Low emission, non-oxygenated fuel composition

Abstract

Provided is an unleaded gasoline fuel which is substantially free of oxygenates, and most preferably contains substantially zero oxygenates. The gasoline fuel also has a Reid vapor pressure less then 7.5 psi, a sulfur content less than 30 ppmw, an aromatic hydrocarbon content between 25 and 30 volume percent, and / or a 50% D-86 Distillation Temperature between 210 and 220.degree. F., and / or a 90% D-86 Distillation Temperature between 300 and 330.degree. F., and the fuel composition fails the California Predictive Model requirements for emissions. Preferably, the olefin content of the fuel is also 8 volume percent or less. Such a gasoline fuel offers a substantially oxygenate free gasoline which avoids the environmental impact of oxygenates, yet when combusted in an internal combustion automobile provides good performance and good emissions, despite failing the California Predictive Model. The gasoline fuel in particular can provide surprisingly lower NO.sub.x emissions than that predicted by the California Predictive Model.

Description

[0001]The present application is a continuation application of U.S. Ser. No. 09 / 071,793, filed May 4, 1998, now abandoned.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to fuels, particularly gasoline fuels which are substantially free of oxygenates. More specifically, the present invention relates to a low-emission gasoline fuel which, upon combustion, provides surprisingly low emissions, particularly of nitrogen oxide emissions, and is also substantially free of oxygen-containing compounds.[0004]2. Brief Description of the Prior Art[0005]One of the major environmental problems confronting the United States and other countries is atmospheric pollution caused by the emission of pollutants in the exhaust gases and gasoline vapor emissions from gasoline fueled automobiles. This problem is especially acute in major metropolitan areas where atmospheric conditions and the great number of automobiles result in aggravated conditions. While veh...

AI Technical Summary

Benefits of technology

[0016]In accordance with the foregoing objectives, the present invention provides an unleaded gasoline fuel which is substantially free of oxygenates, i.e., the fuel contains less than 1.0 weight percent oxygen based on the total weight of the fuel composition, and most preferably contains no oxygen containing compounds. The gasoline fuel of the present invention also has a Reid vapor pressure less than 7.5 psi, a sulfur content less than 30 ppmw, more preferably less than 20 ppmw, an olefin content of no greater than 8 volume percent and an aromatic hydrocarbon content between 25 and 30 volume percent, and / or a 50% D-86 Distillation Temperature between 210 and 220° F., and / or a 90% D-86 Distillation Temperature between 300 and 330° C. The fuel composition also does not meet the emissions performance criteria of the California Predictive Model for emissions. Such a gasoline fuel offers a substantially oxygenate free gasoline which avoids the environmental impact of oxygenates, yet when combusted in an internal combustion automobile provides good performance and good emissions, despite failing the present California Predictive Model requirements.

[0017]In particular, surprisingly low NOx emissions can be observed for the gasoline fuels of the present invention, with the NOx emissions being substantially lower than that predicted by the California Predictive Model established by the California Air Resources Board (CARB). Good Performance with surprisingly low NOx emissions can be obtained despite the fact that the gasoline fuel of the present invention does not meet the specifications for the CARB reformulated gasoline fuel, and fails the California Predictive Model. The gasoline composition of the present invention is substantially free of oxygenates, does not meet the flat limits for at least one, if not more, of the aromatics, T90 and / or T50 requirements set for the new (Phase 2) reformulated gasoline, and fails The California Predictive Model for emissions. Nevertheless, the gasoline fuel of the present invention allows one to enjoy good emissions, and particularly surprisingly low NOx emissions, while also avoiding the potential problems of oxygenates. For it has been surprisingly found that when one controls the amount of sulfur in accordance with the present invention to less than 30 ppmw (and more preferably less then 20 ppmw), and in particular when one controls the amount of sulfur together with olefins in accordance with the present invention to less than 8 volume percent, it is possible to have additional flexibility with respect to the other regulated fuel properties, i.e., aromatics, T90 and T50, in a non-oxygenated fuel without sacrificing low emissions.

[0018]In another embodiment of the present invention, there is provided a method for operating an automotive vehicle having a spark-ignited internal combustion engine. The method comprises introducing into the engine an unleaded gasoline which is substantially free of oxygenates in accordance with the present invention. The unleaded gasoline is then combusted in the engine. In a preferred embodiment, the automotive vehicle also has a catalytic converter through which at least some of the engine exhaust emissions created by combusting the unleaded gasoline are introduced, with the resulting emissions then being discharged from the catalytic converter and subsequently to the atmosphere. Good performance and surprisingly low NOx emissions are realized upon using the unleaded gasoline of the present invention in the operation of an automobile.

Problems solved by technology

One of the major environmental problems confronting the United States and other countries is atmospheric pollution caused by the emission of pollutants in the exhaust gases and gasoline vapor emissions from gasoline fueled automobiles.

This problem is especially acute in major metropolitan areas where atmospheric conditions and the great number of automobiles result in aggravated conditions.

The specifications, however, require the presence of oxygenates in gasoline sold in areas that are not in compliance with federal ambient air quality standards for ozone, and the degree of non-attainment is classified as severe, or extreme.

As a result, the public is beginning to question the benefits and / or importance of having cleaner burning gasolines, if they simply pollute the environment in other ways.

Furthermore, oxygenates also have a lower thermal energy content than non-oxygenated hydrocarbons, and therefore reduce the fuel economy of gasoline fueled motor vehicles.