U.S. patent application number 12/471594 was filed with the patent office on 2009-09-17 for method and use for the prevention of fuel injector deposits.
Invention is credited to Angela Priscilla Breakspear, Rinaldo Caprotti, Russell Martin Thompson.
Application Number | 20090229176 12/471594 |
Document ID | / |
Family ID | 37594134 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090229176 |
Kind Code |
A1 |
Breakspear; Angela Priscilla ;
et al. |
September 17, 2009 |
Method and Use for the Prevention of Fuel Injector Deposits
Abstract
A method of substantially removing, or reducing the occurrence
of, injector deposits in a diesel engine operated using a diesel
fuel containing a minor amount of a metal-containing species is
disclosed. The method includes adding to a diesel fuel the reaction
product between a hydrocarbyl-substituted succinic acid or
anhydride and hydrazine. The diesel engine is equipped with fuel
injectors having a plurality of spray-holes, each spray-hole having
an inlet and an outlet, and the fuel injectors have one or more of
the following characteristics: (i) spray-holes which are tapered
such that the inlet diameter of the spray-holes is greater than the
outlet diameter; (ii) spray-holes having an outlet diameter of 0.10
mm or less; (iii) spray-holes where an inner edge of the inlet is
rounded; (iv) 6 or more spray-holes; (v) an operating tip
temperature in excess of 250.degree. C.
Inventors: |
Breakspear; Angela Priscilla;
(Wiltshire, GB) ; Caprotti; Rinaldo; (Oxford,
GB) ; Thompson; Russell Martin; (Oxon, GB) |
Correspondence
Address: |
INFINEUM USA L.P.
P.O. BOX 710
LINDEN
NJ
07036
US
|
Family ID: |
37594134 |
Appl. No.: |
12/471594 |
Filed: |
May 26, 2009 |
Current U.S.
Class: |
44/418 |
Current CPC
Class: |
C10L 1/226 20130101;
C10L 10/04 20130101; F02M 65/008 20130101; F02M 2200/06 20130101;
C10L 1/2381 20130101; C10L 10/02 20130101; C10L 10/18 20130101;
C10L 1/221 20130101; C07D 259/00 20130101; C07D 207/323 20130101;
F02M 43/00 20130101; C10L 1/2383 20130101; C10L 10/06 20130101 |
Class at
Publication: |
44/418 |
International
Class: |
C10L 1/22 20060101
C10L001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2006 |
EP |
06118488.3 |
Claims
1. A diesel fuel composition comprising a major amount of a diesel
fuel and a minor amount of the reaction product between a
hydrocarbyl-substituted succinic acid or anhydride and hydrazine,
wherein at least 25% by weight of the reaction product has a
molecular weight which is more than 2 times the average molecular
weight of the hydrocarbyl group of the hydrocarbyl-substituted
succinic acid or anhydride.
2. A diesel fuel composition according to claim 1 wherein the
reaction product between the hydrocarbyl-substituted succinic acid
or anhydride is predominantly an oligomeric species of the
structure: ##STR00009## where R' represents the hydrocarbyl
substituent and where n is an integer and greater than 1,
preferably between 2 and 10, more preferably between 2 and 7, for
example 3, 4 or 5.
3. A diesel fuel composition according to claim 1 wherein the
hydrocarbyl group of the hydrocarbyl-substituted succinic acid or
anhydride comprises a C.sub.8-C.sub.36 group or a polyisobutylene
group with a number average molecular weight of between 200 and
2500.
4. A diesel fuel composition according to claim 1 wherein the
hydrocarbyl-substituted succinic acid or anhydride and hydrazine
are reacted in a molar ratio of 2:1-1:4, preferably, 1:1-1:3.
5. A diesel fuel composition according to claim 1 wherein the
reaction product between the hydrocarbyl-substituted succinic acid
or anhydride and hydrazine is present in the diesel fuel in an
amount between 10 and 500 ppm by weight based on the weight of the
fuel.
Description
[0001] This invention relates to a method for the removal or
prevention of fuel injector deposits in diesel engines, in
particular to the removal or prevention of fuel injector deposits
in modern diesel engines. Uses of reaction products to remove or
prevent fuel injector deposits and processes for the production of
diesel fuel detergents are described.
