Note: Descriptions are shown in the official language in which they were submitted.
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
AVIATION-GRADE KEROSENE FROM INDEPENDENTLY PRODUCED
BLENDSTOCKS
STATEMENT REGARDING FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
[0001] This invention was made with government support under contract W911NF-
07-C-0046
awarded by the Defense Advanced Research Projects Agency (DARPA). The
government has
certain rights in the invention.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates generally to aviation-grade high-cetane
kerosene fuel. More
particularly, herein disclosed is an aviation-grade kerosene fuel produced in
part or fully from non-
petroleum feedstocks. Specifically, the disclosed kerosene fuel comprises at
least two
independently produced blendstocks, with the first blendstock comprising
primarily isoparaffins
and normal paraffins (UN) derived from non-petroleum feedstocks and the second
blendstock
comprising primarily cycloalkanes and aromatics (C/A) derived from petroleum
or non-petroleum
feedstocks. In embodiments, a kerosene fuel suitable for use as aviation
turbine fuel having drop-in
and fit-for-purpose compatibility with conventional petroleum-derived fuels
comprises up to 95
volume % (vol.%) UN blendstock and up to 35 vol.% C/A blendstock.
Backuound of the Invention
[0003] The generic term "kerosene" is used to describe the fraction of crude
petroleum that boils
approximately in the range of 293 F to 572 F (145 C to 300 C) and consists of
hydrocarbons
primarily in the range of C8-C16. Kerosenes are the lighter end of a group of
petroleum substances
known as middle distillates.
[0004] As an example, the predominant use of high-cetane kerosene in the
United States is aviation
turbine fuel for civilian (Jet A or Jet A-1) and military (JP-8 or JP-5)
aircraft. Kerosene-based fuels
differ from each other in performance specifications. Jet A and Jet A-1 are
kerosene-type fuels.
The primary physical difference between Jet A and Jet A-1 is freeze point (the
temperature at which
wax crystals disappear in a laboratory test). Jet A, which is mainly used in
the United States, must
have a freeze point of -40 C or below, while Jet A-1 must have a freeze point
of -47 C or below.
Jet A does not normally contain a static dissipater additive, while Jet A-1
often requires this
additive. There are additional differences between the two fuels, and full
specifications are outlined
under the ASTM D1655 and Def Stan 91-91/5 standards, respectively.
1
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
[0005] Military turbine fuel grades such as JP-5 and JP-8 are defined by Mil-
DTL-5624 and Mil-
DTL-83133, respectively. These fuels are kerosene-type fuels made to more
exacting specifications
than the commercial jet fuels. They also contain unique performance enhancing
additives.
Throughout the world, many governments have issued a variety of standards such
as for TS-1
premium kerosene, TS-1 regular kerosene, and T-1 regular kerosene in Russia.
The crude oil
fraction for all of these aviation-grade kerosenes is basically limited to the
range of 300 F to 500 F
(149 C to 260 C), with additional specifications based on recovery rates at
given temperature
points. Hydrocarbons are primarily in the range of C8-C16.
[0006] The ready availability of crude petroleum has encouraged the
establishment of the above-
mentioned specifications for kerosene as the basis for fuels in engines of
various types, and engines
have thus been optimized to run on kerosene having these specifications.
Concern has arisen
regarding the reliability and availability of the petroleum supply. This
concern has stimulated a
search for substitutes. Liquids derived from coal, shale, tar sands, and
renewable resources such as
biomass, in particular, plant material, have been proposed. These processes
have not adequately
produced aviation-grade kerosene that complies with today's jet fuel
specifications.
[0007] The failure of obtaining suitable aviation-grade kerosenes from non-
petroleum feedstocks
has triggered development in downstream processing of the products. For
example, U.S. Patent No.
4,645,585 discloses the production of novel fuel blends from hydroprocessing
highly aromatic
heavy oils such as those derived from coal pyrolysis and coal hydrogenation.
[0008] International Patent WO 2005/001002 A2 relates to a distillate fuel
comprising a stable,
low-sulfur, highly paraffinic, moderately unsaturated distillate fuel
blendstock. The highly
paraffinic, moderately unsaturated distillate fuel blendstock is prepared from
a Fischer-Tropsch-
derived product that is hydroprocessed under conditions during which a
moderate amount of
unsaturates are formed or retained to improve stability of the product.
[0009] Although many physical properties for aviation-grade kerosene can be
matched and even
outperformed, the fuels derived by hydroprocessing and additional upgrading as
described above do
not provide drop-in compatibility with conventional petroleum-derived aviation-
grade kerosene, as
they lack some of the major hydrocarbon constituents of typical petroleum-
derived kerosene.
[0010] An attempt for better modeling of the variety of different hydrocarbon
constituents was
made by Violi et al. (Violi, A.; Yan, S.; Eddings, E.G.; Sarofim, A.F.;
Granata, S.; Faravelli, T.;
Ranzi, E.; Combust. Sci. Technol. 2002, 174 (11-12) 399-417). Violi et al.
modeled JP-8 as a six-
compound blend of well-known hydrocarbons with the following molar
composition: 10% iso-
octane (C8H18), 20% methylcyclohexane (C7H14), 15% m-xylene (C8Hl0), 30%
normal-dodecane
(C12H26), 5% tetralin (CioH12), and 20% tetradecane (C14H30). This surrogate
blend simulates the
2
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
volatility and smoke point of a practical JP-8 fuel. However, this method of
reducing the fuel to a
mere six-compound blend does not reproduce all required performance
specifications of JP-8.
[0011] A different route was pursued in U.S. Patent Application 2006/0138025,
which relates to
distillate fuels or distillate fuel blendstocks comprising a blend of a
Fischer-Tropsch-derived
product and a petroleum-derived product that is then hydrocracked under
conditions to preserve
aromatics. While this may produce some required characteristics from certain
petroleum
feedstocks, such as seal swell and density, this approach reduces the ability
to achieve competing
characteristics, such as freeze point specifications.
