Note: Descriptions are shown in the official language in which they were submitted.
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PYROLYSIS VAPOR RAPID FILTRATION AND CONVERSION TO FUEL
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a non-provisional application which claims
benefit under 35 USC
119(e) to U.S. Provisional Application Ser. No. 61/699,000 filed September 10,
2012, and U.S.
Non-Provisional Application Serial No. 14/021,021 filed September 9, 2013,
entitled
"GENERATING DEOXYGENATED PYROLYSIS VAPORS," which are incorporated herein
in their entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
[0002] None.
FIELD OF THE DISCLOSURE
[0003] This disclosure relates to systems and methods for the fast
pyrolysis of organic matter
to produce transportation fuel. More specifically, it relates to the rapid
removal of entrained char
particulates from pyrolysis vapors, and optionally, catalytic modification of
pyrolysis vapors
created during the fast pyrolysis of organic matter to create a hydrocarbon
transportation fuel or
a component thereof
BACKGROUND
[0005] The U.S. Renewable Fuel Standards (RFS) mandate requires increasing
volumes of
advanced biofuels to be produced. One method being developed to meet this
mandate is the fast
pyrolysis of biomass. Conventional biomass fast pyrolysis involves the rapid
heating of biomass
in the presence of little or no oxygen. Conventional fast pyrolysis produces
oxygenated
pyrolysis vapors that are highly reactive, along with a solid carbonaceous
char particles that
retain the vast majority of metals (e.g. Na, K, Mg) present in the biomass
feedstock. Pyrolysis
vapor product compounds comprise radicals that often lead to rapid,
uncontrolled
oligomerization or polymerization, which is facilitated by entrainment of
metal-impregnated char
particles that can serve as catalysts for these addition reactions. If left
unchecked, large
molecular weight compounds rapidly form that are extremely difficult to
upgrade to
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transportation fuels. Conventional processes typically avoid this result by
rapidly quenching the
pyrolysis vapors to form a liquid pyrolysis oil. However, this typically 1)
fails to remove all
entrained char and metals, 2) delays upgrading of the product 3) decreases
process efficiency by
condensing to liquid pyrolysis oil, then later re-vaporizing for catalytic
conversion to an
industrial or transportation fuel. Additionally, conventional processes
typically remove entrained
char particles via cyclones (incomplete particulate removal) or conventional
filtration that
requires ongoing maintenance.
[0006] There is a need to improve fast pyrolysis technology for the
production of
hydrocarbons having molecular weights and characteristics fungible with
current hydrocarbon
transportation fuels. Such methods and systems must rapidly stabilize raw
pyrolysis vapors to
prevent uncontrolled polymerization, while also quickly and efficiently
removing entrained char
particulates and associated catalyst poisons to prevent them from contacting
the stabilizing or
upgrading catalysts.
BRIEF SUMMARY OF THE DISCLOSURE
BRIEF DESCRIPTION OF THE DRAWING
[0007] A more complete understanding of the present invention and benefits
thereof may be
acquired by referring to the follow description taken in conjunction with the
accompanying
drawings in which:
[0008] The Figure is a simplified diagram of one embodiment of the
inventive processes and
systems described herein, depicting a moving bed granular filter that receives
pyrolysis vapors
from a pyrolysis reactor and conveys them to a downstream reactor while
simultaneously
conveying a heated heat carrier (optionally comprising a catalyst) and
particulate char filtrate to
the same pyrolysis reactor.
[0009] The invention is susceptible to various modifications and
alternative forms, specific
embodiments thereof are shown by way of example in the drawings. The drawings
may not be to
scale. It should be understood that the drawings and their accompanying
detailed descriptions are
not intended to limit the scope of the invention to the particular form
disclosed, but are
illustrative only of specific embodiments.
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DETAILED DESCRIPTION
[0010] Conventional pyrolysis methods and systems have suffered from either
1) char carry-
over in the pyrolysis vapors, leading to deactivation of downstream upgrading
catalysts, or 2) use
of separation devices such as conventional filter and cyclones to remove char
from pyrolysis
vapors, which results in an undesirable delay prior to either quenching or
catalytically upgrading
the pyrolysis vapors. Such delay can allow undesirable secondary reactions to
occur that produce
excessively large molecular weight products that are difficult to further
upgrade into a
transportation fuel.
[0011] The inventive processes and systems disclosed herein provide a
solution to the
problem of catalyst fouling and poisoning over time, as well as the plugging
of catalyst beds that
receive raw pyrolysis vapors carrying entrained char particles. The processes
and systems
disclosed herein also minimize the delay between production of the pyrolysis
vapors and
catalytic upgrading to products that are fungible with petroleum-derived
transportation fuels, or a
component thereof.
[0012] Pyrolysis vapors are known to be highly reactive, and can rapidly
form high
molecular weight compounds that are above the boiling-point range of typical
hydrocarbon
transportation fuels (i.e., a carbon number greater than about 35). Examples
of typical addition
reactions between compounds typically found in pyrolysis vapors are shown in
Schemes 1-3
below:
Scheme 1: Reaction of propionaldehyde (C3) and methyl furan (C5) to form a C11
molecule.
0
///
0
0
H3
CH3
CH3 0
, ,
H3c/ /// + _ H3C/ HO
CH3
HO
H3C
OH
H3C
Scheme 2: Reaction of propylene (C3) and a vinyl cresol (C9) to form a C12
molecule .
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OH OH
/=CH2 CH3
H3C
r 401
H3C
Scheme 3: Reaction of a vinyl cresol (C9) and a dimethoxy vinyl phenol (C10)
to form a C19
molecule.
OH
OH
H3C HO OH
CH3
0
0 0-CH3
H3C
CH3
[0013] The methods and systems described herein allow rapid
filtration/removal of solid char
particles from raw pyrolysis vapors by immediately directing the vapors
through a moving bed
granular filter (MBGF) comprising a heated heat carrier as the granular filter
material. The heated
heat carrier slowly passes through the MBGF and is conveyed along with char
filtrate to the
pyrolysis reactor to facilitate heat transfer to the biomass feedstock.
