GB2359094A

GB2359094A - Anti-foam fuel composition

Info

Publication number: GB2359094A
Application number: GB0003386A
Authority: GB
Inventors: Stuart Pace; Alan Mark Schilowitz
Original assignee: ExxonMobil Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 2000-02-14
Filing date: 2000-02-14
Publication date: 2001-08-15
Also published as: GB0003386D0; WO2001060955A1; DE60120146T2; JP2003523453A; DE60120146D1; EP1274818B1; JP5102421B2; EP1274818A1; ATE328052T1; CA2397456A1

Abstract

This invention relates to a fuel composition comprising a base fuel having a final boiling point above 150{C and an anti-foam, characterised in that the anti-foam comprises di-isobutylene in an amount greater than 2.5 % by volume based on the total fuel composition. The addition of this anti-foam reduces the break-up time for any foam formed significantly.

Description

FUEL COMPOSITION This invention relates to fuel compositions comprising an anti-foam additive to reduce the time needed to break up any foam formation during the filling of a vehicle's fuel tank thereby enabling a more complete filling of the tank and at the same time reducing risk of spillage.

The problem of foaming of fuels due to entrainment of air during filling of fuel tanks of vehicles is well known. The problem has hitherto been mitigated by adding to the fuel antifoams which are substantially non-hydrocarbonaceous. An example of such a non-hydrocarbonaceous additive is a silicon containing polymer. Non- hydrocarbonaceous additives usually have to undergo a rigorous testing programme with respect to their compatibility with the fuel and also environmental considerations. However, if the additive is a hydrocarbon, especially a non-aromatic hydrocarbon, the issues of compatibility and environmental considerations are not as critical. JP-A- 08073870 discloses gasoline compositions for two-cycle engines which contain at least 10 vol % 7-8C olefinic hydrocarbons and have a T50 of 93-105 C, a final distillation temperature of 110-150 C and an octane No. by the motor method of at least 95. Amongst the 11 olefins listed is mentioned 2,4,4-trimethyl-l-pentene. However, it is not clear whether these olefins are used as a blend of several. In any event, the olefins are not used as anti-foaming agents but to achieve high output and low fuel consumption and to avoid seizure even at high compression ratios. Moreover, gasoline used in two-cycle engines (ie two-stroke engines) inevitably have lubricating oils admixed therewith and hence are not as susceptible to foaming as gasolines free of such lubricating oils.

Similarly, SAE Paper 950740 describes various compounds being added to a mixture of toluene (boiling point about 110 C) and isooctane (boiling point 99 C) to monitor the emissions of vehicles powered therewith. One such compound added is di- isobutylene in an amount > 15% by volume. The resultant mixture is unlikely to have a final boiling point above 150 C and there is no mention of the use of di-isobutylene as an anti-foam in this document.

Similarly, JP-A-06200263 describes a composition which contains at least 65% by volume based on the total base fuel of a high boiling component with a boiling point

TABLE 1 Blend Fuel DIB DIB Foam Vol (ml) Mean Break-up Time Mean (ml) (ml) (%) Value (seconds) Value 1 300 0 0 126 124 125 79.2 82.5 80.9 2 292.5 7.5 2.5 130 128 129 79.7 81 80.4 3 285 15 5 130 132 131 62.3 66.9 64.6 4 270 30 10 142 140 141 51.9 49.6 50.8 DIB - Di-isobutylene (a mixture of 3 parts 2,4,4-trimethylpent-1-ene and 1 part 2,4,4 trimethylpent-2-ene) It is generally prepared from a. crude mixture of olefins and usually comprises a mixture of various C8-olefin isomers but always comprises 2,4,4-trimethylpent-l-ene admixed with 2,4,4-trimethylpente-2-ene. These two isomers are suitably present in the di- isobutylene in a weight ratio of about 75% (-1-ene) to about 25% (-2-ene).

Di-isobutylene has an advantage over other non-hydrocarbonaceous anti-foams such as silicon based polymers in that di-isobutylene is substantially miscible with conventional fuels in a11 proportions. Di-isobutylene has the further advantage that current plants making methyl tert-butyl ether (hereafter "MTBE") from isobutylene and methanol (MTBE having more recently fallen out of favour upon environmental considerations), can be readily switched to convert the same isobutylene feedstock to di- isobutylene. Furthermore, di-isobutylene can readily make up the additional component volume to replace the MTBE used hitherto in automotive fuel component pool.

It has also been found that the reduction in break-up time for foams formed is not due to a dilution effect of di-isobutylene. Test results show that addition of up to 2.5% by volume of di-isobutylene in the fuel did not show any reduction in the foam break-up time of the fuel tested.

The present invention is further illustrated with reference to the following Examples: Tests were carried out in which di-isobutylene (a mixture of 3 parts 2,4,4- trimethylpent-1-ene and 1 part 2,4,4-trimethylpent-2-ene) was added to varying quantities to a distillate fuel which was susceptible to foam formation. The resultant admixture was tested in the BNPe Anti-Foam test (French Standard Test NF M 07-075) and the results obtained are shown in Table 1 below: 10. A composition according to any one of the preceding Claims wherein di- isobutylene is used in an amount from 5 to less than 15% by volume of the total fuel composition.

Claims

Claims: 1. A fuel composition comprising a base fuel having a final boiling point greater than 150 C and an anti-foam, characterised in that the anti-foam comprises di-isobutylene in an amount greater than 2.5 % by volume based on the total fuel composition.
2. A composition according to Claim 1 wherein the base fuels comprises mixtures of saturated, olefinic and aromatic hydrocarbons derivable from straight run streams, thermally or catalytically cracked hydrocarbon feedstocks, hydrocracked petroleum fractions, catalytically reformed hydrocarbons, or synthetically produced hydrocarbon mixtures.
3. A composition according to Claim 1 or 2 wherein the base fuel is a petroleum fuels having a boiling range from gasoline (which typically boils in the range from 50 and 200 C with a final boiling point > 150 C ) to distillate fuel (which typically boils between 150 and 400 C).
4. A composition according to any one of the preceding Claims wherein the base fuel is a common distillate fuel selected from motor gasoline, kerosene and diesel fuels.
5. A composition according to any one of the preceding Claims wherein the base fuel has a sulphur content of less than 100 ppm by weight.
6. A composition according to any one of the preceding Claims wherein the base fuel has a sulphur content of less than 50 ppm by weight.
7. A composition according to any one of the preceding Claims wherein the di- isobutylene comprises a mixture of 2,4,4-trimethylpent-l-ene and 2,4,4-trimethylpent-2- ene.
8. A composition according to any one of the preceding Claims wherein the di- isobutylene comprises a mixture of 2,4,4-trimethylpent-l-ene and 2,4,4-trimethylpent-2- ene in a ratio of 75% to 25% by weight.
9. A composition according to any one of the preceding Claims wherein di- isobutylene is used in an amount from 2.5 - 35 % by volume.