Note: Descriptions are shown in the official language in which they were submitted.
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CATALYST-ADSORBENT FILTER FOR AIR PURIFICATION
CROSS-REFERENCE TO RELATED APPLICATIONS
100011 This application claims the benefit of priority of International
Application No.
PCT/CN2018/111425, filed October 23, 2018, the disclosure of which is hereby
incorporated by
reference herein in its entirety.
TECHNICAL FIELD
100021 The present disclosure relates to compositions, devices, and
methods for air
purification. More particularly, the disclosure relates to catalyst-adsorbent
compositions,
devices, and systems, methods of their preparation, and methods of their use
for room
temperature removal of gaseous pollutants from air.
BACKGROUND
100031 Atmospheric pollution is a concern of increasing importance as the
levels of
various atmospheric pollutants continue to increase. Formaldehyde, nitrogen
oxides, sulfur
dioxide, and ammonia are regarded as major pollutants for which various
sorbent systems and
materials are used to remove them from indoor environments.
100041 Traditional pollutant treatment systems and sorbent materials
still face many
challenges, including improving long term performance, increasing the
efficiency of
manufacturing operations, and reducing production costs. Many sorbent
materials are generally
adapted for one type of adsorption application, while being unable to remove
other types of
pollutants. Current cathode air purification technology, for example, requires
two separate layers
for the removal of basic and acidic chemical contaminants, thus requiring more
complex design.
In addition, nonwoven filter systems that utilize carbon pellets result in
high backpressure that
has a detrimental effect on performance.
100051 Thus, there continues to be a need for devices, methods, and
compositions that
can effectively remove multiple pollutants simultaneously.
SUMMARY OF THE DISCLOSURE
100061 The following presents a simplified summary of various aspects of
the present
disclosure in order to provide a basic understanding of such aspects. This
summary is not an
extensive overview of the disclosure. It is intended to neither identify key
or critical elements of
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the disclosure, nor delineate any scope of the particular embodiments of the
disclosure or any
scope of the claims. Its sole purpose is to present some concepts of the
disclosure in a simplified
form as a prelude to the more detailed description that is presented later.
100071 In one aspect of the present disclosure, a catalyst-adsorbent
filter comprises: a
filter body comprising a material selected from polymeric foam, polymeric
fiber, non-woven
fabric, a ceramic, and pulp products (e.g., paper); and a coating formed on
the filter body. The
coating comprises: a manganese oxide catalyst adapted for converting gaseous
pollutants into
chemically-benign species; and an adsorbent adapted for adsorbing the
chemically-benign
species and other gaseous species for which the manganese oxide catalyst is
not adapted to
convert.
100081 In certain embodiments, the adsorbent is selected from a group
consisting of:
silica gel, activated carbon, faujasite, chabazite, clinoptilolite, mordenite,
silicalite, zeolite X,
zeolite Y, ultrastable zeolite Y, ZSM zeolite, offretite, beta zeolite, metal
organic frameworks,
metal oxide, polymers, resins, and combinations thereof.
[00091 In certain embodiments, the adsorbent comprises activated carbon.
100101 In certain embodiments, the activated carbon is synthetic
activated carbon or is
based on or derived from one or more of wood, peat coal, coconut shell,
lignite, petroleum pitch,
petroleum coke, coal tar pitch, fruit pits, nuts, shells, sawdust, wood flour,
synthetic polymer, or
natural polymer.
100111 In certain embodiments, a Bnmauer-Emmett-Teller (BET) surface area
of the
adsorbent is from about 20 m2/g to about 3,000 m2/g.
100121 In certain embodiments, a weight-to-weight ratio of the manganese
oxide to the
adsorbent is from 1:5 to 7:1.
100131 In certain embodiments, the coating further comprises a polymeric
binder, and the
polymeric binder is selected from a group consisting of: polyethylene,
polypropylene, polyolefin
copolymer, polyisoprene, polybutadiene, polybutadiene copolymer, chlorinated
rubber, nitrile
rubber, polychloroprene, ethylene-propylene-diene elastomer, polystyrene,
polyacrylate,
polymethacrylate, polyacrylonitrile, poly(vinyl ester), poly(vinyl halide),
polyamide, cellulosic
polymer, polyimide, acrylic polymer, vinyl acrylic polymer, styrene acrylic
polymer, polyvinyl
alcohol, thermoplastic polyester, thermosetting polyester, poly(phenylene
oxide), poly(phenylene
sulfide), fluorinated polymer, poly(tetrafluoroethylene) polyvinylidene
fluoride,
poly(vinylfluoride) chloro/fluoro copolymer, ethylene chlorotrifluoroethylene
copolymer,
polyamide, phenolic resin, epoxy resin, polyurethane, acrylic/styrene acrylic
copolymer, latex,
silicone polymer, and combinations thereof.
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0 1 4] In certain embodiments, the polymeric binder is present from about 5
wt. % to
about 30 wt. % with respect to a total weight of the coating.
[0015] In certain embodiments, the coating further comprises a
dispersant. In certain
embodiments, the dispersant comprises one or more of an anionic surfactant, a
cationic
surfactant, a zwitterionic surfactant, or a nonionic surfactant.
[0016] In certain embodiments, the filter body comprises a polymeric foam
comprising
polyurethane.
[0017] In certain embodiments, the filter body is in a form of a
honeycomb.
