AU2002305324A1 - Method and an unleaded low emission gasoline for fuelling an automotive engine with reduced emissions - Google Patents

Description

METHOD AND AN UNLEADED LOW EMISSION GASOLINE FOR FUELING AN AUTOMOTIVE ENGINE WITH REDUCED EMISSIONS

Related Applications

This invention is entitled to and hereby claims the benefit of the filing date of U. S. provisional application number 60/288,054, entitled "METHOD FOR FUELING AN AUTOMOTIVE ENGINE WITH REDUCED TOTAL EMISSIONS FROM A MODIFIED REFINING PROCESS IN COMBINATION WITH A GASOLINE SUITABLE FOR USE IN AN AUTOMOTIVE ENGINE" filed May 2, 2001 ; and U. S. provisional application number 60/288,142, entitled "METHOD FOR FUELING AN AUTOMOTIVE ENGINE WITH REDUCED TOTAL EMISSION FROM A MODIFIED REFINING PROCESS IN COMBINATION WITH A GASOLINE SUITABLE FOR USE IN AN AUTOMOTIVE ENGINE" filed May 2, 2001. Field of the Invention

The invention relates to a method for reducing the emissions of total hydrocarbons, carbon monoxide, and nitrogen oxides from an internal combustion automotive engine upon combustion of gasoline therein to power the engine. In some embodiments, the invention relates to an unleaded reduced emissions gasoline having an octane less than 86.7, and a sulfur content less than about 40 ppmw. In other embodiments, the invention relates to a combined process in which a refinery is operated with reduced emissions to produce the unleaded low emission gasoline, and to a system for distributing the unleaded low emissions gasoline. Background of the Invention

In recent years, there has been increasing concern over the availability of worldwide supplies of crude oil and other fluid hydrocarbon feedstocks and fuels. There also have been concerns about the emission of undesirable materials into the atmosphere from the combustion of fuels, such as gasoline, in internal combustion engines.

The foregoing concerns have caused governments to require the use of reformulated gasolines in areas of acute air pollution such as California. For example, California has enacted requirements for a "Phase 2" California reformulated gasoline. (Title 13 C.C.R, Sections 2250-2273 (including test method amendments effective September 27, 2001)). These fuel specifications contained therein are referred to herein as "California formulated gasoline specifications." The requirements of ASTM D4814-01a, approved November 10, 2001, hereby incorporated by reference, also are widely applicable to gasolines manufactured or sold in the United States. In other areas of the world, federal, regional and local governmental entities may apply similar or other requirements.

Cleaner burning gasolines typically require more refining to produce the desired gasoline properties in the gasoline. Typically, the gasolines produced today for operation in relatively low altitudes have a minimum octane requirement of 87 for regular gasoline or a minimum octane requirement of 92 for premium gasoline. The octane values referred to are a combination of the research motor octane number plus the motor octane number divided by two, i.e., (R+M)/2. Manufacturing cleaner burning gasolines typically requires the production in a refining operation of high-octane blending components. Typically, such high-octane blending components are produced in alkylation and reforming units. In some instances, octane also or alternatively may be increased by the addition of dimers of isobutene or isobutene with n-butene. The foregoing materials may be used alone or in combination to increase octane of gasolines.

The operation of units such as a reformer or an alkylation unit is relatively energy intensive and requires substantial quantities of methane, refinery gas, or other energy sources. The energy required increases with the severity of unit operation. As a result of more severe of the processing, some of the feedstocks are lost to unusable products, and refinery emission may increase. Thus, the requirement for higher octane blending components coupled with the requirement for specific compositional requirements in the reformulated gasoline ultimately requires more energy and crude oil or other gasoline component to produce a given quantity of gasoline than was previously the case.

In the production of reformulated gasoline, added refining steps may also be necessary to produce the desired amount of high octane blending components, remove undesirable compounds and modify the properties of other fuel blending streams, such as by isomerization of C₅ range paraffins and the like, to meet the rather stringent distillation and other requirements of reformulated gasoline. This also can increase refining expense and the amount of crude oil required to produce reformulated gasoline when compared to non-reformulated gasoline.

