U.S. patent application number 10/532639 was filed with the patent office on 2006-03-09 for novel fuel with high octane index and reduced lead content.
Invention is credited to Celine Saillet, Michel Thebault, Raymond Touron.
Application Number | 20060052650 10/532639 |
Document ID | / |
Family ID | 32050639 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060052650 |
Kind Code |
A1 |
Thebault; Michel ; et
al. |
March 9, 2006 |
Novel fuel with high octane index and reduced lead content
Abstract
The invention concerns a novel fuel with high octane index and
reduced lead content. Said fuel has a lead content not more than
0.56 gram per liter of fuel, containing at least a first
hydrocarbon base (B1) consisting essentially of isoparaffins
including 4 or 5 carbon atoms, and a second hydrocarbon base (B2)
consisting essentially of isoparaffins including 6 to 9 carbon
atoms, and optionally at least a complement (B3) consisting
essentially of alkylaromatic hydrocarbons including 6 to 11 carbon
atoms, and wherein: the base B2 content in the fuel ranges between
45 vol. % and 85 vol. % and preferably between 50 vol. % and 82
vol. %, and the ratio B1/B2 of amounts in volume % ranges between
0.10 and 0.60 and preferably between 0.15 and 0.45. The invention
also concerns a method for preparing said fuel and uses
thereof.
Inventors: |
Thebault; Michel; (Le Havre,
FR) ; Saillet; Celine; (Sainte Adresse, FR) ;
Touron; Raymond; (Montivilliers, FR) |
Correspondence
Address: |
DICKSTEIN SHAPIRO MORIN & OSHINSKY LLP
1177 AVENUE OF THE AMERICAS (6TH AVENUE)
41 ST FL.
NEW YORK
NY
10036-2714
US
|
Family ID: |
32050639 |
Appl. No.: |
10/532639 |
Filed: |
October 22, 2003 |
PCT Filed: |
October 22, 2003 |
PCT NO: |
PCT/FR03/03128 |
371 Date: |
April 22, 2005 |
Current U.S.
Class: |
585/14 |
Current CPC
Class: |
C10L 1/06 20130101 |
Class at
Publication: |
585/014 |
International
Class: |
C10L 1/16 20060101
C10L001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2002 |
FR |
02/13167 |
Claims
1. A fuel having a lead content of less than or equal to 0.56 gram
per liter of fuel, containing at least one first hydrocarbon base
(B1) comprising more than 70% volume of isoparaffins containing 4
or 5 carbon atoms, and also at least one second hydrocarbon base
(B2) comprising more than 70% volume of isoparaffins containing 6
to 9 carbon atoms, and optionally at least one supplement (B3)
comprising more than 70% volume of hydrocarbons of alkylaromatic
type containing 6 to 11 carbon atoms, in which: the content of the
base B2 in the fuel is between 45% and 85% by volume and preferably
between 50% and 82% by volume, and in that the ratio of the volume
percentage amounts B1/B2 is between 0.10 and 0.60 and preferably
between 0.15 and 0.45.
2. The fuel as claimed in claim 1, wherein the lead content is less
than 0.56 gram per liter of fuel.
3. The fuel as claimed in claim 1, wherein the content of the base
B2 is between 55% and 75% by volume.
4. The fuel as claimed in claim 1, wherein the content of the base
B1 is between 12% and 30% by volume.
5. The fuel as claimed in claim 1, wherein it comprises less than
5% by volume of cycloparaffins containing 5 to 8 carbon atoms.
6. The fuel as claimed in claim 1, wherein the first base (B1)
comprises at least 80% by volume and preferably at least 90% by
volume of isoparaffins containing 5 carbon atoms.
7. The fuel as claimed in claim 1, wherein isopentane constitutes
at least 90% by volume of the isoparaffins containing 5 carbon
atoms.
8. The fuel as claimed in claim 1, wherein the content of
isoparaffins containing 4 carbon atoms in the base (B1) is less
than or equal to 10% by volume.
9. The fuel as claimed in claim 1, wherein the second base (B2)
comprises at least 80% by volume and preferably at least 90% by
volume of isoparaffins containing 8 carbon atoms.
10. The fuel as claimed in claim 9, wherein isooctanes constitute
at least 70% by volume and preferably at least 75% by volume of the
isoparaffins containing 8 carbon atoms.
11. The fuel as claimed in claim 1, wherein the supplement (B3)
comprises at least 80% by volume and preferably at least 85% by
volume of aromatic compounds containing 6 to 9 carbon atoms.
12. The fuel as claimed in claim 11, wherein toluene constitutes at
least 45% by volume and preferably at least 50% by volume of the
aromatic hydrocarbons.
13. The fuel as claimed in claim 1, wherein the ratio of the volume
percentage amounts B3/B2 is between 0.00 and 0.60 and preferably
between 0.00 and 0.55.
14. The fuel as claimed in claim 1, wherein the ratio of the volume
percentage amounts B3/B2 is between 0.1 and 0.60 and preferably
between 0.2 and 0.45.
15. A fuel having a lead content of less than or equal to 0.56 gram
per liter of fuel, containing at least one first part of
isoparaffins containing 4 or 5 carbon atoms, and also at least one
second part of isoparaffins containing 6 to 9 carbon atoms, and
optionally at least one supplementary part of hydrocarbons of
alkylaromatic type containing 6 to 11 carbon atoms, in which: the
content of isoparaffins containing 6 to 9 carbon atoms in the fuel
is between 45% and 85% by volume and preferably between 50% and 82%
by volume, and in that the ratio of the volume percentage amounts
of isoparaffins containing 4 or 5 carbon atoms/isoparaffins
containing 6 to 9 carbon atoms is between 0.10 and 0.60 and
preferably between 0.15 and 0.45.
