Preparation method for high-flux gas-solid separation ceramic membrane based on phase inversion method

Abstract

A preparation method for a high-flux gas-solid separation ceramic membrane based on a phase inversion method, comprising: mixing and stirring ceramic powder, a polymer, a non-solvent additive, a surfactant, and a polar solvent to prepare a membrane preparation solution, carrying out ball milling, ultrasonic treatment and precipitation, carrying out blade coating on a glass plate, soaking in pure water to obtain a ceramic green body, and calcining to obtain a high-flux ceramic membrane.

Description

A method for preparing high-throughput gas-solid separation ceramic membrane based on phase inversion method Technical Field

[0001] The invention relates to a method for preparing a high-flux gas-solid separation ceramic membrane based on a phase conversion method, and belongs to the field of preparation of ceramic membrane materials. Background Art

[0002] In recent years, industrial production processes such as petroleum and chemical industries have generated large quantities of high-temperature, dusty flue gases. Directly released into the air, these gases can easily cause smog and respiratory illnesses, significantly impacting the ecological environment and human health. Compared to other dust removal technologies, membrane separation technology has become the preferred method for purifying high-temperature, dusty flue gases due to its high interception efficiency, ease of operation, low energy consumption, and zero pollution. Among various membrane materials, ceramic membranes show great potential in gas-solid separation due to their high mechanical strength, excellent thermal shock resistance, and long service life.

[0003] Traditional ceramic membranes are prepared using a multi-layer sintering process, and the prepared membrane has an asymmetric multi-layer structure, which is usually composed of a large-pore support layer with high mechanical strength, a slightly larger-pore transition layer to prevent infiltration of membrane particles, and a small-pore separation layer with high separation efficiency. This process has high sintering energy consumption and a long preparation time, which is too expensive for the treatment of high-temperature dust-laden gases. In addition, the porosity of the prepared ceramic membrane is low, usually 30%-40% [Ceram Int, 2021, 47(11): 14966-14987]. There is a high mass transfer resistance in the gas-solid separation process, resulting in low gas flux. Therefore, how to reduce the preparation cost of ceramic membranes and increase the porosity of ceramic membranes is of great significance to improving their competitiveness in practical applications of gas-solid separation.

[0004] In order to improve the porosity of ceramic membranes, researchers have adopted a variety of improved methods to further optimize the membrane preparation process. Currently, the mature preparation methods mainly include the addition of pore-forming agents and freeze-drying. Cheng et al. [Ceramics International, 2020, 46(8): 11297-11303] used carbon black, sawdust and hydroxyethyl cellulose (HEC) as composite pore-forming agents to prepare alumina porous ceramics and investigated the effect of the amount of pore-forming agent added on the porosity. The results showed that when sintered at 1500°C, the porosity of the alumina porous ceramics prepared when the pore-forming agent addition was 18wt% was the highest, about 47.7%. Bakkar et al. [Ceramics International, 2020, 46(5), 6038-6043] used tert-butanol as a solvent, froze the prepared ceramic solution in liquid nitrogen for 20-60 minutes, and then freeze-dried it at -86°C to sublimate the tert-butanol ice crystals. Finally, sintering was performed to obtain zirconia porous ceramics with a porosity of 72%-76%. Although these preparation methods effectively improve the porosity of the membrane, they usually have high equipment requirements and are difficult to control the costs of pore-forming materials and freeze-drying equipment.

[0005] Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing technologies by proposing a high-flux ceramic membrane based on a phase inversion method, significantly reducing production costs and improving production efficiency. Furthermore, by controlling the types and amounts of ceramic powder, polymer, non-solvent additive, surfactant, and polar solvent, the porosity and pore size of the ceramic membrane can be adjusted, thereby improving the gas permeability and dust filtration performance of the ceramic membrane for application in gas-solid separation.

