Catalytic fibers and their uses

Abstract

Described herein are catalytic fibers, and in particular catalytic fibers that exhibit properties and structures that can be used to provide catalytic fabrics that exhibit low pressure drop. In some embodiments, the catalytic fibers comprise a fibrous body that includes one or more grooves along a surface of the fibrous body, and a catalytic material present within the one or more grooves.

Description

[Technical field]

[0001] The present invention relates to catalytically active fibrous structures, and in particular to catalytically active fibers and fabrics that can be used for the selective catalytic reduction of nitrogen oxides.

[0002] This application claims priority pursuant to Article 8 of the Patent Cooperation Treaty to U.S. Provisional Patent Application No. 63 / 306,678, filed February 4, 2022, which is incorporated by reference in its entirety herein. [Background technology]

[0003] Denitrification or selective catalytic reduction (SCR) technology is commonly applied to combustion-derived flue gases to remove nitrogen oxides when passed through a catalytic reactor. Denitrification consists of the reaction of nitrogen oxide species in the gas, such as nitrogen oxide (NO) or nitrogen dioxide (NO2), with a nitrogen-containing reductant, such as ammonia or urea, resulting in the production of diatomic nitrogen (N2) and water. In addition, various absorption or capture techniques are used to remove other species of the flue gas that are not catalytically decomposed. Summary of the Invention [Problem to be solved by the invention]

[0004] In many cases, the exhaust gas stream passing through the modular sections of the catalytic reactor and other downstream equipment such as the baghouse experiences a pressure drop. The pressure drop can be caused by structures, frictional forces, and other factors that impede or block the flow of the exhaust gas stream. The pressure drop can result in various inefficiencies and can cause parasitic power losses during industrial applications such as power generation. [Means for solving the problem]

[0005] In view of these shortcomings, catalytic fibers are described herein that exhibit properties and structures that can be used to provide catalytic fabrics that exhibit low pressure drop. In some embodiments, the catalytic fibers include a fibrous body that includes one or more grooves along a surface of the fibrous body, and a catalytic material present within the one or more grooves. The one or more grooves, in some embodiments, extend along a longitudinal axis of the fibrous body. When extending along the longitudinal axis, the grooves can define lobes between the grooves, the lobes extending radially outward from the fiber center. Alternatively, the one or more grooves can extend along the periphery of the fibrous body. When extending around the fiber periphery, the grooves can define sections of the fiber. In some embodiments, the grooves extend in a spiral manner along the longitudinal axis of the fibrous body.

[0006] The grooves in the fibrous body can have any desired cross-sectional shape. In some embodiments, the grooves have a curved cross-sectional shape. In other embodiments, the grooves have a polygonal or curvilinear cross-sectional shape. The grooves of a fiber can all have the same cross-sectional shape, or the cross-sectional shapes can vary depending on the radial and / or longitudinal location of the groove on the fibrous body.

[0007] In another aspect, a catalytically active fabric is provided. The catalytically active fabric comprises the catalytic fibers described above, the catalytic fibers comprising one or more grooves along a surface of the fibrous body, and a catalytic material present within the one or more grooves. In some embodiments, the fabric is a nonwoven assembly of the catalytic fibers. The nonwoven fabric can be formed by several techniques, including needle punching or the use of a binder. In other embodiments, the fabric can be a woven assembly of the catalytic fibers.

[0008] These and other embodiments are further described in the detailed description that follows. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The embodiments described herein can be more readily understood by reference to the following detailed description and examples, as well as the descriptions preceding and following them. However, the elements, devices, and methods described herein are not limited to the specific embodiments shown in the detailed description and examples. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Many modifications and adaptations will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.

