Preparation method of multifunctional fiber membrane based on multi-stage pore confinement dispersion

Abstract

The application discloses a kind of preparation methods of multifunctional fiber membrane based on multi-level hole limited dispersion, belong to membrane material preparation technical field.The application designs and prepares multi-level hole fiber membrane using electrospinning technology, and by regulating spinning solution component and spinning parameter, the controllable adjustment preparation of multi-level hole structure can be realized.Based on the space limited system of hole structure, high dispersity Pt cluster is constructed in fiber channel using atomic layer deposition technology, and multifunctional fiber membrane is constructed.The multifunctional fiber membrane prepared in the application can simultaneously realize the efficient low-resistance interception of particulate matter in indoor air and the complete catalytic removal of low-concentration formaldehyde, and provides reliable technical support for developing high-performance multifunctional membrane materials.

Description

Technical Field

[0001] This invention belongs to the field of membrane material preparation technology, specifically relating to a method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion. Background Technology

[0002] People spend most of their time indoors, where various pollutants can adversely affect human health. Currently, filtration, adsorption, and catalysis methods have been developed to address different air pollutants, including fiber membrane materials for particulate matter filtration and catalysts for degrading gaseous pollutants (such as formaldehyde and toluene). However, simple composites of several functional materials often face problems such as increased filtration resistance, catalyst growth, or detachment, limiting their practical application. Therefore, developing multifunctional membrane materials is a key research focus in this field. In recent years, fiber membranes with hierarchical porous structures have shown significant advantages in air purification due to their ultra-high specific surface area and interconnected porous structure. Thanks to their special structure, hierarchical porous fiber membranes can maintain low filtration resistance while achieving efficient interception of easily escaped particulate matter such as PM0.3; simultaneously, the porous structure on the fibers facilitates the adsorption-enrichment-catalysis tandem purification mechanism for low-concentration pollutants, solving the difficulty of removing low-concentration harmful pollutants. Furthermore, the porous structure on the fibers provides an ideal environment for the confined dispersion loading of catalysts, which is beneficial for the precise design and modulation of catalyst activity and stability.

[0003] Several studies on the construction of confined and dispersed catalysts have been reported. Chinese invention patent CN110694615B, "Preparation method of Pt-based catalyst confined in tunable-pore titanium oxide nanotubes and its application," utilizes atomic layer deposition (ALD) to confine Pt nanoparticles within the cavity of tunable-pore titanium oxide nanotubes. By adjusting the sacrificial layer thickness, a confined Pt-based catalyst with excellent catalytic performance is prepared. Chinese invention patent CN116651442B, "Surface-confined atomically dispersed Pt@SiO2-N catalyst and its preparation method and application," performs a Pt ALD process on surface-functionalized SiO2-N to obtain a surface-confined atomically dispersed Pt@SiO2-N catalyst. Chinese invention patent CN120679586A, entitled "Preparation Method and Application of a Highly Stable Pt-Based Low-Carbon Alkane Dehydrogenation Catalyst," utilizes a growth strategy of self-restricted surface hydroxyl chemical reactions on activated molecular sieve supports to achieve site-specific anchoring of single-atom-level dispersed Pt clusters, forming stable nanocatalysts with strong metal-support interactions. While the aforementioned methods have all produced catalysts with excellent performance, significant breakthroughs have not yet been achieved in the research of monolithic multifunctional materials for practical applications. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention designs and prepares a hierarchical porous fiber membrane using electrospinning technology. By adjusting the spinning solution composition and spinning parameters, the hierarchical pore structure can be controllably adjusted. Simultaneously, based on the spatially confined system of the pore structure, highly dispersed Pt clusters are constructed within the fiber channels using atomic layer deposition (ALD) technology, forming a multifunctional fiber membrane. The prepared multifunctional fiber membrane can simultaneously achieve efficient and low-resistance retention of indoor particulate matter and catalytic removal of low-concentration gaseous pollutants. This preparation method provides a theoretical basis for the controllable preparation of high-performance multifunctional membrane materials, possessing significant scientific and practical value.

[0005] The purpose of this invention is to provide a method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion. The multifunctional fiber membrane obtained by this method can achieve cluster-level dispersion of the catalyst within the pore structure, enabling efficient catalytic removal of gaseous pollutants such as formaldehyde in indoor air, while also efficiently purifying fine particulate matter in the air.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for preparing a multifunctional fiber membrane based on hierarchical pore confinement dispersion involves sequentially adding polyvinylpyrrolidone, titanium dioxide precursor, and silicon dioxide precursor to a solvent and mixing them to obtain a spinning solution. After electrospinning and calcination, an inorganic hierarchical porous fiber membrane is obtained. Then, atomic layer deposition of Pt clusters is performed on the inorganic hierarchical porous fiber membrane to obtain the aforementioned multifunctional fiber membrane based on hierarchical pore confinement dispersion.

