U.S. patent application number 12/793463 was filed with the patent office on 2010-12-30 for additives for cetane improvement in middle distillate fuels.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to Paul J. Biggerstaff, Jianzhong Yang, Michael J. Zetlmeisl.
Application Number | 20100325944 12/793463 |
Document ID | / |
Family ID | 45067232 |
Filed Date | 2010-12-30 |
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United States Patent
Application |
20100325944 |
Kind Code |
A1 |
Yang; Jianzhong ; et
al. |
December 30, 2010 |
Additives for Cetane Improvement in Middle Distillate Fuels
Abstract
The cetane number of middle distillate fuels may be increased
using an additive composition including a polymer that may be a
homopolymer or copolymer of olefins, and the like, where the
polymer has a weight average molecular weight ranging from about
200,000 to about 5,000,000. The additive composition also includes
a free radical initiator component, which may be an alkyl nitrate
such as 2-ethylhexylnitrate (2-EHN), and/or a peroxide, such as
t-butyl peroxide. In one non-limiting embodiment the amount of
polymer in the additive composition is greater than the free
radical initiator component. A solvent is also present, which the
solvent may include alcohol, an alkyl substituted phenol and/or a
heavy aromatic distillate.
Inventors: |
Yang; Jianzhong; (Missouri
City, TX) ; Zetlmeisl; Michael J.; (Katy, TX)
; Biggerstaff; Paul J.; (Sugar Land, TX) |
Correspondence
Address: |
Mossman, Kumar and Tyler, PC
P.O. Box 421239
Houston
TX
77242
US
|
Assignee: |
Baker Hughes Incorporated
Houston
TX
|
Family ID: |
45067232 |
Appl. No.: |
12/793463 |
Filed: |
June 3, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12128918 |
May 29, 2008 |
|
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12793463 |
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60940914 |
May 30, 2007 |
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Current U.S.
Class: |
44/322 ; 44/325;
44/326 |
Current CPC
Class: |
C10L 1/1832 20130101;
C10L 10/12 20130101; C10L 10/02 20130101; C10L 1/1824 20130101;
C10L 1/1857 20130101; C10L 1/1616 20130101; C10L 1/231 20130101;
C10L 1/143 20130101; C10L 1/1811 20130101; C10L 1/183 20130101;
C10L 1/1641 20130101 |
Class at
Publication: |
44/322 ; 44/326;
44/325 |
International
Class: |
C10L 1/18 20060101
C10L001/18; C10L 1/23 20060101 C10L001/23 |
Claims
1. A method for improving the cetane number of a middle distillate
fuel comprising adding to the distillate fuel an effective amount
of an additive composition for improving the cetane number of the
middle distillate fuel, the additive composition comprising: a
polymer selected from the group consisting of homopolymers and
copolymers of olefins, and mixtures thereof, where the polymer has
a weight average molecular weight ranging from about 200,000 to
about 5,000,000; a free radical initiator component selected from
the group consisting of an alkyl nitrate, a peroxide, and
combinations thereof; and an alcohol.
2. The method of claim 1 where: the amount of the free radical
initiator component ranges from about 50 to about 4000 ppm based on
the total distillate fuel; the amount of the polymer ranges from
about 0.01 to about 20,000 ppm based on the total distillate fuel;
and the amount of the alcohol ranges from about 1 to about 60 vol %
based on the additive composition.
3. The method of claim 1 where the alcohol is selected from the
group consisting of linear or branched alcohols having 2 to 18
carbon atoms and which may be substituted with oxygen, nitrogen or
sulfur.
4. The method of claim 1 where the additive composition further
comprises a component selected from the group consisting of an
alkyl substituted phenol, an alkyl substituted quinone and an alkyl
substituted hydroquinone antioxidant and mixtures thereof, and a
solvent selected from the group consisting of kerosene, a heavy
aromatic distillate and D-2 diesel, and mixtures thereof.
5. The method of claim 1 where the cetane number of the middle
distillate fuel is the same as or greater than the cetane number
achieved when in the additive composition the free radical
initiator component is present at the same total additive dosage
level for both the polymer and the free radical initiator component
and no polymer is present.
6. The method of claim 1 where the middle distillate fuel has
reduced NOx emissions as compared to an otherwise identical fuel
with an additive composition at the same dosage level where: only
the free radical initiator component is substituted for both the
free radical initiator component and the polymer component or only
the polymer component is substituted for both the free radical
initiator component and the polymer component, where the free
radical initiator component is an alkyl nitrate.