[0014] The granular material within the moving bed also serves as the
granular heat carrier
that assists in rapidly transferring heat to the biomass in the pyrolysis
reactor. Char that is removed
from the pyrolysis vapors and retained within the MBGF is then immediately
conveyed along with
the heat carrier to the pyrolysis reactor.
[0015] In certain embodiments, the granular material comprising the moving
bed of the MBGF
also comprises at least one catalyst. One or more catalysts may be included in
a mixture with the
heat carrier. In certain embodiments, the heat carrier itself possess
catalytic activity or be
impregnated with one or more catalysts.
[0016] Pyrolysis vapors filtered by the MBGF optionally contact the at
least one catalyst
within the MBGF, which catalytically upgrades and/or stabilizes the chemical
species within the
pyrolysis vapors to prevent unwanted secondary reactions that produce products
that are difficult
to upgrade to a transportation fuel (or component thereof). In certain
embodiments, the heat
carrier itself may possess catalytic activity, or one or more catalyst(s) may
be impregnated on the
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heat carrier. Alternatively, the heat carrier may be mixed with one or more
catalysts that are
either supported or unsupported.
[0017] Immediately directing raw pyrolysis vapors from a pyrolysis reactor
into a MBGF
comprising at least one catalyst minimizes the time between production of the
pyrolysis vapors and
subsequent upgrading while simultaneously removing char particles that 1)
cause harmful
secondary reactions that limit the upgradability of the vapors and 2) poison
downstream
equipment and catalytic upgrading. The present inventive disclosure also
improves efficiency by
eliminating the heated container that pre-heats the granular heat carrier in a
conventional
pyrolysis system prior to entry of the heat carrier into the pyrolysis
reactor. The heat carrier is
instead heated within the MBGF.
[0018] Rapid heating of the biomass feedstock in an atmosphere containing
little or no oxygen
results in the thermal breakdown of the feedstock, producing oxygenated
hydrocarbon vapors that
are hereinafter termed "pyrolysis vapors". The pyrolysis reactor utilized to
produce these pyrolysis
vapors is compatible with any known pyrolysis reactor configuration or
technology, including, but
not limited to, bubbling bed, circulating bed, moving or fluidized bed,
ablative, vacuum,
microwave heated, plasma-heated, counter-current, auger or combinations of one
or more of
these configurations. The pyrolysis reactor used preferably utilizes a solid
heat carrier and
transfers heat to the biomass feedstock primarily through solid-solid contact.
Preferably, the reactor
comprises at least one auger that assists in rapidly and evenly distributing
heat to the feedstock, as
well as helping to convey the feedstock and optional heat carrier through the
pyrolysis reactor. A
reactor comprising at least one auger is also more efficient in char removal
than, for example, a
fluidized bed reactor that produces char fines by attrition of larger char
particles that then
elutriate into the produced pyrolysis vapors.
[0019] The pyrolysis vapors rise and may be driven by a carrier gas (or
optionally, a pressure
differential) toward an optional disengagement zone that allows separation of
the vapors from
entrained char, heat carrier, and metals while avoiding vapor condensation.
The pyrolysis vapors
then exit the pyrolysis reactor via at least one outlet. Preferably, the at
least one outlet is located
at (or near) the top of the pyrolysis reactor to minimize entrainment of char
particles in the
pyrolysis vapors passing through the outlet(s). The large majority of char
created by pyrolysis of
the feedstock may be eliminated from the reactor in a variety of ways,
depending upon the
pyrolysis technology and configuration utilized. Preventing entrainment of
char prevents
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fouling/poisoning of catalyst(s) located downstream that are utilized to
catalytically stabilize
and/or catalytically upgrade the pyrolysis vapors.
[0020] The pyrolysis vapors passing through the outlet are directed into
the MBGF that is
kept in close proximity in order to remove entrained particulates from the
pyrolysis vapors as
rapidly as possible. The pyrolysis vapors are maintained at all times above a
temperature that
would allow condensation of the vapors to liquid phase. Preferably, this
temperature is between
250 C to 500 C, and is accomplished in part by heating of the granular
filter material within the
MBGF. The pyrolysis vapors may contact the moving bed of granular material in
co-current
flow, cross-current flow, or counter-current flow. In certain embodiments, the
pyrolysis vapors
may contact multiple MBGF within a single container, or multiple containers.
One or more of
the moving beds of granular material may then serve as the heated heat carrier
within the
pyrolysis reactor. Preferably, heat carrier fed to the pyrolysis reactor has
been pre-heated in the
heated container to a temperature of at least 480 C in order to effectively
transfer sufficient heat
to the biomass feedstock to facilitate pyrolysis of the feedstock.
[0021] In certain embodiments, at least one MBGF may comprise a catalyst or
mixtures of
more than one catalyst. In embodiments where more than one MBGF are utilized,
each MBGF
may comprise a different catalyst or different combinations of catalyst. In
some embodiments,
pyrolysis vapors may contact an initial MBGF comprising heat carrier alone,
immediately
followed by a second bed comprising one or more upgrading catalysts. In such
embodiments, the
upgrading catalyst(s) maintain even greater isolation from char particles
entrained in the
pyrolysis vapors.
[0022] Following initial upgrading and/or stabilization of the pyrolysis
vapors within the
MBGF, additional upgrading may be performed. Following upgrading, the product
molecules
have molecular weights that are within the boiling range of a transportation
fuel, such as, but not
limited to gasoline, diesel and gasoil. Without upgrading, the product
compounds may be still be
suitable for use as a component of a hydrocarbon transportation fuel (for
example, as a blend
component at up to about 5-10% (by vol.). With sufficient oxygen removal (and
optionally other
upgrading reactions that increase molecular size), the product optimally
comprises a hydrocarbon
fuel that is fungible with petroleum-derived transportation fuels. In certain
embodiments, for
example, additional oxygen, nitrogen, and sulfur may be removed by
conventional hydrotreating
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processes to produce a finished transportation fuel (as detailed further
below). Each portion of
pyrolysis vapors is maintained in vapor phase both prior to, and during the
upgrading process.