[0007] Preferably, the inorganic hierarchical porous fiber membrane is composed of titanium dioxide and silicon dioxide.

[0008] Preferably, the silicon oxide precursor includes one or more of tetramethyl silicate and tetraethyl orthosilicate; the titanium oxide precursor is tetrabutyl titanate.

[0009] Preferably, the solvents are ethanol and acetic acid; in the spinning solution, the contents of polyvinylpyrrolidone, titanium dioxide precursor, silicon dioxide precursor, ethanol and acetic acid are 10 wt.%, 5~25 wt.%, 5~25 wt.%, 50 wt.%, and 10 wt.%, respectively.

[0010] Preferably, the conditions for electrospinning are: spinning voltage of 10~30 kV, nozzle inner diameter of 0.50~1.55 mm, spinning solution flow rate of 1~10 mL / h, and distance between nozzle and receiving roller of 10~20 cm.

[0011] Preferably, the calcination conditions are: calcination atmosphere is air, heating rate is 1~10 °C / min, calcination temperature is 500~800 °C, and holding time is 1-3 h.

[0012] Preferably, the inorganic hierarchical porous fiber membrane has two types of pore structures: (1) micropores and mesopores on the fibers; and (2) macropores formed by the interfibers.

[0013] Preferably, the Pt precursor used for atomic layer deposition includes one or more of trimethyl(methylcyclopentadienyl)platinum, platinum acetylacetonate, and dinitrodiamineplatinum.

[0014] Preferably, the atomic layer deposition cycle number is 1 to 10 times.

[0015] Preferably, the content of Pt element in the multifunctional fiber membrane is 0.2~2.0 wt.%.

[0016] The beneficial effects of this invention are: 1. The multifunctional fiber membrane prepared by this invention constructs a spatially confined system through the micropores and mesopores in the fibers, which can realize the cluster-level dispersion of the catalyst within the pore structure.

[0017] 2. The multifunctional fiber membrane prepared by this invention has high connectivity and high specific surface area, and exhibits high filtration efficiency and low filtration resistance for easily escaped particulate matter such as PM0.3.

[0018] 3. The multifunctional fiber membrane prepared by this invention has excellent catalytic performance and can achieve complete catalytic removal of low concentrations of formaldehyde at room temperature.

[0019] 4. The preparation method described in this invention is simple and easy to operate, and has broad application prospects. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the cross-section of the multifunctional fiber membrane prepared in Example 1 of the present invention.

[0021] Figure 2 This is a scanning electron microscope image of the surface of the multifunctional fiber membrane prepared in Example 1 of the present invention.

[0022] Figure 3 This is a pore size distribution diagram of the fiber stacking pores of the multifunctional fiber membrane prepared in Example 1 of the present invention.

[0023] Figure 4 The nitrogen adsorption-desorption curve is shown for the multifunctional fiber membrane prepared in Example 1 of this invention.

[0024] Figure 5 Transmission electron microscope and elemental analysis images of a single fiber of the multifunctional fiber membrane prepared in Example 1 of this invention.

[0025] Figure 6 This is a transmission electron microscope (TEM) image of a selected area of ​​a single fiber cross-section of the multifunctional fiber membrane prepared in Example 1 of the present invention.

[0026] Figure 7 This is a size distribution diagram of the Pt clusters loaded on the multifunctional fiber membrane prepared in Example 1 of the present invention. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification. Example 1

[0028] (1) Preparation of spinning solution: Add 2 g of polyvinylpyrrolidone to a mixed solvent of 10 g of ethanol and 2 g of acetic acid. After complete dissolution, add 1.3 g of tetrabutyl titanate and 4.7 g of tetraethyl orthosilicate in sequence. Stir evenly to form a precursor solution.

[0029] (2) Preparation of precursor fiber membrane by electrospinning: The spinning solution was placed in an electrospinning apparatus for spinning. The conditions were set as follows: nozzle inner diameter of 1.15 mm, spinning solution flow rate of 5 mL / h, voltage of 24 kV, and distance between the collecting roller and the nozzle of 15 cm. The collected fiber membrane was dried at 60 °C to remove excess solvent, and the precursor fiber membrane was obtained.

[0030] (3) Calcination: The precursor fiber membrane was calcined at 550 °C for 2 h with a heating rate of 1 °C / min to obtain an inorganic hierarchical porous fiber membrane.

