Note: Descriptions are shown in the official language in which they were submitted.
CA 02157002 2003-06-30
PETROLEUM FUEL ANTIFOAM ADDITIVES
This invention relates to oil compositions, primarily to fuel oil
compositions, and
more especially to the control of foaming in such compositions.
In the processing and transport of hydrocarbon oils, foaming frequently occurs
as
the oil is passed from one vessel to another. The foaming may interfere with
the
pumping of the oil, and may be such as to require a reduction in pumping rate
to allow
foam collapse to avoid oil spills. It is desirable to control foaming to
permit higher rates
of oil transfer.
The problem of foaming is particularly important in the distribution of oils
such as
liquid petroleum oils, especially fuel and lubricant oils. Such oils typically
pass through a
distribution network, involving pumping through pipelines, or a series of
storage tanks.
~s
Fuel oils derived from vegetable or animal material, also known as biofuels,
are
believed to be less damaging to the environment on combustion, and are
obtained from
a renewable resource. Certain biofuels may be used as complete substitutes for
fuel oils
such as diesel fuel oils. Similarly, certain biofuels may be used as partial
substitutes for
2o such fuel oils, being blended into the oils in suitable proportions.
Biofuets ep r se have tower foaming tendencies than typical fuel oils, such as
diesel fuel oils. However, it has unfortunately now been found that blends of
a biofuel
with a diesel fuel oil have much higher foaming tendencies than the fuel oil
ep ~ se. This
2s finding is surprising since the minor components of fuel oils believed to
be responsible
for stabilisation of foam and surface-active in nature, differ from the
constituents of these
biofuels. Consequently, the addition of a quantity of biofuel to a fuel oil
was not
expected to increase the foaming tendency of the resulting blend.
3o It has now also surprisingly been found that foaming in a blend of
petroleum-
based fuel oil and a biofuel may be successfully controlled, in the sense that
the initial
foam height upon agitation is reduced, by an antifoam additive conventionally
used to
control foaming in petroleum distillate fuel oils (hereinafter referred to as
a petroleum fuel
antifoam).
Such additives are themselves surface-active in nature, and are believed to
interfere in some way with the foam-stabilising tendency of other components
of the fuel
blend.
WO 94/19430 ~ ~ , PCTIEP94/00550
~~~'~0~2 -
The invention accordingly provides, in a first aspect, a fuel oil composition
comprising a major proportion of a blend of petroleum-based fuel oil and a
biofuel and a
minor proportion of a petroleum fuel antifoam.
The petroleum fuel antifoams useful in this first aspect of the invention
include
both silicon-containing, and non silicon-containing, compositions. Where the
antifoam is
a silicon-containing composition, it has further been found that foaming in
the blend of
the first aspect may be successfully controlled, in the sense that foam
collapse is
~o accelerated, when the blend contains at most 65% by weight of a biofuel.
The invention accordingly provides, in a preferred embodiment of the first
aspect, a fuel
oil composition comprising a major proportion of a blend of petroleum-based
fuel oil and
a biofuel and a minor proportion of a petroleum fuel antifoam being a silicon-
containing
~ 5 composition, the fuel oil blend containing at most 65% by weight of a
biofuel and at least
35% by weight of a petroleum-based fuel oil.
Where the antifoam is a non-silicon containing composition, it has further
been
found that foaming in the blend of petroleum-based fuel oil and a biofuel may
be
2o successfully controlled, in the sense that foam collapse is accelerated,
where the blend
contains any proportion of biofuel.
The invention accordingly further provides, in a second preferred embodiment
of
the first aspect, a fuel oil composition comprising a major proportion of a
blend of
25 petroleum-based fuel oil and a biofuel and a minor proportion of a
petroleum fuel
antifoam being a non silicon-containing composition.
In this second preferred embodiment, the antifoam is preferably a product
obtainable by the reaction of a polyamine having at least one primary or
secondary
3o amino group and a carboxylic acylating agent. The petroleum-based fuel oil
advantageously has at least one of the following properties: a specific
gravity at 15°C of
at most 0.835, preferably at most 0.825; a kinematic viscosity at 20°C
of at most 3.10
mm2/s; an IBP of at most 175°C; an FBP of at least 370°C; and a
90%-20% of at least
125°C (the last three characteristics being measured in accordance with
ASTM D86).
Also in this second preferred embodiment, the fuel oil blend advantageously
contains at least 60% by weight, and more advantageously more than 65% by
weight, of
biofuel.
WO 94/19430 PCT/EP94/00550
~~.~~Q42
-3-
The invention also provides, in a second aspect, a concentrate comprising a
petroleum fuel antifoam in admixture with a blend of a petroleum-based fuel
oil and a
biofuel; and in a third aspect, the use of a petroleum fuel antifoam to
control foaming in a
blend of petroleum-based fuel oil and a biofuel.
The invention will hereinafter be described in more detail.
The Petroleum-Based Fuel Oil (of all aspects of the invention)
~o
The petroleum-based fuel oil is suitably a middle distillate fuel oil, i.e. a
fuel oil
obtained in refining crude oil as the fraction between the lighter kerosene
and jet fuels
fraction and the heavier fuel oil fraction. Such distillate fuel oils
generally boil within the
range of about 100°C to about 500°C (ASTM D-86), e.g.
