Preparation method of denitration catalytic functional nano spinning filter material

Abstract

The invention relates to the technical field of chemical engineering, and provides a preparation method of a denitration catalytic functional nano spinning filter material, which comprises the following steps: step 1, raw material preparation, step 2, spinning solution preparation, step 3, electrostatic spinning, step 4, heat treatment, and step 5, activating treatment. The method is simple in process, easy to operate and suitable for large-scale production. The prepared nano spinning filter material has a good denitration catalytic effect, can effectively remove nitrogen oxides in waste gas, and has important significance for environmental protection. Meanwhile, the filter material is excellent in filtering performance, can be widely applied to the fields of industrial waste gas treatment, automobile tail gas purification and the like, and has wide market prospects and application value. In practical application, the multifunctional nano spinning filtering material plays an important role in improving the air quality and promoting the development of the environmental protection cause, and brings many positive influences to the society and the environment.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and particularly to a preparation method of a denitration catalytic functional nanofiber filtration material. Background Art

[0002] With the acceleration of the industrialization process, the emissions of nitrogen oxides (NOx) have caused serious pollution to the environment and become an urgent problem to be solved. Traditional denitration methods have many problems such as low efficiency, high cost, and complex operation, and it is difficult to meet the increasingly strict environmental protection requirements. Therefore, it is of great practical significance to develop an efficient, economical, and environmentally friendly denitration technology.

[0003] In the denitration technology, the denitration catalyst plays a key role. However, the existing denitration catalysts often have disadvantages such as low activity, poor stability, and short service life, which limit their effects in practical applications. At the same time, traditional filtration materials also have deficiencies in filtration performance and mechanical properties, and it is difficult to effectively remove particulate matter and harmful substances in waste gas.

[0004] To solve the above problems, researchers are committed to developing new denitration catalytic materials and filtration materials. The development of nanotechnology has brought new opportunities to this field. Nanomaterials have advantages such as large specific surface area, high porosity, and many active sites, and are expected to improve the performance of denitration catalysts. Electrospinning technology, as an effective method for preparing nanofibers, has advantages such as simple process and strong controllability, and has been widely used in the field of materials. However, how to combine the denitration catalyst with electrospinning technology to prepare a nanofiber filtration material with high denitration catalytic performance and good filtration performance is still a technical problem to be solved urgently. Summary of the Invention

[0005] To overcome the defects of the prior art, the purpose of the present invention is to provide a preparation method of a denitration catalytic functional nanofiber filtration material.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: A preparation method of a denitration catalytic functional nanofiber filtration material includes the following steps:

[0007] Step 1, preparation of raw materials:

[0008] Prepare a polymer material, a denitration catalyst precursor, a solvent, and a surfactant; wherein, the polymer material is selected from at least one of polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polystyrene (PS); the denitration catalyst precursor is at least one of compounds containing vanadium (V), tungsten (W), and molybdenum (Mo); the solvent is at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO); the surfactant is at least one of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB).

[0009] Step two, preparation of the spinning solution:

[0010] Dissolve the polymer material in the solvent to form a polymer solution; then add the denitration catalyst precursor to the polymer solution and mix it well under stirring conditions; finally, add the surfactant and continue stirring to obtain a uniform spinning solution; during the stirring process, use ultrasonic-assisted dispersion to improve the dispersion uniformity of the denitration catalyst precursor in the polymer solution.

[0011] Step three, electrospinning:

[0012] Load the spinning solution into the syringe of the electrospinning equipment, adjust the electrospinning parameters, and perform electrospinning to obtain a nanofiber membrane; during the electrospinning process, introduce magnetic field assistance to make the arrangement of the nanofibers more orderly and improve the mechanical properties of the filter material.

[0013] Step four, heat treatment:

[0014] Put the nanofiber membrane into an oven for heat treatment to remove the solvent and cure the polymer material; during the heat treatment process, use a segmented heating method, first heat it to a certain temperature at a lower heating rate, keep it for a period of time, and then heat it to the final temperature at a higher heating rate to effectively reduce the internal stress of the material and improve the stability of the material.

