Pt (at) ZrO2 (at) SiO2 catalytic ceramic membrane with core-shell structure as well as preparation method and application of Pt (at) ZrO2 (at) SiO2 catalytic ceramic membrane
By preparing a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane, the problems of easy loss of platinum-based catalysts and easy fouling of ceramic membranes were solved, achieving efficient simultaneous catalytic ozone oxidation and separation, and improving the treatment efficiency of recalcitrant wastewater.
Patent Information
- Application Number
- CN202511823260.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-02-17
AI Technical Summary
In existing technologies, platinum-based catalysts are expensive and nanoparticles are prone to aggregation and loss. Traditional ceramic membranes are ineffective at removing soluble small molecules and are easily contaminated. The weak bonding between the catalyst and the membrane leads to low catalytic ozone oxidation efficiency and many byproducts.
A core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane was used. Platinum nanosol was prepared by ethylene glycol reduction, ZrO2 shell was deposited by hydrolysis, SiO2 shell was coated by Stöber method, and calcination was performed to form a uniformly loaded α-Al2O3 flat plate membrane, achieving simultaneous catalysis and separation.
It improves catalytic activity and stability, reduces bromate formation, enhances the degradation efficiency of algal toxins and organic matter, maintains high throughput and long-term operational stability, and is suitable for large-scale production.
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Figure CN121534702A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of advanced oxidation and water treatment technology. Specifically, it relates to a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane and its preparation method, as well as its application in the deep treatment of algae-containing water and recalcitrant organic wastewater. Background Technology
[0002] Ozone oxidation technology is one of the effective methods for treating recalcitrant organic wastewater. However, ozone itself has high selectivity, and its direct oxidation efficiency for substances such as algal cells and algal toxins is limited. Furthermore, it suffers from low ozone utilization and the easy generation of byproducts such as bromate. Catalytic ozone technology (catalytic ozone oxidation technology) effectively solves these problems by converting ozone into hydroxyl radicals (·OH) through a catalyst. Among these, platinum (Pt)-based catalysts are among the most active known catalysts, but their high cost, easy agglomeration and loss of nanoparticles, and difficulty in recovery limit their large-scale application.
[0003] Ceramic membrane separation technology, as a highly efficient physical separation method, has been widely used in water treatment. However, traditional ceramic membranes mainly function as sieving membranes, exhibiting poor removal efficiency for dissolved small-molecule organic matter and suffering from severe membrane fouling. Current research has attempted to load catalysts onto the membrane surface, but this typically employs a simple impregnation coating method. This results in weak catalyst-membrane bonding, easy detachment, insufficient exposure of active sites, and severe clogging of the membrane pores by the catalyst layer, leading to a sharp decline in flux.
[0004] Therefore, developing a composite material that combines high catalytic activity, high stability, and the ability to simultaneously achieve efficient separation and catalytic oxidation has become a pressing technical challenge in this field. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing a catalytic ceramic membrane with a core-shell structured Pt@ZrO2@SiO2 active layer. This preparation method is simple, and the resulting product exhibits high catalytic activity, good stability, and high membrane flux. Another objective of this invention is to provide the application of the above-mentioned catalytic ceramic membrane in the deep treatment of algae-containing water and recalcitrant organic wastewater using catalytic ozone.
[0006] To address the aforementioned technical problems, the present invention adopts the following technical solution: The purpose of this invention is to provide a method for preparing a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane, comprising the following steps: Step 1: Platinum nanosols were prepared by ethylene glycol reduction using chloroplatinic acid (H2PtC6·6H2O) as the platinum source and polyvinylpyrrolidone (PVP) as the protective agent. Step 2: Under stirring conditions, platinum nanosol is added to zirconium oxynitrate solution, and then the pH value is adjusted to 9-11. Zr(OH)4 is deposited on the surface of platinum particles through hydrolysis reaction, followed by hydrothermal crystallization to obtain Pt@ZrO2 core-shell particles coated with tetragonal ZrO2. Step 3: Then disperse in an ethanol-water solution to obtain suspension A, then add tetraethyl orthosilicate (TEOS), using hexadecyltrimethylammonium bromide (CTAB) as a template agent and ammonia as a catalyst, and coat the porous SiO2 shell using the Stöber method, then calcine to remove the template agent to form Pt@ZrO2@SiO2 core-shell particles; Step 4: Disperse Pt@ZrO2@SiO2 core-shell particles uniformly in anhydrous ethanol to obtain suspension B. Then, immerse a commercial α-Al2O3 flat sheet membrane in suspension B, remove it, dry it, and sinter it in an air atmosphere to obtain a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane.
