A method for preparing a high-loading functional filter material and a functional filter material

Abstract

A method for preparing high-loading functionalized filter media and the functionalized filter media are disclosed. The preparation method includes the following steps: S1, adding a catalyst, a polymer dispersant, and a pore-forming agent to deionized water and stirring thoroughly to obtain a precursor solution; S2, drying the precursor solution at 60℃-160℃ for 1h-12h to obtain a precursor; rolling the precursor under a pressure of 0.1MPa-10MPa to obtain a functional layer, and cutting it into a certain shape; placing non-woven fabric on the upper and lower surfaces of the functional layer and sewing the three together to form a sandwiched filter media; baking the sandwiched filter media for 2h-8h to remove the pore-forming agent, thus preparing the functionalized filter media. Therefore, the functionalized filter media prepared by this invention can greatly increase the loading capacity of inorganic functional materials, effectively reduce the reaction space velocity, and improve the removal rate of gaseous pollutants.

Description

Technical Field

[0001] This invention relates to the technical field of catalytic filter media, and in particular to a method for preparing high-loading functionalized filter media and the functionalized filter media itself. Background Technology

[0002] Industrial flue gas treatment systems often involve particulate matter and various gaseous pollutants. Particulate matter is mainly filtered using bag filters, while pollutants such as nitrogen oxides, volatile organic compounds, carbon monoxide, and dioxins are generally removed using specialized reactors. Catalytic filter media can achieve integrated removal of particulate matter and gaseous pollutants, reducing equipment investment and operating costs.

[0003] The main factors affecting the catalytic conversion efficiency of these gaseous pollutants include catalyst specific activity, reaction space velocity, and reaction temperature. With a fixed catalyst specific activity, increasing the flue gas reaction temperature requires significant energy consumption and increased investment in heat exchange equipment. Traditional catalytic filter media, such as the composite filter media with synergistic removal of nitrogen oxides and dioxins disclosed in Chinese patent CN110898829B, and the catalytic composite filter media with low-temperature denitrification function disclosed in Chinese patent CN118105776B, are generally produced by direct impregnation or surface coating on non-woven fabrics. The functional layer is prone to detachment, and the loading capacity is very limited, restricting the catalyst loading per unit area, resulting in a high reaction space velocity and low pollutant removal rate. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing functionalized filter media with high loading capacity and functionalized filter media, which can load inorganic functional materials with a large mass and has the advantage of efficiently removing gaseous pollutants.

[0005] To achieve the above objectives, the solution of the present invention is: A method for preparing high-loading functionalized filter media includes the following steps: S1. Prepare the precursor solution for the functional layer; Add the catalyst, polymer dispersant and pore-forming agent to deionized water and stir for 10 min-30 min to obtain the precursor solution; The precursor solution contains the following components by mass: 1 part catalyst, 0.01-1.5 parts polymer dispersant, 0.05-1.5 parts pore-forming agent, and 0.2-1.0 parts deionized water. S2, Dry the precursor solution; The precursor solution prepared in step S1 is dried at 60℃-160℃ for 1h-12h to obtain the precursor. S3, Molding Functional Layer; The precursor obtained in step S2 is roll-formed under a pressure of 0.1 MPa-10 MPa to obtain a functional layer with a thickness of 0.2 mm-6 mm, and then cut into a certain shape. S4, sandwich filter media; Non-woven fabrics are placed on the top and bottom of the functional layer obtained in step S3, and the three are sewn together to form a sandwich filter material. S5. Prepare functionalized filter media; The sandwiched filter material obtained in step S4 is baked for 2-8 hours to remove the pore-forming agent, thus preparing the functionalized filter material.

[0006] Furthermore, the catalyst is a denitrification catalyst or a CO oxidation catalyst; the denitrification catalyst is a vanadium-tungsten-titanium catalyst or a vanadium-molybdenum-titanium catalyst.

[0007] Furthermore, the polymer dispersion is a polytetrafluoroethylene dispersion, a polyimide dispersion, or a polyvinylidene fluoride dispersion, and has a solid content of 40-60 wt%.

[0008] Furthermore, the pore-forming agent is oxalic acid, urea, or ammonium bicarbonate.

