Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/02—Liquid carbonaceous fuels essentially based on components consisting of carbon, hydrogen, and oxygen only
  • C10L1/023—Liquid carbonaceous fuels essentially based on components consisting of carbon, hydrogen, and oxygen only for spark ignition

Definitions

• This invention relates to fuel compositions and in particular to gasoline compositions for use in spark ignition internal combustion engines.
• Such gasoline compositions comprise a mixture of hydrocarbons and other additives.
• the composition is required to vaporise over a range of temperatures to give satisfactory hot and cold starting characteristics and efficient engine operation. To this end the compositions generally have initial and final boiling points within the range 25-35°C and 200-220°C respectively.
• the gasoline composition is often varied with the time of year and/or region to allow for variations in the average ambient temperature-.
• the distillation and vapour pressure characteristics of typical gasolines are as follows.
• compositions generally contain as much butane as is consistent with obtaining satisfactory vapour pressure and boiling range characteristics.
• Spark ignition internal combustion engines such as those used in sutomobiles, generally have, in the interests of efficiency, a relatively high compression ratio.
• a fuel having a high octane rating is required: the Research Octane Number (RON) is normally above 80, more usually above 85, and in most cases above 90: indeed compositions having a RON in the range 95-100 are widely used for premium grade fuels.
• additives are gnerally incorporated into the composition: lead compounds, e.g. lead tetraethyl, are the most widely used octane rating improvers.
• octane improving additives that have been employed include ethers and alcohols such as methyl t-butyl ether (MBE) and t-butanol alone or in admixture with other alcohols such as ethanol.
• MBE methyl t-butyl ether
• t-butanol alone or in admixture with other alcohols such as ethanol.
• the blending RON of these additives varies to some extent on the base gasoline used in the RON determination and on the amount of additive employed: typical blending RON are as follows:
• di-alkyl carbonates can be used to improve the octane rating of gasoline without the aforementioned disadvantages.
• Di-alkyl carbonates have been proposed as gasoline additives in US-A-2331386 which quoted a blending octane number of 96-98 for di-ethyl carbonate (DEC) when used in gasolines of octane number about 74 to 79.
• DEC di-ethyl carbonate
• Our measurements conducted on gasolines having higher RON indicate that DEC has a blending RON of the order of 110-112 and that, surprisingly, di-methyl carbonate (DMC) has a much higher blending RON, of the order of 120-130 or more.
• DMC di- n-propyl carbonate
• DEC di-n-butyl carbonate
• octane improving additives such as alcohols, e.g. methanol, ethanol, t-butanol, and MTBE
• DMC has a number of disadvantages. Inter alia it has a significantly higher specific gravity and a much lower net calorific value (i.e. the heat of combustion excluding the heat liberated by condensation of the water vapour fomed during combustion, since in internal combustion engines this water vapour is not condensed but is emitted with the exhaust gases).
• the present invention provides a gasoline composition having a RON of at least 80 and comprising gasoline hydrocarbons and from 1 to 6% by volume, based on the volume of the composition, of IMC.
• octane improving additives such as alcohols
• water miscible additives presents storage problems, particularly the use of gasoline storage tanks having water providing a base level. Not only may water miscible additives tend to be leached from the gasoline into the aqueous phase upon storage over a water base, but also their presence in the gasoline may increase the solubility of water in the gasoline.
• DMC specific gravity, net calorific value, and water solubility of DMC in relation to other di-alkyl carbonates and other gasoline additives are listed in the following table.
• DMC has an appreciable solubility in water, and this solubility is significantly greater than that of other di-alkyl carbonates, the partition coefficient of DMC between the gasoline and aqueous phases is strongly in favour of dissolution in the gasoline phase.