[0018] In another aspect of the present disclosure, a catalyst-adsorbent
composition
comprises: an adsorbent comprising activated carbon; a catalyst comprising
manganese oxide; a
polymeric binder; and a surfactant dispersant.
[0019] In another aspect of the present disclosure, a method of forming a
catalyst-
adsorbent filter comprises: forming a slurry comprising a metal oxide catalyst
and an adsorbent;
coating the slurry onto a filter body comprising a material selected from
polymeric foam,
polymeric fiber, non-woven fabric, a ceramic, and pulp products (e.g., paper);
and drying the
slurry to form the catalyst-adsorbent filter.
[0020] In certain embodiments, the drying occurs at a temperature from
about 80 C to
about 250 C.
[0021] In certain embodiments, the adsorbent comprises activated carbon,
and a BET
surface area of the adsorbent is from about 20 m2/g to about 3,000 m2/g.
[0022] In certain embodiments the metal oxide catalyst comprises
manganese oxide, a
weight-to-weight ratio of the manganese oxide to the adsorbent is from 1:5 to
7:1.
[0023] In certain embodiments the slurry further comprises a polymeric
binder. In
certain embodiments the polymeric binder is present from about 5 wt. % to
about 30 wt. % with
respect to a total weight of the coating. In certain embodiments, the
polymeric binder is selected
from a group consisting of: polyethylene, polypropylene, polyolefin copolymer,
polyisoprene,
polybutadiene, polybutadiene copolymer, chlorinated rubber, nitrile rubber,
polychloroprene,
ethylene-propylene-diene elastomer, polystyrene, polyacrylate,
polymethacrylate,
polyacrylonitrile, poly(vinyl ester), poly(vinyl halide), polyamide,
cellulosic polymer, polyimide,
acrylic polymer, vinyl acrylic polymer, styrene acrylic polymer, polyvinyl
alcohol, thermoplastic
polyester, thermosetting polyester, poly(phenylene oxide), poly(phenylene
sulfide), fluorinated
polymer, poly(tetrafluoroethylene) polyvinylidene fluoride,
poly(vinylfluoride) chloro/fluoro
copolymer, ethylene chlorotrifluoroethylene copolymer, polyamide, phenolic
resin, epoxy resin,
polyurethane, acrylic/styrene acrylic copolymer, latex, silicone polymer, and
combinations
thereof.
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[0024] In certain embodiments the slurry further comprises a dispersant,
and the
dispersant comprises one or more of an anionic surfactant, a cationic
surfactant, a zwitterionic
surfactant, or a nonionic surfactant.
[0025] In certain embodiments, the filter body comprises a polymeric foam
comprising
polyurethane.
[0026] In another aspect of the present disclosure, a catalyst-adsorbent
filter comprises: a
filter body comprising a material selected from polymeric foam, polymeric
fiber, non-woven
fabric, a ceramic, and pulp products (e.g., paper); and a coating formed on
the filter body. The
coating comprising: a manganese oxide catalyst adapted for converting gaseous
pollutants into
chemically-benign species; an adsorbent adapted for adsorbing the chemically-
benign species
together with other gaseous species and volatile organic compounds; a
polymeric binder; and a
dispersant.
[0027] In another aspect of the present disclosure, a volatile organic
compound (VOC)
scrubbing system comprises any embodiments of the aforementioned catalyst-
adsorbent arranged
to contact air received into the VOC scrubbing system. In one embodiment, the
VOC scrubbing
system comprises one or more filtration cartridges having the catalyst-
adsorbent disposed therein
and arranged to contact a flow of air received into the VOC scrubbing system.
[0028] Any embodiments of the aforementioned catalyst-adsorbent may be
disposed
within the one or more filtration cartridges.
[0029] In another aspect of the present disclosure, a method for treating
air comprising a
pollutant selected from SO2, NH3, NO2, NO, and formaldehyde, the method
comprising flowing
a first volume of air into an air treatment chamber that comprises any
embodiments of the
aforementioned catalyst-adsorbent, the first volume of air having a first
concentration of the
pollutant, and contacting the sorbent with the first volume of air, wherein a
second concentration
of the pollutant of the first volume of air is less than or equal to the first
concentration after the
contacting. In certain embodiments, the first volume of air comprises
recirculated air from an
interior of a building. In certain embodiments, the method further comprises
flowing a second
volume of air into the air treatment chamber, the second volume of air having
a third
concentration of the pollutant, and contacting the sorbent with the second
volume of air, wherein
a fourth concentration of the pollutant of the second volume of air is greater
than or equal to the
third concentration after the contacting. In certain embodiments, the second
volume of air
comprises air from outside of the building.
[0030] In another aspect of the present disclosure, an automobile
ventilation system
comprises a component (e.g., a filter, filter unit, container, air duct, etc.)
that comprises any
embodiments of the aforementioned catalyst-adsorbent disposed within the
component.
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100311 In another aspect of the present disclosure, an aircraft
environmental control
system comprises a filter unit that comprises any embodiments of the
aforementioned catalyst-
adsorbent disposed within the filter unit.
100321 In another aspect of the present disclosure, a cathode air filter
for a fuel cell
system comprises a filter unit that comprises any embodiments of the
aforementioned catalyst-
adsorbent disposed within the filter unit. Such cathode air filters system may
be incorporated
into, for example, fuel cell systems for vehicles, homes, or industrial use.
100331 In another aspect of the present disclosure, an air control system
for removing a
pollutant from atmospheric air comprises a filter unit that comprises any
embodiments of the
aforementioned sorbent disposed within the filter unit.
