Field of the Invention
[0001] The present invention relates to a gasoline composition and its use, particularly,
in combustion engines.
Background of the Invention
[0002] Spark initiated internal combustion gasoline engines require fuel of a minimum octane
level which depends upon the design of the engine. Petroleum refineries are constantly
faced with the challenge of continually improving their products to meet increasingly
severe governmental efficiency and emission requirements, and consumers' desires for
enhanced performance. For example, in producing a fuel suitable for use in an internal
combustion engine, petroleum producers blend a plurality of hydrocarbon containing
streams to produce a product that will meet governmental combustion emission regulations
and the engine manufacturers performance fuel criteria, such as research octane number
(RON). Similarly, engine manufacturers conventionally design spark ignition type internal
combustion engines around the properties of the fuel. For example, engine manufacturers
endeavor to inhibit to the maximum extent possible the phenomenon of auto-ignition
which typically results in knocking and, potentially engine damage, when a fuel with
insufficient knock-resistance is combusted in the engine.
[0003] Under typical driving situations, engines operate under a wide range of conditions
depending on many factors including ambient conditions (air temperature, humidity,
etc.), vehicle load, speed, rate of acceleration, and the like. Fuel blenders have
to design products which perform well under such diverse conditions. This naturally
requires compromise, as often times fuel properties or engine parameters that are
desirable under certain speed/load conditions prove detrimental to overall performance
at other speed/load conditions. It is desirable to provide high burn velocity fuel,
particularly for use under lean conditions to shorten the burn duration and thereby
improve the thermodynamic efficiency. A faster burn velocity also serves to maximize
conversion of the fuel, thereby increasing the overall fuel economy and reducing emissions.
Thus, the flame speed (related to burning velocity) of combustible fuel plays an important
role in fuels chemistry and in the performance of engines (power) and emissions from
spark-ignition engines.
[0004] US 7517215 B1 describes a method for distributed ignition wherein a combustion fuel and an ignition
mixture are combined. The ignition mixture comprises ignition agents and fuel and
where ignition agents can be nano-metallic particles in combination with single-walled
carbon nano-tubes (SWCNTs).
[0005] US 5354344 A describes a fuel oil composition for use in a spark ignition engine, which comprises
conventional gasoline for spark ignition engine use and a compound selected from the
group consisting of an alkynyl alcohol, alkynyl ether, alkynyl ketone, alkenyl aldehyde
or an acetal thereof, furan or a furan compound, and an alkenyl ether.
[0006] WO 2008/071628 A1 describes a method of increasing the sensitivity (RON - MON) of a gasoline composition
comprising admixing with a gasoline base fuel from 1 to 20 vol.%, based on total volume
of the gasoline composition, of a nitroalkane selected from the group consisting of
nitroethane, nitropropane and mixtures thereof; and use of such a gasoline composition
for improved operation of a homogeneous charge compression ignition (HCCI) engine
over a range of load conditions.
Summary of the Invention
[0007] In accordance with a first aspect, the present invention provides a gasoline composition
comprising (a) a major amount of a mixture of hydrocarbons in the gasoline boiling
range and (b) a minor amount of cyclopropyl acetylene, wherein the term 'minor amount'
means less than 50% by weight of the total fuel composition.
[0008] In another aspect, the present invention provides a method of (i) improving the flame
speed of a gasoline and/or (ii) increasing sensitivity of a gasoline, which method
comprises adding to a major portion of a gasoline mixture minor amounts of cyclopropyl
acetylene, wherein the term 'minor amount' means less than 50% by weight of the total
fuel composition.
Brief Description of the Drawing
[0009]
Fig. 1 represents the Schlieren images of single combustion event 30ms after ignition
of Base Fuel-1 plus 20% Cyclopropylacetylene.
Fig. 2 represents the Schlieren images of single combustion event 30ms after ignition
of Base Fuel-1 only.
Fig. 3 represents improvement in Hyundai Acceleration Performance of the Faster Flame
Speed fuel blends versus Base Fuel - 2 (reference fuel); all additive concentrations
in ppmw.
