PHOSPHORYLATED THERMAL STABILITY ADDITIVES FOR DISTILLATE FUELS

ADDITIFS PHOSPHORYLES POUR AUGMENTER LA STABILITE THERMIQUE DE MAZOUTS LEGERS

English Abstract

This invention is directed to the use of a reaction product of a hydrocarbyl
dicarboxylic
acid, or derivative thereof, a polyhydroxyl compound and a phosphorus
compound. A
representative additive is prepared by reacting polyisobutenyl succinic
anhydride (molecular
weight of about 1050 gms/mole); a polyhydroxyl compound, such as
pentaerythritol; and an
organic phosphorus compound, such as diethyl phosphite. The additive is used
in diesel and jet
fuels to reduce the formation of gums and other thermal degradation products.
The additives of
the present invention are economical to produce and provide effective
protection to the fuels at
treat rates as low as 10 mg/liter.
The invention also relates to the use of admixtures of 1) an ester formed by
reacting a
hydrocarbyl substituted dicarboxylic acid, or derivative thereof, with a
polyhydroxyl compound;
and 2) a phosphorus containing compound to stabilize distillate fuels.

Claims

I claim:
1. A fuel composition which comprises a distillate fuel and an additive,
wherein the additive
comprises the reaction product of:
i) at least one hydrocarbyl substituted dicarboxylic acid, or derivative
thereof;
ii) a polyhydroxyl compound; and
iii) a phosphorus compound.
2. The composition of claim 1 wherein component i) is a hydrocarbyl
substituted succinic
anhydride.
3. The composition of claim 1 wherein said phosphorus compound is an organic
phosphorus
compound.
4. The composition of claim 1 wherein said phosphorus compound is an inorganic
phosphorus-containing acid or anhydride, including partial sulfur analogs
thereof.
5. The composition of claim 2 wherein said hydrocarbyl group is a
polyisobutenyl group
having a number average molecular weight of from about 500 to 5,000.
6. The fuel composition of claim 1 wherein said additive is present in an
amount sufficient
to reduce the formation of deposits in the fuel system and the exhaust system
of an engine
operating on said fuel composition.
7. The fuel composition of claim 1 wherein said additive is present in an
amount of from
about 1 to about 1000 mg per liter of fuel.
8. The fuel composition of claim 1 wherein said additive is present in an
amount of from
about 30 to about 200 mg per liter of fuel.

9. The fuel composition of claim 1 wherein said distillate fuel is selected
from diesel fuel or
jet fuel.
10. The fuel composition of claim 9 wherein said jet fuel is selected from JP-
8 jet fuel, Jet-A
fuel and Jet A-1 fuel.
11. The fuel composition according to claim 1 further comprising additives
selected from the
group consisting of ashless dispersants, antioxidants, metal deactivators,
corrosion
inhibitors, conductivity improvers, fuel system icing inhibitors, distillate
fuel stabilizers,
cetane improvers and demulsifiers.
12. A method of reducing deposit formation in engines, wherein said deposit
formations are a
result of distillate fuel subjected to thermal stress, which comprises fueling
said engine
with and operating said engine on the fuel composition of claim l .
13. A composition of matter comprising the reaction products of:
a) at least one compound of the structural formula:
<IMG>
wherein R is a hydrocarbyl radical of 1 to 300 carbon atoms; R1 and R2 are
each
independently selected from the group of -OH, -Cl, -O-lower alkyl; and when R1
and R2 are taken together -O-;
b) at least one polyhydroxyl alcohol selected from:
i) R3 -(OH)x
21

wherein x is an integer of 2 or more and R3 is a hydrocarbyl group of 1 to
20 carbon atoms;
ii) HO-((CH2)y -O)Z-H
wherein y is an integer of 1 to 10 carbon atoms and z is an integer of 1 to
100; and
iii) <IMG>
wherein each R4 can be independently H or -CH3; and x, y and n can each
independently range from 1 to 20; and
iv) mixtures thereof; and
c) at least one phosphorus-containing compound.
14. The composition according to claim 13 wherein R1 and R2 are -O-; R is
polyalkenyl; the
polyhydroxyl alcohol is selected from the group consisting of alkyl diols,
alkyl triols,
pentaerythritol, dipentaerythritol, tripentaerythritol, pentaerythritol
propoxylate,
pentaerythritol ethoxylate, sorbitol, glycols and mixtures thereof; and the
phosphorus-containing
compound is selected from the group consisting of dialkyl phosphites, trialkyl
22