[0010] I. Catalytic Fiber In one aspect, the catalytic fiber includes a fibrous body including one or more grooves (channels) along the surface of the fibrous body, and catalytic material present within the one or more grooves. The one or more grooves extend along the longitudinal axis of the fibrous body in some embodiments. When extending along the longitudinal axis, the grooves can define lobes between the grooves, the lobes extending radially outward from the fiber center. The catalytic fibers described herein can include any desired number of grooves and lobes. In some embodiments, the grooves and associated lobes are rotationally symmetric. For example, the grooves can exhibit the same or substantially the same radial spacing, such as 120 degrees, from one another. In such embodiments, the lobes exhibit the same or substantially the same radial spacing of 120 degrees. The radial spacing of the grooves and lobes can depend on several considerations, including the number of grooves, the geometry of the grooves, and the geometry of the lobes. In other embodiments, the radial spacing of the lobes and / or the grooves is irregular or asymmetric.

[0011] The fibrous body can be formed from any material not inconsistent with the technical objectives described herein, including use in SCR applications. In some embodiments, the fibrous body is formed from glass. In other embodiments, the fibrous body is formed from polymeric materials, including homopolymers and copolymers. The polymeric materials can exhibit thermal stability at temperatures ranging from 120° C. to 350° C. in some embodiments. The polymeric material can be, for example, a polyimide. In some embodiments, the polymeric material is polyetherketone (PEK) or polyetheretherketone (PEEK). The polymeric material can also be selected from the group consisting of polyester, polyamide, polyphenylene sulfide, polyacrylic, polypropylene, polycarbonate, and polyfluoroethylene fibers.

[0012] In some embodiments, the fibrous body is formed from a single polymeric or copolymeric material. Alternatively, the fibrous body can be formed from two or more polymeric / copolymeric materials. In some embodiments, for example, the fibrous body exhibits a core / shell structure. The core can be formed from a polymeric or copolymeric material that provides desirable mechanical properties, and the shell is formed from a polymeric or copolymeric material that exhibits a compatible interaction with the particulate catalyst material present in the fiber grooves. In further embodiments, the fibrous body can be hollow, such as hollow polyimide fibers.

[0013] The fibrous body can have any diameter consistent with the technical objectives described herein, including the formation of a catalytic fabric with low pressure drop. In some embodiments, the fibrous body has a maximum diameter of 10 μm to 2 mm. The maximum diameter of the fibrous body is measured from protrusion to protrusion in some embodiments. The diameter of the fibrous body is, in some embodiments, 100 μm to 1 mm or 250 μm to 1 mm. In some embodiments, the maximum diameter of the fibrous body is greater than 2 mm.

[0014] As described herein, the catalytic material is present within the grooves. In some embodiments, at least 5 percent of the groove volume or at least 10 percent of the groove volume is filled with the catalytic material. The groove volume filled with the catalytic material may also have a value selected from Table I.

[0015] [Table 1]

[0016] The grooves in the fiber body can have any desired cross-sectional shape. In some embodiments, the grooves have a curved cross-sectional shape, such as semicircular, elliptical, or parabolic. Alternatively, the cross-sectional shape of the grooves can be polygonal, such as square, rectangular, or hexagonal. In further embodiments, the cross-sectional shape of the grooves can be curvilinear.

[0017] Any catalytic material consistent with the technical objectives described herein may be disposed within the fiber groove. In some embodiments, the catalyst may be used for selective catalytic reduction of nitrogen oxides, destruction of dioxins, furans and / or volatile organic compounds (VOCs), and oxidation of carbon monoxide (CO). The catalytic material may include one or more platinum group metals (PGMs), including, for example, gold, platinum, iridium, palladium, osmium, rhodium, rhenium, ruthenium, vanadium pentoxide (VO), tungsten oxide (WO), molybdenum oxide (MoO) or other precious metals or mixtures / alloys thereof. In some embodiments, the catalytic material is vanadium tungsten titanium alloy (VW-Ti). The catalytic material may exhibit particulate morphology. In some embodiments, particles of any of the aforementioned catalytic metals, alloys or metal oxides are used. Furthermore, in some embodiments, the particles include an inorganic oxide support and a catalytically active metal functional group. The inorganic oxide support may include, but is not limited to, titania (TiO2), alumina (Al2O3), zirconia (ZrO2), and / or mixtures thereof. Additionally, in some embodiments, the catalytically active metal functional group may include, but is not limited to, gold, platinum, iridium, palladium, osmium, rhodium, rhenium, ruthenium, vanadium pentoxide (VO5), tungsten oxide (WO3), molybdenum oxide (MoO3), or other precious metals or mixtures thereof. In some embodiments, the catalytic material includes one or more zeolites incorporating one or more catalytic metals or alloys, such as zeolite-supported PGM. For example, the catalytic material may include copper zeolites, including Cu-SSZ-13.

