Catalytic filter and associated method of manufacturing

Abstract

A catalytic bag filter includes a body extending from a first end to a second end. The body includes a catalytic filter and a particulate filter. The catalytic filter includes a ceramic paper layer comprised of ceramic fibers, at least one support layer laminated to the ceramic paper layer, and at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer and the at least one support layer. The particulate filter is coupled to the catalytic filter at the first end of the body. A filter interior is delimited by the catalytic filter and the particulate filter.

Description

Patent Attorney Docket No. 3227942WO01CATALYTIC FILTER AND ASSOCIATED METHOD OF MANUFACTURINGCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application is a non-provisional of, and claims the benefit and priority of, U.S. Provisional Patent Application Serial No. 63 / 715,114, filed on November 1, 2024. The entire contents of said application are hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure relates to filters. More particularly, the present disclosure relates to catalytic filters having catalytic activity that are capable of treating exhaust gases at high temperatures while trapping particulate matter. In some embodiments, the catalytic filters are structured as catalytic bag filters.BACKGROUND

[0003] Woven and non-woven bags made from glass or polymeric materials are commonly used in abatement systems in a range of industries including cement, asphalt, pigments and glass. Industry developments have included adding a catalyst to the bags that can also treat gases and reduce the impact on the environment. Current filters are capable of continuous operating at temperatures below 400°C. Accordingly, the currently used filters are limited in their operating temperature range. These filters typically use a catalytic fluoropolymer film, which supports a catalyst. However, the current filters also suffer from poor catalyst utilization due to low or inconsistent catalyst dispersion on the film. The result is that the current filters are inefficient and inconsistent in their effectiveness. Some currently used catalytic bag filters require specialized pre-treatment of non-stick substrates (e.g., non-woven polymer layers, such as polytetrafluoroethylene (PTFE)) to allow catalysts to adhere to the substrate. This pre-treatment adds additional manufacturing time as well as cost. These are just some of the disadvantages associated with catalytic filters that are currently used to filter high temperature exhaust gases.SUMMARY

[0004] Aspects of the following disclosure are directed to embodiment of a catalytic filter. In some embodiments, the catalytic filter includes a ceramic paper layer comprised of ceramic132684305.1Patent Attorney Docket No. 3227942WO01 fibers, at least one support layer laminated to the ceramic paper layer, and at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer and the at least one support layer. In some embodiments of the catalytic filter, the ceramic paper layer comprises woven ceramic fibers. In some embodiments of the catalytic filter, the ceramic paper layer comprises non-woven ceramic fibers. In some embodiments of the catalytic filter, the at least one catalyst is comprised of one of (i) V2O3; (ii) Fe2O3 and (iii) Pt. In some embodiments of the catalytic filter, the ceramic paper layer comprises one or more additives to improve catalytic activity. In some embodiments of the catalytic filter, the one or more additives include at least one of: (i) TiCh; and (ii) zeolites ; and (ii) a zeolite. In some embodiments, the catalytic filter further includes at least two support layers laminated to the ceramic paper layer, wherein the ceramic paper layer is positioned between the at least two support layers.

[0005] Aspects of the following disclosure are directed to embodiments of a catalytic bag filter comprising a body extending from a first end to a second end. In some embodiments, the body comprises a catalytic filter comprising a ceramic paper layer comprised of ceramic fibers, at least one support layer laminated to the ceramic paper layer, and at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer and the at least one support layer. In some embodiments, the catalytic bag filter further includes a particulate filter coupled to the catalytic filter at the first end of the body. In some embodiments, a filter interior is delimited by the catalytic filter and the particulate filter.

