Fuel and related compositions – Liquid fuels – Containing -x-n
Reexamination Certificate
1994-01-31
2001-08-28
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing -x-n
C536S115000, C536S017700
Reexamination Certificate
active
06280487
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel ignition promoter and to a process for preparing the ignition promoter. More particularly, the invention is directed to a process of preparing ignition promoters by combining at least one sugar with polar solvents in the presence of acid catalysts to produce stable solutions, reacting these solutions with an oxirane and thereafter reacting the product obtained with nitric acid under nitrating conditions.
BACKGROUND OF THE INVENTION
There is much interest in developing alternate fuels for internal combustion engines and the like. There is particular interest in ignition promoters for compression-ignition engines, for example, diesel engines, due to the high cost and uncertain availability of petroleum based fuels and environmental concerns. Among potential fuels that have received considerable attention, especially for diesel engines, are the lower alcohols, such as methanol, ethanol, etc. Methanol is of particular interest since it can easily be obtained from natural gas as well as form the large coal reserves available in many Western countries. Unfortunately, methanol or ethanol alone have poor compression-ignition characteristics making them unsuitable for use in conventional diesel engines. It is known however that ignition promoters can be added to lower alcohols to make them suitable for use in diesel engines.
U.S. Pat. No. 5,096,462, which is hereby incorporated by reference, discloses that effective ignition promoters suitable for incorporation into alcohols produce excellent fuels for use in internal combustion engines. The ignition promoters are obtained by removing cellulose from biomass, using any suitable procedure therefor, reacting the remainder of said biomass with an oxirane and thereafter reacting the resulting reaction product with nitric acid under nitrating conditions.
We have now discovered an exceeding simple process for producing an ignition promoter that can be introduced into an alcohol to obtain a fuel suitable for use in internal combustion engines, in particular compression-ignition engines, that involves combining a sugar with a selected solvent, reacting the resulting solution with an oxirane and thereafter reacting the product obtained with nitric acid under nitrating conditions.
SUMMARY OF THE INVENTION
The present invention is directed to a process for preparing an ignition promoter by reacting a sugar in a suitable solvent with an oxirane, recovering the resulting product and nitrating the product. The nitrated product is particularly suitable as an ignition promoter in lower alcohol fuels.
Accordingly, a primary aspect of the invention is to provide an efficient process for producing an ignition promoter and fuels containing the ignition promoters. The ignition promoter produced by the process is particularly desirable as an ignition promoter in lower alcohol fuels to make the fuels suitable for use in compression-ignition engines.
The ignition promoter is prepared by initially dispersing a sugar in a polar solvent with an acid catalyst and heating the dispersion under elevated pressure in an autoclave. In preferred embodiments, the sugar is a disaccharide, such as sucrose, which when heated under elevated pressure in the presence of an acid in methanol, reacts and forms a solution.
These and other aspects of the invention are basically attained by providing a process for preparing an ignition promoter comprising dispersing a sugar and an acid catalyst in a polar solvent to form a dispersion; heating the dispersion at a sufficient temperature to form a first reaction product in the form of a solution; reacting the first reaction product with an oxirane to form a second reaction product; recovering the second reaction product of the first reaction product and oxirane; nitrating the recovered second reaction product with nitric acid to produce a nitro-ester compound; and recovering the nitro-ester compound.
Further aspects of the invention are provided by producing a fuel comprising at least one C
1
-C
6
alkyl alcohol; and an ignition promoter prepared by the process of dispersing a sugar and an acid catalyst in a polar solvent to form a dispersion; heating the dispersion at a sufficient temperature to form a first reaction product; reacting the first reaction product solution with an oxirane to form a second reaction product; recovering the second reaction product of the first reaction product and oxirane; nitrating the recovered second reaction product with nitric acid to produce a nitro-ester compound; and recovering the nitro-ester compound.
DETAILED DESCRIPTION OF THE INVENTION
The invention is directed to an ignition promoter and, more particularly, to a process of preparing the ignition promoter. The process essentially comprises dissolving or dispersing a sugar in a polar solvent with an acid catalyst and heating the dispersion. In preferred embodiments, the dispersion is heated in an autoclave under elevated pressure to produce a first reaction product in the form of a solution. This first reaction product is then reacted with an oxirane under conditions to produce a second reaction product which is then nitrated with nitric acid under nitrating conditions to form a nitro-ester.
The starting materials used to prepare the novel ignition promoter composition are sugars. The term “sugars ” as used herein include (1) water-soluble organic compounds containing a carbonyl group and several alcohol functionalities, usually from four to five alcohol functionalities, and (2) water-soluble hydrolysates of dimers, oligomers and polymers containing at least two units of the water-soluble organic compounds, for example, from two to about 14,000 units, generally from two to about 200 units. Suitable examples of water soluble organic compounds (1) include the monosaccharides such as glucose, d-mannose, d-galactose, fructose, arabinose, xylose and ribose. Suitable examples of water soluble hydrolysates (2) include disaccharides such as, for example, sucrose, galactose, and maltose, and hemicellulose and higher molecular weight polysaccharides.
The reaction is carried out using at least one sugar or in the presence of an acid catalyst. In a preferred embodiment, the selected sugar is commercially available sucrose sold as table sugar such as Domino brand (TM) sugar.
The sugar dispersion containing the acid catalyst in the solvent may be allowed to stand at room temperature. In preferred embodiments, the dispersion is heated for sufficient time to form a clear solution or liquid. The sugar can be heated at room temperature for about one minute to 24 hours at about 50-200° C. and preferably at about 50° C. to 150° C. In embodiments of the invention, the sugar dispersion is heated to 35° C. to 100° C. for about one to five hours.
In the first step of the novel process herein, one or more sugars as defined above are combined with a selected solvent in the presence of an acid catalyst. The solvents are polar solvents. Suitable solvents include water, lower alcohols including, for example, methanol, ethanol, and isopropanol, lower ketones such as acetone and methyl ethyl ketone, and mixtures thereof. The preferred solvents are methanol, acetone and mixtures thereof. The weight ratio of sugar to solvent can be, for example, in the range of 20:1 to 1:20, more preferably, 10:1 to 1:10, and most preferably, from 5:1 to 1:5.
In a preferred embodiment, the solvent is methanol substantially in the absence of water. The sugar is mixed with the methanol in an amount to form a dispersion. The dispersion is heated at elevated pressures in the presence of an acid catalyst to form a first reaction product in the form of a clear liquid.
The process of heating the sugar solution or dispersion in the presence of the acid is preferably at an elevated pressure. The heating step is preferably carried out in an autoclave at a pressure of about 50 to 100 psig and more preferably at about 75 psig. When the sugar is a disaccharide and the solvent is an alcohol, the reaction takes several hours to reach completion at atmos
Porowski Engelina
Schulz Johann G.
JGS Research Company, Inc.
Medley Margaret
Roylance Abrams Berdo & Goodman L.L.P.
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