Note: Descriptions are shown in the official language in which they were submitted.
CA 02429289 2003-05-22
ESSENTIALLY HYDROCARBON COMPOSITIONS TO BE USED AS FUELS
WITH ENHANCED LUBRICATING PROPERTIES
The present invention relates to an essentially hydro-
carbon composition having enhanced lubricating properties.
More specifically, the present invention relates to a
hydrocarbon composition which can be used as a fuel, espe-
cially for Diesel--type engines, which has surprisingly en-
hance lubricating properties with respect to the single
original components, and maintains however a high cetane
number and a reduced presence of aromatics.
Fuels for Diesel engines are characterized by various
properties associated both with their performances in the
combustion phase and also with their cold flow properties
and lubrication. In particular, it is important for the ca-
pacity of Diesel fuel to maintain lubricating properties
which significantly reduce the wear of the mechanical parts
involved in fluid transfer, such as pumps, valves and in-
jectors. These lubricating properties are usually measured
by means of specific empirical methods well known to ex-
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CA 02429289 2003-05-22
perts in the field, such as the indication of the so-called
lubricity according to the HFRR method (regulation CEC-F-
06-A-96), to which reference is made hereunder in the pre-
sent description.
The increasingly restrictive regulations on the char-
acteristics of fuels for injection engines and turbines
(Jet Fuel) generally aim at reducing the quantity of aro-
matic compounds and sulfur in order to maintain exhausted
gas emissions within limits which are becoming stricter and
stricter from an environmental point of view. One of the
most commonly used methods for allowing a Diesel fuel to
fall within these limits consists in effecting a more or
less extensive hydrogenation thereof, which however has the
disadvantage of significantly reducing its lubricating
properties.
It is also known that certain mixtures of hydrocarbons
within the distillation range of typical gas oil cuts for
Diesel engines, i.e. comprised within 230 and 370 C, ob-
tained starting from syn-gas according to a synthesis proc-
ess of the Fischer-Tropsch type, followed by a hydrogenat-
ing-isomerizing treatment, have excellent combustion and
cold flow properties, with a cetane number normally higher
than 60 and up to values of 80 or over, and pour points
lower than -30 C.
Processes of the Fischer-Tropsch type (hereafter indi-
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CA 02429289 2003-05-22
cated with the usual abbreviation F.T.) are known to be
processes which allow gaseous mixtures containing hydrogen
and carbon monoxide in ratios varying from 2/1 to 4/1 (syn-
gas) to be converted into liquid or solid mixtures of es-
sentially linear hydrocarbons, sometimes partially oxygen-
ated. In addition to the process set up in its different
modifications by Fischer and Tropsch in the 30s', all
analogous processes which apply the same principle are in-
cluded in the definition of F.T. processes, i.e. in general
the direct synthesis of organic hydrocarbon or oxygenated
products starting from suitable mixtures of hydrogen and
carbon monoxide, in the presence of appropriate catalysts,
specifically called F.T. catalysts.
Typical F.T. catalysts for obtaining prevalently par-
affinic products with medium-high distillation ranges are
based on cobalt or iron, generally supported on inert ox-
ides such as alumina, silica and their mixtures. The mo-
lecular weight distribution in these liquid mixtures ex-
tends to a range of values which vary according to the
catalyst and process conditions.
The paraffinic products obtained from the Fischer-
Tropsch synthesis reactor are subsequently subjected to hy-
drogenating and/or isomerizing treatment (hydro-
isomerization, hydrotreating, hydrocracking) in the pres-
ence of suitable catalysts, followed by fractionation by
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CA 02429289 2003-05-22
distillation to obtain fuel cuts within the desired range,
usually medium distillates, i.e. gas oil and/or kerosene,
commonly called Diesel Fuel and Jet Fuel.
These cuts (or fractions) deriving from F.T. processes
therefore usually consist of mixtures of essentially paraf-
finic hydrocarbons, with distillation ranges (according to
the publications) from 150-180 to 230-250 for Jet Fuel and
from 230-260 to 360-380 for Diesel, wherein from 60 to 90%
of the molecules have prevalently methyl branchings. Possi-
ble unsaturations or oxygenated groups, typically present
in a quantity ranging from 5 to 10% by weight in the
Fischer-Tropsch synthesis product, are normally removed
during the treatment with hydrogen mentioned above.
