4-isobutyl imidazole; 5-benzyl-l,2,3- triazole; tetrahydro'benzotriazole; benzotriazole; idole; carbazole; and like materials.

The preferred R R R and R groups include the straight or branch chained alkyl and alkyl-substituted phenyl groups whose alkyl substituents contain a total of up to 18 carbon atoms, and preferably are lower alkyl, especially methyl. Illustrative of suitable R R R and R groups are pentyl, butyl, octyl, isooctyl, 2ethyl-heptyl, dodecyl, oleyl, octadecyl, tetradecyl, phenyl and alkylated phenyls such as cresyl, xylenyl, propyl phenyl, butyl phenyl, dibutyl phenyl, monoamylphenyl, diamyl phenyl, decyl phenyl, dodecyl phenyl, tetradecyl phenyl, hexadecyl phenyl and octadecyl phenyl.

In order to provide leaded gasolines of further enhanced characteristics, for instance, as to preignition, spark plug fouling and even, in at least some cases, rumble, there can be included in the gasoline composition of the invention a gasoline-soluble phosphorous compound having the formula:

wherein R has the value described above with respect to the azoles from which the metal salts of the invention are made; R is hydrogen and R and n is an integer of 0 to l. 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 tri-ester. 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 U.S. Pat. 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 aromatic hydroxy compound with phosphoric acid to make the phosphate or with phosphorous trichloride to form the phosphite.

The preferred alcohols are alkanols which can be straight or branched chain 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 Oxo process, phenol and alkylated phenols such as cresol, xylenol, propyl phenol, butyl phenol, dibutyl phenol, monoamylphenol, diarnyl phenol, decyl phenol, dodecyl phenol, tetradecyl phenol, hexadecyl phenol and octadecyl phenol. Particularly preferred alkyl phenols are ortho, meta and para cresol; 2,4- and 2,5-xylenol; 2,4-dimethyl-6-tertiary butyl phenol; octyl and nonylphenols.

By the term leaded gasoline to which the additives of the present invention are incorporated is meant hydrocarbon fractions boiling primarily in the gasoline range, usually about 100 to 425 F., having added thereto a small amount, generally between about 1 to 6 cc. per gallon, preferably about 2 to 4 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 a blend of hydrocarbon mineral oil fractions boiling primarily in the aforementioned range and will contain varying proportions of parafiins, olelns, naphthenes and aromatics derived by distillation, cracking and other refining and chemical conversion processes practiced upon crude oil 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. halohydrocarbon scavengers, oxidation inhibitors, etc. Such gasolines frequently have a Research Method octane number of about 90 to 105, and 2. Motor Method-octane number of about to 98.

The metal salt component of the invention is incorporated in the leaded gasoline in small amounts sufficient to provide a composition exhibiting an advantage in spark-ignition engines, for instance, with respect to one or more of improved rumble, surface ignition characteristics, lower octane number requirement increase, reduced piston ring wear and longer exhaust valve life. The actual amount of the metal salt additive employed may vary depending upon the particular gasoline used, its lead content, etc. In any event, sufficient 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 atom of the metal per gallon of gasoline. The additive will usually provide the gasoline with 0.00004 to 0.008 grams of one or a combination of the metal of the salt per gram of lead, preferably 0.0005 to 0.006 grams of the metal per gram of lead. This often means that about 0.5 to 15 or 30 or more pounds of the metal salt is added, preferably about 2 to 20 pounds, per 1000 barrels of gasoline. The alkali metal salts, when employed in combination with the metal salt of the first embodiment, are ordinarily added in an amount of about 0.002 to 0.8 millimoles or milligram atoms of metal per gallon of gasoline and the total combination of selected metal salt and alkali metal salt is preferably about 0.002 to 0.8 millimole or milligram atom of metal per gallon of gasoline.

When used, about 0.05 to 0.6 theory, preferably about 0.15 to 0.5 theory, of the auxiliary phosphate or phosphite additive, based on the lead content of the gasoline is generally employed. The term theory as applied to the amount of the 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 The following examples are given to illustrate the advantages provided leaded gasolines by the additives of the present invention.

EXAMPLE I A nickel salt, 2-octyl pyrrole, calculated as 142% by weight nickel, is added in an amount of 6 pounds of the salt per 1000 barrels to a gasoline composed of 37 volume percent light straight run gasoline, 23 volume percent light catalytically cracked gasoline, 13 volume percent heavy catalytically reformed gasoline and 27 volume percent heavy catalytically cracked gasoline containing 3 ccs. 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.) and 0.2 theory cresyl diphenyl phosphate (CDP).

