U.S. patent application number 14/920488 was filed with the patent office on 2016-05-26 for catalytic fast pyrolysis process.
The applicant listed for this patent is Anellotech, Inc.. Invention is credited to Charles Sorensen.
Application Number | 20160145496 14/920488 |
Document ID | / |
Family ID | 56009558 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160145496 |
Kind Code |
A1 |
Sorensen; Charles |
May 26, 2016 |
CATALYTIC FAST PYROLYSIS PROCESS
Abstract
The present invention provides an improved catalytic fast
pyrolysis process for increased yield of useful and desirable
products. The process comprises the steps of: a) feeding biomass, a
specific catalyst composition and transport fluid to a catalytic
fast pyrolysis process fluidized bed reactor maintained at reaction
conditions to manufacture a raw fluid product stream, b) feeding
the raw fluid product stream of step a) to a catalyst separation
and stripping system to produce separated catalyst and a fluid
product stream, c) feeding the fluid product stream of step b) to a
vapor/liquid separation system to produce a liquid phase stream and
a vapor phase stream comprising benzene, toluene and xylenes, d)
feeding the vapor phase stream of step c) to a product recovery
system to recover benzene, toluene and xylenes, and e) recycling at
least a portion of the recovered toluene of step d) to the
fluidized bed reactor of step a).
Inventors: |
Sorensen; Charles;
(Haverstraw, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Anellotech, Inc. |
Pearl River |
NY |
US |
|
|
Family ID: |
56009558 |
Appl. No.: |
14/920488 |
Filed: |
October 22, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62082419 |
Nov 20, 2014 |
|
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Current U.S.
Class: |
201/2.5 |
Current CPC
Class: |
Y02P 20/145 20151101;
C10B 49/22 20130101; C10G 1/086 20130101; Y02E 50/14 20130101; B01J
29/40 20130101; C10G 1/08 20130101; Y02E 50/10 20130101; C10B 53/02
20130101; C10G 2400/30 20130101; C10B 57/06 20130101; C10G 1/002
20130101 |
International
Class: |
C10B 53/02 20060101
C10B053/02; C10B 27/06 20060101 C10B027/06; C10B 57/06 20060101
C10B057/06 |
Claims
1. An improved catalytic fast pyrolysis process comprising steps
of: a) feeding biomass, catalyst composition, and transport fluid
to a catalytic fast pyrolysis process fluidized bed reactor
maintained at reaction conditions to manufacture a raw fluid
product stream, b) feeding the raw fluid product stream of step a)
to a solids separation and stripping system to produce separated
solids and a fluid product stream, c) feeding the fluid product
stream of step b) to a vapor/liquid separation system to produce a
liquid phase stream comprising components selected from the group
consisting of water, char, coke, ash, catalyst fines and
combinations thereof, and a vapor phase stream comprising benzene,
toluene and xylenes, d) feeding the vapor phase stream of step c)
to a product recovery system to recover benzene, toluene and
xylenes, and e) recycling at least a portion of the recovered
toluene of step d) to the fluidized bed reactor of step a).
2. The process of claim 1 wherein the crystalline molecular sieve
of the catalyst composition of step a) is characterized by a
silica/alumina mole ratio greater than 12 and a Constraint Index
from 1 to 12.
3. The process of claim 1 wherein the fluidized bed reaction
conditions include a temperature of from 300 to 1000.degree. C. and
pressure from 100 to 1500 kPa.
4. The process of claim 2 wherein the crystalline molecular sieve
of the catalyst composition of step a) is characterized by a
silica/alumina mole ratio from greater than 12 to 240 and a
Constraint Index from 5 to 10.
5. The process of claim 2 wherein the catalyst composition of step
a) comprises a crystalline molecular sieve having the structure of
ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-50 or
combinations thereof.
6. The process of claim 4 wherein the catalyst composition of step
a) comprises a crystalline molecular sieve having the structure of
ZSM-5, ZSM-11, ZSM-22, ZSM-23 or combinations thereof.
7. The process of claim 5 wherein the catalyst composition of step
a) comprises a crystalline molecular sieve having the structure of
ZSM-5.
8. The process of claim 1 wherein from 5 to 99% of the recovered
toluene of step d) is recycled to the fluidized bed reactor of step
a).
9. The process of claim 8 wherein from 30 to 50% of the recovered
toluene of step d) is recycled to the fluidized bed reactor of step
a).
10. The process of claim 1 wherein the solids separation and
stripping system of step b) comprises a cyclone or series of
cyclones.
11. The process of claim 1 wherein the vapor/liquid separation
system of step c) comprises venturi systems, quench systems,
condensers, chillers, absorption systems, scrubbers, demisters, or
combinations thereof.
12. The process of claim 1 wherein the product recovery system of
step d) comprises condensers, chillers, absorption systems,
demisters, or combinations thereof.