• the increase in solubility of water in gasoline resulting from incorporation of DMC into gasoline appears to be significantly less than that given by the incorporation of DEC into gasoline.
• DMC can readily be produced from feedstocks other than crude oil and so its use enables a greater amount of fuel to be obtained from a given quantity of crude oil.
• DMC can be made from methanol by reaction with carbon monoxide and oxygen over a suitable catalyst, e.g. copper chloride: for example see Ind. Eng Chem. Prod. Res. Dev. (1980) 19, 396-403. It may also be made by reacting ethylene oxide with carbon dioxide to produce ethylene carbonate which is then reacted with methanol to produce DMC and ethylene glycol: for example see US-A-3642858 and 3803201.
• a suitable catalyst e.g. copper chloride: for example see Ind. Eng Chem. Prod. Res. Dev. (1980) 19, 396-403. It may also be made by reacting ethylene oxide with carbon dioxide to produce ethylene carbonate which is then reacted with methanol to produce DMC and ethylene glycol: for example see US-A-3642858 and 3803201.
• compositions of the present invention may contain other additives e.g. viscosity modifiers, gum suppressants and other octane improvers, e.g. other di-alkyl carbonates, alcohols or ethers, such as t-butanol and MTBE, and lead compounds such as lead tetraalkyls e.g. lead tetraethyl and lead tetramethyl.
• the lead content is preferably not more than 0.4, preferably not more than 0.15, g Pb/litre.
• the gasoline composition is substantially lead free.
• Di-alkyl carbonates that can be used in combination with DMC (boiling point 90°C) are those di-alkyl carbonates of the formula R 1 -0-R 2 in which R and R 2 are alkyl radicals which may be the same or different and in which the total number of carbon atoms in the alkyl groups R 1 and R 2 is from 3 to 8.
• Examples of such di-alkyl carbonates include: Each of the alkyl groups R and R 2 preferably contains less than 5 carbon atoms.
• the total amount of di-alkyl (including di-metbyl) carbonates is preferably below 10% by volume of the gasoline composition, while the amount of IMC employed, whether alone or in admixture with other di-alkyl carbonates and/or other octane improvers is between l and 6% by volume of the gasoline composition.
• the amount of DMC employed is 3 to 5% by volume.
• the use of such amounts of DMC generally increases the RON of unleaded gasoline or leaded gasoline containing up to 0.4 g Pb/1 by about 1-2 units.
• a mixture of DMC and one or more other di-alkyl carbonates may be preferable to DMC alone because the mixture has a higher calorific value, per unit volume, a range of boiling points and vapourisability, and less mutual solubility in water compare with DMC. All these properties are advantageous in gasoline compositions for spark ignition internal combustion engines. However such a mixture will of course have a lower blending RON than DMC alone.
• a mixture of di-alkyl carbonates may conveniently be made, when using a di-alkyl carbonate producing process, such as those mentioned above, wherein the reactant providing the alkyl radicals is an alcohol, by using as the alcohol a mixture of alcohols.
• a mixture of alcohols may be synthesised from a synthesis gas comprising carbon monoxide and hydrogen, by the use of a suitable catalyst. Processes for making such alcohol mixtures are well known in the art.
• the ratio of higher alcohols (mainly C 2 to C 5 ) to methanol and the structure, i.e. branched or straight chain, of the alcohols higher than ethanol produced by these processes will depend on the precise catalyst and synthesis conditions, including the H 2 /CO ratio employed.
• di-alkyl carbonates are by reaction of an alkylene oxirane e.g. ethylene or propylene oxide, with carbon dioxide to produce an alkylene carbonate which is then reacted with an alcohol to give the di-alkyl carbonate and a glycol (for example as described in US-A-3642,858 and 3,803,201).
• alkylene oxirane e.g. ethylene or propylene oxide
• carbon dioxide e.g. ethylene or propylene oxide
• an alcohol for example as described in US-A-3642,858 and 3,803,201.
• Glycols which have a variety of uses, are often made by the hydrolysis of alkylene oxiranes.
• a di-alkyl carbonate can be made from the alcohol in addition to the production of the glycol from the alkylene oxirane.
• One method that is employed for the production of alkylene oxiranes involves the formation of an alkyl hydroperoxide by the reaction of an alkane with oxygen, i.e. followed by the reaction of the alkyl hydroperoxide with an alkene, e.g. propylene, e.g. (see for example UK-A-1,060,122 and 1,074,330).