[0007] Furthermore, the particle size of the platinum nanosol prepared in step 1 is 2 nm to 5 nm.
[0008] Further specifying, in step 2, the concentration of the zirconium oxynitrate solution is 5 g / L to 10 g / L.
[0009] Further specifying, in step 2, the mass ratio of platinum nanosol to the volume ratio of zirconium oxynitrate solution is (1-3) mg:1 mL.
[0010] To further specify, in step 2, the pH value is adjusted using ammonia.
[0011] Further specifying, in step 2, the hydrolysis reaction takes place at 50℃~60℃. Further specifying, in step 2, hydrothermal crystallization is performed at 80℃~120℃.
[0012] Further specifying, the thickness of the ZrO2 shell obtained in step 2 is 5nm to 20nm.
[0013] Furthermore, in step 3, the ethanol-water solution is prepared by mixing anhydrous ethanol and deionized water in a volume ratio of 9:1. Further specifying, in step 3, the concentration of the ZrO2-coated Pt@ZrO2 core-shell particles is 5 mg / mL to 10 mg / mL.
[0014] Further specifying, in step 3, the amount of tetraethyl orthosilicate used is 5% to 8% of the volume of suspension A.
[0015] Further specifying, in step 3, the amount of CTAB used is 25% of the mass of the Pt@ZrO2 core-shell particles.
[0016] Further specifying, in step 3, the amount of ammonia used is 5% of the volume of suspension A, and the concentration of ammonia is 25wt%-28wt%.
[0017] Further specifying, in step 3, the reaction temperature of the Stöber process is 25℃~30℃, and the reaction time is 6h~8h.
[0018] Further specifying, the thickness of the SiO2 shell obtained in step 3 is 20 nm to 100 nm.
[0019] Further specifying, in step 3, the roasting is carried out at 400℃~600℃.
[0020] Further specifying, in step 4, the solid content of suspension B is 5wt% to 20wt%.
[0021] Further specifying, in step 4, sintering is performed at 1000℃~1200℃.
[0022] Another objective of this invention is to provide a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane prepared by any of the above methods, with a membrane thickness of 5 μm to 50 μm, an average pore size of 10 nm to 100 nm, and a pure water flux of up to 350 L / (m²). 2 ·h·bar).
[0023] Another objective of this invention is to provide a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane prepared by any of the above methods for treating algae-containing water and recalcitrant organic wastewater. The catalytic ceramic membrane is placed in a membrane reactor, and the water to be treated and ozone enter together from one side of the membrane element. Under pressure, water molecules penetrate the catalytic layer for filtration and separation, while ozone is efficiently catalytically decomposed into ·OH upon penetrating the catalytic layer, resulting in immediate and efficient oxidative degradation of algae and organic matter on the membrane surface and within the membrane pores.
[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention organically combines the catalytic functional unit with the membrane separation functional unit, realizing the simultaneous occurrence of the reaction and separation processes, thereby simplifying the overall process flow and improving the processing efficiency.
[0025] The composite membrane exhibits excellent catalytic activity and long-term operational stability, which is mainly due to its unique core-shell structure design: the ZrO2 shell can effectively prevent the internal Pt core from sintering, agglomerating or being lost during high-temperature calcination and use.