[0012] Accordingly, there is an ongoing need for a fuel and process that allow
use of
environmentally- sensitive processes as a bridge to the future and provide
drop-in compatibility
with existing petroleum-based aviation-grade kerosene for clean fuels produced
from secure
domestic resources.
SUMMARY
[0013] Herein disclosed is aviation-grade kerosene comprising: a first
blendstock derived from
non-petroleum feedstock and comprising primarily hydrocarbons selected from
the group
consisting of isoparaffins and normal paraffins, and a second blendstock
comprising primarily
hydrocarbons selected from the group consisting of cycloalkanes and aromatics.
In embodiments,
the second blendstock is derived from feedstock comprising non-petroleum
feedstock. It is
desirable for the aviation-grade kerosene is capable of being blended with
petroleum-derived jet
fuel in any proportion such that the resulting blend meets fuel grade
specification of the petroleum-
derived jet fuel. In embodiments, the aviation-grade kerosene comprises up to
95 vol.% of first
blendstock and up to 35 vol.% of second blendstock.
[0014] In specific embodiments, the aviation-grade kerosene comprises up to 95
vol.% first
blendstock, from about 0 vol.% to about 30 vol.% cycloalkanes, and from about
0 vol.% to about
15 vol.% aromatics. In embodiments, this kerosene comprising up to 95 vol.%
first blendstock,
from about 0 vol.% to about 30 vol.% cycloalkanes, and from about 0 vol.% to
about 15 vol.%
aromatics meets fit-for-purpose requirements. In embodiments, at least 50
weight % of the
kerosene is derived from coal, natural gas, or a combination thereof. In
embodiments, the second
blendstock is derived from coal, biomass, oil-shale, tar, oil sands, or a
combination thereof. In
embodiments, at least 50 weight % of the kerosene is derived from biomass. In
embodiments, at
least 10 weight % of the kerosene is derived from non-cracked bio-oil.
[0015] Also disclosed herein is a method for the production of aviation-grade
kerosene comprising:
producing a first blendstock from at least one non-petroleum feedstock, the
first blendstock
comprising primarily hydrocarbons selected from the group consisting of
isoparaffins and normal
3
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
paraffins; producing a second blendstock comprising primarily hydrocarbons
selected from the
group consisting of cycloalkanes and aromatics; and blending at least a
portion of the first
blendstock with at least a portion of the second blendstock to produce
aviation-grade kerosene. In
embodiments of the method for the production of aviation-grade kerosene, first
and second
blendstocks are independently-produced. In embodiments of the method, the non-
petroleum
feedstock is selected from the group consisting of coal, natural gas, biomass,
vegetable oils, biomass
pyrolysis bio-oils, biologically-derived oils and combinations thereof.
[0016] In some embodiments of the method, at least a portion of first
blendstock is produced via
indirect liquefaction. Indirect liquefaction may comprise Fischer-Tropsch
processing of a feedstock
selected from the group consisting of natural gas, coal, biomass, and
combinations thereof. The
kerosene may comprise up to about 90 vol.% first blendstock produced via
indirect liquefaction.
[0017] In embodiments of the method for the production of aviation-grade
kerosene, the at least one
non-petroleum feedstock comprises triglyceride and/or fatty acid feedstock.
The kerosene may
comprise from about 65 vol.% to about 75 vol.% of first blendstock, the at
least one non-petroleum
feedstock for which comprises triglyceride and/or fatty acid feedstock. In
embodiments, second
blendstock is produced by catalytic cyclization and/or reforming of a portion
of first blendstock, the
at least one non-petroleum feedstock for which comprises triglyceride and/or
fatty acid feedstock.
The kerosene may comprise about 65 vol.% first blendstock, the at least one
non-petroleum
feedstock for which comprises triglyceride and/or fatty acid feedstock; and
about 35 vol.% second
blendstock produced by catalytic cyclization and/or reforming of a portion of
first blendstock.
[0018] In some embodiments, the kerosene comprises about 70 vol.% first
blendstock produced via
catalytic processing of triglyceride and/or fatty acid feedstock and about 30
vol.% second blendstock
produced via pyrolysis processing of high cycloalkane-content material.
[0019] In embodiments of the method for the production of aviation-grade
kerosene, second
blendstock is produced via pyrolysis of a feedstock selected from the group
consisting of coal, oil
shale, oil sands, tar, biomass, and combinations thereof. In specific
embodiments, the kerosene may
comprise about 80 vol.% first blendstock produced via Fischer-Tropsch
processing of natural gas,
coal, and/or biomass and about 20 vol.% second blendstock produced via
pyrolysis processing of
coal tar fraction.
[0020] In some embodiments of the method for the production of aviation-grade
kerosene, the
second blendstock is produced via direct liquefaction. In embodiments, the
kerosene comprises
about 25 vol.% second blendstock produced via direct liquefaction. In specific
embodiments, the
kerosene further comprises about 75 vol.% first blendstock derived from
Fischer-Tropsch processing
of natural gas, coal, and/or biomass.
4
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
[0021] In some embodiments of the method for the production of aviation-grade
kerosene, second
blendstock is produced from a biomass-derived lignin feedstock. The kerosene
may comprise from
about 25 vol.% to about 30 vol.% second blendstock produced from a biomass-
derived lignin
feedstock.
In some embodiments, the kerosene comprises about 30 vol.% second blendstock
produced via
pyrolysis processing of biomass-derived lignin and about 70 vol.% first
blendstock produced via
Fischer-Tropsch processing of natural gas, coal, and/or biomass. In
embodiments, the kerosene
comprises about 25 vol.% second blendstock produced from a biomass-derived
lignin feedstock and
about 75 vol.% first blendstock derived from catalytic processing of
triglyceride feedstock.