[0015] Step five, activation treatment:

[0016] Perform activation treatment on the heat-treated nanofiber membrane in an atmosphere containing ammonia to convert the denitration catalyst precursor into a catalyst with denitration activity. During the activation treatment process, periodically change the flow rate and temperature of ammonia to promote the formation of active sites of the catalyst and improve the denitration catalytic performance.

[0017] Preferably, the polymer material is polyacrylonitrile (PAN), the denitration catalyst precursor is ammonium metavanadate (NH4VO3) and ammonium tungstate ((NH4)10W12O41·xH2O), the solvent is N,N-dimethylformamide (DMF), and the surfactant is sodium dodecyl sulfate (SDS).

[0018] Preferably, the mass fraction of the polymer material in the polymer solution is 8-15%.

[0019] Preferably, the mass fraction of the denitration catalyst precursor in the spinning solution is 5-20%.

[0020] Preferably, the mass fraction of the surfactant is 0.5-2%.

[0021] Preferably, the environmental temperature for electrospinning is 20-30°C, the relative humidity is 30-60%, and the electrospinning parameters include voltage, flow rate, and receiving distance. The voltage is 10-30 kV, the flow rate is 0.1-1.0 mL / h, and the receiving distance is 10-25 cm.

[0022] Preferably, during the ultrasonic-assisted dispersion process, the ultrasonic frequency is 20-50 kHz, and the ultrasonic time is 1-3 h.

[0023] Preferably, during the magnetic field-assisted electrospinning process, the magnetic field intensity is 0.1-0.5 T.

[0024] Preferably, during the activation treatment process, the change cycle of the ammonia gas flow rate and temperature is 1-2 h, the activation treatment temperature is 300-500°C, the treatment time is 2-6 h, and the ammonia gas flow rate is 50-200 mL / min.

[0025] Preferably, the thickness of the nanofiber membrane is 50-200 μm, the heat treatment temperature is 60-150°C, and the treatment time is 2-10 h.

[0026] The beneficial effects of the present invention are embodied in:

[0027] First, by selecting appropriate polymer materials, denitration catalyst precursors, solvents, and surfactants, a nanofiber filtration material with excellent performance can be prepared. The combination of various materials provides a wide range of choices and optimization space.

[0028] Second, the ultrasonic-assisted dispersion technology effectively improves the dispersion uniformity of the denitration catalyst precursor in the polymer solution, ensures the uniform distribution of the catalyst in the material, and thus improves the consistency and stability of the denitration catalytic performance.

[0029] Introducing magnetic field assistance during the electrospinning process makes the nanofibers more orderly arranged, significantly improves the mechanical properties of the filtration material, and enhances its durability and reliability.

[0030] Adopting a stepwise temperature increase method during the heat treatment process can effectively reduce the internal stress of the material, improve the stability of the material, and extend its service life.

[0031] During the activation process, the flow rate and temperature of ammonia are periodically changed, which promotes the formation of catalytic active sites and further improves the denitrification catalytic performance.

[0032] In addition, this method has a simple process and is easy to operate, making it suitable for large-scale production. The prepared nanofiber filter material has good denitrification catalytic effect, can effectively remove nitrogen oxides in waste gas, and is of great significance to environmental protection. At the same time, its filtration performance is also excellent, and it can be widely used in industrial waste gas treatment, automobile exhaust purification and other fields, with broad market prospects and application value. In practical applications, this multifunctional nanofiber filter material will play an important role in improving air quality and promoting the development of environmental protection, bringing many positive impacts to society and the environment. Brief Description of the Drawings

[0033] In the drawings:

[0034] Figure 1 is the process flow chart of the preparation of the present invention. Detailed Description of the Invention

[0035] The present invention will be further described in detail below with reference to the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all of the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. Based on the embodiments of the invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the invention.

[0036] In addition, "a plurality of" means more than two. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the invention.