The Diesel and/or Jet Fuel fractions obtained by the
hydrocracking of F.T. waxes, under suitable conditions, as
described, for example. in patent publications EP-A 1101813
and U.S. 6310108, have excellent properties at low tempera-
tures. Furthermore, due to the lack of sulfurated, nitro-
genated and aromatic compounds, the medium distillates ob-
tained by the hydrocracking of F.T. paraffins have an ex-
cellent performance with respect to their environmental im-
pact, as specified, for example, in the article of Ref.
T.W. Ryan "Emission performance of Fischer-Tropsch Diesel
Fuel", Proceedings of the Conference on Gas Liquids Proc-
essing '99, 17-19 May, 1999, S.Antonio, Texas. In the case
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CA 02429289 2003-05-22
of Diesel, the high hydrogen content produces lower flash
points and consequently a lower emission of NO,,. The lack
of aromatic and sulfurated compounds, moreover, leads to a
drastic reduction in particulate emissions and facilitates
the post-treatment of the gases discharged.
The lubricity of these mixtures or fractions is, on
the contrary, normally unsatisfactory with values higher
than 500 (measured according to the above HFRR method) far
beyond the requisites of the regulations currently in
force, which require values at least lower than 460.
The addition of certain additives to gas oil fraction
or kerosene in order to increase the lubricating capacity,
is also known. This technique is used both for traditional
refinery fuels and also for those obtained by means of F.T.
processes. Although satisfactory results have been obtained
in terms of lubricity, the use of these additives causes a
significant increase in the cost of the fuel, especially
considering the necessity for selecting products essen-
tially not containing sulfur or nitrogen. Furthermore, con-
siderable corrosion phenomena on some parts of the engines
fed with fuels containing these additives, have been ob-
served after a period of time.
Diesel cuts deriving from F.T., which can be used as
blending stocks suitable for improving the combustible
properties and having high lubricating properties, are de-
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CA 02429289 2003-05-22
scribed in U.S. patent 5,689,031. These hydrocarbon mix-
tures comprise a significant portion of oxygenated com-
pounds and are obtained by means of a complex process which
includes the separation of a fraction which is not sub-
jected to hydrogenating treatment and subsequently joined
to the remaining fraction subjected to hydro-isomerization.
Although the diesel cut thus obtained has improved lubri-
cating properties, its low temperature properties are not
entirely satisfactory, and a costly and complex process is
also required for its production.
There is consequently still a great request for im-
proving the quality of fuels in so-called medium distillate
cuts, and especially gas oil, in order to reduce the emis-
sions of NO,, and particulate in the discharge gases, at the
same time maintaining good lubricating and cold flow prop-
erties and reducing the production costs.
The Applicant has now surprisingly found that by add-
ing small quantities of a synthetic cut essentially without
organic oxygen, deriving from a synthesis process of the
Fischer-Tropsch type, to a traditional refinery medium dis-
tillate, especially gas oil, it is possible to obtain a
combustible hydrocarbon composition having a higher lubri-
cating capacity than that obtained from each of the origi-
nal components, and also, with respect to the medium dis-
tillate, a much higher cetane number and an improved qual-
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CA 02429289 2010-04-01
ity of the combustion emissions of an engine fed therewith.
A first object of the present invention therefore relates to a hydrocarbon
composition which can be used as fuel for diesel or turbine engines, wherein
at least
80% by weight, preferably 90% by weight., of said composition has a range of
temperatures of distillation (hereinafter called "distillation range")
comprised within
150 and 380 C, and consists of a mixture of the following components:
A) from 85 to 98% by weight with respect to the overall weight of (A) and (B)
of
any refinery hydrocarbon mixture, having a distillation range comprises within
150 and 380 C,
B) from 2 to 15% by weight with respect to the overall weight of (A) and (B)
of a
hydrocarbon mixture essentially without oxygenated organic compounds,
obtained by means of a process comprising a synthesis reaction of the
Fischer-Tropsch type, having a distillation range comprised within 130 and
380 C, preferably comprised within 150 and 370 C, at least 50% of said
component (B) consisting of branched paraffins.