7. A method for improving the cetane number of a middle distillate
fuel comprising adding to the middle distillate fuel an additive
composition comprising: from about 0.01 to about 20,000 ppm, based
on the total distillate fuel, of a polymer selected from the group
consisting of homopolymers and copolymers of olefins and mixtures
thereof, where the polymer has a weight average molecular weight
ranging from about 200,000 to about 5,000,000; from about 50 to
about 4000 ppm, based on the total distillate fuel, of an alkyl
nitrate; and from about 1 to about 60 vol %, based on the additive
composition, of an alcohol selected from the group consisting of
linear or branched alcohols having 2 to 18 carbon atoms and which
may be substituted with oxygen, nitrogen or sulfur.
8. The method of claim 7 where the additive composition further
comprises a component selected from the group consisting of an
alkyl substituted phenol, an alkyl substituted quinone and an alkyl
substituted hydroquinone antioxidant and mixtures thereof, and a
solvent selected from the group consisting of kerosene, a heavy
aromatic distillate and D-2 diesel, and mixtures thereof.
9. The method of claim 7 where the cetane number of the middle
distillate fuel is the same as or greater than the cetane number
achieved when in the additive composition the free radical
initiator component is present at the same total additive dosage
level for both the polymer and the free radical initiator component
and no polymer is present.
10. An additive composition for improving the cetane number of
middle distillate fuels comprising: a polymer selected from the
group consisting of homopolymers and copolymers of olefins and
mixtures thereof, where the polymer has a weight average molecular
weight ranging from about 200,000 to about 5,000,000; a free
radical initiator component selected from the group consisting of
an alkyl nitrate, a peroxide, and combinations thereof; and an
alcohol selected from the group consisting of linear or branched
alcohols having 2 to 18 carbon atoms and which may be substituted
with oxygen, nitrogen or sulfur.
11. The additive composition of claim 10 where the volume ratio of
polymer to the free radical initiator component ranges from about
100:1 to about 1:100.
12. The additive composition of claim 10 where the amount of
alcohol ranges from about 1 to about 60 vol %.
13. The additive composition of claim 10 where the free radical
initiator component is an alkyl nitrate selected from the group
consisting of 2-ethylhexyl nitrate (2-EHN), iso-propyl nitrate,
iso-amylnitrate, iso-hexylnitrate, cyclohexyl nitrate, dodecyl
nitrate, diglycol nitrate and tetraglycol nitrate.
14. The additive composition of claim 10 further comprising a
component selected from the group consisting of an alkyl
substituted phenol, an alkyl substituted quinone and an alkyl
substituted hydroquinone antioxidant, and a solvent selected from
the group consisting of kerosene, a heavy aromatic distillate and
D-2 diesel, and mixtures thereof.
15. A middle distillate fuel comprising: a middle distillate fuel
selected from the group consisting of diesel fuel, heating oil, jet
fuel, and kerosene; and an effective amount of an additive
composition for improving the cetane number of the middle
distillate fuel comprising: a polymer selected from the group
consisting of homopolymers and copolymers of olefins, and mixtures
thereof, where the polymer has a weight average molecular weight
ranging from about 200,000 to about 5,000,000; a free radical
initiator component selected from the group consisting of an alkyl
nitrate, a peroxide, and combinations thereof; and an alcohol.
16. The middle distillate fuel of claim 15 where: the amount of the
free radical initiator component ranges from about 50 to about 4000
ppm based on the total distillate fuel; and the amount of the
polymer ranges from about 0.01 to about 20,000 ppm based on the
total distillate fuel; and the amount of the alcohol ranges from
about 1 to about 60 vol % based on the additive composition.
17. The middle distillate fuel of claim 15 where the free radical
initiator component is an alkyl nitrate selected from the group
consisting of 2-ethylhexyl nitrate (2-EHN), iso-propyl nitrate,
iso-amylnitrate, iso-hexylnitrate, cyclohexyl nitrate, dodecyl
nitrate, diglycol nitrate and tetraglycol nitrate.
18. The middle distillate fuel of claim 15 where the cetane number
of the middle distillate fuel is the same as or greater than the
cetane number achieved when in the additive composition the free
radical initiator component is present at the same total additive
dosage level for both the polymer and the free radical initiator
component and no polymer is present.