[0037] Please refer to the attached specification Figure 1 , the present invention provides a method for preparing a denitrification catalytic functional nanofiber filter material, comprising the following steps:

[0038] Step 1, raw material preparation:

[0039] Prepare a polymer material, a denitration catalyst precursor, a solvent, and a surfactant; wherein, the polymer material is selected from at least one of polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polystyrene (PS); the denitration catalyst precursor is at least one of compounds containing vanadium (V), tungsten (W), and molybdenum (Mo); the solvent is at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO); the surfactant is at least one of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB);

[0040] Step two, preparation of the spinning solution:

[0041] Dissolve the polymer material in the solvent to form a polymer solution; then add the denitration catalyst precursor to the polymer solution and mix it thoroughly under stirring conditions; finally, add the surfactant and continue stirring to obtain a uniform spinning solution; during the stirring process, ultrasonic-assisted dispersion is used to improve the dispersion uniformity of the denitration catalyst precursor in the polymer solution;

[0042] Step three, electrospinning:

[0043] Load the spinning solution into the syringe of the electrospinning equipment, adjust the spinning parameters, and perform electrospinning to obtain a nanofiber membrane; wherein, the spinning parameters include voltage, flow rate, receiving distance, etc., the voltage is 10 - 30 kV, the flow rate is 0.1 - 1.0 mL / h, and the receiving distance is 10 - 25 cm; during the electrospinning process, a magnetic field is introduced to make the arrangement of the nanofibers more orderly and improve the mechanical properties of the filter material;

[0044] Step four, heat treatment:

[0045] Put the nanofiber membrane into an oven for heat treatment to remove the solvent and cure the polymer material; the heat treatment temperature is 60 - 150 °C, and the treatment time is 2 - 10 h; during the heat treatment process, a stepwise heating method is adopted, first heating to a certain temperature at a lower heating rate, maintaining for a period of time, and then heating to the final temperature at a higher heating rate to effectively reduce the internal stress of the material and improve the stability of the material;

[0046] Step five, activation treatment:

[0047] Perform activation treatment on the heat-treated nanofiber membrane in an atmosphere containing ammonia to convert the denitration catalyst precursor into a catalyst with denitration activity. The activation treatment temperature is 300 - 500 °C, the treatment time is 2 - 6 h, and the ammonia flow rate is 50 - 200 mL / min. During the activation treatment process, the ammonia flow rate and temperature are periodically changed to promote the formation of active sites of the catalyst and improve the denitration catalytic performance.

[0048] Example 1

[0049] Raw material preparation:

[0050] Polymer material: Polyacrylonitrile (PAN)

[0051] Denitration catalyst precursor: Ammonium metavanadate (NH4VO3) and ammonium tungstate ((NH4) 10 W 12 O 41 ·xH2O)

[0052] Solvent: N,N-Dimethylformamide (DMF)

[0053] Surfactant: Sodium dodecyl sulfate (SDS)

[0054] Spinning solution preparation:

[0055] Dissolve 8 - 10% of polyacrylonitrile (PAN) in DMF to form a polymer solution.

[0056] Add 5 - 15% of ammonium metavanadate and ammonium tungstate and stir evenly.

[0057] Add 1% of SDS, continue stirring and perform ultrasonic-assisted dispersion with an ultrasonic frequency of 30 kHz for 2 hours.

[0058] Electrospinning:

[0059] Adjust the parameters of the electrospinning equipment, set the voltage to 25 kV, the flow rate to 0.5 mL / h, and the receiving distance to 15 cm.

[0060] Perform electrospinning in an environment of 20°C and 50% relative humidity to obtain a nanofiber membrane.

[0061] Heat treatment:

[0062] Treat the nanofiber membrane in an oven at a temperature of 80°C for 4 hours using a stepwise heating method.

[0063] Activation treatment:

[0064] Perform activation treatment at 300°C for 4 hours under the condition of an ammonia flow rate of 100 mL / min.