Further objects of the present invention will be evident from the following
description and examples.
In order to clarify the description and claims of the present patent
application
and specify its relative scope, the meaning of some of the terms used herein
is
defined below.-
- the term "distillation range", referring to a mixture of
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CA 02429289 2003-05-22
hydrocarbons, means, unless otherwise specified, the
temperature or range of temperatures at the head of a
typical distillation column from which said mixture is
collected, at normal pressure (0.1009 MPa);
- the definitions of the ranges always comprise the ex-
tremes, unless otherwise specified;
- the term "hydrocracking'{, as used herein with reference
to any mixture or essentially hydrocarbon composition,
generally means treatment with hydrogen of said mixture
or composition, in the presence of a suitable catalyst,
in order to obtain a product with a lower boiling point
or range;
- the terms "oxygen content", referring to a prevalently
hydrocarbon mixture or composition (hydrocarbons > 700
by weight), and "oxygenated", with reference to an or-
ganic compound, always refer to organic oxygen, i.e.
bound to at least one carbon atom, therefore excluding
any reference to water or other inorganic compounds con-
taining oxygen;
- the term "refinery", as used herein referring to compo-
sitions or mixtures of combustible hydrocarbons, gener-
ally indicates compositions obtained from organic raw
materials, especially of a mineral origin, by means of
processing with transformation and purification proc-
esses typical of refineries, such as (hydro) cracking,
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CA 02429289 2003-05-22
reforming, hydrogenation, desulfuration, dewaxing, isom-
erization, distillation.
the term "distillation range comprised within two given
temperatures", with reference to compositions and mix-
tures mentioned in the present invention and claims,
comprises all distillation ranges whose extremes are in-
cluded within the two given temperatures. For example,
limited to the definition of distillation range, a com-
position typically suitable as Diesel fuel, having a
distillation range from 240 to 360 C, is included in the
definition of compositions whose distillation range is
comprised within 150 and 380 C.
Component (A) of the present composition can consist
of any refinery hydrocarbon mixture having the characteris-
tics specified above. Among these, those most suitable for
use as fuels for engines are preferred, even though mix-
tures suitable for other uses are not excluded from the
scope of the present invention. Hydrocarbon mixtures having
a distillation range comprised within 200 to 370 C, par-
ticularly any non-synthetic gas oil fraction ranging from
240 to 360 C, are especially preferred.
Said mixtures of component (A) generally consist of
aliphatic, naphthene and aromatic hydrocarbons with varying
structures and isomerization degrees, prevalently having a
number of carbon atoms greater than 8 and up to about 30.
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Compounds containing hetero-atoms such as S, 0, N, can also
be present to a varying extent.
Refinery distillates containing the minimum possible
quantity of hetero-atoms are however particularly suitable
for the present invention, in accordance with the increas-
ingly strict regulations aimed at reducing problems relat-
ing to the environmental impact of fuels. Medium distil-
lates, and in particular gas oils, having an S content
lower than 1000 ppm, preferably lower than 100 ppm, are
particularly preferred. The lubricating properties of these
products, in fact, progressively deteriorate with a de-
crease in the sulfur content, and have lubricity values
corresponding to average diameters higher than 460 m meas-
ured with the above HFRR method.
Typical but non-limiting examples of essentially hy-
drocarbon mixtures or fractions which can be used as compo-
nent (A) in the compositions of the present invention are,
for example, gas oil and kerosene from primary distilla-
tion, gas oil and kerosene from desulfuration processes,
gas oil from hydrocracking, gas oil from catalytic dewax-
ing.
Component (B) according to the present invention con-
sists of a hydrocarbon mixture essentially without aromatic
compounds and sulfur, and whose content of oxygenated com-
pounds is lower than the minimum level which can be de-
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CA 02429289 2003-05-22
tected with the usual analytic methods, such as IR or NMR
spectroscopy and gas-mass spectrometry. Said hydrocarbon
mixture essentially consists of a mixture of linear and
branched paraffins and is obtained by subjecting the prod-
uct of an F.T. synthesis or a part thereof, to hydrogenat-
ing/isomerization treatment.