100341 As used herein, the term "adsorbent material" refers to a material
that can adhere
gas molecules, ions, or other species within its structure (e.g., removal of
CO2 from air).
Specific materials include but are not limited to clays, metal organic
framework, activated
alumina, silica gel, activated carbon, molecular sieve carbon, zeolites (e.g.,
molecular sieve
zeolites), polymers, resins, and any of these components or others having a
gas-adsorbing
material supported thereon (e.g., such as the various embodiments of sorbents
described herein).
Certain adsorbent materials may preferentially or selectively adhere
particular species.
100351 Also as used herein, the term "catalyst-adsorbent" refers to a
material that has
dual catalytic and adsorptive properties. For example, a catalyst-adsorbent
layer, upon contact
with a molecular species, may catalyze the conversion of the molecular species
into one or more
byproducts, and may also be capable of adsorbing the molecular species and/or
the one or more
byproducts. The catalyst-adsorbent layer may also be capable of adsorbing
other molecular
species that cannot be reacted catalytically by the catalyst-adsorbent layer.
100361 As used herein, the term "adsorption capacity" refers to a working
capacity for an
amount of a chemical species that an adsorbent material can adsorb under
specific operating
conditions (e.g., temperature and pressure). The units of adsorption capacity,
when given in
units of mg/g, correspond to milligrams of adsorbed gas per gram of sorbent.
100371 Also as used herein, the term "particles" refers to a collection
of discrete portions
of a material each having a largest dimension ranging from 0.1 gm to 50 mm.
The morphology
of particles may be crystalline, semi-crystalline, or amorphous. The size
ranges disclosed herein
can be mean/average or median size, unless otherwise stated. It is noted also
that particles need
not be spherical, but may be in a form of cubes, cylinders, discs, or any
other suitable shape as
would be appreciated by one of ordinary skill in the art. "Powders" and
"granules" may be types
of particles.
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100381 Also as used herein, the term "monolith" refers to a single
unitary block of a
particular material. The single unitary block can be in the form of, e.g., a
brick, a disk, or a rod
and can contain channels for increased gas flow/distribution. In certain
embodiments, multiple
monoliths can be arranged together to form a desired shape. In certain
embodiments, a monolith
may have a honeycomb shape with multiple parallel channels each having a
square shape, a
hexagonal shape, or another other shape.
100391 Also as used herein, the term "dispersant" refers to a compound
that helps to
maintain solid particles in a state of suspension in a fluid medium, and
inhibits or reduces
agglomeration or settling of the particles in the fluid medium.
100401 Also as used herein, the term "binder" refers to a material that,
when included in a
coating, layer, or film (e.g., a washcoated coating, layer, or film on a
substrate), promotes the
formation of a continuous or substantially continuous structure from one outer
surface of the
coating, layer, or film through to the opposite outer surface, is
homogeneously or semi-
homogeneously distributed in the coating, layer, or film, and promotes
adhesion to a surface on
which the coating, layer, or film is formed and cohesion between the surface
and the coating,
layer, or film.
100411 Also as used herein, the terms "stream" or "flow" broadly refer to
any flowing gas
that may contain solids (e.g., particulates), liquids (e.g., vapor), and/or
gaseous mixtures.
100421 Also as used herein, the terms "volatile organic compounds" or
"VOCs" refer to
organic chemical molecules having an elevated vapor pressure at room
temperature. Such
chemical molecules have a low boiling point and a large number of the
molecules evaporate
and/or sublime at room temperature, thereby transitioning from a liquid or
solid phase to a gas
phase. Common VOCs include, but are not limited to, formaldehyde, benzene,
toluene, xylene,
ethylbenzene, styrene, propane, hexane, cyclohexane, limonene, pinene,
acetaldehyde,
hexaldehyde, ethyl acetate, butanol, and the like.
100431 Also as used herein, the terms "unpurified air" or "unpurified air
stream" refer to
any stream that contains one or more pollutants at a concentration or content
at or above a level
that is perceived as nuisance, is considered to have adverse effects on human
health (including
short term and/or long term effects), and/or causes adverse effects in the
operation of equipment.
For example, in certain embodiments, a stream that contains formaldehyde at a
concentration
greater than 0.5 part formaldehyde per million parts of air stream calculated
as an eight hour time
weighted average concentration pursuant to "action level" standards set forth
by the
Occupational Safety & Health Administration is an unpurified air stream. In
certain
embodiments, a stream that contains formaldehyde at a concentration greater
than 0.08 part
formaldehyde per million parts of air stream calculated as an eight hour time
weighted average
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concentration pursuant to national standards in China is an unpurified air
stream. Unpurified air
may include, but is not limited to, formaldehyde, ozone, carbon monoxide (CO),
VOCs, methyl
bromide, water, amine-containing compounds (e.g., ammonia), sulfur oxides,
hydrogen sulfide,
and nitrogen oxides.
100441 Also as used herein, the terms "purified air" or "purified air
stream" refer to any
stream that contains one or more pollutants at a concentration or content that
is lower than the
concentration or content of the one or more pollutants in what would be
considered an unpurified
air stream.
