US2982627A

US2982627A - Diesel engine fuels

Info

Publication number: US2982627A
Application number: US698051A
Authority: US
Inventors: James L Lauer; Archibald P Stuart
Original assignee: Sun Oil Co
Current assignee: Sunoco Inc
Priority date: 1957-11-22
Filing date: 1957-11-22
Publication date: 1961-05-02
Anticipated expiration: 1978-05-02

Description

United. States Patent DIESEL ENGINE FUELS James L. Lauer, Philadelphia, and Archibald P. S tuart,

Media, Pa., assignors to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing. Filed Nov. 22, 1957, Ser. No. 698,051

2 Claims. (Cl. 44-57) This invention relates to the use of organic amines together with carbonyls of chromium, molybdenum and tungsten, and to the use of metal ammino carbonyls produced by the reaction of the above metal hexacarbonyls with amines, to improve the ignition characteristics of diesel fuels.

In diesel engine operation, air is compressed to a suiticiently high pressure and temperature in the engine cornbustion chambers to ignite a petroleum hydrocarbon fuel which is injected into the combustion chamber after compression of the air. An important characteristic of the hydrocarbon diesel fuel is the ignition delay period, i.e., the time interval between injection of the hydrocarbon fuel into the combustion chamber and its ignition therein. The ignition delay characteristic of a diesel fuel is conveniently expressed in terms of a cetane number which is the percentage of n-cetane in a mixture of n-cetane and alpha-methyl naphthalene having the same ignition delay characteristics as the diesel fuel. Fuels having too great an ignition delay period, i.e., too low a cetane number, cause excessive engine knocking and rough running, and decrease the life and efiiciency of the engine.

' .It .has previously been observed that the presence of chromium hexacarbonyl in a diesel fuel reduces the ignition delay period, i.e., raises the cetane number of that fuel to a small degree. It is also known that organic amines, in general, increase the ignition delay period, i.e., lower the cetane number of a dieselfuel. It has now been found that by using both a hexacarbonyl of chromium, molybdenum or tungsten and an organic amine, or by using the reaction product of such a hexacarbonyl with an organic amine, as diesel fuel. additives,

the cetane number of the resulting fuel composition is improved substantially over that observed with the hexacarbonyl as the sole additive. One or more of the metal hexacarbonyls together with one or more of the amines can be used or, alternatively, one .or more of the corresponding metal amminocarbonyls can be employed in accordance with the practice of the invention.

The amines used according to the invention, either together with the metal hexacarbonyls, or to prepare the metal ammino carbonyls by reaction with the metal hexacarbonyl are preferably tertiary amines, but primary and secondary amines can also be used. Amines having at least one hydrocarbon substituent of from 1 to 12 carbon atoms are within the scope of the invention. The hydrocarbon substituents attached to the nitrogen atom of the amine can be alkyl, aralkyl, aryl or alkaryl radicals. Suitable alkyl radicals, for example, are those having less than about 7 carbon atoms per group, while suitable aryl radicals include both mononuclear and dinuclear aromatic radicals having less than 13 carbon atoms. Aralkyl and/or alkaryl radicals having less than about 9 carbon atoms per group are preferred. Specific examples of preferred tertiary amines are triphenylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, methyldiethylamine, N,N-dimethylaniline,

Eatented May 2,1961

r 2 ethyldiphenylamine, and-the like.

The metal ammino carbonyls used in this invention have the following general formula: 7

)y(X)z.

where M is chromium, molybdenum or tungsten,

an organic amine as defined hereinabove, and y and z are whole numbers of from 1 to 5, and the sum of which is 6. These compounds are suitably formed by reacting f the metal hexacarbonyl with a suitable amine at elevated temperature, e.g., 200 F. or higher. r 1

Generally metal ammino carbonyls having the general formula M(CO X or M(CIO) X are most readily formed during the reaction between the metal hexacarbonyl. and the amine. However, other metal ammino carbonyls can be formed within the scope of the general formula set forth above. -All of the amino carbonyls of chromium, molybdenum and tungsten can be used in the present invention. Specific examples of suitable metal ammino carbonyls are Cr(CO) C H N) )4[( s s)a l2. )4( e 5 z)s,' Mo(CO) (0-toluidine) Mo(CO) (o-toluicline) and the like. a t