phosphites, phosphorus pentaoxide, phosphoric acid, phosphorous acid,
hypophosphorus
acid and mixtures thereof.
15. The composition according to claim 13 wherein R is a polyolefin having a
number
average molecular weight from about 500 to about 5,000; the polyhydroxyl
alcohol is
pentaerythritol and the phosphorus containing compound is selected from
diethyl
phosphite, dibutylphosphite and mixtures thereof.
16. The composition according to claim 13 wherein the mole ratio of component
(a) to
component (b) is in the range of from 1:2 to 5:1.
17. A method of reducing deposit formation in engines, wherein said deposit
formations are a
result of distillate fuel subjected to thermal stress, which comprises fueling
said engine
with and operating said engine on the fuel composition comprising a major
amount of
fuel and a minor amount of the composition of matter of claim 13.
18. A method of stabilizing a fuel, wherein said method comprises adding to a
fuel to be
stabilized the composition of claim 13.
19. A fuel composition which comprises a distillate fuel and an additive, the
additive
comprising an admixture of:
a) the reaction product of at least one hydrocarbyl substituted dicarboxylic
acid, or derivative thereof, with a polyhydroxyl compound; and
b) phosphorus compound.
20. The fuel composition of claim 19 wherein the hydrocarbyl substituted
dicarboxylic acid,
or derivative thereof, is a hydrocarbyl substituted succinic anhydride.
23

21. The fuel composition according to claim 19 wherein the phosphorus compound
is an
organic phosphorus compound.
22. The fuel composition according to claim 19 wherein the phosphorus compound
is an
inorganic phosphorus-containing acid or anhydride, including partial sulfur
analogs
thereof.
23. The fuel composition according to claim 19 wherein said hydrocarbyl group
is a
polyisobutenyl group having a number average molecular weight of from about
500 to
5,000.
24. The fuel composition according to claim 19 wherein said additive is
present in an amount
of from about 1 to about 1000 mg per liter of fuel.
25. The fuel composition according to claim 19 wherein said distillate fuel is
selected from
diesel fuel or jet fuel.
26. A method of reducing deposit formation in engines, wherein said deposit
formations are a
result of distillate fuel subjected to thermal stress, which comprises fueling
said engine
with and operating said engine on the fuel composition of claim 19.
27. An additive fluid concentrate for use in distillate fuels comprising an
admixture of:
a) the reaction product of at least one hydrocarbyl substituted dicarboxylic
acid, or
derivative thereof, with a polyhydroxyl compound; and
b) phosphorus compound.
28. A method of stabilizing a fuel, wherein said method comprises adding to a
fuel to be
stabilized the additive fluid concentrate of claim 27.
24

29. An additive fluid concentrate for use in distillate fuels comprising the
reaction product of:
a) at least one compound of the structural formula:
<IMG>
wherein R is a hydrocarbyl radical of 1 to 300 carbon atoms; R1 and R2 are
each
independently selected from the group of -OH, -Cl, -O-lower alkyl; and when R1
and R2 are taken together -O-;
b) at least one polyhydroxyl alcohol selected from the group consisting of:
i) R3 -(OH)x
wherein x is an integer of 2 or more and R3 is a hydrocarbyl group of 1 to
20 carbon atoms;
ii) HO -((CH2)y -O)Z-H
wherein y is an integer of 1 to 10 carbon atoms and z is an integer of 1 to
100; and
iii) <IMG>
wherein each R4 can be independently H or -CH3; and x, y and n can each
independently range from 1 to 20; and

iv) mixtures thereof; and
c) at least one phosphorus-containing compound.
30. A method of stabilizing a fuel, wherein said method comprises adding to a
fuel to be
stabilized the additive fluid concentrate of claim 29.
26