16. The fuel as claimed in claim 15, characterized in wherein the
lead content is less than 0.56 gram per liter of fuel.
17. The fuel as claimed in claim 15, wherein the content of
isoparaffins containing 6 to 9 carbon atoms in the fuel is between
55% and 75% by volume.
18. The fuel as claimed in claim 15, wherein the content of
isoparaffins containing 4 or 5 carbon atoms in the fuel is between
12% and 30% by volume.
19. The fuel as claimed in one of claim 15, wherein it comprises
less than 5% by volume of cycloparaffins containing 5 to 8 carbon
atoms.
20. The fuel as claimed in of claim 15, wherein the ratio of the
volume percentage amounts of hydrocarbons of alkylaromatic type
containing 6 to 11 carbon atoms/isoparaffins containing 6 to 9
carbon atoms is between 0.00 and 0.60 and preferably between 0.00
and 0.55.
21. The fuel as claimed in claim 15, wherein the ratio of the
volume percentage amounts of hydrocarbons of alkylaromatic type
containing 6 to 11 carbon atoms/isoparaffins containing 6 to 9
carbon atoms is between 0.1 and 0.60 and preferably between 0.2 and
0.45.
22. The fuel as claimed in claim 1, wherein its lead content is
less than or equal to 0.42 gram per liter of fuel and preferably
0.28 gram per liter of fuel.
23. The fuel as claimed in one of claim 1, wherein its lead content
is less than or equal to 0.26 and preferably less than 0.14 gram
per liter of fuel.
24. The fuel as claimed in one of claim 1, wherein its lead content
is between 0.10 and 0.28 and preferably between 0.14 and 0.26 gram
per liter of fuel.
25. The fuel as claimed in claim 1, wherein its F4 octane number is
greater than or equal to 130.
26. The fuel as claimed in claim 1, wherein its Net Heat of
Combustion (determined according to standard ASTM D4529) is greater
than or equal to 39.1 MJ/kg and preferably greater than or equal to
43.5 MJ/kg.
27. The fuel as claimed in claim 1, wherein its Net Heat of
Combustion (determined according to standard ASTM D4529) is between
39.1 MJ/kg and 43.5 MJ/kg, preferably between 39.1 MJ/kg and 43
MJ/kg, advantageously between 39.1 MJ/kg and 42.2 MJ/kg and more
advantageously between 39.1 MJ/kg and 41.3 MJ/kg.
28-33. (canceled)
34. The fuel as claimed in claim 15, wherein its lead content is
less than or equal to 0.42 gram per liter of fuel and preferably
0.28 gram per liter of fuel.
35. The fuel as claimed in claim 15, wherein its lead content is
less than or equal to 0.26 and preferably less than 0.14 gram per
liter of fuel.
36. The fuel as claimed in claim 15, wherein its lead content is
between 0.10 and 0.28 and preferably between 0.14 and 0.26 gram per
liter of fuel.
37. The fuel as claimed in claim 15, wherein its F4 octane number
is greater than or equal to 130.
38. The fuel as claimed in claim 15, wherein its Net Heat of
Combustion (determined according to standard ASTM D4529) is greater
than or equal to 39.1 MJ/kg and preferably greater than or equal to
43.5 MJ/kg.
39. The fuel as claimed in claim 15, wherein its Net Heat of
Combustion (determined according to standard ASTM D4529) is between
39.1 MJ/kg and 43.5 MJ/kg, preferably between 39.1 MJ/kg and 43
MJ/kg, advantageously between 39.1 MJ/kg and 42.2 MJ/kg and more
advantageously between 39.1 MJ/kg and 41.3 MJ/kg.
40. A process for preparing a fuel with a low lead content and a
high octane number, in which at least one first hydrocarbon base
(B1) comprising more than 70% volume of isoparaffins containing 4
or 5 carbon atoms, and at least one second hydrocarbon base (B2)
comprising more than 70% volume of isoparaffins containing 6 to 9
carbon atoms, and optionally a supplement (B3) comprising more than
70% volume of hydrocarbons of alkylaromatic type containing 6 to 11
carbon atoms, are mixed together in amounts such that: the content
of the base B2 in the fuel is between 45% and 85% by volume and
preferably between 50% and 82% by volume, and in that the ratio of
the volume percentage amounts B1/B2 is between 0.10 and 0.60 and
preferably between 0.15 and 0.45.
41. The process as claimed in claim 40, for the preparation of the
fuel as claimed in claim 1.
42. The process as claimed in claim 40, for the preparation of the
fuel as claimed in claim 15.
43. The use of the fuel as claimed in claim 1 for fueling, alone or
as a mixture, an aircraft controlled-ignition engine.
44. The use of the fuel as claimed in claim 1 for fueling, alone or
as a mixture, a controlled-ignition engine of a competition vehicle
or the like.
45. The use of the fuel as claimed in claim 1 for fueling, alone or
as a mixture, a fuel processing unit, such as a reformer, coupled
to a fuel cell.
46. The use of the fuel as claimed in claim 1 for reducing the
pollution emissions of a controlled-ignition engine.
47. The use of the fuel as claimed in claim 15 for fueling, alone
or as a mixture, an aircraft controlled-ignition engine.
48. The use of the fuel as claimed in claim 15 for fueling, alone
or as a mixture, a controlled-ignition engine of a competition
vehicle or the like.
49. The use of the fuel as claimed in claim 15 for fueling, alone
or as a mixture, a fuel processing unit, such as a reformer,
coupled to a fuel cell.