19. The middle distillate fuel of claim 15 where the additive
composition further comprises a component selected from the group
consisting of an alkyl substituted phenol, an alkyl substituted
quinone and an alkyl substituted hydroquinone antioxidant and
mixtures thereof, and a solvent selected from the group consisting
of kerosene, a heavy aromatic distillate and D-2 diesel, and
mixtures thereof.
20. A middle distillate fuel comprising: a middle distillate fuel
selected from the group consisting of diesel fuel, heating oil, jet
fuel and kerosene; and an effective amount of an additive
composition for improving the cetane number of the middle
distillate fuel comprising a polymer selected from the group
consisting of homopolymers and copolymers of olefins, and mixtures
thereof, where the homopolymer has a weight average molecular
weight ranging from about 200,000 to about 5,000,000; an alkyl
nitrate; and an alcohol where the cetane number of the middle
distillate fuel is the same as or greater than the cetane number
achieved when in the additive composition the free radical
initiator component is present at the same total additive dosage
level for both the polymer and the free radical initiator component
and no polymer is present.
21. The middle distillate fuel of claim 20 where: the amount of the
alkyl nitrate ranges from about 50 to about 4000 ppm based on the
total distillate fuel; the amount of the polymer ranges from about
0.01 to about 20,000 ppm based on the total distillate fuel; and
the amount of the alcohol ranges from about 1 to about 60 vol %
based on the additive composition, all based on the total
distillate fuel.
22. The middle distillate fuel of claim 20 where the alkyl nitrate
is selected from the group consisting of 2-ethylhexyl nitrate
(2-EHN), iso-propyl nitrate, iso-amylnitrate, iso-hexylnitrate,
cyclohexyl nitrate, dodecyl nitrate, diglycol nitrate and
tetraglycol nitrate.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part application from
U.S. Ser. No. 12/128,918 filed May 29, 2008, which is incorporated
herein by reference, and which in turn claims the benefit of U.S.
Provisional Patent Application No. 60/940,914 filed May 30,
2007.
TECHNICAL FIELD
[0002] The present invention relates to additives for middle
distillate fuels, such as diesel, and more particularly relates, in
one embodiment to methods for improving the cetane number of middle
distillate fuels using chemical additives.
TECHNICAL BACKGROUND
[0003] Cetane number is a measurement of the combustion quality of
middle distillate fuels during compression ignition. Middle
distillate fuels include heating oil, diesel, kerosene, jet fuel
and the like. It is a significant expression of middle distillate
fuel quality among a number of other measurements that determine
overall middle distillate fuel quality. The cetane number is a
measure of a fuel's ignition delay; the time period between the
start of injection and start of combustion (ignition) of the fuel.
In a particular diesel engine, higher cetane fuels will have
shorter ignition delay periods than lower cetane fuels. Generally,
diesel engines run well with a cetane number from 40 to 55. Fuels
with higher cetane number which have shorter ignition delays
provide more time for the fuel combustion process to be completed.
Hence, higher speed diesels operate more effectively with higher
cetane number fuels. There is no performance or emission advantage
when the cetane number is raised past approximately 55; after this
point, the fuel's performance hits a plateau.
[0004] Known cetane improvers include nitrates, peroxides,
nitrites, azo compounds and the like and combinations thereof.
Alkyl nitrates, especially 2-ethylene hexyl nitrate (2-EHN), may be
the most cost effective known additives to improve the cetane
number. However, most of these cetane improvers are thermally
sensitive, that is, they can undergo self accelerated decomposition
under thermal (elevated temperature) conditions. Organic peroxides
typically have self accelerated decomposition temperature (SADT)
less than 80.degree. C. Some other cetane improvers such as certain
nitrite and azo compounds are even shock sensitive, which may pose
a dangerous fire and explosive hazard in the field. Even 2-EHN,
considered one the safest of the cetane improvers, still has a SADT
of about 100.degree. C., which requires special storage tank and
engineering control.
[0005] Thus, it would be desirable if other additives could be
developed to improve the cetane number of middle distillate fuels
while be able to reduce or eliminate the amount of common cetane
improvers. If the NOx emissions were also reduced this would
additionally be beneficial.