150°C to about 400°C, for
~5 example, those having a relatively high Final Boiling Point of above
360°C, such as
380°C. The fuel oil can comprise atmospheric distillate or vacuum
distillate, or cracked
gas oil or a blend in any proportion of straight run and thermally and/or
catalytically
cracked distillates. The most common petroleum distillate fuels are kerosene,
jet fuels,
diesel fuels, heating oils and heavy fuel oils. The heating oil may be a
straight
2o atmospheric distillate, or it may contain minor amounts, e.g. up to 35 wt%,
of vacuum
gas oil or cracked gas oils or of both. Heating oils may be made of a blend of
virgin
distillate, e.g. gas oil, naphtha, etc. and cracked distillates, e.g.
catalytic cycle stock. A
representative specification for a diesel fuel includes a minimum flash point
of 38°C and
a 90% distillation point of between 282 and 380°C (see ASTM
Designations D-396 and
25 D-975).
The fuel oil may have a sulphur concentration of 1 % by weight or less based
on
the weight of the fuel. Preferably, the sulphur concentration is 0.2% by
weight or less,
more preferably 0.05% by weight or less, and most preferably 0.01 % by weight
or less.
3o The art describes methods for reducing the sulphur concentration of
hydrocarbon middle
distillate fuels, such methods including solvent extraction, sulphuric acid
treatment, and
hydrodesulphurisation.
The Biofuel (of all aspects of the invention)
The biofuel may be one or more oils derived from animal or vegetable material
or
both and capable of being utilised as a fuel.
WO 94/19430 PCT/EP94/00550
. _..
4
Oils obtained from animal or vegetable material are mainly metabolites
comprising trigylcerides of monocarboxylic acids, e.g. acids containing mainly
10-25
carbon atoms and of the form:
I I H
H- C C ~H
I
O-i -R O-i -R O-i -R
O O O
where R represents an aliphatic radical of predominantly 10-25 carbon atoms
which may
be saturated or unsaturated. Preferably, R is an aliphatic radical of 10-25
carbons.
Generally, such oils contain glycerides of a number of acids, the number and
kind
~o varying with the source of the oil, and may additionally contain
phosphoglycerides. Such
oils may be obtained by methods known in the art.
Examples of derivatives of such oils are alkyl esters, such as methyl esters,
of
fatty acids of the vegetable or animal oils. Such esters can be made by
15 transesterlfiCation.
Reference within this specification to oils that are derived from animal or
vegetable material therefore includes reference both to oils obtained from
said animal or
vegetable material or both, or to derivatives thereof.
Examples of oils derived from animal or vegetable material are rapeseed oil,
coriander oil, soyabean oil, cottonseed oil, sunflower oil, castor oil, olive
oil, peanut oil,
maize oil, almond oil, palm kernel oil, coconut oil, mustard seed oil, beef
tallow and fish
oils. Further examples include oils derived from corn, jute, sesame, shea nut,
ground nut
and linseed and may be derived therefrom by methods known in the art. Rapeseed
oil,
which is a mixture of fatty acids partially esterified with glycerol, is
preferred as it is
available in large quantifies and can be obtained in a simple way by pressing
from
rapeseed. Rapeseed oil typically contains the esters of, in addition to some
11 to 19%
C1g to C1g saturated acids, some 23 to 32% mono-, 40 to 50% di- and 4 to 12%
tri-
so unsaturated C1g to C22 acids, primarily oleic, linoleic, linolenic and
erotic acids.
As lower alkyl esters of fatty acids, consideration may be given to the
following,
for example as commercial mixtures: the ethyl, propyl, butyl and especially
methyl esters
WO 94/19430 ~ PCTIEP94/00550
-5-
of fatty acids with 12 to 22 carbon atoms, for example of lauric acid myristic
acid,
palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid,
~iefi.r~selic acid,
ricinoleic acid, elaeostearic acid, linoleic acid, linolenic acid, eicos~nmc
acid, gadoleic
acid, docosanoic acid or erucic acid, which have an iodine number from 50 to
150,
especially 90 to 125. Mixtures with particularly advantageous properties are
those which
contain mainly, i.e. to at least 50 wt% methyl esters of fatty acids with 16
to 22 carbon
atoms and 1, 2 or 3 double bonds. The preferred lower alkyl esters of fatty
acids are the
methyl esters of oleic acid, linoleic acid, linolenic acid and erucic acid.
Commercial mixtures of the stated kind are obtained for example by cleavage
and
esterification of animal and vegetable fats and oils by their
transesterification with lower
aliphatic alcohols. For production of lower alkyl esters of fatty acids it is
advantageous to
start from fats and oils with high iodine number, such as, for example,
sunflower oil,
rapeseed oil, coriander oil, castor oil, soyabean oil, cottonseed oil, peanut
oil or beef
~5 tallow. Lower alkyl esters of fatty acids based on a new variety of
rapeseed oil are
preferred.
