U.S. patent application number 12/970643 was filed with the patent office on 2011-04-21 for catalytic structures including catalyst materials in porous zeolite materials, and methods of forming same.
This patent application is currently assigned to BATTELLE ENERGY ALLIANCE, LLC. Invention is credited to Daniel M. Ginosar, Lucia Petkovic, Harry W. Rollins.
Application Number | 20110092356 12/970643 |
Document ID | / |
Family ID | 39082831 |
Filed Date | 2011-04-21 |
United States Patent
Application |
20110092356 |
Kind Code |
A1 |
Rollins; Harry W. ; et
al. |
April 21, 2011 |
CATALYTIC STRUCTURES INCLUDING CATALYST MATERIALS IN POROUS ZEOLITE
MATERIALS, AND METHODS OF FORMING SAME
Abstract
Catalytic structures include a catalytic material disposed
within a zeolite material. The catalytic material may be capable of
catalyzing a formation of methanol from carbon monoxide and/or
carbon dioxide, and the zeolite material may be capable of
catalyzing a formation of hydrocarbon molecules from methanol. The
catalytic material may include copper and zinc oxide. The zeolite
material may include a first plurality of pores substantially
defined by a crystal structure of the zeolite material and a second
plurality of pores dispersed throughout the zeolite material.
Systems for synthesizing hydrocarbon molecules also include
catalytic structures. Methods for synthesizing hydrocarbon
molecules include contacting hydrogen and at least one of carbon
monoxide and carbon dioxide with such catalytic structures.
Catalytic structures are fabricated by forming a zeolite material
at least partially around a template structure, removing the
template structure, and introducing a catalytic material into the
zeolite material.
Inventors: |
Rollins; Harry W.; (Idaho
Falls, ID) ; Petkovic; Lucia; (Idaho Falls, ID)
; Ginosar; Daniel M.; (Idaho Falls, ID) |
Assignee: |
BATTELLE ENERGY ALLIANCE,
LLC
Idaho Falls
ID
|
Family ID: |
39082831 |
Appl. No.: |
12/970643 |
Filed: |
December 16, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11464566 |
Aug 15, 2006 |
7879749 |
|
|
12970643 |
|
|
|
|
Current U.S.
Class: |
502/74 ; 502/60;
502/77; 502/78; 502/79; 977/902 |
Current CPC
Class: |
C07C 2529/46 20130101;
B01J 29/035 20130101; C10G 3/49 20130101; C07C 1/20 20130101; C07C
2529/85 20130101; C10G 3/50 20130101; C10G 2400/22 20130101; C10G
2400/20 20130101; B01J 29/40 20130101; B01J 29/005 20130101; B01J
29/072 20130101; B01J 29/80 20130101; B01J 37/0018 20130101; C10G
3/47 20130101; B01J 29/041 20130101; C07C 2529/84 20130101; C07C
1/20 20130101; C10G 3/45 20130101; B01J 29/061 20130101; B01J 29/46
20130101; C07C 11/02 20130101; Y02P 30/40 20151101 |
Class at
Publication: |
502/74 ; 502/60;
502/79; 502/78; 502/77; 977/902 |
International
Class: |
B01J 29/04 20060101
B01J029/04; B01J 29/08 20060101 B01J029/08; B01J 29/18 20060101
B01J029/18; B01J 29/70 20060101 B01J029/70; B01J 29/83 20060101
B01J029/83; B01J 29/85 20060101 B01J029/85; B01J 29/40 20060101
B01J029/40; B01J 37/02 20060101 B01J037/02 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] This invention was made with government support under
Contract No. DE-AC07-05ID14517 awarded by the United States
Department of Energy. The government has certain rights in the
invention.
Claims
1. A catalytic structure comprising: a substantially crystalline
zeolite material; a first plurality of pores substantially defined
by a crystal structure of the substantially crystalline zeolite
material; a second plurality of pores dispersed throughout the
substantially crystalline zeolite material; a metallic material
disposed within at least one pore of at least one of the first
plurality of pores and the second plurality of pores; and a metal
oxide material disposed within at least one pore of at least one of
the first plurality of pores and the second plurality of pores.
2. The catalytic structure of claim 1, wherein the metallic
material comprises a plurality of metallic particles.
3. The catalytic structure of claim 2, wherein the plurality of
metallic particles has an average particle size of less than about
500 angstroms.
4. The catalytic structure of claim 1, wherein the metallic
material comprises at least one of copper, magnesium, zinc, cobalt,
iron, nickel, ruthenium, platinum, palladium, or cesium.
5. The catalytic structure of claim 1, wherein the metal oxide
material comprises a plurality of metal oxide particles.
6. The catalytic structure of claim 5, wherein the plurality of
metal oxide particles has an average particle size of less than
about 500 angstroms.
7. The catalytic structure of claim 1, wherein the metal oxide
material comprises at least one of zinc oxide, magnesium oxide,
zirconium oxide, iron oxide, and tungsten oxide.
8. The catalytic structure of claim 1, wherein the metal material
comprises copper and the metal oxide material comprises zinc
oxide.
9. The catalytic structure of claim 1, wherein the second plurality
of pores comprises a plurality of elongated channels.
10. The catalytic structure of claim 9, wherein each elongated
channel of the plurality of elongated channels is generally
cylindrical and has an average diameter in a range extending from
about 20 angstroms to about 500 angstroms.
11. The catalytic structure of claim 9, wherein the second
plurality of pores further comprises a plurality of generally
spherical pores.
12. The catalytic structure of claim 1, wherein the zeolite
material has a framework type selected from MFI, BEA, FAU, MOR,
FER, ERI, OFF, CHA and AEI.
13. The catalytic structure of claim 12, wherein the zeolite
material comprises an aluminosilicate-based material, an
aluminophosphate-based material, or a silicoaluminophosphate-based
material.
14. The catalytic structure of claim 13, wherein the zeolite
material comprises ZSM-5.
15. The catalytic structure of claim 1, wherein the first plurality
of pores comprises a plurality of micropores and the second
plurality of pores comprises a plurality of mesopores.