[0009] Furthermore, the nonwoven fabric is a polymer nonwoven fabric or a glass fiber nonwoven fabric; the polymer nonwoven fabric is made of polyphenylene sulfide nonwoven fabric, polyimide nonwoven fabric or polytetrafluoroethylene nonwoven fabric.

[0010] Furthermore, the catalyst loading per unit filter area of ​​the functionalized filter media is 120 g / m². 2 -3600 g / m 2 .

[0011] Furthermore, in step S3, a roll forming machine is used for roll forming, with a roller spacing of 0.2 mm to 6.0 mm.

[0012] Furthermore, in step S4, two pieces of nonwoven fabric with the same shape as the functional layer obtained in step S3 are cut and obtained. The two pieces of nonwoven fabric are sandwiched between the functional layer from top to bottom and sewn to fix the shape, thereby obtaining the sandwich filter material.

[0013] Furthermore, in step S4, the functional layer obtained in step S3 is laid flat on the nonwoven fabric used as the base fabric, and another layer of nonwoven fabric is spun on the base fabric and the functional layer using a needle punching process to obtain a sandwich filter material.

[0014] The present invention also provides a high-loading functionalized filter material, which is prepared by the preparation method shown.

[0015] By adopting the above technical solution, this invention uses a polymer to impregnate, dry, and roll-press inorganic functional materials. The bonding of the functional layers is achieved through the intermolecular force of the polymer organic molecules. Then, a needle-punching process is used to lock the functional layers between the nonwoven fabrics. The resulting functionalized filter material can significantly increase the loading capacity of the inorganic functional materials. This ultra-high loading capacity effectively reduces the reaction space velocity and improves the removal rate of gaseous pollutants. In contrast, traditional processes typically use direct impregnation or surface coating on nonwoven fabrics, which easily result in the functional layer detaching and has a very limited loading capacity.

[0016] Meanwhile, the high-load functionalized filter material of the present invention can be adapted to a variety of inorganic functionalized materials, including but not limited to denitrification catalysts, and can cope with the working conditions of low-temperature flue gas, that is, it is suitable for various complex working conditions; while traditional denitrification filter materials can only be used for denitrification, and have high requirements for flue gas temperature and low process operability. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the functionalized filter media layer structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the evaluation of functionalized filter media using a tubular reaction device, as an embodiment of the present invention.

[0018] Labeling Explanation: Functionalized Filter Media 10, Non-woven Fabric Layer 11, Functional Layer 12, Testing Device 20, Gas Cylinder 21, One-way Valve 22, Mass Flow Meter 23, Shut-off Valve 24, Tubular Furnace 25, Tubular Reactor 26, Flue Gas Analyzer 27, Tail Gas Treatment Device 28. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] like Figure 1 As shown, a method for preparing a high-loading functionalized filter material according to the present invention includes the following steps: S1. Prepare the precursor solution for the functional layer; Add the catalyst, polymer dispersant and pore-forming agent to deionized water and stir thoroughly for 10-30 minutes to obtain the precursor solution. The precursor solution contains the following components by mass: 1 part catalyst, 0.01-1.5 parts polymer dispersant, 0.05-1.5 parts pore-forming agent, and 0.2-1 parts deionized water. The catalyst may be a denitrification catalyst or a CO oxidation catalyst; the denitrification catalyst includes vanadium-tungsten-titanium catalysts.

[0021] The polymer dispersion may be a polytetrafluoroethylene dispersion, a polyimide dispersion, or a polyvinylidene fluoride dispersion, etc., and the solid content is 40-60 wt%.

[0022] The pore-forming agent may be oxalic acid, urea, or ammonium bicarbonate, etc.

[0023] S2, Dry the precursor solution; The precursor solution prepared in step S1 is placed in an oven and dried at 60℃-160℃ for 1h-12h to obtain the precursor. S3, Molding Functional Layer; The precursor obtained in step S2 is roll-formed using a roll press with a roller spacing of 0.2mm-6.0mm and a pressure of 0.1MPa-10MPa to obtain a functional layer with a thickness of 0.2mm-6.0mm, which is then cut into a certain shape. S4, sandwich filter media; Non-woven fabrics are placed on the top and bottom of the functional layer obtained in step S3, and the three are sewn together to form a sandwich filter material. Specifically, two pieces of nonwoven fabric with the same shape as the functional layer obtained in step S3 can be cut and obtained. The two pieces of nonwoven fabric are sandwiched between the functional layer from top to bottom and sewn to fix the shape, thus obtaining the sandwiched filter material. Alternatively, the functional layer obtained in step S3 can be laid flat on the nonwoven fabric used as the base fabric, and another layer of nonwoven fabric can be spun on the base fabric and the functional layer using a needle punching process to obtain a sandwich filter material.