[0006] In some embodiments of the catalytic bag filter, the ceramic paper layer comprises woven ceramic fibers. In some embodiments of the catalytic bag filter, the ceramic paper layer comprises non-woven ceramic fibers. In some embodiments of the catalytic bag filter, the catalytic filter is positioned upstream of the particulate filter. In some embodiments of the catalytic bag filter, the at least one catalyst is comprised of one of: (i) V2O3; (ii) Fe2C>3 and (iii) Pt. In some embodiments of the catalytic bag filter, the particulate filter is closed at the second end of the filter body. In some embodiments, the catalytic bag filter further includes at least two support layers laminated to the ceramic paper layer. In some embodiments, the catalytic bag filter further includes a supporting structure configured to support at least one of: (i) the catalytic filter; and (ii) the particulate filter. In some embodiments of the catalytic bag filter, the particulate filter comprises at least one catalyst capable of catalyzing a reaction within a gas passing through the particulate filter to the filter interior.232684305.1Patent Attorney Docket No. 3227942WO01

[0007] Aspects of the following disclosure are directed to methods of manufacturing a catalytic filter. In some embodiments, the method includes forming a ceramic paper layer comprised of ceramic fibers, catalyzing the ceramic paper layer with at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer, laminating the ceramic paper layer and at least one support layer to form a laminated material, and heat treating the laminated material. In some embodiments of the method, the at least one catalyst is comprised of one of: (i) V2O3; (ii) Fe2C>3 and (iii) Pt. In some embodiments of the method, the ceramic paper layer is comprised of woven ceramic fibers. In some embodiments of the method, the ceramic paper layer is comprised of non-woven ceramic fibers.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more particular description of the invention briefly summarized above may be had by reference to the described embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. Thus, for further understanding of the nature and objects of the invention, references can be made to the following detailed description, read in connection with the drawings.

[0009] FIG. 1 schematically illustrates an embodiment of a catalytic filter according to aspects of the disclosure.

[0010] FIG. 2 schematically illustrates an embodiment of a catalytic bag filter according to aspects of the disclosure.

[0011] FIG. 3 schematically illustrates another embodiment of a catalytic filter according to aspects of the disclosure.

[0012] FIG. 4 schematically illustrates another embodiment of a catalytic bag filter according to aspects of the disclosure.

[0013] FIG. 5 schematically illustrates another embodiment of a catalytic bag filter according to aspects of the disclosure.

[0014] FIG. 6 illustrates an embodiment of a method of manufacturing a catalytic filter according to aspects of the disclosure.332684305.1Patent Attorney Docket No. 3227942WO01DETAILED DESCRIPTION

[0015] The following disclosure provides many different embodiments or examples. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and / or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or configurations discussed. To that end, other variations and modifications will be readily apparent to those of sufficient skill. In addition, certain terms may be used throughout this discussion in order to provide a suitable frame of reference with regard to the accompanying drawings. These terms such as “upper”, “lower”, “forward”, “rearward”, “interior”, “exterior”, “top”, “bottom”, “inner”, “outer”, “first”, “second”, and the like are not intended to limit these concepts, except where so specifically indicated. The terms “about” or “approximately” as used herein may refer to a range of 80%-120% of the claimed or disclosed value. The term “similar” refers to two values or configurations as being approximate in shape and / or size, and / or structure. With regard to the drawings, their purpose is to depict salient features and are not specifically provided to scale.

[0016] According to some embodiments of the present disclosure and with reference to FIG. 1, an embodiment of a catalytic filter 100 is schematically shown. In some embodiments, the catalytic filter 100 may comprise a plurality of layers that are laminated or otherwise held together to form a filter composition or filter body 102. In some embodiments, the plurality of layers include a ceramic fiber paper layer 110 and one or more support layers 120, 130. In some embodiments, the ceramic fiber paper layer 110 is positioned between two support layers 120, 130. In some embodiments, the ceramic fiber paper layer 110 comprises, supports, or otherwise carries a catalyst capable of catalyzing a reaction within a target exhaust gas. In any embodiments disclosed herein, the ceramic fiber paper layer 110 may be comprised of woven and / or non-woven fibers. In some embodiments, the fibers are comprised of ceramic and / or glass. In some embodiments, the fibers are comprised of aluminosilicate. In some embodiments, the ceramic fiber paper is comprised of glass and / or ceramic fiber cloth. In some embodiments, the types of fibers, methods of making the ceramic fiber paper layer 110, and suitable catalysts may include432684305.1Patent Attorney Docket No. 3227942WO01 those disclosed in U.S. Patent Nos. 11 ,987,914 and 8, 182,752, the entireties of which are hereby incorporated by reference. In some embodiments, the ceramic fiber paper layer 110 undergoes catalyzing or a catalyst treatment with at least one catalyst such as V2O3, Fe2C>3, Pt, and one or more additives such as T1O2 and zeolites. In some embodiments, the one or more additives may be configured to improve or aid adsorption and / or catalyst activity. In some embodiments, the catalytic filter 100 may be used to convert NOXto N2. In some embodiments, the catalyst operates at temperature ranges that can convert dioxins to furans. In some embodiments, the catalytic filter 100 is capable of operating in high temperature environments, such as above 400°C. In some embodiments, the catalytic filter is configured for operating in temperatures from about 150 °C- 750°C.