[0002] There is continued legislative pressure to reduce emissions
from diesel engines. In Europe by 2008, all new diesel engines must
comply with the Euro V specification. This has resulted in the
development of advanced fuel injection equipment characterised by
fuel injectors which have complex spray-hole geometries, multiple
and narrow spray-holes and which operate with high temperatures and
pressures at the injector tips. As a consequence of this increasing
severity in operating conditions, the injectors of modern
common-rail diesel engines are prone to the formation of deposits.
These deposits, which are found both inside and outside the
spray-holes of the injector nozzles, contribute directly to loss in
engine power and increase in smoke production.
[0003] The formation of deposits on diesel fuel injectors is not a
new phenomenon and historically any problem has been adequately
addressed by the use of conventional diesel detergent additives. It
has been observed however, that the types of deposits formed under
the more severe operating conditions of engines which are being
developed to be Euro V compliant are not adequately removed or
prevented by conventional diesel detergent additives. Although not
wishing to be bound by any theory, it is presently thought that the
formation of injector deposits in modern engines is exacerbated by
the presence of minor amounts of metal-containing species in the
fuel. Indeed, the Applicant's studies have indicated that the use
of fuels with negligible amounts of metal-containing contamination
do not result in any significant problems with deposits. However,
normal diesel fuels will often contain low but measurable amounts
of metal-containing contamination, for example, zinc, copper, iron
and lead, and metal-containing species may also be deliberately
added to perform other functions. Analysis of the deposits formed
in modern diesel engines indicates that, in addition to the
expected carbonaceous materials, metals such as zinc and copper can
be detected. The present invention specifically addresses the
removal and prevention of these new types of injector deposits.
[0004] U.S. Pat. No. 3,375,092 discloses the product of the
reaction between an alkyl succinic acid or anhydride in which the
alkyl radical has from 8 to 24 carbon with a hydrazine. This
product is said to be useful as an anti-icing additive for
gasoline.
[0005] U.S. Pat. No. 2,640,005 discloses succinhydrazides which are
formed for example, by the reaction of hydrazine or hydrazine
hydrate with the anhydride of a substituted succinic acid. These
species are taught as having utility as fungicides.
[0006] U.S. Pat. No. 3,723,460 discloses that the species formed by
the reaction of e.g. polyisobutenyl-substituted succinic acid or
anhydride with hydrazine can be used as fuel and motor oil
additives. The intermediate reaction products are preferably
post-reacted with further compounds for example, those with
displaceable halogens, alkylene oxides etc., but may also be used
alone. The species are discussed as being of sufficient detergent
strength to clean and maintain clean, a gasoline engine induction
system but not of sufficient detergent strength to promote the
formation of gasoline-in-water emulsions. They are also able to
function as a carburetor cleaner. There is no disclosure of use in
diesel engine systems.
[0007] WO 2004/029183 discloses ashless anti-wear, anti-fatigue and
extreme pressure additives for lubricating oils. These have the
formula:
##STR00001##
[0008] where group R.sup.1 may be e.g. alkyl and groups R.sup.2-4
may be hydrogen or similar to R.sup.1. The additives are prepared
by reacting e.g. an alkyl succinic anhydride with hydrazine
hydrate.
[0009] EP 0 632 123 A1 relates to diesel fuel compositions
containing nitrogen-containing dispersants. The dispersant may be
chosen from a very wide range of possible species, including those
derived from hydrazines. The dispersants are characterised in that
the numerical value obtained by multiplying the percentage of
nitrogen in the dispersant by the weight average molecular weight
of the dispersant is between 45,000 and 100,000.