[0024] The nonwoven fabric may be a polymer nonwoven fabric or a glass fiber nonwoven fabric; the polymer nonwoven fabric may be a polyphenylene sulfide nonwoven fabric, a polyimide nonwoven fabric, or a polytetrafluoroethylene nonwoven fabric.

[0025] S5. Prepare functionalized filter media; The sandwiched filter material obtained in step S4 is placed in an oven and baked for 2-8 hours to remove the pore-forming agent, thus preparing the functionalized filter material.

[0026] The above preparation method can be used to prepare functionalized filter media 10 with ultra-high loading capacity (see above). Figure 2 The filter media comprises upper and lower nonwoven fabric layers 11 and a middle functional layer 12, wherein the catalyst loading per unit filter area is 120 g / m². 2 -3600 g / m2 .

[0027] Example 1 20 g of vanadium-tungsten-titanium catalyst powder was dispersed in 100 mL of deionized water, and 3 g of polytetrafluoroethylene dispersion and 3 g of urea were added. The mixture was stirred thoroughly to obtain a precursor solution. The precursor solution was preliminarily dried in an oven at 140℃ for 4 h to obtain the precursor. The obtained precursor was roll-pressed to a thickness of 5 mm and cut into circular functional layers (diameter 8.7 cm, area 59.4 cm²). 2 The functional layer is sandwiched between two layers of polytetrafluoroethylene nonwoven fabric and fixed by needle punching to obtain sandwiched filter material; the obtained sandwiched filter material is placed in an oven and treated at 200℃ for 3 h to finally obtain filter material with denitrification function.

[0028] The denitrification performance of the denitrification functionalized filter media prepared in Example 1 was evaluated in a self-made tubular reaction apparatus, as shown in the test apparatus 20. Figure 3 As shown, the testing device 20 includes a gas cylinder 21, a one-way valve 22, a mass flow meter 23, a shut-off valve 24, a tubular heater 25, a tubular reactor 26 (including temperature control equipment such as thermocouples), a flue gas analyzer 27, and a tail gas treatment device 28, etc.

[0029] The denitrification functionalized filter media 10 is placed inside the tubular reactor 26.

[0030] Test conditions: The test gas entering tubular reactor 26 contains 500 ppm of NO and NH3, 5% of O2 by volume, and the remainder is N2. The gas flow rate is 400 mL / min.

[0031] Test procedure: After the airflow stabilizes for 30 minutes, the concentration of nitrogen oxides at the inlet and outlet is measured using a Laoying 3012H-D portable flue gas analyzer to calculate the denitrification rate of the functionalized filter media.

[0032] Test results: When the reaction temperature is set to 120℃, the denitrification rate of the functionalized filter media containing a 5 mm functional layer is 92%.

[0033] Example 2 The denitrification catalyst can be replaced with a CO oxidation catalyst, preferably one with a composition of CoO. x / C, i.e., carbon-supported cobalt oxide catalyst, with the rest remaining unchanged, repeat the preparation process of Example 1 to prepare CO oxidation functionalized filter media.

[0034] The prepared CO oxidation functionalized filter media was also evaluated using the tubular reactor 26 of Example 1.

[0035] Test conditions: The test gas entering tubular reactor 26 has a CO volume fraction of 2000 ppm, an O2 volume fraction of 1%, and the remainder is N2. The gas flow rate is 400 mL / min.

[0036] Test procedure: After the airflow stabilizes for more than 30 minutes, the concentration of CO at the inlet and outlet is measured using a Laoying 3012H-D portable flue gas analyzer 27 to calculate the catalytic conversion rate of CO.

[0037] Test results: When the reaction temperature is set to 90℃, the CO removal rate of the CO oxidation functional filter material with a 5 mm catalyst layer is 96%.

[0038] Furthermore, the dust removal efficiency of the ultra-high loading functionalized filter media prepared in Examples 1 and 2 above is above 99.99%.

