US2881062A - Hydrocarbon fuel - Google Patents

Description

United States Patent HYDROCARBON FUEL John W. Bishop, Westfield, N.J., assignor to Tide Water Associated Oil Company, Bayonne, N.J., a corporation of Delaware No Drawing. Application August 17, 1955 Serial No. 529,074

5 Claims. (CI. 44-69) This invention relates to a hydrocarbon fuel for interproved hydrocarbon fuel for use in spark ignition engines to improve the performance thereof by reducing certain harmful effects due to engine deposits which form in the operation of modern high compression engines.

With the advent of the high compression engine and the progressive increase in compression ratios in recent years, certain problems have developed in the operation of these engines. One of the most annoying and critical of these problems has been knocking of the engines in use v sufiicient to inhibit surface ignition. Other objectives,

. and spark plug fouling. Certain of these additives actunal combustion engines and, more particularly, to an imand rough operation under certain conditions, particularly during acceleration and at idling speeds. These undesirable characteristics result primarily from deposits which form in the upper cylinder area as unburned residue of the fuel.

Knocking or pinging, as it is sometimes called, results from several causes. The knocking phenomenon known as detonation normally results when the engine has built up top cylinder deposits to extent that its octane requirement exceeds the octane quality of the gasoline employed. Detonation can be reduced or eliminated by raising the octane number of the gasoline through increas- !ing the percentage of tetraethyl lead therein or by employing improved refining methods in manufacture of the gasoline or both.

Another type of knocking which is encountered in modern engines is known as surface ignition. This type of knocking results from abnormal combustion of the fuel in the combustion chamber wherein the fuel is ignited by incandescent surfaces of deposits therein at a time other than that at which the spark plug fires. Such abnormal firing of the charge by surface ignition can be expected to result in a loss of power and rough operation of the engine.

In the case of automobile engines, both surface ignition pinging and detonation pinging are annoying to the motorist and it is desirable to eliminate such noises or to reduce them to a level where they are inaudible. As indicated above, detonation can be controlled by raising the octane value of the fuel. However, in the event that an engine is knocking because of surface ignition but not because of detonation, i.e. surface ignition-limited but not detonation-limited, which is the case in many instances of engines usage today, it is desirable to provide a simple means for inhibiting surface ignition without resorting to the relatively expensive expedients of increasing the tetraethyl lead content and use of additional restantially less than that of the anti-detonating agent but ally have been found to increase top cylinder deposits and to raise the octane requirement of the engine, necessitating the use of a gasoline of higher octane value in order to suppress knocking. Insofar as I am aware, none of these additives are completely effective in eliminating surface ignition.

In accordance with the present invention a motor fuel particularly adapted for spark ignition engines has been developed by dissolving in gasoline, and especially in gasoline containing the usual tetraethyl lead anti-detonating compositions, certain molybdenum compoundswhich are soluble in effective concentrations in the gasoline. Hydrocarbon-soluble compounds of molybdenum which fall within a metallo-organo type structure in which the molybdenum is connected through oxygen to an organic radical are particularly effective. More specifically, they are of the class of compounds in which the molybdenum is connected through oxygen to an organic acid residue and are prepared by reacting a molybdenum compound with an acid hydrogen. Examples of molybdenumorgano compounds of this category are molybdenum salts of organic acids, such as molybdenum salts of the fatty acids as oleic, stearic and the like, and molybdenum salts of the naphthenic acids. Other compounds of molybdenum which are effective are certain phenates and derivatives thereof containing molybdenum, particularly phenates in which one or more of the phenoxy radicals carries substituent alkyl groups.

