[0001] This invention relates to fuel oil compositions and more especially to fuel oil compositions
containing cracked components which are stabilized against sediment formation and
colour development during storage. Cracked components are frequently included to give
higher yields of diesel fuel and heating oil.
[0002] However, when diesel and heating oils containing cracked components are stored at
ambient or elevated temperatures in air they become discoloured and precipitate sludge
or sediment.
[0003] It is clear that the problem of discoloration and sediment formation is exacerbated
by the presence of cracked components in the fuel. This is demonstrated by the results
in Table 1 which show the amount of sediment formed and the colour change when various
fuel blends are tested in the AMS 77.061 accelerated stability test. Published research
(see, for example, Offenhauer et. al, Industrial and Engineering Chemistry, 1957,
Volume 49, page 1265, and the Proceedings of the 2nd International Conference on the
Long Term Stability of Liquid Fuels, San Antonio, Texas, published October 1986) suggests
that discoloration and sediment result from the oxidation of sulphur and nitrogen
compounds present in the fuel. The analysis of cracked components is consistent with
this. The results in Table 2 show that cracked components contain significantly larger
quantities of nitrogen and sulphur than straight distillates. Also, the addition of
nitrogen and sulphur compounds to a stable straight distillate causes an increase
in both sediment and colour in the AMS 77.061 test (Table 3) with the worst result
being obtained when both nitrogen and sulphur compounds are present in the fuel.
[0004] We have found that sediment and colour formation in distillate fuels which are stored
at ambient temperatures for long periods may be reduced by the addition of certain
quaternary ammonium compounds.
[0005] There are several patents which disclose the use of quaternary ammonium compounds
in fuel oils. Most of these patents disclose the use of quaternary ammonium compounds
in which the sum total of carbon atoms in the cation exceeds 10. U.S. Patents No.
3,008,813, 3,265,474, 3,397,970 and 3,346,353 all disclose the use of quaternary ammonium
compounds containing the cation:
[R₂NMe₂]
(+)
where R is C₁₂ to C₁₄, as agents for improving the water tolerance of hydrocarbon
oils.
[0006] U.S. Patent No. 3,033,665 and U.S. Patent No. 3,158,647 both disclose the use of
quaternary ammonium compounds containing the cation:
[R₂NR′₂]
(+)
where R is C₈ to C₂₂ and R′ is C₁ to C₄, as additives for producing a non-stalling
gasoline and as fuel oil stabilisers.
[0007] U.S. Patent No. 3,493,354 discloses the use of quaternary ammonium compounds containing
the cation:
[R₄N]
(+)
in which the sum total of carbon atoms is at least 12, as part of a package to prevent
smoke.
[0008] U.K. Patent No. 973,826 discloses the use of quaternary ammonium nitrites containing
the cation:
[R₂NR′₂]
(+)
where R is C₁₂ to C₂₂ and R′ is C₁ to C₁₀, as a fuel additive to be used in conjunction
with an amine.
[0009] U.K. Patent No. 1,078,497 discloses the use of quaternary ammonium compounds containing
the cation:
[R₂NR′₂]
(+)
where R is C₆ to C₂₂ and R′ is C₁ to C₅.
[0010] U.K. Patent No. 1,392,600 discloses the use as antiwear additives of quaternary ammonium
phosphates in which the cation contains at least 10 (and preferably more) carbon atoms.
[0011] U.K. Patent No. 1,409,019 discloses the use of quaternary ammonium compounds containing
the cation:
[RN(CH₃)₃]
(+)
where R is C₈ to C₄₀, as additives to improve the water tolerance of hydrocarbon liquids.
[0012] Three patents disclose the use of quaternary ammonium compounds in which the total
number of cations atoms in the cation is less than 10. Two of the patents, U.K. Patents
Nos. 1,199,015 and 1,221,647, disclose the use of quaternary ammonium phosphates and
thiophosphates. However phosphorus "poisons" transition metal catalysts such as are
commonly used as particulate traps in e.g. diesel engines. The third patent, U.K.