Although many of the above oils may be used as biofuels, preferred are
vegetable oils or derivatives thereof, of which particularly preferred
biofuels are rapeseed
20 oil, cottonseed oil, soyabean oil, sunflower oil, olive oil, palm oil, or
alkyl ester derivatives
thereof, rapeseed oil methyl ester being especially preferred.
The Blend (of all aspects of the invention)
25 The proportion of biofuel in the blend may range from 0.1 % to 99.9%,
preferably
from 0.1 % to 90% and more preferably from 0.5% to 85%, by weight. Where the
antifoam is a silicon-containing composition, the proportion by biofuel is
advantageously
at most 65%, and more advantageously at most 55%, by weight. Where the
antifoam is
a non silicon-containing composition, the proportion of biofuel is
advantageously at least
30 60%, more advantageously more than 65%, by weight.
It is within the scope of the invention to use, as the blend, two or more
petroleum-
based fuel oils, or more especially two or more biofuels, in admixture with
one or more of
the other type of fuel.
The blend may contain additives other than the petroleum fuel antifoam. Thus,
one or more co-additives such as low temperature flow improvers, stabilisers,
dispersants, antioxidants, corrosion inhibitors, cetane improvers, emissions-
reducing
WO 94/19430 ri, PCTIEP94/00550
v.
agents, reodorants, lubricity agents, antistatic additives or demulsifiers may
be present in
the blend. These co-additives may be added to the blend simultaneously with
the
petroleum fuel antifoam; for example, the antifoam and co-additives may
comprise a
single additive. Alternatively, one or more co-additives may be added to the
blend
independent of the antifoam, or to the petroleum-based fuel oil or biofuel
prior to
blending.
The Petroleum Fuel Antifoam (of all aspects of the invention)
The antifoam is advantageously insoluble in the fuel being treated but is
dispersible therein to form a stable dispersion, if necessary with the aid of
a suitable
dispersant or solvent, either with or without the use of mechanical dispersing
aids.
As the antifoam there may, as indicated above, be used a silicon-containing
~s composition. Such a composition advantageously comprises a siloxane
polymer, for
example a block copolymer containing siloxane blocks and oxyalkylene blocks.
Preferred as such siloxane polymers are those of general formula (i)
Rn Si0(4-n) (i)
2 m
wherein R represents a hydrocarbyl group, n represents an integer in the range
of 1 to 3
and m represents a number >_ 2. The hydrocarbyl group may be a relatively
simple
hydrocarbyl group of from 1 to 30 carbon atoms or may be a polymeric group.
The
groups represented by R may be the same or different in any given siloxane
group or
2s throughout the siloxane polymer and the value of n in the various siloxane
groups in the
siloxane polymer may be the same or different.
The preferred polymers are block co-polymers comprising at least two blocks,
one
block comprising siloxane groups as represented by general formula (i) and the
second
so block comprising oxyalkylene groups of general formula (ii)
(R1-~) (ii) ,
The siloxane block and the oxyalkylene block may be linked to each other by
ss means of a divalent hydrocarbyl group; this may be R in general formula
(i). Hence each
siloxane block contains at least one group represented by general formula (i)
wherein at
WO 94/19430 ~ ~ PCT/EP94/00550
-7-
least one group represented by R is a divalent hydrocarbyl group. The siloxane
block
has a ratio of hydrocarbyl groups to silicon atoms of 1:1 to 3:1.
The hydrocarbyl groups that are represented by R in general formula (i) may be
alkenyl groups for example vinyl and allyl; cycloalkenyl groups, for example
cyclohexenyl; alkyl groups, for example methyl, ethyl, isopropyl, octyl and
dodecyl; aryl
groups, for example phenyl and naphthyl; aralkyl groups, for example benzyl
and
phenylethyl; alkaryl groups, for example styryl, tolyl and n-hexylphenyl; or
cycloalkyl
groups, for example cyclohexyl.
The divalent hydrocarbyl groups represented by R in general formula (i) may be
alkylene groups such as methylene, ethylene, propylene, butylene, 2,2-di-
methyl-1,3-
propylene and decylene, arylene groups such as phenylene and p,p'-diphenylene,
or
alkarylene groups such as phenylethylene. Preferably the divalent hydrocarbyl
group is
an alkylene group containing from two to four successive carbon atoms.
These divalent hydrocarbyl groups are linked to a silicon atom of the siloxane
block by a silicon-to-carbon bond and to an oxygen atom of the oxyalkylene
block by a
carbon-to-oxygen bond.
The siloxane block in the copolymers may contain siloxane groups that are
represented by general formula (i) wherein either the same hydrocarbyl groups
are
attached to the silicon atoms (e.g. the dimethylsiloxy, diphenylsiloxy and
diethylsiloxy
groups) or different hydrocarbyl groups are attached to the silicon atoms
(e.g. the
methylphenylsiloxy, phenylethylmethylsiloxy and ethylvinylsiloxy groups).
The siloxane block in the copolymers may contain one or more types of siloxane
group that are represented by general formula (i) provided that at least one
group has at
least one divalent hydrocarbyl substituent. By way of illustration only,
3o ethylenemethylsiloxy groups can be present in the siloxane block or the
siloxane block
can contain more than one type of siloxane group, e.g. the block can contain
both
ethylenemethylsiloxy groups and diphenylsiloxy groups, or the block can
contain
ethylenemethylsiloxy groups, diphenylsiloxy groups and diethylsiloxy groups.