16. A catalytic structure comprising: a zeolite material capable of
catalyzing a formation of hydrocarbon molecules having two or more
carbon atoms from methanol, the zeolite material comprising: a
first plurality of pores substantially defined by a crystal
structure of the zeolite material; and a second plurality of pores
dispersed throughout the zeolite material; at least one catalytic
material disposed within at least one pore of at least one of the
first plurality of pores and the second plurality of pores, the at
least one catalytic material capable of catalyzing the formation of
methanol from at least one of carbon monoxide and carbon dioxide in
the presence of hydrogen.
17. The catalytic structure of claim 16, wherein the at least one
catalytic material comprises a plurality of metallic particles.
18. The catalytic structure of claim 17, wherein the plurality of
metallic particles has an average particle size of less than about
500 angstroms.
19. The catalytic structure of claim 17, wherein each metallic
particle of the plurality of metallic particles comprises at least
one of copper, magnesium, zinc, cobalt, iron, nickel, ruthenium,
platinum, palladium, or cesium.
20. The catalytic structure of claim 17, wherein the at least one
catalytic material further comprises a plurality of metal oxide
particles.
21. The catalytic structure of claim 20, wherein the plurality of
metal oxide particles has an average particle size of less than
about 500 angstroms.
22. The catalytic structure of claim 20, wherein each metal oxide
particle of the plurality of metal oxides comprises at least one of
zinc oxide, magnesium oxide, zirconium oxide, iron oxide, and
tungsten oxide.
23. The catalytic structure of claim 16, wherein the at least one
catalytic material comprises copper and zinc oxide.
24. The catalytic structure of claim 16, wherein the second
plurality of pores comprises a plurality of elongated channels.
25. The catalytic structure of claim 24, wherein each elongated
channel of the plurality of elongated channels is generally
cylindrical and has an average diameter in a range extending from
about 20 angstroms to about 500 angstroms.
26. The catalytic structure of claim 24, wherein the second
plurality of pores further comprises a plurality of generally
spherical pores.
27. The catalytic structure of claim 16, wherein the zeolite
material has a framework type selected from MFI, BEA, FAU, MOR,
FER, ERI, OFF, CHA and AEI.
28. The catalytic structure of claim 27, wherein the zeolite
material comprises an aluminosilicate-based material, an
aluminophosphate-based material, or a silicoaluminophosphate-based
material.
29. The catalytic structure of claim 28, wherein the zeolite
material comprises ZSM-5.
30. The catalytic structure of claim 16, wherein the first
plurality of pores comprises a plurality of micropores and the
second plurality of pores comprises a plurality of mesopores.
31. A method of fabricating a catalytic structure, the method
comprising: forming a zeolite material at least partially around at
least one template structure, the zeolite material capable of
catalyzing the formation of hydrocarbon molecules having two or
more carbon atoms from methanol; removing the at least one template
structure from within the zeolite material; introducing at least
one catalytic material into the zeolite material, the at least one
catalytic material capable of catalyzing the formation of methanol
from at least one of carbon monoxide and carbon dioxide in the
presence of hydrogen.
32. The method of claim 31, wherein introducing at least one
catalytic material into the zeolite material comprises introducing
a plurality of metallic particles into the zeolite material.
33. The method of claim 32, wherein introducing a plurality of
metallic particles into the zeolite material comprises introducing
a plurality of metallic particles having an average particle size
of less than about 500 angstroms into the zeolite material.
34. The method of claim 32, further comprising selecting each
metallic particle of the plurality of metallic particles to
comprise at least one of copper, magnesium, zinc, cobalt, iron,
nickel, ruthenium, platinum, palladium, or cesium.
35. The method of claim 32, wherein introducing at least one
catalytic material into the zeolite material further comprises
introducing a plurality of metal oxide particles into the zeolite
material.
36. The method of claim 35, wherein introducing a plurality of
metal oxide particles into the zeolite material comprises
introducing a plurality of metal oxide particles having an average
particle size of less than about 200 angstroms into the zeolite
material.
37. The method of claim 35, further comprising selecting each metal
oxide particle of the plurality of metal oxide particles to
comprise at least one of zinc oxide, magnesium oxide, zirconium
oxide, iron oxide, and tungsten oxide.
38. The method of claim 31, wherein introducing at least one
catalytic material into the zeolite material comprises introducing
copper and zinc oxide into the zeolite material.
39. The method of claim 38, wherein introducing copper into the
zeolite material and introducing zinc oxide into the zeolite
material each comprise introducing a nitrate solution into the
zeolite material and heating the zeolite material in air to
temperatures of greater than about 100.degree. C.
40. The method of claim 31, wherein forming a zeolite material at
least partially around at least one template structure comprises
forming a zeolite material around a plurality of elongated template
structures, and wherein removing the at least one template
structure from within the zeolite material comprises fanning a
plurality of elongated channels in the zeolite material.
41. The method of claim 40, wherein forming a plurality of
elongated channels comprises forming a plurality of generally
cylindrical channels having an average diameter in a range
extending from about 20 angstroms to about 500 angstroms in the
zeolite material.
42. The method of claim 40, wherein forming a zeolite material at
least partially around at least one template structure further
comprises forming a zeolite material around a plurality of
generally spherical template structures, and wherein removing the
at least one template structure from within the zeolite material
comprises forming a plurality of generally spherical pores in the
zeolite material.
43. The method of claim 31, wherein forming a zeolite material
comprises forming a zeolite material having a framework type
selected from MFI, BEA, FAU, MOR, FER, ERI, OFF, CHA and AEI.
44. The method of claim 43, wherein forming a zeolite material
comprises forming an aluminosilicate-based material, an
aluminophosphate-based material, or a silicoaluminophosphate-based
material.
45. The method of claim 44, wherein forming a zeolite material
comprises forming ZSM-5.
46. The method of claim 31, wherein forming a zeolite material at
least partially around at least one template structure comprises
forming a zeolite material at least partially around at least one
template structure comprising at least one of a plurality of carbon
nanoparticles and a plurality of carbon nanowires.
47. The method of claim 31, wherein forming a zeolite material at
least partially around at least one template structure comprises
forming a zeolite material at least partially around each of a
plurality of carbon nanotubes.