SUMMARY
[0006] There are provided, in one non-limiting form, additive
compositions for increasing the cetane number of middle distillate
fuels which composition includes a polymer which includes a
homopolymer and/or random or block copolymer of olefins, such as
polyisobutylene (FIB), polypropylene (PP), or a random or block
polyolefin copolymer and the like. These homopolymers or random
copolymers may have a weight average molecular weight (M.sub.w)
ranging from about 200,000 to about 5,000,000 (0.2-5 MM);
alternatively about 900,000 to about 2,600,000 (0.9-2.6 MM). The
additive compositions of these polymeric materials also include a
free radical initiator component, for instance an alkyl nitrate,
such as 2-ethylhexylnitrate (2-EHN), and/or a peroxide, such as an
organic peroxides or hydrogen peroxide. The additive compositions
also include an alcohol as a solvent and optionally other solvents
such as a phenol and a heavy aromatic distillate.
[0007] There are further provided in another non-restrictive
version middle distillate fuels, such as diesel fuels, heating oil,
jet fuels, or kerosene, having improved cetane numbers that
contains an amount of an additive composition effective to increase
the cetane number. The additive composition includes a polymer that
may include a homopolymer of an olefin and/or a random/block
polyolefin copolymer and the like, where the homopolymer or
random/block copolymer has a weight average molecular weight
ranging from about 200,000 to about 5,000,000, alternatively from
about 900,000 to about 2,600,000, and a free radical initiator
component such as an alkyl nitrate and/or a peroxide, and also
contains a solvent such as those mentioned previously, particularly
an alcohol.
[0008] Also provided in another non-limiting embodiment are methods
for improving the cetane number of a middle distillate fuel by
adding to the fuel an effective amount of an additive composition
that includes a polymer component or combination of polymers that
may be a polyolefin homopolymer or a random or block polyolefin
copolymer and mixtures thereof, where the homopolymer or random
copolymer has a weight average molecular weight ranging from about
200,000 to about 5,000,000. The polymer may be linear, branched or
crosslinked. Again, the additive composition additionally contains
a solvent such as an alcohol and also includes a free radical
initiator component which may be an alkyl nitrate and/or a
peroxide.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a bar graph of the cetane number for four
different middle distillate fuels with no additive, 1000 ppm
2-ethyl hexyl nitrate (2-EHN) and 500 ppm 2-EHN and 500 ppm polymer
synergist;
[0010] FIG. 2 is a bar graph of the cetane number for CARB middle
distillate fuel with no additive, 500 ppm polymer synergist, 500
ppm 2-EHN and 500 ppm 2-EHN plus 500 ppm polymer synergist;
[0011] FIG. 3 is a bar graph comparing the cetane numbers from IQT
and ASTM D613 methods for Midwestern ULSD fuel for the cases where
no cetane improvers were added, where 500 ppm 2-EHN and 500 ppm
polymer are used, and where 1000 ppm 2-EHN was added; and
[0012] FIG. 4 is a bar graph comparing the cetane numbers from IQT
and ASTM D613 methods for CARB Diesel fuel for the cases where no
cetane improvers were added, where 500 ppm 2-EHN and 500 ppm
polymer are used, and where 1000 ppm 2-EHN was added.
DETAILED DESCRIPTION
[0013] The methods and compositions herein relate to raising the
cetane number of hydrocarbon fuels and in some cases also reducing
the amount of NOx exhaust emissions resulting from the combustion
of these fuels in compression ignition engines such as internal
combustion engines. In particular, the additives improve (increase)
the cetane number of middle distillate fuels. More specifically,
the methods and compositions herein concern a fuel additive
formulation that includes a relatively high molecular weight
polymer and a free radical initiator along with a suitable organic
solvent. Suitable polymers are homopolymers or copolymers
including, but not necessarily limited to, polyisobutylene,
polypropylene, poly alpha-olefin copolymer and the like. The
polymers may be linear or branched, and may optionally be
crosslinked. The copolymers may be random or block copolymers, or
combinations thereof; that is they may have regions which are
blocks and different regions which are random. In one non-limiting
embodiment the homopolymer or random copolymer has a weight average
molecular weight (M.sub.w) ranging from about 900,000 independently
to about 2,600,000; alternatively, the M.sub.w ranges from about
200,000 independently to about 5,000,000. By "independently"
throughout the application herein is meant that any lower threshold
for a parameter may be combined with any upper threshold. In one
non-limiting embodiment, the polymer presence lowers NOx and in
many embodiments while also increasing the cetane number.
[0014] The additive composition herein also contains a free radical
initiator component that may be an alkyl nitrate and/or a peroxide.