[0017] As previously mentioned, existing catalytic filters, for example catalytic bag filters, require specialized pre-treatment of non-stick substrates (e g., non-woven polymer layers, such as polytetrafluoroethylene (PTFE)) to allow catalysts to adhere to the substrate. This pre-treatment adds additional manufacturing time as well as cost. In some embodiments of the disclosed catalytic filter 100, the ceramic fiber paper layer 110 does not require any pretreatment to enhance adhesion of the catalyst. In some embodiments, the catalyst may bind at higher rates (g / cm3or g / cm2) and / or more durably to the ceramic fibers of the ceramic fiber paper layer 110 as compared with polymer or non-stick substrates. In some embodiments, the ceramic fiber paper layer 110 includes a combination of two or more catalysts. Such combinations of catalysts may not be practical and / or possible using existing polymer or non-stick substrates. In some embodiments, the ceramic fiber paper layer 110 has a basis weight of about 200-250 g / m2.

[0018] In some embodiments, the catalyst may be adhered to or supported on the ceramic fibers prior to, or during the formation of the ceramic fiber paper of the ceramic fiber paper layer 110. In some embodiments, the ceramic fiber paper layer 110 may be formed and then treated with catalyst. In some embodiments, the ceramic fiber paper may be laminated with one or more additional layers, such as support layers 120, 130 discussed below prior to, or after catalyzation.

[0019] In some embodiments, the catalytic filter 100 includes one or more support layers 120, 130 that may be laminated to the ceramic fiber paper layer 110. In some embodiments, at least one of the support layers 120, 130 may include a porous scrim, such as a PTFE scrim having a basis weight of 100-400 g / m2, 100-150 g / m2, 300-400 g / m2, 300-350 g / m2, about 125 g / m2, or about 337.5 g / m2. In some embodiments, the scrim is indicated as 130. In some embodiments,532684305.1Patent Attorney Docket No. 3227942WO01 the support layers 120, 130 do not include any fluoropolymer. In some embodiments, one or more of the support layers 120, 130 are perforated (e.g., needle punched). In some embodiments, one or more of the support layers 120, 130 are non-perforated. In some embodiments, the ceramic fiber paper layer 110 is perforated. In some embodiments, the porosity of the ceramic fiber paper layer 110 is from about 60% to about 90%. In some embodiments, the ceramic fiber paper layer 110 is non-perforated. In any embodiment, any perforated layer may be perforated before lamination with additional layers or may be laminated to one or more additional layers and then said laminate may be perforated.

[0020] In some embodiments, lamination may include applying pressure to the ceramic fiber paper layer 110 and the one or more support layers 120, 130. In some embodiments, the applied pressure is between about 350-500 pli (pounds per linear inch). In some embodiments the pressure is applied for less than about 5 seconds. In some embodiments, if the catalytic filter 100 includes three or more layers, then the lamination may include multiple steps whereby subsets of the three or more layers are first laminated prior to a final lamination including all of the layers. In some embodiments, the ceramic fiber paper 110 may be catalyzed prior to, or after lamination. In any embodiment, the catalytic filter 100 or any layers thereof may undergo heat treatment for shrinkage stabilization. In some embodiments, the heat treatment may include heating the catalytic filter 100 (or a portion of the catalytic filter) to about 290-300 °C. In some embodiments, the catalytic filter 100 may be maintained at a temperature from about 290°C to 300°C for less than 10 minutes. In some embodiments, the ceramic fiber paper layer 110 may be heat treated prior to lamination, after lamination with some but not all of the layers of the catalytic filter 100, or after lamination with all of the layers of the catalytic filter 100.