13. An improved catalytic fast pyrolysis process comprising steps
of: a) feeding biomass, catalyst composition comprising a
crystalline molecular sieve having the structure of ZSM-5, and
transport fluid to a catalytic fast pyrolysis process fluidized bed
reactor maintained at reaction conditions including a temperature
from 300 to 1000.degree. C., pressure from 100 to 1500 kPa and
catalyst-to-biomass mass ratio of from 0.1 to 40 to manufacture a
raw fluid product stream, b) feeding the raw fluid product stream
of step a) to a solids separation and stripping system to produce
separated solids and a fluid product stream, c) feeding the fluid
product stream of step b) to a vapor/liquid separation system to
produce a liquid phase stream comprising components selected from
the group consisting of water, char, coke, ash, catalyst fines and
combinations thereof, and a vapor phase stream comprising benzene,
toluene and xylenes, d) feeding the vapor phase stream of step c)
to a product recovery system to recover benzene, toluene and
xylenes, and e) recycling from 5 to 99% of the recovered toluene of
step d) to the fluidized bed reactor of step a).
14. The process of claim 13 wherein the catalyst composition
comprises binder material selected from the group consisting of
porous inorganic oxide, clay or combinations thereof.
15. The process of claim 14 wherein the inorganic oxide comprises
alumina, zirconia, silica, magnesia, thoria, titania, boria or
combinations thereof.
16. The process of claim 14 wherein the clay comprises bentonite,
kieselguhr or combinations thereof.
17. The process of claim 13 wherein from 30 to 50% of the recovered
toluene of step d) is recycled to the fluidized bed reactor of step
a).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an improved catalytic fast
pyrolysis process. In particular, it relates to an improved
catalytic fast pyrolysis process for producing benzene and
xylenes.
BACKGROUND OF THE INVENTION
[0002] The needs for travel and consumer goods have driven the ever
increasing consumption of fossil fuels such as coal and oil,
typically obtained from deep underground. The extraction of fossil
fuels by mining and drilling has often been accompanied by
environmental and political costs. Furthermore, as the more
accessible sources of fossil fuels are being used up, this has led
to the pursuit of more expensive extraction technologies such as
fracking and deep sea drilling. Additionally, the consumption of
fossil fuels causes higher levels of atmospheric carbon, typically
in the form of carbon dioxide.
[0003] To reduce these problems, there have been extensive efforts
made in converting biomass to fuels and other useful chemicals.
Unlike fossil fuels, biomass is renewable and carbon-neutral; that
is, biomass-derived fuels and chemicals do not lead to increased
atmospheric carbon since the growth of biomass consumes atmospheric
carbon.
[0004] Much of the work on biomass has involved converting refined
biomass including vegetable oils, starches, and sugars; however,
since these types of refined biomass may alternatively be consumed
as food, there is even a greater utility for converting non-food
biomass such as agricultural waste (bagasse, straw, corn stover,
corn husks, etc.), energy crops (like switch grass and saw grass),
trees and forestry waste, such as wood chips and saw dust, waste
from paper mills, plastic waste, recycled plastics or algae, in
combination sometimes referred to as cellulosic biomass. Biomass
generally includes three main components: lignin, hemicellulose,
and cellulose.
[0005] Generating fuels and chemicals from biomass requires
specialized conversion processes different from conventional
petroleum-based conversion processes due to the nature of the
feedstock. High temperatures, solid feed, high concentrations of
water, unusual separations, and oxygenated by-products are some of
the features of biomass conversion that are distinct from those
encountered in petroleum upgrading. Thus, despite extensive
efforts, there are many challenges that must be overcome to
efficiently produce chemicals or fuels from biomass.
[0006] A variety of biomass-derived polymeric materials such as
lignin, cellulose, and hemicellulose, can be pyrolyzed to produce
mixtures of aromatics, olefins, carbon monoxide (CO), carbon
dioxide (CO.sub.2), water, and other products. A particularly
desirable form of pyrolysis is known as catalytic fast pyrolysis
(CFP) which involves the conversion of biomass in a catalytic fluid
bed reactor to produce a mixture of aromatics, olefins, and a
variety of other materials. The aromatics include benzene, toluene,
xylenes (collectively BTX), and naphthalene, among other aromatics.
The olefins include ethylene, propylene, and lesser amounts of
higher molecular weight olefins.
[0007] The raw effluent from a CFP process is a complex mixture
that comprises aromatics, olefins, oxygenates, paraffins, H.sub.2,
CH.sub.4, CO, CO.sub.2, water, char, ash, coke, catalyst fines, and
a host of other compounds. Manufacture, separation and recovery of
the various components, especially those found to be more valuable,
from this complex mixture is increasingly important.
[0008] In U.S. Patent Publication No. 2014/0107306 A1, a method and
apparatus are described for pyrolysis of biomass and conversion of
at least one pyrolysis product to another chemical compound. The
latter method comprises feeding a hydrocarbonaceous material to a
reactor, pyrolyzing within the reactor at least a portion of the
hydrocarbonaceous material under reaction conditions sufficient to
produce one or more pyrolysis products, catalytically reacting at
least a portion of the pyrolysis products, separating at least a
portion of the hydrocarbon products, and reacting a portion of the
hydrocarbon products to produce a chemical intermediate.