Description

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PHOSPHORYLATED THERMAL STABILITY ADDITIVES FOR DISTILLATE
FUELS
TECHNICAL FIELD
This invention relates to additives for distillate fuels which reduce deposit
formation in
fuels that are thermally stressed. More specifically, the invention is
directed to a fuel additive
that comprises the reaction product of a hydrocarbyl substituted dicarboxylic
acid or derivative
thereof, a polyhydroxyl compound, and a phosphorus containing compound. This
reaction
product when added to fuels, such as jet fuels, stabilizes the fuels and
reduces or prevents the
build up of deposits in the fuel system. The invention also relates to the
inclusion of an ester,
formed by reacting a) a hydrocarbyl substituted dicarboxylic acid or
derivative thereof, with b) a
polyhydroxyl compound and a phosphorus-containing compound in a distillate
fuel to reduce the
thermal degradation of the fuel.
BACKGROUND OF THE INVENTION
When liquid hydrocarbon fuels are subjected to transportation, storage and
use, they are
exposed to thermal stress. This exposure to elevated temperatures, or thermal
stress, causes the
fuel to deteriorate. Thermal stress usually results in the formation of
sediment, sludge, or gum
and can also manifest itself visibly by a color change in the fuel.
Sediment, sludge or gum formation can cause blocking of the fuel system, or at
least
reduced performance of the fuel system. For example, in modern civil and
military jet aircraft
the fuel system is used to cool various components, such as engine parts,
prior to its combustion

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in the engine (turbine). This thermal exposure has been shown to cause the
formation of deposits
on heat exchangers, fuel lines and on the injection nozzles of the engine. It
is apparent that the
reduction or elimination of such deposits would be an advancement in the state
of the art. It is
particularly desirable to reduce deposit formation without the use of reactive
nitrogen-containing
components in the fuel which can interfere with other commonly used additives.
U.S. Patent 4,292,186 to Chibnik et al. discloses a fuel additive that is a
metal salt
complex containing a 5- or 6- membered ring. The metal complex is prepared by
forming a non-
acidic reaction product of a polyalkenyl succinic acid or anhydride and a
polyhydric alcohol or
aminoalcohol. This reaction product is then reacted with a metal salt, the
metal being selected
from Groups IB, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table. This
patent does not
suggest nor disclose a fuel additive that is derived from a polyalkenyl
succinic acid/alcohol
reaction product that is reacted with a phosphorus-containing compound.
EP288246 to Kendall teaches a composition for stabilizing fuel oil which
comprises a
phosphate compound and a carboxylic acid having from 2-20 carbon atoms. This
reference does
not disclose the fuel stabilizing additive of this invention
U.S. Patent 5,160,507 to Horodysky discloses an ester-type ashless dispersant
that
contains additional integral sulfur-ester moieties that are effective in
providing thermal stability
to fuels. This patent teaches that the sulfur-ester moieties are required for
imparting thermal and
oxidative stability to hydrocarbon fuels.
U.S. Patent 5,382,266 to Lin et al. relates to an additive that inhibits the
degradation of
fuel oils. The additive is disclosed as a phosphine or phosphate, such as
triphenylphosphite and
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triphenylphosphine. This reference does not suggest the reaction product of
the present invention
as a stabilizer for liquid hydrocarbon fuels.
U.S. Patent No. 5,596,130 to Wright et al. discloses a jet fuel additive that
is a derivative
of (thio)phosphonic acid. This patent specifically discloses the use of a
pentaerythritol ester of
polyisobutenylthiophosphonic acid in turbine combustion fuel oils to inhibit
the formation and
emission of soot and smoke from the engine. This reference makes no suggestion
or disclosure
of the use of a succinic anhydride or dicarboxylic acid to form an ester with
a polyol that is
subsequently reacted with a phosphorus-containing compound.
W096/23855 to Dillworth et al. discloses a fuel oil lubricity additive that
comprises an
ashless dispersant and a carboxylic acid. The carboxylic acid may be in the
form of an ester with
an alcohol of one or more carbon atoms. This reference does not suggest a
stabilizing additive
for jet fuel which comprises the reaction product of 1) a hydrocarbyl
substituted dicarboxylic
acid, or derivative thereof, 2) a polyhydroxyl compound, and 3) a phosphorus
containing
compound.
SUMMARY OF THE INVENTION
As a first aspect of the invention there is disclosed a novel composition of
matter. This
composition of matter comprises the reaction products of:
a) a compound of the structural formula
R-CH-C(O)R'
(I>
CH2- C (O) RZ
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wherein R is hydrocarbyl, preferably an alkyl or alkenyl group having 1 to 300
carbon
atoms, preferably 6 to 1 SO carbon atoms, more preferably 10 to 100 carbon
atoms; R' and
RZ are each independently selected from -OH, -C1, -O-lower alkyl, and when
taken
together, R' and Rz are -O-; with
b) a polyhydroxyl alcohol selected from compounds of the structural formulae:
R' - (OH)x (II)
wherein x is an integer of 2 or more, and R' is a hydrocarbyl group of 1 to 20
carbon
atoms;
HO - ((CHz)y -O)Z -H (III)
wherein y is an integer of 1 to 10 and z is an integer of I to 100;
R°
CHz-(O-CHZ CH)Y-OH
OH-CHZ-C-CHz-(O-CH,-CH)r-OH
R' (IV)
CHz-(O-CHZ-CH)~-OH
R'
wherein each R" can be independently H or -CH,; and x, y and n can each
independently
range from 1 to 20; and mixtures thereof; and
c) a phosphorus containing compound reactive with the reaction product
of a) and b).
Hydrocarbyl, as used herein and in the claims, means alkyl, alkenyl, aryl,
aralkyl, and
alkaryl and may be cyclic or polycyclic and may contain O, N, S or mixtures
thereof.
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In a preferred embodiment, R' and Rz are -0-, and thereby the compound (I) is
a succinic
anhydride of the structural formula
O
R-CH-
O
CHz-C
The mole ratio of a) to b) can range from 1:2 to 5:1, more preferably 1:2 to
3:1 and most
preferably from about 1:2 to 2:1. The molar ratio of the reaction product of
a) and b) (ester) to
the phosphorus containing compound can range from 10:1 to 1:10, with 5:1 to
1:5 being more
preferred and about 3:1 being most preferred.
The present invention also relates to the use of the physical admixture of the
ester and the
phosphorus-containing compound in a distillate fuel. For example, the ester
can be prepared as
described below and then added to a fuel that already contains a phosphorus-
containing
compound. Alternatively, the ester and the phosphorus-containing compound can
be combined
in the form of a concentrate or additive package that can be added to the
distillate fuel. Thus,
there is additionally disclosed, a fuel composition which comprises a
distillate fuel and an
additive, the additive comprising:
i) the reaction product of at least one hydrocarbyl substituted dicarboxylic
acid or
derivative thereof, with a polyhydroxyl compound; and
ii) phosphorus compound.
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EP-7467
The admixture of the ester and the phosphorus containing compound is useful in
a
method of reducing deposit formation in engines, wherein said deposit
formations are a result of
distillate fuel subjected to thermal stress. The method comprises fueling said
engine with and
operating said engine on a fuel composition comprising a distillate fuel and
an additive, the
additive comprising:
i) an ester prepared by reacting at least one hydrocarbyl substituted
dicarboxylic
acid or derivatives thereof, with a polyhydroxyl compound; and
ii) a phosphorus compound.
The two components, i) and ii), or the three-component reaction product, can
be added to
the distillate fuel by any conventional method. For example, the two
components can be added
to the distillate fuel as a single mixture containing both compounds or the
individual components
can be added separately or in any other desired combination. The additives
according to the
invention may be added either as a concentrate or as a solution using a
suitable carrier solvent,
which is compatible with the components and the distillate fuel.
Therefore, the present invention also relates to an additive fluid concentrate
for use in
distillate fuels containing at least the three-part reaction product set forth
above and/or the two
part physical admixture described above.
The present invention further relates to a jet fuel composition comprising as
a major
portion a jet fuel and as a minor portion an additive comprising the three-
part reaction product set
forth above and/or the two part physical admixture described above.
6