While the use of reformulated gasoline is considered to reduce emissions from automobiles, the emission of pollutants to the atmosphere from engines fueled with reformulated gasoline must be considered in combination with the increased emissions to the atmosphere from the refineries producing such fuels, especially carbon dioxide, which has been the subject of attention recently with respect to possible greenhouse effects.

Summary of the Invention

In a first embodiment, this invention relates to an unleaded low emissions gasoline for use in internal combustion engines having an octane (R+M)/2 less than 86.7 and a sulfur content less than about 40 ppmw.

In another embodiment, this invention relates to an unleaded low emissions gasoline for use in an internal combustion automotive engine having an octane (R+M)/2 less than an adjusted octane number, as defined herein. Combustion in the automotive engine produces emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to a comparable unleaded minimum 87 octane gasoline that are no greater than from the unleaded minimum 87 octane gasoline. In some embodiments, the fuel includes a selected quantity of one or more oxygenates selected from the group consisting of ethanol, methyl tertiary butyl ether, ethyl tertiary butyl ether and tertiary amyl methyl ether. Combustion of the reduced emissions gasoline in the automotive engine produces reduced emission of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to combustion in the engine of a comparable unleaded minimum 87 octane gasoline. In preferred cases, at least two of total hydrocarbons, carbon monoxide and nitrogen oxides are reduced by comparison to combustion of a comparable unleaded minimum 87 octane gasoline in the engine. Still other embodiments of this invention relate to methods for reducing emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides from an internal combustion automotive engine, in which an unleaded reduced emissions gasoline having an octane (R+M)/2 less than 86.7 is produced which, upon combustion in the engine, produces reduced emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to a comparable unleaded minimum 87 octane gasoline; and, in which an engine or a fleet of at least 100 vehicles is fueled with the unleaded reduced emissions gasoline.

Yet another embodiment of the invention relates to a method for fueling automotive vehicles with reduced total emissions to the atmosphere, the method comprising: a) operating a refinery to produce an unleaded reduced emissions gasoline having an octane (R+M)/2 less than 86.7 which upon combustion in the engine produces reduced emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to a comparable unleaded minimum 87 octane gasoline, the unleaded reduced emissions gasoline being produced in the refinery from a reduced quantity of feedstock and with reduced emissions by comparison to a refinery operated to produce the minimum 87 octane gasoline; and, b) fueling automotive vehicles with the unleaded reduced emissions gasoline, the total emissions of at least one of total hydrocarbons, carbon monoxide, carbon dioxide and nitrogen oxides for the vehicles and for the refinery producing the reduced emissions gasoline being less than for a refinery producing the unleaded minimum 87 octane gasoline and for the vehicles fueled with minimum 87 octane unleaded gasoline.

Brief Description of the Drawings

Figure 1 is a graph showing the carbon monoxide emissions from the vehicles and the fuels tested;

Figure 2 is a graph showing the total hydrocarbon emissions from the vehicles and the fuels tested;

Figure 3 shows the nitrogen oxide emissions from the vehicles and the fuels tested; and

Figure 4 shows the fleet average emissions for each of the fuels tested for total hydrocarbons, carbon monoxide, and nitrogen oxides.

Description of Preferred Embodiments

Gasolines are well known fuels, as disclosed in U.S. patent 5,288,393 issued February 22, 1994 to Jessup et al, generally composed of a mixture of hydrocarbons boiling at atmospheric pressure in a very narrow temperature range, e.g., 77° F. (25° C.) to 437° F. (225° C). Gasolines typically are composed of mixtures of aromatics, olefins, and paraffins, although some gasolines may also contain such added heteroatom containing material such as such as alcohol (e.g., ethanol) or other oxygenates (e.g., methyl tertiary butyl ether). Gasolines may also contain various additives, such as detergents, anti-icing agents, demulsifiers, corrosion inhibitors, dyes, deposit modifiers, as well as octane enhancers such as tetraethyl lead, where permitted by law. Typically unleaded gasolines contain a concentration of lead no greater than 0.05 gram of lead per gallon (0.013 gram of lead per liter). The unleaded gasoline will typically have an octane value (R/2+M/2) for regular gasoline of at least 87 and for premium of at least 92.