[0009] In U.S. Pat. No. 8,277,643; U.S. Pat. No. 8,864,984; U.S.
Patent Publication No. 2012/0203042 A1; U. S. Patent Publication
No. 2013/0060070 A1, U. S. Patent Publication No. 2014/0027265 A1;
and US Patent Publication No. 2014/0303414 A1, each incorporated
herein by reference in its entirety, apparatus and process
conditions suitable for CFP are described.
[0010] It is a general goal of the technology to provide high
yields of BTX as these are usually the most valuable products.
Under operating conditions currently employed in CFP, more toluene
than either benzene or mixed-xylene products is made. However the
value of toluene can be less than either benzene or xylene, so it
is desirable to increase production of benzene and xylenes from
conversion of biomass in pyrolysis or CFP.
[0011] In conventional aromatics processing, the toluene can be
converted to an equilibrium mixture of benzene and xylenes by
disproportionation in a fixed bed reactor operating at elevated
pressure and in the presence of added hydrogen gas. Such a
disproportionation process is disclosed in U.S. Pat. Nos.
4,052,476; 4,851,604; and 6,958,305; illustrative of a group of
disclosures of such a mechanism. These processes do not convert
biomass in a CFP fluidized bed to produce enhanced amounts of
benzene and xylenes. Further, U.S. Pat. No. 7,563,358 is
illustrative of a group of other disclosures of a mechanism for
producing an aromatic product of benzene, toluene, xylenes from a
hydrocarbon feed comprising: (a) C.sub.6.sup.+ non-aromatic cyclic
hydrocarbons; (b) C.sub.8.sup.+ single-ring aromatic hydrocarbons
having at least one alkyl group containing two or more carton
atoms; and (c) C.sub.9.sup.+ single-ring aromatic hydrocarbons
having at least three methyl groups.
[0012] In light of current commercial practices and the disclosures
of art, a simple economical process for enhancing production of
benzene and xylenes from a catalytic pyrolysis process is needed.
The present invention provides such a process.
SUMMARY OF THE INVENTION
[0013] Various aspects of the present invention include increased
yield of useful and desirable benzene and xylene products in a CFP
process. The present invention provides for this in an economical
improved process. An embodiment of the present process comprises
the steps of: a) feeding biomass, catalyst composition, such as one
comprising a crystalline molecular sieve characterized by a
silica/alumina mole ratio (SAR) greater than 12 and a Constraint
Index from 1 to 12, and transport fluid to a CFP process fluidized
bed reactor maintained at reaction conditions to manufacture a raw
fluid product stream, b) feeding the raw fluid product stream of
step a) to a solids separation and stripping system to produce
separated solids and a fluid product stream, c) feeding the fluid
product stream of step b) to a vapor/liquid separation system to
produce a liquid phase stream comprising components selected from
the group consisting of water, char, coke, ash, catalyst fines and
combinations thereof, and a vapor phase stream comprising benzene,
toluene and xylenes, d) feeding the vapor phase stream of step c)
to a product recovery system to recover benzene, toluene and
xylenes, and e) recycling at least a portion of the recovered
toluene of step d) to the fluidized bed reactor of step a).
[0014] Another embodiment of the present invention comprises such
process wherein the crystalline molecular sieve of the catalyst of
step a) has a structure of ZSM-5, ZSM-1, ZSM-12, ZSM-22, ZSM-23,
ZSM-35, ZSM-38, ZSM-48, ZSM-50 or combinations thereof.
[0015] Another embodiment of the invention process comprises such
process wherein the crystalline molecular sieve of the catalyst of
step a) is characterized by an SAR from greater than 12 to 240 and
a Constraint Index from 5 to 10, such as a crystalline molecular
sieve selected from those having the structure of ZSM-5, ZSM-11,
ZSM-22, ZSM-23 or combinations thereof.
[0016] Another embodiment of the invention process comprises the
steps of: a) feeding biomass, catalyst composition comprising a
crystalline molecular sieve having the structure of ZSM-5, and
transport fluid to a CFP process fluidized bed reactor maintained
at reaction conditions including a temperature from 300 to
1000.degree. C. and pressure from 100 to 1500 kPa to manufacture a
raw fluid product stream, b) feeding the raw fluid product stream
of step a) to a catalyst separation and stripping system to produce
separated catalyst and a fluid product stream, c) feeding the fluid
product stream of step b) to a vapor/liquid separation system to
produce a liquid phase stream comprising components selected from
the group consisting of water, char, coke, ash, catalyst fines and
combinations thereof, and a vapor phase stream comprising benzene,
toluene and xylenes, d) feeding the vapor phase stream of step c)
to a product recovery system to recover benzene, toluene and
xylenes, and e) recycling from about 5 to about 99% of the
recovered toluene of step d) to the fluidized bed reactor of step
a).
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a block flow illustration of an embodiment of the
present process.
DETAILED DESCRIPTION OF THE INVENTION
[0018] As a result of extensive research in view of the above, we
have found that we can economically and effectively conduct a CFP
process to enhance manufacture of valuable benzene and xylenes
product by way of a series of sequential steps.