The siloxane block may contain trifunctional siloxane groups (e.g.
monomethylsiloxane groups, CH3Si01.5), difunctional siloxane groups (e.g.
dimethylsiloxane groups, (CH3)2Si0, monofunctional siloxane groups (e.g.
trimethylsiloxane groups, (CHg)3SiOp_5) or combinations of these types of
siloxane
WO 94/19430 PCT/EP94/00550
f
-
groups having the same or different substituents. Due to the functionality of
the siloxane
groups, the siloxane block may be predominantly linear or cyclic or
crosslinked, or it may
have combinations of these structures.
s The siloxane block may contain organic end-blocking or chain-terminating
organic
groups in addition to the monofunctional siloxane chain-terminating groups
encompassed by general formula (i). Organic end-blocking groups may be
hydroxyl
groups, aryloxy groups such as phenoxy, alkoxy groups such as methoxy, ethoxy,
propoxy and butoxy, and acyloxy groups such as acetoxy.
The siloxane blocks in the copolymers contain at least two siloxane groups
that
are represented by general formula (i) (so that m represents a number >_ 2).
Preferably,
the siloxane blocks contain a total of from five to twenty siloxane groups
that are
represented by general formula (i), with m representing a number in the range
of 5 to 20.
That part of the average molecular weight of the copolymer that is
attributable to the
siloxane blocks may be as high as 50000 but preferably it is from 220 to
20000. If that
part of the average molecular weight of the copolymer that is attributable to
the siloxane
blocks exceeds 50000 or if the siloxane blocks contain a total of more than
twenty
siloxane groups that are represented by general formula (i), the copolymers
are usually
2o not as useful, e.g. they may be too viscous for convenient use in the
additives of this
invention.
The oxyalkylene blocks in the copolymers each contain at least two oxyalkylene
groups that are represented by the general formula (ii) wherein R1 is an
alkylene group.
Preferably, at least 60 per cent by weight of such groups represented by
general formula
(ii) are oxyethylene or oxypropylene groups.
Other oxyalkylene groups that are represented by general formula (ii) which
can
also be present in the oxyalkylene block, preferably in amounts not exceeding
40 per
3o cent by weight are oxy-1,4-butylene, oxy-1,5-amylene, oxy-2,2-dimethyl-1,3-
propylene,
or oxy-1,10-decylene groups.
The oxyalkylene blocks in the copolymers may contain oxyethylene or
oxypropylene groups alone or along with one or more of the various types of
oxyalkylene
groups represented by general formula (ii); the oxyalkylene blocks can contain
only
oxyethylene groups or only oxypropylene groups or both oxyethylene and
oxypropylene
groups, or other combinations of the various types of oxyalkylene groups
represented by
general formula (ii).
WO 94119430 fl ~ PCT/EP94/00550
_g_
The oxyalkylene blocks in the copolymers may contain organic end-blocking or
chain-terminating groups. Such end-blocking groups may be hydroxy groups,
aryloxy
groups such as phenoxy, alkoxy groups such as methoxy, ethoxy, propoxy and
butoxy,
and alkenyloxy groups such as vinyloxy and allyloxy. A single group can serve
as an
end-blocking group for more than one oxyalkylene block; for example, the
glyceroxy
group can serve as an end-blocking group for three oxyalkylene chains.
The oxyalkylene blocks in the copolymers contain at least two oxyalkylene
groups
~o that are represented by general formula (ii). Preferably, each block
contains from four to
thirty of such groups. That part of the average molecular weight of the
copolymer that is
attributable to the oxyalkylene blocks can vary from 176 (for (C2H40)4) to
200000, but
preferably it is from 176 to 15000. Provided that each oxyalkylene block
contains at
least two oxyalkylene groups represented by general formula (ii), the number
of
~s oxyalkylene groups and that part of the average molecular weight of the
copolymer that
is attributable to the oxyalkylene blocks is not critical, providing that the
resulting
copolymer is not rendered physically incompatible with oleaginous liquids.
However,
those copolymers in which that part of the average molecular weight that is
attributable
to the oxyalkylene blocks exceeds 200000 or that contain more than fifty
oxyalkylene
2o groups per block prove less useful, e.g. they are too viscous for
convenient use in the
additives of this invention.
The copolymers may contain siloxane blocks and oxyalkylene blocks in any
relative amounts. In order to possess desirable properties, the copolymer
should contain
25 from 5 parts by weight to 95 parts by weight of siloxane blocks and from 5
parts by
weight to 95 parts by weight of oxyalkylene blocks per 100 parts by weight of
the
copolymer. Preferably, the copolymers contain 5 parts by weight to 50 parts by
weight of
the siloxane blocks and from 50 parts by weight to 95 parts by weight of the
oxyalkylene
blocks per 100 parts by weight of the copolymer.
The copolymers may contain more than one of each of the blocks and the blocks
may be arranged in various configurations such as linear, cyclic or branched
configurations.