Such gasolines typically are used to fuel internal combustion engines used to propel automotive vehicles and for other purposes to which such engines are known to be suited. Such gasolines may also be used in other types of internal combustion engines, such as homogeneous charge compression ignition engines in which the fuel and air are injected as a homogeneous mixture prior to compression. For purposes of this application, "gasolines" are materials generally available to consumers for automotive purposes, and do not include materials prepared for further processing or blending into fuel mixtures prior to sale of the gasoline to the consumer.

Presently most gasoline sold in the United States for use in automotive engines has an octane (R+M)/2 of at least 87 for regular and of at least 92 for premium. These octane levels are considered necessary to prevent knocking and auto-ignition in automotive engines. As well-known in the art, octane levels typically are adjusted from a nominal octane number to account for reduced atmospheric pressure or climatic variation. For instance, an 84.5 octane fuel for use in the highest regions of the mountainous western portion of the United States is believed to provide approximately the same performance with respect to octane as an otherwise similar 89 octane fuel at sea level. Climatic variations may also account for a reduction of up to about one octane. When an octane number is specified as an "adjusted octane number" in this application it refers to an octane of 87, reduced by an incremental octane amount which compensates for altitudinal and/or climatic variations to yield a gasoline of equivalent performance at the altitude and climate of use. Typically, data-are available for a given geographical region in the form of a table or map of the types provided in ASTM D4814- 01a, which provide reductions of octane from nominal sea level numbers as a function of location and/or season.

The specifications and octane requirements discussed above require modification of gasoline blending streams available in most refineries. In particular, to meet the California reformulated gasoline specifications, it is frequently necessary to adjust the olefin content of the gasoline, to adjust the paraffin content of the gasoline, to adjust the aromatics content of the gasoline, and the like. It is, of course, also necessary to adjust the octane of the gasoline to meet minimum octane requirements, and to adjust the T10, T₅₀ and T_go specifications, as well as Reid Vapor Pressure and other specifications as is well known in the art.

According to the present invention it surprisingly has been found that adequate performance and reduced emissions can be achieved with an unleaded reduced emissions gasoline for use in an internal combustion automotive engine having an octane (R+M)/2 less than 86.7, which upon combustion in the internal combustion automotive engine produces emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides which are less by comparison to a comparable unleaded minimum 87 octane gasoline for use in an internal combustion automotive engine. The unleaded minimum 87 octane gasoline and the unleaded reduced emissions gasoline are desirably both in compliance with regulatory specifications such the California reformulated gasoline specifications, or ASTM D4814-01a, or other specifications as required by the location of fuel manufacture or use. In many instances it has been found that at least two of total hydrocarbons, carbon monoxide and nitrogen oxides emissions, and in some instances all three, are equal to or less than emissions from a comparable 87+ octane unleaded gasoline.

Reference to a "comparable" fuel or gasoline refers to a fuel or gasoline that has similar compositional properties to the unleaded reduced emissions gasoline. It is considered that the reduced emissions realized by the present invention may be realized with many gasoline formulations but for comparison purposes, the reduced emissions achieved using the unleaded reduced emissions gasoline are most appropriately determined by comparison to a gasoline of the same or a similar composition wherein only the octane, sulfur content or oxygenate content, or combination thereof, are varied from the comparative fuel in accordance with the present invention. It is recognized that some compositional changes in the comparative gasoline typically will be necessary to change the indicated properties but compositional change typically will be minimal. For example, such changes will be of the type and amount as may be determined by a refinery blending program in response to a request for lower octane gasoline as is well known in the art.

Typically, emissions from combustion of the unleaded reduced emissions gasoline are lower in total hydrocarbons and carbon monoxide than the emissions from the combustion of the unleaded minimum 87 octane gasoline. Desirably, the octane of the unleaded reduced emissions gasoline is from about 80 to 86.7. The octane may be about 86 or lower, and in some cases preferably from 80 to about 83.5 octane. The unleaded reduced emissions gasoline may contain one or more oxygenates commonly used for the introduction of oxygen into gasolines. Suitable oxygenates are ethanol, methyl tertiary butyl ether, ethyl tertiary butyl ether, tertiary amyl methyl ether and the like, or combinations thereof. Typically, amounts of oxygenate sufficient to provide oxygen in the gasoline range in an amount from about 0.1 to about 10 weight percent are used. Preferably the amount is from about 0.3 to about 5.0 weight percent and desirably from about 2 to about 5 weight percent. Of the oxygenates, ethanol and methyl tertiary butyl ether are preferred and of these ethanol is most preferred. When ethanol is used, it is typically added in amounts equal to from about 0.1 to about 10 vol. % of the gasoline. These amounts could vary dependent upon future gasoline specifications regulations and the like. The full range of reduced octane values may be used with the gasoline with or without the oxygenates.