48. The method of claim 47, wherein introducing a first catalytic
material comprises impregnating at least one carbon nanotube of the
plurality of carbon nanotubes with a solution comprising at least
one element of at least one of the first catalytic material and the
second catalytic material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/464,566, filed Aug. 15, 2006, pending, the entire
disclosure of which is hereby incorporated herein by this
reference. This application is related to the subject matter of a
co-pending divisional of the above referenced parent application,
as filed on event date herewith entitled "Systems Including
Catalysts In Porous Zeolite Materials Within A Reactor For Use In
Synthesizing Hydrocarbons" (Attorney Docket No. 2939-7840.2US), and
is also related to the subject matter of U.S. patent application
Ser. No. 11/688,930, filed Mar. 21, 2007, now U.S. Pat. No.
7,592,291, issued Sep. 22, 2009, which application is a
continuation-in-part of U.S. patent application Ser. No. 11/464,566
referenced above.
FIELD OF THE INVENTION
[0003] The present invention relates to catalytic materials,
structures, systems, and methods. More particularly, the present
invention relates to catalytic structures including zeolite
materials, and to systems and methods for synthesizing hydrocarbon
molecules from hydrogen and at least one of carbon monoxide and
carbon dioxide using such catalytic structures. The present
invention also relates to methods of fabricating catalytic
structures that include zeolite materials.
BACKGROUND OF THE INVENTION
[0004] Carbon dioxide gas (CO.sub.2) may be converted into liquid
fuels such as, for example, hydrocarbon molecules of between about
5 and about 12 carbon atoms per molecule (e.g., gasoline) through
multi-step reactions. For example, carbon dioxide (CO.sub.2) gas
and hydrogen (H.sub.2) may be converted to carbon monoxide (CO) gas
and water (H.sub.2O) through the Reverse Water-Gas Shift Reaction,
which is shown by Reaction [1] below.
CO.sub.2+H.sub.2.fwdarw.CO+H.sub.2O [1]
[0005] Synthesis gas, which is a mixture of carbon monoxide gas
(CO) and hydrogen gas (H.sub.2) then may be produced from the
reaction products of the Reverse Water-Gas Shift Reaction by adding
additional hydrogen gas (H.sub.2) to the reaction products. This
synthesis gas may be further reacted through either Fischer-Tropsch
(FT) processes, or through methanol synthesis (MS) plus
methanol-to-gasoline (MTG) processes, to provide liquid fuels.
[0006] Briefly, Fischer-Tropsch processes include various catalyzed
chemical reactions in which synthesis gas is converted into liquid
hydrocarbons in a reactor in the presence of a catalyst and at
temperatures between about 200.degree. C. and about 350.degree. C.
Catalysts used in Fischer-Tropsch processes include, for example,
iron, cobalt, nickel, and ruthenium. While various interrelated
reactions may occur in Fischer-Tropsch processes, the overall
reaction process may be generally represented by Reaction [2]
below.
(2n+1)H.sub.2+nCO.fwdarw.C.sub.nH.sub.2n+2+nH.sub.2O [2]
[0007] As mentioned above, synthesis gas may also be reacted by
first performing a methanol synthesis (MS) process, and then
performing a methanol-to-gasoline (MTG) process to produce liquid
fuels. Methanol synthesis (MS) processes involve the catalytic
conversion of carbon monoxide, carbon dioxide, hydrogen, and water
to methanol and other reaction byproducts. The methanol synthesis
reactions may be generally represented by Reactions [3], [4], and
[5] below.
CO+2H.sub.2CH.sub.3OH [3]
CO.sub.2+3H.sub.2CH.sub.3OH+H.sub.2O [4]
CO+H.sub.2O.fwdarw.CO.sub.2+H.sub.2 [5]
[0008] The methanol-to-gas (MTG) process involves the conversion of
methanol to hydrocarbon molecules using zeolite catalysts, which
are described in further detail below. The methanol-to-gas (MTG)
process occurs in two steps. First, methanol is heated to about
300.degree. C. and partially dehydrated over an alumina catalyst at
about 2.7 megapascals to yield an equilibrium mixture of methanol,
dimethyl ether, and water. This effluent is then mixed with
synthesis gas and introduced into a reactor containing a zeolite
catalyst (such as, for example, a ZSM-5 zeolite), at temperatures
between about 350.degree. C. and about 366.degree. C. and at
pressures between about 1.9 megapascals and about 2.3 megapascals,
to produce hydrocarbons and water. The methanol-to-gas (MTG)
reactions may be generally represented by Reactions [6], [7], and
[8] below.
2CH.sub.3OH.fwdarw.CH.sub.3OCH.sub.3+H.sub.2O [6]
CH.sub.3OCH.sub.3.fwdarw.C.sub.2-C.sub.5Olefins [7]
C.sub.2-C.sub.5Olefins.fwdarw.Paraffins,Cycloparaffins,Aromatics
[8]
[0009] While the feasibility of the above-described reactions has
been demonstrated, mass production of liquid fuels using such
processes has not been widely implemented due, at least in part, to
the relatively high costs associated with carrying out the
reactions, and to the relatively low yields exhibited by the
reactions.
[0010] In an effort to improve the yield of the various reactions
and to minimize the costs associated with carrying out the
reactions, research has been conducted in an effort to improve the
efficiency of the catalysts associated with each of the respective
catalyzed reactions. As previously mentioned, zeolites have been
used as catalysts in the methanol-to-gas (MTG) process.
[0011] Zeolites are substantially crystalline oxide materials in
which the crystal structure of the oxide material defines pores,
channels, or both pores and channels in the oxide material. Such
pores and channels may have cross-sectional dimensions of between
about 1 angstrom and about 200 angstroms, and typically have
cross-sectional dimensions of between about 3 angstroms and about
15 angstroms. Typically, zeolite materials include metal atoms
(classically, silicon or aluminum) that are surrounded by four
oxygen anions to form an approximate tetrahedron consisting of a
metal cation at the center of the tetrahedron and oxygen anions at
the four apexes of the tetrahedron. The tetrahedral metals are
often referred to as "T-atoms." These tetrahedra then stack in
substantially regular arrays to form channels. There are various
ways in which the tetrahedra may be stacked, and the resulting
"frameworks" have been documented and categorized in, for example,
Ch. Baerlocher, W. M. Meier and D. H. Olson, Atlas of Zeolite
Framework Types, 5th ed., Elsevier: Amsterdam, 2001, the contents
of which are hereby incorporated herein in their entirety by this
reference.