The most preferred block co-polymers have the general formula (iii)
WO 94/19430 PCTIEP94/00550
-1°-
. t., ; ,, ..
R
c
(iii)
Si-0~~~
m
R3 (0_R4 )p OR5
wherein p represents an integer >_ 2 and preferably represents an integer in
the range of
4 to 30, c represents an integer in the range of 0 to 2, m represents an
integer z 2, R2
represents a monovalent hydrocarbyl radical of 1 to 12 carbon atoms preferably
a linear
aliphatic radical for example a methyl or ethyl group, R3 represents a
divalent
hydrocarbyl radical of 1 to 12 carbon atoms preferably an alkylene group of at
least two
carbon atoms for example ethylene, 1,3-propylene or 1,4-butylene, R4
represents the
same or different divalent hydrocarbyl radicals of 2 to 10 carbon atoms such
as for
1o example ethylene, 1,3-propylene or 1,6-hexylene, and R5 represents a
monovalent
hydrocarbyl group of 1 to 12 carbon atoms or an end-group such as for example
hydroxyl or hydrogen. It is preferred that R4 represents different hydrocarbyl
radicals
and most preferably represents a mixture of at least one of each of ethylene
and
1,3-propylene radicals.
The above-described block.copolymers may be produced by an addition reaction
between siloxanes containing silicon-bonded hydrogen atoms and oxyalkylene
polymers
containing alkenyl end-blocking groups in the presence of a platinum catalyst.
These
copolymers can also be prepared by a metathesis reaction between siloxanes
containing
2o silicon-bonded chloro-organo groups and an alkaline metal salt of a hydroxy
end-blocked
oxyalkylene polymer.
As the antifoam there may, alternatively, be used a non-silicon containing
composition comprising a product obtainable by the reaction between:
(a) a polyamine of the formula (iv)
H N~(A) N~(B) (C) (iv)
2 H ~H ~NH2
x Y
WO 94/19430 ~ PCT/EP94/00550
-11-
wherein A, B, C are the same or different and each represents a hydrocarbylene
group,
and x and y are integers whose sum is in the range of 0 to 10, and
(b) a carboxylic acylating agent.
Advantageously, the sum of x and y is in the range from 1 to 10. More
advantageously, the sum of x and y is not more than 8, preferably not more
than 6, more
preferably not more than 4 and most preferably not more than 2.
1o As used in this specification the term "hydrocarbyl" refers to a group
having a
carbon atom directly attached to the rest of the molecule and having a
hydrocarbon or
predominantly hydrocarbon character. Among these, there may be mentioned
hydrocarbon groups, including aliphatic (e.g. alkyl or alkenyl), alicyclic
(e.g. cycloalkyl or
cycloalkenyl), aromatic, aliphatic and alicyclic-substituted aromatic, and
aromatic-
substituted aliphatic and alicyclic groups. Aliphatic groups are
advantageously
saturated. Unsubstituted hydrocarbyl groups are prefer-ed; however, if desired
such
groups may carry further hydrocarbyl groups as substituents. Such groups may
also
contain non-hydrocarbon substituents provided their presence does not alter
the
predominantly hydrocarbon character of the group, examples include keto, halo,
2o hydroxy, vitro, cyano, alkoxy and hydroxyalkyl. If the hydrocarbyl group is
substituted, a
single (mono) substituent is prefer-ed. Examples of substituted hydrocarbyl
groups
include 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-ketopropyl,
ethoxyethyl, and
propoxypropyl. The groups may also or alternatively contain atoms other than
carbon in
a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms
include, for
2s example, nitrogen, sulfur, and, preferably oxygen. Advantageously, each
hydrocarbyl
group contains at most 10, preferably at most 8, more preferably at most 6 and
most
preferably at most 4, carbon atoms.
The term 'hydrocarbylene' is used analogously.
In a preferred embodiment of the non-silicon antifoam, the polyamine reactant
is
an alkylene diamine, or polyalkylene polyamine of the above formula where A, B
and C
are each alkylene groups containing up to 10, preferably at most 8, more
preferably at
most 6 and most preferably at most 4, carbon atoms. Thus the polyamine
reactants
preferred in the present invention include simple diamines, for example
ethylene
diamine, propylene diamine, butylene diamine and pentylene diamine;
polyalkylene
polyamines for example diethylene triamine, triethylene diamine, tetraethylene
WO 94!19430 PCT/EP94/00550
-12-
pentamine, pentaethylene hexamine, di(methylethylene)triamine, dibutylene
triamine,
tributylene tetramine and dipentylene hexamine.
t, ,,
The alkylene groups constituting A, B and C may optionally be substituted by
one
or more hydrocarbyl groups as hereinbefore described. In a more highly
preferred
embodiment, A, B and C are alkylene groups containing 1 to 3 carbon atoms,
optionally
substituted by one or more alkyl, alkenyl, alkoxy or hydroxyalkyl groups with
hydroxyalkyl
groups being most preferred. Most highly preferred embodiments of the
polyamines
suitable as reactant (a) include ethylene diamine and diethylene triamine.