[0031] (4) Atomic layer deposition: Using trimethyl(methylcyclopentadienyl)platinum as a precursor, atomic layer deposition was performed on the obtained inorganic hierarchical porous fiber membrane for 5 cycles to obtain a multifunctional fiber membrane. The content of Pt element in the multifunctional fiber membrane was 1.0 wt.%.

[0032] Testing showed that the prepared multifunctional fiber membrane achieved a PM0.3 filtration efficiency of 99.79%, a pressure drop of 40.5 Pa, and a quality factor of 0.153 Pa. -1 It can meet the requirements of high-efficiency, low-resistance filtration of easily escaped particulate matter such as PM0.3 in indoor air.

[0033] The prepared multifunctional fiber membrane was tested and found to have a performance of 120 L·g -1 ·h -1 At a space velocity of [value missing], it can achieve 100% catalytic removal of formaldehyde at a concentration of 2 ppm at room temperature, and its performance does not decay for at least 48 hours, which can meet the national standards for indoor air quality.

[0034] Figure 1 The image shown is a scanning electron microscope image of the cross-section of the multifunctional fiber membrane prepared in Example 1 of the present invention, showing that the fiber has an internal porous structure. Figure 2The image shown is a scanning electron microscope image of the surface of the multifunctional fiber membrane prepared in Example 1, which shows that the fibers are randomly assembled to form a macroporous structure. Figure 3 The image shows the pore size distribution of the multifunctional fiber membrane prepared in Example 1, indicating that the fiber membrane has a macroporous structure. Figure 4 The attached figure shows the nitrogen adsorption-desorption of the multifunctional fiber membrane prepared in Example 1, which is a type IV isotherm with an H4 type hysteresis loop, indicating that the fiber membrane has both microporous and mesoporous structures. Figure 5 Transmission electron microscopy and elemental analysis diagram of a single fiber of the multifunctional fiber membrane prepared in Example 1. Figure 6 The transmission electron microscopy (TEM) images of selected sections of a single fiber cross-section of the multifunctional fiber membrane prepared in Example 1 all show that Pt clusters are uniformly dispersed in various regions of the fiber. Figure 7 The image shows the size distribution of Pt clusters loaded on the multifunctional fiber membrane prepared in Example 1, indicating that the Pt clusters are uniform in size with an average particle size of 1.04 nm. Example 2

[0035] (1) Preparation of spinning solution: Add 2 g of polyvinylpyrrolidone to a mixed solvent of 10 g of ethanol and 2 g of acetic acid. After complete dissolution, add 1.3 g of tetrabutyl titanate and 4.7 g of tetraethyl orthosilicate in sequence. Stir evenly to form a precursor solution.

[0036] (2) Preparation of precursor fiber membrane by electrospinning: The spinning solution was placed in an electrospinning apparatus for spinning. The conditions were set as follows: nozzle inner diameter of 1.15 mm, spinning solution flow rate of 5 mL / h, voltage of 24 kV, and distance between the collecting roller and the nozzle of 15 cm. The collected fiber membrane was dried at 60 °C to remove excess solvent, and the precursor fiber membrane was obtained.

[0037] (3) Calcination: The precursor fiber membrane was calcined at 550 °C for 2 h with a heating rate of 3 °C / min to obtain an inorganic hierarchical porous fiber membrane.

[0038] (4) Atomic layer deposition: Using trimethyl(methylcyclopentadienyl)platinum as a precursor, atomic layer deposition was performed on the obtained inorganic hierarchical porous fiber membrane for 10 cycles to obtain a multifunctional fiber membrane. The content of Pt element in the multifunctional fiber membrane was 2.0 wt.%.

[0039] Testing showed that the prepared multifunctional fiber membrane achieved a PM0.3 filtration efficiency of 99.75%, a pressure drop of 49.0 Pa, and a quality factor of 0.122 Pa. -1 It can meet the requirements of high-efficiency, low-resistance filtration of easily escaped particulate matter such as PM0.3 in indoor air.

[0040] The prepared multifunctional fiber membrane was tested and found to have a performance of 120 L·g -1 ·h-1 At a space velocity of [value missing], it can achieve 100% catalytic removal of formaldehyde at a concentration of 2 ppm at room temperature, and its performance does not decay for at least 72 hours, which can meet the national standards for indoor air quality. Example 3

[0041] (1) Preparation of spinning solution: Add 2 g of polyvinylpyrrolidone to a mixed solvent of 10 g of ethanol and 2 g of acetic acid. After complete dissolution, add 1.3 g of tetrabutyl titanate and 4.7 g of tetraethyl orthosilicate in sequence. Stir evenly to form a precursor solution.