[0010] In accordance with a first aspect, the present invention
provides a method of substantially removing, or reducing the
occurrence of, injector deposits in a diesel engine operated using
a diesel fuel containing a minor amount of a metal-containing
species, the method comprising adding to the diesel fuel the
reaction product between a hydrocarbyl-substituted succinic acid or
anhydride and hydrazine, wherein the diesel engine is equipped with
fuel injectors having a plurality of spray-holes, each spray-hole
having an inlet and an outlet, and wherein the fuel injectors have
one or more of the following characteristics: [0011] (i)
spray-holes which are tapered such that the inlet diameter of the
spray-holes is greater than the outlet diameter; [0012] (ii)
spray-holes having an outlet diameter of 0.10 mm or less; [0013]
(iii) spray-holes where an inner edge of the inlet is rounded;
[0014] (iv) 6 or more spray-holes; [0015] (v) an operating tip
temperature in excess of 250.degree. C.
[0016] In accordance with a second aspect, the present invention
provides the use of the reaction product between a hydrocarbyl
substituted succinic acid or anhydride and hydrazine to
substantially remove, or reduce the occurrence of, injector
deposits in a diesel engine, the diesel engine being equipped with
fuel injectors having one or more of characteristics (i) to (v) as
defined in relation to the first aspect and operated using a diesel
fuel containing a minor amount of a metal-containing species.
[0017] In accordance with a third aspect, the present invention
provides a process for producing a diesel fuel detergent effective
to substantially remove, or reduce the occurrence of, injector
deposition in diesel engine, the diesel engine being equipped with
fuel injectors having one or more of characteristics (i) to (v) as
defined in relation to the first aspect and operated using a diesel
fuel containing a minor amount of a metal-containing species, the
process comprising reacting in a solvent, at least one
hydrocarbyl-substituted succinic acid or anhydride with hydrazine;
refluxing the resulting reaction mixture to complete the reaction,
and; raising the temperature of the reaction mixture to at least
120.degree. C., preferably at least 180.degree. C., under reduced
pressure and for at least 30 minutes, preferably at least one
hour.
[0018] It has been found that the reaction products used in the
first and second aspects, and produced by the process of the third
aspect, are particularly effective at reducing the incidence of
deposits in modern diesel engine fuel injectors, and much more
effective than the widely used PIBSA-PAM detergents under similar
conditions. It was surprising to note however that in older type
diesel engines, such as those used in the industry standard XUD-9
detergency test, the reaction products of use in the present
invention were outperformed by conventional PIBSA-PAM
detergents.
[0019] As discussed above, the incidence of injector deposits
appears to be connected to the presence of metal-containing species
in the fuel. Some diesel fuels will contain no measurable metal
content, in which case the incidence of injector deposits will be
reduced. However, the presence or absence of metal-containing
species in diesel fuels is generally not apparent to the user and
will vary with fuel production, even with fuels from the same
supplier. The present invention is thus useful in those instances
where metal-containing species are present and also as a
preventative measure to lessen the impact of injector deposits when
re-fuelling with a fuel of unknown metal content.
[0020] In the context of all aspects of the present invention,
substantial removal of injector deposits should be taken to mean
that deposits which may be present on the inside or outside of the
spray-holes of the injector nozzles are removed to the extent that
the proper functioning of the injector is not significantly
impaired. This may be determined for example by measuring increases
in exhaust smoke or loss in engine torque. It is not required that
all traces of injector deposit are removed. Similarly, a reduction
in the occurrence of injector deposits does not require that no
deposits whatsoever are formed, only again that the amount of any
deposit which may form is not sufficient to significantly impair
the proper functioning of the injector.
[0021] It is presently thought that the characteristics (i) to (v)
of the fuel injectors all contribute to the formation of injector
deposits. It has been observed that diesel engines employing fuel
injectors which have a plurality of these characteristics are more
prone to deposit formation. Thus in embodiments of the invention,
the fuel injectors have two, preferably three, more preferably
four, most preferably all five of characteristics (i) to (v).
[0022] In a preferred embodiment, the fuel injectors have at least
characteristics (i) and (ii). In a more preferred embodiment, the
fuel injectors have at least characteristics (i), (ii) and (iii).
In an even more preferred embodiment, the fuel injectors have at
least characteristics (i), (ii), (iii) and (iv).