Evaluation of the resulting composition in a spark ignition engine shows operation of engine to be improved, with respect to rumble, surface ignition characteristics, octane number requirement increase, ring wear and exhaust valve life.

Similarly improved results can be obtained by using in the same gasoline containing TEL Motor'Mix and CDP, the following additives in the designated amounts:

Cale. Amount of percent additive, Example Additive metal #/1,000 bbls II Aluminum 2-isobutyl pyrrolate- 6. 86 10 III- Antimony 2,5-didecyl imidazolate. 10. 45 5 IV- Copper 2-octadecylpyrro1ate 9. 22 5 V Zinc 5hexyl-1, 2, B-triazolate 17. 70 3 VI Seandium 4,5-dioleyl-1, 2, 3-tri- 2. 57 15 azolate. VII Titanium 5octyl1, 2,3, i-tetrazo- 6.21

ate. VIII- VzIinadium 2, 3-benzo-1, 4, 5-triazo- 12. 52 5 ate. IX- Chromium indolate 13. 31 5 Miirganese 2, 5-dioctyl imidazo- 8. 64 10 a e. XI Tin 5-hexyl-1, 2, 3, -triazolate 18. 85 3 XII 1. Potassium 2-triacontyl pyrrolate- 7. 24 10 Cobalt 2-is0butyl pyrrolate 18. 25 3 EXAMPLE XIII A potassium salt of 2-octyl pyrrole, calculated as 17.65% potassium is added in an amount of 6 lbs. of the salt per 1000 barrels to a gasoline composed of 37 volume percent light straight run gasoline, 23 volume percent light catalytically cracked gasoline, 13 volume percent heavy catalytically reformed gasoline and 27 volume percent heavy catalytically cracked gasoline containing 3 ccs. 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.) and 0.2 theory cresyl diphenyl phosphate (CDP).

Evaluation of the resulting composition in a spark ignition engine shows operation of engine to be improved with respect to rumble, surface ignition chracteristics, octane number requirement increase, piston ring wear and exhaust valve life.

Similarly improved results can be obtained by using in the same gasoline containing TEL Motor Mix and GDP, the following additives in the designated amounts:

Cale. Amount of The ORI of an engine is obtained by the following pro cedure:

After determining the clean or initial octane requirement of a 327 cubic inch 10.1:1 compression ratio engine,

the gasoline without the additive of the invention is run for 216 hours and the octane requirement increase noted. The engine is then thoroughly cleaned of all deposits so that it again exhibits the same clean octane requirement and run on an identical cycle, with the same gasoline but containing the additive of the invention. After 216 hours use, the octane requirement increase is noted and compared with the octane requirement increase found with the gasoline without the additive to determine the extent of improvement.

The rumble tendency of an engine after a given time of use is measured by a LIB number. The number represents the percent isooctane (containing 3 cc. TEL/ gallon) required in a blend with benzene (containing 3 cc. TEL/ gallon) after a given period of engine operation using the fuel under test, to avoid rumble at a given RPM, 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 certain percent of isooctance in an isooctanebenzene blend (containing 3 cc. TEL/gallon), manually opening the throttle at a given rate and recording the r.p.m. at which rumble occurs, if any in fact occurs. The faster one is able to run the engine with the lowest percent of isooctane in the blend the better the rumble resistance of the engine. Thus, the lower the LIB number the better the rumble characteristics of the engine. The gasoline with and without the additive of the invention is tested in this manner and the LIB numbers obtained with each are compared.

The piston ring wear is determined by equipping a single cylinder COT engine with radioactive rings installed in the grooves of the pistons. The lubricating oil system of the engine is provided with a sealed monitoring well which contains a scintillation counter. The ring wear rate is determined by passing the lubricating oil through the monitoring well and therein detecting the concentration in mg./hour of radioactive iron transported to the oil due to wear of the piston rings.

The test to determine the effect of the fuel composition on exhaust valve life involves running an automobile engine at a fixed number of hours at constant or varied speeds and loads depending on the engine used and then noting the number of valves that failed during this period of time.

The test used to determine the deposit-induced ignition characteristics of the fuel composition comprises equipping an engine with an L-head cylinder and an electronic wild ping counter which records the total number of wild pings which have occurred during the test periods. Since deposit-induced ignition is the tendency to ignite the fuel-air mixture erratically and to produce uncon trolled combustion noticeable as, for instance, wild ping, the electronic counter which is used in conjunction with an ionization gap, automatically detects and records uncontrolled combustion.

-It is claimed:

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

( 11). (Elms ah m that when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical and when m is 1, Z is a carbon atom, said metal being selected from the group consisting of Groups Ia, Ila, IIIa, Va, Ib, Ilb, IIIb, W12, Vb, VIb, VIIb, VIII and tin, the amount of said salt being sufiicient to provide 0.002 to 0.8 milligram atoms of selected metal of said salt per gallon of gasoline.