Suitable alkyl nitrates include, but are not necessarily limited
to, 2-ethylhexyl nitrate (2-EHN),
CH.sub.3(CH.sub.2).sub.3CH(C.sub.2H.sub.5)CH.sub.2ONO.sub.2,
iso-propyl nitrate, iso-amylnitrate, iso-hexylnitrate, cyclohexyl
nitrate, dodecyl nitrate, diglycol nitrate and tetraglycol nitrate
and the like. Ether nitrates and fatty acid nitrates may also be
useful. In one non-limiting embodiment, the alkyl nitrate may
function to primarily lower the NOx emissions, but it has been
discovered herein to give a synergistic increase in the cetane
number when used together with the homopolymer. It is desirable to
minimize the proportions of alkyl nitrate since they are relatively
expensive and hazardous storage concerns.
[0015] The additive composition may also optionally include a
peroxide, in place of or in addition to the alkyl nitrate. Suitable
peroxides include, but are not necessarily limited to, hydrogen
peroxide, di-tertiary butyl peroxide, and benzoyl peroxide, other
organic peroxides, and the like. Further, as noted, some synergism
has been found between the homopolymer and the alkyl nitrate and/or
peroxide. Known cetane boosters for use in distillate fuels include
2-ethylhexyl nitrate, tertiary butyl peroxide, diethylene glycol
methyl ether, cyclohexanol, and mixtures thereof. Conventional,
known ignition accelerators include hydrogen peroxide, benzoyl
peroxide, di-tert-butyl peroxide, and the like.
[0016] Other polymers that may also be useful in the additive
compositions herein include, but are not necessarily limited to,
isotactic polypropylene (such as ones having a weight average
molecular weight (M.sub.w) in the range of about 2,600,000 or
higher) or higher molecular weight hyperbranched polymer products
than those described above. Polymer alone without the 2-EHN may be
useful in some non-limiting embodiments.
[0017] An organic solvent is also useful in the additive
compositions described herein, particular an alcohol. Suitable
alcohols include, but are not limited to, linear or branched
alcohols having 2 to 18 carbon atoms. The hydroxyl group may be
terminal or internal. The alcohol may also be substituted with
oxygen, nitrogen or sulfur, for instance in a side chain. In an
alternative, non-restrictive embodiment the alcohol may be linear
or branched alcohols having 4 independently up to 10 carbon atoms,
in another non-limiting embodiment from about 4 independently up to
8 carbon atoms. Specific examples of suitable alcohols include, but
are not necessarily limited to, butanol, isobutanol, cyclohexanol,
and 2-ethylhexanol and the like and mixtures thereof. In one
non-limiting embodiment, the alcohol may be from about 1 to about
60 volume % of the additive composition, and in an alternative
non-restrictive version the amount of alcohol may range from about
2 independently to about 15 vol % of the additive composition.
[0018] Other useful components, which may serve an integration
function, such as to hold the components together and protect the
integrity of the additive composition, but which may additionally
serve to improve the cetane number, include, but are not
necessarily limited to, phenols and, quinine or hydroquinone
derivatives. In general such derivatives are alkyl substituted
phenols, alkyl substituted quinine, or alkyl substituted
hydroquinone, where the alkyl group are C1 to C300 hydrocarbyl
group that may contain unsaturated double bonds, or triple bonds,
may be linear or branched and may be mono, di, tri, tetra, or penta
substituted, and may contain O, N, or S, e.g, tocopherol or
ubiquinol. Suitable phenols include, but are not necessarily
limited to, 2,6-di-tert-butylphenol,
2,6-di-tert-butyl-4-methylphenol, 2,5-di-tert-butylhydroquinone,
polyisobutylene phenol, tocopherol (Vitamin E family) and the like
and mixtures thereof. Suitable quinone derivatives include, but are
not necessary limited to ubiquinol family and the like or mixtures
thereof; Suitable hydroquinone derivatives include, but not
necessary limited to, tert-butylhydroquinone,
2,5-di-tert-butylhydroquinone and the like or mixtures thereof. In
one non-limiting embodiment, the phenol may be from about 0.001 to
about 20 volume % of the additive composition, and in an
alternative non-restrictive version the amount of alcohol may range
from about 0.1 independently to about 10 vol % of the additive
composition. Other suitable solvents include, but are not
necessarily limited to, heavy aromatic distillates such as those
available from Chevron, kerosene or D-2 diesel and the like and
mixtures thereof. In one non-limiting embodiment, these other
suitable solvents may be from about 0.001 to about 30 volume % of
the additive composition, and in an alternative non-restrictive
version the amount of alcohol may range from about 0.1
independently to about 10 vol % of the additive composition. The
solvent for the homopolymer and the free radical initiator
component may include an alcohol, a phenol derivative and a heavy
aromatic distillate--all three types together. Other useful
components may also include polymer solvation aids including, but
not necessarily limited to, limonene, highly branched aliphatic
hydrocarbons, and the like.