[0012] Silicon-based tetrahedra in zeolitic materials are
electrically neutral since silicon typically exhibits a 4+
oxidation state. Tetrahedra based on elements other than silicon,
however, may not be electrically neutral, and charge-compensating
ions may be present so as to electrically neutralize the
non-neutral tetrahedra. For example, many zeolites are
aluminosilicates. Aluminum typically exists in the 3+ oxidation
state, and charge-compensating cations typically populate the pores
to maintain electrical neutrality. These charge-compensating
cations may participate in ion-exchange processes. When the
charge-compensating cations are protons, the zeolite may be a
relatively strong solid acid. The acidic properties of such solid
acid zeolites may contribute to their catalytic properties. Other
types of reactive metal cations may also populate the pores to form
catalytic materials with unique properties.
[0013] Notwithstanding the research that has been conducted with
respect to the above-described reactions and their respective
catalytic materials, there remains a need in the art for catalytic
materials and structures than can be used to provide a direct route
or mechanism for the reduction of carbon monoxide (CO) and/or
carbon dioxide (CO.sub.2) to liquid fuels.
BRIEF SUMMARY OF THE INVENTION
[0014] In one example embodiment, the present invention includes a
catalytic structure that includes a substantially crystalline
zeolite material having a first plurality of pores and a second
plurality of pores. The pores of the first plurality are
substantially defined by interstitial spaces within the crystal
structure of the substantially crystalline zeolite material. The
pores of the second plurality are dispersed throughout the
substantially crystalline zeolite material. A metallic material may
be disposed within at least one pore of at least one of the first
plurality of pores and the second plurality of pores. A metal oxide
material also may be disposed within at least one pore of at least
one of the first plurality of pores and the second plurality of
pores.
[0015] In another example embodiment, the present invention
includes a catalytic structure that includes a zeolite material
that is capable of catalyzing the formation of hydrocarbon
molecules having two or more carbon atoms from methanol, and at
least one catalytic material that is capable of catalyzing the
formation of methanol from at least one of carbon monoxide and
carbon dioxide in the presence of hydrogen disposed within the
zeolite material. The zeolite material includes a first plurality
of pores substantially defined by interstitial spaces within the
crystal structure of the zeolite material, and a second plurality
of pores dispersed throughout the zeolite material. The catalytic
material may be disposed within at least one pore of at least one
of the first plurality of pores and the second plurality of
pores.
[0016] In an additional example embodiment, the present invention
includes methods of fabricating catalytic structures. A zeolite
material capable of catalyzing the formation of hydrocarbon
molecules from methanol may be formed at least partially around at
least one template structure. The template structure may be removed
from within the zeolite material, and at least one catalytic
material capable of catalyzing the formation of methanol from at
least one of carbon monoxide and carbon dioxide in the presence of
hydrogen is introduced into the zeolite material.
[0017] In yet a further example embodiment, the present invention
includes methods of synthesizing hydrocarbon molecules having two
or more carbon atoms in which hydrogen and at least one of carbon
monoxide and carbon dioxide are contacted with a catalytic
structure. The catalytic structure includes a zeolite material that
is capable of catalyzing the formation of hydrocarbon molecules
having two or more carbon atoms from methanol, and at least one
catalytic material that is capable of catalyzing the formation of
methanol from at least one of carbon monoxide and carbon dioxide in
the presence of hydrogen disposed within the zeolite material. The
zeolite material includes a first plurality of pores substantially
defined by interstitial spaces within the crystal structure of the
zeolite material, and a second plurality of pores dispersed
throughout the zeolite material. The catalytic material may be
disposed within at least one pore of at least one of the first
plurality of pores and the second plurality of pores.
[0018] In still another example embodiment, the present invention
includes systems for synthesizing hydrocarbon molecules from
hydrogen and at least one of carbon monoxide and carbon dioxide.
The systems include a catalytic structure disposed within a
reactor. The catalytic structure includes a zeolite material that
is capable of catalyzing the formation of hydrocarbon molecules
having two or more carbon atoms from methanol, and at least one
catalytic material that is capable of catalyzing the formation of
methanol from at least one of carbon monoxide and carbon dioxide in
the presence of hydrogen disposed within the zeolite material. The
zeolite material includes a first plurality of pores substantially
defined by interstitial spaces within the crystal structure of the
zeolite material, and a second plurality of pores dispersed
throughout the zeolite material. The catalytic material may be
disposed within at least one pore of at least one of the first
plurality of pores and the second plurality of pores.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] While the specification concludes with claims particularly
pointing out and distinctly claiming that which is regarded as the
present invention, the advantages of this invention may be more
readily ascertained from the following description of the invention
when read in conjunction with the accompanying drawings in
which:
[0020] FIG. 1 is a cross-sectional view of one example of a
catalytic structure that embodies teachings of the present
invention and includes a metal material and a metal oxide material
that are disposed within pores of a zeolite material;
[0021] FIG. 2 is a simplified illustration representing one example
of a chemical structure framework that may be exhibited by the
zeolite material shown in FIG. 1;
[0022] FIG. 3 is an enlarged cross-sectional view of a pore
extending through the zeolite material shown in FIG. 1 and
illustrating catalytic material within the pore;
[0023] FIGS. 4 through 7 illustrate one example of a method that
may be used to fabricate a catalytic structure according to
teachings of the present invention;
[0024] FIG. 8 is a partial cross-sectional view of a reactor that
includes a catalytic structure that embodies teachings of the
present invention;
[0025] FIG. 9 is a partial cross-sectional view of a reactor that
includes another catalytic structure that embodies teachings of the
present invention; and
[0026] FIG. 10 is a schematic diagram of a system that embodies
teachings of the present invention and includes a catalytic
structure for catalyzing the formation of hydrocarbon molecules
from hydrogen and at least one of carbon monoxide and carbon
dioxide.
