1. Field of the Invention
The present invention relates generally to reducing the amounts of pollutants produced during the combustion of carbonaceous fuels such as gasoline, diesel fuel, fuel oil, and coal. More particularly, the present invention relates to materials that can be added to the fuel prior to combustion in order to reduce the level of pollutants emitted as a result of the combustion process.
2. Description of Related Art
The combustion of carbonaceous fuels is a major source of air pollution. The primary pollutants produced as a result of the combustion of such fuels include carbon monoxide, nitrogen oxides, sulfur oxides, unburned hydrocarbons, particulate matter, and volatile organic compounds.
There is today considerable interest in developing processes for eliminating or substantially reducing the amounts of pollutants that are emitted into the atmosphere as a result of fuel combustion. One approach involves treating the fuel prior to combustion in order to remove pollutant precursors. For example, numerous desulfurization processes have been devised to remove sulfur from fuel oil, coal, and other fuels prior to combustion. Although it is desirable to use preprocessed fuels that are inherently clean-burning, such fuels are expensive to produce.
Another approach to reducing air pollution involves treating the combustion gases to remove pollutants. A wide variety of adsorbents, as well as catalytic materials, have successfully been used for the removal of pollutants from combustion gases, including carbon monoxide, nitrogen oxides, and sulfur oxides. For example, catalytic mufflers have been successfully used in automobiles to reduce pollutant emissions. Other scrubber devices have also been employed with some success in the removal of pollutants from a variety of combustion flue gases.
In addition to the above pollution-control mechanisms, there has also been interest in developing fuel additives that can be mixed with the fuel prior to combustion. The fuel additive participates in the combustion process, and its components act as scavengers or otherwise react with pollutants to convert them into nonpolluting combustion products. An example of this type of fuel additive is disclosed in U.S. Pat. No. 4,274,835, and involves improving combustion efficiency and reducing sulfur combustion emissions from burning coal by the addition of small amounts of chlorophyll, squalane, squalene, carotenoids, or mixtures thereof.
Many other processes have been developed over the years that are also effective in controlling pollutant emissions. However, the importance of reducing the amounts of substances emitted into the air mandates that researchers continue to seek new and improved methods for limiting the pollutants produced as a result of the combustion of carbonaceous fuels.