100451 Also as used herein, the term "substrate" refers to a material
(e.g., a metal, semi-
metal, semi-metal oxide, metal oxide, polymeric, ceramic, paper, pulp/semi-
pulp products, etc.)
onto or into which the catalyst is placed. In certain embodiments, the
substrate may be in the
form of a solid surface having a washcoat containing a plurality of catalytic
particles and/or
adsorbent particles. A washcoat may be formed by preparing a slurry containing
a specified
solids content (e.g., 30-50% by weight) of catalytic particles and/or
adsorbent particles, which is
then coated onto a substrate and dried to provide a washcoat layer. In certain
embodiments, the
substrate may be porous and the washcoat may be deposited outside and/or
inside the pores.
100461 Also as used herein, the term "nitrogen oxide" refers to compounds
containing
nitrogen and oxygen including but not limited to, nitric oxide, nitrogen
dioxide, nitrous oxide,
nitrosylazide, ozatetrazole, dinitrogen trioxide, dinitrogen tetroxide,
dinitrogen pentoxide,
trinitramide, nitrite, nitrate, nitronium, nitrosonium, peroxonitrite, or
combinations thereof.
100471 Also as used herein, the term "sulfur compounds" refers to
compounds containing
sulfur including but not limited to sulfur oxides (sulfur monoxide, sulfur
dioxide, sulfur trioxide,
disulfur monoxide, disulfiir dioxide), hydrogen sulfide, or combinations
thereof.
100481 Also as used herein, the term "about," as used in connection with
a measured
quantity, refers to the normal variations in that measured quantity, as
expected by the skilled
artisan making the measurement and exercising a level of care commensurate
with the objective
of measurement and the precision of the measuring equipment. For example, when
"about"
modifies a value, it may be interpreted to mean that the value can vary by
1%.
100491 Surface area, as discussed herein, is determined by the Brunauer-
Emmett-Teller
(BET) method according to DIN ISO 9277:2003-05 (which is a revised version of
DIN 66131),
which is referred to as "BET surface area." The specific surface area is
determined by a
multipoint BET measurement in the relative pressure range from 0.05-0.3 plpo.
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BRIEF DESCRIPTION OF THE DRAWINGS
[00501 The present disclosure is illustrated by way of example, and not
by way of
limitation, in the figures of the accompanying drawings, in which:
100511 Fig. 1 depicts an illustrative air-flow system in accordance with
an embodiment of
the disclosure;
100521 Fig. 2A depicts a cross-section of a filter body having a catalyst-
adsorbent coating
formed thereon in accordance with an embodiment of the disclosure;
100531 Fig. 2B depicts a cross-section of a catalyst-adsorbent coating
formed on a surface
of a filter body in accordance with an embodiment of the disclosure; and
100541 Fig. 3 is a flow diagram illustrating a method of forming a
catalyst-adsorbent
filter sorbent in accordance with an embodiment of the disclosure.
DETAILED DESCRIPTION
100551 The embodiments described herein relate to catalyst-adsorbent
compositions and
systems for removing pollutants from air. More specifically, the catalyst-
adsorbent compositions
may be incorporated into indoor air, cabin air, and cathode air purification
systems, which may
be designed to remove toxic chemical pollutants such as formaldehyde, ozone,
carbon monoxide,
nitrogen oxides, sulfur dioxide, amines (including ammonia), sulfur compounds
(including
thiols), chlorinated hydrocarbons, and other alkali or acidic chemicals.
100561 In certain embodiments, a high surface area adsorbent (e.g.,
activated carbon)
mixed with a metal oxide catalyst (e.g., manganese oxide) and other functional
additives yields a
catalyst-adsorbent composition that serves as an all-in-one solution for
removing gaseous
pollutions described herein with high efficiency. The catalyst-adsorbent
composition may be
coated onto a filter body, such as an open-pored foam, honeycomb, or nonwoven
filter body, to
increase filtration efficiency and facilitate acceptable backpressure.
100571 The embodiments of the present disclosure allow for air
purification at low
temperatures (e.g., room temperature ranges from 20 C to 25 C) without
requiring heating of
the unpurified air or catalyst-adsorbent filter. In addition, the materials
and relatively low
temperatures utilized in forming the catalyst-adsorbent composition allow for
a broader range of
filters, such as polymeric foam materials, that would otherwise be
incompatible with higher
temperature processes used for coating metallic filters.
100581 The embodiments of the present disclosure further allow for
effective catalysis
without the use of ultra-violet (UV) radiation or electricity, and are free of
photo-catalytic
chemistry.
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100591 The embodiments of the present disclosure further allow for the
formation of
catalyst-adsorbent filters that are free of detectable odors even after long
term operation.
100601 Fig. 1 depicts an illustrative air-flow system 100 in accordance
with an
embodiment of the disclosure. The system 100 includes a filter unit 104 and an
HVAC system
106 installed as part of a building 102. As shown in Fig. 1, the filter
scrubber unit 104 and the
HVAC system 106 are fluidly coupled to each other and to the interior air
space of the building
102 such that a recirculation air flow path 108 is established. As various
pollutants, such as
VOCs, accumulate within the interior air space of the building 102, interior
air is recirculated
through the filter unit 104 to catalyze and/or adsorb the pollutants using a
catalyst-adsorbent
filter, as described herein. Purified air then passes through the HVAC system
106, which may be
further filtered (e.g., to remove dust and other particulates) and may be
heated or cooled before
being recirculated back into the building 102.
[0061] The embodiment of system 100 is merely illustrative, and it is to
be understood
that the embodiments of catalyst-adsorbent filters described herein may be
incorporated into
other systems for treating air, such as an automobile ventilation system, and
aircraft
environmental control system, an air control system for treating atmospheric
air,
humidifying/dehumidifying systems, odor removal systems, VOC scrubbing
systems, treatment
systems for cathode air in fuel cell systems for cars, homes, or industrial
use, and other systems.