[0021] Turning to FIGS. 2 and 3, an embodiment of a catalytic bag filter or bag filter 200 is shown. In some embodiments, the bag filter 200 includes a filter body 202 extending from a first end 201 to a second end 203. In some embodiments, the bag filter 200 includes a catalytic filter 210. In some embodiments, the catalytic filter 210 is similar to embodiments of the catalytic filter 100 previously discussed and comprises a plurality of layers. Accordingly, in some embodiments, the plurality of layers may include a ceramic fiber paper layer 212 and one or more support layers 214, 216. In some embodiments, the ceramic fiber paper layer 212 is positioned between support layers 214, 216. In some embodiments, the one or more support layers 214, 216 may comprise a metal mesh, polymers scrims 216, and / or other porous layers. In some embodiments, the catalytic632684305.1Patent Attorney Docket No. 3227942WO01 filter 210 may include a ceramic monolith, such as a honeycomb filter, formed from ceramic fibers. In some embodiments, the ceramic fiber paper layer 212 comprises, supports, or otherwise carries a catalyst capable of catalyzing a reaction within a target exhaust gas passing through the catalytic filter 210. In any embodiments disclosed herein, the ceramic fiber paper layer 212 may be comprised of woven and / or non-woven fibers. In some embodiments, the fibers are comprised of aluminosilicate. In some embodiments, the ceramic fiber paper is comprised of a glass and / or ceramic fiber cloth. In some embodiments, the types of fibers, methods of making the ceramic fiber paper layer 212, and suitable catalysts may include those disclosed in U.S. Patent Nos. 11,987,914 and 8,182,752, the entireties of which are hereby incorporated by reference. In some embodiments, the ceramic fiber paper layer 212 undergoes catalyzing or a catalyst treatment with at least one catalyst such as V2O3, Fe2<D3, Pt, and one or more additives such as TiCh and zeolites. In some embodiments, the catalytic filter 210 includes ceramic fibers as a substrate for the catalyst. In some embodiments, the one or more additives may be configured to improve or aid adsorption and catalytic activity. In some embodiments, the catalytic filter 210 may be used to convert NOXto N2. In some embodiments, the catalyst operates at temperature ranges that can convert dioxins to furans. In some embodiments, the catalytic filter 100 is capable of operating in high temperature environments, such as above 400°C. In some embodiments, the catalytic filter and / or the bag filter is configured for operating in temperatures from about 150 °C-750°C.

[0022] Turing to FIG. 3, in some embodiments, the filter body 202 further includes a particulate filter 220. In some embodiments, the catalytic filter 210 and the particulate filter 220 are coupled to, or joined with, each other as shown in FIG. 3 to form the filter body 202. In some embodiments, the particulate filter 220 is connected to the catalytic filter 210 at the first end 201 of the filter body 202. In some embodiments, the particulate filter 220 is closed at the second end 203 of the filter body 202. In some embodiments, the bag filter 200 defines a bag filter interior or filter interior 204 that is delimited by the catalytic filter 210 and the particulate filter 220. In some embodiments, the particulate filter 220 may include any of the layers of the catalytic filter 100, 210 previously discussed. In some embodiments, the particulate filter 220 may comprise, support, or otherwise carry one or more catalysts capable of catalyzing a reaction within a target exhaust gas. In some embodiments, the particulate filter 220 is uncatalyzed. In some embodiments, the particulate filter 220 is configured to remove particulate matter from an exhaust gas moving from an exterior of the bag filter 200 to the filter interior 204 as indicated by the arrows in FIG. 3. In732684305.1Patent Attorney Docket No. 3227942WO01 some embodiments, the catalytic filter 210 is positioned downstream of the particulate filter 220 and includes a catalyst such as any of those described herein or combinations thereof. In some embodiments, the catalytic filter 210 may be configured to be retrofitted into existing bag filters.