[0023] Optimally, the final product of the process does not include a
significant quantity of
product molecules having a carbon number greater than about 35 carbons, more
preferably no
greater than about 30 carbons. Hydrocarbons larger than this are typically
unsuitable for use as a
transportation fuel or a component thereof, and would have a boiling point
above the boiling
point range of gasoline, kerosene or jet fuel, diesel #1, #2 or #4 and light
fuel oil.
[0024] The length and or volume of the reaction zone or reactor where the
upgrading occurs
is at least partly determined by the kinetics of the reactions occurring
between the catalyst(s) and
the portion of raw pyrolysis vapors. These kinetics can be determined by
conventional
methodology, such as by analyzing the molecular composition of mixtures of
partially-upgraded
pyrolysis vapors and raw pyrolysis vapors over time at a given temperature and
pressure using
conventional gas chromatography / mass spectrometry. The size of the reaction
zone is optimized
such that the average carbon number of product molecules leaving the reaction
zone is between 6
and 35, more preferably between 6-30, or within the carbon number range of
molecules in the
boiling range of transportations fuels such as gasoline, kerosene, jet fuel,
diesel #1, #2 or #4 and
light fuel oil. Optimization of the average carbon number of the product can
be performed based
upon the desired specifications of the product fuel.
[0025] In certain embodiments, a portion of the product of the reacting
(e.g., products with a
carbon number below 6, excess hydrogen, etc.) or a portion of one or more of
the pyrolysis vapor
portions may be returned to the pyrolyzer or to any of the upgrading reactors
to be further
upgraded or utilized in the upgrading of the pyrolysis vapors.
[0026] The low particulate vapors leaving the MBGF may optionally be
further upgraded by
hydrotreating, which is familiar to those having skill in the art and further
reduces oxygen
content of the products while also removing residual sulfur and nitrogen to
levels that meet
government mandates for a finished transportation fuel. Hydrotreating can be
performed in one-
step or multiple steps in the presence of conventional hydrotreating
catalyst(s) or via other
known methods, such as thermal deoxygenation in the presence of a metal
hydroxide (e.g.,
CaOH).
[0027] Each portion of pyrolysis vapors may be diluted with a carrier gas
that may be the
same carrier gas at was utilized in the pyrolysis reactor, or a different gas
added downstream
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from the pyrolysis reactor. The carrier gas may be an inert gas or a reactive
gas. If the carrier gas
is a reactive gas, it may also serve to facilitate one or more upgrading
reactions.
[0028] Examples of biomass feedstock used in the present invention include,
but are not
limited to, oil-containing biomass, such as jatropha plant, macroalgae or
microalgae.
Carbohydrate-based biomass may also be used as feedstock, where carbohydrate-
based refers to
biomass where at least a fraction of its composition is made of carbohydrates.
Carbohydrate-
based biomasses are available from a variety of sources including cellulosic
biomass and algal
biomass. Specific examples of feedstock useful in the current invention
include, but are not
limited to: sugars, carbohydrates, fatty acids, proteins, oils, eucalyptus
oil, forest residues, dead
trees, branches, leaves, tree stumps, yard clippings, wood chips, wood fiber,
sugar beets,
miscanthus, switchgrass, hemp, corn, corn fiber, poplar, willow, sorghum,
sugarcane, palm oil,
corn syrup, algal cultures, bacterial cultures, fermentation cultures, paper
manufacturing waste,
agricultural residues (e.g., corn stover, wheat straw and sugarcane bagasse),
dedicated energy
crops (e.g., poplar trees, switchgrass, and miscanthus giganteus sugarcane)
sawmill and paper
mill discards, food manufacturing waste, meat processing waste, animal waste,
biological waste
and/or municipal sewage.
[0029] The pyrolysis reactor utilized is compatible with any known
pyrolysis reactor
configuration or technology that may benefit from the use of a heat carrier.
Examples of such
configurations may include, but are not limited to, bubbling bed, circulating
bed, moving or
fluidized bed, vacuum, microwave heated, plasma-heated, counter-current,
auger, free-fall or
combinations of one or more of these configurations.
[0030] Figure 1 depicts an exemplary embodiment of a process and system for
conducting
pyrolysis of organic material or biomass to produce a transportation fuel or
component thereof.
A pyrolysis reactor 20 comprises a heat carrier inlet 17 for entry of a heated
granular heat carrier
15, a biomass feedstock inlet 10 for entry of a biomass feedstock 12. The
biomass feedstock 12
is heated in the pyrolysis reactor 20 by at least one heating method that may
include a heating
jacket in the external housing 21, or the heated heat carrier 15. The
pyrolysis reactor 20 is
typically operated to exclude most oxygen or air by the introduction of a
carrier gas. In the
embodiment shown in Figure 1, a carrier gas 19 enters the reactor near the
pyrolysis vapors
outlet 28, although in alternative embodiments, the carrier gas may
alternatively enter the system
via other points of entry, such as the biomass feedstock inlet 10 or heat
carrier inlet 17. As the
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biomass feedstock 12 is rapidly heated to temperatures exceeding 300 C in the
pyrolysis reactor
20, pyrolysis vapors 27 rise into the upper portion of the pyrolysis reactor
20 and are swept
toward the outlet 28 that is preferably located near the top of the reactor to
help prevent solids
from leaving the reactor via this outlet. Alternative embodiments may comprise
additional
outlets for pyrolysis vapors that are not depicted in Figure 1. Preferably,
such outlets would be
positioned on the upper portion of the pyrolysis reactor. Arrangement of
multiple outlets is
within the capability of one having skill in the art.
[0031] During pyrolysis of the biomass feedstock 12 in the pyrolysis
reactor 20, the large
majority of produced char and granular heat carrier is removed near the bottom
of the reactor via
outlet 22. After separation of the granular heat carrier from the char 25 in
separation device 24,
the separated granular heat carrier 23 is conveyed to a heated container 31,
which encloses a
moving bed granular filter (MBGF) 33 that utilizes the separated granular heat
carrier 23 as
granular filter material. The separated granular heat carrier 23 that is
recycled to heated container
33 may be supplemented or replaced by fresh granular heat carrier 32 either
continuously or
periodically. The heated container 31 may periodically also serve as a
regenerator for the
granular heat carrier in the MBGF 31 by heating the granular heat carrier and
optional catalyst(s)
to a temperature that is high enough to remove deposits of coke and any other
catalyst poison,
reactivate catalytic activity, or both.