Detailed Description of the Invention
[0010] We have found that the blended fuel composition described above significantly enhance
the flame speed of gasoline fuels without compromise in RON. In an ideal case, flame
speed is the measured rate of expansion of the flame front, generally measured in
meters/second (m/s). In a spark engine, flame speed depends on gas pressure, temperature,
and density change as a result of changes in volume due to piston motion (see
Internal Combustion Engine Fundamentals, John B. Heywood. McGraw-Hill Book Co., 1988). Thus, "rate of expansion of the flame front" can also be measured by the increase
in the pressure. Early pressure rise after spark (at 0 seconds) is also a measure
of high burning velocity.
[0011] The gasoline composition of the present invention contains component (b) of a minor
amount of cyclopropyl acetylene, wherein the term 'minor amount' means less than 50%
by weight of the total fuel composition. Cyclopropyl acetylene includes an acetylenic
group and the term "acetylenic group" refers to unsaturated hydrocarbons that have
carbon atoms in chains linked by one or more triple bonds. The component (b) is a
compound having the formula:
wherein n is 0 and R
1 to R
6 are independently hydrogen. In an embodiment not claimed here, n could be an integer
from 0 to 7; R
1 to R
6 could independently be hydrogen, alkyl group having 1 to 7 carbon atoms, alkenyl
group having 1 to 7 carbon atoms, alkynyl group having 1 to 7 carbon atoms, cyclic
group having 1 to 7 carbon atoms, with the proviso that the total number of carbon
atoms in the compound are from 5 to 12.
[0012] Some of these cyclopropyl group-containing acetylenic compounds are available from
GSF Chemicals Corporation and Sigma-Aldrich Company Ltd. Various synthetic routes
can be used in the preparation of cyclopropyl group-containing acetylenic compounds.
For example, cyclopropylacetylene can be prepared by chlorination of acetylcyclopropane
with PCl
5 in the presence of an organic base in a chlorinated hydrocarbon with dehydrochlorination
of the mixture of alpha,-alpha dichlorocyclopropane and alpha-chlorovinylcyclopropane
(with base at reflux in a solvent) and simultaneous distillation. (see Dolgii, I.
E.; Shvedova, I. B.; Shavrin, K. N.; Nefedov, O. M. (Zelinskii, N. D., Institute of
Organic Chemistry, USSR). U.S.S.R. (1977)) Dicyclopropylacetylenic derivatives can
be prepared using Favorskii reaction and common organic systhesis procedure (
Nefedov, O. M.; Dolgii, I. E.; Shvedova, I. B.; Baidzhigitova, E. A. Inst. Org. Khim.
Im. Zelinskogo, Moscow, USSR. Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1978),
(6), 1339-44.) Cycopropyl Cyanide can be prepared by the reaction of sodium amide with chlorobutyronitrile
(
Organic Syntheses, Volume 3, page 223. John Wiley & Sons, Inc. Submitted by M. J.
Schlatter and checked by R. L. Shriner and Chris Best). Other methods can be used to prepare the cyclopropyl group-containing acetylenic
compounds useful in the invention as are known to one who is skilled in the art of
organic synthesis. Examples of cyclopropyl group-containing acetylenic compounds include,
for example, cyclopropyl acetylene; 1-cyclopropyl-1-propyne; 1-cyclopropyl-2-propyne;
1-methyl-1-ethynyl-cyclopropane; 2-methyl-1-ethynyl-cyclopropane; 1,1-(3-methylene-1-propyne-1,3-diyl)bis-;
1,1-bicyclopropyl, 2,2-diethynyl-; 1-cyclopropylpenta-1,3-diyne; cyclopropane, 1,1-(1,3-butadiyne-1,4-diyl)bis-;
cyclopropane, 1,1-(3-methyl-1-propyne-1,3-diyl)bis-; and 1,4-dicyclopropylbuta-1,3-diyne.
[0013] The fuel composition of the present invention comprises a major amount of a mixture
of hydrocarbons in the gasoline boiling range and a minor amount of component (b).
As used herein for component (b), the term "minor amount" means less than 50% by weight
of the total fuel composition, preferably less than about 30% by weight of the total
fuel composition. However, the term "minor amount" will contain at least some amount,
preferably at least 0.001% by weight of the total fuel composition.