DETAILED DESCRIPTION OF THE INVENTION
[0027] As used herein, the term "zeolite material" means and
includes any substantially crystalline material generally
represented by the formula:
M.sub.xM'.sub.y . . . N.sub.z[T.sub.mT'.sub.n . . . O.sub.2(m+n+ .
. . )-.epsilon.(OH).sub.2.epsilon.](OH).sub.br(Aq).sub.p.qQ
wherein M and M' represent exchangeable and/or non-exchangeable
metal cations, N represents non-metallic cations (which may be
removable upon heating), T and T' represent T atoms (which may be
selected from, for example, beryllium, boron, aluminum, silicon,
phosphorous, gallium, and germanium), O represents oxygen atoms, OH
represents hydroxide ions, Aq represents chemically bonded water
(or any other strongly held ligands of the T-atoms (e.g., T and
T'), and Q represents sorbate molecules, which may be, but are not
limited to, water molecules. In the above formula, x, y, z, m, n,
.epsilon., br, p, and q each may be any number greater than or
equal to zero. In other words, if one of the components is not
present in the material, then the corresponding subscript would be
zero. The portion of the formula contained within the brackets
provides the framework of the substantially crystalline material.
The crystal structure of zeolite materials typically includes a
plurality of interconnected tetrahedra and has a framework density
(FD) of between about 12 and about 23, wherein the framework
density is defined as the number of tetrahedrally coordinated atoms
(T-atoms) per 1,000 cubic angstroms. By way of example and not
limitation, zeolite materials include aluminosilicate based
materials, aluminophosphate-based materials, and
silicoaluminophosphate-based materials. An example of a zeolite
material is an aluminosilicate-based material having a chemical
structure in which the unit cell (smallest geometrically repeating
unit of the crystal structure) is generally represented by the
formula:
M.sub.(y/n)[(AlO.sub.2).sub.y(SiO.sub.2).sub.z].(x)H.sub.2O,
wherein M is a cation selected from elements in Group IA and Group
IIA of the Periodic Table of the Elements (including, for example,
sodium, potassium, magnesium and calcium), n is the valence of the
cations M, x is the number of water molecules per unit cell, y is
the number of AlO.sub.2 units per unit cell, and z is the number of
SiO.sub.2 units per unit cell. In some zeolite materials, the ratio
of z to y (z/y) may be any number greater than 1. Another example
of a zeolite material is a silicoaluminophosphate-based material
having a chemical structure in which the unit cell is generally
represented by the formula:
(Si.sub.aAl.sub.bP.sub.c)O.sub.2.(x)H.sub.2O,
wherein x is the number of water molecules per unit cell, z is the
number of silicon atoms per unit cell, b is the number of aluminum
atoms per unit cell, and c is the number of phosphorous atoms per
unit cell. Such silicoaluminophosphate-based materials may also
include a small amount of organic amine or quaternary ammonium
templates, which are used to form the materials and retained
therein. Such zeolite materials may further include additional
elements and materials disposed within the interstitial spaces of
the unit cell.
[0028] As used herein, the term "pore" means and includes any void
in a material and includes voids of any size and shape. For
example, pores include generally spherical voids, generally
rectangular voids, as well as elongated voids or channels having
any cross-sectional shape including nonlinear or irregular
shapes.
[0029] As used herein, the term "micropore" means and includes any
void in a material having an average cross-sectional dimension of
less than about 20 angstroms (2 nanometers). For example,
micropores include generally spherical pores having average
diameter diameters of less than about 20 angstroms, as well as
elongated channels having average cross-sectional dimensions of
less than about 20 angstroms.
[0030] As used herein, the term "mesopore" means and includes any
void in a material having an average cross-sectional dimension of
greater than about 20 angstroms (2 nanometers) and less than about
500 angstroms (50 nanometers). For example, mesopores include
generally spherical pores having average diameters between about 20
angstroms and about 500 angstroms, as well as elongated channels
having average cross-sectional dimensions between about 20
angstroms and about 500 angstroms.
[0031] As used herein, the term "macropore" means and includes any
void in a material having an average cross-sectional dimension of
greater than about 500 angstroms (50 nanometers). For example,
macropores include generally spherical pores having average
diameters greater than about 500 angstroms, as well as elongated
channels having average cross-sectional dimensions greater than
about 500 angstroms.
[0032] The illustrations presented herein are not meant to be
actual views of any particular catalytic structure, reactor, or
system, but are merely idealized representations, which are
employed to describe the present invention. Additionally, elements
common between figures may retain the same numerical
designation.
[0033] One example of a catalytic structure 10 that embodies
teachings of the present invention is shown in FIG. 1. The
catalytic structure 10 includes a zeolite material 12 that is
capable of catalyzing the formation of hydrocarbon molecules having
two or more hydrocarbons from methanol. As discussed in further
detail below, the zeolite material 12 may have both a mesoporous
structure and a macroporous structure.
[0034] Referring to FIG. 1, the catalytic structure 10 may include
a plurality of mesopores 14 dispersed throughout the zeolite
material 12. The mesopores 14 may include elongated channels
extending randomly through the zeolite material 12. By way of
example and not limitation, some of the mesopores 14 may include an
elongated pore having a generally cylindrical shape and an average
cross-sectional diameter in a range extending from about 20
angstroms (2 nanometers) to about 500 angstroms (50 nanometers).
Other mesopores 14 may be generally spherical and may have an
average diameter in a range extending from about 20 angstroms (2
nanometers) to about 500 angstroms (50 nanometers). In additional
embodiments, the mesopores 14 may be disposed in an ordered array
within the zeolite material 12. For example, the mesopores 14 may
include elongated channels extending generally parallel to one
another through the zeolite material 12. In some embodiments,
communication may be established between at least some of the
mesopores 14. In additional embodiments, each mesopore 14 may be
substantially isolated from other mesopores 14 by the zeolite
material 12. Furthermore, the zeolite material 12 may include a
plurality of macropores in addition to, or in place of, the
plurality of mesopores 14.