[0042] (2) Preparation of precursor fiber membrane by electrospinning: The spinning solution was placed in an electrospinning apparatus for spinning. The conditions were set as follows: nozzle inner diameter of 1.55 mm, spinning solution flow rate of 10 mL / h, voltage of 20 kV, and distance between the collecting roller and the nozzle of 15 cm. The collected fiber membrane was dried at 60 °C to remove excess solvent, and the precursor fiber membrane was obtained.

[0043] (3) Calcination: The precursor fiber membrane was calcined at 550 °C for 2 h with a heating rate of 5 °C / min to obtain an inorganic hierarchical porous fiber membrane.

[0044] (4) Atomic layer deposition: Using trimethyl(methylcyclopentadienyl)platinum as a precursor, atomic layer deposition was performed on the obtained inorganic hierarchical porous fiber membrane for 3 cycles to obtain a multifunctional fiber membrane. The content of Pt element in the multifunctional fiber membrane was 0.6 wt.%.

[0045] Testing showed that the prepared multifunctional fiber membrane achieved a PM0.3 filtration efficiency of 99.77%, a pressure drop of 54.5 Pa, and a quality factor of 0.111 Pa. -1 It can meet the requirements of high-efficiency, low-resistance filtration of easily escaped particulate matter such as PM0.3 in indoor air.

[0046] The prepared multifunctional fiber membrane was tested and found to have a performance of 120 L·g -1 ·h -1 At a space velocity of 1000 h⁻¹, the room temperature catalytic efficiency for formaldehyde at a concentration of 2 ppm is 64.0%. Example 4

[0047] (1) Preparation of spinning solution: Add 2 g of polyvinylpyrrolidone to a mixed solvent of 10 g of ethanol and 2 g of acetic acid. After complete dissolution, add 1.0 g of tetrabutyl titanate and 5.0 g of tetramethyl silicate in sequence. Stir evenly to form a precursor solution.

[0048] (2) Preparation of precursor fiber membrane by electrospinning: The spinning solution was placed in an electrospinning apparatus for spinning. The conditions were set as follows: nozzle inner diameter of 0.50 mm, spinning solution flow rate of 1 mL / h, voltage of 10 kV, and distance between the collecting roller and the nozzle of 10 cm. The collected fiber membrane was dried at 60 °C to remove excess solvent, and the precursor fiber membrane was obtained.

[0049] (3) Calcination: The precursor fiber membrane was calcined at 500 °C for 3 h with a heating rate of 1 °C / min to obtain an inorganic hierarchical porous fiber membrane.

[0050] (4) Atomic layer deposition: Using platinum acetylacetonate as a precursor, atomic layer deposition was performed once on the obtained inorganic hierarchical porous fiber membrane to obtain a multifunctional fiber membrane. The content of Pt element in the multifunctional fiber membrane was 0.2 wt.%. Example 5

[0051] (1) Preparation of spinning solution: Add 2 g of polyvinylpyrrolidone to a mixed solvent of 10 g of ethanol and 2 g of acetic acid. After complete dissolution, add 5.0 g of tetrabutyl titanate and 1.0 g of tetraethyl orthosilicate in sequence. Stir evenly to form a precursor solution.

[0052] (2) Preparation of precursor fiber membrane by electrospinning: The spinning solution was placed in an electrospinning apparatus for spinning. The conditions were set as follows: nozzle inner diameter of 1.15 mm, spinning solution flow rate of 5 mL / h, voltage of 30 kV, and distance between the collecting roller and the nozzle of 20 cm. The collected fiber membrane was dried at 60 °C to remove excess solvent, and the precursor fiber membrane was obtained.

[0053] (3) Calcination: The precursor fiber membrane was calcined at 800 °C for 1 h with a heating rate of 10 °C / min to obtain an inorganic hierarchical porous fiber membrane.

[0054] (4) Atomic layer deposition: Using dinitrodiammineplatinum as a precursor, atomic layer deposition was performed on the obtained inorganic hierarchical porous fiber membrane for 5 cycles to obtain a multifunctional fiber membrane. The content of Pt element in the multifunctional fiber membrane was 1.0 wt.%.

[0055] Comparative Example 1 The difference between this embodiment and Embodiment 1 is that atomic layer deposition is not performed; the remaining steps are the same as in Embodiment 1.

[0056] Testing showed that the prepared multifunctional fiber membrane achieved a PM0.3 filtration efficiency of 99.80%, a pressure drop of 56.0 Pa, and a quality factor of 0.111 Pa. -1 It can meet the requirements of high-efficiency, low-resistance filtration of easily escaped particulate matter such as PM0.3 in indoor air.