[0022] In embodiments of the method for the production of aviation-grade
kerosene, the method
further comprises testing the aviation grade kerosene for at least one
requirement selected from the
group consisting of fit-for-purpose requirements, ASTM requirements, and
combinations thereof. In
embodiments, the method further comprises adjusting the ratio of first
blendstock and second
blendstock in the kerosene to meet at least one requirement selected from the
group consisting of fit-
for-purpose requirements, ASTM requirements, and combinations thereof. In some
embodiments,
the method further comprises adjusting the amount of cycloalkanes and
aromatics in the second
blendstock to meet at least one requirement selected from the group consisting
of fit-for-purpose
requirements, ASTM requirements, and combinations thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] For a more detailed description of the preferred embodiment of the
present invention,
reference will now be made to the accompanying drawings, wherein:
[0024] Figure 1 is a schematic of an indirect liquefaction process suitable
for producing
isoparaffin/n-paraffin (UN) blendstock according to an embodiment of the
present disclosure.
[0025] Figure 2 is a schematic of a pyrolysis process suitable for producing
cycloalkane/aromatic
(C/A) blendstock according to an embodiment of the present disclosure.
[0026] Figure 3 is a schematic of a direct liquefaction process suitable for
producing
cycloalkane/aromatic (C/A) blendstock according to an embodiment of the
present disclosure.
[0027] Figure 4 is a comparison of gas chromatography data from FT (FT derived
liquid fuel
from natural gas - bottom) and Fuel Sample A (top) produced from two discrete
blendstocks
and technological process: (1) an isoparaffinic kerosene (IPK) produced from
FT technology
and natural gas feedstock and (2) an aromatic/cycloparaffinic blendstock
produced from
petroleum feedstock.
[0028] Figure 5 is a comparison of gas chromatography data from typical JP-8
(bottom) and
Fuel Sample C (top) produced from two discrete blendstocks and technological
process: (1) an
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
isoparaffinic kerosene (IPK) produced from a crop oil feedstock and (2) an
aromatic/cycloparaffinic blendstock produced from a crop oil feedstock.
NOTATION AND NOMENCLATURE
[0029] The term "UN blendstock" as used herein refers to a material that
comprises at least 95
weight % of isoparaffins, normal paraffins, or a mixture thereof.
[0030] The term "C/A blendstock" as used herein refers to a material that
comprises at least 95
weight % of cycloalkanes, aromatics, or a mixture thereof.
[0031] The terms "aviation-grade kerosene" or "jet fuel" as used herein refer
to kerosene-type fuels
that are specified by military turbine fuel grades such as JP-5 and JP-8 and
defined by Mil-DTL-
5624 and Mil-DTL-83133, respectively, or civilian aviation jet fuels such as
Jet A or Jet A-1 with
full specifications outlined under the ASTM D1655 and Def Stan 91-91/5
standards, respectively.
Throughout the world there exist a variety of similar standards that might
change over time and are
considered under this definition.
[0032] The term "fit-for-purpose requirements" as used herein refers to fuel
property requirements
that are not necessarily addressed by military or ASTM standards, but are
still important to fuel
performance and stability in jet engines and during fuel handling,
distribution, and storage.
Examples of fit-for-purpose requirements include fuel compatibility with
aircraft fuel and engine
system materials of construction, adequate fuel performance in compression
ignition (versus
turbine) engines in a wide variety of ground environments, and possible fuel
performance
requirements related to swelling of elastomeric seals in, for example, turbine
engines.
[0033] The term "drop-in compatibility" as used herein refers to aviation-
grade kerosene capable
of being blended with petroleum-derived jet fuel in any proportion (i.e. from
0% to 100%) such that
the resulting blend meets fuel grade specification and fit-for-purpose
requirements of the equivalent
petroleum-based jet fuel.
[0034] The term "UN-C/A fuel" as used herein refers to aviation-grade kerosene
derived from at
least two independently produced blendstocks, with a first UN blendstock
derived from non-
petroleum feedstocks and a second C/A blendstock derived from petroleum or non-
petroleum
feedstocks.
DETAILED DESCRIPTION
1. Overview
[0035] Herein disclosed are a fuel and a method for making the fuel whereby
the fuel has drop-in
compatibility with existing petroleum-derived fuels and enables production of
most or all of a fuel
from domestic, non-petroleum, and/or renewable feedstocks. The method of
making this aviation-
6
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
grade jet fuel may allow broad flexibility in fuel formulation in order to
meet specific end-use
requirements. The disclosed UN-C/A fuel comprises a blend of fuel components,
namely straight-
chain (normal) and branched (iso-) paraffins, cycloalkanes, and/or aromatics.
[0036] Meeting a specification for aviation-grade kerosene requires providing
a complex mixture
of fuel chemical classes that have conflicting effects on physical properties.
For example, longer
carbon chain molecules serve to reduce volatility and increase density, which
in turn raises freeze
point above acceptable levels for high altitude flight. Balancing these
characteristics along with
energy density, flash point, viscosity, smoke point, seal-swelling capacity,
and other characteristics
makes fuel formulation difficult when derived from a single non-petroleum
resource.
[0037] The aviation-grade kerosene herein disclosed is produced from at least
two independently-
produced blendstocks, with a first blendstock comprising primarily
hydrocarbons selected from the
group consisting of isoparaffins and normal paraffins (UN) and derived from
non-petroleum
feedstocks and a second blendstock comprising primarily hydrocarbons selected
from the group
consisting of cycloalkanes and aromatics (C/A) and derived from petroleum or
non-petroleum
feedstocks. In embodiments, the finished UN-C/A jet fuel comprises up to 95
volume % (vol.%)
UN blendstock and up to 35 (vol.%) C/A blendstock.