[0065] Example 2

[0066] Raw material preparation:

[0067] Polymer material: Polyvinylidene fluoride (PVDF)

[0068] Denitration catalyst precursor: Ammonium molybdate ((NH4)6Mo7O24 ·4H2O)

[0069] Solvent: Dimethyl sulfoxide (DMSO)

[0070] Surfactant: Cetyltrimethylammonium bromide (CTAB)

[0071] Preparation of spinning solution:

[0072] Dissolve 10 - 12% of polyvinylidene fluoride (PVDF) in DMSO.

[0073] Add 10% of ammonium molybdate and stir evenly.

[0074] Add 0.5% of CTAB and perform ultrasonic - assisted dispersion. The ultrasonic frequency is 25 kHz and the time is 1.5 hours.

[0075] Electrospinning:

[0076] Adjust the parameters of the electrospinning equipment. The voltage is set to 20 kV, the flow rate is 0.3 mL / h, and the receiving distance is 12 cm.

[0077] Conduct electrospinning in an environment of 25°C and relative humidity of 40%.

[0078] Heat treatment:

[0079] Treat in an oven at a temperature of 100°C for 3 hours using a step - by - step heating method.

[0080] Activation treatment:

[0081] Under the condition of ammonia gas flow rate of 150 mL / min, conduct activation treatment at 400°C for 3 hours.

[0082] Example 3

[0083] Raw material preparation:

[0084] Polymer material: Polystyrene (PS)

[0085] Denitrification catalyst precursor: Ammonium tungstate ((NH4) 10 W 12 O 41 ·xH2O)

[0086] Solvent: N,N - Dimethylacetamide (DMAc)

[0087] Surfactant: Sodium dodecyl sulfate (SDS)

[0088] Preparation of spinning solution:

[0089] Dissolve 9 - 15% of polystyrene (PS) in DMAc.

[0090] Add 8% ammonium tungstate and stir evenly.

[0091] Add 1.5% SDS and perform ultrasonic-assisted dispersion at an ultrasonic frequency of 40 kHz for 2 hours.

[0092] Electrospinning:

[0093] Adjust the parameters of the electrospinning equipment, set the voltage to 30 kV, the flow rate to 0.7 mL / h, and the receiving distance to 20 cm.

[0094] Perform electrospinning in an environment at 22 °C and a relative humidity of 35%.

[0095] Heat treatment:

[0096] Treat in an oven at 120 °C for 5 hours using a stepwise heating method.

[0097] Activation treatment:

[0098] Perform activation treatment at 350 °C for 2 hours under the condition that the ammonia flow rate is 75 mL / min.

[0099] To further illustrate the advantages of the method of the present invention, the following comparative experiments were carried out, and there are the following charts;

[0100] Comparative Example 1: Without ultrasonic-assisted dispersion

[0101] During the preparation of the spinning solution, except for not performing ultrasonic-assisted dispersion, other conditions are the same as in Example 1.

[0102] Comparative Example 2: Without magnetic field-assisted electrospinning

[0103] During electrospinning, except for not performing magnetic field assistance, other conditions are the same as in Example 1.

[0104] Table 1. Comparison of process parameters in Example 1, 2, 3 and Comparative Example 1, 2

[0105]

[0106]

[0107] According to Table 1 above, the following conclusions can be obtained:

[0108] Comparative Example 1: Without ultrasonic-assisted dispersion

[0109] The test results of the denitrification catalytic performance of the prepared nanofiber membrane show that the denitrification efficiency is reduced by about 20% compared with Example 1, indicating that ultrasonic-assisted dispersion helps to improve the dispersion uniformity of the denitrification catalyst precursor, thereby enhancing the denitrification performance of the material.

[0110] Comparative Example 2: Without magnetic field-assisted electrospinning

[0111] The test results of the mechanical properties of the prepared nanofiber membrane show that its tensile strength is reduced by about 15% compared with that of Example 1, and the elongation at break is reduced by about 10%, indicating that magnetic field assistance can make the nanofibers more orderly arranged and improve the mechanical properties of the filter material.

