U.S. patent application number 11/703993 was filed with the patent office on 2007-08-30 for catalytic burner for combustion of liquid fuels.
This patent application is currently assigned to The Board of Regents, The University of Texas System. Invention is credited to Kenneth J. JR. Balkus, Thomas J. Pisklak.
Application Number | 20070202450 11/703993 |
Document ID | / |
Family ID | 38444419 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070202450 |
Kind Code |
A1 |
Pisklak; Thomas J. ; et
al. |
August 30, 2007 |
Catalytic burner for combustion of liquid fuels
Abstract
Flameless catalytic burner systems made of zeolites that have a
higher working temperature and greater flow rate than existing
flameless catalytic burners have been developed. The burner systems
comprise wicks that are capable of wicking low vapor pressure
fuels.
Inventors: |
Pisklak; Thomas J.; (Dallas,
TX) ; Balkus; Kenneth J. JR.; (The Colony,
TX) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
The Board of Regents, The
University of Texas System
|
Family ID: |
38444419 |
Appl. No.: |
11/703993 |
Filed: |
February 8, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60771618 |
Feb 8, 2006 |
|
|
|
60771918 |
Feb 8, 2006 |
|
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Current U.S.
Class: |
431/320 |
Current CPC
Class: |
F23D 3/24 20130101; F23D
3/02 20130101; F23D 2900/03081 20130101 |
Class at
Publication: |
431/320 |
International
Class: |
F23D 3/24 20060101
F23D003/24 |
Claims
1. A catalytic burner system comprising: a burner comprising at
least one molecular sieve, wherein said burner comprises an upper
portion and a lower portion; a catalyst, wherein said catalyst is
dispersed within the upper portion of the burner; a wick, wherein
said wick comprises an upper portion and a lower portion, the upper
portion of the wick being connected to the lower portion of the
burner; and, a reservoir, wherein said reservoir houses a liquid
fuel that is contacted by the lower portion of the wick.
2. The burner system of claim 1, wherein the wick is removably
connected to the burner.
3. The burner system of claim 1, wherein the wick is permanently
connected to the burner.
4. The burner system of claim 1, wherein the concentration of the
dispersed catalyst decreases in a gradient from the surface to the
interior of the burner.
5. The burner system of claim 1, wherein said catalyst is a Group
VIII metal.
6. The burner system of claim 1, wherein the catalyst is a metal
selected from the group consisting of gold, manganese, cerium,
cobalt, copper, lanthanum, platinum, palladium and rhodium.
7. The burner system of claim 1, wherein said burner comprises a
binder that forms a rigid structure when heated.
8. The burner system of claim 7, wherein the binder is selected
from the group consisting of bentonite, hectorite, laponite,
montmorillonite, ball clay, kaolin, palygorskite (attapulgite),
barasym SSM-100(synthetic mica-montmorillonite), ripidolite,
rectorite, optigel SH (synthetic hectorite), illite, nontronite,
illite-smectite, sepiolite, beidellite, cookeite, or generally any
type of clay, borosilicate glass, aluminosilicate glass and glass
fibers.
9. The burner system of claim 1, wherein said burner comprises a
thermal conductor that facilitates the transfer of heat through the
burner.
10. The burner system of claim 9, wherein the thermal conductor is
selected from the group consisting of boron nitride, steel,
stainless steel, transition metals, carbon nanofibers, carbon
nanotubes and diamond.
11. The burner system of claim 1, wherein said burner comprises a
combustion additive that enhances the combustion of the liquid
fuel.
12. The burner system of claim 1, wherein said molecule sieve is a
zeolite.
13. The burner system of claim 12, wherein said zeolite has a Si/Al
ratio of greater than 60.
14. The burner system of claim 1, wherein said wick is made of a
porous material.
15. The burner system of claim 14, wherein said porous material is
a zeolite.
16. The burner system of claim 1, wherein said wick is a woven
cloth wick.