It is further desirable that the unleaded reduced emissions gasoline contains less than about 40 ppmw (parts per million by weight) of sulfur. Preferably, the sulfur is present in an amount less than about 30 ppmw, desirably, less than about 15 ppmw and more desirably, less than about 10 ppmw, and most desirably, less than about 5 ppmw.

The unleaded reduced emissions gasoline may be produced with an octane in the range described and containing an oxygenate in a selected amount and with the low sulfur content. Either the oxygenates or the low sulfur content alone may be used in combination with the low octane values to achieve desirable results. Many of the gasolines of the present invention are within the specifications for California reformulated gasoline as well as in compliance with all ASTM D4814-01a and other federal, state, and local gasoline specifications. Specifically, ethanol contents of the gasoline may be required to be up to 10 vol. % or higher.

While the use of the unleaded reduced emissions gasoline of the present invention in a single vehicle is effective to reduce emissions from the single vehicle it is more effective when the gasoline is used to fuel a fleet of vehicles. By this approach, the emissions may be reduced from a large number of vehicles as well as from a single vehicle. A fleet of vehicles is used to refer to any substantial number of vehicles (i.e., 100 or more vehicles) that may be operated using the unleaded reduced emissions gasoline of the present invention. The terms "fuel or "fueling" as used herein refer to providing the unleaded low emissions gasoline to automotive vehicles and combustion of the fuel therein to power the vehicles.

Further, it may be desired to reduce the pollution in an area and the emissions may be reduced in the area by distributing the unleaded reduced emissions gasoline via a plurality of distribution networks to distribution outlets from which it may be distributed to a fleet of selected vehicles or to randomly service automotive vehicle customers. In such instances the emissions from automotive vehicles in the area can be reduced.

It also should be noted that the emissions resulting from fueling automotive vehicles results from the emissions from the vehicle itself and also from the emissions from the refinery in which the gasoline to fuel the automotive vehicle is produced. According to the present invention the refinery may be operated to produce more gasoline per a given volume of gasoline feedstock as a result of the lower octane requirements of the gasoline. Such refinery operation may involve changes in the operation of at least one of a fluid catalytic cracker, a reformer, an alkylation unit, an isomerization unit, and the like, as known to those skilled in the art. As a further result of the operation of the refinery in this manner the refinery requires less fuel for heat and other operations to produce the reduced quantity of higher-octane blending components. Typically, the greater the reduction in octane the greater the improvement in the volume of gasoline generated from a given volume of feedstock and trie greater the reduction in the emissions from the refinery. Typically, the refinery emissions are primarily carbon dioxide and in recent years considerable attention has been directed to methods for reducing the emission of carbon dioxide.

In one computer simulation of a refinery operation, assuming a gasoline pool of 800,000 barrels per day of 87 octane gasoline as a base case, the alteration of the refinery operation to produce gasoline having an octane of 86 results in production of an additional 35,280 gallons of gasoline per day from the same quantity of the same feedstock with a concurrent reduction of more than 17,000,000 pounds per year of carbon dioxide emitted from the refinery and a reduction of over 6,000,000 pounds per year of natural gas required for fuel. The net result is a substantial savings in the refinery requirements for light hydrocarbons or other fuel and a substantial reduction in the amount of carbon dioxide emitted into the atmosphere. Because the refinery operates at reduced emissions into the atmosphere and produces the gasoline of the present invention from a reduced quantity of feedstock considerable efficiency and emissions reduction is accomplished. Also, a substantial reduction of the total emissions into the atmosphere as a result of the production and use of the lower octane gasoline for automotive engines is realized. In this regard it should be noted that even if the use of the lower octane gasoline in an automotive engine resulted in the same amount of emissions as with the 87 and higher octane fuels there would still be a net reduction of the emissions to the atmosphere as a result of the increased efficiency of and reduced emissions from the refinery operation. Examples