[0019] The present improved process comprises steps of: a) feeding
biomass, such as, for example, that provided from renewable sources
of organic materials, catalyst composition comprising one or more
of a particular family of crystalline molecular sieves, for
example, those characterized by a SAR greater than 12 and a
Constraint Index from 1 to 12, and transport fluid to a CFP process
fluidized bed reactor maintained at specific reactions conditions,
for example, a temperature from 300 to 1000.degree. C. and pressure
from 100 to 1500 kPa, to manufacture a raw fluid product stream, b)
feeding the raw fluid product stream of step a) to a solids
separation and stripping system, hereinafter more particularly
described, to produce separated solids and a fluid product stream,
c) feeding the fluid product stream of step b) to a vapor/liquid
separation system, hereinafter more particularly described, to
produce a liquid phase stream comprising various components, such
as those selected from the group consisting of water, char, coke,
ash, catalyst fines and combinations thereof, and a vapor phase
stream comprising benzene, toluene, xylenes and other aromatic
compounds, d) feeding the vapor phase stream of step c) to a
product recovery system, hereinafter more particularly described,
to recover benzene, toluene and xylenes, and e) recycling at least
a portion of the recovered toluene of step d) to the fluidized bed
reactor of step a).
[0020] As used herein, the terms "aromatics" or "aromatic compound"
refer to a hydrocarbon compound or compounds comprising one or more
aromatic groups such as, for example, single aromatic ring systems
(e.g., benzyl, phenyl, etc.) and fused polycyclic aromatic ring
systems (e.g., naphthyl, 1,2,3,4-tetrahydronaphthyl, etc.).
Examples of aromatic compounds include, but are not limited to,
benzene, toluene, indane, indene, 2-ethyltoluene, 3-ethyltoluene,
4-ethyltoluene, trimethylbenzene (e.g., 1,3,5-trimethylbenzene,
1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, etc.),
ethylbenzene, styrene, cumene, n-propylbenzene, xylenes (e.g.,
p-xylene, m-xylene, o-xylene), naphthalene, methylnaphthalene
(e.g., 1-methylnaphthalene), anthracene, 9,10-dimethylanthracene,
pyrene, phenanthrene, dimethyl naphthalene (e.g.,
1,5-dimethylnaphthalene, 1,6-dimethylnaphthalene,
2,5-dimethylnaphthalene, etc.), ethyl naphthalene, hydrindene,
methylhydrindene, and dimethylhydrindene. Single ring and/or higher
ring aromatics may also be produced in some embodiments. Aromatics
also include single and multiple ring compounds that contain
heteroatom substituents, i.e., phenol, cresol, benzofuran, aniline,
indole, etc.
[0021] As used herein, the term "biomass" has its conventional
meaning in the art and refers to any organic source of energy or
chemicals that is renewable. Its major components can be: (1) trees
(wood) and all other vegetation; (2) agricultural products and
wastes (corn, fruit, garbage ensilage, etc.); (3) algae and other
marine plants; (4) metabolic wastes (manure, sewage), and (5)
cellulosic urban waste. Examples of biomass materials are
described, for example, in Huber, G. W. et al, "Synthesis of
Transportation Fuels from Biomass: Chemistry, Catalysts, and
Engineering," Chem. Rev. 106, (2006), pp. 4044-4098.
[0022] Biomass is conventionally defined as the living or recently
dead biological material that can be converted for use as fuel or
for industrial production. The criterion as biomass is that the
material should be recently participating in the carbon cycle so
that the release of carbon in the combustion process results in no
net increase averaged over a reasonably short period of time (for
this reason, fossil fuels such as peat, lignite and coal are not
considered biomass by this definition as they contain carbon that
has not participated in the carbon cycle for a long time so that
their combustion results in a net increase in atmospheric carbon
dioxide). Most commonly, biomass refers to plant matter grown for
use as biofuel, but it also includes plant or animal matter used
for production of fibers, chemicals or heat. Biomass may also
include biodegradable wastes or byproducts that can be burned as
fuel or converted to chemicals, including municipal wastes, green
waste (the biodegradable waste comprised of garden or park waste,
such as grass or flower cuttings and hedge trimmings), byproducts
of farming including animal manures, food processing wastes, sewage
sludge, and black liquor from wood pulp or algae. Biomass excludes
organic material which has been transformed by geological processes
into substances such as coal, oil shale or petroleum. Biomass is
widely and typically grown from plants, including miscanthus,
spurge, sunflower, switchgrass, hemp, corn (maize), poplar, willow,
sugarcane, and oil palm (palm oil) with the roots, stems, leaves,
seed husks and fruits all being potentially useful. Processing of
the raw material for introduction to the processing unit may vary
according to the needs of the unit and the form of the biomass.