17. A method for combusting a liquid fuel comprising, providing a
burner comprising at least one molecular sieve, wherein said burner
has a first, upper portion and a second, lower portion; providing a
wick that is connected to the lower portion of the burner;
providing a catalyst that is dispersed within the upper portion of
the burner; providing a reservoir that contain liquid fuel;
contacting the wick with the liquid fuel; transmitting the fuel
from the reservoir to the burner through the wick; and, igniting
the catalyst with an ignition source.
18. The method of claim 17, wherein the catalyst is dispersed in a
concentration gradient that decreases from the surface of the
burner to the interior of the burner.
19. The method of claim 17, wherein said catalyst is a Group VIII
metal.
20. The method of claim 17, wherein the catalyst is a metal
selected from the group consisting of gold, manganese, cerium,
cobalt, copper, lanthanum, platinum, palladium and rhodium.
21. The method of claim 17, wherein the burner comprises a binder
that forms a rigid structure when heated.
22. The method of claim 17, wherein said burner comprises a thermal
conductor that facilitates the transfer of heat through the
burner.
23. The method of claim 17, wherein said burner comprises a
combustion additive that enhances the combustion of the liquid
fuel.
24. The method of claim 17, wherein said molecule sieve is a
zeolite.
25. The method of claim 24, wherein said zeolite has a Si/Al ratio
of greater than 60.
26. The method of claim 17, wherein said wick is made of a porous
material.
27. The method of claim 26, wherein said porous material is a
zeolite.
28. The method of claim 17, wherein said wick is a woven cloth
wick.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/771,618, filed Feb. 8, 2006 and U.S. Provisional
Application No. 60/771,918, filed Feb. 8, 2006.
BACKGROUND OF THE INVENTION
[0002] Currently, there are several flameless catalytic burners and
lamps available on the market. Certain of these prior art devices
are employed for the delivery of fragrance to a room or other area.
The chemical delivery system (for the delivery of chemicals such as
fragrances) employed in the prior art devices is based on the
flameless combustion of a carrier solvent/fragrance mixture to
deliver fragrance to the surrounding atmosphere. The system is
composed of a reservoir for containing the solvent/fragrance
mixture, and a wick that is attached to a macroporous flameless
catalytic burner, to provide flow from the reservoir to the burner.
Prior art flameless catalytic burners are typically 2.0 cm in
length having an upper portion that is typically 1.7 cm in
diameter, and a lower portion that is typically 1.1 cm in diameter.
The upper portion contains the catalyst and performs the
combustion, while the smaller, lower portion connects to a wick,
typically made of cloth. The cloth wick transports the fuel from
the reservoir to the catalytic burner.
[0003] The solvent/fragrance mixture is approximately 90 wt %
2-propanol, 2 wt % essential oils (fragrance), and 8 wt % water.
This mixture is transported through the cloth wick to the catalytic
burner, where the 2-propanol is catalytically combusted, the heat
of which vaporizes the fragrance. Vaporization of the fragrance
increases the rate at which it is dispersed into the surrounding
atmosphere. The 2-propanol-based fuel is typically combusted by a
commercial platinum catalyst at approximately 215.degree. C. The
prior art catalytic burners are composed of macroporous ceramic
support materials that are formed from nonporous materials, such as
cristobalite, and are capable of absorbing the solvent/fragrance
mixture. There are several disadvantages associated with the prior
art catalytic burners. Firstly, they achieve only partial
combustion of the 2-propanol fuel such that acetone and the
volatile organic compound (VOC) 2-propanol are released into the
atmosphere as pollutants. Partial combustion also results in coke
build-up that reduces catalyst efficiency and eventually
deactivates the catalyst. Secondly, the catalyst layer is located
only on the outer surface of the burner, and does not penetrate
into the interior regions of the burner. This arrangement requires
the fuel to travel farther up into the burner before combustion can
take place. Another drawback to the prior art burners is that
because of their low porosity or lack of porosity, they cannot
absorb low vapor pressure (LVP) fuels at a rate sufficient to
sustain catalytic burning of the fuels. LVP fuels are generally
more desirable because they generate fewer VOC pollutants than
traditional fuels.