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The methods and additives of the instant invention effectively stabilize the
distillate fuels
during storage. The term "stabilized" as used herein, means that particulate
formation in the
distillate fuel and color deterioration of the fuel are inhibited. The term
"particulate formation"
is meant to include the formation of insoluble solids, sediment and gum.
An additional aspect of the invention is directed to a process for inhibiting
the
degradation of distillate fuels and for stabilizing fuels which comprises
adding to the distillate
fuel an effective inhibiting amount of the three part reaction product
described herein or the
admixture described herein. The invention is also directed to a method of
reducing deposit
formation in engines, the method comprises fueling the engine with, and
operating the engine on,
a fuel composition comprising a distillate fuel and an additive that is the
three-part reaction
product described herein or the admixture described herein.
The present invention is also directed to a process for inhibiting the thermal
degradation
of jet fuel which comprises adding to said jet fuel an effective amount of a
reaction product
derived from reacting a hydrocarbyl substituted dicarboxylic acid, or
derivative thereof with a
polyhydroxyl compound to create a first reaction product (the ester), and
thereafter reacting said
first reaction product with a phosphorus containing compound. This process is
also possible
using the three-component reaction product where all three components are
reacted
simultaneously or by using an admixture of the ester and the phosphorus
containing compound.
This invention also discloses a stabilized distillate fuel composition
comprising a
distillate fuel and an effective stabilizing amount of the novel composition
of matter described
herein. There is further disclosed a composition comprising a major amount of
a liquid
7