[0023] As used herein, the terms "olefin" or "olefin compound"
(a.k.a. "alkenes") have their ordinary meaning in the art, and
refer to any unsaturated hydrocarbon containing one or more pairs
of carbon atoms linked by a double bond. Olefins include both
cyclic and acyclic (aliphatic) olefins, in which the double bond is
located between carbon atoms forming part of a cyclic (closed ring)
or of an open chain grouping, respectively. In addition, olefins
may include any suitable number of double bonds (e.g., monoolefins,
diolefins, triolefins, etc.). Examples of olefin compounds include,
but are not limited to, ethene, propene, allene (propadiene),
1-butene, 2-butene, isobutene (2-methylpropene), butadiene, and
isoprene, among others. Examples of cyclic olefins include
cyclopentene, cyclohexene, and cycloheptene, among others. Aromatic
compounds such as toluene are not considered olefins; however,
olefins that include aromatic moieties are considered olefins, for
example, benzyl acrylate or styrene.
[0024] As used herein, the term `oxygenate" includes any organic
compound that contains at least one atom of oxygen in its structure
such as alcohols (e.g., methanol, ethanol, etc.), acids (e.g.,
acetic acid, propionic acid, etc.), aldehydes (e.g., formaldehyde,
acetaldehyde, etc), esters (e.g., methyl acetate, ethyl acetate,
etc.), ethers (e.g., dimethyl ether, diethyl ether, etc.),
aromatics with oxygen containing substituents (e.g., phenol,
cresol, benzoic acid etc.), cyclic ethers, acids, aldehydes, and
esters (e.g. furan, furfural, etc.), and the like.
[0025] As used herein, the terms "pyrolysis" and "pyrolyzing" have
their conventional meaning in the art and refer to the
transformation of a compound, e.g., a solid hydrocarbonaceous
material, into one or more other substances, e.g., volatile organic
compounds, gases and coke, by heat, preferably without the addition
of, or in the absence of, oxygen. Preferably, the volume fraction
of oxygen present in a pyrolysis reaction chamber is 0.5% or less.
Pyrolysis may take place with or without the use of a catalyst.
"Catalytic pyrolysis" refers to pyrolysis performed in the presence
of a catalyst, and may involve steps as described in more detail
below. Catalytic fast pyrolysis (CFP) that involves the conversion
of biomass in a catalytic fluid bed reactor to produce a mixture of
aromatics, olefins, and a variety of other materials is a
particularly beneficial pyrolysis process. Examples of catalytic
pyrolysis processes are outlined, for example, in Huber, G. W. et
al, "Synthesis of Transportation Fuels from Biomass: Chemistry,
Catalysts, and Engineering," Chem. Rev. 106, (2006), pp. 4044-4098,
incorporated herein by reference.
[0026] As used herein, the term "recovery" of a component is the
fraction (or percent) of that component that is present in the
recovered product stream(s) compared to the amount of that
component that is present in the reactor effluent stream. For
example if 10 grams of "A" is present in the reactor effluent and
8.5 grams of "A" is present in the recovered product stream, then
the recovery of "A" is 8.5/10 or 0.85 (85%). All percentages
provided herein are by mass unless otherwise indicated.
[0027] The catalyst composition required in the CFP process
fluidized bed reactor of the present invention comprises a
crystalline molecular sieve characterized by an SAR greater than 12
and a Constraint Index from 1 to 12. Non-limiting examples of these
crystalline molecular sieves are those having the structure of
ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-50 or
combinations thereof. As an embodiment, the catalyst composition
comprises a crystalline molecular sieve characterized by an SAR
from greater than 12 to 240 and a Constraint Index from 5 to 10,
such as, for example, molecular sieves having the structure of
ZSM-5, ZSM-11, ZSM-22, ZSM-23 or combinations thereof.
[0028] The members of the class of molecular sieves useful herein
have an effective pore size of generally from about 5 to about 8
Angstroms, such as to freely sorb normal hexane. In addition, the
molecular sieve structure must provide constrained access to larger
molecules. For example, if the only pore windows in a molecular
sieve structure are formed by 8-membered rings of silicon and
aluminum atoms, then access by molecules of larger cross-section
than normal hexane is excluded and the molecular sieve is not of
the desired type for use herein. Windows of 10-membered rings are
preferred, although, in some instances, excessive puckering of the
rings or pore blockage may render these molecular sieves
ineffective.
[0029] A convenient measure of the extent to which a molecular
sieve provides control to molecules of varying sizes to its
internal structure is the Constraint Index of the crystal.
