Note: Descriptions are shown in the official language in which they were submitted.
CA 02469766 2004-06-04
DISTILLATE FUEL COMPOSITIONS FOR IMPROVED COMBUSTION ~,,t~_~5~9
AND ENGINE CLEANLINESS
I I (;1_D
The present invention relates to a synergistic interaction bchvcen an
overbased calcium
sulfonate detergent and <tn ashless succinimide dispersant that allows (car
the formulation of
improved distillate fuel additive packages. (n addition to the metallic:
detergent and the ashless
dispcrsant, the additive compositions cont<rin an organometallic complex of
manganese.
Distillate fuels treated with the additive compositions exhibit improved
combustion because of
the detergent and the organomctallic manganese compound and good fuel system
cleanliness
because of the detergent/dispersant interaction.
I3~\C:KGROUND
to i\ great deal of prior art has been devoted to formulating distillate fuel
additive
compositions to provide environmental benefits when the fuel is combusted.
Such benefits
include, liar example. reduced emissions of no;~ious pollutants such as oxides
of nitrogen and
particulate matter. reduced acidity of emitted particulates, and better fuel
economy (which
amounts to lower emissions of carbon dioxide per amount of fuel bcwncd). The
effects of these
t5 fuels on the cleanliness of fuel systems, e_g., on the buildup of carbon
and lacquer on the fuel
injectors found in diesel engines, has received less study.
A need exists for a distillate fuel additive composition that provides for the
simultaneous
achievement of improved combustion, fuel and combustion. system cleanliness,
improved fuel
economy, and reduction in pollutant generation.
SUMMARY OF THE EMBODIMENTS
An embodiment presented herein provides a fuel additive composition comprising
an
organometallic manganese compound, an alkyl-substituted succinimide ashless
dispersant, and an
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overbased calcium sulfonate detergent of TBN above about 200. In another
embodiment the T BN
of the overbased calcium sulfonate is about 300.
Anotf~er embodiment provides a fuel comprising a major amount of a middle
distillate
fuel and a minor amount of a fuel additive composition comprising an
organornetallic manganese
compound, an alkyl-substituted succinimide ashless dispc:rsant, and an
ovcrbased calcium
sulfonate detergent of TBN above about 200.
Accordingly, in one example herein is provided a method of for improving the
cleanliness
of a fuel intake systems by use in the fuel intake system of a fuel containing
a fuel additive
composition comprising an organornetallic manganese compound, an alkyl-
substituted
succinimide ashless dispersant, and an overbased calcium sulfonate detergent
of TBN about 300.
It is to be understood that both the foregoing general description and the
following
detailed description are exemplary and explanatory only and are intended to
provide further
explanation of the present invention. as claimed.
DETAILED DESCRIPTION OF EMBODIMENTS
In one embodiment is provided herein distillate fue~I additive compositions
for use in
distillate firets that provide enhanced fuel combustion and, at the same time,
superior cleanliness of
fuel intake systems. Distillate firels are defined herein as petroleum-based
hydrocarbon fuels
boiling in the range of about 140-3b0°C [284-680°F] and
encompass diesel and biodiesel fuels,
jet fuels, marine fuels and home heating oils. Distillate fuels containing the
additive
compositions of the invention show enhanced combustion characteristics.
If certain components of the additive packages described herein are present in
specific
proportions, fuels containing the additive packages also show excellent fuel
injector cleanliness
3
..,~.~~
CA 02469766 2004-06-04
rr~-~s9n
as measured by the Cummins i_,10 diesel detergency test. ~I his injector
cleanliness is exhibited as
an injector rating of at most 10.0 in the Cummins L10 diesel detergency test.
Other embodiments herein provide an additive composition, a distillate fuel
containing the
additive composition, and a method of improving the cleanliness of fuel intake
systems by use of
the fuel containing the additive composition.
In an embodiment, tile additive composition contains at least an
organometallic complex of
manganese, an overbased calcium sulfonate detergent and an ashless succinimide
dispcrsant such
that when the additive composition is dissolved in a distillate fuel, the
following relationship is
satisfied:
-0.159x + 0.243y - 0.0143xy < -8.4
where
x = concentration of succinimide (in potu~ds per thousand barrels)
y = concentration of overbased calcium sulfonate (in PTB)
t 5 with the following limitations:
x = 20-35, preferably 25-30, and y = 10-120, preferably 30-50.