The beneficial effect of compounds of molybdenum is readily ascertainable in test engine runs as will be apparent from the disclosure appearing hereinbelow when such compounds are incorporated in leaded gasolines such as those presently available to the public for the operation of modern high compression engines. In such gasolines the molybdenum decomposition products resulting during burning of gasoline in the engine appear, in addition to suppression of surface ignition, to have the property of combining with the lead and also with any sulfur present. in .the gasoline and scavenging these elements to some degree from the compression chamber. It would also appear that as an additional function the molybdenum sulfide formed during combustion of a sulfur containing gasoline may operate to improve the lubrication of the cylinder walls, rings and other moving parts. Thus, the particular molybdenum compounds here under consideration appear capable of performing multiple functions when incorporated in motor fuel in suitable proportions.

The following examples are intended to set forth specific embodiments of the invention with no intent necessarily to limit the invention to the use of the specific compositions disclosed therein. In the examples the molybdenum compounds noted therein were dissolved in a commercial gasoline manufactured for use in automobile engines and refined from East Texas and Gulf Coast crudes by conventional refining methods. This gasoline contained 2.8 mL/gallon of conventional tetraethyl lead anti-detonating composition and had a Research octane rating of 94.

The fuel in which these molybdenum compounds had been incorporated was used to operate a test engine especially adapted for detecting surface ignition. This engine is a CFR supercharged (F4) engine having a shrouded intake valve and fitted with a conventional spark plug and ignition system and with an additional spark plug in which the side electrode has been removed. The latter plug provides an ionization gap and is electrically connected during the test runs to a deposite ignition counter manufactured by the Erwin Scientific Instrument Company. The deposit ignition counter, when so connected and operated, indicates and counts all explosions occurring within the cylinder except those which occur as a result of the firing of the spark plug. Such explosions are detected by the deposite ignition counter as a result of current flowing across the gap in the modified spark plug through ionized gases caused by the surface ignition firing of the combustion charge. With this equipment the number of surface ignitions per unit of time can be accurately measured during operation of the engine.

The above-described single cylinder engine had a compression ratio of 9.0 to l with a spark setting at top dead center of the piston travel. During. each test run the engine was operated on the test fuel for a maximum of 40 hours at a speed of 1 800 r.p.m. and while maintaining thetemperature of the cooling jacket at 212 F. and the temperature of the intake air at 250 F. The crankcase lubricant employed was a refined hydrocarbon crankcase lubricating oil of 450 SUS viscosity at 100 F. consisting of 100 percent distillate lubricating oil containing no additives.

In order to approach normal driving conditions for automobile engines the test engine was operated throughout each run alternately under low duty conditions for 19.5 minutes and high duty conditions for 0.5 minute. During the low duty cycle the supercharge pressure was adjusted so that the absolute manifold pressure was equivalent to 20 inches of mercury at an air to fuel ratio of 13 to 1. High duty cycle conditions were adjusted to give an absolute manifold ratio equivalent to 30 inches of mercury and an air to fuel ratio of 14 to 1. The low duty cycle permitted the engine to build up deposits in order to encourage surface ignition during the subsequent high duty cycle, the latter being under high power output conditions at which the engine containing such deposits would be more likely to exhibit surface ignition.

In conductance of the engine tests referred to herein, deposits were removed from the combustion chamber of the test engine before commencing each run in order that all runs were started under similarly clean engine conditions.

Example I The above-described engine was operated in a first 40 hour test under the above stated conditions using as basefuel the commercial lead gasoline described above. The average number of surface ignition counts per hour indicated by the deposit ignition counter was 49. This run constituted a standardization run for the base gasoline containing no molybdenum additives and no additives other than the conventional tetraethyl lead composition incorporated by the refiner.

Example 11 There was dissolved into the above-specified base gasoline of Example I 0.2 percent by weight of molybdenum naphthenate. This amount was equivalent to 0.2 theory based upon the lead content. The molybdenum naphthenate contained percent by weight of molybdenum and was prepared in known manner by reacting M0 0 with commercial naphthenic acid of 220 acid number. The resulting solution produced a gasoline composition having a distinctive reddish-purple color.