100621 Figs. 2A and 2B depict a cross-sections of a catalyst-adsorbent
filter 200 formed
in accordance with an embodiment of the disclosure. The catalyst-adsorbent
filter 200 includes a
filter body 210, which is illustrated as being in a form of a honeycomb filter
with air
passageways 215 formed therethrough. It is to be understood that the honeycomb
filter is merely
illustrative, and that other filter shapes may be used. The catalyst-adsorbent
filter 200 further
includes a catalyst-adsorbent composition coated onto interior walls of the
filter body 200.
[0063] In certain embodiments, the filter body may be in the form of an
open-pored
foam, a honeycomb, or a nonwoven filter body. In certain embodiments, a
material of the filter
body may be ceramic (e.g., porous ceramic), metallic, polymeric foam, plastic,
paper, fibrous
(e.g., polymeric fiber), or combinations thereof. For example, in certain
embodiments, the filter
body may be formed from polyurethane fibers or a polyurethane foam. In certain
embodiments,
the filter body may be a metallic monolithic filter body, a ceramic monolithic
filter body, a paper
filter body, a polymer filter body, or a ceramic fiber monolithic substrate.
In certain
embodiments, the filter body may be an HVAC duct, an air filter, or a louver
surface. In certain
embodiments, the filter body may be a portable air filter, or a filter
disposed in a vehicle, such as
a motor vehicle, railed vehicle, watercraft, aircraft, or space craft.
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100641 In certain embodiments, the catalyst-adsorbent composition may be
formulated as
a slurry and washcoated onto the filter body. In certain embodiments, a
loading of the catalyst-
adsorbent composition on the filter body may range from about 0.5 g/in3 to
about 4 g/in3 with
respect to a volume of the filter body. In certain embodiments, the catalyst-
adsorbent
composition may be coated onto the filter body and may form a single catalyst-
adsorbent layer
on the solid substrate or a plurality of catalyst-adsorbent layers. If a
plurality of catalyst-
adsorbent layers is coated on the solid substrate, the layers may vary in
their compositions or
alternatively all catalyst-adsorbent layers may have the same composition.
100651 In certain embodiments, the catalyst of the catalyst-adsorbent
composition may
comprise a catalytic metal oxide. The catalytic metal oxide may include one or
more of
manganese oxide, cobalt oxide, molybdenum oxide, chromium oxide, copper oxide,
or cerium
oxide. In certain embodiments, the metal oxide may be a rare earth metal
oxide.
100661 In certain embodiments, the catalytic metal oxide is manganese
oxide. In certain
embodiments, the manganese oxide is amorphous or at least partially amorphous.
In certain
embodiments, the manganese oxide is semi-crystalline. In certain embodiments,
the manganese
oxide may comprise cryptomelane, birnessite, vernadite, manganese oxide
polymorph I, poorly
crystalline cryptomelane, amorphous manganese oxide, polymorphs thereof,
amorphous
manganese oxide, or mixtures thereof
100671 In certain embodiments, the metal oxide catalyst is present from
about 10 wt. %
to about 90 wt. %, from about 20 wt. % to about 90 wt. %, from about 30 wt. %
to about
90 wt. %, from about 30 wt. % to about 80 wt. %, from about 40 wt. % to about
80 wt. %, or
from about 40 wt. % to about 70 wt. % based on a total weight of the catalyst-
adsorbent
composition.
100681 In certain embodiments, the adsorbent of the catalyst-adsorbent
composition
comprises an adsorbent selected from silica gel, activated carbon, faujasite,
chabazite,
clinoptilolite, mordenite, silicalite, zeolite X, zeolite Y, ultrastable
zeolite Y, ZSM zeolite (e.g.,
ZSM-5, ZSM-11), offretite, beta zeolite, metal organic frameworks, metal
oxide, polymers,
resins, and combinations thereof.
100691 In certain embodiments, the adsorbent may include an adsorbent
material may
include a primary adsorbent (such as one or more discussed above) on a
supporting material,
such as carbon, an oxide (e.g., alumina, silica), or zeolite.
100701 In certain embodiments, the adsorbent comprises activated carbon.
The activated
carbon may be synthetic activated carbon or based on or derived from wood,
peat coal, coconut
shell, lignite, petroleum pitch, petroleum coke, coal tar pitch, fruit pits,
nuts, shells, sawdust,
wood flour, synthetic polymer, natural polymer, and combinations thereof.
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[0071] In certain embodiments, the adsorbent includes a plurality of
porous particles in a
powder form. In certain embodiments, an average size of the particles/powder
ranges from
about 1.0 gm to about 100 gm. In certain embodiments, the average size ranges
from about
5.0 pm to about 50 gm. In certain embodiments, a BET surface area of the
adsorbent is from
about 20 m2/g to about 3,000 m2/g, or greater.
[0072] In certain embodiments, the BET surface area of the adsorbent is
from about
50 m2/g to about 3,000 m2/g. In certain embodiments, the BET surface area of
the adsorbent is
from about 100 m2/g to about 3,000 m2/g. In certain embodiments, the BET
surface area of the
adsorbent is from about 250 m2/g to about 3,000 m2/g. In certain embodiments,
the BET surface
area of the adsorbent is from about 500 m2/g to about 3,000 m2/g. In certain
embodiments, the
BET surface area of the adsorbent is from about 600 m2/g to about 3,000 m2/g.
