In-situ regeneration of filter media to improve catalyst efficiency

Abstract

Various aspects of the present disclosure relate to devices, systems, and methods for regenerating filter media used in purifying an exhaust gas stream. The method can include increasing the NOx removal efficiency of the filter media by increasing the upstream NO2 concentration, where increasing the upstream NO2 concentration includes oxidizing NO outside the exhaust gas stream to produce additional NO2 and introducing the additional NO2 into the exhaust gas stream.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Provisional Application No. 63 / 452,947, filed March 17, 2023, the entire contents of which are incorporated herein by reference for all purposes.

[0002] FIELD OF THE DISCLOSURE This disclosure relates generally to devices, systems and methods for purifying exhaust gas streams, and more particularly to devices, systems and methods for regenerating filter media used in purifying exhaust gas streams. [Background technology]

[0003] Coal-fired power plants, municipal waste incinerators, and oil refineries produce large amounts of exhaust gases containing a variety of environmental pollutants, namely, nitrogen oxides (NOx compounds), mercury (Hg) vapor, and particulate matter (PM). In the United States, approximately 27 million tons of SO2 and 45 tons of Hg are produced annually from coal combustion alone. Therefore, improved methods for removing NOx compounds, sulfur oxides, mercury vapor, and particulate matter from industrial exhaust gases, such as those from coal-fired power plants, are needed. Summary of the Invention [Problem to be solved by the invention]

[0004] Catalytic filter media and bags are used to remove NOx from exhaust gas streams. During the selective reduction of NOx (SCR) process, ammonium hydrogen sulfate (ABS, NH4HSO4) can be produced, which can mask active catalyst sites and shorten catalyst life.

[0005] The present disclosure generally relates to a method for in-situ regenerating catalytic filter media or catalytic filter bags by removing formed ABS and restoring catalytic performance. The method relies on the presence of NO in the exhaust gas stream as it passes through the catalytic filter bag. In some embodiments, the method includes increasing the upstream NO concentration by introducing an oxidizer into the exhaust gas stream. In particular embodiments, the method includes introducing NO into the exhaust gas stream in addition to the oxidizer. In some embodiments, the method includes mixing NO with an oxidizer outside the exhaust gas duct to produce NO, and then injecting the mixed gas containing NO into the exhaust gas duct upstream of a baghouse.

[0006] According to one embodiment ("Embodiment 1"), the method includes providing at least one filter medium; flowing an exhaust gas stream across a cross-section of the at least one filter medium such that the exhaust gas stream passes through the cross-section of the at least one filter medium; and improving the NOx removal efficiency of the at least one filter medium. The at least one filter medium can include at least one catalytic material and an ammonium hydrogen sulfate (ABS) deposit, an ammonium sulfate (AS) deposit, or any combination thereof. The exhaust gas stream can include NOx compounds, the NOx compounds including nitric oxide (NO) and nitrogen dioxide (NO2). In some embodiments, improving the NOx removal efficiency of the at least one filter medium includes increasing an upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds. In certain embodiments, increasing the upstream NO concentration to be in the range of 2% to 99% of the total concentration of upstream NO compounds includes providing a stream of NO, oxidizing the NO stream with at least one oxidant to produce additional NO, and introducing the additional NO into the exhaust gas stream.

[0007] Embodiment 2 is the method of embodiment 1, wherein the NO stream is oxidized prior to introduction into the exhaust gas stream.

[0008] Embodiment 3 is the method of any previous embodiment, wherein providing an NO stream comprises removing at least some NO from the exhaust gas stream and selectively filtering the at least some NO from the exhaust gas stream to obtain the NO stream.

[0009] Embodiment 4 is the method of any previous embodiment, wherein increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds further comprises introducing additional oxidant into the exhaust gas stream.

[0010] Embodiment 5 is the method of any previous embodiment, wherein at least one filter media is regenerated by the method.

[0011] Embodiment 6 is the method of any previous embodiment, wherein the step of oxidizing the NO stream with at least one oxidant to produce additional NO2 is carried out at a temperature between -20°C and 280°C.

[0012] Embodiment 7 is the method of any previous embodiment, wherein the at least one oxidizing agent is hydrogen peroxide (H2O2), ozone (O3), a hydroxyl radical, an organic peroxide, a metal peroxide, a peracid, or any combination thereof.

[0013] Embodiment 8 is the method of any previous embodiment, wherein oxidizing the NO stream comprises reacting the NO stream with an excess of at least one oxidizing agent.

[0014] Embodiment 9 is the method of any previous embodiment, wherein during the flowing step, the temperature of the exhaust gas stream is in the range of 80°C to 450°C.

[0015] Embodiment 10 is the method of embodiment 9, wherein the temperature of the exhaust gas stream is in the range of 160°C to 280°C.

[0016] Embodiment 11 is the method of any previous embodiment, wherein the exhaust gas stream further comprises oxygen (O), water (HO), nitrogen (N), carbon monoxide (CO), sulfur dioxide (SO), sulfur trioxide (SO), one or more hydrocarbons, one or more particulate matter, or any combination thereof.

[0017] Embodiment 12 is the method of any previous embodiment, wherein flowing the exhaust gas stream across a cross-section of the at least one filter media comprises flowing the exhaust gas stream perpendicular to the cross-section of the at least one filter media.

[0018] Embodiment 13 is the method of any previous embodiment, wherein the at least one filter media is disposed within at least one filter bag, and the at least one filter bag is contained within at least one filter bag housing, and the at least one catalytic material is in the form of catalytic particles.

[0019] Embodiment 14 is the method of embodiment 13, wherein the at least one filter media comprises a porous guard layer and a porous catalyst layer, the porous catalyst layer comprising catalyst particles.

[0020] Embodiment 15 is the method of embodiment 14, wherein the porous protective layer of the at least one filter media comprises a microporous layer, and the microporous layer comprises an expanded polytetrafluoroethylene (ePTFE) membrane.

[0021] Embodiment 16 is the method of embodiment 14, wherein the porous catalyst layer of the at least one filter media comprises at least one polymer substrate.

[0022] Embodiment 17 is the method of embodiment 14, wherein the porous catalyst layer comprises at least one ceramic substrate.

[0023] Embodiment 18 is the method of embodiment 14, wherein the porous catalyst layer comprises polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (ETFE), ultra-high molecular weight polyethylene (UHMWPE), polyparaxylylene (PPX), polylactic acid, polyimide, polyamide, polyaramid, polyphenylene sulfide, fibrous glass, or any combination thereof.

[0024] Embodiment 19 is the method of embodiment 14, wherein the catalyst particles are enmeshed within the porous catalyst layer.

[0025] Embodiment 20 is the method of any of embodiments 14 to 19, wherein the porous catalyst layer is in the form of a layered assembly, the layered assembly comprising a porous catalyst film and at least one felt batt, the at least one felt batt being disposed on at least one side of the porous catalyst film.

[0026] Embodiment 21 is the method of embodiment 20, wherein the porous catalyst film comprises an expanded polytetrafluoroethylene (ePTFE) membrane.

[0027] Embodiment 22 is the method of embodiment 20, wherein the at least one felt batt comprises polytetrafluoroethylene (PTFE) felt, PTFE fleece, expanded polytetrafluoroethylene (ePTFE) felt, ePTFE fleece, woven fluoropolymer staple fibers, nonwoven fluoropolymer staple fibers, or any combination thereof.