II. Kerosene
[0038] Petroleum-based kerosene may be obtained either from the atmospheric
distillation of crude
oil ("straight-run" kerosene) or from cracking of heavier petroleum streams
("cracked" kerosene).
The kerosene is further treated by a variety of processes to remove or reduce
the level of
undesirable components, e.g., aromatic hydrocarbons, sulfur, nitrogen, or
olefinic materials. This
additional processing also reduces compositional variation and enriches
components that improve
performance (cycloalkanes and isoparaffins, for example). In practice, the
major processes used are
hydrodesulfurization (treatment with hydrogen to remove sulfur components),
washing with caustic
soda solution (to remove sulfur components), and hydrogenation (to remove, for
example, olefins,
sulfur, metals, and/or nitrogen components). Aromatics that may have formed
during the cracking
process are removed via solvent extraction. For instance, hydrodesulfurized
kerosene is obtained
by treating a kerosene-range petroleum stock with hydrogen to convert organic
sulfur to hydrogen
sulfide, which is then removed. These subsequent treatments may blur the
distinction between
straight-run and cracked kerosenes.
[0039] While kerosenes are essentially similar in composition, the precise
composition of a
specific kerosene-range refinery stream depends on the crude oil from which
the kerosene was
derived and on the refinery processes used for its production. Because they
are complex
hydrocarbon mixtures, materials in this category are typically not defined by
detailed compositional
7
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
data but instead by process history, physical properties, and product-use ASTM
and similar
specifications.
[0040] Consequently, detailed compositional information for the streams in
this category is limited.
General compositional information on representative kerosene-range refinery
streams and fuels,
presented in Table 1, illustrates the fact that the materials in this category
are similar in physical
properties and composition. Regardless of crude oil source or processing
history, major
components of kerosenes comprise branched and straight-chain paraffins (iso-
and normal or n-
alkanes) and naphthenes (cycloparaffins or cycloalkanes), which normally
account for at least 75
vol.% of a finished fuel. Aromatic hydrocarbons in this boiling range, such as
alkylbenzenes
(single ring) and alkylnaphthalenes (double ring) do not normally exceed 25
vol.% of a kerosene
product. Olefins are usually not present at more than 5% by volume. The
distillation range of
kerosenes is such that benzene (80 C boiling point) and normal-hexane (69 C
boiling point)
concentrations are generally less than 0.01% by mass. The boiling points of
the 3-7 fused-ring
polycyclic aromatic compounds (PACs) are well above the boiling range of
straight-run kerosene
streams. Consequently, the concentrations of PACs found in kerosenes are very
low, if not below
the limits of detection of the available analytical methods. A detailed
analysis of a
hydrodesulfurized kerosene illustrates this and is presented as Table 2.
[0041]
Table 1: General Kerosene Com ositional Information
Hydrodesulfurized Jet A JP-8
Kerosene
API Gravity 39-45.5 37.2-46.1 37.0-46.7
Aromatic Content, 18 - 21.4 11.6 - 24.0 13.6 - 22.1
Vol.%
Olefin Content, vol.% 1.0 -1.66 0.0 - 4.1 0.6 - 3.0
Saturates Content, 77 2- 82 71.9 - 88.4 74.9 - 85.8
Vol.%
10% Distillation, F 329 - 406 294 - 394 333 - 390
FBP Distillation, F 404 -510 419 -474
(Final Boiling Pt.) 451- 568 (90%) (90%)
[0042]
Table 2: H drodesulfurized Kerosene
Component Weight Percent
Nonaromatics 80.27
Saturates 78.61
Olefins 1.66
Aromatics 19.72
Less than Three-Ring PAC 19.72
Three- to Seven-Ring PAC <0.01
8
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
III. UN Blendstock
[0043] The herein disclosed UN-C/A blend fuel comprises at least one UN
blendstock comprising
primarily hydrocarbons selected from the group consisting of isoparaffins and
normal paraffins, the
hydrocarbons derived from non-petroleum feedstock. The finished UN-C/A jet
fuel comprises up to
95 vol.% of UN blendstock. In embodiments, UN blendstock comprises isoparaffin
and/or normal
paraffin compounds containing primarily from eight to sixteen carbon atoms per
molecule (C8 to
C16 compounds). In embodiments, these compounds are produced directly via a
chemical process
such as, but not limited to, Fischer-Tropsch condensation of syngas,
thermocatalytic processing of
vegetable oils, pyrolysis, liquefaction, and gas-to-liquids processing.
[0044] In embodiments, UN blendstock is derived from one or a combination of
the following
feedstocks: natural gas, coal, biomass, vegetable oils, biomass pyrolysis bio-
oils, and other
biologically-derived oils. UN blendstock can be produced by several routes. In
a specific
embodiment, as shown in Figure 1, indirect liquefaction is used to produce UN
blendstock. Indirect
liquefaction feedstock, such as coal or biomass, 10 is gasified in gasifier 40
with steam 20 and/or oil
30. Gasifier effluent 50, may comprise carbon monoxide, hydrogen, carbon
dioxide, hydrogen
sulfide, and/or ammonia. Gasifier effluent 50 is purified and upgraded in step
60, whereby a
contaminant stream(s) 70 comprising, for example, hydrogen sulfide, ammonia,
and/or carbon
dioxide is removed. Syngas stream 80, comprising primarily CO and H2,
undergoes liquefaction 90
to yield liquid products 100. In embodiments, liquid products 100 are
synthesized from syngas 80
by catalytic Fischer-Tropsch (F-T) processing. The Fischer-Tropsch reactions
produce a wide
spectrum of oxygenated compounds, in particular, alcohols and paraffins
ranging in carbon
numbers from C1-C3 (gases) to C35+ (solid waxes). These Fischer-Tropsch
products yield distillate
fuels that comprise C8-C16 paraffins and, through isomerization, C8-C16
isoparaffins that have
excellent cetane numbers and very low sulfur and aromatic content. These
properties make F-T
products suitable for use as UN blendstock. However, because of the lack of
adequate cycloalkanes
and aromatics, Fischer-Tropsch distillate fuels are typically unable to meet
all military and ASTM
specifications and fit-for-purpose requirements. Therefore, as described
further hereinbelow, UN
blendstock is blended with C/A blendstock to obtain aviation-grade UN-C/A
fuel. In embodiments,
UN-C/A fuel comprises up to 95 vol.% UN blendstock, alternatively about 90
vol.% UN blendstock
derived from Fischer-Tropsch processing of natural gas, coal, and/or biomass.