Patent No. 1,432,265, describes quaternary ammonium compounds to be used in combination
with a sulphone polymer as an antistatic additive.
[0013] The present invention provides a fuel composition comprising a fuel oil obtained
by the cracking of heavy oil and a quaternary ammonium compound which is soluble in
the fuel and which comprises a hydrocarbyl cation in which the ratio of carbon atoms
to quaternary nitrogen atoms is not more than 10:1 and an anion which is derived from
an acid which is a carboxylic acid, carboxylic acid anhydride, a phenol, a sulphurized
phenol or a sulphonic acid. The hydrocarbyl group or groups optionally carries or
carry a tertiary amino nitrogen atom or atoms but is or are otherwise unsubstituted.
[0014] Advantageously, the quaternary ammonium compound contains 1 to 4 quaternary nitrogen
atoms, and not more than 10 carbon atoms.
[0015] The quaternary ammonium compounds are effective fuel stabilizers in the absence of
any other additive. Furthermore, the quaternary ammonium compounds are more effective
as fuel stabilizers than quaternary ammonium compounds in which the ratio of carbon
atoms to quaternary nitrogen atoms in the cation exceeds 10.
[0016] Examples of suitable compounds are
1) Quaternary ammonium compounds in which the structure of the cation is:
[R¹R²R³R⁴N]+
in which R¹, R², R³, R⁴ are alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkaryl
or aralkyl groups such that the sum total of carbon atoms in the cation does not exceed
10.
Examples of such cations include tetramethylammonium, ethyltrimethylammonium, n-propyltrimethylammonium,
iso-propyltrimethylammonium, n-butyltrimethylammonium, pentyltrimethylammonium, hexyltrimethylammonium,
heptyltrimethylammonium, phenyltrimethylammonium, o-tolyltrimethylammonium, m-tolyltrimethylammonium,
p-tolyltrimethylammonium, benzyltrimethylammonium, diethyldimethylammonium, di-n-propyldimethylammonium
and di-n-butyldimethylammonium.
2) Quaternary ammonium compounds in which the structure of the cation is:
- where R⁵ and R⁶ are alkyl, cycloalkyl, alkenyl, or cycloalkenyl and may be the
same or different but are such that the total number of carbon atoms in the cation
does not exceed 10.
Examples of such cations include methylpyridinium, ethylpyridinium, methyl-2-picolinium,
methyl-3-picolinium and methyl-4-picolinium.
3) Quaternary ammonium compounds in which the structure of the cation is:
- where R⁷ is alkyl, cycloalkyl, alkenyl, cycloalkenyl
- where R⁸ is nothing, when n = 1, or alkyl, cycloalkyl, alkenyl or cycloalkenyl,
when n = 2, such that the ratio of carbon atoms in the cation to quaternary nitrogen
atoms does not exceed 10:1.
Examples of such cations are the cations in which R⁷ = methyl, R⁸ is absent, and n
= 1, and in which R⁷ = R⁸ = methyl, and n = 2.
4) Quaternary ammonium compounds in which the structure of the cation is:
[R⁹R¹⁰R¹¹R¹²N₄(CH₂)₆]m(+)
- where R⁹ is alkyl, cycloalkyl, alkenyl, cycloalkenyl
- where R¹⁰, R¹¹, R¹² can be nothing, or alkyl, cycloalkyl, alkenyl, cycloalkenyl
such that the ratio of carbon atoms in the cation to quaternary nitrogen atoms does
not exceed 10:1
- m is 1 to 4, the value of m being increased from unity by one for each of R¹⁰, R¹¹,
R¹², having a meaning other than zero.
Examples of such cations are:
[(CH₃)pN₄(CH₂)₆]p(+)
where p is 1, 2, 3 or 4.
[0017] It will be understood that in compounds containing two or more quaternary nitrogen
compounds the linkages between them will also be hydrocarbyl groups, i.e., the cation
consists of quaternary nitrogen, carbon and hydrogen atoms, optionally substituted
by tertiary amino nitrogen atoms.
[0018] Cations in groups (3) and (4) when R⁸, or one or more of R¹⁰, R¹¹, R¹², represent
zero are examples of hydrocarbyl groups carrying tertiary amino nitrogen atoms.