[0023] In some embodiments, such as shown in FIG. 4, the bag filter 200’ may include at least two catalytic filters 210, 210’. In such embodiments, the at least two catalytic filters 210, 210’ may be comprised the same as each other or may be comprised differently. For example, in an embodiment, a first catalytic filter 210 may have a first porosity and a second catalytic filter 210’ may have a second porosity that is different than the first porosity. Likewise, in some embodiments, the first catalytic filter 210 may comprise a first basis weight and the second catalytic filter 210’ may comprise a second basis weight that is different than the first basis weight. In another non-limiting example, the first catalytic filter 210 may include a first catalyst and the second catalytic filter 210’ may include a second catalyst that is different from the first catalyst.

[0024] Turning to FIG. 5, another embodiment of a bag filter 300 is shown. In some embodiments, the bag filter 300 includes a body 302 extending from a first end 301 to a second end 303. In some embodiments, the body includes a supporting structure 305, a catalytic filter 310, and a particulate filter 320. In some embodiments, the supporting structure 305 is structured as a metal ring and is configured to support the catalytic filter 310 and / or the particulate filter 320. In some embodiments, the catalytic filter 310 may be similar to previously discussed embodiments of catalytic filter 100, 210. In some embodiments, the bag filter 300 defines a bag filter interior or filter interior 304 that is at least partially delimited by the catalytic filter 310 and the particulate filter 320. In some embodiments, the particulate filter 320 is similar to other embodiments of the particulate filter 220 previously discussed and comprises a catalytic filter media 322 comprised of ceramic and / or glass. In some embodiments, the catalytic filter media 322 is comprised of ceramic and / or glass fibers 324. In some embodiments, the particulate filter 320 is configured to remove particulate matter and undesired gas by the interaction of exhaust with the catalyst on the ceramic / glass fiber. In some embodiments, the particulate filter 320 may include catalyst within, onto the surface, and / or attach to woven and / or non-woven ceramic and / or glass fiber 324.

[0025] In some embodiments, the particulate filter 320 may include any of the layers of the embodiments of the catalytic filter 100 previously described. In some embodiments, the particulate filter 320 may comprise, support, or otherwise carry one or more catalysts capable of832684305.1Patent Attorney Docket No. 3227942WO01 catalyzing a reaction within a target exhaust gas. Tn some embodiments, the particulate filter 320 is uncatalyzed.

[0026] The embodiments of the catalytic filter 100 and catalytic bag filters 200, 300 disclosed use a catalytic filter media 322 comprised of ceramic and / or glass, which enable operation at higher temperatures than prior art filters. Moreover, unlike currently used catalytic fluoropolymer film, the catalytic filter media 322 provides a more favorable geometry for catalyst to be deposited and results in higher catalyst dispersion and / or layering. The overall result is a better utilization of the catalyst, which may increase the overall efficiency of the catalytic filter 100, 210, 310 and / or bag filter 200, 300. Some embodiments of the bag filter 200, 300 described herein are a multifunctional product and may be used to remove particulates and gases that are harmful to the environment. The combined action of embodiments of the bag filter 200, 300 may obviate the need for additional processes and their associated costs while achieving the same effect. Some embodiments of the bag filter 200, 300 of the present disclosure may be used in a variety of applications such as waste treatment, energy production facilities, chemical processing facilities, lime and cement processing facilities, and / or metal processing facilities.

[0027] Embodiments of a method 400 of manufacturing a catalytic filter will now be discussed with reference to FIG. 6. In some embodiments, a ceramic fiber paper layer 110 is formed from a woven fabric and / or an un-woven fabric at step 402. In some embodiments, needle punch refractory ceramic fibers / low biopersistent (NP RCF / LBP) non-woven fibers are bonded to or impregnated with a scrim. In some embodiments, the scrim comprises a polytetrafluoroethylene (PTFE) yarn. In some embodiments, the ceramic fiber paper layer 110 goes through a catalyzation process at step 404. In some embodiments, the ceramic paper layer is laminated to the at least one support layer to form a laminated material or laminated structure, for example the catalytic filter, at step 406. In some embodiments, the laminate or laminated structure is heat treated at step 408. In some embodiments, the catalyzation process may be performed prior to formation of the laminated structure or after said formation (i.e., before step 406 or after step 406). In some embodiment, the method stops at step 410.