In embodiments, the
UN-C/A fuel comprises about 80 vol.% UN blendstock derived from Fischer-
Tropsch processing of
natural gas, coal, and/or biomass. In alternative embodiments, UN-C/A fuel
comprises about 70
vol.% UN blendstock derived from Fischer-Tropsch processing of natural gas,
coal, and/or biomass.
[0045] In embodiments, UN blendstock is produced from triglyceride and/or
fatty acid feedstocks.
UN blendstock n-paraffins may be produced, for example, via: (1) catalytic
triglyceride
9
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
dissociation into fatty acids and glycerol, (2) glycerol removal, and (3)
oxygen removal from fatty
acids (e.g., via catalytic decarboxylation and/or reduction) to yield normal
paraffins. UN blendstock
isoparaffins may be produced via (4) catalytic isomerization of a portion of
these normal paraffins
to yield isoparaffins.
[0046] In embodiments, UN-C/A fuel comprises from about 65 vol.% to about 95
vol.% UN
blendstock derived from catalytic processing of triglyceride feedstock. In
specific embodiments,
UN-C/A fuel comprises about 75 vol.% UN blendstock derived from catalytic
processing of
triglyceride feedstock. In alternative embodiments, UN-C/A fuel comprises
about 80 vol.% UN
blendstock derived from catalytic processing of triglyceride feedstock. In
alternative embodiments,
UN-C/A fuel comprises about 80 to 90 vol.% UN blendstock derived from
catalytic processing of
triglyceride feedstock.
IV. C/A Blendstock
[0047] As mentioned hereinabove, UN blendstock typically has a density below
minimum
requirements. For example, the UN blendstock typically has a density below the
MIL-DTL-83133-
specified minimum requirement of 0.775 kg/L and may be very near to exceeding
or may exceed
the freeze point maximum requirement of less than -47 C. As it is desirable
for the UN-C/A fuel to
meet standard (for example, MIL-DTL-83133-specified) density, freeze point,
and flash point
requirements, the disclosed UN-C/A fuel further comprises at least one
independently-produced
C/A blendstock to obtain required density and cold-flow performance. The C/A
blendstock
comprises primarily hydrocarbons selected from the group consisting of
cycloalkanes and
aromatics. The aviation-grade UN-C/A fuel comprises an appropriate blend of
aromatics and
cycloalkanes whereby requisite density and freeze point specifications of the
resulting high cetane
kerosene fuel are met. In embodiments, the hydrocarbons of the C/A blendstock
are derived from
petroleum feedstocks. In embodiments, the hydrocarbons of the C/A blendstock
are derived from
non-petroleum feedstocks. In embodiments, the hydrocarbons of the C/A
blendstock are derived
from a combination of petroleum and non-petroleum feedstocks. In embodiments,
the UN-C/A fuel
comprises up to 35 vol.% C/A blendstock.
[0048] In embodiments, the C/A blendstock comprises aromatics. In embodiments,
the C/A
blendstock comprises aromatics selected primarily from the group consisting of
C9 to C15
aromatics which provide the requisite density. In embodiments, the aromatics
are primarily
alkylated benzene compounds. In addition to providing density, aromatics may
also contribute to
beneficial seal swelling and may provide needed lubricity and viscosity. In
embodiments, the C/A
blendstock comprises less than about 15 vol.% aromatics. In embodiments, the
C/A blendstock
comprises from about 0 vol.% to about 15 vol.% aromatics.
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
[0049] In embodiments, C/A blendstock comprises cycloalkanes. In embodiments,
the C/A
blendstock comprises cycloalkanes primarily selected from the group consisting
of C9 to C15
cycloalkanes which reduce freeze point (to counteract the freeze point
increase resulting from
aromatic addition) without adversely decreasing flash point. In embodiments,
C/A blendstock
comprises less than about 30 vol.% cycloalkane. In embodiments, suitable
freezepoint are obtained
in the UN-C/A fuel by selection of aromatics (i.e. having high density and low
freezepoint) for the
C/A blendstock such that the C/A blendstock comprises 0% cycloalkanes. In
embodiments, C/A
blendstock comprises from about 0 vol.% to about 30 vol.% cycloalkane. In
embodiments, jet-fuel
compliant UN-C/A fuel comprises up to 95 vol.% of paraffins selected from
isoparaffins and
normal paraffins, from about 0 vol.% to about 30 vol.% cycloalkanes, and from
about 0 vol.% to
about 15 vol.% aromatics. In embodiments, UN-C/A fuel comprises about 95 vol.%
UN blendstock
and about 5% high density low freezepoint aromatic.
[0050] Without limitation, C/A blendstock may be derived from one or a
combination of the
following feedstocks: petroleum, oil shale, oil sands, natural gas, coal,
biomass, vegetable oil,
biomass pyrolysis bio-oil, and other biologically-derived oils. In
embodiments, aviation-grade UN-
C/A kerosene comprises at least 50 weight % of hydrocarbons selected from
cycloalkanes and
aromatics, said hydrocarbons derived from coal, biomass, or a combination
thereof.