Crystalline materials which provide a highly restricted access to
and egress from its internal structure have a high value for the
Constraint Index, and materials of this kind usually have pores of
small size, e.g. less than 5 Angstroms. On the other hand,
crystalline materials which provide relatively free access to the
internal crystal structure have a low value for the Constraint
Index, and usually have pores of large size, e.g. greater than 8
Angstroms. A simple determination of the Constraint Index may be
made by passing continuously a mixture of an equal weight of normal
hexane and 3-methylpentane over a small sample, approximately 1
gram or less, of crystalline material at atmospheric pressure
according to the following procedure. The sample of the crystalline
material, in the form of pellets or extrudate, is crushed to a
particle size about that of coarse sand and mounted in a glass
tube. Prior to testing, the crystalline material is treated with a
stream of air at 537.degree. C. for at least 15 minutes. The
crystalline material is then flushed with helium and the
temperature adjusted between 287.degree. C. and 510.degree. C. or
higher to allow an overall conversion of between 10 and 60% when
the mixture of hydrocarbons is passed at 1 liquid hourly space
velocity (i.e., 1 volume of liquid hydrocarbon per volume of
crystalline material per hour) over the crystalline material with a
helium dilution to give a helium to total hydrocarbon mole ratio of
4:1. After 20 minutes on stream, a sample of the effluent is
analyzed, most conveniently by gas chromatography, to determine the
fraction remaining unchanged for each of the two hydrocarbons. The
Constraint Index is the ratio of the log of the n-hexane remaining
divided by the log of the 3-methylpentane remaining. The Constraint
Index approximates the ratio of the cracking rate constants for the
two hydrocarbons. The method by which Constraint Index is
determined is described more fully in U.S. Pat. No. 4,029,716,
incorporated by reference for details of the method.
[0030] Constraint Index (CI) values for some typical materials
are:
TABLE-US-00001 CI Test Temp, .degree. C. ZSM-4 0.5 316 ZSM-5 6-8.3
371-316 ZSM-11 5-8.7 371-316 ZSM-12 2.3 316 ZSM-20 0.5 371 ZSM-22
7.3 427 ZSM-23 9.1 427 ZSM-34 50 371 ZSM-35 4.5 454 ZSM-48 3.5 538
ZSM-50 2.1 427 Mordenite 0.5 316 REY 0.4 316 Dealuminized Y 0.5 510
Beta 0.6-2 316-399
[0031] CI values typically characterize the specified crystalline
material, but are the cumulative result of several variables useful
in the determination and calculation thereof. Thus, for a given
crystal exhibiting a CI value within the range of 1 to 12,
depending on the temperature employed during the test method, with
accompanying conversion between 10 and 60%, the CI may vary within
the indicated range of 1 to 12. Likewise, other variables such as
crystal size or the presence of possibly occluded contaminants and
binders intimately combined with the crystal may affect the CI. It
is understood to those skilled in the art that the CI, as utilized
herein, while affording a highly useful means for characterizing
the molecular sieves of interest is approximate, taking into
consideration the manner of its determination, with the
possibility, in some instances, of compounding variable extremes.
However, in all instances, at a temperature within the
above-specified range, the CI will have a value for any given
molecular sieve useful herein within the approximate range of 1 to
12.
[0032] The molecular sieve for use herein or the catalyst
composition comprising same may be thermally treated at high
temperatures. This thermal treatment is generally performed by
heating at a temperature of at least 370.degree. C. for a least 1
minute and generally not longer than 20 hours (typically in an
oxygen containing atmosphere, preferably air). While subatmospheric
pressure can be employed for the thermal treatment, atmospheric
pressure is desired for reasons of convenience. The thermal
treatment can be performed at a temperature up to 925.degree. C.
The thermally treated product is particularly useful in the present
process.
[0033] For the catalyst composition useful in this invention, the
suitable molecular sieve may be employed in combination with a
support or binder material such as, for example, a porous inorganic
oxide support or a clay binder. Non-limiting examples of such
binder materials include alumina, zirconia, silica, magnesia,
thoria, titania, boria and combinations thereof, generally in the
form of dried inorganic oxide gels and gelatinous precipitates.
Suitable clay materials include, by way of example, bentonite,
kieselguhr and combinations thereof. The relative proportion of
suitable crystalline molecular sieve of the total catalyst
composition may vary widely with the molecular sieve content
ranging from 30 to 90 percent by weight and more usually in the
range of 40 to 70 percent by weight of the composition. The
catalyst composition may be in the form of an extrudate, beads or
fluidizable microspheres.
[0034] The molecular sieve for use herein or the catalyst
composition comprising it may have original cations replaced, in
accordance with techniques well known in the art, at least in part,
by ion exchange with hydrogen or hydrogen precursor cations and/or
non-noble metal ions of Group VIII of the Periodic Table, i.e.
nickel, iron and/or cobalt.
[0035] Examples of apparatus and process conditions suitable for
the CFP process are described in U.S. Pat. Nos. 8,277,643 and
8,864,984, and U. S. Patent Publication Nos. 2012/0203042 A1,
2014/0027265 A1, 2014/0303414 A1 and 2013/0060070A1, each
incorporated herein by reference. Conditions for CFP of biomass may
include one or a combination of the following features (which are
not intended to limit the broader aspects of the invention): a
catalyst composition; that catalyst composition comprising a metal
selected from the group consisting of titanium, vanadium, chromium,
manganese, iron, cobalt, nickel, copper, zinc, gallium, platinum,
palladium, silver, phosphorus, sodium, potassium, magnesium,
calcium, tungsten, zirconium, cerium, lanthanum, and combinations
thereof; a fluidized bed, circulating bed, moving bed, or riser
reactor; an operating temperature in the range of 300 to
1000.degree. C.; and a solid catalyst/biomass mass ratio of from
0.1 to 40.