[0023] The reaction between the hydrocarbyl-substituted succinic
acid or anhydride and hydrazine produces a mixture of reaction
products (as discussed hereinbelow). This mixture is made up from
species which have a range of molecular weights. These range from
low molecular weight species, being composed of one moiety of
hydrocarbyl-substituted succinic acid or anhydride and one or two
moieties of hydrazine, to species composed of more than one moiety
of hydrocarbyl-substituted succinic acid or anhydride and one or
more moieties of hydrazine. These latter species have relatively
higher molecular weights than the former. It has been observed that
most effective detergency is obtained by employing a reaction
product which contains a significant proportion of higher molecular
weight species. Accordingly, it is advantageous that at least 25%,
preferably at least 50%, most preferably at least 80% by weight of
the reaction product between the hydrocarbyl-substituted succinic
acid or anhydride and hydrazine has a molecular weight which is
more than 2 times, preferably more than 2.5 times, the average
molecular weight of the hydrocarbyl group of the
hydrocarbyl-substituted succinic acid or anhydride.
[0024] Expressed in terms of EP 0 632 123 A1 discussed above,
preferably, the reaction product of the present invention is such
that the numerical value obtained by multiplying the percentage of
nitrogen in the product by the weight average molecular weight of
the product is in excess of 105,000, more preferably in excess of
110,000, for example between 110,000 and 250,000.
[0025] The various features of the invention, which are applicable
to all aspects will now be described in more detail.
[0026] (a) The Reaction Product
[0027] This comprises the product of the reaction between a
hydrocarbyl-substituted succinic acid or anhydride and
hydrazine.
[0028] (i) Hydrocarbyl-Substituted Succinic Acid or Anhydride.
[0029] 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. They may be saturated or unsaturated, linear or
branched. Preferably, the hydrocarbyl groups are hydrocarbon
groups. These groups may contain non-hydrocarbon substituents
provided their presence does not alter the predominantly
hydrocarbon character of the group. Examples include keto, halo,
nitro, cyano, alkoxy and acyl. The groups may also or alternatively
contain atoms other than carbon in a chain otherwise composed of
carbon atoms. Suitable hetero atoms include, for example, nitrogen,
sulphur, and oxygen. Advantageously, the hydrocarbyl groups are
alkyl groups.
[0030] Preferably, the hydrocarbyl group of the
hydrocarbyl-substituted succinic acid or anhydride comprises a
C.sub.8-C.sub.36 group, preferably a C.sub.8-C.sub.18 group.
Non-limiting examples include dodecyl, hexadecyl and octadecyl.
Alternatively, the hydrocarbyl group may be a polyisobutylene group
with a number average molecular weight of between 200 and 2500,
preferably between 800 and 1200. Mixtures of species with different
length hydrocarbyl groups are also suitable, e.g. a mixture of
C.sub.16-C.sub.18 groups.
[0031] The hydrocarbyl group is attached to a succinic acid or
anhydride moiety using methods known in the art. Additionally, or
alternatively, suitable hydrocarbyl-substituted succinic acids or
anhydrides are commercially available e.g. dodecylsuccinic
anhydride (DDSA), hexadecylsuccinic anhydride (HDSA),
octadecylsuccinic anhydride (ODSA) and polyisobutylsuccinic
anhydride (PIBSA).
[0032] (ii) Hydrazine
[0033] Hydrazine has the formula:
NH.sub.2--NH.sub.2
[0034] Hydrazine may be hydrated or non-hydrated. Hydrazine
monohydrate is preferred.
[0035] (iii) Reaction of (i) and (ii)
[0036] The reaction between the hydrocarbyl-substituted succinic
acid or anhydride and hydrazine produces a variety of products. As
noted above, it is preferable for good detergency that the reaction
product contains a significant proportion of species with
relatively high molecular weight. The precise nature of the species
produced in the reaction has not yet been fully elucidated however,
it is presently thought that a major high molecular weight product
of the reaction is an oligomeric species predominantly of the
structure:
##STR00002##
[0037] where n is an integer and greater than 1, preferably between
2 and 10, more preferably between 2 and 7, for example 3, 4 or 5.
Each end of the oligomer may be capped by one or more of a variety
of groups. Some possible examples of these terminal groups
include:
##STR00003##
[0038] Alternatively, the oligomeric species may form a ring having
no terminal groups:
##STR00004##
[0039] Also thought to be present is a species of the
structure:
##STR00005##
[0040] where R' represents the hydrocarbyl substituent. It should
be noted that it is also within the scope of the present invention
to use more than one hydrocarbyl-substituted succinic acid or
anhydride in which case the groups R' in the above structures may
be different from one another.