[0035] In one embodiment of the present invention, the zeolite
material 12 may have an MFI framework type as defined in Ch.
Baerlocher, W. M. Meier and D. H. Olson, Atlas of Zeolite Framework
Types, 5th ed., Elsevier: Amsterdam, 2001. Furthermore, the zeolite
material 12 may include an aluminosilicate-based material. By way
of example and not limitation, the zeolite material 12 may include
ZSM-5 zeolite material, which is an aluminosilicate-based zeolite
material having an MFI framework type. Furthermore, the zeolite
material 12 may be acidic. For example, at least some metal cations
of the zeolite material 12 may be replaced with hydrogen ions to
provide a desired level of acidity to the zeolite material 12. Ion
exchange reactions for replacing metal cations in a zeolite
material with hydrogen ions are known in the art.
[0036] FIG. 2 is an enlarged view of a portion of the zeolite
material 12 shown in FIG. 1 and provides a simplified
representation of the chemical structure framework of a zeolite
material 12 having an MFI framework type, as viewed in the [010]
direction. As shown therein, the zeolite material 12 may include a
plurality of micropores 18 that extend through the zeolite material
12 and are substantially defined by the interstitial spaces within
the crystal structure of the zeolite material 12. The micropores
18, shown in FIG. 2, may be substantially straight. The zeolite
material 12 may further include additional micropores (not shown in
FIG. 2) that extend through the zeolite material 12 in the [100]
direction in a generally sinusoidal pattern.
[0037] Various types of zeolite materials 12 are known in the art,
and any zeolite material 12 that exhibits catalytic activity with
respect to the formation of hydrocarbon molecules from methanol, as
discussed in further detail below, may be used in catalytic
structures that embody teachings of the present invention, such as
the catalytic structure 10 shown in FIG. 1. For example, the
zeolite material 12 may include a silicoaluminophosphate-based
material. Furthermore, the zeolite material 12 may have framework
types other than MFI. By way of example and not limitation, the
zeolite material 12 may have a BEA, FAU, MOR, FER, ERI, OFF, CHA or
an AEI framework type. By way of example and not limitation, the
zeolite material 12 may include SAPO-34 (CHA) or ALPO.sub.4-18
(AEI).
[0038] Referring to FIG. 3, the catalytic structure 10 further
includes an additional catalytic material disposed on and/or in the
zeolite material 12. The additional catalytic material may be
capable of catalyzing the formation of methanol from one or both of
carbon monoxide (CO) and carbon dioxide (CO.sub.2) in the presence
of hydrogen. For example, the catalytic structure 10 may include a
first catalytic material 20 and a second catalytic material 22
disposed on interior and/or exterior surfaces of the zeolite
material 12. As shown in FIG. 3, the first catalytic material 20
and the second catalytic material 22 may be disposed within
mesopores 14 of the zeolite material 12. It is contemplated that
the first catalytic material 20, the second catalytic material 22,
or both the first catalytic material 20 and the second catalytic
material 22 also may be disposed within micropores 18 (FIG. 2) of
the zeolite material 12.
[0039] In some embodiments, the first catalytic material 20 may
form a coating extending over surfaces of the zeolite material 12
within the mesopores 14. In additional embodiments, the first
catalytic material 20 may be configured as a plurality of
nanoparticles disposed within the mesopores 14 of the zeolite
material 12. Such nanoparticles may have an average diameter of,
for example, less than about 500 angstroms (50 nanometers), and,
more particularly, less than about 200 angstroms (20 nanometers).
Similarly, the second catalytic material 22 may form a coating
extending over surfaces of the zeolite material 12 within the
mesopores 14. In additional embodiments, the second catalytic
material 22 may be configured as a plurality of nanoparticles
disposed within mesopores 14 of the zeolite material 12. Such
nanoparticles may have an average diameter of, for example, less
than about 500 angstroms (50 nanometers), and, more particularly,
less than about 200 angstroms (20 nanometers).
[0040] In yet additional embodiments, the first catalytic material
20 and the second catalytic material 22 each may comprise regions
of a single layer or coating extending over surfaces of the zeolite
material 12 within the mesopores 14.
[0041] In some embodiments of the present invention, one or both of
the first catalytic material 20 and the second catalytic material
22 may be chemically bound to the zeolite material 12 by, for
example, a chemical complex or a chemical bond. In additional
embodiments, the first catalytic material 20 and the second
catalytic material 22 may be physically bound to the zeolite
material 12 by mechanical interference between surfaces of the
zeolite material 12 and conformal layers of one or both of the
first catalytic material 20 and the second catalytic material 22
formed over such surfaces of the zeolite material 12. In yet other
embodiments, there may be substantially no chemical or physical
bond between the zeolite material 12 and one or both of the first
catalytic material 20 and the second catalytic material 22. For
example, nanoparticles of one or both of the first catalytic
material 20 and the second catalytic material 22 may be generally
loosely disposed within the mesopores 14 of the zeolite material
12.
[0042] As previously mentioned, the first catalytic material 20 and
the second catalytic material 22 may be capable of catalyzing the
formation of methanol from at least one of carbon monoxide and
carbon dioxide in the presence of hydrogen. By way of example and
not limitation, the first catalytic material 20 may include a
metallic material such as, for example, copper, magnesium, zinc,
cobalt, iron, nickel, ruthenium, platinum, palladium, or cesium
(including alloys based on one or more of such metallic materials).
By way of example and not limitation, the second catalytic material
22 may include a metal oxide material such as, for example, zinc
oxide, magnesium oxide, zirconium oxide, iron oxide, or tungsten
oxide.
[0043] One example of a method that may be used to form catalytic
structures that embody teachings of the present invention, such as,
for example, the catalytic structure 10 shown in FIGS. 1 through 3,
will now be described with reference to FIGS. 4 through 7.
[0044] Referring to FIG. 4, a plurality of template structures 30
may be provided within a container 32. The template structures 30
may have a selected size and shape corresponding to a desired size
and shape of pores, such as, for example, the mesopores 14 (FIG.