[0057] Testing showed that the prepared inorganic hierarchical porous fiber membrane, at 120 L·g -1 ·h -1 At a space velocity of 1000 h⁻¹, the room temperature catalytic efficiency for formaldehyde at a concentration of 2 ppm was 22.9%. Compared with the multifunctional fiber membrane with Pt clusters deposited by atomic layer deposition, the inorganic hierarchical porous fiber membrane exhibited very low formaldehyde catalytic activity, indicating that the highly dispersed Pt clusters deposited by atomic layer deposition endow the multifunctional fiber membrane with excellent catalytic performance.

[0058] Comparative Example 2 The difference between this embodiment and Embodiment 1 is that electrospinning is not performed. The spinning solution is directly dried and calcined to obtain a powder sample, which is then subjected to atomic layer deposition. The remaining steps are the same as in Embodiment 1.

[0059] Testing revealed that the prepared powder sample did not have a hierarchical porous structure.

[0060] Testing revealed that the powdered catalyst prepared via atomic layer deposition exhibited a yield of 120 L·g. -1 ·h -1 At a space velocity of [value missing], the room-temperature catalytic efficiency for formaldehyde at a concentration of 2 ppm was 85.6%. Compared with the multifunctional fiber membrane with Pt atomic layer deposition, the formaldehyde catalytic activity of the powder catalyst was insufficient. This may be due to the particle growth caused by the unrestricted growth of Pt and the lack of confinement enhancement effect during the catalytic process. This indicates that the hierarchical porous structure plays an important role in the Pt particle formation process and the catalytic process.

[0061] Comparative Example 3 The difference between this embodiment and Embodiment 1 is that, after obtaining the inorganic hierarchical porous fiber membrane, atomic layer deposition is not performed. Instead, it is impregnated and reduced in an aqueous solution containing chloroplatinic acid, and the content of the loaded Pt element is 1.0 wt.%. The remaining steps are the same as in Embodiment 1.

[0062] The prepared multifunctional fiber membrane was tested and found to have a performance of 120 L·g -1 ·h -1 At a space velocity of 1000 h⁻¹, the room-temperature catalytic efficiency for formaldehyde at a concentration of 2 ppm was 36.2%. This indicates that the supported Pt particles have the ability to catalyze the removal of formaldehyde. However, compared to the Pt clusters formed by atomic layer deposition (ALD), the Pt clusters exhibit significantly higher catalytic activity. Therefore, the multifunctional fiber membrane prepared by ALD modification possesses superior performance.

Claims

1. A method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion, characterized in that: Polyvinylpyrrolidone, titanium dioxide precursor, and silicon dioxide precursor were sequentially added to a solvent and mixed to prepare a spinning solution. After electrospinning and calcination, an inorganic hierarchical porous fiber membrane was obtained. Then, Pt clusters were deposited on the inorganic hierarchical porous fiber membrane to obtain a multifunctional fiber membrane based on hierarchical pore confinement dispersion.

2. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The inorganic hierarchical porous fiber membrane is composed of titanium dioxide and silicon dioxide.

3. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The silicon oxide precursor includes one or more of tetramethyl silicate and tetraethyl orthosilicate; the titanium oxide precursor is tetrabutyl titanate.

4. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The solvents are ethanol and acetic acid; in the spinning solution, the contents of polyvinylpyrrolidone, titanium dioxide precursor, silicon dioxide precursor, ethanol and acetic acid are 10 wt.%, 5~25 wt.%, 5~25 wt.%, 50 wt.%, and 10 wt.%, respectively.

5. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The conditions for electrospinning are: spinning voltage 10~30 kV, nozzle inner diameter 0.50~1.55 mm, spinning solution flow rate 1~10 mL / h, and distance between nozzle and receiving roller 10~20 cm.

6. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The calcination conditions are as follows: the calcination atmosphere is air, the heating rate is 1~10 °C / min, the calcination temperature is 500~800 °C, and the holding time is 1~3 h.

7. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The inorganic multi-level porous fiber membrane has two types of pore structures: (1) micropores and mesopores on the fibers; and (2) macropores formed by the interfibers.

8. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The Pt precursors used in atomic layer deposition include one or more of trimethyl(methylcyclopentadienyl)platinum, platinum acetylacetonate, and dinitrodiammineplatinum.

9. The method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The atomic layer deposition cycle is 1 to 10 times.

10. A method for preparing a multifunctional fiber membrane based on hierarchical pore confined dispersion according to claim 1, characterized in that: The content of Pt element in the multifunctional fiber membrane is 0.2~2.0 wt.%.

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