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EP-7467
hydrocarbon fuel and 0.0005 to 2% by weight of the product obtained by
reacting a hydrocarbyl
substituted dicarboxylic acid, or derivative thereof with a polyhydroxyl
compound and a
phosphorus containing compound.
DETAILED DESCRIPTION OF THE INVENTION
Subjecting distillate fuels to thermal stress tends to result in significant
deposit formation.
The function of the present invention is to reduce deposit formation anywhere
in the fuel and
exhaust systems. In jet fuel compositions, for instance, this includes
reducing deposit formation
in the fuel nozzles and spray rings, and on surfaces such as heat exchangers,
manifolds, actuators
and turbine vanes and blades. In other distillate fuel compositions, such as
diesel fuel, the
addition of the additives of the present invention serves to prevent injector
deposits and to
increase fuel stability.
Suitable phosphorus compounds for forming the additives of the present
invention
include phosphorus compounds or mixtures of phosphorus compounds capable of
introducing a
phosphorus atom into the reaction product of the polyhydroxyl compound and the
hydrocarbyl
substituted dicarboxylic acid, or derivative thereof. Any phosphorus compound,
organic or
inorganic, capable of undergoing such a reaction can be used. Accordingly, use
can be made of
inorganic phosphorus compounds such as the inorganic phosphorus acids and the
inorganic
phosphorus oxides, including their hydrates. Typical organic phosphorus
compounds include
full and partial esters of phosphorus acids, such as the mono-, di- and
triesters of phosphorus
acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid and
the
8

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tetrathiophosphoric acid; the mono-, di- and triesters of phosphorus acid ,
thiophosphorus acid,
dithiophosphorus acid and trithiophosphorus acid; the trihydrocarbyl phosphine
oxides; the
trihydrocarbyl phosphine sulfides; the mono- and dihydrocarbyl phosphonates
and their mono-,
di- and trithio analogs; the mono- and dihydrocarbyl phosphonites, and their
mono- and dithio
analogs; and the like. Thus, use can be made of such compounds as, for
example, phosphorous
acid (H3P03, sometimes depicted as HZ(HP03), and sometimes called ortho-
phosphorus acid or
phosphonic acid), phosphoric acid (H,PO4, sometimes called orthophosphoric
acid),
hypophosphoric acid (H4Pz06), metaphosphoric acid (HP03), pyrophosphoric acid
(H4Pz0,),
hypophosphorus acid (H3P02, sometimes called phosphinic acid), pyrophosphorus
acid (H4Pz05,
sometimes called pyrophosphonic acid), phosphinous acid (H3P0),
tripolyphosphoric acid
(HSP30,o), tetrapolyphosphoric acid (H6P,0,3), trimetaphosphoric acid
(H3P309), phosphorus
trioxide, phosphorus tetroxide, phosphorus pentoxide and the like. Partial or
total sulfur analogs
such as phosphorotetrathioic acid (H3PS4), phosphoromonothioic acid (H3P03S)
and
phosphorodithioic acid (H3POzSz) can also be used in forming the additives
according to this
invention.
Likewise, use can be made of organic phosphorus compounds such as mono-, di-
and
triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl
monoacid phosphates,
monohydrocarbyl diacid phosphates and mixtures thereof), mono-, di- and
triesters of
phosphorus acid (e.g., trihydrocarbyl phosphites, dihydrocarbyl hydrogen
phosphites,
hydrocarbyl diacid phosphites and mixtures thereof), esters of phosphonic
acids (both "primary"
and "secondary"), esters of phosphinic acids, phosphonyl halides,
halophosphites,