The test engine was operated using as fuel this gasoline composition under the conditions set forth hereinabove while counting the number of surface ignitions throughout a 40 hour run. The average number of surface ignitions registering on the counter during this run was 2 counts per hour. This indicates an extremely great reduction, in fact a virtual elimination, of surface ignition due to the presence of the molybdenum compound 4 in the fuel employed, as is clearly evident from comparison with the test results of Example I on the base gasoline.

Example Ill The molybdenum compound used in this example was tri(tertiary amyl phenoxy)molyb denum dichloride. This molybednum phenate was prepared by reacting molybdenum pentachloride with tertiary amyl phenol under conditions which are known to produce the phenate. Using as fuel the base gasoline containing 0.07 percent (0.2 theory) of this molybdenum phenate a run was made as above-described in the test engine with the result that the average number of surface ignition counts per hour in this case was 1.5, thus indicating the extreme effectiveness of this additive in reducing surface ignition.

The following table discloses data obtained using the above-described test engine and test conditions in which the base fuel contained, in addition to conventional tetraethyl lead anti-detonating agent, also the various additives listed in the table. Periodic standardization runs were made using the base gasoline in order to confirm the surface ignition tendencies of the base gasoline and the condition of the engine. These standardization runs exhibited average numbers of surface ignitions per hour of 49, 40.5, 51, 37, 40 and 42, respectively, thus indicating that the base fuel and engine combination maintained a uniformly high level of surface ignition (43.2 average). The tabulated data below include the results of the runs in the above examples for comparison purposes.

Base Gasoline (2.8 ml. of TEL/gal.) Plus Indicated Additive Average Counts Per Hour NINNN 0.05 theory tri(tertiary amyl phenoxy) molybdenum dichloride (0.018%) Base gasoline (no molybdenum additive) 1 36 hour run. I 24 hour run. 3 Average 6 runs.

The outstanding effectiveness of the molybdenum compounds in reducing surface ignition is evident from the above examples and tabulated data which shows a material reduction in surface ignition counts for the gasoline of this invention over the commercial leaded gasoline which formed the base thereof and a striking improvement over certain compounds of other metals as zirconium and phosphorus, the latter of which have been used or proposed as gasoline additives.

The molybdenum compounds of this invention are markedly effective in reducing surface ignition when dissolved in motor fuel in relatively low proportionate amounts and an important concept resides in the discovery thatsuch small proportionate but effective amounts can be employed without causing seriously objectionable side effects which often attend use of certain known additives. As indicated in the above test data, surface ignition may be practically eliminated when using in a sparkignition engine, gasoline containing molybdenum compounds in concentrations as low as 0.05 percent by weight with little lessening of the effect when the amount is reduced to 0.01 percent. A practical reduction in surface ignition is indicated for concentrations as low as about 0.001 percent. The lower concentrations are preferred for several specific reasons; first because of relatively low material cost and second, because at the lower concentrations there is less tendency of metal additives in general toward formation of engine deposits in use and less tendency toward formation of precipitates in the fuel prior to use. Regarding the latter elfect, Lawson engine runs using the fuel of this invention indicate no objectionable deposit formation in leaded fuels containing up to about 0.2 percent molybdenum compounds of the type herein disclosed. Although this concentration, as shown in the above data, is extremely effective in inhibiting surface ignition, it is preferred to employ these additives in lower proportionate amounts in the fuel, as for example at about 0.01 percent or lower since at or below 0.01 percent concentrations little if any tendency towards instability is exhibited by gasoline containing such amounts and satisfactory surface ignition inhibition is obtained.

The disclosed molybdenum compounds in the abovespecified proportionate amounts did not appear to materially affect the octane rating of the gasolines in which they were incorporated. Use thereof in the engine runs set forth hereinabove did not cause dirty engine conditions.