[0041] Both of the above structures contain at least two moieties
derived from the hydrocarbyl-substituted succinic acid or
anhydride. The molecular weights of these species are thus more
than twice the average molecular weight of the hydrocarbyl
substituent R'. In the context of the present invention the species
are thus of relatively high molecular weight.
[0042] As lower molecular weight reaction products, species of the
following structures are also thought to be present:
##STR00006##
[0043] Further possible minor products include:
##STR00007##
[0044] There may also be some salt formation resulting in species
of the following structures:
##STR00008##
[0045] The general synthesis of the reaction products used in the
present invention has been described in the art, for example, U.S.
Pat. No. 3,375,092, U.S. Pat. No. 2,640,005 and U.S. Pat. No.
3,723,460 cited hereinabove. A range of possible reaction schemes
and products has also been given by Feuer et al., in Jn. Amer.
Chem. Soc, 73 (1951) pp. 4716-4719. By way of example a possible
preparative route is as follows.
[0046] A charge of alkyl-substituted succinic anhydride together
with an equal weight of solvent, e.g. toluene is heated to ca.
50.degree. C. under nitrogen. The desired amount of hydrazine
hydrate is added drop-wise causing an exotherm. Once addition is
complete, the reaction mixture is heated to reflux for several
hours. The mixture is then water/solvent stripped and the
temperature raised to 180.degree. C. under reduced pressure.
[0047] Preferably, the hydrocarbyl-substituted succinic acid or
anhydride and hydrazine are reacted in a molar ratio of between 2:1
and 1:4, more preferably between 1:1-1:3.
[0048] Preferably, the reaction product between the
hydrocarbyl-substituted succinic acid or anhydride and hydrazine is
added to the diesel fuel in an amount of between 10 and 500 ppm by
weight, based on the weight of the fuel, more preferably between 20
and 100 ppm.
[0049] (b) The Diesel Fuel
[0050] Preferably, the diesel fuel is a petroleum-based fuel oil,
especially a middle distillate fuel oil. Such distillate fuel oils
generally boil within the range of from 110.degree. C. to
500.degree. C., e.g. 150.degree. C. to 400.degree. C. The fuel oil
may comprise atmospheric distillate or vacuum distillate, cracked
gas oil, or a blend in any proportion of straight run and thermally
and/or refinery streams such as catalytically cracked and
hydro-cracked distillates.
[0051] Other examples of diesel fuels include Fischer-Tropsch
fuels. Fischer-Tropsch fuels, also known as FT fuels, include those
described as gas-to-liquid (GTL) fuels, biomass-to-liquid (BTL)
fuels and coal conversion fuels. To make such fuels, syngas
(CO+H.sub.2) is first generated and then converted to normal
paraffins by a Fischer-Tropsch process. The normal paraffins may
then be modified by processes such as catalytic cracking/reforming
or isomerisation, hydrocracking and hydroisomerisation to yield a
variety of hydrocarbons such as iso-paraffins, cyclo-paraffins and
aromatic compounds. The resulting FT fuel can be used as such or in
combination with other fuel components and fuel types. Also
suitable are diesel fuels derived from plant or animal sources such
as FAME. These may be used alone or in combination with other types
of fuel.
[0052] Preferably, the diesel fuel has a sulphur content of at most
0.05% by weight, more preferably of at most 0.035% by weight,
especially of at most 0.015%. Fuels with even lower levels of
sulphur are also suitable such as, fuels with less than 50 ppm
sulphur by weight, preferably less than 20 ppm, for example 10 ppm
or less.
[0053] As discussed herein, the Applicants have observed that the
problems associated with the formation of injector deposits in
engines being developed to be Euro V compliant are associated with
the presence of metal-containing species in the diesel fuel.