~o
The polyamine reactant may comprise a mixture of polyamines, each component
being a polyamine having the aforesaid general formula (iv). Of such mixtures,
those
comprising alkylene diamines and polyalkylene pofyamines are preferred, such
amines
being optionally substituted by one or more hydrocarbyl groups. More preferred
are
~5 mixtures comprising alkylene diamines and polyalkylene polyamines wherein
said
alkylene groups contain 1-3 carbon atoms, optionally substituted by one or
more alkyl,
alkenyl, alkoxy or hydroxyalkyl groups. Most highly-preferred mixtures of
polyamines
include mixtures of ethylene diamine, diethylene triamine.
2o The carboxylic acylating agents useful as reactant (b) contain one or more
carboxylic acylating groups, and a hydrocarbyl group sufficient to impart
hydrocarbon
solubility to the molecule. Suitable carboxylic acylating groups include
carboxylic acid
groups and derivatives thereof possessing a leaving group, i.e. a group
capable of being
displaced during reaction. Examples of such carboxylic derivatives include
esters,
25 anhydrides and acyl halides including acyl chlorides, acyl bromides and
acyl iodides,
although other carboxylic derivatives known in the art as acylating agents may
be used
to equal effect.
More preferred carboxylic acylating agents are monocarboxylic acylating agents
so of the formula (v):
R6 COX (v)
where R6 represents a hydrocarbyl group, and where X represents a leaving
35 group. Such preferred agents include fatty acid compositions, such as
naturally-
occurring fatty acids and derivatives of same. Preferably, such fatty acids or
derivatives
contain from 8 to 40, more preferably 10 to 30, even more preferably 12 to 24,
and most
preferably 12 to 18 carbon atoms. In such fatty acid compositions, R8 is
preferably
WO 94/19430 PCT/EP94/00550
-13-
straight or branched-chain alkyl or alkenyl. Most preferred fatty acids
include those
selected from the group comprising lauric, myristic, palmitic, stearic, oleic,
cekanoic and
corn-fatty acids, the last four acids or mixtures thereof being most
preferred.
The preferred fatty acid compositions may also comprise mixtures of fatty
acids,
having an average carbon number within the preferred ranges hereinbefore
described.
Such specifically-preferred mixtures include mixtures of the above fatty
acids, and
naturally-originating mixtures such as coco-fatty acid fraction and cekanoic
acid (a
mixture of iso-C13 fatty acids). Mixtures of naturally-originating fatty acids
with the other
~o fatty acids described above are also preferred.
The products of reaction may be of mixed composition. Thus, the product may
comprise a mixture of simple amides, di- and higher poly-amides, imides and/or
amidine
reaction products where the nature of reactants (a) and (b) and the ratio in
which they
~5 are combined permits such reactions to take place. Their definition in
terms of reaction
products thus describes most conveniently the range of possible compositions
obtained
in accordance with this invention.
Reaction conditions suitable for generating the above reaction products are
for
2o example known in the art for promoting the acylation of polyamines. Thus,
the reaction
may be carried out by mixing the reactants (a) and (b), optionally combined in
the
presence of a mutual co-solvent, and heating the mixture sufficiently to cause
reaction to
occur, without raising the temperature above the decomposition temperature of
the
reactants or product. Alternatively, reactant (a) may be heated to reaction
temperature
2s and reactant (b) added over an extended period. Suitable temperatures are
typically
between 100°C and 300°C, the exact temperature being determined
by the nature of the
selected reactants. Examples of the preparation of products according to this
invention
are found in US 4,394,135, and EP 147,240, to which further attention is
directed.
3o A further class of non-silicon antifoams in accordance with this invention
are
those obtainable by the reaction of the carboxylic acylating agent (b) as
hereinbefore
described with one or more polyamines (a) of the general formula (vi)
vi
R7 ~(A) N~(B) (C) ~ )
HN ~H N ~ NHR8
H
x Y
WO 94/19430 PCT/EP94/00550
~~.~~~~2
-14-
wherein A, B and C are as hereinbefore defined and herein R7 and R8 maybe the
same
or different and each represents hydrogen or a ,hydrocarbyl group, provided
that both R7
and R8 are not hydrogen, and x and y are infegers whose sum is in the range
from 0 to
10.
In a preferred embodiment, the polyamine reactant is a terminal N-substituted
or
terminal N,N'-disubstituted polyamine of the formula {vi) wherein A, B and C
are each
alkylene groups containing up to 10, preferably at most 8, more preferably at
most 6 and
~o most preferably at most 4, carbon atoms. Thus these polyamine reactants
include
terminal N-substituted or terminal N,N'-disubstituted derivatives of simple
diamines such
as ethylene diamine, propylene diamine, butylene diamine and pentylene
diamine, and
terminal N-substituted, or terminal N,N'-disubstituted derivatives of
polyalkylene
polyamines such as diethylene triamine, triethylene diamine, tetraethylene
pentamine,
pentaethylene hexamine, di(methylethylene)triamine, dibutylene triamine,
tributylene
tetramine and dipentylene hexamine.
In a more preferred embodiment, R7 and R8 of the polyamine reactant each
independently represent hydrogen or an aliphatic hydrocarbyl group. This
aliphatic
2o hydrocarbyl group is preferably a straight or branched chain alkyl,
oxyalkyl or
hydroxyalkyl group. Most preferably, it is a hydroxyalkyl group, for example a
2-
hydroxyethyl group.