As already mentioned above, the latter product is usu-
ally characterized by a substantial absence of sulfur and
preferably consists of over 70t by weight of linear paraf-
fins having more than 15 carbon atoms. F.T. products are
frequently solid or semi-solid at room temperature and for
this reason are called waxes. Not all F.T. synthesis proc-
esses provide high-boiling mixtures of linear paraffins.
Depending on the conditions used and the catalyst, the
Fischer-Tropsch process can produce mixtures having differ-
ent distillation temperature ranges, also relatively low if
desired. It has proved to be more convenient however to
carry out the process so as to prevalently obtain high-
boiling mixtures or waxes, which can then be suitably de-
graded ad fractionated into the desired distillation cuts.
It is also known that F.T. processes produce hydrocar-
bon mixtures containing oxygenated hydrocarbons, normally
in the form of alcohols, whose content can generally reach
a maximum of 10t by weight with respect to the total.
If the F.T. process is carried out in the presence of
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CA 02429289 2003-05-22
catalysts based on cobalt, these oxygenated compounds
mainly consist of alcohols with a linear chain, but can
also comprise acids, esters and aldehydes in much lower
concentrations (The Fischer Tropsch and Related Syntheses,
H.H. Storch, N. Golumbic, R.B. Anderson, John Wiley & Sons,
Inc., N.Y. 1951). It is generally known in the art that
these oxygenated compounds are prevalently. concentrated in
the low-boiling fraction of a typical mixture obtained from
the Fischer-Tropsch synthesis, whereas the fraction with a
boiling point higher than 300 C, preferably higher than
370 C, has a content of organic oxygen not higher than 0.1%
(expressed as weight of oxygen with respect to the total
weight of the fraction).
In relation to the characteristics of the F.T. prod-
uct, there are various kinds of hydrogenating treatment
suitable for producing a hydrocarbon mixture which can be
used as component (B). If the distillation range of the
F.T. product is from 150 to 380 C, preferably from 240 to
370 C, the hydrogenating treatment is such as to hydrogen-
ate the unsaturated and oxygenated groups, but not signifi-
cantly reduce the average molecular weight. Experts in the
field can decide whether to also apply a hydrogenat-
ing/isomerizing treatment according to what is known in the
art, in order to give satisfactory low temperature proper-
ties, either as a subsequent step to the hydrogenation of
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CA 02429289 2003-05-22
the oxygenated groups, or contemporaneously with this in
the presence of suitable hybrid catalysts, i.e. containing
both hydrogenating functions (supported noble metals), and
isomerizing functions (acid sites).
When, on the other hand, the F.T. product comprises
significant parts of waxy high-boiling products, it is
typically subjected to an upgrading process comprising one
or more hydrocracking steps, optionally preceded by a hy-
drogenation step. As is known, a hydrocracking step is car-
ried out in the presence of a bifunctional catalyst, con-
taining a metal with a hydro-dehydrogenating activity sup-
ported on an inorganic solid comprising at least one oxide
or silicate with acid characteristics.
Hydrocracking catalysts typically comprise metals of
groups 6 to 10 of the periodic table of elements (in the
form approved by IUPAC and published by "CRC Press Inc." in
1989, to which reference will be made hereunder), espe-
cially nickel, cobalt, molybdenum, tungsten or noble metals
such as palladium or platinum. Whereas the former are more
suitable for processing hydrocarbon mixtures with rela-
tively high sulfur contents, noble metals are more active,
but are poisoned by sulfur and other hetero-atoms and are
therefore particularly suitable for processing hydrocarbon
mixtures of the type obtained by means of F.T.
Carriers which can normally be used for the purpose
13 -
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are various types of zeolites (13, Y), X-A1203 (wherein X
can be Cl or F), silico-aluminas, the latter being amor-
phous or with varying degrees of crystallinity, or mixtures
of crystalline zeolites and amorphous oxides. For greater
details on the various catalysts, specific characteristics
and different hydrocracking processes based thereon, refer-
ence should be made, among the numerous publications avail-
able in literature, to the publication of J.Scherzer and
A.J. Gruia "Hydrocracking Science and Technology", Marcel
Dekker, Inc. Editor (1996).