1), to be formed in the catalytic structure 10. By way of example
and not limitation, the template structures 30 may comprise
nanoparticles, nanowires, or nanotubes. The template structures 30
may be formed from or include any material that may be subsequently
removed from a zeolite material 12 formed around the template
structures 30 without significantly damaging or otherwise affecting
the zeolite material 12. By way of example and not limitation, the
template structures 30 may include carbon. In the embodiment shown
in FIG. 4, the template structures 30 include carbon nanowires.
Each carbon nanowire may be generally cylindrical and may have an
average cross-sectional diameter between about 10 angstroms (1
nanometer) and about 2,000 angstroms (200 nanometers).
[0045] In additional embodiments, the template structures 30 may
include carbon nanoparticles, carbon nanotubes, or a mixture of at
least two of carbon nanowires, nanoparticles, and nanotubes.
Furthermore, the template structures 30 optionally may be formed
from or include materials other than carbon such as, for example,
any polymer material allowing the formation of a zeolite material
12 around the template structures 30 and subsequent removal of the
polymer material from the zeolite material 12 without significantly
damaging or otherwise affecting the zeolite material 12.
[0046] Referring to FIG. 5, a zeolite material 12 may be formed
around the template structures 30 using methods known in the art,
such as, for example, those methods described in U.S. Pat. No.
3,702,886 to Argauer et al., the entire disclosure of which is
incorporated herein in its entirety by this reference.
[0047] After forming the zeolite material 12 around the template
structures 30, the template structures 30 may be removed from
within the zeolite material 12 to form mesopores 14 (and optionally
macropores), as shown in FIG. 6. If the template structures 30
comprise carbon material, the carbon material may be removed by,
for example, calcining in air. By way of example and not
limitation, the zeolite material 12 and the template structures 30
may be heated in air to temperatures of about 600.degree. C. for
about 20 hours to calcine the carbon material.
[0048] After removing the template structures 30 from within the
zeolite material 12 to form the mesopores 14 (and optionally
macropores), the first catalytic material 20 and the second
catalytic material 22 may be provided on and/or in the zeolite
material 12.
[0049] By way of example and not limitation, particles of the first
catalytic material 20 and particles of the second catalytic
material 22 (or precursor materials from which the first catalytic
material 20 and the second catalytic material 22 can be
subsequently formed) may be suspended in a liquid. The liquid and
the particles of the first catalytic material 20 and the second
catalytic material 22 may be provided within the mesopores 14 of
the zeolite material 12 by, for example, immersing the zeolite
material 12 in the liquid suspension. The zeolite material 12 then
may be removed from the liquid suspension and allowed to dry (at
ambient or elevated temperatures) to remove the liquid from the
liquid suspension, leaving behind the particles of the first
catalytic material 20 and the second catalytic material 22 within
the mesopores 14 of the zeolite material 12.
[0050] As another example, the first catalytic material 20 and the
second catalytic material 22 may be provided on and/or in the
zeolite material 12 by precipitation of their respective metal
salts (i.e., nitrates or acetates). The precursor salts may be
provided in the mesopores 14 of the zeolite material 12 using, for
example, the incipient wetness technique. The precursor salts then
may be precipitated using standard reagents such as, for example,
ammonia or sodium hydroxide. As previously discussed herein, in one
embodiment of the present invention, the first catalytic material
20 may include copper and the second catalytic material 22 may
include zinc oxide. One method by which copper and zinc oxide may
be provided within mesopores 14 of the zeolite material 12 is to
immerse the zeolite material 12 in a nitrate solution comprising
copper nitrate (Cu(NO.sub.3).sub.2) and zinc nitrate
(Zn(NO.sub.3).sub.2). In additional embodiments, the zeolite
material 12 may be first immersed in one of a copper nitrate
solution and a zinc nitrate solution, and subsequently immersed in
the other of the copper nitrate solution and the zinc nitrate
solution. Furthermore, the zeolite material 12 may be dried after
immersion in the first nitrate solution and prior to immersion in
the second nitrate solution.
[0051] The copper nitrate and zinc nitrate on and within the
zeolite material 12 then may converted to copper oxide (CuO) and
zinc oxide (ZnO) by, for example, heating the zeolite material 12
in air to temperatures between about 100.degree. C. and about
250.degree. C. The copper oxide (CuO) then may be converted to
copper (Cu) by, for example, flowing hydrogen gas (H.sub.2) over
the zeolite material 12 at elevated temperatures (for example,
about 240.degree. C.).
[0052] As yet another example, the first catalytic material 20 and
the second catalytic material 22 may be provided on and/or in the
zeolite material 12 by preparing a first aqueous solution of zinc
nitrate and copper nitrate and adding the zeolite material 12 to
the aqueous solution. An additional solution may be prepared that
includes hexamethylenetetramine and sodium citrate. This additional
solution may be added to the first aqueous solution, and the
mixture may be heated in a closed vessel, such as, for example, a
Parr acid digestion bomb, to between about 95.degree. C. and about
120.degree. C. for between about one hour and about four hours. The
sample then may be filtered, washed, and dried. The sample then may
be oxidized in air at temperatures between about 100.degree. C. and
about 250.degree. C. to form the copper oxide and zinc oxide, after
which the copper oxide may be converted to copper as described
above.
[0053] In an additional method that embodies teachings of the
present invention, the template structures 30 shown in FIG. 4 may
include carbon nanotubes. The carbon nanotubes may be impregnated
with a solution comprising copper nitrate and zinc nitrate. After
forming the zeolite material 12 around the impregnated carbon
nanotubes, the carbon nanotubes may be removed by calcining in air,
as previously described, and copper and zinc oxide may be formed
from the copper nitrate and the zinc nitrate, respectively, as the
carbon nanotubes are calcined in the air.
[0054] Referring to FIG. 7, the above described method may be used
to provide the first catalytic material 20, which may include
copper (Cu), and the second catalytic material 22, which may
include zinc oxide (ZnO), within mesopores 14 of the zeolite
material 12 (and optionally within micropores 18 (FIG. 2) and/or
macropores of the zeolite material 12) and to form the catalytic
structure 10.