[0028] In some embodiments, the method may include one or more additional processing steps. In some embodiments, the one or more processing steps may include a further lamination process with a felt composite or other material. In some embodiments, the one or more additional processing steps may be associated with forming the catalytic filter into a catalytic bag filter such932684305.1Patent Attorney Docket No. 3227942WO01 as previously described. In some embodiments, the one or more additional processing stems may include additional catalyzation and / or treatment with additives.

[0029] Although various embodiments have been shown and described, the disclosure is not limited to such embodiments and will be understood to include all modifications and variations as would be apparent to one of ordinary skill in the art. Therefore, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed; rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.1032684305.1

Claims

Patent Attorney Docket No. 3227942WO01CLAIMS1. A catalytic filter comprising: a ceramic paper layer comprised of ceramic fibers; at least one support layer laminated to the ceramic paper layer; and at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer and the at least one support layer.

2. The catalytic filter of claim 1, wherein the ceramic paper layer comprises woven ceramic fibers.

3. The catalytic filter of claim 1 , wherein the ceramic paper layer comprises non-woven ceramic fibers.

4. The catalytic filter of claim 1, wherein the at least one catalyst is comprised of one of: (i) V2O3; (ii) Fe2Ch and (iii) Pt.

5. The catalytic filter of claim 1, wherein the ceramic paper layer comprises one or more additives to improve catalytic activity.

6. The catalytic filter of claim 5, wherein the one or more additives include at least one of: (i) TiCh; and (ii) zeolites ; and (ii) a zeolite.

7. The catalytic filter of claim 1 , further comprising at least two support layers laminated to the ceramic paper layer, wherein the ceramic paper layer is positioned between the at least two support layers.

8. A catalytic bag filter comprising: a body extending from a first end to a second end, the body comprising, a catalytic filter comprising, a ceramic paper layer comprised of ceramic fibers,1132684305.1Patent Attorney Docket No. 3227942WO01 at least one support layer laminated to the ceramic paper layer, and at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer and the at least one support layer, and a particulate fdter coupled to the catalytic fdter at the first end of the body, wherein a filter interior is delimited by the catalytic filter and the particulate filter.

9. The catalytic bag filter of claim 8, wherein the ceramic paper layer comprises woven ceramic fibers.

10. The catalytic bag filter of claim 8, wherein the ceramic paper layer comprises nonwoven ceramic fibers.

11. The catalytic bag filter of claim 8, wherein the catalytic filter is positioned upstream of the particulate filter.

12. The catalytic bag filter of claim 8, wherein the at least one catalyst is comprised of one of: (i) V2O3; (ii) Fe2Ch and (iii) Pt.

13. The catalytic bag filter of claim 8, wherein the particulate filter is closed at the second end of the filter body.

14. The catalytic bag filter of claim 8, further comprising at least two support layers laminated to the ceramic paper layer.

15. The catalytic bag filter of claim 8, further comprising a supporting structure configured to support at least one of: (i) the catalytic filter; and (ii) the particulate filter.

16. The catalytic bag filter of claim 8, wherein the particulate filter comprises at least one catalyst capable of catalyzing a reaction within a gas passing through the particulate filter to the filter interior.1232684305.1Patent Attorney Docket No. 3227942WO0117. A method of manufacturing a catalytic filter, comprising: forming a ceramic paper layer comprised of ceramic fibers; catalyzing the ceramic paper layer with at least one catalyst capable of catalyzing a reaction within a gas passing through the ceramic paper layer; laminating the ceramic paper layer and at least one support layer to form a laminated material; and heat treating the laminated material.

18. The method of claim 17, wherein the at least one catalyst is comprised of one of: (i) V2O3; (ii) Fe2C>3 and (iii) Pt.

19. The method of claim 17, wherein the ceramic paper layer is comprised of woven ceramic fibers.

20. The method of claim 17, wherein the ceramic paper layer is comprised of non-woven ceramic fibers.1332684305.1

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