Commonly when present, metal-containing species will be present as
a contaminant, for example through the corrosion of metal and metal
oxide surfaces by acidic species present in the fuel. In use, fuels
such as diesel fuels routinely come into contact with metal
surfaces for example, in vehicle fuelling systems, fuel tanks, fuel
transportation means etc. Typically, metal-containing contamination
will comprise metals such as zinc, iron, copper and lead.
[0054] In addition to metal-containing contamination which may
present in diesel fuels there are circumstances where
metal-containing species may deliberately be added to the fuel. For
example, as is known in the art, metal-containing fuel-borne
catalyst species may be added to aid with the regeneration of
particulate traps. Such catalysts are often based on metals such as
iron, cerium, Group I and Group II metals e.g., calcium and
strontium, either as mixtures or alone. Also used are platinum and
manganese. The presence of such catalysts may also give rise to
injector deposits when the fuels are used in engines being
developed to be Euro V compliant.
[0055] Metal-containing contamination, depending on its source, may
be in the form of insoluble particulates or soluble compounds or
complexes. Metal-containing fuel-borne catalysts are often soluble
compounds or complexes or colloidal species. It will be understood
that metal-containing species in the context of the present
invention include both species which are metallic and those where
the metal constituent is in compounded form.
[0056] In an embodiment, the metal-containing species comprises a
fuel-borne catalyst.
[0057] In a preferred embodiment, the metal-containing species
comprises zinc.
[0058] Typically, the amount of metal-containing species in the
diesel fuel, expressed in terms of the total weight of metal in the
species, is between 0.1 and 50 ppm by weight, for example between
0.1 and 10 ppm by weight, based on the weight of the diesel
fuel.
[0059] (c) Fuel Injector Characteristics
[0060] Historically, diesel engine fuel injectors have been simple
in design. In recent years, the connection between injector design
and engine performance has become better understood. For example,
the knowledge that a fine distribution of fuel droplets promotes a
decrease in emissions has led to a gradual narrowing of fuel
injector spray-holes and increased injector pressures. As mentioned
hereinabove, the drive to meet the upcoming Euro V emissions
specification has led to further advances in fuel injector
design.
[0061] (i) Tapered Spray-Holes
[0062] The majority of fuel injectors have spray-holes which are
uniform in cross-section. In the present invention, preferably the
spray-holes are tapered such that diameter at the point where the
fuel enters the spray-hole (the inlet) is greater than the diameter
at the point where the fuel exits the spray-hole (the outlet). Most
typically, the spray-holes will be conical or frusto-conical in
shape.
[0063] (ii) Spray-Hole Diameter
[0064] The spray-holes preferably have an outlet diameter of 0.10
mm or less, more preferably 0.08 mm or less. This may be compared
to injectors of 10 to 15 years ago which had spray-holes of
typically 0.25 mm.
[0065] (iii) Rounded Spray-Holes
[0066] In the context of the present invention, rounded spray-holes
are those where the inner edge of the inlet of the hole has been
formed, smoothed or eroded to have a curved or radial profile,
rather than an angled profile.
[0067] (iv) Multiple Spray-Holes
[0068] Historically, fuel injectors have had up to four
spray-holes. The present invention relates to fuel injectors
preferably having 6 or more spray-holes, for example 6, 7, 8, 9, 10
or more. It is anticipated that future designs of fuel injectors
will have even more spray-holes.
[0069] (v) Operating Tip Temperature
[0070] The combination of lower fuel flow due to a large number of
spray-holes, higher fuel pressures and complex spray-hole geometry
leads to increased injector tip temperatures. Typically, the fuel
injectors will have an operating tip temperature in excess of
250.degree. C., preferably in excess of 300.degree. C. It will be
understood that the operating tip temperature of the fuel injectors
refers to the temperature of the injector tip during normal running
of the diesel engine. Those skilled in the art will be aware of
methodologies to measure the injector tip temperature, for example
by the use of suitably placed thermocouples.
[0071] Characteristics (i) to (iv) result in a less turbulent fuel
flow through the injector. Whilst this is generally advantageous,
it lessens the possibility for the fuel to physically erode any
deposits which may be present. The increase in operating tip
temperature is also thought to contribute to the formation of
deposits.