[0032] Further referring to Figure 1, arranged within close proximity of
the outlet 28 is a
heated container 31 comprising a moving bed granular filter (MBGF) 33, where
the granular
filter material of the MBGF comprises at least one upgrading catalyst. The
pyrolysis reactor 20
is connected via conduit 29 to the heated container 31. The length of conduit
29 is minimized to
allow rapid transport of the pyrolysis vapors to the heated container 31 for
separation of
entrained char as well as rapid catalytic stabilization and/or upgrading of
the pyrolysis vapors 27
by contact with the at least one catalyst in MBGF 33. This produces an
upgraded low-particulate
pyrolysis vapors 35 that may be chemically less reactive, better-suited for
additional subsequent
upgrading to a transportation fuel (or component thereof), or both. The
granular filter material of
the MBGF 33 may optionally comprise mixtures of more than one catalyst, or
multiple beds of
catalyst (either moving or fixed) that contact the pyrolysis vapors in series
or in parallel (not
depicted). In the embodiment of Figure 1, the pyrolysis gas 27 contacts the
MBGF in cross-
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current flow, meaning the flow of gas is perpendicular to the downward flow of
granular filter
material in the MBGF 33.
[0033] Further referring to the embodiment depicted in Figure 1, the
upgraded low-
particulate pyrolysis vapors 35 are conveyed to a second reactor 36 comprising
a bed of one or
more additional upgrading catalysts 37, where the upgraded low-particulate
product 35 is reacted
to produce an upgraded product mixture 38 that when later partially (or
entirely) condensed to
liquid by any known conventional method (not depicted), is fungible with a
petroleum-derived
transportation fuel or a component thereof
[0034] Referring once again to Figure 1 rapid removal of entrained char
particulates from the
pyrolysis vapors 27 by the MBGF 33 within the heated container 31
significantly enhances the
longevity of downstream upgrading catalysts 37 and may also extend the active
lifespan of any
catalysts present within the MBGF. It is common for the biomass feedstock 12
to include
measurable amounts of metals that act as poisons to desirable upgrading
catalysts, and this metal
content becomes concentrated in the char produced during pyrolysis. With the
physical
arrangement described herein and exemplified in Figure 1, downstream upgrading
catalyst(s) 37
that are more susceptible to poisoning by metals may be used to upgrade the
pyrolysis vapors 27,
since the impact of metal poisoning and coke formation is dramatically
reduced. In addition, the
upgraded product mixture 38 is essentially free of solids and metals, thereby
increasing its
stability and eliminating the need for subsequent particle removal.
[0035] Figure 2 depicts a second exemplary embodiment of a process and
system for
conducting pyrolysis of organic material or biomass to produce a
transportation fuel or
component thereof. A pyrolysis reactor 50 comprises an external housing 51, a
biomass
feedstock inlet 40 for entry of a biomass feedstock 42. As the biomass
feedstock 42 is rapidly
heated to temperatures exceeding 300 C in the pyrolysis reactor 50, pyrolysis
vapors 55 rise into
the upper portion of the pyrolysis reactor 50 and are swept toward the
pyrolysis vapors outlet 58.
The biomass feedstock 42 is heated in the pyrolysis reactor 50 by at least one
heating method
that may include a heating jacket in the external housing 51, or via
introduction of a granular
heat carrier 45 via the pyrolysis vapors outlet 58, which also serves as an
inlet for granular heat
carrier 45 such that the pyrolysis vapors flow upward counter-current to the
descending granular
heat carrier 45. The pyrolysis reactor is typically operated to exclude most
oxygen or air by the
introduction of a carrier gas. In the embodiment shown in the Figure, a
carrier gas 49 enters the
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pyrolysis reactor 50 near the outlet 58, although the carrier gas may
alternatively enter the
system via other points of entry, such as the biomass feedstock inlet 40.
[0036] Further referring to Figure 2, a heated container 61 comprising a
moving bed granular
filter (MBGF) 63 is connected by a conduit 57 within close proximity of the
pyrolysis vapors
outlet 58. This allows rapid separation of entrained char from the pyrolysis
vapors 55 to produce
an low-particulate pyrolysis vapors 65 that are better-suited for subsequent
upgrading to a
transportation fuel (or component thereof), or both. The granular filter
material of the MBGF 63
may comprise any material, reactive or inert, that is capable of retaining
heat. Preferably, the
granular heat carrier is sized to facilitate the removal of particulate char
from the pyrolysis
vapors, is attrition-resistant and capable of rapidly transferring heat to the
biomass feedstock 42.
[0037] Further referring to the embodiment depicted in Figure 2, the low-
particulate
pyrolysis gas 65 is conveyed to an upgrading reactor 66 where it is reacted at
a suitable
temperature and pressure with one or more upgrading catalyst(s) 67 to produce
an upgraded
product mixture 69 that when later partially (or entirely) condensed to liquid
by any known
conventional method (not depicted) is fungible with a petroleum-derived
transportation fuel, or a
component thereof.
[0038] In the embodiment shown in Figure 2, char formed during pyrolysis
that is not
conveyed out of the pyrolysis reactor 50 by becoming entrained in the
pyrolysis vapors 55
leaving via outlet 58 instead leaves via outlet 53 along with excess heat
carrier 45 and is
optionally recycled to process, combusted or disposed of In embodiments where
the heat carrier
45 is recycled to process (such as to the MBGF 63 within the heated container
61) it may be first
separated from the char and regenerated by conventional means to remove
accumulated coke and
other catalyst poisons.
[0039] Referring once again to Figure 2, filtering the pyrolysis vapors 55
in the MBGF 63
reduces the quantity of char particulates that become entrained in low-
particulate pyrolysis
vapors 65, and reduces exposure of the one or more upgrading catalyst(s) 67
within upgrading
reactor 66. This significantly enhances the longevity of the upgrading
catalyst(s) 67, since the
impact of metal poisoning and coke formation is dramatically reduced (as
described above).