[0019] The acid which is used to form the anion may be a carboxylic acid, carboxylic acid
anhydride, phenol, sulphurized phenol or sulphonic acid.
[0020] The carboxylic acid may be e.g.:
i) An acid of the formula
R¹³-COOH
where R¹³ is hydrogen, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl,
or aryl. Examples of such acids include formic acid, acetic acid, propionic acid,
butyric acid, valeric acid, palmitic acid, stearic acid, cyclohexanecarboxylic acid,
2-methylcyclohexanecarboxylic acid, 4-methylcyclohexane carboxylic acid, oleic acid,
linoleic acid, linolenic acid, cyclohex-2-eneoic acid, benzoic acid, 2-methylbenzoic
acid, 3-methylbenzoic acid, 4-methylbenzoic acid, salicylic acid, 2-hydroxy-4-methylbenzoic
acid, 2-hydroxy-4-ethylsalicylic acid, p-hydroxybenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic
acid, o-aminobenzoic acid, p-aminobenzoic acid, o-methoxybenzoic acid and p-methoxybenzoic
acid.
ii) A dicarboxylic acid of the formula
HOOC-(CH₂)n-COOH
where n is zero or an integer, including e.g. oxalic acid, malonic acid, succinic
acid, glutaric acid, adipic acid, pimelic acid and suberic acid. Also included are
acids of the formula
where x is zero or an integer, y is zero or an integer and x and y may be equal or
different and R¹³ is defined as in (i). Examples of such acids include the alkyl or
alkenyl succinic acids, 2-methylbutanedioic acid, 2-ethylpentanedioic acid, 2-n-dodecylbutanedioic
acid, 2-n-dodecenylbutanedioic acid, 2-phenylbutanedioic acid, and 2-(p-methylphenyl)butanedioic
acid. Also included are polysubstituted alkyl dicarboxylic acids wherein other R¹³
groups as described above may be substituted on the alkyl chain. These other groups
may be substituted on the same carbon atom or different atoms. Such examples include
2,2-dimethylbutanedioic acid; 2,3-dimethylbutanedioic acid; 2,3,4-trimethylpentanedioic
acid; 2,2,3-trimethylpentanedioic acid; and 2-ethyl-3-methylbutanedioic acid.
[0021] The dicarboxylic acids also include acids of the formula:
HOOC-(C
rH
2r-2)COOH
where r is an integer of 2 or more. Examples include maleic acid, fumaric acid, pent-2-enedioic
acid, hex-2-enedioic acid; hex-3-enedioic acid, 5-methylhex-2-enedioic acid; 2,3-di-methylpent-2-enedioic
acid; 2-methylbut-2-enedioic acid; 2-dodecylbut-2-enedioic acid; and 2-polyisobutylbut-2-enedioic
acid.
[0022] The dicarboxylic acids also include aromatic dicarboxylic acids e.g. phthalic acid,
isophthalic acid, terephthalic acid and substituted phthalic acids of the formula:
where R¹³ is defined as in (i) and n = 1, 2, 3 or 4 and when n > 1 then the R¹³ groups
may be the same or different. Examples of such acids include 3-methylbenzene-1,2-dicarboxylic
acid; 4-phenylbenzene-1,3-dicarboxylic acid; 2-(1-propenyl)benzene-1,4-dicarboxylic
acid, and 3,4-dimethylbenzene-1,2-dicarboxylic acid.
[0023] The carboxylic acid anhydrides include the anhydrides that may be derived from the
carboxylic acids described above. Also included are the anhydrides that may be derived
from a mixture of any of the carboxylic acids described above. Specific examples include
acetic anhydride, propionic anhydride, benzoic anhydride, maleic anhydride, succinic
anhydride, dodecylsuccinic anhydride, dodecenylsuccinic anhydride, an optionally substituted
polyisobutylenesuccinic anhydride, advantageously one having a molecular weight of
between 500 and 2000 daltons, phthalic anhydride and 4-methylphthalic anhydride.