[0019] It has been discovered that the addition of the combination
of additives described herein to a diesel fuel, which additives
comprise a major/equal amount of polymer with a equal/minor amount
of 2-EHN resulted in an increase of cetane number of the fuel to a
level surpassing that would be expected based on the single
contribution attributed to each component individually. Thus the
combination of alkyl nitrate and polymer constitutes an
unexpectedly synergetic combination.
[0020] The methods herein relate to additive compositions for
distillate fuels, as contrasted with products from resid. In the
context herein, the methods and compositions are particularly
suitable for middle distillate fuels which include, but are not
necessarily limited to diesel fuel, heating oil, kerosene,
gasoline, jet fuel, and the like. It will be appreciated that
middle distillate fuels include, but are not necessarily limited
to, blends of conventional hydrocarbons meant by these terms with
oxygenates, e.g. alcohols, such as methanol, ethanol, and other
additives or blending components presently used in these distillate
fuels, such as MTBE (methyl-tert-butyl ether), or that may be used
in the future. In one non-limiting embodiment herein, middle
distillate fuels include low sulfur fuels, which are defined as
having a sulfur content of 0.2% by weight or less, and in another
non-limiting embodiment as having a sulfur content of about 0.0015
wt. % useful middle distillate fuels herein are diesel and
kerosene. It is expected that a more conventional diesel fuel (i.e.
with an aromatic content of >28%) treated with the additive
composition herein will be equivalent in emissions to a Texas Low
Emissions Diesel (TxLED) fuel with <10% aromatic content.
[0021] Generally, in one non-limiting embodiment herein the
composition for improving the cetane numbers of middle distillate
fuels is a mixture or blend of the free radical initiator component
and at least one of the polymers together with an organic solvent,
particularly an alcohol. In another non-restrictive version herein
the homopolymer or random copolymer is present in the fuel in the
range of about 0.01 independently up to about 20,000 ppm, in
another non-restrictive version up to about 250 ppm, in one non
limiting embodiment from about 0.5 independently up to about 100
ppm; alternatively from about 1 independently up to about 10 ppm,
alternatively up to about 5 ppm. The polymer concentration in the
additive composition may be from about 2000 to about 40,000 ppm.
The free radical initiator component, such as an alkyl nitrate,
particularly 2-EHN, may be present in the fuel in the range of
about 50 independently to about 4,000 ppm, in another non-limiting
embodiment from about 100 independently to about 500 ppm,
alternatively from about 200, independently up to about 400 ppm.
These amounts are much lower than the amounts of about 1750 ppm
2-EHN alone used in some prior fuel formulations, but by largely
replacing the 2-EHN with a homopolymer, similar NOx reductions may
be achieved. In one non-limiting embodiment, the volume ratio of
polymer to the free radical initiator component ranges from about
1:100 to about 100:1, and alternatively the volume ratio of polymer
to the free radical initiator component ranges from about 1:100 to
about 100:1; and in one particularly suitable ratio range, from
about 1:1 to about 1.5:1; alternatively from about 1:1 to about
3:1.
[0022] It will be appreciated that the methods and compositions
herein also encompass middle distillate fuels per se containing the
additive compositions described herein, as well as methods of
improving the cetane numbers of middle distillate fuels using the
additive compositions described herein.
[0023] Other, optional components of the middle distillate fuels in
non-limiting embodiments may include, but are not necessarily
limited to detergents, pour point depressants, additional cetane
improvers different from those noted as part of the additive
composition, lubricity additives, dehazers, cold operability
additives, conductivity additives, biocides, dyes, and mixtures
thereof. Particularly useful components may include condensation
reaction products of aldehydes and amines which are useful as
antioxidants and are effective to lower emissions such as
particulate matter (PM) and unburnt hydrocarbon (HC). A specific
non-limiting example is the condensation reaction product between
formaldehyde and di-n-butylamine. In another non-limiting
embodiment, water is explicitly absent from the additive
composition.
[0024] The invention will be illustrated further with respect to
the following non-limiting Examples that are included only to
further illuminate the invention and not to restrict it.