[0007] The technical solution of the present invention is: a method for preparing a high-throughput gas-solid separation ceramic membrane based on a phase inversion method, the specific steps of which are as follows: A. At a certain temperature, a polymer, a non-solvent additive, a surfactant, and a ceramic powder of a certain particle size are added to a polar solvent N-methylpyrrolidone (NMP) in a certain mass ratio and stirred evenly to obtain a membrane-forming solution; the polymer is one of polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polysulfone (PSF); the non-solvent additive is one of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP); the surfactant is one of polysorbate (PS), sodium dodecyl sulfate (SDS), and cetyltrimethylammonium bromide (CTAB); the mass ratio of the polymer, non-solvent additive, surfactant, ceramic powder, and NMP is (4-6):1:(0.5-1.5):(20-45):(25-50). The membrane-forming solution is ball-milled for a period of time, and then subjected to sonication and precipitation to eliminate bubbles. B. Pour the defoamed film-forming liquid onto a clean, smooth glass plate and apply it with a scraper. Immediately soak the liquid in pure water. After a certain period of time, separate the solidified ceramic green body from the glass plate, dry it at room temperature for 4-12 hours, and then calcine it to obtain a ceramic membrane.

[0008] Preferably, the stirring temperature is 30-70°C.

[0009] Preferably, the particle size of the ceramic powder is 0.5-30 μm.

[0010] Preferably, the ceramic powder is one or more of ZrO2, Y2O3, Al2O3, SiO2, SiC, TiO2, Si3N4 or mullite.

[0011] Preferably, the stirring speed of the membrane-forming liquid is 500-1500 rpm, and the stirring time is 1-4 h.

[0012] Preferably, the ball milling time is 3-12 hours, the ultrasonic time is 0.5-3 hours, and the precipitation time is 1-3 hours.

[0013] Preferably, during the coating process, the distance between the bottom of the scraper and the substrate is 200-800 μm, the moving speed of the scraper is 1-50 mm / s, and the immersion time in pure water is 8-24 h.

[0014] Preferably, the calcination process is to calcine the green body at 1100-1800° C., control the heating rate and cooling rate at 0.5-3° C. / min, and hold the temperature for 1-3 hours.

[0015] The average pore size of the ceramic membrane prepared by the present invention is 0.13-2.74 μm, the porosity is 68.9%-89.2%, and the gas permeability is 923.6-1300.6 μm. 3 m-2 h -1 kPa -1 The filtration effect for dust with a diameter less than 0.3μm is greater than 99%. Beneficial effects

[0016] To date, research on ceramic membranes with finger-like structures prepared by phase inversion for use in gas-solid separation has been very limited. The present invention provides a method for preparing high-throughput ceramic membranes for gas-solid separation based on phase inversion. This method offers advantages such as a simple process flow, a short preparation cycle, high production efficiency, and low production costs.

[0017] The microstructure of the membrane prepared by the phase inversion method is closely related to the type and amount of ceramic powder, polymer, non-solvent additive, surfactant and polar solvent. Generally speaking, the smaller the particle size of the ceramic powder, the smaller the pore size of the ceramic membrane produced. The type of polymer plays a decisive role in the permeability and physicochemical stability of the membrane. Increasing the polymer content can increase the density of the membrane, while excessive content will lead to a sharp decrease in the membrane porosity. The non-solvent additives polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) in the membrane-forming solution are both hydrophilic non-solvent additives. Adding an appropriate amount of surfactant to the membrane-forming solution can promote the intrusion of water into the membrane-forming solution, thereby increasing the membrane pore size. The polar solvent leaches from the membrane-forming solution during the membrane formation process, and due to its high solubility in water, it acts as a pore-forming agent, thereby increasing the flux of the membrane.

[0018] By controlling the types and addition amounts of ceramic powders, polymers, non-solvent additives, surfactants, and polar solvents, the pore size and porosity of the ceramic membrane can be adjusted, and ceramic membranes with high porosity, good gas permeability, and excellent dust filtration performance can be prepared, providing a reference for the preparation of high-flux ceramic membranes for gas-solid separation.

[0019] The present invention discloses a method for preparing high-throughput gas-solid separation ceramic membranes based on a phase inversion process. Compared with other ceramic membrane preparation methods, this method offers a simple process flow, a short preparation cycle, and high production efficiency, significantly reducing the production cost of ceramic membranes. The method is also applicable to a wide range of ceramic materials. It can achieve uniform coating of large-area substrates in a short period of time, producing high-porosity ceramic membranes with nano- and micron-scale pores in a single step, enabling the large-scale preparation and application of high-throughput ceramic membrane materials in the field of gas-solid separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a macroscopic morphology of the ceramic green body prepared in Example 3.

[0021] FIG2 is a SEM image of the surface of the ceramic membrane prepared in Example 3.