[0028] Embodiment 23 is the method of any previous embodiment, wherein the at least one catalytic material comprises at least one of vanadium monoxide (VO), vanadium trioxide (VO), vanadium dioxide (VO), vanadium pentoxide (VO), tungsten trioxide (WO), molybdenum trioxide (MoO), titanium dioxide (TiO), silicon dioxide (SiO), aluminum trioxide (AlO), manganese oxide (MnO), zeolite, or any combination thereof.

[0029] Embodiment 24 is the method of any previous embodiment, wherein during the providing step, the ABS deposit is deposited on the catalytic material of the at least one filter media in a percentage ranging from 0.01% to 99% by weight of the at least one filter media.

[0030] Embodiment 25 is the method of any previous embodiment, wherein after the step of increasing the upstream NO concentration to be in the range of 2% to 99% of the total concentration of upstream NO compounds, the ABS deposits are deposited on the catalytic material of the at least one filter media at a rate in the range of 0.01% to 98% by weight of the at least one filter media.

[0031] Embodiment 26 is the method of any previous embodiment, wherein at least one oxidant is O3.

[0032] Embodiment 27 is the method of any previous embodiment, wherein at least one oxidizing agent is H2O2.

[0033] Embodiment 28 is the method of any previous embodiment, wherein increasing the NOx removal efficiency further comprises removing at least some ABS deposits, AS deposits, or any combination thereof from the at least one filter media.

[0034] Embodiment 29 is the method of any previous embodiment, further comprising adding ammonia (NH3) to the exhaust gas stream.

[0035] Embodiment 30 is the method of embodiment 29, wherein the added NH3 has a concentration in the range of 0.0001% to 0.5% of the concentration in the exhaust gas stream.

[0036]

[0013] Embodiment 31 is a method comprising: providing at least one filter medium; flowing an exhaust gas stream across a cross-section of the at least one filter medium such that the exhaust gas stream passes through the cross-section of the at least one filter medium from an upstream side of the filter medium to a downstream side of the filter medium; and maintaining a NOx removal efficiency of the at least one filter medium at least 50% of the initial NOx removal efficiency of the at least one filter medium by providing a NOx concentration measured from the upstream side of the filter medium to be in the range of 2% to 99% of the total concentration of NOx compounds and controlling the NOx concentration measured from the downstream side of the filter medium to be in the range of 0.0001% to 0.5% of the concentration of the exhaust gas stream. In some embodiments, the at least one filter medium comprises at least one catalytic material. In some embodiments, the exhaust gas stream comprises nitrogen oxide (NOx) compounds, the nitrogen oxide (NOx) compounds including nitric oxide (NO) and nitrogen dioxide (NO2); sulfur dioxide (SO2); and ammonia (NH3). In some embodiments, providing a NO concentration measured from the upstream side of the filter media in a range of 2% to 99% of the total concentration of NO compounds includes providing a stream of NO; ​​oxidizing the NO stream with at least one oxidizing agent to produce additional NO; and introducing the additional NO into the exhaust gas stream.

[0037] Embodiment 32 is the method of any of the previous embodiments, wherein the method purifies an exhaust gas stream.

[0038] Embodiment 33 is the method of any previous embodiment, wherein the at least one filter medium comprises a porous catalytic fluoropolymer film having an upstream side and a downstream side, the porous catalytic fluoropolymer film comprising a plurality of perforations, each of the plurality of perforations being a straight passageway from an upstream inlet surface of the porous catalytic fluoropolymer film to a downstream outlet surface of the porous catalytic fluoropolymer film. In some embodiments, the straight passageways are configured to promote flow through the straight passageways relative to flow through pores of the material, and the straight passageways have a diameter of 0.1 mm to 3 mm. In some embodiments, the porous catalytic fluoropolymer film has a fractional open area of ​​0.14% to 50%.

[0039] Embodiment 34 is a system including at least one filter media, at least one filter bag, and at least one filter bag housing. The at least one filter media can include an upstream side, a downstream side, at least one catalytic material, an ammonium hydrogen sulfate (ABS) deposit, an ammonium sulfate (AS) deposit, or any combination thereof. The at least one filter media can be disposed within the at least one filter bag, and the at least one filter bag can be disposed within the at least one filter bag housing. In some embodiments, the at least one filter bag housing is configured to receive an exhaust gas flow that intersects a cross-section of the at least one filter media, causing the exhaust gas flow to pass through the cross-section of the at least one filter media from the upstream side of the at least one filter media to the downstream side of the at least one filter media, and the exhaust gas flow includes NOx compounds, the NOx compounds including nitric oxide (NO) and nitrogen dioxide (NO2). In some embodiments, the system is configured to increase the NOx removal efficiency of the at least one filter media during the step of increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds. In some embodiments, the step of increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds includes providing a NO stream, oxidizing the NO stream with at least one oxidant to produce additional NO2, and introducing the additional NO2 into the exhaust gas stream.

[0040] The foregoing embodiments are merely exemplary and should not be construed as limiting or narrowing the scope of the inventive concepts provided by the present disclosure. While multiple examples are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples. Therefore, the accompanying drawings and detailed description are to be interpreted as illustrative and not restrictive. [Brief explanation of the drawings]

[0041] The accompanying drawings are included to provide a further understanding of the disclosure, constitute a part of this specification, illustrate embodiments, and together with the specification serve to explain the principles of the disclosure.

[0042] [Figure 1A] 1 illustrates an exemplary filter media according to an embodiment of the present disclosure. [Figure 1B] 1 illustrates an exemplary filter media according to an embodiment of the present disclosure. [Figure 1C] 1 illustrates an exemplary filter media according to an embodiment of the present disclosure. [Figure 1D] 1 illustrates an exemplary filter media according to an embodiment of the present disclosure.

[0043] [Figure 2] 1 is a flow diagram of a method for regenerating filter media according to an embodiment of the present disclosure.

[0044] [Figure 3] 1 is a flow diagram of a method for regenerating filter media according to an embodiment of the present disclosure.

[0045] Detailed Description Definitions and Terminology The present disclosure is not intended to be construed in a limiting sense, for example, the terms used in this application should be interpreted broadly in the context of the meaning that one of ordinary skill in the art would give to such terms.

[0046] With respect to terms involving imprecision, the terms "about" and "approximately" may be used interchangeably to refer to measurements that include the stated measurement as well as measurements that are reasonably close to the stated measurement. A measurement that is reasonably close to the stated measurement deviates reasonably slightly from the stated measurement to an extent that is understood and easily identified by one of ordinary skill in the art. Such deviations may result from, for example, measurement error, differences in calibration of measuring and / or manufacturing equipment, human error in reading and / or setting measurements, minor adjustments made to optimize performance and / or structural parameters to account for measurement differences associated with other components, specific implementation scenarios, imprecise adjustment and / or manipulation of objects by humans or machines, etc. If it is determined that a person of ordinary skill in the art would not be able to easily identify such a reasonably small difference, the terms "about" and "approximately" may be understood to mean ±10% of the stated value.

[0047] As used herein, the term "flow-through" means that the exhaust gas stream flows across the cross-section of at least one filter media, such that the exhaust gas stream passes through the cross-section of the at least one filter media. In some embodiments of the "flow-through" configuration, the exhaust gas stream flows perpendicular to the cross-section of the at least one filter media.