Diesel fuels which are used in the practice of the invention are hydrocarbon mixtures normally derived from petroleum and boiling in the range of about 350 F. to 700 F. at atmospheric pressure. These diesel fuels can contain, in addition, additives-such as pour point dew pressants, viscosity improvers, and the like which are known in the art. Y e l The novel ignition improvers of the present invention, or decomposition products thereof, normally do not deposit in engine combustion chambers in sufficient amount; t to cause significant engine wear or other problems. How, ever, if desired, scavenging agents can be ,used to sup-. press deposition of. the ignition improvers or decomposi tion products thereof. Halogenated hydrocarbonssuch as ethylene dibromide, ethylene dichloride, carbon tetrachloride, diand trichloropentanes,. diandtrichlorobu, tanes, tetrachlorobutanes, dichlorobenzene, tetrachlorof benzene, benzotrichloride, benzotribromide, beuzotrihexacarbonyls and the amines, or alternatively the me'tal' ammino carbonyls, are added to the hydrocarbon diesel.

fuel prior to the injection .of the fuel into the combustionl chambers of a'die'sel engine. .The metal hexacarbqnylsi and the amines, as well as the corresponding metal ammino carbonyls, are sufiiciently soluble in diesel me hydrocarbons so that suitable amounts ,of these additiveg, as described hereinafter, can readily be. dissolved in-thediesel fuel. Although not usually required, mutual sqlg. v

vents and/or dispersing agents can be used if desired to"v improve the stability tions.

When both metal hexacarbonyls and aminesai'elemq, ,7 ployed, therelative proportions of the. amine coinpon t; to the metal hexacarbonyl component 'canwarygbe Other amines can be used include diethylamine, diphenylamine, N-ethyly of the. novel diesel fuel compoSi-; V

6:1 and 1:1 on a molar basis. Mole ratios for the amine component to the metal hexacarbonyl component offrom 4:1 to 2:1 are distinctly preferred. Generally, thetotal amount of the metal hexacarbonyl and amine, or of the metal ammino carbonyl'by itself, is suitably equal to form about 0.005 to about 5.0% by weight of the resulting fuel composition. Amounts in the range of from about 0.01% to about 2.0% are preferred.

In a second practice of the invention, applicable only where one or more metal ammino hexacarbonyl is emploved, the novel diesel fuel ignition improver is introduced into the engine combustion chambers in admixture with the air which is charged thereto. In this embodiment of the invention, the metal ammino carbonyl ignition improvers are admixed with the diesel hydrocarbon fuel inside the engine combustion chambers after injection of the hydrocarbon fuel therein.

Chromium, molybdenum and tungsten ammino carbonyls have sufiiciently high vapor pressure at normal conditions so that by contacting the air charged to the engine with the metal ammino carbonyl, suflicient volatilized metal ammino carbonyl is carried into the engine combustion chambers to effect a reduction in the ignition delay period of the diesel hydrocarbon fuel. Thus in this second practice of the invention the engine intake air is contacted with the metal ammino carbonyl prior to admission of the air to the engine combustion chambers. The metal ammino carbonyls are normally solid, and this contact can conveniently be effected by packing the intake air filter with the solid ignition improver in powder form. Other means known in the art for introducing the metal ammino carbonyl in admixture with the air can be used.

Alternatively, in this second practice of the invention, suitable amounts of solid chromium, molybdenum and/ or tungsten ammino carbonyl can be directly introduced into the engine via the air intake manifold. These ignition improvers in powder form are sucked into the manifold together with the engine air and introduced into the engine combustion chambers dispersed in the air. In the combustion chambers, the metal ammino carbonyls are vaporized before injection and combustion of the fuel. Any suitable means known in the art can be employed for supplying the novel ignition improvers of this invention to the engine air intake manifold. For

example, a container holding powdered metal ammino carbonyl can be connected as by a tube to the engine intake manifold. During engine operation, the powdered ignition improvers are aspirated into the intake manifold by reason of the vacuum therein.

' In order to illustrate a specific embodiment of the invention, o-toluidine and molybdenum hexacarbonyl were reacted together at about 250 F. in the ratio of about 5 mols of o-toluidine to about 1 mole of molybdenum hexacarbonyl. The reaction product, comprising molybdenum ammino carbonyls represented mainly by the formulas M(CO) (o-toluidine) and M0(CO) (o-toluidine) was added to a commercially available kerosene diesel fuel having an atmospheric boiling range of from about 400 F. to about 600 F. in an amount equal to about 1.5% by weight of the resulting fuel composition. The diesel fuel containing the molybdenum ammino carbonyl had a cetane number greater by 2.0 numbers than the same fuel without the additive of the invention.