50. The use of the fuel as claimed in claim 15 for reducing the
pollution emissions of a controlled-ignition engine.
Description
[0001] The present invention relates to novel fuel formulations
having a high octane number and reduced contents of organo-lead
compounds, which may be used for fueling controlled-ignition
internal combustion engines, in particular those fitted in
aircraft, or engines with a high compression ratio.
[0002] It is known that, prior to being made available on the
market, fuels intended for fueling controlled-ignition internal
combustion engines must satisfy precise physicochemical
characteristics to ensure that the user obtains high mechanical
performance and, at the same time, to minimize the sources of
pollution, whether they are generated by the exhaust gases or by
the product itself during its handling or storage. These
characteristics, which may vary substantially from one fuel to
another, must remain within a range defined by official
specifications collated and published by qualified bodies, such as
AFNOR in France or ASTM in the United States. Among these
specifications, that relating to the octane number, i.e. the number
measuring the anti-knock value of a fuel by comparison with a
"reference" spirit, is an essential characteristic, since it
reflects the combustion performance of the fuel in the engine
cylinders, and in particular its resistance to pinking, i.e. its
resistance to uncontrolled bulk self-combustion.
[0003] Thus, two types of octane number are distinguished in the
art for spirits intended for fueling engines fitted in motor
vehicles: the RON (Research Octane Number) and the MON (Motor
Octane Number), which are referred to, respectively, in the
profession as F1 and F2.
[0004] In the field of aviation, and more specifically for aircraft
fitted with controlled-ignition engines, the fuels available on the
market must be produced with care and must in particular have very
good resistance to pinking for obvious reasons of reliability and
operating safety at altitude, and above all given the severe and
particular conditions of use of these engines, which run at full
load during the takeoff phase. Two specific octane numbers have
consequently been defined and incorporated into the specifications
of aircraft spirit, namely: [0005] the MON or motor octane number
(which replaces the old number, previously referred to as F3 in the
profession), which is aimed at assessing correct functioning of the
motorization as a whole during normal running, i.e. at altitude and
at stabilized speed; and [0006] the supercharge octane number, also
known as F4 or performance number, which reflects the combustion
performance needs of the engine on takeoff.
[0007] Thus, a fuel whose commonly used trade name is "AVGAS 100LL"
corresponds to a spirit for controlled-ignition piston aircraft
engines, the MON of which should be, according to standard ASTM
D910-01 (Standard Specification for Aviation Gasolines) or the
equivalent British standard DEF STAN (Defense Standard) 91-90 of 8
May 1996, greater than or equal to 99.5; and the F4 greater than or
equal to 130. The abbreviation "LL" means "low lead", i.e. the lead
content of the fuel, generally originating from alkylleads, should
be, according to this standard that is currently in force, less
than or equal to 0.56 gram per liter of spirit.
[0008] It is known that the spirits manufactured directly by
distillation of crude petroleum do not have the required
characteristics, in particular the required octane characteristics,
to allow them to be placed directly on the aviation market. The
refiner must therefore, during their manufacture, perform mixing of
various hydrocarbon bases in order to obtain products which, with
the optional addition of additives, will comply with the various
specifications required for their marketing. These bases may
consist, for example and in a nonlimiting manner, of: [0009] light
distillation fractions essentially containing paraffins containing
4 or 5 carbon atoms; [0010] hydrocarbons derived from the
alkylation of gases containing 1 to 4 carbon atoms, free of
aromatic or olefinic molecules; [0011] light spirits originating
from the direct distillation of crude petroleum, whether these
spirits are isomerized or nonisomerized; and [0012] hydrocarbons
mainly containing aromatic compounds having, by nature, high octane
numbers.
[0013] However, the octane requirements of fuels for aircraft
engines are so high that it is generally impossible to economically
produce such fuels, having the required specifications, without
resorting to the massive addition of additives. This is why
refiners commonly add an organolead compound in order to ensure the
MON and F4 specifications of spirit of type 100LL, in accordance
with standard ASTM D910-01. This compound is generally
tetraethyllead (C.sub.8H.sub.20Pb), abbreviated as TEL, the content
of which in the fuel should be in accordance with the standard and
should not exceed 0.56 gram of lead per liter of spirit.
[0014] It is known, however, that the use of lead in fuels, on
account of its harmful nature to health, has been terminated in
Europe since Jan. 1, 2000 and since Jan. 1, 1996 in the United
States, for motor vehicle spirits, but not for fuels intended for
controlled-ignition aircraft engines, by special exemption from the
Environmental Protection Agency (EPA). Consequently, it is now
acknowledged that aircraft spirit remains an important source of
pollution for the atmosphere.
[0015] The problem of reducing lead content in certain aircraft
engine spirits, and especially AVGAS 100LL, or even of eliminating
it, is thus acutely relevant and a solution will need to be found
in the short or medium term. However, replacement alternatives have
already been proposed, for instance the use of: [0016] a lead-free
spirit for aircraft of the type 82UL (specified by ASTM D6227-00)
or for motor vehicles, but the anti-pinking characteristics of
motor vehicles are insufficient to be able to feed all the existing
fleet; [0017] a lead-free aviation spirit composition, but with
additions of oxygenated compounds such as MTBE or ETBE, as
described in patent WO 02/22766; [0018] a spirit that is also
lead-free, formulated with, inter alia, known hydrocarbon bases, an
alkyl tert-butyl ether, an aromatic amine and optionally a
manganese compound, as claimed in patent WO 97/44413; [0019] an
aircraft spirit formulation manufactured from standard bases with
addition of toluene and an aromatic amine for F4, in accordance
with the description of patent WO 94/25545; [0020] a lead-free
spirit manufactured with addition of
methylcyclopentadienyl-manganese-tricarbonyl (abbreviated as MMT)
in accordance with the teaching of patents EP 0 540 297, EP 0 609
089 and WO 94/17158, or [0021] a lead-free composition for aircraft
spirit, manufactured with addition of triptane, as described in
patent WO 98/22556.