Tests were performed to determine exhaust emissions from a three vehicles using lower (less than 86.7) octane gasolines by comparison to 87 minimum octane gasolines. The gasolines tested are shown in Table 1. These gasolines were prepared from refinery streams or components considered equivalent to the refinery streams. The refinery streams used were an isomerate stream, a heavy reformate and catalytically cracked naphtha, a heavy raffinate, and a light alkylate, with toluene being used as a substitute for light reformate and mixed iso-hexanes as a substitute for light raffinate. Light reformate is typically considered to be primarily a C₇-C₈ stream which is predominantly toluene, thus toluene is representative of this stream. Similarly the mixed iso-hexanes are considered to be a close substitute for the light raffinate. It is also noted that the olefin levels in the fuels tested were relatively low. This was a result of the difficulty in finding suitable low sulfur blending stocks that were low in sulfur with higher olefin contents. The low olefins content is not considered to have any disparate effect on the validity of the test results. The gasolines tested have been designed to have closely comparable octane, sulfur content and oxygenate content. Ethanol was the oxygenate fuel tested and was supplied as a commercial fuel grade material. The fuel properties were targeted to meet the California reformulated gasoline specifications, except for fuel 4 as noted below. The term "fuel" is used synonymously with the term "gasoline" herein. Fuels 1 and 6 have a standard octane of 87+. Fuel 1 has a relatively high sulfur content (70 ppmw) and an 87.4 octane with fuel 6 having a low sulfur content, (<5) with an 87.2 octane. The sulfur level of the low octane fuels 2-5 was reduced to less than 5 ppmw to anticipate further low sulfur regulations. Fuel 4 has an octane value of 83.1 but also has a 90° F distillation temperature of 338°, which exceeds the California reformulated gasoline specifications but would meet the requirements in other areas. Fuel 5 was blended with enough ethanol to give 2 weight percent oxygen in the fuel. Two more fuels 7 and 8 were prepared and tested using varying sulfur content with octanes of 85.8 and 85.3 respectively and higher sulfur levels of 37 and 72 ppmw, respectively.

TABLE 1

FUEL PROPERTIES

Fuel 1 2 3 4 5 6 7 8

Anti-knock Index, (R+M)/2 87.4 80.3 84.9 83.2 81.4 87.2 85.8 85.3

Sulfur (ppmw) 70 <5 <5 <5 <5 <5 37 72 (ASTM D 5453)

Research Octane Number 90.5 82.5 87.2 85.5 83.5 89.6 88.4 87.9 (ASTM D 2699)

Motor Octane Number 84.2 78.1 82.5 80.8 79.2 84.7 83.1 82.6 (ASTM D 2700)

Reid Vapor Pressure (psi) 6.7 6.7 6.5 6.4 6.8 6.1 6.6 6.4 (ASTM D 5191)

10% Distillation Temp. (°F) 142 140 142 140 135 148 141 142 (ASTMD 86)

50% Distillation Temp. (°F) 202 199 209 212 196 201 204 205 (ASTMD 86)

90% Distillation Temp. (°F) 298 292 295 338 291 281 291 296 (ASTM D 86)

API Gravity (°API) 61.5 62.6 62.2 62.3 61.5 62.9 61.6 61.2 (ASTMD 4052)

Aromatics (Vol. %) 25 25 25.5 22 25 22.3 24.7 25.2 (ASTM D 1319)

Olefins (Vol %) 1.5 0 0 1.5 0 0 0.6 0.7

(ASTM D 5580)

Saturates (Vol %) 73.5 75 74.5 76.5 74.6 77.7 74.7 74.1 (ASTM D 1319)

Benzene (Vol. %) 0.17 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.16 (ASTM D 1319)

Ethanol (Vol. %) 0.0 0.0 0.0 0.0 5.6 0.0 0.0 0.0

(measured addition) Duplicate emission tests on each fuel were conducted using the Federal test procedure (FTP) on the first six fuels in three vehicles. The FTP (Federal Test Procedure) specified herein refers to Code of Federal Regulations, Volume 40, "Protection of the Environment," Subpart B, "Emission Regulations for 1977 and Later Model Year New Light-duty Vehicles and New Light-Duty Trucks; Test Procedures, herein incorporated by reference in its entirety. The test vehicles were a 1998 Honda Accord with California low emission vehicle (LEV) certification, a 1999 Dodge Caravan with national low emissions vehicle (NLEV) certification, and a 2000 Ford Explorer. Table 2 shows the emission test results for total hydrocarbons, carbon monoxide, and nitrogen oxides from the tests with the various fuels.