[0040] Figure 3 depicts a third exemplary embodiment of a process and
system for
conducting pyrolysis of organic material or biomass to produce a
transportation fuel or
component thereof. A pyrolysis reactor 80 comprises an external housing 81, a
heat carrier inlet
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77 for entry of a heated granular heat carrier 75, a biomass feedstock inlet
70 for entry of a
biomass feedstock 72 and one or more helical augers 82 that when driven by a
motor 85, rotate
about a longitudinal axis to facilitate the transport of the biomass feedstock
72 and the heated
granular heat carrier 75 along the length of the reactor from an inlet end
portion 78 towards an
outlet end portion 88. Proximal to the outlet end portion 88, the large
majority of produced char
and granular heat carrier falls into a char catch 91 by gravitational force
and is removed 92. A
heated container 98 contains a moving bed granular filter (MBGF) 99 that
utilizes the heated
granular heat carrier 75 as the granular filter material. The biomass
feedstock 72 is heated in the
pyrolysis reactor 80 by at least one heating method that may include a heating
jacket in the
external housing 81, one or more heated augers 82, or via introduction of
heated granular heat
carrier 75 via the heat carrier inlet 77 proximal to the inlet end portion 78.
[0041] The pyrolysis reactor is typically operated to exclude most oxygen
or air by the
introduction of a carrier gas. In the embodiment shown in Figure 3, a carrier
gas 79 enters
through carrier gas inlet 83, although the carrier gas may alternatively enter
the system via other
points of entry, such as the biomass feedstock inlet 70 or heat carrier inlet
77. As the biomass
feedstock 72 is rapidly heated in the pyrolysis reactor, the majority of char
formed during
pyrolysis is conveyed by the two adjacent parallel augers 82 along with the
heated granular heat
carrier 75 towards the second end portion 88. The large majority of char and
heated granular heat
carrier 75 fall together into the char catch 91 and are then removed 92 and
optionally recycled to
process (for example, via inlet 107), combusted or disposed of In embodiments
where the heated
granular heat carrier 75 is recycled to process, it may be first separated
from the char and
regenerated by conventional means to remove accumulated coke and other
catalyst poisons (not
depicted).
[0042] Again referring to Figure 3, pyrolysis vapors 87 rise into the upper
portion of the
pyrolysis reactor 80 and are swept toward the outlet end portion 88, exiting
through a first outlet
93 that is preferably located near the top of the reactor to help prevent
solids from leaving the
reactor via this outlet. Alternative embodiments may comprise additional
outlets for pyrolysis
vapors that are not depicted in Figure 3. Such outlets may be grouped in close
proximity to the
first outlet 93, or may be spaced at intervals along the length of the
pyrolysis reactor 80.
Arrangement of such outlets is within the capability of one having skill in
the art. Arranged
within close proximity of the first outlet 93 is a heated container 98
comprising a moving bed
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granular filter (MBGF) 99, where the granular filter material of the MBGF 99
comprises at least
one upgrading catalyst. The pyrolysis reactor 80 is in close proximity to the
heated container 98
to allow rapid separation of entrained char from the pyrolysis vapors 87 as
well as rapid
upgrading of the pyrolysis vapors 87 by direct contact with the granular
filter material
(comprising at least one upgrading catalyst) in the MBGF 99 to produce an
upgraded low-
particulate product 106 that may be chemically less reactive, better-suited
for additional
subsequent upgrading to a transportation fuel, or both. The granular filter
material of the MBGF
99 may optionally comprise mixtures of more than one catalyst, or multiple
beds of catalyst
(either moving or fixed) that contact the pyrolysis vapors either in series or
in parallel.
[0043] Further referring to the embodiment depicted in Figure 3, the
upgraded low-
particulate product 106 is conveyed to a second upgrading reactor 110 where it
is reacted at a
suitable temperature and pressure with one or more additional upgrading
catalyst(s) 112 to
produce an upgraded product mixture that when partially- or wholly-condensed
to liquid (not
depicted), is fungible with a petroleum-derived transportation fuel or a
component thereof.
[0044] Heated granular heat carrier containing filtered char 94 leaves the
heated container 98
via an outlet near the bottom of the heated container 98 and is separated from
the char in
separation device 95 to produce separated char 96 and the heated granular heat
carrier 75 that is
then conveyed to the pyrolysis reactor 80.
[0045] Figure 4 depicts a fourth exemplary embodiment of a process and
system for
conducting pyrolysis of organic material or biomass to produce a
transportation fuel or
component thereof. A pyrolysis reactor 130 comprises an external housing 131,
a heat carrier
inlet 127 for entry of a heated granular heat carrier 125, a biomass feedstock
inlet 120 for entry
of a biomass feedstock 122. The biomass feedstock 122 is heated in the
pyrolysis reactor 130 by
at least one heating method that may include a heating jacket in the external
housing 131, one or
more heated augers 132, or by the heated granular heat carrier 125. The
pyrolysis reactor 130 is
typically operated to exclude most oxygen or air by the introduction of a
carrier gas 129 via a
carrier gas inlet 133. Twin adjacent helical augers 132 are driven by a motor
135 and rotate about
a longitudinal axis to facilitate the transport of the biomass feedstock 122
and the heated granular
heat carrier 125 along the length of the reactor from an inlet end portion 128
towards an outlet
end portion 138As the biomass feedstock 122 is rapidly heated in the pyrolysis
reactor 130,
pyrolysis vapors 137 rise into the upper portion of the pyrolysis reactor 80,
exiting through a first
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outlet 153 that is preferably located near the top of the reactor to help
prevent solids from leaving
the reactor via this outlet. Alternative embodiments may comprise additional
outlets for pyrolysis
vapors that are not depicted in Figure 4. Proximal to the outlet end portion
138, the large
majority of produced char and heated granular heat carrier 125 falls into a
char catch 141 by
gravitational force and is removed 142. After separation of the heated
granular heat carrier 125
from the char, the granular heat carrier may optionally be conveyed to heated
container 151 that
contains a moving bed granular filter (MBGF) 149 that utilizes the heated
granular heat carrier
125 as its granular filter material. Alternatively, heated container 151
receives fresh granular heat
carrier (or a mixture of fresh and recycled granular heat material) via inlet
157.