[0026] Highly active metallic Pt with strong bond to the support was formed through a one-step in-situ reduction method. 0Meanwhile, the ZrO2 shell itself also possesses ozone catalytic activity, which synergistically promotes the generation of hydroxyl radicals (·OH) with the Pt core. The generated ·OH can immediately oxidize and degrade organic matter and microbial cells accumulated on the membrane surface and in the membrane pores, thereby alleviating membrane fouling at its source and maintaining long-term stability of membrane flux.
[0027] Furthermore, the highly efficient ozone catalytic decomposition reduces the opportunity for ozone to come into contact with bromide ions in water, thereby effectively inhibiting the formation of the carcinogen bromate. Moreover, under the same Pt loading, the catalytic membrane of this invention demonstrates improved degradation of typical recalcitrant pollutants such as algal toxins and odor-causing substances compared to the traditional impregnation method. In terms of preparation method, the core-shell structure catalyst layer was uniformly and firmly loaded on the complex porous α-Al2O3 flat plate membrane substrate by means of "dynamic coating" and "one-step calcination-reduction" process. The process is simple and suitable for large-scale production. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of the structure of the catalytic ceramic membrane of the present invention; Figure 2 This is a scanning electron microscope (SEM) image of the core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane prepared in Example 1 of this invention; Figure 3 This is a process flow diagram of the catalytic ceramic membrane described in this invention for treating algae-containing water in a catalytic ozone membrane reactor; Figure 4 This is a comparison of the pure water flux of the catalytic ceramic membrane described in this invention and a commercial membrane; Figure 5 This is a comparison graph showing the change in membrane flux over time when treating algae-containing water in the comparative example and embodiment of the present invention. Detailed Implementation
[0029] The present invention will be described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but should not be considered as limiting the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.
[0030] Example 1: The preparation method of the core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane in this example is carried out according to the following steps: Step 1: Using chloroplatinic acid (H2PtC6·6H2O) as the platinum source and polyvinylpyrrolidone (PVP) as the protective agent, Pt nanosols with an average particle size of 3 nm were prepared by ethylene glycol reduction. The specific steps are as follows: 0.50 g of chloroplatinic acid hexahydrate (H2PtCl6·6H2O, Pt content 37.5%) and 1.0 g of polyvinylpyrrolidone were dissolved together in 100 mL of ethylene glycol to form a mixed solution. Under the protection of argon atmosphere, the mixed solution was heated to 150 °C for reflux reaction to reduce the platinum precursor and obtain the platinum nanosol.
[0031] Step 2: Take 100 mL of platinum nanosol obtained in Step 1 and add it to 200 mL of 7.0 g / L zirconium oxynitrate (ZrO(NO3)2) solution. Adjust the pH of the system to 10.0±0.2 with 28 wt% ammonia water. Perform hydrolysis reaction in a 55℃ water bath with stirring for 2 hours to deposit Zr(OH)4 on the surface of platinum particles. After the reaction is completed, transfer the suspension to a 250 mL polytetrafluoroethylene-lined hydrothermal reactor and perform hydrothermal crystallization at 100℃ for 12 hours. After natural cooling, centrifugation (8000 rpm, 10 min), washing with deionized water 3 times, and drying at 80℃ overnight, Pt@ZrO2 core-shell particles coated with tetragonal ZrO2 (ZrO2 shell thickness 10-12 nm) are obtained.
[0032] Step 3: 1.0 g of ZrO2-coated Pt@ZrO2 core-shell particles were ultrasonically dispersed in a mixed solution of 180 mL anhydrous ethanol and 20 mL deionized water. 0.25 g of cetyltrimethylammonium bromide (CTAB) and 12.0 mL of tetraethyl orthosilicate (TEOS) were added, along with 10.0 mL of 28 wt% ammonia water as a catalyst. The mixture was dried at 60 °C for 12 h, and then placed in a muffle furnace and heated to 550 °C at 2 °C / min for 4 h to remove the CTAB template agent, yielding Pt@ZrO2@SiO2 double-shell core-shell particles (thickness 45–55 nm). Step 4: 2.0 g of Pt@ZrO2@SiO2 core-shell particles were uniformly dispersed in 18.0 g of anhydrous ethanol and ultrasonically dispersed for 30 min to prepare a uniform suspension with a solid content of 10 wt%. A commercial α-A2O3 flat sheet membrane was then immersed in this suspension, removed, dried at 100 °C, and sintered at 1200 °C in air for 4 h to obtain a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane. The obtained membrane thickness was 18 μm–22 μm, the average pore size was 50 nm–70 nm, and the pure water flux was 350 L / (m²). 2 ·h·bar).