[0036] Referring more particularly to FIG. 1, which shows a block
flow illustration of an embodiment of the present process. Biomass
feedstock is prepared by chipping, drying, grinding, washing or
other processes, or some combination of these in biomass
preparation system 100, and fed to CFP fluid bed reactor 110 via
line 1. Catalyst composition comprising a crystalline molecular
sieve characterized by an SAR greater than 12 and a CI from 1 to
12, e.g. having the structure of ZSM-5, and transport fluid, e.g.
recycle gas, are introduced to the CFP reactor 110 via lines 7 and
2, respectively. The CFP reactor is fluidized by the recycle gas or
other fluid. The raw fluid product stream from the CFP reactor 110
is provided to solids separation and stripping system 130 via line
4. Spent solid material from reactor 110 is passed to a catalyst
regeneration system 120 via line 6 where it is regenerated by
removing coke and char and generating steam, and the regenerated
catalyst is returned to reactor 110 via line 7. Excess steam from
the catalyst regeneration system 120 may be sent to other processes
or uses via line 8. A portion of the separated solids from solids
separation and stripping system 130 may be passed back to reactor
110 via line 5, and fluid product from system 130 is passed to
quench and vapor/liquid separation system 140 via line 9. In
vapor/liquid separation system 140 are produced a liquid phase
stream comprising components selected from the group consisting of
water, char, coke, ash, catalyst fines and combinations thereof,
and a vapor phase stream comprising benzene, toluene, xylenes and
other aromatics. Water is removed from vapor/liquid separation
system 140 via line 15, vapor phase stream comprising benzene,
toluene and xylenes is removed via line 10, and the remainder of
components is removed via line 16. A portion of the line 16
components may be passed to recycle compressor 160, and then to CFP
reactor 110 via line 2 as recycle gas for fluidization purposes. A
portion, such as, for example, from 5 to 25%, of the compressed
recycle gas in line 2 may be passed via line 18 to biomass
preparation system 100. From line 16 a portion of the stream may be
taken as a purge of, for example, from 5 to 50%, via line 17 in
order to prevent the buildup of inert materials in the system. The
stream of line 10 is passed to product recovery system 150 for
recovery of benzene, toluene, xylenes and other aromatics. From
product recovery system 150 is obtained benzene via line 11,
xylenes via line 12, toluene via line 14, and other aromatics via
line 13. At least a portion, such as from 5 to 99%, for example
from 10 to 95%, such as from 30 to 50%, of the contents of line 14
is passed to CFP reactor 110 via line 3 as recycle. Recycle stream
3 can be fed to reactor 110 as a separate stream, or it can be
combined with the fluidization fluid stream 2 (not shown), or it
can be combined with the biomass stream 1 (not shown), or it can be
combined with stream 7 (not shown), or it can be combined with a
fresh catalyst stream (not shown), or any combination of these.
[0037] The CFP reactor 110 may be operated at a temperature from
300 to 1000.degree. C., and the raw fluid product stream from
reactor 110 is typically at a temperature of 300 to 620.degree. C.,
such as 400 to 575.degree. C., for example 500 to 550.degree. C.,
and a pressure of 100 kPa to 1500 kPa, such as 200 kPa to 1000 kPa,
for example 300 kPa to 700 kPa (pressures expressed as absolute
pressures). The raw fluid product stream from reactor 110 comprises
aromatics, olefins, oxygenates, paraffins, H.sub.2, CH.sub.4, CO,
CO.sub.2, water, char, ash, coke, catalyst fines, and a host of
other components. On a water-free and solids-free basis the raw
fluid product stream can comprise 20 to 60%, such as 25 to 55%, for
example 30 to 50% CO; 10 to 50%, such as 15 to 40%, for example 20
to 35% CO.sub.2; 0.1 to 10%, such as 0.2 to 5%, for example 0.3 to
1.0% H.sub.2; 2 to 15%, such as 3 to 10%, for example 4 to 8%
CH.sub.4; 2 to 40%, such as 3 to 35%, for example 4 to 30%, BTX;
0.1 to 10%, such as 0.2 to 5%, for example 0.3 to 3% oxygenates;
and 1 to 15%, such as 2 to 10%, for example 3 to 6% C.sub.2-C.sub.4
olefins. On a water-free and solids-free basis the raw fluid
product stream can comprise a vapor mixture where the sum of CO and
CO.sub.2 is 30 to 90%, such as 40 to 85%, for example 50 to
80%.
[0038] Quenching with, for example, water in the vapor/liquid
separation system 140 may be conducted at conditions of temperature
from -5 to 200.degree. C., such as from 10 to 100.degree. C., for
example from 40 to 80.degree. C., and pressure of 150 to 1500 kPa,
for example from 300 to 700 kPa. The product resulting from such a
quenching step may then be compressed at conditions of 100 to 8000
kPa, for example 600 to 2000 kPa, and then cooled at conditions of
-30 to 60.degree. C., for example 5 to 30.degree. C.