[0051] C/A blendstock may be produced by several methods. Figure 2 shows an
embodiment for
the production of C/A blendstock via pyrolysis (heating in a deficiency of
oxygen). Pyrolysis may
be performed by any method known to one of skill in the art. In Figure 2,
pyrolysis feedstock 110
undergoes pyrolysis 120. Suitable pyrolysis feedstock 110 includes, without
limitation, coal, oil
shale, oil sands, biomass, and combinations thereof. Gases 140 and
char/ash/minerals 130 are
removed. Pyrolysis oil vapors are condensed, the resulting pyrolysis oil 150
is hydrotreated as is
known to those of skill in the art. In embodiments, catalytic hydrotreating is
used to reduce the
level of at least one contaminant selected from the group consisting of
nitrogen, sulfur, oxygen, and
metals. In embodiments, pyrolysis oil 150 is treated with hydrogen 180 and the
level of sulfur
and/or nitrogen in pyrolysis oil 150 is reduced via elimination of gas
stream(s) 170 comprising, for
example, hydrogen sulfide and/or ammonia. Via hydrotreating 160, contaminant-
reduced liquid
products 190 are obtained. This procedure is similar to the procedure used in
upgrading crude oil
in a refinery to produce a variety of liquid fuels, as known to those of skill
in the art. Table 3
presents a comparison of pyrolyzed coal tar fractions based on typical boiling
range and major
hydrocarbon constituents.
11
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
[0052]
Table 3: Typical Coal Tar Fractions
Typical HC Constituents and
Fraction Boiling Range, C Carbon Numbers
Ammoniacal Liquor -100 -
Light Oil <170 Benzene, C6; Toluene, C7; Xylene, C8
Middle Oil or Carbolic Oil 170-230 Naphthalene, Cio
Heavy Oil or Creosote Oil 230-270 Naphthalene, Clo
Green Oil or Anthracene Oil 270-360 Anthracene, C14
Residue or Pitch >360 -
[0053] In particular, low-temperature tar and light oils formed from sub-
bituminous and bituminous
coals at temperatures below about 700 C as relatively fluid, dark brown oils
that comprise phenols,
pyridines, paraffins, and/or olefins. The oils are heterogeneous, with any one
component
constituting only a fraction of a percent of the total mass. The lignite tars
may also contain up to
10% of paraffin waxes, so the product has a "butter-like consistency" and
solidifies at temperatures
as high as 6 C to 8 C. The primary high-temperature tar vapors formed above
700 C are more
homogeneous. The light oils are predominantly benzene, toluene, and xylenes
(BTX) and the tars
are bitumen-like viscous mixtures that contain high proportions of
polycondensed aromatics. For
the most part, the pyrolysis tars and oils are not suitable final fuel
products. Often they are
unstable, and when warmed, they polymerize and become more viscous. Ash and
mineral matter
130 is removed in pyrolysis 120, which increases the heating value, but sulfur
and nitrogen are not
completely removed in pyrolysis 120. A more stable and useful product is
obtained by
hydrogenating 160 and removing the sulfur and/or nitrogen from the fuel as
hydrogen sulfide and/or
ammonia in stream(s) 170. These procedures are, as noted previously, similar
to the various
refinery procedures used to upgrade natural crude oils. The hydrotreated
liquid products 190 may
be further refined and upgraded, by any methods known to one of skill in the
art, to yield a mix of
cycloalkanes and aromatics of which the C/A blendstock is comprised.
[0054] In embodiments, the UN-C/A fuel comprises about 20 vol.% C/A blendstock
derived from
pyrolysis processing of a coal tar fraction. In embodiments, the UN-C/A fuel
comprises about 80
vol.% UN blendstock derived from Fischer-Tropsch processing of natural gas,
coal, and/or biomass,
and about 20 vol.% C/A blendstock derived from pyrolysis processing of coal
tar fraction. In
embodiments, UN-C/A fuel comprises about 30 vol.% C/A blendstock derived from
pyrolysis
processing of a high cycloparaffin-content material derived from oil shale or
oil sand feedstock. In
embodiments, UN-C/A fuel comprises about 70 vol.% UN blendstock derived from
catalytic
processing of triglyceride feedstock and about 30 vol.% C/A blendstock derived
from pyrolysis
processing of a high cycloparaffin-content material derived from an oil shale
or oil sand feedstock.
12
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
[0055]In another embodiment of the invention, shown in Figure 3, direct
liquefaction 220 of
liquefaction feedstock 210 is used to produce C/A blendstock. Liquefaction
feedstock 210 may
comprise, for example, coal and/or biomass. There are two basic procedures:
hydroliquefaction and
solvent extraction. In hydroliquefaction, coa1210 is mixed with recycled coal
oi1230 and, together
with hydrogen 240, fed to high-pressure catalytic reactor 220 where
hydrogenation of coal 210
takes place. In solvent extraction, also termed "solvent refining," coal 210
and hydrogen 240 are
dissolved at high pressure in a recycled coal-derived solvent 230 which
transfers hydrogen 240 to
coal 210. After phase separation 260, wherein gases 270 and ash 280 may be
removed from coal
liquid 250 which may be further cleaned and upgraded by refinery procedures to
produce liquid
fuels 290. In solvent refining, with a low level of hydrogen transfer, a
solid, relatively clean fuel
termed "solvent refined coal" 290 is obtained. As in pyrolysis, the compounds
are similar to the
coal tars and highly aromatic in nature. Hydrogenation and selective catalytic
processing, as known
to one of skill in the art, may be performed to yield a mix of cycloalkanes
and aromatics that
provide the C/A blendstock.