[0048] As used herein, the term "flow-by" means that the exhaust gas stream does not flow across the cross-section of the at least one filter media, such that the exhaust gas does not pass through the cross-section of the at least one filter media. In some embodiments of the "flow-by" configuration, the exhaust gas stream flows parallel to the cross-section of the at least one filter media.

[0049] As used herein, "upstream" refers to a location in the exhaust gas stream before it enters the filter media. In the context of "flow-through," "upstream" can refer to a location in the exhaust gas stream before it enters the cross-section of the filter media. In the context of "flow-by," "upstream" can refer to a location in the exhaust gas stream before it enters the enclosure that contains the filter media (e.g., a housing, filter bag, or other suitable enclosure described herein).

[0050] As used herein, "downstream" refers to the location of the exhaust gas flow after it exits the filter media. In the context of "flow-through," "downstream" can refer to the location of the exhaust gas flow after it exits the cross-section of the filter media. In the context of "flow-by," "downstream" can refer to the location of the exhaust gas flow after it exits the enclosure containing the filter media (e.g., a housing, filter bag, or other suitable enclosure described herein).

[0051] As used herein, the term "NOx compounds" refers to any nitrogen oxide. In some non-limiting embodiments, "NOx compounds" can refer specifically to gaseous nitrogen oxides, which are known environmental pollutants.

[0052] As used herein, the term "catalytic composite article" shown in the examples refers to any material comprising a combination of at least one catalytic material and at least one additional material according to any embodiment described herein. The additional material is not limited to any particular type of material and may be, for example, a membrane, a felt batt, a ceramic substrate (including, but not limited to, a ceramic candle), a honeycomb substrate, a monolith substrate, or any combination thereof. The catalytic composite article may, in some non-limiting examples, be a porous catalytic film. Description of Various Embodiments

[0053] Those skilled in the art will readily appreciate that the various aspects of the present disclosure may be implemented by any number of methods and apparatus configured to perform the intended functions. Also, the accompanying drawings referred to herein are not necessarily drawn to scale and may be exaggerated to illustrate various aspects of the present disclosure, and in that regard the drawings should not be construed as limiting.

[0054] As mentioned above, catalytic filter media or bags may be used to remove NOx from exhaust gas streams. NH3 may be applied as a reducing agent during the selective reduction of NOx (SCR) process, where NH3 reacts with NOx to produce N2 and H2O. Sulfur dioxide (SO2) in the exhaust gas may be oxidized to sulfur trioxide (SO3) by SCR, which may then react with NH3 to produce ammonium hydrogen sulfate (ABS, NH4HSO4), which can mask catalytic active sites and shorten catalyst life.

[0055] The present disclosure generally relates to a method for in-situ regeneration of catalytic filter media or catalytic filter bags by removing formed ABS and restoring catalytic performance. According to some embodiments, the method relies on the presence of NO in the exhaust gas stream during flow-through or flow-by of the exhaust gas stream through the catalytic filter bag. In certain embodiments, the catalytic article is used in a flow-through configuration, where gas or liquid flows across (e.g., perpendicular to) the cross-section of the catalytic article, such that the gas or liquid passes through a layer of catalyst particles within the catalytic article. In more specific embodiments, the catalytic article is used in a flow-by configuration, where gas or liquid flows parallel to the cross-section of the catalytic article, such that the gas or liquid flows parallel and diffusely across the catalyst particles in the catalyst layer and does not pass through the cross-section of the catalytic article. In some embodiments, the method includes increasing the NO concentration upstream by introducing an oxidant into the exhaust gas stream to oxidize NO to NO.

[0056] Some compounds present in the exhaust gas may prevent the desired conversion of NO to NO, resulting in an inability of the oxidizing agent, such as ozone or H2O2, to produce sufficient NO2 in the exhaust gas stream. According to some embodiments of the present disclosure, the method includes introducing additional NO2 into the exhaust gas stream. NO2 may be difficult to obtain for injection into the exhaust gas. In certain embodiments, the method includes generating NO2 on-site for injection into the exhaust gas stream.

[0057] In some embodiments, the method includes mixing NO with an oxidant external to or away from the flue gas duct to produce NO, and then injecting the NO-containing gas mixture into the flue gas duct upstream of the baghouse, so that the effectiveness of the oxidant is not affected by fly ash or one or more particulate matter in the flue gas.

[0058] 1A-1D illustrate exemplary filter media according to embodiments of the present disclosure. As shown in FIG. 1A, filter media 101 can be contained within filter bag 100. Flow-through of exhaust gas stream 102 through filter media 101 is permitted by passage through cross section A. After flow-through of exhaust gas stream 102 through filter media 101, flow-by of exhaust gas stream 102 through filter bag 100 is permitted, as indicated by the vertical arrows.

[0059] FIG. 1B illustrates an exemplary filter media 101 according to some embodiments of the present disclosure. As shown in FIG. 1B, an exhaust gas stream 102, which may include NOx compounds and solid particulate matter 107, can flow through cross section A from an upstream side 103 of the filter media 101 to a downstream side 104 of the filter media. While not shown, the upstream side 103 of the filter media 101 may correspond to the exterior of a filter bag, such as filter bag 100, in some embodiments. Similarly, the downstream side 104 of the filter media 101 may correspond to the interior of a filter bag, such as filter bag 100. In some embodiments, the filter media 101 can include at least one protective membrane 106 and one or more felt batts 108 on at least one of the upstream side 103 of the filter media 101, the downstream side 104 of the filter media 101, or any combination thereof. In some embodiments, the one or more felt batts 108 can be disposed on a porous catalyst film 105. In some embodiments, the combination of one or more felt batts 108 and porous catalyst film 105 may be collectively referred to as a porous catalyst layer.

[0060] 1C illustrates one exemplary embodiment of a porous catalyst film 105. As shown, the porous catalyst film 105 can include catalyst particles 109 on at least one surface of the porous catalyst film 105. ABS deposits 110 can be deposited on the surfaces of the catalyst particles 109.

[0061] FIG. 1D illustrates an additional non-limiting, exemplary embodiment of filter media 101. As shown, filter media 101 can include a porous catalyst layer 111. In some non-limiting embodiments, filter media 101 can be in the form of a filter bag. In some embodiments, porous catalyst layer 111 can be coated with a catalytic material (not shown in FIG. 1D), such as catalyst particles. In some embodiments, the catalytic material can be attached to porous catalyst layer 111 by one or more adhesives (not shown in FIG. 1D) described herein. In some embodiments, filter media 101 can include a porous protective membrane 106.

[0062] The present disclosure generally relates to a method for regenerating at least one filter media (e.g., filter media 101 shown in Figures 1A-1D) to improve catalytic efficiency. The method can be used to produce filter media for use in purifying exhaust gas streams.

[0063] In some embodiments, the filter media includes at least one catalytic material. In some embodiments, the at least one catalytic material can include, for example, vanadium monoxide (VO), vanadium trioxide (VO), vanadium dioxide (VO), vanadium pentoxide (VO), tungsten trioxide (WO), molybdenum trioxide (MoO), titanium dioxide (TiO), silicon dioxide (SiO), aluminum trioxide (AlO), manganese oxide (MnO), zeolite, or any combination thereof. In some embodiments, the at least one catalytic material is in the form of catalyst particles.