In the upgrading treatment of products coming from the
F.T. synthesis, it is preferable to precede the hydrocrack-
ing step by at least one hydrogenation step of the unsatu-
rated and oxygenated compounds, especially alcohols, possi-
bly present, as these can contribute to decreasing the ac-
tivity of the hydrocracking catalyst and its lower stabil-
ity with time. For example, patent application EP-A 321,303
(Shell) describes a process which comprises the separation
of the light fraction (290-OC, rich in oxygenated com-
pounds) of a hydrocarbon mixture from an F.T. process, and
sending the 290+ C fraction to a hydrocrack-
ing/isomerization reactor for the production of medium dis-
tillates. The catalyst claimed for both reactors consists
of platinum supported on fluorinated alumina.
European patent application EP-A 1101813 describes an
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CA 02429289 2003-05-22
upgrading process of a waxy F.T. product comprising a hy-
drogenating treatment step mainly aimed at removing the or-
ganic oxygen and unsaturations in the olefins and, if nec-
essary, the partial isomerization of the lighter part of
the product, typically carried out at a temperature ranging
from 150 to 300 C, a hydrogen pressure ranging from 0.5 to
MPa and a space velocity (WHSV) ranging from 0.5 to
4 h"1, with a hydrogen/filler ratio ranging from 200 to
2000 Nlt/Kg. The hydrogenation catalyst is based on nickel,
10 platinum or palladium, supported on alumina, silico-
alumina, fluorinated alumina, with a concentration of the
metal which, depending on the type, ranges from 0.1 to 70%,
preferably from 0.5 to 10%, by weight. The hydrogenated
mixture is subsequently subjected to hydrocracking effected
so as to provide a conversion degree of at least 50% and
produce a medium distillate cut with high conversions and
selectivities. The catalyst used for the purpose preferably
consists of a noble metal, particularly Pt or Pd, supported
on an amorphous silica-alumina gel and micro/mesoporous
with a controlled pore size, a surface area of at least 500
m2/g and a molar ratio SiO2/Al2O3 ranging from 40/1 to
150/1, obtained according to one of the methods described
in European patent applications EP-A 582,347, EP-A 701,480
or EP 1,048,346, whose contents are incorporated herein as
reference. At the end, the hydrocracking reaction mixture
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is sent to a distillation/separation step from which, oper-
ating according to the known art, a medium distillate is
obtained, subdivided into gas oil and kerosene fractions,
both suitable, but especially the gas oil fraction, as com-
ponent (B) of the composition according to the present in-
vention.
The F.T. hydrocarbon mixture which forms component (B)
preferably comprises not less than 50%, more preferably
from 60 to 90%, by weight of branched aliphatic hydrocar-
bons, of which at least 60% has a methyl branching, as de-
termined with the gas-mass and NMR instrumental techniques
currently available. Other preferred characteristics of
this mixture are:
- Cetane Number > 60, more preferably > 70
- Pour Point < -10 C, more preferably < -25 C
- Distillation range substantially overlapping (at least
by 20 C) that of component (A), more preferably from
240 to 370 C.
The proportions of components (A) and (B) preferably
range from 85 to 98% by weight and from 15 to 2% by weight
respectively with respect to the overall weight of the two
components. These together form from 80 to 100%, preferably
from 90 to 100% by weight of the composition according to
the present invention, the remainder optionally consisting
of additives and smaller quantities of other components
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typically used in the preparation of fuels and combustibles
according to the usual technique.
The composition according to the present invention can
be easily prepared by mixing components (A) and (B) indi-
cated above, in the suitable proportions. Any suitable
method in the art can be adopted for the purpose, and there
are no particular critical operating conditions. The compo-
sition can be obtained for example by batch mixing in suit-
able containers, or, more conveniently, in continuous, as
normally happens within the scope of refinery processing.
According to a possible but non-limiting embodiment, compo-
nents (A) and (B), in appropriate proportions, are poured
into a container and briefly mixed at room temperature un-
til they are homogeneously dispersed in each other. The op-
tional additives can be added, when desired, to the pre-
formed mixture of (A) and (B), or they can be already pre-
sent, in suitable quantities, in one or both of the compo-
nents at the moment of mixing, preferably in component (A).
Particularly preferred, according to the present in-
vention, are compositions in which the mixture of compo-
nents (A) and (B) have a distillation range included in
typical gas oil cuts, i.e. from 200 C to 380 C, more pref-
erably from 240 to 360 C.