[0024] The phenols from which the anion of the quaternary ammonium compound may be derived
are of many different types. Examples of suitable phenols include:
(i) Phenols of the formula:
where n = 1, 2, 3, 4 or 5, where R¹³ is defined above and when n > 1 then the substituents
may be the same or different. The hydrocarbon group(s) may be bonded to the benzene
ring by a keto or thio-keto group. Alternatively the hydrocarbon group(s) may be bonded
through an oxygen, sulphur or nitrogen atom. Examples of such phenols include o-cresol;
m-cresol; p-cresol; 2,3-dimethylphenol; 2,4-dimethylphenol; 2,3,4-trimethylphenol;
3-ethyl-2,4-dimethylphenol; 2,3,4,5-tetramethylphenol; 4-ethyl-2,3,5,6-tetramethylphenol;
2-ethylphenol; 3-ethylphenol; 4-ethylphenyl; 2-n-propylphenol; 2-isopropylphenol;
4-n-butylphenol; 4-isobutylphenol; 4-sec-butylphenol; 4-t-butylphenol; 4-nonylphenol;
2-dodecylphenol; 4-dodecylphenol; 4-octadecylphenol; 2-cyclohexylphenol; 4-cyclohexylphenol;
2-allylphenol; 4-allylphenol; 2-hydroxydiphenyl; 4-hydroxydiphenol; 4-methyl-4′-hydroxydiphenyl;
o-methoxyphenol; p-methoxyphenol; p-phenoxyphenol; 2-hydroxydiphenylsulphide; 4-hydroxydiphenylsulphide;
4-hydroxyphenylmethylsulphide; and 4-hydroxyphenyldimethylamine. Also included are
alkyl phenols where the alkyl group is obtained by polymerization of a low molecular
weight olefin e.g. polypropylphenol or polyisobutylphenol.
[0025] Also included are phenols of the formula:
and/or
where R′ and R˝ which may be the same or different are as defined above for R¹³ and
m and n are integers. Examples of such phenols include 2,2′-dihydroxy-5,5′-dimethyldiphenylmethane;
5,5′-dihydroxy-2,2′-dimethyldiphenylmethane; 4,4′-dihydroxy-2,2′-dimethyl-dimethyldiphenylmethane
; 2,2′-dihydroxy-5,5′-dinonyldiphenylmethane; 2,2′-dihydroxy-5,5′-didodecylphenylmethane
and 2,2′,4,4′-tetra-t-butyl-3,3′-dihydroxydiphenylmethane.
[0026] Also included are sulphurized phenols of the formula:
where R′ and R˝ which may be the same or different are as defined above, and m and
n are integers and x is 1,2,3 or 4. Examples of such phenols include:
2,2′-dihydroxy-5,5′dimethyldiphenylsulphide;
5,5′-dihydroxy-2,2′-di-t-butyldiphenyldisulphide;
4,4′-dihydroxy-3,3′-di-t-butyldiphenylsulphide;
2,2′-dihydroxy-5,5′-dinonyldiphenyldisulphide;
2,2′-dihydroxy-5,5′didodecyldiphenyldisulphide;
2,2′-dihydroxy-5,5′-didodecyldiphenyltrisulphide; and
2,2′-dihydroxy-5,5′-didodecyldiphenyltetrasulphide.
[0027] The sulphonic acids from which the anion of the quaternary ammonium salt can be derived
include alkyl and aryl sulphonic acids which have a total of 1-200 carbon atoms per
molecule although the preferred range is 1-80 atoms per molecule. Included in this
description are aryl sulphonic acids of the formula:
where n = 1, 2, 3, 4, 5 and when n > 1 the substituents may be the same or different,
and R‴, may represent R¹³ as defined above.