[0064] In certain embodiments, at least one filter media comprises an upstream side and a downstream side. In some embodiments, the at least one filter media is disposed within at least one filter bag. In some embodiments, multiple filter media are disposed within a single filter bag. In some embodiments, the at least one filter bag is contained within at least one filter bag housing. In some embodiments, multiple filter bags are disposed within a single filter bag housing.

[0065] In some embodiments, a filter medium includes a porous protective layer and a porous catalyst layer. In some embodiments, the porous catalyst layer includes at least one catalyst material. In some embodiments, the at least one catalyst material is disposed on the porous catalyst layer. In some embodiments, the at least one catalyst material is present (e.g., embedded) within the porous catalyst layer.

[0066] In certain embodiments, the porous protective layer comprises a microporous layer. In some embodiments, the microporous layer comprises an expanded polytetrafluoroethylene (ePTFE) membrane. In some embodiments, the at least one catalyst material is adhered to the filter media by at least one adhesive. In some embodiments, the at least one catalyst material is adhered to the porous catalyst layer by at least one adhesive. In some exemplary embodiments, the at least one filter media is in the form of a filter bag, such that the at least one catalyst material is adhered to the porous catalyst layer by at least one adhesive, thereby forming a coated filter bag. In some embodiments, the at least one catalyst material is in the form of catalyst particles, such that the coated filter bag is coated with the catalyst particles.

[0067] In some embodiments, the at least one adhesive is selected from polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), high molecular weight polyethylene (HMWPE), high molecular weight polypropylene (HMWPP), perfluoroalkoxyalkane (PFA), polyvinylidene fluoride (PVDF), vinylidene fluoride (THV), chlorofluoroethylene (CFE), or any combination thereof. In some embodiments, the at least one adhesive is polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), high molecular weight polyethylene (HMWPE), high molecular weight polypropylene (HMWPP), perfluoroalkoxyalkane (PFA), polyvinylidene fluoride (PVDF), vinylidene fluoride (THV), chlorofluoroethylene (CFE), or any combination thereof.

[0068] In some embodiments, the porous catalyst layer comprises at least one polymer substrate. In some embodiments, the polymer substrate comprises at least one of polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (ETFE), ultra-high molecular weight polyethylene (UHMWPE), polyparaxylylene, polylactic acid, polyimide, polyamide, polyaramid, polyphenylene sulfide, fibrous glass, or any combination thereof. In some embodiments, the at least one polymer substrate is polytetrafluoroethylene, poly(ethylene-co-tetrafluoroethylene), ultra-high molecular weight polyethylene, polyparaxylylene (PPX), polylactic acid, polyimide, polyamide, polyaramid, polyphenylene sulfide, fibrous glass, or any combination thereof.

[0069] In some embodiments, the porous catalyst layer comprises at least one ceramic substrate. In some embodiments, the at least one ceramic substrate is in the form of a ceramic candle described herein. In some embodiments, one ceramic substrate comprises ceramic fibers. In some embodiments, the ceramic fibers comprise an alkali metal silicate, an alkaline earth metal silicate, an aluminosilicate, or any combination thereof.

[0070] In some embodiments, the porous catalyst layer is in the form of a layered assembly including a porous catalyst film and one or more felt pads. In some embodiments, the one or more felt pads are disposed on at least one side of the porous catalyst film. In some embodiments, the porous catalyst film includes at least one catalyst material. In some embodiments, the at least one catalyst material is disposed on the porous catalyst film. In some embodiments, the at least one catalyst material is present within (e.g., embedded in) the porous catalyst film.

[0071] In some embodiments, the one or more felt batts comprise at least one of polytetrafluoroethylene (PTFE) felt, PTFE fleece, expanded polytetrafluoroethylene (ePTFE) felt, ePTFE fleece, woven fluoropolymer staple fibers, nonwoven fluoropolymer staple fibers, or any combination thereof. In some embodiments, the one or more felt batts are polytetrafluoroethylene (PTFE) felt, PTFE fleece, expanded polytetrafluoroethylene (ePTFE) felt, ePTFE fleece, woven fluoropolymer staple fibers, nonwoven fluoropolymer staple fibers, and any combination thereof.

[0072] In some embodiments, the porous catalytic film comprises a membrane. In some embodiments, the porous catalytic film comprises a polymer membrane. In some embodiments, the porous catalytic film comprises a fluoropolymer membrane, and the porous catalytic film can be referred to as a porous catalytic fluoropolymer film.

[0073] Non-limiting examples of suitable synthetic polymer membranes include polyurethane, polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), polyvinylidene fluoride (PVDF), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), modified polytetrafluoroethylene polymers, tetrafluoroethylene (TFE) copolymers, polyalkylenes such as polypropylene and polyethylene, polyestersulfone (PES), polyesters, poly(p-xylylene) (ePPX) as taught in U.S. Patent Application Publication No. 2016 / 0032069, and U.S. Patent No. 9,299,499 to Sbriglia. Examples of suitable synthetic polymer membranes include porous ultra-high molecular weight polyethylene (eUHMWPE) as taught in U.S. Patent No. 9,926,416, porous ethylene tetrafluoroethylene (eETFE) as taught in U.S. Patent No. 9,932,429 to Sbriglia, porous polylactic acid (ePLLA) as taught in U.S. Patent No. 7,932,184 to Sbriglia et al., porous vinylidene fluoride-co-tetrafluoroethylene or trifluoroethylene [VDF-co-(TFE or TrFE)] polymers as taught in U.S. Patent No. 9,441,088 to Sbriglia, and copolymers and combinations thereof. In at least one embodiment, the synthetic polymer membrane is a microporous synthetic polymer membrane, such as a microporous fluoropolymer membrane having a microstructure of nodes and fibrils, in which the nodes are interconnected by fibrils and the pores are voids or spaces located between the nodes and fibrils throughout the membrane. An example of a node and fibril microstructure is described in U.S. Patent No. 3,953,566 to Gore. In some embodiments, the porous catalyst film or layer comprises an expanded polytetrafluoroethylene (ePTFE) membrane.

[0074] In some embodiments, a porous catalyst film or layer includes catalyst particles enmeshed within a porous catalyst layer, such as an ePTFE membrane. In some embodiments, the ePTFE membrane has a microstructure, the microstructure including nodes, fibrils, or any combination thereof. In some embodiments, the catalyst particles may be enmeshed within the microstructure. In some embodiments, the catalyst particles may be enmeshed within nodes. In some embodiments, the catalyst particles may be enmeshed within fibrils. In some embodiments, the catalyst particles may be enmeshed within nodes and fibrils.

[0075] In certain embodiments, at least one filter medium can include a porous catalytic fluoropolymer film having an upstream side and a downstream side. The porous catalytic fluoropolymer film can include a plurality of perforations, each of which is a linear passageway from an upstream inlet surface of the porous catalytic fluoropolymer film to a downstream outlet surface of the porous catalytic fluoropolymer film. An example of a porous catalytic fluoropolymer film is described in U.S. Pat. No. 1,107,821 to Gore. In some embodiments, the linear passageways are configured to promote flow through the linear passageways compared to flow through the pores of the material, and the linear passageways can have a diameter of 0.1 mm to 3 mm. In certain embodiments, the porous catalytic fluoropolymer film has an open area ratio of 0.14% to 50%.