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halophosphates, tertiary pyrophosphate esters and the partial sulfur analogs
of any of the
foregoing organic phosphorus compounds and the like, wherein each hydrocarbyl
group contains
up to about 100 carbon atoms, preferably up to about 50 carbon atoms, more
preferably up to
about 24 carbon atoms and most preferably up to about 12 carbon atoms.
The hydrocarbyl substituted dicarboxylic acids, and derivatives thereof (e.g.,
acid halides,
acid esters and acid anhydrides), suitable for use in the present invention
may be compounds of
the structural formula
R-CH-C(O)R'
(1)
CH2- C (O) R~
wherein R is hydrocarbyl, preferably an alkyl or alkenyl group having 1 to 300
carbon atoms,
preferably 6 to 150 carbon atoms, more preferably 10 to 100 carbon atoms; R'
and R2 are each
independently selected from -OH, -C1, -O-lower alkyl, and when taken together,
R' and Rz are -
O-.
Preferred hydrocarbyl substituted dicarboxylic acids include hydrocarbyl
substituted
succinic anhydrides. The hydrocarbyl substituent is usually a polyolefin, and
preferably a
polyisobutylene group, having a number average molecular weight of from about
500 to 5000,
more preferably 600 to 3000 and most preferably from about 950 to about 2000.
Suitable polyhydroxyl alcohols for use in the present invention include any
compound
that contains 2 or more hydroxyl groups (-OH) and which will react with the
selected
hydrocarbyl substituted dicarboxylic acid will be useful in preparing the fuel
additives according
to the invention.

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Preferred polyhydroxyl alcohol are selected from compounds of the structural
formulae:
R' - (OH)X (II)
wherein x is an integer of 2 or more, and R' is a hydrocarbyl group of 1 to 20
carbon
atoms;
HO - ((CHz)Y -O)Z -H (III)
wherein y is an integer of 1 to 10 and z is an integer of 1 to 100;
R°
CHz-(O-CHz-CH)y-OH
OH-CHz-C-CHz-(O-CHz-CH)x-OH
R° (IV)
CHz-(O-CHz-CH)~-OH
R°
wherein each R° can be independently H or -CH3; and x, y and n can each
independently
range from 1 to 20; and mixtures thereof.
Representative compounds of the above formulae, suitable for use in the
present
invention, include alkyl diols, alkyl triols, glycols, glycerol,
pentaerythritol, tripentaerythritol,
trimethylolethane, triethylolpropane, 1,2,6-hexanetriol, sorbitol, inositol
and polyvinyl alcohol.
Pentaerythritol propoxylates and pentaerythritol ethoxylates are also useful
polyols in preparing
the additives according to the invention. The preferred polyol for use in the
present invention is
pentaerythritol.
In conducting the reaction of the hydrocarbyl substituted dicarboxylic acid
with the
polyhydroxyl compound, any temperature at which the desired reaction occurs at
a satisfactory