[0022] All the spirit compositions that are currently available
present refiners with technical difficulties of formulation, while
at the same time generating additional costs due to the use of
numerous additives, or specific hydrocarbon bases, which is made
necessary in order to compensate for the absence of or decrease in
lead, i.e. the lack of octane, and consequently to achieve the
specified MON and F4 targets. Furthermore, the environmental
compatibilities of the various additives used at the present time
have not yet been entirely demonstrated; thus, all aromatic amines
are classified as toxic substances, in the event of absorption by
inhalation or ingestion, and especially for the skin. As regards
MMT, it is indexed by the EPA as being an atmospheric pollutant
that may be potentially hazardous to man.
[0023] To manufacture aircraft spirits of 100LL type economically
and with reduced environmental risks, refiners are thus confronted
with the following alternative: [0024] either formulating fuels
using bases commonly available in refineries, but in which the
organolead compounds have been replaced with additions of various
additives, or specific hydrocarbon bases, so as to obtain an MON
and an F4 in accordance with the specification in force. These
additions consequently give rise to extra cost for the refiner and
possible environmental drawbacks; [0025] or to subject the various
hydrocarbon bases included in the composition of fuels to expensive
treatments in order to increase their octane number and thus reduce
or even dispense with the lead, but these various treatments
require, however, complex processes that also generate a large
additional cost for the refiner.
[0026] The research conducted by the Applicant in the field of fuel
manufacture has now enabled it to establish, surprisingly, that the
precise and rigorous formulation of aviation spirits, from certain
hydrocarbon bases generally available in a petroleum refinery,
makes it possible to give them a sufficiently high octane number of
the F4 type, at least equal to 130, and an MON at least equal to
99.5, while at the same time substantially reducing the content of
organolead compounds, and especially of TEL, without having to
resort to octane-providing substitution additives.
[0027] The aim of the invention is thus to provide novel fuel
formulations for controlled-ignition internal combustion engines,
made from a mixture of hydrocarbon bases available in a petroleum
refinery, and containing an appreciably reduced amount of
organolead compounds compared with the formulations of the prior
art, and which give these fuels an octane number and
characteristics that comply with the standards in force.
[0028] To this end, one subject of the invention is a fuel having a
lead content of less than or equal to 0.56 gram per liter of fuel,
containing at least one first hydrocarbon base (B1) consisting
essentially of isoparaffins containing 4 or 5 carbon atoms, and
also at least one second hydrocarbon base (B2) consisting
essentially of isoparaffins containing 6 to 9 carbon atoms, and
optionally at least one complement (B3) consisting essentially of
hydrocarbons of alkylaromatic type containing 6 to 11 carbon atoms,
in which: [0029] the content of the base B2 in the fuel is between
45% and 85% by volume and preferably between 50% and 82% by volume,
and in that [0030] the ratio of the volume percentage amounts B1/B2
is between 0.10 and 0.60 and preferably between 0.15 and 0.45.
[0031] To this end, a subject of the invention is also a fuel
having a lead content of less than or equal to 0.56 gram per liter
of fuel, containing at least one first part of isoparaffins
containing 4 or 5 carbon atoms, and also at least one second part
of isoparaffins containing 6 to 9 carbon atoms, and optionally at
least one complementary part of hydrocarbons of alkylaromatic type
containing 6 to 11 carbon atoms, in which: [0032] the content of
isoparaffins containing 6 to 9 carbon atoms in the fuel is between
45% and 85% by volume and preferably between 50% and 82% by volume,
and in that [0033] the ratio of the volume percentage amounts of
isoparaffms containing 4 or 5 carbon atoms/isoparaffins containing
6 to 9 carbon atoms is between 0.10 and 0.60 and preferably between
0.15 and 0.45.
[0034] In the present description: [0035] the term "essentially
consisting of" means the presence of a large amount, preferably
greater than 70% by volume, of cited compounds in the corresponding
hydrocarbon base; [0036] the lead contents are cited by reference
to the methods for measuring lead contents, described in standards
ASTM D3341 (iodine monochloride method) or ASTM D5059 (X-ray
spectrometry method); [0037] the MON and the F4 are measured,
respectively, in accordance with standards ASTM D2700 and ASTM
D909.
[0038] According to the invention, the ratio of the volume
percentage amounts B3/B2 is between 0.00 and 0.60 and preferably
between 0.00 and 0.55; alternatively, the ratio of the volume
percentage amounts of hydrocarbons of alkylaromatic type containing
6 to 11 carbon atoms/isoparaffins containing 6 to 9 carbon atoms is
between 0.00 and 0.60 and preferably between 0.00 and 0.55.
[0039] The use of at least the two fractions (B1), (B2),
preferentially along with at least the fraction (B3), and their
incorporation in the abovementioned relative amounts, allows the
refiner to formulate fuels that simultaneously have a high octane
number and a reduced lead content, of less than or equal to 0.56
gram per liter, preferably less than or equal to 0.42 gram per
liter, even more preferably less than or equal to 0.35 gram per
liter, entirely preferably less than or equal to 0.28 gram per
liter and ideally equal to 0.14 gram per liter of fuel.
