Fuel and related compositions – Liquid fuels – Organic oxygen compound containing
Patent
1996-02-20
1997-05-13
Howard, Jacqueline V.
Fuel and related compositions
Liquid fuels
Organic oxygen compound containing
44451, C10L 118
Patent
active
056288050
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an aqueous ethanol fuel which contains an adduct of a polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide as an ignition improver.
Because of the high ignition temperature of ethanol, it is not possible to use pure ethanol as fuel in a conventional diesel engine. One way of igniting the ethanol fuel is to provide the diesel engine with spark plugs, but this necessitates extensive modifications to the engine construction. For conventional diesel engines, a so-called ignition improver, i.e. an agent which serves to lower the ignition temperature of the fuel, has been added to the ethanol. The predominant ignition improvers are alkyl nitrates, and the most used substance is 2-ethylhexyl nitrate, generally abbreviated EHN.
EHN, which has a rather strong and disagreeable odour, is toxic and can be hydrolysed to nitric acid and 2-ethylhexanol when stored for longer periods of time, especially at elevated temperature. The hydrolysis causes a marked lowering of the pH, implying a serious risk of corrosion. A further serious objection to EHN is that the substance contains nitrogen which may increase the emission of nitrogen oxides with the exhaust gases.
European Patent Application 403 516 discloses that the mentioned disadvantages of using EHN as an ignition improver can be eliminated if it is replaced by a water-soluble polyalkylene glycol compound containing 6-50 alkylene oxide units having 2-4 carbon atoms under the proviso that the molecular weight of the polyalkylene glycol compound is less than 2500.
European patent application 030 429 relates to fuel comprising a mixture of at least one alcohol having a molecular weight of less than 160 and at least one further organic compound, which can be a compound containing one or more oxygen atoms but no nitrogen atoms. In the working examples acetaldehyde is the only nitrogen-free ignition improving agent used in an ethanol fuel.
It is also known to add corrosion inhibitors and lubricants to fuel. German Patent Application A1, 3 628 504 describes a fuel mixture of hydrocarbons, an alcohol and a corrosion inhibitor in an amount of up to 5000 ppm. This inhibitor contains a surface active agent, i.e. block polymers of alkylene oxides.
British Patent Application A 2 143 846 discloses the use of 0.005-0.05% by weight of a polyalkylene glycol as a lubricity improver in a diesel fuel based on methanol and/or ethanol.
British Patent Application A 1 591 398 describes a methanol fuel containing at least 50% by weight of methanol and as an ignition improver a methanol-soluble polyether containing 4-400 oxyalkylene units derived from ethylene oxide and/or propylene oxide units, the oxyalkylene units being at least 40% by weight of the polyether.
It has now surprisingly been found that the ignition of an aqueous ethanol based fuel can be essentially improved if an water soluble adduct of a polyol, with 3-10, preferably 3-6 hydroxyl groups and ethylene oxide and/or propylene oxide with a molecular weight of from 350 to 10 000, preferably from 450 to 5 000, is used as an ignition improver. The adduct has at least 3 hydroxyl groups and tests have shown that its presence in an ethanol fuel essentially shortens the delay of ignition in comparison with the polyalkylene glycol compounds of European Patent Application 403 516, which contain 1 or 2 hydroxyl groups. Since the adduct containing only carbon, hydrogen and oxygen its combustion contributes no additional hazard to the environment.
An aqueous ethanol fuel according to the invention has the form of a solution and contains 70-96%, preferably 80-95% by weight of ethanol, 2-10%, preferably 3-6% by weight of water and 0.5-20%, preferably 2-10% by weight of the water-soluble adduct.
Preferred adducts are those which are encompassed by the formula from the group consisting of the ether, aldehyde and keto group and having 3-22, preferably 3-12 carbon atoms, A is ethyleneoxy and/or propyleneoxy, n is a number from 2-20, preferably from 3-10 and m is a number from 3 to 10, prefera
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patent: 4333739 (1982-06-01), Neves
patent: 4541835 (1985-09-01), Norton et al.
patent: 4541837 (1985-09-01), Norton et al.
patent: 5183476 (1993-02-01), Carlsson et al.
Lif Anna
Svennberg Stig
Akzo Nobel nv
Howard Jacqueline V.
Mancini Ralph J.
Morris Louis A.
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