That specific embodiment of this invention residing in hydrocarbon fuels containing molybdenum compounds in which the molybdenum atom is connected through oxygen to organic radicals is believed unique, as compared to known fuels allegedly containing dissolved molybdenum compounds of different molecular structure, in exhibiting relatively low tendency towards hydrolysis of the molybdenum additive and in possessing other distinguishing features and advantages.

The incorporation of molybdenum compounds in leaded gasoline in relatively small amounts results in an incidental but nevertheless economically important advantage in imparting to the fuel a distinctive color. It is thus within the broader concepts of this invention to provide a leaded hydrocarbon fuel containing any dissolved molybdenum compound capable of imparting color to the resulting solution, to thus replace all or a portion of the conventional dye required for these leaded gasolines which at the same time is effective to improve such gasoline in one or more of the respects disclosed elsewhere herein.

With further reference to the molecular composition of compounds of the phenate structure, there are contemplated, as included within the concept of the invention, such molybdenum phenates as contain at least one aromatic radical connected to molybdenum through oxygen and wherein the remaining valences of the molybdenum atom are satisfied by other radicals. Likewise substituent groups on the rings of the phenate may be of any suitable carbon chain length as long as the compound as a whole is sufficiently soluble in the hydrocarbon fuel in amounts to impart fuel icproving effectiveness.

1 claim:

1. A motor fuel composition consisting essentially of gasoline having dissolved therein, in an amount effective to reduce the surface ignition tendency of said gasoline, a molybdenum compound selected from the group consisting of molybdenum naphthenate and tn'(tertiary amyl phenoxy) molybdenum dichloride.

2. A motor fuel composition as defined in claim 1 in which the said molybdenum compound is present in amount by weight of between about 0.001% and 0.02%.

3. A leaded gasoline having dissolved therein between about 0.01 theory and about 0.2 theory of molybdenum naphthenate.

4. A leaded gasoline having dissolved therein between about 0.05 theory and about 0.2 theory of tri(tertiary amyl phenoxy) molybdenum dichloride.

5. A leaded gasoline having dissolved therein an alkyl phenoxy molybdenum chloride in amount effective to reduce the surface ignition tendency of said gasoline.

References Cited in the file of this patent UNITED STATES PATENTS 1,779,061 Danner et al Oct. 21, 1930 2,086,775 Lyons et a1. July 13, 1937 2,151,432 Lyons et a1 Mar. 21, 1939 FOREIGN PATENTS 684,887 France July 2, 1930 UNITED STATES. PATENT OFFICE CERTIFICAT OF C) ,.ECON

Patent No, 2,881,662 April '7, 1959 John W Bishop It is hereby certified that error in above numberei patent requiring eorrentio that seicl Letters Patent should read as corrected below,

In the grant, 2 and I, for "ass'ignor to Tide Water Aseoeiated Oil Company, of Bayonne, New Jersey, a corporation of Delaware," read ass'ignor to Tidewater Oil Company, a corporation of Delaware, line 1-2, for "Tide Water Associated Oil Company, its successors" read me Tidewater Oil Company, its. successors in the heading to the printed specification, lines 3 to 5, for essignor to Tide Water Associated Oil Company, Bayonne, N; J, a corporation of Delaware" read assignor to Tidewater Oil Company, a, corporation of .Uelaware' column 1, line 59, for "engines" read engine column 6, line 10, for ioproving" read improving Signed and sealed this 11th day of August 1959,.

. (SEAL) Attest:

KARL AXLINE v ROBERT (3.. WATSON Attesting Officer I Comissioner of Patents

Claims (2)

1. 3. A LEADED GASOLINE HAVING DISOLVED THEREIN BETWEEN ABOUT 0.01 THEORY AND ABOUT 0.2 THEORY OF MOLYBDENUM NAPHTHENATE.
2. 4. A LEADED GASOLINE HAVING DISCOLVED THEREIN BETWEEN ABOUT 0.05 THEORY AND ABOUT 0.2 THEORY OF TRI(TERIARY AMYL PHENOXY) MOLYBDENUM DICHLORIDE.