[0014] An effective amount of component (b), more particularly cyclopropyl acetylene, is
introduced into the combustion zone of the engine in a variety of ways to improve
flame speed. As mentioned, a preferred method is to add a minor amount of component
(b) to the fuel. For example, component (b) may be added directly to the fuel or blended
with one or more carriers to form an additive concentrate which may then be added
at a later date to the fuel.
[0015] The amount of component (b) used will depend on the particular variation of Formula
I used, the engine, the fuel, and the presence or absence of carriers and additional
detergents. Generally, component (b) is added in an amount up to about 20% by weight,
especially from about 0.005% by weight, more preferably from about 0.05% by weight,
even more preferably from about 0.5% by weight, most preferably from about 1% by weight,
based on the total weight of the fuel composition.
[0016] Suitable liquid hydrocarbon fuels of the gasoline boiling range are mixtures of hydrocarbons
having a boiling range of from about 25°C to about 232°C and comprise mixtures of
saturated hydrocarbons, olefinic hydrocarbons and aromatic hydrocarbons. Preferred
are gasoline mixtures having a saturated hydrocarbon content ranging from about 40%
to about 80% by volume, an olefinic hydrocarbon content from 0% to about 30% by volume
and an aromatic hydrocarbon content from about 10% to about 60% by volume. The base
fuel is derived from straight run gasoline, polymer gasoline, natural gasoline, dimer
and trimerized olefins, synthetically produced aromatic hydrocarbon mixtures, or from
catalytically cracked or thermally cracked petroleum stocks, and mixtures of these.
The hydrocarbon composition and octane level of the base fuel are not critical. The
octane level, (R+M)/2, will generally be above about 85. Any conventional motor fuel
base can be employed in the practice of the present invention. For example, hydrocarbons
in the gasoline can be replaced by up to a substantial amount of conventional alcohols
or ethers, conventionally known for use in fuels. The base fuels are desirably substantially
free of water since water could impede a smooth combustion.
[0017] The word major amount is used herein because the amount of hydrocarbons in the gasoline
boiling range is often 50 weight or volume percent or more.
[0018] Normally, the hydrocarbon fuel mixtures to which the invention is applied are substantially
lead-free, but may contain minor amounts of blending agents such as methanol, ethanol,
ethyl tertiary butyl ether, methyl tertiary butyl ether,tert-amyl methyl ether and
the like, at from about 0.1% by volume to about 15% by volume of the base fuel, although
larger amounts may be utilized. The fuels can also contain conventional additives
including antioxidants such as phenolics, e.g., 2,6-di-tertbutylphenol or phenylenediamines,
e.g., N,N'-di-sec-butyl-p-phenylenediamine, dyes, metal deactivators, dehazers such
as polyester-type ethoxylated alkylphenol-formaldehyde resins. Corrosion inhibitors,
such as a polyhydric alcohol ester of a succinic acid derivative having on at least
one of its alpha-carbon atoms an unsubstituted or substituted aliphatic hydrocarbon
group having from 20 to 50 carbon atoms, for example, pentaerythritol diester of polyisobutylene-substituted
succinic acid, the polyisobutylene group having an average molecular weight of about
950, in an amount from about 1 ppm (parts per million) by weight to about 1000 ppm
by weight, may also be present.
[0019] The fuel compositions of the present invention may also contain one or more detergents.
When detergents are utilized, the fuel composition will comprise a mixture of a major
amount of hydrocarbons in the gasoline boiling range as described hereinbefore, a
minor amount of component (b) as described hereinbefore and a minor amount of one
or more detergents. As noted above, a carrier as described hereinbefore may also be
included. As used herein for detergents, the term "minor amount" means less than about
10% by weight of the total fuel composition, preferably less than about 1% by weight
of the total fuel composition and more preferably less than about 0.1% by weight of
the total fuel composition. The one or more detergents are added directly to the hydrocarbons,
blended with one or more carriers, blended with component (b), or blended with component
(b) and one or more carriers before being added to the hydrocarbon. The compound of
component (b) can be added at the refinery, at a terminal, at a depot, at a retail
site, or by the consumer.