[0033] Application testing: The prepared catalytic ceramic membrane was assembled into a dead-end filtration device. A mixture containing *Microcystis aeruginosa* (1×10⁻⁶) was prepared. 6Simulated algal water (cells / mL) was prepared and ozone (dosage 1.0 mg / L) was simultaneously introduced. The system was operated at 400 kPa. Results showed that the algal cell removal rate was >99.8% within 30 minutes, the membrane flux remained above 70% of the initial flux, and the concentrations of microcystin LR and bromate in the effluent were both below the detection limit.
[0034] Comparative Example 1: Pt was loaded onto a commercial Al2O3 ceramic membrane using a conventional impregnation method. Under the same application test conditions, the membrane flux decreased to 20% of the initial flux within 30 minutes, and significant Pt loss was detected in the operating solution.
[0035] Depend on Figure 2 The scanning electron microscope (SEM) images and corresponding energy-dispersive X-ray spectroscopy (EDS) elemental distribution maps of the Pt@ZrO2@SiO2 core-shell particles prepared in Example 1 are shown. The SEM images reveal that the particles are regularly spherical with uniform size, good dispersion, and smooth surfaces without significant agglomeration. The EDS results show that O and Si elements are highly overlapping and uniformly distributed throughout the outer layer of the particles, indicating a continuous and complete SiO2 shell. Zr elements exhibit a distinct ring-like distribution, located in the central region of the particles, forming an intermediate shell approximately 20 nm thick. Pt elements are concentrated only in the core region of the particles, indicating that the Pt nanonucleus is completely and tightly encapsulated by the ZrO2 and SiO2 double shells, without exposure or migration. These results fully demonstrate that the present invention successfully constructed a clear Pt (core)@ZrO2 (inner shell)@SiO2 (outer shell) core-shell structure.
[0036] Depend on Figure 4 It can be seen that, under the test conditions of 4.0 bar transmembrane pressure difference and deionized water, the pure water flux of the core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane is not significantly different from that of the commercial α-Al2O3 ceramic membrane. After coating with the core-shell structured catalytic layer, the pure water flux of the membrane remains at 350 L·m. -2 ·h -1 ·bar -1 The high level of this invention fully demonstrates that the outer porous SiO2 shell possesses both a high specific surface area and an excellent through-pore structure, which, while imparting catalytic function, maximizes the preservation of the membrane's high-flux characteristics and fully meets the requirements for continuous industrial operation.
[0037] Depend on Figure 5 It can be seen that the Pt@ZrO2@SiO2 catalytic ceramic membrane exhibits superior anti-fouling ability when combined with ozone, and is effective in treating water containing algae (Microcystis aeruginosa, cell concentration 1×10⁻⁶). 6When the flux is at a concentration of (cells / mL), under ozone-free conditions, viscous substances such as algal cells, extracellular polymers (AOM), proteins, and polysaccharides rapidly adsorb and deposit on the membrane surface and within the pores, forming a dense algal cake layer and gel layer. The flux rapidly decreases to 30% of the initial value, representing a typical case of severe biofouling. When combined with ozone, the catalytic ceramic membrane of this invention generates a large amount of strong oxidizing species such as ·OH in situ on the surface. This can completely mineralize the adsorbed algal cells and AOM into CO2, H2O, and small molecule acids within <0.1 s, with almost no secondary cake layer formation. The final relative flux stabilizes at 0.86 (i.e., a decrease of only 14%), which is 2.87 times that of the ozone-free group, and the antifouling ability is improved by nearly 3 times. These results indicate that the Pt@ZrO2@SiO2 core-shell structure catalytic ceramic membrane of this invention, when combined with ozone, is not only suitable for high-concentration industrial wastewater but also highly efficient for emergency treatment of algae-containing surface water and deep purification of drinking water, demonstrating strong environmental adaptability and industrial application value.