Table 3 and Figures 1 , 2, and 3 show the averages of these results for each fuel/vehicle combination. The fleet average emissions (i.e., each emission averaged over the three vehicles) are shown in Figure 4. In addition, duplicate FTP tests were run on fuels 7 and 8 using only the 1998 Honda Accord. The individual vehicle test results are included in Table 2 and the trends with lower octane fuels are shown in Figures 1 , 2, and 3.

TABLE 3

Average Emission Test Results

AVERAGE EMISSIONS*

Vehicle Fuel THC CO NOx

Ford Explorer 1 0.0845 1.1410 0.0375

Ford Explorer 2 0.0820 0.9180 0.0375

Ford Explorer 3 0.0805 1.0520 0.0295

Ford Explorer 4 0.0890 0.8770 0.0295

Ford Explorer 5 0.0840 1.0640 0.0370

Ford Explorer 6 0.0880 1.0625 0.0230

Honda Accord 1 0.0990 2.1870 0.1225

Honda Accord 2 0.0740 1.6730 0.0805

Honda Accord 3 0.0845 2.2000 0.0955

Honda Accord 4 0.0875 1.5110 0.0885

Honda Accord 5 0.0675 1.3395 0.1070

Honda Accord 6 0.0790 2.0455 0.0685

Honda Accord 7 0.0905 2.1515 0.0745

Honda Accord 8 0.0785 1.7725 0.0995

Dodge Caravan 1 0.1045 0.5655 0.1540

Dodge Caravan 2 0.1050 0.8015 0.1515

Dodge Caravan 3 0.0875 0.6410 - 0.1450

Dodge Caravan 4 0.0890 0.4075 0.1130

Dodge Caravan 5 0.0900 0.5280 0.1300

Dodge Caravan 6 0.0900 0.6760 0.1105

ALL EMISSIONS VALUES ARE SHOWN IN GRAMS PER MILE The fleet average total hydrocarbon emissions and the carbon monoxide emissions for all of the low sulfur, low octane gasolines (fuels 2-5) were either less, or not significantly different, than either the lower sulfur (less than 5 ppmw) or the higher sulfur (70 ppmw) 87 minimum octane gasolines. This is unexpected in that the low octane gasoline would be expected to cause knock, which is auto-ignition induced combustion. Such auto-ignition combustion could cause fuel/air mixture inhomogeneities that would increase the carbon monoxide and total hydrocarbon emissions during the cold phase of the test and increase local temperatures and pressures that would increase NOx. For NOx the lower sulfur 87 minimum octane gasoline (fuel 6) had the lowest emission level and the higher sulfur 87 minimum octane gasoline (fuel 1) had the highest emission level while the lower octane gasolines had emissions between the two.

Further tests were conducted with fuel 5. This fuel contained 2% oxygen (as ethanol) but otherwise was substantially the same as fuel 2. Basically, fuel 5 was produced to be the same as fuel 2 except that ethanol was added and isomerate was removed to keep the vapor pressure constant. The ethanol fuel (fuel 5) average CO emissions were significantly less than fuel 2 but its total hydrocarbon and NOx emissions were not significantly different. In additional tests run with the Honda Accord, using fuels of varying sulfur content, it was determined, that with this particular engine, the general trend is increasing CO emissions with increasing octane, lower carbon monoxide with the inclusion of ethanol, lower carbon monoxide with higher 90% distillation temperatures, with relatively small effects of sulfur and its interaction as a function of the octane. For total hydrocarbon emissions a general trend of increasing total hydrocarbon emissions with increasing octane level was noted. Statistically, there appears to be an interaction between sulfur and the octane level. Practically, this can be interpreted as the sulfur having a different effect on low octane gasoline compared to high-octane gasoline. Only the 37 parts per million sulfur, low octane gasoline was observed to make statistically higher total hydrocarbons emissions than the 5 parts per million 87 minimum octane fuel. Inclusion of the octane/sulfur interaction in the statistical analysis resulted in confirmation of increasing total hydrocarbon emissions with increasing octane.