[0076] In some embodiments, the at least one filter medium is in the form of a ceramic candle. In some embodiments, the ceramic candle comprises at least one ceramic material. In some embodiments, the at least one ceramic material is selected from silica aluminate, calcium magnesium silicate, calcium silicate fibers, or any combination thereof. In some embodiments, the catalyst particles form a coating on the at least one ceramic material.

[0077] In some embodiments, the at least one filter media can include any material configured to capture at least one of solid particulate matter, liquid aerosols, or any combination thereof from the exhaust gas stream, hi some embodiments, the at least one filter media is in the form of at least one of a filter bag, a honeycomb, a monolith, or any combination thereof.

[0078] In some embodiments, at least one filter medium comprises an ammonium hydrogen sulfate (ABS) deposit, an ammonium sulfate (AS) deposit, or any combination thereof. In some embodiments, the ABS deposit is deposited on at least one catalytic material of the at least one filter medium. In some embodiments, the ABS deposit is deposited within at least one catalytic material of the at least one filter medium.

[0079] In some embodiments, the ABS deposit can be present in a percentage ranging from 0.01% to 99%, or from 0.1% to 99%, or from 1% to 99%, or from 10% to 99%, or from 25% to 99%, or from 50% to 99%, or from 75% to 99%, or from 95% to 99%, by weight of the at least one filter medium, or any percentage subsumed within these ranges.

[0080] In some embodiments, the ABS deposit can be present in a range of 0.01% to 95%, or 0.01% to 75%, or 0.01% to 50%, or 0.01% to 25%, or 0.01% to 10%, or 0.01% to 1%, or 0.01% to 0.1%, by weight of the at least one filter media, or any range encompassed therein.

[0081] In some embodiments, the ABS deposit is present in a range of 0.1% to 95%, or 1% to 75%, or 10% to 50% by weight of the at least one filter media during the providing step.

[0082] FIG. 2 is a flow diagram of a method 200 for regenerating at least one filter media according to an embodiment of the present disclosure.

[0083] The method 200 can include providing at least one filter media in step 202. The at least one filter media can include at least one catalytic material and an ammonium hydrogen sulfate (ABS) deposit, an ammonium sulfate (AS) deposit, or any combination thereof. In certain embodiments, the ABS deposit is deposited on the catalytic material of the at least one filter media in a proportion ranging from 0.01% to 99% by weight of the at least one filter media.

[0084] The method 200 can include, in step 204, flowing the exhaust gas stream across a cross-section of the at least one filter media such that the exhaust gas stream passes through the cross-section of the at least one filter media. In some embodiments, the exhaust gas stream flows from an upstream side to a downstream side of the at least one filter media. In some embodiments, flowing the exhaust gas stream across the cross-section of the at least one filter media includes flowing the exhaust gas stream perpendicular to the cross-section of the at least one filter media.

[0085] In some embodiments, the method 200 can include flowing the exhaust gas stream through (i.e., not intersecting) the at least one filter medium such that the exhaust gas stream does not pass through (i.e., does not intersect with) a cross-section of the at least one filter medium at step 204. In some embodiments, the exhaust gas stream flows parallel to the cross-section of the at least one filter medium.

[0086] In certain embodiments, the temperature of the exhaust gas stream in step 204 can range from about 80°C to about 450°C, or from about 90°C to about 280°C, or from about 100°C to about 280°C, or from about 110°C to about 280°C, or from about 120°C to about 280°C, or from about 130°C to about 280°C, or from about 160°C to 280°C, or any temperature within these ranges.

[0087] In some embodiments, the temperature of the exhaust gas stream in step 204 can range from about 80°C to about 250°C, or from about 80°C to 225°C, or from about 80°C to 200°C, or from about 80°C to 175°C, or from about 80°C to 150°C, or from about 80°C to 125°C, or any temperature contained within these ranges.

[0088] In some embodiments in which at least one filter media in step 204 is in the form of or includes a ceramic substrate (e.g., a ceramic candle), the temperature of the exhaust gas stream can range from about 170°C to about 450°C, or from about 200°C to about 400°C, or from about 200°C to about 450°C, or from about 250°C to about 450°C, or from about 300°C to about 450°C, or from about 350°C to about 450°C, or from about 400°C to about 450°C, or any temperature within these ranges.

[0089] In some embodiments in which at least one filter medium in step 204 is in the form of or includes a ceramic substrate (e.g., a ceramic candle), the temperature of the exhaust gas stream can range from about 170° C. to about 400° C., or from about 170° C. to about 350° C., or from about 170° C. to about 300° C., or from about 170° C. to about 250° C., or from about 170° C. to about 200° C., or any temperature subsumed within these ranges. In some embodiments in which at least one filter medium in the form of or includes a ceramic substrate (e.g., a ceramic candle), the temperature of the exhaust gas stream during the flowing step is in the range of 250° C. to 350° C.

[0090] In some embodiments, the exhaust gas stream can include NOx compounds, including nitric oxide (NO) and nitrogen dioxide (NO2). In particular embodiments, the exhaust gas stream can include NOx compounds (e.g., nitric oxide (NO) and / or nitrogen dioxide (NO2)), sulfur dioxide (SO2), and ammonia (NH3). In some embodiments, the exhaust gas stream can further include oxygen (O2), water (HO), nitrogen (N2), carbon monoxide (CO), sulfur dioxide (SO2), sulfur trioxide (SO3), one or more hydrocarbons, or any combination thereof. In certain embodiments, the exhaust gas stream can include one or more particles, such as fly ash (e.g., particles from a cement plant, silicon oxide, aluminum oxide, iron oxide, calcium oxide, other metal salts, or any combination thereof), one or more dry sorbents (e.g., Ca(OH), CaO, NaHCO, NaCO, or any combination thereof), dust, soot, ash, or the like, or sulfur particulates, or particulates comprising transition metal salts, or any combination thereof.

[0091] In some embodiments, the method 200 can include providing NO from outside the exhaust gas stream in step 206, oxidizing the NO with at least one oxidant to produce NO in step 208, and introducing the NO into the exhaust gas stream in step 210. The NO can be generated outside the exhaust gas stream or away from the exhaust gas stream. In certain embodiments, the NO is oxidized prior to introduction into the exhaust gas stream. Because the NO is generated outside the exhaust gas stream by oxidation of NO with at least one oxidant (e.g., ozone or HO), the fly ash and / or one or more particulate matter in the exhaust gas stream do not directly contact the oxidant. Therefore, the fly ash and / or one or more particulate matter do not interfere with the oxidation of NO or inhibit the production of NO, thereby further improving the catalytic efficiency of the one or more filter media. The concentration of NO ranges from 1 ppm to about 500,000 ppm.

[0092] In an alternative embodiment of step 206, providing NO comprises removing at least a portion of the NO from the flue gas stream and selectively filtering the at least a portion of the NO from the flue gas stream to obtain NO. In some embodiments, the selective filtering removes one or more particulate matter, fly ash, or one or more dry sorbents from the NO removed from the flue gas stream.

[0093] In certain embodiments, oxidizing NO with at least one oxidizing agent to produce NO is carried out at a temperature between −20° C. and 280° C. The at least one oxidizing agent can include hydrogen peroxide (HO), ozone (O), hydroxyl radical, organic peroxide, metal peroxide, peracid, or any combination thereof. In some embodiments, oxidizing NO comprises reacting NO with an excess of at least one oxidizing agent.