Particularly preferred amines are those in which one of R7 and R8 is hydrogen.
2s Also advantageously, the sum of x and y in the polyamine is not more than
8, preferably
not more than 6, more preferably not more than 4 and most preferably not more
than 2.
The polyamine reactant may comprise a mixture of polyamines, each component
being a polyamine having the aforesaid general formula. Of such mixtures,
those
so comprising terminal N-substituted or terminal N,N'-disubstituted alkylene
diamines, and
terminal N-substituted or terminal N,N'-disubstituted polyalkylene polyamines
are
preferred, such amines being optionally substituted by one or more hydrocarbyl
groups.
Most preferred are mixtures comprising alkylene diamines and polyalkylene
polyamines
wherein said alkylene groups contain 1-3 carbon atoms, optionally substituted
by one or
s~ more alkyl, alkenyl, alkoxy or hydroxyalkyl groups.
The polyamine reactant may also comprise a mixture of polyamines of the
formula (iv) in combination with a mixture of polyamines of the formula (vi).
WO 94/19430 PCT/EP94/00550
-15-
The degree of acylation of polyamine (a) is generally dictated by the number
of
primary and secondary nitrogens present within the polyamine, i.e. the number
of
possible acylation sites, the proportions in which reactants (a) and (b) are
mixed, and the
time allowed for reaction. The product may be formed by the reaction of one
mole of
polyamine with at least one mole of the carboxylic acylating agent.
Preferably, the
product is formed by the reaction of one mole of polyamine with at least two
moles of the
carboxylic acylating agent. More preferably, the product is formed by the full
acylation of
the polyamine by the carboxylic acylating agent. Within this specification,
the term'fulf
1o acylation is used to define reactions where every amino group on the
polyamine has
undergone a condensation reaction upon addition of acylating agent (b). Thus,
under
'full' acylation, each polyamine amino group will react to evolve one
equivalent of water,
irrespective of the exact nature of the condensation reaction which occurs
with the
acylating agent (b).
Particularly preferred embodiments of the non silicon-containing antifoam are
those in which the product may be obtained by the reaction between one mole of
the
polyamine of the formula (iv) or (vi) as hereinbefore defined with at least
two moles of
the monocarboxylic acylating agent of the formula (v) also hereinbefore
defined. Most
2o advantageous are those products which may be obtained by the full acylation
of said
polyamine by said acylating agent.
In accordance with all aspects of the invention, the concentration of the
antifoam
in the fuel oil composition may for example be in the range of 0.1 to 10,000
ppm,
preferably 0.5 to 5000 ppm and most preferably 1 to 100 ppm (active
ingredient) by
weight per weight of fuel oil. Particularly advantageous concentrations are in
the range
of 1 to 20 ppm.
Concentrate
Concentrates are convenient as a means for incorporating the antifoam into the
bulk fuel blend. Incorporation may be by methods known in the art. The
concentrates
may also contain co-additives as required and as hereinbefore described and
preferably
contain from 3 to 75 wt%, more preferably 3 to 60 wt%, most preferably 10 to
50 wt% of
the additives preferably in solution in oil. Examples of carrier liquids are
organic solvents
including hydrocarbon solvents, for example petroleum fractions such as
naphtha,
kerosene, diesel and heater oil; aromatic hydrocarbons such as aromatic
fractions, e.g.
those sold under the 'SOLVESSO' trade name; and paraffinic hydrocarbons such
as
WO 94/19430 PCT/EP94/00550
-16-
hexane and pentane and isoparaffins. The carrier liquid must, of course, be
selected
having regard to its compatibility with the additives and with the fuel blend.
In accordance with the second aspect~of the invention, suitable as such a
carrier
liquid is the fuel blend into the bulk of whictl.,the concentrate will be
incorporated.
,, g ..
The antifoam may be incorporated into the bulk fuel blend by other methods
such
as those known in the art. Co-additives may be incorporated into the bulk fuel
blend at
the same time as the antifoam or at a different time.
The invention will now be illustrated by way of example only as follows:
Fuels used in the examples
Two petroleum-based fuel oils and a biofuel, having the characteristics shown
in
Table 1, were used in the following examples of the invention. Both fuel oils
were diesel
fuels whilst the biofuel was rapeseed methyl ester.
Table 1
Fuel Characteristics Fuel Oil Fuel Oil Biofuel
A B
Densit , /ml, 15C 0.82 0.85 0.88
Viscosit , 20C, mm2/s 3.09 4.7 7.22
ASTM-D86 Distillation:
(C)
IBP 168 188
20% 203 230
90% 330 329
FBP 371 362
90-20 127 90
90-FBP 41 33
Cloud Point, C LS.O. 3015 -3 -5 -4
CFPP, C E.N. 116 -5 -4 -14
Examples of Antifoams useful in the invention
(i) Non silicon-containing compositions:-
WO 94/19430 ~ PCTlEP94/00550
-17-
Example 1
Oleic acid (282 g; 1.0 moles) was dissolved in toluene (250 mls). Diethylene
triamine (DETA) (34.3 g; 0.33 moles) was dissolved in toluene (100 mls), the
slight
s stoichiometric excess of DETA being used to ensure subsequent acylation of
every
amino-group. The amine solution was added slowly to the stir-ed solution of
the acid
over one hour. During this addition there was an exotherm and the reaction
temperature
increased by 13°C. When the addition of the amine was complete, the
reaction mixture
was heated to reflux for 7 hours and 45 minutes. During the reflux water (17
mls; theory
~o = 18 mls) was collected in a Dean & Stark trap. At the end of the reflux
the toluene was
removed by distilling the reaction mixture to a pot temperature of
150°C. Final traces of
solvent were removed from the product by applying a vacuum of 500 mm Hg.
