Fuel and related compositions – Liquid fuels – Containing organic -c
Reexamination Certificate
2000-05-09
2001-08-07
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing organic -c
C044S403000
Reexamination Certificate
active
06270537
ABSTRACT:
The present invention concerns a fuel composition especially an aviation fuel composition, and a blend for use therein.
In high speed aircraft, both civilian and military, the liquid fuel is combusted to produce power, but also is circulated in the aircraft as a heat exchange fluid to remove the excess heat generated at such speeds e.g. in lubricating oils. The fuel is thus maintained for long periods at high temperatures, which results in discoloration and decomposition to produce soluble coloured products and insoluble products such as gums, sediments and granular material; insoluble products can form deposits that reduce the heat exchange capacity and can block filters potentially causing loss of power. Soluble coloured by-products are unsightly and an indication of some decomposition. The cause of discoloration etc. may be from phenols, naphthenates and sulphur compounds and/or metals which are often present in the fuels.
U.S. Pat. No. 5,478,367 describes the addition to diesel or jet fuel of a substituted unsaturated polyamine derivative dispersant to reduce particulate emissions on combustion and to reduce fouling i.e. deposition of insoluble deposits. The macrocyclic compounds preferably contain an N═C—N—C═O group and especially have fused rings, such as are made by reaction of a hydrocarbyl (e.g. fatty alkyl) succinic anhydride and a polyalkylene amnine.
Canadian Patent Publ. 2067907 describes the addition to distillate jet fuels of hydroxylamines to stabilise them against degradation at elevated temperatures.
U.S. Pat. No. 5,468,262 describes addition to jet fuels of thermal stability additives which are prepared by reacting a polyamine, aldehyde and phenol to form a condensate which is then reacted with a succinic anhydride containing a polyolefin derived unsaturated group. The additives are effective at 0.2% by weight.
EP-A-678568 describes addition to jet engine fuels of anti deposition agents which are derivatives of (thio)phosphonic acids.
There have now been discovered improved thermal stabilising additives for jet fuels which are oil soluble macromolecules comprising a hydroxy-carboxylic acid functionality.
Accordingly the present invention provides a jet fuel composition comprising a cyclic compound comprising m units of the formula 1a.
and n units of the formula (Ib)
joined together to form a ring,
wherein Y is a divalent bridging group which may be the same or different in each unit;
R
0
is H or (C
1
-C
6
) alkyl; R
5
is H or (C
1-C
60
) alkyl; and j is 1 or 2;
R
3
is hydrogen, a hydrocarbyl or a hetero-substituted hydrocarbyl group; each of R
1
, R
2
and R
4
, which may be the same or different, is hydroxyl, hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl, with the proviso that at least one of R
1
, R
2
, R
4
is hydroxyl, and m+n is 4 to 20, m is 1-8 and n is at least 3 and preferably either R
1
is hydroxyl and R
2
and R
4
are independently either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl, or R
2
and R
4
are hydroxyl and R
1
is either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl; and m+n is from 4 to 20, m is from 1 to 8 and n is at least 3. The cyclic compound is preferably a compound of the formula (I) with a ring structure.
wherein Y
1
and Y
2
are divalent bridging groups, which may be the same or different; R
3
is hydrogen, a hydrocarbyl or a hetero-substituted hydrocarbyl group; each of R
1
, R
2
and R
4
, which may be the same or different, is hydroxyl hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl, with the proviso that at least one of R
1
, R
2
, R
4
is hydroxyl, and m+n is 4 to 20, m is 1-8 and n is at least 3.
When more than one salicylic acid unit is present in the ring (i.e. m>1), the salicylic acid and phenol units may be distributed randomly, although this does not exclude the possibility that in some rings there may be several salicylic acid units joined together in a row. Thus the m and n units may be joined in block and/or randomly.