[0018] As mentioned above, the catalytic material can be particulate in nature, such that in some embodiments the catalytic material does not form a chemical interaction with the fibers, but is retained by mechanical engagement within the fiber grooves and interstitial spaces of the fibers as described below.

[0019] II. Catalytic Fabric In another aspect, catalytically active fabrics are described herein. The catalytically active fabrics include the catalytic fibers described in Section I above. In some embodiments, the fabrics are nonwoven assemblies of catalytic fibers. The nonwoven fabrics can be formed by several techniques, including needle punching or the use of binders. In other embodiments, the fabrics can be woven assemblies of catalytic fibers.

[0020] Advantageously, the catalytically active fabric exhibits a desired porosity while maintaining effective catalytic activity. The desired porosity can aid in maintaining a low pressure drop across or through the fabric. In some embodiments, the catalytic fabric exhibits a porosity of at least 40% by volume. In some embodiments, the porosity of the catalytic fabric has a value selected from Table II.

[0021] [Table 2]

[0022] The porosity of the catalytic fabric may depend on several considerations, including the woven or nonwoven structure of the fabric, the catalyst loading of the fabric, the layering of the fabric, and / or the initial porosity of the fabric in a non-catalyzed state. As described further herein, the catalytic fabric may be made directly from the catalytic fibers described in Section I, or catalytic material may be added to the non-catalyzed fabric, thereby providing catalytic material within the grooves of the fibers.

[0023] The catalytic fabric can have any desired catalyst loading. In some embodiments, the catalytic material is present in the fabric in an amount of 40 to 80 weight percent of the catalytic fabric. The catalytic material may be present in an amount of 50 to 75 weight percent of the catalytic fabric. As described herein, the catalytic material is present in the grooves of the fibrous body. Additionally, in some embodiments, the catalytic material is also present in the interstitial spaces between the fibers. Advantageously, the catalytic fabric can exhibit a porosity as described herein, including a porosity selected from Table II, with the catalytic material present in the fiber grooves and interstitial spaces of the fibers. In some embodiments, the catalytic fabric having the composition and properties described herein can extract more than 50 percent or more than 60 percent NO from a gas stream passing through the fabric. x Additionally, the catalytic material of the fabric may be stable to various cleaning processes, such as backflushing or other methods of removing particulate contaminants from the fabric. For example, the catalytic fabric may exhibit greater than 50 percent NOx removal after at least 5 or 10 cleaning cycles. x Efficiency can be maintained.

[0024] The fabrics described herein can be used in a variety of applications, including baghouse applications associated with power plants and other industrial filtration / gas processing operations.

[0025] These and other embodiments are further described in the following non-limiting examples.

[0026] Example 1 - Catalytic Fabric High temperature (HT) polyimide fibers with a multi-groove / multi-lobe cross section, commercially available under the trade name P84® from Evonik Fibres GmbH, Schoerfling, Austria, were processed into a nonwoven filter bag structure. An aqueous slurry of VW / Ti catalytic material was prepared. A nonwoven filter bag was contacted with the slurry and mechanically pressed to impart the VW / Ti catalytic material to the polyimide fibers. The coated fibers were mechanically pressed to deposit the VW / Ti catalytic material in the grooves of the polyimide fibers and in the interstitial spaces of the nonwoven. The slurry was applied and subsequently mechanically pressed to impart until a loading of 40-45 wt.% catalytic material was achieved. The catalytic nonwoven filter bag was then dried and de-dusted.