[0022] FIG3 is a SEM image of a cross section of the ceramic membrane prepared in Example 3.

[0023] FIG4 is an XRD pattern of the ceramic membrane prepared in Example 3.

[0024] FIG5 is a graph showing the pore size distribution of the ceramic membrane prepared in Example 3. DETAILED DESCRIPTION

[0025] Example 1

[0026] At 30°C, polyethersulfone (PES), polyethylene glycol (PEG), polysorbate (PS), and 0.5μm ZrO2 powder were added to n-methylpyrrolidone (NMP) in a mass ratio of 4:1:0.5:20:25. The mixture was stirred at 500 rpm for 1 hour to obtain a film-forming solution. The film-forming solution was then ball-milled for 3 hours, ultrasonicated for 0.5 hours, and allowed to settle for 1 hour to eliminate bubbles. The debubbled film-forming solution was poured onto a clean, smooth glass plate and coated with a scraper. The distance between the scraper bottom and the substrate was 200μm, and the scraper was moved at a speed of 1mm / s. After coating, the ceramic membrane was immediately immersed in pure water. After 8 hours, the solidified ceramic green body was separated from the glass plate and dried at room temperature for 4 hours. Then, the temperature was increased to 1100℃ at a rate of 0.5℃ / min in air atmosphere and kept at this temperature for 1 hour. The average pore size of the prepared ceramic membrane was 0.13μm, the porosity was 84.2%, and the gas permeability was 1092.1m 3 m -2 h -1 kPa -1 The filtration effect for dust with a diameter less than 0.3μm is 99.98%.

[0027] Example 2

[0028] At 40°C, polyethersulfone (PES), polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), and 2μm TiO2 and ZrO2 powders were added to n-methylpyrrolidone (NMP) in a mass ratio of 4:1:1:25:35. The mixture was stirred at 800 rpm for 2 hours to obtain a film-forming solution. The solution was then ball-milled for 6 hours, ultrasonicated for 1 hour, and allowed to settle for 2 hours to eliminate bubbles. The debubbled film-forming solution was poured onto a clean, smooth glass plate and coated with a scraper. The distance between the scraper bottom and the substrate was 400μm, and the scraper was moved at a speed of 10 mm / s. After coating, the ceramic membrane was immediately immersed in pure water. After 12 hours, the solidified ceramic green body was separated from the glass plate and dried at room temperature for 8 hours. Then, the temperature was increased to 1500℃ at a rate of 1℃ / min in air atmosphere and kept at this temperature for 1.5 hours. The average pore size of the prepared ceramic membrane was 0.59μm, the porosity was 85.7%, and the gas permeability was 1250.4m 3 m -2 h -1 kPa -1 The filtration effect for dust with a diameter less than 0.3μm is 99.97%.

[0029] Example 3

[0030] At 50°C, polyvinylidene fluoride (PVDF), polyvinyl pyrrolidone (PVP), cetyltrimethylammonium bromide (CTAB), and 7μm SiC powder were added to n-methylpyrrolidone (NMP) in a mass ratio of 5:1:1:35:45. The mixture was stirred at 1200 rpm for 3 hours to prepare a film-forming solution. The solution was then ball-milled for 8 hours, ultrasonicated for 2 hours, and allowed to settle for 3 hours to eliminate bubbles. The debubbled film-forming solution was poured onto a clean, smooth glass plate and coated with a scraper. The distance between the scraper bottom and the substrate was 400μm, and the scraper was moved at a speed of 20mm / s. After coating, the ceramic membrane was immediately immersed in pure water. After 16 hours, the solidified ceramic green body was separated from the glass plate and dried at room temperature for 10 hours. Then, the temperature was increased to 1250℃ at a rate of 2℃ / min in air atmosphere and kept warm for 2 hours. The average pore size of the prepared ceramic membrane was 2.35μm, the porosity was 89.2%, and the gas permeability was 1300.6m 3 m -2 h -1 kPa -1 The filtration effect for dust with a diameter less than 0.3μm is 99.96%.