[0020] The treat rate of the fuel additive detergent packages that contains one or more
detergents in the final fuel composition is generally in the range of from about 0.007
weight percent to about 0.76 weight percent based on the final fuel composition. The
fuel additive detergent package may contain one or more detergents, dehazer, corrosion
inhibitor and solvent. In addition a carrier fluidizer may sometimes be added to help
in preventing intake valve sticking at low temperature.
[0021] While the invention is susceptible to various modifications and alternative forms,
specific embodiments thereof are shown by way of examples herein described in detail.
It should be understood, that the detailed description thereto are not intended to
limit the invention to the particular form disclosed, but on the contrary, the intention
is to cover all modifications, equivalents and alternatives falling within the scope
of the appended claims. The present invention will be illustrated by the following
illustrative embodiment, which is provided for illustration only and is not to be
construed as limiting the claimed invention in any way.
Octane Test Methods
[0022] The Research Octane Number (RON) (ASTM D2699) and Motor Octane Number (MON) (ASTM
D2700) will be the techniques used in determining the R+M/2 octane of the fuel. The
RON and MON of a spark-ignition engine fuel is determined using a standard test engine
and operating conditions to compare its knock characteristic with those of primary
reference fuel blends of known octane number. Compression ratio and fuel-air ratio
are adjusted to produce standard knock intensity for the sample fuel, as measured
by a specific electronic detonation meter instrument system. A standard knock intensity
guide table relates engine compression ratio to octane number level for this specific
method. The specific procedure for the RON can be found in ASTM D-2699 and the MON
can be found in ASTM D-2700.
[0023] Table I contains the engine conditions necessary in determine the RON and MON of
a fuel.
Table I
RON and MON Test Conditions |
Test Engine Conditions |
Research Octane Number |
Motor Octane Number |
Test Method |
ASTM D-2699-92 |
ASTM D-2700-92 |
Engine |
Cooperative Fuels Research (CFR) Engine |
Cooperative Fuels Research (CFR) Engine |
Engine RPM |
600 RPM |
900 RPM |
Intake Air |
Varies with Barometric |
38°C |
Temperature |
Pressure (eq 88kPA=19.4 °C, 101.6kPa = 52.2 °C) |
|
Intake Air Humidity |
3.56 - 7.12 g H2O/kg dry air |
3.56 - 7.12 g H2O/kg dry air |
Intake mixture temperature |
not specified |
149 °C |
Coolant Temperature |
100 °C |
100 °C |
Oil Temperature |
57 °C |
57 °C |
Ignition Advance-fixed |
13 degrees BTDC |
Varies with compression ratio (eq 14-26 degrees BTDC) |
Carburetor Venture |
Set according to engine altitude (eq 0 - 500 m = 14.3, 500 - 1000 m = 15.1 mm) |
14.3 mm |
Flame Speed Test Method
[0024] Flame Speed of the fuels were tested with Leeds Combustion Bomb Method as described
in SAE Technical Paper Series 2000-01-0192, Aspects of Laminar and Turbulent Burning
Velocity relevant to SI Engines, by
L.Gillespie, M. Lawes, C.G.W. Sheppard and R. Woolley, SAE 2000 World Congress, Detroit,
Michigan, March 6-9, 2000. Fuels were tested under laminar conditions with initial conditions of 5 bar absolute
pressure and 360K. All the burning velocities were measured at an equivalence ratio
ϕ =1 1 (i.e., stoichiometric). The tests were conducted using the Leeds Mk2 fan stirred
combustion vessel (bomb) a stainless sphere of 30 liter volume and with extensive
optical access. The fuels were injected into the bomb and allowed to vaporize fully,
than a stoichiometric amount of air was added. The gases were mixed with stirring
fans inside the vessel and the contents were heated to the desired temperature. The
fans were turned off prior to ignition. Mixtures were ignited using a spark plug.
Pressure transducers were flush mounted inside the bob and recorded the pressure rise
as a function of time.
Base Fuel
[0025] The base fuel physical properties used in the tests can be found in Table II.