[0004] In light of the disadvantages discussed above, there is
therefore a need for a flameless catalytic burner system that can
overcome the problems prevalent in presently available devices.
SUMMARY OF THE INVENTION
[0005] The invention is directed to a catalytic burner system
comprising a burner constructed of at least one molecule sieve,
where the burner comprises an upper portion and a lower portion; a
catalyst, wherein said catalyst is dispersed within the upper
portion of the burner; a wick, wherein said wick comprises an upper
portion and a lower portion, the upper portion of the wick being
connected to the lower portion of the burner; and, a reservoir,
wherein said reservoir houses a liquid fuel that is contacted by
the lower portion of the wick.
[0006] The invention is also directed to a method for combusting a
liquid fuel comprising, a burner constructed of at least one
molecular sieve, wherein said burner has a first, upper portion and
a second, lower portion; providing a wick that is connected to the
lower portion of the burner; providing a catalyst that is dispersed
within the upper portion of the burner; providing a reservoir that
contain liquid fuel; contacting the wick with the liquid fuel; and,
transmitting the fuel from the reservoir to the burner through the
wick.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 is a longitudinal cross-section of a first catalytic
burner system of the invention;
[0008] FIG. 2 is a longitudinal cross-section of a second catalytic
burner system of the invention; and,
[0009] FIG. 3 is a longitudinal cross-section of a catalytic burner
of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0010] An embodiment of the invention provides a flameless
catalytic burner capable of absorbing fuels at a rate sufficient to
maintain autocatalytic combustion.
[0011] An embodiment of the invention provides a burner that is
constructed of highly porous crystalline materials, such as
zeolites, which provides a flow rate of fuels that is sufficient to
allow the catalyst to function, but low enough to prevent the fuel
from extinguishing the catalyst. An optimal or preferred fuel
travel rate in a zeolite-based burner is 0.6 ml/min.
[0012] In an embodiment of the invention, a molecular sieve-based
burner is composed of a shaped structure comprising an upper
portion that contains a catalyst. The lower portion of the burner
does not contain catalyst, and is shaped with a shoulder that
facilitates placement of the burner in a reservoir. The upper
portion of the burner can be of any shape having linear edges
including, pyramidal, octagonal, or hexagonal. This lower portion
of the burner sits on top of a reservoir having a neck, which in
turn permits the shoulder of the burner to contact the neck of the
reservoir. The lower portion of the burner is connected to an upper
portion of a wick. The lower portion of the wick contacts fuel
located in the reservoir. The wick transports the fuel from the
reservoir to the catalyst.
[0013] In certain embodiments of the invention, the wick is
constructed from a porous material. In an embodiment of the
invention, the wick is made of zeolites. In another embodiment of
the invention, the wick is made of cloth, for e.g., woven cloth
wick or a woven cotton wick. In certain embodiments of the
invention, the wick is constructed from porous materials other than
zeolites, such as porous ceramic materials.
[0014] The wick of the present invention is a solid structure
which, unlike wicks used in prior art burner systems, does not
contain a concentric hole along its longitudinal centerline.
[0015] In certain embodiments of the invention, the fuel is a
liquid fuel. The preferred liquid fuel for use is a LVP fuel that
generates lower amounts of VOCs than traditional fuels.
[0016] An embodiment of the invention provides a zeolite-based
flameless catalytic burner that can reach a higher working
temperature than currently available burners. This feature reduces
the emission of VOCs from the burner, which in turn reduces
coking.
[0017] A specific industrial application for a catalytic burner is
its use in a flameless lamp. However, one of ordinary skill in the
art would readily recognize that the catalytic burner described
herein has numerous industrial applications including, portable
stoves, radiant heater, dispersant systems for various as
fragrances, insecticides, aromatherapy compounds, fungicides and
herbicides; heat producing components in portable heat pumps,
micro-chemical reactor system, heat source in portable warmers, and
any application in which a portable heater is required.