[0040] Specifically, the fuels according to the invention may be
manufactured using hydrocarbon bases available in a standard
refinery, and may achieve high octane numbers, in accordance with
the strictest standards such as standard ASTM D910-01, while at the
same time having a lead content that may be as low as 0.27 g/l, or
even less. Thus, with strictly processed bases, it is possible to
formulate aircraft fuels having a lead content of only 0.14 g/l.
The refiner thus adds less lead derivative than previously.
[0041] In the present description, reference is made mainly to
fuels for aircraft engines, but the fuels in accordance with the
invention may be used in fields other than aviation, and especially
for fueling, alone or as a mixture, controlled-ignition engines for
vehicles of all types, especially aircraft. The use of the fuel
according to the invention is particularly advantageous for fueling
the engines of competition vehicles or the like, i.e. for engines
with a high compression ratio, requiring fuels with a very high
octane number. The fuel that is the subject of the present
invention may also be used for fueling, alone or as a mixture,
systems of very diverse nature, for example a fuel processing unit,
such as a reformer, coupled to a fuel cell.
[0042] The first hydrocarbon base (B1) used for the manufacture of
the fuels in accordance with the invention belongs to the family of
paraffinic hydrocarbons and may be, for example, a light base
containing at least 80% by volume and preferably at least 90% by
volume of isoparaffinic molecules containing 4 or 5 carbon atoms
and preferably 5 carbon atoms. Even more preferably, isopentane
constitutes at least 90% by volume of the molecules containing 5
carbon atoms.
[0043] This light paraffinic base may originate, for example, from
a fractionation of the lightest fraction of the distillate produced
by the atmospheric distillation of crude petroleum or from an
alkane isomerization unit.
[0044] Advantageously, this hydrocarbon fraction may contain up to
10% by volume of isoparaffins containing 4 carbon atoms; isobutane
constitutes at least 5% by volume of said isoparaffins, when there
is a need to increase the vaporization of the fuel to feed the
controlled-ignition engine.
[0045] The second base used (B2) typically contains at least 80% by
volume and preferably at least 90% by volume of isoparaffins
containing between 6 and 9 carbon atoms and preferably 8 carbon
atoms. Isooctanes constitute at least 70% by volume and preferably
at least 75% by volume of these isoparaffinic hydrocarbons
containing 8 carbon atoms.
[0046] Such a hydrocarbon base may originate from various processes
for processing crude petroleum, generally present in a petroleum
refinery. In particular, this isooctane-rich hydrocarbon fraction,
also known in the profession as "alkylate", may be produced, for
example, via the process for the alkylation of isobutane with light
olefins.
[0047] An alternative consists in replacing some of this
isoparaffinic fraction and simultaneously reducing the proportion
of alkylate, which is a petroleum base whose manufacturing cost is
relatively high, with a hydrocarbon fraction originating from a
unit for isomerizing light spirits, these spirits being derived
from the distillation of crude petroleum.
[0048] The complement used (B3) is a hydrocarbon fraction
containing 6 to 11 carbon atoms, of which the content of aromatic
compounds. containing 6 to 9 carbon atoms is typically greater than
or equal to 80% by volume and preferably greater than or equal to
85% by volume. Even more preferably, these aromatic compounds
contain 7 carbon atoms and are toluene, the content of which in the
complement (B3) is greater than or equal to 45% by volume and
preferably greater than or equal to 50% by volume. This hydrocarbon
base used in the formulation of the spirits for aircraft engines
generally originates from a manufacturing process known as spirit
"reforming", available in particular in a petroleum refinery. This
process makes it possible, by means of a set of chemical reactions
taking place at high temperature and high pressure, necessarily in
the presence of a suitable catalyst, to convert straight-chain or
cyclic molecules contained in the heaviest spirits, for example
those produced by the direct distillation of crude petroleum, into
more stable branched and cyclic aromatic hydrocarbons. These
aromatic hydrocarbons are generally referred to as "reformates" in
the profession and have a high octane number.
[0049] In addition to the bases (B1), (B2) and (B3), the fuel
according to the invention may contain many other bases. These may
be chosen especially from all the bases liable to be included in
the composition of the spirits. These bases may be derived from
standard refining operations (for example, but in a nonlimiting
manner, the distillation of crude petroleum, catalytic cracking,
hydrocracking, reforming, isomerizing, alkylating, etc. processes),
but may also comprise synthetic-hydrocarbons such as those obtained
by oligomerization of olefins or by Fischer-Tropsch synthesis.
[0050] Preferably, these additional bases are chosen from those
having a distillation range of between 25.degree. C. and
175.degree. C. (determined according to standard ASTM D 86) and
even more preferably between 75.degree. C. and 135.degree. C. A
person skilled in the art will readily know how to determine the
nature and amounts of the additional bases liable to be
incorporated into the fuel according to the invention, given the
application for which this fuel is intended and the bases available
in the refinery.
[0051] Each base included in the composition of the fuel according
to the invention, i.e. (B1), (B2), (B3) and also any additional
base, may advantageously have been totally or partially subjected
to a desulfurization and/or deazotization treatment and,
optionally, a dearomatization treatment, at any stage in its
production. For example, it is possible to use bases that have been
hydroprocessed under more or less severe conditions (comprising
hydrodesulfurization and/or saturation of the aromatic and olefinic
compounds and/or hydrodeazotization).
[0052] The fuel according to the invention advantageously has a
sulfur content (determined according to standards ASTM D1266 or
ASTM D2622) of less than or equal to 500 ppm by weight, preferably
less than or equal to 100 ppm by weight, even more preferably a
sulfur content of less than or equal to 50 ppm by weight or even 10
ppm by weight.
