Fuel and related compositions – Liquid fuels – Organic nitrogen compound containing
Reexamination Certificate
1999-08-31
2001-01-23
Johnson, Jerry D. (Department: 1764)
Fuel and related compositions
Liquid fuels
Organic nitrogen compound containing
C044S424000
Reexamination Certificate
active
06176886
ABSTRACT:
TECHNICAL FIELD
The present invention relates to fuel compositions comprising additives for low sulfur, middle-distillate, compression ignition fuels, that increases the lubricity of the fuel without adding factors that would damage the fuel system of a vehicle using said fuel compositions or cause an increase in undesirable combustion by-products.
BACKGROUND OF THE INVENTION
Problems associated with fuel lubricity arose in the mid- 1960's when a number of aviation fuel pump failures occurred. After considerable research, it was realized that advances in the refining of aviation turbine fuel had resulted in the almost complete removal of the naturally occurring lubricating components from the fuel. The removal of these natural lubricants resulted in the seizure of fuel pump parts. By the mid-1980's, it seemed likely that a similar problem was imminent in diesel fuel pumps. Fuel injection pump pressures had been steadily increasing while there was also a growing concern to reduce the sulfur content of the diesel fuel. The desire to reduce the sulfur content of the diesel fuel, in an effort to reduce pollution, required the use of more rigorous fuel refining processes. It was determined that as refining processes became more stringent, the naturally occurring oxygen containing compounds and polyaromatics which contribute to diesel fuel's inherent lubricity were eliminated.
Environmental concerns have led to a need for fuels with reduced sulfur content, especially diesel fuels. However, the refining processes that are used to produce fuels with low sulfur contents also result in a product of lower viscosity and a lower content of other components in the fuel that contribute to its lubricity, for example, polycyclic aromatics and polar compounds. Furthermore, sulfur containing compounds in general are regarded as providing anti-wear properties and a result of the reduction in their proportions, together with a reduction in proportions of other components providing lubricity, has been an increase in reported failures of fuel pumps in diesel engines using low sulfur fuels.
This problem may be expected to become worse in the future because in order to meet stricter requirements on exhaust emissions, high-pressure fuel pumps are being introduced and are expected to have more stringent lubricity requirements than present equipment.
In certain types of in-line diesel injection pumps, engine oil contacts diesel fuel. Engine oil may also come into contact with the diesel fuel through direct addition of used engine oil to the fuel. Certain types of lubricity additives used in low sulfur diesel fuel have been found to contribute to fuel filter blockage and to pump plunger sticking. Lubricity additives having poor compatibility with engine oil have been shown to cause these problems. Compatibility is defined as the tendency for the diesel fuel containing the lubricity additive not to form fuel insoluble deposits, gels or heavy sticky residues when in contact with engine oil. These deposits, gels or residues have been shown to cause fuel filter blockage and injection pump sticking. The additives of the present invention are compatible with engine oil.
Mannich reaction products have been taught for use as detergent/dispersants in fuels, primarily gasoline, for years. The prior art Mannich reaction products typically contain high molecular weight alkyl groups on the hydroxyaromatic compounds. In contrast, the Mannich reaction products of the present invention are obtained from alkyl-substituted hydroxyaromatic compounds wherein the alkyl group contains from 9 to 30 carbon atoms.
U.S. Pat. No. 3,877,889 discloses Mannich bases useful as additives for liquid fuels to impart dispersancy, anti-icing and rust inhibiting properties. The reference fails to teach the use of said Mannich reaction products as lubricity additives in low sulfur compression ignition fuels.
U.S. Pat. No. 4,231,759 teaches reaction products obtained from the Mannich condensation of high molecular weight alkyl-substituted hydroxy aromatic compounds, amines and aldehydes for improving the detergency of liquid hydrocarbon fuels.
U.S. Pat. No. 5,853,436 discloses diesel fuel compositions containing a lubricity enhancing amount of a salt of an alkyl hydroxyaromatic compound and an aliphatic amine. These salts are different than the reaction products of the present invention.
While the prior art is replete with numerous treatments for fuels, it does not disclose the addition of the present additives to low sulfur compression ignition fuels or teach their use for providing enhanced lubricity to said fuels.
SUMMARY OF THE INVENTION
The present invention relates to the treatment of a low sulfur, middle-distillate, compression-ignition fuel to substantially reduce the wear occasioned upon fuel pumps used to pump said fuels. The present invention also relates to the discovery that the addition to a fuel of the reaction products of the present invention will significantly improve lubricity as compared to a similar fuel that has not been treated with said additive. Further, the present invention provides an additive that is economical, will not damage the fuel system, will not cause an increase in the level of undesirable combustion products and is lubricant compatible.
Thus, there is disclosed a fuel composition comprising a major amount of a low sulfur, compression ignition fuel and a minor amount of a Mannich additive. This Mannich additive unexpectedly decreases the fuel composition's ability to cause wear to fuel pump components that come into contact with said fuel composition. The Mannich additive is preferably present in the fuel in an amount within the range of from about 10 parts by weight of additive per million parts by weight fuel (ppm w/w) to about 1000 ppm w/w. More preferably, the Mannich additive is present in the fuel in an amount within the range from about 20 ppm w/w to about 500 ppm w/w, most preferably, from about 30 ppm w/w to about 300 ppm w/w.
There is also disclosed a method for reducing the wear of fuel pumps through which a fuel is pumped, comprising adding a fuel-soluble additive to said fuel wherein the fuelsoluble additive comprises a Mannich additive and wherein the Mannich additive is added to the fuel in an amount effective to improve the lubricity of the fuel, typically, the Mannich additive is present in the fuel composition in an amount of at least 10 ppm w/w, preferably from 20 to about 500 ppm w/w.
Also disclosed is a fuel composition comprising a low sulfur content, compression ignition fuel and a lubricity additive, said lubricity additive comprising a Mannich additive obtained by reacting a low molecular weight alkyl-substituted hydroxyaromatic compound, an aldehyde and an amino-alcohol under suitable Mannich condensation reaction conditions to obtain said Mannich additive.
In view of the problems discussed above, a general aspect of the present invention is to provide a fuel additive to protect the fuel pump from excessive wear and breakdown. A further aspect of the invention is to provide a fuel-soluble additive suitable for addition to a fuel that does not damage the fuel system and does not cause an increase in undesirable combustion products. Yet another aspect of the invention is to provide a fuel additive that works in conjunction with other additives such as detergents so that the life of the internal combustion engine, and especially the fuel pump, can be extended.
DETAILED DESCRIPTION OF THE INVENTION
The Mannich reaction products useful as lubricity additives in the fuel compositions of the present invention are fuel-soluble reaction products obtained by the reaction of a low molecular weight alkyl-substituted hydroxyaromatic compound, an aldehyde an amino-alcohol under suitable Mannich reaction conditions.
The low molecular weight alkyl-substituted hydroxyaromatic compounds and aldehydes used in the preparation of the Mannich reaction products of the present invention may be any such compounds known and applied in the art, in accordance with the foregoing limitatio
Henly Timothy J.
Loper John T.
Quigley Robert
Ethyl Corporation
Hamilton Thomas
Johnson Jerry D.
Moore James T.
Rainear Dennis H.
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