Internal-combustion engines – Water and hydrocarbon
Patent
1994-10-31
1996-07-16
Solis, Erick R.
Internal-combustion engines
Water and hydrocarbon
123 1A, 44301, F02B 4702
Patent
active
055357083
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process useful for reducing the nitrogen oxides (NO.sub.x, where x is an integer, generally 1 or 2) emissions from a diesel engine to achieve reductions in nitrogen oxides in an efficient, economical, and safe manner not before seen.
One significant drawback to the use of diesel-fueled trucks, buses, passenger vehicles, locomotives, off-road vehicles, etc. (as opposed to gasoline-powered vehicles) is caused by their relatively high flame temperatures during combustion, which can be as high as 2200.degree. F. and higher. Under such conditions there is a tendency for the production of thermal NO.sub.x in the engine, the temperatures being so high that free radicals of oxygen and nitrogen are formed and chemically combine as nitrogen oxides. In fact, NO.sub.x can also be formed as a result of the oxidation of nitrogenated species in the fuel.
Nitrogen oxides comprise a major irritant in smog and are believed to contribute to tropospheric ozone, which is a known threat to health. In addition, nitrogen oxides can undergo photochemical smog formation through a series of reactions in the presence of sublight and hydrocarbons. Furthermore, they have been implicated as a significant contributor to acid rain and are believed to augment the undesirable warming of the atmosphere which is generally referred to as the "greenhouse effect."
Methods for the reduction of NO.sub.x emissions from diesel engines which have previously been suggested include the use of catalytic converters, engine timing changes, exhaust gas recirculation, and the combustion of "clean" fuels, such as methanol and natural gas. Unfortunately, the first three would be difficult to implement because of the effort required to retrofit existing engines. In addition, they may cause increases in unburned hydrocarbons and particulate emissions to the atmosphere. Although the use of clean fuels do not have such drawbacks, they require major changes in a vehicle's fuel system, as well as major infrastructure changes for the production, distribution, and storage of such fuels.
What is desired, therefore, is a method and composition which can achieve significant reductions in the NO.sub.x emissions from diesel engines without requiring substantial retrofitting of the engines, nor an increase in emissions of other pollutants. The method and composition selected should be capable of being instituted on a commercial level without significant infrastructure changes.
BACKGROUND ART
The desirability of improving the efficiency of combustion in a vehicle's engine has long been recognized. For instance, Lyons and McKone is U.S. Pat. No. 2,086,775, and again in U.S. Pat. No. 2,151,432, disclose a method for improving combustion efficiency in an internal combustion engine by adding to the fuel what is described as "relatively minute quantities" of catalytic organometallic compounds. The Lyons and McKone patents, though, are directed solely to internal combustion engines and do not address the problem of NO.sub.x emissions from diesel engines.
In a unique application of catalytic technology described in International Publication No. WO 86/03482 and U.S. Pat. No. 4,892,562, Bowers and Sprague teach the preparation of diesel fuel containing fuel soluble platinum group metal compounds at levels of from 0.01 to 1.0 parts per million (ppm). The Bowers and Sprague results were corroborated and refined by work of Kelso, Epperly, and Hart, described in "Effects of Platinum Fuel Additive on the Emissions and Efficiency of Diesel Engines," Society of Automotive Engineers (SAE) Paper No. 901,492, August 1990. Although the use of platinum group metal additives is effective, further nitrogen oxides reductions are still believed possible.
Moreover, in "Assessment of Diesel Particulate Control--Direct and Catalytic Oxidation," SAE Paper No. 81 0112, 1981, Murphy, Hillenbrand, Trayser, and Wasser have reported that the addition of catalyst metal to diesel fuel can improve the operation of a diesel trap. Among the catalysts disclos
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Platinum Plus, Inc.
Solis Erick R.
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