The product obtained was a waxy solid. The IR spectrum of the product showed
~s no trace of oleic acid (peak at 1711 wavenumbers). There were, however,
peaks at
1665 and 1590 wavenumbers consistent with the formation of secondary and
tertiary
amine groups, i.e. that acylation had been essentially full.
Examples 2 and 3
Analogous reaction conditions were employed to generate the fully-acylated
reaction products as illustrated in Table 2 below.
Table 2
Reactants
Ex. (a) polyamine (b) monocarboxylicRatio
of
No. ac latin a ent a:b used
2 H2N~ N~ N ~NH2 oleic acid slightly
H greater
than 1:4
3 H tall-oil fatty slightly
acid
H2N ~ N ~NH2 greater
than 1:3
WO 94/19430 ~ ~ PCT/EP94/00550
_~g_
Examples 4 and 5
. E.. .. ;, ~:
Reaction conditions analogous to those used for the synthesis of the previous
examples 1-3 were employed in the reaction of one mole of diethylene triamine
with two
s moles of monocarboxylic acylating agent, as shown in Table 3.
Table 3
Reactants
Example (a) polyamine (b) monocarboxylic
No.
ac latin a ent
H
H2N %~~ N ~~NH2 stearic acid
tall-oil fatty acid
In both examples, the major product was of the form
H R
N N ~N
O
R
where the acylating agent (b) corresponds to RCOOH, i.e. still a fully-
acylated product
~5 within the meaning of this specification, every amino group of the
polyamine having
undergone reaction upon addition of acylating agent (b) and three moles of
water per
mole of DETA having been evolved.
Examples 6 to 14
Reaction conditions analogous to those used for the synthesis of Examples 1-3
were employed to generate the products illustrated in Table 4 below.
WO 94/19430 PCT/EP94/00550
-19-
Table 4
Reactants
Example No. (a) polyamine (b) monocarboxylic
ac latin a ent
6 H2N~,/ NH2 stearic acid
7 - " - oleic acid
8 - " - cekanoic acid
9 - " - coco fatty acid
- " - tall-oil fatty acid
11 - " - 1:1 mixture of coco
and
tall-oil fatt acids
12 H coco fatty acids
HO ~\~ N i!~NH2
13 - " - cekanoic acid
14 - " - stearic acid
In each example, one mole of polyamine was reacted with slightly in excess of
two moles of acylating agent.
(ii) Silicon-containing compositions:-
~o Antifoam A - a proprietary block copolymer comprising siloxane blocks and
oxyalkylene
blocks, and of the general class hereinbefore described. Antifoam A is sold
commercially for the treatment of middle distillate fuel oils.
WO 94/19430 ~ ~ PCT/EP94/00550
-20-
Example of the Invention:
1
The fuel oil compositions defined in Table 5 were prepared by a conventional
laboratory blending technique, using a WARING blender. The foaming tendency of
each
blend of biofuel and petroleum-based fuel oil was measured following addition
of
antifoam example 4 or antifoam A, using a test procedure involving the
agitation by hand
of 100 ml of test fuel oil in a previously-cleaned and dried 4 oz bottle, the
bottle then
being placed in normal attitude on a stationary, flat surface. The subsequent
length of
~o time (in seconds) over which the foam generated by shaking collapsed
sufficiently to
reveal a clear area of liquid surtace was recorded as one measure of foaming
tendency,
longer foam collapse times indicating greater foam stability.
As indicated by the results in Table 5, the non silicon-containing antifoam
~5 significantly reduced foam collapse time in all blends comprising fuel oil
A, and in those
blends comprising fuel oil B and at least 60% of biofuel (by wt.)
The silicon-containing antifoam significantly reduced foam collapse time in
all
blends comprising fuel oil A and at most 60% of biofuel (by wt.), and in all
blends
2o comprising fuel oil B and at most 70% of biofuel (by wt.) These results
suggest the
silicon-containing antifoam to be generally effective in fuel oil blends
comprising at most
about 65% biofuel (by wt.).
The foaming tendency of each blend in Table 5 was also measured in terms of
25 the initial foam height obtained upon agitation. In Table 5, the foam
height of each
antifoam-containing fuel oil composition is shown (in parentheses) as a
percentage of
the foam height of the corresponding untreated blend.
The blend foam height results show that initial foam height is generally
reduced
3o upon addition of a petroleum fuel antifoam.
WO 94!19430 PCT/EP94/00550
21
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