Fuel and related compositions – Liquid fuels – Organic oxygen compound containing
Reexamination Certificate
2002-09-09
2004-07-13
Toomer, Cephia D. (Department: 1714)
Fuel and related compositions
Liquid fuels
Organic oxygen compound containing
C044S350000, C044S388000, C044S448000, C044S437000, C044S438000, C044S439000, C044S349000
Reexamination Certificate
active
06761745
ABSTRACT:
BACKGROUND OF THE INVENTION
This application is a continuation-in-part of application Ser. No. 09/612,572, filed on Jul. 7, 2000 now abandoned, and a continuation-in-part of application Ser. No. 09/767,940, filed on Jan. 24, 2001 now abandoned, the disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
This invention relates to unleaded motor fuel for spark ignition internal combustion engines. More particularly the invention relates to a method for lowering the dry vapor pressure equivalent (DVPE) of a fuel composition including a hydrocarbon liquid and ethanol by using an oxygen-containing compounds and C
6
-C
12
hydrocarbons. The ethanol and DVPE adjusting components used to obtain the fuel composition are preferably derived from renewable raw materials. By means of the method of the invention motor fuels containing up to 20% by volume of ethanol meeting standard requirements for spark ignition internal combustion engines operating with gasoline are obtainable.
Conventional gasoline (“gasoline”) is the major fuel for spark ignition internal combustion engines. As employed herein, the phrase conventional gasoline includes a volatile, highly inflammable, generally colorless, liquid obtained by fractional distillation of petroleum. The extensive use of gasoline results in the pollution of the environment. The combustion of gasoline derived from crude oil or mineral gas disturbs the carbon dioxide balance in the atmosphere, and causes the greenhouse effect. Crude oil reserves are decreasing steadily with some countries already facing crude oil shortages.
The growing concern for the protection of the environment, tighter requirements governing the content of harmful components in exhaust emissions, and crude oil shortages, force industry to develop urgently alternative fuels which burn more cleanly.
The existing global inventory of vehicles and machinery operating with spark ignition internal combustion engines does not allow currently the complete elimination of gasoline as a motor fuel.
The task of creating alternative fuels for internal combustion engines has existed for a long time and a large number of attempts have been made to use renewable resources for yielding motor fuel components.
U.S. Pat. No. 2,365,009, issued in 1944 describes the combination of C
1
-C
5
alcohols and C
3
-C
5
hydrocarbons for use as a fuel. In U.S. Pat. No. 4,818,250 issued in 1989 it is proposed to use limonene obtained from citrus and other plants as a motor fuel, or as a component in blends with gasoline. In U.S. Pat. No. 5,607,486 issued in 1997, there are disclosed novel engine fuel additives comprising terpenes, aliphatic hydrocarbons and lower alcohols.
Currently tert-butyl ethers are widely used as components of gasolines. Motor fuels comprising tert-butyl ethers are described in U.S. Pat. No. 4,468,233 issued in 1984. The major portion of these ethers is obtained from petroleum refining, but can equally be produced from renewable resources.
Ethanol is a most promising product for use as a motor fuel component in mixtures with gasoline. Ethanol is obtained from the processing of renewable raw material, known generically as biomass, which, in turn, is derived from carbon dioxide under the influence of solar energy.
The combustion of ethanol produces significantly less harmful substances in comparison to the combustion of gasoline. However, the use of a motor fuel principally containing ethanol requires specially designed engines. At the same time spark ignition internal combustion engines normally operating on gasoline can be operated with a motor fuel comprising a mixture of gasoline and not more than about 10% by volume of ethanol. Such a mixture of gasoline and ethanol is presently sold in the United States as gasohol. Current European regulations concerning gasolines allow the addition to gasoline of up to 5% by volume of ethanol.
The major disadvantage of mixtures of ethanol and conventional gasoline is that for mixtures containing up to about 20% by volume of ethanol there is an increase in the dry vapor pressure equivalent as compared to that of the conventional gasoline.