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reaction rate can be used. Typically the reaction is conducted in a solvent,
such as mixed xylenes
and thus an appropriate reaction temperature is the reflux temperature of the
mixture. Ordinarily,
the phosphorylation reaction (whether conducted concurrently or separately) is
conducted at
temperatures in the range of 80 to 200°C, more preferably 100 to
180°C. However, departures
from those ranges can be made whenever deemed necessary or desirable. These
reactions may
be conducted in the presence or absence of an ancillary diluent or liquid
reaction medium.
Numerous catalysts may be used to prepare the compounds of the invention, for
example,
any material that supplies a free proton may be used. Representative of such
catalysts includes
sulfuric acid, acidic ion exchange resin and hydrocarbon soluble sulfonic
acids. Base catalysts
are also useful and include the hydrocarbon soluble tertiary amines.
The additives of the present invention are used in a fuel in any amount
sufficient to
reduce the formation of deposits in the fuel and exhaust systems of an engine,
such as an internal
combustion engine or a jet engine. Preferably, the additive is used in an
amount of from about 1
to about 1000 mg per liter of fuel, more preferably in the range of from about
5 to about 200, and
most preferably from about 10 to about 100 mg per liter of fuel on an active
ingredient basis, i.e.,
excluding diluent or solvent. The preferred distillate fuels for use in the
present invention are
diesel fuels and jet fuels, more preferably, JP-8, Jet-A fuels and Jet-A1
fuels.
The inventive additives are typically added to the fuel at ambient
temperatures and
pressures. The inventive additives are preferably added to the distillate fuel
prior to any
appreciable deterioration of the fuel. However, the additives are also
effective even after some
deterioration has occurred.
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Other components which may be used with the additives of the present invention
include
ashless dispersants, antioxidants, metal deactivators, corrosion inhibitors,
conductivity improves
(e.g., static dissipators), fuel system icing inhibitors, distillate fuel
stabilizers, cetane improvers
and demulsifiers. The various additional components that can be included in
the distillate fuel
compositions of this invention are used in conventional amounts. Thus, the
amounts of such
optional components are not critical to the practice of this invention. The
amounts used in any
particular case are sufficient to provide the desired functional property to
the fuel composition.
EXAMPLE I
Preparation of Thermal Stability Additive
To a one (1) liter reaction flask fitted with a condensor, the following
materials were
added:
I) polyisobutenyl succinic anhydride (PBSA)
(molecular weight = 1050 gms/mole) 135.43 gms (0.129 moles)
2) pentaerythritol 13.77 gms (0.101 moles)
3) mixed xylenes (solvent) 75.50 gms
4) AmberlystTM 15 resin (catalyst) 1.30 gms
The mixture was heated to reflux (about 175°C) and stirred for four (4)
hours. The
mixture was filtered to remove the catalyst and the filtrate was returned to
the reaction vessel.
Diethyl phosphite (4.75 gms) (0.034 moles) was then added to the mixture. The
molar ratio of
PBSA to pentaerythritol to phosphite was thus 1.0:0.78:0.26. The mixture was
heated at reflux
for about one ( I ) hour with stirring. About 2.0 ml of water was removed by
azeotropic
distillation. The xylenes were then removed by vacuum distillation. The final
product contained
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CA 02308554 2000-08-31
0.656% by weight phosphorus. The resulting product was tested in the Hot
Liquid Process
Simulator (HLPS) described below.
HLPS Test
To evaluate the inventive additives and their effects on fuel compositions
subjected to
thermal stress, this sample and others described below were tested using the
Hot Liquid Process
Simulator (HLPS) test. In this test all additives were evaluated in a typical
Jet A fuel which is
pumped for 250 minutes at 2.0 ml per minute over a tube heated to
320°C. The weight of the
deposits which accumulate on the tube are recorded. Low deposit weight numbers
indicate an
effective additive in this test. The results for a Control (untreated fuel)
and a fuel treated with the
additive prepared in this Example are set forth in Table I below. All treat
rates are based on
active ingredients, i.e., excluding diluents or carrier fluids.
TABLE I
Sample Treat Rate IiLPS Deposit
Control 0 460 ~,g
Example I 25 mg/1 110 pg
PTS Test
:l5 Another test used in the petroleum industry to evaluate the thermal
stabilizing properties
of a fuel additive is the Pad Thermal Stability (PTS) test. Treated and
untreated samples of No. 2
diesel fuel are heated to 150°C for four (4) hours, cooled to room
temperature and then filtered
through Whatman No. 1 filter paper. White light reflectance from the filter
paper is then
*Trade-mark
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measured. A higher reflectance indicates an effective additive in this test.
The results for the
additive prepared in Example I and a Control are set out in Table
II.
TABLE II
Sample Treat Rate Reflectance (%)
(mg/liter)
Control 0 55.4
Example I 25 91.4
These two tests amply demonstrate that an additive according to the invention
is highly
effective in reducing the thermal degradation of fuels. Further, the reaction
product according to
this invention does not require nitrogen (unlike the succinimide and amine
dispersants) and will
therefore be less likely to interfere with other commonly used fuel additives
such as water
separators and coalescers.
EXAMPLE II
The procedure described in Example I was used, except that there was no
addition of
diethyl phosphite. Therefore, this Example is a control and was only the ester
between the
succinic anhydride and the pentaerythritol. Phosphorus content was zero (0).
The molar ratio of
PBSA to the pentaerythritol was 1.00:0.78.
EXAMPLE III
To a one (I) liter reaction flask, fitted with a condensor, the following
materials were
added:

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1) polyisobutenyl succinic anhydride (PBSA)
(molecular weight = 1400 gms/mole) 238.74 gms (0.171 moles)
2) pentaerythritol 17.86 gms (0.130 moles)
3) xylenes 123.28 gms
4) AmberlystT"' 15 106 gms
The mixture was heated to reflux (about 180°C) and stirred for four (4)
hours. About 2.6
ml of water generated by the reaction was removed by azeotropic distillation.
The product was
then filtered and the solvent removed by vacuum distillation. As no phosphorus
was added, this
sample would also serve as a control.
EXAMPLE IV
The following materials were added to a 2-liter re action flask fitted with a
condenser:
1) PBSA (molecular weight of about 2200 gms/mole) 312.21 gms (0.142 moles)
2) pentaerythritol 14.97 gms (0.110 moles)
3) sulfuric acid (catalyst) 4.0 drops
4) xylenes 136.0 gms
The molar ratio of the PBSA to the pentaerythritol was 1:0.77. This mixture
was heated
to reflux and stirred for four (4) hours. About 3.0 ml of water was
azeotropically removed. The
product was then filtered and solvents were removed by vacuum distillation.
This sample also
served as a control.
EXAMPLE V
Base Catalyzed
The following materials were added to a two-(2) liter reaction flask:
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1 ) polyisobutenyl succinic anhydride (PBSA)
(molecular weight = 1050 gms/mole) 576.84 gms (0.549 moles)
2) pentaerythritol 86.34 gms (0.635 moles)
3) diethyl phosphite 33.46 gms (0.242 moles)
4) N,N-dimethyl-cyclohexylamine (catalyst) 4.0 drops
5) xylenes 188.8 gms
The molar ratio of the PBSA to pentaerythritol to phosphite was I :1.16:0.44.
The
mixture was heated to reflux (about 173°C) and stirred for four (4)
hours. About 10.5 ml of
water was azeotropically removed from the reaction product which was then
filtered. The
phosphorus content of the final reaction product (without solvent) was 0.663%
by weight.
Table III sets forth various additives that were added to fuels and tested
using the HLPS
test and/or the PTS Test. In some of the testing, the ester products without
reacted phosphorus,
such as, the reaction product of Example II, were combined with free
(unreacted) sources of
phosphorus, for example, Sample Nos. 8 and 9.
1 S TABLE III
Sample Additives) Treat Phosphorus PTS* HLPS
No. Rate Concentration% Jet Fuel
(mg/liter)pg/1 Reflectancepg of deposit
1 Controls/Blanks - - 55.4 460
2 Example I 9.1 60 90.7 -
3 Example II 10.0 0 84.9 -
4 Example III 25.0 0 88.3 -
5 Example IV 25.0 0 77.8 -
6 Example V 10 66 92.6 -
7 Example V 25 165 - 60
8 Example II plus 10.0/0.2761 86.4 -
diethylphosphite (DEP)
(DEP)
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9 Example II plus 10.0/0.3861 84.8 -
dibutylphosphite (DBP)
(DBP)
1050 PBSA/sorbitol25.0 0 74.2 -
(molar ratio 1:0.88)
11 1050 25.0 164 85.8 -
PBSA/sorbitol/DEP
(molar ratio 1:0.88:0.29)
12 Example II 25.0 0 88.7 370
13 Example I 25 165 91.4 110,140*
14 Example II plus 25.0/0.73165 90.0 210
DEP (DEP)
Primene 81 R* 10.0 0 84.9 -
* *
16 Succinimide dispersant10.0 0 68.8 -
* PTS test performed in diesel fuel, 4 hours at 150°C
* * Two runs
*** Commercial diesel fuel stabilizer supplied by Rohm & Haas
5
From the data contained in Table III, it is evident that the reaction products
according to
the invention are effective fuel stabilizers. Especially preferred are the
base catalyzed products
(Example V). The lower molecular weight PBSAs for example 1050 molecular
weight (Example
10 V) are also preferred in the preparation of the fuel stabilizers according
to the invention.
The data also confirm that the reaction product of the ester (succinic
anhydride and/or
dicarboxylic acid with the alcohol) with the phosphorus containing compound is
more effective
than the physical mixture of the ester and the phosphorus compound. See Sample
Nos. 2 versus
Sample Nos. 8 or 9.
15 The HLPS results, shown in Table I, demonstrate that the additives of the
present
invention provide fuel compositions which exhibit significantly reduced
deposit formation upon
being subjected to thermal stress as compared to untreated fuel compositions.
As with the PTS
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test, the phosphorus containing reaction product is more effective than the
physical mixture of
the ester the phosphorus compound. Compare Sample No. 13 with Sample No. 14.
The exposure of distillate fuels to heat, either during transportation or when
used as a heat
sink, causes fuel to form deposits in the fuel system. This is highly
undesirable and the
petroleum industry is continually searching for additives that will reduce or
prevent the
formation of such deposits. The additives according to this invention satisfy
that need in an
effective and economical manner.
This invention is susceptible to considerable variation in its practice.
Accordingly, this
invention is not limited to the specific exemplifications set forth herein.
Rather, this invention is
within the spirit and scope of the appended claims, including any equivalents
thereof, available
as a matter of law.
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