[0053] The fuel according to the invention may contain one or more
additives that a person skilled in the art can readily select from
the numerous additives conventionally used for fuels. The choice of
these additives depends essentially on the application for which
the fuel is intended. Mention is especially made, but in a
nonlimiting manner, of corrosion-inhibiting, antifreeze or
antistatic additives, additives for improving the cold properties,
tracer additives or detergent additives, and mixtures thereof.
[0054] For example, when the fuel is intended for aviation use, it
may contain, inter alia, at least one antioxidant chosen from
sterically hindered phenols (for instance
2,6-di-t-butyl-4-methylphenol (BHT), 2,6-di-t-butylphenol and
2,4-dimethyl-6-t-butylphenol).
[0055] The determination of the contents of other possible
hydrocarbons and common additives in the fuel, in order to make it
comply with the regulations in force in the art or with particular
characteristics, is within the competence of a person skilled in
the art and poses no particular technical problem.
[0056] The invention also relates to a process for preparing fuel
with a low lead content and a high octane number, in which at least
one first hydrocarbon base (B1) consisting essentially of
isoparaffins containing 4 or 5 carbon atoms, and at least one
second hydrocarbon base (B2) consisting essentially of isoparaffins
containing 6 to 9 carbon atoms, and, preferably, at least one
supplement (B3) consisting essentially of hydrocarbons of
alkylaromatic type containing 6 to 11 carbon atoms, and,
optionally, additives that are common for this type of fuel, are
mixed together, by means known in the art, in amounts such that:
[0057] the content of the base B2 in the fuel is between 45% and
85% by volume and preferably between 50% and 82% by volume, and in
that [0058] the ratio of the volume percentage amounts B1/B2 is
between 0.10 and 0.60 and preferably between 0.15 and 0.45.
[0059] Finally, the invention relates to the use of such a fuel for
reducing the polluting emissions of a controlled-ignition engine.
Specifically, besides reducing the pollution due to the reduction
in the lead content in the fuel, this reduction also results in a
decrease in the content of methyl bromide, produced during the
combustion of AVGAS 100LL. This methyl bromide, which has known
destructive effects on the atmospheric ozone layer, originates from
the dibromoethane that is added (referred to as a "scavenger" in
the profession) during the manufacture of 100LL spirit so as to
trap the lead in the engine cylinders, and allow its removal by
volatility after the combustion cycle.
[0060] According to one embodiment, the lead content is less than
0.56 gram per liter of fuel.
[0061] According to one embodiment, the content of the base B2 is
between 55% and 75% by volume. According to one embodiment, the
content of the base BI is between 12% and 30% by volume.
[0062] According to one embodiment, the fuel comprises less than 5%
by volume of cycloparaffins containing from 5 to 8 carbon
atoms.
[0063] According to one embodiment, the ratio of the volume
percentage amounts B3/B2 is between 0.1 and 0.60 and preferably
between 0.2 and 0.45.
[0064] According to one embodiment, the lead content is less than
or equal to 0.26 and preferably less than 0.14 gram per liter of
fuel.
[0065] According to another embodiment, the lead content is between
0.10 and 0.28 and preferably between 0.14 and 0.26 gram per liter
of fuel.
[0066] According to one embodiment, the Net Heat of Combustion
(determined according to standard ASTM D4529) is between 39.1 MJ/kg
and 43.5 MJ/kg, preferably between 39.1 MJ/kg and 43 MJ/kg,
advantageously between 39.1 MJ/kg and 42.2 MJ/kg and more
advantageously between 39.1 MJ/kg and 41.3 MJ/kg.
[0067] The reduction of the lead content in the fuel, in accordance
with the invention, is particularly advantageous for the following
reasons, alone or in combination: [0068] it complies with the
existing specifications and does not have the environmental
drawbacks of the usual fuels, intended for the same applications,
for a manufacturing cost that is substantially lower than said
usual fuels; [0069] it does not incorporate any octane-providing
additives other than a reduced amount of organolead compounds;
[0070] its environmental qualities are more suited to the current
requirements; [0071] its lower lead content allows the scavenger
content to be reduced; and [0072] it is compatible with all the
other fuels for controlled-ignition engines.
[0073] Other characteristics and advantages of the invention will
become apparent in the detailed examples that follow, which have no
limiting nature.
EXAMPLES
Example 1
[0074] The Applicant formulated 4 fuels (listed C1 to C4) in
accordance with the invention using the hydrocarbon bases B1, B2
and B3 generally found in a petroleum refinery, and the
compositions of which are indicated in table 1 below, and 4 other
mixtures not within the scope of the invention (listed C5 to C8).