Although the compositions according to the present in-
vention show, as such, evident improvement in the lubri-
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cants properties, this does not exclude that they, can also
contain certain quantities of known additives for improving
the lubricity. In this case, it has been found that the lu-
bricating properties of the composition are however sur-
prisingly improved with respect to a mixture consisting of
component (A) alone with the same quantity of additive.
More generally, the compositions of the present inven-
tion can comprise up to 2096, preferably up to 10% by weight
with respect to the total weight, of one or more additives
usually used in the art for giving certain desired proper-
ties to compositions to be used as fuels, such as viscosity
improvers, anti-freeze agents, additives for improving the
combustion, such as cetane improvers and octane improvers.
In the preparation of the composition with an improved
lubricating capacity of the present invention, these addi-
tives can be indifferently added to the preformed mixture
of components (A) and (B), or each additive can be inde-
pendently added or contained in one of components (A) and
(B), or again, said additives can be added, in any order,
during and contemporaneously with the mixing of said compo-
nents (A) and (B) .
It has also been found that the lubricating capacity
of a typically classifiable fuel such as a medium distil-
late can be surprisingly improved by the addition of rela-
tively small quantities of non-oxygenated synthetic hydro-
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carbon cuts obtained from syntheses of the F.T. type.
A second object of the present invention therefore re-
lates to a method for improving the lubricating capacity
(lubricity) of a fuel for engines, characterized in that a
synthetic hydrocarbon mixture essentially without oxygen-
ated organic compounds, obtained by means of a process com-
prising a synthesis reaction of the Fischer-Tropsch type,
having a distillation range comprised within 130 and 380 C,
preferably within 150 and 370 C, more preferably within 240
and 370 C, is added to said fuel, in a quantity ranging
from 1 to 25% by weight with respect to the fuel itself.
According to a preferred aspect, said fuel is particu-
larly suitable for use in diesel engines and essentially
has the characteristics of the refinery hydrocarbon mixture
forming component (A) described above. The hydrocarbon mix-
tures indicated above as preferred component (A), espe-
cially the component (A) defined as gas oil, suitable as a
fuel for Diesel cycles, are therefore preferred as fuels
suitable for effecting the method.
The above fuel can also contain, according to the pre-
sent invention, one or more of the typical additives of fu-
els defined within the medium distillate range, as men-
tioned above. These additives do not generally exceed 20%
by weight of the fuel.
It is also preferable, for the purposes of the present
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CA 02429289 2003-05-22
invention, for the method in question to comprise the addi-
tion and mixing with said fuel of a hydrocarbon mixture de-
riving from a Fischer-Tropsch synthesis, having a distilla-
tion range substantially overlapping that of the fuel.
Particularly advantageous results are obtained by add-
ing to said fuel, a hydrocarbon mixture essentially having
the characteristics previously specified for component (B)
of the composition according to the present invention; more
preferably in a quantity ranging from 2 to 15% by weight.
Some examples are provided for a more detailed de-
scription of the present invention and for its practical
embodiment, which however merely illustrate particular as-
pects of the invention and should in no way be considered
as limiting the overall scope of the invention itself.
EXAMPLES
The lubricating properties of the compositions de-
scribed in the examples were evaluated by means of a lu-
bricity measurement according to the HFRR (high frequency
reciprocating rig) method. This method, developed at the
Mechanical Engineering Department of London Imperial Col-
lege has been recognized as being among the most qualified
for the lubricating capacity or lubricity measurement of a
composition suitable for use as a fuel, and is well known
by experts in the field. The equipment for effecting this
measurement is available on the market.
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The equipment for effecting the measurement according
to the HFRR method consists in an upper sphere loaded with
a standard weight which oscillates against a lower static
plate. The contact is totally immersed in the fuel on which
the measurement is being effected. During the measurement,
the friction and electric resistance of the contact are
registered and the diameter of the wear trace on the sphere
at the end of the test, is measured. In particular, a meas-
uring instrument supplied by the company PCS Ltd. of London
(UK) was used, with a load of 200 g on an AISI E-52100
steel sphere having a diameter of 6 mm, which oscillates on
a plate made of the same material. The measurement is ef-
fected on a 2 ml sample of fuel composition at 60 C.
in the following examples an essentially paraffinic
hydrocarbon mixture was used, obtained by the hydrocracking
and fractionation of a waxy mixture deriving from a tradi-
tional Fischer-Tropsch synthesis, according to the follow-
ing method.