[0094] In some embodiments, the at least one oxidizing agent comprises hydrogen peroxide, ozone, an organic peroxide, a metal peroxide, a peracid, or any combination thereof. Examples of at least one organic peroxide that may be suitable for some embodiments of the present disclosure include, but are not limited to, benzoyl peroxide, dibenzoyl peroxide, peracetic acid, acetylacetone peroxide, acetylbenzoyl peroxide, tert-butyl hydroperoxide, naphthoyl peroxide, di(1-naphthoyl) peroxide, diacetyl peroxide, ethyl hydroperoxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, or any combination thereof. Examples of at least one metal peroxide that may be suitable for some embodiments of the present disclosure include, but are not limited to, barium peroxide (BaO), sodium peroxide (NaO), or any combination thereof. Examples of at least one peracid that may be suitable for some embodiments of the present disclosure include, but are not limited to, persulfuric acid (H2SO5), pernitric acid (HNO4), perphosphoric acid (H3PO5), or any combination thereof.

[0095] The method 200 can optionally include introducing an additional oxidant into the exhaust gas stream in step 212. The method 200 can optionally include introducing or adding ammonia (NH3) to the exhaust gas stream in step 214. The added NH3 can have a concentration in the range of 0.0001% to 0.5% of the concentration in the exhaust gas stream.

[0096] In step 216, the method 200 for regenerating at least one filter media can include increasing the NOx removal efficiency of the at least one filter media by increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of NOx compounds upstream. In certain embodiments (not shown in FIG. 2), increasing the NOx removal efficiency further includes removing at least a portion of ABS deposits, AS deposits, or any combination thereof from the at least one filter media.

[0097] In some embodiments, increasing the NOx removal efficiency of at least one filter media can include increasing the NO2 concentration to be in the range of 2% to 99%, or 5% to 99%, or 10% to 99%, or 25% to 99%, or 50% to 99%, or 75% to 99%, or 95% to 99% of the total concentration of NOx compounds in the exhaust gas, or the NO2 concentration can be increased to a percentage within these ranges.

[0098] In some embodiments, increasing the NOx removal efficiency of at least one filter media can include increasing the NO2 concentration to be in the range of 2% to 95%, or 2% to 75%, or 2% to 50%, or 2% to 25%, or 2% to 10%, or 2% to 5% of the total concentration of NOx compounds in the exhaust gas, or the NO2 concentration can be increased to a percentage within these ranges.

[0099] In some embodiments, increasing the NOx removal efficiency of the at least one filter media comprises increasing the NO2 concentration to a range of 5% to 95% of the total concentration of NOx compounds in the exhaust gas. In some embodiments, increasing the NOx removal efficiency of the at least one filter media comprises increasing the NO2 concentration to a range of 10% to 75% of the total concentration of NOx compounds in the exhaust gas. In some embodiments, increasing the NOx removal efficiency of the at least one filter media comprises increasing the NO2 concentration to a range of 25% to 50% of the total concentration of NOx compounds in the exhaust gas.

[0100] In some embodiments, increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds in the exhaust gas can be the result of steps 206, 208, and 210. In some embodiments, increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds in the exhaust gas can be the result of steps 206, 208, 210, and 212.

[0101] In some embodiments, after increasing the upstream NO concentration in step 216 to a value in the range of 2% to 99% of the total concentration of upstream NO compounds in the exhaust gas, the ABS deposits are deposited on the catalytic material of the at least one filter media in a proportion in the range of 0.01% to 98% by weight of the at least one filter media.

[0102] FIG. 3 is a flow diagram of a method 300 for regenerating at least one filter media according to an embodiment of the present disclosure.

[0103] The method 300 can include providing at least one filter media in step 302. The at least one filter media can include at least one catalytic material and an ammonium hydrogen sulfate (ABS) deposit, an ammonium sulfate (AS) deposit, or any combination thereof. In certain embodiments, the ABS deposit is deposited on the catalytic material of the at least one filter media in a proportion ranging from 0.01% to 99% by weight of the at least one filter media.

[0104] The method 300 can include, in step 304, flowing the exhaust gas stream across a cross-section of the at least one filter media such that the exhaust gas stream passes through the cross-section of the at least one filter media. In some embodiments, the exhaust gas stream flows from an upstream side to a downstream side of the at least one filter media. In some embodiments, flowing the exhaust gas stream across the cross-section of the at least one filter media includes flowing the exhaust gas stream perpendicular to the cross-section of the at least one filter media.

[0105] In certain embodiments, the temperature of the exhaust gas stream ranges from 80°C to 450°C. In some embodiments, during the flowing step, the temperature of the exhaust gas stream ranges from 160°C to 280°C. In some embodiments, during the flowing step, the temperature of the exhaust gas stream ranges from 175°C to 280°C. In some embodiments, during the flowing step, the temperature of the exhaust gas stream ranges from 200°C to 280°C. In some embodiments, during the flowing step, the temperature of the exhaust gas stream ranges from 225°C to 280°C. In some embodiments, during the flowing step, the temperature of the exhaust gas stream ranges from 250°C to 280°C.

[0106] In some embodiments, the exhaust gas stream can include NOx compounds (e.g., nitric oxide (NO) and / or nitrogen dioxide (NO2)), sulfur dioxide (SO2), and ammonia (NH3). In some embodiments, the exhaust gas stream can further include oxygen (O2), water (HO), nitrogen (N2), carbon monoxide (CO), sulfur dioxide (SO2), sulfur trioxide (SO3), one or more hydrocarbons, or any combination thereof. In particular embodiments, the exhaust gas stream can include one or more particles, such as fly ash (e.g., particles from a cement plant, silicon oxide, aluminum oxide, iron oxide, calcium oxide, other metal salts, or any combination thereof), dry sorbent (e.g., Ca(OH)2, CaO, NaHCO3, Na2CO3, or any combination thereof), dust, soot, ash, etc., or sulfur particulates, or particulates comprising transition metal salts, or any combination thereof.

[0107] In some embodiments, the method 300 can include providing NO from outside the exhaust gas stream in step 306, oxidizing the NO with at least one oxidant to produce NO in step 308, and introducing the NO into the exhaust gas stream in step 310. The NO can be generated outside the exhaust gas stream. In certain embodiments, the NO is oxidized prior to introduction into the exhaust gas stream. Because the NO is generated outside the exhaust gas stream by oxidation of NO with at least one oxidant (e.g., ozone or HO, or any of the organic peroxides, metal peroxides, or peracids listed above), the fly ash and / or one or more particulate matter in the exhaust gas stream do not come into direct contact with the oxidant. Therefore, the fly ash and / or one or more particulate matter do not interfere with the oxidation of NO or prevent the production of NO, thereby further improving the catalytic efficiency of the one or more filter media.

[0108] In an alternative embodiment of step 306, providing NO comprises removing at least a portion of the NO from the flue gas stream and selectively filtering the at least a portion of the NO from the flue gas stream to obtain NO. In some embodiments, the selective filtering removes one or more particulate matter, fly ash, or one or more dry sorbents from the NO removed from the flue gas stream.

[0109] In certain embodiments, the step of oxidizing NO with at least one oxidizing agent to produce additional NO is carried out at a temperature of about −20° C. to about 280° C., or about −10° C. to about 260° C., or about 0° C. to about 240° C., or about 10° C. to about 220° C., or about 20° C. to about 200° C., or about 30° C. to about 180° C., or about 40° C. to about 160° C., or about 50° C. to about 140° C., or about 65° C. to about 130° C., or about 80° C. to about 120° C. The at least one oxidizing agent can include hydrogen peroxide (HO), ozone (O), hydroxyl radical, organic peroxide, metal peroxide, peracid, or any combination thereof. In some embodiments, oxidizing NO comprises reacting NO with an excess of at least one oxidizing agent.