[0112] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0113] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0114] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of a denitration catalytic functional nanofiber filter material, characterized in that, The following steps are involved: Step 1: Raw materials preparation: Prepare a polymer material, a denitration catalyst precursor, a solvent and a surfactant; wherein the polymer material is selected from at least one of polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polystyrene (PS); the denitration catalyst precursor is at least one of compounds containing vanadium (V), tungsten (W), and molybdenum (Mo); the solvent is at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO); the surfactant is at least one of sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB); Step 2: Preparation of spinning solution: Dissolving the polymer material in the solvent to form a polymer solution; then adding the denitration catalyst precursor to the polymer solution and mixing them thoroughly under stirring conditions; finally adding the surfactant and continuing stirring to obtain a uniform spinning solution; During the stirring process, ultrasonic assisted dispersion is used to improve the dispersion uniformity of the denitration catalyst precursor in the polymer solution; Step 3, electrospinning: The spinning solution is loaded into a syringe of an electrospinning device, and the spinning parameters are adjusted to perform electrospinning to obtain a nanofiber membrane; during the electrospinning process, a magnetic field is introduced to assist so that the arrangement of the nanofibers is more orderly and the mechanical properties of the filter material are improved; Step 4: Heat treatment: The nanofiber membrane is placed in an oven for heat treatment to remove the solvent and solidify the polymer material; during the heat treatment process, a staged heating method is adopted, firstly heating to a certain temperature at a lower heating rate, maintaining for a period of time, and then heating to a final temperature at a higher heating rate, so as to effectively reduce the stress inside the material and improve the stability of the material; Step 5: Activation treatment: The heat-treated nanofiber membrane is activated in an atmosphere containing ammonia to convert the denitrification catalyst precursor into a catalyst with denitrification activity. During the activation process, the flow rate and temperature of ammonia are periodically changed to promote the formation of active sites of the catalyst and improve the denitrification catalytic performance.

2. The preparation method of a denitration catalytic functional nanofiber filtration material according to claim 1, wherein, The polymer material is polyacrylonitrile (PAN), and the denitration catalyst precursor is ammonium metavanadate (NH4VO3) and ammonium tungstate ((NH4) 10 W 12 O 41 ·xH2O), the solvent is N,N-dimethylformamide (DMF), and the surfactant is sodium dodecyl sulfate (SDS).

3. The preparation method of a denitration catalytic functional nanofiber filter material according to claim 1 or 2, characterized in that, The mass fraction of the polymer material in the polymer solution is 8-15%.

4. The preparation method of a denitration catalytic functional nanofiber filter material according to claim 1 or 2, characterized in that, The mass fraction of the denitration catalyst precursor in the spinning solution is 5-20%.

5. The preparation method of a denitrification catalytic functional nanofiber filter material according to claim 1 or 2, characterized in that, The mass fraction of the surfactant is 0.5-2%.

6. The preparation method of a denitrification catalytic functional nanofiber filter material according to claim 1, characterized in that, The environmental temperature of the electrospinning is 20-30° C., the relative humidity is 30-60%, and the spinning parameters include voltage, flow rate, and receiving distance. The voltage is 10-30 kV, the flow rate is 0.1-1.0 mL / h, and the receiving distance is 10-25 cm.

7. The preparation method of a denitrification catalytic functional nanofiber filtration material according to claim 1, characterized in that, In the ultrasound-assisted dispersion process, the ultrasound frequency is 20-50 kHz and the ultrasound time is 1-3 h.

8. The preparation method of a denitrification catalytic functional nanofiber filtration material according to claim 1, characterized in that, During the magnetic field-assisted electrospinning process, the magnetic field strength was 0.1-0.5T.

9. The preparation method of a denitration catalytic functional nanofiber filter material according to claim 1, characterized in that During the activation treatment process, the change cycle of the ammonia flow rate and temperature is 1-2h, the activation treatment temperature is 300-500°C, the treatment time is 2-6h, and the ammonia flow rate is 50-200mL / min.

10. The preparation method of a denitration catalytic functional nanofiber filter material according to claim 1, characterized in that, The thickness of the nanofiber membrane is 50 - 200 μm, the heat treatment temperature is 60 - 150 °C, and the treatment time is 2 - 10 h.

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