Fuel and related compositions – Liquid fuels – Boron containing
Reexamination Certificate
2000-11-08
2003-11-11
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Boron containing
Reexamination Certificate
active
06645262
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the chemical arts. In particular, it relates to liquid hydrocarbon fuel compositions, such as low-sulfur diesel and low-sulfur gasoline fuel compositions.
2. Discussion of the Related Art
Liquid hydrocarbon fuels typically contain up to as much as 40,000 ppm sulfur. The sulfur imparts several desirable properties to the fuels. For example, sulfur provides high lubricity in rolling, rotating, or sliding engine parts such as piston rings and liners, fuel pumps, and injector systems. However, sulfur suffers from serious disadvantages. It causes environmental problems in the form of high levels of sulfur dioxide (SO
2
) and hazardous particulates in engine exhaust gases. Because of high SO
2
particulate and emissions, diesel-powered engines are not widely used or permitted in many large cities.
Consequently, there has been a longstanding need to develop low-sulfur hydrocarbon fuel compositions. For example, low-sulfur No. 2 diesel fuel currently contains about 500 ppm sulfur and numerous attempts are being made to further reduce the sulfur content to about 300 ppm sulfur or less. Unfortunately, removing the sulfur reduces the lubricating capacity of the diesel fuel, accelerating wear in fuel system and combustion chamber components. When sulfur is eliminated from fuels, high friction and wear occur on sliding surfaces of fuel-delivery systems and cause catastrophic failure.
Boric acid is environmentally safe, inexpensive, and has an unusual capacity to enhance the antifriction and antiwear properties of sliding metal surfaces. U.S. Pat. No. 5,431,830, to Erdemir, describes adding boric acid to greases, oils, and the like to improve lubricity. The patent suggests that the particles of boric acid, under high pressure and frictional traction, interact with the load-bearing surfaces to provide excellent resilience and load carrying capacity. The layer structure of crystalline boric acid particles can slide over each other with relative ease and can reduce friction and wear.
Boric acid is a crystalline compound, insoluble in hydrocarbons such as greases and oils. Because of the viscous nature of greases and oils, the Erdemir patent teaches that boric acid can be dispersed in the greases and oils simply by using conventional equipment and techniques. This patent also describes solid polymers having boric acid incorporated in the polymeric structure. This patent does not suggest that boric acid can be added to improve the performance of low-sulfur hydrocarbon fuels. Nor does the patent suggest a method for preparing stable suspensions of boric acid in liquid hydrocarbon fuels or any other such low-viscosity hydrocarbon media.
U.S. Pat. No. 3,929,800, to Horowitz, describes a process for simultaneously polymerizing and grafting monomers onto liquid hydrocarbons, to improve various properties including viscosity. Among the liquid hydrocarbons disclosed in the Horowitz patent are post pyrolytic gasoline and catalytic cracking fractions. The patent does not suggest adding boric acid to the liquid hydrocarbons or modifying the process to form stable suspensions of particulate boric acid in such hydrocarbons.
Accordingly, there remains a great need for liquid hydrocarbon fuel compositions that provide high lubricity and low wear in various engine components, such as fuel pumps and injector systems, a clean environment (resulting from the use of low-sulfur fuels), and low cost. There is a further need for stable suspensions containing particulate boric acid in liquid hydrocarbon fuel compositions. The invention meets these needs and provides related advantages as well.
SUMMARY OF THE INVENTION
Now in accordance with the invention there have been found liquid hydrocarbon fuel concentrates containing from about 50,000 ppm to about 250,000 ppm particulate boric acid, based on the total weight of the concentrate, suspended in a liquid hydrocarbon fuel. The liquid hydrocarbon fuels include gasoline, diesel fuel, aviation fuel, jet fuel, boat or motorcycle fuel. In some embodiments the liquid hydrocarbon fuel contains less than 500 ppm or less than 300 ppm sulfur or even substantially no sulfur. In some embodiments, the boric acid has a particle size of about 65 microns or less, preferably, in the range of from about 0.1 to about 2.5 microns or from about 0.5 to about 1 micron. In some embodiments, the concentrate is diluted to form a finished liquid hydrocarbon fuel containing only from about 10 ppm to about 50,000 ppm boric acid, preferably about 30 ppm to about 5,000 ppm, boric acid based on the total weight of the finished fuel, suspended in the fuel composition.
Also in accordance with the invention, there have been found liquid hydrocarbon fuel compositions formed of a reaction product of boric acid having a particle size of about 65 microns or less, preferably, in the range of from about 0.1 to about 2.5 microns, and in some embodiments from about 0.5 to about 1 micron, associated with a liquid hydrocarbon fuel having a monomer or prepolymer chemically grafted thereon. The liquid hydrocarbon fuels include gasoline, diesel fuel, aviation fuel, jet fuel, boat or motorcycle fuel and in some embodiments contains less than 500 ppm, or less than 300 ppm or even substantially no sulfur.
In some embodiments, the monomer or prepolymer is a silane monomer or prepolymer. And in some embodiments, the liquid hydrocarbon fuel composition additionally contains from about 200 ppm to about 600 ppm surfactant, based on the weight of the fuel concentrate and from about 2 ppm to about 6 ppm surfactant, based on the weight of the finished fuel.
The finished liquid hydrocarbon fuel when combusted in an internal combustion engine provides superior lubricity and reduced engine wear, causes less hazardous particulates and gases to be emitted, prevents corrosion, and provides a certain degree of increased fuel economy. Additionally, the boric acid remains suspended in both the concentrate and the finished inventive fuel compositions providing a shelf-life of one to two years.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Boric acid is advantageously added to any liquid hydrocarbon fuel for use in an internal combustion engine such as gasoline, diesel fuel, aviation fuel, jet fuel, boat or motorcycle fuel and, in particular, it is advantageously added to low-sulfur liquid hydrocarbon fuels. Low sulfur liquid hydrocarbon fuel are fuels containing less than 40,000 ppm sulfur. It is an advantage of the liquid hydrocarbon fuels in accordance with the invention that they can contain less than 500 ppm or less than 300 ppm or even substantially no sulfur.
Boric acid useful in accordance with the invention is advantageously produced by the low temperature jet-milling of commercially available boric acid. The conditions of the low temperature jet-milling process can be adjusted to produce boric acid particles having particle size of 65 microns or less, as desired. In preferred embodiments, the boric acid has a particle size in the range of from about 0.1 to about 2.5 microns, preferably in the range of from about 0.5 to about 1 micron.
It is most efficient to initially prepare a concentrated suspension of the boric acid in the liquid hydrocarbon fuel. The concentrate preferably contains from about 50,000 ppm and preferably up to about 250,000 ppm particulate boric acid, based on the weight of the suspension.
The concentrate can then be diluted with additional liquid hydrocarbon fuel to obtain the final desired concentration. The concentration of boric acid in the finished fuel composition will depend on the particular fuel and the particular engine system. Typically, however, the final boric acid concentration will be in the range of from about 10 ppm to about 50,000 ppm and more preferably in the range of from about 30 ppm to about 5,000 ppm, based on the weight of the liquid hydrocarbon fuel composition. For example, the particulate boric acid concentration in no. 2 diesel fuel is in the range of from about 50 ppm to about 25,000 ppm and more
Foscue Charles T.
Horowitz Carl
Mukherjee Satyabrata
Olliges William
Sanduja Mohan L.
Advanced Lubrication Technology Inc.
Medley Margaret
Sonnenschein Nath & Rosenthal
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