[0110] The method 300 can optionally include introducing additional oxidant and / or NH3 into the exhaust gas stream in step 312. The added NH3 can have a concentration in the range of 0.0001% to 0.5% of the concentration in the exhaust gas stream.

[0111] The method 300 can include providing a NO concentration measured from the upstream side of the filter media that is in the range of 2% to 99% of the total concentration of NO compounds, in step 314. By providing a NO concentration in the upstream side of the filter media that is in the range of 2% to 99% of the total concentration of NO compounds, the NO removal efficiency of the at least one filter media can be maintained in an amount that is at least 50% of the initial NO removal efficiency of the at least one filter media.

[0112] In some embodiments, providing a NO concentration in the range of 2% to 99% of the total concentration of NO compounds upstream of the filter media can maintain the NO removal efficiency of the at least one filter media at about 50% to about 97%, or about 60% to about 97%, or about 70% to about 97%, or about 75% to about 96%, or about 80% to about 95% of the initial NO removal efficiency of the at least one filter media, or any percentage within these ranges.

[0113] In some embodiments, providing a NO concentration measured from the upstream side of the filter media in a range of 2% to 99% of the total concentration of NOx compounds can be the result of steps 306, 308, and 310. In some embodiments, providing a NO concentration measured from the upstream side of the filter media in a range of 2% to 99% of the total concentration of NOx compounds can be the result of steps 306, 308, 310, and 312.

[0114] The method 300 can further include, at step 316, controlling the NO2 concentration measured from the downstream side of the filter media to be in the range of 0.0001% to 0.5% of the concentration in the exhaust gas stream.

[0115] In some embodiments, a method for purifying an exhaust gas stream includes method 200 or method 300 .

[0116] According to some embodiments, a system includes at least one filter media, at least one filter bag, and at least one filter bag housing. The at least one filter media is disposed within the at least one filter bag, and the at least one filter bag is disposed within the at least one filter bag housing. In some embodiments, the at least one filter media includes an upstream side, a downstream side, at least one catalytic material, an ammonium hydrogen sulfate (ABS) deposit, an ammonium sulfate (AS) deposit, or any combination thereof. In some embodiments, the at least one filter bag housing is configured to receive an exhaust gas flow that intersects a cross-section of the at least one filter media, causing the exhaust gas flow to pass through the cross-section of the at least one filter media from the upstream side of the at least one filter media to the downstream side of the at least one filter media. The exhaust gas flow can include NOx compounds, including nitric oxide (NO) and nitrogen dioxide (NO2).

[0117] In certain embodiments, the system is configured to increase the NOx removal efficiency of the at least one filter media during the step of increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds. In some embodiments, increasing the upstream NO2 concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds includes providing NO, oxidizing the NO with at least one oxidant to produce additional NO2, and introducing the additional NO2 into the exhaust gas stream. [Example]

[0118] Example 1 (no ozone) A gas mixture containing 13 cc / min of 10% NO in N2, 1750 cc / min of N2, and 75 cc / min of O2 was mixed at room temperature and set to flow through the reactor containing 8% moisture. Gas-phase NO and NO2 concentrations were monitored with an MKS MULTI-GAS 2030D FTIR analyzer. The measured NO concentration was 579 ppm, and the NO2 concentration was 18 ppm. The NO2 concentration in the NOx was 3%. Example 2: Injecting NO into an ozone gas stream

[0119] A gas mixture containing 10% NO in N2 at 13 cc / min, 1750 cc / min N2, and 0.64% O3 in O2 at 75 cc / min (O2 concentration of 99.36%) was mixed at room temperature and set to flow through the reactor containing 8% moisture. Gas-phase NO and NO2 concentrations were monitored using an MKS MULTI-GAS 2030D FTIR analyzer. The measured NO concentration was 295 ppm, and the NO2 concentration was 305 ppm. By oxidizing NO with O3, the NO2 concentration in NOx increased to 50.8%. The 0.64% O3 in O2 was generated from a TG-20 O3 generator. Example 3: Catalytic NO 2 reproduction

[0120] An industrial cement production plant equipped with a filter bag house assembly is provided with a reactor pipeline, the reactor pipeline being configured so that its contents are added to the exhaust gas upstream of the filter bag assembly, and a NO source and an ozone source are connected to the reactor pipeline.

[0121] Under normal cement plant operating conditions, when the concentration of ammonium hydrogen sulfate and / or ammonium sulfate reaches the catalyst limit, the NO and ozone sources are turned on to mix approximately equimolar amounts of NO and ozone in the reaction pipeline to generate NO2. This NO2 is produced in the reaction pipeline and enters the flue gas upstream of the baghouse. The increased NO2 concentration removes the ammonium hydrogen sulfate and / or ammonium sulfate, thereby regenerating the catalyst.

[0122] The disclosure of this application has been described above generally and with reference to specific embodiments. It will be apparent to those skilled in the art that various modifications and changes may be made to each embodiment without departing from the scope of the disclosure. Therefore, it is intended that each embodiment cover the modifications and changes of the disclosure provided they fall within the scope of the appended claims and their equivalents.

Claims

1. 1. A method, comprising: Providing at least one filter media, wherein the at least one filter media comprises: at least one catalytic material; ammonium hydrogen sulfate (ABS) deposits, ammonium sulfate (AS) deposits, or any combination thereof; and directing an exhaust gas stream across a cross-section of the at least one filter media such that the exhaust gas stream passes through the cross-section of the at least one filter media, wherein the exhaust gas stream comprises: NOx compounds and the NOx compound comprises Nitric oxide (NO), Nitrogen dioxide (NO ２ )and and increasing the NOx removal efficiency of the at least one filter media; Including, The step of increasing the NOx removal efficiency of the at least one filter media comprises: ２ increasing the concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds; The upstream NO ２ increasing the concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds, providing a flow of NO; oxidizing the NO stream with at least one oxidizing agent to produce additional NO ２ and The additional NO ２ into the exhaust gas stream; A method comprising:

2. 10. The method of claim 1, wherein the NO stream is oxidized prior to introduction into the exhaust gas stream.

3. 2. The method of claim 1, wherein providing the NO stream comprises removing at least a portion of the NO from the exhaust gas stream and selectively filtering the at least a portion of the NO from the exhaust gas stream to obtain the NO stream.

4. The upstream NO ２ increasing the concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds; introducing additional oxidant into said exhaust gas stream. The method of claim 1 further comprising:

5. The method of claim 1 , wherein said method regenerates said at least one filter media.

6. oxidizing the NO stream with at least one oxidizing agent to produce additional NO ２ 2. The method of claim 1, wherein the step of producing is carried out at a temperature of from -20°C to 280°C.

7. The at least one oxidizing agent is hydrogen peroxide (H ２ O ２ ), ozone (O ３ ), a hydroxyl radical, an organic peroxide, a metal peroxide, a peracid, or any combination thereof.

8. The method of claim 1 , wherein oxidizing the NO stream comprises reacting the NO stream with an excess of the at least one oxidizing agent.