[0072] It has also been observed that the reaction products which
are the subject of the present invention are effective to improve
the lubricity of low sulphur-content diesel fuels. The reaction
product of dodecyl-substituted succinic anhydride and hydrazine was
found to be particularly effective in this regard.
[0073] The invention will now be described by way of example
only.
[0074] Preparative Routes
EXAMPLE 1
[0075] Dodecylsuccinic anhydride (200 g, 0.75 mol) was weighed into
a 11, three neck, round-bottom flask together with toluene (200 g).
Under nitrogen and with stirring, the temperature was raised to ca.
50.degree. C. and hydrazine monohydrate (37.59 g, 0.75 mol) added
dropwise. Once addition was complete, the mixture was heated to
reflux for 5 hours. Toluene was removed at 40.degree. C. until no
more bubbling was seen and then the product was held for 1 hour at
0 mbar and 40.degree. C.
[0076] The product produced in the reaction contained around 10% by
weight of species having a molecular weight more than 2 times the
molecular weight of the hydrocarbyl group of the dodecylsuccinic
anhydride reactant.
EXAMPLE 2
[0077] Dodecylsuccinic anhydride (200 g, 0.75 mol) was weighed into
a 11, three neck, round-bottom flask together with toluene (200 g).
Under nitrogen and with stirring, the temperature was raised to ca.
50.degree. C. and hydrazine monohydrate (112.76 g, 2.25 mol) added
dropwise. Once addition was complete, the mixture was heated to
reflux for 5 hours. Toluene was removed at 40.degree. C. until no
more bubbling was seen and then the product was held for 4 hours at
0 mbar and 180.degree. C.
[0078] The product produced in the reaction contained around 70% by
weight of species having a molecular weight more than 2 times the
molecular weight of the hydrocarbyl group of the dodecylsuccinic
anhydride reactant.
EXAMPLE 3
[0079] A further example using dodecylsuccinic anhydride in a
synthesis similar to Example 2 produced a product containing around
84% by weight of species having a molecular weight more than 2
times the molecular weight of the hydrocarbyl group of the
dodecylsuccinic anhydride reactant.
[0080] Effect of Process Variables
[0081] Example 2 was repeated varying the temperature and pressure
of the final stage following the removal of toluene. Table 1 below
shows the effect of these variables on the molecular weight
distribution of the products obtained. In the Table, high MW
species are those having a molecular weight more than 2 times the
molecular weight of the hydrocarbyl group of the dodecylsuccinic
anhydride reactant.
TABLE-US-00001 TABLE 1 Temperature/.degree. C. Pressure/mbar % of
high MW species 40 35 20 60 35 15 80 35 17 100 35 18 120 35 25 140
35 33 160 35 46 180 35 62 180 0 76
[0082] Following the routes of Examples 1 and 2, further species
were prepared by reacting hydrazine mono-hydrate with a
C.sub.2-4-alkyl succinic anhydride and a
polyisobutylene-substituted succinic anhydride (mol weight of PIB
ca. 1000).
[0083] Test Protocol
[0084] The protocol used is described by Graupner et al. "Injector
deposit test for modern diesel engines", Technische Akademie
Esslingen, 5th International Colloquium, 12-13 Jan. 2005, 3.10, p
157, Edited by Wilfried J. Bartz. Briefly, the protocol aims to
replicate the operating conditions in a modern diesel engine with
an emphasis on the fuel injector tip. The test is split into five
stages: [0085] a) an iso-speed measurement of engine power output
[0086] b) an 8 hour endurance run [0087] c) an extended soaking
period (3 to 8 hours) during which the engine is stopped and
allowed to cool [0088] d) a second 8 hour endurance run [0089] e)
an iso-speed measurement of engine power output.
[0090] For the data presented herein, the five stages above were
used however, stages b), c) and d) can be repeated any number of
times to suit the testing programme being undertaken. Also, stages
a) and e) may be omitted but are useful to improve understanding of
the results. Results are reported as the difference between the
average torque at the start of the test during stage a) and the
average torque at the end of the test during stage e).
Alternatively, if the isospeed procedure is not run, the measured
difference between starting torque at full load/full speed and
final load/speed can be used. Differences in smoke production are
also noted. The formation of injector deposits will have a negative
influence on the final power output and will increase the amount of
smoke observed. The injectors used had the physical characteristics
(i)-(v) described above.