Table II
Base Fuel Physical Properties |
Parameter |
Method |
Units |
Base Fuel-1 |
Base Fuel-2 |
RON |
ASTM D2699 |
|
95.4 |
95.3 |
MON |
ASTM D2700 |
|
86.6 |
86.4 |
Density @ 15 °C |
IP 365 |
g cm-3 |
0.7300 |
0.7293 |
Oxidation Stability (induction) |
IP 40 |
mins |
> 1440 |
|
Unwashed gum |
IP 131 |
mg/100ml |
6 |
8 |
Distillation |
IP 123 |
|
|
|
IBP |
|
°C |
34.9 |
35.7 |
10% rec |
|
°C |
51.8 |
54.9 |
20% rec |
|
°C |
59.9 |
62.5 |
30% rec |
|
°C |
68.1 |
70.6 |
40% rec |
|
°C |
77.8 |
80.6 |
50% rec |
|
°C |
89.7 |
92.7 |
60% rec |
|
°C |
103.1 |
105.7 |
70% rec |
|
°C |
115.6 |
118.4 |
80% rec |
|
°C |
126.7 |
129.6 |
90% rec |
|
°C |
139.6 |
141.3 |
95% rec |
|
°C |
146.9 |
147.9 |
FBP |
|
°C |
167.1 |
171.4 |
Residue |
|
% vol |
1.0 |
1.0 |
Recovery |
|
% vol |
95.5 |
97.8 |
Loss |
|
% vol |
3.5 |
1.2 |
E70 |
|
% vol |
32.0 |
29.1 |
E100 |
|
% vol |
57.9 |
55.7 |
E120 |
|
% vol |
74.0 |
71.4 |
E150 |
|
% vol |
96.3 |
95.7 |
RVP |
IP 394/ASTM 519 |
kPa |
59.8 |
56.0 |
GC |
LTP/26 |
|
|
|
C |
|
|
6.60 |
6.61 |
H |
|
|
12.51 |
12.56 |
O |
|
|
0.00 |
0.00 |
Paraffins |
|
% vol |
7.41 |
7.29 |
Isoparaffins |
|
% vol |
53.84 |
53.90 |
Olefins (including dienes) |
|
% vol |
3.06 |
3.76 |
Dienes |
|
% vol |
0.01 |
0.01 |
Napthenes |
Napthenes % vol |
% vol |
6.28 |
6.14 |
Aromatics |
|
% vol |
29.07 |
28.79 |
Oxygenates |
|
% vol |
0.00 |
0.00 |
Unknowns |
|
% vol |
0.35 |
0.13 |
Total |
|
% vol |
100.01 |
100.01 |
Benzene (+Me Cyc5 ene) |
|
% vol |
0.48 |
0.52 |
Sulphur - WD XRF |
ISO 20884 |
mg/kg |
|
10 |
Sulphur - Antek |
ISO 20846 |
mg/kg |
5 |
|
Examples 1-8
[0026] For examples 1-3, the additives were each added to Base Fuel 1 (Octane 91) at 20%
in weight. These samples were then tested thrice for RON, MON, and flame speed. The
average of three runs was tabulated in Table III. Similar blending method was used
for examples 4-8 with Base Fuel 2 (Octane 91) at concentrations indicated in Table
III.