[0046] Further referring to Figure 4, arranged within close proximity of
the first outlet 153 is
a heated container 151 comprising a moving bed granular filter (MBGF) 149,
where the granular
filter material of the MBGF 149 comprises at least one upgrading catalyst. In
the embodiment
shown, the pyrolysis reactor 130 is in close proximity to the heated container
41 to allow rapid
separation of entrained char from the pyrolysis vapors 37 as well as rapid
upgrading of the
pyrolysis vapors 137 to produce an upgraded low-particulate product 166 that
may be chemically
less reactive, better-suited for additional subsequent upgrading to a
transportation fuel (or
component thereof), or both. the upgraded low-particulate product 166 is
conveyed to a second
upgrading reactor 174 where it is reacted at a suitable temperature and
pressure with one or more
additional upgrading catalyst(s) 178 to produce an upgraded product mixture
180 that when
partially- or wholly-condensed to liquid (not depicted), is fungible with a
petroleum-derived
transportation fuel or a component thereof
[0047] The granular filter material (granular heat carrier) of the MBGF 149
may optionally
comprise mixtures of more than one catalyst, or multiple beds of catalyst
(either moving or
fixed) that contact the pyrolysis vapors in series or in parallel. The
granular filter material is kept
inside the heated container 151 long enough to allow heating of the granular
filter material to
become the heated granular heat carrier. Used granular filter material
carrying char particles
removed from the pyrolysis vapors 137 within the MBGF 149 leaves the heated
container 151
via conduit 154 and is conveyed to the granular heat carrier inlet 127.
[0048] To reduce granular heat carrier entrainment that would lead to
granular heat carrier
entrainment in the pyrolysis vapors, the median granular heat carrier particle
size is greater than
about 100 microns, preferably greater than about 250 microns and most
preferably greater than
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300 microns. For similar reasons, the bulk density of the granular heat
carrier particles is
typically at least 500 kg/m3, and preferably greater than about 1,000 kg/m3.
[0049] While a significant quantity of heat for performing pyrolysis of the
feedstock is
derived from the heated granular heat carrier, the temperature within the
pyrolysis reactor may
be maintained via one or more additional mechanisms, such as heating of the
reactor walls,
heating of the at least one auger, microwave or inductive heating, addition of
a heated carrier gas
and microwave heating. Regardless of the heating mechanism utilized,
preferably the pyrolysis
reactor and its contents are maintained at a temperature of at least 315 C.
[0050] Heat carrier may be composed of a variety of materials that are
capable of retaining
heat. Preferably, the granular heat carrier is also efficient in absorbing
heat as well as transferring
heat to a biomass feedstock.
[0051] As previously mentioned, in certain embodiments a carrier gas is
employed that may
comprise one or more of many gases that are either inert or reactive. For
example, the carrier gas
may comprise gases such as nitrogen, helium, argon, hydrogen, methane and
mixtures thereof If
the carrier gas comprises a reactive gas, the reactive gas may optionally
react with the biomass
during pyrolysis, may serve as a reactant when the pyrolysis products are
upgraded by contacting
the upgrading catalyst(s), or both. The carrier gas may be injected into the
system at more than
one point, or injected simultaneously at multiple points. One point may
comprise combining the
carrier gas with the feedstock prior to entering the pyrolysis reactor, while
another may comprise
injecting the carrier gas directly into the pyrolysis reactor proximal to the
biomass feedstock
inlet. A third point may comprise injecting the carrier gas proximal to the
first outlet of the
pyrolysis reactor. This may be preferable if the carrier gas is to be used as
a reactant during
upgrading of the primary pyrolysis product.
[0052] In certain embodiments, a gas may be injected just upstream of the
pyrolysis reactor
first outlet in order to 1) assist in preventing entrained char and heat
carrier particles from
leaving the pyrolysis reactor, 2) quench the primary pyrolysis product to a
lower temperature, 3)
heat the primary pyrolysis product to a higher temperature, or combinations
thereof In
embodiments where the carrier gas serves to quench the primary pyrolysis
product, such
quenching may prevent coking. Embodiments where the carrier gas serves to heat
the primary
pyrolysis product may prevent formation of char and secondary pyrolysis
reactions that may
reduce the subsequent upgradability of the primary pyrolysis product to a bio-
derived fuel.
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However, quenching is limited such that the quenched primary pyrolysis product
does not
condense prior to contacting the upgrading catalyst(s). Typically, this
requires that the quenched
pyrolysis vapors maintain a temperature of at least 250 C to prevent
condensation to liquid
phase.
[0053] The volumetric flow rate, or "standard gas hourly space velocity"
(SGHSV) of the
carrier gas is adjusted to minimize the time between pyrolysis and catalytic
upgrading, such that
the upgrading catalyst (or optionally, catalysts) contacts primary products of
pyrolysis and not
larger secondary products that are more difficult to upgrade to a bio-derived
transportation fuel.
Volumetric flow rate for a given embodiment depends upon factors including,
but not limited to,
the volume of the pyrolysis reactor, the temperature and pressure at which the
pyrolysis reactor is
maintained, the feed rate of the biomass feedstock to the pyrolysis reactor,
and the type of
feedstock utilized. A paper by J.N. Brown, et al. provides one example of how
these variables
can be adjusted to determine an optimal volumetric flow rate for a desired
pyrolysis outcome,
including, for example, the pyrolysis liquid to pyrolysis gas ratio, and the
relative percentage of
the feedstock converted to char.
[0054] The pressure maintained within the pyrolysis reactor is generally
within a range of
about 0 psig to 3000 psig. Preferably, the pyrolysis reactor is maintained at
a pressure in the
range of 100 psig to 500 psig to increase throughput of biomass feedstock, and
in certain
embodiments, facilitate catalytic upgrading of the primary pyrolysis product.
The pyrolysis
reactor operates at a temperature between 300 C and 700 C and pressures
between 0 psig and
2500 psig. The carrier gas for the pyrolyzer may be any mixture of gases with
less than 22 vol%
molecular oxygen, but preferably less than 0.5 vol% molecular oxygen.
Preferably gases are
hydrogen, nitrogen, methane, carbon dioxide, carbon monoxide, or some
combination thereof.