9. 10. The method of claim 1, wherein during the flowing step, the temperature of the exhaust gas stream is in the range of 80°C to 450°C.

10. 10. The method of claim 9, wherein the temperature of the exhaust gas stream is in the range of 160°C to 280°C.

11. The exhaust gas stream is oxygen (O ２ ), water (H ２ O), nitrogen (N ２ ), carbon monoxide (CO), sulfur dioxide (SO ２ ), sulfur trioxide (SO ３ ), one or more hydrocarbons, one or more particulates, or any combination thereof.

12. 10. The method of claim 1, wherein flowing the exhaust gas stream across a cross section of the at least one filter media comprises flowing the exhaust gas stream perpendicular to a cross section of the at least one filter media.

13. 10. The method of claim 1, wherein the at least one filter media is disposed within at least one filter bag, the at least one filter bag is contained within at least one filter bag housing, and the at least one catalytic material is in the form of catalytic particles.

14. the at least one filter media: a porous protective layer; A porous catalyst layer 14. The method of claim 13, wherein the porous catalyst layer comprises catalyst particles.

15. 15. The method of claim 14, wherein the porous protective layer of the at least one filter media comprises a microporous layer, the microporous layer comprising an expanded polytetrafluoroethylene (ePTFE) membrane.

16. 15. The method of claim 14, wherein the porous catalyst layer of the at least one filter media comprises at least one polymeric substrate.

17. The method of claim 14 , wherein the porous catalyst layer comprises at least one ceramic substrate.

18. 15. The method of claim 14, wherein the porous catalyst layer comprises polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (ETFE), ultra-high molecular weight polyethylene (UHMWPE), polyparaxylylene (PPX), polylactic acid, polyimide, polyamide, polyaramid, polyphenylene sulfide, fibrous glass, or any combination thereof.

19. The method of claim 14 , wherein the catalyst particles are enmeshed within the porous catalyst layer.

20. The porous catalyst layer is in the form of a layered assembly, the layered assembly comprising: a porous catalyst film; At least one felt bat 15. The method of claim 14, comprising: said at least one felt batt disposed on at least one side of said porous catalyst film.

21. 21. The method of claim 20, wherein the porous catalyst film comprises an expanded polytetrafluoroethylene (ePTFE) membrane.

22. 21. The method of claim 20, wherein the at least one felt batt comprises polytetrafluoroethylene (PTFE) felt, PTFE fleece, expanded polytetrafluoroethylene (ePTFE) felt, ePTFE fleece, woven fluoropolymer staple fibers, nonwoven fluoropolymer staple fibers, or any combination thereof.

23. The at least one catalytic material is selected from the group consisting of vanadium monoxide (VO), vanadium trioxide (V ２ O ３ ), vanadium dioxide (VO ２ ), vanadium pentoxide (V ２ O ５ ), tungsten trioxide (WO ３ ), molybdenum trioxide (MoO ３ ), titanium dioxide (TiO ２ ), silicon dioxide (SiO ２ ), aluminum trioxide (Al ２ O ３ ), manganese oxide (MnO ２ ), zeolites, or any combination thereof.

24. 10. The method of claim 1, wherein during the providing step, an ABS deposit is deposited on the catalytic material of the at least one filter media in a percentage ranging from 0.01% to 99% by weight of the at least one filter media.

25. The upstream NO ２ 10. The method of claim 1, wherein after the step of increasing the concentration to be in the range of 2% to 99% of the total concentration of upstream NOx compounds, ABS deposits have deposited on the catalytic material of the at least one filter medium in a proportion in the range of 0.01% to 98% by weight of the at least one filter medium.

26. The at least one oxidizing agent is O ３ The method of claim 1, wherein

27. The at least one oxidizing agent is H ２ O ２ The method of claim 1, wherein

28. 10. The method of claim 1, wherein the increasing the NOx removal efficiency step further comprises removing at least a portion of the ABS deposits, the AS deposits, or any combination thereof from the at least one filter media.

29. The exhaust gas stream is added to ammonia (NH ３ 10. The method of claim 1, further comprising the step of adding

30. The added NH ３ 30. The method of claim 29, wherein has a concentration in the range of 0.0001% to 0.5% of the concentration of the exhaust gas stream.

31. 1. A method, comprising: providing at least one filter media, wherein the at least one filter media includes at least one catalytic material; directing an exhaust gas stream across a cross-section of the at least one filter media such that the exhaust gas stream passes through the cross-section of the at least one filter media from an upstream side of the filter media to a downstream side of the filter media, wherein the exhaust gas stream comprises: NOx compounds, Nitric oxide (NO), Nitrogen dioxide (NO ２ )and and NOx compounds, which may include Sulfur dioxide (SO ２ )and, Ammonia (NH ３ )and and maintaining a NOx removal efficiency of the at least one filter media in an amount of at least 50% of an initial NOx removal efficiency of the at least one filter media; wherein said retaining step comprises: NO measured from the upstream side of the filter media ２ providing a concentration of NOx compounds in the range of 2% to 99% of the total concentration of NOx compounds measured from the upstream side of the filter media; ２ providing a concentration in the range of 2% to 99% of the total concentration of the NOx compounds, providing a flow of NO; oxidizing the NO stream with at least one oxidizing agent to produce additional NO ２ and The additional NO ２ into the exhaust gas stream; and The NO measured from the downstream side of the filter media ２ controlling the concentration to be in the range of 0.0001% to 0.5% of the concentration of the exhaust gas stream; A method carried out by

32. A method according to any one of the preceding claims, wherein the exhaust gas stream is purified by the method.

33. the at least one filter media: Porous catalyzed fluoropolymer film having an upstream side and a downstream side wherein the porous catalyzed fluoropolymer film comprises a plurality of perforations; each of the plurality of perforations is a straight path from the upstream inlet surface of the porous catalytic fluoropolymer film to the downstream outlet surface of the porous catalytic fluoropolymer film, wherein: i) the linear passages are configured to promote flow through the linear passages relative to flow through pores of the material; and ii) the linear passage has a diameter of 0.1 mm to 3 mm; The method of any one of claims 1 to 32, wherein the porous catalyzed fluoropolymer film has a percent open area of ​​0.14% to 50%.

34. 1. A system comprising: at least one filter media, The upstream side and The downstream side and at least one catalytic material; ammonium hydrogen sulfate (ABS) deposits, ammonium sulfate (AS) deposits, or any combination thereof; at least one filter media comprising: at least one filter bag, wherein the at least one filter media is disposed within the at least one filter bag; at least one filter bag housing, wherein the at least one filter bag is disposed within the at least one filter bag housing; Including, the at least one filter bag housing is configured to receive an exhaust gas flow that intersects a cross-section of the at least one filter medium such that the exhaust gas flow passes through the cross-section of the at least one filter medium from the upstream side of the at least one filter medium to the downstream side of the at least one filter medium; The exhaust gas stream NOx compounds and the NOx compound comprises Nitric oxide (NO), Nitrogen dioxide (NO ２ )and Including, The system includes an upstream NO ２ increasing the NOx removal efficiency of the at least one filter media during the step of increasing the concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds; The upstream NO ２ increasing the concentration to be in the range of 2% to 99% of the total concentration of the upstream NOx compounds; providing a flow of NO; oxidizing the NO stream with at least one oxidizing agent to produce additional NO ２ and The additional NO ２ into the exhaust gas stream; Including, the system.

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