Preparation method of dedusting and denitration composite filter material

Abstract

The invention provides a preparation method of a dedusting and denitration composite filter layer, and belongs to the technical field of environment-friendly catalysis. The preparation method of the dedusting and denitration filter layer comprises the following steps: uniformly mixing polytetrafluoroethylene and a chitosan solution, then adding a catalyst, a foaming agent and a surfactant into the mixed solution, stirring and foaming, coating a filter base material with a foamed emulsion, and carrying out heat setting treatment to form the dedusting and denitration composite filter layer. The preparation process is simple and efficient, industrial production is easy to achieve, the obtained dust removal and denitration composite filter layer is high in bonding fastness, the efficient dust removal performance is kept, meanwhile, the environmental protection function of catalytic denitration is achieved, the complexity of the system is reduced through the integrated design, the cost is reduced, and meanwhile the operation efficiency of the system is improved.

Description

Technical Field

[0001] The invention provides a method for preparing a dust removal and denitration composite filter material, and belongs to the technical field of environmental protection filtration. Background Art

[0002] With the acceleration of industrialization, air pollution has become a global environmental problem, posing serious challenges to human health and ecosystems. Dust and nitrogen oxides (NOx) are the main pollutants in the atmosphere, which not only significantly reduce air quality, but also may cause a variety of health problems including respiratory diseases. What's more, NOx emissions are closely related to environmental problems such as acid rain and photochemical smog, which further aggravates the threat to human health and ecosystems. In the field of industrial flue gas purification, especially the treatment of nitrogen oxides and dust generated in industrial processes such as coal-fired power plants, cement plants, and steel plants, it is particularly important. The global awareness of environmental protection is constantly improving, environmental protection regulations are becoming more and more stringent, and the control requirements for industrial emissions are also constantly increasing. Although traditional dust removal technologies, such as electrostatic precipitators and bag filters, can effectively remove dust, they are limited in their effectiveness in removing nitrogen oxides.

[0003] In order to achieve the integration of dust removal and denitration, the preparation process of membrane materials includes the preparation of membrane carriers, the preparation of nano-denitrification catalyst slurry, and the efficient composite of membrane materials and nano-denitrification catalysts. The ideal integrated ceramic membrane material for dust removal and denitration should have a good filtration outer membrane and a microporous structure of integrated catalysts. When selecting membrane carrier materials, it should be ensured that the filter element does not deactivate the catalyst, but instead helps the catalytic reaction and remains stable under high temperature and high corrosion environments. In addition, the membrane carrier material should have a high porosity. In order to increase the loading area of ​​the catalyst and improve the catalytic activity, it is sometimes necessary to coat a catalytically active layer with a high specific surface area on the pore surface of the large-pore support. Then, the catalyst active components are coated on the membrane material pre-coated with a high specific surface area catalytically active layer by processes such as vacuum impregnation. Since all selective catalytic reduction catalysts rely on electron exchange between active substances, the efficiency of electron exchange can be improved by controlling the morphology and crystallinity between the substrate and the active material. Increasing the effective surface area of ​​the catalyst can improve the unit mass efficiency of the catalyst.

[0004] At present, the filter material that realizes the integration of denitration and dust removal is mainly to combine the catalyst with the filter material substrate by dipping or coating. For example, patent CN108704390A coats the catalyst on the surface of metal fiber by a curing agent, while patent CN103463871A uses glass fiber as a supporting material and loads the MnOx denitration catalyst thereon by dipping. Patent CN04014200A innovatively mixes the denitration catalyst powder with the polytetrafluoroethylene filter membrane powder to prepare a catalytic filter membrane, and achieves a close combination of the filter material base cloth and the catalytic filter membrane through hot pressing composite technology. However, these technologies still face challenges in terms of uniform loading of catalytic particles, ease of operation and stability of the catalyst. Summary of the invention

[0005] The present invention provides a method for preparing a dust removal and denitration composite filter material, and innovates the post-finishing preparation process. The present invention mixes polytetrafluoroethylene and chitosan solutions evenly, then adds a catalyst, a foaming agent and a surfactant into the mixed solution, stirs and foams the mixed solution, applies the foaming emulsion to a filter substrate, and forms the dust removal and denitration composite filter material through heat setting treatment.

[0006] In order to solve the above problems, the present invention provides a method for preparing a dust removal and denitration composite filter material, which is characterized by comprising the following steps:

[0007] (1) adding 10% to 15% chitosan solution to a polytetrafluoroethylene solution, and uniformly stirring the solution at a speed of 200 to 300 r / min for 5 to 10 minutes to prepare a mixed solution;

[0008] (2) adding 6% to 15% of a catalyst, 2% to 5% of a foaming agent and 2% to 5% of a surfactant to the mixed solution, and stirring and foaming at 1000 to 1500 r / min to prepare a composite foam emulsion;

[0009] (3) Use an automatic coating machine to coat the composite foam emulsion on the needle-punched felt filter substrate, and heat and dry it in an oven at 80 to 150° C. for 3 to 5 minutes.