[0056] In embodiments, the UN-C/A fuel comprises about 20 vol.% C/A blendstock
derived from
direct liquefaction of a coal feedstock. In embodiments, the UN-C/A fuel
comprises about 80 vol.%
UN blendstock derived from Fischer-Tropsch processing of natural gas, coal,
and/or biomass, and
about 20 vol.% C/A blendstock derived from direct liquefaction of a coal
feedstock.
[0057] In an embodiment, C/A blendstock comprises cycloalkanes obtained by
separation (e.g., via
distillation or extraction) of cycloalkanes selected from the group consisting
of C9-C15
cycloalkanes from petroleum feedstocks. In embodiments, C/A blendstock
comprises aromatic
compounds obtained by separation (e.g., via distillation or extraction) of
aromatic compounds
selected from the group consisting of C9-C15 single-ring aromatic compounds
from petroleum
feedstocks. Suitable petroleum feedstocks comprise oil sand- and/or oil shale-
derived products that
are inherently rich in cycloalkanes.
[0058] In an embodiment, C/A blendstock is produced by catalytic cyclization
and/or reforming of
UN blendstock prepared from triglyceride and/or fatty acid feedstocks as
disclosed hereinabove. In
this embodiment, UN blendstock may be produced via: (1) catalytic triglyceride
dissociation into
fatty acids and glycerol, (2) glycerol removal, (3) oxygen removal from fatty
acids (via catalytic
decarboxylation and/or reduction) to yield normal paraffins, and, to the
extent desired, (4) catalytic
isomerization of a portion of these normal paraffins to yield isoparaffins. In
embodiments, UN-C/A
fuel comprises about 35 vol.% C/A blendstock derived from catalytic processing
of triglyceride
feedstock. In embodiments, UN-C/A fuel comprises about 65 vol.% UN blendstock
derived from
catalytic processing of triglyceride feedstock and about 35 vol.% C/A
blendstock derived from
catalytic processing of triglyceride feedstock.
13
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
[0059] In another embodiment of the invention, C/A blendstock is produced from
biomass-derived
lignin feedstock. C/A blendstock may be produced via catalytic
depolymerization of biomass-
derived lignin feedstock followed by hydroprocessing as required to yield a
desired proportion (for
example, JP-8-quality) of cycloalkanes and aromatics. In embodiments, the UN-
C/A fuel comprises
about 20 vol.% C/A blendstock derived from pyrolysis of biomass-derived
lignin. In alternative
embodiments, UN-C/A fuel comprises about 15 vol.% C/A blendstock derived from
catalytic
processing of lignin. In embodiments, UN-C/A fuel comprises about 80 vol.% UN
blendstock
derived from Fischer-Tropsch processing of natural gas, coal, and/or biomass,
and about 20 vol.%
C/A blendstock derived from pyrolysis processing of biomass-derived lignin. In
embodiments, UN-
C/A fuel comprises about 85 vol.% UN blendstock derived from catalytic
processing of triglyceride
feedstock and about 15 vol.% C/A blendstock derived from catalytic processing
of lignin.
V. UN-C/A Fuel
[0060] A finished UN-C/A fuel may have "drop-in compatibility" with its
petroleum-derived
counterpart, i.e. the UN-C/A fuel may be blended in any proportion, from 0
vol.% to 100 vol.%
with a petroleum-derived counterpart. The disclosed I/N-C/A fuel provides for
the blending of fuel
components (including isoparaffins, normal paraffins, cycloalkanes, and/or
aromatics), at least two
of which are derived from disparate processes, to create UN-C/A fuel. In
embodiments, at least 50
weight % of an aviation-grade UN-C/A kerosene fuel is derived from coal,
natural gas, or a
combination thereof. In embodiments, at least 50 weight % of an UN-C/A fuel is
derived from
biomass. In embodiments, at least 10 weight % of an UN-C/A fuel is derived
from non-cracked
bio-oil. In embodiments, UN-C/A fuel has a cetane number of greater than about
70.
[0061] In embodiments, the I/N-C/A fuel complies with specifications for Jet A
and/or another
civilian jet fuel. In embodiments, the UN-C/A fuel complies with a military
jet fuel specification
selected from JP-8 and other military-grade jet fuel specifications.
[0062] In addition to meeting fuel property and performance requirements
listed in U.S. military
and ASTM (American Society for Testing and Materials) International aviation
jet fuel
specifications, in embodiments, an UN-C/A-blended fuel will also meet
applicable U.S. military-
specified fit-for-purpose requirements that address a variety of fuel
performance and materials
compatibility issues. As mentioned hereinabove, fit-for-purpose requirements
refers to fuel
property requirements that are not necessarily addressed by military or ASTM
standards, but are
important to fuel performance and stability in jet engines and during fuel
handling, distribution, and
storage. Examples of fit-for-purpose requirements include fuel compatibility
with aircraft fuel and
engine system materials of construction, adequate fuel performance in
compression ignition (versus
turbine) engines in a wide variety of ground environments, and possible fuel
performance
14
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
requirements related to swelling of elastomeric seals in, for example, turbine
engines. These fit for
purpose requirements, in addition to feedstock properties and ASTM standards
are used to
determine the optimal ratio of the UN blendstock to the C/A blendstock.
VI. EXAMPLES
Example 1: Fuel Sample A
[0063] A FT fuel produced from natural gas containing iso-paraffinic and
normal paraffin
hydrocarbons did not comply with density requirement of the JP-8 military
specification (MIL-
DTL-83133E). In this example, a mixture of aromatic hydrocarbon fluid
containing aromatic
hydrocarbons ranging in carbon chain length from 8-16, was blended to a
concentration of 23% by
weight with the FT fuel. A summary of results from Fuel Sample A compared to
specification
requirements outlined in MIL-DTL-83133E is provided in Table 4.