[0018] An embodiment of the invention relates to a catalytic burner
made of a porous molecular sieve material on which a metal catalyst
is supported. The porous structure absorbs fuel, which is
catalytically combusted by catalyst that is supported on the
burner.
[0019] As depicted in FIG. 1, a catalytic burner system 10
comprising a burner 11 and wick 12 is shown. The burner 11
comprises an upper portion 11a, and a lower portion 11b. The lower
portion of the burner 11b comprises a shoulder 11c. The burner 11
further comprises a vertical portion 11d that extends below the
shoulder 11c. The lower portion of the burner tapers inward such
that the diameter of the lower portion of the burner is smaller
than the diameter of the upper portion of the burner. The diameter
of the upper portion of the catalytic burner shown in FIG. 1 ranges
from 1.0 to 2.0 cm, and the length of the burner ranges from 1.0 to
2 cm. A close-up view of the burner is illustrated in FIG. 3.
[0020] The upper portion of the burner 11a comprises catalyst 17
that is distributed throughout the structure of the upper portion
of the burner. The distribution of the catalyst is more
concentrated on the peripheral portion of the burner 17a, than in
the inner portion of the burner 17b. Thus a concentration gradient
ranging from high to low is established from the peripheral portion
of the burner to the inner portion of the burner.
[0021] The wick 12 is connected to the burner 11 by insertion into
a space 16 located within the lower portion of the burner. The wick
12 may be removably or permanently connected to the burner 11,
depending on the type of wick used. The length of the wick 12
depicted in FIG. 1 is approximately 12 cm. The wick does not
contain any catalyst, and is typically shaped like a cylinder and
is smaller in diameter (0.5 to 1.5 cm) than the upper portion and
has a length between 2.0 to 12.0 cm. In an embodiment of the
invention, the wick ranges in length from 10 to 12 cm. The wick
extends into the fuel reservoir and contacts the fuel present in
the reservoir. The fuel is absorbed by the wick, and travels up the
length of the wick to the burner. In the case of a porous wick, the
fuel enters the pores of the wick and travels through the pores
from the reservoir through the burner structure, and comes in
contact with the catalyst.
[0022] The embodiment of the invention depicted in FIG. 2 is a
catalytic burner system 20 having a burner 11 and a porous,
non-cloth wick 22. The wick 22 can be either removably or
permanently connected to the burner 11. All aspects of the
catalytic burner system 20 show in FIG. 2 are similar to the system
show in FIG. 1, except for the difference in the type of wick used
in the two systems.
[0023] The upper portion of the burner 11 containing the catalyst
is contacted with a ignition source for igniting the catalyst such
as lighter, match or any heat source that will cause the fuel to
combust, in order to burn the fuel that travels up the wick from
the reservoir to the upper portion of the burner.
[0024] The catalytic burner is constructed of highly porous
materials such as molecular sieves. A particular type of molecular
sieve that can be used in the construction of the burner includes
zeolites. Zeolites are crystalline microporous aluminosilicates
with pores having diameters in the range of 0.2 to 1.0 nm and high
surface areas of up to 1000 m.sup.2/g. Zeolite crystals are
characterized by one to three-dimensional pore systems, having
pores of precisely defined diameter. The corresponding
crystallographic structure is formed by tetrahedras of (AlO.sub.4)
and (SiO.sub.4), which form the basic building blocks for various
zeolite structures. Due to their uniform pore structure, zeolite
crystals exhibit the properties of selective adsorption and high
adsorption capacities for LVP fuels. All zeolites have ion-exchange
ability and can exchange H.sup.+ for cations such as Na.sup.+ and
K.sup.+.