• an alkene e.g. propylene, e.g.
• the alkyl group R should be a tertiary alkyl group so that the hydroperoxide has sufficient stability for use in the reaction with the alkene.
• a by-product of this reaction is thus the alcohol ROH corresponding to the alkyl hydroperoxide ROOH.
• the nature of the by-product alcohol ROE will of course depend on the alkane feedstock employed to make the hydroperoxide ROOH. Depending on the alkyl group R the by-product alcohol ROH can be put to a variety of uses including one or more of:
• the alcohol ROH can be used as part or all of the alcohol reacted with an alkene to give an ether, e.g. as described in iv) above.
• Some or all of the alkene may be derived from part of the alcohol ROH by dehydration as in iv) above while the remainder of the alcohol ROH is reacted, if desired in admixture with an alcohol, e.g. methanol, obtained from another source, with the alkene to give an ether, or ether mixture, suitable for use as gasoline additives.
• an alcohol mixture produced from a mixture of hydroperoxides can be separated into “high” and “low” fractions: the "high” fraction can be dehydrated to the corresponding alkene or alkenes while the "low” fraction reacted with the alkene or alkene mixture obtained from the "high” fraction to give the ether or ether mixture.
• a further aspect of the invention provides a process for the manufacture of i) a di-alkyl carbonate product consisting of at least one di-alkyl carbonate, ii) an alcohol product A consisting of at least one alcohol and/or an ether product consisting of at least one ether, and iii) a glycol product consisting of at least one glycol, comprising
• the above process can thus upgrade an alkane feedstock into an alcohol product useful as a gasoline additive as such or as a reactant for the production of a gasoline additive, and an alkene feedstock into a glycol product and also upgrade said alcohol product or a different alcohol component into a di-alkyl carbonate product which is useful as a gasoline additive.
• a further aspect of the invention provides, in a process wherein an alkane feedstock and an alkene feedstock are upgraded to form an alcohol product and a glycol product by:
• isobutane is used as the alkane feedstock and the resulting hydroperoxide is reacted with propylene to give propylene oxide and t-butanol.
• the propylene oxide is converted to propylene carbonate which is reacted with methanol to produce propylene glycol and DMC.
• ethylene is used in place of propylene thus giving ethylene glycol and DMC.
• the t-butanol is preferably used as such, in admixture with the DMC, as a fuel additive, or some or all of the t-butanol is dehydrated to isobutene which is etherified with methanol to give MTBE which is used in admixture with the DMC and the remainder, if any, of the t-butanol as a gasoline additive.
• Example 1 was repeated using blends of 3 and 5% v/v of various di-alkyl carbonates in a gasoline composition comprising 80% v/v iso-octane and 20% v/v n-hep.tane. Motor Octane Numbers (MON) were also determined by the Standard Method (ASTM D2700). The results were as follows:
• Example 2 was repeated using leaded premium grade gasolines in place of the iso-octane/n-heptane mixtures.
• the gasolines which differed for each di-alkyl carbonate, each contained 0.4 g Pb/l.
• the distribution of DMC between gasoline and water was determined by shaking together at ambient temperature equal volumes of water on a commercial premium grade gasoline containing 0.4 g Pb/l to which various amounts of DMC had been added. When equilibrium had been reached, samples of each phase were analysed for DMC. The results are given in the following table.
• K for t-butanol (at a level of 3% v/v t-butanol in gasoline) is about 0.26 while that for methanol is very small.

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Liquid Carbonaceous Fuels (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (6)

Publications (2)

Family

ID=27261631

Family Applications (1)

Country Status (4)

Cited By (4)

Family Cites Families (3)

• 1983
  • 1983-06-07 EP EP83303288A patent/EP0098691A3/de not_active Withdrawn
  • 1983-06-07 GB GB838315608A patent/GB8315608D0/en active Pending
  • 1983-06-15 NZ NZ20459083A patent/NZ204590A/en unknown
  • 1983-06-17 AU AU15896/83A patent/AU1589683A/en not_active Abandoned

Also Published As

Similar Documents

Legal Events