Gases from the pyrolysis process may also be recycled to serve as part or all
of the carrier gas.
[0055] The physical distance between the pyrolysis reactor and the
upgrading catalyst(s) may
vary, but is preferably minimized, taking into consideration the space
velocity of the primary
pyrolysis vapors (optionally in a mixture with a carrier gas) out of the
pyrolysis reactor.
Minimizing this distance assists in decreasing the time between production of
the primary
pyrolysis vapors and subsequent contacting with one or more upgrading
catalyst(s). Through
optimizing the variables of distance and space velocity, the inventive
processes and systems
described herein assures that the upgrading catalyst contacts and
catalytically upgrades primary
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pyrolysis vapor compounds produced from pyrolysis and not subsequent secondary
products
created by non-preferred reactions as little as 0.25 seconds after production
of the pyrolysis
vapors. Generally, the distance between the pyrolyzer and the upgrading
catalyst(s) is less than 4
ft. More preferably, this distance is less than 1 ft., and most preferably,
less than 6 inches.
[0056] Optionally, a disengagement zone is located near the at least one
outlet of the
pyrolysis reactor that may include additional features to limit reactivity of
the pyrolysis vapors
prior to contact with the upgrading catalyst(s). Such features may include,
but are not limited to,
temperature control, introduction of a gas or fluid to quench the primary
pyrolysis product (as
mentioned previously), flow control through judicious choices in geometry
(preferably, a
geometry minimizing bends and small orifices to decrease the potential for
vapor condensation,
the presence of a pre-catalyst (such as zeolite monolith, or any of the above-
mentioned
upgrading catalysts) at the interface between reactors.
[0057] After exiting the pyrolysis reactor along with produced char, the
granular heat carrier,
optionally comprising one or more catalysts, may be periodically or
continuously passed through
a regenerator for de-coking as needed, then returned to the container
comprising the MBGF. The
heat carrier could optionally be diverted from other points in the system for
regeneration. Fresh
heat carrier, optionally comprising one or more catalysts, may be added on a
periodic or
continuous basis to the system to compensate for catalyst attrition,
deactivation or both.
[0058] Additional upgrading catalysts may be employed in separate catalyst
beds located
downstream from the MBGF. Optionally, multiple upgrading catalyst beds may be
placed within
a single reactor and operated in series, or as a mixture of upgrading
catalysts. In certain
embodiments, multiple upgrading catalyst beds may be operated in different
reactors, in parallel
or series to facilitate different upgrading pathways. If multiple upgrading
reactors are utilized,
different conditions may be maintained in each reactor in order to facilitate
a given catalytic
reaction. To facilitate flow of the pyrolysis vapors through multiple
reactors, a pressure
differential may be maintained wherein the pressure in each successive reactor
progressively
decreases. These upgrading beds may utilize any known configuration including,
but not limited
to, fixed bed, bubbling bed or circulating bed to remove residual
particulates. Such methods may
be as described in US8268271, which is hereby incorporated by reference,
[0059] Examples of some upgrading catalysts that may be useful for the
present invention,
along with typical reaction conditions are disclosed in US Pat. App.
13/416,533, although any
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catalyst known to catalyze the conversion of biomass-derived pyrolysis
products to a fuel range
hydrocarbon or an intermediate compound may be utilized. The upgrading
catalyst(s) may
include, but are not limited to, zeolites, metal modified zeolites, and other
modified zeolites.
Other catalysts may include forms of alumina, silica-alumina, and silica,
unmodified or modified
with various metals, not limited to but including, Nickel, Cobalt, Molybdenum,
Tungsten,
Cerium, Praseodymium, Iron, Platinum, Palladium, Ruthenium and Copper and
mixtures thereof
Still other catalysts may include unsupported metals, supported or unsupported
metal oxides or
metal phosphides, and mixtures thereof Catalyst types include deoxygenation
catalysts,
hydrogenation catalysts, hydrodesulfurization catalysts, hydrodenitrogenation
catalysts,
hydrocracking catalysts, water-gas-shift catalysts, and condensation
catalysts. Catalysts may be
sulfided or un-sulfided.
[0060] In certain embodiments employing a hydrogenation catalyst as an
upgrading catalyst,
the hydrogenation catalyst may selected from the group consisting of ceria
(Ce), magnesium
(Mg), nickel (Ni), cobalt (Co), gold (Au), iridium (Ir), osmium (Os),
palladium (Pd), platinum
(Pt), rhodium (Rh), ruthenium (Ru) and combinations thereof In certain
embodiments
employing a condensation catalyst as an upgrading catalyst, the catalyst is
selected from the
group consisting of alumina, silica, silica-alumina, zirconia, titania, ceria,
manganese oxide,
magnesium, praseodymium oxide, samarium oxide, and combinations thereof
Optionally, the
condensation catalyst comprises a promoter metal selected from the group
consisting of copper
(Cu), nickel (Ni), cobalt (Co), Iron (Fe), gold (Au), iridium (Ir), osmium
(Os), palladium (Pd),
platinum (Pt), rhodium (Rh), and combinations thereof In certain embodiments
employing a
polishing catalyst as an upgrading catalyst, the polishing catalyst is
selected from the group
consisting of molybdenum (Mo), tungsten (W), cobalt (Co), nickel (Ni), NiW,
NiMo, NiMoW,
CoMo and combinations thereof. The polishing catalyst may be associated with a
solid support
material that may include carbon, alumina, silica, zeolite, ceramic, A1203,
and other known solid
support materials.
[0061] The catalytic upgrading of the pyrolysis vapors may result in
product that is less
reactive, has a lower or higher molecular weight, a lower oxygen content, a
lower water content,
an altered range of organic chemical species or combinations of more than one
of these effects
when compared to pyrolysis vapors that have not been catalytically upgraded.
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[0062] The residence time of the pyrolysis vapors in the MBGF and each
upgrading reactor
generally ranges from 0.01 sec to 1000 sec. Preferably, the residence time is
in a range from
0.05 sec to 400 secs. More preferably, the residence time is in a range from
0.1 sec to 200 sec.
Most preferably, the residence time is in a range from 0.1 sec to 100 sec.