[0010] Preferably, the mixed solution in step (1) comprises a polytetrafluoroethylene solution with a solid content of 60 wt% and a chitosan solution with a solid content of 0.1 wt%.

[0011] Preferably, in step (1), the ratio of the polytetrafluoroethylene solution to the chitosan solution is (6:1) to (8:1).

[0012] Preferably, in step (2), the catalyst is 6% to 10% cerium manganese catalyst, the foaming agent is 2% to 5% polymethyl hydrogen siloxane and the surfactant is 2% to 5% betaine.

[0013] Preferably, the filter substrate in step (3) comprises glass fiber needle felt, polyphenylene sulfide needle felt, polyimide needle felt, and composite needle felt filter materials of two or more of the above.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention forms a composite filter material by mixing polytetrafluoroethylene and chitosan solution, introducing a catalyst, a foaming agent and a surfactant, and then coating and heat setting processes. This process adopts an integrated design. Compared with the traditional curing agent coating or impregnation method, the catalyst is directly mixed and coated with PTFE, avoiding the use of a curing agent while ensuring the high-efficiency filtering performance of the filter layer. This design significantly improves the bonding force between the catalyst and the PTFE filter layer and the filter substrate, and effectively achieves the removal of dust and nitrogen oxides.

[0016] By controlling the foaming process, the composite filter material of the present invention has a uniform and optimized pore structure, which is compared with the catalytic filter membrane prepared by mixing the denitration catalyst powder with the polytetrafluoroethylene filter membrane powder, which is not only beneficial to improving the filtration efficiency, but also helps to reduce the pressure drop and reduce the risk of local blockage. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the specific implementation of the present invention is further described below in conjunction with the accompanying drawings and specific implementation examples, but the implementation methods of the present invention are not limited thereto.

[0018] Example 1

[0019] A method for preparing a dust removal and denitration composite filter material comprises the following steps:

[0020] Raw material preparation: weigh 100 g of polytetrafluoroethylene solution with a solid content of 60 wt% and 15 g of chitosan solution with a solid content of 0.1 wt%.

[0021] Preparation of mixed solution: 15 g chitosan solution was slowly added into 100 g polytetrafluoroethylene solution, and stirred evenly at a speed of 250 r / min for 10 minutes to ensure that the two solutions were fully mixed to form a uniform mixed solution.

[0022] Addition of additives: 10g of cerium manganese catalyst was added to the mixed solution in turn to enhance the catalytic performance of the filter layer; then 4g of polymethylhydrogensiloxane foaming agent was added to improve the foam structure and increase the porosity of the filter layer; and 4g of betaine surfactant was added to reduce the surface tension of the solution and promote the stable formation of foam.

[0023] Stirring and foaming: Stir at a high speed of 1200 rpm for 5 minutes to ensure that the additives are evenly dispersed in the mixed solution to form a stable composite foam emulsion.

[0024] Coating the filter substrate: Use automated coating equipment to evenly coat the composite foam emulsion on the pre-prepared polyphenylene sulfide needle felt filter substrate to ensure the uniformity and consistency of the filter layer.

[0025] Heat setting treatment: Place the coated filter substrate into an oven and heat and dry it at a constant temperature of 130°C for 5 minutes to solidify the composite foam emulsion on the filter substrate to form a dust removal and denitrification composite filter material with stable structure and excellent performance.

[0026] Example 2

[0027] A method for preparing a dust removal and denitration composite filter material comprises the following steps:

[0028] Raw material preparation: weigh 100 g of polytetrafluoroethylene solution with a solid content of 60 wt% and 10 g of chitosan solution with a solid content of 0.1 wt%.

[0029] Preparation of mixed solution: 10 g chitosan solution was slowly added into 100 g polytetrafluoroethylene solution, and stirred evenly at a speed of 300 r / min for 8 minutes to ensure that the two solutions were fully mixed to form a uniform mixed solution.

[0030] Addition of additives: 6g of cerium manganese catalyst was added to the mixed solution in sequence to enhance the catalytic performance of the filter layer; then 2g of polymethylhydrogensiloxane foaming agent was added to improve the foam structure and increase the porosity of the filter layer; and 2g of betaine surfactant was added to reduce the surface tension of the solution and promote the stable formation of foam.

[0031] Stirring and foaming: Stir at a high speed of 1000 rpm for 10 minutes to ensure that the additives are evenly dispersed in the mixed solution to form a stable composite foam emulsion.

[0032] Coating the filter substrate: Use automated coating equipment to evenly coat the composite foam emulsion on the pre-prepared polyphenylene sulfide needle felt filter substrate to ensure the uniformity and consistency of the filter layer.

[0033] Heat setting treatment: Place the coated filter substrate into an oven and heat and dry it at a constant temperature of 100°C for 3 minutes to solidify the composite foam emulsion on the filter substrate to form a dust removal and denitrification composite filter material with stable structure and excellent performance.

[0034] Example 3

[0035] A method for preparing a dust removal and denitration composite filter material comprises the following steps:

[0036] Raw material preparation: weigh 100 g of polytetrafluoroethylene solution with a solid content of 60 wt% and 8 g of chitosan solution with a solid content of 0.1 wt%.