In certain
embodiments, the BET surface area of the adsorbent is from about 700 m2/g to
about 3,000 m2/g.
In certain embodiments, the BET surface area of the adsorbent is from about
800 m2/g to about
3,000 m2/g. In certain embodiments, the BET surface area of the adsorbent is
from about
900 m2/g to about 3,000 m2/g. In certain embodiments, the BET surface area of
the adsorbent is
from about 1,000 m2/g to about 3,000 m2/g. In certain embodiments, the BET
surface area of the
adsorbent is from about 1,000 m2/g to about 2,750 m2/g. In certain
embodiments, the BET
surface area of the adsorbent is from about 1,000 m2/g to about 2,500 m2/g. In
certain
embodiments, the BET surface area of the adsorbent is from about 1,100 m2/g to
about
2,500 m2/g. In certain embodiments, the BET surface area of the adsorbent is
from about
1,200 m2/8 to about 2,500 m2/g. In certain embodiments, the BET surface area
of the adsorbent
is from about 1,300 m2/g to about 2,500 m2/g. In certain embodiments, the BET
surface area of
the adsorbent is from about 1,400 m2/g to about 2,500 m2/g. In certain
embodiments, the BET
surface area of the adsorbent is from about 1,500 m2/g to about 2,500 m2/g. In
certain
embodiments, the BET surface area of the adsorbent is from about 1,600 m2/g to
about
2,500 m2/g. In certain embodiments, the BET surface area of the adsorbent is
from about
1,700 m2/g to about 2,500 m2/g. In certain embodiments, the BET surface area
of the adsorbent
is from about 1,800 m2/g to about 2,500 m2/g. In certain embodiments, the BET
surface area of
the adsorbent is from about 1,800 m2/g to about 2,400 m2/g. In certain
embodiments, the BET
surface area of the adsorbent is from about 1,800 m2/g to about 2,300 m2/g.
[0073] In certain embodiments, the adsorbent is activated carbon having a
BET surface
area from about 1,000 m2/g to about 2,500 m2/g. In certain embodiments, the
adsorbent is
activated carbon having a BET surface area from about 1,800 m2/g to about
2,300 m2/g.
[0074] In order to increase capacity of the porous support utilized in
the embodiments of
the present disclosure, the adsorbent can be activated. The activation may
include subjecting the
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adsorbent (e.g., particles) to various conditions including, but not limited
to, ambient
temperature, vacuum, an inert gas flow, or any combination thereof, for a
sufficient time to
activate the adsorbent. In certain embodiments, the adsorbent may be activated
by calcining.
100751 In certain embodiments, a weight-to-weight ratio of the manganese
oxide to the
adsorbent is from 1:1 to 7:1. In certain embodiments, the weight-to-weight
ratio is from 2:1 to
5:1. In certain embodiments, the weight-to-weight ratio may be 1:1, 2:1, 3:1,
4:1, 5:1, 6:1, 7:1,
or any combination of subranges defined therebetween. In certain embodiments,
the weight-to-
weight ratio may be 1:1 to 1:5. In certain embodiments, the weight-to-weight
ratio may be 1:1,
1:2, 1:3, 1:4, 1:5, or any combination of subranges defined therebetween.
100761 In certain embodiments, the catalyst-adsorbent composition may
further comprise
a binder. Examples of suitable binders may include but are not limited to:
polyethylene,
polypropylene, polyolefin copolymers, polyisoprene, polybutadiene,
polybutadiene copolymers,
chlorinated rubber, nitrile rubber, polychloroprene, ethylene-propylene-diene
elastomers,
polystyrene, polyacrylate, polymethacrylate, polyacrylonitrile, poly(vinyl
esters), poly (vinyl
halides), polyamides, cellulosic polymers, polyimides, acrylics, vinyl
acrylics, styrene acrylics,
polyvinyl alcohols, thermoplastic polyesters, thermosetting polyesters,
poly(phenylene oxide),
poly(phenylene sulfide), fluorinated polymers such as
poly(tetrafluoroethylene), polyvinylidene
fluoride, poly(vinlyfluoride) and chloro/fluoro copolymers such as ethylene
chlorotrifluoroethylene copolymer, polyamide, phenolic resins, polyurethane,
acrylic/styrene
acrylic copolymer latex and silicone polymers.
100771 In certain embodiments, the binder is a polymeric binder selected
from:
polyethylene, polypropylene, polyolefin copolymer, polyisoprene,
polybutadiene, polybutadiene
copolymer, chlorinated rubber, nitrile rubber, polychloroprene, ethylene-
propylene-di ene
elastomer, polystyrene, polyacrylate, polymethacrylate, polyacrylonitrile,
poly(vinyl ester),
poly(vinyl halide), polyamide, cellulosic polymer, polyimide, acrylic polymer,
vinyl acrylic
polymer, styrene acrylic polymer, polyvinyl alcohol, thermoplastic polyester,
thermosetting
polyester, poly(phenylene oxide), poly(phenylene sulfide), fluorinated
polymer,
poly(tetrafluoroethylene) polyvinylidene fluoride, poly(vinylfluoride)
chloro/fluoro copolymer,
ethylene chlorotrifluoroethylene copolymer, polyamide, phenolic resin, epoxy
resin,
polyurethane, acrylic/styrene acrylic copolymer, latex, silicone polymer, and
combinations
thereof. In certain embodiments, the binder comprises an acrylic/styrene
copolymer latex and
polyurethane dispersion.