[0028] The hydrocarbon group(s) may be bonded to the benzene ring through a carbonyl group
or the thio-keto group. Alternatively the hydrocarbon group(s) may be bonded to the
benzene ring through a sulphur, oxygen or nitrogen atom. Thus examples of sulphonic
acids that may be used include: benzene sulphonic acid; o-toluenesulphonic acid,
m-toluenesulphonic acid; p-toluenesulphonic acid; 2,3-dimethylbenzenesulphonic acid;
2,4-dimethylbenzenesulphonic acid; 2,3,4-trimethylbenzenesulphonic acid; 4-ethyl-2,3-dimethylbenzenesulphonic
acid; 4-ethylbenzenesulphonic acid; 4-n-propylbenzenesulphonic acid; 4-n-butylbenzenesulphonic
acid; 4-isobutylbenzenesulphonic acid; 4-sec-butylbenzenesulphonic acid; 4-t-butylbenzenesulphonic
acid; 4-nonylbenzenesulphonic acid; 2-dodecylbenzenesulphonic acid; 4-dodecylbenzenesulphonic
acid; 4-cyclohexylbenzenesulphonic acid; 2-cyclohexylbenzenesulphonic acid; 2-allylbenzenesulphonic
acid; 2-phenylbenzenesulphonic acid; 4(4′methylphenyl)benzenesulphonic acid; 4-methylmercaptobenzenesulphonic
acid; 2-methoxybenzene sulphonic acid; 4-phenoxybenzenesulphonic acid; 4-methylaminobenzenesulphonic
acid; 2-dimethylaminobenzenesulphonic acid; and 2-phenylaminobenzenesulphonic acid.
Also included are sulphonic acids of the type listed above where R‴ is derived from
the polymerization of a low molecular weight olefin e.g. polypropylbenzenesulphonic
acid and polyisobutylenebenzenesulphonic acid.
[0029] Also included are sulphonic acids of the formula:
R-SO₃H
where R is alkyl, cycloalkyl, alkenyl or cycloalkenyl. Examples of such sulphonic
acids that may be used include methylsulphonic acid; ethylsulphonic acid; n-propylsulphonic
acid; n-butylsulphonic acid; isobutylsulphonic acid; sec-butylsulphonic acid; t-butylsulphonic;
nonylsulphonic acid; dodecylsulphonic acid; polypropylsulphonic acid; polyisobutylsulphonic
acid; cyclohexylsulphonic acid; and 4-methylcyclohexylsulphonic acid.
[0030] Some of the quaternary ammonium salts which may be employed according to the present
invention are commercially available. It is preferred to use one of these compounds.
Alternatively the quaternary ammonium compounds may be synthesized in any suitable
manner. The quaternary ammonium compounds may be prepared by known processes. Two
methods are preferred for the synthesis of compounds such as quaternary ammonium sulphonates,
sulphurized phenates and carboxylates.
[0031] In the first method a quaternary ammonium hydroxide is prepared by reacting, for
example, a quaternary ammonium chloride with a strong base (for example sodium hydroxide)
in an alcohol (for example methanol).
R₄N
(+) X
(-) + NaOH → R₄N
(+) OH
(-)+ NaX
[0032] After removing the metal halide by filtration, the solution of quaternary ammonium
hydroxide is mixed with the acid in a suitable solvent and allowed to react:
R₄N(+) OH
(-) + HA → R₄N(+) A(-) + H₂O
[0033] The rate of reaction may be increased by raising the reaction temperature above ambient.
Once the reaction is complete the solvents and water are removed by distillation.
[0034] In the second method the organic acid is reacted with a metal oxide or hydroxide
to form the metal salt:
HA + NaOH → NaA + H₂O
[0035] If the reaction is done in a suitable solvent (for example, heptane or toluene) the
water formed during the reaction may be removed by refluxing the solvent and using
a Dean and Stark trap. Once all the water has been removed the solution of the metal
salt is treated with a quaternary ammonium halide:
NaA + [R₄N]
(+) X
(-) →[R₄N]
(+)A
(-) + NaX
[0036] The metal halide is removed by filtration, the solvent is removed by distillation.
Alternatively, the solvent can be removed by distillation and the metal halide filtered
from the final product.
[0037] Preferably the fuel composition comprises 5 to 1000 ppm, more preferably 10 to 500
ppm, and most preferably 20 to 200 ppm of quaternary ammonium compound based on parts
of the fuel.