Examples 1-18
[0025] Tables I through IV are compilations of experimental cetane
number test results using the ASTM D613 test methodology in a
Midwestern, Eastern, Western and CARB Diesel ultra-low sulfur
diesel (ULSD) fuels. All tests were performed at Southwest Research
Institute (SwRI) unless otherwise noted. The data show that in
these ULSDs, the same level of cetane improvement may be achieved
by replacing the relatively more expensive 2-EHN with an additive
composition containing 0.2% of an about 2,000,000 Mw PIB
homopolymer synergist. The results are plotted in FIG. 1.
TABLE-US-00001 TABLE I Cetane Synergist Performance Summary Cetane
Engine Test Results via ASTM D613 (Midwestern ULSD) Synergist 2-EHN
Cetane Number Ex. Dosage, ppm Dosage, ppm Cetane # Improvement 1 0
0 44.8 -- 2 0 1000 48.2 3.4 3 400 600 48.4 3.6 4 500 500 48.3 3.5 5
600 400 48.3 3.5
TABLE-US-00002 TABLE II Cetane Synergist Performance Summary Cetane
Engine Test Results via ASTM D613 (Eastern ULSD) Synergist 2-EHN
Cetane Number Ex. Dosage, ppm Dosage, ppm Cetane # Improvement 6 0
0 47.7 -- 7 0 1000 49.6 1.9 8 400 600 48.6 0.9 9 500 500 49.6 1.9
10 600 400 50.4 2.7
TABLE-US-00003 TABLE III Cetane Synergist Performance Summary
Cetane Engine Test Results via ASTM D613 (Western ULSD) Synergist
2-EHN Cetane Number Ex. Dosage, ppm Dosage, ppm Cetane #
Improvement 11 0 0 50.4 -- 12 0 1000 51.1 0.7 13 500 500 51.4 1.3
14 600 400 51.1 1.0
TABLE-US-00004 TABLE I Cetane Synergist Performance Summary Cetane
Engine Test Results via ASTM D613 (CARB Diesel) Synergist 2-EHN
Cetane Number Ex. Dosage, ppm Dosage, ppm Cetane # Improvement 15 0
0 51.3 -- 16 0 1000 53.8 2.5 17 500 500 53.5 2.2 18 600 400 53.5
2.2
[0026] Thus, the cetane numbers of the middle distillate fuels is
the same as or greater than the cetane number achieved when in the
additive composition the free radical initiator component is
present at the same total additive dosage level for both the
homopolymer and the free radical initiator component combined, and
no homopolymer is present.
Examples 19-26
[0027] Examples 19-26 present the results of testing from the
combination of diluted polymer synergist and 2-EHN which worked
better than either additive used individually. In these
comparisons, the solvent is believed to help improve the cetane
number. The synergist was again 2,000,000 Mw PIB homopolymer. The
fuels used were a ULSD and CARB Diesel. The results of Table VI are
graphed in FIG. 2. FIG. 2 illustrates that with total 1000 ppm of
either polymer synergist and solvent, 2-EHN and solvent, or polymer
synergist and 2-EHN, the latter combination surprisingly gives the
best results. The solvent was butanol.
TABLE-US-00005 TABLE V Synergistic Effect of 2-EHN and Cetane
Synergist Cetane Engine Test Results via ASTM D613 (Valero ULSD)
2-EHN Synergist Ex. Dosage, ppm Dosage, ppm Solvent Cetane # 19 0 0
-- 50.4 20 0 500 500 47.1 21 500 0 500 49.8 22 500 500 -- 51.4
TABLE-US-00006 TABLE VI Synergistic Effect of 2-EHN and Cetane
Synergist Cetane Engine Test Results via ASTM D613 (CARB Diesel)
2-EHN Synergist Ex. Dosage, ppm Dosage, ppm Solvent Cetane # 23 0 0
-- 51.3 24 0 500 500 52.2 25 500 0 500 52.7 26 500 500 -- 53.5
Examples 27-29
[0028] During testing, all high molecular weight polymers ranging
from about 900,000 to 2,100,000 only showed marginal performance
when used alone for NOx reduction. It was surprisingly discovered
that when about 2,000,000 Mw PIB polymer was used with 2-EHN that a
clear synergistic effect was shown that gave a 6.2% NOx reduction
as compared with only 0.1% reduction when only the 1% PIB mixture
was used and only a 3.2% reduction when 2-EHN was used alone. The
fuel used was a typical ULSD from a Valero refinery. The 1% PIB
mixture was 1 vol % about 2,000,000 M.sub.w PIB homopolymer, 5 vol
% butanol and 94% Chevron heavy aromatic distillates. From previous
experiments, adding about 5 to about 10% mineral oil may also help
lower the NOx emissions. The results are shown in Table VII.