The statistical analysis of the data also indicated a large interaction between the octane and sulfur content with respect to NOx emissions. It was also concluded that NOx increases as the octane increases. Ethanol appeared to statistically increase the amount of NOx emissions. It appears that all of the values for NOx emission for the low octane fuels fell between the two 87 octane fuels, one of which had a high sulfur content and the other of which had a low sulfur content. It appears that the NOx emissions from the lower octane fuels are not substantially different than the California Phase 2 gasolines (Fuels 1 and 6).

In Figure 1 , the carbon monoxide emissions for the various fuels for the various vehicles tested are shown. In Figure 2 the total hydrocarbon emissions are shown, in Figure 3 the nitrogen oxide emissions are shown and in Figure 4 the fleet average emissions are shown.

In view of this data it appears that reducing the octane level of gasoline has no detrimental effects and that reducing the octane results in reduced emissions from the engines tested with the fuels tested. Accordingly, it appears that reducing the octane level of a gasoline has beneficial results with respect to the reduction of emissions upon combustion of the gasoline in an internal combustion automotive engine. Such fuels typically can be produced readily in compliance with all U.S. federal, state, local, and California gasoline requirements unless octane is a regulated property in a particular state or local specification. Accordingly, this improvement in emissions can readily be achieved. While greatest improvements are achieved by reduction of the octane in combination with the use of low sulfur containing gasolines it is also desirable that an oxygenate be included to reduce carbon monoxide emissions and for regulatory compliance. It also appears that the ethanol reduces the CO emissions upon the combustion of the gasoline.

As further discussed above, it appears that the amount of carbon dioxide emission from the refinery wherein the gasoline is produced can be greatly reduced while increasing the volume of gasoline from a given feedstock. It further appears that natural gas or other fuels may be conserved by production of gasoline having an octane value less than 87.

In total it appears that the gasoline of the present invention can be produced by a refinery, which can operate at lower emission conditions and more efficient conditions in that it produces a greater quantity of gasoline from a given quantity of feedstock with reduced emissions. It has been shown that the gasoline of the present invention when combusted in internal combustion engines results in reduced emissions by comparison to currently available standard gasolines. This is surprising and unexpected in view of the widely established practice of requiring an octane of 87 minimum for regular and a minimum octane of at least 91 , and more typically 92 for premium.

Having thus described the invention by reference to its preferred embodiments it is respectfully pointed out that the embodiments described are illustrative rather than limiting in nature and that many variations and modifications are possible within the scope of the present invention.

Claims (27)

We claim:

1. An unleaded low emissions gasoline for use in an internal combustion engine having an octane (R+M)/2 less than 86.7 and a sulfur content less than about 40 ppmw.

2. The gasoline of Claim 1 wherein the octane is from about 80 to about 86.

3. The gasoline of Claim 1 wherein the octane is from about 80 to about 83.5.

4. The gasoline of Claim 1 wherein the sulfur content is less than about 10 ppmw.

5. The gasoline of Claim 1 wherein the gasoline contains an oxygenate selected from the group consisting of ethanol, methyl tertiary butyl ether, ethyl tertiary butyl ether, and tertiary amyl ether in an amount sufficient to provide an oxygen content from about 0.5 to about 10 weight percent in the gasoline.

6. The gasoline of Claim 5 wherein the oxygenate is ethanol and the fuel contains about 0.3 to about 5.0 weight percent oxygen.

7. The gasoline of Claims 1 , 3 or 6 wherein the sulfur content is less than about 5 ppmw.

8. An unleaded low emissions gasoline for use in an internal combustion automotive engine having an octane (R+M)/2 of less than an adjusted octane number which upon combustion in the internal combustion automotive engine produces emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to a comparable unleaded minimum 87 octane gasoline for use in an internal combustion automotive engine no greater than with the comparable unleaded gasoline having an octane of at least 87.