[0027] Example 2 - Selective catalytic reduction with catalytic fabric The catalytic nonwoven filter bag of Example 1 was used for the NOx removal test shown in Table III. x I put it to the test.

[0028] [Table 3]

[0029] As shown in Table III, the catalyzed nonwoven filter bag significantly reduced nitrogen oxides in the gas stream under a variety of conditions. Various embodiments of the present invention have been described to accomplish the various objectives of the present invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Many modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A catalytic fiber comprising: a fibrous body including one or more grooves along a surface of the fibrous body; a catalytic material present within the one or more grooves; A catalytic fiber comprising:

2. The catalyst fiber of claim 1 , wherein the one or more grooves extend along a longitudinal axis of the fibrous body.

3. The catalyst fiber of claim 2 comprising a plurality of grooves defining protrusions between said grooves.

4. The catalyst fiber of claim 1 , wherein the one or more grooves extend along a periphery of the fibrous body.

5. The catalyst fiber of claim 1 , wherein the one or more grooves have a curved cross-sectional shape.

6. The catalyst fiber of claim 1 , wherein the one or more grooves have a polygonal cross-sectional shape.

7. The catalyst fiber of claim 1 , wherein the one or more grooves have a curved cross-sectional shape.

8. The catalyst fiber of claim 1 , wherein the catalytic material fills at least 5 percent of the groove volume.

9. The catalyst fiber of claim 1 , wherein the catalytic material fills at least 50 percent of the groove volume.

10. The catalyst fiber of claim 1 , wherein the one or more grooves extend helically along a longitudinal axis of the fibrous body.

11. The catalytic fiber of claim 1 , wherein the catalytic material is operable for the selective catalytic reduction of nitrogen oxides.

12. The catalytic material may be selected from the group consisting of gold, platinum, iridium, palladium, osmium, rhodium, rhenium, ruthenium, vanadium pentoxide (V 2 O 5 ), tungsten oxide (WO 3 ), or molybdenum oxide (MoO 3 10. The catalyst fiber of claim 1, comprising one or more of the following:

13. The catalyst fiber of claim 1 , wherein the fibrous body is formed from glass.

14. The catalyst fiber of claim 1 , wherein the fibrous body is formed from a polymeric material.

15. 15. The catalytic fiber of claim 14, wherein the polymeric material exhibits thermal stability at temperatures above 200°C or 250°C.

16. 15. The catalytic fiber of claim 14, wherein the polymeric material exhibits thermal stability at temperatures from 120°C to 350°C.

17. The catalyst fiber of claim 14 , wherein the polymeric material is a polyimide.

18. 15. The catalytic fiber of claim 14, wherein the polymer material is polyetherketone (PEK) or polyetheretherketone (PEEK).

19. The catalyst fiber of claim 1 , wherein the catalytic material is in particulate form.

20. 1. A catalytically active fabric comprising: A catalytic fiber comprising a fibrous body including one or more grooves along a surface of the fibrous body, and a catalytic material present within the one or more grooves. A catalytically active fabric comprising:

21. 21. The catalytically active fabric of claim 20, wherein the catalytic fibers are non-woven.

22. 21. The catalytically active fabric of claim 20, wherein the catalytic fibers are woven.

23. 21. The catalytically active fabric of claim 20, wherein the catalytic material is also present in interstitial spaces defined by the catalytic fibers of the fabric.

24. 24. The catalytically active fabric of claim 23, wherein the catalytic material is present in an amount of from 40 percent to 80 percent by weight of the fabric.

25. 25. The catalytically active fabric of claim 24 having a porosity of 40 to 80 volume percent.

26. 21. The catalytically active fabric of claim 20, wherein the fabric has a bag structure.

27. At least 50 percent denitrification x 27. The catalytically active fabric of claim 26 having an efficiency.

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