The organometallic manganese compound does not affect injector cleanliness. In
an
embodiment, the organometallic manganese compound may be present in the fuel
at:
concentrations of up to about 20 PTB.
It has been discovered that the combustion-improving conventional additive
packages
previously known do not necessarily pass the Currunins L 10 diesel detergency
test (where a pass
is defined as an average injector rating of 10.0 or less). To identify the
components in the
additive composition that affect injector ratings, an experimental design was
earned out. A
4
_. ..___. _ . .~_ _
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synergy (i.e. a nOI11117ear (l7tCr7CtIOn~ waS ObSerVed I?etW'f:Pt7 117e
OVerbaSed Ca1C111117 slllfOnatc
detergent and the succinirnide dispersant. This was a surprising result which
is not anticipated by
any prior art.
The results of the experimental design were used to generate a model for
average injector
rating, as follows:
Rating = -0.159x + 0.243y - 0.0143xy + 18.4 ( 1 )
where
x = concentration of succinil7ude (in pounds per thousand barrels, or PTB)
y = concentration of overbased calcium sulfonate (in P'fB)
Since the average injector rating must be 10.0 or lower for a pass in the
Cummins L.10 test, the
equation becomes:
10.0 > -0.159x + 0.243y - 0.0143xy + I 8.4 (2)
or
-0.159x + 0.243y - 0.0143xy <_ -8.4 (3)
IS The detergent/dispersant synergy is represented by the xy term.
The model was validated by the testing of three new formulations that satisfy
the above equation:
1. x = 28 PTB, y = 32 P~rB
2. x = 26 PTB, y = 40 PTB
3. x = 25 PTB, y = 48 PTB
All three formulations gave an average injector rating of below 10.0, in
accordance with the
model. Of course, there are an infinite number of solutions for x and y in
equation 3. Examples
of currently practical solutions are the following ranges:
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EP-7599
x = 20-35, preferably 25-30
y = 10-120, preferably ~0-50
The amount of organometallic manganese compound was shown to have no
significant
adverse effect on injector ratings and is therefore not constrained by the
model represented by
equation 3. As an economic matter only, the amount of manganese compound is,
in an
embodiment, limited to 20 PTl3 or less. The benefits derived from the
inclusion of a manganese
compound are not directly related to injector ratings, hut are much more
prevalent in the areas of
particulate emission reduction, reduced NOX and SOx, reduced hydrocarbons,
improved fuel
economy, and combustion improvement_
Co Especially useful herein is rnethylcyclopentadienylmanganese tricarbonyl
(MMT~) as the
organometallic manganese compound, a succinimide prepared from 850 to 2100-MW
PIBSA and
a polyalkylene polyamine approximating tetraethylenepentamine in composition
as the ashless
dispersant, and an overbased calcium sulfonate of ~I~BN up to about X00 as the
detergent. MMT~
is available from Ethyl Corporation, Riclunond, VA. 'Ihe diesel fuel used in
the Cummins L10
study was a high-sulfur (0.4wgt % sulfur) fuel, but any diesel fuel (including
low-sulfur and
ultralow-sulfur fuels) may be used: A separate LIO experiment has shown that
the addition of 2-
ethylhexyl nitrate cetane impraver to a fuel containing the inventive additive
does not degrade the
detergent performance.
The following examples further illustrate aspects of the present invention but
do not limit
2o the present invention.
EXAMPLES:
Since the Cummins L10 test was designed to evaluate additives and fuels for on-
road use
in North America, HiTEC~-4080 Fuel Additive was used in this example. This
additive is Ethyl
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Corporation's antifoam-free Greenbum u0 road diesel fuel additive package.
used with a
recommended treat rate of 500 ppm (w/w). 'fhe formulation is shown in 'liable
1.
Component % weight ppm COIIIpOtlentPTB component
at 500 ppm at X00 ppm
total total
HiTEC~ 9645 15_34 76.7 22.8
2-ethylhexanol 46.22 23l . I 68.8
Hi'CEC~ 61 I 32.16 160.8 47.9
HiTEC~ 536 0.93 4.7 1.4
D-5 021 0. 97 4. 9 1. 5
HiTEC~ 3062 4.38 21.9 6.6
Table 1. Composition of I~iTEC Iz 4080
For the purposes of this example, the European components D-5021 (demulsifier)
and
HiTEC~ 536 (corrosion inhibitar) were replaced with the North ~mcrican
components Tolad
9310 and 50% dodecenylsuccinic acid, respectively, on an eduivalent weight
basis. These
components were held constant at the above concentrations in e~~ery test. The
components
to expected to have significant effects on Cummins L10 ratings were I-IiTEC~
9645 (a
succinimide-based dispersant), HiTEC~ 611 (overbased calcium sulfonate) and I-
IiTEC~ 3062
(62% MMT~ in aromatic solvent).