[0025] Zeolites have a Si/Al ratio ranging from 1-[ but preferably
greater than 60. Examples of zeolites that may be used in the
construction of catalytic burners include, without limitation, all
forms of ZSM-5, silicalite, all forms of mordenite, all forms of
zeolite Y, all forms of zeolite X, all forms of zeolite A, all MFI
type zeolites, all faujasite type zeolites, all forms of zeolite
.beta., all forms of zeolite UTD-1, all forms of zeolite UTD-12,
all forms of zeolite UTD-13, all forms of zeolite UTD-18, all forms
of MCM-22, all forms of ferrierite, and all naturally occurring
zeolites. The burners of the claimed invention may also be
constructed from mesoporous materials such as DAM-1, MCM-41,
MCM-48, SBA-15, MSU, and MBS.
[0026] Zeolite-based burners are highly porous and allow the fuel
to travel from the reservoir through the zeolite material at far
greater rates than contemporary flameless catalytic burners
constructed from macroporous materials. Typical fuel travel rates
in zeolite-based burners are 0.2 ml/min to 0.8 ml/min. An optimal
or preferred fuel travel rate in a zeolite-based burner is 0.6
ml/min. The surface area of the zeolite-based catalytic burners
ranges from 10 m.sup.2/g to 1000 m.sup.2/g, and is preferably at
least 400 m.sup.2/g.
[0027] The zeolites are ion exchanged with combustion metal
catalysts such as platinum, palladium, and rhodium and combinations
thereof. This ion exchange process facilitates the uniform
dispersion of the catalyst throughout the structure of the burner.
Additionally, the small pore size of the zeolites induces the
formation of metal nanoparticles, which exposes a greater surface
area of the metal catalysts and leads to more efficient and
complete combustion of the fuel. The small pore size of the
zeolites further facilitates an improvement in the level of VOC
emissions because of their high adsorption capacities for LVP fuels
relative to prior art burners made of macroporous materials. Thus,
zeolite-based burners are environmentally friendly relative to
prior art burners, particularly with respect to their improved VOC
emissions and their ability to burn low LVP fuels.
[0028] An embodiment of the invention provides a zeolite-based
flameless catalytic burner that can reach a higher working
temperature (>275.degree. C.) than currently available burner.
This feature reduces the emission of VOCs from the burner, which in
turn reduces coking. The increased operating temperature of the
current invention is in part due to more efficient catalyst
dispersion in the material, as well as the ability of the fuel to
travel through the burner at faster and more uniform rate. Whereas
current catalytic burners have the catalyst located only on the
surface of the ceramic burner, a zeolite-based burner has catalyst
dispersed throughout the structure of the burner by virtue of the
ion exchange properties of zeolites.
[0029] In certain embodiments of the invention, the
silicon/catalyst (Si/Cat.) ratio of the structure of the
zeolite-based burner may range from 100 to 5. In an embodiment of
the invention, the Si/Cat. ratio at the surface of the burner is
approximately 25. This ratio decreases in a gradient-like manner
from the surface to the center of the burner.
[0030] The burner of the claimed invention further comprises a
binder. The binder, as used herein, refers to any material which
upon heating, binds together to form a rigid structure. Examples of
materials that can be used as binders include materials such as,
without limitation, bentonite, hectorite, laponite,
montmorillonite, ball clay, kaolin, palygorskite (attapulgite),
barasym SSM-100 (synthetic mica-montmorillonite), ripidolite,
rectorite, optigel SH (synthetic hectorite), illite, nontronite,
illite-smectite, sepiolite, beidellite, cookeite, or generally any
type of clay, borosilicate glass, aluminosilicate glass, or glass
fibers.
[0031] The binder is not necessarily limited to a single component
but instead may comprise a mixture of two or more binders, such as
0-15% bentonite and 85-100% laponite. In an embodiment of the
invention, a binder mixture comprising 0-15 wt % bentonite and
85-100 wt % laponite is used in the construction of a catalytic
burner.
[0032] The increased working temperatures of zeolite-based burners
can also be achieved by the addition of a high thermal conductivity
material, such as boron nitride (BN). The BN increases the thermal
conductivity of the monolith and thus higher temperatures are
achieved. A thermal conductor, as used herein, is any material
which assists in the transfer of heat through the burner structure.