[0091] To replicate the conditions expected in a modern diesel
engine, a small amount of metal contamination in the form of zinc
neodecanoate was added to the fuel used to run the engine.
[0092] The fuel used was a low-sulphur content diesel fuel with the
characteristics shown in Table 2 below.
TABLE-US-00002 TABLE 2 Test description Value Units sulphur content
0.0005 mass % cetane number 55.4 -- density @ 15.degree. C. 844.9
kgm.sup.-3 distillation characteristics D5% 204.8 .degree. C. D10%
211.6 .degree. C. D20% 222.2 .degree. C. D30% 232.2 .degree. C.
D40% 242.1 .degree. C. D50% 252.3 .degree. C. D60% 262.8 .degree.
C. D70% 275.1 .degree. C. D80% 290.5 .degree. C. D90% 315.1
.degree. C. D95% 337.1 .degree. C. FBP 353.6 .degree. C. IBP 179.7
.degree. C. kinematic viscosity @ 20.degree. C. 3.935 cSt kinematic
viscosity @ 40.degree. C. - D445 cloud point -14.0 .degree. C. CFPP
-33.0 .degree. C.
[0093] For comparative purposes, the species of the invention were
tested in the industry standard XUD9 detergency test. A commercial
PIBSA-PAM detergent was tested also. The results are given in Table
3 below.
TABLE-US-00003 TABLE 3 Needle lift in Species Treat rate wppm
(active ingredient) XUD9 Untreated fuel -- 92 PIBSA-PAM 30 57
PIBSA-PAM 60 53 PIBSA-PAM 100 8 PIBSA-PAM 279 14 Example 1 60 83
Example 2 60 83 Example 3 60 93 PIB1000 hydrazide 60 77 C.sub.24-SA
hydrazide 60 78 Example 2 300 83 PIB1000 hydrazide 300 76
[0094] These results show that the commercial PIBSA-PAM detergent
gave the expected excellent performance in the XUD-9 test.
Contrastingly, the hydrazine species performed poorly, even at high
treat rates.
[0095] The species were then tested using the test protocol
described above. Results are given in Table 4 below. 3 ppm of Zn in
the form of zinc neodecanoate was added to the fuel for all tests
(except for the untreated fuel alone).
TABLE-US-00004 TABLE 4 Treat rate wppm Species (active ingredient)
Torque loss Untreated fuel -- 43% Untreated fuel + 3 ppm Zn --
17.2% PIBSA-PAM 60 13.7% PIB1000 hydrazide 60 9.7% C.sub.24-SA
hydrazide 60 7.1% Example 1 60 12.0% Example 2 60 5.2%
[0096] Table 5 below shows a further result for the product of
Example 3.
TABLE-US-00005 TABLE 5 Treat rate wppm Species (active ingredient)
Torque loss Untreated fuel -- 1.3% Untreated fuel + 3 ppm Zn --
10.0% PIBSA-PAM 60 9.2% Example 3 60 0.9%
[0097] The results show that the addition of zinc to the untreated
fuel gives rise to a large increase in torque loss. The commercial
PIBSA-PAM detergent only gave a marginal improvement. All hydrazine
species provided a greater improvement than the commercial
detergent. Particularly good performance was obtained for the
species of Example 2 and Example 3 which both contained a high
proportion of the higher molecular weight species.
[0098] The results in Table 6 below also illustrate the effect of
the molecular weight distribution of the species on torque loss.
Again, all tests contained 3 ppm of Zn in the form of zinc
neodecanoate. The species used were the products of the reaction
between dodecylsuccinic anhydride and hydrazine mono-hydrate
following the routes of Examples 1 and 2 above and were present in
the fuel at 60 wppm.
TABLE-US-00006 TABLE 6 % of high MW species Torque loss 90.0 0.1%
73.4 4.2% 72.0 5.2% 70.0 5.2% 10.0 12.0%
[0099] These results confirm the increased effectiveness of the
materials which contain the highest percentage of higher molecular
weight species.
* * * * *