The resulting two-level, three-factor (23) design is shown in Figure I; the
numbers along
the axes denote concentrations in PTB.
t5
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48 B+
H-611 C+ 6.6
62
a rs- ~.- a
A- H-9645 A+
0 23
Figure 1. Experimental design for IIi'fECCi> 4080 components
All tests were carried out in the same Cummins L,10 engine anti in the same
batch of
high-sulfur Cat 1K fuel. The test order was randomized. 'fhe results are shown
in Table 2.
Test no. PTB H-9645PTB EI-61PTB EI-3062Avg. flow Avg. CRC
I
_ loss (%) rating
D102-97-1 0 0 6.6 3.2 19.1
D102-98-1 23 0 0 4.2 14.7
D I 02-99-123 0 6.6 2.9 15.3
D102-100-I23 48 0 2.3 9.9
D102-I01-I0 48 6.6 8.9 34.7
~
D I 02-102-111.5 24 3.3 4.1 16.8
D102-103-10 48 0 4.0 25.9
DI02-104-123 48 6.6 3.1 11.9 ~
D i 02-105-10 0 0 1.9 18.2
Table 2. Cummins L10 results for H-4080 experimental design
An analysis of variance (ANOVA) on the data in Table 2 showed that average
flow loss was
io independent of all three factors. The ANOVA for CRC rating is shown below.
Analysis of Variance for CRC
s
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EP-7599
Source Sum of Squares Df Wean Square F-Ratio P-Value
A (I-I-9645) 265.651 I 265.651 29.81 0.0028
B (I-1-G 28.6012 I 28.5012 3.20 0.1337
11 )
AB 124.031 1 124.031 13.92 0.0136
Total error 44.5563 5 8.91125
Total {corn) 462.74 8
R-squared = 90.3712 percent
R-squared (adjusted for d.f,) = 84.5939 percent
Standard Error of Est. = 2.98517
Mean absolute error = 1.55556
Durbin-Watson statistic = 2.10796
Iii'CEC~ 3062 and the higher-order terms AC, BC and ABC were significant at
less than
the 85% confidence level and are therefore excluded. 'the model coefficients
are as follows:
Regression
coeffs.
for CRC
______________________________________________________________________
constant = 18.4375
A {H-9645) _ -0.158696
B (H-G 1 = 0.242708
i )
AB = -0.0142663
The regression coefficients show that HiTEC~ 9645 unexpectedly decreases the
CRC
response (a beneficial effect, since lower CRC ratings indicate less injector
depositing), while
HiTEC~ 61 I increases the ratings. 'flrere is a significant negative
interaction between HiTEC~
9645 and I-IiTEC~ 611, meaning that the deleterious effect of 1-IiTEC~ 611 on
CRC rating at
low concentrations of dispersant is more than cancelled out at high dispersant
concentrations. In
other words, HiTEC~ 611 improves CRC ratings when in the presence of high
amounts of
HiTEC~ 9645. This effect is shown graphically by the interaction diagram in
Figure 2.
Ordinarily, a p-value of 0.13 would result in HiTEC~ 611 alone being excluded
from the model:
this value indicates that the coefficient is different from zero only at the
87% confidence level.
9
>._ ~:~.: .-nn~~.~.~.~--. ~.~ _._.._ ~_..~.._ _ . . .~.. _ .----
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EP-7599
However, if the model contains an interaction between Ivi'I'I:C~ c)645 and I-
li'rEC~ 61 I, the
I-IiTEC~ 61 1 term should also be included to preserve model hierarchy.
34.7
A 30.6
c
t
a 26.4
a
22.3
C
R
C 18.2
14.0
9.9
A- A+
Figure 2. Interaction of A:H-9645 and B:EI-611
t0 FORMULATION OF MODIa IED DISPERSANT PACKAGES TO PASS THE CUMMINS
L 10 TEST
From the model developed above, it is therefore possible to adjust the
components in, for
example, HiTEC~ 4080 in order to hit a desired CRC target. As mentioned
previously, the
maximum CRC rating for a Cummins L 10 pass is I0Ø Constant response curves
for CRC as a
function of HiTEC~ 9645 and HiTEC~ 611 concentrations (in PTB) are shown in
Figure 3.
i0
.. ., .x .srrac,r.v~.-~. ., ~ n... n.. .~..,..- .-_--. , ._.,_..... .... ._ ,
x" ~,~r ~.~,~.~",.~,. ,.~".,....._- . .._.,.......