100781 In certain embodiments, the binder, or mixture of binders, is
present from about
wt. % to about 30 wt. % with respect to a total weight of the catalyst-
adsorbent composition
when dried and deposited onto the filter body. In certain embodiments, the
polymeric binder is
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present from about 10 wt. % to about 30 wt. %, from about 15 wt. % to about 30
wt. %, from
about 5 wt. % to about 25 wt. %, from about 5 wt. % to about 20 wt. %, from
about 10 wt. % to
about 20 wt. %, or from about 15 wt. % to about 20 wt. %.
[0079] In certain embodiments, the catalyst-adsorbent composition
includes a dispersant.
The dispersant may include one or more of an anionic surfactant, a cationic
surfactant, a
zwitterionic surfactant, or a nonionic surfactant. In certain embodiments, the
dispersant is a
nonionic acrylic copolymer.
[0080] Fig. 3 is a flow diagram illustrating a method 300 of forming a
catalyst-adsorbent
filter sorbent in accordance with an embodiment of the disclosure. The method
300 begins at
block 302, where a slurry is formed. The slurry comprises a metal oxide
catalyst and an
adsorbent, which may be formed by dissolving the metal oxide catalyst and
adsorbent in an
aqueous solution.
[0081] In certain embodiments, the slurry further comprises a polymeric
binder. In
certain embodiments, the polymeric binder is selected from: polyethylene,
polypropylene,
polyolefin copolymer, polyisoprene, polybutadiene, polybutadiene copolymer,
chlorinated
rubber, nittile rubber, polychloroprene, ethylene-propylene-diene elastomer,
polystyrene,
polyacrylate, polymethacrylate, polyacrylonitrile, poly(vinyl ester),
poly(vinyl halide),
polyamide, cellulosic polymer, polyimide, acrylic polymer, vinyl acrylic
polymer, styrene acrylic
polymer, polyvinyl alcohol, thermoplastic polyester, thermosetting polyester,
poly(phenylene
oxide), poly(phenylene sulfide), fluorinated polymer,
poly(tetrafluoroethylene) polyvinylidene
fluoride, poly(vinylfluoride) chloro/fluoro copolymer, ethylene
chlorotrifluoroethylene
copolymer, polyamide, phenolic resin, epoxy resin, polyurethane,
acrylic/styrene acrylic
copolymer, latex, silicone polymer, and combinations thereof.
[0082] In certain embodiments, the slurry further comprises a dispersant.
The dispersant
may include one or more of an anionic surfactant, a cationic surfactant, a
zwitterionic surfactant,
or a nonionic surfactant.
[0083] In certain embodiments, the slurry further includes an oxidant,
which may
improve removal efficiency of nitrogen oxides. The oxidant may be selected
from nitric acid,
hypochlorite, a persulfate, a peroxide, permanganate, or a chlorate.
[0084] In certain embodiments, the slurry further includes an alkaline
component, such
as a hydroxide, ammonia, or a carbonate, which may improve slurry
stabilization. In certain
embodiments, a pH of the slurry may be adjusted between 2 and 12, or between 4
and 10.
[0085] At block 304, the slurry is coated onto a filter body. The filter
body may
comprise a material selected from polymeric foam, polymeric fiber, non-woven
fabric, a
ceramic, or a pulp product (e.g., paper). In certain embodiments, the filter
body comprises a
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polymeric foam comprising polyurethane. In certain embodiments, the filter
body is in a form of
a honeycomb.
100861 At block 306, the slurry is dried to form the catalyst-adsorbent
filter. In certain
embodiments, the drying is performed at a temperature from about 80 C to about
250 C.
The polymeric binder may be present from about 5 wt. A) to about 30 wt. A)
with respect to a
total weight of the coating.
100871 It is noted that the blocks of method 300 are not limiting, and
that, in certain
embodiments, some or all of the blocks of their respective methods may be
performed. In
certain embodiments, one or more of the blocks may be performed substantially
simultaneously.
Some blocks may be omitted entirely or repeated.
ILLUSTRATIVE EXAMPLES
100881 The following examples are set forth to assist in understanding
the disclosure and
should not, of course, be construed as specifically limiting the embodiments
described and
claimed herein. Such variations of the embodiments, including the substitution
of all equivalents
now known or later developed, which would be within the purview of those
skilled in the art, and
changes in formulation or minor changes in experimental design, are to be
considered to fall
within the scope of the embodiments incorporated herein.
Example 1
100891 A mixture of 5.9 g of a dispersant, 27.4 g of potassium hydroxide
(KOH), and
737 g water was prepared, and 297.6 g Mn02 powder and 59.5 g activated carbon
powder were
then dispersed into the mixture to form a slurry having a 32 wt.% solid
content based on a total
weight of the slurry. A final slurry was achieved by adding to the slurry 31.2
g of a polyacrylic
latex and 31.2 g polyurethane latex binder. The final slurry had a solids
content of about
35 wt.%, a pH of about 10, and a maximum viscosity of 720 centipoise.