TABLE-US-00001 TABLE 1 Composition of the 3 bases B1, B2 and B3 B1
C5 isoparaffins 95.47% mass C5 and C4 paraffins 3.34% mass C4 and
C5 olefins 1.19% mass B2 C8 isoparaffins 82.87% mass C6, C7 and C9
isoparaffins 10.02% mass C5, C10 and C11 isoparaffins 5.75% mass C4
and C11 paraffins 1.29% mass C9 olefins 0.02% mass C11 aromatics
0.05% mass B3 C7 aromatics 51.72% mass C8 aromatics 26.36% mass C9
aromatics 9.84% mass C6, C10 and C11 aromatics 1.74% mass C4 to C11
paraffins 2.54% mass C4 to C9 isoparaffins 5.99% mass Others 1.81%
mass
[0075] For each fuel thus manufactured, the main physicochemical
characteristics (cf table 2) were measured in accordance with
standard ASTM D910-01. TABLE-US-00002 TABLE 2 Main characteristics
of the aviation spirit 100LL and corresponding analysis methods
Specifications ASTM D-910-01 F4 min 130.0 ASTM D909 MON min 99.5
ASTM D2700 NHC MJ/kg min 43.5 ASTM D4529 VP (38.degree. C., KPa)
min 38.0 ASTM D5191 max 49.0 10% evaporated .degree. C. max 75 ASTM
D86 50% evaporated .degree. C. max 105 ASTM D86 90% evaporated
.degree. C. max 135 ASTM D86 Final point max 170 ASTM D86 Pb g/l
max 0.56 ASTM D2392 NHC: Net heat of combustion VP: Vapor
Pressure
[0076] The results of the measurements are given in table 3
TABLE-US-00003 TABLE 3 Manufacture of the fuels and characteristics
thereof according to ASTM D910-01 Specifications ASTM D-910-
Mixtures C1 C2 C3 C4 C5 C6 C7 C8 01 B1 (% v) 21.2 21.1 12.0 17.3
37.5 7.0 61.5 19.8 -- B2 (% v) 50.8 57.9 68.7 57.5 40.0 91.2 20.8
31.2 -- B3 (% v) 28.0 21.0 19.3 25.2 22.5 1.8 17.7 49.0 -- B1/B2
0.42 0.36 0.17 0.30 0.94 0.07 2.96 0.63 B3/B2 0.55 0.36 0.28 0.44
0.56 0.02 0.85 1.57 F4 150.0 130.0 131.8 130.0 130.9 130.8 105.7
132.3 min 130.0 ASTM D909 MON 105.6 102.0 102.0 101.4 102.8 103.2
100.8 99.8 min 99.5 ASTM D2700 NHC 43.5 43.8 43.8 43.6 43.7 44.5
44.0 42.6 min 43.5 MJ/kg ASTM D4529 VP 48.0 49.0 38.0 43.6 69.3
34.5 100.0 42.9 min 38.0 (38.degree. C., max 49.0 KPa) ASTM D5191
10% 62.2 61.6 72.0 66.4 42.8 76.1 14.6 65.9 max 75 evaporated
.degree. C. ASTM D86 50% 103.7 101.9 105.0 104.5 95.9 102.3 85.23
109.8 max 105 evaporated .degree. C. ASTM D86 90% 122.7 118.9 118.2
121.3 119.2 108.8 115.9 134.2 max 135 evaporated .degree. C. ASTM
D86 Final 157.2 152.8 151.9 155.6 153.4 140.9 149.9 170.6 max 170
point .degree. C. ASTM D86 Pb g/l 0.54 0.30 0.28 0.27 0.38 0.30
0.27 0.23 max 0.56 ASTM D2392
[0077] It is seen in table 3 that the fuels formulated in
accordance with the present invention (C1 to C4) satisfy the main
characteristics of ASTM D910-01 for AVGAS 100LL. In contrast, when
the content of B2 in the fuels (C5 to C8) is not between 45% and
85% by volume, or when the ratio B1/B2 is not within the range
0.10-0.60, the specifications are not met. This table also teaches
that it is possible to formulate a fuel with a lead content equal
to 0.27 gram per liter of fuel while at the same time satisfying
the standard in force (C4).
Example 2
[0078] This example is identical to example 1, but the fuels C9 to
C 16 were formulated using purified bases B1, B2 and B3, the
respective new compositions of which are indicated in table 4
below. TABLE-US-00004 TABLE 4 Composition of the 3 bases B1 C5
isoparaffins 100.00% mass B2 C8 isoparaffins 99.97% mass C7
isoparaffins 0.03% mass B3 C7 aromatics 99.95% mass C5 and C8
aromatics 0.05% mass
[0079] The results of the measurements are given in table 5
TABLE-US-00005 TABLE 5 Manufacture of the fuels and characteristics
thereof according to ASTM D910-01 Specifications ASTM Mixttures C9
C10 C11 C12 C13 C14 C15 C16 D-91001 B1 (% v) 26.1 16.2 17.2 19.3
29.5 38.5 7.5 20.8 -- B2 (% v) 47.9 83.6 68.1 54.8 28.8 43.2 89.2
30.7 -- B3 (% v) 26.0 0.2 14.7 25.9 41.7 25.3 3.3 48.5 -- B1/B2
0.54 0.19 0.25 0.35 1.02 0.89 0.08 0.68 B3/B2 0.54 0.01 0.21 0.47
1.44 0.58 0.03 1.58 F4 155.0 134.9 130.1 130.0 130.4 132.2 130.5
142.0 min ASTM D909 130.0 MON 107.9 105.4 102.7 101.2 99.6 104.4
103.3 99.7 min 99.5 ASTM D2700 NHC MJ/kg 43.5 44.7 44.0 43.5 42.8
46.7 44.6 42.4 min 43.5 ASTM D4529 VP (38.degree. C., 48.9 38.0
38.0 39.6 52.1 67.0 25.6 39.6 min 38.0 KPa) ASTM max 49.0 D5191 10%
evaporated 61.6 73.6 73.1 70.8 57.8 51.4 85.7 70.1 max 75 .degree.
C. ASTM D86 50% evaporated 98.6 95.4 98.5 100.4 101.2 101.9 98.6
105.2 max 105 .degree. C. ASTM D86 90% evaporated 102.1 95.6 99.1
101.8 106.0 109.1 96.0 107.3 max 135 .degree. C. ASTM D86 Final
point 111.9 103.3 108.2 111.9 117.1 118.7 104.5 119.5 max 170
.degree. C. ASTM D86 Pb g/l 0.54 0.28 0.18 0.14 0.14 0.23 0.17 0.14
max 0.56 ASTM D2392
[0080] As in example 1, the fuels formulated in accordance with the
present invention (C9 to C12) satisfy the main characteristics of
ASTM D910-01 for AVGAS 100LL. Furthermore, with the use of purified
bases, the content of 0.14 gram of lead per liter of fuel may be
achieved (C12), while at the same time satisfying the
specifications for the spirit 100LL. In contrast, when the content
of the base B2 in the fuels (C13 to C16) is not between 45% and 85%
by volume, and when the ratio B1/B2 is not within the range
0.10-0.60, the specifications are not- met.