TABLE-US-00007 TABLE VII High Molecular Weight PIB Alone, EHN Alone
and PIB + EHN EHN Ex. Treat Rate PIB active Conc. % NOx No. Sample
(ppm) (ppm) (ppm) Red. 27 BPC91 (0.2% PIB 2000 4 0 0.1 mixture) 28
2-EHN 500 0 500 3.2 29 BPC121 (1% PIB 2000 3.2 400 6.2 mixture +
2-EHN)
[0029] Thus, the middle distillate fuel has reduced NOx emissions
as compared to an otherwise identical fuel with an additive
composition at the same dosage level where: (a) only the free
radical initiator component is substituted for both the free
radical initiator component and the homopolymer component and/or
(b) only the homopolymer component is substituted for both the free
radical initiator component and the homopolymer component, where
the free radical initiator component is an alkyl nitrate.
Examples 30-39
[0030] While determining cetane number via the ASTM D613 engine
testing procedure is the industry standard methodology, it is
commonplace, especially in refinery sites, to also use a quicker
bench method referred to as IQT (Ignition Quality Test) as a guide
for assessing fuel. This method is ASTM D6890 and it calculates a
derived cetane number.
[0031] IQTs were conducted at a third party lab different from SwRI
to see how the IQT data compared to the D613 data. The polymer
synergist was the same as for Examples 1-26. The expectation was
that the data would be comparable under both test methodologies.
Table VIII presents the data in tabular form; the amounts of 2-EHN
and the polymer synergist were in ppm. FIG. 3 is a bar graph of the
results for Examples 35, 39 and 36 for Midwestern ULSD fuel; FIG. 4
is a bar graph of the results for Examples 30, 33 and 34 for CARB
Diesel fuel.
[0032] However, the initial results from the two fuels indicated
that the D613 data and the IQT data were not the same. The IQT
showed a bigger response to using straight 2-EHN than the D613
testing did, for unknown reasons. Further investigation would be
needed to determine the exact mechanism involved.
TABLE-US-00008 TABLE VIII Ex. Fuel 2-EHN Synergist IQT D613 30 CARB
Diesel 0 0 50.42 51.3 31 CARB Diesel 334 666 53.75 53.0 32 CARB
Diesel 400 600 53.44 53.5 33 CARB Diesel 500 500 54.48 53.5 34 CARB
Diesel 1000 0 56.08 53.8 35 Midwestern ULSD 0 0 46.17 44.8 36
Midwestern ULSD 1000 0 49.53 48.2 37 Midwestern ULSD 334 666 47.59
49.2 38 Midwestern ULSD 400 600 48.00 48.3 39 Midwestern ULSD 500
500 48.28 48.3
[0033] In the foregoing specification, the invention has been
described with reference to specific embodiments thereof, and has
been demonstrated as effective for reducing the emissions of fuels.
However, it will be evident that various modifications and changes
may be made thereto without departing from the broader spirit or
scope of the invention as set forth in the appended claims.
Accordingly, the specification is to be regarded in an illustrative
rather than a restrictive sense. For example, specific combinations
of polymers together with certain free radical initiator
components, e.g. alkyl nitrates and/or peroxides and organic
solvents (e.g. alcohols, phenols and/or heavy aromatic distillates)
falling within the claimed parameters, but not specifically
identified or tried in a particular composition to improve the
emissions of fuels herein, are expected to be within the scope of
this invention. Certain compositions under certain conditions may
serve to improve cetane numbers and/or lower NOx emissions; and/or
without any substantial increase in PM emissions or with
substantially unchanged PM emissions. It is anticipated that the
compositions described herein may also impart to the engines in
which they are used as emissions reducers, greater horsepower, and
better fuel economy as a result of less friction, whether they are
used in diesel or gasoline engines.
[0034] The present invention may suitably comprise, consist or
consist essentially of the elements disclosed and may be practiced
in the absence of an element not disclosed. For instance, the
additive composition may consist of or consist essentially of the
homopolymers and the free radical initiators, including one or more
solvent such as an alcohol, a phenol, and or a heavy aromatic
distillate, as described in the claims.
[0035] The words "comprising" and "comprises" as used throughout
the claims is to interpreted "including but not limited to".
* * * * *