In addition to boron nitride, thermal conductors include materials
such as, without limitation, steel, stainless steel, transition
metals, carbon nanofibers, carbon nanotubes, or diamond.
[0033] Additionally, the catalytic burner structure may contain
additives that enhance the combustion of organic compounds. These
additives include materials such as, without limitation, octahedral
layered manganese oxide (OL-1), octachedral molecular sieve
(OMS-1), manganese oxide, or perovskites.
[0034] An embodiment of the invention comprises about 15 wt %
binder, about 84 wt % molecular sieve, and about 1 wt % thermal
conductor.
[0035] In an embodiment of the invention, the catalyst which is
embedded throughout the structure of the catalytic burner, is a
metal catalyst comprising a single metal or a mixture of two or
more metals. Examples of metals that are used as catalysts in
embodiments of the invention include, without limitation, gold,
manganese, cerium, cobalt, copper, lanthanum platinum, palladium,
and rhodium and combination thereof. However, one of ordinarily
skill in the art would recognize that any metal that enhances the
combustion or oxidation of the fuels may be used as a catalyst in
embodiments of the invention, including metals in Group VIII.
[0036] In certain embodiments of the invention, the dispersed
catalyst is comprised of 1-100 wt % platinum and 0-99 wt % rhodium.
In other embodiments of the invention, the catalyst comprises about
75 wt % platinum and about 25 wt % rhodium.
[0037] The catalytic burner systems of the invention present
several advantages over existing burners. Firstly, the construction
of the burner using zeolite or molecular sieve materials permits
the sequestration of the catalyst in the pores of the molecular
sieve. This allows placement of the catalyst in specific areas of
the upper portion of the burner, and also permits the introduction
of other metals into the pores. Secondly, the porosity of the
molecular sieves facilitates the increased flow of fuel through the
system. The walls of the pores of the molecular sieves are
themselves extremely porous, unlike the pore walls of macroporous
ceramic materials that have low porosity and prevent flow of fuel.
Consequently, zeolite-based burners have a higher flow rate and
flow volume. Since flow rate and flow volume together dictate how
fast and how much fuel reach the catalyst, higher flow rates and
volumes promote higher temperature of the catalyst. The ability of
zeolites to selectively adsorb molecules allows for more control
over the chemistry of the catalyst and the burner materials. These
properties provide advantages in adapting the chemistry of the
burners for future applications that include changes in fuel
composition.
WORKING EXAMPLES
Example 1
Zeolite/Clay Composite Catalytic Burners
[0038] Typical zeolite/clay catalytic burners are composed of 85 wt
% zeolite (NaX) and 15 wt % bentonite. To 8.5 g zeolite NaX, 1.5 g
of bentonite is added. The solids are mixed vigorously and ground
in a mortar and pestle to ensure complete mixing. Then, 5.5 ml of a
2 wt % polyvinyl alcohol (PVA) and water solution was added to the
solids. After thorough mixing the solids were placed in a die and
pressed at 5000 psig. The compressed pellet was then removed from
the die and dried at 50.degree. C. for 24 hours. The dried pellet
was then placed in a tube furnace and heated to 850.degree. C. for
6 hours. The hardened, formed pellet was then removed and shaped.
After shaping, metal catalysts were absorbed into the composite
form.
[0039] To prepare the catalysts, 30 mg of platinum(II)
acetylacetonate and 10 mg of rhodium(II) acetate were ground
together in a mortar and pestle. The catalyst mixture was then
dissolved in 5 ml acetone. The preformed zeolite composite burner
was dipped into the catalyst solution and allowed to absorb the
catalyst solution. This procedure was repeated as necessary to
ensure complete coverage. The catalyst loaded composite was then
heated at 500.degree. C. under flowing air for 2 hours to decompose
the metal salts. The temperature was then reduced to 250.degree. C.
and the composite was heated for 2 hours under flowing H.sub.2 to
reduce the metal. After cooling to room temperature the completed
catalytic burner was removed.