In the formula I Y
1
and Y
2
may each independently be a hydrocarbyl bridging group or be a hetero-substituted hydrocarbyl group or up to 50% mole of the totality of Y
1
and Y
2
group may be a hetero atom. The hydrocarbyl bridging group is preferably aliphatic and has a chain of 1-4 carbon atoms; preferably the group is of formula (CR
7
R
8
)
d
e.g. (CHR
8
)d where each of R
7
and R
8
, which may be the same or different, represents hydrogen or hydrocarbyl e.g. of 1-6 carbons, such as methyl or ethyl and d is an integer of 1-4 preferably 2 or especially 1; advantageously the group is of formula (CHR
8
)
d
where R
8
is as defined above preferably methyl or especially hydrogen. Y
1
and/or Y
2
may also represent a hetero-substituted hydrocarbyl group with a hetero atom, e.g. O, S or NH interrupting a chain of carbon atoms e.g. 2-4 carbon atoms, such as in CH
2
OCH
2
, CH
2
SCH
2
or CH
2
NHCH
2
. Up to 50 mole % of the totality of Y
1
and Y
2
groups may be a hetero atom e.g. O or NH or especially S, e.g. 1-50 mole % especially 8-20 mole % of said groups. Preferably Y
1
and Y
2
are hydrocarbyl groups, and the compound of formula I is sulphur free.
Each of R
1
, R
2
and R
4
represents hydroxyl, hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl with the proviso that at least one of R
1
, R
2
and R
4
represents hydroxyl. Thus all three may represent hydroxyl as in a phloroglucinol derivative, or two as in a resorcinol derivative (i.e. the compound of formula I contains a resorcinarene group), or one as in a phenol derivative. Preferably either R
1
is hydroxyl and R
2
and R
4
are independently either hydrogen (which is preferred), hydrocarbyl or hetero-substituted hydrocarbyl, or R
2
and R
4
are hydroxyl and R
1
is either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl.
Regarding R
1
to R
5
and R
8
, the term “hydrocarbyl” includes (C
1
-C
60
) alkyl such as t-butyl, t-amyl, s-butyl, isopropyl, octyl, nonyl, dodecyl and octadecyl. Alternatively the hydrocarbyl group may be derived from a polyolefin, for example polyethylene, polypropylene, polybutylene or a polyolefin copolymer, for example an ethylene/propylene copolymer, preferably derived from a polyisobutene. Alternatives include isoprene-butadiene, styrene-isoprene or styrene-butadiene block copolymers such as those disclosed in WO 96/40846, or ethylene-propylene and ethylene-butene-1 copolymers having molecular weights from 1500 to 2500 or 7500, as disclosed in U.S. Pat. No. 5,567,344 and U.S. Pat. No. 5,578,237. Mixtures of all the above may also be employed. Any hetero-substituted hydrocarbyl group has the heteroatom, preferably —O— or ═NH, interrupting a chain of carbon atoms, such as an alkoxy-alkyl group of 2-20 carbons. Each of R
1
-R
5
may otherwise be as described for R
3
below.
The hydrocarbyl group for R
1
, R
2
or R
4
usually has 1-14 e.g. 1-6 carbons and is preferably saturated, especially an alkyl group e.g. methyl, ethyl, propyl, butyl or hexyl group. The hetero-substituted hydrocarbyl group has at least one e.g. 1-3 especially 1 hetero atom e.g. O, S or NH interrupting a chain of carbon atoms e.g. 2-20, or 2-6 carbons as in an alkoxy alkylene group such as ethoxy ethyl.
R
3
is hydrogen, hydrocarbyl or a hetero-substituted hydrocarbyl group. Preferably R
3
is hydrocarbyl or a hetero-substituted hydrocarbyl in at least R
3
group in the compound of formula 1, especially with n such groups in the molecule. The hydrocarbyl group may be alkyl, alkenyl, cycloalkyl, aryl, aralkyl and contains at least 1 especially at least 4 or at least 8 carbon atoms e.g. 4-40 carbons in particular with 8-20 carbons in a chain. Preferred are linear or branched alkyl e.g. of 8-24 or 8-20 carbons, such as decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, lauryl, myristyl, stearyl, palmityl, propylene tetramer or alkenyl e.g. of 6-24 carbons such as oleyl, or cycloalkyl e.g. of 5-8 carbons such as cyclohexyl, aryl e.g. of 6-24 carbons such as phenyl, tolyl and alkylphenyl with 6-16 carbons in the alkyl e.g. dodecylphenyl and aralkyl e.g
BP Oil International Limited
Medley Margaret
Nixon & Vanderhye
Toomer Cephia D.
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