FIG. 1
shows the behavior of the dry vapor pressure equivalent (DVPE) as a function of the ethanol content of mixtures of ethanol and gasoline A92 summer, and gasoline A95 summer and winter at 37.8° C. The gasolines known as A92 and A95 are standard, conventional gasolines purchased at gas stations in the United States and Sweden. Gasoline A92 originated in the United States and gasoline A95, in Sweden. The ethanol employed was fuel grade ethanol produced by Williams, USA. The DVPE of the mixtures was determined according to the standard ASTM D-5191 method at the SGS laboratory in Stockholm, Sweden.
For the range of concentrations by volume of ethanol between 5 and 10% which is of particular interest for use as a motor fuel for standard spark ignition engines, the data in
FIG. 1
show that the DVPE of mixtures of gasoline and ethanol can exceed the DVPE of source gasoline by more than 10%. Since the commercial petroleum companies normally supply the market with gasoline already at the maximum allowed DVPE, which is strictly limited by current regulations, the addition of ethanol to such presently commercially available gasolines is not possible.
It is known that the DVPE of mixtures of gasoline and ethanol can be adjusted. U.S. Pat. No. 5,015,356 granted on May 14, 1991 proposes reformulating gasoline by removing both the volatile and non-volatile components from C
4
-C
12
gasoline to yield either C
6
-C
9
or C
6
-C
10
intermediate gasoline. Such fuels are said to better facilitate the addition of alcohol over current gasoline because of their lower dry vapor pressure equivalent (DVPE). A disadvantage of this method of adjusting the DVPE of mixtures of gasoline and ethanol is that in order to obtain such a mixture it is necessary to produce a special reformulated gasoline, which adversely affects the supply chain and results in increased prices for the motor fuel. Also, such gasolines and their mixtures with ethanol have a higher flash point, which impairs their performance properties.
It is known that some chemical components decrease DVPE when added to gasoline or to a mixture thereof with ethanol. For example, U.S. Pat. No. 5,433,756 granted on Jul. 18, 1995 discloses chemical clean-combustion-promoter compounds comprising, in addition to gasoline, ketones, nitro-paraffin and also alcohols other than ethanol. It is noted that the composition of the catalytic clean-combustion-promoter disclosed in the patent reduces the DVPE of gasoline fuel. Nothing is mentioned in this patent about the impact of the clean-combustion-promoter composition on the DVPE of mixtures of gasoline and ethanol.
U.S. Pat. No. 5,688,295 granted on Nov. 18, 1997 provides a chemical compound as an additive to gasoline or as a fuel for standard gasoline engines. In accordance with the invention, an alcohol-based fuel additive is proposed. The fuel additive comprises from 20-70% alcohol, from 2.5-20% ketone and ether, from 0.03-20% aliphatic and silicon compounds, from 5-20% toluene and from 4-45% mineral spirits. The alcohol is methanol or ethanol. It is noted in the patent that the additive improves gasoline quality and specifically decreases DVPE. The disadvantages of this method of motor fuel DVPE adjustment are that there is a need for large quantities of the additive, namely, not less than 15% by volume of the mixture; and the use of silicon compounds, which form silicon oxide upon combustion, results in increased engine wear.
In WO9743356 a method for lowering the vapor pressure of a hydrocarbon-alcohol blend by adding a co-solvent for the hydrocarbon and alcohol to the blend, is described. A spark ignition motor fuel composition is also disclosed, including a hydrocarbon component of C
5
-C
8
straight-chained or branched alkanes, essentially free of olefins, aromatics, benzene and sulphur, in which the hydrocarbon component has a minimum anti-knock index of 65, according to ASTM D-2699 and D-2700 and
Golubkov Igor
Hull Angelica
Fitzpatrick ,Cella, Harper & Scinto
Toomer Cephia D.
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