PREPARATIVE EXAMPLE
A synthesis gas oil suitable as component (B) accord-
ing to the present invention, was prepared, using a waxy
product deriving from a Fischer-Tropsch process, essen-
tially consisting of linear hydrocarbons according to the
following composition (weight c):
Fraction < 150 C 4.9
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Kerosene (from 150 to 260 C) 13.9
Gas oil (from 260 to 370 C) 25.8
Fraction > 370 C 55.4
Alcohols (weight %) 4.7
Sulfur and aromatics absent
This mixture was subjected to hydrocracking treatment
according to the known techniques, and particularly accord-
ing to what is described in Example 5 of the patent EP-A
1101813.
At the end, after fractionation, a fraction was ob-
tained within the distillation range of gas oil (Gas oil
FT, yield 46%) having the following characteristics:
HFRR (wear diameter, ( m)): 607
Content of sulfur and aromatics absent
density: 0.824 Kg/dm3
Distillation range 250-360 C
Oxygen content less than 0.001 wt%
This fraction was used without further modifications
or additives in the following examples.
EXAMPLE 1
Three hydrocarbon compositions with an improved lu-
bricity according to the present invention, were prepared,
to be used as fuel for diesel engines, by mixing different
proportions of the following two components:
A) a refinery gas oil cut called "Gas oil All, having the
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CA 02429289 2003-05-22
following characteristics:
HFRR, wear diameter (pm) 407
sulfur (weight %) 0.8
density at 15 C 0.8491
aromatics (weight %) 25.2
distillation range ( C) 230-370
B) an essentially paraffinic hydrocarbon mixture consist-
ing of "Gas oil FT" obtained according to the above
Preparative Example.
Some of the properties of the compositions thus ob-
tained, indicated as (i), (ii) and (iii) respectively, are
indicated in Table 1 below, together with the relative pro-
portions of components (A) and (B).
EXAMPLE 2
Four hydrocarbon compositions with an improved lubric-
ity according to the present invention, were prepared, to
be used as fuel for diesel engines, by mixing different
proportions of the following two components:
A) a refinery gas oil cut called "Gas oil B11, having the
following characteristics:
HFRR, wear diameter ( m) 505
sulfur (weight t) 0.023
density at 15 C 0.8429
aromatics (weight %) 30.4
distillation range ( C) 230-370
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CA 02429289 2003-05-22
B) an paraffinic hydrocarbon mixture consisting of "Gas
oil FT" obtained as described above.
Some of the properties of the compositions thus ob-
tained, indicated as (i), (ii), (iii) and (iv) respec-
tively, are indicated in Table 1 below, together with the
relative proportions of components (A) and (B).
EXAMPLE 3
Three hydrocarbon compositions with an improved lu-
bricity according to the present invention, were prepared,
to be used as fuel for diesel engines, by mixing different
proportions of the following two components:
A) a refinery gas oil cut called "Gas oil C", having the
following characteristics:
HFRR, wear diameter (gm) 675
sulfur (weight 0.0047
density at 15 C 0.7971
aromatics (weight 8.8
distillation range ( C) 230-310
B) an paraffinic hydrocarbon mixture consisting of "Gas
oil FT" obtained as described above.
Some of the properties of the compositions thus ob-
tained, indicated as (i), (ii) and (iii) respectively, are
indicated in Table 1 below, together with the relative pro-
portions of components (A) and (B).
As can be seen from Table 1 below, the compositions
- 24 -
CA 02429289 2003-05-22
according to the present invention all have a surprisingly
improved lubricity (lower HFRR wear diameter values) with
respect to the lubricity of both of the original components
A and B. In the case represented by Example 2, the improve-
ment in lubricity is such as to allow specification values
to be reached (HFRR < 450 m) even though both of the
original components have higher HFRR values (505 gm and 607
pm respectively).
15
25
-
CA 02429289 2003-05-22
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26 -