[0037] Preparation of mixed solution: 8 g of chitosan solution was slowly added into 100 g of polytetrafluoroethylene solution, and stirred evenly at a speed of 200 r / min for 6 minutes to ensure that the two solutions were fully mixed to form a uniform mixed solution.

[0038] Addition of additives: 8g of cerium manganese catalyst was added to the mixed solution in sequence to enhance the catalytic performance of the filter layer; then 3.5g of polymethylhydrogensiloxane foaming agent was added to improve the foam structure and increase the porosity of the filter layer; and 3.5g of betaine surfactant was added to reduce the surface tension of the solution and promote the stable formation of foam.

[0039] Stirring and foaming: Stir at a high speed of 1100 rpm for 8 minutes to ensure that the additives are evenly dispersed in the mixed solution to form a stable composite foam emulsion.

[0040] Coating the filter substrate: Use automated coating equipment to evenly coat the composite foam emulsion on the pre-prepared polyphenylene sulfide needle felt filter substrate to ensure the uniformity and consistency of the filter layer.

[0041] Heat setting treatment: Place the coated filter substrate into an oven and heat and dry it at a constant temperature of 120°C for 4 minutes to solidify the composite foam emulsion on the filter substrate to form a dust removal and denitrification composite filter material with stable structure and excellent performance.

[0042] Example 4

[0043] A method for preparing a dust removal and denitration composite filter material comprises the following steps:

[0044] Raw material preparation: weigh 100 g of polytetrafluoroethylene solution with a solid content of 60 wt% and 12 g of chitosan solution with a solid content of 0.1 wt%.

[0045] Preparation of mixed solution: 12 g chitosan solution was slowly added into 100 g polytetrafluoroethylene solution, and stirred evenly at a speed of 250 r / min for 7 minutes to ensure that the two solutions were fully mixed to form a uniform mixed solution.

[0046] Addition of additives: 9 g of cerium manganese catalyst was added to the mixed solution in turn to enhance the catalytic performance of the filter layer; then 3.6 g of polymethylhydrogensiloxane foaming agent was added to improve the foam structure and increase the porosity of the filter layer; and 3.6 g of betaine surfactant was added to reduce the surface tension of the solution and promote the stable formation of foam.

[0047] Stirring and foaming: Stir at a high speed of 1200 rpm for 8 minutes to ensure that the additives are evenly dispersed in the mixed solution to form a stable composite foam emulsion.

[0048] Coating the filter substrate: Use automated coating equipment to evenly coat the composite foam emulsion on the pre-prepared polyphenylene sulfide needle felt filter substrate to ensure the uniformity and consistency of the filter layer.

[0049] Heat setting treatment: Place the coated filter substrate in an oven and heat and dry it at a constant temperature of 110°C for 4 minutes to solidify the composite foam emulsion on the filter substrate to form a dust removal and denitrification composite filter material with stable structure and excellent performance.

[0050] Table 1 Example Example 1 Example 2 Example 3 Example 4 0.5μm particle filtration efficiency 30.2％ 43.2％ 21.5％ 20.5％ 2.5μm particle filtration efficiency 99.8％ 99.9％ 99.9％ 99.9％ Catalytic destocking efficiency 53.2％ 75.8％ 65.4％ 52.1％

[0051] Although the present invention is described in detail by way of preferred embodiments, the present invention is not limited thereto. Those skilled in the art may make various specific changes according to different actual needs without departing from the scope and spirit of the present invention, but they still fall within the scope of protection of this application.

Claims

1. A method for preparing a composite filter material for dust removal and denitration, characterized in that: The preparation method comprises the following steps: S1. Add 10% to 15% chitosan solution to the polytetrafluoroethylene solution, and stir evenly at a speed of 200 to 300 r / min for 5 to 10 minutes to prepare a mixed solution; S2, adding 6% to 15% of a catalyst, 2% to 5% of a foaming agent and 2% to 5% of a surfactant to the mixed solution, stirring and foaming at 1000 to 1500 r / min to prepare a composite foam emulsion; S3. Use an automatic coating machine to coat the composite foam emulsion on the filter substrate, and heat and dry it in an oven at 80-150° C. for 3-5 minutes.

2. The method for preparing the dust removal and denitration composite filter material according to claim 1, characterized in that: The mixed solution in S1 is a polytetrafluoroethylene solution with a solid content of 60 wt% and a chitosan solution with a solid content of 0.1 wt%.

3. The method for preparing the dust removal and denitration composite filter material according to claim 1, characterized in that: The ratio of the polytetrafluoroethylene solution to the chitosan solution in S1 is (6:1) to (8:1).

4. The dust removal and denitrification composite filter material according to claim 1, characterized in that: The catalyst in S2 is 6% to 15% of cerium manganese catalyst, the foaming agent is 2% to 5% of polymethyl hydrogen siloxane and the surfactant is 2% to 5% of betaine.

5. The method for preparing the dust removal and denitration composite filter material according to claim 1, characterized in that: The filter substrate described in S3 includes glass fiber needle felt, polyphenylene sulfide needle felt, polyimide needle felt and two or more composite needle felt filter materials mentioned above.