[0031] Table 1 compares the performance of the ceramic membrane prepared by the phase inversion method in Example 3 with that in the literature. Figure 1 is a macroscopic morphology of the circular ceramic green body prepared in Example 3. Figure 2 is a SEM image of the surface of the ceramic membrane prepared in Example 3. Figure 3 is a SEM image of the cross-section of the ceramic membrane prepared in Example 3. Figure 4 is an XRD pattern of the ceramic membrane prepared in Example 3. Figure 5 is a pore size distribution diagram of the ceramic membrane prepared in Example 3. As can be seen from the figure: the prepared ceramic membrane has a high porosity and a concentrated pore size distribution.

[0032] Example 4

[0033] At 70°C, polysulfone (PSF), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), and 10μm Al2O3 and TiO2 powders were added to n-methylpyrrolidone (NMP). The mass ratio of PSF, PEG, CTAB, Al2O3 and TiO2 powders to NMP was 6:1:1.5:45:50. The mixture was stirred at 1500 rpm for 4 hours to obtain a film-forming solution. The film-forming solution was then ball-milled for 12 hours, ultrasonicated for 3 hours, and allowed to settle for 3 hours to eliminate bubbles. The debubbled film-forming solution was poured onto a clean, smooth glass plate and coated with a scraper. The distance between the scraper bottom and the substrate was 800μm, and the scraper was moved at a speed of 50 mm / s. After coating, the ceramic membrane was immediately immersed in pure water. After 24 hours, the solidified ceramic green body was separated from the glass plate and dried at room temperature for 12 hours. Then, the temperature was increased to 1800℃ at a rate of 3℃ / min in air atmosphere and kept at this temperature for 3 hours. The average pore size of the prepared ceramic membrane was 2.74μm, the porosity was 68.9%, and the gas permeability was 923.6m 3 m -2 h -1 kPa -1 The filtration effect for dust with a diameter less than 0.3μm is 99.41%.

[0034] Table 1 is a comparison of the performance of the ceramic membrane prepared in Example 3 and the literature

Claims

1. A method for preparing a high-throughput gas-solid separation ceramic membrane based on the phase inversion method, characterized in that: The specific operation steps are as follows: A. At a certain temperature, a polymer, a non-solvent additive, a surfactant, and ceramic powder with a certain particle size are added to the polar solvent N-methylpyrrolidone (NMP) according to a certain mass ratio, and stirred evenly to obtain a film-forming solution; the polymer is one of polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polysulfone (PSF); the non-solvent additive is one of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP); the surfactant is one of polysorbate (PS), sodium dodecyl sulfate (SDS), and cetyltrimethylammonium bromide (CTAB); the mass ratio of the polymer, non-solvent additive, surfactant, ceramic powder, and NMP is (4-6):1:(0.5-1.5):(20-45):(25-50); the film-forming solution is ball-milled for a period of time, and then ultrasonicated and precipitated to remove bubbles; B. Pour the defoamed film-forming solution onto a clean and smooth glass plate, use a scraper for scraping, immediately immerse it in pure water after scraping, separate the cured green ceramic body from the glass plate after a certain time, dry it at room temperature for 4-12 h, and then obtain a ceramic membrane through a calcination process.

2. The method for preparing a high-flux gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, wherein: The stirring temperature in step A is 30-70 °C.

3. A method for preparing a high-throughput gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, characterized in that: The particle size of the ceramic powder in step A is 0.5-30 μm.

4. A method for preparing a high-flux gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, characterized in that: The type of the ceramic powder in step A is one or several of ZrO2, Y2O3, Al2O3, SiO2, SiC, TiO2, Si3N4, or mullite.

5. A method for preparing a high-throughput gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, characterized in that: The stirring speed of the film-forming solution in step A is 500-1500 rpm, and the stirring time is 1-4 h.

6. The method for preparing a high-throughput gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, characterized in that: The ball-milling time in step A is 3-12 h, the ultrasonic time is 0.5-3 h, and the precipitation time is 1-3 h.

7. A method for preparing a high-flux gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, characterized in that: During the scraping process in step B, the distance between the bottom of the scraper and the substrate is 200-800 μm, the moving speed of the scraper is 1-50 mm / s, and the immersion time in pure water is 8-24 h.

8. A method for preparing a high-throughput gas-solid separation ceramic membrane based on the phase inversion method according to claim 1, characterized in that: The calcination process in step B is to calcine the green body at 1100-1800 °C, control the heating rate and cooling rate at 0.5-3 °C / min, and the holding time is 1-3 h.

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