Example 2
Zeolite/Clay/Boron Nitride (BN) Composite Catalytic Burners
[0040] Typical zeolite/clay/BN catalytic burners are composed of 77
wt % zeolite (NaX), 15 wt % bentonite, and 8 wt % BN. To 7.7 g
zeolite NaX, 1.5 g of bentonite and 0.8 g BN is added. The solids
are mixed vigorously and ground in a mortar and pestle to ensure
complete mixing. Then, 5.5 ml of a 2 wt % polyvinyl alcohol (PVA)
and water solution was added to the solids. After thorough mixing
the solids were placed in a die and pressed at 5000 gpsi. The
compressed pellet was then removed from the die and dried at
50.degree. C. for 24 hours. The dried pellet was then placed in a
tube furnace and heated to 850.degree. C. for .about.6 hours. The
hardened, formed pellet was then removed and shaped. After shaping,
metal catalysts were absorbed into the composite form.
[0041] To prepare the catalysts, 30 mg of platinum(II)
acetylacetonate and 10 mg of rhodium(II) acetate were ground
together in a mortar and pestle. The catalyst mixture was then
dissolved in 5 ml acetone. The pre-formed zeolite composite burner
was dipped into the catalyst solution and allowed to absorb the
catalyst solution. This procedure was repeated as necessary to
ensure complete coverage. The catalyst loaded composite was then
heated at 500.degree. C. under flowing air for 2 hours to decompose
the metal salts. The temperature was then reduced to 250.degree. C.
and the composite was heated for 2 hours under flowing H.sub.2 to
reduce the metal. After cooling to room temperature the completed
catalytic burner was removed.
Example 3
Zeolite/Glass Composite Catalytic Burners
[0042] Typical zeolite/glass catalytic burners are composed of 85
wt. % zeolite (ZSM-5, Si/Al=220) and 15 wt % borosilicate glass. To
8.5 g zeolite ZSM-5, 1.5 g of 270 mesh ground glass is added. The
solids are mixed vigorously and ground in a mortar and pestle to
ensure complete mixing. Then, 4.5 ml of a 2 wt % polyvinyl alcohol
(PVA) and water solution was added to the solids. After thorough
mixing the solids were poured into a mold and dried at 50.degree.
C. for 24 hours. The dried pellet was removed from the mold and
placed in a tube furnace and heated to 1000.degree. C. for .about.1
hour. The hardened, formed pellet was then cooled to room
temperature.
[0043] To prepare the catalysts, 30 mg of platinum(II)
acetylacetonate and 10 mg of rhodium(II) acetate were ground
together in a mortar and pestle. The catalyst mixture was then
dissolved in 5 ml acetone. The pre-formed zeolite composite burner
was dipped into the catalyst solution and allowed to absorb the
catalyst solution. This procedure was repeated as necessary to
ensure complete coverage. The catalyst loaded composite was then
heated at 500.degree. C. under flowing air for 2 hours to decompose
the metal salts. The temperature was then reduced to 250.degree. C.
and the composite was heated for 2 hours under flowing H.sub.2 to
reduce the metal. After cooling to room temperature the completed
catalytic burner was removed.
Example 4
Zeolite/Glass/BN Composite Catalytic Burners
[0044] Typical zeolite/glass/BN catalytic burners are composed of
84 wt. % zeolite (ZSM-5, Si/Al=220), 15 wt % borosilicate glass,
and 1 wt % boron nitride. To 8.4 g zeolite ZSM-5, 1.5 g of 270 mesh
ground glass, and 0.1 g BN is added. The solids are mixed
vigorously and ground in a mortar and pestle to ensure complete
mixing. Then, 4.5 ml of a 2 wt % polyvinyl alcohol (PVA) and water
solution was added to the solids. After thorough mixing the solids
were poured into a mold and dried at 50.degree. C. for 24 hours.