[0039] In summary, the present invention has the following advantages: Structurally: This invention uses a polymer to impregnate and dry an inorganic functional material, and roll-forms it. The cohesion between the polymer molecules is used to bond the functional layer, and then a needle punching process is used to lock the functional layer between the non-woven fabrics, which can greatly improve the loading capacity of the inorganic functional material. In contrast, traditional processes generally use direct impregnation or surface coating on non-woven fabrics, which makes the functional layer easy to fall off and the loading capacity is very limited.

[0040] Functionally, the high-load functionalized filter media of this invention can be adapted to a variety of inorganic functionalized materials, including but not limited to denitrification catalysts, and can cope with low-temperature flue gas conditions, that is, it is suitable for various complex conditions; while traditional denitrification filter media can only be used for denitrification, and has high requirements for flue gas temperature and low process operability.

[0041] Since the bonding force between organic and inorganic materials is often very weak, the preparation method of this invention uses a polymer dispersion to assemble inorganic functional materials with organic filter materials. This not only preserves the functional characteristics of inorganic materials and enables them to be successfully shaped, but also solves the contradiction between loose powder that is easy to shed and dense under pressure that is not easy to breathe (firmness and breathability). The beneficial effects are significant and outstanding.

[0042] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, equivalent changes and modifications without departing from the principle of the present invention should still fall within the scope of protection of the present invention.

[0043] In the description of the embodiments of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] The foregoing disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described above. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0045] Furthermore, this application provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

Claims

1. A method for preparing a high-loading functionalized filter material, characterized in that, Includes the following steps: S1. Prepare the precursor solution for the functional layer; Add the catalyst, polymer dispersant and pore-forming agent to deionized water and stir for 10 min-30 min to obtain the precursor solution; The precursor solution contains the following components by mass: 1 part catalyst, 0.01-1.5 parts polymer dispersant, 0.05-1.5 parts pore-forming agent, and 0.2-1.0 parts deionized water. S2, Dry the precursor solution; The precursor solution prepared in step S1 is dried at 60℃-160℃ for 1h-12h to obtain the precursor. S3, Molding Functional Layer; The precursor obtained in step S2 is roll-formed under a pressure of 0.1 MPa-10 MPa to obtain a functional layer with a thickness of 0.2 mm-6 mm, and then cut into a certain shape. S4, sandwich filter media; Non-woven fabrics are placed on the top and bottom of the functional layer obtained in step S3, and the three are sewn together to form a sandwich filter material. S5. Prepare functionalized filter media; The sandwiched filter material obtained in step S4 is baked for 2-8 hours to remove the pore-forming agent, thus preparing the functionalized filter material.

2. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: The catalyst is a denitrification catalyst or a CO oxidation catalyst; the denitrification catalyst is a vanadium-tungsten-titanium catalyst or a vanadium-molybdenum-titanium catalyst.

3. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: The polymer dispersion is a polytetrafluoroethylene dispersion, a polyimide dispersion, or a polyvinylidene fluoride dispersion, and has a solid content of 40-60 wt%.

4. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: The pore-forming agent is oxalic acid, urea, or ammonium bicarbonate.

5. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: The nonwoven fabric is a polymer nonwoven fabric or a glass fiber nonwoven fabric; the polymer nonwoven fabric is made of polyphenylene sulfide nonwoven fabric, polyimide nonwoven fabric or polytetrafluoroethylene nonwoven fabric.

6. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: The catalyst loading per unit filter area of ​​the functionalized filter media is 120 g / m². 2 -3600 g / m 2 .

7. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: Step S3 involves roll forming using a roller press with a roller spacing of 0.2 mm to 6.0 mm.

8. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: In step S4, two pieces of nonwoven fabric with the same shape as the functional layer obtained in step S3 are cut and obtained. The two pieces of nonwoven fabric are sandwiched between the functional layer from top to bottom and sewn to fix the shape, thereby obtaining the sandwich filter material.

9. The method for preparing a high-loading functionalized filter material according to claim 1, characterized in that: In step S4, the functional layer obtained in step S3 is laid flat on the nonwoven fabric used as the base fabric, and another layer of nonwoven fabric is spun on the base fabric and the functional layer using a needle punching process to obtain a sandwich filter material.

10. A high-loading functionalized filter media, characterized in that: It is prepared by any one of the preparation methods described in claims 1-9.

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