Table III
Example # |
Base blend |
Additive (in weight %) in Gasoline |
Flamespeed Pressure in bomb(bar) at 0.1s after ignition |
RON |
MON |
(R+M) /2 |
1 |
Base Fuel 1 |
None |
17.35 |
95.4 |
86.6 |
91.0 |
2 |
Base Fuel 1 |
20% of Cyclopropylacetylene |
32.33 |
97.0 |
81.8 |
89.4 |
3 |
Base Fuel 1 |
20% of 1-Pentyne |
26.59 |
93.2 |
81.8 |
87.5 |
4 |
Base Fuel 2 |
None |
21.66 |
95.2 |
86.9 |
91.0 |
5 |
Base Fuel 2 |
5% of Cyclopropylacetylene |
25.09 |
96.1 |
85.3 |
90.7 |
6 |
Base Fuel 2 |
10% of Cyclopropylacetylene |
32.74 |
96.3 |
84.6 |
90.4 |
7 |
Base Fuel 2 |
5% of 1-Pentyne |
24.22 |
95.3 |
85.6 |
90.4 |
8 |
Base Fuel 2 |
10% of 1-Pentyne |
24.36 |
94.9 |
84.9 |
89.9 |
[0027] Addition of molecules containing cyclopropyl and acetylenic groups significantly
enhanced the flame speed of the given fuel composition. The increase in cylinder pressure
compared to the reference fuel after 0.1 seconds after ignition is used as the measure
of the laminar flame speed. Results showed that Cyclopropylacetylene and 1-Pentyne
at blend concentrations of 10% and 5% produced a statistically significant (at 99%)
improvement in chamber pressure compared to the reference fuel. We chose another molecule
with three member ring, without acetylene moiety (carbon triple bond carbon), for
example, Carene. Carene was tested at 20% in Base Fuel 2. This blend showed no statistically
significant improvement in pressure difference compared to the Base Fuel 2 (reference
fuel).
[0028] At a concentration of 20 wt.% Cyclopropylacetylene in the Base Fuel-1 shows the pressure
increase in the combustion chamber 0.1 seconds after ignition of the homogeneous charge
is statistically (>95%) significantly greater than the Base Fuel-1 (reference fuel).
For example, Schlieren images of the combustion, 30ms after the ignition event shown
in the Figures clearly show a large difference in both the flame size and structure
(Cyclopropylacetylene being more cellular). It is noted that at nearly 33ms the flame
for the fuel blend containing cyclopropylacetylene fills the viewing window; the Base
Fuel-1 (reference fuel) takes nearly 38.5ms to fill the viewing window, so it is not
possible to show differences in flame size after this point. Hence the images are
not shown at 100ms (0.1 seconds) after ignition to help corroborate the pressure data.
However, pressure at 0.1 seconds has been tabulated in Table III.
[0029] Cyclopropylacetylene, 1-Pentyne were blended at 0.5% and 1.0% into Base Fuel - 2.
Each fuel blend was tested in a single day along with the reference fuel (base fuel
without the additive) in an A-B-A-B..... type test design on the chassis dynamometer.
A Hyundai Coupe was used for the testing. As this vehicle has shown to be insensitive
to changes in fuel octane the improvements in acceleration performance achieved between
the test and reference fuel are attributed to changes in the laminar flame speed of
the fuel. A standard chassis dynamometer power and acceleration test procedure on
a Hyundai Coupe was used to obtain these results as shown in Figure 3. The figure
shows over 0.2% acceleration performance improvements with 1% cyclopropylacetylene
as an additive as compared to the base fuel without the additive.
[0030] The benefit of this increase in flame speed is best utilized in performance applications
such as racing fuel and premium fuel. Addition of such molecules in fuels typically
results in less pollution, more power and better efficiency. Faster burning fuels
allow engines to run on lean mixtures of gasoline and air, potentially reducing nitrogen
oxide and hydrocarbon emissions. As seen in the above Table, the flame speed of the
cyclopropyl acetylene in gasoline is greatly increased without lowering the RON value.
Further, the fuel composition of the invention increases fuel sensitivity. There are
industry reports that indicate fuel with higher sensitivity (lower MON) has better
anti-knock quality. (see SAE Technical Paper Series 2001-01-3584, Fuel Anti-Knock
quality-Part I. Engine Studies, by G.T. Kalghatgi and SAE Technical Paper Series 2001-01-3585,
Fuel Anti-Knock Quality-Part II. Vehicle Studies -How Relevant is Motor Octane Number
(MON) in Modern Engines, by G.T. Kalghatgi.) An increase in fuel sensitivity increases
the "octane index" of the fuel which is a better measure of the anti-knock quality
of the fuel, and leads to improved power and acceleration performance. As seen from
the above Table III, while RON value of the cyclopropyl acetylene containing formulation
is higher than the reference fuel without the cyclopropyl acetylene, MON value of
the cyclopropyl acetylene containing formulation is lower than the reference fuel
without the cyclopropyl acetylene.