[0038] The cracked component in the fuel oil which leads to the undesirable colour formation
and sediment is generally obtained by cracking of heavy oil and may be fuel oil in
which the main constituent is a fraction otained from a residual oil.
[0039] Typical methods available for the thermal cracking are visbreaking and delayed coking.
Alternatively the fuels may be obtained by catalytic cracking, the principal methods
being moving-bed cracking and fluidized-bed cracking. After cracking, the distillate
oil is extracted by normal or vacuum distillation, the boiling point of the distillate
oil obtained usually being 60-500°C. Compositions composed entirely of this fuel
or fuels which are mixtures of the cracked fraction and normal distillates may be
used in the present invention.
[0040] The present invention accordingly provides a fuel composition comprising a distillate
fraction and a cracked fraction and a quaternary ammonium compound soluble in the
composition, the quaternary ammonium compound having a cation in which the substituent
on the or each quaternary nitrogen is a hydrocarbyl group optionally bearing a tertiary
amino nitrogen atom, and in which cation the ratio of carbon atoms to quaternary nitrogen
atoms is at most 10:1, the anion being derived from a carboxylic acid or anhydride,
a phenol, a sulphurized phenol or a sulphonic acid. The invention also provides the
use of such a quaternary ammonium compound in inhibiting sediment and color formation
in a fuel oil composition, especially one containing a component obtained by the cracking
of heavy oil.
[0041] The proportion by weight of direct-distillation fraction and cracked fraction in
a fuel oil composition which is a mixture can vary considerably, but is usually 1:0.03
- 1:2 and preferably 1:0.05 - 1:1. Typically the content of cracked fraction is usually
5-97%, and preferably 10-50%, based on the weight of the composition.
[0042] The fuel oil compositions of the present invention may contain other additives such
as antioxidants, anticorrosion agents, fluidity improvers, agents absorbing ultraviolet
radiation, detergents, dispersants and cetane improvers in small amounts (for example,
usually less than 2% based on the weight of the composition).
[0043] The present invention is illustrated by the following examples:
Example 1
Synthesis of Tetramethylammonium Dodecylphenate
[0044] A solution of sodium hydroxide (10 g; 0.25 moles) in methanol (100 mls) was added
slowly, under nitrogen, to a stirred solution of tetramethylammonium bromide (38.5
g; 0.25 moles) in methanol (200 mls). When the addition was complete the solution
was stirred for a further 30 minutes.
[0045] The sodium bromide was filtered off and the solution of the tetramethylammonium hydroxide
added directly to a solution of dodecylphenol (65.5 g; 0.25 moles) in toluene (200
mls). The reaction mixture was heated to reflux for 1 hour and then the solvents were
removed by heating to 150°C under vacuum.
[0046] Stanco 150 (83.8 g), a mineral oil base stock (Exxon), was added to the product which
was then filtered through Dicalite 4200 (diatomaceous earth).
TBN = 122 mg KOH/g
TABLE 1 Shows the effect of blending different amounts of a straight distillate with an unhydrofined
catalytically cracked gas oil on sediment and colour in the AMS 77.061 accelerated
stability test.
TABLE 2 Shows typical nitrogen and sulphur levels for straight run distillates and unhydrofined
catalytically cracked gas oils.
TABLE 3 Shows the effect of doping a stable fuel with compounds containing nitrogen and sulphur.
TABLE 4 Shows AMS 77.061 test results on fuels treated with quaternary ammonium compounds
in accordance with the present invention. From a comparison of the results for the
treated fuels with the results for the untreated fuel, it is clear that the compounds
of this invention give good control of colour and sediment.