[0064]
Table 4: Results from Jet Fuel Specification Tests of Fuel Sample A Comprising
Blend
of Aromatic Hydrocarbon and Fischer-Tropsch Derived Fuel
Specification Test Sample A Military Spec
Acid Number, mg KOH/gm 0.003 0.015 max
Aromatics, vol% 19.4 25 vol% max
Olefins, vol% 0.0 5 vol% max
Sulfur, mass% 0.0 0.30 max
Heat of Combustion, Btu/lb 18500 18400
Distillation:
10% recovered, C 172 205 max
Endpoint, C 274 300 max
Residue, vol% 1.4 1.5 max
Loss, vol% 0.4 1.5 max
Flash Point, C 48 >38
Freeze Point, C -57 -47 max
Hydrogen Content, mass% 14.0 13.4 min
API Gravity @ 60 F 48.2 37.0-51.0
Specific Gravity @ 15 C 0.787 0.775-0.84
[0065] As seen in the data presented in Table 2, the resulting fuel had a
density of 0.788 g/ml
achieving the minimum specification requirement of 0.775 as defined by MIL-DTL-
83133E while
complying with all of the parameters contained within the specification. Data
from gas
chromatography of Sample A and a typical FT fuel is provided in Figure 4.
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
Example 2: Fuel Sample B
[0066] The same FT fuel as used in Example 1 was blended at 82%wt. with 8%wt.
of a mixed
aromatic fluid and 10%wt. cycloparaffinic fluid. A summary of Fuel Sample B
results from key
specification parameters is provided in Table 5.
[0067]
Table 5: Results for Key Jet Fuel Specification Tests of Fuel Sample B
Comprising Blend of
Aromatic and Cycloparaffin Hydrocarbons with Fischer-Tropsch Derived Fuel
Specific Freeze Point, Flash HHV,
Gravity C Point, C MJ/kg
Specification value is
Mil Spec 0.775-0.84 -47 >38C >42.8 a lower heating value
Sample B 0.779 -61.4 48 46.1 Lab analysis
FT Fuel 0.755 -56.7 48 46.6 Lab analysis
[0068] As seen in the results in Table 5, the resulting fuel Sample B
possessed a MIL-DTL-
83133E specification compliant fuel with a density of 0.779 g/ml.
Example 3: Fuel Sample C
[0069] Two hydrocarbon blendstocks, one consisting of normal- and iso-
paraffinic hydrocarbon
and the second consisting a mixture of aromatic and cycloparaffinic
hydrocarbon, were produced
exclusively from crop oil and blended to achieve a fuel sample complying with
the requirements of
MIL-DTL-83133E. In this example, neither fuel blendstock possessed, on its
own, the physical
characteristics required by the specification; however, through blending at a
ratio of 44% normal
and iso-paraffinic blendstock, and 66% aromatic and cycloparaffinic
blendstock, the resulting fuel
achieved the necessary characteristics. A summary of results from Fuel Sample
C compared to
specification parameters outlined in MIL-DTL-83133E is provided in Table 6.
Data from gas
chromatography of Sample C and a typical JP-8 fuel is provided in Figure 5.
[0070]
Table 6: Results from Jet Fuel Specification Tests of Fuel Sample C Comprising
a Blend of
Two Discrete Hydrocarbon Blendstocks Produced from Crop Oil
Specification Test Sample C Military Spec
Aromatics, vol% 19.8 25 vol% max
Olefins, vol% 1.9 5 vol% max
Heat of Combustion, Btu/lb 18400 18400
Distillation:
10% recovered, C 171 205 max
Endpoint, C 255 300 max
Residue, vol% 1.2 1.5 max
Loss, vol% 0.4 1.5 max
Flash Point, C 49 >38
16
CA 02692380 2009-12-22
WO 2009/014859 PCT/US2008/068622
Table 6: Results from Jet Fuel Specification Tests of Fuel Sample C Comprising
a Blend of
Two Discrete Hydrocarbon Blendstocks Produced from Crop Oil
Specification Test Sample C Military Spec
Freeze Point, C -52 -47 max
API Gravity @ 60 F 44.3 37.0-51.0
Specific Gravity @ 15 C 0.805 0.775-0.84
[0071] While preferred embodiments of the invention have been shown and
described,
modifications thereof can be made by one skilled in the art without departing
from the spirit and
teachings of the disclosure. The embodiments described herein are exemplary
only, and are not
intended to be limiting. Many variations and modifications of the invention
disclosed herein are
possible and are within the scope of the invention. Where numerical ranges or
limitations are
expressly stated, such express ranges or limitations should be understood to
include iterative
ranges or limitations of like magnitude falling within the expressly stated
ranges or limitations
(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10
includes 0.11, 0.12, 0.13,
etc.). Use of the term "optionally" with respect to any element of a claim is
intended to mean that
the subject element is required, or alternatively, is not required. Both
alternatives are intended to be
within the scope of the claim. Use of broader terms such as comprises,
includes, having, etc. should
be understood to provide support for narrower terms such as consisting of,
consisting essentially of,
comprised substantially of, etc.
[0072] Accordingly, the scope of protection is not limited by the description
set out above but is
only limited by the claims which follow, that scope including all equivalents
of the subject matter of
the claims. Each and every claim is incorporated into the specification as an
embodiment of the
present invention. Thus, the claims are a further description and are an
addition to the preferred
embodiments of the present invention. The discussion of a reference is not an
admission that it is
prior art to the present invention, especially any reference that may have a
publication date after the
priority date of this application. The disclosures of all patents, patent
applications, and publications
cited herein are hereby incorporated by reference, to the extent they provide
exemplary, procedural
or other details supplementary to those set forth herein.
17