[0039] The solids separation and stripping system (e.g. 130 of FIG.
1) of step b) of the present process may include unit operations
known to effectively separate entrained catalyst and certain other
components from the raw fluid product stream of the CFP process.
That raw fluid product stream may comprise entrained catalyst,
catalyst fines, char, coke, ash, water, C.sub.9.sup.+ aromatics,
oxygenates, benzene, toluene, xylenes, CO, CO.sub.2, CH.sub.4,
N.sub.2, H.sub.2, C.sub.2-C.sub.4 olefins and paraffins, and other
compounds. Embodiments of such unit operations include one or more
cyclones (such as, for example, in series), screens, filters, or
some combination of these.
[0040] The vapor/liquid separation system (e.g. 140 of FIG. 1) of
step c) of the present process may include unit operations known to
effectively accomplish separation of the fluid product stream of
step b) into a liquid phase stream comprising components selected
from the group consisting of water, char, coke, ash, catalyst fines
and combinations thereof, and a vapor phase stream comprising
benzene, toluene and xylenes. Embodiments of such unit operations
include venturi, quench systems, condensers, chillers, absorption
systems, scrubbers, demisters, or combinations of these.
[0041] The product recovery system (e.g. 150 of FIG. 1) of step d)
of the present process may include unit operations known to
effectively accomplish separation and recovery of benzene, toluene,
xylenes and other aromatic compounds from the vapor phase of step
c). Embodiments of such unit operations include condensers,
chillers, absorption systems, demisters, or combinations of
these.
[0042] The following Example demonstrates the present invention and
its capability for use. The invention is capable of other and
different embodiments, and its several details are capable of
modifications in various apparent respects, without departing from
the spirit and scope of the invention. Accordingly, the Example is
to be regarded as illustrative in nature and not as restrictive.
All percentages are by mass unless otherwise indicated.
Example
[0043] A calculation approach was used to develop a conservative
estimate of toluene conversion in a CFP process fluidized bed with
the understanding that the CFP BTX product may not be at
equilibrium. A representative BTX composition of a CFP process was
mathematically converted to the chemical equilibrium composition
using standard equilibrium calculation methods at 525.degree. C.
Then to this composition, additional toluene was added and chemical
equilibrium for the new system was calculated. In the newly
equilibrated system the incremental toluene was converted to
additional benzene and mixed xylenes. These calculations were done
at two toluene additions representing 30% recycle and 50% recycle
of the baseline toluene amounts. At 30% recycle, the corresponding
toluene conversion was 14% of the added toluene; at 50% recycle the
conversion was 22% of the added toluene. The molar selectivity in
both cases was 50/50 benzene/xylenes.
[0044] Results are shown below in Table 1 (mass balance for 30%
recycle) and Table 2 (mass balance for 50% recycle). The results
demonstrate that there are no chemical equilibrium constraints to
the present invention process to increase the yield of more
valuable benzene and xylenes products. The values shown in the
tables are kg/hour. In the tables, A=compound; B=reaction product
without toluene recycle; C=equilibrated product without toluene
recycle; D=toluene recycle; E=combined feed; F=equilibrated
reaction product with toluene recycle; G=incremental production;
and H=percent toluene conversion.
TABLE-US-00002 TABLE 1 A B C D E F G H Benzene 137 155 155 182 27
Toluene 386 345 115 460 397 14 o-Xylene 44 74 74 84 10 m-Xylene 120
146 146 164 18 p-Xylene 92 59 59 67 8 Total 779 779 894 894 63
TABLE-US-00003 TABLE 2 A B C D E F G H Benzene 137 155 155 208 53
Toluene 386 345 230 575 448 22 o-Xylene 44 74 74 94 20 m-Xylene 120
146 146 184 38 p-Xylene 92 59 59 75 16 Total 779 779 1009 1009
127
[0045] The results of this example show that a CFP process may be
conducted to enhance benzene and xylenes production by way of the
present process. It is a benefit of the present invention process
that an existing CFP reactor and catalyst system in a fluid bed can
be used in this manner. This avoids the need for a separate fixed
bed disproportionation reactor system to increase production of
benzene and xylenes. Another advantage of the present invention is
that it allows manufacturing flexibility for the CFP process to
respond to changes in product demand. For example, if xylene demand
is high, more toluene can be recycled to the CFP reactor to produce
more xylene. When toluene demand is high, the amount of recycle can
be reduced or recycle can be stopped completely.
[0046] All patents, patent applications, test procedures, priority
documents, articles, publications, manuals, and other documents
cited herein are fully incorporated by reference to the extent such
disclosure is not inconsistent with this invention and for all
jurisdictions in which such incorporation is permitted.
[0047] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated.
[0048] While the illustrative embodiments of the invention have
been described with particularity, it will be understood that
various other modifications will be apparent to and may be readily
made by those skilled in the art without departing from the spirit
and scope of the invention. Accordingly, it is not intended that
the scope of the claims hereof be limited to the examples and
descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present invention, including all features which
would be treated as equivalents thereof by those skilled in the art
to which the invention pertains.
* * * * *