TABLE 1
Fuel 3* |
Fuel 4** |
Sediment |
|
wt % |
(*) |
(mg/100 ml) |
Δ Colour (a) |
100 |
0 |
(0.14 ± 0.09) |
≃0.5, <0.5,<0.5 |
80 |
20 |
(0.61 ± 0.13) |
≃1.0, 1.0, 1.0,1.0 |
60 |
40 |
(1.12 ± 0.10) |
≃1.0,≃1.0,≃1.0,≃1 |
40 |
60 |
(1.80 ± 0.04) |
∼2.0, ∼2.0 |
20 |
80 |
(2.10 ± 0.10) |
∼2.0, ∼2.0 |
0 |
100 |
2.90 |
∼6.0 |
* Straight distillate |
** Unhydrofined catalytically cracked gas oil (CCGO) |
(a) Colour Change (ASTM D1500 test) |
TABLE 2
The Nitrogen and Sulphur Contents of Various Fuels |
Type of Fuel |
Nitrogen (ppm) |
Sulphur (%) |
Unhydrofined CCGO |
695 |
1.11 |
Unhydrofined CCGO |
650 |
1.70 |
Straight distillate |
50 |
0.24 |
Straight distillate |
70 |
0.25 |
Straight distillate |
97 |
0.23 |
Straight distillate |
128 |
0.24 |
TABLE 3
The Effect of Doping with Dimethyl Pyrrole (DMP) and a Sulphonic Acid (SA) on the
Stability of a Straight Distillate Fuel in the AMS 77.061 Test |
DMP |
SA |
Sediment |
Colour |
(ppm) (a) |
(ppm) (b) |
(mg/100 ml) |
Before |
After |
NIL |
NIL |
0.06, 0.10 |
< 0.5 |
< 1.0 |
NIL |
50 |
0.02, 0.00 |
< 0.5 |
< 1.5 |
|
|
|
< 0.5 |
< 1.5 |
50 |
NIL |
0.76, 0.59 |
< 0.5 |
< 1.0 |
|
|
|
< 0.5 |
< 1.0 |
50 |
50 |
1.06, 1.01 |
< 1.5 |
< 3.0 |
|
|
|
< 1.5 |
< 3.0 |
(a) 2,5-dimethylpyrrole |
(b) a commercially available alkyl-aryl sulphonic acid having a SAN of approximately
80 mg KOH.g of acid |
TABLE 4
The Effect of Short Chain Quaternary Ammonium compounds in the AMS 77.061 Test |
CATION |
ANION |
SEDIMENT (a) |
Δ COLOUR |
NONE |
NONE |
(1.18 ± 0.20) (b) |
≃1.0 |
(CH₃)₄N |
PIBSATE |
(0.05 ± 0.06) (c) |
≃1.0, ≃1.0 |
(CH₃)₄N |
DDP (d) |
(0.16 ± 0.00) (c) |
≃0.5, ≃0.5 |
(CH₃)₄N |
NPS (e) |
(0.00 ± 0.00) (c) |
≃0.5, ≃0.5 |
a) mgs.100 mls of fuel |
b) (mean ± standard deviation) of 14 tests |
c) (mean ± standard deviation) of 2 tests |
d) dodecylphenol |
e) nonylphenol sulphide |
* Fuel is 80% straight distillate and 20% unhydrofined catalytically cracked gas oil |
**Additive used at 100 ppm |
1. A fuel composition comprising a fuel oil obtained by the cracking of heavy oil
and a quaternary ammonium compound which is soluble in the fuel and which comprises
a hydrocarbyl cation in which optionally the hydrocarbyl group carries or groups carry
a tertiary amino nitrogen atom or atoms but is or are otherwise unsubstituted, and
in which cation the ratio of carbon atoms to quaternary nitrogen atoms is not more
than 10:1, and an anion which is derived from an acid which is a carboxylic acid,
carboxylic acid anhydride, phenol, sulphurized phenol or sulphonic acid.
2. A composition according to claim 1, in which the cation of the quaternary ammonium
compoud contains from 1 to 4 quaternary nitrogen atoms.
3. A fuel composition according to claim 1, in which the cation is of the formula:
[R¹R²R³R⁴N]⁺
in which R¹, R², R³, and R⁴, which may be the same or different, are each alkyl, cycloalkyl,
alkenyl, cycloalkenyl, aryl, aralkyl or alkaryl such that the number of carbon atoms
in the cation does not exceed 10.