The dried pellet was removed from the mold and placed in a tube
furnace and heated to 1000.degree. C. for .about.1 hour. The
hardened, formed pellet was then cooled to room temperature.
[0045] To prepare the catalysts, 30 mg of platinum(II)
acetylacetonate and 10 mg of rhodium(II) acetate were ground
together in a mortar and pestle. The catalyst mixture was then
dissolved in 5 ml acetone. The pre-formed zeolite composite burner
was dipped into the catalyst solution and allowed to absorb the
catalyst solution. This procedure was repeated as necessary to
ensure complete coverage. The catalyst loaded composite was then
heated at 500.degree. C under flowing air for 2 hours to decompose
the metal salts. The temperature was then reduced to 250.degree. C.
and the composite was heated for 2 hours under flowing H.sub.2 to
reduce the metal. After cooling to room temperature the completed
catalytic burner was removed.
Example 5
Zeolite/Glass/Clay/BN Composite Catalytic Burners
[0046] Typical zeolite/glass/BN catalytic burners are composed of
82 wt. % zeolite (ZSM-5, Si/Al=220), 15 wt % borosilicate glass, 2
wt % bentonite, and 1 wt % boron nitride. To 10.1 g zeolite ZSM-5,
1.8 g of glass fibers, 0.27 g bentonite, and 0.14 g BN is added.
The solids are mixed vigorously and ground in a mortar and pestle
to ensure complete mixing. Then, 4.5 mL of a 2 wt % polyvinyl
alcohol (PVA) and water solution was added to the solids. After
thorough mixing the solids were poured into a mold and dried at
50.degree. C. for 24 hours. The dried pellet was removed from the
mold and placed in a furnace and heated to 1000.degree. C. for
.about.1 hour. The hardened, formed pellet was then cooled to room
temperature.
[0047] To prepare the catalysts, 30 mg of platinum(II)
acetylacetonate and 10 mg of rhodium(II) acetate were ground
together in a mortar and pestle. The catalyst mixture was then
dissolved in 5 mL acetone. The pre-formed zeolite composite burner
was dipped into the catalyst solution and allowed to absorb the
catalyst solution. This procedure was repeated as necessary to
ensure complete coverage. The catalyst loaded composite was then
heated at 500.degree. C. under flowing air for 2 hours to decompose
the metal salts. The temperature was then reduced to 250.degree. C.
and the composite was heated for 2 hours under flowing H.sub.2 to
reduce the metal. After cooling to room temperature the completed
catalytic burner was removed.
Example 6
Zeolite Composite Catalytic Burner With Palladium
[0048] Typical zeolite/glass/BN catalytic burners are composed of
82 wt. % zeolite (ZSM-5, Si/Al=220), 15 wt % borosilicate glass, 2
wt % bentonite, and 1 wt % boron nitride. To 10.1 g zeolite ZSM-5,
1.8 g of glass fibers, 0.27 g bentonite, and 0.14 g BN is added.
The solids are mixed vigorously and ground in a mortar and pestle
to ensure complete mixing. Then, 4.5 ml of a 2 wt % polyvinyl
alcohol (PVA) and water solution was added to the solids. After
thorough mixing the solids were poured into a mold and dried at
50.degree. C. for 24 hours. The dried pellet was removed from the
mold and placed in a furnace and heated to 1000.degree. C. for
.about.1 hour. The hardened, formed pellet was then cooled to room
temperature.
[0049] To prepare the catalyst, 30 mg of palladium(II) acetate an
was dissolved in 5 ml acetone. The pre-formed zeolite composite
burner was dipped into the catalyst solution and allowed to absorb
the catalyst solution. This procedure was repeated as necessary to
ensure complete coverage. The catalyst loaded composite was then
heated at 500.degree. C. under flowing air for 2 hours to decompose
the metal salts. The temperature was then reduced to 250.degree. C.
and the composite was heated for 2 hours under flowing H.sub.2 to
reduce the metal. After cooling to room temperature, the completed
catalytic burner was removed.
* * * * *