1. Field of the Invention
This invention relates to novel fuel compositions for use in spark ignited internal combustion engines. More particularly, this invention relates to gasoline-ethanol fuel mixtures having rust inhibiting and/or preventing properties. The invention also is concerned with a process for conferring anti-corrosion properties to ethanol in gasoline fuel mixtures.
2. Description of the Prior Art
Worldwide concern over the growing shortages of crude oil supplies has promoted the use of many materials as blending agents in gasoline to extend the fuel supply. From the engine or motor vehicle manufacturers' point of view, it seems easiest to employ alcohol blended with gasoline. Methanol, ethanol and t-butyl alcohol have emerged as the most widely used alcohol blending agents. Recently, a high level of interest has been shown in the use of "Gasohol," defined herein as a blend of gasoline with from about 5 volume percent to about 30 volume percent ethanol, as an automotive fuel. Interest has been especially high in countries such as Brazil which have an intense cultivation of sugar cane, mandioca and other raw materials of vegetable origin adequate for the production of ethanol.
The use of a polar oxygenate such as ethanol in gasoline blends, however, has far reaching consequences. One of these is the creation of corrosion problems both in the logistic chain and in the vehicle itself. In pipelines and storage tanks rust, which normally would remain on the walls, is loosened by the alcohol and transported through the system. Of perhaps greater concern with the use of commercial ethanol in gasoline blends are phase separation problems which occur because water containing ethanol has limited solubility in gasoline. When phase separation occurs, corrosion of many of the metals and alloys which make up the vehicle fuel distribution system and the vehicle engine is promoted due to water contacting the metals and metal alloys. Specifically, fuel tank terne plate (steel coated with an alloy of lead 80-90% and tin 10-20%), zinc and aluminum diecast carburetor and fuel pump parts, brass fittings, steel lines, etc. can corrode when exposed to gasoline-ethanol fuel mixtures. This problem can be remedied to some extent by the use of anhydrous or substantially anhydrous ethanol as a blending agent. However, if the fuel mixture is stored for too long a period of time before use, the anhydrous ethanol will pick up water from the environment and become hydrous or ("wet") ethanol and phase separation will occur. Even in the absence of phase separation, corrosion can be brought about by the presence of trace amounts of acetic acid, acetaldehyde, acetate and n-butanol in the ethanol-gasoline blends which are formed during the production of the ethanol. Other corrosion problems can arise from dissolved mineral salts, such as highly corrosive sodium chloride, which may be picked up by the fuel during production, storage and transportation.
Thus, there is presently a need for a corrosion inhibitor that will either curb or prevent the corrosion of conventional systems which are used to store and transport commercial ethanol in gasoline fuel blends and one that will curb or prevent corrosion of the vehicle fuel systems in which these fuels are ultimately used. Further, it is important that the corrosion inhibitor be effective in very small quantities to avoid any adverse effects, such as adding to the gum component of the fuel, etc., as well as to minimize cost. The corrosion inhibitors of the present invention satisfy these needs.
U.S. Pat. No. 2,334,158 discloses an anti-corrosive composition of matter comprising predominately non-gaseous hydrocarbons containing small amounts each of a polycarboxylic acid having at least 16 carbon atoms and a mutual solvent for hydrocarbons and water such as di-ethylene glycol mono alkyl ether or an ethylene glycol mono alkyl ether.
U.S. Pat. No. 2,962,443 discloses steam turbine lubricants containing the reaction product of:
(a) an aliphatic hydrocarbon-substituted succinic acid having the structure ##STR1## in which R is an aliphatic hydrocarbon radical having at least 10 carbon atoms, with PA1 (b) from about 1 to about 75 percent on a molar basis of an alkylene oxide. PA1 (A) an alkenyl succinic acid, PA1 (B) an alkenyl succinic anhydride, and PA1 (C) an alkenyl succinic ester in which the alkoxy group contains from 1 to 6 carbon atoms, wherein the alkenyl groups (A), (B), and (C) contain from 50 to 250 carbon atoms.
Reportedly, the addition of such a product to a steam turbine lubricant comprising a major amount of a mineral oil renders the lubricant resistant to rust and to the formation of stable emulsions.
U.S. Pat. No. 2,993,772 discloses a process for preventing, inhibiting and modifying the formation of deposits in internal combustion and jet engines employing a substantially hydrocarbon fuel which comprises burning in such engines a fuel consisting of a liquid hydrocarbon having a boiling point up to about 500.degree. F. and a minor amount, in the range of approximately 0.001 to 2% by weight of the fuel, sufficient to prevent, inhibit and modify such deposits, of a member selected from the group consisting of an oil soluble alkenyl succinic acid and the anhydride thereof, having 8 to 31 carbon atoms on the alkenyl group.
U.S. Pat. No. 2,993,773 discloses a process for preventing, inhibiting and modifying the formation of deposits in internal combustion and jet engines employing a substantially hydrocarbon fuel which comprises burning in such engines a fuel consisting of a liquid hydrocarbon having a boiling point up to about 500.degree. F. and a minor amount, in the range of approximately 0.001 to 2.0 weight percent of said fuel sufficient to prevent, inhibit and modify such deposits, of an ester of (1) a member selected from the group consisting of an alkenyl succinic acid and the anhydride thereof, having 8 to 31 carbon atoms on the alkenyl group and (2) an alcohol, said ester being soluble in said liquid hydrocarbon and being composed of only carbon, hydrogen and oxygen.
U.S. Pat. No. 3,117,091 discloses as rust preventative compounds for a petroleum based carrier such as motor gasoline, aviation gasoline, jet fuel, turbine oils and the like, the partial esters of an alkyl or alkenyl succinic anhydride produced by the reaction of one molar equivalent of a polyhydric alcohol with two molar equivalents of the anhydride.
U.S. Pat. No. 3,287,268 discloses the addition to sulfurized and/or chlorinated cutting oils an alkenyl succinic acid ester derivative to reduce the tendency of the oil to produce foam and to lessen the stability of the foam that is produced. The alkenyl succinic acid ester derivative employed comprises a mixture of an alkenyl succinic acid and an ester formed from that acid, or from a related alkenyl succinic acid containing about 8 to 30 carbon atoms in the alkenyl group, and a glycol of 2 to 4 carbon atoms.
U.S. Pat. No. 3,346,354 discloses a hydrocarbon fuel composition capable of reducing intake valve and port deposits which comprises a major proportion of a distillate hydrocarbon mixture boiling substantially in the range of from 100.degree. F. to 750.degree. F. and from 50 to 1000 ppm of a succinic acid derivative selected from the group consisting of
U.S. Pat. No. 3,574,574 discloses a motor fuel composition which promotes reduced intake valve and port deposits containing from 0.005 to 0.1 volume percent of a polyester of a polymerized carboxylic acid.
U.S. Pat. No. 3,632,510 discloses lubricating and fuel compositions comprising a major amount of a lubricating oil and a minor proportion of an ester derivative of a hydrocarbon-substituted succinic acid wherein the hydrocarbon substituent contains at least about fifty aliphatic carbon atoms, the substituent being further characterized by having no more than about 5% olefinic linkages therein based on the total number of carbon-to-carbon covalent linkages in the substituent. The esters include the acidic esters, diesters, mixed ester-metal salts, and mixtures of these wherein the ester moiety is derived from monohydric and polyhydric alcohols, phenols, naphthols, and the like.
U.S. Pat. No. 3,687,644 discloses a gasoline composition containing as anti-icing additives 0.00001% to 0.02% by weight of a mono- or polycarboxylic acid, or an anhydride, ester, amide, imide thereof; and 0.01% to 5% by weight of an alcohol, glycol or polyol. Optionally, an ester of an alkoxylated phenol-aldehyde resin is also present.
U.S. Pat. No. 4,148,605 discloses novel dicarboxylic ester-acids resulting from the condensation of an alkenylsuccinic anhydride with an aliphatic hydroxy acid having from 2 to about 18 carbon atoms and amine salts of said ester-acid as rust or corrosion inhibitors in organic compositions.
U.S. Pat. No. 4,175,927 discloses exhaust hydrocarbon emissions of an internal combustion engine being operating on gasoline containing a cyclopentadienyl manganese antiknock are reduced by the addition of a dimer or a trimer acid or mixture of a dimer and a trimer acid produced by the polymerization or condensation of an unsaturated aliphatic monocarboxylic acid having between 16 and 18 carbon atoms per molecule to the gasoline.
U.S. Pat. No. 4,177,768 discloses an anti-wear compression ignition fuel for use in diesel engines comprising (1) a monohydroxy alkanol having from 1 to 5 carbon atoms, (2) an ignition accelerator and (3) a wear inhibiting amount of a dimerized unsaturated fatty acid and an ester of a phosphorus acid.
U.S. Pat. No. 4,185,594 discloses an anti-wear compression ignition fuel for use in diesel engines comprising (1) a monohydroxy alkanol having from 1 to 5 carbon atoms, (2) an ignition accelerator and (3) a wear inhibiting amount of a dimerized unsaturated fatty acid.
U.S. Pat. No. 4,207,076 discloses crude ethyl-t-butyl ether used as a cosolvent for hydrous ethanol in gasoline fuel mixtures. The ether solubilizes grain alcohol in all proportions in low aromatic content gasolines.
U.S. Pat. No. 4,207,077 discloses pure methyl-t-butyl ether used as a cosolvent for hydrous ethanol in gasoline fuel mixtures. The ether solubilizes grain alcohol in all proportions in low aromatic content gasolines.
U.S. Pat. No. 4,214,876 discloses improved corrosion inhibitor compositions for hydrocarbon fuels consisting of mixtures of (a) about 75 to 95 weight percent of a polymerized unsaturated aliphatic monocarboxylic acid having about 16 to 18 carbons, and (b) about 5 to 25 weight percent of a monoalkenyl-succinic acid wherein the alkenyl group has 8 to 18 carbons. Also described are concentrates of the above compositions in hydrocarbon solvents, as well as fuels containing the compositions.
U.S. Pat. No. 4,227,889 discloses an anti-wear compression ignition fuel composition for use in diesel engines comprising (1) from about 70 percent by weight to about 98.45 percent by weight of a monohydroxy alkanol having from 1-5 carbon atoms, (2) from about 1 percent by weight to about 25 percent by weight of a fuel oil boiling above the gasoline boiling range, and (3) a wear inhibiting amount of a dimerized unsaturated fatty acid. Optionally, said fuel composition may also contain an ignition accelerator such as an organic nitrate.
U.S. Pat. No. 4,242,099 discloses an anti-wear compression ignition fuel for use in diesel engines comprising (1) a monohydroxy alkanol having from 1 to 5 carbon atoms, and (2) a wear inhibiting amount of a C.sub.12 to C.sub.30 hydrocarbyl succinic acid or anhydride, e.g. tetrapropenyl succinic acid. Optionally, said fuel composition may also contain an ignition accelerator such as an organic nitrate.
U.S. Pat. No. 4,248,182 discloses an anti-wear compression ignition fuel for use in diesel engines comprising (1) a monohydroxy alkanol having from 1 to 5 carbon atoms, and (2) a wear inhibiting amount of a C.sub.8 to C.sub.20 aliphatic monocarboxylic acid. Optionally, said fuel composition may also contain an ignition accelerator such as an organic nitrate.