4. A composition according to claim 3, in which the cation is tetramethylammonium.
5. A composition according to claim 1, in which the cation is of the formula:
in which R⁵ and R⁶ which may be the same or different are each alkyl, cycloalkyl,
alkenyl, or cycloalkenyl such that the number of carbon atoms in the cation does not
exceed 10.
6. A composition according to claim 1, in which the cation is of the formula:
in which R⁷ is alkyl, cycloalkyl, alkenyl or cycloalkenyl; R⁸ is nothing in which
case n is 1 or alkyl, cycloalkyl, alkenyl, or cycloalkenyl in which case n is 2, such
that the ratio of carbon atoms to quaternary nitrogen atoms in the cation does not
exceed 10.
7. A composition according to claim 1, in which the cation is of the formula:
[R⁹R¹⁰R¹¹R¹²N₄(CH₂)₆]m(+)
in which R⁹ is alkyl, cycloalkyl, alkenyl or cycloalkenyl; R¹⁰, R¹¹ or R¹² which may
be the same or different are each nothing, alkyl, cycloalkyl, alkenyl or cycloalkenyl,
such that the ratio of carbon atoms to quaternary nitrogen atoms in the cation does
not exceed 10; and m is an integer of 1 to 4, the value of m increasing from unity
by one for each of R¹⁰, R¹¹, and R¹² that represents a substituent.
8. A composition according to claim 7, in which the cation is N-methylhexamethylenetetrammonium
or N,N′N˝,N‴-tetramethylhexamethylenetetrammonium.
9. A composition according to any one of the preceding claims in which the anion of
the quaternary ammonium compound is derived from a carboxylic acid.
10. A composition according to claim 9, in which the carboxylic acid is of the formula:
R¹³-COOH
or
in which p and q which may be the same or different are each zero or an integer or
HOOC - (C
rH
2r-2) - COOH
in which r is an integer of 2 or more or
HOOC - (CH₂)
z - COOH
in which z is zero or an integer of 1 or more or
in which R¹³ is hydrogen, alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkaryl
or aralkyl.
11. A composition according to any one of claims 1 to 8, in which the anion of the
quaternary ammonium compound is derived from a carboxylic acid anhydride, advantageously
a carboxylic acid as defined in claim 10 or is a substituted succinic anhydride of
the formula:
in which R¹³ is defined as in claim 10, or is a substituted anhydride with an optionally
substituted polyisobutylene, in which the polyisobutylene advantageously has a molecular
weight of between 500 to 2000 daltons.
12. A composition according to any one of claims 1 to 8, in which the anion of the
quaternary ammonium compound is derived from a phenol, advantageously one of the formula:
in which s is an integer from 0 to 5 and R¹³ is defined as in claim 10, and when
s is greater than 1 each R¹³ may be the same or different, preferably nonylphenol
or dodecylphenol; or of the formula:
in which t and u, which may be the same or different, are each an integer from 0
to 4; or of the formula:
in which v and w, which may be the same or different, are each an integer from 0
to 4; R¹³ is as defined in claim 10, and for each t, u, v and w greater than 1, each
R¹³ may be the same or different; and x is zero or an integer from 1 to 10.
13. A composition according to claim 12 in which:
- R¹³ is C₉
- v is 1 or 2
- w is 1 or 2
- x is 1 to 6 or in which
- R¹³ is C₁₂
- both v and w are 1
- x is 1 to 6.
14. A composition according to any one of claims 1 to 8, in which the anion of the
quaternary ammonium compound is derived from a sulphonic acid, preferably one of the
formula:
in which y is an integer from 0 to 5; R¹³ is as defined in claim 10, and when y is
greater than 1 each R¹³ may be the same or different.
15. A composition as defined in any one of the preceding claims in which the fuel
oil comprises a direct-distillation fraction and a cracked fraction, the cracked fraction
comprising 5 to 97% by weight of the composition.
16. A composition as defined in any one of the preceding claims which comprises from
5 to 1000 ppm, advantageously 10 to 500 ppm, and preferably 20 to 200 ppm, of the
quaternary ammonium compound.
17. Use of a quaternary ammonium compound as defined in any one of claims 1 to 14
as an inhibitor for sediment and colour formation in a fuel oil composition.