9. The unleaded low emissions gasoline of Claim 8 wherein the unleaded low emissions gasoline is in compliance with the ASTM D4814-01a.

10. The unleaded low emissions gasoline of Claim 8 wherein the emissions of total hydrocarbons and carbon monoxide are less than the emissions of total hydrocarbons and carbon monoxide from combustion of the unleaded minimum 87 octane gasoline.

11. The unleaded low emissions gasoline of Claim 8 wherein the octane is from 80 to 83.5.

12. A method for reducing emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides from an internal combustion automotive engine, the method comprising: a) producing an unleaded reduced emissions gasoline having an octane (R+M)/2 from about 80 to 86.7 which upon combustion in the engine produces reduced emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to a comparable unleaded minimum 87 octane gasoline; and b) fueling the engine with the unleaded reduced emissions gasoline.

13. The method of Claim 12 wherein the unleaded reduced emissions gasoline has an octane less than an adjusted octane number.

14. The method of Claim 12 or 13 wherein the unleaded reduced emissions gasoline has a sulfur content of less than about 5 ppmw.

15. The method of Claim 12 wherein the unleaded reduced emissions gasoline has an octane from about 80 to about 83.5.

16. The method of Claim 15 wherein the unleaded reduced emissions gasoline has a sulfur content of less than about 5 ppmw sulfur.

17. The method of Claim 12 wherein the unleaded reduced emissions gasoline contains an oxygenate selected from the group consisting of ethanol, methyl tertiary butyl ether, ethyl tertiary butyl ether and tertiary amyl methyl ether and combinations thereof in a amount from about 0.3 to 5 weight percent oxygenate.

18. The method of Claim 12 wherein a fleet of at least 100 vehicles powered by internal combustion engines are fueled with the unleaded reduced emissions gasoline.

19 The method of Claim 18 further including the step of providing the unleaded reduced emissions gasoline to a network of distribution stations to distribute the unleaded reduced emissions gasoline to consumer vehicles.

20. A method for fueling automotive vehicles with reduced total emissions to the atmosphere the method comprising: a) operating a refinery to produce an unleaded reduced emissions gasoline having an octane (R+M)/2 less than 86.7 which upon combustion in the engine produces reduced emissions of at least one of total hydrocarbons, carbon monoxide and nitrogen oxides by comparison to a comparable unleaded minimum 87 octane gasoline, the unleaded reduced emissions gasoline being produced in the refinery from a reduced quantity of feedstock and with reduced emissions by comparison to a refinery producing the minimum 87 octane leaded gasoline; and, b) fueling automotive vehicles with the unleaded reduced emissions gasoline, the total emissions of at least one of total hydrocarbons, carbon monoxide, carbon dioxide and nitrogen oxides from combustion of the unleaded reduced emissions gasoline in the automotive vehicles and from the refinery producing the unleaded reduced emissions gasoline being less than for a refinery producing the unleaded minimum 87 octane gasoline and the combustion of the unleaded minimum 87 octane gasoline in the automotive vehicles.

21. The method of Claim 20 wherein the unleaded reduced emissions gasoline has an octane less than an adjusted octane number.

22. The method of Claim 20 or 21 wherein the unleaded reduced emissions gasoline has an octane between about 80 and 83.5.

23. The methods of Claims 21 or 22 wherein the unleaded reduced emissions gasoline has less than 40 ppmw sulfur.

24. The methods of Claims 21 or 22 wherein the unleaded reduced emissions gasoline has less than 15 ppmw sulfur.

25. The methods of Claims 21 or 22 wherein the unleaded reduced emissions gasoline has less than 5 ppmw sulfur.

26. The methods of Claims 21 or 22 wherein the unleaded reduced emissions gasoline has less than 15 ppmw sulfur and one or more oxygenates selected from the group consisting of ethanol, methyl tertiary butyl ether, ethyl tertiary butyl ether and tertiary amyl methyl ether in an amount from about 0.1 to about 10 weight percent.

27. The methods of Claims 12 or 20 in which at least two of total hydrocarbons, carbon monoxide and nitrogen oxides are reduced when compared to combustion of a comparable unleaded minimum 87 octane gasoline.