[0038] The specific embodiments of the present invention have been described in detail above. It should be noted that the present invention is not limited to the specific embodiments described above. Various modifications or alterations can be made by those skilled in the art without departing from the scope of protection defined by the claims, and all such modifications or alterations fall within the scope of the present invention.
Claims
1. A method for preparing a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane, characterized in that, Includes the following steps: Step 1: Platinum nanosols were prepared by ethylene glycol reduction using chloroplatinic acid as the platinum source and polyvinylpyrrolidone as the protective agent. Step 2: Under stirring conditions, platinum nanosol is added to zirconium oxynitrate solution, and then the pH value is adjusted to 9-11. Zr(OH)4 is deposited on the surface of platinum particles through hydrolysis reaction, followed by hydrothermal crystallization to obtain Pt@ZrO2 core-shell particles coated with tetragonal ZrO2. Step 3: Then disperse in an ethanol-water solution to obtain suspension A, then add tetraethyl orthosilicate (TEOS), using hexadecyltrimethylammonium bromide (CTAB) as a template agent and ammonia as a catalyst, and coat the porous SiO2 shell using the Stöber method, then calcine to remove the template agent to form Pt@ZrO2@SiO2 core-shell particles; Step 4: Disperse Pt@ZrO2@SiO2 core-shell particles uniformly in anhydrous ethanol to obtain suspension B. Then, immerse a commercial α-Al2O3 flat sheet membrane in the suspension, remove it, dry it, and sinter it in an air atmosphere to obtain a core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane.
2. The method according to claim 1, characterized in that, The particle size of platinum nanosol is 2nm to 5nm.
3. The method according to claim 1, characterized in that, The concentration of the zirconium oxynitrate solution is 5 g / L to 10 g / L, and the mass ratio of platinum nanosol to the volume of zirconium oxynitrate solution is (1-3) mg: 1 mL.
4. The method according to claim 1, characterized in that, The pH value is adjusted with ammonia water, hydrolysis reaction is carried out at 50℃~60℃, and hydrothermal crystallization is carried out at 80℃~120℃, with a ZrO2 shell thickness of 5nm~20nm.
5. The method according to claim 1, characterized in that, The ethanol-water solution was prepared by mixing anhydrous ethanol and deionized water in a volume ratio of 9:
1. The concentration of the ZrO2-coated Pt@ZrO2 core-shell particles was 5 mg / mL to 10 mg / mL. The amount of tetraethyl orthosilicate was 5% to 8% of the volume of suspension A. The amount of CTAB was 25% of the mass of the Pt@ZrO2 core-shell particles. The amount of ammonia was 5% of the volume of suspension A, and the concentration of ammonia was 25 wt% to 28 wt%.
6. The method according to claim 1, characterized in that, The reaction temperature of the Stöber process is 25℃~30℃, and the reaction time is 6h~8h; the SiO2 shell thickness is 20nm~100nm.
7. The method according to claim 1, characterized in that, Calcination at 400℃~600℃.
8. The method according to claim 1, characterized in that, The solid content of suspension B is 5wt% to 20wt%, and it is sintered at 1000℃ to 1200℃.
9. A core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane prepared by any method according to claims 1-8, characterized in that, Membrane thickness 5μm~50μm, average pore size 10nm~100nm, pure water flux up to 350 L / (m 2 ·h·bar).
10. A core-shell structured Pt@ZrO2@SiO2 catalytic ceramic membrane prepared by any of the methods in claims 1-8 for treating algae-containing water and recalcitrant organic wastewater.