Similar beneficial results were obtained when a physical admixture of the metal hexacarbonyl together with the amine was employed in accordance with the invention. To illustrate the latter embodiment, a physical admixture of o-toluidine and molybdenum hexacarbonyl was prepared in the proportions of about 2:1 parts by Weight, respectively. These proportions are equivalent to a mole ratio of o-toluidine to molybdenum hexacarbonyl of about 5:1, in the resultant physical admixture. This admixture was added to a commercially available kerosene diesel fuel in an amount equal to about 1.5% by 4 1 weight of the resulting fuel composition, the o-toluidine representing about 1.0% by weight, and the molybdenum hexacarbonyl representing about 0.5% by weight, of the final fuel. The kerosene diesel fuel so employed had an atmospheric boiling range of from about 400" F. to about 600 F. and, b'eforethe addition of the ignition improvers, had a cetane number of about 49.2. The same diesel fuel, after the addition of the physical admixture of o-toluidine and molybdenum hexacarbonyl as above described had a cetane number of about 53.4, or about 4.2 cetane numbers higher than the base fuel, this latter value representing an improvement of over 8.5% over the base fuel.

In order to demonstrate the synergistic beneficial effect of the physical admixture of the amine with the metal hexacarbonyl over and above that exhibited by the individual components separately, the following tests were performed. A sample of the commercially available kerosene diesel fuel used in the preceding example, having a cetane number of 49.2, was divided into two portions. To one portion was added about 1.0% by weight of o-toluidine and to the other 0.5 by weight of molybdenum hexacarbonyl. The individual concentrations of the additives in the latter samples were the same as the individual concentrations of those additives when used together in the preceding example, wherein a physical admixture of o-toluidine and molybdenum hexacarbonyl was employed in the same base fuel, As was to be expected in view of prior knowledge, the cetane number of the diesel fuel containing the o-toluidine alone was lowered by 2.6 numbers, while the cetane number of the fuel containing the molybdenum hexacarbonyl alone was raised by only 2.0 numbers. Nevertheless, as was shown in the preceding example, when the o-toluidine and molybdenum hexacarbonyl were employed in the same amounts, but together in the same fuel, the cetane num ber of that fuel was raised by 42 numbers. This observed increase represents an improvement of 110% over and above the effect of the molybdenum hexacarbonyl alone. Thus it can readily be seen that an unexpected beneficial result is obtained when the two additives are used in combination.

When other embodiments of the invention are practiced, as herein described, substantially equivalent results are obtained.

This application is a continuation-in-part of our application, Serial Number 516,052, filed June 16, 1955, and

now abandoned.

The invention claimed is:

.1. A fuel composition consisting essentially of a petroleum hydrocarbon diesel fuel and from 0.005% to 5.0% by weight of additive material consisting of molybdenum hexacarbonyl and a primary alkaryl amine having less than 9 carbon atoms, wherein the molar ratio of said amine to molybdenum hexacarbonyl is in the range of from 6:1 to 1:1.

2. A fuel composition according to claim 1 wherein said amine is toluidine.

References Cited in the file of this patent UNITED STATES PATENTS 1,779,061 Danner et a1 Oct. 31, 1930 1,940,096 Mueller-Cunradi Dec. 19, 1933 2,164,151 Crandall et al June 27, 1939 2,602,049 Smith et al. July 1, 1952 2,860,167 Brown Nov. 11, 1958 OTHER REFERENCES Chromium Hexacarbonyl I, The Preparation and Stability of Chromium Hexacarbonyl, by Cumming et al,. Jour. of Applied Physics (Soc. of Chem, Ind, London), vol. 2, part 2, November 1952, pp. 624-632.

Chromium Hexacarbonyl II, Chromium Hexacarbonyl as a Fuel Additive, by Cumming et al., Journal of Applied Chem. (Soc. of Chem. Ind., London), vol. 5, part I, pp. 39-52, June 22, 1954

Claims

1. A FUEL COMPOSITION CONSISTING ESSENTIALLY OF A PETROLEUM HYDROCARBON DIESEL FUEL AND FROM 0.005% TO 5.0% BY WEIGHT OF ADDITIVE MATERIAL CONSISTING OF MOLYBDENUM HEXACARBONYL AND A PRIMARY ALKARYL AMINE HAVING LESS THAN 9 CARBON ATOMS, WHEREIN THE MOLAR RATIO OF SAID AMINE TO MOLYBDENUM HEXACARBONYL IS IN THE RANGE OF FROM 6:1 TO 1:1.