[0063] The temperature maintained within the MBGF and each upgrading
reactor is
generally in the range from 72 F to 1500 F. Preferably, the temperature is in
the range from 100
F to 1000 F, although if multiple upgrading reactors are used, the MBGF and
each upgrading
reactor each may be maintained at a different temperature within this range.
[0064] Certain upgrading reactions are advantageously conducted at a
pressure that is greater
than atmospheric pressure. The pressure that is maintained in the MBGF and
each one or more
upgrading reactors may range from 0-3000 psig, although a preferred pressure
range is zero to
1000 psig. In certain embodiments, the pressure may range from 10 to 800 psig,
from 20 to 650
psig, from 100 to 500 psig. An exemplary pressure might be 400 psig. If
multiple upgrading
reactors are used, the MBGF and each upgrading reactor may be maintained at a
different
pressure within this range, although the pressure within the MBGF will
typically match the
pressure within the pyrolysis reactor to facilitate the flow of materials and
gases between them.
[0065] The flow of pyrolysis vapors within the MBGF may be horizontal if
encountering the
moving bed in a cross-flow configuration, or preferably upward if encountering
the moving bed
filter in a counter-current flow configuration. The flow of pyrolysis vapors
within each
upgrading reactor is preferably upward, although downward or lateral gas flow
may also be
utilized.
[0066] Upon exiting the final upgrading reactor, the upgraded product may
be directed to a
condensation system that functions to reduce the temperature to a temperature
that is at or below
the dew point for at least one component of the product, thereby allowing
condensation and
collection of that component as a liquid transportation fuel or transportation
fuel component that
may be utilized as blendstock to make a finished transportation fuel.
Typically, the quenching
conditions utilized do not result in the condensation of methane, but
preferably will condense
hydrocarbons containing four or more carbons. Hydrogen may be separated from
the non-
condensable gas by a variety of conventional methods and recycled as at least
a portion of the
carrier gas, thereby also serving as a source of reducing equivalents for
pyrolysis vapor
upgrading reactions. In certain embodiments, recycled hydrogen may be added
directly into, or
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just upstream from, an upgrading reactor to facilitate one or more upgrading
reactions.
Alternatively, the entirety, or some fraction, of the bulk non-condensable gas
is used for this
same purpose. In another embodiment, the entirety, or some fraction, of the
bulk of the non-
condensable gas is sent to a combustor or hydrogen generation unit (e.g., a
reformer) to generate
either heat or hydrogen, respectively. The resulting heat or hydrogen may then
be partially or
entirely recycled back to the process.
HYPOTHETICAL EXAMPLE
[0067] Upon combining and reacting at least one partially-upgraded stream
of pyrolysis
vapors with a stream of non-upgraded pyrolysis vapors, a series of reactions
take place that
increase the molecular weight and carbon number of the product compounds.
Chemical reactions
taking place may include condensation, dimerization, oligomerization, and
alkylation, among
others. The increase in average molecular weight resulting from the reacting
of these streams is
limited by the relative abundance of reactive functional groups in the
partially-stabilized streams
of pyrolysis vapors. Examples of such reactive functional groups include, but
are not limited to,
aldehydes, ketones, alcohols. Olefins also are conducive to reactions leading
to products of
increased molecular weight in the inventive process. The reaction pathways
provided in Scheme
1-3 (see above) are intended as non-limiting examples demonstrating how
certain oxygenated
hydrocarbons present in primary pyrolysis vapors can be converted to molecules
having
molecular weights in the gasoline, diesel and gasoil boiling range and
suitable for use as a
hydrocarbon transportation fuel.
DEFINITIONS
[0068] As used herein, the term "entrainment" is defined as transport of a
solid particle by a
gas stream. Entrainment of a given solid particle typically occurs when the
local velocity of a
gas stream exceeds the terminal falling velocity of the particle.
[0069] As used herein, the term "standard gas hourly space velocity" or
"SGHSV" refers to
the gas hourly space velocity of a gas stream measured at standard conditions.
[0070] As used herein, the term "fuel component" is defined as a mixture of
chemical
compounds suitable for blending with, and comprising at least a portion of, a
finished
transportation fuel.
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[0071] As used herein, the terms "stabilize" and "stabilizing" are defined
as removing at
least a portion of the reactive functional groups or moieties present on the
chemical compounds
found in pyrolysis vapors.
[0072] As used herein, the term "transportation fuel" is defined as fuels
having carbon
numbers within the range of molecules suitable for use in hydrocarbon
transportation fuels,
including gasoline, kerosene, jet fuel, diesel #1, #2 or #4 and light fuel
oil.
[0073] As used herein, the term "upgrading catalyst" is defined as any
catalyst that facilitates
chemical reactions within the molecules present in pyrolysis vapors (resulting
from fast-
pyrolysis of biomass) that converts them to products suitable for use in a
transportation fuel, a
transportation fuel component, or that converts them to intermediate products
(including
stabilized, less reactive intermediate products) that are more easily further
converted to a
transportation fuel or transportation fuel component.
[0074] In closing, it should be noted that the discussion of any reference
is not an admission
that it is prior art to the present disclosure, in particular, any reference
that may have a
publication date after the priority date of this application. At the same
time, each and every
claim below is hereby incorporated into this detailed description or
specification as an additional
embodiment of the present invention.
[0075] Although the systems and processes described herein have been
described in detail, it
should be understood that various changes, substitutions, and alterations can
be made without
departing from the spirit and scope of the invention as defined by the
following claims. Those
having skill in the art may be able to study the preferred embodiments and
identify additional
variants of the invention that are not exactly as described herein, but that
remain within the
scope of the claims. The description, abstract and drawings are not intended
to limit the scope of
the invention. Instead, the invention is specifically intended to be as broad
as the claims below
and their inventive equivalents.
REFERENCES
[0076] All of the references cited herein are expressly incorporated by
reference. The
discussion of any reference is not an admission that it is prior art to the
present invention,
especially any reference that may have a publication data after the priority
date of this
application. Incorporated references are listed again here for convenience:
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1. Brown, J.N., et al. "Process Optimization of an Auger Pyrolyzer with Heat
Carrier Using Response Surface
Methodology." Biores. Tech. 103:405-4141(2012).
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