_..,..._.,.,._:,.."..,.....__- _._,.._."."."",.~nj,,~,"n. ~~.L,
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C'RC
__ 9 0
_.... X0.0
CIO
Figure 3. Contours of estimated response surfaces for CI2C rating
Based on the above model for CRC, any combination of I-li'CECOO 9645 and HiTEC
61 1
to the right of the 10.0 contour (the dashed line) in Figure 3 should give a
passing
Cummins I,10 rating. 'Chree points were selected on t:he 9.0 contour (the
solid line) in the
L10 test. The additive combinations corresponding to these points were:
1. 28 PTB 1-Ii'rEC~ 9645 + 32 fTB 1-IiTEC~ 611
Io 2. 26 PTB HiTEC~ 9645 + 40 PTB HiTEC~ 611
3. 25 PTB HiTEC~ 9645 + 48 PTB HiTEC~ 61 I
All three packages also contained 6.6 PTB of Ethyl's MMT~ as I-IiTEC~ 3062
plus solvent,
demulsifier and corrosion inhibitor as described above. The resulting Cummins
L10 data are
shown in Table 3.
Modified package Test no. Avg_flow loss Avg. CRC rating
(%)
1 D 102-x 07-2 2.0 8.6
2 D 102-107-1 3.1 8.5
3 D 102-109- i 3.3 9.9
Table 3. Cummins L10 results for modified versions of H1TEC~ 4080
As expected from the above model and calculations, all three packages pass the
Cummins L10
test.
A simple 23 experimental design has determined the quantitative effects of
various
components in a Greenburn~ Diesel Fuel Additive package on Cummins L 10
performance. It
II
,____ .,r ,~~. ""K. . ....~. ~._,.~x.T..., ........ _.. "~x~,~,"_y:_=
,;,~i,~,.~,v,~~,A,.,.. . ...~ ._._.~,~~m~,-. __._ ._. . __..._.____
_._~___.... ___._....____
. . ~ ~ . .. _ .. ~. .~...
20 24 ZS 32
I-I-9645
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Et'-?599
was found that the succinimide dispersant (lfiT'EC~ 9645) had a beneficial
effect on injector
ratings, while the overbased calcium sulfonate detergent (1-Ii'fI;C~ 61 1)
harmed those ratings. In
addition, a strong interaction between these two components was observed which
reduced the
undesirable effect of the detergent. MMTC~ (as HiTEC~ 3062) had no significant
effect on
injector cleanliness. The model derived from the experimental design w<is used
to formulate
modified Greenburn 0-type packages that passed the Cummins LIO test.
Other embodiments of the present invention will be apparent to those skilled
in the art
from consideration of the spe<:ification and practice of the invention
disclosed herein. As used
throughout the specification and claims, "a" and/or "an'' may refer to one or
more than one.
t0 Unless otherwise indicated, all numbers expressing quantities of
in~;redients, properties such as
molecular weight, percent, ratio, reaction conditions. and so forth used in
the specification and
claims are to be understood as being modified in all instances by the term
"about." Accordingly,
unless indicated to the contrary, the numerical parameters set forth in the
specification and
claims are approximations flat may vary depending upon the desired properties
sought to be
i5 obtained by the present invention. At the very least, and not as an attempt
to limit the application
of the doctrine of equivalents to the scope of the claims, each numerical
parameter should at least
be construed in light of the number of reported significant digits and by
applying ordinary
rounding techniques. Notwithstanding that the numerical ranges and parameters
setting forth the
broad scope of the invention are approximations, the numerical values set
forth in the specific
2o examples are reported as precisely as possible. Any nurner~ical value,
however, inherently
contains certain errors necessarily resulting from the standard deviation
found in their respective
testing measurements. It is intended that the specification and examples be
considered as
12
_. . . . ~ ~ ..~.. v ,. ,~~.»"~.w. , .., " '. ,~.,......_ __ ~.~,~,~ » ,
4~~",.,~. _. .,..~.,m~._.._. ....._... ~.. ,h .".mw.._. __~,. ,~~.~
~.~,..,~~,..."~a~,e~.
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exemplary only, with a true scope and spirit of the invention being indicated
by the following
claims.
13