Example 3
[0081] Given that the "CRC-unleaded Aviation Gasoline Development
Group" envisaged in its preliminary report of 18 Nov. 1999 a
possible relaxation of the specification of the Net Heat of
Combustion for the spirit 100LL, which may be up to several percent
of the nominal value, the Applicant has established the ranges of
formulations for fuels satisfying the specifications of ASTM
D910-01, for various contents of lead, and several values of the
minimum NHC, ranging from 43.5 to 39.1 MJ/kg, when these fuels are
manufactured with industrial bases of petroleum refinery type, or
purified products. The results are presented in tables 6 and 7.
1/Industrial Bases
[0082] The bases B1, B2 and B3 have the physicochemical
characteristics in accordance with table 1 above. TABLE-US-00006
TABLE 6 Ranges of formulations for the spirit 100LL starting with
industrial bases, for various lead contents and several values of
the minimum NHC INDUSTRIL BASES NHC (ASTM D4529) >=43.5
>=43.0 >=42.8 >=42.2 >=41.3 >=39.1 Pb content %
relaxation (g/l of fuel) 0 -1% -2% -3% -5% -10% 0.00 D0 D0 D0 D0 D0
D0 0.08 D0 D0 D0 D0 D0 D0 0.09 D0 D0 D0 D0 D0 D0 0.10 D0 D0 D0 D0
D0 D0 0.11 D0 D0 D0 D0 D0 D0 0.12 D0 D0 D0 D0 D0 D0 0.13 D0 D0 D0
D0 D0 D0 0.14 D0 D0 D0 D0 D0 D0 0.15 D0 D0 D0 D0 D0 D0 0.16 D0 D0
D0 D0 D0 D0 0.17 D0 D0 D0 D0 D0 D0 0.18 D0 D0 D0 D0 D0 D0 0.24 D0
D0 D0 D0 D0 D0 0.25 D0 D0 D0 D0 D0 D0 0.26 D0 D0 D0 D0 D0 D0 0.27
D1 D4 D7 D9 D12 D13 0.28 D2 D5 D8 D10 D14 0.56 D3 D6 D11 D15 D0
means that there is no possible range of formulation of a spirit
100LL that satisfies the main characteristics of standard ASTM
D910-01.
[0083] It is seen in table 6 that with hydrocarbon bases or
fractions of petroleum origin, generally available in a petroleum
refinery, as defined in table 1, the smallest admissible lead
content to manufacture a fuel that satisfies the standard in force
is 0.27 g/l (D1), irrespective of the adopted value of the minimum
NHC of between 43.5 and 39.1 MJ/kg (D4, D7, D9, D12 and D13).
2/Purified Bases
[0084] The physicochemical characteristics of the bases B1, B2 and
B3 are given in table 4 above. TABLE-US-00007 TABLE 7 Ranges of
formulations for the spirit 100LL starting with purified bases, for
various lead contents and several values of the minimum NHC
PURIFIED BASES NHC (ASTM D4529) >=43.5 >=43.0 >=42.8
>=42.2 >=41.3 >=39.1 Pb content % relaxation (g/l of fuel)
0 -1% -2% -3% -5% -10% 0.00 D0 D0 D0 D0 D0 D0 0.08 D0 D0 D0 D0 D0
D0 0.09 D0 D0 D19 D26 D38 D39 0.10 D0 D8 D20 D27 D40 0.11 D0 D9 D21
D28 D41 0.12 D0 D10 D22 D29 D42 0.13 D0 D11 D23 D30 D43 0.14 D1 D12
D24 D31 D44 0.15 D2 D13 D25 D32 D45 0.16 D3 D14 D33 D46 0.17 D4 D15
D34 D47 0.18 D5 D16 D35 D48 0.28 D6 D17 D36 D49 0.56 D7 D18 D37 D50
D0 means that there is no possibility of formulating a spirit 100LL
that satisfies the main characteristics of standard ASTM
D910-01.
[0085] It is seen in table 7 that, with purified products, as
defined in table 4 above, it is possible to formulate an aviation
spirit containing 0.14 g/l of lead (D1), while at the same time
satisfying the characteristics defined in the standard in force for
aviation spirit 100LL. Furthermore, this minimum lead content
reaches 0.10 g/l (D8) when the value of the minimum NHC is reduced
to 43.0 MJ/kg (1% relaxation), it is 0.09 g/l (D19) for a minimum
NHC value of 42.6 MJ/kg (2% relaxation) and less, down to 39.1
MJ/kg (10% relaxation). The fact of characterizing the minimum NHC
1% below the value of the current standard makes it possible to
reduce the lead content by about 28%, and this reduction is 36%
when the minimum NHC is relaxed by 2% and more.
[0086] The fuels thus manufactured in accordance with the invention
have various advantages, alone or in combination: [0087] they have
a high octane number, thus corresponding to the F4 and MON octane
number specification for aviation spirit 1OOLL, without the need to
add additional octane-providing additives; [0088] they are
environmentally friendly, since they contain a smaller amount of
organolead and scavenger compounds; [0089] they are less expensive
to manufacture; [0090] they make it possible to reduce the
pollution impact of lead on the health of living beings; [0091]
finally, they are compatible with the other equivalent
hydrocarbons.
* * * * *