Example 2
100901 A test sample was prepared using a polyurethane foam core as a
filter body. The
polyurethane foam core had a diameter of 1 inch and a length of 40
millimeters. The
polyurethane foam core was coated with the final slurry obtained from Example
1. The coated
polyurethane foam core was dried at 110 C and maintained at 110 C for 1
hour. A washcoat
dry gain of the coated polyurethane core was 1.8 g. An additional rectangular
polyurethane foam
sample having dimensions of 408 by 283 millimeters and a 5-millimeter
thickness square
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polyurethane foam was coated by the same procedure, resulting in a washcoat
dry gain of 49.3 g,
which was tested using the GB/T 32085 standard.
Comparative Example 1
[0091] A mixture of 13.2 g of a dispersant, 6.6 g of KOH, 99.3 g of
polyacrylic latex, and
1127 g water was prepared, and 331 g of activated carbon powder was then
dispersed into the
mixture to form a slurry having a 26 wt.% solid content based on a total
weight of the slurry, a
pH of about 8, and a maximum viscosity of 1026 centipoise.
Comparative Example 2
[0092] A test sample was prepared using a polyurethane foam core as a
filter body. The
polyurethane foam core had a diameter of 1 inch and a length of 40 millimeter.
The
polyurethane foam core was coated with the slurry obtained from Comparative
Example 1. The
coated polyurethane foam core was dried at 110 C and maintained at 110 C for
1 hour. A
washcoat dry gain of the coated polyurethane core was 1.0 g.
Results
[0093] Table 1 below summarizes the results obtained from placing the
coated
polyurethane foam cores into a plug-flow reactor. During the tests, the
unpurified air stream
included SO2, NOx, and NH3, each present at 30 ppm. Other parameters of the
air stream
include a temperature of 25 0.5 C, relative humidity of 18%, 10% 02, and a
space velocity of
150,000 III, and a total flow time of 1 hour. Table 1 demonstrates that
Example 2 is capable of
adsorbing more pollutants than Comparative Example 2, with greater SO2
adsorption capacity.
Moreover, Example 2 exhibited improved washcoat adhesion than Comparative
Example 2.
Table 1
Sample SO2 NH3 NO2 adsorption NO adsorption Washcoat
adsorption adsorption capacity (mg/g) capacity adhesion
capacity capacity (mg/g)
(mg/g) (mg/g)
Example 2 79.2 7.7 43.1 5.2 Good
Comparative 49.5 10.1 85.9 No activity Bad
Example 2
[0094] In the foregoing description, numerous specific details are set
forth, such as
specific materials, dimensions, processes parameters, etc., to provide a
thorough understanding
of the embodiments of the present disclosure. The particular features,
structures, materials, or
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characteristics may be combined in any suitable manner in one or more
embodiments. The
words "example" or "exemplary" are used herein to mean serving as an example,
instance, or
illustration. Any aspect or design described herein as "example" or
"exemplary" is not
necessarily to be construed as preferred or advantageous over other aspects or
designs. Rather,
use of the words "example" or "exemplary" is intended to present concepts in a
concrete fashion.
As used in this application, the term "or" is intended to mean an inclusive
"or" rather than an
exclusive "or". That is, unless specified otherwise, or clear from context, "X
includes A or B" is
intended to mean any of the natural inclusive permutations. That is, if X
includes A; X includes
B; or X includes both A and B, then "X includes A or B" is satisfied under any
of the foregoing
instances. In addition, the use of the terms "a," "an," "the," and similar
referents in the context
of describing the materials and methods discussed herein (especially in the
context of the
following claims) are to be construed to cover both the singular and the
plural, unless otherwise
indicated herein or clearly contradicted by context.
100951 Recitation of ranges of values herein are merely intended to serve
as a shorthand
method of referring individually to each separate value falling within the
range, unless otherwise
indicated herein, and each separate value is incorporated into the
specification as if it were
individually recited herein. All methods described herein can be performed in
any suitable order
unless otherwise indicated herein or otherwise clearly contradicted by
context.
100961 Reference throughout this specification to "one embodiment,"
"certain
embodiments," "one or more embodiments," "an embodiment," or "some
embodiments" means
that a particular feature, structure, material, or characteristic described in
connection with the
embodiment is included in at least one embodiment of the present disclosure.
Thus, the
appearances of the phrases such as "in one or more embodiments," "in certain
embodiments,"
"in one embodiment," or "in an embodiment" in various places throughout this
specification are
not necessarily referring to the same embodiment of the present disclosure.
Furthermore, the
particular features, structures, materials, or characteristics may be combined
in any suitable
manner in one or more embodiments.
100971 It is to be understood that the above description is intended to
be illustrative, and
not restrictive. Many other embodiments will be apparent to those of skill in
the art upon
reading and understanding the above description. The scope of the disclosure
should, therefore,
be determined with reference to the appended claims, along with the full scope
of equivalents to
which such claims are entitled. The use of any and all examples, or exemplary
language (e.g.,
"such as") provided herein, is intended merely to better illuminate the
materials and methods and
does not pose a limitation on the scope unless otherwise claimed. No language
in the
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specification should be construed as indicating any non-claimed element as
essential to the
practice of the disclosed materials and methods.
100981 Although the embodiments disclosed herein have been described with
reference
to particular embodiments it is to be understood that these embodiments are
merely illustrative of
the principles and applications of the present disclosure. It will be apparent
to those skilled in
the art that various modifications and variations can be made to the method
and apparatus of the
present disclosure without departing from the spirit and scope of the
disclosure. Thus, it is
intended that the present disclosure include modifications and variations that
are within the scope
of the appended claims and their equivalents, and the above-described
embodiments are
presented for purposes of illustration and not of limitation.
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