2. A gasoline composition consisting essentially of hydrocarbon gasoline, an anti-knock quantity of tetralower-alkyl lead compound, and a gasoline-soluble metal salt of an azole having the formula:

a so. Ul a) i (Ra n Dn wherein Z is an atom selected from the group consisting of nitrogen and carbon and at least one Z is carbon; R R R and R are hydrocarbon radicals of up to 30 carbon atoms; n is an integer of to 1, with the proviso that when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical and when n is 1, Z is a carbon atom, said metal being selected from the group consisting of Groups IIIa, Va, 1b, III), 1111!), IVb, Vb, VIb, VIIb, VIII and tin, the amount of said salt being sufficient to provide 0.002 to 0.8 milligram atoms of selected metal of said salt per gallon of gasoline.

3. The composition of claim 2 in which there is also included about 0.05 to 0.6 theory of a gasoline-soluble phosphorous compound having the formula:

wherein R is a hydrocarbon radical of up to about 30 carbon atoms on the average, R is selected from the group consisting of hydrogen and R, and is a n integer having a value of O to 1.

4. The composition of claim 2 wherein the selected metal is an iron group metal.

5. The composition of claim 4 wherein the metal is nickel.

6. The composition of claim 3 wherein at least one R in the structure of claim 3 is an alkyl phenyl radical of 7 to 15 carbon atoms.

7. The composition of claim 6 wherein the amount of phosphorus compound is about 0.15 to 0.5 theory.

8. The composition of claim 6 wherein the selected metal is an iron group metal.

'9. The composition of claim 8 wherein the metal is nickel.

10. A gasoline composition consisting essentially of hydrocarbon gasoline, an anti-knock quantity of a tetralower-alkyl-lead compound, and a gasoline-soluble metal salt of an azole having the formula:

wherein Z is an atom selected from the group consisting of nitrogen and carbon and at least one Z is carbon; R R R and R are hydrocarbon radicals of up to 30 8 carbon atoms; n is an integer of 0 to 1, with the proviso that when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical 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.

12. The composition of claim 11 wherein the selected metal is an iron group metal.

13. The composition of claim 12 wherein the metal is nickel.

14. The composition of claim 13 wherein the phosphorous compound is cresyl diphenyl phosphate.

15. A gasoline composition consisting essentially of hydrocarbon gasoline, an anti-knock quantity of tetralower-alkyl lead compound, and a gasoline-soluble metal salt of an azole having the formula:

(1111) lma l iot: (1 4)::

wherein Z is an atom selected from the group consisting of nitrogen and carbon and at least one Z is carbon; R R R and R are hydrocarbon radicals of up to 30 carbon atoms; n is an integer of 0 to 1, with the provisio that when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical and when n is 1, Z is a carbon atom, said metal being selected from the group consisting of alkali and alkaline earth metals, the amout of said salt being suflicient to provide 0.002 to 0.8 milligram atoms of selected metal of said salt per gallon of gasoline.

1-6. The composition of claim 15 in which there is also included about 0.05 to 0.6 theory of a gasoline-soluble phosphorous compound having the formula:

wherein R is a hydrocarbon radical of up to about 30 carbon atoms on the average, R is selected from the group consisting of hydrogen and R, and n is an integer having a value of 0 to 1.

17. The composition of claim 16 wherein at least one R in the structure of claim 16 is an alkyl phenyl radical of 7 to 15 carbon'atoms.

18. The composition of claim 17 wherein the amount of phosphorus compound is about 0.15 to 0.5 theory.

19. A gasoline composition consisting essentially of hydrocarbon gasoline, an anti-knock quantity of a tetralower-alkyl-lead compound, and a gasoline-soluble metal salt of an azole having the formula:

Z=Z U a); (E ton wherein Z is an atom selected from the group consisting of nitrogen and carbon and at least one Z is carbon; R R R and R are hydrocarbon radicals of up to 30 carbon atoms; 11 is an integer of 0 to 1, with the proviso than when n is 0, Z is selected from the group consisting of a nitrogen atom and the radical included about 0.05 to 0.6 theory of a gasoline-soluble phosphorous compound having the formula:

RO /OR RO o 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.

21. The composition of claim 20 wherein the phosphorus compound is cresyl diphenyl phosphate.

References Cited UNITED STATES PATENTS 3,354,189 11/1967 Revukas 44-68 X DANIEL E. WYMAN, Primary Examiner W. I. SHINE, Assistant Examiner US. Cl. X.R. 44-68, 69