[0055] Referring to FIG. 8, in some embodiments of the present
invention, the catalytic structure 10 may include a quantity of
powder 48 comprising relatively fine particles. The particles of
the powder 48 may include first and second catalytic materials 20,
22 disposed within a zeolite material 12, as previously described
in relation to FIGS. 1 through 3. The powder 48 may be provided
within a container 40 having an inlet 42 and an outlet 44, and the
powder 48 may be disposed between the inlet 42 and the outlet 44.
In this configuration, a gas comprising hydrogen and at least one
of carbon monoxide (CO) and carbon dioxide (CO.sub.2) may be
introduced into the container 40 through the inlet 42. As the gas
contacts the powder 48, the powder 48 may catalyze the formation of
hydrocarbon molecules having two or more carbon atoms from the
carbon monoxide (CO) and carbon dioxide (CO.sub.2). In particular,
the first catalytic material 20 and the second catalytic material
22 (FIG. 3) may catalyze the formation of methanol from the carbon
monoxide (CO) and carbon dioxide (CO.sub.2), and the zeolite
material 12 may catalyze the formation of hydrocarbon molecules
having two or more carbon atoms from the methanol. The hydrocarbon
molecules may be collected from the outlet 44 of the container 40
and purified and/or concentrated as necessary or desired.
[0056] Referring to FIG. 9, in additional embodiments of the
present invention, the catalytic structure 10 may include a
plurality of particles, briquettes, or pellets 50, each of which
includes first and second catalytic materials 20, 22 disposed
within a zeolite material 12, as previously described in relation
to FIGS. 1 through 3. By way of example and not limitation, the
pellets 50 may be formed by pressing the powder 48, previously
described in relation to FIG. 8, in a die or mold to form the
pellets 50. The plurality of pellets 50 may be provided within a
container 40, as shown in FIG. 9. In this configuration, a gas
comprising at least one of carbon monoxide (CO) and carbon dioxide
(CO.sub.2) may be introduced into the container 40 through the
inlet 42, and the pellets 50 may catalyze the formation of
hydrocarbon molecules having two or more carbon atoms from hydrogen
and the carbon monoxide (CO) and/or carbon dioxide (CO.sub.2), as
previously described in relation to FIG. 8.
[0057] FIG. 10 is a simplified schematic of a system 60 that
embodies teachings of the present invention and that may be used to
form hydrocarbon molecules having two or more carbon atoms from
carbon monoxide (CO) and/or carbon dioxide (CO.sub.2) in the
presence of hydrogen using a catalytic structure that embodies
teachings of the present invention, such as, for example, the
catalytic structure 10 previously described in relation to FIGS. 1
through 3. By way of example and not limitation, the system 60 may
include a reactor 41, a gas-liquid separator 64, and a compressor
66. As previously discussed, the reactor 41 may include a catalytic
structure that embodies teachings of the present invention, such
as, for example, the catalytic structure 10. The system 60 may
further include a first heat exchanger 68A for heating a reactant
mixture fed to the reactor 41, and a second heat exchanger 68B for
cooling products (and any unreacted reactants and/or reaction
byproducts) as they exit the reactor 41.
[0058] The system 60 may further include a heating device (not
shown) for heating the reactor 41 and the catalytic structure 10 to
elevated temperatures. For example, a heating device may be
configured to heat the reactor 41 and the catalytic structure 10 to
a temperature between about 200.degree. C. and about 500.degree. C.
Furthermore, the reactor 41 may be pressurized to between about 0.5
megapascals (5 atmospheres) and about 10 megapascals (100
atmospheres).
[0059] As shown in FIG. 10, a reactant mixture 70 that includes
hydrogen gas and at least one of carbon monoxide (CO) and carbon
dioxide (CO.sub.2) may be passed through the first heat exchanger
68A and fed to the reactor 41. As previously discussed, the
catalytic structure 10 may catalyze the formation of hydrocarbon
molecules having two or more carbon atoms from the hydrogen and
carbon monoxide (CO) and/or carbon dioxide (CO.sub.2). A product
mixture 72 (which may include such hydrocarbon molecules), together
with any unreacted reactant gasses 74 and reaction byproducts, may
be collected from the reactor 41 and passed through the second heat
exchanger 68B to the gas-liquid separator 64. The gas liquid
separator 64 may be used to separate liquid hydrocarbon products of
the product mixture 72 from the unreacted reactant gases 74. The
unreacted reactant gasses 74 may be re-pressurized as necessary
using the compressor 66 and recombined with the reactant mixture 70
through a three-way valve 78, as shown in FIG. 10.
[0060] The liquid hydrocarbon products in the product mixture 72
collected from the gas-liquid separator 64 may then be further
processed as necessary or desired. For example, additional
distillation equipment (not shown) may be used to purify and
concentrate the various hydrocarbon components in the product
mixture 72, as necessary or desired.
[0061] The catalytic structures, systems, and methods described
herein may be used to catalyze the conversion of hydrogen and at
least one of carbon monoxide and carbon dioxide to hydrocarbons
having two or more carbon atoms with improved catalytic activity
and selectivity relative to known catalytic structures, systems,
and methods. Furthermore, the catalytic structures, systems, and
methods described herein may facilitate economic utilization of
carbon dioxide from stationary carbon dioxide sources, such as
coal-powered and hydrocarbon-powered electricity generation plants,
which otherwise may be vented to atmosphere. Furthermore, the
methods described herein may be used to fabricate various catalytic
structures, other than those described herein, that include a
bi-modal (microporous and mesoporous) or multi-modal (microporous,
mesoporous, and macroporous) zeolite material and a metal and/or
metal oxide catalyst material disposed on and/or in the zeolite
material. Such catalytic structures may be bi-functional. In other
words, the zeolite material itself may function as one catalytic
material, while the catalytic material disposed on and/or in the
zeolite material may function as a second catalytic material. In
addition to the synthesis of hydrocarbon molecules from hydrogen
and carbon monoxide and/or carbon dioxide, such bi-functional
catalytic structures may be useful in many additional applications
where it is necessary or desirable to provide different catalytic
functions to a single catalytic structure or material.
[0062] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *